US2515786A - Method and machine for forming pipe from flat sheets - Google Patents

Description

July 18, 1950 A. L. MITCHELL METHOD AND MACHINE FOR FORMING PIPE FROM FLAT SHEETS Filed Feb. 3, 1948 6 Sheets-Sheet l INVENTOR {IECH 4. MHZ/{ELL ,9 r TOENEY y 8, 1950 A. L. MITCHELL 2,515,786

METHOD AND MACHINE FOR FORMING PIPE FROM FLAT SHEETS Filed Feb. 5, 1948 6 Sheets-Sheet y 1950 A. L. MITCHELL 22 5 METHOD AND MACHINE FOR FORMING PIPE FROM FLAT SHEETS Filed Feb. 3, 1948 6 Sheets-Sheet 3 JNVENTOR.

AECH .L. MITCHELL M y 1950 A. L. MITCHELL 2,515,786

METHOD AND MACHINE FOR FORMING PIPE FROM FLAT SHEETS Filed Feb. 3, 1948 6 Sheets-Sheet 4 Fifi"; lU

INVENTOR. flEC/ L. lW/TC/JEAZ.

July 18, 1950 A. L. MITCHELL METHOD ANDMACHINE FOR FORMING PIPE FROM FLAT SHEETS Filed Feb. 5, 1948 6 Sheets-Sheet 5 R L w H m m V U EH EHM m M L H C R 3. av QWN qww R Q! s a Q a! S. sun: wu am am N! hi :5 9Q P2 a a. o QM q I 1 3w K-J H- U O I July 18, 1950 A. 1.. MITCHELL 2,515,786

M 'ruon AND MACHINE FOR FORMING PIPE FROM FLAT SHEETS Filed Feb. 3, 1948 6 Sheets-Sheet 6 f'IE l 'Z INVENTOR. flRC/v L. M/TCA/ELL A TTOR/VE) Patented July 18, 1950 METHOD AND MACHINE FOR FORMING PIPE FRQM FLAT SHEETS Arch L. Mitchell, Oakland, Calif., assignor, by direct and mesne assignments, of two-tenths to Dorothy M. Clifford and five-tenths to Kenneth R. Clifford Application February 3, 1948, Serial No. 5,924

37 Claims. 1

This invention relates to the art of forming pipes by bending fiat sheets of metal or other material in tubular shape. The invention constitutes an improvement on the method and machine disclosed in the U. S. patent to Miller, No. 1,718,753, and the following disclosure is to be read in connection with the disclosure of said patent.

The aforesaid Miller patent relates to a machine having a cylindrical mandrel conforming to the inside surface of the pipe to be formed. The mandrel is supported by an axle disposed horizontally, and is movable vertically within guides or standards. When the mandrel is in a raised position a sheet of metal is placed beneath it on rollers spaced apart a distance equal to the external diameter of the pipe. The mandrel is then forced downward against the sheet, thereby bending the sheet into a trough-like shape. Thereafter the rollers are moved upwardly about the mandrel axis to roll the sheet about the upper half of the mandrel. The resulting tube is removed from the mandrel by lifting the mandrel and tilting it to clear the axle support at the discharge end and then sliding the formed tube from the mandrel.

A particular feature of the Miller machine is that it is capable of bending the sheet all the way to and including the ends of the tube, and that it avoids outwardly flared corners at the seam ends, thereby effecting considerable savings in labor which would otherwise be required for straightening the ends, and insuring proper alignment of the ends of adjacent sections and facilitating welding when laying the sections end to end. A further feature is that the machine is of a type which can be constructed of any desired length, for forming tubes of any length, limited only by the available size of sheets and by the capacity of equipment for moving the fin ished pipe, thereby minimizing the need for numerous welded connections.

The machine according to the Miller patent is not, however, readily adaptable for forming pipes of different sizes or wall thickness, and the operations involved in forming and removing the pipe are cumbersome. The operations must be carefully supervised and controlled by a skilled operator; therefore, the machine is not suitable for automatic operation. Moreover, the machine is not adapted for moving a roller over the seam to insure perfect forming.

It is an object of the present invention to provide improvements in the Miller pipe forming method and machine to overcome certain operating difficulties inherent therein, to form a more even seam, and to make the machine more versatile and adapted for either manual ,or semior fully-automatic operation. The control mechanism for achieving such semior fully-automatic operation is not, however, a part of the instant invention and will be only incidentally referred to.

A further object is to provide a pipe forming machine in which the forming rollers on the two sides of the pipe are independently operable so as to be movable over the pipe seam to insure a more perfect shaping of the pipe edges; and to provide an improved method wherein the forming rollers are moved over the pipe and seam in an improved manner.

Another object is to provide an improved mandrel which is readily expanded or contracted to change the diameter of the mandrel for forming pipes of different diameters, and/or of different wall thicknesses, and/or for facilitating the removal of the formed pipe from the mandrel; and to provide a mandrel having a welding strip of copper or other suitable material to permit the pipe seam to be welded on the mandrel.

Another object is to provide an improved supporting framework or mounting for the forming rollers by journalling them on arcuate segmental racks supported on dollies, whereby the racks and the rollers are given a floating support and the pivotal support of the Miller machine is avoided, thereby giving freedom of action and eliminating the obstruction to the movement of the pipe by the pivotal connection at the discharge end of the mandrel. A further feature of this floating support is that it permits any desired number of segmental racks to be placed at points intermediate the ends of the mandrel, thereby affording a better support for the forming rollers and permitting longer pipes to be formed.

Another object is to provide an improved pipe forming machine wherein the forming rollers are adjustably mounted on the movable mechanism, for example, on the segmental racks previously referred to, whereby the interval between the rollers can be rapidly varied for forming pipes of different external diameters. Such rollers may be used with a non-adjustable mandrel to permit pipes of different wall thickness to be 1 formed, or with an adjustable mandrel to form pipes of different internal diameters. Ancillary thereto, it is an object to provide a system of shafts and ears for rapidly and uniformly adjusting the rollers to difierent intervals.

Another object is to provide auxiliary rollers for engaging the lower portion of the pipe (i. e., the part bent about the mandrel during the first, downward movement thereof) for ironing out the sheet around the mandrel and for providing an additional guiding support for the segmental racks.

Still a further object is to provide an improved supporting and actuating structure for the mandrel which obviates the need for removing the mandrel from the machine for the removal of the formed pipe. Ancillary thereto, it is an object to provide an improved mechanism for removing the formed pipe from the mandrel, comprising a longitudinally slidable ejecting bar and a cradle or saddle arranged to support the pipe and mandrel both vertically and laterally when the mandrel axle is freed from its support at the discharge end, and to support the mandrel above the ejecting bar after the removal of the pipe and during the reciprocation of the ejecting bar.

With the foregoing and other objects in view, some of which will be explained and pointed out in the course of the following description, and some of which will be apparent therefrom, reference is made to the accompanying drawings forming a part of this specification and illustrating one specific embodiment for carrying out my invention, it being understood that the invention can be otherwise embodied and that such drawings are not to be construed as limiting the scope of the invention and improvements.

In the drawings:

Fig. 1 is a plan view of a machine embodying the invention;

Fig. 2 is an elevation view thereof, partly in section;

Fig. 3 is an end elevation View of the B or discharge end;

Fig. 4 is a transverse sectional view taken on line 4 s of Fig. 2', showing the construction of the mandrel, the vertically adjustable and slidable ejecting bar and the vertically adjustable cradle;

Fig. 5 is a transverse sectional view taken on line 5-5 of Fig. 2, showing one of the intermediate frames and the segmental rack associated therewith;

Fig. 6 is a plan view of the cradle rollers at one of the saddle frames, showing the drive mechanism for the ejecting bar;

Fig. 7 is a horizontal sectional view, taken on line l'! of Fig. 2, showing the construction of the mandrel and the movable leaves;

Fig. 8 is a view similar to Fig. 7, but showing only portions thereof, illustrating a contracted adjustment of the mandrel;

Fig. 9 is a horizontal sectional view, taken on line 99' of Fig. 2, showing the mandrel. axle support at the 13- end;

Figs. 10, ll, 12, 13 and 14 are end elevation views of the A or operating end, showing successive operations performed by the machine, certain parts being omitted in Figs. 11-14;

Fig. 15 is an elevation view of a portion of the tube, mandrel and ejecting bar, showing the pipe being ejected;

Fig. 16 isan enlarged vertical longitudinal sectional view taken on line 16-46 of Fig. 1.; and

Fig. 17 is a horizontal sectional. view taken on line 11-41 of Fig. 16.

Referring to the drawings, and particularly to Figs. 1-3, 16 and 1'7, themachine comprises, two ends: an operating or A end (appearing at the left in Figs. 1 and 2) and an exit or 13 end. The machine is supported by a plurality of transverse frames 20 and 22, arranged in pairs, one on each side of transverse plates 22a. These frames may be fastened to any suitable base or to the floor. The frames 22 are of similar construction; the. end frame 20 at the A end is taller to provide av guide for the mandrel axle, asdescribed hereinafter. The. frames 22 and plates 22a have upstanding side portions and downwardly recessed central portions forming a free space for movement of the mandrel and the tubular work formed thereon. A plurality of dollies 2d are journalled on longitudinal shafts secured to the frames 22 and plates 22a to form circular series of supports for segmental racks 26R. and 26L (the letters R and L being appended to reference characters in this specification to designate like parts applied to the right and left sides, respectively, of the machine). Each segmental rack has a pair of arcuate trackways 23, providing smooth exterior and interior surfaces for engaging the dollies 2 3' (Figs. 2 and 5). While I prefer to use dollies running on smooth trackways, it is evident that rollers of any type, e. g., toothed free rolling pinions, can be used. The racks are longitudinally offset, to permit both to be rotated to their downward positions without interference. An arcuate rack gear 30 is formed integrally with each rack gear intermediate to the smooth trackways 28 on the exterior or lower face; this gear meshes with drive pinion 32R or 32L, mounted on longitudinal shafts journalled in the transverse frames. It will be noted that the trackways 28 and dollies 2d constrain the supported segmental racks to rotate substantially along the arc of a circle as the drive pinion is rotated. The racks are arranged so that all rotate about a common longitudinal axis. The pinions 32R are driven independently of the pinions 32L to permit independent operation of the segmental racks. These racks are seen to be of arcuate construction, whereby they provide open spaces for passage of a mandrel and of the tubular work between the racks at and about said common axis.

A pair of leaves MR and 34L are adjustably bolted to the segmental racks 26R and 26L, respectively, by bolts 86 extending downwardly through transverse slots in the leaves and through holes in the racks. The leaves are spaced apart to provide a mandrel opening between them and carry at their inner edges a plurality of forming rollers 33, which are free-rolling and journalled on spindles supported by projections on the leaves, as shown. The leaves may, if desired, be

I provided with anti-friction rollers and guides on their upper faces as disclosed in the aforesaid Miller patent to facilitate the introduction of a fiat sheet of metal. The leaves are easily adjusted for forming pipes of different external diameters by loosening the bolts 36 and sliding the leaves transversely on the segmental racks. To facilitate this adjustment the lower faces of the leaves have a plurality of transverse, serrated or geared strips, forming rack gears meshing with pinions dim, and ML mounted on longitudinal shafts 32R. and ML respectively. These pinions are in engagement with the serrated portions of the leaves only when the leaves and their supporting segmental racks are in their lowered positions, as shown in Figs. 3, 10, 11 and 14; when they are elevated by rotating the segmental racks on the dollies 2-!- to the positions shown in Figs. 12-13, the leaves are raised from their pinions.

The drive pinions 32R and. 32L are mounted on main, longitudinal drive shafts, journalled in pillow blocks on the transverse frames. Only the main drive shaft 4 3R. appears in Fig. 2, driving the pinions 3218,; a similar main drive shaft 44L on. the left side drives pinions 32L. The shaft MB is driven by a bevel gear 46R from a gear box d8 through a transverse shaft 50R and bevel gear MR, and the shaft il-iL is driven through a similar bevel gear 16L meshing with a bevel gear on a transverse shaft (not visible in the drawings) from the gear box 58. The gear box 48 takes power from an electric motor 52 and motor shaft 54, and contains suitable clutch mechanisms for applying power to the shafts 44R and ML, independently of one another. These clutches may be controlled mechanically or electrically from the operators stand at the A end for manual operation, or may be controlled electrically by a time sequence mechanism 56. The time sequence mechanism and the clutch mechanisms within the gear box may be constructed in conformity with well known engineering practice. It is, therefore, not believed to be necessary to illustrate or describe these parts in detail in this specification. It will sufiice to state that the gear box and the time sequence mechanism 56, if used, are arranged to connect the drive shaft 54 to the transverse shafts connected to the bevel gear 51R (andthe bevel gear at the left side) to move the segmental racks and the rollers 38 in the successive movements described hereinafter under the heading Operation.

The shafts 42R and 42L are journalled in pillow blocks in the transverse frames and carry bevel gears. The gear 51R meshes with the bevel gear 583 as shown in Figs. 2 and 1'7; a corresponding pair of gears 51L and 58L are provided for the shaft ML. The bevel gears are driven by vertical shafts (shaft 6BR only being shown), and the two vertical shafts are geared through bevel gears to a transverse shaft El to which a handwheel 62 is secured. By operating the handwheel (52 the shafts 42R and 42L are rotated simultaneously in opposite directions, thereby operating their pinions 40R and AOL for moving the leaves MR and 34L apart or together after the bolts 46 have been unclamped. As will be explained hereafter, the rollers 38 form the pipe by bending a flat sheet about the mandrel. The adjustment by means of the handwheel 52 permits the interval between these rollers to be easily adjusted, thereby eliminating the need for costly tooling up when pipes of different sizes are to be formed. After the adjustment has been completed the bolts 3% are firmly clamped.

The mandrel according to this invention is indicated generally at 64. It is in the form of a cylinder of generally circular cross-section and its outer surface is formed by a plurality of longitudinal bars 66 forming sectors which are arranged at the periphery and are movable radially inwardly or outwardly to change the exterior diameter of the mandrel (Figs. 4 and 7-9). There will necessarily be longitudinal spaces between adjacent sectors 66 (except when the mandrel is adjusted to its smallest diameter) hence, these sectors are made numerically sufiicient and of proper widths to effect a perfect cylindrical forming of the pipe when the sheet is bent or curved about it. In the embodiment shown twenty-four sectors are used, but the invention is not limited to the use of such a number of sectors, and I may employ a smaller or a greater number. The outer face of each sector is preferably curved with a radius of curvature corresponding to a pipe of average size which may be formed on the machine or, if desired, to a pipe of the size which is tobe formed most frequently. The particular machine described herein is designed to form pipe in any desired size from 8-inch to 30-inch diameter; hence the sectors have their outer surfaces formed with a radium of curvature of nine and one half inches.

The mandrel 64 is supported by a tubular main axle 68 extending the entire length of the mandrel and projecting at each end beyond the sectors 66. The main axle contains subaxles 10 and 72 mounted slidably and concentrically within it. Mandrel-expanding arms 14 connect each sector 66 to the subaxle 10 at a plurality of support points along the axle, there being a separate arm i l for each sector. Such clusters of arms may be located at a sufficient number of points along the mandrel axis to afford adequate support for the sectors, for example, at intervals of three feet. The clusters may contain one arm for each sector, or, as shown in the drawing, the arms may be grouped into two or more clusters for structural reasons. The arms 14 extend into recesses in the inner faces of the sectors 66 and are connected pivotally thereto by pins 16. They extend radially inwardly through slots in the main axle 68 and their inner, rounded ends abut an annular groove on the subaxle Ill. The inner ends are secured by a ring 18 passing through holes in the several arms, these holes being located at the centers of curvature of the arcs defining the curved ends of the arms. There is one such ring for each cluster of radial arms. To avoid undue weakening of the main axle 68 by cutting twentyfour slots therethrough at each support point, I may connect only every alternate arm at one location and connect the other arms a short distance away. This is shown in Figs. '7 and 8, wherein the arms M are shown for supporting ever second sector at one connecting point, and the arms Ma are connected to the alternate sectors omitted from Fig. 16 for clarity. It will be evident that as the subaxle 10 and the sectors 66 are displaced longitudinally one with respect to the other the angular disposition of the mandrel expanding arms 14 and Ma with respect to the axis of the axle is varied, thereby varying the radial distance from the mandrel axis to the sectors. In this adjustment the arms M and 14a are guided circumferentially by the slots in the axle 68, but do not engage the axle 68 longitudinally.

To effect the necessary relative longitudinal movement between the sectors 66 and the subaxle 1!! it is necessary to support the sectors longitudinally. This may be achieved by any suitable mechanical arrangement. To effect a uniform support along the length of the mandrel it is preferred to employ the following arrangement: A second set of mandrel expanding arms is provided at a plurality of points, extending from the tubular main axle 68 to the sectors. These arms are secured to the sectors by means of pins and extend into recesses, as described for the arms 74 their rounded inner ends are in abutment with annular grooves in the main axle G8 and are secured by a ring 82, corresponding to the ring 18, and similarly connected. Clusters of arms 80 may be placed opposite each cluster of arms 14, and such an arrangement'is preferred to prevent buckling of the sectors; however, it is not in every case essential to the practice of the invention that there be such correspondence. By this arrangement a relative movement of the main tubular axle 68 and the subaxle TI] is sufficient to effect the desired radial adjustment of the sectors 66. During this adjustment there is some longitudinal displacement of the sectors with respect to the axle 68; however, this motion is moderate, and with the inclinations and relative lengths of the arms 14 and 80 shown may amount, for example, to less than twelve inches in the case of a mandrel adjusted between diameters of eight and thirty inches. The axle 68 is vertically slidable at the A end 7 in a slot 84. in the end frame 20 and secured against axial movement relative to the frame by engagement with opposite faces of the frame by bushings 86 and 88 (Figs. 2, 7, 10 and 16). The bushing 88 is fixed to the upper end of an operating rod 89 which is vertically reciprocable and driven by a fluid driven motor 90. In the embodiment shown the motor 90 is a pneumatic or hydraulic cylinder containing a piston connected to the rod 89, the cylinder being double-acting, i. e., arranged to move the rod 89 by power upwardly or downwardly for raising or lowering the mandrel. The motor is supplied with high pressure operating fluid from a pump or compressor (not shown) through lines 92 and 9t, and spent, low pressure fluid is discharged through a line 98 and returned to the fluid reservoir from which the pumpor compressor takes suction. The lines 92 and 95 are controlled by valves 98 and let, located at the operators stand (not shown) at the operating or A end. These valves may, if desired, be arranged for automatic operation by the time sequence mechanism 56 when the machine is fitted for semior fully-automatic operation. It will be understood that any reciprocating or rotary hydraulic or electric motor of approved type may be employed for elevating or lowering the mandrel, such devices being well known in themselves.

A similar hydraulic motor I02 is mounted at the B end (Figs. 2 and 3), provided with fluid supply and discharge lines corresponding to those previously described for motor 99, and collectively indicated at Hi4; these lines may be similarly provided with control valves I03 and H35 whichmaybe at the operators stand and arranged by suitable control means, not shown, for actuation by the time sequence mechanism 56. This hydraulic motor has its output'in a similar VI-. tically movable operating rod 36 carrying at its upper end a cradle I538 with outwardly flared upstanding portions for centering and supporting the axle 68. The cradle N58 is detachably se-v cured to the axle 68 for pulling the axle down with the rod H16 when it is connected, and for moving the rod H16 downwards away from the mandrel axis and clear of the bottom thereof when detached. As shown in Fig. 9, the detachable connection comprises a pair of movable, flat lugs H which extend radially and horizontally outwards from the axle into laterally extending, horizontal slots H2 in the upstanding side portions of the cradle Hi8. These lugs are pivoted to the innermost subaxle I2 at a flattened por tion thereof on a vertical pin and extend outwardly through slots in the main axle 58, the slots in the subaxle iii being of sufficient length to permit the relative movement between it and the main axle 68 previously described for adjuste ing the mandrel diameter without engagement of the slot ends with the lugs H0. Each lug has an inclined slot H4 through which passes a pin fixed to th main axle E8 and connecting the slot walls thereof. As shown in solid lines in Fig. 9, the lugs are positioned to connect the axle to the cradle. When the subaxle I2 is moved to the left the lugs are retracted to the positions shown in dotted lines, thereby disconnectingthem from the cradle. It will be noted that the fram 22 at the B end does not extend upwardly above the bottom of the mandrel when the latter is in its lowest position and adjusted for its largest diameter, and that the mandrel axle is not laterally supported at this end.

For actuating the subaxles I0 and 12 with respect to the main axle 68 there are two fluid motors, H6 and H8, respectively, mounted on the bushing 88 and provided with the necessary fluid supply and discharge lines, indicated collectively at I20 (Fig. 1.), for permitting independent operation of the motors in either direction. The motor I It or pinion 22 may be provided with any suitable hydraulic or mechanical lock or stop for holding the axles "68 and I9 relatively fixed after they have been adjusted. As shown in Figs. 7, 8 and 16, the motor I I6 drives a pinion I22, meshing with a geared portion of the subaxle In, said geared portion extending longitudinally along the subaxle, whereby rotation of the pinion will cause reciprocation thereof. Similarly, the motor H8 drives a pinion I2fi meshing with a similar geared portion on the subaxle I2, there being a slot in the side Wall of the subaxle iii to permit the pinion I24 to engage the innermost subaxle 212. While I have shown hydraulic motors for reciprocating the subaxles longitudinally with respect to the main axle 58, it should be noted that the instant invention is not limited to any specific arrangement for effecting such motions, and that any mechanism may be substituted therefor, and that the hydraulic arrangement has been selected for the illustrative embodiment because of its sim plicity. Moreover, the pinion I22 and/or the pinion I24 may be operated manually by means of a handwheel or the like. The supply lines I28 are provided with control valves (not shown) which may be located at the operators stand and may, if desired, be actuated by the time sequence mechanism 56.

The uppermost sectors 68 of the mandrel are of special construction and differ from the other sectors in that they are faced with a backing strip I26 for welding the pipe seam while it is on the mandrel (Figs. 3, 4 and 16). These strips may be made of any metal suitable as backing strips for welding, such as copper or a cuprous or similar metal alloy not readily welded to the steel or iron sheet of which the tube is to be formed. The other sectors and the bodies of the uppermost sectors may bemade ,of steel r a ferrous lloy.

An ejecting bar I28 extends longitudinally at the Center of the machine beneath the mandrel. It has an upwardly extending projection I30 at the A end, ferming a hook or engaging means for pulling the pipe off of the mandrel in the manner shown in Fig. 15. This bar may have a hat upper face or a face upwardly concave in cross section with a radius of curvature corresponding to the radius of a pipe of average size,

as shown. The lower face of the bar is serrated to form a rack gear meshing with supporting and driving pinions I32, there being a plurality of such pinions along the length of the machine, e. g,, twelve, arranged four between each pair of transverse frames 22 (Figs. 4, 6 and 1.6). The pinions are fixed to transverse shafts ltd journalled in vertically movable saddle frames J36 having depending rods I38 slidable within vertical cylinders his which may be secured to a base or to the floor. The bar I28 is guided by vertical fingers 436a. on the saddle frames. A mechanical stop of any convenient form, such as a clamp M2, is provided for each cylinder M0 to secure the rod 138 at any vertically adjusted position and afford a solid support for the saddle frame and the parts of the machine resting thereon. It will be understood that the saddle frame must be moved vertically when the machine is adjusted initially, or when it is being changed to form pipe of a different diameter, the adjustment being such that the bottom of the mandrel will be above the top of the ejecting bar by a distance equal to the thickness of the pipe when the mandrel is in its lowest position. The pipe will thereby rest on the ejecting bar as shown in Fig. 15.

For aifording lateral support to the pipe and/or mandrel at the B end, and for supporting the mandrel vertically at the B end when the cradle I08 is disconnected and the pipe is bein or has been ejected, I provide a saddle having vertically movable support members arranged to engage the mandrel in their upper positions and to impose some upwardly converging support thereon, tending to center the mandrel. In one aspect, the saddle comprises support members which are movable vertically with respect to the ejecting bar to support the mandrel after the trailing ed e of the formed pipe (i. e., the end toward the A end of the machine) has passed the support member; the vertical movement may be effected by any desired mechanism, such as spring or mechanical devices including levers or cams synchronized with the ejection of the pipe, and such members may or may not engage the pipe when in their downward position, and may or may not be longitudinally movable.

More specifically, in the embodiment illustrated herein, the saddle comprises one or more roups of rollers I44, each group having at least one roller on each side of the ejecting ba I 28. The rollers in each group are arranged. to provide a supporting surface which is curved to conform to the curvature of the mandrel in any adjusted size thereof (Fig. 4) stated in another way, the rollers I44 on each side of the ejecting bar I28 may move up or down so that all rollers bear on the mandrel despite changes in the diameter of the mandrel when the mandrel is on or a short distance above the bar I28. I may, in certain cases, provide a single group of such rollers, or two of such groups, located near or at the B end, or many groups all along the length of the mandrel, but prefer to provide a plurality of such groups, for example, one group for each of the pinions I32 between the midpoint of the machine and the B end.

Referring to Figs. 2, e, 6 and 17, I have provided four rollers I44 in each group, arranged two on each side of the ejecting bar. Each roller has outwardly convex surfaces of revolution to insure smooth contact with the supported pipe or mandrel despite the fact that for some sizes of the mandrel the axis of the roller may not be parallel to the tangent to the pipe or mandrel at the point of contact. The rollers I44 are free-rolling and are journalled in individual cradles I46 having square shafts slidably mounted in the saddle frame I36. (The frames I36 between the A end and the midpoint of the machine are not necessarily provided with rollers.) The shafts are inclined to diverge downwardly from the mandrel axis when the mandrel is adjusted to an average diameter and is resting on the ejecting bar I28. The cradles I 40 are urged upwardly by springs I48. It is evident that the resilient mounting for the cradles I45 permits them to rise or descend to bring the rollers I44 into engagement with the mandrel in any adjusted size of the mandrel, while the curved shape of the rollers insures even contact.

The stiffness of the springs I40 is such that the rollers I44 will support the weight of the mandrel alone a distance above the ejecting bar approximately equal to the thickness of the pipe. This will afford support for the mandrel at the B end after the pipe has been removed from the mandrel while the ejecting bar is moved to the left, without scrapin of the projection I30 against the bottom of the mandrel. When a pipe is on the mandrel the combined weight of the mandrel and pipe is sufficient to compress the springs I48 sufficiently to bring the pipe down against the ejecting bar and permit the projection I30 to engage the trailing end of the pipe. It might be supposed that when a pipe of light weight is formed the Weight of the pipe may be insuificient to insure compression of the springs, because the upward thrust of the springs increases progressively during compression. However, it should be noted that the springs I44 are relatively long in comparison to the thickness of the pipe, so that the thrust of the springs is changed only very slightly during compression through a distance equal to the thickness of the pipe. Moreover, when light weight pipe is formed the diameters of the mandrel and pipe are usually comparatively small; in this case the outermost rollers I44 are more elevated and their springs I48 are more extended than when pipe of larger diameter is formed, and the springs, therefore, exert a smaller upward force. These effects overcome the supposed difficulty previously noted, with the result that satisfactory operation is achieved.

While I have in the foregoing paragraphs described the preferred embodiment of the invention, includin vertically movable supports, it should be noted that the supports need not in every case be vertically movable with respect to the ejecting bar, and/or that rollers may be omitted, and that the invention is not to be limited to the specific arrangement shown. Thus, by fixing the cradles M6 to the saddle frames I36 and thereby providing stationary supports on one or more of the saddle frames near the B end, the machine can be operated without the springs I48. In this event the ejecting bar is preferably moved only a short distance, say one fourth of the length of the mandrel and the pipe is pulled from the machine by any external engaging means. As the trailing edge of the pipe passes the last support the B end of the mandrel drops onto the stationary supports a distance equal to the thickness of the pipe; the mandrel will not, however, engage the projection I30 because the A end of the mandrel is supported by its axle 68 if the height of the projection I36 is less than /4, of the height through which the B end dropped. Moreover, the pinions I32 can be mounted on an incline, downwardly to the 13 end to prevent contact of the mandrel with th projection I30.

The saddle frames I36 and rods I38 may be adjusted vertically by loosening the mechanical clamps I42 and applying a suitable implement such as a mechanical or hydraulic jack to the frames. I may, optionally, provide a linkage for simultaneous adjustment of all of the frames bya power device. In this preferred arrangement a pair of longitudinal operating bars I50R and I53L is connected to each cylinder I40 by pivotal connections to a pair of downwardly extending links I52 and a pair of upwardly extending links I54; these links are further pivoted at their outer ends to the cylinder I40 and to the rod I38, respectively. A fluid motor I56, such as an air or hydraulic cylinder with a reciprocable piston, is connected by links I58 to the operating bars I50R and I50L.

When fluid under pressure is admitted to the motor I56 through a supply conduit I66, controlled by a valve I62, the operating bars are pulled toward the B end. It is evident that the operating bars will swing in translatory motion upwards as the links I52 rotate clockwise about the cylinders M6. Simultaneously the links I54 move counter-clockwise, thereby lifting the rods I38. When fluid is discharged from the motor via conduit I64 the weight of the saddle frames and supported parts collapses the links I52 and I54, thereby moving the operating bars IIJR. and I5IlL toward the A end. I may, of course, employ a hydraulic motor which is double acting, for applying power to the operating bars in both directions; a second supply conduit I6! is, in this case, necessary.

- The pinions I32 are power driven through bevel gears secured to the shafts I34 from a longitudinal shaft I66 j-ournalled in the saddle frames I36 (see Fig. 6). The shaft I66 drives through bevel gears "I68 at the lower and upper ends of shaft 161 'jou'rn'alled in brackets on the saddle frames. Shaft I66 is driven thru bevel gears I69 from a vertical splined shaft I extending into the gear box 48. The splined shaft I1!) is verticallyextenside to permit transmission of power although the saddle frames carrying the shaft I66 are adjusted vertically. This shaft I16 is driven from the motor 52 by clutch devices in the gear box 48 and may be controlled manually from the operators stand or by the time sequence mechanism 56.

The segmental racks 26R and 26L may option ally be provided with upwardly and inwardly extending projections I12, supporting free rolling rollers I14 (see Figs. 3 and 5). These rollers are adjusted to be in engagement with the pipe about the mandrel and serve two functions: they iron out irregularities at the under part of the pipe and afford further guiding means for the racks, which are in floating'support in the dollies 24. For radial adjustment the projections I12 are ,slidably mounted in guideways on the racks and clamped by bolts and nuts I16.

Operation The machine having been adjusted for the size of pipe to be formed the successive operations are as follows:

1. The mandrel is raised to the position shown in Fig. 10 and the axle 68 is connected to the cradle I68 by operation of the fluid motor H8 to move the subaxle 12 toward the B end and thereby sliding the lugs Ill] outwardly.

2. -A flat "sheet, such as a sheet of metal I18, is fed onto the machine from the side, coming to rest on the leaves 34R and 34L, under the mandrel 64, as Shown in Fig. 10.

3. The hydraulic motors and I 62 are operated'to pull 'the mandrel down into the mandrel opening to the position shown in Fig. 11. With the mandrel axis substantially coaxial with the common axis of rotation of the segmental racks. The sheet I18 isv thereby bent through approximately 180 into a trough-like shape about the bottom sector of the mandrel .while the sheet is engagement with the forming rollers 38. When the mandrel is fully lowered the sheet I18 is in engagement with the ejecting bar I 28 and the saddle rollers I44, as well as with the auxiliary rollers I 14, when provided.

4. The motor 552 and gear, box 48 are operated to rotate the pinions 32R and 32L simultaneously in opposite directions, thereby rotating the segmental racks 26R and 26L upwardly and moving the forming rollers 38 along the two upstanding ends of the sheet I16 to curve or roll it about the upper sector of the mandrel. The clutchin the gear box id is preferably operated to stop the upward movement of the racks 26L after about and to stop the upward movement of the racks 26R after completing 92, thereby insuring a complete rolling of the right edge of sheet end without abutting the not yet rolled left edge. The inial simultaneous movement of the rollers balances the lateral forces and eliminates strain on the mandrel. During the last 10 of movement the thrust is mainly downward, and the stationary rollers aid in steadying the mandrel. The rack 2GP. is then retracted a convenient distance, say to 17, and the rack 26L is simultaneously advanced to move over the seam and onto the right sheet end, e. g., to 95. This operation is illustrated in Fig. '12of the drawings. The difference between the angular limits of travel, 92 and 95 is due to the fact that the rollers 38 on the right leaf 3 .13. passes only slightly beyond the top of the mandrel, but not far enough to move off the edge of the sheet I13 onto the mandrel or up against the opposededge of the sheet; the rollers 38 on the left leaf ML, however, can roll entirely over the pipe seam, indicated at Il8-d, because by this time the right sheet end has been rolled down. The racks 26R and 26L may, if desired, be further operated to pass over the seam one or more times, for example, four times, to insure a perfectly smooth seam. During these operations the ejecting bar and saddle rollers aid in secur ing the pipe sheet Iii; against rotation on the mandrel.

During the foregoing step the auxiliary rollers I1 5 iron out irregularities in the sheet at the lower portion and sides of the pipe, to the height indicated in Fig. 12.

While I have, in the foregoing, described a preferred method for operating the rollers 38, it should be understood that my invention is not limited thereto, and that I may employ the technique described in the Miller patent.

5. The segmental racks are retracted slightly, e. g., to 67, as shown in Fig. 13, spaced apart sufficiently only to allow a welding head I80 to pass between the leaves 3 3R and 34L, thereby acting as clamps to hold the sheet rigidly in place until welding and grinding are completed. The welding head I83 may be supported on any suitable overhead, structure having a horizontal trackway (not shown) permitting the head to move along the pipe seam I'I'Ba. The welding head moves along the pipe seam above the weld* ing strips I26. Optionally, the rollers 38 may be passed one or more times over the welded seam.

6. The segmental racks 25R and 26L are retracted to normalcy of 45, or to their downward positions of 0 asshown in Fig. 14.

7. The hydraulic motor H3 is operated to disengage the axle 68 from the cradle I08. If desired, the motor I62 is operated slightly prior to this disengaging operation so as to relieve any vertical stress on the lugs III) and insure easy operation without the danger of a jumping movement of the mandrel upon retraction of the lugs. After the lugs have been retracted the motor I02 is operated to lower the cradle I 08 below the level of the ejecting bar I28.

8. The finished pipe is ejected by operation of the ejecting bar I28 through the shafts I66 and I10. Optionally, the mandrel may be contracted slightly by operating the hydraulic motor H6; this may be necessary in certain situations when the pipe'binds to the mandrel. In the usual case,

however, it is not necessary to contract the mandrel and such contraction is usually not desired because it necessitates readjustment of the mandrel before the next piece of pipe can be formed. In one mode of operating the machine the ejecting bar is moved toward the B end only a relatively short distance, e. g., one fourth of the length of the machine, moving the pipe with it as shown in Fig. 15. The pipe is then pulled out onto a table provided with supporting rollers (not shown) by external means. I may, however, also move the bar I28 toward the B end until the projection I3ll is opposite the B end of the mandrel; in this method of operation the receiving table must be provided with supporting pinions for supporting the bar I28. When the pipe has been removed from the mandrel the latter is supported on the rollers IM.

9. The ejecting bar I28 is returned to its normal position by reversing the pinions I32. Thereafter the motor M22 is operated to raise the cradle I08 and support the axle 68.

Adjustment As will be evident from the operations described above, the diameter of the mandrel must be adjusted prior to the pipe forming operation by operating the motor I I6 to make the mandrel diameter conform to the desired internal diameter of the pipe, and the leaves 34R and 34L and the projections I12 must be adjusted to bring the rollers 33 and auxiliary rollers I14 into close engagement with the outside of the pipe. The leaves 34R and 34L are conveniently adjusted by means of pinions 40R and 40L and handwheel 62. While One handwheel for simultaneously adjusting both leaves has been described, it is evident that separate handwheels for separate adjustment of the leaves may be provided. The projections I12 must be adjusted manually. The saddle frames are adjusted by means of motor I56 to a height at which the pipe will rest on the ejecting bar I28 when the mandrel is pulled down to the position shown in Fig. 11. It should be noted that the axle of the mandrel is always in the same position when the mandrel is in its downward position, regardless of the adjusted diameter of the mandrel.

The dollies 24 are, as previously stated, located on arcs of circles having their centers on the common axis of rotation of the segmental racks, leaves and forming rollers. This common axis is essentially coextensive with the mandrel axis when the mandrel is-pulled down; however, these two axes are not exactly the same, it being preferred to have the mandrel axis slightly higher than said common axis by an amount to take care of play in the dollies and deformation of the racks 26R and 26L due to mechanical stress. The required locations of the dollies to compensate for these factors and to insure an even radially inward pressure of the forming rollers 38 against the ends of the sheet I18 can be readily calculated by methods well known to engineers and need not be further described in this specification.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. The method of bending a sheet into tubular form about a mandrel comprising the steps of placing the sheet on a base having a mandrel opening therein, forcing the sheet into the opening by means of a mandrel, whereby the intermediate portion of the sheet is'bent about that portion of the mandrel forced into the opening, thereafter swinging a first set of rollers on one side of the mandrel and a second set of rollers on the other side of the mandrel over the ends of the sheet so as to bend the sheet ends over the outer portion of the mandrel until the first set of rollers is substantially over the edge of one sheet end, and thereafter retracting said first set of rollers and advancing the second set of rollers beyond the edge of the other end and onto the adjacent edge of said one sheet end.

2. The method of bending a sheet into tubular form about a mandrel comprising the steps of placing the sheet on a base having a mandrel opening therein, forcing the sheet into the opening by means of a mandrel, whereby the intermediate portion of the sheet is bent about that portion of the mandrel forced into the opening, thereafter simultaneously swinging a first set of rollers on one side of the mandrel and a second set of rollers 0n the other side of the mandrel from said base over the ends of the sheet so as to bend the sheet ends over the outer portion of the mandrel until both sets of rollers are within about 10 of arc of the edges of their respective sheet ends, the rolling force being exerted on the two sheet ends at points opposite to each other for balancing out each other and eliminating strain on the mandrel, thereafter stopping the motion of the second set of rollers and continuing the motion of the first set of rollers entirely to the edge of the sheet end engaged thereby, and retracting said first set of rollers and advancing the second set of rollers beyond the edge of the other sheet end engaged thereby and onto the edge of the sheet end engaged by the first set of rollers.

3. A pipe forming machine comprising, in combination, a plurality of transverse frames having upstanding side portions and upwardly concave, recessed central portions forming a space for movement of a mandrel, two groups of dollies on each frame mounted for individual rotations on longitudinal axes, the first group having upwardly directed support faces tangent to a transverse first circle and the second group having downwardly directed guide faces tangent to a transverse second circle, said first and second circles for the several frames having their centers on a common longitudinal axis above the central part of the frames, two sets of transverse segmental racks, each rack having a downwardly directed arcuate track conforming to said first circle and supported by a first group of dollies and an upwardly directed track conforming to said second circle and guidingly engaging a second group of dollies, a pair of longitudinally elongated leaves above the sides of said frames spaced apart to provide a mandrel opening between them, one of said leaves being secured to one of said sets of racks and the other leaf being secured to the other set of racks, whereby each leaf may be moved about said common axis, a mandrel movable between the leaves into and out of the mandrel opening and in its outer position permitting a sheet to be placed on the leaves beneath the mandrel, means for forcing the mandrel into the opening into a position substantially coaxial with said common axis for bending the sheet about the lower portion of the mandrel, and means for swinging the racks and leaves upwardly about said common axis for rolling the end of the sheet about the upper portion of the mandrel.

4. The pipe forming machine according to claim 3 wherein each set of racks comprises a plurality secured to different segmental raclrs, said leaves being spaced apart to provide a mandrel opening between them, means supporting said segmental racks for movement about a common axis, a mandrel movable between the leaves into and out of the mandrel opening and in its outer position permitting a sheet to be placed on the leaves beneath the mandrel, means for forcing the mandrel into the opening for bending the sheet about the lower portion of the mandrel, and means for swinging the racks and leaves independently upwardly about said common axis for rolling the ends of the sheet about the upper portion of the mandrel and moving at least one of said leaves over the seam of the tubular work on the mandrel and onto the opposed sheet end.

8. A pipe forming machine comprising, in combination, a pair of longitudinally elongated leaves secured to diiferent segmental racks, said leaves being spaced apart to provide a mandrel opening between them, forming rollers mounted on the inner edges of said leaves, means supporting said segmental racks for movement about a common axis, a mandrel movable between the leaves into and out of the mandrel opening and in its outer position permitting a sheet to be placed on said leaves beneath the mandrel, means for forcing the mandrel into the opening into a position substantially coaxial with said common axis for bending the sheet about the lower portion of the mandrel, means for swinging the racks and leaves upwardly about said common axis for moving the forming rollers about the mandrel and rolling the ends of the sheet about the upper portion of the mandrel, and auxiliary rollers arranged to move about the lower portion of the mandrel simultaneously with said forming rollers for perfecting the bending of the portion of the sheet bent about the lower portion of the mandrel.

9. The pipe forming machine according to claim 8 wherein the segmental racks are arcuate and provided with arcuate trackways associated with supporting rollers, and the auxiliary rollers are journalled on said arcuate segmental racks.

10. A pipe forming machine comprising, in combination, a pair of longitudinally elongated forming members spaced apart to provide a mandrel opening between them, support and actuating means for said forming members arranged to swing said members about a common axis, an expansible, elongated mandrel movable between the forming members into and out of the opening and in its outer position permitting a sheet to be placed on the forming members beneath the mandrel, and means for forcing the mandrel into the opening for bending the sheet about the lower portion of the mandrel, said mandrel having a plurality of peripheral surface members adjustably supported from the inside of the mandrel for radial movement to permit adjustment of the mandrel diameter.

11. The pipe forming machine according to claim 10 wherein the mandrel comprises a longiill tudinal supporting axle connected to said means for moving the mandrel into and out of the opening, a slidable axle parallel to said supporting axle, a plurality of pivoted mandrel-expanding arms spaced along the length of the mandrel between said reciprocable axle and said peripheral surface members for changing the mandrel diameter as said slidable axle is moved with respect to the supporting axle, and means for position-- ing the said peripheral members .with respect to the supporting axle.

12. In combination with the pipe forming machine according to claim 11, a motor on said supporting axle connected to said slidable axle for moving the latter axle relatively to the supporting axle to selectively expand or collapse the mandrel.

13. The pipe forming machine according to claim 10 wherein the peripheral surface members of the mandrel are longitudinal, parallel sector bars having substantial depth radially with respect to the mandrel to afiord rigidity against radially inward flexure and spaced peripherally about the mandrel to permit free radial movement thereof, a longitudinally reciprocable axle within the mandrel, and a plurality of generally radial arms for each sector bar connected to said axle for moving said sector bars radially.

14. As a subcombination, an expansible, elongated cylindrical mandrel for a pipe forming machine comprising, in combination, a pair of parallel, relatively longitudinally slidable axles, a plurality of longitudinal, parallel sector bars at the periphery of the mandrel extending substantially throughout the length thereof, said bars having substantial depth radially with respect to the mandrel to afford rigiditiy against radially inward flexure and disposed to permit free radial movement thereof, a plurality of longitudinally inclined mandrel-expanding arms pivotally connected at their inner ends to one of said axles and at their outer ends to said sector bars for expanding said mandrel by urging said sector bars radially outwardly in compression, means acting independently of said mandrel-expanding arms for positioning said sector bars longitudinally with respect to the other of said axles, and means for moving said axles relatively to each other.

15. The mandrel according to claim 14 wherein the means for positioning the sector bars longitudinally with respect to the said other axle comprises a second plurality of mandrel-expanding arms pivotally connected at their inner ends to said other axle and at their outer ends to said sector bars and inclined longitudinally in a direction opposed to the first mentioned mandrelexpanding arms for opposing the longitudinal stress thereof.

16. As a subcombination, a mandrel for a pipe forming machine comprising, in combination, a supporting axle, a plurality of longitudinal sectors at the periphery thereof made of a ferrous metal, and a welding backing strip of a metal not readily weldable to steel, secured to the outer face of at least one of said sectors.

17. A pipe forming machine comprising, in combination, a pair of longitudinally elongated leaves secured to different segmental racks, said leaves being spaced apart to provide a mandrel opening between them, said leaves being laterally adjustable on said racks for changing the width of said mandrel opening, means supporting said segmental racks for movement about a common axis, a mandrel movable between the leaves into and out of the mandrel opening and in its outer position permitting a sheet to be placed on the leaves beneath the mandrel, means for forcing the mandrel into the opening for bending the sheet about the lower portion of the mandrel, and means for swinging the racks and leaves upwardly about said common axis for rolling the ends of the sheet about the upper portion of the mandrel.

18. The pipe forming machine according to claim 17 wherein the leaves are provided with transverse'rack gears,- and the machine is provided with adjusting pinions meshing with said gears for moving the leaves laterally to adjust the width of the mandrel opening.

19. In combination with the pipe forming machine according to claim 17, rollers adjustably mounted on said segmental-racks beneath said leaves, said rollers being adjustable toward or away from said common axis and being adapted for perfecting the bending of the portion of the sheet .bent about'the'lower portion of the mandrel.

20. A pipe forming machine comprising, in combination, a pair of longitudinally elongated leaves secured to different segmental racks, said leaves being'spaced apart to provide a mandrel opening between them and being laterally adjustable on said racks for movement about a common axis, a. mandrel having a plurality of peripheral surface members adjustable for changing the diameter of the mandrel, said mandrel being movable between the leaves into and out of the mandrel opening and in. its outer position permitting a sheet to be placed on the leaves beneath the mandrel, means for forcing the mandrel into the opening for bending the sheet about the lower portion of the mandrel, and means for rolling the ends of the sheet about the upper portion of the mandrel. f l

21. In combination with the pipe forming machine according to claim 20, a longitudinally reciprocable ejecting bar mounted for adjustment towards or away from said common axis, and means on said bar, for engaging the tubular work on said mandrel.

22. A pipe forming machine comprising, in combination, a plurality of transverse frames having upstanding" s'ide"portions and recessed central portions forming a space for movement of a mandrel, a pluralityof dollies on said frames, a plurality of transverse arcuate segmental racks supported by said dollies, a pair of longitudinally elongated leaves secured to different sets of said racks, said leaves being spaced apart to provide amandrel opening between them, a mandrel movable between the leaves into and out of the mandrel opening and in its outer position permitting a sheet to be placed on the leaves beneath the mandrel, means for forcing the mandrel into the mandrel'opening for bending the sheet about the lower .portion of the mandrel, means for swinging the racks and leaves upwardly about the mandrel for rolling the ends of the sheet about the upper portion of the mandrel, and means for ejecting the tubular work on the mandrel while said mandrel is within said mandrel opening.

a 23. The pipe forming machine according to claim 22 wherein the means for ejecting the tubular work comprises a longitudinal ejecting bar reciprocally mounted below said leaves so as to be contiguous to the part of said sheet bent about the lower portion of the mandrel when the mandrel is forced into the opening and engaging means on said bar for engaging a portion of the tubular work.

, 24. A pipe forming machine comprising, in combination, a pair of longitudinally elongated forming members spaced apart to provide a mandrel opening between them, support and actuating means for said forming members arranged to swing said members about a common axis, said support and actuating means being open at the discharge end of the machine, a mandrel movable between the forming members into and out of the mandrel opening and in its outer position permitting a sheet to be placed on the forming members beneath the mandrel, means for forcing the mandrel into the opening into a position substantially coaxial with said common axis for bending the sheet about the lower portion of the mandrel, and ejection means having an engaging portion thereof disposed beneath said forming members in alignment with a portion of said sheet bent about the lower portion of the mandrel when the mandrel is forced into the opening and beyond the end of the sheet away from the said discharge end, said ejecting means being longitudinally movable toward said discharge end.

25. A pipe forming machine comprising, in combination, a pair of longitudinally elongated forming members spaced apart to provide a mandrel opening between them, support and actuating means for said forming members arranged to swing said members about a common axis, said support and actuating means being open at the discharge end of the machine, a mandrel having a supporting axle movable between the forming members into and out of the mandrel opening and in its outer position permitting a sheet to be placed on the forming members beneath the mandrel, means for forcing the mandrel into the opening into a position substantially coaxial with said common axis for bending the sheet about the lower portion of the mandrel, said means comprising a vertically movable rod at the discharge end supported beneath the mandrel having a por tion thereof engag'e'able with said supporting axle, and locking means for detachably connecting said engaging portion and axle, said rod being retractible below the bottom of the mandrel when said mandrel is within the said mandrel opening.

26. A pipe forming machine comprising, in combination, a supporting structure having a transverse frame at the discharge end thereof with upstanding side portions and a recessed central portion forming a space for movement of tubular work, a pair of longitudinally elongated leaves beneath the mandrel, means for forcing the mandrel into the opening into a position substantially coaxial with said common axis for bending the sheet about the lower portion of the mandrel, means for swinging the racks and leaves upwardly about said common axis for rolling the ends of the sheet about the upper portion of the mandrel, means for ejecting the tubular work on the mandrel while the mandrel is within said mandrel opening, and support means beneath the mandrel forming a saddle for engaging the mandrel and affording lateral support thereto when the tubular work on the mandrel is removed therefrom.

27. The pipe forming machine according to claim 26 wherein the support means comprisesvertically movable supports arranged on both" sides of the vertical center plane of the mandrel;

28. The pipe forming machine according to claim 26 wherein the support means comprises a plurality of rollers on each side of the vertical center plane of the mandrel, said rollers being vertically movable and provided with means for moving said rollers successively upwardly into engagement with the mandrel as the tubular work is removed from the 'mandreL- 29. The pipe forming machine according to claim 26 wherein the means for ejecting the work and the support means comprises a longitudinal ejecting bar reciprocally mounted beneath the mandrel at a'height to be engaged by the tubular work when the mandrel is forced downward into said mandrel opening; an upward projection on said ejecting bar for engaging the end of the tubular work, supporting and driving pinions for said ejecting bar, at least one'supporting roller on each side of said ejecting bar near said discharge end and vertically movable with respect able for changing the width of said mandrelopeming to receive a mandrel of any size, and the means for ejecting the Work comprises a longitudinal ejecting bar reciprocally mounted beneath the mandrel, a vertical adjustable support forsaid ejecting bar, and the support means for the mandrel comprises mandrel engaging means located on both sides of said ejecting bar and vertically adjustable with said support for the ejecting bar, said engaging means being vertically movable with respect to said ejecting bar for engaging a mandrel of any diameter.

32. A pipe forming machine comprising, in combination, a plurality of transverse frames arranged in a roW having upstanding side portions and recessed central portions forming a space for movement of a mandrel, one end of said row being near the'discharge end of the'machine, a

plurality of dollies onsaid frames, a plurality of transverse arcuate segmental racks supported by said dollies, a pair of longitudinally elongated leaves secured to different sets of said racks, said leaves being spaced apart to provide a mandrel opening between them, a mandrel movable be-- tween the leaves into and out of the mandrel opening and in its outer positionpermitting a sheet to be placed on the leaves'beneath the mandrel, operating members engaging the ends of the mandrel for raising the mandrel to said outer position and'for forcing the mandrel downwardly into the opening for bending the sheet about the lower portion of 'themandrel, means for. swinging the racks and leaves upwardly about tubular work to be removed from the mandrel while-the mandrel is within said mandrel open ing.

33. The pipe forming machine according to claim 32 wherein the operating member at said dischargeend is a vertically reciprocable operating rod supported beneath the mandrel and extending upwardly to the mandrel.

34. The pipe forming machine according to claim 32 wherein the mandrel is provided with a supporting axle and the operating member at the discharge end is vertically movable and is provided with a cradle engageable with said axle, said axle and cradle being provided with locking means for detachably connecting said cradle and axle.

35. The pipe forming machine according'to' claim 3 1 wherein the locking means is provided with a'motorconnected to actuate the locking means selectively-into locking and unlocking posi-tions, and remote control means for said motor.

36. As a subcombination, a vertically adjustable ejecting and supporting structure for a mandrel operable in a pipe forming machine wherein one end of the mandrel is disengaged from its supporting means at the discharge end thereof for discharging the tubular work therefrom, comprising a longitudinal ejecting bar adapted toengage said man'drel'at the bottom thereof said ejecting bar having means for engaging the tubular work on said mandrel, thelower face of said bar forming a rack gear, supporting and driving pinions for said ejecting bar, frames for said pinions, a sup port on'each side of said ejecting bar near said discharge end vertically movable with respect to, said ejecting bar, and means for simultaneously REFERENCES CITED I The following references are of record in the file of, this patent:

UNITED STATES PATENTS Numberv Name 7 Date v 72,904 Rees Dec. 31, 1867 460,947 Clapp Oct. 31, 1891 5 3,255 Briggs July '1, 1896 622,139 Nall Mar. 28, 1899 1,027,555 MacFarlane May 28, 1912 1,029,024 Murray June 11, 1912 1,043,665 Boyd f Nov. 5, 19,12 11 4 ,862 Peoples June 29, 1915 1,3 3,55 Smith 1 Dec. 2, 1919 54L Horst .7- e ept 13, 192' 598, B r --.---.--9 an- 1 11.92 1 899,143 Erahin Feb. 23, 1933 1,943,360 Arnold Jan. 16, 193 2,121,901 Butty June 23, 1938 2,158,176 Dewey May 16, 1939 2,160,720, Butcher j May 30, 1939 2,192,484 Bryan Mar. 5, 1940 2,298,087 Stechbart Oct. 6, 1942 2,371,376 Bisbee Mar. 13,1945 2,373,163 Cailloux Apr. 1'0, 1945 f FOREIGN PATENTS Number Country Date 123,197 Great Britain Feb. 20, 1919 "784,321 France May 6, 1935

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