US3004582A - Multiple radius pipe bending machine - Google Patents

Description

Oct. 17, 1961 E. D. KEY

MULTIPLE RADIUS PIPE BENDING MACHINE 3 Sheets-Sheet 1 Filed March 18, 1959 INVEN TOR. JZ/za4ri J K y.

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Oct. 17, 1961 KEY 3,004,582

MULTIPLE RADIUS PIPE BENDING MACHINE Filed March 18, 1959 :5 Sheets-Sheet 2 IN VEN TOR.

E 5 Zia/47%)] A C 1961 E. D. KEY 3,00

MULTIPLE RADIUS PIPE BENDING MACHINE Filed March 18, 1959 3 Sheets-Sheet 3 67 INVENTOR. A96? 17 ziwdr D, Key

Mich.

Filed Mar. 13, 1959, Ser. No. 800,256 4- Claims. (Cl. 153-38) This invention relates to improvements in pipe bending machines and, more particularly, to improvements in bending machines suitable for cold bending pipe and conduit used for electric wiring installations. This application is a continuation-in-part of prior copending application Serial No. 733,377, filed May 6, 1958, for a Multiple Radius Pipe Bending Machine and now abandoned.

A primary object of this invention is to provide an extremely versatile pipe bending machine quickly and simply adaptable to accurately bend pipes of various diameters over a wide range of diiferent radii through angles ranging from zero to slightly over 90 degrees.

Another object of this invention is to provide a pipe bending machine which may be preset so that each bending cycle is automatically controlled providing precision bends that are smooth and consecutively identical.

Still another object of this invention is to provide a pipe bending machine which enables the simultaneous bending of several pipes, thereby substantially increasing efficiency and productive capacity.

A further object of this invention is to provide a pipe bending machine which enables the bent pipe to be easily extracted from the bending shoes.

Still another object of this invention is to provide a pipe bending machine which can quickly and simply be disassembled and reassembled for compact handling, thereby enhancing its portable characteristics and facilirating its storage when not in use.

Other objects and advantages of this invention will become apparent to those skilled in the art on reading the specification with reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view of the pipe bending machine embodying the invention and illustrating the relationship of its component parts to a pipe being bent;

FIGURE 2 is a perspective view of a small radius base ram and a series of ram extension dies for attachment thereto;

FIGURE 3 is a perspective view of a large radius base ram and a series of ram extension dies for attachment thereto;

FIGURE 4 is a vertical sectional view of a pipe bending shoe and adjacent ram extension dies as shown in FIGURE 1 and taken along line 4-4 thereof;

FIGURE 5 is a vertical sectional view through a twocavity segmented bending shoe connected to the outermost ram extension die and illustrating the relative positioning of the pipes in said cavities;

FIGURE 6 is a vertical sectional view through a fivecavity solid bending shoe and illustrating the relative positioning of the pipes in said cavities;

FIGURE 7 is a vertical sectional view of a five-cavity solid bending shoe illustrating an alternate method for attaching said bending shoe to the adjacent ram extension die;

FIGURE 8 is a fragmentary perspective view of FIG. 2 and illustrating the operation of the holding shoe and holding shoe return mechanism as they might appear when viewed from the position of arrow 8 near the left end of FIG. 1;

FIGURE 9 is a perspective view of the power unit and a schematic view of the automatic control circuit;

.FIGURE 10 is a fragmentary vertical sectional view of the ram extension dies and bending shoes supported by the roller carriage on the central track bar;

FIGURE 11 is a fragmentary vertical sectional view of the roller carriage shown in FIGURE 10 and taken along line 11-11 thereof;

FIGURE 12 is a fragmentary plan view of the bending machine illustrating a multiple bending operation;

FIGURE 13 is a vertical sectional view of the pipe end stop shown in FIGURE 12, taken along line 13-13 thereof and rotated clockwise;

FIGURE 14 is a view of an oifset bent pipe made with this machine;

FIGURE 15 is a view of a pipe bent into a figuration by this machine; and

FIGURE 16 is a view of a pipe bent in an angle of less than 90 degrees.

Referring now in detail to the drawings and as may be seen to best advantage in FIGURE 1, the automatic bending machine has been sub-divided for descriptive purposes into four basic operational elements; a power unit 1, a bending ram assemblage 2, a pipe holding fixture 3, and an automatic control mechanism for regulating the reciprocating travel of the bending ram assemblage. The relationship of the four operating elements as shown in FIGURE 1 enables the bending machine to be placed and operated on any comparatively flat surface of suitable size.

The power unit 1, as shown in FIGURES l and 9, comprises a conventional double-acting hydraulic piston and saddle concylinder assembly, a hydraulic pump of suitable capacity and pressure, a fluid reservoir, and suitable valves and passages to control the direction of piston and piston rod travel. The particular power unit illustrated has an outer housing 4 which is integral with the hydraulic cylinder and pump assemblies. Power units developing thrust forces upwards of tons and acting through a horizontal travel distance of about fifty inches are suitable for bending conduit sizes ordinarily encountered in electric wiring installations. The hydraulic pump is drivingly linked to electric motor 5 by means of flexible belt 6 acting over motor pulley 7 and pump pulley 8 as shown in FIGURE 9. An electric servo motor 9 connected to the shaft of lower control lever 10 enables rapid reversal of the direction of the piston rod 12 and is energized by means of the automatic control feature of this machine, which will be discussed in detail in a subsequent portion of this specification. Upper control lever 11 regulates the speed of travel of the hydraulically operated piston rod 12.

The bending ram assembly 2 is connected to the power unit 1 by means of a female adapter in the rear body of the base ram 13 which slides over and is removably splined or keyed to the end of the piston rod 12 and locked thereto by a set screw. The bending ram assembly 2 is comprised of a base ram 13, a series of arcuate fillers or ram extension dies 14, and a plurality of pipe bending shoes 15 removably attached to the arcuate face of the outermost ram extension die. FIGURE 2 is a perspective view of a small radius base ram 13 and a series of ram extension dies 14 adaptable for separate and successive removable attachment to the forward face of the base ram 13. The arcuate faces of the base ram 13 and ram extension dies 14 are concentric and ascribe circular arcs of approximately 90 which extend about 45 to each side of the longitudinal center axis of the ram and hydraulic piston rod 12. By the addition of one or more of the ram extension dies 14 to the face of the base ram 13 the radius of the ram can be varied in increments corresponding to the thickness of each extension die. In this manner the radius of the smallbase ram 13 shown in FIGURE 2 can be increased to any do- Pa jtented Oct. 17, 1961 3 sired radius by the successive attachment of the required number of ram extension dies 14. However, an additional base ram of a radius approximately intermediate to the range or radii required is preferred for large radius bends because of its greater rigidity in comparison to that of a small base ram equipped with a large number of ram extension dies. Accordingly, the large base ram 13 and extension dies 14 shown in FIGURE 3 have radii which sequentially follow the maximum extended radius of the small base ram shown in FIGURE 2. The innermost ramextension die is removably attached to the forward face of the base ram by means of two screws inserted at the back face of the base ram through holes 16 which are in alignment with tapped holes in the back side of the ram extension die. Successive attachment of additional ram extension dies to the innermost extension die is achieved by a pin and hinge type latching means, as shown in FIGURE 8. Hinge plates 17 are rigidly secured to each end of each ram extension die 14 by screws 18, said hinge plates having collars 20 which when placed in vertical alignment are removably secured together by the insertion of pin 19. The upper and lower sides of the ram extension dies are provided with grooves 21, as shown in FIGURE 4, having a vertical forward edge for engaging the latching levers 22 on the pipe bending shoes 15. The latching levers 22 are held in engagement with grooves 21 by means of spring clips 23, as may be best seen in FIGURE and are pivotally secured to the bending shoes by means of pivot pins 26. The pipe bending shoes are positioned along the arcuate forward face of the outermost ram extension die at spaced intervals as determined by the spacing of positioning holes 25 along the center of the face of the extension die 14 and cooperate with pins 24 which protrude from the center of the rear surface of the bending shoes 15. A sufficient number of pipe bending shoes are used to provide ample surface area to adequately support the pipe as it is bent during the forward thrust of the bending ram assembly, assuring smooth, concentric bends. Distortion of the circular cross section of the pipe or conduit being bent is minimized by the semi-circular cross section of the cavities in the face of the pipe bending shoes which radially support the pipe or conduit around approximately oneehalf its outer periphery.

The pipe bending shoes are either of a solid or segmented construction having one or more die cavities in their forward working face. A segmented. single-cavity bending shoe is shown in FIGURE 4; a segmented doublecavity bending shoe is shown in FIGURE 5; and a fivecavity solid bending shoe is illustrated in FIGURES 6 and 7. The unique segmented constructoin of the pipe bending shoes shown in FIGURES 4 and 5 is particularly applicable to pipes having diameters in excess of one and one-half inches, although it may also be applied to bending shoes for smaller diameter pipes. This segmented bending shoe feature enables the easy extraction and release of bent pipes from the bending shoes with a minimum of effort. Pipes of smaller diameters generally do not become as tightly wedged in the bending shoe cavities as do pipes of larger diameters and accordingly, solid bending shoes properly lubricated with a graphite base or other suitable lubricant provide satisfactory release of small diameter pipes. The segmented bending shoe, as shown in FIGURE 4, is comprised of a U-shaped outer casing 28 having upper and lower surfaces 29 and 30, respectively, that diverge outwardly toward the bending face of the shoe. Contained within the outer casing 28 are upper and lower bending shoe segments 31 and 32, respectively, which are loosely secured to the casing by screws 33 comprising a threaded portion 34 firmly attached to the bending shoe segments, an enlarged diameter shank portion 35, and a round head 36. The length of the unthreaded shank 35 exceeds the thickness of the outer bending shoe casing between shoulders 37 of recess holes 38 and the back inner surface of, the casing 28.

This arrangement enables each bending shoe segment to move forward independently out of the casing until heads 36 of screws 33 contact shoulders 37 of recess holes 33. Holes 39 in the casing through which shanks 35 of screws 33 pass are enlarged, thereby permitting the segments to move laterally as well as outwardly relative tothe casing but small enough to prevent head 36 of screw 33 from passing through or becoming wedged therein. During the forward bending stroke of the ram assembly the pipe 27 in the pipe'bending shoe cavity firmly seats bending shoe segments 31 and 32 in the bending shoe casing 28. On completion of the bend and retraction of the bending ram assembly the segments 31 and and 32.

are able to withdraw partially from the casing to the extent permitted by screw shanks 35, enabling the segments to diverge outwardly along inner surfaces 29 and 3% of the outer casing 28, opening the semi-circular cavity in the bending shoes and thereby releasing the bent pipe.

A two-cavity segmented bending shoe is shown in FEG'URE 5 which is similar in construction to the singlecavity shoe illustrated in FIGURE 4. The two-cavity segmented shoe construction. has upper and lower se ments 31 and 32, respectively, but requires, in addition, a middle segment which is also movably connected to the outer casing 28, enabling its partial outward movement relative to the casing. ltwill be appreciated by those skilled in the art that multiple-cavity segmented shoes of three or more cavities can be made based on the construction illustrated in FIGURE 5. It is preferred that the segmented inner bending shoe dies be split along the horizontal length of the semi-circular cavity therein in a plane passing through the approximate center of each cavity.

In the preferred embodiment of this machine, multiplecavity solid bending shoes are used for pipe diameters up to and including one and one-half inches. Solid bending shoes for three-quarter inch and one inch diameter pipe have five cavities, shoes for one and one-quarter inch pipe have four cavities, while three cavities are employed in solid bending shoes for one and one-half inch diameter pipes. Segmented bending shoes are used for bending pipes having diameters of one and one-half inches up to and including five inches.

' The drawing in FIGURE 7 represents an alternate method by which the bending shoes may be removably secured to the arcuate face of the outermost ram extension die. This alternate method utilizes cap screw 41 which is screwed into the back side of the pipe bending shoe 15 through a hole in the recessed rear center portion of the ram extension die. Two pins 24 projecting from the back surface of the bending shoe engage with a series of positioning holes 25 equally spaced along the face of the outermost ram extension die. It will be noted that this alternate method obviates the necessity of having grooves 21 in the upper and lower surfaces of the ram exte ion dies 14 and bending shoe latching levers 22. The pipe holding fixture is comprises of four radial link bars 4-2 which are pivotally connected to the power unit housing 4 by means of pins 43 and brackets 44 which are in vertical alignment. Each pair of radial link rods 42 extends outwardly in parallel spaced-apart relationship and disposed approximately 45 from the longitudinal center axis of the bending ram assembly 2 and hydraulic piston rod 12. Upper and lower cross link bars 45 are removably pinned to each pair of radial link bars i2. by means of pins 46 which also provide the pivot support for. pipe holding shoes 4-7. The radial link bars 42 and. cross link bars 45 have holes 43 equally spaced along the center line of their respective lengths, each of said holes having indicia associated'therewith such as a numbering or lettering sequence, whereby the appropriate hole may be selected for mounting pipe holding shoes 47 in accordance with the radius of the'bend to be made and diameter of the pipeto be bent. Pipe holding shoes 47 have a different set of cavities in each of their four faces corresponding to accesses.

5 the pipe holding cavities in the face of the pipe bending shoes 15. Two pair of pipe holding shoes 47 are required to provide the necessary sets of cavities to fit all the pipe sizes that can be bent in this machine. The pipe holding shoes 47 are detachably secured to pins 46 by means of set screw 49 recessed in one face of the pipe holding shoe, as may be best seen in FIGURE 8. The holding shoes are also provided with a return spring mechanism whereby on completion of each bending cycle the holding shoes are returned to the starting position enabling the insertion of the next length of pipe to be bent without requiring manual repositioning of each holding shoe. Included in the holding shoe return spring mechanism is a lever arm 50 adapted for sliding onto the upper end of a pin 46 and detachably secured thereto by set screw 51. A U-shaped clamp 52 slidably mounted on cross link bar 45 is linked to lever arm 50 by means of coil spring 53. A lug 54 extending downward from the outer periphery of the base of the lever arm 50 provides a stop mechanism so that the pipe holding shoe will stop in the position desired. The clamp 52 is positioned along the upper cross link bar 45 so that coil spring 53 is placed in tension while the lever arm 5'!) is held in a rotatably fixed position by lug 54 in contact with the side of the upper cross link bar 45. In operation, the holding shoe 47 is rotated so that the holding shoe face having cavities corresponding to the number and diameters of the pipes to be bent faces said cavities of said shoe positioned in contach with said pipes which initially extend perpendicular to the longitudinal central axis of the bending ram assembly. In that position the lever arm 50 with lug 54 in contact with the side of upper cross link bar 45 is locked to pin 46 by tightening Allen set screw 51 and holding shoe 47 is also locked to pin 46 by set screw 49. As the pipe is bent during the outward thrust of the bending ram assembly each of the holding shoes rotate inward toward the ram, causing pin 46 and lever arm 50 to rotate to the same degree, thereby increasing the tension in coil spring 53. Upon removal of the bent pipe from the holding shoe and bending shoe dies, the coil spring 53 acting through lever arm 56 rotatably retracts the bending shoes to the position Where lug 54 is again in contact with the upper cross link bar.

A central guide track 56 disposed below and parallel with the reciprocating path of travel of the bending ram assembly 2, as may be seen in FIGURES l and 10, in conjunction with a roller carriage 57 cooperating thereon provides a means for supporting and guiding the bending ram assembly during its reciprocating travel. Movable supporting spacers 58 elevate the central guide track 56 above the platform in order that the lower cross link bar 45 may be adjusted without interfering with the central guide track. The roller carriage '57, as shown in FIG- URES l and 11, is comprised of an inverted U-shaped channel body 59 having rollers 60 rotatably mounted on shaft 61 rigidly secured to opposing flanges 62 of the inverted U carriage body 59. The side flanges 62 of the roller carriage are spaced apart a distance slightly exceeding the width of the central guide track 56 and extend down slightly below the upper surface of said guide track, thereby cooperating intermittently with the side of said guide track stabilizing and guiding the carriage relative to the guide track which is secured by suitable means or anchors to the base platform. A projection or pin 63 extending from the front upper surface of the roller carriage 57 en ages with holes 6 in the lower surface of the ram extension dies 14 removably connecting the carriage to the bending ram assembly. The use of the roller carriage 57 is preferred for all bending operations, although in situations where only a few ram extension dies 14 are used the weight of the bending ram assembly can be adequately supported by the hydraulic piston rod 12. When large radius bends are being made requiring the use of a large number of ramextension dies 14, the weight of the bending ram assembly may cause unduly high stressesto be formed in the hydraulic piston rod and piston assembly without the supporting help of the roller carriage 57.

The automatic control mechanism for regulating the reciprocating travel of the bending ram assembly illustrated schematically in FIGURE 9 is comprised of a slide bar 65 having a graduated upper surface and is rigidly supported in a horizontal position parallel to the longitudinal center axis of the hydraulic piston rod 12 and bending ram assembly 2 by means of clamp 66 securely attached to the forward outer periphery of the hydraulic piston rod 12. Supported from bracket 67 extending outwardly from the power unit housing 4 are limit switches 68 and 69 which are actuated by cams 70 and 71 slidably mounted on slide bar 65. By the adjustment of cam 71 on slide bar 65 the forward travel of the bending ram assembly can be controlled by means of limit switch 69 normally in an open contact position, which energizes servo motor 9 when it becomes activated by cam 71. Upon being energized, electric servo motor 9 quickly rotates lower control lever 10 into the reverse position, whereby the bending ram is quickly reversed. As the bending ram assembly is retracted cam 70 mounted on slide bar 65 approaches limit switch 68 which is normally in a closed position but when activated by cam 7 0 opens, opening start relay contacts in starter box 74, thereby deenergizing electric pump motor 5 and stopping the ram. The rapid reversal and instantaneous withdrawal of the bending ram assembly provided by this machine is essential in order to assure accurate bends which can be consecutively duplicated. The automatic shut-off or stopping action of limit switch 68 enables the ram to be stopped in a position wherein the center pipe bending shoes are in transverse alignment with the pipe holding shoes 47, allowing sufficient room so that the next pipe or series of pipes to be bent can be inserted and held between the holding shoes and bending shoes preparatory to the next bending cycle.

It will be appreciated by those skilled in the art that alternate means may be employed to instantly reverse the forward thrust of the bending ram, such as an electric solenoid connected to a hydraulic slide valve slidable between forward, neutral, and reverse positions. The automatic control feature of this bending machine makes the machine particularly suitable for producing a large quantity of precision bent pipes which must be consecutively identical to each other. The extreme versatility of this machine is further illustrated in FIGURES 12-16. The fragmentary plan view of the pipe bending machine shown in FIGURE 12 illustrates the use of the bending machine for imparting multiple bends in a length of pipe, such as an offset, as shown in FIGURE 14. A pipe end stop 72 is generally employed to facilitate positioning the pipe lengthwise relative to the bending ram. The configuration of pipe end stop 72 may be of any general design enabling its removableattachment, as in FIG- U RE 13, to the upper cross link bar 45 by means of pins 73.

A typical bending operation of the machine will now be described to provide additional correlation between its operative parts. Assuming that a one-inch diameter pipe is to be bent into an offset, as shown in FIGURE 14, the first step is to attach the appropriate number of ram extension dies 14 to the base ram 13 in accordance with the radius bend desired, and then the selected pipe bending shoes having five one-inch cavities in theirface are removably mounted on the arcuate outer face of the outermost ram extension die. Pipe holding shoes 47 are positioned in holes 48 by means of pins 46 corresponding to the radius of the bend and diameter of the pipe to be bent. The holding shoe return spring mechanisms are adjusted to correctly position the holding shoe faces having five one-inch cavities in transverse alignment with each other. The next step entails the adjustment of cams 70 and 71 on slide bar 65 to set the reciprocating travel of the bending ram assembly so that, for example, a 45 bend is achieved. Pipe end stop 72 is then positioned u some that the 45 bends will occur along the appropriate point of the pipes length. The bending ram assembly is then moved through one complete cycle in order that it stops at the appropriate point for inserting the pipe. Five oneinch diameter pipes are then inserted between the holdng shoes and pipe bending shoes with their ends abutting pipe end stop '72. Lower control lever 16 is rotated into the forward position and electric pump motor is energized by a conventional start-stop push button switch which over-rides open limit switch 68 by manually holding the starter relay in closed position until the ram moves outward to a point beyond which cam '70 on slide bar 65 no longer is in contact with limit switch 63, which then closes, holding the starter relay in closed position until again activated by cam 70. A complete bending cyclethen ensues without requiring any further attention from the operator until the ram once again stops in the retracted position. The bent pipes are removed from the machine, turned end for end, and reinserted as before and as shown in FIGURE 12. Lever it? is again pulled forward by the operator and pump motor 5 energized, thereby causing the machine to undergo another automatic bending cycle. The five pipes bent in an ofiset configuration, as shown in FIGURE 14, are then removed from the machine preparatory to the insertion of five additional pipes to be subssquently bent.

In a similar manner, multiple bends, such as a saddle illustrated in FIGURE 15, can be accurately and quickly bent by this machine. Simpler bends, such as a 90 bend, or bends ranging from zero to slightly over 90, such as a kick as shown in FIGURE 16, also can be bent quickly and consecutively on this machine.

It will be understood that the invention herein described is not limited to the exact details of construction and operation of the automatic multiple radii pipe bending machine as shown in the drawings and disclosed in the specification, inasmuch as various modifications can be made by persons skilled in the art which are within the scope of the appended claims.

What is claimed is:

1. In a pipe bending machine, the combination comprising a frame, a double acting fluid actuated cylinder on said frame having a longitudinally reciprocable piston rod, a variable radius bending ram mounted on said rod and reciprocable thereby, said bending ram comprising a base ram having an arcuate forward surface and a series of arcuate tillers of progressively increasing radii detachably secured to said arcuate forward surface for varying the radius of said bending ram, and a plurality of pipe bending shoes arcuately disposed along the forward surface of the outermost of said arcuate fillers, each of said bending shoes comprising a casing having an aligning pin in'the rearward surface thereof for slidably engaging a corresponding aligning bore in the forward surface of the outermost of said arcuate fillers, a plurality of resiliently biased pivotally mounted latching levers on said casing for detachably engaging mounting grooves in the upper and lower surfaces of the outermost of said arcuate fillers, the forward surface of said casing formed to define a plurality of cavities of semi-circular cross-section for receiving and engaging piping of a corresponding diameter, said frame also having a pair ofradial-link bars pivotally connected thereto and extending outwardly to each side of said bending ram, a pair of cross-link bars extending transversely between said link bars and detachably secured thereto by a pivot pin slidably and rotatably disposed in aligned apertures through said radial and said cross-link bars, a pair of holding shoes disposed between said pairs of cross-link and radial-link bars and mounted on said pivot pins, each of said holding shoes including a holding face formed to define cavities of semi:

circular cross-section corresponding to'said cavities in said bending shoes, a lever detachably affixed to each of said pivot pins including stop means thereon to'limit the rotational'travel of'each'of said-holding-shoes in one direction to a start position in which said holding face is perpendicular to the reciprocable path of travel of said ram, resilient means connected to each of said levers audto one ofsaid link bars biasing said holding shoes toward said start position, guide means coacting with said bending ram disposed parallel to the reciprocable path of travel thereof, and presettable control means for controlling the forward and rearward travel of said bendmg ram.

2. In a pipe bending machine, the combination comprising a frame, a double acting fluid actuated cylinder on said frame having a longitudinally reciproca ble piston rod, a variable radius bending ram mounted on said rod and reciprocable thereby, said bending ram comprising a base ram having an arcuate forward surface and a series of arcust fillers of progressively increasing radii detachably secured to said arcuate forward surface for varying the radius of said bending ram, each of said arcuate fillers provided with a plurality of annular collars at each of the ends thereof alignable with corresponding annular collars on the ends of adjacent ones of said arcuate fillers for slidably receiving a securing pin for detachably securing said arcuate fillers together, and a plurality of pipe bending shoes arcuately disposed along the forward surface of the outermost of said arcuate fillers, each of said bending shoes comprising a casing having an aligning pin in the rearward surface thereof for slidably engaging a corresponding aligning bore in the forward surface of the outermost of said arcuate fillers, a plurality of resiliently biased pivotally mounted latching levers on said casing for detachably engaging mounting grooves in the upper and lower surfaces of the outermost of said arcuate fillers, the forward surface of said casing formed to define a plurality of cavities of semi-circular cross-section for receiving and engaging piping of a corresponding diameter, said frame also having a pair of radial-link bars pivotally connected thereto and extending outwardly toeach side of said bending ram, a pair of cross-link bars extending transversely between said link bars and detachably secured thereto by a pivot pin slidably and rotatably disposed in aligned apertures through said radial and said cross-link bars, a pair of holding shoes disposed between said pairs of cross-link and radial-link bars and mounted on said pivot pins, each of said holding shoes including a holding face formed to define cavities of semi-circular cross-section corresponding to said cavities in said bending shoes, a lever detachably atfixed to each of said pivot pins including stop means thereon to limit the rotational travel of each of said holding shoes in one direction to a start position in which said holding face is perpendicular to the reciprocable path of travel of said ram, resilient means connected to each of said levers and to one of said link bars biasing said holding shoes toward said start position, guide means coacting with'said bending ram disposed parallel to the reciprocable path of travel thereof, and presettable control means for controlling the forward and rearward travel of said bending ram.

3. In a pipe bending machine, the combination com prising a frame, a double acting fluid actuated cylinder on said frame having a longitudinally reciprocable piston rod, a variable radius bending ram mounted on said rod and reciprocable thereby, said bending ram comprising a base ram having an arcuate forward surface and a series of arcuate fillers of progressively increasing radii detachably secured to said arcuate forward surface for varying the radius of said bending ram, and a plurality of pipe bending shoes arcuately disposed along the forward surface ofthe outermost of said arcuate fillers, each of said bending shoes comprising an outer casing including a rearward wall and upper and lower diverging walls affixed thereto defining therewith a forwardly directed cavity, a segmented inner pipe bending die slida-bly disposed in said forwardly directed cavity and having aforward face defining at least one cavity of a semhcircular cross-section, said segmented inner die segmented along the length of each of said semi-circular cavities in a plane passing through the approximate center thereof, each of the segments of said segmented inner die being movably secured to said rearward wall enabling the restricted outward movement thereof from said forwardly directed cavity, an aligning pin on the outer surface of said rearward wall for slidably engaging a corresponding aligning bore in the forward surface of the outermost of said arcuate fillers, and securing means for detachably securing each of said bending shoes to said outermost arcuate filler, said frame also having a pair of radial-link bars pivotally connected thereto and extending outwardly to each side of said bending ram, a pair of cross-link bars extending transversely between said link bars and detachably secured thereto by a pivot pin slidably and rotatably disposed in aligned apertures through said radial and said cross-link bars, a pair of holding shoes disposed between said pairs of crosslink and radial-link bars and mounted on said pivot pins, each of said holding shoes including a plurality of holding faces formed to define cavities of semi-circular crosssection for receiving a variety of diiferent pipe sizes, a lever detachably affixed to each of said pivot pins including stop means thereon to limit the rotational travel of each of said holding shoes in one direction to a start position in which an appropriate one of said holding faces is perpendicular to the reciprocable path of travel of said ram, and resilient means connected to each of said levers and to one of said link bars biasing said holding shoes toward said start position.

4. In a pipe bending machine, the combination comprising a frame, a double acting fluid actuated cylinder on said frame having a longitudinally reciprocable piston rod, a variable radiusbending ram mounted on said rod and reciprocable thereby, said bending ram comprising a base ram having an arcuate forward surface and a series of arcuate fillers of progressively increasing radii detachably secured to said arcuate forward surface for varying the radius of said bending ram, and a plurality of pipe bending shoes arcuately disposed along the forward surface of the outermost of said arcuate fillers, each of said bending shoes comprising an outer casing including a rearward wall and upper and lower diverging walls afiixed thereto defining therewith a forwardly directed cavity, a segmented inner pipe bending die slidably disposed in said forwardly directed cavity and having a forward face defining at least one cavity of a semi-circular crosssection, said segmented inner die segmented along the length of each of said semi-circular cavities in a plane passing through the approximate center thereof, each of the segments of said segmented inner die being movably secured to said rearward wall enabling the restricted outward movement thereof from said forwardly directed cavity, an aligning pin on the outer surface of said rearward wall for slidably engaging a corresponding bore in the forward surface of the outermost of said arcuate fillers, and securing means for detachably securing each of said bending shoes to said outermost arcuate filler, said frame also having a pair of radial-link bars pivotally connected thereto and extending outwardly to each side of said bending ram, a pair of cross-link bars extending transversely between said link bars and detachably secured thereto by a pivot pin slidably and rotatably disposed in aligned apertures through said radial and said cross-link bars, a pair of holding shoes disposed between said pairs of cross-link and radial-link bars and mounted on said pivot pins, each of said holding shoes including a plurality of holding faces formed to define cavities of semi-circular cross-section for receiving a variety of different pipe sizes, a lever detachably affixed to each of said pivot pins including stop means thereon to limit the rotational travel of each of said holding shoes in one direction to a start position in which an appropriate one of said holding faces is perpendicular to the reciprocable path of travel of said ram, resilient means connected to each of said levers and to one of said link bars biasing said holding shoes toward said start position, a central guide track disposed below and parallel to the reciprocating path of travel of said bending ram, a roller carriage contacting said guide track and removably attached to said bending ram for supporting and guiding said bending ram during the reciprocable travel thereof, and presettable control means for automatically controlling the forward and rearward travel of said bending ram.

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