Forming device

Abstract

A molding device that: molds a metal pipe having a flange; and comprises a molding die that molds the metal pipe. The molding die has: a first die and a second die that are mutually facing in a first direction, in a cross-sectional view; and a third die for restricting a planned flange section of the metal pipe material. The third die continues to correct displacement of the planned flange section, until clamping by the first die and the second die.

Description

Forming device and metal pipe

[0001] The present invention relates to a forming device and a metal pipe.

[0002] Conventionally, forming apparatuses used for forming metal pipes have been known. For example, Patent Document 1 listed below discloses a forming apparatus including a forming die having a pair of lower and upper dies, and a fluid supply unit that supplies a fluid into a metal pipe material held between the forming dies.

[0003] Japanese Patent Application Laid-Open No. 2009-220141

[0004] In some cases, the conventional forming apparatus described above forms a flanged metal pipe by compressing both widthwise sides of a metal pipe material with an upper die and a lower die. However, such forming apparatus cannot restrict the widthwise expansion of the flange portion, making it difficult to form the flange portion to a desired size.

[0005] The present invention has been made to solve such problems, and an object of the present invention is to provide a molding device that can reduce the variation in size of the flange portion, and a metal pipe in which the variation in size of the flange portion is reduced.

[0006] A molding apparatus according to one aspect of the present invention is a molding apparatus for molding a metal pipe with a flange, and includes a molding die for molding the metal pipe, the molding die having a first die and a second die facing each other in a first direction in a cross-sectional view, and a third die for regulating a flange-intended portion of the metal pipe material, and the third die continues to correct misalignment of the flange-intended portion until the first die and the second die are clamped together.

[0007] In the molding apparatus, the mold has a first mold and a second mold facing each other in a first direction in a cross-sectional view. The mold also has a third mold for regulating the flange portion of the metal pipe. This third mold continues to correct misalignment of the flange portion until the first mold and the second mold are clamped together. Therefore, the third mold can continue to correct misalignment of the flange portion even while the first mold and the second mold are closing and the flange portion is being crushed. As a result, variation in the size of the completed flange portion can be reduced.

[0008] The third die is disposed on at least one side of the 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. This third die can prevent the flange portion of the metal pipe material, which is crushed by the first die and the second die, from expanding too much 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, the third die can continue to restrict the flange portion even when the first die and the second die are closing and the flange portion is being crushed. As a result, variation in the size of the flange portion can be reduced.

[0009] The third die may be tapered at least one of between the third die and the first die and between the third die and the second die, so that the third die moves away from the metal pipe material as the first die and the second die approach each other. In this case, the third die can be moved away from the metal pipe material with a simple structure.

[0010] The forming die may form a metal pipe that is curved when viewed from a first direction. In this case, the size of the flange portion tends to vary between the inner and outer circumferential sides of the curve, but by adopting the configuration of the present invention, the variation can be reduced.

[0011] The metal pipe may have flange portions on both sides in a second direction intersecting the first direction, and the forming die may have a pair of third dies arranged on both sides of the metal pipe material in the second direction. In this case, it is possible to reduce variation in size of the flange portions on both sides of the metal pipe.

[0012] The pair of third dies may be arranged so 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.

[0013] The pair of third dies may be arranged so that the flange portions on both sides have different predetermined sizes in the second direction, in which case the flange portions on both sides of the metal pipe can have desired sizes.

[0014] The forming apparatus may further include a fluid supply unit that supplies a fluid to the heated metal pipe material. The heated metal pipe material is prone to variations in size of the flange portion due to temperature variations, but by adopting the configuration of the present invention, such variations can be reduced.

[0015] The molding device may further include an elastic mechanism that applies an elastic force to the third mold toward the metal pipe material in a second direction intersecting the first direction. In this case, the third mold can be returned to its original position when the first mold and the second mold are opened without providing an expensive actuator or the like.

[0016] A metal pipe according to one aspect of the present invention has a hollow pipe portion and a pair of flange portions protruding from the pipe portion on both sides in the width direction, and the width direction sizes of the pair of flange portions are different from each other and have predetermined sizes.

[0017] In the metal pipe, the widthwise sizes of the pair of flange portions are different from each other, and in this case, processing is performed during molding so that each flange portion has the predetermined size, thereby reducing the variation in the size of the flange portions.

[0018] A forming apparatus according to one aspect of the present invention is a forming apparatus for forming a flanged metal pipe, and includes a forming mold for forming the metal pipe, wherein the forming mold has a first mold and a second mold that face each other in a first direction in a cross-sectional view, and a third mold that is arranged on at least one side of the metal pipe material in a second direction that intersects the first direction, and the third mold moves away from the metal pipe material as the first mold and the second mold move closer to each other.

[0019] In the molding apparatus, the mold has a first mold and a second mold that face each other in a first direction in a cross-sectional view. The mold also has a third mold arranged on at least one side of the metal pipe material in a second direction intersecting the first direction. This third mold can prevent the flange portion of the metal pipe material, which is crushed between the first mold and the second mold, from expanding too much in the second direction. Here, the third mold moves away from the metal pipe material as the first mold and the second mold approach each other. Therefore, the third mold can continue to restrict the flange portion even when the first mold and the second mold are closing and the flange portion is being crushed. As a result, variation in the size of the flange portion can be reduced.

[0020] According to the present invention, it is possible to provide a forming device capable of reducing variations in the size of a flange portion, and a metal pipe in which variations in the size of a flange portion are reduced.

[0021] FIG. 1 is a schematic diagram 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 seals a metal pipe material. FIG. 3 is a cross-sectional view showing a state of forming using a forming die. FIG. 4 is a cross-sectional view showing a state of forming using a forming die. FIG. 5 is a cross-sectional view showing a state of forming using a forming die. FIG. 6 is a cross-sectional view showing a state of forming using a forming die. FIG. 7 is a cross-sectional view showing a state of forming using a forming die. FIG. 8 is a schematic diagram showing a state of bending of a metal pipe material and a metal pipe.

[0022] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicated explanations will be omitted.

[0023] FIG. 1 is a schematic diagram of a molding apparatus 1 according to this embodiment. As shown in FIG. 1, the molding apparatus 1 is an apparatus for molding a metal pipe having a hollow shape by blow molding. In this embodiment, the molding apparatus 1 is installed on a horizontal surface. The molding apparatus 1 includes a molding die 2 (molding 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 this specification, the metal pipe refers to a hollow article after molding in the molding apparatus 1 is completed, and the metal pipe material 40 refers to a hollow article before molding in the molding apparatus 1 is completed. The metal pipe material 40 is a pipe material made of a steel type that can be hardened. In addition, among the horizontal directions, the direction in which the metal pipe material 40 extends during molding is sometimes referred to as the "longitudinal direction," and the direction perpendicular to the longitudinal direction is sometimes referred to as the "width direction (second direction)."

[0024] The forming die 2 is a die for forming the metal pipe material 40 into a metal pipe, and includes a lower die 11 (first die) and an upper die 12 (second die) that face each other in the vertical direction (first direction). The forming die 2 also includes a pair of lateral dies 14, 15 (third die) that face each other in the width direction (see FIG. 3). The detailed shapes of the dies 11, 12, 14, 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 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.

[0025] The drive mechanism 3 is a mechanism that moves at least one of the lower mold 11 and the upper mold 12. In Fig. 1, the drive mechanism 3 is configured to move only the upper mold 12. The drive mechanism 3 includes a slide 21 that moves the upper mold 12 so that the lower mold 11 and the upper mold 12 are aligned with each other, a pull-back cylinder 22 as an actuator that generates a force that pulls the slide 21 upward, a main cylinder 23 as a drive source that pressurizes the slide 21 downward, and a drive source 24 that applies a drive force to the main cylinder 23.

[0026] The holding unit 4 is a mechanism for holding the metal pipe material 40 disposed between the lower mold 11 and the upper mold 12. The holding unit 4 includes a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 at one end of the molding die 2 in the longitudinal direction, and a lower electrode 26 and an upper electrode 27 that hold the metal pipe material 40 at the other end of the molding die 2 in the longitudinal direction. The lower electrode 26 and the upper electrode 27 on both sides in the longitudinal direction hold the metal pipe material 40 by sandwiching the vicinity of the end of the metal pipe material 40 from above and below. Grooves having a shape corresponding to the outer peripheral surface of the metal pipe material 40 are formed on the upper surface of the lower electrode 26 and the lower surface of the upper electrode 27. The lower electrode 26 and the upper electrode 27 are provided with drive mechanisms (not shown) that allow them to move independently in the vertical direction.

[0027] 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 passing electricity through the metal pipe material 40. The heating unit 5 heats the metal pipe material 40 between the lower mold 11 and the upper mold 12, while the metal pipe material 40 is spaced apart from the lower mold 11 and the upper mold 12. The heating unit 5 includes a lower electrode 26 and an upper electrode 27 on both sides of the longitudinal direction, and a power source 28 that applies current to the metal pipe material via these electrodes 26, 27. The heating unit 5 may be arranged in a pre-process of the molding device 1 and may be an external heating unit.

[0028] The fluid supply unit 6 is a mechanism for supplying high-pressure fluid into the metal pipe material 40 held between the lower mold 11 and the upper mold 12. The fluid supply unit 6 supplies high-pressure fluid to the metal pipe material 40, which has been heated in the heating unit 5 to a high temperature, to expand the metal pipe material 40. The fluid supply unit 6 is provided on both longitudinal ends of the molding die 2. The fluid supply unit 6 includes a nozzle 31 that supplies fluid into the metal pipe material 40 from an opening at the end of the metal pipe material 40, a drive mechanism 32 that moves the nozzle 31 toward and away from the opening of the metal pipe material 40, and a supply source 33 that supplies high-pressure fluid into the metal pipe material 40 through the nozzle 31. The drive mechanism 32 brings the nozzle 31 into close contact with the end of the metal pipe material 40 while ensuring a seal (see FIG. 2 ) during fluid supply and exhaust, and moves the nozzle 31 away from the end of the metal pipe material 40 at other times. The fluid supply unit 6 may supply a gas such as high-pressure air or an inert gas as the fluid. The fluid supply unit 6 may be integrated into the holding unit 4 having a mechanism for moving the metal pipe material 40 in the vertical direction, and may also be integrated into the heating unit 5.

[0029] FIG. 2 is a cross-sectional view showing the state when 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 of the metal pipe material 40 can be inserted. The nozzle 31 is supported by a drive mechanism 32 so that the center line of the nozzle 31 coincides with a reference line SL1. The inner diameter of the supply port 31a at the end of the nozzle 31 on the metal pipe material 40 side is approximately equal to the outer diameter of the metal pipe material 40 after expansion molding. In this state, the nozzle 31 supplies a high-pressure fluid from an internal flow path 36 to the metal pipe material 40. An example of the high-pressure fluid is gas.

[0030] 1 , the cooling unit 7 is a mechanism for cooling the molding die 2. By cooling the molding die 2, the cooling unit 7 can rapidly cool the expanded metal pipe material 40 when it comes into contact with the molding surface of the molding die 2. The cooling unit 7 includes flow paths 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 paths 36 and circulates the water.

[0031] The control unit 8 is a device that controls the entire molding 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 the operation of molding the metal pipe material 40 in the molding die 2.

[0032] Specifically, the control unit 8 controls the timing of transfer from a transfer device such as a robot arm to place the metal pipe material 40 between the open lower and upper dies 11 and 12. Alternatively, the control unit 8 may wait for an operator to manually place the metal pipe material 40 between the lower and upper dies 11 and 12. The control unit 8 also controls the actuators of the holding unit 4 to support the metal pipe material 40 with the lower electrodes 26 on both longitudinal sides, and then lower the upper electrode 27 to sandwich the metal pipe material 40. The control unit 8 also controls the heating unit 5 to electrically heat the metal pipe material 40. As a result, an axial current flows through the metal pipe material 40, and the metal pipe material 40 itself generates heat through Joule heat due to its own electrical resistance.

[0033] The control unit 8 controls the drive mechanism 3 to lower the upper die 12 and bring it close to the lower die 11, thereby closing the forming die 2. Meanwhile, the control unit 8 controls the fluid supply unit 6 to seal the openings at both ends of the metal pipe material 40 with the nozzle 31 and supply fluid. As a result, the metal pipe material 40, softened by heating, expands and comes into contact with the forming surface of the forming die 2. The metal pipe material 40 is then formed to fit the shape of the forming surface of the forming die 2. Once the metal pipe material 40 comes into contact with the forming surface, it is quenched by the forming die 2, which is cooled by the cooling unit 7, thereby quenching the metal pipe material 40.

[0034] The detailed configuration of the molding die 2 of the molding apparatus 1 will be described with reference to Figures 3 and 4. First, the metal pipe 41 molded by the molding die 2 will be described with reference to Figure 4(b). The metal pipe 41 has a hollow pipe portion 41a and flange portions 41b, 41c protruding on both sides in the width direction. The pipe portion 41a has a rectangular tubular shape. However, the shape of the pipe portion 41a is not particularly limited and may be any shape depending on the application. The flange portions 41b, 41c are formed by crushing both widthwise ends of the metal pipe material 40 with the dies 11, 12. Note that the portions of the metal pipe material 40 that will become the flange portions 41b, 41c after completion are referred to as flange portions 40b, 40c (Figure 4(a)). In the following description, unless otherwise noted, the protruding portions of the metal pipe 41 after completion will be referred to as the "flange portions." In addition, in the metal pipe material 40 in a state before the forming is completed, the portion intended to become the flange portion after completion is referred to as the "flange-intent portion." The shape of the "flange-intent portion" changes depending on the progress of the forming. Also, 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 top and bottom. In the example shown in FIG. 9( a), the flange portion 41b is located on the inner periphery side, and the flange portion 41c is located on the outer periphery side.

[0035] As shown in Fig. 3(a), the lower mold 11 includes a flat portion 51 extending in the width direction, a recessed portion 52 formed at the center of the flat portion 51 in the width direction, and support portions 53, 54 formed at both outer ends in the width direction. The recessed portion 52 is a portion for molding the lower portion of the pipe portion 41a of the metal pipe 41 (see Fig. 4(b)). Both sides of the recessed portion 52 in the width direction of the flat portion 51 are configured as molding surfaces for molding the flange portions 41b, 41c (see Fig. 4(b)). The support portions 53, 54 are portions that protrude upward from the flat portion 51. The support portion 53 is a portion for supporting the side mold 14, and the support portion 54 is a portion for supporting the side mold 15.

[0036] The upper mold 12 includes a flat portion 61 that extends in the width direction and a molding body portion 62 that protrudes downward from the center of the flat portion 61 in the width direction. The molding body portion 62 has a generally trapezoidal cross-sectional shape that tapers downward. The molding body portion 62 has a recess 63 on its lower surface 62a. The recess 63 is a portion that forms the upper portion of the pipe portion 41a of the metal pipe 41 (see FIG. 4(b)). The lower surface 62a of the molding body portion 62 is configured as a molding surface for forming the flange portions 41b, 41c on both sides of the recess 63 in the width direction (see FIG. 4(b)). The molding body portion 62 has tapered surfaces 62b, 62c that widen outward in the width direction from the lower surface 62a toward the upper flat portion 61.

[0037] The side die 14 is disposed on one side of the metal pipe material 40 in the width direction. The side die 15 is disposed on the other side of the metal pipe material 40 in the width direction. The dies 14, 15 are dies that restrict the expansion of the flange-prepared portions 40b, 40c of the metal pipe material 40 when the flange-prepared portions 40b, 40c expand outward in the width direction. The dies 14, 15 have restricting surfaces 14a, 15a on the inside in the width direction that restrict the expansion of the flange-prepared portions 40b, 40c. Tapered surfaces 14b, 15b that incline upward so as to expand outward in the width direction are formed on the upper sides of the restricting surfaces 14a, 15a.

[0038] The mold 14 is connected to a gas damper 66 (elastic mechanism) provided on the support portion 53 of the mold 11. The gas damper 66 extends inward in the width direction from the support portion 53 and is connected to the mold 14. The mold 15 is connected to a gas damper 67 (elastic mechanism) provided on the support portion 54 of the mold 11. The gas damper 67 extends inward in the width direction from the support portion 54 and is connected to the mold 15. The gas dampers 66, 67 are elastic mechanisms that apply elastic force to the molds 14, 15 toward the metal pipe material 40 in the width direction, i.e., inward.

[0039] Here, the dies 14, 15 are configured to move away from the metal pipe material 40 as the lower die 11 and the upper die 12 approach each other. In this embodiment, the dies 14, 15 move outward in the width direction as the upper die 12 descends. Specifically, due to the tapered structures 71, 72 formed between the dies 14, 15 and the upper die 12, the dies 14, 15 move outward in the width direction so as to move away from the metal pipe material 40 as the dies 11 and 12 approach each other.

[0040] Next, the molding procedure using the molding die 2 will be described. As shown in FIG. 3A, in the initial molding state, the dies 11, 12, 14, and 15 are positioned at a distance from the metal pipe material 40. In this embodiment, the dies 14 and 15 are positioned so that the flange portions 41b and 41c (see FIG. 4B) on both sides have the same widthwise size. Specifically, the dies 14 and 15 are positioned symmetrically with respect to the center position in the widthwise direction of the molding die 2. As a result, the inner regulating surfaces 14a and 15a in the widthwise direction of the dies 14 and 15 are positioned at the same distance from the center position in the widthwise direction of the molding die 2. The control unit 8 heats the metal pipe material 40 in this state.

[0041] Next, as shown in FIG. 3( b), the control unit 8 lowers the mold 12. Here, the mold 12 descends to a position where the tapered surfaces 62b, 62c of the mold 12 contact the tapered surfaces 14b, 15b of the molds 14, 15. The control unit 8 also controls the fluid supply unit 6 to supply fluid into the metal pipe material 40, thereby performing blow molding (primary blow molding). The flange portions 40b, 40c on both sides of the width direction of the metal pipe material 40 expand to enter between the flat surface 51 of the mold 11 and the lower surface 62a of the mold 12. At this time, the flange portions 40b, 40c contact the restricting surfaces 14a, 15a of the molds 14, 15, thereby restricting further outward deformation in the width direction. In this manner, when the restricting surfaces 14a, 15a of the molds 14, 15 restrict the flange portions 40b, 40c, misalignment of the flange portions 40b, 40c can be corrected.

[0042] Next, as shown in FIG. 4( a), the control unit 8 further lowers the mold 12. At this time, the tapered surfaces 62b, 62c of the mold 12 also move downward. Then, the tapered surfaces 14b, 15b of the molds 14, 15 are guided by the tapered surfaces 62b, 62c of the mold 12 and move outward in the width direction. Therefore, the restricting surfaces 14a, 15a of the molds 14, 15 also move outward in the width direction. The elastic forces of the gas dampers 66, 67 keep the molds 14, 15 pressed against the tapered surfaces 62b, 62c of the mold 12.

[0043] Meanwhile, the flange portions 40b, 40c of the metal pipe material 40 are further crushed between the flat surface 51 of the die 11 and the lower surface 62a of the die 12, and as a result, the widthwise dimension gradually increases as the die 12 descends. However, even if the flange portions 40b, 40c attempt to protrude significantly outward in the widthwise direction due to variations, they are restricted by the restricting surfaces 14a, 15a of the dies 14, 15 and do not increase any further. In this way, even when the dies 14, 15 are not in contact with the flange portions 40b, 40c, the restricting surfaces 14a, 15a restrict the flange portions 40b, 40c (the flange portions 40b, 40c attempting to protrude significantly) and this state can be said to correct the misalignment of the flange portions 40b, 40c.

[0044] The control unit 8 further lowers the mold 12 until the molds 11 and 12 are completely closed (bottom dead center) as shown in FIG. 4( b). At this time, the flange portions 40b and 40c are completely crushed, resulting in completed flange portions 41b and 41c. In this state, the control unit 8 applies fluid to the metal pipe material 40 using the fluid supply unit 6 to form the pipe portion 41a corresponding to the shape of the recesses 52 and 63, thereby completing the metal pipe 41. After this, the control unit 8 moves the mold 12 upward to open it, and the molds 14 and 15 return to the position shown in FIG. 3( a) due to the restoring forces of the gas dampers 66 and 67. Here, the completely closed state of the molds 11 and 12 corresponds to the state in which the molds 11 and 12 have been clamped. The molds 14 and 15 continue to correct any misalignment of the flange portions 40b and 40c until they are clamped.

[0045] Next, the operation and effects of the molding device 1 according to this embodiment will be described.

[0046] In the molding apparatus 1, the molding die 2 has dies 11 and 12 that face each other in the vertical direction (first direction) in a cross-sectional view. The molding die 2 also has dies 14 and 15 arranged on both sides of the metal pipe material 40 in the width direction (second direction) intersecting the vertical direction. These dies 14 and 15 can prevent the flange portions 40b and 40c 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 dies 11 and 12 approach each other. Therefore, the dies 14 and 15 can continue to restrict the flange portions 40b and 40c even when the dies 11 and 12 are closing and the flange portions 40b and 40c are being crushed. As a result, the variation in size of the flange portions 40b and 40c after completion can be reduced.

[0047] Due to the tapered structures 71, 72 formed between the upper die 12 and the dies 14, 15, as the dies 11, 12 approach each other, the dies 14, 15 move away from the metal pipe material 40. In this case, the dies 14, 15 can be moved away from the metal pipe material 40 with a simple structure in which only the tapered structures 71, 72 are provided.

[0048] The metal pipe 41 has flanges 41b, 41c on both sides in the width direction, and the molding die 2 has a pair of dies 14, 15 arranged on both sides in the width direction of the metal pipe material 40. In this case, it is possible to reduce variation in size of the flanges 41b, 41c on both sides of the metal pipe 41.

[0049] The molding device 1 further includes gas dampers 66, 67 that apply elastic force to the dies 14, 15 toward the metal pipe material 40 in the width direction. In this case, the dies 14, 15 can be returned to their original positions when the dies 11, 12 are opened without providing an expensive actuator or the like.

[0050] The pair of molds 14, 15 are arranged so that the flanges 41b, 41c on both sides have the same size in the width direction. In this case, the flanges 41b, 41c on both sides of the metal pipe 41 can have the same size.

[0051] The molding die 2 forms a metal pipe 41 that is curved when viewed from above and below. In this case, the sizes of the flange portions 41 b, 41 c tend to vary between the inner and outer circumferential sides of the curve, but by adopting the configuration of this embodiment, this variation can be reduced.

[0052] The molding device 1 further includes a fluid supply unit 6 that supplies a fluid to the heated metal pipe material 40. The heated metal pipe material 40 is prone to variations in size of the flange portions 41b, 41c due to variations in temperature, etc., but by employing the configuration of this embodiment, this variation can be reduced.

[0053] The relationship between the curvature of the metal pipe 41 (metal pipe material 40) and temperature will be described in more detail. As shown in FIG. 9( a), when the metal pipe material 40 is electrically heated, the current density is higher on the inner periphery than on the outer periphery, resulting in a temperature difference on the inner periphery. As a result, the metal pipe material 40 experiences a larger amount of thermal expansion on the inner periphery than on the outer periphery. Furthermore, as shown in FIG. 9( b), when the dies 11 and 12 are closed to form the flanges 41b and 41c, a compressive force acts on the inner periphery and a tensile force acts on the outer periphery. This results in excess material on the inner flange 41b. Therefore, as shown in FIG. 9( c), the metal pipe 41 undergoes deformation that reduces the curvature angle due to the difference between longitudinal expansion and contraction and thermal expansion, making the pipe center more likely to shift toward the outer periphery. Therefore, when the dies 14 and 15 are not provided as in this embodiment, the inner flange 41b tends to be larger in width. In contrast, the molding apparatus 1 according to this embodiment can reduce variations in the flange portions 41 b, 41 c between the dies 14, 15, thereby making it possible to uniform the size of the inner flange portion 41 b and the size of the outer flange portion 41 c. Furthermore, by appropriately adjusting the operation of the dies 14, 15, it is possible to improve the degree of freedom in molding the corner R of the metal pipe 41 having a complex shape.

[0054] In the molding apparatus 1, the dies 14, 15 continue to correct the misalignment of the pre-flange portions 40b, 40c until the dies 11, 12 are clamped together. Therefore, the dies 14, 15 can continue to correct the misalignment of the pre-flange portions 40b, 40c even while the dies 11, 12 are closing and the pre-flange portions 40b, 40c are being crushed. As a result, it is possible to reduce the variation in size of the completed flange portions 41b, 41c.

[0055] The present invention is not limited to the above-described embodiments.

[0056] For example, in the above-described embodiment, the molds 14, 15 are arranged so that the widthwise size of the flange portion 41b and the widthwise size of the flange portion 41c are the same. Alternatively, the pair of molds 14, 15 may be arranged so that the widthwise sizes of the flange portions 41b, 41c on both sides are different from each other. In this case, the flange portions 41b, 41c on both sides of the metal pipe 41 can each be made to the desired size.

[0057] For example, as shown in FIG. 6( b), the flange portion 41b may be molded larger than the flange portion 41c. In this case, as shown in FIG. 5( a), in the initial state, the restricting surface 14a of the mold 14 may be positioned outward of the restricting surface 15a of the mold 15 relative to the widthwise center of the molding die 2. In this case, as shown in FIG. 5( b), during the primary blowing stage, the flange-to-be portion 40c contacts the restricting surface 15a, while the flange-to-be portion 40b is spaced from the restricting surface 14a. Therefore, the flange-to-be portion 40c expands while being restricted by the restricting surface 15a, while the flange-to-be portion 40b can expand without being restricted. As shown in FIG. 6( a), when the control unit 8 further moves the mold 12 downward, the mold 15 moves outward, while the mold 14 does not move until it contacts the tapered surface 62b. Meanwhile, the flange-to-be portion 40b is crushed and expands outward, thereby contacting the restricting surface 14a. As a result, the flange portions 40b are restricted by the restricting surfaces 14a. The control unit 8 further moves the mold 12 downward, thereby completing the flange portions 41b and 41c as shown in FIG.

[0058] As described above, the metal pipe 41 shown in FIG. 6(b) has a hollow pipe portion 41a and a pair of flange portions 41b, 41c protruding from the pipe portion 41a on both sides in the width direction, and the pair of flange portions 41b, 41c have predetermined widthwise sizes that are different from each other.

[0059] The widthwise sizes of the pair of flange portions 41b, 41c of the metal pipe 41 are different from each other, and since a process is performed during molding so that each of the flange portions 41b, 41c has the predetermined size, it is possible to reduce the variation in size of the flange portions 41b, 41c.

[0060] Also in the embodiment shown in Figures 5 and 6, the dies 14 and 15 continue to correct the misalignment of the flange portions 40b and 40c until the dies 11 and 12 are clamped together (Figure 6(b)).

[0061] In the above-described embodiment, the metal pipe 41 has a pair of flange portions 41b, 41c. 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 one flange portion 41b. In this case, as shown in FIG. 7(a), in the initial state, the restricting surface 14a of the mold 14 may be positioned outward of the restricting surface 15a of the mold 15 with respect to the center position in the width direction of the molding die 2. Furthermore, the recesses 52, 63 are formed to the right of the center position. In this case, the restricting surface 15a is positioned at the right end of the recesses 52, 63. In this case, as shown in FIG. 7(b), during the primary blowing stage, the flange-to-be portion 40b contacts the restricting surface 14a, while the right end of the pipe portion 40a contacts the restricting surface 15a. Therefore, no flange-to-be portion is formed on the right side. As shown in Figure 8(a), when the control unit 8 further moves the mold 12 downward, the molds 14 and 15 move outward. The state in which the flange portion is not formed on the right side of the pipe portion 40a continues. When the control unit 8 further moves the mold 12 downward, the flange portion 41b is completed as shown in Figure 8(b).

[0062] 7 and 8, the mold 14 continues to correct the misalignment of the flange portion 40b until the mold 11 and mold 12 are clamped together (FIG. 8(b)).

[0063] In the above embodiment, the regulating dies are provided on both sides in the width direction, but they may be provided on only one side in the width direction.

[0064] In the above-described embodiment, the tapered structures 71 and 72 are formed between the molds 14 and 15 and the upper mold 12. Alternatively, the tapered structures may be formed between the molds 14 and 15 and the lower mold 11, or between both the molds 11 and 12.

[0065] In the above-described embodiment, a gas damper is used as the elastic mechanism, but any mechanism that generates elastic force may be used, and may be formed of an elastic member, etc. Furthermore, the molds 14 and 15 may be configured so that their widthwise positions can be controlled by an actuator, etc.

[0066] In the above embodiment, the mold used in the molding device for STAF has been described as an example. However, the type of molding device in which the mold according to the present invention is used is not particularly limited, and any molding device that supplies a fluid to expand a metal pipe material may be used.

[0067] 1...molding device, 2...molding mold (molding mold), 6...fluid supply section, 11...mold (first mold), 12...mold (second mold), 14, 15...mold (third mold), 40...metal pipe material, 40b, 40c...flange-intent section, 41b, 41c...flange section, 41...metal pipe, 66, 67...gas damper (elastic mechanism), 71, 72...tapered structure.

Claims

1. A molding device for molding a flanged metal pipe, comprising: a molding die for molding the metal pipe, wherein the molding die has 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 flange-to-be portion of the metal pipe material, and the third die continues to correct any misalignment of the flange-to-be portion until the first die and the second die are clamped together.

2. The molding device according to claim 1, wherein the third mold is disposed on at least one side of the metal pipe material in a second direction intersecting the first direction, and the third mold moves away from the metal pipe material as the first mold and the second mold move closer to each other.

3. A molding device as described in claim 1 or 2, wherein the third mold moves away from the metal pipe material as the first mold and the second mold approach each other due to a tapered structure formed on at least one of the third mold and the first mold and the second mold.

4. A molding device according to any one of claims 1 to 3, wherein the molding die forms the metal pipe to be curved when viewed from the first direction.

5. A molding device according to any one of claims 1 to 4, wherein the metal pipe has flange portions on both sides in a second direction intersecting the first direction, and the molding die has a pair of third dies arranged on both sides of the metal pipe material in the second direction.

6. A molding apparatus according to claim 5, wherein the pair of third dies are respectively arranged so that the sizes of the flange portions on both sides in the second direction are the same.

7. A molding apparatus according to claim 5, wherein the pair of third dies are arranged so that the flange portions on both sides have different predetermined sizes in the second direction.

8. The molding apparatus according to any one of claims 1 to 7, further comprising a fluid supply unit that supplies a fluid to the heated metal pipe material.

9. A molding device according to any one of claims 1 to 8, further comprising an elastic mechanism that applies an elastic force to the third mold toward the metal pipe material in a second direction that intersects with the first direction.

10. A metal pipe having a hollow pipe section and a pair of flange sections protruding from said pipe section on both sides in the width direction, wherein the sizes of the pair of flange sections in the width direction are different from each other and have predetermined sizes.

11. A molding device for molding a flanged metal pipe, comprising: a molding die for molding the metal pipe, wherein the molding die has a first die and a second die that face each other in a first direction in a cross-sectional view, and a third die that is disposed on at least one side of the metal pipe material in a second direction that intersects with the first direction, and the third die moves away from the metal pipe material as the first die and the second die move closer to each other.

Images