US3606783A

US3606783A - Segmented roll for forming helically corrugated pipe

Info

Publication number: US3606783A
Application number: US811972A
Authority: US
Inventors: Clarence P Lewis
Original assignee: Armco Inc
Current assignee: Contech Engineered Solutions LLC
Priority date: 1969-04-01
Filing date: 1969-04-01
Publication date: 1971-09-21
Anticipated expiration: 1988-09-21

Abstract

AN IMPROVED SEGMENTED ROLL FOR FORMING HELICALLY CORRUGATED PIPE BY CURLING AN ELONGATED STRIP OF SHEET METAL HAVING LONGITUDINALLY EXTENDING, ALTERNATING RIDGES AND VALLEYS THEREIN, INTO A HELICAL CONVOLUTION.

Description

Sept. 21, 1971 c. P. LEWIS 3,505,783

f SEGMENTED ROLL FOR FORMING HELICALLY CORRUGATED PIPE Filed April 1, 1969 4 Sheets-Sheet 1 INVENTOR/S CLARENCE I? LEWIS ATTOR NEYS Sept. 21, 1971 c. P.-| Ew|s 3,505,733

SEGMENTED ROLL FOR FORMING HELICALLY CORRUGATED PIPE Filed April 1, 1969 4 Sheets-Sheet 2 FiaJA F16 4 I Q.YIINVENTOR/S CLARENCE P L EWIS c. P. LEWIS 3,606,783

SEGMENTED ROLL FOR FORMING HELICALLY CORRUGATED PIPE Sept. 21, 1971 4. Sheets-Sheet 3 Filed April 1, 1969 INVENTOR/S (LAKE/W5 LEW/S BY k%adaa, ana

ATTORNEYS Sept. 21, 1971 c. P. LEWIS 3,606,783

'SEGMENTED ROLL FOR FORMING HELICALLY CORRUGATED PIPE Filed April 1. 1969 4 Sheets-Sheet 4- \a. J J J l/ H Mb I CG/Zm Q 4-\ INVENTOR/S ATTORNEYS United States Patent Olfice 3,606,783 Patented Sept. 21, 1971 3,606,783 SEGMENTED ROLL FOR FORlVHNG HELICALLY CORRUGATED PIPE Clarence P. Lewis, Carlisle, Ohio, assignor to Armco Steel Corporation, Middletown, Ohio Filed Apr. 1, 1969, Ser. No. 811,972 Int. Cl. B21c 37/12; B21f 3/02; B23k 31/00 US. Cl. 72-135 11 Claims ABSTRACT OF THE DISCLOSURE An improved segmented roll for forming helically corrugated pipe by curling an elongated strip of sheet metal having longitudinally extending, alternating ridges and valleys therein, into a helical convolution.

BACKGROUND OF THE INVENTION (1) Field of the Invention This invention relates to an improved apparatus for making pipe and more particularly to helically forming pipe from an elongated strip of fiat sheet metal.

(2) Description of the prior art A number of machines have heretofore been utilized in forming helically corrugated spiral pipe by bending an elongated strip of sheet metal or the like into helical convolutions and joining or connecting the adjacent edges of the convolutions by welding, forming a lock seam, or the like. However, such machines have generally been restricted to the formation of a single size of pipe for each size of forming shoe employed therewith. The time required to change such a machine from producing one size of pipe to another has therefore been extensive, resulting in increased labor costs and extended periods when the machine was unproductive.

United States Letters Patent No. 3,247,692, in the name of Paul K. Davis, attempted to alleviate the aforementioned problems by providing an improved mounting means and shifting means for a segmented roll for forming helically corrugated pipe. Briefly, the mounting means comprises a plurality of independent mounting plates which are slidably mounted within and rotatable with respect to the segmented roll. Each mounting plate is provided with a slot therein for receipt of the circular portion of one of the rollers such that the periphery of the roller projects therefrom. Each mounting plate is also provided with opposed parallel side edges which are generally contiguous with adjacent mounting plates, thereby maintaining the planes of the peripheries of the rollers parallel and spaced apart. Accordingly, excessive dirt particles are prevented from accumulating therebetween so that the easy glide of adjacent mounting plates is maintained.

The shifting means of the present invention for shifting the mounting plates together along the axis and for changing the angle of the planes of the peripheries of the rollers with respect to the longitudinal axis of the elongated supporting member of the segmented roll which houses the mounting plates, may comprise an adjustable means at the end of the elongated supporting member and a tapered spacer block. A portion of the adjustable means is generally contiguous with a side edge of one of the end mounting plates and may be adjusted so that the spacer block may be inserted within the elongated supporting member so that the tapered face thereof is generally contiguous with a side edge of the other end mounting plate. Accordingly, the rollers of the segmented roll may be set and the angle of the plane of the peripheries of the rollers with respect to the longitudinal axis of the elongated supporting member may be changed as the angle of the alternating ridges and valleys or corrugations tioned difficulties by providing a forming device compris- 4o ing a plurality of forming rolls containing connected mounting means or plates carrying yokes supporting rollers. However, the C-section connectors joining the mounting means or plates have led to binding problems as dirt accumulates therein and prevents the easy glide of adjacent mounting means or plates.

The machine of Davis is not restricted to the formation of a single size of helically corrugated pipe because Davis provides shifting means for the connected mounting means or plates. One form of shifting means for the connected mounting means or plates comprises the use of an arm to adjust the rollers of the forming rolls of the forming device as the angle between the forming device and the carriage is changed to produce pipe of varying diameter. Such an adjustment aligns the end roller with the crimping wheel used for lock seam pipe or with the weld roller used for welded seam pipe. However, this shifting means has proven unsatisfactory because binding occurs due to the accumulation of dirt in the C-section connectors, thus preventing the easy glide of adjacent mounting means or plates. Additionally, the alignment was found to be unsatisfactory.

Davis also proposes an alternative method of shifting means. Here the angle of the rollers of the forming rolls SUMMARY OF THE INVENTION The present invention has eliminated the aforemenof the metal strip relative to the axis of the pipe being formed changes.

It will be obvious that a dilferently angled spacer block is needed for each diameter of pipe being made. The advantage, however, is that jig bore accuracy is obtained in an adjustable apparatus.

In a further embodiment of the present invention the shifting means comprises a spacer block slidably received within each end of the elongated supporting means and adjustable means to position them therein with respect to the mounting plates. Each of the spacer blocks is proyided with a substantially identical tapered face which is generally contiguous with a side edge of one of the end mounting plates.

In still a further embodiment of the present invention the shifting means comprises at least one templet bar slidably mounted adjacent to and parallel with the segmented roller. Means are provided for pivotally joining each of the mounting plates with the templet bar, and means actuate the templet bar so that the mounting plates may be rotated together to set the rollers and to change the angle of the plane of the peripheries of the rollers with respect to the longitudinal axis of the elongated supporting member as desired.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a top plan view of an apparatus for making helically corrugated pipe which utilizes the improvement of the present invention.

FIG. 2 is an enlarged front elevation of the forming device utilizing the present invention.

FIG. 3A is an enlarged cross sectional view taken on the line 3A3A of FIG. 4.

FIG. 3B is an enlarged cross sectional view similar to FIG. 3A but showing a modification of the invention.

FIG. 4 is an enlarged end elevation of a portion of the forming device utilizing the present invention.

FIG. is a cross sectional view through a spacer block of the present invention taken on the line 55 of FIG. 2.

FIG. 6 is an enlarged view showing the geometric relationship between the forming angle and the angle that the tapered face of the spacer block makes with the longer edge thereof.

FIG. 7 is a perspective view showing a further embodiment of the shifting means according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 discloses a top plan view of an apparatus for forming helically corrugated spiral pipe 1 from an elongated strip of sheet metal 3. In general, the apparatus comprises a corrugating station 5 and a forming station 7. At the corrugating station, a carriage, generally designated 9, receives the strip of sheet metal 3, forms longitudinal ridges and valleys therein and advances it through the forming device, generally designated 11, at the forming station where the strip of sheet metal 3 is continuously formed into the pipe 1. The pipe then proceeds to a discharge station for further processing.

The carriage 9 does not form a part of the present invention and will only be described in sufiicient detail as to explain the development of the present invention. It will suflice to say that the carriage 9 carries on its upper side a plurality of corrugating rolls 12. The rolls 12 have one or more wheels 13 and are arranged in a plurality of stands or matched pairs so that the strip of metal 3 will pass between the upper and lower rolls of each stand and be deformed into corrugations as the strip passes from the input end 15 toward the output end 17 of the carriage 9. The corrugations formed in the strip of metal 3 by the wheels 13 on the rolls 12 are of a common form comprising alternating ridges and valleys connected by integral oppositely inclined portions. If desired, lock seam elements (not shown) may be formed centrally of oppositely inclined portions at the edges of the strip. However, this will, of course, depend on how the adjacent edges of the helical convolutions are to be joined, such as by welding, forming a lock seam, or the like.

As the strip of metal 3 leaves the output end 17 of the carriage 9 it is fed through the forming device 11. The forming device, as best seen in FIGS. 2, 3 and 4, comprises a frame 19 supporting a forming roll mechanism. The forming roll mechanism is located in a position intercepting the feed path of a strip of metal 3 from the carriage 9 and includes supporting segmented heel, arbor and buttress

rolls

21, 22 and 23 and first and second matched pairs of

seam rollers

25a, 25b and 27a, 27b respectively. The arbor roll 22 acts as the pressure roll and curls the strip of metal 3 into an are using the buttress 23 as the strip of metal 3 is moved therethrough by the driving means on the carriage 9.

The heel, arbor and buttress

rolls

21, 22 and 23, as will be more fully explained hereinafter, are made up of a plurality of individual rollers 33 and have an axis of rotation parallel to a pipe axis 1a about which the strip of metal 3 is curled. In the formation of smooth walled pipe, unitary rolls may be substituted for the segmented rolls 21, 22 and 23. The unitary rolls will comprise elongated, substantially cylindrical rolls supported for rotation about parallel axes intercepting the feed path of a flat strip at an oblique angle and will similarly function to curl the strip about the pipe axis 1a.

The subject segmented heel, arbor and buttress

rolls

21, 22 and 23, with their axes at an oblique angle to the feed path of the strip of metal 3, cause the strip to be curled by the individual rollers thereon into helical convolutions, the pitch angle of which is the same as the oblique angle. It should be noted that the carriage 9 is supported for swinging relative to the frame 19 of the forming device 11. Accordingly, the oblique angle between the feed path of the carriage 9 and the segmented heel, arbor and buttress

rolls

21, 22 and 23 may be adjusted in relation to the width of the strip of metal 3 at the output end of the carriage 9 and the diameter of the pipe being formed so that the trailing edge 29 of a preceding portion of the strip of metal 3, when curled through a convolution of 360, is adjacent the leading edge 31 of a following portion of the strip. In this manner, the strip of metal 3 is curled into closed helical convolutions so that When the adjacent edges are joined a continuous helically corrugated spiral pipe is completed and discharged from the forming device 11 along the pipe axis 1a.

The segmented heel, arbor and buttress

rolls

21, 22 and 23 preferably comprise a plurality of individually mounted rollers 33. Each roller 33 has a periphery generally conforming to a corrugation which has been previously formed in the strip of metal 3 by the wheels 13 at the corrugating station 5. Each of the rollers 33 is rotatably mounted within an independent mounting plate 35 a portion of which is slidably mounted within and rotatable with respect to the segmented roll. Each of the mounting plates 35 has a slot 35a therein into which the circular portion 33a of the roller 33 fits. As can be seen, the periphery of each roller 33 projects from the end of its mounting plate 35. Each mounting plate 35 has opposed parallel side edges 35b which are generally contiguous with adjacent mounting plates, thereby main taining the planes of the peripheries of the rollers 33 parallel and spaced apart. It should be noted that the shortest distance between the planes of the rollers 33 is equal to the distance between the adjacent ridges or valleys of the corrugations of the strip of metal 3.

The independent plates 35 carrying the rollers 33 of the segmented heel, arbor and buttress

rolls

21, 22 and 23 are mounted in the elongated members or

ways

37, 38 and 39, respectively, such as within the T-shaped slots 40, for sliding therewith and rotation with respect thereto. The

ways

37, 38 and 39 are secured to the frame 19 of the forming device 11. It should be emphasized that the mounting plates 35 carrying the rollers 33 are not connected together when they are slidably mounted within the elongated members or

way

37, 38 and 39. This factor is important, because binding problems have been eliminated as excessive dirt particles may not accumulate between the mounting plates 35 so as to prevent the easy glide of adjacent mounting plates.

It is, of course, critical that the rollers 33 conform to the alternating ridges and valleys of the corrugations of the strip of metal 3 as the helical convolution is being formed. However, the angle of the plane of the periphcries of the rollers 33 with respect to the longitudinal axis of the elongated supporting members or

ways

37, 38 and 39 must be changed as the angle of the alternating ridges and valleys of the corrugations of the strip of metal 3 relative to the pipe axis 1a changes by movement of the carriage 9. This, of course, is necessary as the diameter of the pipe being formed is changed. According to the present invention the rollers 33 may be kept in proper alignment by shifting means which comprise either two spacer blocks 41 and the adjusting means 43, as shown in the heel roll 21 in FIGS. 2 and 3A, or a spacer block 41 and the adjusting means 43, as shown in the heel roll 21 in FIG. 3B. Each spacer block 41 is provided with a tapered face 41a. The spacer blocks 41 may be mounted within the elongated supporting members or

ways

37, 38 and 39, as best seen in FIG. 5, by means of a spring plunger 45.

If the shifting means comprises two spacer blocks 41, a spacer block 41 is slidably received within each end of the elongated supporting members or ways 37, 38', and

39 such that the substantially identical tapered edges 41a thereof will be generally contiguous with the outside edges 35b of the end mounting plates 35 when the adjacent mounting plates 35 are substantially contiguous with each other. In practice, the adjusting pin 43 is loosened sufficiently to allow the spacer blocks 41 to be properly positioned, and then it is tightened so that the planes of the peripheries of the rollers 33 is set. However, if the shifting means comprises a spacer block 41 and the adjusting means 43, which is preferably an adjusting pin 43 having at one end and a pivotally mounted shoe portion 44, as best seen in FIG. 3B, the adjusting pin 43 is loosened sufliciently so that the desired spacer block 41 may be inserted in the elongated supporting members or

ways

37, 38 and 39 with the tapered face 41a thereof facing toward a side edge 35!; of one of the end mounting plates 35. The adjusting pin 43 is then tightened until the pivotal Shoe portion 44 thereof is generally contiguous with a side edge 35b of the other end mounting plate 35 and the parallel side edges 35b of the mounting plates 35 are substantially contiguous with each other and the side edge 35b of the endmost mounting plate 35 rests against the tapered face 41a of the spacer block 41. The plane of the peripheries of the rollers 33 is then set. It should also be noted that the edges 41a of the spacer blocks 41 may either bear against the portion of the end mounting plates 41, exterior of the supporting members of

ways

37, 38 and 39, as shown in the arbor roll 22 in FIG. 2, or against the portion within the supporting members or

ways

37, 38 and 39, such as that portion within the T-shaped slots 40, as shown in the heel roll 21 in FIG. 2. The former position is preferred due to the larger bearing surface area available.

It will be obvious that the angle of the plane of the peripheries of the rollers 33 with respect to the longitudinal axis of the elongated supporting members or

ways

37, 38 and 39 may be adjusted with extreme accuracy by varying the tapered face of the spacer block as the angle of the alternating ridges and valleys relative to the axis of the pipe being formed changes. The basic advantage is that a jig bore accuracy is obtaining in an adjustable apparatus.

In operation, a plurality of spacer blocks 41, which differ from each other both in the length of the longer edge 41b and in the angle I that the tapered face 41a makes therewith, are required in order to manufacture helically corrugated spiral pipe of varying diameters.

Turning to FIG. 6, it will be seen that due to the geometric configuration the forming angle 1', which is the acute angle of the alternating ridge and valleys of the corrugations of the strip of metal 3 relative to the pipe axis 1a, is equal to the angle I which the tapered side 41a of the spacer block 4 1 makes with the longer edge 41b thereof. In practice, where 1 equals the forming angle, K equals the lead, H equals the mean circumference of the pipe being formed, and W equals the Width of the strip of metal 3, the forming angle J, and thus the angle I, may be calculated from the following formula:

1r(mean diameter) W 1r(inside diameter+depth of corrugations) Cosine J=g For example, to make pipe of 18-inch inside diameter from a strip of metal having a width of 24 inches and having /2 inch deep corrugations,

Cos J: :4128969 pipe of varying inside diameters to be made from 24inch wide strip having /2 inch deep corrugations.

Forming angle I Mean circum- Plpe size (inside and thus ference H 1r angle .T Lead K (I.D.+%) Cos J" The length of the longer edge 41b of the spacer blocks 41 cannot be predicted accurately by geometric relationship due to the tolerance in the thickness and differences in springback characteristics of various metal strips 3. In practice, an approximate length of the longer edge 41b is calculated from the geometric relationship and a reasonable increment is subtracted so that all final corrections can be madewith the positive addition of shims. Accordingly, the spacer block 41 maybe adapted to any particular set of operating conditions. This approximate length calculation is, of course, based on the smallest diameter helically corrugated spiral pipe that Will be made in the forming operation, as the large diameter pipe will require a longer edge 41b on the spacer blocks 41. Accordingly, the feature of positive shimming will be preserved. It should be noted that the spacer block length calculation for the heel and buttress

rolls

21 and 23 will include a compensation for the fact that these rolls are displaced from the pipe axis 1a as opposed to the spacer block 41 for the arbor roll 22 which lies directly below the pipe axis 1a.

The rollers 33 may also be kept in proper alignment by means of the embodiment of the shifting means disclosed in FIG. 7. There are at least one templet bar 45 is slidably mounted adjacent to and parallel with each of the elongated members or

ways

37, 38 and 39. A pin 47 is fixed to each end of the mounting plates 35 and pivotally joins each plate with the templet bar 45, as at 49. Any conventional means 52 may be provided to actuate the templet bar 45, whereby the mounting plates 35 may be rotated together to set the rollers 33 with respect to the longitudinal axis of the elongated members or

ways

37, 38 and 39 with extreme accuracy as the angle of the alternating ridges and valleys relative to the axis of the pipe 1a being formed changes. In practice, it has been found that two templet bars 45 are preferred and that the conventional actuating means 52 should include gear means joining the bars 45 such that they may be actuated together in opposite directions.

The means 52 to actuate the templet bars 45 may include any conventional dial which is calibrated such that the longitudinal movement of the bars 45 will correspond to the angle of the planes of the peripheries of the rollers with respect to the longitudinal axis of the

ways

37, 38 and 39 which is desired.

What I claim is:

1. In a segmented roll for forming helically corrugated pipe by curling an elongated strip of sheet metal having longitudinally extending, alternating ridges and valleys therein, into a helical convolution, of the type having:

(a) a plurality of rollers having peripheries generally conforming to the shape of said ridges and valleys;

(b) mounting means for said rollers, said mounting means mounting each roller for rotation With its periphery in a plane;

(c) elongated supporting means supporting said mounting means with the peripheries of said rollers projecting therefrom, for engaging said ridges and valleys, said supporting means supporting said mounting means for movement along and with corresponding points on said rollers aligned parallel to the longitudinal axis of said supporting means, and for movement changing the angle of the planes of the peripheries of said rollers with respect to said longitudinal axis of said supporting means; and (d) means for shifting said mounting means parallel to said axis and for changing the angle of the planes of the peripheries of said rollers with respect to said longitudinal axis of said supporting means; the improvement wherein said mounting means comprises a plurality of independent mounting plates a portion of which are slidably mounted within and independently swingable with respect to said elongated supporting means, each said mounting plate having a slot therein for receipt of the circular portion of one of said rollers such that the periphery of said roller projects therefrom, and opposed parallel side edges which are generally contiguous with adjacent mounting plates, thereby maintaining the planes of the peripheries of said rollers parallel and spaced apart, whereby excessive dirt particles are prevented from accumulating in said elongated supporting means and so that the easy glide of adjacent mounting plates is maintained, and wherein said shifting means comprises an adjustable pin at one end of said elongated supporting means, said adjustable pin having a pivotally mounted shoe portion at one end thereof which is substantially contiguous with a side edge of one of the end said mounting plates, and at least one spacer block slidably received Within the other end of said elongated supporting means, said spacer block having a tapered face which is generally contiguous with a side edge of the other one of said end mounting plates, whereby said adjustable pin and said spacer block set said rollers, and the angle of the plane of the peripheries of said rollers with respect to the longitudinal axis of said elongated supporting means may be changed with extreme accuracy as the angle of said alternating ridges and valleys relative to the axis of said pipe being formed changes by varying said tapered f ace of said spacer block.

2. The improved segmented roll according to claim 1, wherein a spring plunger is utilized to retain said spacer block within said elongated supporting member.

3. The improved segmented roll according to claim 1, wherein said spacer block bears against the portion of one of said end mounting plates exterior of said supporting means.

4. The improved segmented roll according to claim 1, wherein said spacer block bears against the portion of one of said end mounting plates within said supporting means.

5. The improved segmented roll according to claim 1, wherein the angle that the tapered face of said spacer block makes with the longer edge thereof may be calculated from the formula:

J W/ H where J=the angle that the tapered face of said spacer block makes with the longer edge thereof;

W=the width of the strip of metal from which a spiral pipe is formed; and

H the mean circumference of the pipe being formed.

(c) elongated supporting means supporting said mount- 8 ing means with the peripheries of said rollers projecting therefrom, for engaging said ridges and valleys, said supporting means supporting said mounting means for movement along and with corresponding points on said rollers aligned parallel to the longitudinal axis of said supporting means, and for movement changing the angle of the planes of the peripheries of said rollers with respect to said longitudinal axis of said supporting means; and (d) means for shifting said mounting means parallel to said axis and for changing the angle of the planes of the peripheries of said rollers with respect to said longitudinal axis of said supporting means; the improvement wherein said mounting means comprises a plurality of independent mounting plates a portion of which are slidably mounted within and independently swingable with respect to said elongated supporting means, each said mounting plate having a slot therein for receipt of the circular portion of one of said rollers such that the periphery of said roller projects therefrom, and opposed parallel side edges which are generally contiguous with adjacent mounting plates, thereby maintaining the planes of the peripheries of said rollers parallel and spaced apart, whereby excessive dirt particles are prevented from accumulating in said elongated supporting means and so that the easy glide of adjacent mounting plates is maintained, and wherein said shifting means comprises a spacer block slidably received within each end of said elongated supporting means, each said spacer block having a substantially identical tapered face which is generally contiguous with a side edge of one of said end mounting I plates, and an adjustable pin at one end of said elongated supporting means, a portion of said adjustable pin being substantially contiguous with one of said spacer blocks, whereby said adjustable pin and said spacer blocks set said rollers, and the angle of the plane of the peripheries of said rollers with respect to the longitudinal axis of said elongated supporting means may be changed with extreme accuracy as the angle of said alternating ridges and valleys relative to the axis of said pipe being formed changes by varying said tapered face of said spacer blocks.

7. The improved segmented roll according to claim 6, wherein a spring plunger is utilized to retain each said spacer block within said elongated supporting member.

8. The improved segmented roll according to claim 6, wherein at least one of said spacer blocks bears against the portion of one of said end mounting plates exterior of said supporting means.

9. The improved segmented roll according to claim 6, wherein at least one of said spacer blocks bears against the portion of one of said end mounting plates within said supporting means.

10. The improved segmented roll according to claim 6, wherein the angle that the tapered face of said spacer block makes with the longer edge thereof may be calculated from the formula:

W=the width of the strip of metal from which a spiral pipe is formed; and

H=the mean circumference of the pipe being formed.

11. In a segmented roll for forming helically corrugated pipe by curling an elongated strip of sheet metal having longitudinally extending, alternating ridges and valleys therein, into a helical convolution, of the type having:

(c) elongated supporting means supporting said mounting means with the peripheries of said rollers projecting therefrom, for engaging said ridges and valleys, said supporting means supporting said mounting means for movement along and with corresponding points .on said rollers aligned parallel to the longitudinal axis of said supporting means, and for movement changing the angle of the planes of the periphcries of said rollers with respect to said longitudinal axis of said supporting means; and I (d) means for shifting said mounting means parallel to said axis and for changing the angle of the planes of the peripheries of said rollers with respect to said longitudinal axis of said supporting means; the improvement wherein said mounting means comprises a plurality of independent mounting plates a portion of which are slidably mounted within and independently swingable with respect to said elongated supporting means, each said mounting plate having a slot therein for receipt of the circular portion of one of said rollers such that the periphery of said roller projects therefrom, and opposed parallel side edges which are generally contiguous with adjacent mounting plates, thereby maintaining the planes of the peripheries of said rollers parallel and spaced apart, whereby excessive dirt particles are prevented from accumulating in said elongated supporting means and so that the easy glide of adjacent mounting plates is maintained, and wherein said shifting means comprises two 10 templet bars slidably mounted adjacent to and parallel with said elongated supporting means; means pivotally joining each said mounting plate with said templet bar; and means to actuate said templet bar so that said mounting plates may be rotated together to such said rollers, said actuating means including gear means joining said bar's such as said bars may be actuated together in opposite directions, the angle .of the plane of the peripheries of said rollers with respect to the longitudinal axis of said elongated supporting means may be changed with extreme accuracy as the angle of said alternating ridges and valleys relative to the axis of said pipe being formed changes by varying said tapered face of said spacer block.

References Cited UNITED STATES PATENTS 1,659,792 2/1928 Thorsby 7249 2,388,383 11/1945 Buczkoski 72143 3,247,692 4/1966 Davis 7249 CHARLES W. LANHAM, Primary Examiner R. M. ROGERS, Assistant Examiner US. Cl. X.R. 7249; 29-4773