US3195184A - Apparatus for making double walled tube - Google Patents

Description

E. F. SVEC APPARATUS FOR MAKING DOUBLE WALLED TUBE Original Filed Dec. 16, 1957 Il lIIIIIIIIIfIIIlIIII/Ill l,

July 20, 1965 United States Patent 3,195,3.8d APPARATUS FR MAKNG DQUBELE WALLED 'EURE Emil Francis Svec, New Yaris, NE.; Viera li/i. Svcs, errecutris: ot said Emil Svcs, deceased, assigner to Flexigrip, luc., New York, NX., a corporation of New York @riginal appiication Esc. 16, w57, Ser. No. 703,033, now Patent No. 3,683,495, dated May 7, i953. Divided and this application Apr. 30, i962, Ser. No. 196,025'

2 Ciairns. (Ci. itl-i4) This application is a division of U.S. application Serial No. 703,033, led December 16, 1957, now Patent No. 3,088,495.

This invention relates to apparatus for making a multi- Walled thermoplastic strip` More specically, this invention relates to apparatus for making 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.

According to certain important aspects of the present invention, there is provided a thermo-plastic 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 4article or articles covered therein against mechanical damage, and against dirt, voil 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 enoase a series of electrical wires and the like.

Accordingly, it is an important object of the present invention to provide apparatus for making a thermoplastic multi-walled strip construction having interlockingly engageable edges for folding the strip into a tube.

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 apparatus for manufacturing a multi-Walled therrno-plastic strip having peripheral edges adapted for interlocked engagement to form the strip into a tube.

Yet another and still further object of this invention is to provide means for extruding a multi-walled thermoplastic strip including 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 l 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 iI-ll of FIGURE l, 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 l@ in FIGURE l 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 hereiniili Patented July 20, i965 "ice after become apparent. In the form in which the strip lil 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 str-ip Iii 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 susbtantially waterand 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 fiat 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 to permit the tube to be flattened out.

As best shown in FIGURE 4, the thickened edge portions il and i3 are identical in cross section but oi'set in opposite directions from the plane of the strip 10 and are adapte-d 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 l5, 15a and ribs to, and ida that extend continuously along the edge portion i2. Two such grooves 15, 15a and two such ribs lo, 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 1S, between which are formed edges i9 that impart to the ribs a hook-like contour. When the closure strips i2 and lf3 are matingly inter-engaged, the edges 1E of the ribs lo, ida are in opposed relationship to resist lateral separation of the edges 12 and 13.

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 l2 and i3. 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 Waterand moisture-tight throughout its extent. Where the article 10 is made of thermoplastic material, the seam S can be permanently closed by cementing (gluing) the edges strips 12 and 13 together along their contacting surfaces.

According to other important features of the present invention, the strip l0 and the tube lll 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 a iirst Wall 2@ which Wall has at its opposite ends the closure strips l2 and I3. A second wall 2l is also mounted on the strip lo and tube il whereby link or hinge portions .Z2-22 are disposed at opposite ends of the Wall 21 and extend transversely with respect to the Walls 220 and 2l and interconnect these walls generally at the area of the closure strips I2 and i3. 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. As will be noted from FIGURE 2, the rst wall 20 lies in a rst plane when the multiple walled strip is lying fiat, and the edge closure strips 12 and 13 lie along the edges of the wall 20.

The second wall 21 is substantially parallel to the iirst wall 2d, and the hinge portions 22 support it in a second plane. This structure also makes it more easy to form adsense Vthe multi-walled unit into a tube. it will be apparent `that the circumferences of the two layers must be difierent, and to accommodate this change when the multiwalled strip is rolled into a tube, the hinge Vportions 22, 22 will bend, permitting the walls to form a circle with- 'out undue stress. This also permits the tube to be rolled vin either direction, and in FIGURE 3 the tube is shown rolled with `the second wall 21 on the inside of the first wall 20. As will be observed, the tube could be rolled in the other direction with the second wall 2l on the outside. This Vcould easily be accommodated in view of the laterally extending hinge portions 22, 22. Any pulling on the second wall portion 2l in the arrangement shown in FIGURE 3 will not result in a direct tensile stress being placed on the first wall 20, since the laterally extending hinge portions 22, 22 can first bend before directV pull is exerted on the first'wall 2t). lt will be noted that the laterally extending hinge portions 22 position the second wall2l with a space between itrand the iirst wall 20. However, if material, such as a bundle of wires, is wrapped which have excess circumference, the second wall 21 can expand to lie against the outer wall 24B due tothe bending of the hinge portions 22, 2322,v without placing Astress on ythe, connection between the rst and second Walls. f Yet, in normal position, a space between the walls and 2l will be maintained due to the resilient stiffness of the hinge portions 22, 22 which position the second wall 21 inwardly of the first wall Ztl. The hinge portions extend laterally from the first and second planes of the first and second walls 20, 2l, andV can be at right angles thereto but are preferably slightly inclined to extend inwardly toward each other so that the length of the first wall 2t) between the hinge portions is longer than the second wall. This permits the hinge portions to bend more easily, and to bend toward a position normal to the walls, when the Strip is rolled into a tube with the second Wall 21 on the inside.

The second wall 2l 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 thetube. This slitting would be along the dot dash line of FIGURE 3.

Accordingfto the method and apparatus aspects of the present invention, an extruder apparatus 25 is provided. Indicated at v26 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 charnber 30h of a head 3l. Disposed in axial alignment with the propeller 28 in the chamber Stib is a molding structure or extruder portion 25a.

The molding structure l25a is preferably comprised of a series of three or more interchangeable blocks or forming die portions 26a, 26h, and 26C. Closure blocks or plates 26a and 26e comprise end blocks and have longitudinally Or axially extending Acavities or grooves therein indicated at 27 and 28 of predetermined configuration for extruding Vthe closure strips or endsof the strip l@ indicated at 12 and l3`in FIGURE 2. l

The central die portion 26h includes a main cavity or pocket area indicated generally at 29 and in which is mounted a separator wall structure or plate 3@ which is suspended or hung within the pocket area 29 by means of a series of extensions 31 which extensions may comprise screws 31a extending through the block 26h into the separator 30 for vertical adjustment of the same within the pocket area 29 for varying the dimensions of the extruded product. in other words the screws 3io may be turned up or down to move the plate Sii up or down and thereby easily simultaneously change the thickness of bot the first and second walls 20 and 2l of the tube. This readily controls the Wall thickness for serving various purposes. As above described, the first wall 20 operates primarily to withstand the lateral stress imposed by the closure strip edges, and the second wall 2l acts as a second Vor outwardly as the situation may demand).

spaced wall and as a cushioning member protecting the first wall and maintaining a space therebetween, with forces applied to the second Wall being withstood by the second wall, and also by the hinge portions Z2 at each end. When a special environment is presented which requires either more or less strength for lateral forces encountered by the first wall 26, or more or less strength for scud resistance or insulating properties or similar require- The present invention contemplates one form of struc-V tnre wherein the walls are of the same thickness. The

invention also contemplates a structure with a first wallV Zti of a first thickness, and a second wall 21 of a heavier thickness to provide betterinsulative qualities and irnproved scuff resistance wherein either the inside orthe outside of the tube is to be subjected to excessive seuilC (the tube is then rolled with the wall 21 facing inwardly The invention also contemplates a tube wherein the first wall 2t) is of a first thickness which is larger than the thickness of the second wall 2l, such as wherein the material must portion 2li of the strip iti or the tube Ill being formed within the cavity 32 and the wall portion 21 of the strip liti or the tube ll Vbeing formed within the wall cavity 33.

Transversely linking the cavities 32 and 33 are trans- -verse link cavities or grooves indicated generally at 34, 34

wherein linking portions 22,22 of the strip lil or the tube il are formed during the extrusion process. It will be noted that the cavity 33 is in alignment with the fastener cavities or grooves Z7 and 23 in the blocks 26a and 26o. 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 Zeb and through the extensions 3l and then into the separator wall structure 3l). A second series of passageways V36 extend through the separator block 39 which passageways are disposed at right angles to the passageways 35. A suitable fiuid such as air is forced through the aligned passageways 35 and 36 from the topside of the block 2611 through Va supply conduit 37 and the fluid is discharged in a direc- The air passing through the passageways may be cooled such as by a cooler 3S to speed up hardening of the ex- Y truded plastic strip upon its discharge.

Recapitulating the process of rny invention, the mass of heated plastic material is initially moved by the screw 2% into the chamber 3@ thereby providing a large mass of plastic material which material is being moved axially against theV molding or extruder portion 25o. The molding` structure 25a operates to divide the mass of heated vthermoplastic material into a series of wall streams and aV series of linking streams by means of the cavity grooves 3:2, 33 and 34 while contemporaneously further molding and undulatingl the thermo-plastic material by means of the cavities or grooves 27 and 28 in the blocks 26a and 26h 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 passageways 35 and 36 preventing the soft pliable linked wall structure from co1- lapsing until the heated thermo-plastic muiti-walled striplike mass is hardened and is formed into a form sustaining multi-wall strip having fastener structure for forming the multi-wall strip into a tubular Wall structure 1l.

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 0r 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 mechanism for extruding a multi-wall sheet having fastener elements at its edges and adapted to be rolled into a tube, the mechanism comprising means defining an extrusion chamber, a central die member having a die Wall with an elongated die opening therein receiving extrudate from the chamber and provided with upper and lower edges deiining outer wall surfaces of the sheet and side edges, edge die members beside the central die member having openings dening the outer surfaces of linking portions joined to the sheet formed by the central die member for joining the walls of the sheet, a plate member supported in said die opening of the central die member and constituting a mandrel having outer surfaces for defining the inner surfaces of the sheet Walls, means for adjustably supporting said plate member for adjusting its position relative to said opening of the central die member so that the thicknesses of said Walls can be simultaneously changed, and means for forcing plastic material into said chamber and through the die openings.

2. A mechanism for extruding a multi-wall sheet having fastener elements at its edges and adapted to be rolled into a tube, the mechanism comprising means defining an extrusion chamber, a central die member having a die wall with an elongated die opening therein receiving extrudate from the chamber and provided with upper and lower edges defining outer wall surfaces of the sheet and side edges, edge die members beside the central die member having openings defining the outer surfaces of linking portions joined to the sheet formed by the central die member for joining the walls of the sheet, a plate member supported in said die opening of the central die member and constituting a mandrel having outer surfaces for defining the inner surfaces of the sheet walls, means for adjustably supporting said plate member for adjusting its position relative to said opening of the central die member so that the thicknesses of said walls can be simultaneously changed, means deiining air emission openings in the edge of said plate member for directing a iiow of air between the walls of the sheet, means for delivering air to said openings, and means for forcing plastic material into said chamber and through the die openings.

References Cited bythe Examiner UNITED STATES PATENTS 1,476,258 12/23 Kroch v13B-55 1,937,069 1l/33 Rado 13S-55 2,583,329 l/52 Eckert 18-55 XR 2,720,679 10/ 55 Ratlif 25-17 XR 2,750,631 l/56 Johnson 18-55 XR 2,748,401 6/56 Winstead. lS-lZ 3,03 8,205 6/ 62 Plummer 18-55 XR 3,103,409 9/63 Bohres et al` 264-209 3,108,851 10/63 Hofer et al. 264-209 ROBERT F. WHITE, Primary Examiner.

MORRIS LIEBMAN, ALEXANDER H. BRODMER- KEL, Examiners.

Claims (1)

1. A MECHANISM FOR EXTRUDING A MULTI-WALL SHEET HAVING FASTENER ELEMENTS AT ITS EDGES AND ADAPTED TO BE ROLLED INTO A TUBE, THE MECHANISM COMPRISING MEANS DEFINING AN EXTRUSION CHAMBER, A CENTRAL DIE MEMBER HAVING A DIE WALL WITH AN ELONGATED DIE OPENING THEREIN RECEIVING EXTRUDATE FROM THE CHAMBER AND PROVIDE WITH UPPER AND LOWER EDGES DEFINING OUTER WALL SURFACES OF THE SHEET AND SIDE EDGES, EDGE DIE MEMBERS BESIDE THE CENTRAL DIE MEMBER HAVING OPENING DEFINING THE OUTER SURFACES OF LINKING PORTIONS JOINED TO THE SHEET FORMED BY THE CENTRAL DIE MEMBER FOR JOINING THE WALLS OF THE SHEET, A PLATE MEMBER SUPPORTED IN SAID DIE OPENING OF THE CENTRAL DIE MEMBER AND CONSTITUTING A MANDREL HAVING OUTER SURFACES FOR DEFINING THE INNER SURFACES OF THE SHEET WALLS, MEANS FOR ADJUSTABLY SUPPORTING SAID PLATE MEMBER FOR ADJUSTING ITS POSITION RELATIVE TO SAID OPENING OF THE CENTRAL DIE MEMBER SO THAT THE THICKNESS OF SAID WALLS CAN BE SIMULTANEOUSLY CHANGED, AND MEANS FOR FORCING PLASTIC MATERIAL INTO SAID CHAMBER AND THROUGH THE DIE OPENINGS.

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