Pipe Bending Machine
A pipe bending machine has a beam mounted in see-saw pivotal relation on a fulcrum and spaced apart cradles support the pipe. An actuator initially drives the second cradle and the beam apart to pivot the pipe about the first cradle until the pipe is in contact with the die and thereafter drives the beam away from the second cradle to bend the pipe against the die. The mechanical advantage of the levered operation requires only a single actuator motion to bend the pipe. An external mandrel allows the pipe to be incrementally fed through the bending machine and secures the pipe against cross-sectional distortion during the bending process.
This application claims priority U.S. Provisional Application No. 61/328,560, filed Apr. 27, 2010.
BACKGROUND OF THE INVENTIONThis invention relates generally to pipe bending and more particularly concerns both the efficiency of pipe bending equipment and the quality of the bends which are created.
Throughout the world each year, thousands of miles of large diameter pipe are assembled and laid underground for transporting oil, natural gas, refined petroleum products, and other fluids. One prior art bending machine has a frame; a caterpillar assembly or other system for moving the portable bending machine from location to location; a bending die which is mounted in fixed position in an upper portion of the frame; a stiffback trough and a pin-up shoe. To begin the pipe bending operation, a segment of pipe is inserted into the pipe bending machine from the rear end thereof such that the pipe segment extends over the pin-up shoe and onto the stiffback trough. Rollers are provided at the forward end of the stiffback trough to facilitate the insertion, relocation, and removal of the pipe segment. An axial positioning mechanism is used to move the pipe segment along the stiffback trough until the portion of the pipe wherein the bend is to be made is properly positioned beneath the bending die. The bending die has a curved bending surface which contacts the top of the pipe and is shaped to impart a desired bend radius to the pipe segment during the bending operation. The stiffback trough is connected to the frame by a pair of outboard hydraulic bending cylinders which are secured between the front portion of the frame and the front portion of the stiffback trough. In addition, four inboard hydraulic cylinders are connected between the upper portion of the frame and the rear portion of the stiffback trough. The pin-up shoe is connected to the rear portion of the frame for supporting the rear portion of the pipe segment during the bending operation. The vertical position of the pin-up shoe can be adjusted by sliding a pin-up wedge beneath the shoe using a hydraulic pin-up cylinder. After the pipe segment has been inserted and axially positioned in the bending machine, the stiffback trough is raised vertically to bring the upper surface of the pipe segment into contact with the bending die. This procedure, referred to as “leveling,” is accomplished using the outboard and inboard bending cylinders. Next, the pin-up cylinder is extended to move the pin-up wedge against the pin-up shoe so that the shoe contacts the lower surface of the pipe segment. With the pipe shoe in contacting position, the outboard cylinder is then operated to provide a lifting force to the outer end of the stiffback trough such that the stiffback trough imparts a bending moment to the pipe segment sufficient to cause the pipe segment to bend upwardly against the curved bending surface of the bending die. At the same time that the outboard cylinders are operated to apply the necessary bending moment to the pipe segment. The in board cylinders of the prior art machine must also be operated to raise the rearward end of the stiffback trough in order to clamp the pipe segment against the bending die.
Heretofore, when bending a pipe segment using a bending machine of the type illustrated in
Unfortunately, the need to extend the stiffback trough beneath the bending die also necessitates that the inboard leveling cylinders be positioned behind the pipe bending point. Thus, the inboard cylinders in effect create a competing bending moment which further increases the required size and output of the outboard cylinders and also increases the strength and weight requirements of the machine frame and other components.
Also, when using a prior art internal bending mandrel, it has been necessary that (a) the stiffback trough have an upwardly curved interior surface having a size and shape corresponding the bottom half of the pipe and (b) the bending die have a downwardly curved interior which similarly corresponds to the size and shape of the upper half of the pipe. Thus, together, the stiffback trough and the bending die substantially surround the pipe during the bending operation except for a small longitudinal gap between the two on each side of the pipe near the pipe's horizontal center plane. The use of stiffback trough and bending die structures of this type which substantially surround the pipe, as well as the need to apply a leveling and clamping force to the stiffback trough at location behind the bend point, have inherently been required heretofore when using an internal bending mandrel to further ensure that no distortion, wrinkling, buckling, and egging occurs.
Thus, a need exists for a more economical, efficient, and reliable system and method for bending pipe. Such system will preferably (a) eliminate the need for inserting a bending mandrel into the interior of the pipe to protect the pipe from distortion, wrinkling, buckling, or egging during the bending operation, (b) eliminate the need for an inboard leveling and clamping cylinder arrangement which exerts an undesirable competing bending moment force against the stiffback trough, and (c) reduce the strength and weight requirements of the bending machine frame and other components, (d) significantly reduce the complexity and cost of the bending system and process, (e) provide increased speed, efficiency, and precision, (f) increase the life span of the equipment and system, (g) provide reconfigured load points which allow more efficient use of hydraulic energy, (h) provide an increased mechanical advantage to existing hydraulic components without increasing the power demand, and (i) provide better stress distribution to the machine frame.
Pipe bending requires application to the pipe of forces of various magnitudes and in various directions. The force magnitudes required generally increase in relation to the diameters and thicknesses of the pipes being bent. The strength of the supporting structure and the number, type and size of actuating components that are presently deemed necessary to manipulate and bend the pipe result in the design of heavy, immobile, slow-operating, expensive machines. in To handle in multiple directions and involving a multitude of force exerting actuators. In bending steel pipe, In the use of known pipe bending equipment, as a pipe is loaded into the bending machine, the pipe simultaneously internally receives a mandrel. which is aligned in the machine on the path of pipe insertion. The mandrel is intended to prevent the occurrence of out-of-round deviation, or buckling, of the pipe as bending forces are applied to the pipe during the bending process.
It is, therefore, among the objects of this invention to provide a pipe bending machine and method which limit the likelihood of distortion, wrinkling, buckling, and egging of the pipe, eliminate the need for an internal bending mandrel, simplify the bending operation, provide improved bending protection, efficiency, speed, and precision, increase the life span of the bending equipment, eliminate the application of wasteful competing bending moments, provide better stress distribution on the bending machine frame, reduced power demand, apply energy more efficiently, increase mechanical advantage and reduce the strength and weight requirements of the machine frame and other components.
SUMMARY OF THE INVENTIONIn accordance with the invention, a pipe bending machine is provided which reduces the number and size of actuators and supporting structure needed to bend a pipe and/or which retains the shape of the pipe by acting against and holding the exterior of the pipe during the bending operation.
To retain the shape of the pipe, a mandrel is provided which has a plurality of pairs of members, each pair having an inner contour shaped to mate against the exterior wall of the pipe to substantially maintain the cross-sectional shape of the pipe during bending. Each pair has an inner contour shaped to urge the members to mate against the exterior wall of the pipe as the pipe is impelled against the urging inner contour. Preferably, each pair is independently pivotally mounted so as to be at rest in response to gravity in a sufficiently open condition to receive a pipe and to close on and concentrically mate against the exterior wall of the pipe in response to the pipe imposing force against the internal contour.
To reduce the number and size of supporting actuators and structure, the machine for bending the has a beam mounted in see-saw pivotal relation on a fulcrum. First and second spaced apart cradles are aligned to support the pipe. The first cradle is mounted on the beam on one side of the fulcrum and the second cradle is mounted on an actuator mounted on the beam on an opposite side of the fulcrum. A die is positioned between the cradles. The actuator initially drives the second cradle and the beam apart to pivot the pipe about the first cradle until the pipe is in contact with the die and thereafter drives the second cradle away from the beam to bend the pipe against the die. Thus, a single actuator motion is all that is required to bend the pipe.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
While the invention will be described in connection with preferred embodiments thereof, it will be understood that it is not intended to limit the invention to those embodiments or to the details of the construction or arrangement of parts illustrated in the accompanying drawings.
The Lever
Turning first to
As seen in
Looking at
The Mandrel
Turning to
Retainers 53 and spacers 55 are alternately mounted on the outer perimeters of the upstream portions of the rods 57 by sliding inwardly facing notches on their opposite ends onto the rods 57. The cleats 67 and 69 are mounted on the inner perimeters of the rods 57 by sliding outwardly facing notches 75 on their opposite ends onto the rods 57. The inner perimeters of the rods 57 and the outer perimeters of the notches 75 in the cleats 67 and 69 are complementarily arcuate to facilitate pivoting of the cleats 67 and 69 on the rods 57.
As shown, the cleats 67 and 69 have thick lower portions with thinner upper tongue portions 77. The retainers 53 have the same thickness as the tongues 77 and the spacers 55 have a thickness that fills the gap created between the tongues 77 of abutting pairs of cleats 67 and 69. The result is that the retainers 53, which are centered on the pairs of cleats 67 and 69, and the spacers 55, each of which are shared by face-to-face cleats 67 and 69 of sequential pairs, form an assembly which resists twisting and wobbling during the bending process.
Looking at
As seen in
Continuing to look at
Returning to
The Bending Machine
A preferred embodiment of a bending machine 100 incorporating the principles of the lever assembly 10 and mandrel 50 above described is illustrated in
Pipe P feeds through the bending machine 100 in a downstream direction 119. A first pipe cradle 121 is mounted near the downstream end of the beam 111 on an axle or other pivot member 123 which allows the downstream cradle 121 to rotate so that the pipe P will remain fully seated in the cradle 121 throughout the bending process. A second cradle 125 is mounted on a scissor 127 with upper and lower arms 129 and 131 extending from intermediate joints 133. The scissor 127 is driven by a screw drive 135 powered by a motor 137. The upstream cradle 125 is connected to the scissor upper arms 129 by an axle or other pivot member 139 which allows the upstream cradle 125 to rotate so that the pipe P will also be fully seated in the upstream cradle 125 throughout the bending process. The bottom joint 141 of the scissor 127 is mounted on the beam 111. As shown, the bottom joint 141 preferably consists of two spaced apart joints 141 so as to provide greater control and efficiency in the operation of the scissor 127. The beam fulcrum 113 divides the beam 111 into downstream and upstream portions, as shown in such a proportion as to apply an approximately 2:1 mechanical advantage from the screw drive 135 to the pipe P at the downstream cradle 121 in comparison to the upstream cradle 125. The upstream end of the beam 111 has a supporting frame assembly 143 mounted to the beam 111. The frame assembly 143 supports the beam 111 on the ground during the bending operation. The beam 111 also supports downstream and upstream rollers 145 and 147;respectively, to facilitate loading Of the pipe P into the machine 100 and onto the cradles 121 and 125.
A radial control arm 151 is connected at its downstream end on an axle or other pivot member 153 to the beam 111 at a point upstream of the fulcrum 113 and below the downstream roller 145. As seen in
Returning to
The preferred embodiment of the die assembly 200 is illustrated in greater detail in
A preferred embodiment of the external mandrel 250 associated with the die 200 is illustrated in greater detail in
Looking at
Along the upstream portion of the spine 259, each vertebra 251 has an associated pair of jaws 267 and 269, one jaw 267 of each pair being mounted on one of the rods 257 and the other jaw 269 of each pair being mounted on the other of the rods 257. The jaws 267 and 269 are independently pivotally mounted so that each pair of jaws 267 and 269 is freely at rest in response to gravity in a sufficiently open condition to receive the pipe P. Each pair of jaws 267 and 269 has an internal contour 271 or 273 shaped at least in part to cause the pair of jaws 267 and 269 to close on and concentrically mate against an exterior wall of the pipe P in response to the pipe P imposing force against the internal contour 271 or 273 so that the mandrel 250 substantially maintains the cross-sectional shape of the pipe P during bending. As best seen in
Looking at
Operation
As seen in
In the operation of the machine 100, after the pipe P has been loaded horizontally downstream onto the rollers 145 and 147 of the lever assembly 110 of the machine 100, the screw drive 135 initially causes the scissor 127 to expand vertically, causing the distance between the upstream cradle 125 and the beam 111 to increase and thereby elevate the upstream cradle 125 to pick up the pipe P. At the same time, the downstream cradle 121, which is mounted on the downstream side of the fulcrum 113, is elevated by the beam 111 to pick up the pipe P. As the screw drive 135 continues its vertical expansion, the pipe P continues to be elevated by both cradles 121 and 125 while the pipe P pivots on the downstream cradle 121, changing its angular relation to the beam 111. Eventually, the pipe P makes contact with the die assembly 200, at which time the pipe P is pinned between the downstream cradle 121 and the downstream portion of the die assembly 200. At this time, the downstream portion of the pipe P has been inserted into and mated with the downstream portion of the external mandrel 250. However, the force exerted by the screw drive 135 on the moving beam 111 was selected to be less than the force required to bend the pipe P. But, as the screw drive 135 continues to drive between the upstream cradle 125 and the beam 111, the beam has been immobilized by the fixed positions of the downstream cradle 121 and the die assembly 200 and can no longer pivot on the fulcrum 113. Therefore, the force of the screw drive 135 multiplied by the mechanical advantage of the lever assembly 110 will be applied to the upstream portion of the pipe P, bending the portion of the pipe P in the upstream portion of the mandrel 250 to be sequentially inserted into and mated with the jaws 267 and 269 of the upstream portion of the external mandrel 250 and then bent into conformance with the die assembly 200. While the mechanical advantage shown is approximately 2:1, other mechanical advantage ratios can be used provided they result in exertion of pipe bending force only after the pipe P has contacted the die assembly 200 and is mated in the downstream jaws 267 and 269 of the external mandrel 250.
Turning to
As the bending force is applied to the pipe P, the force applied may tend to urge the upstream cradle 125 to shift on the pipe P. The radial control arm 151 provides counter-acting force on the upstream cradle 125 to offset this tendency. The pipe P is then released by termination of the applied force and the weight of the pipe P assists gravity in causing the jaws 267 and 269 to rotate back to the gravity-maintained at-rest “opened” condition. The pipe P is then advanced for the next incremental distance and the process repeated until the desired length pipe P is bent to the radius established by the die 200.
Thus, it is apparent that there has been provided, in accordance with the invention, an on-board external mandrel that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.
Claims
1. For use in a machine for bending pipe, a mandrel comprising a plurality of vertebra, each said vertebra having a pair of jaws, each jaw of said pair being independently pivotally mounted whereby said pair of jaws is at rest in response to gravity in a sufficiently open condition to receive a pipe therein, each said pair of jaws having an internal contour shaped at least in part to cause said pair of jaws to close on and mate against an exterior wall of the pipe in response to the pipe imposing force against said internal contour whereby the mandrel substantially maintains a cross-sectional shape of the pipe during bending thereof.
2. A mandrel according to claim 1, said plurality of vertebra forming a spinal column which, with said vertebrae mated against the pipe in said closed condition, is free to conform to a bending arc of the pipe.
3. For use in a machine for bending pipe, a mandrel comprising a plurality of vertebra, each said vertebra having a pair of jaws, each jaw of said pair being independently pivotally mounted whereby each said pair of jaws is at rest in response to gravity in a sufficiently open condition to transversely receive a pipe being elevated into said pair of jaws, each said pair of jaws having an upper internal contour shaped to cause said pair of jaws to rotate into a closed condition on the pipe in response to the pipe being elevated against said upper internal contour and to bear against an exterior wall of the pipe in said closed condition to substantially maintain a cross-sectional shape of the pipe during bending thereof.
4. A mandrel according to claim 3, said plurality of vertebra forming a spinal column which, with said vertebrae bearing against the pipe in said closed condition, is free to conform to a bending arc of the pipe.
5. For use in bending pipe, a machine comprising:
- a frame;
- a plurality of vertebra mounted on said frame to form a spinal column which is free to conform to a bending arc of the pipe; and
- a lower trough movably mounted in said frame to bend the pipe against said spinal column;
- each said vertebra having a pair of jaws, each jaw of said pair being independently pivotally mounted whereby said pair of jaws is at rest in response to gravity in a sufficiently open condition to transversely receive the pipe as the pipe is elevated into said pair of jaws, each said pair of jaws having an upper internal contour shaped to cause said pair of jaws to rotate into a closed condition on the pipe in response to the pipe being elevated against said upper internal contour and each said pair of jaws having an internal contour shaped to bear against an exterior wall of the pipe in said closed condition to substantially maintain a cross-sectional shape of the pipe during bending thereof.
6. For use in bending pipe, a mandrel comprising:
- a plurality of pairs of members;
- each said pair having an inner contour shaped to mate against an exterior wall of the pipe to substantially maintain a cross-sectional shape of the pipe during bending thereof; and
- each said pair having an inner contour shaped to urge said members to mate against the exterior wall of the pipe as the pipe is impelled against said urging inner contour.
7. A mandrel according to claim 6, said members of each said pair having their respective said mating surfaces diametrically opposed when mated against the pipe.
8. For use in bending pipe, a machine comprising:
- a frame;
- an upper die mounted in said frame;
- a lower trough movably mounted in said frame to bend the pipe against a surface of said die;
- a plurality of pairs of members mounted on said frame to freely conform to a bending arc of the pipe, each said pair having an inner contour shaped to mate against an exterior wall of the pipe to substantially maintain a cross-sectional shape of the pipe during operation of said trough to bend the pipe against said die and having an inner contour shaped to urge said members to mate against the exterior wall of the pipe as the pipe is impelled against said urging inner contour.
9. A machine according to claim 8, said members of each said pair having their respective said mating surfaces diametrically opposed when mated against the pipe.
10. A machine according to claim 9, said diametrically opposed surfaces being on opposite sides of a bending plane of the pipe.
11. A machine according to claim 10, said bending plane being a vertical plane and said opposing pairs of members being aligned for substantially horizontal mating and releasing motion.
12. A method for bending pipe comprising the steps of:
- urging the pipe against a bending die; and
- simultaneously girthing an exterior wall of the pipe to substantially maintain a cross-sectional shape of the pipe during bending.
13. A method according to claim 12, said step of girthing comprising mating opposing members against opposite sides of the pipe.
14. A method according to claim 13, said opposing members being on opposite sides of a pipe bending plane.
15. A machine for bending pipe comprising:
- a beam mounted in see-saw pivotal relation on a fulcrum;
- first and second spaced apart cradles aligned to support the pipe, said first cradle being mounted on said beam on one side of said fulcrum and said second cradle being mounted on an actuator mounted on said beam on an opposite side of said fulcrum; and
- a die positioned between said cradles;
- said actuator initially driving said second cradle and said beam apart to pivot the pipe about said first cradle until the pipe is in contact with said die and thereafter driving said beam second cradle away from said beam to bend the pipe against said die.
16. A machine according to claim 15, a force exerted on said second cradle by said actuator being insufficient to bend the pipe before the pipe contacts said die driving and being sufficient by application of mechanical advantage on said first cradle to bend the pipe after the pipe contacts said die.
17. A machine according to claim 16, said mechanical advantage being leverage created by said beam and said fulcrum.
18. A machine according to claim 15, said actuator comprising an hydraulic cylinder.
19. A machine according to claim 15, said actuator comprising a screw drive.
20. A machine according to claim 15 further comprising a radial control arm pivotally connected at one end to said beam and at another end to said cradle, said arm being biased to a neutral telescopic condition and responsive to expansive and compressive forces applied thereto by said second cradle to exert compressive and expansive counter-forces against said second cradle.
Type: Application
Filed: Apr 26, 2011
Publication Date: Oct 27, 2011
Inventors: Bryan R. Kirchmer (Granger, IN), Laprentis Eugene McIntosh (Tulsa, OK)
Application Number: 13/094,623
International Classification: B21D 9/00 (20060101); B21D 7/00 (20060101);