Ohmic heating device, molding system, and ohmic heating method

Abstract

This ohmic heating device comprises an electrode part that comes into contact with the outer peripheral surface of a metal pipe material and that supplies a current thereto. The electrode part has a first clamp section that includes a placement surface on which the metal pipe material is placed and a second clamp section that is disposed above the first clamp section so as to sandwich the metal pipe material with the first clamp section. The second clamp section can move so that there is space directly above the placement surface, while maintaining a position in a direction along the axial direction of the metal pipe material.

Description

Electric Heating Apparatus, Forming System, and Electric Heating Method

[0001] The present disclosure relates to an electric heating apparatus, a forming system, and an electric heating method.

[0002] As a forming system, there is known a forming system including: an electric heating apparatus that electrically heats a metal pipe material; and a forming apparatus that forms the metal pipe material heated by the electric heating apparatus (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Application Publication No. 2009-220141

[0004] In the electric heating apparatus as described above, an electrode section has a lower clamp part and an upper clamp part, and is configured to vertically sandwich the metal pipe material between these clamp parts. In such an electric heating apparatus, after electrically heating the metal pipe material, the upper clamp part is lifted, and then the upper clamp part is moved in the axial direction of the metal pipe material to open above the metal pipe material, and the metal pipe material is sometimes taken out upward by a robot hand or the like. In this case, it may take time to take out the metal pipe material after electric heating, which results in a large temperature decrease before the metal pipe material is formed, leading to a concern that the formability of the metal pipe material deteriorates.

[0005] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide an electric heating apparatus, a forming system, and an electric heating method capable of quickly taking out a metal pipe material after electric heating.

[0006] The electric heating apparatus includes an electrode section that contacts an outer circumferential surface of a metal pipe material and supplies an electric current, the electrode section includes: a first clamp part including a placement surface on which the metal pipe material is placed; and a second clamp part disposed on the first clamp part to sandwich the metal pipe material between the second clamp part and the first clamp part, and the second clamp part is movable such that a space directly above the placement surface is emptied while maintaining a position thereof in a direction along the axial direction of the metal pipe material.

[0007] In this electrically heated device, the second clamp is moved so that there is space directly above the mounting surface while maintaining a position along the axial direction of the metal pipe material. Therefore, the metal pipe material after electric heating can be removed by moving the second clamp in a single motion, rather than by moving it in stages. As a result, the metal pipe material after electric heating can be removed quickly.

[0008] The device is equipped with a movable mechanism for moving the second clamp section, which is divided into two clamp bodies, and the movable mechanism may be configured to allow each of the clamp bodies to rotate so as to move closer to and further away from the mounting surface. In this case, a configuration can be specifically realized in which the second clamp section is moved so that there is space directly above the mounting surface.

[0009] The device may be equipped with a movable mechanism for moving the second clamping portion, and the movable mechanism may be rotatable so as to move the second clamping portion closer to and further away from the mounting surface. In this case, a configuration can be specifically realized in which the second clamping portion is moved so that there is space directly above the mounting surface.

[0010] The device is equipped with a movable mechanism for moving the second clamp section, which is divided into two clamp bodies, and the movable mechanism may allow each of the clamp bodies to slide along the radial direction of the metal pipe material. In this case, a configuration can be specifically realized in which the second clamp section is moved so that there is space directly above the mounting surface.

[0011] When the first clamp portion and the second clamp portion are in contact, a gap may be formed between the two clamp bodies. In this case, the two clamp bodies can be configured not to come into contact with each other. As a result, for example, wear on the two clamp bodies can be suppressed.

[0012] The second clamping portion may be provided with a guide portion that guides the movement of the second clamping portion so as to maintain its position along the axial direction of the metal pipe material. In this case, the movement of the second clamping portion while maintaining its position along the axial direction of the metal pipe material can be reliably achieved by the guidance of the guide portion.

[0013] Of the first and second clamping sections, only the first clamping section may be electrically connected to a conductor that conducts current from the current supply section. In this case, since the movable second clamping section is not electrically connected to the conductor, interference with its movement can be suppressed.

[0014] The molding system according to this disclosure comprises the above-mentioned electrically heated device and a molding apparatus for molding a metal pipe material heated by the electrically heated device. This molding system can be used to obtain the same effects and functions as the above-mentioned electrically heated device.

[0015] The electric heating method according to this disclosure is an electric heating method that includes the step of supplying an electric current by bringing an electrode portion into contact with the outer circumferential surface of a metal pipe material, wherein the electrode portion includes a first clamp portion including a mounting surface on which the metal pipe material is placed, and a second clamp portion positioned on the first clamp portion so as to sandwich the metal pipe material between the first clamp portion and the second clamp portion, and the electric heating method includes the step of moving the second clamp portion while maintaining its position in a direction along the axial direction of the metal pipe material, so as to leave space directly above the mounting surface. With this electric heating method, the same effects and advantages as the electric heating device described above can be obtained.

[0016] According to this disclosure, it is possible to provide an electrically heated device, a molding system, and an electrically heated method that can quickly remove metal pipe material after electrically heated.

[0017] Figure 1 is a schematic diagram showing a molding system according to the first embodiment. Figure 2 is another schematic diagram showing the molding system of Figure 1. Figure 3 is a schematic diagram showing the energized heating device of Figure 1. Figure 4 is a side view showing the peripheral configuration of the electrode section in the closed state in the energized heating device of Figure 3. Figure 5 is a perspective view showing the peripheral configuration of the electrode section in the closed state in the energized heating device of Figure 3. Figure 6 is a side view showing the peripheral configuration of the electrode section in the open state in the energized heating device of Figure 3. Figure 7 is an enlarged view showing a part of the energized heating device of Figure 4. Figure 8 is a perspective view showing the guide section of the energized heating device of Figure 4. Figure 9 is a flowchart showing the energized heating method according to the first embodiment. Figure 10 is a side view showing the peripheral configuration of the electrode section in the closed state in the energized heating device according to the second embodiment. Figure 11 is a side view showing the peripheral configuration of the electrode section in the closed state in the energized heating device according to the third embodiment.

[0018] The embodiments will be described below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be omitted.

[0019] [First Embodiment] The first embodiment will now be described. As shown in Figures 1 and 2, the molding system 100 according to the first embodiment is a system for manufacturing a molded product 140 by heating a metal pipe material 40 and molding the heated metal pipe material 40 with a mold. As the metal pipe material 40, for example, carbon steel or MnB steel with improved hardenability can be used. The molding system 100 comprises an electrically heated device 101, a molding apparatus 103 having a mold 102, and a cooling mechanism 104.

[0020] As shown in Figure 3, the electric heating device 101 heats the metal pipe material 40 by passing an electric current through it. The electric heating device 101 includes at least an electrode section 60 that contacts the metal pipe material 40 and supplies an electric current, and a power supply 90 that supplies an electric current to the electrode section 60 (details will be described later). By supplying an electric current from the power supply 90 to the metal pipe material 40 via the electrode section 60, the metal pipe material 40 itself generates heat through Joule heating due to its own electrical resistance. This type of heating by electric current is called "electric heating". The electric heating device 101 in this embodiment is an external electric heating device that is located outside the molding apparatus 103, at a different location from the molding apparatus 103.

[0021] Returning to Figures 1 and 2, the molding apparatus 103 is a device that molds a metal pipe material 40 heated by an electrically heated device 101 using a mold 102. For example, in the illustrated configuration, the molding apparatus 103 performs molding and hardening by supplying fluid to the heated metal pipe material 40 and bringing it into contact with the molding surface of the mold. The molding apparatus 103 forms a molded product 140, which is a hollow metal pipe, by blow molding.

[0022] The molding apparatus 103 comprises a mold 102, a drive mechanism 3, a holding unit 4, a fluid supply unit 6, a cooling unit 7, and a control unit 8. In this specification, the metal pipe material 40 refers to a hollow article before molding is completed in the molding apparatus 103. The metal pipe material 40 is a pipe material of a hardenable steel type. In addition, the axial direction (extension direction) of the metal pipe material 40 during molding may be referred to as the "axial direction," and the horizontal direction perpendicular to the axial direction may be referred to as the "width direction." The outer side of the metal pipe material 40 in the axial direction may simply be referred to as the "outer side in the axial direction," and the inner side of the metal pipe material 40 in the axial direction may simply be referred to as the "inner side in the axial direction."

[0023] The molding die 102 is a mold for forming a molded product 140 from a metal pipe material 40, and comprises a lower mold 11 and an upper mold 12 that face each other in the vertical direction. The lower mold 11 and the upper mold 12 are made of steel blocks. Each of the lower mold 11 and the upper mold 12 is provided with a recess in which the metal pipe material 40 is contained. When the lower mold 11 and the upper mold 12 are in close contact with each other (mold closed state), their respective recesses form a space of the target shape in which the metal pipe material is to be molded. Therefore, the surface of each recess becomes the molding surface of the molding die 102. The lower mold 11 is fixed to the base 13 via a die holder or the like. The upper mold 12 is fixed to the slide of the drive mechanism 3 via a die holder or the like.

[0024] The drive mechanism 3 is a mechanism for moving at least one of the lower mold 11 and the upper mold 12. In the illustrated example, the drive mechanism 3 has a configuration that moves 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 come into contact with each other, a pull-back cylinder 22 as an actuator that generates a force to pull the slide 21 upward, a main cylinder 23 as a drive source that pressurizes the slide 21 downward, and a drive source 24 that provides driving force to the main cylinder 23.

[0025] The holding portion 4 is a mechanism for holding a metal pipe material 40 positioned between the lower mold 11 and the upper mold 12. The holding portion 4 comprises a lower holding portion 41 and an upper holding portion 42 that hold the metal pipe material 40 at one end in the longitudinal direction of the molding die 102, and a lower holding portion 41 and an upper holding portion 42 that hold the metal pipe material 40 at the other end in the longitudinal direction of the molding die 102. The lower holding portion 41 and the upper holding portion 42 hold the metal pipe material 40 by clamping the vicinity of the end of the metal pipe material 40 from above and below. The lower holding portion 41 and the upper holding portion 42 are provided with a drive mechanism (not shown) that allows them to move independently in the vertical direction.

[0026] 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 become hot when heated by the electric heating device 101, causing the metal pipe material 40 to expand. The fluid supply unit 6 is provided on both ends in the longitudinal direction of the molding die 102. The fluid supply unit 6 comprises 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 back and forth relative to the opening of the metal pipe material 40, and a supply source 33 that supplies high-pressure fluid into the metal pipe material 40 via the nozzle 31. The drive mechanism 32 ensures a tight seal when supplying and exhausting fluid by making the nozzle 31 tightly attached to the end of the metal pipe material 40, and separates the nozzle 31 from the end of the metal pipe material 40 at other times.

[0027] The fluid supply unit 6 may supply gases such as high-pressure air or inert gas as the fluid. Furthermore, the fluid supply unit 6 may be the same device as at least one of the holding unit 4, which has a mechanism for moving the metal pipe material 40 vertically, and the electrically heated device 101.

[0028] The cooling unit 7 is a mechanism for cooling the mold 102. By cooling the mold 102, the cooling unit 7 can rapidly cool the expanded metal pipe material 40 when it comes into contact with the molding surface of the mold 102. The cooling unit 7 includes a flow path 36 formed inside the lower mold 11 and the upper mold 12, and a water circulation mechanism 37 that supplies and circulates cooling water to the flow path 36.

[0029] The control unit 8 is a device that controls the entire molding apparatus 103. The control unit 8 controls the drive mechanism 3, the holding unit 4, 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 with the molding die 102.

[0030] The control unit 8 controls the drive mechanism 3 to lower the upper mold 12 and bring it close to the lower mold 11, thereby closing the mold 102. 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, which has been softened by heating, expands and comes into contact with the molding surface of the mold 102. The metal pipe material 40 is then molded to conform to the shape of the molding surface of the mold 102. When forming a molded product 140 with a flange, a portion of the metal pipe material 40 is inserted into the gap between the lower mold 11 and the upper mold 12, and then the mold is closed to crush the inserted portion and form the flange. When the metal pipe material 40 comes into contact with the molding surface, it is rapidly cooled by the mold 102 cooled by the cooling unit 7, thereby quenching the metal pipe material 40.

[0031] The cooling mechanism 104 is a mechanism for cooling the molded product 140. In this embodiment, the cooling mechanism 104 is located outside the mold 102, at a different location from the mold 102. The cooling mechanism 104 may be a cooling jig 110 for cooling the molded product 140. The cooling mechanism 104 comprises an upper jig 111 and a lower jig 112 for receiving the molded product 140 after molding. The upper jig 111 and the lower jig 112 sandwich the molded product 140, thereby removing heat from the molded product 140 at the point of contact with the molded product 140.

[0032] As shown in Figures 3, 4, and 5, the electrically heated device 101 comprises a base 50, an electrode section 60, a movable mechanism 70, a power supply 90, and a control unit 95. The base 50 supports the electrode section 60 and the movable mechanism 70 on its upper surface 50a. Leakage is prevented by sandwiching an insulating plate 58 (see Figure 3) made of insulating material between the base 50 and the electrode section 60 (electrode mounting section).

[0033] The electrode portion 60 contacts the outer circumferential surface of the end of the metal pipe material 40 and holds the end of the metal pipe material 40 so as to surround it. The electrode portion 60 supplies current from the power supply 90 to the end of the metal pipe material 40. The electrode portion 60 is provided at one end and the other end of the metal pipe material 40. The electrode portion 60 has a lower clamp portion (first clamp portion) 61 and an upper clamp portion (second clamp portion) 62.

[0034] The lower clamp portion 61 is a rectangular block-shaped member made of a conductive material (for example, copper). Viewed from the axial direction, a groove corresponding to the shape of the lower part of the metal pipe material 40 is formed in the upper center in the width direction of the lower clamp portion 61. The bottom surface of the groove of the lower clamp portion 61 constitutes a mounting surface 61a on which the metal pipe material 40 is placed. The mounting surface 61a is a curved surface corresponding to the outer circumferential surface of the metal pipe material 40. The mounting surface 61a is in contact with the lower part of the metal pipe material 40.

[0035] The upper clamp portion 62 is a rectangular block-shaped member and is made of a conductive material (for example, copper). The upper clamp portion 62 is positioned on the lower clamp portion 61 so as to sandwich the metal pipe material 40 between it and the lower clamp portion 61. Viewed from the axial direction, a groove is formed in the lower center of the upper clamp portion 62 in the width direction, corresponding to the shape of the upper part of the metal pipe material 40. The bottom surface of this groove in the upper clamp portion 62 constitutes a contact surface 62a that contacts the upper part of the metal pipe material 40. The contact surface 62a is a curved surface corresponding to the outer circumferential surface of the metal pipe material 40. The upper clamp portion 62 is divided in the width direction into two side clamp portions (clamp bodies) 62L and 62R.

[0036] The side clamp portions 62L and 62R are members formed by dividing the upper clamp portion 62 into two equal parts in the width direction, such that the contact surface 62a is divided into two equal parts. A tapered surface 63 is formed on the axial outer side surface of the lower part of the side clamp portions 62L and 62R, which can contact the guide portion 80 described later (see Figure 8). The tapered surface 63 is a flat surface and, when viewed from the width direction, inclins inward in the axial direction as it goes downward.

[0037] The mounting surface 61a of the lower clamp portion 61 and the contact surface 62a of the upper clamp portion 62 are continuous and smoothly aligned when the electrode portion 60 is holding the end of the metal pipe material 40 (the closed state of the upper clamp portion 62, described later). The mounting surface 61a and the contact surface 62a extend in a circular shape corresponding to the outer circumferential surface of the metal pipe material 40 when viewed from the axial direction when the electrode portion 60 is holding the end of the metal pipe material 40. A flat wire connection portion 66, with the vertical direction being the thickness direction, is integrally provided at the lower part of the lower clamp portion 61. The wire connection portion 66 is made of a conductive material. A wire (not shown) that conducts current from the power supply 90 is electrically connected to the lower clamp portion 61 via the wire connection portion 66, while the wire is not connected to the upper clamp portion 62. In other words, of the lower clamp portion 61 and the upper clamp portion 62, the wire is electrically connected only to the lower clamp portion 61.

[0038] The movable mechanism 70 is a mechanism for opening and closing the upper clamp portion 62. The movable mechanism 70 moves the upper clamp portion 62. Specifically, the movable mechanism 70 moves the upper clamp portion 62 so as to switch between an open state, where the upper clamp portion 62 is opened so that there is space directly above the mounting surface 61a, and a closed state, where the upper clamp portion 62 is closed so that the area directly above the mounting surface 61a is closed by the upper clamp portion 62. When the upper clamp portion 62 is in the closed state, the lower surface 62s of the upper clamp portion 62 and the upper surface 61s of the lower clamp portion 61 are in contact, and the lower clamp portion 61 and the upper clamp portion 62 are electrically connected. When the upper clamp portion 62 is in the open state, the lower surface 62s of the upper clamp portion 62 and the upper surface 61s of the lower clamp portion 61 are separated.

[0039] As shown in Figures 4, 5, and 6, the movable mechanism 70 of this embodiment moves the upper clamp portion 62 so that the area directly above the mounting surface 61a is open, while maintaining the position of the upper clamp portion 62 in the axial direction. The movable mechanism 70 also moves the upper clamp portion 62 so that the area directly above the mounting surface 61a is closed by the upper clamp portion 62, while maintaining the position of the upper clamp portion 62 in the axial direction, thereby closing the upper clamp portion 62. In the illustrated example, the movable mechanism 70 includes a first movable member 71, a second movable member 72, a first cylinder 75, and a second cylinder 76.

[0040] The first movable member 71 is rotatably supported by a support portion 55L provided on the base 50 via a first rotation axis X1 extending along the axial direction. This allows the first movable member 71 to rotate around the first rotation axis X1 as its base (center). The first movable member 71 has a fixed side clamp portion 62L and rotates integrally with the side clamp portion 62L. Here, the side clamp portion 62L is fixed to the first movable member 71 with its upper surface, outer side surface in the axial direction, and outer side surface in the width direction in contact with the side clamp portion 62L. An insulating portion (not shown) made of insulating material is provided between the first movable member 71 and the electrode portion 60.

[0041] The second movable member 72 is rotatably supported by a support portion 55R provided on the base 50 via a second rotation axis X2 extending along the axial direction. This allows the second movable member 72 to rotate around the second rotation axis X2 as its base axis. The side clamp portion 62R of the second movable member 72 is fixed and rotates integrally with the side clamp portion 62R. Here, the side clamp portion 62R is fixed to the second movable member 72 with its upper surface, outer side surface in the axial direction, and outer side surface in the width direction in contact with the side clamp portion 62R. An insulating portion (not shown) made of insulating material is provided between the second movable member 72 and the electrode portion 60.

[0042] The first cylinder 75 is a drive source that drives the first movable member 71. For example, a hydraulic cylinder is used as the first cylinder 75. The first cylinder 75 includes a cylinder body 75A and a cylinder rod 75B. The lower portion of the cylinder body 75A is rotatably supported on one side in the width direction of the base 50 via a first base end shaft Z1 extending along the axial direction. The tip end of the cylinder rod 75B is rotatably connected to a connecting portion 71U provided on the outer side in the width direction at the upper portion of the first movable member 71 via a first connecting shaft Y1 extending along the axial direction. The first cylinder 75 is connected to a control unit 95, and the operation thereof is controlled by the control unit 95.

[0043] The second cylinder 76 is a drive source that drives the second movable member 72. For example, a hydraulic cylinder is used as the second cylinder 76. The second cylinder 76 includes a cylinder body 76A and a cylinder rod 76B. The lower portion of the cylinder body 76A is rotatably supported on the other side in the width direction of the base 50 via a second base end shaft Z2 extending along the axial direction. The tip end of the cylinder rod 76B is rotatably connected to a connecting portion 72U provided on the outer side in the width direction at the upper portion of the second movable member 72 via a second connecting shaft Y2 extending along the axial direction. The second cylinder 76 is connected to a control unit 95, and the operation thereof is controlled by the control unit 95.

[0044] Such a movable mechanism 70 enables each of the side clamp portions 62L, 62R to rotate about the first rotation shaft X1 and the second rotation shaft X2 respectively so as to approach and separate from the mounting surface 61a. For example, when the upper clamp portion 62 is in a closed state, controlling the first cylinder 75 and the second cylinder 76 by the control unit 95 and driving the cylinder rods 75B, 76B to retract causes the following operation. That is, each of the first cylinder 75 and the second cylinder 76 rotates about the first base end shaft Z1 and the second base end shaft Z2 respectively such that the upper portion thereof falls outward in the width direction. Each of the first movable member 71 and the second movable member 72 rotates about the first rotation shaft X1 and the second rotation shaft X2 respectively so as to open outward in the width direction.

[0045] As a result, the side clamp portions 62L and 62R fixed to the first and second movable members 71 and 72 move outward in the width direction around the first and second rotation axes X1 and X2, respectively (that is, along an arc-shaped trajectory that moves outward in the width direction while moving upward). Consequently, the upper clamp portion 62 moves so that the area directly above the mounting surface 61a is cleared while maintaining its position along the axial direction, and the upper clamp portion 62 becomes open. Specifically, the upper clamp portion 62 in the closed state moves in a single motion without changing its position along the axial direction, so that the area directly above the mounting surface 61a is cleared, and the upper clamp portion 62 becomes open. In other words, the pair of side clamps 62L and 62R of the upper clamp portion 62, whose lower surface 62s is in contact with the upper surface 61s of the lower clamp portion 61, do not move in the axial direction, but open in a double-opening structure (double-door structure) so that the mounting surface 61a is visible when viewed from above, while moving away from the mounting surface 61a, and the upper clamp portion 62 is in the open state.

[0046] On the other hand, in the movable mechanism 70, when the upper clamp portion 62 is in the open state, the control unit 95 controls the first cylinder 75 and the second cylinder 76 and drives the cylinder rods 75B and 76B to extend, thereby operating in the opposite direction to the above-described operation and closing the upper clamp portion 62.

[0047] Returning to Figure 3, the power supply 90 is a current supply unit that supplies current to the electrode section 60. The power supply 90 is connected to the control unit 95, and its operation is controlled by the control unit 95. The control unit 95 transmits a control signal to the movable mechanism 70, thereby driving the first and second cylinders 75 and 76 to move the upper clamp section 62 and switching the open and closed states of the upper clamp section 62. The control unit 95 transmits a control signal to the power supply 90, thereby controlling the timing of the energized heating by the energized heating device 101, and also controls the heating temperature by adjusting the magnitude of the current.

[0048] As shown in Fig. 7, in the present embodiment, when the upper clamp portion 62 is in the closed state, that is, when the upper surface 61s of the lower clamp portion 61 and the lower surface 62s of the upper clamp portion 62 are in contact with each other, a gap Gp is formed between the side clamp portions 62L and 62R. In the closed state of the upper clamp portion 62, the side clamp portions 62L and 62R do not contact each other in the width direction, but are spaced apart by the gap Gp as a minute distance. The gap Gp is an interval that prevents abnormal heating between the side clamp portions 62L and 62R during energization heating of the electrode portion 60. The gap Gp is, for example, a minute interval of less than 1 mm.

[0049] As shown in Fig. 8, the energization heating apparatus 101 includes a guide portion 80. The guide portion 80 guides the movement of the upper clamp portion 62 such that the position in the direction along the axial direction is maintained. The guide portion 80 opens and closes the upper clamp portion 62 while regulating the axial position of the upper clamp portion 62. In the illustrated example, the guide portion 80 is a plate-shaped member having the axial direction as the thickness direction and the vertical direction as the longitudinal direction. The guide portion 80 is fixed in contact with the axially outer side surface of the lower clamp portion 61. The upper portion of the guide portion 80 projects upward from the upper surface 61s of the lower clamp portion 61. The upper portion of the guide portion 80 is shaped to protrude in a beak shape inward in the axial direction.

[0050] A pair of guide portions 80 are provided corresponding to each of the side clamp portions 62L and 62R. One guide portion 80 is provided at a position where the upper portion thereof can contact the tapered surface 63 at the lower part of the side clamp portion 62L. The other guide portion 80 is provided at a position where the upper portion thereof can contact the tapered surface 63 at the lower part of the side clamp portion 62R. A guide surface 83 corresponding to the tapered surface 63 is formed on the axially inner side of the upper portion of the guide portion 80. The guide surface 83 is a flat surface, and when viewed from the width direction, it inclines inward in the axial direction as it goes downward. When the upper clamp portion 62 moves from the open state to the closed state, the guide surface 83 contacts the tapered surfaces 63 of the side clamp portions 62L and 62R to guide the movement.

[0051] A method for electrically heating a metal pipe material 40 using the electrically heated device 101 configured as described above will be explained with reference to the flowchart in Figure 9.

[0052] In the electric heating method, first, the metal pipe material 40 is set on the electrode section 60. Specifically, the control unit 95 controls the movable mechanism 70 to move the upper clamp section 62 to the open state (step S1). In step S1, while maintaining a position along the axial direction, the side clamp sections 62L and 62R are rotated around the first and second rotation axes X1 and X2 as base axes in one movement so that the area directly above the mounting surface 61a is clear. The robot hand places the metal pipe material 40 on the mounting surface 61a of the lower clamp section 61 (step S2). The control unit 95 controls the movable mechanism 70 to move the upper clamp section 62 to the closed state (step S3). In step S3, while maintaining a position along the axial direction, the side clamp sections 62L and 62R are rotated around the first and second rotation axes X1 and X2 as base axes in one movement so that the area directly above the mounting surface 61a is closed. This allows the electrode portion 60 to hold the metal pipe material 40 and to bring the electrode portion 60 into contact with the outer circumferential surface of the metal pipe material 40.

[0053] Next, the control unit 95 controls the power supply 90 and supplies current from the power supply 90 to the outer surface of the metal pipe material 40 via the electrode portion 60 that is in contact with the outer surface of the metal pipe material 40, thereby energizing and heating the metal pipe material 40 (step S4). Subsequently, the metal pipe material 40 is removed from the electrode portion 60. Specifically, the metal pipe material 40 is grasped by the robot hand (step S5). The control unit 95 controls the movable mechanism 70 and moves the upper clamp portion 62 to an open state (step S6). Then, the metal pipe material 40 is unloaded by the robot hand (step S7).

[0054] As described above, in the energized heating device 101, molding system 100, and energized heating method according to this embodiment, the upper clamp portion 62 is moved so that the area directly above the mounting surface 61a is clear while maintaining its position along the axial direction. Therefore, the metal pipe material 40 after energized heating can be removed by moving the upper clamp portion 62 in a single operation, rather than by moving it in stages. As a result, the metal pipe material 40 can be quickly removed from the energized heating device 101 after energized heating. Consequently, the time from energized heating of the metal pipe material 40 to molding can be shortened, and the amount of temperature drop of the metal pipe material 40 from energized heating to molding can be reduced. If the amount of temperature drop is large, the moldability of the material deteriorates and it becomes difficult to mold it into the shape specified by the mold. Therefore, in this embodiment, where the amount of temperature drop can be reduced, it is possible to improve the moldability.

[0055] In the electrically heated device 101, the movable mechanism 70 allows the side clamp portions 62L and 62R to rotate toward and away from the mounting surface 61a. In this case, the movable mechanism 70, which has a double-opening structure that allows the side clamp portions 62L and 62R to rotate toward opening, can be used to specifically realize a configuration in which the upper clamp portion 62 is moved so that the area directly above the mounting surface 61a is left open.

[0056] In the electrically heated device 101, a gap Gp is ​​formed between the side clamps 62L and 62R when the upper clamp 62 is in the closed position. In this case, the device can be configured so that the two do not come into contact with each other when the side clamps 62L and 62R are moved by the movable mechanism 70. This suppresses wear of the side clamps 62L and 62R. In particular, the gap Gp is ​​set to a minute distance so that the space between the side clamps 62L and 62R does not overheat when the electrode 60 is heated by current, thereby suppressing overheating of a part of the metal pipe material 40, and preventing damage to O-rings and the like attached to the metal pipe material 40 in a later process due to heat.

[0057] The electrically heated device 101 includes a guide section 80. In this case, the movement of the upper clamp section 62 while maintaining its position along the axial direction of the metal pipe material 40 can be reliably achieved by the guide of the guide section 80.

[0058] In the electrically heated device 101, the wires that conduct current from the power supply 90 are electrically connected only to the lower clamp portion 61. In this case, since the wires are not electrically connected to the movable upper clamp portion 62, interference with the movement of the wires can be suppressed.

[0059] In the electrically heated device 101, the lower clamp portion 61 and the side clamp portions 62L and 62R are all made of conductive material. This allows the electrode portion 60 to effectively electrically heat the metal pipe material 40. In the electrically heated device 101, hydraulic cylinders are used for the first and second cylinders 75 and 76. This increases the driving force of the upper clamp portion 62, thereby increasing the movement speed of the upper clamp portion 62, and making it possible to remove the metal pipe material 40 even more quickly after electrically heating.

[0060] Here, a comparative calculation was performed to compare the time it takes for the metal pipe material 40 to be removed after energizing in the energizing heating device 101 with the time it takes for the metal pipe material 40 to be removed after energizing in a conventional energizing heating device. The conventional energizing heating device is a device that, after energizing the metal pipe material 40, first raises the upper clamp part, and then moves the upper clamp part in the axial direction after that operation. According to the results of the comparative experiment, the time it takes for the metal pipe material 40 to be removed in the conventional energizing heating device is 4 seconds (temperature of the metal pipe material 40: 1050°C (immediately after energizing) → 965°C (after 4 seconds)), while the time it takes for the metal pipe material 40 to be removed in the energizing heating device 101 is 0.4 seconds (temperature of the metal pipe material 40: 1050°C (immediately after energizing) → 1040°C (after 0.4 seconds)). Thus, it can be assumed that in this embodiment the time it takes for the metal pipe material 40 to be removed can be significantly shortened and the temperature drop of the metal pipe material 40 can be significantly suppressed.

[0061] [Second Embodiment] Next, a second embodiment will be described. In describing the second embodiment, the differences from the first embodiment will be explained, and redundant explanations will be omitted.

[0062] As shown in Figure 10, the energized heating device 201 according to the second embodiment differs from the first embodiment in that it includes an upper clamp portion 262 and a movable mechanism 270 instead of the upper clamp portion 62 and movable mechanism 70 (see Figure 4). The upper clamp portion 262 is not divided into two side clamp portions 62L and 62R (see Figure 4) but is formed as a single unit. The other configurations of the upper clamp portion 262 are the same as those of the upper clamp portion 62. The movable mechanism 270 cantilever-supports the upper clamp portion 262 and allows the upper clamp portion 262 to rotate toward and away from the mounting surface 61a around a first rotation axis (rotation axis) X1.

[0063] The movable mechanism 270 includes a movable member 271 and a cylinder 275. The movable member 271 has an upper clamp portion 262 fixed to it and rotates integrally with the upper clamp portion 262. The movable member 271 cantilever-supports the upper clamp portion 262. Here, the upper clamp portion 262 is fixed to the movable member 271 with its upper surface, axial outer side surface, and both sides in the width direction in contact with the movable member 271. The other configurations of the movable member 271 are the same as those of the first movable member 71 (see Figure 4). The cylinder 275 is a drive source that drives the movable member 271. For example, a hydraulic cylinder is used as the cylinder 275. The other configurations of the cylinder 275 are the same as those of the first cylinder 75 (see Figure 4).

[0064] In such a movable mechanism 270, for example, when the upper clamp portion 262 is in the closed state, the cylinder 275 is controlled by the control unit 95 and driven to retract the cylinder rod 75B, thereby operating as follows: The cylinder 275 rotates around the first base end axis Z1. The movable member 271 rotates around the first rotation axis X1 so as to open outward in the width direction. As a result, the upper clamp portion 262 fixed to the movable member 271 moves so as to open outward in the width direction around the first rotation axis X1 (that is, along an arc-shaped trajectory that moves outward in the width direction while moving upward). Consequently, the upper clamp portion 262 moves so that the area directly above the mounting surface 61a is clear while maintaining its position along the axial direction, and the upper clamp portion 262 is in the open state. On the other hand, in the movable mechanism 270, when the upper clamp portion 262 is in the open state, the control unit 95 controls the cylinder 275 and drives the cylinder rod 75B to extend, thereby operating in the opposite direction to the above-described operation and closing the upper clamp portion 262.

[0065] As described above, the electrically heated device 201 and the electrically heated method according to this embodiment can also be used to obtain the same effects and benefits as those of the above embodiment.

[0066] In this embodiment, the movable mechanism 270 is rotatable so that the upper clamp portion 262 moves closer to and further away from the mounting surface 61a. In this case, a configuration can be specifically realized in which the upper clamp portion 262 is moved so that there is space directly above the mounting surface 61a. Furthermore, when the upper clamp portion 262 is opened and closed with a cantilevered opening and closing structure as in this embodiment, the configuration can be simplified and costs can be reduced compared to when the upper clamp portion is opened and closed with a double-opening structure.

[0067] [Third Embodiment] Next, a third embodiment will be described. In describing the third embodiment, the differences from the first embodiment will be explained, and redundant explanations will be omitted.

[0068] As shown in Figure 11, the energized heating device 301 according to the third embodiment differs from the first embodiment in that it is equipped with a movable mechanism 370 instead of the movable mechanism 70 (see Figure 4). The movable mechanism 370 allows each of the side clamp portions 62L and 62R to slide along the radial direction of the metal pipe material 40. The movable mechanism 370 allows each of the side clamp portions 62L and 62R to slide toward and apart from each other along the width direction. The movable mechanism 370 includes a first movable member 371, a second movable member 372, a first cylinder 375, and a second cylinder 376.

[0069] The first movable member 371 has a side clamp portion 62L fixed to it. Here, the side clamp portion 62L is fixed to the first movable member 371 with its upper surface, axial outer side surface, and widthwise outer side surface in contact with it. The first movable member 371 is configured to slide (reciprocate) along a rail RW laid on a support portion 355 provided on the base 50 so as to extend in the width direction. The first movable member 371 slides integrally with the side clamp portion 62L.

[0070] The second movable member 372 has a side clamp portion 62R fixed to it. Here, the side clamp portion 62R is fixed to the second movable member 372 with its upper surface, axial outer side surface, and widthwise outer side surface in contact with the second movable member 372. The second movable member 372 is configured to slide along a rail RW laid on a support portion 355 provided on the base 50 so as to extend in the width direction. The second movable member 372 slides integrally with the side clamp portion 62R.

[0071] The first cylinder 375 is a drive source that slides the first movable member 371. For example, a hydraulic cylinder is used as the first cylinder 375. The first cylinder 375 includes a cylinder body 375A and a cylinder rod 375B. The cylinder body 375A is fixed to the support part 355. The cylinder rod 375B is provided to extend along the horizontal direction. The tip of the cylinder rod 375B is fixed and connected to the first movable member 371. The first cylinder 375 is connected to the control unit 95, and its operation is controlled by the control unit 95.

[0072] The second cylinder 376 is a drive source that slides the second movable member 372. For example, a hydraulic cylinder is used as the second cylinder 376. The second cylinder 376 includes a cylinder body 376A and a cylinder rod 376B. The cylinder body 376A is fixed to the support part 355. The cylinder rod 376B is provided to extend along the horizontal direction. The tip of the cylinder rod 376B is fixed and connected to the second movable member 372. The second cylinder 376 is connected to the control unit 95, and its operation is controlled by the control unit 95.

[0073] In such a movable mechanism 370, for example, when the upper clamp portion 62 is in the closed state, the first and second cylinders 375 and 376 are controlled by the control unit 95 and driven to retract the cylinder rods 375B and 376B, thereby operating as follows: The side clamp portions 62L and 62R, fixed to the first and second movable members 371 and 372, move along the rail RW so as to be separated from each other in the width direction. As a result, the side clamp portions 62L and 62R move while maintaining their positions along the axial direction, so as to create space directly above the mounting surface 61a, and the upper clamp portion 62 becomes open. On the other hand, in the movable mechanism 370, when the upper clamp portion 62 is in the open state, the first and second cylinders 375 and 376 are controlled by the control unit 95 and driven to extend the cylinder rods 375B and 376B, thereby operating in the opposite direction to the above-described operation, and the upper clamp portion 62 becomes closed.

[0074] As described above, the energized heating device 301 and the energized heating method according to this embodiment can also be used to obtain the same effects and benefits as those of the above embodiment.

[0075] In this embodiment, the movable mechanism 370 allows each of the side clamp portions 62L and 62R to slide along the radial direction of the metal pipe material 40. In this case, it is possible to specifically realize a configuration in which the side clamp portions 62L and 62R are moved so that there is space directly above the mounting surface 61a. In addition, in this case, since there is no constraint in the height direction, it becomes possible to make the electrically heated device 301 lower (low profile).

[0076] [Modifications] The present disclosure is not limited to the embodiments described above.

[0077] In the above embodiment, the mechanism is designed to move while maintaining a position along the axial direction, meaning it is moved without moving in the axial direction, but it is not limited to this. While maintaining a position along the axial direction, it may also move slightly in the axial direction. For example, in the first embodiment, the first and second rotation axes X1 and X2 extend in a direction inclined with respect to the axial direction, and the side clamp portions 62L and 62R rotate around these first and second rotation axes X1 and X2 as base axes.

[0078] In the above embodiment, the energized heating devices 101, 201, and 301 are external energized heating devices provided outside the molding apparatus 103, separate from the molding apparatus 103, but are not limited to this. The energized heating devices 101, 201, and 301 may also be internal energized heating devices provided inside the molding apparatus 103. Such internal energized heating devices heat the metal pipe material 40 while it is positioned inside the molding die 102 (positioned in the space between the molds 11 and 12). By applying this disclosure to such a molding apparatus 103 (i.e., by having an internal energized heating device in the molding apparatus 103), the metal pipe material 40 can be removed earlier, and the cycle time within the molding apparatus 103 can be shortened.

[0079] The components in the above embodiments and modifications are not limited to the materials and shapes described above, and various materials and shapes can be applied. Furthermore, the components in the above embodiments and modifications can be arbitrarily applied to the components in other embodiments or modifications.

[0080] 40...metal pipe material, 60...electrode part, 61a...mounting surface, 61...lower clamp part (first clamp part), 62, 262...upper clamp part (second clamp part), 62L, 62R...side clamp part (clamp body), 70, 270, 370...movable mechanism, 80...guide part, 100...molding system, 101, 201, 301...electric heating device, 103...molding device, Gp...gap, X1...first rotation axis (rotation axis), X2...second rotation axis.

Claims

1. An electric heating device comprising an electrode portion that supplies an electric current by contacting the outer surface of a metal pipe material, wherein the electrode portion includes a first clamp portion including a mounting surface on which the metal pipe material is placed, and a second clamp portion positioned on the first clamp portion so as to sandwich the metal pipe material between itself and the first clamp portion, and the second clamp portion is movable such that the area directly above the mounting surface is clear while maintaining a position along the axial direction of the metal pipe material.

2. The electrically heated device according to claim 1, further comprising a movable mechanism for moving the second clamp portion, wherein the second clamp portion is composed of two clamp bodies, and the movable mechanism allows each of the clamp bodies to rotate so as to move closer to and further away from the aforementioned mounting surface.

3. The electrically heated device according to claim 1, further comprising a movable mechanism for moving the second clamp portion, wherein the movable mechanism is rotatable so as to move the second clamp portion closer to and further away from the aforementioned mounting surface.

4. The electrically heated device according to claim 1, further comprising a movable mechanism for moving the second clamp portion, wherein the second clamp portion is divided into two clamp bodies, and the movable mechanism allows each of the clamp bodies to slide along the radial direction of the metal pipe material.

5. The electrically heated device according to claim 2 or 4, wherein a gap is formed between one and the other clamp body when the first clamp portion and the second clamp portion are in contact.

6. The electrically heated device according to claim 1 or 2, further comprising a guide portion that guides the movement of the second clamp portion so as to maintain the position of the metal pipe material in a direction along the axial direction.

7. The electrically powered heating device according to claim 1 or 2, wherein a conductor for conducting current from the current supply unit is electrically connected to only the first clamp portion of the two clamp portions.

8. A molding system comprising: an electrically heated device according to claim 1 or 2; and a molding device for molding the metal pipe material heated by the electrically heated device.

9. An electric heating method comprising the step of supplying an electric current by bringing an electrode portion into contact with the outer circumferential surface of a metal pipe material, wherein the electrode portion includes a first clamp portion including a mounting surface on which the metal pipe material is placed, and a second clamp portion positioned on the first clamp portion so as to sandwich the metal pipe material between the first clamp portion and the second clamp portion, and the electric heating method comprising the step of moving the second clamp portion while maintaining its position in a direction along the axial direction of the metal pipe material, such that there is space directly above the mounting surface described above.

Images