JP2020073285A - Molding device - Google Patents

Abstract

To provide a molding device capable of improving safety.SOLUTION: According to a molding device 10 on the present embodiment, the movement of a metal mold 13 by electromagnetic force can be restrained by switching the direction of a direct current of flowing in a metal pipe material, with a simple constitution by switching of operation of an electromagnetic switch MC1 and an electromagnetic switch MC2. That is, even when having a mechanism for heating the metal pipe material 14 by electric conduction by a first electrode 17 and a second electrode 18, the movement of the metal mold 13 to the metal pipe material 14 side by the electromagnetic force can be restrained. Thereby, safety can be improved by preventing the occurrence of electric leakage by contacting the metal mold 13 and the metal pipe material 14 in electric conduction heating.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a molding device.

  2. Description of the Related Art Conventionally, there has been known a molding device that blow-molds a metal pipe by closing the mold with a mold. For example, the molding device disclosed in Patent Document 1 includes a mold and a gas supply unit that supplies gas into the metal pipe material. In this molding apparatus, the metal pipe material is placed in the mold, and the metal pipe material is expanded by supplying gas from the gas supply unit to the metal pipe material with the mold closed. Mold into a shape that corresponds to the shape. In this molding apparatus, the metal pipe material is held by the electrode and the metal pipe material is electrically heated by the electrode before the metal pipe material is expanded.

JP, 2012-000654, A

  Here, in the above-described molding apparatus, when the metal pipe material is electrically heated by the electrodes, the mold and members around the mold may be magnetized. In such a case, during the electric heating of the metal pipe material, an electromagnetic force may be applied to the magnetized mold so that the mold moves in the sliding direction, which is the direction in which the mold moves. When the mold moves due to the action of this electromagnetic force and the metal pipe material is being heated by energization, electric leakage may occur through the mold, and the device may be damaged.

  The present invention has been made to solve such a problem, and an object thereof is to provide a molding apparatus capable of improving safety.

  A molding apparatus according to the present invention is a molding apparatus for expanding a metal pipe material to mold a metal pipe, at least one of which is movable, and a mold having an upper mold and a lower mold for molding the metal pipe, A pair of electrodes that heat the metal pipe material by heating the metal pipe material, an electric power supply unit that supplies electric power to the pair of electrodes, and a gas supply that supplies gas into the heated metal pipe material to expand it. And a section. The power supply unit is connected to a DC current generating unit that generates a DC current, a first power supply side line connected to the positive output terminal of the DC current generating unit, and a negative output terminal of the DC current generating unit. A second power source side line, a first electrode side line connected to one electrode of the pair of electrodes, a second electrode side line connected to the other electrode of the pair of electrodes, and an operation In doing so, it is possible to electrically connect the first power supply side line and the first electrode side line and to electrically connect the second power supply side line and the second electrode side line. The first electromagnetic switch and the first power supply side line and the second electrode side line are electrically connected to each other when operated, and the second power supply side line and the first electrode side line are electrically connected. Second electromagnetic switch capable of being connected to the first electromagnetic switch, first electromagnetic switch and second electromagnetic switch Either one and a control section for controlling to operate.

  According to the molding apparatus of the present invention, the direction of the direct current flowing through the metal pipe material can be switched with a simple configuration by switching the operations of the first electromagnetic switch and the second electromagnetic switch. Therefore, the magnetization of the mold can be reduced, and the movement of the mold due to the action of the electromagnetic force can be suppressed. This can improve safety.

  A molding apparatus according to the present invention is a molding apparatus for expanding a metal pipe material to mold a metal pipe, at least one of which is movable, and a mold having an upper mold and a lower mold for molding the metal pipe, A pair of electrodes that heat the metal pipe material by heating the metal pipe material, a power supply unit that supplies electric power to the electrodes, and a gas supply unit that supplies gas into the heated metal pipe material to expand the gas. , Is provided. The power supply unit includes an AC power supply that generates an AC current, a first electrode side line connected to one electrode of the pair of electrodes, and a second electrode side line connected to the other electrode of the pair of electrodes. When an alternating current is supplied, the electrode side line converts the current into a direct current and outputs it. The positive side output end is connected to the first electrode side line and the negative side output end is the second electrode side line. When the AC current is supplied to the first rectifier, the DC voltage is converted into a DC current for output, and the positive output terminal is connected to the second electrode side line, and the negative output terminal is connected to the second electrode side line. A second rectifier connected to the first electrode side line; and a first electromagnetic switch capable of electrically connecting an AC power supply and the first rectifier when operating, and a second rectifier operating when operating. A second electromagnetic switch capable of electrically connecting the AC power supply and the second rectifier; One of the electromagnetic switch and the second electromagnetic switch having a control unit for controlling to operate.

  According to the molding apparatus of the present invention, the direction of the direct current flowing through the metal pipe material can be switched with a simple configuration by switching the operations of the first electromagnetic switch and the second electromagnetic switch. Therefore, the magnetization of the mold can be reduced, and the movement of the mold due to the action of the electromagnetic force can be suppressed. This can improve safety.

  As described above, according to the present invention, the safety of the molding apparatus can be improved.

It is a schematic block diagram which shows the shaping | molding apparatus which concerns on 1st Embodiment and 2nd Embodiment of this invention. FIG. 2 is a cross-sectional view of a blow molding die, an upper die, and a lower die holding portion taken along line II-II of FIG. 1. It is an enlarged view of the electrode periphery, (a) is a figure which shows the state which the electrode hold | maintained the metal pipe material, (b) is a figure which shows the state which the sealing member contacted to the electrode, (c) is the front of the electrode It is a figure. It is a figure which shows the manufacturing process by a shaping | molding apparatus, (a) is a figure which shows the state in which the metal pipe material was set in the metal mold | die, (b) is a figure which shows the state in which the metal pipe material was hold | maintained at the electrode. is there. It is a figure which shows the manufacturing process following FIG. It is a figure which shows operation | movement of a blow molding die and an upper mold holder, and the change of the shape of a metal pipe material. It is a figure following FIG. It is a figure following FIG. It is a schematic block diagram which shows the electric power supply part of the shaping | molding apparatus which concerns on 1st Embodiment of this invention. It is a schematic block diagram which shows the electric power supply part of the shaping | molding apparatus which concerns on 2nd Embodiment of this invention.

  Hereinafter, preferred embodiments of a molding apparatus according to the present invention will be described with reference to the drawings. In each figure, the same or corresponding parts will be denoted by the same reference symbols, without redundant description.

[First Embodiment]
<Structure of molding equipment>
FIG. 1 is a schematic configuration diagram of a molding apparatus, and FIG. 2 is a cross-sectional view of a blow molding die, an upper die, and a lower die holding portion taken along line II-II of FIG. As shown in FIG. 1, a molding apparatus 10 for molding a metal pipe 100 (see FIG. 5) holds a blow mold 13 composed of a lower mold 11 and an upper mold 12 which are paired with each other, and a lower mold 11. At least one of the lower die holding portion 91 for holding and the upper die holding portion 92 for holding the upper die 12, and the lower die holding portion 91 holding the lower die 11 and the upper die holding portion 92 holding the upper die 12 ( Here, a drive mechanism 80 for moving the upper die holding part 92), a pipe holding mechanism 30 for holding the metal pipe material 14 indicated by an imaginary line between the lower die 11 and the upper die 12, and a pipe holding mechanism 30. A heating mechanism 50 for energizing and heating the held metal pipe material 14 and a high-pressure gas (gas) for supplying into the heated metal pipe material 14 held between the lower mold 11 and the upper mold 12. Gas supply unit 60 and pipe holder A pair of gas supply mechanisms (gas supply units) 40, 40 for supplying gas from the gas supply unit 60 into the metal pipe material 14 held by 30, and water circulation forcibly cooling the blow molding die 13 with water. And a mechanism 72. The molding apparatus 10 according to this embodiment includes a lower mold drive mechanism 90 that drives the lower mold 11 up and down. Further, the molding apparatus 10 controls the drive of the drive mechanism 80, the drive of the lower mold drive mechanism 90, the drive of the pipe holding mechanism 30, the drive of the heating mechanism 50, and the gas supply of the gas supply unit 60. And a control unit 70.

  The lower die 11 is fixed to the large base 15 via the lower die holding portion 91. The lower die 11 is composed of a large steel block and has a recess 16 on its upper surface (divided surface with the upper die 12). As shown in FIGS. 1 and 2, the lower mold holding portion 91 that holds the lower mold 11 holds the first lower die holder 93 that holds the lower mold 11 and the first lower die holder 93 in order from the top. A second lower die holder 94 and a lower die base plate 95 holding the second lower die holder 94 are provided in an overlapping manner, and the lower die base plate 95 is fixed to the base 15. As shown in FIG. 1, the axial lengths of the first lower die holder 93 and the second lower die holder 94 (horizontal length in FIG. 1) are approximately the same as the axial length of the lower die 11. It has become.

  Further, an electrode storage space 11a is provided near the left and right ends (left and right ends in FIG. 1) of the lower mold 11, and a pair of vertically movable actuators (not shown) are arranged in the electrode storage space 11a. Of the electrodes (first electrode 17 and second electrode 18). On the upper surfaces of the first electrode 17 and the second electrode 18, semicircular arc-shaped grooves 17a and 18a corresponding to the lower outer peripheral surface of the metal pipe material 14 are formed (see FIG. 3C). The metal pipe material 14 can be placed so that the metal pipe material 14 is just fitted into the concave grooves 17a and 18a. In addition, the front surfaces of the first and second electrodes 17 and 18 (the surfaces in the outer direction of the mold) are formed with tapered concave surfaces 17b and 18b, which are recessed by tapering the periphery toward the concave grooves 17a and 18a. There is. A cooling water passage 19 is formed in the lower mold 11. On the lower surface side of the lower die 11, a lower die drive mechanism 90 that penetrates the second lower die holder 94 and the lower die base plate 95 and extends in the vertical direction is provided. The lower die driving mechanism 90 includes a support portion 101 that supports the lower surface of the lower die 11, and a shaft portion 102 that extends downward from the support portion 101. The lower end side of the shaft portion 102 is connected to a drive unit (not shown).

  The pair of first and second electrodes 17 and 18 located on the lower die 11 side constitutes a pipe holding mechanism 30, and the metal pipe material 14 can be moved up and down between the upper die 12 and the lower die 11. Can be supported by. The molding apparatus 10 is provided with a thermocouple (not shown) for measuring the temperature of the metal pipe material 14. For example, the thermocouple may be inserted from the side of the mold 13. However, the thermocouple is merely an example of the temperature measuring means, and may be a non-contact type temperature sensor such as a radiation thermometer or an optical thermometer. It should be noted that if the correlation between the energization time and the temperature is obtained, the temperature measuring means may be omitted.

  The upper die 12 is a large steel block having a recess 24 on its lower surface (divided surface with the lower die 11) and having a cooling water passage 25 built therein. As shown in FIGS. 1 and 2, the upper die holding portion 92 that holds the upper die 12 holds the first upper die holder 96 that holds the upper die 12 and the first upper die holder 96 in order from the bottom. A second upper die holder 97 and an upper die base plate 98 that holds the second upper die holder 97 are provided in an overlapping manner, and the upper die base plate 98 is fixed to the slide 82. As shown in FIG. 1, the axial lengths of the first upper die holder 96 and the second upper die holder 97 (horizontal length in FIG. 1) are substantially the same as the axial length of the upper die 12. It has become. The slide 82 to which the upper die holding portion 92 is fixed is configured to be hung by the pressure cylinder 26, and is guided by the guide cylinder 27 so as not to shake laterally.

  An electrode housing space 12a similar to that of the lower mold 11 is provided near the left and right ends (left and right ends in FIG. 1) of the upper mold 12, and an actuator (not shown) is provided in the electrode housing space 12a, like the lower mold 11. ) Is provided with a first electrode 17 and a second electrode 18 configured to be able to move up and down. On the lower surfaces of these first and second electrodes 17 and 18, there are formed semicircular arc-shaped grooves 17a and 18a corresponding to the upper outer peripheral surface of the metal pipe material 14 (see FIG. 3 (c)). The metal pipe material 14 can be fitted into the concave grooves 17a and 18a. In addition, the front surfaces of the first and second electrodes 17 and 18 (the surfaces in the outer direction of the mold) are formed with tapered concave surfaces 17b and 18b, which are recessed by tapering the periphery toward the concave grooves 17a and 18a. There is. Therefore, the pair of first and second electrodes 17 and 18 located on the upper die 12 side also constitutes the pipe holding mechanism 30, and the metal pipe material 14 is vertically moved by the pair of upper and lower first and second electrodes 17 and 18. When sandwiched from the direction, the outer circumference of the metal pipe material 14 can be surrounded so as to be in close contact with the entire circumference. The fixed portions of the actuators that move the first electrode 17 and the second electrode 18, which are movable portions, up and down are held and fixed by the lower die holding portion 91 and the upper die holding portion 92, respectively.

  The drive mechanism 80 includes a slide 82 that moves the upper die 12 and the upper die holding portion 92 so that the upper die 12 and the lower die 11 are aligned with each other, and a drive portion 81 that generates a driving force for moving the slide 82. , And a servo motor 83 that controls the amount of fluid with respect to the drive unit 81. The drive unit 81 is configured by a fluid supply unit that supplies a fluid for driving the pressurizing cylinder 26 (operating oil when a hydraulic cylinder is used as the pressurizing cylinder 26) to the pressurizing cylinder 26.

  The control unit 70 can control the movement of the slide 82 by controlling the servo motor 83 of the drive unit 81 to control the amount of fluid supplied to the pressurizing cylinder 26. The drive unit 81 is not limited to the one that applies the drive force to the slide 82 via the pressurizing cylinder 26 as described above. For example, the drive unit is mechanically connected to the slide 82 to generate the servo motor 83. The driving force for driving may be directly or indirectly applied to the slide 82. For example, an eccentric shaft, a drive source (for example, a servomotor and a speed reducer) that applies a rotational force that rotates the eccentric shaft, and a conversion unit that converts the rotational motion of the eccentric shaft into a linear motion to move the slide (for example, , A connecting rod, an eccentric sleeve, or the like). In addition, in the present embodiment, the drive unit 81 may not include the servo motor 83.

  As shown in FIG. 2, a step is provided on both the upper end surface of the lower mold 11 and the lower end surface of the upper mold 12. Specifically, a recess 16 having a rectangular cross section is formed in the center of the upper end surface of the lower mold 11, and a cross section is formed at a position facing the recess 16 of the lower mold 11 at the center of the lower end surface of the upper mold 12. A rectangular recess 24 is formed.

  The first lower die holder 93, which constitutes the lower die holding portion 91 and holds the lower die 11, is provided with a recess 93a having a rectangular cross section at the center of the upper end surface 93e of the rectangular parallelepiped. A substantially lower half of the lower mold 11 is fitted and held in a gap 93c which is provided in the center and divides the first lower die holder 93. Between the convex portions 93b, 93b on both sides forming the concave portion 93a of the first lower die holder 93, and the side surface of the substantially upper half of the lower mold 11 protruding above the bottom surface 93d of the first lower die holder 93. Are provided with spaces S1 and S2, respectively, and these spaces S1 and S2 are spaces into which a convex portion 96b of the first upper die holder 96 described later enters when the blow molding die 13 is closed.

  The first upper die holder 96, which constitutes the upper die holding portion 92 and holds the upper die 12, forms two stepwise steps from the upper side to the lower side on both sides of the rectangular parallelepiped so that the rectangular parallelepiped faces downward. Is configured in a stepped block shape that gradually decreases. A recess 96a having a rectangular cross section is formed in the center of the lower end surface 96d of the first upper die holder 96, and the upper die 12 is held in the recess 96a so as to be housed therein. Therefore, the inner side surfaces of the respective convex portions 96b, 96b on both sides forming the concave portion 96a of the first upper die holder 96 are in contact with the side surfaces of the upper die 12. Further, the convex portions 96b and 96b project below the lower end surface of the upper die 12 by a predetermined length, and enter the spaces S1 and S2 of the first lower die holder 93 when the blow molding die 13 is closed. Has become. Further, when the blow molding die 13 is closed, the lower end surface (tip surface) 96d of the convex portion 96b of the first upper die holder 96 contacts the bottom surface 93d of the concave portion 93a of the first lower die holder 93, The stepped surface 96e formed on both sides of the convex portion 96b of the first upper die holder 96 and located above the convex portion 96b contacts the upper end surface 93e of the convex portion 93b of the first lower die holder 93. I have come into contact with them.

  As shown in FIG. 1, the heating mechanism 50 includes a first electrode 17 and a second electrode 18, a power source 51, and conductive wires extending from the power source 51 and connected to the first electrode 17 and the second electrode 18, respectively. 52 and a switch 53 provided on the conducting wire 52. The control unit 70 can heat the metal pipe material 14 to the quenching temperature (AC3 transformation point temperature or higher) by controlling the heating mechanism 50.

  Each of the pair of gas supply mechanisms 40 includes a cylinder unit 42, a cylinder rod 43 that moves back and forth according to the operation of the cylinder unit 42, and a seal member 44 connected to the tip of the cylinder rod 43 on the pipe holding mechanism 30 side. , With. The cylinder unit 42 is mounted and fixed on the base 15 via the block 41. A taper surface 45 is formed at the tip of the seal member 44 so as to be tapered, and is formed in a shape capable of being fitted and abutted with the taper concave surfaces 17b and 18b of the first and second electrodes 17 and 18, respectively. (See Figure 3). The seal member 44 extends from the cylinder unit 42 side toward the tip, and more specifically, as shown in FIGS. 3A and 3B, a gas passage through which the high-pressure gas supplied from the gas supply unit 60 flows. 46 is provided.

  As shown in FIG. 1, the gas supply unit 60 extends from a high-pressure gas source 61, an accumulator 62 that stores the gas supplied by the high-pressure gas source 61, and from the accumulator 62 to a cylinder unit 42 of the gas supply mechanism 40. The first tube 63, the pressure control valve 64 and the switching valve 65 interposed in the first tube 63, and the second tube extending from the accumulator 62 to the gas passage 46 formed in the seal member 44. 67, and a pressure control valve 68 and a check valve 69 provided on the second tube 67. The pressure control valve 64 serves to supply the cylinder unit 42 with a gas having an operating pressure adapted to the pressing force of the seal member 44 against the metal pipe material 14. The check valve 69 plays a role of preventing the high-pressure gas from flowing backward in the second tube 67.

  The control unit 70 can supply the gas having 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 a thermocouple (not shown) and controls the pressurizing cylinder 26, the switch 53, 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 accumulated 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, And a pipe 75. Although omitted, a cooling tower for lowering the water temperature and a filter for purifying water may be provided in the pipe 75.

<Molding method of metal pipe using molding machine>
Next, a method of molding a metal pipe using the molding device 10 will be described. FIG. 4 shows from a pipe charging step of charging the metal pipe material 14 as a material to an electric heating step of heating the metal pipe material 14 by energizing it. More specifically, FIG. 4A is a diagram showing a state where the metal pipe material is set in the mold, and FIG. 4B is a diagram showing a state where the metal pipe material is held by the electrodes. Further, FIG. 5 is a diagram showing a manufacturing process following FIG.

  First, a quenchable steel type metal pipe material 14 is prepared. As shown in FIG. 4A, this metal pipe material 14 is placed (input) on the first and second electrodes 17 and 18 provided on the lower mold 11 side by using, for example, a robot arm. Since the concave grooves 17a and 18a are formed in the first and second electrodes 17 and 18, the metal pipe material 14 is positioned by the concave grooves 17a and 18a. Next, the control unit 70 (see FIG. 1) controls the pipe holding mechanism 30 to cause the pipe holding mechanism 30 to hold the metal pipe material 14. Specifically, as shown in FIG. 4B, an actuator (not shown) that allows the first electrode 17 and the second electrode 18 to move back and forth is actuated, and the first and second electrodes 17 located above and below , 18 are brought into close contact with each other. By this contact, both ends of the metal pipe material 14 are sandwiched by the first and second electrodes 17 and 18 from above and below. Further, the holding is carried out by the existence of the concave grooves 17a, 18a formed in the first and second electrodes 17, 18 in such a manner that the metal pipe material 14 is in close contact with the entire circumference thereof. ..

  Subsequently, as shown in FIG. 1, the control unit 70 controls the heating mechanism 50 to heat the metal pipe material 14. Specifically, the control unit 70 turns on the switch 53 of the heating mechanism 50. Then, electric power is supplied to the metal pipe material 14 from the power source 51, and the resistance existing in the metal pipe material 14 causes the metal pipe material 14 itself to generate heat (Joule heat). At this time, the measured value of the thermocouple is constantly monitored, the energization is controlled based on the result, and the cylinder unit 42 of the gas supply mechanism 40 is operated to seal both ends of the metal pipe material 14 with the seal members 44. (See also FIG. 3).

  6 is a diagram showing the operation of the blow molding die and the first upper die holder and changes in the shape of the metal pipe material, FIG. 7 is a diagram following FIG. 6, and FIG. 8 is a diagram following FIG. 7.

  As shown in FIG. 6, the blow molding die 13 is closed with respect to the metal pipe material 14 after heating. At this time, the convex portions 96b and 96b of the first upper die holder 96 enter into the spaces S1 and S2 of the first lower die holder 93, and the pipe is provided between the concave portion 16 of the lower die 11 and the concave portion 24 of the upper die 12. The main cavity portion MC having a substantially rectangular cross section, which is a gap for forming the portion (main body portion) 100a, is formed, and the main cavity portion MC is formed between the upper end surface of the lower mold 11 and the lower end surface of the upper mold 12. Sub-cavity portions SC1 and SC2, which are gaps for communicating with the main cavity portion MC and for forming the flange portions 100b and 100c, are formed on both sides of the above.

  Here, the sub-cavity portions SC1 and SC2 between the upper end surface of the lower die 11 and the lower end surface of the upper die 12 extend so as to be opened outside the die, while the sub-cavity portions SC1 and SC2 are The inner surfaces 96f of the convex portions 96b and 96b of the first upper die holder 96 are closed from the outside. The convex portions 96b and 96b for closing the sub-cavity portions SC1 and SC2 of the first upper die holder 96 from the outside of the mold have foreign matter such as debris generated when the metal pipe ruptures inside the mold, and the sub-cavity portions SC1 and SC2. It works so as not to be emitted by blocking the progress through the mold. Therefore, the first upper die holder 96 having the convex portions 96b and 96b also functions as a shield member.

  Then, in this state, that is, in the state before the blow molding die is completely closed, the metal pipe material 14 is accommodated in the main cavity portion MC, and the bottom surface of the concave portion 16 of the lower die 11 and the upper die 12 are roughly. From the state of contacting the bottom surface of the recess 24, a high pressure gas is supplied into the metal pipe material 14 by the gas supply unit 60 to start blow molding.

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

  In parallel with this, the blow molding die 13 is further closed, and as shown in FIG. 7, the main cavity portion MC and the sub-cavity portions SC1 and SC2 are further closed between the lower die 11 and the upper die 12. It gets narrowed.

  Therefore, the metal pipe material 14 expands in the main cavity portion MC so as to follow the recesses 16 and 24, and a part (both sides) 14a and 14b of the metal pipe material 14 enters the sub-cavity portions SC1 and SC2. Inflate so as to enter each.

  Then, as shown in FIG. 8, the blow molding die 13 is further closed, and the bottom surface 93d of the concave portion 93a of the first lower die holder 93 is attached to the lower end surface of the convex portion 96b of the first upper die holder 96. 96d abuts, the step surface 96e of the first upper die holder 96 abuts on the upper end surface 93e of the convex portion 93b of the first lower die holder 93, and the inside of the convex portion 93b of the first lower die holder 93 The mold closing of the blow molding die 13 is completed in a state where the side surface is in contact with the outer surface of the convex portion 96b of the first upper die holder 96 and the first lower die holder 93 and the first upper die holder 96 are in close contact with each other.

  At this time, the main cavity portion MC and the sub-cavity portions SC1 and SC2 are made narrower than the state shown in FIG. 7, and in this state, as described above, the sub-cavity portions SC1 and SC2 have the first cavity. The upper die holder 96 is closed from the outside by the inner surfaces 96f of the convex portions 96b and 96b.

  Therefore, the metal pipe material 14 that is softened by heating and supplied with the high-pressure gas is molded in the main cavity portion MC as a pipe portion 100a having a rectangular cross-section that matches the rectangular cross-section of the main cavity portion MC. In the cavity parts SC1 and SC2, a part of the metal pipe material 14 is formed as flange parts 100b and 100c having a rectangular cross section.

  At the time of this blow molding, the outer peripheral surface of the metal pipe material 14 blown and expanded is brought into contact with the recess 16 of the lower mold 11 to be rapidly cooled, and at the same time, to be contacted with the recess 24 of the upper mold 12 to be rapidly cooled ( Since the upper die 12 and the lower die 11 have large heat capacities and are controlled to be at a low temperature, heat of the pipe surface is immediately removed to the die side when the metal pipe material 14 comes into contact with each other. .. Such a cooling method is called mold contact cooling or mold cooling. Immediately after being quenched, austenite transforms to martensite (hereinafter, transformation of austenite to martensite is referred to as martensite transformation). In the latter half of cooling, the cooling rate became smaller, so that the martensite is transformed into another structure (troustite, sorbite, etc.) by recuperation. Therefore, it is not necessary to perform a separate tempering process. Further, in the present embodiment, cooling may be performed by supplying a cooling medium to the metal pipe 100 instead of or in addition to cooling the mold. For example, the metal pipe material 14 is brought into contact with the mold (upper mold 12 and lower mold 11) until the temperature at which the martensitic transformation starts, and then the mold is opened and the cooling medium (cooling gas) is used as the metal pipe material. The martensite transformation may be generated by spraying on 14. Note that the description in this paragraph has been made by taking the case where the metal pipe material 14 is steel as an example.

  Then, the metal pipe 100 having the pipe portion 100a and the flange portions 100b and 100c can be obtained as a molded product by the above-described forming method as shown in FIG. In the present embodiment, since the main cavity portion MC has a rectangular cross section, the metal pipe material 14 is blow-molded in accordance with the shape, so that the pipe portion 100a is formed into a rectangular tubular shape. .. However, the shape of the main cavity MC is not particularly limited, and any shape such as a circular cross section, an elliptical cross section, or a polygonal cross section may be adopted according to a desired shape.

<Structure of power supply unit>
The molding apparatus 10 according to this embodiment includes a power supply unit 120 that supplies power to the first electrode 17 and the second electrode 18. Hereinafter, the configuration of the power supply unit 120 according to the present embodiment and its surroundings will be described with reference to FIG. 9.

  The power supply unit 120 shown in FIG. 9 is incorporated in the molding apparatus 10 as shown in FIG. 1 and supplies power to the pair of electrodes (the first electrode 17 and the second electrode 18). Thereby, the metal pipe material 14 is electrically heated. At this time, the mold 13 and members around the mold may be magnetized. For example, if energization heating is continued for a certain period in a state where one first electrode 17 of the pair of electrodes is a positive electrode and the other second electrode 18 of the pair of electrodes is a negative electrode, a predetermined amount of the mold 13 is obtained. The magnetization in the direction of advances. In such a case, while the metal pipe material 14 is being electrically heated, an electromagnetic force may be applied to the magnetized mold 13 such that the mold 13 moves in the sliding direction, which is the direction in which the mold 13 moves. There is a nature. If the mold 13 moves due to the action of this electromagnetic force and comes into contact with the metal pipe material 14 that is being energized and heated, electric leakage may occur through the mold 13 and the device may be damaged. Therefore, the power supply unit 120 of the molding apparatus 10 according to the present embodiment supplies the first electrode 17 and the second electrode 18 in order to reduce the magnetization of the mold 13 and suppress the movement of the mold 13 due to the electromagnetic force. A switching unit 125 that can switch the direction of the DC current is provided.

  Next, a specific configuration of the power supply unit 120 will be described.

  As shown in FIG. 9, the power supply unit 120 includes an AC power supply 121 that generates an AC current, an inverter 122, a transformer 123 as a rectifier, and a first output end 123P of the transformer 123. Connected to the power supply side line 143a, the second power supply side line 143b connected to the negative output end 123N of the transformer 123, the first electrode side line 145a connected to the first electrode 17, and the second electrode 18. The second electrode side line 145b and the first power source side line 143a and the second power source side line 143b are electrically connected and connected to the first electrode side line 145a and the second electrode side line 145b. A switching unit 125 that can switch the state and a control unit 126 that controls switching of the switching unit 125 are provided. Here, a bus bar may be used for the first power supply side line 143a, the second power supply side line 143b, the first electrode side line 145a, and the second electrode side line 145b, but it is not particularly limited.

  The AC power supply 121 generates a three-phase AC and is connected to the inverter 122 by three cables. Specifically, the U phase is transmitted to the inverter 122 by the cable 141a, the V phase is transmitted by the cable 141b, and the W phase is transmitted by the cable 141c. As the AC power supply 121, for example, one having 3ΦAC200V or 3ΦAC400V is used, but is not particularly limited.

  The inverter 122 is connected to the transformer 123 as a rectifier by two cables. Specifically, the U phase is transmitted to the transformer 123 via the cable 142a and the V phase is transmitted to the transformer 123. Here, the output from the inverter 122 is, for example, single-phase AC300V800A, single-phase AC600V800A, but is not particularly limited.

  As described above, the transformer 123 is connected to the switching unit 125 by the first power source side line 143a and the second power source side line 143b. Specifically, the positive side output end 123P of the transformer 123 is connected to the terminal 125a of the switching unit 125 by the first power supply side line 143a, and the negative side output end 123N is connected by the second power supply side line 143b of the switching unit 125. It is connected to the terminal 125b. When the alternating current is supplied, the transformer 123 converts it into a direct current and outputs it. Therefore, the AC power supply 121, the inverter 122, and the transformer 123 may be collectively regarded as a DC current generator that generates a DC current. Here, the output from the transformer 123 is, for example, DC20V15000A, DC30V10000A, but is not particularly limited.

  As described above, the switching section 125 is connected to the first electrode 17 and the second electrode 18 of the pipe holding mechanism 30 by the first electrode side line 145a and the second electrode side line 145b. Specifically, the output from the terminal 125c of the switching unit 125 is connected to the first electrode 17 by the first electrode side line 145a, and the output from the terminal 125d of the switching unit 125 is performed by the second electrode side line 145b. It is connected to the second electrode 18.

  The switching unit 125 also includes an electromagnetic switch MC1 (first electromagnetic switch) and an electromagnetic switch MC2 (second electromagnetic switch). The electromagnetic switch MC1 electrically connects the first power supply side line 143a and the first electrode side line 145a when operated (when ON), and also connects the second power supply side line 143b and the second power supply side line 143b. It is possible to electrically connect to the electrode side line 145b. In addition, the electromagnetic switch MC2 electrically connects the first power supply side line 143a and the second electrode side line 145b when operated (when ON), and also connects the second power supply side line 143b and the first power supply side line 143b. It is possible to electrically connect to the electrode side line 145a. The specific internal structure of the switching unit 125 is as follows.

The terminal 125a of the switching unit 125 is connected to the terminal MC1a of the electromagnetic switch MC1 and the terminal MC2a of the electromagnetic switch MC2 by the internal cable of the switching unit 125 that branches at the branch point A. Specifically, the cable 125e ₁ connected to the terminal 125a branches at the branch point A into the cables 125e ₂ and 125e ₃ . The cable 125e ₂ is connected to the terminal MC1a of the electromagnetic switch MC1. The cable 125e ₃ is connected to the terminal MC2a of the electromagnetic switch MC2. The terminal 125b is connected to the terminal MC1b of the electromagnetic switch MC1 and the terminal MC2b of the electromagnetic switch MC2 by an internal cable of the switching unit 125 that branches at the branch point B. Specifically, the cable 125f ₁ connected to the terminal 125b branches into the cables 125f ₂ and 125f ₃ at the branch point A. The cable 125f ₂ is connected to the terminal MC1b of the electromagnetic switch MC1. Cable 125f ₃ is connected to the terminal MC2b the electromagnetic switch MC2.

Further, the terminal MC1c of the electromagnetic switch MC1 and the terminal MC2d of the electromagnetic switch MC2 are connected to the terminal 125c by an internal cable branched at the branch point C. Specifically, the cable 125g ₁ connected to the terminal MC1c of the electromagnetic switch MC1 and the cable 125g ₂ connected to the terminal MC2d of the electromagnetic switch MC2 are integrated into the cable 125g ₃ at the branch point C. ing. The cable 125g ₃ is connected to the terminal 125c. The terminal MC1d of the electromagnetic switch MC1 and the terminal MC2c of the electromagnetic switch MC2 are connected to the terminal 125d by an internal cable branched at the branch point D. Specifically, the cable 125h ₁ connected to the terminal MC1d of the electromagnetic switch MC1 and the cable 125h ₂ connected to the terminal MC2c of the electromagnetic switch MC2 are integrated into the cable 125h ₃ at the branch point D. ing. The cable 125h ₃ is connected to the terminal 125d.

  With the above configuration, the electromagnetic switch MC1 electrically connects the positive side output end 123P of the transformer 123 and the first electrode 17, and electrically connects the negative side output end 123N of the transformer 123 and the second electrode 18. It is possible to connect to. The electromagnetic switch MC2 electrically connects the positive side output end 123P of the transformer 123 and the second electrode 18, and also electrically connects the negative side output end 123N of the transformer 123 and the first electrode 17. It is possible. That is, the switching unit 125 uses the electromagnetic switches MC1 and MC2 to electrically connect the positive output terminal 123P and the negative output terminal 123N of the transformer 123 to the first electrode 17 and the second electrode 18. Can be switched.

  The control unit 126 controls so that either one of the electromagnetic switch MC1 and the electromagnetic switch MC2 operates. Specifically, the control unit 126 turns off the electromagnetic switch MC2 when the electromagnetic switch MC1 is ON, and turns off the electromagnetic switch MC1 when the electromagnetic switch MC2 is ON. The control is performed so that As a result, the control unit 126 electrically connects the positive-side output end 123P of the transformer 123 and the first electrode 17 and electrically connects the negative-side output end 123N of the transformer 123 and the second electrode 18. 1 state and a second state in which the positive side output end 123P of the transformer 123 and the second electrode 18 are electrically connected and the negative side output end 123N of the transformer 123 and the first electrode 17 are electrically connected. And switch. In the first state, the first electrode has a positive pole and the second electrode has a negative pole. In the second state, the first electrode has a negative pole and the second electrode has a positive pole. Therefore, the control unit 126 causes the switching unit 125 to switch between the first state and the second state at a predetermined interval, thereby switching the direction of the direct current flowing through the metal pipe material at a predetermined interval.

  With the above configuration, the direction of the direct current flowing through the metal pipe material can be switched with a simple configuration by switching the operations of the electromagnetic switches MC1 and MC2. Since the magnetization in the mold 13 in the predetermined direction can be canceled, the magnetization of the mold 13 can be reduced and the movement of the mold due to the action of the electromagnetic force can be suppressed. The control unit 126 may cause the switching unit 125 to perform switching a plurality of times during energization heating, may perform a switching for each energization heating, or may perform a switching for each energization heating. May be switched.

  Further, since the electromagnetic switch MC1 and the electromagnetic switch MC2 are configured to be controlled by the control unit 126, the magnetization of the mold 13 can be reduced with a simple configuration that can be performed using a commercially available device, and the action of electromagnetic force can be exerted. The movement of the mold due to can be suppressed.

[Second Embodiment]
In the second embodiment of the present invention, the molding apparatus 10 employs a power supply unit 130 as shown in FIG. 10 instead of the power supply unit 120 shown in the first embodiment. The switching unit 135 in the power supply unit 130 has two transformers 133A and 133B (first rectifier and second rectifier). The control unit 136 switches the transformer to be energized by causing the switching unit 135 to switch the connection state, and switches the direction of the direct current flowing through the metal pipe material. Hereinafter, the configuration of the power supply unit 130 according to the present embodiment and its surroundings will be specifically described with reference to FIG. 10. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

  As illustrated in FIG. 10, the power supply unit 130 includes an AC power supply 121 that generates an AC current, an inverter 122, and a first power supply side line 152a and a second power supply side line 152b connected to the inverter 122. , A first electrode side line 145a connected to the first electrode 17, a second electrode side line 145b connected to the second electrode 18, a first power source side line 152a and a second power source side line 152b. Is electrically connected to the first electrode side line 145a and the second electrode side line 145b, and includes a switching unit 135 that can switch the connection state, and a control unit 136 that controls switching of the switching unit 135. There is. Here, a cable is used for the first power supply side line 152a and the second power supply side line 152b. Bus bars are used for the first electrode side line 145a and the second electrode side line 145b. However, the configuration of each line is not particularly limited. The AC power supply 121 and the inverter 122 have the same configuration as the power supply unit 120 of the first embodiment. Further, the connection between the AC power supply 121 and the inverter 122 has the same configuration as the power supply unit 120 of the first embodiment.

  As described above, the inverter 122 is connected to the switching unit 135 by the first power source side line 152a and the second power source side line 152b. The U phase is transmitted to the terminal 135a of the switching unit 135 by the first power supply side line 152a, and the V phase is transmitted to the terminal 135b of the switching unit 135 by the second power supply side line 152b.

  The switching unit 135 has the transformer 133A as the first rectifier and the transformer 133B as the second rectifier as described above. When supplied with an alternating current, the transformers 133A and 133B convert the current into a direct current and output it. The positive side output end 133AP of the transformer 133A is connected to the first electrode side line 145a, and the negative side output end 133AN is connected to the second electrode side line 145b. Further, in the transformer 133B, the positive side output end 133BP is connected to the second electrode side line 145b, and the negative side output end 133BN is connected to the first electrode side line 145a.

  Further, the switching unit 135 includes an electromagnetic switch MC3 (first electromagnetic switch) and an electromagnetic switch MC4 (second electromagnetic switch). The electromagnetic switch MC3 can electrically connect the first power supply side line 152a and the second power supply side line 152b to the transformer 133A as the first rectifier when operating (when ON). is there. That is, when the electromagnetic switch MC3 operates, it is possible to electrically connect the AC power supply 121 and the first rectifier. Further, the electromagnetic switch MC4 can electrically connect the first power source side line 152a and the second power source side line 152b to the transformer 133B as the second rectifier when operating (when ON). It is possible. That is, the electromagnetic switch MC4 can electrically connect the AC power supply 121 and the second rectifier when operating. The specific internal structure of the switching unit 135 is as follows.

The terminal 135a of the switching unit 135 is connected to the terminal MC3a of the electromagnetic switch MC3 and the terminal MC4a of the electromagnetic switch MC4 by the internal cable of the switching unit 135 that branches at the branch point E. Specifically, the cable 135e ₁ connected to the terminal 135a branches into the cables 135e ₂ and 135e ₃ at the branch point E. The cable 135e ₂ is connected to the terminal MC3a of the electromagnetic switch MC3. The cable 135e ₃ is connected to the terminal MC4a of the electromagnetic switch MC4. The terminal 135b is connected to the terminal MC3b of the electromagnetic switch MC3 and the terminal MC4b of the electromagnetic switch MC4 by an internal cable of the switching unit 135 that branches at the branch point F. Specifically, the cable 135f ₁ connected to the terminal 135b branches into the cables 135f ₂ and 135f ₃ at the branch point F. The cable 135f ₂ is connected to the terminal MC3b of the electromagnetic switch MC3. The cable 135f ₃ is connected to the terminal MC4b of the electromagnetic switch MC4. The terminals MC3c and MC3d of the electromagnetic switch MC3 are connected to the transformer 133A as a rectifier by cables 135e ₄ and 135f ₄ inside the switching unit 135. The terminals MC4c and MC4d of the electromagnetic switch MC4 are connected to the transformer 133B as a rectifier by the cables 135e ₅ and 135f ₅ inside the switching unit 135.

The positive output terminal 133AP of the transformer 133A and the negative output terminal 133BN of the transformer 133B are connected to the terminal 135c by an internal cable branched at the branch point G. Specifically, the cable 135g ₁ connected to the positive output terminal 133AP of the transformer 133A and the cable 135g ₂ connected to the negative output terminal 133BN of the transformer 133B are connected to the cable 135g ₃ at the branch point G. Integrated. The cable 135g ₃ is connected to the terminal 135c. The negative output terminal 133AN of the transformer 133A and the positive output terminal 133BP of the transformer 133B are connected to the terminal 135d by an internal cable branched at the branch point H. Specifically, the cable 135h ₁ connected to the negative output end 133AN of the transformer 133A and the cable 135h ₂ connected to the positive output end 133BP of the transformer 133B are connected to the cable 135h ₃ at the branch point H. Integrated. The cable 135h ₃ is connected to the terminal 135d. Therefore, in the transformer 133A, the positive output terminal 133AP is connected to the first electrode 17, and the negative output terminal 133AN is connected to the second electrode 18. In the transformer 133B, the positive side output end 133BP is connected to the second electrode 18, and the negative side output end 133BN is connected to the first electrode 17.

  With the above configuration, the electromagnetic switch MC3 can electrically connect the AC power supply 121 and the transformer 133A as a rectifier. The electromagnetic switch MC4 can electrically connect the AC power supply 121 and the transformer 133B as a rectifier. That is, the switching unit 135 can switch the electrical connection state of the AC power source to the transformers 133A and 133B by the electromagnetic switches MC3 and MC4. In other words, the switching unit 135 causes the positive side output terminals 133AP and 133BP, the negative side output terminals 133AN and 133BN of the transformers 133A and 133B, the negative side output terminals 133AN and 133BN, the first electrode 17 and the second electrode by the electromagnetic switches MC3 and MC4. The electrical connection state with the electrode 18 can be switched.

  The control unit 136 controls so that either one of the electromagnetic switch MC3 and the electromagnetic switch MC4 operates. Specifically, the control unit 136 turns off the electromagnetic switch MC4 when the electromagnetic switch MC3 is ON, and turns off the electromagnetic switch MC3 when the electromagnetic switch MC4 is ON. The control is performed so that As a result, the control unit 136 switches between the third state in which the AC power supply 121 and the transformer 133A are electrically connected and the fourth state in which the AC power supply 121 and the transformer 133B are electrically connected. In the third state, a voltage is applied from the transformer 133A to the first electrode 17 and the second electrode 18. Therefore, in the third state, the first electrode 17 becomes a positive pole and the second electrode becomes a negative pole. On the other hand, in the fourth state, a voltage is applied from the transformer 133B to the first electrode 17 and the second electrode 18. Therefore, in the fourth state, the first electrode 17 becomes a negative pole and the second electrode becomes a positive pole. Therefore, the control unit 136 causes the switching unit 135 to switch between the third state and the fourth state at a predetermined interval, thereby switching the direction of the direct current flowing through the metal pipe material at a predetermined interval.

  With the above configuration, the direction of the direct current flowing through the metal pipe material can be switched with a simple configuration by switching the operations of the electromagnetic switches MC1 and MC2. Since the magnetization in the mold 13 in the predetermined direction can be canceled, the magnetization of the mold 13 can be reduced and the movement of the mold due to the action of the electromagnetic force can be suppressed. The control unit 136 may cause the switching unit 135 to perform switching a plurality of times during energization heating, may perform switching for each energization heating, or may perform switching a plurality of times for energization heating. May be switched.

  Further, since the electromagnetic switch MC3 and the electromagnetic switch MC4 are controlled by the control unit 136, the magnetization of the die 13 can be reduced by a simple configuration using a commercially available device, and the electromagnetic force acts. The movement of the mold can be suppressed.

  The present invention is not limited to the above-described first embodiment and second embodiment. The molding apparatus according to the present invention may be any modification of the above-described one without departing from the scope of the claims.

  The blow molding die 13 may be either an anhydrous cold die or a water cooled die. However, the anhydrous cold mold requires a long time when the mold is lowered to around room temperature after the completion of blow molding. In this respect, with the water-cooled mold, cooling is completed in a short time. Therefore, from the viewpoint of improving productivity, the water-cooled mold is desirable.

  10 ... Molding device, 11 ... Lower mold, 12 ... Upper mold, 13 ... Mold, 14 ... Metal pipe material, 40 ... Gas supply mechanism (gas supply unit), 17 ... First electrode, 18 ... Second electrode, 120 , 130 ... Power supply unit, 121 ... AC power supply, 143a, 152a ... First power supply side line, 143b, 152b ... Second power supply side line, 123P, 133AP, 133BP ... Positive side output end, 123N, 133AN, 133BN ... Negative output terminal, 123, 133A, 133B ... Transformer, 145a ... First electrode side line, 145b ... Second electrode side line, 126, 136 ... Control part, MC1, MC2, MC3, MC4 ... Electromagnetic switch ..

Claims (2)

A molding device for expanding a metal pipe material to form a metal pipe,
At least one is movable, a mold having an upper mold and a lower mold for molding the metal pipe,
A pair of electrodes that heat the metal pipe material by energizing the metal pipe material,
A power supply unit for supplying power to the pair of electrodes,
A gas supply unit for supplying a gas into the heated metal pipe material to expand the gas;
The power supply unit,
A direct current generator that generates a direct current,
A first power supply side line connected to the positive side output end of the direct current generating section;
A second power supply side line connected to the negative side output end of the DC current generating section;
A first electrode side line connected to one electrode of the pair of electrodes;
A second electrode side line connected to the other electrode of the pair of electrodes;
When operating, the first power supply side line and the first electrode side line are electrically connected, and the second power supply side line and the second electrode side line are electrically connected. A first electromagnetic switch capable of
When operating, the first power supply side line and the second electrode side line are electrically connected, and the second power supply side line and the first electrode side line are electrically connected. A second electromagnetic switch capable of
A molding device, comprising: a control unit that controls one of the first electromagnetic switch and the second electromagnetic switch to operate. A molding device for expanding a metal pipe material to form a metal pipe,
At least one is movable, a mold having an upper mold and a lower mold for molding the metal pipe,
A pair of electrodes that heat the metal pipe material by energizing the metal pipe material,
A power supply unit for supplying power to the electrodes,
A gas supply unit for supplying a gas into the heated metal pipe material to expand the gas;
The power supply unit,
An AC power supply that generates an alternating current,
A first electrode side line connected to one electrode of the pair of electrodes;
A second electrode side line connected to the other electrode of the pair of electrodes;
When an alternating current is supplied, it is converted into a direct current and output, and the positive output end is connected to the first electrode side line and the negative output end is connected to the second electrode side line. And a first rectifier,
When an alternating current is supplied, the current is converted into a direct current and output, and the positive output end is connected to the second electrode side line and the negative output end is connected to the first electrode side line. And a second rectifier,
A first electromagnetic switch capable of electrically connecting the alternating-current power supply and the first rectifier when operating,
A second electromagnetic switch capable of electrically connecting the alternating-current power supply and the second rectifier when operating,
A molding device, comprising: a control unit that controls one of the first electromagnetic switch and the second electromagnetic switch to operate.

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