Patent Publication Number: US-2023148390-A1

Title: Forming device and metal pipe

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a bypass continuation of International PCT Application No. PCT/JP2021/028982, filed on Aug. 4, 2021, which claims priority to Japanese Patent Application No. 2020-135822, filed on Aug. 11, 2020, which are incorporated by reference herein in their entirety. 
     BACKGROUND 
     Technical Field 
     Certain embodiments of the present invention relate to a forming device and a metal pipe. 
     Description of Related Art 
     In the related art, a forming device used for forming a metal pipe is known. For example, the related art described below discloses a forming device that includes a forming tool including a lower die and an upper die paired with each other, and a fluid supply unit for supplying a fluid into a metal pipe material held between the forming dies. 
     SUMMARY 
     A forming device according to an aspect of the present invention is a forming device that forms a metal pipe with a flange and includes a forming tool for forming the metal pipe, in which the forming tool includes a first die and a second die that face each other in a first direction in a cross-sectional view, and a third die for regulating a planned flange portion of a metal pipe material, and the third die continues to correct misalignment of the planned flange portion until the first die and the second die are clamped. 
     A metal pipe according to an aspect of the present invention includes a hollow pipe portion, and a pair of flange portions protruding from the pipe portion to both sides in a width direction, in which sizes of the pair of flange portions in the width direction are predetermined sizes different from each other. 
     A forming device according to an aspect of the present invention is a forming device that forms a metal pipe with a flange and includes a forming tool for forming the metal pipe, in which the forming tool includes a first die and a second die facing each other in a first direction in a cross-sectional view, and a third die disposed on at least one side of a metal pipe material in a second direction intersecting the first direction, and the third die moves away from the metal pipe material as the first die and the second die approach each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic view of a forming device according to an embodiment of the present invention. 
         FIG.  2    is a cross-sectional view showing a state when a nozzle has sealed a metal pipe material. 
         FIGS.  3 A and  3 B  are cross-sectional views showing a forming process using a forming tool. 
         FIGS.  4 A and  4 B  are cross-sectional views showing a forming process using the forming tool. 
         FIGS.  5 A and  5 B  are cross-sectional views showing a forming process using the forming tool. 
         FIGS.  6 A and  6 B  are cross-sectional views showing a forming process using the forming tool. 
         FIGS.  7 A and  7 B  are cross-sectional views showing a forming process using the forming tool. 
         FIGS.  8 A and  8 B  are cross-sectional views showing a forming process using the forming tool. 
         FIGS.  9 A to  9 C  are schematic views showing states of bending of the metal pipe material and a metal pipe. 
     
    
    
     DETAILED DESCRIPTION 
     In the forming device such as the related art described above, there is a case where the metal pipe having a flange is formed by crushing both sides of the metal pipe material in a width direction with the upper die and the lower die. However, such a forming device has a problem in that it is difficult to forma flange portion to a desired size because when the flange portion is expanding in the width direction, the expansion cannot be regulated. 
     It is desirable to provide a forming device capable of reducing variation in size of a flange portion, and a metal pipe in which the variation in size of the flange portion is reduced. 
     In the forming device, the forming tool includes the first die and the second die that face each other in the first direction in a cross-sectional view. In addition, the forming tool includes the third die for regulating the planned flange portion of the metal pipe. The third die continues to correct the misalignment of the planned flange portion until the first die and the second die are clamped. Therefore, even in a state in which a die closing operation of the first die and the second die progresses so that crushing of the planned flange portion progresses, the third die can continue to correct the misalignment of the planned flange portion. As described above, it is possible to reduce the variation in size of the flange portion after completion. 
     The third die may be disposed on at least one side of the metal pipe material in a second direction intersecting the first direction, and the third die may move away from the metal pipe material as the first die and the second die approach each other. The third die can restrict the flange portion of the metal pipe material, which is crushed by the first die and the second die, from expanding excessively in the second direction. Here, the third die moves away from the metal pipe material as the first die and the second die approach each other. Therefore, even in a state in which a die closing operation of the first die and the second die progresses so that crushing of the flange portion progresses, the third die can continue to regulate the flange portion. As described above, it is possible to reduce the variation in size of the flange portion. 
     The third die may move away from the metal pipe material as the first die and the second die approach each other by a tapered structure formed with at least one of the first die and the second die. In this case, the third die can be kept away from the metal pipe material with a simple structure. 
     The forming tool may form the metal pipe which is curved when viewed from the first direction. In this case, the size of the flange portion tends to vary between an inner peripheral side and an outer peripheral side of the curve, but the variation can be reduced by adopting the configuration of the present invention. 
     The metal pipe may include flange portions on both sides in a second direction intersecting the first direction, and the forming tool may include a pair of the third dies disposed on both sides of the metal pipe material in the second direction. In this case, it is possible to reduce the variation in size of the flange portions on both sides of the metal pipe. 
     Each of the pair of the third dies may be disposed such that the flange portions on both sides have the same size in the second direction. In this case, the flange portions on both sides of the metal pipe can have the same size. 
     Each of the pair of the third dies may be disposed such that sizes of the flange portions on both sides in the second direction are predetermined sizes different from each other. In this case, each of the flange portions on both sides of the metal pipe can have a desired size. 
     The forming device may further include a fluid supply unit that supplies a fluid to the metal pipe material that is heated. The size of the flange portion of the heated metal pipe material tends to vary due to variation in temperature or the like, but the variation can be reduced by adopting the configuration of the present invention. 
     The forming device may further include an elastic mechanism that applies an elastic force to the third die toward the metal pipe material in a second direction intersecting the first direction. In this case, when the first die and the second die are opened, the third die can be returned to its original position without providing an expensive actuator or the like. 
     In the metal pipe, the sizes of the pair of flange portions in the width direction are predetermined sizes different from each other. In this case, since processing is performed such that each flange portion has a predetermined size during forming, it is possible to reduce the variation in size of the flange portion. 
     In the forming device, the forming tool includes the first die and the second die that face each other in the first direction in a cross-sectional view. In addition, the forming tool includes the third die disposed on at least one side of the metal pipe material in a second direction intersecting the first direction. The third die can restrict the flange portion of the metal pipe material, which is crushed by the first die and the second die, from expanding excessively in the second direction. Here, the third die moves away from the metal pipe material as the first die and the second die approach each other. Therefore, even in a state in which a die closing operation of the first die and the second die progresses so that crushing of the flange portion progresses, the third die can continue to regulate the flange portion. As described above, it is possible to reduce the variation in size of the flange portion. 
     Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, in the respective drawings, the same portions or corresponding portions are designated by the same reference signs, and duplicated descriptions will be omitted. 
       FIG.  1    is a schematic view of a forming device  1  according to the present embodiment. As shown in  FIG.  1   , the forming device  1  is an apparatus that forms a metal pipe having a hollow shape by blow forming. In the present embodiment, the forming device  1  is installed on a horizontal plane. The forming device  1  includes a forming tool  2  (forming die), a drive mechanism  3 , a holding unit  4 , a heating unit  5 , a fluid supply unit  6 , a cooling unit  7 , and a control unit  8 . In addition, in the present specification, the metal pipe refers to a hollow article after completion of forming in the forming device  1 , and a metal pipe material  40  refers to a hollow article before completion of forming in the forming device  1 . The metal pipe material  40  is a steel type pipe material that can be hardened. In addition, in the horizontal direction, a direction in which the metal pipe material  40  extends during forming is sometimes referred to as a “longitudinal direction”, and a direction orthogonal to the longitudinal direction is sometimes referred to as a “width direction (second direction)”. 
     The forming tool  2  is a die for forming the metal pipe material  40  into the metal pipe and includes a lower die  11  (first die) and an upper die  12  (second die) facing each other in a vertical direction (first direction). In addition, the forming tool  2  includes a pair of lateral dies  14  and  15  (third dies) facing each other in the width direction (refer to  FIGS.  3 A and  3 B ) . Detailed shapes and the like of the dies  11 ,  12 ,  14 , and  15  will be described later. The lower die  11  and the upper die  12  are made of steel blocks. The lower die  11  is fixed to a base stage  13  via a die holder or the like. The upper die  12  is fixed to a slide of the drive mechanism  3  via a die holder or the like. 
     The drive mechanism  3  is a mechanism that moves at least one of the lower die  11  and the upper die  12 . In  FIG.  1   , the drive mechanism  3  has a configuration in which only the upper die  12  is moved. The drive mechanism  3  includes a slide  21  that moves the upper die  12  such that the lower die  11  and the upper die  12  are joined together, and a pull-back cylinder  22  serving as an actuator that generates a force for pulling the slide  21  upward, a main cylinder  23  serving as a drive source that downward-pressurizes the slide  21 , and a drive source  24  that applies a driving force to the main cylinder  23 . 
     The holding unit  4  is a mechanism that holds the metal pipe material  40  disposed between the lower die  11  and the upper die  12 . The holding unit  4  includes a lower electrode  26  and an upper electrode  27  that hold the metal pipe material  40  on one end side in the longitudinal direction of the forming tool  2 , and a lower electrode  26  and an upper electrode  27  that holds the metal pipe material  40  on the other end side in the longitudinal direction of the forming tool  2 . The lower electrodes  26  and the upper electrodes  27  on both sides in the longitudinal direction hold the metal pipe material  40  by sandwiching vicinities of the end portions of the metal pipe material  40  from the vertical direction. In addition, groove portions having a shape corresponding to an outer peripheral surface of the metal pipe material  40  are formed on an upper surface of the lower electrode  26  and a lower surface of the upper electrode  27 . The lower electrode  26  and the upper electrode  27  are provided with drive mechanisms (not shown) and are movable independently in the vertical direction. 
     The heating unit  5  heats the metal pipe material  40 . The heating unit  5  is a mechanism that heats the metal pipe material  40  by energizing the metal pipe material  40 . The heating unit  5  heats the metal pipe material  40  in a state in which the metal pipe material  40  is spaced apart from the lower die  11  and the upper die  12  between the lower die  11  and the upper die  12 . The heating unit  5  includes the lower electrodes  26  and the upper electrodes  27  on both sides in the longitudinal direction as described above, and a power supply  28  that causes an electric current to flow to the metal pipe material through the electrodes  26  and  27 . In addition, the heating unit  5  may be disposed in a preceding process of the forming device  1  and may perform heating externally. 
     The fluid supply unit  6  is a mechanism that supplies a high-pressure fluid into the metal pipe material  40  held between the lower die  11  and the upper die  12 . The fluid supply unit  6  supplies the high-pressure fluid into the metal pipe material  40  that has been brought into a high-temperature state by being heated by the heating unit  5  and expands the metal pipe material  40 . The fluid supply unit  6  is provided on both end sides of the forming tool  2  in the longitudinal direction. The fluid supply unit  6  includes a nozzle  31  that supplies a fluid from an opening portion of an end portion of the metal pipe material  40  to the inside of the metal pipe material  40 , a drive mechanism  32  that moves the nozzle  31  forward and backward with respect to the opening portion of the metal pipe material  40 , and a supply source  33  that supplies the high-pressure fluid into the metal pipe material  40  via the nozzle  31 . The drive mechanism  32  brings the nozzle  31  into close contact with the end portion of the metal pipe material  40  in a state in which a sealing property is secured at the time of supply and exhaust of the fluid (refer to  FIG.  2   ) and at other times, separates the nozzle  31  from the end portion of the metal pipe material  40 . In addition, the fluid supply unit  6  may supply a gas such as high-pressure air or an inert gas as the fluid. Additionally, the fluid supply unit  6  may include the heating unit  5  together with the holding unit  4  having a mechanism that moves the metal pipe material  40  in the vertical direction as the same device. 
       FIG.  2    is a cross-sectional view showing a state in which the nozzle  31  seals the metal pipe material  40 . As shown in  FIG.  2   , the nozzle  31  is a cylindrical member into which the end portion of the metal pipe material  40  can be inserted. The nozzle  31  is supported by the drive mechanism  32  such that a center line of the nozzle  31  coincides with a reference line SL 1 . An inner diameter of a supply port  31   a  at an end portion of the nozzle  31  on the side of the metal pipe material  40  substantially coincides with an outer diameter of the metal pipe material  40  after expansion forming. In this state, the nozzle  31  supplies the high-pressure fluid to the metal pipe material  40  from an internal flow path  36 . Examples of the high-pressure fluid include a gas and the like. 
     Returning to  FIG.  1   , the cooling unit  7  is a mechanism for cooling the forming tool  2 . By cooling the forming tool  2 , the cooling unit  7  can rapidly cool the metal pipe material  40  when the expanded metal pipe material  40  has come into contact with a forming surface of the forming tool  2 . The cooling unit  7  includes the flow path  36  formed inside the lower die  11  and the upper die  12 , and a water circulation mechanism  37  that supplies cooling water to the flow path  36  and circulates the cooling water. 
     The control unit  8  is a device that controls the entire forming device  1 . The control unit  8  controls the drive mechanism  3 , the holding unit  4 , the heating unit  5 , the fluid supply unit  6 , and the cooling unit  7 . The control unit  8  repeatedly performs an operation of forming the metal pipe material  40  with the forming tool  2 . 
     Specifically, the control unit  8  controls, for example, a transport timing from a transport device such as a robot arm to dispose the metal pipe material  40  between the lower die  11  and the upper die  12  in an open state. Alternatively, the control unit  8  may wait for a worker to manually dispose the metal pipe material  40  between the lower die  11  and the upper die  12 . Additionally, the control unit  8  controls an actuator of the holding unit  4  and the like such that the metal pipe material  40  is supported by the lower electrodes  26  on both sides in the longitudinal direction, and then the upper electrodes  27  are lowered to sandwich the metal pipe material  40 . Additionally, the control unit  8  controls the heating unit  5  to energize and heat the metal pipe material  40 . Accordingly, an axial electric current flows through the metal pipe material  40 , and an electric resistance of the metal pipe material  40  itself causes the metal pipe material  40  itself to generate heat due to Joule heat. 
     The control unit  8  controls the drive mechanism  3  to lower the upper die  12  and bring the upper die  12  close to the lower die  11  to close the forming tool  2 . On the other hand, the control unit  8  controls the fluid supply unit  6  to seal the opening portions of both ends of the metal pipe material  40  with the nozzle  31  and supply the fluid. Accordingly, the metal pipe material  40  softened by heating expands and comes into contact with the forming surface of the forming tool  2 . Then, the metal pipe material  40  is formed so as to follow a shape of the forming surface of the forming tool  2 . When the metal pipe material  40  comes into contact with the forming surface, hardening of the metal pipe material  40  is performed by being quenched with the forming tool  2  cooled by the cooling unit  7 . 
     A detailed configuration of the forming tool  2  of the forming device  1  will be described with reference to  FIGS.  3 A and  3 B  and  FIGS.  4 A and  4 B . First, a metal pipe  41  formed by the forming tool  2  will be described with reference to  FIG.  4 B . The metal pipe  41  includes a hollow pipe portion  41   a  and flange portions  41   b  and  41   c  protruding to both sides in the width direction. The pipe portion  41   a  has a rectangular tubular shape. However, a shape of the pipe portion  41   a  is not particularly limited and may be any shape depending on applications. The flange portions  41   b  and  41   c  are formed by crushing both end portions of the metal pipe material  40  in the width direction with the dies  11  and  12 . In the metal pipe material  40 , locations that are planned to become the flange portions  41   b  and  41   c  after completion are referred to as planned flange portions  40   b  and  40   c  ( FIG.  4 A ). Also in the following description, unless otherwise specified, a protrusion portion in the metal pipe  41  after completion of forming is referred to as a “flange portion”. Further, in the metal pipe material  40  in a state before the completion of forming, a location planned to become the flange portion after the completion is referred to as a “planned flange portion”. A shape of the “planned flange portion” changes depending on the degree of progress of forming. Further, as shown in  FIG.  9 A , the metal pipe  41  is curved so as to protrude to one side in the width direction when viewed from the vertical direction. In an example shown in  FIG.  9 A , the flange portion  41   b  is disposed on an inner peripheral side and the flange portion  41   c  is disposed on an outer peripheral side. 
     As shown in  FIG.  3 A , the lower die  11  includes a planar portion  51  expanding in the width direction, a recessed portion  52  formed at a center position in the width direction of the planar portion  51 , and support portions  53  and  54  formed at both outer end portions in the width direction. The recessed portion  52  is a portion that forms a lower portion of the pipe portion  41   a  of the metal pipe  41  (refer to  FIG.  4 B ). In the planar portion  51 , both sides of the recessed portion  52  in the width direction are configured as forming surfaces for forming the flange portions  41   b  and  41   c  (refer to  FIG.  4 B ). The support portions  53  and  54  are portions that protrude upward from the planar portion  51 . The support portion  53  is a portion that supports the lateral die  14 , and the support portion  54  is a portion that supports the lateral die  15 . 
     The upper die  12  includes a planar portion  61  expanding in the width direction and a forming body portion  62  protruding downward at a center position of the planar portion  61  in the width direction. The forming body portion  62  has a substantially trapezoidal cross-sectional shape that narrows downward. The forming body portion  62  includes a recessed portion  63  on a lower surface  62   a.  The recessed portion  63  is a portion that forms an upper portion of the pipe portion  41   a  of the metal pipe  41  (refer to  FIG.  4 B ). The lower surface  62   a  of the forming body portion  62  is configured as forming surfaces for forming the flange portions  41   b  and  41   c  on both sides of the recessed portion  63  in the width direction (refer to  FIG.  4 B ). The forming body portion  62  includes tapered surfaces  62   b  and  62   c  that expand outward in the width direction from the lower surface  62   a  toward the planar portion  61  located above. 
     The lateral die  14  is disposed on one side of the metal pipe material  40  in the width direction. The lateral die  15  is disposed on the other side of the metal pipe material  40  in the width direction. The dies  14  and  15  are dies that, when the planned flange portions  40   b  and  40   c  of the metal pipe material  40  are expanding outward in the width direction, regulate the expansion of the planned flange portions  40   b  and  40   c.  The dies  14  and  15  include regulation surfaces  14   a  and  15   a  that regulate the expansion of the planned flange portions  40   b  and  40   c  on an inner side in the width direction. On an upper side of the regulation surfaces  14   a  and  15   a,  tapered surfaces  14   b  and  15   b  which are inclined so as to expand outward in the width direction toward an upward direction are formed. 
     The die  14  is connected to a gas damper  66  (elastic mechanism) provided in the support portion  53  of the die  11 . The gas damper  66  extends inward in the width direction from the support portion  53  and is connected to the die  14 . The die  15  is connected to a gas damper  67  (elastic mechanism) provided in the support portion  54  of the die  11 . The gas damper  67  extends inward in the width direction from the support portion  54  and is connected to the die  15 . The gas dampers  66  and  67  are elastic mechanisms that apply elastic forces to the dies  14  and  15  to a side of the metal pipe material  40  in the width direction, that is, inward. 
     Here, the dies  14  and  15  are configured so as to be moved away from the metal pipe material  40  as the lower die  11  and the upper die  12  approach each other. In the present embodiment, as the upper die  12  is lowered, the dies  14  and  15  move outward in the width direction. Specifically, the dies  14  and  15  move outward in the width direction so as to be moved away from the metal pipe material  40  as the die  11  and the die  12  approach each other by tapered structures  71  and  72  formed with the upper die  12 . 
     Next, a procedure for forming with the forming tool  2  will be described. As shown in  FIG.  3 A , in an initial forming state, the dies  11 ,  12 ,  14 , and  15  are disposed at positions separated from the metal pipe material  40 . Here, in the present embodiment, the dies  14  and  15  are disposed such that the flange portions  41   b  and  41   c  on both sides (refer to  FIG.  4 B ) have the same size in the width direction. Specifically, the dies  14  and  15  are disposed at positions symmetrical with respect to a center position of the forming tool  2  in the width direction. Accordingly, the regulation surfaces  14   a  and  15   a  inside the dies  14  and  15  in the width direction are disposed at the same distance with respect to the center position of the forming tool  2  in the width direction. The control unit  8  heats the metal pipe material  40  in this state. 
     Next, as shown in  FIG.  3 B , the control unit  8  lowers the die  12  downward. Here, the die  12  is lowered to a position where the tapered surfaces  62   b  and  62   c  of the die  12  come into contact with the tapered surfaces  14   b  and  15   b  of the dies  14  and  15 . In addition, the control unit  8  controls the fluid supply unit  6  to supply the fluid into the metal pipe material  40  to perform blow forming (primary blowing). The portions of the planned flange portions  40   b  and  40   c  on both sides of the metal pipe material  40  in the width direction expand so as to enter between the planar portion  51  of the die  11  and the lower surface  62   a  of the die  12 . At this time, the planned flange portions  40   b  and  40   c  come into contact with the regulation surfaces  14   a  and  15   a  of the dies  14  and  15 , so that further outward deformation in the width direction is restricted. In this way, in a state in which the dies  14  and  15  regulate the planned flange portions  40   b  and  40   c  with the regulation surfaces  14   a  and  15   a,  misalignment of the planned flange portions  40   b  and  40   c  can be corrected. 
     Next, as shown in  FIG.  4 A , the control unit  8  further lowers the die  12 . At this time, the tapered surfaces  62   b  and  62   c  of the die  12  also move downward. Then, the tapered surfaces  14   b  and  15   b  of the dies  14  and  15  are guided by the tapered surfaces  62   b  and  62   c  of the die  12 , and thus move outward in the width direction. Therefore, the regulation surfaces  14   a  and  15   a  of the dies  14  and  15  also move outward in the width direction. The dies  14  and  15  are maintained in a state of being pressed against the tapered surfaces  62   b  and  62   c  of the die  12  by the elastic forces of the gas dampers  66  and  67 . 
     On the other hand, the planned flange portions  40   b  and  40   c  of the metal pipe material  40  are further crushed between the planar portion  51  of the die  11  and the lower surface  62   a  of the die  12 , so that dimensions thereof in the width direction gradually increase with lowering of the die  12 . However, even when the planned flange portions  40   b  and  40   c  try to largely protrude outward in the width direction due to variation, they are regulated by the regulation surfaces  14   a  and  15   a  of the dies  14  and  15  and do not become larger than that. In this way, even in a state in which the dies  14  and  15  are not in contact with the planned flange portions  40   b  and  40   c,  a state in which the planned flange portions  40   b  and  40   c  (the planned flange portions  40   b  and  40   c  trying to largely protrude) are regulated with the regulation surfaces  14   a  and  15   a  can be said to be a state in which the misalignment of the planned flange portions  40   b  and  40   c  is corrected. 
     The control unit  8  further lowers the die  12  so that the dies  11  and  12  are completely closed as shown in  FIG.  4 B  (bottom dead point). At this time, the planned flange portions  40   b  and  40   c  are completely crushed to complete flange portions  41   b  and  41   c . In this state, the control unit  8  completes the metal pipe  41  by forming the pipe portion  41   a  corresponding to the shapes of recessed portions  52  and  63  by sharing the fluid to the metal pipe material  40  by the fluid supply unit  6 . Thereafter, when the control unit  8  moves the die  12  upward to open the dies, the dies  14  and  15  return to positions shown in  FIG.  3 A  due to restoring forces of the gas dampers  66  and  67 . Here, a state in which the dies  11  and  12  are completely closed corresponds to a state in which the dies  11  and  12  are clamped. The dies  14  and  15  continue to correct the misalignment of the planned flange portions  40   b  and  40   c  until the dies are clamped. 
     Next, operations and effects of the forming device  1  according to the present embodiment will be described. 
     In the forming device  1 , the forming tool  2  includes the dies  11  and  12  facing each other in the vertical direction (first direction) in a cross-sectional view. In addition, the forming tool  2  includes the dies  14  and  15  disposed on both sides of the metal pipe material  40  in the width direction (second direction) intersecting the vertical direction. The dies  14  and  15  can restrict the planned flange portions  40   b  and  40   c  of the metal pipe material  40 , which are crushed by the dies  11  and  12 , from expanding excessively in the width direction. Here, the dies  14  and  15  move away from the metal pipe material  40  as the die  11  and the die  12  approach each other. Therefore, even in a state in which a die closing operation of the die  11  and the die  12  progresses so that crushing of the planned flange portions  40   b  and  40   c  progresses, the dies  14  and  15  can continue to regulate the planned flange portions  40   b  and  40   c.  As described above, it is possible to reduce the variation in size of the flange portions  41   b  and  41   c  after completion. 
     The dies  14  and  15  move away from the metal pipe material  40  as the die  11  and the die  12  approach each other by the tapered structures  71  and  72  formed with the upper die  12 . In this case, the dies  14  and  15  can be kept away from the metal pipe material  40  by a simple structure in which only the tapered structures  71  and  72  are provided. 
     The metal pipe  41  includes the flange portions  41   b  and  41   c  on both sides in the width direction, and the forming tool  2  includes the pair of dies  14  and  15  disposed on both sides of the metal pipe material  40  in the width direction. In this case, it is possible to reduce variation in size of the flange portions  41   b  and  41   c  on both sides of the metal pipe  41 . 
     The forming device  1  further includes the gas dampers  66  and  67  that apply elastic forces to the dies  14  and  15  to a side of the metal pipe material  40  in the width direction. In this case, the dies  14  and  15  can be returned to their original positions when the dies  11  and  12  are opened without providing an expensive actuator or the like. 
     Each of the pair of dies  14  and  15  is disposed such that the flange portions  41   b  and  41   c  on both sides have the same size in the width direction. In this case, the flange portions  41   b  and  41   c  on both sides of the metal pipe  41  can have the same size. 
     The forming tool  2  forms the metal pipe  41  which is curved when viewed from the vertical direction. In this case, the sizes of the flange portions  41   b  and  41   c  tend to vary between an inner peripheral side and an outer peripheral side of the curve, but the variation can be reduced by adopting the configuration of the present embodiment. 
     The forming device  1  further includes the fluid supply unit  6  that supplies a fluid to the heated metal pipe material  40 . The sizes of the flange portions  41   b  and  41   c  of the heated metal pipe material  40  tend to vary due to variation in temperature or the like, but the variation can be reduced by adopting the configuration of the present embodiment. 
     A relationship between bending and a temperature of the metal pipe  41  (metal pipe material  40 ) will be described in more detail. As shown in  FIG.  9 A , when the metal pipe material  40  is electrically heated, a current density is higher on an inner peripheral side than on an outer peripheral side, and the temperature is higher on the inner peripheral side, so that a heating temperature difference occurs. Then, an amount of thermal expansion of the metal pipe material  40  is larger on the inner peripheral side than on the outer peripheral side. Further, as shown in  FIG.  9 B , when the dies  11  and  12  are closed to form the flange portions  41   b  and  41   c,  a compressive force acts on the inner peripheral side and a tensile force acts on the outer peripheral side. As a result, the flange portion  41   b  on the inner peripheral side is in a state of excess material. Therefore, as shown in  FIG.  9 C , the metal pipe  41  is deformed to reduce a bending angle due to influences of expansion and contraction in the longitudinal direction and a difference in the amount of thermal expansion, and a center of the pipe tends to shift to the outer peripheral side. Therefore, in a case where the dies  14  and  15  as in the present embodiment are not provided, the size of the flange portion  41   b  on the inner peripheral side tends to be larger in the width direction. On the other hand, in the forming device  1  according to the present embodiment, since the variation of the flange portions  41   b  and  41   c  can be reduced by the dies  14  and  15 , the size of the flange portion  41   b  on the inner peripheral side and the size of the flange portion  41   c  on the outer peripheral side can be made uniform. In addition, by appropriately adjusting operations of the dies  14  and  15 , it is possible to improve a degree of freedom in forming a corner R of the metal pipe  41  having a complicated shape. 
     In the forming device  1 , the dies  14  and  15  continue to correct the misalignment of the planned flange portions  40   b  and  40   c  until the die  11  and the die  12  are clamped. Therefore, even in a state in which a die closing operation of the dies  11  and  12  progresses so that crushing of the planned flange portions  40   b  and  40   c  progresses, the dies  14  and  15  can continue to correct the misalignment of the planned flange portions  40   b  and  40   c.  As described above, it is possible to reduce the variation in size of the flange portions  41   b  and  41   c  after completion. 
     The present invention is not limited to the above-described embodiment. 
     For example, in the above-described embodiment, the dies  14  and  15  are disposed such that the size of the flange portion  41   b  in the width direction and the size of the flange portion  41   c  in the width direction are the same. Alternatively, each of the pair of dies  14  and  15  may be disposed such that the sizes of the flange portions  41   b  and  41   c  on both sides in the width direction are predetermined sizes different from each other. In this case, each of the flange portions  41   b  and  41   c  on both sides of the metal pipe  41  can have a desired size. 
     For example, as shown in  FIG.  6 B , the flange portion  41   b  may be formed to be larger than the flange portion  41   c.  In this case, as shown in  FIG.  5 A , in an initial state, the regulation surface  14   a  of the die  14  may be disposed farther from the center position of the forming tool  2  in the width direction than the regulation surface  15   a  of the die  15  is. In this case, as shown in  FIG.  5 B , at a stage of performing primary blowing, the planned flange portion  40   c  comes into contact with the regulation surface  15   a,  while the planned flange portion  40   b  is in a state of being separated from the regulation surface  14   a.  Therefore, the planned flange portion  40   c  can expand while being regulated by the regulation surface  15   a,  while the planned flange portion  40   b  can expand without being regulated. As shown in  FIG.  6 A , when the control unit  8  further moves the die  12  downward, the die  15  moves outward, while the die  14  does not move until the die  14  comes into contact with the tapered surface  62   b.  On the other hand, the planned flange portion  40   b  is crushed and expands outward to come into contact with the regulation surface  14   a.  Accordingly, the planned flange portion  40   b  is regulated by the regulation surface  14   a.  The control unit  8  further moves the die  12  downward, so that the flange portions  41   b  and  41   c  are completed as shown in  FIG.  6 B . 
     As described above, the metal pipe  41  shown in  FIG.  6 B  includes the hollow pipe portion  41   a  and the pair of flange portions  41   b  and  41   c  protruding from the pipe portion  41   a  to both sides in the width direction, and the sizes of the pair of flange portions  41   b  and  41   c  in the width direction are predetermined sizes different from each other. 
     In the metal pipe  41 , the sizes of the pair of flange portions  41   b  and  41   c  in the width direction are predetermined sizes different from each other. In this case, since processing is performed such that each of the flange portions  41   b  and  41   c  has a predetermined size during forming, it is possible to reduce the variation in size of the flange portions  41   b  and  41   c.    
     Also in the embodiment shown in  FIGS.  5 A and  5 B  and  FIGS.  6 A and  6 B , the dies  14  and  15  continue to correct the misalignment of the planned flange portions  40   b  and  40   c  until the die  11  and the die  12  are clamped ( FIG.  6 B ). 
     In the above-described embodiment, the metal pipe  41  includes the pair of flange portions  41   b  and  41   c.  Alternatively, the metal pipe  41  may have a flange portion on only one side in the width direction. For example, as shown in  FIG.  8 B , the metal pipe  41  may have only the flange portion  41   b  on one side. In this case, as shown in  FIG.  7 A , in the initial state, the regulation surface  14   a  of the die  14  may be disposed farther from the center position of the forming tool  2  in the width direction than the regulation surface  15   a  of the die  15  is. Further, the recessed portions  52  and  63  are formed so as to be shifted to the right side of the center position. In this case, the regulation surface  15   a  is disposed at a position of right end portions of the recessed portions  52  and  63 . In this case, as shown in  FIG.  7 B , at a stage of performing primary blowing, the planned flange portion  40   b  comes into contact with the regulation surface  14   a,  while a right end portion of a pipe portion  40   a  comes into contact with the regulation surface  15   a.  Therefore, the planned flange portion is not formed on the right side. As shown in  FIG.  8 A , when the control unit  8  further moves the die  12  downward, the dies  14  and  15  move outward. A state in which the planned flange portion is not formed on the right side of the pipe portion  40   a  is continued. The control unit  8  further moves the die  12  downward, so that the flange portion  41   b  is completed as shown in  FIG.  8 B . 
     Also in the embodiment shown in  FIGS.  7 A and  7 B  and  FIGS.  8 A and  8 B , the die  14  continues to correct the misalignment of the planned flange portion  40   b  until the die  11  and the die  12  are clamped ( FIG.  8 B ). 
     In the above-described embodiment, the dies for regulation are provided on both sides in the width direction, but may be provided only on one side in the width direction. 
     In the above-described embodiment, the tapered structures  71  and  72  are formed between the dies  14  and  15  and the upper die  12 . Alternatively, the tapered structures may be formed between the dies  14  and  15  and the lower die  11  or may be formed between the dies  14  and  15  and both the dies  11  and  12 . 
     In the above-described embodiment, the gas damper is adopted as the elastic mechanism, but the elastic mechanism may be anything that generates an elastic force and may be formed of an elastic member or the like. In addition, the dies  14  and  15  may have a configuration in which positions thereof in the width direction can be controlled by an actuator or the like. 
     In the above-described embodiment, the description has been made by using the forming tool adopted in the forming device for STAF as an example. However, the type of the forming device in which the forming tool according to the present invention is adopted is not particularly limited, and may be any type of the forming device that supplies a fluid to expand the metal pipe material. 
     It should be understood that the invention is not limited to the above-described embodiment, but maybe modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.