CA2046428A1 - Core removal from molded products - Google Patents
Core removal from molded productsInfo
- Publication number
- CA2046428A1 CA2046428A1 CA002046428A CA2046428A CA2046428A1 CA 2046428 A1 CA2046428 A1 CA 2046428A1 CA 002046428 A CA002046428 A CA 002046428A CA 2046428 A CA2046428 A CA 2046428A CA 2046428 A1 CA2046428 A1 CA 2046428A1
- Authority
- CA
- Canada
- Prior art keywords
- core
- cured
- molded product
- heating
- binder
- 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
- 238000000034 method Methods 0.000 claims abstract description 76
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 47
- 239000000463 material Substances 0.000 claims abstract description 40
- 239000011230 binding agent Substances 0.000 claims abstract description 30
- 150000001720 carbohydrates Chemical class 0.000 claims abstract description 20
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims abstract description 16
- 235000014633 carbohydrates Nutrition 0.000 claims abstract description 13
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 10
- 239000004576 sand Substances 0.000 claims abstract description 10
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 10
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229920002472 Starch Polymers 0.000 claims abstract description 7
- 235000019698 starch Nutrition 0.000 claims abstract description 7
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims abstract description 4
- 239000008107 starch Substances 0.000 claims abstract description 3
- 229910052751 metal Inorganic materials 0.000 claims description 31
- 239000002184 metal Substances 0.000 claims description 31
- 239000004033 plastic Substances 0.000 claims description 14
- 229920003023 plastic Polymers 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 13
- 150000002739 metals Chemical class 0.000 claims description 8
- 229920000642 polymer Polymers 0.000 claims description 8
- 239000008121 dextrose Substances 0.000 claims description 6
- 239000011521 glass Substances 0.000 claims description 6
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 229920002261 Corn starch Polymers 0.000 claims description 3
- 239000008120 corn starch Substances 0.000 claims description 3
- 235000013379 molasses Nutrition 0.000 claims description 2
- 239000011162 core material Substances 0.000 description 113
- 239000000047 product Substances 0.000 description 55
- 238000000465 moulding Methods 0.000 description 20
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 229920003169 water-soluble polymer Polymers 0.000 description 5
- 239000000126 substance Substances 0.000 description 4
- -1 tin Chemical class 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 239000011236 particulate material Substances 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229940099112 cornstarch Drugs 0.000 description 2
- 238000001723 curing Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 235000000346 sugar Nutrition 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- 229910000906 Bronze Inorganic materials 0.000 description 1
- 102100024133 Coiled-coil domain-containing protein 50 Human genes 0.000 description 1
- 206010011968 Decreased immune responsiveness Diseases 0.000 description 1
- 101000910772 Homo sapiens Coiled-coil domain-containing protein 50 Proteins 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 241000209149 Zea Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 238000013007 heat curing Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002991 molded plastic Substances 0.000 description 1
- 239000012768 molten material Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 235000013824 polyphenols Nutrition 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910052845 zircon Inorganic materials 0.000 description 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
- B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
- B22C1/188—Alkali metal silicates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/167—Mixtures of inorganic and organic binding agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
- B22C1/26—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of carbohydrates; of distillation residues therefrom
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
- B22D29/001—Removing cores
- B22D29/002—Removing cores by leaching, washing or dissolving
-
- 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
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
- B29C33/52—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
Abstract
ABSTRACT OF THE DISCLOSURE A method of removing a core from a molded product in which the core is formed of a particulate inert material, such as sand, bound together by a cured binder of a water soluble carbohydrate alone or mixed with a silicate is disclosed. The silicate is preferably an alkali earth metal silicate, preferably sodium silicate, and the carbohydrate is preferably a saccharide or starch. The binder is cured by heat. The core and molded product are exposed to water, preferably heated water in a bath or steam, to rapidly disintegrate the core and remove it from the molded product.
Description
20~28 CORE REMOVAL FROM MOLDED PRODUCTS
______________________.__ ____________ ~ACRGROUND AND S~MMARY OF THE INVENTION
The present invention is directed to a metbod for the removal of a molding core from a molded product after the procluct has been molded and a cured core and product made thereby.
Over the years considerable attention has been directed to the development and expansion of lost core technology for the molding of products having complex shapes, undercuts or negative drafts or complex cavity configurations. In lost core technology such complex shapes and configurations which cannot typically be formed utilizing permanent, reusable molding forms are formed by using a shaped core or other mold form on a one time basis to form the portion of the product which is of comple~
Configuration and is ~hen removed from the complex portion of the molded product by disintegrating the core away ~rom the molded product.
Various materials and procedures have been employed in the forming and removal of such cores, all of which have their disadvantages.
One such prior procedure involves the use of low melt metals, such as tin, bismu~h or other low melt alloys. In this procedure the low melt metal is first shaped into the negative of the complex shape which is to be presen~ in ~he finished molded product. l'his metal cnre i9 then positioned in the , 2~46~28 mold and the material from which the finished product is to be molded is pored or injected into the mold about the core. Once the mat~erial from which the product is to be made has solidified, the molded product together with the core are removed from the mold and are heated to mel~ the core away from the finished product.
~ his low melt metal procedure suffers a number of disadvantages7 In the first instance the procedure can only typically be employed in the molding of materials which are of a higher melt temperature than the low melt metal core material.
Thus, the procedure is not generally usable in the molding of plastic polymers which have a lower melt or decomposition temperature than the metal of the core. Another disadvantage is that the heat and pressures during molding tend to deform the core.
Moreover, the core material is heavy and e~pensive, and it may be toxic. ~herefore, the low melt metal is difficult to handle and process. The low melt metal procedures are also energy intensive requiring large amounts of heat in the melting process, and they frequently require high temperature oil baths which are both expensive and hazardous. The low melt metal procedures are also difficult ~o contro~ during the core removal to prevent damage to the molded end product, and the low melt metals are hard to reclaim.
Still another disadvan~age is that the low melt metal procedures typically reguire relatively long periods of time for the removal of the core which may be upwards of 45 minutes or more.
Water soluble polymers, such as amorphous acrylic base copolymers, have also been employed as , :: .: .
. , .
-204642~
core materials. These water soluble polymers represent a substantial improvement over the low melt metal procedures because they are simpler to tool and they enjoy a reduction in material costs, weight and toxicity. However, they are generally only capable of use in the molding of plastic polymers because the typical melt temperatures of the water soluble polymers is about 350 - 4100F. Moreover, the water soluble polymer core itself must typically be hollow to allow the water to enter the core which is to dissolve the core for removal. Thusl the core must usually be formed by fusing two pieces ~ogether with the attendant disadvantages of fusing and positioning of the core parts for fusing. Also because the core is hollow, it is not as strong as a solid core would be. The water soluble polymer cores al~o require a considerable time for removal of 15-20 minutes or more, and they are difficult to preheat due to their relatively low melt temperature and the possibility of flexing or distortion of the core. Another disadvantage of ~he water soluble po~ymer cores is their relatively high cost, although they may be reclaimable upon removal.
Polymer cores have also been utilized which are removable with chemical solutions or acids.
These cores also suffer the low temperature melting and relatively high expense disadvantages, and they are not usually subject to reclaimation. Moreover, the chemical solvents or acids pre~ent their own disadvantages in handling, storage, e~pense and disposal.
Cores have also been utilized for the molding oi~ high temperature materials, i.e. metals~
;: ; - : .
- ,.: - :, ; ~ :
, ~ . , ~ . , ,~ , :
. . :.. , ~, , ~ . .
-~ 2046~28 in which the core is formed of sand which is bound into its discrete desired configuration by binders including sodium silica~e ancl a sugar, such as dextrose. In these sodium silicate-dextrose bound cores, once the molded product has been formed, it and its core are removed from the mold and vibrated to disintegrate tbe core. The purpose of the sugars in these vibrationally removed cores is to provide a component material in the core which will decompose when exposed to the high molten metal temperatures during molding of the products to weaken the core as the metal is solidifying so that the core will more rapidly disintegrate when subjected to the subsequent vibration.
The principal disadvantage o~ these vibrationally removed cores is the expense and power consumed in imparting the vibrational energy to the molded product and its core and the core, once it is removed, is difficult to reclaim due to the presence of the sodium silicate and the core fragments which may still be bound toge~her to some extent.
~oreover, the application of vibration is not well suited to plastic molded products due to the undue stresses which must be imparted to the plastic during vibration and the reduced impact qualities in the lighter more resilient plastic products as opposed to metal products. Such reduced impact qualities extend the time needed for core removal. Indeed, even the use of vibratory teohnique3 for removal o~ the core from metal molded products may take con-qiderable periods of time.
In the present invention, most if not all of the aforementioned disadvantages are avoidedO In , , ~
. ., : . ~
. .
"
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..
the method of the present invlention, a core may be employed with equal facility for the molding o~
product materials which range over a wide range of melt temperatures, including ~errous metals of high melt temperatures at the high end of the range to low melt plas~ic polymers, such as polyethylene, at the low end of the range. In the method of the present invention, the cores are of a relatively light weight, are easily handled and inexpensive, and the core material is easy to reclaim and reuse following removal. In the method of the present invention, temperature control is simple and the core forming ànd removal iæ not anergy intensive. Moreover, materials employed in the method of the present invention are neither toxic nor do they present environmental concerns. Significantly, in the method of the present invention, the core may be easily and rapidly removed in most cases in less than a minute from the molded product simply by immersing the molded product and core in a plain water bath. In the method of the present invention, the core may be either solid or hollow, but core parts need not be fused as in other prior procedures. Thus, the core is simple to ~orm and shape, i8 ~trong and is stable in configuration. Still another advantage of the method of the present invention is that machining and finishing operations on the core are eliminated and the core may be used for the forming of eithe~
interior or exterior comple~ product surface~, is dimensionally stable and i9 able to withstand high pre sura and in many instances high temperature injection molding procedure~.
:
, 2~46~2~
In one principal as]pect of the present invention, a method of removing a molding core from a molded pr~duct is provided in which the core comprises a pa~ticulate inert material which is formed into a discrete configuration conforming to the configuration of at least a portion of the molded product. The particulate inert material is bound in that configuration by a cured binder comprising a water soluble carbohydrate. The method comprises e~posing the bound core in the molded produc~ to water to disintegrate and remove the core from the molded product after the product has been molded~
In anothex principal aspect of the present invention, the binder may also include a silicate, preferably an alkali earth metal silicate, and more preferably sodium silicate.
In still another principal aspect of the present inventionr the water soluble carbohydrate is a saccharide or starch.
In still another principal aspect of the present invention, the binder is cured by heating, preferably by microwave energy.
In still another principal aspect of the present invention, the particulate inert ma~erial is selected from the group consisting of sand, metal shot~ plas~ic polymers, glass, alumina, clays and mixtures thereof.
In still another principal a~pect of the present invention, the water employed to disintegrate and remove the core is heated, preferably to less than about 100 CO
In still another principal aspect of the present invention, the core and molded product are .
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2~4~28 immersed in a bath of the watler to disintegrate and remove the core.
In still another principal aspect of the present invention, the wa~er employed to disintegrate and remove the core is steam.
In still another principal aspect of the present invention, the molded product is formed of a material selected from the group consisting essentially of plastics and metals.
These and o~her objects, features and advantages of the present invention will be more clearly understood upon consideration of the detailed description of the preferred embodiment of the invention which will be described ~o follow.
BRIEF DESCRIPTION OF THE DRAWINQ
In the course of this description, reference will be made to the attached drawing in which:
FIG. 1 is a perspective view of a molded product formed in accordance with the principles of the present invention and showing the positioning of a molding core therein; and FIG. 2 is a cross-sectioned plan view showing an exterior mold, a molded product therein and a core as employed in the present invention in ~ the product.
`~, DESCRIPTION OF THE PR FERRED EMBODIMENT
~ The method of the present invention is - directed to the ~orming of a molded product 10 having at least some surfaces which are of a comple~
Configuration which would otherwise be difficult or :' ,- . . ..
2~6~28 ~8--incapable of molding without the use of a lost core technique. The product 10 is shown in FIGS. 1 and 2 only as e~emplary of one having such comple~
configuration, it not being intended that the particular shape or use of the product itself form a part of the present invention.
By way of example, the product 10 may comprise a molded plastic or metal part or fitting having a generally cubic shape as shown in FIG. 1 with annular ports 12 in each of the side face~ of the cube which are defined by annular e~terior flanges 14 and a hollow interior cavity 16 as shown in FIG. 2. It will be seen that due ~or example to the presence of the interior cavity 16, it would be difficult if not impossible to mold the product 10 using only an exterior mold, such as the mold 18 having mold par~s 19 and 20 as shown in FI~. 2.
Therefore, in order to facilitate the molding of the complex configured product 10, a molding core C i5 employed which is later removed from the product 10 after the product is removed from ~he mold.
A preferred core C for practicing the method of the present invention is ~ormed of a particula~e inert material which is bound into its desired configuration which is a negative of the surface configuration to be formed in the molded product. The binder preferably comprises a water soluble carbohydrate. A silicate may also be included in the binder.
~; A wide variety of particulate inert materials, either organic or inorganic, may be employed to form the core. The particulate inert material should have sufficiently high melt and , 2~6~2~
--g decomposition temperatures to withstand the temperature of the molten materials which are to be molded into the desired product 10 hardly soluble in water. Also they should not react with or be soluble in the material from which thle desired molded product is formed7 and should not adhere to any great extent to the product material.
A wide variety of sands may be used as the particulate inert material for the core, including most conventional foundry sands, such as 45-130 GFN
silica, lake and bank sands. Chromite, zircon and olivine sands can also be used, as well as reclaimed sands. Examples of other particulate inert materials which may be employed as core materials include small steel shot or glass beads or bubbles, small polypropylene pellet~, aluminas and clays. A
Combination of two or more of these materials may also be used.
The water soluble carbohydrate binder may include saccharides, such as des~rose and molasses, and starches such as corn starch. These carbohydrates may be utilized alone as the binder or they may be supplemented with a silicate. The silicate when used i9 preferably an inorganic alkali earth metal silicate, such as sodium silicate. A
suitable silicate-carbohydrate binder for use in the practice of the method of the present invention may be for example Adcosil NF available from Ashland Chemical Inc. which contains approximately 10~
de~trose of the total solids, has a SiO2/Na2O ratio of approximately 1.95, and a visco~ity of approximately 2.1-2.8 Stokes at 25 C.
'; , , ' 2~6~28 The molding procedure of the present invention may include injection molding, but is not limited thereto.
The core may inclucle reinforcements such as metal rods, wires or the like in order to strengthen the core. The core may also be coated, if desired, with known non-water based coatings to improve its surface smoothness.
The significant feature of the method of the present invention is that it has been discovered that cores formed of the aforementioned materials may be quickly and easily removed from the molded product simply by e~posing the molded prod~ct and core to water or steam, preferably heated water. The water may be in ~he form of pressurized wa~er or steam jets or a bath. If a water bath open to the atmosphere is employed, the temperature of the water is preferably less than 100C to avoid the added expense of boiling and the attendant loss of water due to evaporation.
It has been found that in the method of the present invention, simple immersion of the molded product in a water bath results in a very rapid, and in some cases almost ins~antaneous disintegration and removal of the core from the molded product without regard to whether the core has been exposed during the molding process to extreme high metal melt temperatures or low plastic melt temperatures, such as the melt temperature of polyethylene.
Although it is believed that the foregoing description of the pre~ent invention together with the knowledge o~ those skilled in the art are sufficient to enable one in the art to form the core, complete tb~ molding operation and remove the core, a .
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2046~28 brief description of those steps by way of e~ample follows.
The particulate inert core material and the binder are first mixed in a container. The particulate material, preferably dry, i9 added to the container and the binder material in the amount of about 5 wt. % in a suitable inert carrier liquid such as water, is added to the particulate material.
Where the particulate inert material is sand, after mixing the material in the container has the appearance of wet sand.
The next typical step is to ~orm the molded core by placing a portion of the mixed core material in a core box having a configuration of the desired final complex configuration of the molded product.
The core material is ~hen cured in the core box in that configuration by using heat, preferably in the form of microwave radiation. Microwave radiation levels on the order of those of a regular kitchen microwave will cure the core in about 1 1/2 minutes, depending upon the size of the core.
Binders containing silicates have typically been cured in the past by passing carbon dioxide through the core material in the core box. It has been ~ound in the present invention $hat the use of carbon dioxide to cure such silicate containing binder~ results in greatly reduced water solubility and greatly increased core removal times. Thu~, carbon dioxide curing is not preferred in the present invention. Heat curing is the preferred method of curing, It not only results in excellent water solubility of the core binder, but permits reduction in the a~ount of the binder material to as little as ,' ~- . .'' -about 2 wt. % of the particulate material without adverse result on the core strength.
The cured core C which is bound by the cured binder into the configuration in which it is to be inserted into the exterior mold 18 is positioned in the mold. The core C preferably has slightly larger portions than the overall size of the f inal molded product 10 to form "core prints" 22 to insure accurate positioning of the core C in the mold 18 as shown in FI~. 2.
Once the core C is positioned in the mold 18, the metal or plastic material of which it is desired to form the final molded product 10 is then injected into the remaining spaces in the mold 18 between the core C and the interior faces of the exterior mold 18 parts 19 and 20.
These injected product materials may include a wide range of plastics, including polyesters, nylons, polysulfones, polycarbonates, PTFE or phenolics~ They may also include a wide : range of metals including aluminum, bronze, brass, steel or iron. I~ will be understood that the aforementioned materials are not exhaustive of all of ~:: the materials which may be molded employing the . method of the present invention.
~~ The mold 18 is then cooled in order to solidify the molten molded produc~ material into its final shape~
~ After the product material has solidified, i the mold 1~ parts 19 and 20 are separated and the .: molded product 10 and core C are removed from the ~` mold 18. :~n accor~ance with the presen~ invention, they are together e~posed to pre~rized jets of .. .. , .. -.
2 ~ 2 8 water or steam or plunged into a water bath. The water is preferably heated in order to accelerate the disintegration and removal of the core material from the molded product 10~ It has been found that even cores C of relatively large size completely disintegrate and are removed from the molded prod~ct 10 within a matter of 15-30 seconds when immersed in a hot water bath~
The sand fr~m the clisintegrated core will settle to the bottom of the water bath and may be readily reclaimed. The silicate, if present, and the dissolved wa~er soluble carbohydrate, if it is still present and has not been decomposed by the heat during molding, are removed from the bath by maintaining a flow of fresh water through the bath.
The following are e2amples of core materials and binders which may be employed in practicing the method of the prese~t invention. They are given as exemplary only and are not to be considered as limiting the invention.
:~
.
:, '. .
~0~6~2~
Partioulate Inert inder Material ~_ _______Comments__~_~
Sodium s~licate/
De~trose Sand Good-strength. Gbod water solubility with core disintegrating in less than 1 minute.
Pure Corn Starch2, Sodium silicate/
rextrosel Sand Good strength. Esen better water solubility than just sodium silicate/de~troæ.
Molasses3 Sand Fair but acoeptable strength.
About same water solubility as corn-starch - sodium silicate/d4~tro~e binder.
Sodium s~licate/
Dextrose Glass Beads Good strength. Gbod water solubility with core disintegrating in less than 1 minute.
~' Sodium s~licate/
Dextrose Steel Shot Good strength. Gocd water solu~ility.
___~_ ~_____ ___ ___ ~ ________ _______ 1. Adcosil NF, Ashland Chemical InC.
2. Argo, CPC International InC.
______________________.__ ____________ ~ACRGROUND AND S~MMARY OF THE INVENTION
The present invention is directed to a metbod for the removal of a molding core from a molded product after the procluct has been molded and a cured core and product made thereby.
Over the years considerable attention has been directed to the development and expansion of lost core technology for the molding of products having complex shapes, undercuts or negative drafts or complex cavity configurations. In lost core technology such complex shapes and configurations which cannot typically be formed utilizing permanent, reusable molding forms are formed by using a shaped core or other mold form on a one time basis to form the portion of the product which is of comple~
Configuration and is ~hen removed from the complex portion of the molded product by disintegrating the core away ~rom the molded product.
Various materials and procedures have been employed in the forming and removal of such cores, all of which have their disadvantages.
One such prior procedure involves the use of low melt metals, such as tin, bismu~h or other low melt alloys. In this procedure the low melt metal is first shaped into the negative of the complex shape which is to be presen~ in ~he finished molded product. l'his metal cnre i9 then positioned in the , 2~46~28 mold and the material from which the finished product is to be molded is pored or injected into the mold about the core. Once the mat~erial from which the product is to be made has solidified, the molded product together with the core are removed from the mold and are heated to mel~ the core away from the finished product.
~ his low melt metal procedure suffers a number of disadvantages7 In the first instance the procedure can only typically be employed in the molding of materials which are of a higher melt temperature than the low melt metal core material.
Thus, the procedure is not generally usable in the molding of plastic polymers which have a lower melt or decomposition temperature than the metal of the core. Another disadvantage is that the heat and pressures during molding tend to deform the core.
Moreover, the core material is heavy and e~pensive, and it may be toxic. ~herefore, the low melt metal is difficult to handle and process. The low melt metal procedures are also energy intensive requiring large amounts of heat in the melting process, and they frequently require high temperature oil baths which are both expensive and hazardous. The low melt metal procedures are also difficult ~o contro~ during the core removal to prevent damage to the molded end product, and the low melt metals are hard to reclaim.
Still another disadvan~age is that the low melt metal procedures typically reguire relatively long periods of time for the removal of the core which may be upwards of 45 minutes or more.
Water soluble polymers, such as amorphous acrylic base copolymers, have also been employed as , :: .: .
. , .
-204642~
core materials. These water soluble polymers represent a substantial improvement over the low melt metal procedures because they are simpler to tool and they enjoy a reduction in material costs, weight and toxicity. However, they are generally only capable of use in the molding of plastic polymers because the typical melt temperatures of the water soluble polymers is about 350 - 4100F. Moreover, the water soluble polymer core itself must typically be hollow to allow the water to enter the core which is to dissolve the core for removal. Thusl the core must usually be formed by fusing two pieces ~ogether with the attendant disadvantages of fusing and positioning of the core parts for fusing. Also because the core is hollow, it is not as strong as a solid core would be. The water soluble polymer cores al~o require a considerable time for removal of 15-20 minutes or more, and they are difficult to preheat due to their relatively low melt temperature and the possibility of flexing or distortion of the core. Another disadvantage of ~he water soluble po~ymer cores is their relatively high cost, although they may be reclaimable upon removal.
Polymer cores have also been utilized which are removable with chemical solutions or acids.
These cores also suffer the low temperature melting and relatively high expense disadvantages, and they are not usually subject to reclaimation. Moreover, the chemical solvents or acids pre~ent their own disadvantages in handling, storage, e~pense and disposal.
Cores have also been utilized for the molding oi~ high temperature materials, i.e. metals~
;: ; - : .
- ,.: - :, ; ~ :
, ~ . , ~ . , ,~ , :
. . :.. , ~, , ~ . .
-~ 2046~28 in which the core is formed of sand which is bound into its discrete desired configuration by binders including sodium silica~e ancl a sugar, such as dextrose. In these sodium silicate-dextrose bound cores, once the molded product has been formed, it and its core are removed from the mold and vibrated to disintegrate tbe core. The purpose of the sugars in these vibrationally removed cores is to provide a component material in the core which will decompose when exposed to the high molten metal temperatures during molding of the products to weaken the core as the metal is solidifying so that the core will more rapidly disintegrate when subjected to the subsequent vibration.
The principal disadvantage o~ these vibrationally removed cores is the expense and power consumed in imparting the vibrational energy to the molded product and its core and the core, once it is removed, is difficult to reclaim due to the presence of the sodium silicate and the core fragments which may still be bound toge~her to some extent.
~oreover, the application of vibration is not well suited to plastic molded products due to the undue stresses which must be imparted to the plastic during vibration and the reduced impact qualities in the lighter more resilient plastic products as opposed to metal products. Such reduced impact qualities extend the time needed for core removal. Indeed, even the use of vibratory teohnique3 for removal o~ the core from metal molded products may take con-qiderable periods of time.
In the present invention, most if not all of the aforementioned disadvantages are avoidedO In , , ~
. ., : . ~
. .
"
.. : :
..
the method of the present invlention, a core may be employed with equal facility for the molding o~
product materials which range over a wide range of melt temperatures, including ~errous metals of high melt temperatures at the high end of the range to low melt plas~ic polymers, such as polyethylene, at the low end of the range. In the method of the present invention, the cores are of a relatively light weight, are easily handled and inexpensive, and the core material is easy to reclaim and reuse following removal. In the method of the present invention, temperature control is simple and the core forming ànd removal iæ not anergy intensive. Moreover, materials employed in the method of the present invention are neither toxic nor do they present environmental concerns. Significantly, in the method of the present invention, the core may be easily and rapidly removed in most cases in less than a minute from the molded product simply by immersing the molded product and core in a plain water bath. In the method of the present invention, the core may be either solid or hollow, but core parts need not be fused as in other prior procedures. Thus, the core is simple to ~orm and shape, i8 ~trong and is stable in configuration. Still another advantage of the method of the present invention is that machining and finishing operations on the core are eliminated and the core may be used for the forming of eithe~
interior or exterior comple~ product surface~, is dimensionally stable and i9 able to withstand high pre sura and in many instances high temperature injection molding procedure~.
:
, 2~46~2~
In one principal as]pect of the present invention, a method of removing a molding core from a molded pr~duct is provided in which the core comprises a pa~ticulate inert material which is formed into a discrete configuration conforming to the configuration of at least a portion of the molded product. The particulate inert material is bound in that configuration by a cured binder comprising a water soluble carbohydrate. The method comprises e~posing the bound core in the molded produc~ to water to disintegrate and remove the core from the molded product after the product has been molded~
In anothex principal aspect of the present invention, the binder may also include a silicate, preferably an alkali earth metal silicate, and more preferably sodium silicate.
In still another principal aspect of the present inventionr the water soluble carbohydrate is a saccharide or starch.
In still another principal aspect of the present invention, the binder is cured by heating, preferably by microwave energy.
In still another principal aspect of the present invention, the particulate inert ma~erial is selected from the group consisting of sand, metal shot~ plas~ic polymers, glass, alumina, clays and mixtures thereof.
In still another principal a~pect of the present invention, the water employed to disintegrate and remove the core is heated, preferably to less than about 100 CO
In still another principal aspect of the present invention, the core and molded product are .
. . . . .
. . . .
,. .
2~4~28 immersed in a bath of the watler to disintegrate and remove the core.
In still another principal aspect of the present invention, the wa~er employed to disintegrate and remove the core is steam.
In still another principal aspect of the present invention, the molded product is formed of a material selected from the group consisting essentially of plastics and metals.
These and o~her objects, features and advantages of the present invention will be more clearly understood upon consideration of the detailed description of the preferred embodiment of the invention which will be described ~o follow.
BRIEF DESCRIPTION OF THE DRAWINQ
In the course of this description, reference will be made to the attached drawing in which:
FIG. 1 is a perspective view of a molded product formed in accordance with the principles of the present invention and showing the positioning of a molding core therein; and FIG. 2 is a cross-sectioned plan view showing an exterior mold, a molded product therein and a core as employed in the present invention in ~ the product.
`~, DESCRIPTION OF THE PR FERRED EMBODIMENT
~ The method of the present invention is - directed to the ~orming of a molded product 10 having at least some surfaces which are of a comple~
Configuration which would otherwise be difficult or :' ,- . . ..
2~6~28 ~8--incapable of molding without the use of a lost core technique. The product 10 is shown in FIGS. 1 and 2 only as e~emplary of one having such comple~
configuration, it not being intended that the particular shape or use of the product itself form a part of the present invention.
By way of example, the product 10 may comprise a molded plastic or metal part or fitting having a generally cubic shape as shown in FIG. 1 with annular ports 12 in each of the side face~ of the cube which are defined by annular e~terior flanges 14 and a hollow interior cavity 16 as shown in FIG. 2. It will be seen that due ~or example to the presence of the interior cavity 16, it would be difficult if not impossible to mold the product 10 using only an exterior mold, such as the mold 18 having mold par~s 19 and 20 as shown in FI~. 2.
Therefore, in order to facilitate the molding of the complex configured product 10, a molding core C i5 employed which is later removed from the product 10 after the product is removed from ~he mold.
A preferred core C for practicing the method of the present invention is ~ormed of a particula~e inert material which is bound into its desired configuration which is a negative of the surface configuration to be formed in the molded product. The binder preferably comprises a water soluble carbohydrate. A silicate may also be included in the binder.
~; A wide variety of particulate inert materials, either organic or inorganic, may be employed to form the core. The particulate inert material should have sufficiently high melt and , 2~6~2~
--g decomposition temperatures to withstand the temperature of the molten materials which are to be molded into the desired product 10 hardly soluble in water. Also they should not react with or be soluble in the material from which thle desired molded product is formed7 and should not adhere to any great extent to the product material.
A wide variety of sands may be used as the particulate inert material for the core, including most conventional foundry sands, such as 45-130 GFN
silica, lake and bank sands. Chromite, zircon and olivine sands can also be used, as well as reclaimed sands. Examples of other particulate inert materials which may be employed as core materials include small steel shot or glass beads or bubbles, small polypropylene pellet~, aluminas and clays. A
Combination of two or more of these materials may also be used.
The water soluble carbohydrate binder may include saccharides, such as des~rose and molasses, and starches such as corn starch. These carbohydrates may be utilized alone as the binder or they may be supplemented with a silicate. The silicate when used i9 preferably an inorganic alkali earth metal silicate, such as sodium silicate. A
suitable silicate-carbohydrate binder for use in the practice of the method of the present invention may be for example Adcosil NF available from Ashland Chemical Inc. which contains approximately 10~
de~trose of the total solids, has a SiO2/Na2O ratio of approximately 1.95, and a visco~ity of approximately 2.1-2.8 Stokes at 25 C.
'; , , ' 2~6~28 The molding procedure of the present invention may include injection molding, but is not limited thereto.
The core may inclucle reinforcements such as metal rods, wires or the like in order to strengthen the core. The core may also be coated, if desired, with known non-water based coatings to improve its surface smoothness.
The significant feature of the method of the present invention is that it has been discovered that cores formed of the aforementioned materials may be quickly and easily removed from the molded product simply by e~posing the molded prod~ct and core to water or steam, preferably heated water. The water may be in ~he form of pressurized wa~er or steam jets or a bath. If a water bath open to the atmosphere is employed, the temperature of the water is preferably less than 100C to avoid the added expense of boiling and the attendant loss of water due to evaporation.
It has been found that in the method of the present invention, simple immersion of the molded product in a water bath results in a very rapid, and in some cases almost ins~antaneous disintegration and removal of the core from the molded product without regard to whether the core has been exposed during the molding process to extreme high metal melt temperatures or low plastic melt temperatures, such as the melt temperature of polyethylene.
Although it is believed that the foregoing description of the pre~ent invention together with the knowledge o~ those skilled in the art are sufficient to enable one in the art to form the core, complete tb~ molding operation and remove the core, a .
- , .
.: ,, :; .: : : ~
,. . .~
.. . . ::
2046~28 brief description of those steps by way of e~ample follows.
The particulate inert core material and the binder are first mixed in a container. The particulate material, preferably dry, i9 added to the container and the binder material in the amount of about 5 wt. % in a suitable inert carrier liquid such as water, is added to the particulate material.
Where the particulate inert material is sand, after mixing the material in the container has the appearance of wet sand.
The next typical step is to ~orm the molded core by placing a portion of the mixed core material in a core box having a configuration of the desired final complex configuration of the molded product.
The core material is ~hen cured in the core box in that configuration by using heat, preferably in the form of microwave radiation. Microwave radiation levels on the order of those of a regular kitchen microwave will cure the core in about 1 1/2 minutes, depending upon the size of the core.
Binders containing silicates have typically been cured in the past by passing carbon dioxide through the core material in the core box. It has been ~ound in the present invention $hat the use of carbon dioxide to cure such silicate containing binder~ results in greatly reduced water solubility and greatly increased core removal times. Thu~, carbon dioxide curing is not preferred in the present invention. Heat curing is the preferred method of curing, It not only results in excellent water solubility of the core binder, but permits reduction in the a~ount of the binder material to as little as ,' ~- . .'' -about 2 wt. % of the particulate material without adverse result on the core strength.
The cured core C which is bound by the cured binder into the configuration in which it is to be inserted into the exterior mold 18 is positioned in the mold. The core C preferably has slightly larger portions than the overall size of the f inal molded product 10 to form "core prints" 22 to insure accurate positioning of the core C in the mold 18 as shown in FI~. 2.
Once the core C is positioned in the mold 18, the metal or plastic material of which it is desired to form the final molded product 10 is then injected into the remaining spaces in the mold 18 between the core C and the interior faces of the exterior mold 18 parts 19 and 20.
These injected product materials may include a wide range of plastics, including polyesters, nylons, polysulfones, polycarbonates, PTFE or phenolics~ They may also include a wide : range of metals including aluminum, bronze, brass, steel or iron. I~ will be understood that the aforementioned materials are not exhaustive of all of ~:: the materials which may be molded employing the . method of the present invention.
~~ The mold 18 is then cooled in order to solidify the molten molded produc~ material into its final shape~
~ After the product material has solidified, i the mold 1~ parts 19 and 20 are separated and the .: molded product 10 and core C are removed from the ~` mold 18. :~n accor~ance with the presen~ invention, they are together e~posed to pre~rized jets of .. .. , .. -.
2 ~ 2 8 water or steam or plunged into a water bath. The water is preferably heated in order to accelerate the disintegration and removal of the core material from the molded product 10~ It has been found that even cores C of relatively large size completely disintegrate and are removed from the molded prod~ct 10 within a matter of 15-30 seconds when immersed in a hot water bath~
The sand fr~m the clisintegrated core will settle to the bottom of the water bath and may be readily reclaimed. The silicate, if present, and the dissolved wa~er soluble carbohydrate, if it is still present and has not been decomposed by the heat during molding, are removed from the bath by maintaining a flow of fresh water through the bath.
The following are e2amples of core materials and binders which may be employed in practicing the method of the prese~t invention. They are given as exemplary only and are not to be considered as limiting the invention.
:~
.
:, '. .
~0~6~2~
Partioulate Inert inder Material ~_ _______Comments__~_~
Sodium s~licate/
De~trose Sand Good-strength. Gbod water solubility with core disintegrating in less than 1 minute.
Pure Corn Starch2, Sodium silicate/
rextrosel Sand Good strength. Esen better water solubility than just sodium silicate/de~troæ.
Molasses3 Sand Fair but acoeptable strength.
About same water solubility as corn-starch - sodium silicate/d4~tro~e binder.
Sodium s~licate/
Dextrose Glass Beads Good strength. Gbod water solubility with core disintegrating in less than 1 minute.
~' Sodium s~licate/
Dextrose Steel Shot Good strength. Gocd water solu~ility.
___~_ ~_____ ___ ___ ~ ________ _______ 1. Adcosil NF, Ashland Chemical InC.
2. Argo, CPC International InC.
3. Grand~a's ~unsulfured), Motts USA.
In each o~ the above examples, the amount of binder used ~together with its water carrier) was a~out 5 wto% Of the particulate inert material. Where both sodium silicate/dextrose and an additional carbohydra~e binder were employed, they were a 50-50 mixture of each for a total of S wt~ ~.
In each of the above examples, the core disintegrated e~tremely rapidly -- on the order of less than one minute. It has been found that where . .
:.~` . ' ` ' : ` ` ' ` : `~
``
21D~6~2~
the cores are e~posed to high molten metal temperatures, for example in the molding of aluminum, the core remains water soluble, but the time needed for disintegration is somewhat longer.
Although the core C as shown in the drawings is shown for the ~ormation of an interior cavity in the molded product, it will be apprecia~ed that the term "core" as employed herein is not limited to only the formation of interior surfaces or cavities. The method of the present invention also contemplates the use of molded cores and removal from the molded product for the formation of cOmple~ undercut exterior surfaces with equal facility.
It will also be understood that the preferred embodiment of the present invention which has been described is merely illustrative of the principles of the present invention. ~umerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.
: :
. ~ . , , : - , , .
In each o~ the above examples, the amount of binder used ~together with its water carrier) was a~out 5 wto% Of the particulate inert material. Where both sodium silicate/dextrose and an additional carbohydra~e binder were employed, they were a 50-50 mixture of each for a total of S wt~ ~.
In each of the above examples, the core disintegrated e~tremely rapidly -- on the order of less than one minute. It has been found that where . .
:.~` . ' ` ' : ` ` ' ` : `~
``
21D~6~2~
the cores are e~posed to high molten metal temperatures, for example in the molding of aluminum, the core remains water soluble, but the time needed for disintegration is somewhat longer.
Although the core C as shown in the drawings is shown for the ~ormation of an interior cavity in the molded product, it will be apprecia~ed that the term "core" as employed herein is not limited to only the formation of interior surfaces or cavities. The method of the present invention also contemplates the use of molded cores and removal from the molded product for the formation of cOmple~ undercut exterior surfaces with equal facility.
It will also be understood that the preferred embodiment of the present invention which has been described is merely illustrative of the principles of the present invention. ~umerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the invention.
: :
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Claims (40)
1. A method of removing a molded core from a molded product wherein said core comprises a particulate inert material which is formed into a discrete configuration conforming to the configuration of at least a portion of the molded product and the particulate inert material is bound in said configuration by a cured binder comprising a water soluble carbohydrate, said method comprising exposing said bound core with said water soluble carbohydrate therein and said molded product to water after the product has been molded to disintegrate and remove the core from the molded product.
2. The method of claim 1, wherein said binder also includes a silicate.
3. The method of claim 2, wherein said silicate is an alkali earth metal silicate.
4. The method of claim 3, wherein said silicate is sodium silicate.
5. The method of claim 1, wherein said water soluble carbohydrate is selected from the group consisting essentially of saccharides and starches.
6. The method of claim 5, wherein said saccharide is selected from the group consisting essentially of dextrose and molasses.
7. The method of claim 5, wherein said starch is corn starch.
8. The method of claim 2, wherein said water soluble carbohydrate is selected from the group consisting essentially of saccharides and starches.
9. The method of claim 1, wherein the particulate inert material is selected from the group consisting of sand, metal shot, plastic polymers, glass, alumina, clays and mixtures thereof.
10. The method of claim 2, wherein the particulate inert material is selected from the group consisting of sand, metal shot, plastic polymers, glass, alumina, clays and mixtures thereof.
11. The method of claim 1, wherein said water is heated.
12. The method of claim 11, wherein the temperature of the heated water has a temperature of less than about 100° C.
13. The method of claim 1, wherein said water is steam.
14. The method of claim 1, wherein the core and molded product are immersed in a bath of said water to disintegrate and remove the core.
15. The method of claim 1, wherein said molded product is formed of a material selected from the group consisting essentially of plastics and metals.
16. The method of claim 2, wherein said molded product is formed of a material selected from the group consisting essentially of plastics and metals.
17. The method of claim 16, wherein said silicate is sodium silicate, said water soluble carbohydrate is selected from the group consisting of saccharides and starches, and wherein the core and molded product are immersed in a bath of heated water to disintegrate and remove the core.
18. The method of claim 17, wherein the particulate inert material is selected from the group consisting essentially of sand, metal shot, plastic polymers, glass, alumina, clays and mixtures thereof.
19. The method of claim 19 wherein said binder is cured by heating.
20. The method of claim 19, wherein said heating is by microwave energy.
21. The method of claim 2, wherein said binder is cured by heating.
22. The method of claim 21, wherein said heating is by microwave energy.
23. The method of claim 5, wherein said binder is cured by heating.
24. The method of claim 23, wherein said heating is by microwave energy.
25. The method of claim 9, wherein said binder is cured by heating.
26. The method of claim 25, wherein said heating is by microwave energy.
27. The method of claim 11, wherein said binder is cured by heating.
28. The method of claim 27, wherein said heating is by microwave energy.
29. The method of claim 18, wherein said binder is cured by heating.
30. The method of claim 29, wherein said heating is by microwave energy.
31. The molded product formed by the method of claim 1.
32. The molded product formed by the method of claim 15.
33. The cured core in said discrete configuration as formed by the method of claim 19.
34. The cured core in said discrete configuration as formed by the method of claim 20.
35. The cured core in said discrete configuration as formed by the method of claim 21.
36. The cured core in said discrete configuration as formed by the method of claim 22.
37. The cured core in said discrete configuration as formed by the method of claim 23.
38. The cured core in said discrete configuration as formed by the method of claim 24.
39. The cured core in said discrete configuration as formed by the method of claim 25.
40. The cured core in said discrete configuration as formed by the method of claim 26.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US551,769 | 1990-07-11 | ||
US07/551,769 US5089186A (en) | 1990-07-11 | 1990-07-11 | Process for core removal from molded products |
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CA2046428A1 true CA2046428A1 (en) | 1992-01-12 |
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Application Number | Title | Priority Date | Filing Date |
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CA002046428A Abandoned CA2046428A1 (en) | 1990-07-11 | 1991-07-05 | Core removal from molded products |
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US (2) | US5089186A (en) |
EP (1) | EP0466419B1 (en) |
JP (1) | JPH04232705A (en) |
AU (1) | AU639116B2 (en) |
CA (1) | CA2046428A1 (en) |
DE (1) | DE69125064T2 (en) |
MX (1) | MX9100109A (en) |
NO (1) | NO912716L (en) |
Families Citing this family (50)
Publication number | Priority date | Publication date | Assignee | Title |
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US5262100A (en) * | 1990-07-11 | 1993-11-16 | Advanced Plastics Partnership | Method of core removal from molded products |
US5993716A (en) * | 1990-10-19 | 1999-11-30 | Draenert; Klaus | Material and process for its preparation |
US5830548A (en) | 1992-08-11 | 1998-11-03 | E. Khashoggi Industries, Llc | Articles of manufacture and methods for manufacturing laminate structures including inorganically filled sheets |
US5545450A (en) | 1992-08-11 | 1996-08-13 | E. Khashoggi Industries | Molded articles having an inorganically filled organic polymer matrix |
US5851634A (en) | 1992-08-11 | 1998-12-22 | E. Khashoggi Industries | Hinges for highly inorganically filled composite materials |
US5658603A (en) | 1992-08-11 | 1997-08-19 | E. Khashoggi Industries | Systems for molding articles having an inorganically filled organic polymer matrix |
US5453310A (en) | 1992-08-11 | 1995-09-26 | E. Khashoggi Industries | Cementitious materials for use in packaging containers and their methods of manufacture |
US5506046A (en) | 1992-08-11 | 1996-04-09 | E. Khashoggi Industries | Articles of manufacture fashioned from sheets having a highly inorganically filled organic polymer matrix |
US5800647A (en) | 1992-08-11 | 1998-09-01 | E. Khashoggi Industries, Llc | Methods for manufacturing articles from sheets having a highly inorganically filled organic polymer matrix |
US5508072A (en) | 1992-08-11 | 1996-04-16 | E. Khashoggi Industries | Sheets having a highly inorganically filled organic polymer matrix |
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-
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- 1990-07-11 US US07/551,769 patent/US5089186A/en not_active Ceased
-
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- 1991-06-27 AU AU79382/91A patent/AU639116B2/en not_active Ceased
- 1991-07-05 DE DE69125064T patent/DE69125064T2/en not_active Expired - Fee Related
- 1991-07-05 EP EP91306134A patent/EP0466419B1/en not_active Expired - Lifetime
- 1991-07-05 CA CA002046428A patent/CA2046428A1/en not_active Abandoned
- 1991-07-08 MX MX9100109A patent/MX9100109A/en not_active IP Right Cessation
- 1991-07-10 NO NO91912716A patent/NO912716L/en unknown
- 1991-07-11 JP JP3170861A patent/JPH04232705A/en active Pending
-
1994
- 1994-02-17 US US08/198,141 patent/USRE35334E/en not_active Expired - Lifetime
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US5089186A (en) | 1992-02-18 |
NO912716D0 (en) | 1991-07-10 |
AU639116B2 (en) | 1993-07-15 |
DE69125064T2 (en) | 1997-07-31 |
USRE35334E (en) | 1996-09-24 |
AU7938291A (en) | 1992-01-16 |
EP0466419B1 (en) | 1997-03-12 |
NO912716L (en) | 1992-01-13 |
EP0466419A2 (en) | 1992-01-15 |
DE69125064D1 (en) | 1997-04-17 |
EP0466419A3 (en) | 1992-12-09 |
MX9100109A (en) | 1992-02-28 |
JPH04232705A (en) | 1992-08-21 |
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