US 3088495 A
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May 7, 1963 E. F. SVEC RIB AND GROOVE FASTENER STRUCTURE Filed Dec. 16, 195'! 25a, /3 ZZ /3 28 3,083,495 Patented May 7, 1963 are 3,033,495 RIB AND GRGUVE FASTENER STRUCTURE Emil Francis Svec, New York, N.Y.; Viera Marina Svec,
exccutrix of said Emil Francis Sven, deceased, assignor to Flexigrip, Inc, New York, N.Y., a corporation of New York Filed Dec. 16, 1957, Ser. No, 793,033 6 Claims. Cl. 138128) This invention relates to a multi-walled thermo-plastic strip and method and means for manufacturing the same. More specifically, this invention relates to a multi-walled thermo-plastic strip including fastener structure disposed along opposite edges of the strip for locking the edges together and forming the strip into a tube, and method and means for manufacturing such a strip.
According to certain important aspects of the present invention, there is provided a thermoplastic tube type strip having interlocking edges with a multi-Wall structure having a plurality of compartments which double walled strip has a number of advantages a few of which are now described. The double wall tube construction provides increased protection for article or articles covered therein against mechanical damage, and against dirt, oil and the like. This double Wall strip structure also has high insulating properties. Double walled tubes of the present type also may be utilized to protectively encase a series of electrical wires and the like.
The present invention further embodies the novel concept of providing a fastener structure for the edge of a strip which may be formed into a tube, having interlocking ribs and grooves which are sloped or angled so that the median planes of the ribs and grooves at an angle, less than a right angle to the plane of the strip so as to increase the resistance to separation of the matingly engaged edge portions when oppositely acting forces are applied to the strip either during the wrapping operation to place the strip in tubular form or after the tube has been formed. In addition, the median planes of the ribs and grooves are preferably angled with respect to one another to further increase the resistance against pull out. Preferably, the hook-like ribs on each edge are angled toward one another with median planes through the ribs converging in a direction away from the tip ends of the hook-like ribs.
Accordingly, it is an important object of the present invention to provide a thermo-plastic multi-Walled strip construction having interlockingly engageable edges for folding the strip into a tube.
Another object of the present invention relates to a novel method of manufacturing a multi-Walled thermoplastic strip.
A further object of the present invention relates to novel apparatus for manufacturing a multi-walled thermoplastic strip.
Yet another object of the present invention concerns a novel method and apparatus for manufacturing a multiwalled thermo-plastic strip having peripheral edges adapted for interlocked engagement to form the strip into a tube.
Another and still further object of the present invention is to provide a tube-forming article and a strip of extended length having thickened edge portions formed with continuously extending ribs and grooves of hookshaped contour in section for locking interengagement to form a tube therefrom, and with the median planes of the axes of the ribs and grooves sloping at an angle with respect to one another and at an angle, other than a right angle, to the plane of the strip in such manner as to increase the resistance to separation of the edge portions when they are interengaged and are subjected to oppositely acting forces tending to effect such separation.
It is a further important object of this invention to provide a tube-forming article and a tube formed therefrom with closure strips that are integral with the sheetlike body of the article and that are of a thickness not more than three times the thickness of the sheet-like body portion, the median planes of the ribs and grooves in the closure strips being sloped in such manner as to make it possible for the closure of the strips to be relatively thinner than heretofore and offer the same or greater resistance to separation once the closure strips are interengaged.
Another and still further but more specific object of this invention is to provide a tube type strip having opposite edges with confronting hook-like ribs and grooves which are inclined away from the end of the strip to resist lateral pull and with the outermost rib on each edge disposed at a reduced angle with respect to the angle of the adjacent inner rib.
Yet another and still further object of this invention is to provide method and means for extruding a multiwalled thermo-plastic strip including method and means for maintaining the walls of the strip separated until they are hardened so they will not collapse upon being discharged from the extruder.
Other and further important objects of this invention will become apparent from the following detailed description and the appended claims, and from the accompanying drawings illustrating a preferred embodiment of this invention, in which like reference numerals refer to like parts and in which:
FIGURE 1 is a fragmentary, partly cross-sectioned, extruder device shown extruding a strip, according to the features of the present invention;
FIGURE 2 is an enlarged fragmentary cross-sectional view taken substantially on the broken section line I I-11 of FIGURE 1 looking in the direction indicated by the arrows;
FIGURE 3 is a fragmentary perspective view of a multi-walled thermo-plastic strip provided with interlocking edges, according to certain features of the present invention; and
FIGURE 4 is an enlarged fragmentary end elevation of the interlocked edges of the double-Walled tube shown in FIGURE 3.
The reference numeral 10 in FIGURE 1 indicates generally an extruded double-walled strip and the reference numeral 11 in FIGURE 3 indicates generally the strip 10 folded into tubular form in a manner which will hereinafter become apparent. In the form in which the strip 10 would be sold, it may be a flat strip of extended length, capable of being bent transversely into the tube 11, or being wrapped about smaller tubes, cables or the like into the seamed tube-form shown in FIGURE 3.
The strip 10 is preferably a strip of relatively thin, flexible material, suitably formed from a plastic such as vinyl polymer or copolymer, as for instance, polyvinyl chloride, or from polyethylene, or other substantially water-and moisture-proof plastic material having high dielectric strength and suitable strength against being torn or ruptured despite its relative thinness.
According to the present invention, the strip is preferably extruded flat in a manner which will hereinafter be described in detail although it will be appreciated that the tube could be extruded initially in tubular form, with the tube then being severed between the thickened edge portions 12 and 13 to permit the tube to be flattened out.
As best shown in FIGURE 4, the thickened edge portions 12 and 13 are identical in cross section but offset in opposite directions from the plane of the strip 10 and are adapted to confront each other when overlapped and formed into a tube. Since the closure strips 12 and 13 are otherwise identical, only one need be described. A closure strip is provided with alternating, adjacent grooves 15, 15a and ribs 16, and 16a that extend continuously along the edge portion 12. Two such grooves 15, 15a and two such ribs 16, 16a are shown, although a greater number of grooves and ribs can be used if desired. The ribs and grooves are complementally formed and the ribs are provided with enlarged head portions 17 and restricted neck portions 18, between which are formed edges 19 that impart to the ribs a hook-like contour. When the closure strips 12 and 13 are matingly interengaged, the edges 19 of the ribs 16, 16a are in opposed relationship to resist lateral separation of the edges 12 and 13.
In accordance with my present invention, instead of the median planes of the ribs and grooves being at right angles, or perpendicular, to the web of the strip on which the closures are formed or to which the closures are attached, the median planes of the ribs 16, 16a and those of the grooves 15, 150 are at an angle less than 90. The median planes through the height axes of the ribs 16, 16a and through the depth axes of the grooves 15, 15a are shown in FIGURE 4 by the dot and dash lines M, M. When the edge portions 12 and 13 are inter-engaged as shown in FIGURE 4, the hook-like ribs of the strip lie in planes that are slightly offset from each other as with respect to the parallel planes indicated by the dotted lines M", M, disposed along the outer edge surface of the adjoining edge portions 12 and 13. The angle referred to as indicating the slope of the height axes of the ribs is the acute angle formed between the plane lines M, M and M, M and these angles, should, preferably, lie between 65 and 85. For illustration, the rib 16 may be inclined at an angle between 65 and 75, the rib 16:: may be inclined at an angle between 75 and 85 and the rib 16a may have a greater heighth than the rib 16. Since the hook-like ribs 16, 16a, slant inwardly toward the strip when the strip is viewed endwise, and further since the ribs 16, 16a converge towards one another in a direction away from the hook like rib side of the edge portion 12 or 13, the effect of so slanting and converging the ribs is to increase the resistance of the inter-engaged edge portions 12 and 13 to separation when they are subjected to oppositely acting forces applied through the strip and tending to pull the edge portions apart.
One of the disadvantages of heretofore known plastic fasteners is the fact that the thickness of the closure strips, or edge closure elements, must be unreasonably great in comparison to the thickness of the webs on which said closure elements are formed, or in comparison to the thickness of the material used for the article itself. By the provision of the sloping ribs and grooves as herein illustrated and described and wherein the ribs converge toward one another with the rib 16 having a greater height than the rib 16a, it is entirely possible to obtain the same resistance to separation of the closure elements while keeping the thickness of the thickened edge portions with which said elements are formed not over three times the thickness of the main body of the strip, and preferably not over about 2 or 1 /2 times. Thus by employing sloping ridges and grooves, as shown, adequate strength is obtained without the necessity of greatly thickened edge portions, and with a consequent saving in material as a result of the decrease in the thickness of the seam, indicated by the reference numeral S, that is formed when the article 10 is bent into tubular form.
In view of the foregoing it will now be appreciated why conventional type projections on flat strips have not been found to be particularly well suited for application to a strip to be formed into a tube by interlocking edge projections and grooves. For the mos-t part, such projections normally used on flat strips, when used on tubes, have a tendency to pull out when engaged together due to the fact the conventional projections are disposedat right angles or are angled in the direction of lateral pull. In this connection it will be noted that when a standard fastener is bent lengthwise the two strips have a tendency to slide, one against the other, with the ends of the underneath strip protruding against the ends of the upper strip. The reason for this is that the strips are bent with different radii. However, when the ends of the strips are sealed together, they cannot slide any more; yet the material of the lower strip has to move when subjected to a bending force. As long as there is a sufficient clearance between the teeth of the engaged strips, or .suflicient clearance between the heads of the ridges and the corresponding grooves, the standard fastener will not come apart. However, the dimensions of these clearances are (for other considerations) limited. Therefore, when the conventional fastener is being bent, and as soon as these clearances are filled up, each groove is forced and begins to widen and open up side wise enabling the ribs to disengage from the grooves.
The hook-like ribs herein disclosed are of special construction to resist pull out since the ribs are both angled in the same direction, inclined against lateral pull. Moreover, as mentioned above, these angles are not equal, since the angle on the outer rib is less than the angle on the inner rib. This construction enables the ribs on one strip to establish a pincer-like grip with the rib on the other strip, like a talon. This relationship not only increases very considerably the resistance of the interengaged strips against lateral pull out, but also makes the closure water tight.
In summary, only projections or ribs with different dimensions will overcome the defects of operation described above. A tube formed with ribs as herein shown will not open up when bent in any direction even as a spiral.
Closure of the tube to form the seam S can be effectuated manually by incrementally pressing together successive portions of the confronting closure elements of the edge portions 12 and 13. While a slider can be used for the purpose it is preferable to take the slider away, once the closure elements are engaged, since then the seam S will be substantially water-and-moisture tight throughout its extent. Where the article 10 is made of thermo-plastic material, the seam S can be permanently closed by cementing (gluing) the edge strips 12 and 13 together along their contacting surfaces.
According to other important features of the present invention, the strip 10 and the tube 11 are provided with a multi-walled construction which is here illustrated as a double walled form of my invention since additional walls may be readily formed without departing from this invention. The double wall construction includes an outer wall 29 which wall has at its opposite ends the closure strips 12 and 13. An inner wall 21 is also mounted'on the strip 10 and tube 11 whereby link portions 2222 are disposed at opposite ends of the wall portion 21 and extend transversely with respect to the walls 20 and 21 and interconnect these walls generally at the area of the closure strips 12 and 13. This double walled strip construction when utilized as a tube provides increased protection for articles covered therein against mechanical damage, and against dirt, oil and the like. This double wall strip structure also has high insulating properties.
The inside wall portion 21 can be slit-lengthwise, at any suitable place along the entire length of the wall portion to create two flaps which may be used either to wrap two bundles of wire, each separately, or to use one of the flaps to cover the closure inside of the tube.
According to the method and apapratus aspects of the present invention, an extruder apparatus 25 is provided. Indicated at 26 is a discharge end of a heated extrusion cylinder, in which heated plastic material 27a is fed by a screw 28 through a discharge opening 29 into a chamber 3t) of a head 31. Disposed in axial alignment with the propeller 28 in the chamber 3t) is a molding structure or extruder portion 25a.
The mOlding structure 25a is preferably comprised of a series of three or more interchangeable blocks or forming die portions 26a, 26b, and 260. Closure blocks or plates 26a and 260 comprise end blocks and have longitudinally or axially extending cavities or grooves therein indicated at 27 and 28 of predetermined configuration for extruding the closure strips or ends of the strip indicated at 12 and 13 in FIGURE 2.
The central die portion 26b includes a main cavity or pocket area indicated generally at 29 and in which is mounted a separator wall structure 30 which is suspended or hung within the pocket area 29 by means of a series of extensions 31 which extensions may comprise screws extending through the block 26b into the separator 30 for vertical adjustment of the same within the pocket area 29 for varying the dimensions of the extruded product. The main pocket area 29 is defined at its periphery by a peripheral surface 29a (FIGURE 2) and the separator wall structure is defined atits periphery by a peripheral surface 30a whereby these surfaces 29a and 3th: cooperate together to define superimposed wall cavities or grooves 32 and 33 with the wall portion Zti of the strip lit or the tube 11 being formed within the cavity 32 and the wall portion 21 of the strip It} or the tube 11 being formed within the wall cavity 33.
Transversely linking the cavities 3'2 and 33 are transverse link cavities or grooves indicated generally at 34, 34 wherein linking portions 22, 22 of the strip 10 or the tube 11 are formed during the extrusion process. It Will be noted that the cavity 33 is in alignment with the fastener cavities or grooves 27 and 28 in the blocks 26a and 26a. In manufacturing a double wall strip one of the major problems faced was how to keep the walls apart after extrusion until they harden. To solve this problem, a fluid system has been developed.
To this end, a series of passageways 35 extend vertically downwardly through the block 26b and through the extensions 31 and then into the separator wall structure 34). A second series of passageways 36 extend through the separator block 30 which passageways are disposed at right angles to the passageways 35. A suitable fluid such as air is adapted to be forced through the aligned passageways 35 and 36 from the top side of the block 26b whereby the fluid is discharged in a direction axially away from the screw 28 out through the openings or passageways 36 through the separator block 30 so that as the linked wall structure or strip 10 is discharged from the block 26b, the fluid will operate to maintain the superimposed walls 20 and 21 out of contact with one another until the walls are sufiiciently solidified so that the wall structure will not collapse or become damaged upon discharge from the extruder portion 25a. The air passing through the passageways may be cooled to speed up hardening of the extruded plastic strip upon its discharge.
Recapitulating the process of my invention, the mass of heated plastic material is initially moved by the screw 28 into the chamber 30 thereby providing a large mass of plastic material which material is being moved axially against the molding or extruder portion 25a. The molding structure 25a operates to divide the mass of heated thermoplastic material into a series of wall streams and a series of linking streams by means of the cavity grooves 32, 33 and 34 while contemporaneously further molding and undulating the thermo-plastic material by means of the cavities or grooves 27 and 28 in the blocks 26a and 26b to provide fastener strips 12 and 13 at opposite ends of the wall portion 21.
As the same is passed through the molding structure 25a the relatively soft and pliable mass is formed to shape. The coolant which may comprise a cool air stream is directed through the pasageways 35 and 36 preventing the soft pliable linked wall structure from collapsing until the heated thermo-plastic multi-walled striplike mass is hardened and is formed into a form sustaining multi-wall strip 10 having fastener structure for forming the multi-wall strip into a tubular wall structure 11.
Through the use of the present method and apparatus the thickness of the web on which the ribs are mounted may at all times be kept to a minimum since there is no film or sheet to be welded to them as is the case with some of the conventional fasteners and a three piece tube may be in this manner avoided. Reducing the width of the web is of particular importance on tubes in reducing manufacturing cost, but further since when thin webs are used, the pliability of the tube becomes dependent upon the pliability of the wall as opposed to the pliability of the web where a thick web construction is used.
By utilizing a multi die-block construction, the die blocks can be used in a great many set ups without necessitating new die blocks and manufacturing costs may be thereby kept to a minimum.
It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.
I claim as my invention:
1. A one piece multi-wall tube, comprising flexible tubular strip structure of extended length having spaced wall portions with the spaced wall portions being joined together by linking wall spacers integral with the wall portions, said flexible strip structure having fastener structure at opposite ends of one of the wall portions each fastener structure including complemental edge structure having inclined adjacent ribs and grooves extending along the strip length which ribs and grooves are hook-like in contour in section and in detachable locking inter-engagement together forming a multi-wall tube, the median planes of said ribs and grooves sloping at an angle to the plane of said strip such that the hook-like ribs slant in the direction of their free ends inwardly toward the tubular strip structure to increase the resistance to sep aration of the interengaged fastener structures, said tubular strip structure inclusive of said fastener structures being integral and composed of a substantially waterand moisture-proof plastic material having high dielectric strength.
2. A one piece multi-wall tube comprised of flexible tubular strip structure of extended length having spaced wall portions with the spaced wall portions being joined together by linking wall portions, said multi-wall flexible strip structure having fastener structure including edge structure at opposite ends having adjacent complementally formed ribs and grooves with adjacent ribs inclined toward each other, said ribs and grooves extending along the strip length in locking inter-engagement together, said strip structure being integral and composed of a substantially water-and moisture-proof plastic material having high dielectric strength.
3. A one piece multi-wall tube comprised of flexible tubular strip structure of extended length having spaced wall portions With the spaced wall portions being joined together by linking wall portions, said multi-wall flexible strip structure having fastener structure including edge structure at opposite ends having adjacent complementally formed ribs and grooves with adjacent ribs inclined toward each other, said ribs and grooves extending along the strip length in locking inter-engagement together, said strip structure being integral and composed of a substantially water-and moisture-proof plastic material having high dielectric strength, said wall portions and said linking wall portions defining the periphery of a chamber extending along the length of the tube.
4. A fastener structure for the edges of a strip to be formed into a tube or the like comprising a closure strip having a linking portion at one side for joining in a coplanar relationship with a strip, and having a plurality of ribs with grooves adjacent the ribs with said grooves having a shape substantially complemental to the ribs to receive other ribs of substantially the same shape, said ribs and grooves situated with their median planes slanting toward each other for a pincer-like grip to increase the resistance to separation when attached to another closure strip.
5. A fastener structure for the edges of a strip to be formed into a tube or the like comprising a closure strip having a linking portion at one side for joining in a coplanar relationship with a strip, and having a plurality of ribs with grooves adjacent the ribs with said grooves having a shape substantially complemental to the ribs to receive other ribs of substantially the same shape, said ribs having a hook-like contour with inwardly facing surfaces at one side, said ribs and grooves situated with their median planes slanting toward each other for a pincer-like grip to increase the resistance to separation when attached to another closure strip.
6. A fastener structure for the edges of a strip to be formed into a tube or the like comprising a closure strip having a linking portion at one side for joining in a coplanar relationship with a strip, and having a plurality of ribs with' grooves adjacent the ribs with said grooves having a shape complemental to the ribs to receive other ribs of the same shape, said ribs and grooves situated with their median planes slanting toward said linking portion to increase the resistance to separation when attached to another closure strip, the outermost of said ribs with respect to said linking portion having an inclination to extend toward its adjacent rib for a pincer-like grip.
References Cited in the file of this patent UNITED STATES PATENTS 400,094 Limont Mar. 26, 1889 1,476,258 Kroch Dec. 4, 1923 1,937,069 Rado Nov. 28, 1933 2,512,844 Weber June 27, 1950 2,519,375 Jargstorfi' et a1 Aug. 22, 1950 2,558,367 Madsen June 26, 1951 2,748,401 Winstead June 5, 1956 2,750,232 Szantay et a1. June 12, 1956 2,756,172 Kidd July 24, 1956 2,791,807 Marin May 14-, 1957 2.931664 Plummer May 24, 1960
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