JP2023159248A - Molding apparatus - Google Patents

Abstract

To provide an electrification heating device and an electrification heating method capable of reducing unevenness in a temperature distribution in an axial direction of a metal pipe material at heating.SOLUTION: Electrodes 101, 102 perform electrification relative to a part in a circumferential direction of an outer peripheral surface 14a of a metal pipe material 14, and do not perform electrification relative to the other part in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14. Therefore, the metal pipe material 14 can be arranged relative to the electrodes 101, 102 so as to electrify a part (first area E1) at a projection side of bending in the circumferential direction in the outer peripheral surface 14a of the metal pipe material 14. In the case of this arrangement, electrification is performed on the projection side (first area E1) of bending of the metal pipe material 14, as a part in which a path of electric current is long and is hardly heated, and electrification is not performed on a recess side (second area E2) of bending of the metal pipe material, as a part in which a path of electric current becomes short and is easily heated.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to an electrical heating device and an electrical heating method that heat a metal pipe material by applying electricity to the material.

BACKGROUND ART Conventionally, a molding apparatus is known that performs blow molding by closing a metal pipe with a molding die. For example, the molding apparatus disclosed in Patent Document 1 includes a mold and a gas supply section that supplies gas into a metal pipe material. In this forming device, heated metal pipe material is placed in a forming mold, and with the forming mold closed, gas is supplied from the gas supply section to the metal pipe material to cause it to expand. is molded into a shape corresponding to the shape of the molding die.

Japanese Patent Application Publication No. 2015-112608

In a conventional molding apparatus, the metal pipe material is held by an electrode before expansion molding, and the metal pipe material is heated by applying electricity through the electrode. Here, metal pipes as finished products have been required to have various shapes, and accordingly, metal pipe materials having various shapes have also been used. Here, there are cases in which a metal pipe material that is entirely bent is used. However, since the current tries to flow through the metal pipe material through the shortest path, there is a problem that when performing electrical heating of bent metal pipe material, temperature unevenness tends to occur in the metal pipe material in the axial direction of the metal pipe material. be. Therefore, it is required to suppress the unevenness of the temperature distribution in the axial direction of the metal pipe material.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrical heating device and an electrical heating method that can reduce the unevenness of the temperature distribution in the axial direction of a metal pipe material during heating.

The current heating device according to the present invention is a current heating device that heats a metal pipe material by applying current to the material, and includes an electrode that supplies power in contact with the outer peripheral surface of the metal pipe material, and the electrode is connected to the outer periphery of the metal pipe material. A portion of the surface in the circumferential direction is energized, and another portion of the outer circumferential surface of the metal pipe material is not energized.

According to the energization heating device according to the present invention, the electrode energizes a portion of the outer circumferential surface of the metal pipe material in the circumferential direction, and energizes the other portion of the outer circumferential surface of the metal pipe material in the circumferential direction. Do not do this. Therefore, the metal pipe material can be arranged with respect to the electrode so that electricity is applied to a portion of the outer circumferential surface of the metal pipe material on the protruding side of the bend in the circumferential direction. When arranged in this way, electricity is applied to the protruding side of the bend in the metal pipe material, which has a long current path and is difficult to heat, and to the concave side of the bend in the metal pipe material, which has a short current path and is easily heated. No electricity is applied on the side. This prevents the current from flowing in a concentrated manner on the bent side of the metal pipe material, thereby suppressing an increase in the amount of heat generated at that position. As described above, it is possible to reduce unevenness in the temperature distribution in the axial direction of the metal pipe material during heating.

In the current heating device, the electrode includes a first portion and a second portion that are spaced apart from each other and sandwich the outer circumferential surface of the metal pipe material, and the first portion extends in the circumferential direction of the outer circumferential surface of the metal pipe material. A part of the metal pipe material is energized, and the other part in the circumferential direction of the outer peripheral surface of the metal pipe material is not energized. This makes it easy to align the metal pipe material with respect to the electrode, since the part of the metal pipe material that is energized can be supported by the first part, and the part that is not energized can be supported by the second part. .

In the current heating device, the electrode includes a conductive part that supports the metal pipe material by contacting a part in the circumferential direction of the outer peripheral surface of the metal pipe material, and a conductive part that contacts the other part in the circumferential direction of the outer peripheral surface of the metal pipe material. an insulating part that supports a metal pipe material. By providing the conductive part and the insulating part in this manner, it is possible to easily configure a part to be energized and a part to not be energized.

The current heating method according to the present invention is a current heating method in which a metal pipe material is heated by applying current to it using the above-mentioned current heating device, and includes a step of preparing a metal pipe material bent so as to protrude in a bending direction. , a step of arranging the metal pipe material with respect to an electrode so that a portion of the outer circumferential surface of the metal pipe material on the protruding side of the bend in the circumferential direction is energized; and a step of heating the metal pipe material by applying electricity with the electrode. , is provided.

According to the energization heating method according to the present invention, it is possible to obtain the same functions and effects as the above-described energization heating device.

According to the electrical heating device of the present invention, it is possible to provide an electrical heating device and an electrical heating method that can reduce unevenness in the temperature distribution in the axial direction of a metal pipe material during heating.

FIG. 1 is a schematic configuration diagram showing a molding device in which a metal pipe material heated by the electrical heating device according to the present embodiment is used. FIG. 2 is an enlarged view of the area around the electrode, in which (a) shows the electrode holding the metal pipe material, (b) shows the seal member pressed against the electrode, and (c) a front view of the electrode. It is. FIG. 1 is a perspective view of the electrical heating device according to the present embodiment. FIG. 1 is a schematic diagram of an electrical heating device according to the present embodiment. 5 is a sectional view taken along the line VV shown in FIG. 4. FIG. FIG. 7 is a cross-sectional view of an electrode according to a modification. FIG. 7 is a cross-sectional view of an electrode according to a modification. FIG. 7 is a cross-sectional view of an electrode according to a modification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a molding device using a metal pipe material heated by an electrical heating device according to the present invention will be described with reference to the drawings. In addition, in each figure, the same parts or corresponding parts are given the same reference numerals, and overlapping explanations will be omitted.

<Configuration of molding equipment>
FIG. 1 is a schematic configuration diagram of a molding apparatus according to this embodiment. As shown in FIG. 1, a forming apparatus 10 for forming a metal pipe includes a forming die 13 consisting of an upper die 12 and a lower die 11, and a drive mechanism 80 for moving at least one of the upper die 12 and the lower die 11. , a pipe holding mechanism 30 that holds the metal pipe material 14 disposed between the upper mold 12 and the lower mold 11; and a high pressure inside the heated metal pipe material 14 held between the upper mold 12 and the lower mold 11. a gas supply section 60 for supplying gas; a pair of gas supply mechanisms 40, 40 for supplying gas from the gas supply section 60 into the metal pipe material 14 held by the pipe holding mechanism 30; , a water circulation mechanism 72 that forcibly cools the mold 13 with water, and a control section 70 that controls the drive of the drive mechanism 80, the drive of the pipe holding mechanism 30, and the gas supply of the gas supply section 60, respectively. It is configured with the following.

The lower mold 11, which is one of the molding molds 13, is fixed to a base 15. The lower die 11 is composed of a large steel block, and includes, for example, a rectangular cavity (recess) 16 on its upper surface. A cooling water passage 19 is formed in the lower mold 11, and a thermocouple 21 inserted from below is provided approximately in the center. This thermocouple 21 is supported by a spring 22 so as to be movable up and down.

Furthermore, a space 11a is provided near the left and right ends (left and right ends in FIG. 1) of the lower mold 11, and a lower holding member 17, which will be described later, is a movable part of the pipe holding mechanism 30 in the space 11a. , 18, etc., are arranged so as to be movable up and down. Then, by placing the metal pipe material 14 on the lower holding members 17 and 18, the lower holding members 17 and 18 become metal pipes arranged between the upper mold 12 and the lower mold 11. Contact material 14.

The lower holding members 17 and 18 are fixed to a reciprocating rod 95 that is a movable part of an actuator (not shown) that constitutes the pipe holding mechanism 30. This actuator is for vertically moving the lower holding members 17, 18, etc., and a fixed portion of the actuator is held on the base 15 side together with the lower mold 11.

The upper mold 12, which is the other molding die 13, is fixed to a slide 81, which will be described later, and which constitutes a drive mechanism 80. The upper die 12 is made of a large steel block, has a cooling water passage 25 formed therein, and has, for example, a rectangular cavity (recess) 24 on its lower surface. This cavity 24 is provided at a position facing the cavity 16 of the lower mold 11.

Similar to the lower mold 11, a space 12a is provided near the left and right ends of the upper mold 12 (left and right ends in FIG. Upper holding members 17, 18, etc. are arranged to be movable up and down. Then, in a state in which the metal pipe material 14 is placed on the upper holding members 17 and 18, the upper holding members 17 and 18 are moved downward to form a gap between the upper mold 12 and the lower mold 11. The metal pipe material 14 is contacted.

The upper holding members 17 and 18 are fixed to a reciprocating rod 96 that is a movable part of an actuator that constitutes the pipe holding mechanism 30. This actuator is for vertically moving the upper holding members 17, 18, etc., and a fixed portion of the actuator is held on the slide 81 side of the drive mechanism 80 together with the upper die 12.

In the right side portion of the pipe holding mechanism 30, a semicircular groove 18a corresponding to the outer peripheral surface of the metal pipe material 14 is formed on each of the surfaces where the holding members 18, 18 face each other (see FIG. 2). ), the metal pipe material 14 can be placed so as to fit into the groove 18a. Further, a tapered concave surface 18b is formed on the front surface of the holding member 18 (the surface facing the outside of the mold), the circumference of which is tapered and depressed toward the concave groove 18a. Therefore, when the metal pipe material 14 is held from above and below by the right side portion of the pipe holding mechanism 30, the structure is such that the outer periphery of the right end portion of the metal pipe material 14 can be tightly surrounded over the entire circumference. ing.

In the left side portion of the pipe holding mechanism 30, a semicircular groove 17a corresponding to the outer peripheral surface of the metal pipe material 14 is formed on each of the surfaces where the holding members 17, 17 face each other (see FIG. 2). ), the metal pipe material 14 can be placed so as to fit into the groove 17a. Furthermore, a tapered concave surface 17b is formed on the front surface of the holding member 17 (the surface facing the outside of the mold), the circumference of which is tapered and depressed toward the concave groove 17a. Therefore, when the metal pipe material 14 is held between the left side portion of the pipe holding mechanism 30 from above and below, the outer periphery of the left end portion of the metal pipe material 14 can be tightly surrounded over the entire circumference. ing.

As shown in FIG. 1, the drive mechanism 80 includes a slide 81 that moves the upper mold 12 so that the upper mold 12 and the lower mold 11 are brought together, and a shaft 82 that generates a driving force to move the slide 81. and a connecting rod 83 for transmitting the driving force generated by the shaft 82 to the slide 81. The shaft 82 extends in the left-right direction above the slide 81 and is rotatably supported, and has an eccentric crank 82a that projects from the left and right ends and extends in the left-right direction at a position apart from its axis. have. This eccentric crank 82a and a rotating shaft 81a provided at the top of the slide 81 and extending in the left-right direction are connected by a connecting rod 83. In the drive mechanism 80, the control unit 70 controls the rotation of the shaft 82 to change the height of the eccentric crank 82a in the vertical direction, and this change in the position of the eccentric crank 82a is transmitted to the slide 81 via the connecting rod 83. This allows the vertical movement of the slide 81 to be controlled. Here, the rocking (rotational movement) of the connecting rod 83 that occurs when transmitting the positional change of the eccentric crank 82a to the slide 81 is absorbed by the rotating shaft 81a. Note that the shaft 82 rotates or stops depending on the drive of a motor or the like controlled by the control unit 70, for example.

Returning to FIG. 1, each of the pair of gas supply mechanisms 40 is connected to a cylinder unit 42, a cylinder rod 43 that moves forward and backward in accordance with the operation of the cylinder unit 42, and a tip of the cylinder rod 43 on the pipe holding mechanism 30 side. and a sealing member 44. The cylinder unit 42 is mounted and fixed on the block 41. A tapered surface 45 is formed at the tip of the sealing member 44 so as to be tapered, and is configured to fit into the tapered concave surfaces 17b and 18b of the holding members 17 and 18 (see FIG. 2). The sealing member 44 has a gas passage extending from the cylinder unit 42 side toward the tip, through which high-pressure gas supplied from the gas supply section 60 flows, as shown in FIGS. 2(a) and 2(b) in detail. 46 are provided.

The gas supply unit 60 includes a gas source 61, an accumulator 62 that stores the gas supplied by the gas source 61, a first tube 63 extending from the accumulator 62 to the cylinder unit 42 of the gas supply mechanism 40, and the first tube 63. A pressure control valve 64 and a switching valve 65 are interposed in the first tube 63, a second tube 67 extends from the accumulator 62 to the gas passage 46 formed in the seal member 44, and a second tube 67 is interposed in the second tube 67. It consists of a pressure control valve 68 and a check valve 69. The pressure control valve 64 serves to supply gas to the cylinder unit 42 at an operating pressure adapted to the pressing force of the seal member 44 against the metal pipe material 14 . The check valve 69 serves to prevent high pressure gas from flowing backward within the second tube 67 . The pressure control valve 68 provided in the second tube 67 serves to supply gas having an operating pressure for expanding the metal pipe material 14 to the gas passage 46 of the sealing member 44 under the control of the control unit 70. fulfill.

The control unit 70 can supply gas at a desired operating pressure into the metal pipe material 14 by controlling the pressure control valve 68 of the gas supply unit 60. Further, the control unit 70 acquires temperature information from the thermocouple 21 by receiving information from (A) shown in FIG. 1, and controls the drive mechanism 80 and the like.

The water circulation mechanism 72 includes a water tank 73 that stores water, a water pump 74 that pumps up the water stored in the water tank 73, pressurizes it, and sends it to the cooling water passage 19 of the lower mold 11 and the cooling water passage 25 of the upper mold 12. It consists of piping 75. Although omitted, a cooling tower for lowering the water temperature or a filter for purifying the water may be interposed in the piping 75.

<Metal pipe forming method using forming equipment>
Next, a method of forming a metal pipe using the forming apparatus 10 will be explained. First, a cylindrical metal pipe material 14 of hardenable steel is prepared. This metal pipe material 14 is placed (thrown) onto holding members 17 and 18 provided on the lower mold 11 side using a robot arm or the like which will be described later. The metal pipe material 14 at the time of charging is in a state of being heated by an electrical heating device 100 described below. Since grooves 17a and 18a are formed in the holding members 17 and 18, the metal pipe material 14 is positioned by the grooves 17a and 18a.

Next, the control unit 70 causes the pipe holding mechanism 30 to hold the metal pipe material 14 by controlling the drive mechanism 80 and the pipe holding mechanism 30. Specifically, by driving the drive mechanism 80, the upper mold 12, holding members 17, 18, etc. held on the slide 81 side are moved toward the lower mold 11 side, and the holding members 17, 18, etc. included in the pipe holding mechanism 30 are moved toward the lower mold 11 side. 18 and the holding members 17, 18, etc., by operating an actuator that allows the holding members 17, 18, etc. to move forward and backward, the vicinity of both ends of the metal pipe material 14 is held by the pipe holding mechanism 30 from above and below. Due to the presence of grooves 17a and 18a formed in the holding members 17 and 18, the metal pipe material 14 is held in close contact with the entire circumference near both ends of the metal pipe material 14.

At this time, as shown in FIG. 2(a), the end of the metal pipe material 14 on the holding member 18 side is aligned with the groove 18a of the holding member 18 and the tapered concave surface in the extending direction of the metal pipe material 14. It protrudes toward the seal member 44 side from the boundary with 18b. Similarly, the end of the metal pipe material 14 on the holding member 17 side protrudes toward the sealing member 44 from the boundary between the groove 17a and the tapered concave surface 17b of the holding member 17 in the extending direction of the metal pipe material 14. There is. Further, the lower surfaces of the upper holding members 17, 18 and the upper surfaces of the lower holding members 17, 18 are in contact with each other. However, the structure is not limited to a structure in which the metal pipe material 14 is in close contact over the entire circumference of both ends, but may be a structure in which the holding members 17 and 18 are in contact with a part of the metal pipe material 14 in the circumferential direction.

Subsequently, under the control of the drive mechanism 80 by the control unit 70, the mold 13 is closed against the heated metal pipe material 14. As a result, the cavity 16 of the lower mold 11 and the cavity 24 of the upper mold 12 are combined, and the metal pipe material 14 is placed and sealed in the cavity between the lower mold 11 and the upper mold 12.

Thereafter, by operating the cylinder unit 42 of the gas supply mechanism 40, the sealing member 44 is advanced to seal both ends of the metal pipe material 14. At this time, as shown in FIG. 2(b), the sealing member 44 is pressed against the end of the metal pipe material 14 on the holding member 18 side, thereby forming a boundary between the concave groove 18a and the tapered concave surface 18b of the holding member 18. The portion that protrudes further toward the seal member 44 side is deformed into a funnel shape along the tapered concave surface 18b. Similarly, by pressing the sealing member 44 against the end of the metal pipe material 14 on the holding member 17 side, a portion protrudes toward the sealing member 44 from the boundary between the groove 17a and the tapered concave surface 17b of the holding member 17. is deformed into a funnel shape along the tapered concave surface 17b. After sealing is completed, high-pressure gas is blown into the metal pipe material 14 to shape the metal pipe material 14 softened by heating so as to follow the shape of the cavity.

Since the metal pipe material 14 is heated to a high temperature (approximately 950° C.) and softened, the gas supplied into the metal pipe material 14 thermally expands. Therefore, for example, by using compressed air as the gas to be supplied, the metal pipe material 14 at 950° C. can be easily expanded by the thermally expanded compressed air.

The outer circumferential surface of the metal pipe material 14 expanded by blow molding contacts the cavity 16 of the lower mold 11 and is rapidly cooled, and at the same time contacts the cavity 24 of the upper mold 12 and is rapidly cooled (the upper mold 12 and the lower mold 11 are Since the metal pipe material 14 has a large heat capacity and is controlled at a low temperature, when the metal pipe material 14 comes into contact with the metal pipe material, the heat on the pipe surface is immediately transferred to the mold side.) Then, quenching is performed. Such a cooling method is called mold contact cooling or mold cooling. Immediately after rapid cooling, austenite transforms into martensite (hereinafter, the transformation of austenite into martensite is referred to as martensite transformation). In the latter half of cooling, the cooling rate became low, so martensite transformed into another structure (troostite, sorbite, etc.) due to recuperation. Therefore, there is no need to perform a separate tempering treatment. Further, in this embodiment, instead of or in addition to mold cooling, cooling may be performed by supplying a cooling medium into the cavity 24, for example. For example, cooling is performed by bringing the metal pipe material 14 into contact with the mold (upper mold 12 and lower mold 11) until the temperature at which martensitic transformation begins, and then the mold is opened and the cooling medium (cooling gas) is applied to the metal pipe material. Martensitic transformation may be caused by spraying it onto 14.

After performing blow molding on the metal pipe material 14 as described above, the metal pipe material 14 is cooled and the mold is opened, thereby obtaining a metal pipe having, for example, a substantially rectangular cylindrical main body.

Next, the electrical heating device 100 according to this embodiment will be described with reference to FIGS. 3 and 4. Note that the metal pipe material 14 used in this embodiment has a curved shape in the axial direction so as to protrude entirely in the bending direction D1. Here, the metal pipe material 14 is curved in an arc shape so as to have an apex at the center in the axial direction. In the following description, the region of the metal pipe material 14 that protrudes in the bending direction D1 will be referred to as a first region E1, and the region that is recessed in the opposite direction to the bending direction D1 will be referred to as a second region E2. It is sometimes called. As shown in FIG. 4, when the metal pipe material 14 is viewed from a direction perpendicular to the bending direction D1 and the axial direction, the outer circumference side region of the curved shape of the metal pipe material 14 is the first region E1, and the inner circumference The area on the side becomes the second area E2. Note that the boundary between the first region E1 and the second region E2 is assumed to be the center position in the width direction of the metal pipe material 14 when viewed from the direction shown in FIG. The energization heating device 100 has the function of holding such metal pipe material 14 and heating it by energization. Further, the electrical heating device 100 has a function of setting the held metal pipe material 14 into the molding die 13. As shown in FIG. 4, the electrical heating device 100 includes a first electrode 101, a second electrode 102, a power supply section 103, and a control section 106. Further, as shown in FIG. 3, the electrical heating device 100 has a first position adjustment section 108 provided for the first electrode 101 and a second position adjustment section 108 provided for the second electrode 102. An adjustment section 109 is provided.

As shown in FIG. 4, the electrode 101 is a member that holds the metal pipe material 14 and energizes the metal pipe material 14 between it and the second electrode 102. The first electrode 101 includes a holding member (first portion) 101A and a holding member (second portion) 101B. The first electrode 101 is held by sandwiching the metal pipe material 14 between the holding member 101A and the holding member 101B. The first electrode 101 holds the vicinity of one end 14b of the metal pipe material 14 in the axial direction. Note that one holding member 101A is connected to a conducting wire 110 extending from the power supply section 103. Thereby, the holding member 101A can flow current to the metal pipe material 14. Note that the detailed configuration of the first electrode 101 will be described later.

The second electrode 102 is a member that holds the metal pipe material 14 at a different position from the first electrode 101 and energizes the metal pipe material 14 between the second electrode 102 and the first electrode 101 . The second electrode 102 includes a holding member 102A and a holding member 102B. The second electrode 102 is held by sandwiching the metal pipe material 14 between the holding members 102A and 102B. The second electrode 102 holds the vicinity of the other end 14c of the metal pipe material 14 in the axial direction. Note that one holding member 102A is connected to a conductive wire 111 extending from the power supply section 103.

The power supply unit 103 is a device that supplies electricity between the first electrode 101 and the second electrode 102 while holding the metal pipe material 14 between the first electrode 101 and the second electrode 102 . The power supply unit 103 includes at least a DC power supply and a switch. The power supply unit 103 is electrically connected to the holding member 101A of the first electrode 101 via a conducting wire 110, and is electrically connected to the holding member 102A of the second electrode 102 via a conducting wire 111. The control unit 106 can perform control to turn the switch of the power supply unit 103 ON/OFF. Therefore, the control unit 106 can turn on the switch of the power supply unit 103 at a predetermined timing and cause current to flow through the metal pipe material 14.

As shown in FIG. 3, the first position adjustment section 108 and the second position adjustment section 109 are configured by robot arms. For example, the first position adjustment section 108 includes a robot hand 108a that grips the metal pipe material 14, a movable section 108b that can three-dimensionally change the posture of the robot hand 108a, and a horizontal movement of the entire movable section 108b and the robot hand 108a. It includes a pedestal 108c that can be rotated in the direction. Thereby, the first position adjustment section 108 can hold the metal pipe material 14 from all angles and directions. Further, the first position adjustment unit 108 can hold the metal pipe material 14 in any posture, and can arrange the held metal pipe material 14 in any position within the range of motion. The second position adjustment section 109 has the same configuration as the first position adjustment section 108 .

The first position adjustment section 108 is provided at a position spaced apart from the second position adjustment section 109 so as to be aligned with the first position adjustment section 108 . The first position adjustment unit 108 includes a first electrode 101 at the tip of the robot hand 108a. Thereby, the first position adjustment section 108 can adjust the attachment position of the first electrode 101 with respect to the metal pipe material 14. The second position adjustment unit 109 includes a second electrode 102 at the tip of the robot hand 109a. This makes it possible to adjust the position of the metal pipe material 14 held by the first electrode.

Each of the position adjustment sections 108 and 109 can hold the metal pipe material 14 outside the molding die 13 and transport the metal pipe material 14 to install it inside the molding die 13. Note that each position adjustment section 108, 109 may be controlled by a control section 106 (see FIG. 4). Therefore, the control unit 106 can hold the metal pipe material 14 in each of the position adjustment units 108 and 109, perform electrical heating, and then place the heated metal pipe material in the molding die 13.

Next, the detailed configuration of the first electrode 101 will be described with reference to FIG. 5. FIG. 5 is a sectional view taken along line VV shown in FIG. 4. Note that the second electrode 102 has the same configuration as the first electrode 101, so a description thereof will be omitted.

As shown in FIG. 5, the holding member 101A is a block-shaped member with a substantially rectangular cross section. A groove portion 101Ab is formed on the opposing surface 101Aa that faces the holding member 101B among the side surfaces of the holding member 101A. The groove portion 101Ab has a shape corresponding to the outer circumferential surface 14a of the metal pipe material 14, and has a semicircular recessed shape. When holding the metal pipe material 14, the holding member 101A brings the groove portion 101Ab into contact with the first region E1 on the outer peripheral surface 14a of the metal pipe material 14. The holding member 101B is a block-shaped member having a substantially rectangular cross section. A groove portion 101Bb is formed on the opposing surface 101Ba that faces the holding member 101A among the side surfaces of the holding member 101B. The groove portion 101Bb has a shape corresponding to the outer circumferential surface 14a of the metal pipe material 14, and has a semicircular recessed shape. When the holding member 101B holds the metal pipe material 14, the groove portion 101Ab is brought into contact with the second region E2 on the outer peripheral surface 14a of the metal pipe material 14. Note that the shapes of the grooves 101Ab and 101Bb may be changed as appropriate to match the cross-sectional shape of the metal pipe material 14.

Here, the first electrode 101 energizes a portion of the outer circumferential surface 14 a of the metal pipe material 14 in the circumferential direction, and energizes another portion of the outer circumferential surface 14 a of the metal pipe material 14 in the circumferential direction. Do not do this. In this embodiment, the first electrode 101 energizes the first region E1 in the circumferential direction of the outer circumferential surface 14a of the metal pipe material 14, and the first region E1 in the circumferential direction of the outer circumferential surface 14a of the metal pipe material No current is applied to area E2 of No. 2. Note that the part of the first electrode 101 that conducts electricity to a part in the circumferential direction of the outer circumferential surface 14a of the metal pipe material 14 is referred to as the energized part 150A, and the other part in the circumferential direction of the outer circumferential surface 14a of the metal pipe material 14 In some cases, a portion that is not energized will be described as a non-energized portion 150B. The non-energized portion 150B is a portion that is in contact with the outer peripheral surface 14a of the metal pipe material 14 and supports the metal pipe material 14, but does not energize the metal pipe material 14.

As described above, the first electrode 101 includes a holding member 101A and a holding member 101B that are spaced apart from each other and sandwich the outer circumferential surface 14a of the metal pipe material 14 between them. The holding member 101A energizes the first region E1 in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14. The holding member 101B does not apply electricity to the second region E2 in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14. Specifically, the holding member 101A is made of a conductive material. For example, copper, aluminum, etc. are used as the conductive material. The holding member 101B is made of an insulating material. For example, ceramics, mica, asbestos, glass fiber, etc. are used as the insulating material.

With the above configuration, the holding member 101A functions as a conductive portion 121A that supports the metal pipe material 14 by contacting the first region E1 in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14. The holding member 101A allows the current flowing from the conducting wire 110 to flow into the metal pipe material 14 via the groove portion 101Ab. Alternatively, when the direction of the current is reversed, the holding member 101A allows the current flowing from the metal pipe material 14 to flow through the groove portion 101Ab to the conducting wire 110. Therefore, the holding member 101A functions as a current-carrying portion 151A for the metal pipe material 14. In addition, "energization" in this specification shall mean flowing an electric current from an electrode to a metal pipe material, and receiving an electric current from a metal pipe material. The holding member 101B functions as an insulating portion 121B that supports the metal pipe material 14 by contacting the second region E2 in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14. Further, the holding member 101B functions as a non-current-carrying portion 151B that does not apply current to the metal pipe material 14. In the example shown in FIG. 5, the entire holding member 101B is made of an insulating material, but it is sufficient that at least the portion that contacts the metal pipe material 14, that is, the groove portion 101Bb is made of an insulating material. For example, the entire surface of the holding member 101B made of a conductive material may be coated with an insulating material.

Next, an electrical heating method using the electrical heating device 100 described above will be described.

First, a process of preparing a metal pipe material 14 bent so as to protrude in the bending direction D1 as shown in FIG. 4 is performed. Next, the metal pipe material 14 is connected to the first electrode 101 and the second electrode so that a portion of the outer circumferential surface 14a of the metal pipe material 14 on the protruding side of the bend in the circumferential direction (first region E1) is energized. A step of arranging the electrode 102 is performed. In this step, the first region E1 of the outer peripheral surface 14a of the metal pipe material 14 is brought into contact with the groove portion 101Ab of the holding member 101A of the first electrode 101. Further, in this step, the second region E2 of the outer circumferential surface 14a of the metal pipe material 14 is brought into contact with the groove portion 101Bb of the holding member 101B of the first electrode 101. In this manner, the first electrode 101 holds the metal pipe material 14 with the holding members 101A and 101B. The second electrode 102 also holds the metal pipe material 14 in the same manner as the first electrode 101 . Next, a step is performed in which the metal pipe material 14 is heated with electricity using the first electrode 101 and the second electrode 102. In this step, among the first electrodes 101, only the holding member 101A is energized to the metal pipe material 14, and the holding member 101B is not energized. Among the second electrodes 102, only the holding member 102A is energized to the metal pipe material 14, and the holding member 102B is not energized.

Next, the functions and effects of the energization heating device 100 and the energization heating method according to the present embodiment will be explained.

According to the electrical heating device 100 according to the present embodiment, the electrodes 101 and 102 energize a portion of the outer circumferential surface 14a of the metal pipe material 14 in the circumferential direction, and No current is applied to other parts in the direction. Therefore, the metal pipe material 14 is arranged with respect to the electrodes 101 and 102 so that electricity is applied to a portion of the outer circumferential surface 14a of the metal pipe material 14 on the protruding side of the bend in the circumferential direction (first region E1). be able to. When arranged in this way, the current is applied to the bent protruding side (first region E1) of the metal pipe material 14, which has a long current path and is difficult to heat, and the current is applied to the part where the current path is short and is easily heated. No current is applied to the concave side (second region E2) of a certain metal pipe material. This prevents the current from flowing in a concentrated manner on the bent side of the metal pipe material 14, thereby suppressing an increase in the amount of heat generated at that position. As described above, it is possible to reduce unevenness in the temperature distribution in the axial direction of the metal pipe material 14 during heating.

In the electrical heating device 100, the electrodes 101 and 102 include holding members 101A and 102A and holding members 101A and 101B that are spaced apart from each other and sandwich the outer circumferential surface 14a of the metal pipe material 14 between them. The holding members 101A and 102A energize a portion (first region E1) of the outer circumferential surface 14a of the metal pipe material 14 in the circumferential direction, and the holding members 101B and 102B energize the portion (first region E1) of the outer circumferential surface 14a of the metal pipe material 14 in the circumferential direction. No current is applied to the other portion (second region E2). As a result, the parts of the metal pipe material 14 that are energized can be supported by the holding members 101A and 102A, and the parts that are not energized can be supported by the holding members 101B and 102B. 14 is easy to align.

In the electrical heating device 100, the electrodes 101 and 102 include a conductive portion 121A that supports the metal pipe material 14 by contacting a portion (first region E1) in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14; An insulating portion 121B that supports the metal pipe material 14 by contacting another portion (second region E2) in the circumferential direction of the outer peripheral surface 14a of the material 14 is provided. In this way, by providing the conductive part 121A and the insulating part 121B, the energized part 151A is energized and the non-energized part 151B is not energized (for example, the energized part can be switched as shown in FIGS. (compared to conventional configurations).

The current heating method according to the present embodiment is a current heating method in which the metal pipe material 14 is heated by applying current to it using the above-described current heating device 100, and the metal pipe material 14 is bent so as to protrude in the bending direction D1. The metal pipe material 14 is connected to the electrodes 101 and 102 so that a part (first region E1) of the outer circumferential surface 14a of the metal pipe material 14 on the bending protruding side in the circumferential direction is energized. and a step of energizing and heating the metal pipe material 14 with electrodes 101 and 102.

According to the energization heating method according to the present embodiment, the same actions and effects as those of the energization heating device 100 described above can be obtained.

The invention is not limited to the embodiments described above.

For example, the electrode may have a conductive part and an insulating part in one holding member. The electrode 200 shown in FIG. 6 includes holding members 200A and 200B. In the following description, the direction in which the holding members 200A and 200B face each other will be referred to as a facing direction D2, and the direction perpendicular to the facing direction D2 and the axial direction will be referred to as a width direction D3. The holding members 200A, 200B include conductive parts 201A, 201B made of a conductive material on one side in the width direction D3, and insulating parts 202A, 202B made of an insulating material on the other side in the width direction D3. There is. Conductive wire 110 is connected to conductive portion 201A. In this case, the conductive portion 201A and the conductive portion 201B are electrically connected to each other via the opposing surfaces 201Aa and 201Ba. However, the conducting wire 110 may be connected to the conductive part 201B, or may be connected to both the conductive part 201A and the conductive part 201B. With the above configuration, the conductive parts 201A and 201B function as a current-carrying part 251A that supplies current to the metal pipe material 14. The insulating parts 202A and 202B function as a non-current-carrying part 251B that does not apply current to the metal pipe material 14.

Such an electrode 200 supplies current to a portion of the outer peripheral surface 14a of the metal pipe material 14 in the circumferential direction at the conductive parts 201A and 201B, and conducts current to a part of the outer peripheral surface 14a of the metal pipe material 14 at the insulating parts 202A and 202B. No current is applied to other portions of the surface 14a in the circumferential direction. Therefore, it is possible to arrange the metal pipe material 14 with respect to the electrode 200 so that a portion (first region E1) of the outer circumferential surface 14a of the metal pipe material 14 on the protruding side of the bend in the circumferential direction is energized. can. Here, the metal pipe material 14 is arranged such that a first region E1 and a second region E2 face each other in the width direction D3, and the first region E1 contacts the conductive parts 201A and 201B, and the second region E1 contacts the conductive parts 201A and 201B. Region E2 contacts insulating parts 202A and 202B. When arranged in this way, the current is applied to the bent protruding side (first region E1) of the metal pipe material 14, which has a long current path and is difficult to heat, and the current is applied to the part where the current path is short and is easily heated. No current is applied to the concave side (second region E2) of a certain metal pipe material. This prevents the current from flowing in a concentrated manner on the bent side of the metal pipe material 14, thereby suppressing an increase in the amount of heat generated at that position. As described above, it is possible to reduce unevenness in the temperature distribution in the axial direction of the metal pipe material 14 during heating.

Further, the electrode 200 includes conductive parts 201A and 201B that support the metal pipe material 14 by contacting a portion (first region E1) in the circumferential direction of the outer peripheral surface 14a of the metal pipe material 14, and the outer periphery of the metal pipe material 14. Insulating portions 202A and 202B are provided that support the metal pipe material 14 by contacting another portion (second region E2) of the surface 14a in the circumferential direction. In this way, by providing the conductive parts 201A, 201B and the insulating parts 202A, 202B, the energized part 251A that is energized and the non-energized part 251B that is not energized (for example, as shown in FIGS. 7 and 8 described below) (compared to a configuration in which parts are switched) can be configured easily.

Further, for example, the electrode may be configured to be switchable between a energized portion and a non-energized portion within one holding member. The electrode 300 shown in FIG. 7 includes holding members 300A and 300B. The holding members 300A, 300B have conductive parts 301A, 301B made of a conductive material on one side in the width direction D3, conductive parts 302A, 302B made of a conductive material on the other side in the width direction D3, and a conductive part 302A, 302B made of a conductive material on the other side in the width direction D3. An insulating part 303A made of an insulating material between the conductive parts 301A and 302A at a central position in the width direction D3, and an insulating part 303B made of an insulating material between the conductive parts 301B and 302B at a central position in the width direction D3. There is.

The conducting wire 110 is branched into a branch portion 110a and a branch portion 110b. Further, a switch 112 is provided at the branch portion 110a, and a switch 113 is provided at the branch portion 110b. Branch portion 110a is connected to conductive portion 301A, and branch portion 110b is connected to conductive portion 302A. In this case, the conductive portion 301A and the conductive portion 301B are electrically connected to each other via the opposing surfaces 301Aa and 301Ba. The conductive portion 302A and the conductive portion 302B are electrically connected to each other via their opposing surfaces 302Aa and 302Ba.

The electrode 300 having the above configuration can switch between the energized portion 351A and the non-energized portion 351B. For example, when the switch 112 is turned on and the switch 113 is turned off as shown in FIG. It functions as 351B. Further, when the switch 112 is turned OFF and the switch 113 is turned ON, the conductive parts 302A and 302B function as a current-carrying part 351A, and the conductive parts 301A and 301B and the insulating parts 303A and 303B function as a non-current-carrying part 351B.

When the switch 112 is turned on and the switch 113 is turned off, such an electrode 300 energizes a portion of the outer circumferential surface 14a of the metal pipe material 14 in the circumferential direction at the conductive parts 301A and 301B, and The conductive parts 302A and 302B do not apply current to other parts in the circumferential direction of the outer circumferential surface 14a of the metal pipe material 14. Therefore, it is possible to arrange the metal pipe material 14 with respect to the electrode 300 so that the part (first region E1) of the outer circumferential surface 14a of the metal pipe material 14 on the protruding side of the bend in the circumferential direction is energized. can. Here, the metal pipe material 14 is arranged such that a first region E1 and a second region E2 face each other in the width direction D3, the first region E1 contacts the conductive parts 301A and 301B, and the second region E1 contacts the conductive parts 301A and 301B. Region E2 contacts conductive parts 302A and 302B. When arranged in this way, the current is applied to the bent protruding side (first region E1) of the metal pipe material 14, which has a long current path and is difficult to heat, and the current is applied to the part where the current path is short and is easily heated. No current is applied to the concave side (second region E2) of a certain metal pipe material. This prevents the current from flowing in a concentrated manner on the bent side of the metal pipe material 14, thereby suppressing an increase in the amount of heat generated at that position. As described above, it is possible to reduce unevenness in the temperature distribution in the axial direction of the metal pipe material 14 during heating.

Furthermore, by switching the switches 112 and 113, the positions of the energized portion 351A and the non-energized portion 351B can be switched. That is, when the switch 112 is turned OFF and the switch 113 is turned ON from the state shown in FIG. 7, the conductive parts 302A and 302B become the current-carrying part 351A. In this case, the metal pipe material 14 is arranged with respect to the electrode 300 so that the first region E1 contacts the conductive parts 302A, 302B, and the second region E2 contacts the conductive parts 301A, 301B. By providing such a switching mechanism, after the metal pipe material 14 is held by the electrode 300, the energized portion 351A and the non-energized portion 351B can be set.

Further, as shown in FIG. 8, an electrode 400 having more switching patterns may be employed. The electrode 400 shown in FIG. 8 includes holding members 400A and 400B. The electrode 400 shown in FIG. 8 includes conductive parts 401A, 401B, 402A, 402B, and insulating parts 403A, which have the same meaning as the conductive parts 301A, 301B, 302A, 302B, and insulating parts 303A, 303B of the electrode 300 in FIG. 403B. Furthermore, the electrode 400 includes an insulating part 404A provided on the opposite surface of the conductive part 401A, an insulating part 404B provided on the opposite surface of the conductive part 401B, and an insulating part 406A provided on the opposite surface of the conductive part 402A. , and an insulating section 406B provided on the opposite surface of the conductive section 402B. With such a configuration, when the metal pipe material 14 is held, the conductive parts 401A, 401B, 402A, and 402B are insulated from each other.

The conducting wire 110 has a branch portion 110a having a switch 112, a branch portion 110b having a switch 113, a branch portion 110c having a switch 114, and a branch portion 110d having a switch 115. Branch portion 110a is connected to conductive portion 401A, branch portion 110b is connected to conductive portion 402A, branch portion 110c is connected to conductive portion 401B, and branch portion 110d is connected to conductive portion 402B.

The electrode 400 having the above configuration can switch between the energized portion 451A and the non-energized portion 451B. For example, when switches 112 and 113 are turned on and switches 114 and 115 are turned off as shown in FIG. , 404A, 404B, 406A, and 406B function as a non-current-carrying portion 351B. Further, when the switches 114 and 115 are turned ON and the switches 112 and 113 are turned OFF, the conductive parts 401B and 402B function as the current-carrying part 351A, and the conductive parts 401A and 402A and the insulating parts 403A, 403B, 404A, 404B, 406A , 406B function as the non-current-carrying portion 351B. Further, when the switches 112 and 114 are turned ON and the switches 113 and 115 are turned OFF, the conductive parts 401A and 401B function as the current-carrying part 351A, and the conductive parts 402A and 402B and the insulating parts 403A, 403B, 404A, 404B, 406A , 406B function as the non-current-carrying portion 351B. Further, when the switches 113 and 115 are turned on and the switches 112 and 114 are turned off, the conductive parts 402A and 402B function as the current-carrying part 351A, and the conductive parts 401A and 401B and the insulating parts 403A, 403B, 404A, 404B, 406A , 406B function as the non-current-carrying portion 351B.

When the switches 112 and 113 are turned on and the switches 114 and 115 are turned off, such an electrode 400 conducts electricity to a portion of the outer peripheral surface 14a of the metal pipe material 14 in the circumferential direction at the conductive parts 401A and 402A. At the same time, the conductive parts 401B and 402B do not energize other parts in the circumferential direction of the outer circumferential surface 14a of the metal pipe material 14. Therefore, it is possible to arrange the metal pipe material 14 with respect to the electrode 300 so that the part (first region E1) of the outer circumferential surface 14a of the metal pipe material 14 on the protruding side of the bend in the circumferential direction is energized. can. Here, the metal pipe material 14 is arranged such that the first region E1 and the second region E2 face each other in the opposing direction D2, the first region E1 contacts the conductive parts 401A and 402A, and the second region E1 contacts the conductive parts 401A and 402A, and the second region E2 Region E2 contacts conductive parts 401B and 402B. When arranged in this way, the current is applied to the bent protruding side (first region E1) of the metal pipe material 14, which has a long current path and is difficult to heat, and the current is applied to the part where the current path is short and is easily heated. No current is applied to the concave side (second region E2) of a certain metal pipe material. This prevents the current from flowing in a concentrated manner on the bent side of the metal pipe material 14, thereby suppressing an increase in the amount of heat generated at that position. As described above, it is possible to reduce unevenness in the temperature distribution in the axial direction of the metal pipe material 14 during heating.

Furthermore, by turning ON/OFF the switches 112, 113, 114, and 115, the positions of the energized portion 451A and the non-energized portion 451B of the electrode 400 can be switched. Therefore, depending on the arrangement of the metal pipe material 14, the energized portion 451A and the non-energized portion 451B are arranged such that the first region E1 contacts the energized portion 451A and the second region E2 contacts the non-energized portion 451B. You can switch positions.

Note that the shape of the metal pipe material is not limited to the above-mentioned shape. For example, the metal pipe material may be bent rather than curved.

Although the above-described energization heating device has a configuration including an electrode and a position adjustment section, it may not have a position adjustment section. That is, an electrode having the same configuration as described above may be provided on the molding device side. In this case, when installing the metal pipe material in the forming apparatus, the electrodes and the metal pipe material are aligned.

100... Electrical heating device, 101, 102, 200, 300, 400... Electrode, 103... Power supply unit, 101A, 102A, 200A, 300A, 400A... Holding member (first part), 101B, 102B, 200B, 300B , 400B... Holding member (second part) 121A, 201A, 201B, 301A, 301B, 302A, 302B, 401A, 401B, 402A, 402B... Conductive part, 121B, 202A, 202B, 303A, 303B, 403A, 403B, 404A, 404B, 406A, 406B...Insulating section.

Claims (4)

An energization heating device that heats a metal pipe material by energizing it,
comprising an electrode that supplies power in contact with the outer peripheral surface of the metal pipe material,
The electrode is
An electrical heating device that energizes a portion of the outer circumferential surface of the metal pipe material in the circumferential direction, and does not energize the other circumferential portion of the outer circumferential surface of the metal pipe material. The electrode includes a first portion and a second portion that are spaced apart from each other and sandwich the outer peripheral surface of the metal pipe material,
The first portion energizes the portion in the circumferential direction of the outer peripheral surface of the metal pipe material,
The electrical heating device according to claim 1, wherein the second portion does not apply electricity to the other portion in the circumferential direction of the outer circumferential surface of the metal pipe material. The electrode is
a conductive part that supports the metal pipe material by contacting the part in the circumferential direction of the outer peripheral surface of the metal pipe material;
The electrical heating device according to claim 1 or 2, further comprising: an insulating section that supports the metal pipe material by contacting the other portion in the circumferential direction of the outer peripheral surface of the metal pipe material. An energization heating method in which the metal pipe material is heated by energizing it using the energization heating device according to any one of claims 1 to 3,
preparing the metal pipe material bent so as to protrude in the bending direction;
arranging the metal pipe material relative to the electrode so that a portion of the outer peripheral surface of the metal pipe material on the protruding side of the bend in the circumferential direction is energized;
An electrical heating method comprising the step of electrically heating the metal pipe material with the electrode.

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