CA2332062A1 - Integral multi-material injection molding nozzle seal and tip - Google Patents
Integral multi-material injection molding nozzle seal and tip Download PDFInfo
- Publication number
- CA2332062A1 CA2332062A1 CA 2332062 CA2332062A CA2332062A1 CA 2332062 A1 CA2332062 A1 CA 2332062A1 CA 2332062 CA2332062 CA 2332062 CA 2332062 A CA2332062 A CA 2332062A CA 2332062 A1 CA2332062 A1 CA 2332062A1
- Authority
- CA
- Canada
- Prior art keywords
- tip
- injection molding
- molding nozzle
- nozzle
- removable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000463 material Substances 0.000 title claims abstract description 75
- 238000001746 injection moulding Methods 0.000 title claims abstract description 50
- 238000005219 brazing Methods 0.000 claims abstract description 28
- 238000007789 sealing Methods 0.000 claims description 11
- 239000012768 molten material Substances 0.000 claims description 4
- 239000000155 melt Substances 0.000 abstract description 10
- 239000004020 conductor Substances 0.000 abstract description 4
- 238000010276 construction Methods 0.000 abstract description 3
- 230000001737 promoting effect Effects 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 description 8
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 6
- DMFGNRRURHSENX-UHFFFAOYSA-N beryllium copper Chemical compound [Be].[Cu] DMFGNRRURHSENX-UHFFFAOYSA-N 0.000 description 6
- 238000012423 maintenance Methods 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 229910052719 titanium Inorganic materials 0.000 description 6
- 238000009826 distribution Methods 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 5
- 229910000881 Cu alloy Inorganic materials 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 229910000997 High-speed steel Inorganic materials 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 230000013011 mating Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003292 glue Substances 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- 230000008439 repair process Effects 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 206010013642 Drooling Diseases 0.000 description 1
- 208000008630 Sialorrhea Diseases 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000012778 molding material Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/28—Closure devices therefor
- B29C45/2806—Closure devices therefor consisting of needle valve systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/278—Nozzle tips
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C2045/2761—Seals between nozzle and mould or gate
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/278—Nozzle tips
- B29C2045/2787—Nozzle tips made of at least 2 different materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/28—Closure devices therefor
- B29C45/2806—Closure devices therefor consisting of needle valve systems
- B29C2045/2879—Back flow of material into nozzle channel
Abstract
The present invention provides an integral multi-material injection molding nozzle seal and tip. The inner tip member, through which the melt duct extends; is formed of either a highly thermally conductive material or hard material while the surrounding outer sleeve member, which contacts the cooled mold to provide a seal around the gate, is formed of a substantially less conductive material to avoid undue heat loss. The tip member and sleeve member are integrally attached, preferably by brazing, at an interface between the two portions. The integral construction facilitates easier removal of the seal and tip, thereby promoting a longer service life.
Description
Title: Integral Multi-Material Injection Molding Nozzle Seal and Tip FIELD OF THE INVENTION
This invention relates to injection molding and, in particular, to an integral multi-material nozzle seal and tip which is removably attachable to an injection molding nozzle.
BACKGROUND OF THE INVENTION
One piece nozzle seals and gate inserts for insertion in the front end of a heated nozzle are well known and have various configurations.
U.S. Patent No. 4,043,740 to Gellert shows a nozzle seal which fits into a matching seat in the front end of the nozzle and has a portion which tapers inwardly around the gate. U.S. Patent No. 4,981,431 to Schmidt discloses a nozzle seal having an outer sealing flange which is screwed into place in a seat in the front end of the heated nozzle. U.S. Patent No. 4,875,848 to Gellert describes a gate insert which screws into place and has an integral electrical heating element. U.S. Patent No. 5,028,227 to Gellert et al. shows a gate insert having a circumferential removal flange to permit it to be pried from the nozzle seat when removal is desired.
These nozzle seals, however, are unsatisfactory when molding materials having a narrow temperature window because heat transfer is slow along the nozzle seal and heat is lost to the surrounding cooled mold.
To combat this problem, U.S. Patent No. 5,299,928 to Gellert discloses the use of a two-piece nozzle insert, wherein an outer sealing piece is made of a material having relatively low thermal conductivity, such as titanium, and wherein an inner tip piece is made of a material having a relatively high thermal conductivity, such as beryllium copper, or a wear resistant material like tungsten carbide. This results in good heat transfer in the interior portion of the part, with an insulative effect being created by the exterior less conductive portion. However, because the inner tip piece must be made of a material such as beryllium copper or tungsten carbide, it cannot be easily and reliably threaded for attachment to the outer sealing piece of the two-piece seal. Consequently the inner tip portion is trapped in place between the seal and nozzle to hold the inner piece in place while the seal is installed in the nozzle. Typically, as shown in Gellert 5,299,928, this is achieved by providing the inner piece with an outwardly extending shoulder against which the outer piece can bear to securely retain the inner piece between the outer piece and the nozzle when the outer piece is threaded onto the nozzle.
This two-piece design, however, presents several problems not present with the one-piece gate seals. First and foremost among these is the difficulties which are experienced when the nozzle seal is to be removed. Periodic removal of the nozzle seal and tip is required for maintenance, replacement and resin colour changes. In use, however, heated melt often seeps in and around the junction of the nozzle and the inner piece of the removable nozzle seal. When cooled, this resin seepage acts like a glue to stick in the nozzle seal in the nozzle end. When the connector is unthreaded in single piece devices, the "glue" is broken, however, because the inner and outer pieces of the nozzle seal are unattached in two-piece nozzles seals like that of the Gellert '928, when the outer piece is unscrewed and removed from the nozzle, the inner piece remains stuck within the nozzle. The inner piece must then be dislodged from the nozzle by other means, such as by hitting or prying the inner piece to unstick it from its seat in the nozzle end. Invariably, whatever the technique for dislodging, additional wear and/or even outright damage to the inner piece results, shortening the life of the piece.
Other multi-piece designs are also known. United States Patents Nos. US,545,028 to Hume, 5,658,604 to Gellert and 6,089,468 to Bouti show various alternatives or improvements to the design of Gellert '928, but these also suffer from the same drawback, namely that the tip insert is not fixed to the nozzle seal, but rather trapped between the seal and the nozzle. Thus, these devices are still susceptible to having the tip remain stuck in the nozzle end when the seal is unscrewed and removed from the nozzle for maintenance, etc.
This invention relates to injection molding and, in particular, to an integral multi-material nozzle seal and tip which is removably attachable to an injection molding nozzle.
BACKGROUND OF THE INVENTION
One piece nozzle seals and gate inserts for insertion in the front end of a heated nozzle are well known and have various configurations.
U.S. Patent No. 4,043,740 to Gellert shows a nozzle seal which fits into a matching seat in the front end of the nozzle and has a portion which tapers inwardly around the gate. U.S. Patent No. 4,981,431 to Schmidt discloses a nozzle seal having an outer sealing flange which is screwed into place in a seat in the front end of the heated nozzle. U.S. Patent No. 4,875,848 to Gellert describes a gate insert which screws into place and has an integral electrical heating element. U.S. Patent No. 5,028,227 to Gellert et al. shows a gate insert having a circumferential removal flange to permit it to be pried from the nozzle seat when removal is desired.
These nozzle seals, however, are unsatisfactory when molding materials having a narrow temperature window because heat transfer is slow along the nozzle seal and heat is lost to the surrounding cooled mold.
To combat this problem, U.S. Patent No. 5,299,928 to Gellert discloses the use of a two-piece nozzle insert, wherein an outer sealing piece is made of a material having relatively low thermal conductivity, such as titanium, and wherein an inner tip piece is made of a material having a relatively high thermal conductivity, such as beryllium copper, or a wear resistant material like tungsten carbide. This results in good heat transfer in the interior portion of the part, with an insulative effect being created by the exterior less conductive portion. However, because the inner tip piece must be made of a material such as beryllium copper or tungsten carbide, it cannot be easily and reliably threaded for attachment to the outer sealing piece of the two-piece seal. Consequently the inner tip portion is trapped in place between the seal and nozzle to hold the inner piece in place while the seal is installed in the nozzle. Typically, as shown in Gellert 5,299,928, this is achieved by providing the inner piece with an outwardly extending shoulder against which the outer piece can bear to securely retain the inner piece between the outer piece and the nozzle when the outer piece is threaded onto the nozzle.
This two-piece design, however, presents several problems not present with the one-piece gate seals. First and foremost among these is the difficulties which are experienced when the nozzle seal is to be removed. Periodic removal of the nozzle seal and tip is required for maintenance, replacement and resin colour changes. In use, however, heated melt often seeps in and around the junction of the nozzle and the inner piece of the removable nozzle seal. When cooled, this resin seepage acts like a glue to stick in the nozzle seal in the nozzle end. When the connector is unthreaded in single piece devices, the "glue" is broken, however, because the inner and outer pieces of the nozzle seal are unattached in two-piece nozzles seals like that of the Gellert '928, when the outer piece is unscrewed and removed from the nozzle, the inner piece remains stuck within the nozzle. The inner piece must then be dislodged from the nozzle by other means, such as by hitting or prying the inner piece to unstick it from its seat in the nozzle end. Invariably, whatever the technique for dislodging, additional wear and/or even outright damage to the inner piece results, shortening the life of the piece.
Other multi-piece designs are also known. United States Patents Nos. US,545,028 to Hume, 5,658,604 to Gellert and 6,089,468 to Bouti show various alternatives or improvements to the design of Gellert '928, but these also suffer from the same drawback, namely that the tip insert is not fixed to the nozzle seal, but rather trapped between the seal and the nozzle. Thus, these devices are still susceptible to having the tip remain stuck in the nozzle end when the seal is unscrewed and removed from the nozzle for maintenance, etc.
Also similar to the Gellert '928 configuration is the removable nozzle tip and seal insert disclosed in US 5,208,052 to Schmidt. Here a beryllium copper tip is held in place between the nozzle and a titanium seal which is threaded to the nozzle. An insulative air space is further provided between the tip and the sleeve. A zero clearance fit exists between the tip and the sleeve in the cold condition so that, when the nozzle reaches operating temperature, the tip longitudinal growth caused by thermal expansion forces the sleeve outward and downward against the mold.
While apparently providing an improved means for sealing the mold gate, the insert of Schmidt also suffers from the limitations of the prior art discussed above, in that when the sleeve is removed for maintenance or replacement, the tip is susceptible to remaining stuck in the nozzle end because the tip and sleeve are unconnected. Thus, tip damage of the type already described may still result. A further disadvantage of the Schmidt design is that the nozzle tip and sleeve require extremely accurate machining to within tight tolerances to ensure that the zero clearance sealing mechanism of the invention is effective. Such accurate machining is time-consuming and expensive.
Another removable tip and gate configuration is provided by United States Patent No. 5,879,727 to Puri. Puri discloses providing an intermediate titanium or ceramic insulating element between a copper-alloy nozzle tip and a steel gate insert to thermally isolate the nozzle tip from the gate insert while permit a secure mechanically connection between the two.
The tip itself joins the assembly to the nozzle end, either removably, through the provision of threads, or integrally. As described above, however, the threading of the nozzle tip is undesirable where copper-alloy tips are used and impossible if a tungsten carbide tip insert is desired. Furthermore, the additional insulating sleeve of Puri is an additional element which must be accurately machined and maintained, thereby adding to both the initial cost and the maintenance demands on the operator.
US 4,004,871 to Hardy discloses a bi-material mold gate conduit for use in injection molding thermosetting resins. The Mold gate conduit has an inner tube welded or brazed to an outer sleeve-like body.
The outer sleeve is slidably received within and pinned between co-operating mold plate members, and an annular chamber for circulating coolant around the gate is provided between the outer sleeve and the inner tube. However, because the outer sleeve is only slidably received by the assembly, there is no secure attachment provided and, further, removal can be difficult because resin leakage can freeze the conduit to the assembly, making the unit just as susceptible to damage in removal as in those devices described above.
Accordingly, there is a need for an improved multi-material replaceable nozzle tip which is more easily removable and which is less susceptible to damage than the replace able nozzle tips of the prior art.
Further, there is a need for such tips which are more easily manufacturable and at a reduced cost.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a removable injection molding nozzle tip comprising a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member, and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, wherein said sleeve member is threadlessly integrally attached to said tip member at said interface.
In a second aspect, the present invention provides a removable injection molding nozzle tip comprising a tip member formed of a first material, said tip member having a rear end, a front end adapted to communicate with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and a substantially smooth outer surface extending around at least a portion of said tip member, and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a substantially smooth inner surface contacting at least a portion of said outer surface of said tip member to form a interface therebetween, said sleeve member being integrally attached to said tip member at said interface.
In a third aspect, the present invention provides an injection molding apparatus for forming a molded article, the apparatus comprising at least one mold cavity, said at least one mold cavity formed between at least one pair of mold plates, said at least one mold cavity having a mold gate for communicating with an interior of said at least one cavity, an injection molding nozzle having a body, an end, and at least one melt channel through said body, said injection molding nozzle connectable to a source of molten material and capable of feeding molten material from said source to said end through said at least one melt channel, and a nozzle tip removably mounted to said end of said injection molding nozzle, said nozzle tip having a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct communicating with said at least one melt channel and extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member, and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact one of said mold plates around said mold gate, a rear end adapted for removable attachment to said injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, said sleeve member being threadlessly integrally attached to said tip member at said interface.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example to the accompanying drawings showing articles made according to a preferred embodiment of the present invention, in which:
Figure 1 is a sectional view of an injection molding system incorporating a removable multi-material nozzle tip according to a preferred embodiment of the present invention;
Figure 2 is an enlarged sectional view of the nozzle tip of Figure 1;
Figure 3 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having no internal shoulder;
Figure 4 is an enlarged sectional view of a further alternate embodiment of the nozzle tip of Figure 1, having a tip of reduced size;
Figure 5 is an enlarged sectional view of a yet further alternate embodiment of the nozzle tip of Figure 1, having a two-piece seal portion;
Figure 6 is an enlarged sectional view of a still further alternate embodiment of the nozzle tip of Figure 1, having a two-piece tip portion;
Figure 7a is an enlarged sectional view of another alternate embodiment of the nozzle tip of Figure 1, having a wear-resistant tip;
Figure 7b is an enlarged sectional view of a second configuration of the embodiment of Figure 7a;
Figure 8a is an enlarged sectional view of yet another alternate embodiment of the nozzle tip of Figure 1, having an internal angled portion at an upper end thereof;
Figure 8b is a much enlarged sectional view of a portion of Figure 8a;
_7_ Figure 8c is an enlarged sectional view of a second configuration of the embodiment of Figure 8a, having an internal angled portion at a lower end thereof;
Figure 8d is a much enlarged sectional view of a portion of Figure 8c;
Figure 9 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having a two-channel tip;
Figure 10 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having alternate attachment means;
Figure 11 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having a further alternate attachment means;
Figure 12 is an enlarged sectional view of a portion of an injection molding system incorporating a replaceable integral nozzle tip according a second main embodiment of the present invention;
Figures 13a-13d are enlarged sectional views of alternate embodiments of the nozzle tip of Figure 12;
Figure 14 is a sectional view of a portion of an injection molding system incorporating a replaceable integral valve-gated nozzle tip according to the present invention;
Figure 15 is an enlarged sectional view of the nozzle tip of Figure 14;
Figure 16 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 14, having an internal shoulder; and Figure 17 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 14, having an integral construction.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A portion of a multi-cavity injection molding system or apparatus made in accordance with the present invention is shown in the Figures generally at M. Referring to Figure 1, apparatus M has a melt distribution manifold 10 interconnecting several heated nozzles 12 in a mold 14. While mold 14 usually has a greater number of plates depending upon the application, in this case a nozzle mold platen 15, cavity plate 16, a support plate 17, a back plate 18 and under cavity platen 19, which are secured together by bolts 20, are shown for ease of illustration. The melt distribution manifold 10 is heated by an integral electrical heating element 22 and mold 14 is cooled by pumping cooling water through cooling conduits 24. Melt distribution manifold 10 is mounted between cavity plate 16 and back plate 18 by a central locating ring 26 and insulative spacer members 28 which provide an insulative air space 30 between heated manifold 10 and surrounding mold 14.
A melt passage 32 extends from a central inlet 34 in a cylindrical inlet portion 36 of manifold 10 and branches outward in manifold 10 to convey heated melt through a central bore 38 in each of heated nozzles 12. Heated melt then flows through a melt duct 40 in an integral nozzle seal and tip 42 according to the present invention to a gate 44 extending through cavity plate 16 leading to a cavity 46. Each nozzle 12 has a rear end 48 which abuts against front face 50 of melt distribution manifold 10 and a front end 52 with a threaded seat 54 extending around central melt bore 38. An electrical heating element 56 extends in the nozzle 12 integrally around central melt bore 38 to an external terminal 58 to receive power through leads 60. Nozzle 12 is seated in a well 62 in cavity plate 16 with an insulative air space 68 between heated nozzle 12 and cooled mold 14.
Nozzles 12 are securely retained in wells 62 by bolts 74 which extend from manifold 10 into cavity plate 16.
Referring to Figure 2, integral nozzle seal and tip 42 has a tip member 76 integrally joined to a sleeve member 78. As will be described below, sleeve 78 performs a sealing function and a connecting function. Tip 76 has an outer surface 80, a rear end 82, and a front end 84 and melt duct 40 extending from rear end 82 to front end 84. Outer surface 80 has a substantially smooth (i.e. unthreaded) cylindrical portion 86 extending between a shoulder 88, which extends outwardly near the rear end 82, and _g_ a portion 90, which tapers inwardly to the front end 84. Sleeve 78 of integral nozzle seal and tip 42 has a rear end 92, a front end 94, and an inner surface 96 with a substantially smooth (i.e. unthreaded) cylindrical portion 98 which fits around the cylindrical portion 86 of the outer surface 80 of the tip 76. Tip 76 is integrally attached to sleeve 78 at an interface 100 where portion 86 of outer surface 80 and portion 98 of inner surface 96 contact one another, as will be described in more detail below. Sleeve 78 also has a hexagonal nut-shaped portion 102 extending between a rear portion 104 and a cylindrical front seal portion 106. Rear portion 104 is threaded and adapted to engage mating threads in seat 54 in front end 52 of nozzle 12.
Melt duct 40 through tip 76 of integral nozzle seal and tip 42 is aligned with central melt bore 38 through nozzle 12 and leads to an outlet 110 at front end 84 and is aligned with gate 44. The nut-shaped intermediate portion 102 extends outwardly into insulative air space 68 between front end 52 of the heated nozzle and cooled mold 14 and is engageable by a suitable tool to tighten integral nozzle seal and tip 42 in place or remove it for cleaning or replacement if necessary, as will be described further below. Sleeve 78 of integral nozzle seal and tip 42 extends forwardly towards gate 44 and seal portion 106 of sleeve 78 is in sealing contact with cylindrical surface 114 of opening 112 to prevent pressurized melt escaping into insulative air space 68.
Tip 76 may be made of a corrosion and wear resistant material such as tungsten carbide or may be a highly thermally conductive material such as beryllium copper (BeCu) or other copper alloys. Sleeve 78 of integral nozzle seal and tip 42, which is in contact with both heated nozzle and cooled mold 14, is made of a material which is less thermally conductive, and preferably much less thermally conductive, than the tip 76.
Materials such as a high speed steel, H13 stainless steel and titanium are preferred. Tip 76 is integrally attached to sleeve 78, preferably by nickel alloy brazing, along an interface 100.
Referring again to Figure 1, in use electrical power is applied to heating element 22 in manifold 10 and to heating elements 56 in nozzles 12 to heat them to an operating temperature. Pressurized melt is provided from a molding machine (not shown) to central inlet 34 of melt passage 32 according to a predetermined cycle. The melt flows through melt distribution manifold 10, nozzles 12, integral nozzle seal and tip 42 and gate 44 into cavity 46. After cavity 46 is filled and a suitable packing and cooling period has expired, the injection pressure is released and the melt conveying system is decompressed to avoid stringing through open gates 44. The mold 14 is then opened to eject the molded product. After ejection, mold 14 is closed and the cycle is repeated continuously with a cycle time dependent upon the size of cavities 46 and the type of material being molded. During this repetitious injection cycle, heat is continuously transferred by integral nozzle seal and tip 42 according to a predetermined thermodynamic cycle. The proximity of the cooled metal around cavity 46 and the uniform thin insulation provided between it and integral nozzle seal and tip 42 allows for controlled solidification of the sprue. During injection, the highly conductive tip 76 of integral nozzle seal and tip 42 helps to conduct excess heat which is generated by the friction of the melt flowing through the constricted area of gate 44 rearwardly to avoid stringing and drooling of the melt when the mold opens for ejection. After the melt has stopped flowing, solidification of melt in gate 44 is enhanced by the removal of excess friction heat through tip 76 of integral nozzle seal and tip 42.
Also, in use, integral nozzle seal and tip 42 is periodically removed for maintenance, repair or resin colour change. To do so, nozzle 12 is withdrawn from well 62 and hex-nut portion 102 of integral nozzle seal and tip 42 is engaged by a suitable tool permit integral nozzle seal and tip 42 to be threadingly removed from end 52 of nozzle 12. Since the nozzle seal of the present invention is integral, the nozzle seal is always removed in one piece from end 52 of nozzle 12. Unlike the prior art, due to its integral nature integral nozzle seal and tip 42 is not susceptible to having tip 76 remain stuck within nozzle 12 after sleeve 78 is removed. The thread-advancing action in unscrewing integral seal and tip 42 from nozzle 12 ensures that the integral seal and tip does not stick thereto.
As is known in the art, employing a highly conductive tip 76 with a sleeve 78 of lesser conductivity provides the combination of good conductivity along tip 76, to maintain a rapid thermodynamic cycle, and provides thermal separation via sleeve 78 to reduce heat lost to cooled mold 14. (A measure of insulation is also provided by a circumferential air space 120 provided between tip 76 and sleeve 78, which also partially fills with melt which solidifies to provide additional insulation.) According to the present invention, however, bonding tip 76 to sleeve 78 provides an nozzle seal integral unit which results in better performance and longevity, by reason of facilitating maintenance and tip change because removal of the threaded connector portion also intrinsically removes the tip portion as well from the nozzle seat, thereby removing the possibility that the tip will be independently stuck in the nozzle and thereby require additional effort to remove. In doing so, the present invention provides a tip which will not need to be subject to the physical abuse, as it were, the prior art nozzle tips are subject to in removal from a stuck condition in a nozzle. This permits the present invention to provide a nozzle seal unit with increased longevity and which facilitates easier nozzle seal removal overall.
Advantageously, the present invention also permits integral nozzle seal and tip 42 to be fabricated more simply because brazing tip 76 to sleeve 78 permits these components to be made within less strict tolerances than the prior art. Specifically, because an additional brazing material is added between tip 76 and sleeve 78 at interface 100, outer surface 80 and inner surface 96 do not necessarily have to be within the same strictness of tolerances as with the prior art, which typically requires a smooth, face-to-face contact at interface 100. Thus, the present invention provides a replaceable nozzle tip and seal which may be made more economically.
Referring to Figures 3-9, alternate embodiments of the nozzle tip of Figure 1, are shown. As most of the elements are the same as those described above, common elements are described and illustrated using the same reference numerals. Referring to Figure 3, in a first alternate embodiment, tip 76 and sleeve 78 are of roughly the same length and tip 76 resides completely within sleeve 78.
Referring to Figure 4, in an alternate embodiment of the nozzle tip of Figure 1, tip 76 is shorter than sleeve 78, and terminates at a shoulder 122. Melt duct 40 has two regions, namely a connector melt duct 40A and a tip melt duct 40B.
Referring to Figure 5, in a further alternate embodiment of the nozzle tip of Figure 1, sleeve assembly 130 comprises a seal member 132 and a connector member 134 integrally joined, preferably by brazing, along an interface 136. Seal member 132 is preferably made of a material having lower thermal conductivity, such as H13 stainless steel, high speed steel or titanium, while connector member 134 is more thermal conductive and made of BeCu or other alloys of copper.
Referring to Figure 6, in a further alternate embodiment of the nozzle tip of Figure 1, tip assembly 140 comprises a rear member 142 and a tip member 144 integrally joined, preferably by brazing, along an interface 146.
Referring to Figure 7a, in a further alternate embodiment of the nozzle tip of Figure 1, tip portion 150 comprises a body member 152 and a tip point 154 integrally joined, preferably by brazing, along an interface 156.
Body member 152 is preferably made of a material having high thermal conductivity, such as beryllium copper, and tip point 154 is made of a corrosion and wear resistant material such as tungsten carbide. Referring to Figure 7b, in an alternate configuration, a tip insert 154' is used, which is integrally joined, preferably by brazing, along an interface 156'. The brazing is preferably achieved with a brazing material having a substantially lower melt temperature than the brazing done at interface 100, such that tip insert 154' is removable without compromising the braze at interface 100.
Referring to Figure 8a, in another alternate embodiment nozzle tip of Figure 1, tip 76 and sleeve 78 have a mating angled section 160, near rear end 82 of tip 76, at which tip portion is slightly expanded in diameter.
This construction assists in the assembly of integral nozzle seal and tip 42 prior to the integral joining of tip 76 and sleeve 78. Referring to Figure 8b, alternately a mating angled section 162 may be provided near front end 94 of sleeve 78, at which tip 76 is slightly reduced in diameter.
Referring to Figure 9, in another alternate embodiment nozzle tip of Figure 1, tip 76 is a two-channel tip in which melt duct 40 terminates in two outlets 110a and 110b.
As one skilled in the art will appreciate, the replaceable integral nozzle seal and tip of the present invention is not limited to one in which nozzle seat 54 and seal rear portion 104 are threaded to one another.
Rather, other means of removably connecting integral nozzle seal and tip 42 to nozzle 12 may be employed. For example, rear portion 104 can be brazed to seat 54 using a second brazing material which has a melting temperature which is substantially lower than the brazing material used at interface 100, as disclosed in U.S. Patent No. 6,009,616 to Gellert, incorporated herein by reference. Referring to Figure 10, in one aspect tip 76 is integrally brazed to sleeve 78 along interface 100 using a first brazing material, as described above, to make integral nozzle seal and tip 42. The integral tip insert is then brazed to nozzle 12, along an interface 170, using a second brazing material which has a melting temperature preferably substantially below that of the first brazing material. This approach allows integral tip to be easily removed for replacement or repair by heating but does not affect the metallurgical bond at interface 100 during either installation or removal. Referring to Figure 11, in a second aspect, a combined attachment means for attaching integral nozzle seal and tip 42 to nozzle 12 is shown. In this aspect, integral nozzle seal and tip 42 is both threaded and brazed to nozzle 12. Rear portion 104 has threads for engaging seat 54, as described for the embodiments above, and is additionally brazed along interface 172 using a second brazing material which has a melting temperature preferably substantially below that of the first brazing material employed at interface 100.
Referring to Figure 12, in another embodiment of the present invention sleeve 78 is connected around and outside front end 52 of nozzle 12. Sleeve 78 has a threaded read end 104 which removably engages threads in seat 54 of nozzle 12. Tip 76 is integrally brazed to sleeve 78 at interface 100. Optionally, tip 76 may also be brazed directly to nozzle 12, along interface 180, using a second brazing material which has a melting temperature preferably substantially below that of the first brazing material employed at interface 100, in a process as disclosed in Gellert 6,009,616 and described above. The integral connection between tip 76 and sleeve 78, along interface 100 permits the integral nozzle seal and tip 42 to be removed as a single unit.
Figures 13a-13d disclose some of the many modifications possible to the Figure 12 embodiment of the present invention. In Figure 13a, the threaded connection between rear portion 104 and seat 54 is replaced by a braze along interface 182, this braze being of a second brazing material which has a melting temperature preferably substantially below that of the first brazing material employed at interface 100. Referring to Figure 13b, nozzle 12 may be provided with a band heater either in place of or conjunction with electrical heating element 56 (not seen in Figure 13b but shown in Figure 1). As shown in Figure 13c, electrical heating element 56 may extend to front end 52 of nozzle 12 and inside the portion of nozzle 12 surrounded by rear portion 104 of sleeve 78. Referring to Figure 13d, tip 76 may be a two-channel tip in which melt duct 40 terminates in two outlets 110a and 110b.
As one skilled in the art will appreciate, the replaceable integral nozzle seal and tip of the present invention is not limited to a torpedo style gating as described above. Referring to Figures 14-17, the present invention is shown in use in several a valve gating embodiments.
As most of the elements are the same as those described above, common elements are described and illustrated using the same reference numerals.
Referring to Figure 15, a portion of an injection molding nozzle is shown with a replaceable integral valve-gated nozzle according to the present invention. As with the embodiments above, integral nozzle seal and tip 42 comprises a tip 76 and a sleeve 78. Centrally located within melt passage 32 and melt duct 40 is a valve pin 190 positionable between an "open" position (as seen on the left half of Figure 14) and a "closed"
position (as seen on the right half of Figure 14). During the injection cycle, valve pin is withdrawn to its "open" position by suitable means (not shown) to permit pressurized melt to flow from an injection molding machine (not shown), through melt passage 32, melt duct 40 and gate 44 into cavity 46. When the cavity is filled with melt and a suitable packing period has passed, valve pin 190 is moved to the closed position to block and seal gate 44 prior to the opening of the mold to eject the molded part. The specifics of the operation of such valve gates are not within the scope of the present invention and are well-known in the art and, thus, a more detailed description is not required in this specification.
Tip 76 and a sleeve 78 are again integrally joined, preferably by nickel alloy brazing, along an interface line 100 between outer surface 80 of tip 76 and inner surface 96 of sleeve 78. As with the embodiments described above, tip 76 is preferably made of a highly thermally conductive material such as beryllium copper (BeCu) while sleeve 78 is preferably made of a material which is less thermally conductive, and preferably much less thermally conductive, than the tip 76. Materials such as a high speed steel, H13 stainless steel and titanium are preferred.
Referring to Figure 16, in an alternate embodiment of the valve gate of Figure 10 and 11, tip 76 has a shoulder 88 which extends outwardly near the rear end 82.
It will be understood that, in the descriptions in this specification, the same reference numerals have been used throughout the Figures to depict the elements which are common to, or have a common function within, the embodiments described.
While the above description constitutes the preferred embodiments, it will be appreciated that the present invention is susceptible to modification and change without departing from the fair meaning of the accompanying claims. For example, other brazing materials may be used or, rather than brazing, the nozzle tip and seal portions may be integrally made by thermally bonding, welding, thermally expanding, interference fitting tip 76 within sleeve 78. As well, one skilled in the art will appreciate that the present invention may also be applied to inserts utilizing other gating methods, such as sprue gates, edge gates, multi-tip gates and horizontal tip gates, and that the present invention is not limited to the gating configurations described herein. Still other modifications will be apparent to those skilled in the art and thus will be within the proper scope of the accompanying claims.
While apparently providing an improved means for sealing the mold gate, the insert of Schmidt also suffers from the limitations of the prior art discussed above, in that when the sleeve is removed for maintenance or replacement, the tip is susceptible to remaining stuck in the nozzle end because the tip and sleeve are unconnected. Thus, tip damage of the type already described may still result. A further disadvantage of the Schmidt design is that the nozzle tip and sleeve require extremely accurate machining to within tight tolerances to ensure that the zero clearance sealing mechanism of the invention is effective. Such accurate machining is time-consuming and expensive.
Another removable tip and gate configuration is provided by United States Patent No. 5,879,727 to Puri. Puri discloses providing an intermediate titanium or ceramic insulating element between a copper-alloy nozzle tip and a steel gate insert to thermally isolate the nozzle tip from the gate insert while permit a secure mechanically connection between the two.
The tip itself joins the assembly to the nozzle end, either removably, through the provision of threads, or integrally. As described above, however, the threading of the nozzle tip is undesirable where copper-alloy tips are used and impossible if a tungsten carbide tip insert is desired. Furthermore, the additional insulating sleeve of Puri is an additional element which must be accurately machined and maintained, thereby adding to both the initial cost and the maintenance demands on the operator.
US 4,004,871 to Hardy discloses a bi-material mold gate conduit for use in injection molding thermosetting resins. The Mold gate conduit has an inner tube welded or brazed to an outer sleeve-like body.
The outer sleeve is slidably received within and pinned between co-operating mold plate members, and an annular chamber for circulating coolant around the gate is provided between the outer sleeve and the inner tube. However, because the outer sleeve is only slidably received by the assembly, there is no secure attachment provided and, further, removal can be difficult because resin leakage can freeze the conduit to the assembly, making the unit just as susceptible to damage in removal as in those devices described above.
Accordingly, there is a need for an improved multi-material replaceable nozzle tip which is more easily removable and which is less susceptible to damage than the replace able nozzle tips of the prior art.
Further, there is a need for such tips which are more easily manufacturable and at a reduced cost.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a removable injection molding nozzle tip comprising a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member, and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, wherein said sleeve member is threadlessly integrally attached to said tip member at said interface.
In a second aspect, the present invention provides a removable injection molding nozzle tip comprising a tip member formed of a first material, said tip member having a rear end, a front end adapted to communicate with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and a substantially smooth outer surface extending around at least a portion of said tip member, and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a substantially smooth inner surface contacting at least a portion of said outer surface of said tip member to form a interface therebetween, said sleeve member being integrally attached to said tip member at said interface.
In a third aspect, the present invention provides an injection molding apparatus for forming a molded article, the apparatus comprising at least one mold cavity, said at least one mold cavity formed between at least one pair of mold plates, said at least one mold cavity having a mold gate for communicating with an interior of said at least one cavity, an injection molding nozzle having a body, an end, and at least one melt channel through said body, said injection molding nozzle connectable to a source of molten material and capable of feeding molten material from said source to said end through said at least one melt channel, and a nozzle tip removably mounted to said end of said injection molding nozzle, said nozzle tip having a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct communicating with said at least one melt channel and extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member, and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact one of said mold plates around said mold gate, a rear end adapted for removable attachment to said injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, said sleeve member being threadlessly integrally attached to said tip member at said interface.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example to the accompanying drawings showing articles made according to a preferred embodiment of the present invention, in which:
Figure 1 is a sectional view of an injection molding system incorporating a removable multi-material nozzle tip according to a preferred embodiment of the present invention;
Figure 2 is an enlarged sectional view of the nozzle tip of Figure 1;
Figure 3 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having no internal shoulder;
Figure 4 is an enlarged sectional view of a further alternate embodiment of the nozzle tip of Figure 1, having a tip of reduced size;
Figure 5 is an enlarged sectional view of a yet further alternate embodiment of the nozzle tip of Figure 1, having a two-piece seal portion;
Figure 6 is an enlarged sectional view of a still further alternate embodiment of the nozzle tip of Figure 1, having a two-piece tip portion;
Figure 7a is an enlarged sectional view of another alternate embodiment of the nozzle tip of Figure 1, having a wear-resistant tip;
Figure 7b is an enlarged sectional view of a second configuration of the embodiment of Figure 7a;
Figure 8a is an enlarged sectional view of yet another alternate embodiment of the nozzle tip of Figure 1, having an internal angled portion at an upper end thereof;
Figure 8b is a much enlarged sectional view of a portion of Figure 8a;
_7_ Figure 8c is an enlarged sectional view of a second configuration of the embodiment of Figure 8a, having an internal angled portion at a lower end thereof;
Figure 8d is a much enlarged sectional view of a portion of Figure 8c;
Figure 9 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having a two-channel tip;
Figure 10 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having alternate attachment means;
Figure 11 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 1, having a further alternate attachment means;
Figure 12 is an enlarged sectional view of a portion of an injection molding system incorporating a replaceable integral nozzle tip according a second main embodiment of the present invention;
Figures 13a-13d are enlarged sectional views of alternate embodiments of the nozzle tip of Figure 12;
Figure 14 is a sectional view of a portion of an injection molding system incorporating a replaceable integral valve-gated nozzle tip according to the present invention;
Figure 15 is an enlarged sectional view of the nozzle tip of Figure 14;
Figure 16 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 14, having an internal shoulder; and Figure 17 is an enlarged sectional view of an alternate embodiment of the nozzle tip of Figure 14, having an integral construction.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A portion of a multi-cavity injection molding system or apparatus made in accordance with the present invention is shown in the Figures generally at M. Referring to Figure 1, apparatus M has a melt distribution manifold 10 interconnecting several heated nozzles 12 in a mold 14. While mold 14 usually has a greater number of plates depending upon the application, in this case a nozzle mold platen 15, cavity plate 16, a support plate 17, a back plate 18 and under cavity platen 19, which are secured together by bolts 20, are shown for ease of illustration. The melt distribution manifold 10 is heated by an integral electrical heating element 22 and mold 14 is cooled by pumping cooling water through cooling conduits 24. Melt distribution manifold 10 is mounted between cavity plate 16 and back plate 18 by a central locating ring 26 and insulative spacer members 28 which provide an insulative air space 30 between heated manifold 10 and surrounding mold 14.
A melt passage 32 extends from a central inlet 34 in a cylindrical inlet portion 36 of manifold 10 and branches outward in manifold 10 to convey heated melt through a central bore 38 in each of heated nozzles 12. Heated melt then flows through a melt duct 40 in an integral nozzle seal and tip 42 according to the present invention to a gate 44 extending through cavity plate 16 leading to a cavity 46. Each nozzle 12 has a rear end 48 which abuts against front face 50 of melt distribution manifold 10 and a front end 52 with a threaded seat 54 extending around central melt bore 38. An electrical heating element 56 extends in the nozzle 12 integrally around central melt bore 38 to an external terminal 58 to receive power through leads 60. Nozzle 12 is seated in a well 62 in cavity plate 16 with an insulative air space 68 between heated nozzle 12 and cooled mold 14.
Nozzles 12 are securely retained in wells 62 by bolts 74 which extend from manifold 10 into cavity plate 16.
Referring to Figure 2, integral nozzle seal and tip 42 has a tip member 76 integrally joined to a sleeve member 78. As will be described below, sleeve 78 performs a sealing function and a connecting function. Tip 76 has an outer surface 80, a rear end 82, and a front end 84 and melt duct 40 extending from rear end 82 to front end 84. Outer surface 80 has a substantially smooth (i.e. unthreaded) cylindrical portion 86 extending between a shoulder 88, which extends outwardly near the rear end 82, and _g_ a portion 90, which tapers inwardly to the front end 84. Sleeve 78 of integral nozzle seal and tip 42 has a rear end 92, a front end 94, and an inner surface 96 with a substantially smooth (i.e. unthreaded) cylindrical portion 98 which fits around the cylindrical portion 86 of the outer surface 80 of the tip 76. Tip 76 is integrally attached to sleeve 78 at an interface 100 where portion 86 of outer surface 80 and portion 98 of inner surface 96 contact one another, as will be described in more detail below. Sleeve 78 also has a hexagonal nut-shaped portion 102 extending between a rear portion 104 and a cylindrical front seal portion 106. Rear portion 104 is threaded and adapted to engage mating threads in seat 54 in front end 52 of nozzle 12.
Melt duct 40 through tip 76 of integral nozzle seal and tip 42 is aligned with central melt bore 38 through nozzle 12 and leads to an outlet 110 at front end 84 and is aligned with gate 44. The nut-shaped intermediate portion 102 extends outwardly into insulative air space 68 between front end 52 of the heated nozzle and cooled mold 14 and is engageable by a suitable tool to tighten integral nozzle seal and tip 42 in place or remove it for cleaning or replacement if necessary, as will be described further below. Sleeve 78 of integral nozzle seal and tip 42 extends forwardly towards gate 44 and seal portion 106 of sleeve 78 is in sealing contact with cylindrical surface 114 of opening 112 to prevent pressurized melt escaping into insulative air space 68.
Tip 76 may be made of a corrosion and wear resistant material such as tungsten carbide or may be a highly thermally conductive material such as beryllium copper (BeCu) or other copper alloys. Sleeve 78 of integral nozzle seal and tip 42, which is in contact with both heated nozzle and cooled mold 14, is made of a material which is less thermally conductive, and preferably much less thermally conductive, than the tip 76.
Materials such as a high speed steel, H13 stainless steel and titanium are preferred. Tip 76 is integrally attached to sleeve 78, preferably by nickel alloy brazing, along an interface 100.
Referring again to Figure 1, in use electrical power is applied to heating element 22 in manifold 10 and to heating elements 56 in nozzles 12 to heat them to an operating temperature. Pressurized melt is provided from a molding machine (not shown) to central inlet 34 of melt passage 32 according to a predetermined cycle. The melt flows through melt distribution manifold 10, nozzles 12, integral nozzle seal and tip 42 and gate 44 into cavity 46. After cavity 46 is filled and a suitable packing and cooling period has expired, the injection pressure is released and the melt conveying system is decompressed to avoid stringing through open gates 44. The mold 14 is then opened to eject the molded product. After ejection, mold 14 is closed and the cycle is repeated continuously with a cycle time dependent upon the size of cavities 46 and the type of material being molded. During this repetitious injection cycle, heat is continuously transferred by integral nozzle seal and tip 42 according to a predetermined thermodynamic cycle. The proximity of the cooled metal around cavity 46 and the uniform thin insulation provided between it and integral nozzle seal and tip 42 allows for controlled solidification of the sprue. During injection, the highly conductive tip 76 of integral nozzle seal and tip 42 helps to conduct excess heat which is generated by the friction of the melt flowing through the constricted area of gate 44 rearwardly to avoid stringing and drooling of the melt when the mold opens for ejection. After the melt has stopped flowing, solidification of melt in gate 44 is enhanced by the removal of excess friction heat through tip 76 of integral nozzle seal and tip 42.
Also, in use, integral nozzle seal and tip 42 is periodically removed for maintenance, repair or resin colour change. To do so, nozzle 12 is withdrawn from well 62 and hex-nut portion 102 of integral nozzle seal and tip 42 is engaged by a suitable tool permit integral nozzle seal and tip 42 to be threadingly removed from end 52 of nozzle 12. Since the nozzle seal of the present invention is integral, the nozzle seal is always removed in one piece from end 52 of nozzle 12. Unlike the prior art, due to its integral nature integral nozzle seal and tip 42 is not susceptible to having tip 76 remain stuck within nozzle 12 after sleeve 78 is removed. The thread-advancing action in unscrewing integral seal and tip 42 from nozzle 12 ensures that the integral seal and tip does not stick thereto.
As is known in the art, employing a highly conductive tip 76 with a sleeve 78 of lesser conductivity provides the combination of good conductivity along tip 76, to maintain a rapid thermodynamic cycle, and provides thermal separation via sleeve 78 to reduce heat lost to cooled mold 14. (A measure of insulation is also provided by a circumferential air space 120 provided between tip 76 and sleeve 78, which also partially fills with melt which solidifies to provide additional insulation.) According to the present invention, however, bonding tip 76 to sleeve 78 provides an nozzle seal integral unit which results in better performance and longevity, by reason of facilitating maintenance and tip change because removal of the threaded connector portion also intrinsically removes the tip portion as well from the nozzle seat, thereby removing the possibility that the tip will be independently stuck in the nozzle and thereby require additional effort to remove. In doing so, the present invention provides a tip which will not need to be subject to the physical abuse, as it were, the prior art nozzle tips are subject to in removal from a stuck condition in a nozzle. This permits the present invention to provide a nozzle seal unit with increased longevity and which facilitates easier nozzle seal removal overall.
Advantageously, the present invention also permits integral nozzle seal and tip 42 to be fabricated more simply because brazing tip 76 to sleeve 78 permits these components to be made within less strict tolerances than the prior art. Specifically, because an additional brazing material is added between tip 76 and sleeve 78 at interface 100, outer surface 80 and inner surface 96 do not necessarily have to be within the same strictness of tolerances as with the prior art, which typically requires a smooth, face-to-face contact at interface 100. Thus, the present invention provides a replaceable nozzle tip and seal which may be made more economically.
Referring to Figures 3-9, alternate embodiments of the nozzle tip of Figure 1, are shown. As most of the elements are the same as those described above, common elements are described and illustrated using the same reference numerals. Referring to Figure 3, in a first alternate embodiment, tip 76 and sleeve 78 are of roughly the same length and tip 76 resides completely within sleeve 78.
Referring to Figure 4, in an alternate embodiment of the nozzle tip of Figure 1, tip 76 is shorter than sleeve 78, and terminates at a shoulder 122. Melt duct 40 has two regions, namely a connector melt duct 40A and a tip melt duct 40B.
Referring to Figure 5, in a further alternate embodiment of the nozzle tip of Figure 1, sleeve assembly 130 comprises a seal member 132 and a connector member 134 integrally joined, preferably by brazing, along an interface 136. Seal member 132 is preferably made of a material having lower thermal conductivity, such as H13 stainless steel, high speed steel or titanium, while connector member 134 is more thermal conductive and made of BeCu or other alloys of copper.
Referring to Figure 6, in a further alternate embodiment of the nozzle tip of Figure 1, tip assembly 140 comprises a rear member 142 and a tip member 144 integrally joined, preferably by brazing, along an interface 146.
Referring to Figure 7a, in a further alternate embodiment of the nozzle tip of Figure 1, tip portion 150 comprises a body member 152 and a tip point 154 integrally joined, preferably by brazing, along an interface 156.
Body member 152 is preferably made of a material having high thermal conductivity, such as beryllium copper, and tip point 154 is made of a corrosion and wear resistant material such as tungsten carbide. Referring to Figure 7b, in an alternate configuration, a tip insert 154' is used, which is integrally joined, preferably by brazing, along an interface 156'. The brazing is preferably achieved with a brazing material having a substantially lower melt temperature than the brazing done at interface 100, such that tip insert 154' is removable without compromising the braze at interface 100.
Referring to Figure 8a, in another alternate embodiment nozzle tip of Figure 1, tip 76 and sleeve 78 have a mating angled section 160, near rear end 82 of tip 76, at which tip portion is slightly expanded in diameter.
This construction assists in the assembly of integral nozzle seal and tip 42 prior to the integral joining of tip 76 and sleeve 78. Referring to Figure 8b, alternately a mating angled section 162 may be provided near front end 94 of sleeve 78, at which tip 76 is slightly reduced in diameter.
Referring to Figure 9, in another alternate embodiment nozzle tip of Figure 1, tip 76 is a two-channel tip in which melt duct 40 terminates in two outlets 110a and 110b.
As one skilled in the art will appreciate, the replaceable integral nozzle seal and tip of the present invention is not limited to one in which nozzle seat 54 and seal rear portion 104 are threaded to one another.
Rather, other means of removably connecting integral nozzle seal and tip 42 to nozzle 12 may be employed. For example, rear portion 104 can be brazed to seat 54 using a second brazing material which has a melting temperature which is substantially lower than the brazing material used at interface 100, as disclosed in U.S. Patent No. 6,009,616 to Gellert, incorporated herein by reference. Referring to Figure 10, in one aspect tip 76 is integrally brazed to sleeve 78 along interface 100 using a first brazing material, as described above, to make integral nozzle seal and tip 42. The integral tip insert is then brazed to nozzle 12, along an interface 170, using a second brazing material which has a melting temperature preferably substantially below that of the first brazing material. This approach allows integral tip to be easily removed for replacement or repair by heating but does not affect the metallurgical bond at interface 100 during either installation or removal. Referring to Figure 11, in a second aspect, a combined attachment means for attaching integral nozzle seal and tip 42 to nozzle 12 is shown. In this aspect, integral nozzle seal and tip 42 is both threaded and brazed to nozzle 12. Rear portion 104 has threads for engaging seat 54, as described for the embodiments above, and is additionally brazed along interface 172 using a second brazing material which has a melting temperature preferably substantially below that of the first brazing material employed at interface 100.
Referring to Figure 12, in another embodiment of the present invention sleeve 78 is connected around and outside front end 52 of nozzle 12. Sleeve 78 has a threaded read end 104 which removably engages threads in seat 54 of nozzle 12. Tip 76 is integrally brazed to sleeve 78 at interface 100. Optionally, tip 76 may also be brazed directly to nozzle 12, along interface 180, using a second brazing material which has a melting temperature preferably substantially below that of the first brazing material employed at interface 100, in a process as disclosed in Gellert 6,009,616 and described above. The integral connection between tip 76 and sleeve 78, along interface 100 permits the integral nozzle seal and tip 42 to be removed as a single unit.
Figures 13a-13d disclose some of the many modifications possible to the Figure 12 embodiment of the present invention. In Figure 13a, the threaded connection between rear portion 104 and seat 54 is replaced by a braze along interface 182, this braze being of a second brazing material which has a melting temperature preferably substantially below that of the first brazing material employed at interface 100. Referring to Figure 13b, nozzle 12 may be provided with a band heater either in place of or conjunction with electrical heating element 56 (not seen in Figure 13b but shown in Figure 1). As shown in Figure 13c, electrical heating element 56 may extend to front end 52 of nozzle 12 and inside the portion of nozzle 12 surrounded by rear portion 104 of sleeve 78. Referring to Figure 13d, tip 76 may be a two-channel tip in which melt duct 40 terminates in two outlets 110a and 110b.
As one skilled in the art will appreciate, the replaceable integral nozzle seal and tip of the present invention is not limited to a torpedo style gating as described above. Referring to Figures 14-17, the present invention is shown in use in several a valve gating embodiments.
As most of the elements are the same as those described above, common elements are described and illustrated using the same reference numerals.
Referring to Figure 15, a portion of an injection molding nozzle is shown with a replaceable integral valve-gated nozzle according to the present invention. As with the embodiments above, integral nozzle seal and tip 42 comprises a tip 76 and a sleeve 78. Centrally located within melt passage 32 and melt duct 40 is a valve pin 190 positionable between an "open" position (as seen on the left half of Figure 14) and a "closed"
position (as seen on the right half of Figure 14). During the injection cycle, valve pin is withdrawn to its "open" position by suitable means (not shown) to permit pressurized melt to flow from an injection molding machine (not shown), through melt passage 32, melt duct 40 and gate 44 into cavity 46. When the cavity is filled with melt and a suitable packing period has passed, valve pin 190 is moved to the closed position to block and seal gate 44 prior to the opening of the mold to eject the molded part. The specifics of the operation of such valve gates are not within the scope of the present invention and are well-known in the art and, thus, a more detailed description is not required in this specification.
Tip 76 and a sleeve 78 are again integrally joined, preferably by nickel alloy brazing, along an interface line 100 between outer surface 80 of tip 76 and inner surface 96 of sleeve 78. As with the embodiments described above, tip 76 is preferably made of a highly thermally conductive material such as beryllium copper (BeCu) while sleeve 78 is preferably made of a material which is less thermally conductive, and preferably much less thermally conductive, than the tip 76. Materials such as a high speed steel, H13 stainless steel and titanium are preferred.
Referring to Figure 16, in an alternate embodiment of the valve gate of Figure 10 and 11, tip 76 has a shoulder 88 which extends outwardly near the rear end 82.
It will be understood that, in the descriptions in this specification, the same reference numerals have been used throughout the Figures to depict the elements which are common to, or have a common function within, the embodiments described.
While the above description constitutes the preferred embodiments, it will be appreciated that the present invention is susceptible to modification and change without departing from the fair meaning of the accompanying claims. For example, other brazing materials may be used or, rather than brazing, the nozzle tip and seal portions may be integrally made by thermally bonding, welding, thermally expanding, interference fitting tip 76 within sleeve 78. As well, one skilled in the art will appreciate that the present invention may also be applied to inserts utilizing other gating methods, such as sprue gates, edge gates, multi-tip gates and horizontal tip gates, and that the present invention is not limited to the gating configurations described herein. Still other modifications will be apparent to those skilled in the art and thus will be within the proper scope of the accompanying claims.
Claims (19)
1. A removable injection molding nozzle tip comprising:
a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member; and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, wherein said sleeve member is threadlessly integrally attached to said tip member at said interface.
a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member; and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, wherein said sleeve member is threadlessly integrally attached to said tip member at said interface.
2. A removable injection molding nozzle tip according to claim 1 wherein said sleeve member is brazed to said tip member.
3. A removable injection molding nozzle tip according to claim 1 wherein said sleeve member is integrally attached to said tip member by an attachment means selected from the group consisting of brazing, interference-fitting, press-fitting and thermally-bonding.
4. A removable injection molding nozzle tip according to claim 1 wherein said second material is substantially less thermally conductive than said first material.
5. A removable injection molding nozzle tip according to claim 1 wherein said rear end of said seal member is adapted to threadingly engage said injection molding nozzle body.
6. A removable injection molding nozzle tip according to claim 1 wherein said rear end of said seal member is adapted to be brazed to said injection molding nozzle body.
7. A removable injection molding nozzle tip according to claim 1 wherein said sleeve member further comprises a sealing portion and a connecting portion, said sealing portion being formed of said second material and said connecting portion being formed of a third material, said third material having higher thermal conductivity than said second material.
8. A removable injection molding nozzle tip according to claim 1 wherein said tip member comprises a tip portion and a rear portion, said tip portion being formed of a third material and said rear portion being formed of said first material, said third material having higher hardness than said first material.
9. A removable injection molding nozzle tip according to claim 8 wherein said tip portion is removably attachable to said rear portion.
10. A removable injection molding nozzle tip comprising:
a tip member formed of a first material, said tip member having a rear end, a front end adapted to communicate with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and a substantially smooth outer surface extending around at least a portion of said tip member; and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a substantially smooth inner surface contacting at least a portion of said outer surface of said tip member to form a interface therebetween, said sleeve member being integrally attached to said tip member at said interface.
a tip member formed of a first material, said tip member having a rear end, a front end adapted to communicate with a mold gate, a central melt duct extending through said tip member from said rear end to said front end, and a substantially smooth outer surface extending around at least a portion of said tip member; and a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact a mold plate around a mold gate, a rear end adapted for removable attachment to an injection molding nozzle body, and a substantially smooth inner surface contacting at least a portion of said outer surface of said tip member to form a interface therebetween, said sleeve member being integrally attached to said tip member at said interface.
11. A removable injection molding nozzle tip according to claim 10 wherein said second material is substantially less thermally conductive than said first material.
12. A removable injection molding nozzle tip according to claim 10 wherein said sleeve member is integrally attached to said tip member by an attachment means selected from the group consisting of brazing, interference-fitting, press-fitting and thermally-bonding.
13. A removable injection molding nozzle tip according to claim 10 wherein said sleeve member further comprises a sealing portion and a connecting portion, said sealing portion being formed of said second material and said connecting portion being formed of a third material, said third material having higher thermal conductivity than said second material.
14. A removable injection molding nozzle tip according to claim 10 wherein said tip member comprises a tip portion and a rear portion, said tip portion being formed of a third material and said rear portion being formed of said first material, said third material having higher hardness than said first material.
15. An injection molding apparatus for forming a molded article, the apparatus comprising:
(a) at least one mold cavity, said at least one mold cavity formed between at least one pair of mold plates, said at least one mold cavity having a mold gate for communicating with an interior of said at least one cavity;
(b) an injection molding nozzle having a body, an end, and at least one melt channel through said body, said injection molding nozzle connectable to a source of molten material and capable of feeding molten material from said source to said end through said at least one melt channel; and (c) a nozzle tip removably mounted to said end of said injection molding nozzle, said nozzle tip having:
(i) a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct communicating with said at least one melt channel and extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member; and (ii) a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact one of said mold plates around said mold gate, a rear end adapted for removable attachment to said injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, said sleeve member being threadlessly integrally attached to said tip member at said interface.
(a) at least one mold cavity, said at least one mold cavity formed between at least one pair of mold plates, said at least one mold cavity having a mold gate for communicating with an interior of said at least one cavity;
(b) an injection molding nozzle having a body, an end, and at least one melt channel through said body, said injection molding nozzle connectable to a source of molten material and capable of feeding molten material from said source to said end through said at least one melt channel; and (c) a nozzle tip removably mounted to said end of said injection molding nozzle, said nozzle tip having:
(i) a tip member formed of a first material, said tip member having a rear end, a front end communicating with a mold gate, a central melt duct communicating with said at least one melt channel and extending through said tip member from said rear end to said front end, and an outer surface extending around said tip member; and (ii) a sleeve member formed of a second material different from said first material, said sleeve member extending around at least a portion of said tip member, said sleeve member having a front end adapted to sealingly contact one of said mold plates around said mold gate, a rear end adapted for removable attachment to said injection molding nozzle body, and a inner surface contacting at least a portion of said outer surface of said tip member to form an interface between said sleeve member and said tip member, said sleeve member being threadlessly integrally attached to said tip member at said interface.
16. A removable injection molding nozzle tip according to claim 15 wherein said second material is substantially less thermally conductive than said first material.
17. A removable injection molding nozzle tip according to claim 15 wherein said sleeve member is integrally attached to said tip member by an attachment means selected from the group consisting of brazing, interference-fitting, press-fitting and thermally-bonding.
18. A removable injection molding nozzle tip according to claim 15 wherein said rear end of said seal member is adapted to threadingly engage said injection molding nozzle body.
19. A removable injection molding nozzle tip according to claim 15 wherein said rear end of said seal member is adapted to be brazed to said injection molding nozzle body.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2332062 CA2332062A1 (en) | 2001-01-23 | 2001-01-23 | Integral multi-material injection molding nozzle seal and tip |
| CA2406162A CA2406162C (en) | 2000-04-12 | 2001-04-12 | Injection nozzle system and injection molding machine incorporating same |
| PCT/CA2001/000527 WO2001078961A1 (en) | 2000-04-12 | 2001-04-12 | Injection nozzle system and injection molding machine incorporating same |
| AU2001252074A AU2001252074A1 (en) | 2000-04-12 | 2001-04-12 | Injection nozzle system and injection molding machine incorporating same |
| US10/268,886 US6769901B2 (en) | 2000-04-12 | 2002-10-11 | Injection nozzle system for an injection molding machine |
| US10/880,438 US7182591B2 (en) | 2000-04-12 | 2004-06-30 | Injection nozzle system and injection molding machine incorporating same |
| US11/679,455 US7507081B2 (en) | 2000-04-12 | 2007-02-27 | Injection nozzle system for an injection molding machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2332062 CA2332062A1 (en) | 2001-01-23 | 2001-01-23 | Integral multi-material injection molding nozzle seal and tip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2332062A1 true CA2332062A1 (en) | 2002-07-23 |
Family
ID=4168152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2332062 Abandoned CA2332062A1 (en) | 2000-04-12 | 2001-01-23 | Integral multi-material injection molding nozzle seal and tip |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2332062A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004085131A1 (en) * | 2002-11-12 | 2004-10-07 | Husky Injection Molding Systems Ltd. | Injection molding nozzle |
| WO2008128319A1 (en) * | 2007-04-20 | 2008-10-30 | Husky Injection Molding Systems Ltd. | Improved nozzle tip for high melt pressure applications |
| US7780434B2 (en) | 2001-10-03 | 2010-08-24 | Mold-Masters (2007) Limited | Nozzle for an injection molding apparatus |
| WO2017201611A1 (en) * | 2016-05-27 | 2017-11-30 | Husky Injection Molding Systems Ltd. | Mold gate structures |
-
2001
- 2001-01-23 CA CA 2332062 patent/CA2332062A1/en not_active Abandoned
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7780434B2 (en) | 2001-10-03 | 2010-08-24 | Mold-Masters (2007) Limited | Nozzle for an injection molding apparatus |
| US7891969B2 (en) | 2001-10-03 | 2011-02-22 | Mold-Masters (2007) Limited | Injection molding nozzle |
| WO2004085131A1 (en) * | 2002-11-12 | 2004-10-07 | Husky Injection Molding Systems Ltd. | Injection molding nozzle |
| WO2008128319A1 (en) * | 2007-04-20 | 2008-10-30 | Husky Injection Molding Systems Ltd. | Improved nozzle tip for high melt pressure applications |
| US7549855B2 (en) | 2007-04-20 | 2009-06-23 | Husky Injection Molding Systems Ltd. | Nozzle tip for high melt pressure applications |
| WO2017201611A1 (en) * | 2016-05-27 | 2017-11-30 | Husky Injection Molding Systems Ltd. | Mold gate structures |
| US11084195B2 (en) | 2016-05-27 | 2021-08-10 | Husky Injection Molding Systems Ltd. | Mold gate structures |
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| Date | Code | Title | Description |
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