US2592336A

US2592336A - Machine and method for forming collapsible tubing

Info

Publication number: US2592336A
Application number: US80675A
Authority: US
Inventors: William E Rejeski
Original assignee: Wiremold Co
Current assignee: Wiremold Co
Priority date: 1949-03-10
Filing date: 1949-03-10
Publication date: 1952-04-08
Anticipated expiration: 1969-04-08

Description

April 8, 1952 w. E. REJESK] MACHINE AND METHOD FOR FORMING COLLAPSIBLE TUBING 4 Sheets-Sheet 1 Filed March 10, 1949 f'cr/nfor- WtCliarnEReieski April 8, 1952 w. E/REJESKI 2,592,336

I MACHINE AND METHOD FOR FORMING COLLAPSIBLE TUBING Filed March 10, 1949 4 Sheets-Sheet 2 2 J-CONvo CONvo April 8, 1952 w. E. REJESKI 2,592,336

MACHINE AND METHOD FOR FORMING COLLAPSIBLE TUBING Filed March 10, 1949 4 Sheets-Sheet 5 g 49 6 8Q HO 6 e [Tu/M TVZQamEReiesTfc' Aprll 8, 1952 w REJESK] 2,592,336

MACHINE AND METHOD FOR FORMING COLLAPSIBLE TUBING Filed March 10, 1949 4 Sheets-Sheet 4 Patented Apr. 8, 1952 UNITED .MACHINE AND METHOD FOR FORMING CGLLAPSIBLE TUBING William E. 'Reje'ski, Hartford, Conn, ass'ignor to The Wiremo'ld Company, Hartford, 'Oonm, a corporation of Connecticut Application March 10, 19.49, Serial No. 80,675

I Bil-Claims.

This invention relates to methods and machines for making tubing and more particularly fiexible and collapsible two-element tubing.

It is an object of this invention to provide an improved method of combining the elements composing the tubing and thereafter forming the tubing of the combined elements in such a way that when the tubing is collapsed, 'the'ilexible element or fabric will Ifold outwardly and hence not impede the passage of air or "fluid through the tubing as is the case when the flexible material or fabric folds inwardly Another object is to provide a machine .tior carrying out the new method and for producing the new tubing.

Another object of the invention is to provide a machine and .method for combining the elements of collapsible tubing in such a way as tozre'quire the use of a less amount of metal than heretofore has been necessary.

Other objects and advantages of the invention will become apparent as it is described in connection with the accompanying drawings.

'In the drawings:

Fig.1 is a fragmentary perspective view partly in section of a portion of a'machine for making the improved tubing and for carrying out my novel method for forming theltubirig,

.Fig- 2 is a plan view partly broken away and partly in section, of a machine assh'own in Fig. 1 embodying the invention;

lFigfiB is an end view or themachine illustrated in Fig.2 but with the fabric guide removed:

'Fig. 4 is a detail view showing in bottom plan the endfp'or'tio'n oithefabric'guide;

Fig. 5 is an end view or the "fabric guide illustrated in Fig. 4;

Fig. 6 *is a fragmentary "view partly-in section of the mandrel and pressure roils'acting'upon'the second and third 'convolutions of tubing being :formed 'accordingto'th'e invention;

Fig.6! is atop plan viewpartly in section o'fthe pressure rolls and -their adjusting mechanism associated'withtheir driving mechanism;

Fig. 8 is a transverse section view taken a'l'on'g pinching roll and 'itsmountin Fig. 12 is a section 'view 'o'i'another form-of tubing which can be made by the invention,

"This invention is an improvement upon the machine and method disclosed in the application of A.'E. Ch'ernack, S. N.'705;O39,"filed October -23, 1946, for Method and Machine 'for Forming'Tubing," Patent Number 2,539,814.

' Referring to the drawings, a strip of thin sheet metal 20 which preferably is preformed by any "suitable means into channel shape by having its opposite "edges bent into acute angles to form flanges 2| and 22, is fed to a rotating mandrel (designated generally by 30) and rotary bending and pinching rolls (designated generally by 45 and and is guided in an advancing spiral path by a *guideway "42 in a'g-uide block liL-aswill hereinafter more particularly be described.

The cylindrical mandrel 30 is formed on a 1'0- "tatin'gsha ft 28 extending through the guide block 40. The mandrel 30 also extends through the guide "block 48 and is held in place on the rotating shaft 28 by means of a key (not shown) :and bolt 34, so as to rotate'with shaft 28.

'The guide block so is a machined casting mounted on a stationary casting 43 which may in turn be mounted upon asu'itable machine frame not shown. 'The guide block-ln has a spiral guideway -42, rectangular in cross-section, out into its vertical iac'e around and adjacent the mandrel 311 to receive the tra l-ling edge 'z'z-cr the-preformed channel strip 20. The pitch of the guideway depends upon the desired advance cf the channel 'striplil.

To guide the -:opposite side of the channel strip. a spiral guiding member or r ib 3 5 is affixed :at :one e'ndby a screw 3-! upon-an extension- 240f :the guide block til, thesur face of the extension being horizontal and-substantially tangential to the top of the 'mandrelell. After the guide'rib 35 :has

"wound about one and one quarter turns :around the mandrel, it terminates. .Starting :from the center line-ofthe mandrel at the top, :its leading edge tapers toward the trailing edge to :such extent that'the guide would :terminatein a point if continued to the point of contact of the pressure rolls with the channel strip. .However, .so as to avoid a weak end-point, 'Zthe guide .rib :is trunca'ted between saidpointand the top nf-theimandr'el. The-effect of this tapering of the guiderib 35 is to guide the movement of the third convolution of the preformed metal strip over .next to the second convolution, as hereinafter will .be more fully-described.

In order to inserta-strip FS of cloth or fabric or other flexible material, .a guide member designated generally by the numeral 10 is fixedly positioned above the ma-n'dre'l lby a supporting by bolts 8i.

bracket 12 which may be attached to a fixed part (not shown) of the machine. This cloth guide is generally of inverted channel form, converging at its end portion over the top of the mandrel, as will be described. The fabric guide is or may be curved upwardly toward the entrance end. At the entrance end the guide has side flanges I I, 13 substantially perpendicular to the roof of the guide and extending downwardly. As the guide proceeds toward the exit end, the flange II carrying the forward edge of the fabric is bent into an acute angle or curved reversely toward the mandrel so as to tuck the fabric under the trailing edge of the second convolution of the metal strip on the mandrel. The opposite flange 13 of the guide, which carries the trailing edge of the fabric strip, is or may be bent into an oblique angle or curved on a radius outwardly so as to tuck the trailing edge of the fabric strip FS-under the trailing flange 22 of the metal strip 20 at about the point where the metal strip enters the spiral guideway 42 of the guide block 40.

Sometimes it is desirable that the fabric guide 10 be provided with a bottom wall. It may be in the form of a strip of sheet metal 15 welded to the edges of the guides flanges II, 13. At about the point where the guide starts to converge to the exit end, an extension 16 which is or may be relatively springy, is secured to or made integral with an extension of the bottom 15.

With the cloth inserted in the first and second convolutions of the metal channel strip 20, the trailing edge of the second convolution will have two layers of fabric under its flange. In that condition the fabric strip and the metal channel are fed around the mandrel to the first or bending roll 90.

Referring to Figs. 7 to 10, support for the bending and pinching rolls is afiorded by a cast head 52 which is formed with a vertical flat face 53, bearing against a flat vertical face on a standard 60 on which it is adjustably secured The standard 60 may be a casting having a horizontal portion 65 resting on and secured to the machine frame II in a suitable manner.

Formed integral with the head 52 are parallel side members 52a and 52b which project forwardly from the'head 52 at opposite sides of the standard 60 and are provided with horizontal parallel open slots in which are movably mounted the ends of a rectangular shaft housing 66. Journalled in the housing 66 is a shaft 68 which projects from both ends of the housing and has aflixed on one end thereof a drive gear 69. On the other end is mounted the pinching roll 45 which adjustably carries the bending roll 90. The gear 69 is driven by suitable driving mechanism which is or may be similar to that illustrated in the application of A. E. Chernack S. N. 705,039, filed October 23, 1946, now Patent 2,539,814.

The shaft housing 66 is provided with a vertical circular opening, in which is mounted an annular bushing 18, having snugly fitted therein the cylindrical lower end of a pin 19. The pin 19 has a flattened body portion snugly fitting in slot 80 in the upper portion of the side member 5212. At its upper end the pin 19 is attached to a plate 8| which bears upon the top surface of the side member 521) and is adjustably secured thereto. The adjustment is accomplished by bolts 82 extending through slots 83 in the plate 8i and engaging in threaded openings in the upper portion of the side member 52b. This method of securing the shaft housing 66 permits of adjusting the main shaft housing in the horizontal slots in the side members 52a, 52b and also permits of a pivotal movement of the housing about the lower cylindrical end of the pin 19 as an axis.

Aifixed by bolts and pins 841) to the shaft housing 66 is a spring-bearing bracket 84. The bracket 84 has a circular bore for a coil compression spring 81. The opposite end of this spring and its shank is housed in a spring-housing member 86 which may be ailixed to the side member 52a in any suitable fashion and may have an adjustment screw 88 for varying the tension of the spring.

In this manner the pressure of the whole pinching roll assembly against the mandrel, more particularly against the metallic strip member of the tubing, can be regulated.

The bending and

pinching rolls

90 and 45 are side by side. Roll 45 is mounted upon the rotating shaft 68 whose axis is parallel to the axis of the mandrel and roll 90 is driven by roll 45 as more fully described below. The axis of the roll shaft 68 is or may be at about the same level as the axis of the mandrel, the details of the mounting rolls being described in detail below. 7

The roll 45 has a hub 41 mounted upon the .shaft 68 and keyed thereto by a key 48, a nut '49 on the threaded end of the shaft serving to hold the roll in place.

The roll 90 is mounted upon a mounting bracket designated generally by the numeral I00. The bracket I00 has a U-shaped portion with arms IOI, I02 embracing the end portion of the shaft housing 66. In this portion of the housing 66 are grooves or guideways 66g which are parallel and located on opposite sides of the housing 66. Into these guideways extend guide pins I04 so as to guide the movement of the bracket I00 relative to the housing. To secure the bracket I00 in the desired adjusted position, set screws I03 extending through the arms of the bracket into the guideways are provided. Extending toward the end of the shaft 68 from the U-portion of the bracket I00 is a bearing portion having a flange part I06 from which extends a sleeve part I0I. These parts I06 and I0! may, if desired, be a separate member bolted to the U-portion of bracket I00. A hub portion ofthe roll 90 is mounted upon the sleeve portion I01 on the bracket member I00, there being provided a bearing 96 therebetween.

In order to drive the roll 90 from the roll 45, a pin 91 is mounted in the roll 90 and extends laterally therefrom into an elongated radial slot in the roll 45. Thus as the roll 45 is turned by its shaft 68, it carries with it by reason of the pin and

slot connection

46, 91, the roll 90 which thus revolves on the sleeve portion III! of the bracket.

For the purpose of adjusting the roll 90 relative to the roll 45, the internal diameter ofthe bracket sleeve I01 is greater than the hub 41 of the roller 45. An adjustment bolt H0 is mounted in an extension or arm 84a of the spring support member 84. This adjustment bolt extends through the transverse part of the bracket member I00 in a sliding fit. For that purpose the end portion of the bolt I I0 may be of reduced section and without screw threads. A diametrical pin H2 is provided in the end of the escapee inside surface of the bracket I to move the bracket in one direction. Upon rotation of the adjustment bolt H0 in the other direction, the shoulder formed at the reduction of the end portion of the adjustment bolt will engage the outer side of the bracket to move the bracket in the other direction.

The first or bending" roll '90 has two circumferential surfaces 91. 92, one '(-9I being of less diameter than theother "(-92). The'first surface #91 ni'erely bends the trailing edge 22 of the second convolution of the metal strip 'downward'but does not pinch it as tightly as .possible. It bends the trailing edge merely to hold the fabric'edges under the trailing flange. The second surface 92 of the first pressure roll acts upon the forward edge 2| of the metal strip and pinches the forward flange down tightly against the body of the strp. Adjustment of this roll by the means above described enables surfaces 9| and 92 to be properly located relative to the second pressure roll 45.

The second pressure roll 45 has but one cir- 'cumferential surface. It acts upon the trailing flange of the metallic strip in the third convolution and pinches it down tightly to hold the fabric between the body of the strip and the underside of the flange 22. w

By reason of the tapering of the forward edge of the guide rib 35, the third convolution of the metal strip is guided by said edge as the strip is moved toward the second convolution (as illustrated best in Fig. 6) by the back pressure of the roll 45. acting on the metal strip as it presses thereon.

The movement of the third convolution toward the second causes a folding of excess fabric over the forward edge 2| of the metal strip in the third convolution. Thus when the second pressure Iroll acts upon the third convolution to press down or pinch the trailing edge of the metal strip, it will at the same time pinch this folded fabric. As a result of this pinching, the fabric will always tend to fold outwardly when the finished tube is expanded and compressed.

In the foregoing description and in Figs. 1 to 6 of the drawings, certain of the parts have been shown enlarged for the sake'of clarity, the invention being more readily understandable with such parts as the metallic strip 20., the guide 35 and the fabric strip FS enlarged, than if said parts were shown in exact proportion to the other parts of the machine as they appear in actual practice.

-It is also possible to form the bending and pinching rolls as a unit, though under such conditlons the adjustability of the surfaces of the roll is surrendered. A unitary roll is illustrated in Fig. 11, wherein similar reference numerals are applied to similar parts. The rollis mounted on the'shaft B8 and caused'to turn therewith by 'akey. The circumferential surfaces ii and I92 acting on the second convolution of the metal strip like the surfaces 9|, 92 of the previously described roll 98 and the circumferential surface 145 acting on the third convolution like the surface of the previously-described roll 45.

It may sometimes be desirable to tuck, a reversely folded forward edge of the fabric under the trailing edge of the second convolution of the metal strip as illustrated in Fig. 12 to more securely hold the fabric edges. Hence the invention is hot limited to tucking a single thickhess-edge, nor a double reversely folded edge;

neither is it limited to a metal strip having a reversely-bent fla'n'ge 2| on its forward edge, since said flange may. if desired, be omitted. The invention may also be applied to a preformed metalstrip having its trailing edge serrated as disclosed in my co-pending application, S. N. 78,-135 entitled "Collapsible Tubing" flle'd February 24, 1949, issued concurrently herewith and claiming tubing of the sort described herein.

Mariy modiflcatlons of this invention will octo those skilled in the art. Therefore I do not limit it to the specific embodiments shown and described.

What is claimedls: l. The method of -forming collapsible tubing comprising forming 'aspiralled convolution from a preformed strip of metal having at least "one edge bent to form a flange, inserting one edge of a strip of flexible material under one flange of said metal strip during the formation of said convolution, inserting the other edge of said flexible strip under said one fla'nge during "the formation of a succeeding convolution, and pressing down said one flange of the metal-strip on the inserted edges of the flexible strip.

2. The method of forming collapsible tubing comprising-forming a spiralled convolution from a preformed strip of metal having its edges bent to form flanges, inserting one edge of a strip of flexible material under one of -the edge flanges of said metal strip during the formation of said convolution, inserting the other edge of said flexible strip under said one flange during the formation of a succeeding convolution, pressing of said metal strip.

'3. The method of forming collapsible tubing comprising forming a spiralled convolution from a preformed strip of metal having its edges bent to form flanges, inserting one edge of "a strip of flexible material under one of the edge flanges of said metal strip during the formation of said convolution, inserting the other edge of said flexbie strip-under said one "flange during the formation of a succeeding convolution, and pressing down the other flange of said metalstrip simultaneously with the pressing down of said one 4. The method of forming collapsible tubing comprising forming a spiralled convolution from a preformed strip of metal having "at least -one edge bent to form a flange ,'insertin'g one edge of a strip of flexible material under one flange of said metal strip during the formation of said c i'on'volution, folding over'the other edge of said flexible strip upon itself and inserting said folded edge over the flexible strip and under said one flange during the formation of a succeeding cohvolution, and pressing down said one flange of the metal strip on the inserted edges of the flex-ie a 5. The method of forming collapsible tubing comprising forming a spiralled convolution from a preformed strip of metal having its edges bent to form flanges, inserting one edge of a strip of flexible material under one of the edge flanges of said metal strip during the formation of said convolution, folding over the other edge 'of said flexible strip upon itself and inserting said folded edge under said one of the flanges during the formation of a succeeding convolution, and pressmg down said one of the ilanges or the metal strip 1 on the inserted edges of the flexible strip, and simultaneously with the pressing down of said .one of the flanges of the metal strip, pressin down the other flange of said metal strip.

6. The method of forming collapsible tubing comprising forming a spiralled convolution from a preformed strip of metal having at least one edge bent to form a flange, inserting one edge of a strip of flexible material under one flange of said metal strip during the formation, of said convolution, inserting the other edge of said flexible strip under the same flange of said metallic strip as the first-mentioned edge of the flexible strip during the formation of a succeeding convolution, and pressing down said same flange of the metal strip on the-inserted edges of the flexible strip to hold them during the formation of said succeeding convolution, and pinching said same flange onto said edges of the fabric strip on forming a third convolution.

7. The method of forming collapsible tubing comprising forming a spiralled convolution from a preformed strip of metal having at least one edge bent to form a flange, inserting one edge of a strip of flexible material under one of the edge flanges of said metal strip during the formation of said convolution, inserting the other edge of ,said flexible strip under the same flange of said metallic strip as the first-mentioned edge of the flexible strip during the formation of a succeeding convolution, creating outside the tubing a folded excess of material of said flexible strip between said first formed convolution and the succeeding convolution while advancing them,

and pinching said fold, and pressing down said same flange of the metal strip on the inserted edges of the flexible strip.

8. The method of forming collapsible tubing comprising forming a spiralled convolution from a preformed strip of metal having at least one edge bent to form a flange, inserting one edge of a strip of flexible material under one of the edge flanges of said metal strip during the formation of said convolution, inserting the other edge of said flexible strip under the same flange of said metallic strip as the first-mentioned edge of the flexible strip during the formation of a succeeding convolution, and creating outside the tubing a folded excess of material of said flexible strip between said first formed convolution and the succeeding convolution while advancing them, and pinching said fold while pressing down said same flange of the metal strip on to the inserted edges of the flexible strip.

9. The method of forming collapsible tubing comprising forming a spiralled convolution from -a preformed strip 'of metal having at least one edge bent to form a flange, tucking the opposite edges of a flexible strip under the flange of the trailing edge of the metal strip in adjacent convolutions, folding over excess material of said fabric strip on the outside of the tubing and pinching the fold of said excess and simultaneously bending said trailing edge flange to secure the edges of said flexible strip to said metal strip.

. 10. The method of forming collapsible tubing tions, folding said excess, and pinching said fold while bending said trailing edge flange to secure the edges of said flexible strip to said metal strip.

11. In a machine for forming collapsible tubing from a preformed strip of metal having at least one edge bent to form a flange, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip under the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, and means to press said trailing flange onto the inserted edges of flexible strip in said second convolution.

12. A machine as claimed in claim 11 wherein said pressing of the flanges serves to temporarily hold the flexible strip, and means to pinch down said flange and firmly secure said flexible strip edges during the formation of a third convolution.

13. A machine as claimed in claim 11 wherein the means to form spiralled convolutions comprises a rotary mandrel, and stationary means to guide the metal strip during the formation of the convolutions in the course of forming the tubing, one of said guide means serving to guide one convolution toward another.

14. A machine as claimed in claim 11 having means to guide one convolution toward a succeeding convolution creating an excess of folded material of said flexible strip therebetween on the outside of the tube, and means to pinch the fold.

15. A machine as claimed in claim 11 having means to guide one convolution toward a, succeeding convolution creating an excess of folded material of said flexible strip therebetween on the outside of the tube, and means to pinch the fold and simultaneously to press down said trailing flange onto the inserted edges of the flexible strip.

16. In a machine for forming collapsible tubing from a preformed strip of metal having at least one edge bent to form a flange, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip under the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip in a second convolution, and means to bend down said trailing flange to hold the edges of the flexible strip during formation of a second convolution, means to guide toward the second convolution the metallic strip as it advances thus creating an excess of folded material of said flexible strip outside the tubing, and means to pinch the fold and to pinch down the flange to securely hold the edges of the flexible strip. I I i 17. In a machine for forming collapsible tubing from a preformed strip of metal having at least one edge bent to form a flange, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip imder the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, means to bend down said trailing flange to hold the edges of the flexible strip during formation of said second convolution, and means thereafter to firmly press down the flange and permanently secure the edges of the flexible strip, and means to adjust the bending means relatively to said pressing means.

18. In a machine for forming collapsible tubing from a preformed strip of metal having at least one edge bent to form a flange, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip under the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, means to bend down said trailing flange to hold the edges of the flexible strip during formation of said second convolution, and means to thereafter firmly press down the flange and permanently secure the edges of the flexible strip, and means to adjust the bending means relatively to said pressing means, said bending means being driven by said pressing means.

19. A machine as claimed in claim 18 having means to adjust the bending means relatively to said pressing means.

20. In a machine for forming collapsible tubing from a preformed strip of metal having opposite edges bent to form flanges, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip under the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, and means to press said trailing flange onto the inserted edges of flexible strip in said second convolution, and means to press down fully the forward flange of the metal strip during the formation of second convolution.

21. In a machine for forming collapsible tubing from a preformed strip of metal having opposite edges bent to form flanges, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible .strip under the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, and means to press said trailing flange onto the inserted edges of flexible strip in said second convolution, and means to press down said trailing flange to hold the inserted edges of the flexible strip during the formation of the second convolution and simultaneously to pinch down fully the forward flange of the metal strip.

22. In a machine for forming collapsible tubing from a preformed strip of metal having opposite edges bent to form flanges, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip under the trailing flange of the metal strip in one convolution, means to insert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, and means to press said trailing flange onto the inserted edges of flexible strip in said second convolution, and means to press down said trailing flange to hold the inserted edges of the flexible strip during the formation of the second convolution and simultaneously to pinch down fully the forward flange of the metal strip, and means to pinch down fullv said trailing flange during formation of a third convolution. I

23. A machine as claimed in claim,21 having means for forming a fold of excess material of said flexible strips outside the tubing, and means to pinch the fold.

24. A machine as claimed in claim 21 having means to form a fold of excess material of said flexible strip outside the, tubing, and means to pinch the fold while pinching down fully said trailing flange during formation of a third convolution.

25. In a machine as claimed in claim 11 having means to fold over outside the tubing excess material of the flexible strip between convolutions, and means to pinch the fold.

26. A machine as claimed in claim 25 wherein rotating roll means having different circumferential surfaces causes the bending of the flange and the pinching of thefolded material.

27. A machine as claimed in claim 11 wherein the means to insert the flexible strip comprises a flattened tubular member having converging toward its exit end, said exit end having its trailing and forward edges extending obliquely and reversely bent, respectively.

28. A machine as claimed in claim 27 wherein the tubular member has a spring finger near its exit end in extension fromthe bottom portion of said member, to guide the outflow of the flex ible strip therefrom.

29. A machine as claimed in claim 11 wherein the means to form the metal strip in the spiralled convolutions comprises a rotary mandrel, stationary means to guide-the metal strip on forming the first convolution, and a stationary member spiralled around the mandrel and tapering so as to guide the movement of one convolution toward another.

30. In a machine for forming collapsible tubing from a preformed strip of metal having at least one edge bent to form a flange, means to form said metal strip into successive spiralled convolutions, means to insert the trailing edge of a flexible strip under the training flange of the metal strip in one convolution, means toinsert the forward edge of the flexible strip under the trailing edge flange of the metal strip in a second convolution, and means to press said trailing flange onto the inserted edges of flexible strip in said second convolution, means to fold over outside the tubing excess material of the flexible strips between adjacent convolutions after said pressing, and means to pinch the fold, said means to form spiralled convolutions and said foldforming means comprising a rotary mandrel, stationary means to guide the metal strip on forming the first convolution and a stationary member spiralled around the mandrel and tapering so as to guide the movement 'of one convolution toward another.

WILLIAM E. REJESKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,580,760 Palmer Apr. 13, 1926 2,539,814 Chernack Jan. 30, 1951