US2092873A - Method and machine for corrugating tubes - Google Patents

Description

S-Sheets-Sheeti ma E INVE TO N y W? L. H. BRINKMAN METHOD AND MACHINE FOR CORRUGATING TUBES Filed Aug. 26, 1933 Sept. 14, 1937.

of mmoj mmy LmJ EH y 7/ x E E I 1 0.32 lill o l 09 mNZ J mm m pm mm 2.9 6W x 8 1: Q: @Q I m H Se t. .14, 1937. L. H. BRINKMAN A METHOD AND MACHINE FOR CORRUGATING TUBES 7 Filed Aug; 26, 1933 s Sheets-Sheet; 2 Y

. m2 wm Sept. 14, 1937 1.. BRINKMAN METHOD AND MACHINE FORCORRUGATING TUBES Filed Aug. 26, 1933 5 SHeets-Sheet 5 INVENTORr Patented Sept. 14, 1937 I METHOD AND MACHINE FOR. CORRUGAT- ING TUB Louis H. Brinkman, Glen Ridge, N. J.; Laura. Brinkman, administratrix of said Louis H. Brinkman, deceased, assignor of one-third to Laura. Brinkman and one-third to Blanche Moriarty, both of White Plains, N. Y., and one-third to Natalie B. Cocke, Birmingham,

Ala.

Application August 26, 1933, Serial No. 686,881

16 Claims.

This invention relates to metal working; especially to the working of the metal of tubes and pipes, that is, long cylindrical hollow bodies, and more especially to the corrugating of tubes or pipes.

A principal object of this invention is the production of a device by means of which the wall of a tube or pipe, especially one with a comparatively thin wall, may be formed into a series of parallel independent corrugations or folds as a continuous process applicable to tubes of any length.

Other objects and advantages will appear as the description of the particular physical embodiment selected to illustrate the invention progresses, and the novel features will be particularly pointed out in the appended claimsi In describing the invention in detail, and the particular physical embodiments selected to illustrate the invention reference will be had to the accompanying drawings and the several views therein, in which like characters of reference designate like parts throughout the several views, and in which:-- v

Figure 1 is partly aside elevation and partly a longitudinal sectional view of a tube corrugating machine embodying theinvention;

Figure 1a is a detail of the sleeve mounting;

Figure 2 is partly a top plan view and partly a by the line sectional viewon the plane indicated IIII of Fig. 1;

Figure 3 is a sectional view on the plane indicated by the line III-III of Fig. 1, with some parts broken away to more clearly show the construction; 1 i

Figure 4 is a'view along the line IV IV of Fig. 1, viewedin the direction .of the arrowsat the ends ofthe line IV-IVof Fig. 1, with some parts'broken away to more clearly show'the construction;

.- Figure 5, shows'theirelative arrangement'of the tOOlSOflFigS. '3 and14 during'one step'in" the manufacture; 1.. I a 1-. Y Figure 6 is anend view, and -Figure 7 'a longitudinal sectional-view; "on theplane-z.indicated iby line -.VI-I-VII of Fig..6,of another embodiment of the part'of the;apparatus shown at the right hand-.zside of Eig. 1; T; i 1

Figure 8 is a clamp or vice =for apreventing au-ndesired movement .of the-.pipe during one period Sin"the-manufacturer. a -'Figure 9-: illustratesfa sectiorr of. .tubing,i before, duringand after corrugating, and shows the tools ofj Figli5,contiguqusaherewithi. --=Reerrir g;,to Figs 1:,-&.;I::represents one o Main shaftliis also provided with, a ,se

supporting legs of the apparatus, 2 is a common bed rigidly fixed to base I by bolts 21). This immovable common bed 2 supports two sub-frames 3 and I03. Sub-frame 3 carries a main frame 4 for shaft 6 and for the apparatus associated therewith and, as shown in Fig. 3, the whole is slidably mounted, as a unit, upon suitable bearing surfaces 3a, upon the common bed 2.

Sub-frame I03 is fixed on common bed 2 by bolts I031). It is, however, adapted to be adjusted horizontally relative to sub-frame 3 by means of a threaded rod I037 operating in projections I038, Sub-frame 3 is likewise adjusted by rod'31' and projections 3s. The relative spacing of sub-' frame 3, in its idle position, and sub-frame I03 in its fixed position, and of the units associated therewith, is determined by the size and/or spacing of the corrugations to be-formed in the tubing or pipe. I The racked tracks 59t, like studs 3s and 13s, form no part of either sub-frame 3 or subframe I03, but are rigidly .fixed to and form a part of immovable common bed 2. 1 Frame 4 on sub-frame-3 is provided with a pair of vertically extending parallel supporting arms 4a. Driveshaft 5 isimountedin suitablebearings 5b on these arms 4a.: Shaft-,5 is adapted to receive power from a prime mover not shown) bymeans of a'pulleyaor wheel 5c: or by. other .suitable means.

The main shafts, designated G andv I06, respectively, are of hollow cylindrical construction. Shaft, 15. .(at the left handsidesof Fig. .1), is

,mounted-away fromlts ends inbearings 'Iid ion ,frame 4; it is in energy transfer-relation with drive shaft 5 tl'n oughigears 5g and 69. I p 00nd gear means 6h. Gear 6h meshes w'ith gear 55h oniidler shaft; 5,6, and is adapted torevolve shaft 58 h hin' rn e ves s a t 59% ed me fl ste m? e eb pa i are.- cipro'cating motiontheflentire assembly, moun j g a n-names. i .e., sane a length of pipe of the particular size to be processed, and is preferably provided with a curved recess 6b for guiding the pipe or tubing P into proper position. Additional support for pipe P is provided, intermediate its length, by device S or of any other suitable type.

Bushings (not shown) similar to 6a may be provided on the interior of shaft I06 for slidably supporting the pipe P after it has been corrugated.

A removable head 1 is mounted by threads 1a, on shaft 6. End plate 8 is fixed by screws 8a to head 1 and moves therewith. End plate 8 is adapted to cooperate with end plate I08 on the oppositely located head I01, in a manner to be described.

The main body of head 1 is rigidly fixed to shaft 6 and adapted to move therewith. Head 1 is provided with radial recesses in which are mounted, respectively, a number of inwardly extending radially arranged grooving tools or fingers 9 and I0. (See Figs. 3 and 5.) The inner fingers 9 are preferably set at an angle to the vertical axis of the outer fingers I0.

Inner fingers 9 serve to form an annular groove when pressed against the smooth surface of pipe P, and outer fingers I0 serve to shape this initial groove (the. pipe having been advanced) whenforcibly contracted thereon.

The contracting pressure necessary to operate fingers 9 is provided by angular flange II, which is slidably arranged on head 1, bearing directly against fingers 9.

Fingers I0 are set slightly ahead of fingers 9 and there is a slight time lag in their otherwise simultaneous contracting movement. This desired lag is simply attained by exerting pressure from angular flange II through a beveled ring IIa, against a curved surface I0a on the head of each finger I0.

Angular flange I I is removably threaded on sleeve I2 operating on main shaft 6 and is adapted to revolve therewith.

Sleeve I2 is slidably mounted by key l2k, operating in keyway 6k, on shaft 6 and is adapted to be moved horizontally forward by pressure of vertical arm 62 operating in groove I2a provided for the purpose in sleeve I 2. The necessary reversed horizontal movement of flange II .and sleeve I2 is provided by coiled spring I2s.

Fingers 9 and I0 are provided, respectively, with springs 9s and I0s,Ywhich serve to restore them to their inoperative position upon completion of their contracting inward movement. As will be described in connection with Fig. 8, a

- more positive movement than that exerted by springs 9s and Ms may be provided wherever necessary or desirable.

Head I01 is removably fastened to shaft I06 by threads l01a. Head I01, on rigid shaft I06 like head 1 on the revolving, reciprocating shaft 6 carries an end plate I08. corrugations made by tool 9 are separately compressed by reason of the reciprocating movement of head 1 and tools I0 toward tools I I0 in stationary head I01.

Head I01 is provided with a series of radial recesses adapted to accommodate the series of radially-arranged tools IIO. As shown in Fig. 9, these tools IIO serve to cooperate in the compressing operation and act to insure uniformity of contour in the corrugations while being compressed into final form; they also serve to grip, and thereby obviate rotation or other undesired movement of pipe P.

The contracting pressure necessary to operate tools IIO (to grasp pipe P) is provided through beveled ring IIIa by the sliding movement of angular flange III on head I08. Flange III is removably threaded on sleeve II2. Sleeve II2 is slidably keyed by key I I2k operating in groove I06k on fixed shaft I06 and is adapted to be moved horizontally forward by the pressure exerted thereagainst by ring II2a. Ring II2a receives its forward movement, on shaft operating on common shaft I60.

The reversed horizontal movement of angular flange III, sleeve H2 and ring II2a, necessary to relieve the tension on springs I-I0s to release tools H0, is provided by coiled spring II2s.

As set forth. in connection withFig. 1, main shaft 6 is driven by drive shaft 5 through gear 5g6g. Gear 6h, on main shaft 6 drives gear 56h on idle shaft 56, gear 56h in turn, meshes with gear 51h on shaft 51 see Fig. 2). This longitudinal shaft 51 is provided intermediate its length with worm gear 51g which is adapted to mesh with a corresponding gear adjacent one end of lateral shaft 58. As shown in both Figs. 1 and 2 shaft 58 carries two eccentric cams 58c and 6Ic. v

A second lateral shaft 59, is mounted in suitable housings on frame 4 and carries pinion 59a,

rocker arm 591, and lever bar 5912. Rocker arm 591' in following eccentric cam 580 is depressed, and, being keyed to shaft 59 will advance pinion 59a (and hence the entire units 4, 5, 6, etc.) on rigid track 59t. lever bar 59b, which is also keyed to lateral shaft 59 will rise, at its outer extremity, and increase the tension upon spring 59s. When the .downward pressure by eccentric I06, through rocker arm I6I and vertical arm I62 cam 580 on rocker arm 591' is removed, the tension exerted by spring 593 through lever bar 5917 will cause shaft 59, pinion 59a (and the entire assembly mounted thereabove) to move in the reverse direction on racked tracks 59t.

Rocker arm 6I moves on axle 60. Axle 60, like shafts 6515859, is mounted on main frame 4 and moves therewith. Rocker arm 6I follows eccentric cam 6 lo and, its outer end being raised, will cause shaft 60 to move in a direction opposite to that of cam 6Ic.

Axle 60 serves as a pivot for vertical arms 62. Arms 62 are provided with suitable rollers 62a operating in groove I2a of sleeve I2. previously described, sleeve I2 is slidably keyed on shaft 6, it carries angular flange II which serves to depress grooving tools 9 and I0 when sleeve.

I From the foregoing it will be apparent that the rotary motion of shaft 6 (provided by drive shaft 5 through gears 557-691) is in no wise interrupted by the reciprocating horizontal movement of sleeve I2, or by the radial movement of grooving tools 9 and I0.

In the preferred embodiment, Fig. 1, shaft I06 does not revolve nor is it or the sub-frame I03 subject to any reciprocating movement. The pressure necessary to contract the radially-arranged gripping tools H0 is provided, through keyed sleeve I2, by ring II2a. Ring II2a receives its forward movement on shaft I 06 through vertical arm I62 and rocker arm I6I mounted on common pivot shaft I60. Rocker arm |6I follows an eccentric cam I580. This cam I58c rotates with lateral shaft I58, which like the corresponding lateral shaft 58 on the opposite unit is driven by similar worm gears I5Ig on the sectional longitudinal shaft 5|I 51.

As shown in both Figs. 1 and 2 shaft sections 51 and I51 are flexibly joined by means of extensible and contractible coupling members 51a and I5'Iu.

The only functions of shaft I06 and the assembly mounted thereon are to (1) support pipe P, (2) to grip pipe P, (3) provide a face against which the corrugations may be separately compressed.

The apparatus shown in the embodiment of Figs. 6 and '7 fulfills all of these functions and,

in addition, provides a more direct movement for actuating and more positive movement for releasing the radially arranged gripping tools IIO, than that shown in Figs. 1, 3, and 4.

Like digits and characters represent similar or corresponding parts in all of the figures. Thus, referring to Figs. 6 and 7: 202 is the common bed; 203 the horizontally adjustable sub-frame; 2031' the threaded rod and 203s a threaded projection providing this horizontal adjustment for sub-frame 203; 204 represents the main frame or supporting arbor for the gripping tool assembly. The longitudinal drive shaft is 251, the

driven shaft is 258.

In the embodiment shown in Figs. 6 and 7, the

radially arranged gripping tools are designated 2); they are slidably supported on bearing surfaces in suitable recesses 2l0b in end member 201. Each gripping tool 2 I0, carries near its outer extremity, a finger or stud 2|0a. These studs 2|0a are adapted to slide in cam slots 2| Ib provided for the purpose in an annular or ring-like member 2| Ia. These cam slots reach the periph-r ery of 2|Ia, so that by disconnecting 26I from 2| Ia, then by rotating 2| la the studs 2I0a may be removed entirely from the slots, and tools 2l0 removed radially. Annulus 2| Ia carries a slotted stud 2| Is in which arm 26| operates. Arm 26I, near its lower extremity, is slotted to receive shaft 258 and carries a roller 2581 cooperating with cam 2580. Cam 2580 is mounted on shaft 258 and is driven by shaft 251 through gears 251a and 2589, thus oscillating 2| Ia and tools 2l0.

In the embodiment, Figs. 6 and '7, above described, it is apparent that the upward or releasing movement of gripping tools 2l0 is no less positive than the inward or gripping movement and for this reason may be preferred to the spring actuated gripping tool assembly of Fig. 1.

Although the machine is entirely automatic in operation when all of the several grooving and gripping tools are functioning, it is nevertheless necessary to use a clamping device S (which may be of any suitable or convenient type) for preventing undesired rotary or other movement of pipe P during the formation of the first few grooves, and to allow subsequent advance of the P l Pipe P is inserted through clamping and supporting device S, shaft 6, bushing 6a to a point past the first grooving tools or fingers 9 and preferably between the two sets of fingers.

The jaws of clamping device S are clamped and the power turned on. Power developed by the prime mover (not shown) will be transmitted through pulley 50 to drive shaft 5 and thence which operate at an angle, begin to close.

to main shaft 6 through gears 59-69. As head 1 bearing the radially arranged grooving tools 9 and I is fixed to shaft 6 at Ia; an as sleeve I2 carrying actuating flange II and ring ||a is slidably keyed to. shaft 6 by key I210, the entire assembly, i. e., shaft 6, head I, end plate 8, tools 9 and I0, flange II, and sleeve I2, will rotate about pipe P.

As shaft 6 revolves, it drives longitudinal drive shaft 51 (by means of gears Sn and 56h, Fig. 2). Shaft 51 operating through worm gear 51h, shaft 58, rocker arm BI and vertical arm 62 advances sleeve I2 on main shaft 6 and forces flange I and ring I la against tools 9 and I0. Tools 9 and I0 are thereby pressed against pipe P and form a pair of parallel grooves therein. The pipe is then released from clamping device S, and head 1 in moving forward, (tools 9 and I0 being still in position), the outer groove will be squeezed against the gripping tools 0. The first corrugation or bellows fold having been formed, the

pipe is further advanced (manually) at which time tools 0 operate to firmly grasp the corrugation already formed.

As previously set forth, gripping tools I I0 may be actuated in a manner similar to that provided for the operation of grooving tools 9 and I0, or in the manner described in connection with the embodiment shown in Figs. 6 and 7. In any event, the operation of all of the tools 9I0 and H0 is in a predetermined order. The sequence of operation is preferably as follows:

The radially arranged set of grooving tools or fingers I0 are set slightly ahead of fingers 9 in order to allow them to obtain a grip on'the tubing and prevent it from slipping when fingers 9 When these two sets of fingers 9 and I0 have obtained a grip on the tubing, gripping tools 0 in right hand head |0'| open and release the tube. Left hand head 1' Jumps forward suddenly and advances the tubing the distance of one corrugation. Tools 0 close again and grip this new corrugation while head I continues moving forward and compresses the bridge formed between the two grooves made by fingers 9 and I0, causing it to swell out into the form of a corrugation. As

shown in Fig. 9, during this latter operation,

grooving tools 9 and I0 and gripping tools I I0 are still within the grooves and serve to ensure uniformity of contour during the compressing operation. As shown by both Figures and 9 at the point of furthest outward movement, tools I0 are adjacent or contiguous to gripping tools 0.

After the corrugation or bellows fold has been formed by the motion forward of head I against stationary head |0'|, the gripping tools 0 remain closed while grooving tools 9 and I0 open and are released from pipe P while head I moves quickly back. Tool I0 is now contiguous the shallow groove formed during the first cycle by tool 9, and tool 9 is in position to initiate a new groove. When these two sets of fingers 9|0 have obtained a grip on the tubing, tools I I0 open and release the tube and the entire cycle is repeated.

It is essential that tool I0 does not actually contact with the bottom of the groove formed by tool 9, that is, tool 9 in forming a groove somewhat thins the metal at the bottom of the groove, so that if tool I0 further acted to depress the bottom of the groove the metal would be thinned still more. Applicant prevents this undesired result by so timing the operations that tool I0 has not quite reached the bottom of the initiated groove when head I moves forward. As head 1 moves forward, pressure by tool H0 is exerted on the end wall W, i. e., the forward side of the bridge between grooves, so that the outer periphery of the bridge moves outwardly and the bottom of the next to the last groove formed moves inwardly, followed closely by tool I0, so close as not to actually spin the metal of the bottom of the groove but closely enough to produce the proper shape. Concurrently, pressure is exerted by tool l0 a ainst the end wall W" of the bridge.

As the top of the bridge moves outwardly, the metal of the bridge decreases in thickness,so that the final result is a tube in which the metal is of substantially the same thickness throughout.

If the bridge between grooves is not slightly convex outwardly, there is danger that the bridge will cave inwardly instead of bulging outwardly when squeezed between tools l0 and H0. Because of this applicant forms the ends of tools It and H0 so that the proper form is assured. Tool 9 is formed with the curved portions 90 and 9d. These portions ensure a properly rounded form for the bridge between grooves before it is compressed. Further, the edge 9c of the tool 9 in its final inner position is as close as it can conveniently be brought to edge We of tool l0, so as to cover substantially all of the bridge by the'forming tools.

The tools 9, l0, and H0 are placed, as shown in Figs. 3 and 4, so that when they are pushed inwardly to their greatest extent their ends form practically a circle with a space between tools of about the thickness of the stock being worked. The radius of the arc of the face or working end of tool 9 is about 0.01 of an inch greater than one-half the outside diameter of the tube being worked. This prevents any catching of the corners of the tool in the material.

The are of tool I0 is that of a circle whose radius is one-half the diameter at the initiated groove when completely formed, plus about 0.005 of an inch.

The are of tool H0 is that of a circle whose radius is one-half of the diameter at the groove when completely formed plus about 0.002 of an inch.

Although I have illustrated and described one particular physical embodiment of my invention and explained the principle, construction, and mode of operation thereof, nevertheless, I desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A machine for forming parallel corrugations in a tube of indeterminate length comprising a plurality,ofspaced axially aligned supporting members through which said tube is adapted topass, a plurality of series of grooving tools arranged about said tube near an end of one of said supporting members, means to cause relative rotation between said tools and said tube, gripping tools adjacent-the adjacent opposed end of another of said members, means for pressing all of said series of grooving tools against the outer surface of said tube to form a plurality of parallel grooves therein, means for actuating said gripping tools to prevent undesired movement of said tube while-said grooving tools are operating and means to cause certain of said tools to approach each other for successively squeezing each of said parallel grooves during said simultaneous grooving and gripping operations.

2. A machine for forming parallel corrugations in a tube of indeterminate length comprising a plurality of spaced axially aligned supporting members through which said tube is adapted to pass, a plurality of series of grooving tools arranged about said tube near an end of one of said supporting members, means for rotating said last-mentioned supporting member, with said grooving tools, relatively to said tube, gripping tools adjacent the opposed end of another of said members, means for pressing all of said series of grooving tools against the outer surface of said tube to form a plurality of parallel grooves therein, means for actuating said gripping tools to prevent undesired movement of said tube while said grooving tools are operating and means to cause relative movement between said first mentioned and said second mentioned supporting members for advancing said grooves relative to said gripping tools.

3. A machine for forming parallel corrugations in a tube of indeterminate length, comprising a plurality of spaced axially aligned supporting members through which said tube-is adapted to pass, a plurality of series of grooving tools arranged about said tube near an end of one of said supporting members, means to cause relative rotation between said tools and said tube, gripping tools adjacent the opposed end of another of said members, means for pressing all of said series of grooving tools against the outer surface of said tube to form a plurality of parallel grooves therein, means for actuating said gripping tools to prevent undesired movement of said tube while said grooving tools are operating,

means for causing intermittent relative appoaching movements of said grooving tools and gripping tools, for successively squeezing each of said parallel grooves and means for releasing said gripping tools to permit advancing said tube bodily relative to said gripping tools during periods intermediate said successive squeezing operations, and by virtue of certain of said approaching movements.

4. A machine for forming parallel corrugations in a tube of indeterminate length, comprising a plurality of spaced axially aligned supporting members through which said tube is adapted to pass, a plurality of series of grooving tools arranged about said tube near an end of one of said supporting members, means for rotating said last mentioned supporting member with said grooving'tools, relatively to said tube, gripping tools adjacent the opposed end of another of said members, means for pressing all of said series of grooving tools against the outer surface of said tube to form a plurality of parallel grooves therein, means for actuating said gripping tools to prevent undesired movement of said tube while said grooving tools are operating, means for causing intermittent relative approaching movements of said grooving tools and gripping tools, for successively squeezing each of said parallel grooves during said simultaneous pressing and gripping operations, and means for advancing said tube bodily relatively to the initial position of said grooving tools after completion of the squeezing operation upon each preceding corrugation.

5. A machine for forming parallel corrugations in a tube of indeterminate length comprising a plurality of spaced axially aligned supporting members through which said tube is adapted to pass, a plurality of series of grooving tools arranged about said tube near an end of one of said supporting members, means for rotating said last mentioned supporting member with said grooving tools, relatively to' said tube, gripping tools -adjacent the opposed end of another of said members, means for pressing all of said series of grooving tools at predetermined intervals against the outer surface of said tube to form a plurality of parallel grooves therein, means for actuating said gripping tools to prevent undesired movement of said tube while said grooving tools are operating, means for causing intermittent relative approaching movements of said grooving tools and gripping tools for successively squeezing each of said parallel grooves during said grooving and gripping operation and means for moving said tube bodily to an advanced position relatively to the initial position of all of the tools during periods intermediate said repeated simultaneous grooving, gripping and squeezing operations.

6. The method of corrugating a tube which consists in forming an annular groove in said tube, initiating a second groove, and initiating a third groove, and concurrently deepening said second groove by applying force laterally to the posterior wall of said groove to cause the leading wall of said second groove to approach the adjacent end wall of said first mentioned groove.

7. The method of deforming tubular metal stock of indeterminate length and approximately uniform original diameter, to form the walls thereof into corrugations embodying concave portions of less diameter than the original, and convex portions of greater diameters than the original, with walls of diminished, substantially uniform thickness, said method comprising the steps of advancing said stock intermittently and applying a multiplicity of compressive forces acting exclusively upon and uniformly against the exterior superficies of said stock tube to form in its walls a series of longitudinally spaced constrictions or concave portions of diminished wall thickness and lesser diameter than the original, and connected by convex portions, and to compress said convex portions one by one to cause protrusion thereof beyond the original tube diameter and simultaneously to reduce the wall thickness of said convex portions, each corrugation in its final form being completed by two constrictive steps and a consecutive compressing step.

8. The method of deforming tubular metal stock of indeterminate length and approximately uniform original diameter, to form the walls thereof into corrugations embodying concave portions of less diameter than the original, and con-' vex portions of greater diameter than the original, with walls of diminished, substantially uniform thickness, said method comprising the steps of advancing said stock intermittently and applying forces acting upon the exterior superficies of said stock tube to form in its walls a series of longitudinally spaced constrictions or concave portions of diminished wall thickness and lesser diameter than the original, and connected by convex portions, and a force acting concurrently to compress said convex portions one by one to cause protrusion thereof beyond the original tube diameter and simultaneously to reduce the wall thickness of said convex portions, each corrugation in its final form being completed by two constrictive steps and a consecutive compressing step, the constrictive steps including an initiatory constriction performed by a force applied rotatively and laterally as to advance the portion of stock under treatment,-and a perfecting constric tion also performed during said advance, while the leading portion of stock is held against rotation and against advancement, and each com-1 pressing step being performed by a force applied during said advance and contributing thereto while the leading portion dwells, and said tube, including both the perfected portion, a partially treated portion and the untreated portion, being fed bodily during a dwell in the operation of the constrictive and compressing forces.

9. The method .of forming parallel corrugations in a longitudinally movable, non-rotating tube of indeterminate length which-consists in producing a groove in said tube adjacent the section to be corrugated, inserting separable dies within said groove, producing another parallel annular groove by lateral pressure while restraining said tube from longitudinal movement, advancing said group of later grooves towards said first mentioned'groove while maintaining said first mentioned groove from longitudinal movement whereby the surface connecting said first mentioned groove and the first groove of said later formed group is expanded outwardly'to form an annular ridge in said tube, advancing said tube, inserting said separable dies in the first and second grooves of said group, forming other parallel annular grooves, in succession, advancing each such preceding group while maintaining said grooves of each such preceding group from longitudinal movement whereby said first mentioned groove, said annular ridge and said first groove of said preceding group form a single complete corrugation in said tube, and so continuing until the desired portion of said tube is corrugated.

10. A continuous method of parallelly corrugating a tube of substantially uniform diameter and indeterminate length, which comprises forming successively by progressively applied increments of rotary, exclusively exterior lateral pressure, a series of grooves in said tube and, concurrently with the formation of said series, subjecting the surface forming an end wall of each already formed groove of said series and the surface constituting the partly formed adjacent wall of another of said grooves to longitudinal pressure and advancing the tube bodily from time to time, -said operations being performed upon the walls of all of the grooves seriatim.

11. A method of parallelly corrugating a tube which comprises forming by rotary, exclusively exterior, lateral pressure a plurality of grooves in said tube and then, consecutively with said grooving operation, subjecting the surface forming an end wall of each of said grooves successively to longitudinal pressure while limiting the radially outward movement of the surface connecting said wall and the wall of the next preceding groove.

12. A continuous method of parallelly corrugating a tube which comprises forming by lateral pressure a plurality of grooves in said tube and then, simultaneously with a continuance of said grooving operation, subjecting the surface forming an end wall of each of said grooves and the surface forming the adjacent end wall of another of said grooves to longitudinal pressure, applied intermittently to each such successive pair of end walls, while limiting the radially outward movement of the surface connecting said end walls.

13. The method of forming corrugations in a tube which comprises initiating grooves by rotating compressive forces simultaneously around the entire periphery of the tube while thinning the metal at the bottom of the grooves, then squeezing a bridge thus formed, between two tools .so that the bridge becomes a corrugation having a greater diameter than the original tube and the initiated groove is depressed so that the metal of the corrugation becomes thinner than the original tube wall to correspond to the thickness at the bottom of the groove.

14. The method of forming corrugations in a tube which comprises forming two separated grooves therein by applying compressive forces simultaneously around the entire periphery of the tube, revolving said forces circumferentially against the periphery of the tube while applying compression thereto, and then squeezing the bridge between certain of said forces and complemental peripherally applied non-revoluble forces, while allowing the outer periphery of the bridge to expand outwardly and the bottom of the grooves to go inwardly while forming the side thereof.

15. The method of corrugating a tube which comprises initiating separated grooves therein by rotating compressive forces simultaneously the bridge and keeping the bottom of the grooves free from thinning action.

16. The method of deforming tubular metal stock of indeterminate length and approximately uniform original diameter, to form the walls thereof into corrugations embodying concave portions of less diameter than the original, with walls of diminished, substantially uniform thickness, said method comprising the steps of advancing said stock intermittently and applying rotatively a multiplicity of compressive forces acting simultaneously and uniformly upon the exterior superficies of said stock tube in a direction normal to said periphery at each such region of compression to form in its wall a series of longitudinally spaced constrictions or concave portions of diminished wall thickness and lesser diameter than the original, and connected by convex portions, and of compressing said convex portions one by one to cause'protrusion there'- of beyond the original tube diameter and simultaneously to reduce the wall thickness of said convex portions.

LOUIS H. BRINKMAN.

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