JP2013144320A - Pipe bending apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the thickness reduction and flatness of a pipe accurately suppressible in a pipe bending apparatus and a method for pipe bending.SOLUTION: The base end of a pipe P is made to be pressable with a hydraulic cylinder 12 and, meanwhile, the top end of the pipe P is held by a first holding mechanism 19 of a turning arm 17, made to be guidable in a bending direction and also a driven gear 22 for holding the pipe P and imparting torsional stress to the pipe P is supported to be capable of rotational driving. With the hydraulic cylinder 12 and the driven gear 22 operated, a process for imparting the torsional stress to the pipe P and a process for imparting the bending stress are alternately repeated and the bending work is applied to the pipe P.

Description

  The present invention relates to a pipe bending apparatus and method for bending a pipe.

  In a once-through boiler, a large number of heat transfer tubes are arranged mainly in the vertical direction to form a water cooling wall of the furnace. Water is supplied to each heat transfer tube of the furnace water cooling wall by a feed water pump and a burner is provided. Thus, steam is generated by heating the internal water via the heat transfer tube, and this steam is sent to, for example, a steam turbine for driving.

  In such a once-through boiler, the lower end of a large number of heat transfer tubes constituting the furnace water cooling wall is connected to the water drum at the header, and the water drum is supplied with water by a water supply pump. The water inside is supplied to each heat transfer tube. Therefore, it is necessary to form a bend part in the lower part of the heat transfer tube.

  As a technique for bending a pipe, for example, there are those described in Patent Documents 1 and 2 below. The method and apparatus for bending a metal pipe described in Patent Document 1 is such that the rear end of the pipe is supported by a piston and is held by a twisting device having a chuck mechanism to maintain the tip at a predetermined radius. To be gripped by the guide arm of the rotating arm and bent by applying torsional force in parallel with plastic deformation in the axial direction of the pipe due to the pressing force of the piston and the compression force accompanying the back pressure of the guide bracket It is.

  Further, the pipe bending machine described in Patent Document 2 heats the heated tube wall region of the metal tube, and then presses the bending die having an outer contour with the same bending radius as the bending radius of the bending portion against the metal tube. However, this metal tube is bent. In this device, when the clamping mechanism is pushed by the hydraulic cylinder device and the held pipe is pushed into the guide bending pipe to bend the pipe, the pipe is twisted to suppress an increase or decrease in the wall thickness. Yes.

JP 58-68430 A Japanese Patent Application Laid-Open No. 07-051752

  However, in the metal pipe bending method and apparatus of Patent Document 1, the application of torsional force is aimed at facilitating plastic deformation due to multiaxial stress, resulting in a reduction in the thickness reduction rate. However, there is no disclosure about how much torsion should be given. Further, even in the pipe bending machine of Patent Document 2 described above, the rotation amount (twisting amount) is suitably within 360 °. There is only a description that the length of the screw shaft and the twist angle of the spiral groove are appropriately set according to the material of the workpiece, the bending allowance, and the rotation angle, and there is no disclosure of a method for determining an appropriate twist amount. .

  The present invention solves the above-described problems, and an object of the present invention is to provide a pipe bending apparatus and method capable of suppressing pipe thinning and flatness with high accuracy.

  In order to achieve the above object, a pipe bending apparatus of the present invention comprises pipe bending means for holding a pipe end portion and applying a bending stress, and pipe twisting means for applying a torsional stress to the pipe. In the pipe bending apparatus, by alternately repeating the application of the bending stress by the pipe bending means and the application of the torsional stress by the pipe twisting means, the thickness reduction rate of the bent portion is made substantially zero. It is a feature.

  The pipe bending apparatus of the present invention is a pipe bending apparatus comprising pipe bending means for applying bending stress while holding an end of the pipe, and pipe twisting means for applying torsional stress to the pipe. The twist angle of the pipe by the twisting means is set based on the pipe outer diameter, the pipe bend radius, and the pipe bend angle so that the length in the twist direction of the pipe approximates the length of the neutral axis of the pipe. Thus, the thickness reduction rate of the bent portion is made substantially zero.

  In the pipe bending method of the present invention, the process of applying a torsional stress to the pipe and the process of applying a bending stress to the pipe are alternately repeated so that the thinning ratio of the bent part becomes almost zero. The pipe is bent.

  The pipe bending method according to the present invention includes a process of applying a torsional stress to a pipe and a process of applying a bending stress to the pipe, wherein the pipe is twisted at a length in the twisting direction of the pipe. By setting based on the pipe outer diameter, pipe bending radius, and pipe bending angle so as to approximate the length of the neutral axis, the pipe is bent so that the thinning rate of the bent portion is almost zero. It is characterized by applying.

  According to the pipe bending apparatus of the present invention, pipe bending means for applying bending stress by holding the end of the pipe and pipe twisting means for applying torsional stress to the pipe are provided, and the bending stress by the pipe bending means is provided. By alternately applying the torsional stress and applying the torsional stress by the pipe twisting means, the thinning rate of the bent part is made almost zero, so creep damage due to stress concentration rather than processing with conventional processing equipment Can be made difficult to occur, and thinning and flattening of the pipe can be suppressed with high accuracy.

  According to the pipe bending apparatus of the present invention, in a pipe bending apparatus comprising pipe bending means for applying bending stress while holding the end of the pipe, and pipe twisting means for applying torsional stress to the pipe, The twisting angle of the pipe by the pipe twisting means is set based on the pipe outer diameter, the pipe bending radius, and the pipe bending angle so that the length in the twisting direction of the pipe approximates the length of the neutral axis of the pipe. By doing so, the thickness reduction rate of the bent part is made almost zero, so that it is less likely to cause creep damage due to stress concentration than with the conventional processing equipment, and the pipe thickness reduction is accurate. And flatness can be suppressed.

  According to the pipe bending method of the present invention, the thinning rate of the bent portion is substantially zero by alternately performing the process of applying torsional stress to the pipe and the process of applying bending stress to the pipe. Since the pipe is bent, creep damage due to stress concentration can be made less likely to occur than with the conventional processing method, and thinning and flattening of the pipe can be suppressed with high accuracy.

  According to the pipe bending method of the present invention, a process for imparting torsional stress to a pipe and a process for imparting bending stress to a pipe are performed, and the twist angle of the pipe is determined so that the length in the torsional direction of the pipe is within the pipe. By setting the pipe based on the pipe outer diameter, pipe bending radius and pipe bending angle so as to approximate the length of the sex axis, the pipe is bent so that the thinning rate of the bent portion is almost zero. As compared with the conventional processing method, creep damage due to stress concentration can be made difficult to occur, and pipe thinning and flatness can be suppressed with high accuracy.

FIG. 1 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram illustrating an operating state of the pipe bending apparatus according to the first embodiment. FIG. 3 is a schematic diagram illustrating the principle of a bending method by the pipe bending apparatus according to the first embodiment. FIG. 4 is a flowchart illustrating a procedure of a bending method performed by the pipe bending apparatus according to the first embodiment. FIG. 5 is a graph showing the flatness ratio with respect to the twist angle by the pipe bending apparatus and method of the first embodiment. FIG. 6 is a graph showing the thinning rate with respect to the twist angle by the pipe bending apparatus and method of Example 1. FIG. 7 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 2 of the present invention. FIG. 8 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 3 of the present invention. FIG. 9 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 4 of the present invention. FIG. 10 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 5 of the present invention. FIG. 11 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 6 of the present invention. FIG. 12 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 7 of the present invention. 13 is a cross-sectional view taken along line XIII-XIII in FIG.

  Exemplary embodiments of a pipe bending apparatus and method according to the present invention will be explained below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example.

  1 is a schematic configuration diagram illustrating a pipe bending apparatus according to a first embodiment of the present invention, FIG. 2 is a schematic diagram illustrating an operating state of the pipe bending apparatus according to the first embodiment, and FIG. FIG. 4 is a schematic diagram showing the principle of the bending method by the pipe bending apparatus, FIG. 4 is a flowchart showing the procedure of the bending method by the pipe bending apparatus of the first embodiment, and FIG. 5 is the pipe bending apparatus of the first embodiment. FIG. 6 is a graph showing the thinning rate with respect to the torsion angle by the pipe bending apparatus and method of Example 1. FIG.

  In the pipe bending apparatus according to the first embodiment, as shown in FIG. 1, a hydraulic cylinder 12 is installed on the first mount 11, and an output rod 13 of the hydraulic cylinder 12 is connected to a proximal end portion of the pipe P. Is connected to the support substrate 14. A rotating arm 17 is rotatably supported by a support shaft 18 via a mounting bracket 16 on the second pedestal 15, located on the front side of the hydraulic cylinder 12 described above. The rotating arm 17 is equipped with a first holding mechanism (first restraining means) 19 that holds the tip of the pipe P at the center. The second frame 15 is provided with a mold 20 comprising a pair of guide members 20a and 20b for supporting the outer periphery of the pipe P. The guide members 20a and 20b are semicircular on opposite surfaces. A guide surface is formed.

  In this embodiment, the rotating arm 17 functions as a guide means of the present invention for holding the tip of the pipe P and guiding the pipe P in a predetermined bending direction, and the hydraulic cylinder 12 moves the pipe P in the axial direction. It functions as the pipe moving means of the present invention. The hydraulic cylinder 12 and the rotating arm 17 function as a pipe bending means of the present invention that holds the end of the pipe P and applies a bending stress from the outside.

  A driven gear 22 is rotatably supported by a bearing (not shown) on a third frame 21 located between the first frame 11 and the second frame 15, and a drive device 23 installed on the third frame 21. A drive gear 24 meshes with the driven gear 22. The driven gear 22 has a second holding mechanism (second restraining means) 25 that holds the outer periphery of the pipe P at the center. In this embodiment, the driven gear 22, the driving device 23, and the driving gear 24 function as pipe twisting means of the present invention that applies torsional stress to the pipe P from the outside.

  In the pipe bending method using the pipe bending apparatus of the present embodiment, a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P are alternately repeated, so that the pipe P Bending is performed. Therefore, as described above, the rotating arm 17 has the first holding mechanism 19, the driven gear 22 has the second holding mechanism 25, and the first holding mechanism 19 of the rotating arm 17 is always Although the pipe P is held, the second holding mechanism 25 of the driven gear 22 restrains the pipe P and applies a torsional stress when the pipe P is twisted, but when the pipe P is bent, The restraint is released.

  That is, when bending is performed on the pipe P whose cross section is a perfect circle shape, the thickness is increased by compression inside the pipe P and the thickness is reduced by tension outside the bend. At this time, the pipe P has a flat shape. Therefore, in the present embodiment, twisting and bending are alternately applied to the pipe P so as to absorb changes in the thickness of the pipe P.

  Further, in the present embodiment, the twist angle (amount) of the pipe P is set, that is, calculated so that the thickness reduction rate at the bent portion is substantially zero. Specifically, the twist angle of the pipe P is set based on the pipe diameter, the pipe bending radius, and the pipe bending angle.

  Here, the flatness ratio with respect to the twist angle and the thinning ratio with respect to the twist angle by the pipe bending apparatus and method of the first embodiment will be described. As shown in FIG. 5, when the twist angle is 0 degree, the flatness of the pipe is large, but when the twist angle is secured to a predetermined angle as in this embodiment, the flatness of the pipe decreases. I understand. In addition, as shown in FIG. 6, when bending is performed without twisting, that is, when the twist angle is 0 degree, the pipe thinning rate is small, but as in this embodiment, the pipe is twisted. As is added, the thickness reduction rate of the pipe increases, and it can be seen that the thickness reduction rate becomes 0 at a certain twist angle.

Here, the flatness ratio and the thinning ratio are obtained by the following mathematical formulas.
Flatness ratio = (long diameter of pipe after bending-short diameter of pipe after bending) / pipe diameter before bending Thinning ratio = (outer wall thickness of pipe after bending-pipe thickness before bending) (Thickness) / thickness of pipe before bending Further, the thinning rate is almost 0 here means that -1% <thickness reduction <1%. If the thinning rate is such a value, it is substantially unnecessary to distinguish from other portions.

  In addition, the pipe diameter concerning setting of a twist angle uses any one or both of the internal diameter of a pipe, an outer diameter. Usually, since a standard product is used for the pipe, if either the inner diameter or the outer diameter is determined, the other is also determined. When the pipe is not a normal standard product, the torsion angle at which the thickness reduction rate becomes 0 can be determined more accurately by using both the inner diameter and the outer diameter.

  As shown in FIG. 3, when bending the pipe P, the torsion angle of the pipe P is set so that the thinning ratio is substantially zero based on the outer diameter D, the pipe bending radius r, and the pipe bending angle θ. When set, the portion located inside at the start of machining moves to the outside along with the twisting of the pipe P, while the portion located outside at the beginning of machining is accompanied by the twisting of the pipe P. Since it moves to the inside, it is possible to suppress the thickness increase phenomenon due to the compression of the material inside the pipe P and the thickness reduction phenomenon due to the tension of the material outside the bend, and to suppress the flattening of the pipe P. it can. L1 and L2 are examples showing how the line on the pipe surface parallel to the pipe axis before machining moves and deforms after machining.

  Here, the pipe bending method using the pipe bending apparatus of the present embodiment will be specifically described with reference to the flowchart of FIG.

  In the pipe bending method using the pipe bending apparatus according to the present embodiment, as shown in FIGS. 1 and 4, in step S11, a pipe P having a straight cross section having a perfect circular shape is formed into a pipe bending apparatus. Attach to. That is, the pipe P is inserted into the rotating arm 17, the mold 20, and the driven gear 22, and the base end portion is in contact with the support substrate 14, while the distal end portion is held by the first holding mechanism 19 of the rotating arm 17. . At this time, the second holding mechanism 25 of the driven gear 22 is released from holding the pipe P.

  First, in step S 12, the hydraulic cylinder 12 is extended, and the pipe P is pressed by the support substrate 14 to advance (microfeed) by a predetermined amount. It rotates to apply bending stress to the tip of the pipe P. Next, in step S13, the intermediate portion of the pipe P is held by the second holding mechanism 25 of the driven gear 22. Subsequently, in step S14, the driving device 23 is operated to rotate the driving gear 24. By transmitting the rotational force to the driven gear 22, the driven gear 22 is rotated by a small angle, and a torsional stress is applied to the pipe P.

  In step S15, the holding of the pipe P by the second holding mechanism 25 of the driven gear 22 is released. Subsequently, in step S16, the hydraulic cylinder 12 is again extended and the pipe P is moved by the support substrate 16. By pressing and finely feeding, the distal end portion of the pipe P is rotated together with the rotating arm 17, and a bending stress is applied to the distal end portion of the pipe P. At this time, since the pipe P is moved and bent in the axial direction while being supported by the mold 20, deformation in the direction other than the bending direction is suppressed. In step S17, it is determined whether or not the pipe P has been bent to a predetermined bending angle. If the pipe P has not been bent to a predetermined bending angle, the process returns to step S13, and the pipe P is bent to a predetermined bending angle. Steps S13 to S17 are repeated.

  At this time, during processing of the pipe P, torsional stress and bending stress are alternately applied to the pipe P, so that the pipe P is bent while rotating. In other words, since the portion of the pipe P located inside at the start of machining moves to the outside along with the twisting of the pipe P, the material compressed inside the pipe P bends and flows outside. It is possible to suppress the thickness increase phenomenon due to the compression of the material inside the bending of P and the thickness reduction phenomenon due to the tension of the material outside the bending, and it is possible to suppress the flattening of the pipe P.

  After that, if it is determined in step S17 that the pipe P has been bent to a predetermined bending angle as shown in FIG. 2, the pipe P in which the bend is formed by bending is formed in step S18. Remove from the processing equipment.

  As described above, in the pipe bending apparatus and method according to the first embodiment, the proximal end portion of the pipe P can be pressed by the hydraulic cylinder 12, while the distal end of the pipe P is supported by the first holding mechanism 19 of the rotating arm 17. By supporting the driven gear 22 that holds the pipe P in the bending direction and supports the driven gear 22 that applies the torsional stress while driving and rotating the hydraulic cylinder 12 and the driven gear 22, The process of applying torsional stress to P and the process of applying bending stress are alternately repeated, and the pipe P is bent by setting the pipe torsion amount so that the thinning ratio of the bent portion is almost zero. I am doing so.

  Therefore, by alternately applying torsional stress and bending stress to the pipe P, the pipe P is bent while being rotated, and the portion located inside at the start of processing is Since it moves to the outside along with the twisting process, the thickness increase phenomenon inside the bending of the pipe P and the thickness reduction phenomenon outside the bending are suppressed, and the flattening of the pipe is suppressed. A bend pipe having a desired shape can be easily manufactured, and the manufacturing cost can be reduced. As a result, creep damage due to stress concentration can be made less likely to occur than with the conventional processing apparatus and method, and pipe thinning and flatness can be suppressed with high accuracy.

  In addition, the first holding mechanism 19 is provided on the rotating arm 17, the second holding mechanism 25 is provided on the driven gear 22, the first holding mechanism 19 always holds the pipe P, and the second holding mechanism 25 is The pipe P is held when the pipe P is twisted by the rotation of the driven gear 22, and the pipe P is moved by the hydraulic cylinder 12, and the holding of the pipe P is released when the pipe P is bent by the rotating arm 12. . Accordingly, since the second holding mechanism 25 holds the pipe P during the twisting operation of the pipe P, a predetermined twisting amount can be reliably given to the pipe P, while the second holding mechanism is provided during the bending operation of the pipe P. Since 25 does not hold | maintain the pipe P, the pipe P can move appropriately, the damage of the 2nd holding | maintenance mechanism 25 can be prevented, and it can contribute to simplification of a structure.

  In this embodiment, when the pipe P having the outer diameter D is bent at the pipe bending radius r by the pipe bending angle θ, the twist angle (amount) of the pipe P is the length L1, L1 in the twist direction of the pipe P. L2 is set based on the pipe outer diameter D, the pipe bending radius r, and the pipe bending angle θ so that the length of the neutral axis O of the pipe P is approximated. Therefore, when torsional stress is applied to the pipe P, the length in the twisting direction of the pipe P approximates the length of the neutral axis O of the pipe P by setting the twisting angle to a predetermined value. It is possible to suppress the thickening phenomenon inside the bending of P and the thinning phenomenon outside the bending.

  FIG. 7 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the pipe bending apparatus according to the second embodiment, as shown in FIG. 7, a hydraulic cylinder 12 is installed on the first mount 11, and the base end portion of the pipe P can be pressed against the output rod 13 of the hydraulic cylinder 12. The support substrate 14 is connected. A rotating arm 17 is rotatably supported by a support shaft 18 via a mounting bracket 16 on the second base 15, and a first holding mechanism 19 is attached to the rotating arm 17. Further, the second frame 15 is provided with a mold 20 including a pair of guide members 20a and 20b that support the outer periphery of the pipe P. In addition, a driven gear 22 is rotatably supported on the third frame 21, and a driving gear 24 of a driving device 23 is engaged with the driven gear 22. A second holding mechanism 25 is attached to the driven gear 22. ing.

  In this embodiment, a high-frequency induction heating mechanism 31 is provided as a heating unit that is positioned between the rotating arm 17 and the mold 20 and heats the vicinity of the bending fulcrum of the pipe P. The high frequency induction heating mechanism 31 includes a heating coil 32 positioned around the pipe P and a transformer 33 connected to the heating coil 32, and the heating coil 32 mechanically moves near the bending fulcrum of the pipe P. It is possible to heat up to near the melting temperature.

  And the pipe bending method using the pipe bending apparatus of a present Example is a pipe bending process by alternately applying a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P. P is bent, and at this time, the high frequency induction heating mechanism 31 heats the pipe P to near the mechanical melting temperature. Therefore, the pipe P can reduce the processing force for bending and twisting because the internal stress of the material is reduced.

  That is, during processing of the pipe P, torsional stress by the driving device 12 and bending stress by the hydraulic cylinder 14 are alternately applied to the pipe P, so that the pipe P is bent by the rotating arm 19 while rotating. . At this time, the vicinity of the bending fulcrum of the pipe P is heated by the high frequency induction heating mechanism 31 and the internal stress is reduced, so that the driving force (working force) of the hydraulic cylinder 12 and the driven gear 22 (drive device 23) is reduced. And since the part which was located inside the pipe P at the time of a bending process starts moving outside with the twisting process of the pipe P, the material compressed inside the bending of the pipe P will flow to the outside, The thickness increase phenomenon due to the compression of the material inside the bending of the pipe P and the thickness reduction phenomenon due to the tension of the material outside the bending can be suppressed, and the flattening of the pipe P can be suppressed.

  As described above, in the pipe bending apparatus and method according to the second embodiment, the proximal end portion of the pipe P can be pressed by the hydraulic cylinder 12, while the distal end of the pipe P is supported by the first holding mechanism 19 of the rotating arm 17. A high frequency that holds the pipe and can be guided in the bending direction, supports the driven gear 22 that holds the pipe P and applies torsional stress so that it can be driven to rotate, and heats the vicinity of the bending fulcrum of the rotation of the pipe P An induction heating mechanism 31 is provided.

  Accordingly, in the state where the vicinity of the bending fulcrum of the pipe P is heated by the high frequency induction heating mechanism 31, the torsional stress by the driving device 23 and the bending stress by the hydraulic cylinder 12 are alternately and repeatedly applied to the pipe P. The pipe P is bent while being bent, and the portion located inside at the start of processing moves to the outside along with the torsion processing. It is possible to suppress the thinning phenomenon on the outside and to suppress the flattening of the pipe, so that a bend pipe having a desired shape can be easily manufactured with a simple configuration and the manufacturing cost can be reduced. it can.

  Further, when bending the pipe P, since the vicinity of the bending fulcrum of the pipe P is heated to the vicinity of the mechanical melting temperature by the high frequency induction heating mechanism 31, the internal stress of the pipe P is reduced, so that the processing force is reduced. Since the reaction force can be reduced while reducing the size, it is possible to perform highly accurate bending with a low processing force. Since the portions other than the bending fulcrum of the pipe P are not heated and are close to normal temperature, the holding portions by the holding mechanisms 19 and 25 are not deformed, and by holding the pipe P appropriately, high-precision processing can be performed. It becomes possible.

  In the second embodiment, the high frequency induction heating mechanism 31 is applied as the heating means for heating the pipe P. However, the present invention is not limited to this, and an electric heater, a gas heater, or the like may be applied.

  FIG. 8 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 3 of the present invention.

  In the pipe bending apparatus according to the third embodiment, as shown in FIG. 8, a horizontal substrate 42 is installed on the lower frame 41, and a hydraulic cylinder 44 is mounted on the upper frame 43. An arc-shaped push die 46 is connected to the tip of the output rod 45 extending below the cylinder 44. A pair of guide tubes 47a and 47b for supporting the pipe P is provided on the substrate 42, and rolling rollers 48a and 48b are mounted below the guide tubes 47a and 47b. A driving device (not shown) is provided that applies a torsional stress by rotating the pipe P in the circumferential direction via the guide tubes 47a and 47b. In this embodiment, the pipe bending means of the present invention is constituted by the hydraulic cylinder 44 and the push die 46.

  And the pipe bending method using the pipe bending apparatus of a present Example is a pipe bending process by alternately applying a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P. B is bent. That is, when bending is performed on the pipe P whose cross section is a perfect circle shape, the thickness is increased by compression inside the pipe P and the thickness is reduced by tension outside the bend. At this time, the pipe P has a flat shape. Therefore, in the present embodiment, twisting and bending are alternately applied to the pipe P so as to absorb changes in the thickness of the pipe P.

  Accordingly, a straight pipe P having a perfectly circular cross section is inserted into the guide tubes 47a and 47b and supported on the substrate 42. First, a bending stress is applied to the intermediate portion of the pipe P by operating the hydraulic cylinder 44 and lowering the pressing die 46 by a predetermined amount. Next, in a state where rotation of the pipe P in the circumferential direction is constrained, the driving device is operated to rotate the pipe P by a predetermined amount, whereby torsional stress is applied to the pipe P. Then, in a state where the restriction of the pipe P is released, the hydraulic cylinder 44 is actuated again to lower the push die 46 by a predetermined amount, thereby applying bending stress to the intermediate portion of the pipe P. The pipe P is bent to a predetermined bending angle by repeatedly performing the bending process of the pipe P by the hydraulic cylinder 44 and the twisting process of the pipe P by the driving device.

  During processing of the pipe P, torsional stress and bending stress are alternately applied to the pipe P, so that the pipe P is bent while rotating. In other words, since the portion of the pipe P located inside at the start of machining moves to the outside along with the twisting of the pipe P, the material compressed inside the pipe P bends and flows outside. It is possible to suppress the thickness increase phenomenon due to the compression of the material inside the bending of P and the thickness reduction phenomenon due to the tension of the material outside the bending, and it is possible to suppress the flattening of the pipe P.

  As described above, in the pipe bending apparatus and method according to the third embodiment, the horizontal base plate 42 is installed on the lower frame 41, while the hydraulic cylinder 44 is mounted on the upper frame 43, and the output rod extends downward. An arc-shaped pressing die 46 is connected to the tip of 45, and a pair of guide tubes 47a and 47b for supporting the pipe P is provided on the substrate 42. The pipe P is rotated in the circumferential direction via the guide tubes 47a and 47b. A driving device that moves and applies torsional stress is provided, and the pipe P is bent by alternately repeating the process of applying torsional stress to the pipe P and the process of applying bending stress.

  Therefore, by repeatedly applying torsional stress and bending stress to the pipe P using a driving device and press working, the pipe P is bent while being turned, and the inner side at the start of machining is applied. Since the portion located in the position moves to the outside along with the torsion processing, the thickness increase phenomenon inside the bending of the pipe P and the thickness reduction phenomenon outside the bending are suppressed, and the flattening of the pipe is suppressed. Thus, a bend pipe having a desired shape can be easily manufactured with a simple configuration, and the manufacturing cost can be reduced.

  At this time, the pipe P can be easily bent by pressing the pressing die 46 against the outer peripheral portion of the pipe P by the hydraulic cylinder 44.

  FIG. 9 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 4 of the present invention.

  In the pipe bending apparatus according to the fourth embodiment, as shown in FIG. 9, a horizontal arc-shaped fixed mold 52 is installed on the lower frame 51, while pipe twisting means are provided on the left and right side frames 53a and 53b. Driving devices 54a and 54b are installed, and hydraulic cylinders 56a and 56b are attached to the tip ends of the output shafts 55a and 55b of the driving devices 54a and 54b. And the support substrates 58a and 58b which support the edge part of the pipe P are connected with the front-end | tip part of output rod 57a, 57b of this hydraulic cylinder 56a, 56b. In the present embodiment, the hydraulic cylinders 56a and 56b and the fixed mold 52 constitute the pipe bending means of the present invention.

  And the pipe bending method using the pipe bending apparatus of a present Example is a pipe bending process by alternately applying a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P. B is bent. That is, when bending is performed on the pipe P whose cross section is a perfect circle shape, the thickness is increased by compression inside the pipe P and the thickness is reduced by tension outside the bend. At this time, the pipe P has a flat shape. Therefore, in the present embodiment, twisting and bending are alternately applied to the pipe P so as to absorb changes in the thickness of the pipe P.

  Therefore, the end portions of the straight pipe P having a perfect circular cross section are supported by the support substrates 58a and 58b. First, the hydraulic cylinders 56a and 56b are actuated to apply a tensile force to each end of the pipe P, and an intermediate part of the pipe P is pressed against the fixed mold 52, whereby a bending stress is applied to the pipe P. To do. At this time, it is desirable to move the driving devices 54a and 54b and the hydraulic cylinders 56a and 56b downward. Next, torsional stress is applied to the pipe P by operating the driving devices 54a and 54b to rotate the pipe P by a predetermined amount. Then, again, the hydraulic cylinders 56a and 56b are operated to press the pipe P against the fixed mold 52, so that bending stress is applied to the intermediate portion of the pipe P. The pipe P is bent to a predetermined bending angle by repeatedly performing the bending process of the pipe P by the hydraulic cylinders 56a and 56b and the twisting process of the pipe P by the driving devices 54a and 54b.

  During processing of the pipe P, torsional stress and bending stress are alternately applied to the pipe P, so that the pipe P is bent while rotating. In other words, since the portion of the pipe P located inside at the start of machining moves to the outside along with the twisting of the pipe P, the material compressed inside the pipe P bends and flows outside. It is possible to suppress the thickness increase phenomenon due to the compression of the material inside the bending of P and the thickness reduction phenomenon due to the tension of the material outside the bending, and it is possible to suppress the flattening of the pipe P.

  As described above, in the pipe bending apparatus and method according to the fourth embodiment, the arc-shaped fixed mold 52 is installed on the lower frame 41, while the driving devices 54a and 54b and the hydraulic cylinders 56a and 56b are arranged on the sides. A process of applying a tensile force to the pipe P by the hydraulic cylinders 56a and 56b and enabling a bending process by applying a rotational force by the moving devices 54a and 54b and applying a torsional stress to the pipe P The pipe P is bent by alternately and repeatedly applying the bending stress and the process of applying the bending stress.

  Therefore, the twisting force and the bending stress are alternately and repeatedly applied to the pipe P using the rotational force and the tensile force, so that the pipe P is bent while being turned, and the inner side at the start of the processing is performed. Since the portion located in the position moves to the outside along with the torsion processing, the thickness increase phenomenon inside the bending of the pipe P and the thickness reduction phenomenon outside the bending are suppressed, and the flattening of the pipe is suppressed. Thus, a bend pipe having a desired shape can be easily manufactured with a simple configuration, and the manufacturing cost can be reduced.

  At this time, by applying a tensile force to the pipe P by the hydraulic cylinders 56a and 56b, the outer peripheral portion of the pipe P is pressed against the fixed mold 52 to bend, thereby easily bending the pipe P. Can be applied.

  FIG. 10 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 5 of the present invention.

  In the pipe bending apparatus according to the fifth embodiment, as shown in FIG. 10, the fixed die 61 has an arcuate guide portion 61a. Further, a restraining member 62 is provided on the side of the fixed die 61, and the end of the pipe P can be restrained to the fixed die 61 by the restraining member 62. Further, a pressing member 63 is supported so as to be movable along an arc-shaped guide rail 64 so as to face the guide portion 61 a of the fixed mold 61. A driving device (not shown) that rotates the pipe P supported by the restraining member 62 in the circumferential direction to apply torsional stress is provided. In this embodiment, the fixed die 61 and the pressing member 63 constitute the pipe bending means of the present invention.

  And the pipe bending method using the pipe bending apparatus of a present Example is a pipe bending process by alternately applying a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P. B is bent. That is, when bending is performed on the pipe P whose cross section is a perfect circle shape, the thickness is increased by compression inside the pipe P and the thickness is reduced by tension outside the bend. At this time, the pipe P has a flat shape. Therefore, in the present embodiment, twisting and bending are alternately applied to the pipe P so as to absorb changes in the thickness of the pipe P.

  Therefore, the end portion of the straight pipe P whose cross section is a perfect circle is restrained and supported by the stationary die 61 by the restraining member 62. First, a bending stress is applied to the pipe P by operating a hydraulic cylinder (not shown) to move the pressing member 63 along the guide rail 64 by a predetermined amount. Next, a torsional stress is applied to the pipe P by operating the driving device to rotate the pipe P by a predetermined amount. Then, by again moving the pressing member 63 by a predetermined amount, bending stress is applied to the pipe P. The pipe P is bent to a predetermined bending angle by repeatedly performing the bending process of the pipe P by the pressing member 63 and the twisting process of the pipe P by the driving device.

  During processing of the pipe P, torsional stress and bending stress are alternately applied to the pipe P, so that the pipe P is bent while rotating. In other words, since the portion of the pipe P located inside at the start of machining moves to the outside along with the twisting of the pipe P, the material compressed inside the pipe P bends and flows outside. It is possible to suppress the thickness increase phenomenon due to the compression of the material inside the bending of P and the thickness reduction phenomenon due to the tension of the material outside the bending, and it is possible to suppress the flattening of the pipe P.

  As described above, in the pipe bending apparatus and method according to the fifth embodiment, the fixed die 61 is provided with the arc-shaped guide portion 61a, and the fixed die 61 is provided with the restraining member 62 that restrains the end portion of the pipe P. The pressing member 63 is movably supported along the arc-shaped guide rail 64 so as to face the guide portion 61a of the fixed mold 61, and the pipe P supported by the restraining member 62 is rotated in the circumferential direction to apply torsional stress. A driving device is provided, and the pipe P is bent by alternately performing a process of applying a torsional stress to the pipe P and a process of applying a bending stress.

  Accordingly, the twisting stress and the bending stress are alternately and repeatedly applied to the pipe P using the driving device and the pressing member 63, so that the bending process is performed while the pipe P is rotated. Since the portion located inside moves to the outside along with the twisting process, the thickness increase phenomenon inside the pipe P and the thickness reduction phenomenon outside the bending are suppressed, and the flattening of the pipe is suppressed. Thus, a bend pipe having a desired shape can be easily manufactured with a simple configuration, and the manufacturing cost can be reduced.

  At this time, since the pressing member 63 is moved along the guide portion 61a of the fixed mold 61, the pipe P is bent by being pressed against the outer peripheral portion of the pipe P. Therefore, the pipe P can be easily bent. it can.

  FIG. 11 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 6 of the present invention.

  In the pipe bending apparatus of the sixth embodiment, as shown in FIG. 11, a hydraulic cylinder 73 is connected to an output shaft 72 of a driving device 71 as pipe twisting means, and an output rod 74 of the hydraulic cylinder 73 is connected to an output rod 74. A support substrate 75 that supports the base end of the pipe P is connected. The support substrate 75 is provided with a mandrel 76 that is inserted into the pipe P. A disc-shaped first guide member 77 is rotatably supported in front of the hydraulic cylinder 73, and a linear first guide portion 77 a and an arc-shaped second guide are provided on the outer periphery of the first guide member 77. A portion 77b is formed. A second guide member 78 is provided opposite to the first guide portion 77a of the first guide member 77, and the second guide member 78 is moved closer to the first guide member 77 by a hydraulic cylinder (not shown). The end portion of the pipe P can be restrained by the guide members 77 and 78. A linear guide 79 that guides the movement of the pipe P is provided between the support substrate 75 and the first guide member 77. In this embodiment, the hydraulic cylinder 73 and the guide members 77 and 78 constitute the pipe bending means of the present invention.

  And the pipe bending method using the pipe bending apparatus of a present Example is a pipe bending process by alternately applying a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P. B is bent. That is, when bending is performed on the pipe P whose cross section is a perfect circle shape, the thickness is increased by compression inside the pipe P and the thickness is reduced by tension outside the bend. At this time, the pipe P has a flat shape. Therefore, in the present embodiment, twisting and bending are alternately applied to the pipe P so as to absorb changes in the thickness of the pipe P.

  Accordingly, the base end portion of the straight pipe P having a perfect circular cross section is supported by the support substrate 75 and the tip end portion of the pipe P is supported by the guide members 77 and 79. First, the hydraulic cylinder 73 is actuated to advance the pipe P by a predetermined amount via the support substrate 75, whereby the tip end portion of the pipe P is rotated together with the guide members 77 and 78. Bending stress is applied to. Next, the driving device 71 is operated to rotate the pipe P by a predetermined amount via the hydraulic cylinder 73 and the support substrate 75, thereby applying a torsional stress to the pipe P. Subsequently, by operating the hydraulic cylinder 73 again to advance the pipe P by a predetermined amount via the support substrate 75, the tip end portion of the pipe P is rotated together with the guide members 77 and 78, and the tip end of the pipe P Apply bending stress to the part. The pipe P is bent to a predetermined bending angle by repeatedly performing the bending process of the pipe P by the hydraulic cylinder 73 and the twisting process of the pipe P by the driving device 71.

  During processing of the pipe P, torsional stress and bending stress are alternately applied to the pipe P, so that the pipe P is bent while rotating. In other words, since the portion of the pipe P located inside at the start of machining moves to the outside along with the twisting of the pipe P, the material compressed inside the pipe P bends and flows outside. It is possible to suppress the thickness increase phenomenon due to the compression of the material inside the bending of P and the thickness reduction phenomenon due to the tension of the material outside the bending, and it is possible to suppress the flattening of the pipe P.

  As described above, in the pipe bending apparatus and method according to the sixth embodiment, the hydraulic cylinder 73 is connected to the output shaft 72 of the driving device 71, and the base end portion of the pipe P is supported by the output rod 74 of the hydraulic cylinder 73. A support substrate 75 is connected to the front side of the hydraulic cylinder 73, and a first guide member 77 having a disk shape is rotatably supported in front of the hydraulic cylinder 73, and a second guide member 78 for restraining the tip of the pipe P is provided. The pipe P is bent by alternately and repeatedly performing the process of applying a torsional stress and the process of applying a bending stress to the pipe P.

  Therefore, the twisting stress and the bending stress are alternately and repeatedly applied to the pipe P by using the driving device 71 and the hydraulic cylinder 73 pressing member 63, so that the bending process is performed while the pipe P rotates. Since the portion located inside at the start of machining moves to the outside along with the twisting process, the increase in the thickness of the pipe P on the inner side and the decrease in the thickness on the outer side of the bending are suppressed, and the flatness of the pipe is suppressed. Therefore, it is possible to easily manufacture a bend pipe having a desired shape with a simple configuration and to reduce manufacturing costs.

  At this time, the end portion of the pipe P is restrained by the first guide member 77 by the second guide member 78, and the pipe P is bent along the second guide portion 77b by rotating the first guide member 77. Therefore, the pipe P can be easily bent with high accuracy.

  In Examples 1 to 6 described above, the pie P is bent by alternately performing the process of applying the torsional stress to the pipe P and the process of applying the bending stress to the pipe P. However, the present invention is not limited to this method. That is, the pipe P may be bent by simultaneously performing a process of applying a torsional stress to the pipe P and a process of applying a bending stress to the pipe P. For example, in the first embodiment, the pipe twisting means of the present invention comprising the driven gear 22, the driving device 23, and the driving gear 24 is movably supported along the moving direction of the pipe P, thereby moving the pipe P. Thus, torsional stress can be applied while applying bending stress.

  In the first to sixth embodiments described above, as the pipe twisting means of the present invention, a gear mechanism is provided in the middle portion of the pipe P to impart a twisting rotational force to the pipe P, or in series with a hydraulic cylinder as the pipe bending means. However, the present invention is not limited to these, and an optimal device may be selected as appropriate according to various mechanisms.

  12 is a schematic configuration diagram illustrating a pipe bending apparatus according to Embodiment 7 of the present invention, and FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG.

  In the pipe bending apparatus according to the seventh embodiment, as shown in FIGS. 12 and 13, a support substrate 83 that supports the base end portion of the pipe P is connected to the output rod 82 of the hydraulic cylinder 81 as a pipe moving means. ing. In this case, the support substrate 83 can be rotated by pipe twisting means. A disc-shaped first guide member (inner guide member) 84 is rotatably supported in front of the hydraulic cylinder 81, and a linear first guide portion 84a and an outer peripheral portion of the first guide member 84 are provided. An arcuate second guide portion 84b is formed. A second guide member (outer guide member) 85 is provided to face the first guide portion 84a of the first guide member 84, and the second guide member 85 is connected to the first guide member 84 by a hydraulic cylinder (not shown). By moving closer, the end of the pipe P can be restrained by the guide members 84 and 85. Further, a linear guide 86 for guiding the movement of the pipe P is provided between the support substrate 83 and the first guide member 84. In the present embodiment, the guide members of the present invention are constituted by the guide members 84 and 85.

  In addition, the first guide member 84 and the second guide member 85 are formed with an inner guide surface 87 and an outer guide surface 88 that form a semicircular shape in accordance with the shape of the pipe P. The outer guide surface 88 is formed with a concave portion 89 that protrudes outward with respect to the perfect circle shape indicated by a two-dot chain line in FIG.

  In the pipe bending method using the pipe bending apparatus of the present embodiment, when the pipe P is subjected to a process of applying a bending stress, the pipe P tip portion is provided with the first guide member 84 and the concave portion 89. The pipe P is bent while being held by the member 85. That is, when bending is performed on the pipe P whose cross section is a perfect circle shape, the thickness is increased by compression inside the pipe P and the thickness is reduced by tension outside the bend. At this time, the pipe P has a flat shape. Therefore, in this embodiment, by providing the concave portion 89 in the second guide member 85 that supports the outside of the pipe P among the pair of guide members 84 and 85, the material compressed on the bending inner side of the pipe P is the concave portion. By flowing to the 89 side, the change in the thickness of the pipe P is absorbed.

  Accordingly, the base end portion of the straight pipe P having a perfect circular cross section is supported by the support substrate 83 and the tip end portion of the pipe P is supported by the guide members 84 and 85. First, the hydraulic cylinder 81 is actuated to advance the pipe P by a predetermined amount via the support substrate 83, so that the leading end of the pipe P is rotated together with the guide members 84 and 85, and the leading end of the pipe P is moved. Bending stress is applied to. At this time, when bending stress is applied to the pipe P, the thickness tends to increase due to compression inside the pipe P, but there is a recess 89 in the second guide member 85 that supports the outside of the pipe P. The material compressed inside the bending of the pipe P flows toward the concave portion 89 side, and suppresses the increase in thickness due to the compression of the material inside the bending of the pipe P and the reduction in thickness due to the tension of the material outside the bending. In addition, the flattening of the pipe P can be suppressed. In this case, the process of applying torsional stress to the pipe P and the process of applying bending stress are alternately repeated, and the pipe P is bent so that the thickness reduction rate of the bent portion is substantially zero.

  As described above, in the pipe bending apparatus and method according to the seventh embodiment, the support substrate 83 that supports the base end portion of the pipe P is connected to the output rod 82 of the hydraulic cylinder 81, while the disk is disposed in front of the hydraulic cylinder 81. A first guide member 84 having a shape is rotatably supported, and a second guide member 85 that restrains the tip of the pipe P is provided, and an inner guide surface having a semicircular shape is formed on the opposing surface of each guide member 84, 85. 87 and the outer guide surface 88 are formed, and the outer guide surface 88 is formed with a concave portion 89 that protrudes outward with respect to the perfect circle shape.

  Accordingly, the pipe P is advanced by the hydraulic cylinder 81 and the tip portion thereof is rotated together with the guide members 84 and 85, so that bending stress is applied to the tip portion of the pipe P and the pipe P is bent. At this time, the material compressed on the inner side of the bending of the pipe P flows to the concave portion 89 side, and the portion located on the inner side at the start of processing moves to the outer side in accordance with torsion processing. The thickness increase phenomenon inside the bend and the thickness decrease phenomenon outside the bend are suppressed, and the flattening of the pipe is suppressed, making it possible to easily manufacture a bend pipe having a desired shape with a simple configuration. In addition, the manufacturing cost can be reduced.

  The pipe bending apparatus and method according to the present invention suppresses the increase in thickness on the inner side of the pipe and the decrease in thickness on the outer side of the bend, and also suppresses flattening of the pipe. The present invention can also be applied to a bending apparatus and a pipe bending method.

12 Hydraulic cylinder (pipe bending means, pipe moving means)
14 Support substrate 17 Rotating arm (pipe bending means, guide means)
19 First holding mechanism (first restraining mechanism)
20 Mold (guide means)
22 Driven gear (pipe twisting means)
23 Drive unit (pipe twisting means)
24 Drive gear (pipe twisting means)
25 Second holding mechanism (second restraining mechanism)
31 High-frequency induction overheating mechanism 42 Substrate 44 Hydraulic cylinder (pipe bending means)
46 Push type 52 Fixed type 54a, 54b Driving device (pipe twisting means)
56a, 56b Hydraulic cylinder (pipe bending means)
61 fixed mold 62 restraining member 63 pressing member (pipe bending means)
71 Drive unit (pipe twisting means)
73 Hydraulic cylinder (pipe bending means, pipe moving means)
75 Support substrate 77 First guide member (pipe bending means, guide means)
78 Second guide member (pipe bending means, guide means)
81 Hydraulic cylinder (pipe bending means, pipe moving means)
83 Support substrate 84 First guide member (pipe bending means, guide means)
85 Second guide member (pipe bending means, guide means)
87 Inner guide surface 88 Outer guide surface 89 Recess

Claims (4)

  In a pipe bending apparatus comprising pipe bending means for holding a pipe end to apply bending stress and pipe twisting means for applying torsional stress to the pipe, the bending stress is applied by the pipe bending means and A pipe bending apparatus characterized in that a torsional stress is repeatedly applied alternately by a pipe twisting means so that a thinning ratio of a bent portion becomes substantially zero.   In a pipe bending apparatus comprising pipe bending means for applying bending stress by holding an end of a pipe and pipe twisting means for applying torsional stress to the pipe, the twist angle of the pipe by the pipe twisting means is set. By setting the pipe outer diameter, the pipe bending radius, and the pipe bending angle so that the length in the torsional direction of the pipe approximates the length of the neutral axis of the pipe, A pipe bending apparatus characterized in that the value is substantially zero.   Bending the pipe so that the thinning rate of the bent portion is substantially zero by alternately performing a process of applying a torsional stress to the pipe and a process of applying a bending stress to the pipe. A characteristic pipe bending method.   A process of applying a torsional stress to the pipe and a process of applying a bending stress to the pipe are performed, and the torsion angle of the pipe is approximated to the length of the neutral axis of the pipe in the torsional direction of the pipe The pipe bending process is characterized in that the pipe is bent so that the thinning rate of the bent part is substantially zero by setting based on the pipe outer diameter, the pipe bending radius, and the pipe bending angle. Method.

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