阅读说明：本技术 成型装置 (Molding device ) 是由 杂贺雅之 闲浩之 山内启 于 2018-12-13 设计创作，主要内容包括：一种成型装置(成型装置(10)),其使金属管材料(金属管材料(14))膨胀而成型出金属管,该成型装置具备：模具(模具(13)),利用上型(上型(12))及下型(下型(11))成型出金属管；下侧基底部(下型基底部(110)),其设置于下型的下侧；上侧基底部(上侧基底部(120)),其设置于上型的上侧；支柱部(支柱部(150)),其立设于下侧基底部与上侧基底部之间；及电加热部(电加热部(50)),其向配置在上型与下型之间的金属管材料供给电力而进行电加热,在电加热部进行电加热时,支柱部内部的磁通量密度高于下侧基底部的下表面中心处的磁通量密度及上侧基底部的上表面中心处的磁通量密度中的至少一个。(A molding device (10)) that expands a metal tube material (14)) to mold a metal tube, comprising: a die (13)) for molding a metal pipe by using an upper die (12)) and a lower die (11)); a lower base section (110)) provided on the lower side of the lower mold; an upper base section (120)) provided on the upper side of the upper mold; a pillar section (150)) that is vertically provided between the lower base section and the upper base section; and an electric heating unit (50) that supplies electric power to the metal pipe material disposed between the upper mold and the lower mold to electrically heat the metal pipe material, wherein when the electric heating unit electrically heats the metal pipe material, the magnetic flux density inside the column unit is higher than at least one of the magnetic flux density at the center of the lower surface of the lower base unit and the magnetic flux density at the center of the upper surface of the upper base unit.)

1. A molding device for molding a metal pipe by expanding a metal pipe material, comprising:

a die for molding the metal tube by using an upper die and a lower die;

a lower base part provided at a lower side of the lower mold;

an upper base part provided on an upper side of the upper mold;

a pillar portion erected between the lower base portion and the upper base portion; and

an electric heating unit for supplying electric power to the metal pipe material disposed between the upper mold and the lower mold to perform electric heating,

when the electric heating portion performs electric heating, a magnetic flux density inside the pillar portion is higher than at least one of a magnetic flux density at a center of a lower surface of the lower base portion and a magnetic flux density at a center of an upper surface of the upper base portion.

2. The molding apparatus according to claim 1, further comprising:

and a sensor disposed inside at least one of the upper base portion and the lower base portion.

3. The molding apparatus according to claim 1 or 2,

the electric heating unit includes: a pair of electrodes which are in contact with the metal tube material when electrically heated; and a pair of bus bars for transmitting power to the pair of electrodes,

the pair of bus bars are arranged on one side of the mold in a 1 st direction and a 2 nd direction orthogonal to the up-down direction, in which the pair of electrodes face each other.

Technical Field

The present invention relates to a molding apparatus.

Background

Conventionally, there is known a molding apparatus for blow molding a metal pipe by closing a mold. For example, a molding device described in patent document 1 includes a die and an electric heating unit that electrically heats a metal pipe material. In this molding apparatus, a metal pipe material is electrically heated and then placed in a mold. Then, the molding device closes the mold and supplies gas to the metal tube material in this state to expand it, thereby molding the metal tube material into a shape corresponding to the shape of the mold. In a conventional molding apparatus, each electrode is brought into contact with a metal pipe material and then energized to heat the metal pipe material. When the electric heating is performed, a large current (for example, about several tens of thousands of amperes) flows through the power feeding line, and thus the mold is magnetized by the influence of a leakage magnetic field from the power feeding line, and the mold may move. The molding device described in patent document 1 includes a mold movement suppression unit for suppressing the movement of the mold.

Prior art documents

Patent document

Patent document 1: international publication No. 2017/038692

Disclosure of Invention

Technical problem to be solved by the invention

However, in the molding apparatus, it is required not only to suppress the movement of the mold due to magnetization caused by electric heating, but also to reduce the influence of the magnetic field on the sensors and the like disposed around the mold. That is, it is required to reduce the influence of the magnetic field on the sensor and the like around the mold.

Accordingly, an object of the present invention is to provide a molding apparatus capable of reducing the influence of a magnetic field on a sensor or the like around a mold.

Means for solving the technical problem

A forming apparatus according to an embodiment of the present invention is a forming apparatus for forming a metal pipe by expanding a metal pipe material, the forming apparatus including: a die for forming a metal tube by using an upper die and a lower die; a lower base part provided on the lower side of the lower mold; an upper base part provided on the upper side of the upper mold; a pillar portion erected between the lower base portion and the upper base portion; and an electric heating unit that supplies electric power to the metal pipe material disposed between the upper mold and the lower mold to perform electric heating, wherein when the electric heating unit performs electric heating, a magnetic flux density inside the pillar portion is higher than at least one of a magnetic flux density at a center of a lower surface of the lower base portion and a magnetic flux density at a center of an upper surface of the upper base portion.

According to this molding device, the pillar portion is disposed between the lower base portion provided on the lower side of the lower mold and the upper base portion provided on the upper side of the upper mold. When the electric heating portion performs electric heating, the magnetic flux density inside the pillar portion is higher than at least one of the magnetic flux density at the center of the lower surface of the lower base portion and the magnetic flux density at the center of the upper surface of the upper base portion. The fact that the magnetic flux density increases when the electric heating is performed means that the pillar portion is configured to absorb the surrounding magnetic flux around the mold. In this way, since the pillar portion absorbs the magnetic flux generated around the die, the magnetic flux toward the other sensors can be reduced by that amount. According to the above, the influence of the magnetic field on the sensor and the like around the mold can be reduced.

The molding apparatus may further include a sensor disposed inside at least one of the upper base portion and the lower base portion. The inner sides of the upper base part and the lower base part are parts which are not easily affected by the magnetic field. Therefore, by disposing the sensor at this position, the influence of the magnetic field on the sensor can be reduced.

In the molding device, the electrical heating unit may include: a pair of electrodes which are in contact with the metal tube material when electrically heated; and a pair of bus bars for transmitting power to the pair of electrodes, wherein the pair of bus bars may be disposed on one side of the mold in a 1 st direction and a 2 nd direction orthogonal to the up-down direction, the pair of bus bars facing each other. The pair of bus bars are portions through which a large current flows when electrical heating is performed. By disposing two such bus bars on one side of the mold in the 2 nd direction, the other side region of the mold becomes a region where the magnetic field generated from the bus bars is blocked by the mold. Therefore, by disposing a sensor or the like in this region, the influence of the magnetic field can be reduced.

Effects of the invention

According to the molding apparatus of the present invention, there is provided a molding apparatus capable of reducing the influence of a magnetic field on a sensor or the like around a mold.

Drawings

Fig. 1 is a front view of a molding apparatus according to an embodiment of the present invention.

Fig. 2 is a schematic configuration diagram showing a molding apparatus according to an embodiment of the present invention.

Fig. 3 is an enlarged view of the periphery of the electrode, in which (a) is a view showing a state where the electrode holds a metal tube material, (b) is a view showing a state where a sealing member is pressed against the electrode, and (c) is a front view of the electrode.

Fig. 4 is a view of the structure of the periphery of the mold as viewed from above.

Fig. 5 is a view of the bus bar as viewed from the front side in the X-axis direction.

Fig. 6 is a model diagram showing the intensity of magnetic flux density in the vicinity of the pillar portion.

Detailed Description

Hereinafter, preferred embodiments of the molding system of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description thereof is omitted.

< Structure of molding apparatus >

Fig. 1 is a front view of a molding apparatus according to the present embodiment. As shown in fig. 1, the molding apparatus 10 includes a mold 13, a lower base portion 110, an upper base portion 120, and a pillar portion 150. The mold 13 includes an upper mold 12 and a lower mold 11. The lower base portion 110 is provided on the lower side of the lower mold 11, facing the lower mold 11. One direction in the horizontal direction is referred to as an X-axis direction (1 st direction), and a direction orthogonal to the X-axis direction in the horizontal direction is referred to as a Y-axis direction (2 nd direction). One in the X-axis direction (right side of the paper surface in fig. 1) is set as a positive side, and one in the Y-axis direction (front side of the paper surface in fig. 1) is set as a positive side.

The lower base portion 110 is a component called a bed (bed), and constitutes a base of the molding apparatus 10. A driving mechanism for moving the lower mold 11 and the like are housed in the lower base 110. The lower base portion 110 has a rectangular parallelepiped shape, and has an upper surface 110a and a lower surface 110b extending in the horizontal direction. The lower base portion 110 has a plate-like base 111 on the upper end side. The lower die 11, an electrode and a gas supply mechanism described later are disposed on the base 111. The upper surface of the base 111 corresponds to the upper surface 110a of the lower base 110. Upper base portion 120 is provided on the upper side of upper mold 12 so as to face upper mold 12. The upper base portion 120 is a component called a crown (crown) and is a component that becomes a base of an upper structure of the molding apparatus 10. A driving mechanism or the like for moving the upper mold 12 is accommodated in the upper base bottom 120. The upper base portion 120 has a rectangular parallelepiped shape, and has a lower surface 120a and an upper surface 120b extending in the horizontal direction. The pillar portion 150 is a member that is vertically provided between the lower base portion 110 and the upper base portion 120. A plurality of (four in this case) pillar portions 150 are formed so as to surround the periphery of the mold 13. The detailed structure of the pillar portion 150 will be described later.

Fig. 2 is a schematic configuration diagram of the molding apparatus according to the present embodiment. As shown in fig. 2, a molding apparatus 10 for molding a metal pipe includes: a mold 13 composed of the upper mold 12 and the lower mold 11; a drive mechanism 80A that moves the upper mold 12; a drive mechanism 80B that moves the lower mold 11; a tube holding mechanism 30 that holds the metal tube material 14 arranged between the upper mold 12 and the lower mold 11; an electric heating unit 50 that heats the metal tube material 14 held by the tube holding mechanism 30 by supplying electricity thereto; a gas supply unit 60 for supplying high-pressure gas (gas) into the heated metal tube material 14 held between the upper die 12 and the lower die 11; and a pair of gas supply mechanisms 40 and 40 for supplying gas from the gas supply unit 60 into the metal tube material 14 held by the tube holding mechanism 30, and the molding device 10 further includes a control unit 70 for controlling the driving of the driving mechanisms 80A and 80B, the driving of the tube holding mechanism 30, the driving of the electric heating unit 50, and the gas supply of the gas supply unit 60, respectively.

The lower mold 11, which is one of the molds 13, is formed of a large steel block, and has a rectangular cavity (recess) 16 on an upper surface thereof. The lower mold 11 is movably disposed near the center of the lower base 110 on the base 111. The lower mold 11 has a rectangular parallelepiped shape extending in the X-axis direction. That is, the metal tube material 14 is molded in a state of extending in the X-axis direction at the time of molding. The lower mold 11 is formed with a cooling water passage 19.

Further, electrodes 17 and 18 (lower electrodes) and the like described later constituting the tube holding mechanism 30 are disposed near the ends of the lower mold 11 in the X axis direction. Further, by placing the metal tube material 14 on the lower electrodes 17, 18, the lower electrodes 17, 18 come into contact with the metal tube material 14 disposed between the upper mold 12 and the lower mold 11. Thereby, the lower electrodes 17, 18 are electrically connected to the metal tube material 14. In the present embodiment, the lower electrodes 17 and 18 are fixed to the base 111 and are disposed at positions adjacent to both ends of the lower mold 11 in the X-axis direction.

Insulating materials 91 for preventing current are provided between the lower mold 11 and the lower electrode 17 and below the lower electrode 17, between the lower mold 11 and the lower electrode 18, and below the lower electrode 18, respectively. Here, the lower electrodes 17 and 18 are supported by a support member 112 provided on a base 111 via an insulating material 91.

The upper mold 12, which is the other mold of the molds 13, is fixed to a later-described slider 81A constituting the drive mechanism 80A. The upper mold 12 is formed of a large steel block, has a cooling water passage 25 formed therein, and has a rectangular cavity (recess) 24 on the lower surface thereof. The cavity 24 is provided at a position facing the cavity 16 of the lower mold 11. The upper mold 12 has a rectangular parallelepiped shape extending in the X-axis direction.

Spaces 12a are provided near both ends of the upper mold 12 in the X-axis direction, and movable portions of the tube holding mechanism 30 (i.e., electrodes 17 and 18 (upper electrodes) described later) are disposed in the spaces 12a so as to be movable up and down. In a state where the metal tube material 14 is placed on the lower electrodes 17, 18, the upper electrodes 17, 18 are moved downward to be in contact with the metal tube material 14 disposed between the upper mold 12 and the lower mold 11. Thereby, the upper electrodes 17, 18 are electrically connected to the metal tube material 14.

Insulating material 101 for preventing current conduction is provided between upper mold 12 and upper electrode 17 and above upper electrode 17, and between upper mold 12 and upper electrode 18 and above upper electrode 18, respectively. Each insulating material 101 is fixed to a movable portion (i.e., the advancing-retreating rod 96) of the actuator constituting the tube holding mechanism 30. The actuator is used to move the upper electrodes 17, 18 and the like up and down, and a fixed portion of the actuator is held on the slider 81 side of the drive mechanism 80A together with the upper mold 12.

Semi-arc-shaped grooves 18a (see fig. 3) corresponding to the outer peripheral surface shape of the metal tube material 14 are formed in the surfaces of the electrodes 18, 18 facing each other in the right side portion of the tube holding mechanism 30, and the metal tube material 14 can be fitted into the groove 18a portion. As in the case of the above-described groove 18a, a semi-arc-shaped groove corresponding to the outer peripheral surface shape of the metal tube material 14 is formed on the exposed surfaces of the insulating materials 91, 101 facing each other in the right side portion of the tube holding mechanism 30. A tapered concave surface 18b is formed on the front surface (surface facing the outside of the mold) of the electrode 18, the periphery of the groove 18a being recessed so as to be inclined in a conical shape toward the groove 18 a. Therefore, if the metal tube material 14 is sandwiched from the top-bottom direction by the right side portion of the tube holding mechanism 30, the entire outer periphery of the right side end portion of the metal tube material 14 can be surrounded tightly.

Semi-arc-shaped grooves 17a (see fig. 3) corresponding to the outer peripheral surface shape of the metal tube material 14 are formed in the surfaces of the electrodes 17, 17 facing each other at the left side portion of the tube holding mechanism 30, and the metal tube material 14 can be fitted into the groove 17a portion. As with the above-described groove 17a, semi-arc shaped grooves corresponding to the outer peripheral surface shape of the metal tube material 14 are formed on the exposed surfaces of the insulating materials 91, 101 at the left side portion of the tube holding mechanism 30 that face each other. A tapered concave surface 17b is formed on the front surface (surface facing the outside of the mold) of the electrode 17, the periphery of the groove 17a being recessed so as to be inclined in a conical shape toward the groove 17 a. Therefore, if the metal tube material 14 is sandwiched from above and below by the left side portion of the tube holding mechanism 30, the entire outer periphery of the left side end portion of the metal tube material 14 can be surrounded tightly.

As shown in fig. 2, the drive mechanism 80A includes: a slider 81A that moves the upper mold 12 in a direction in which the upper mold 12 and the lower mold 11 are closed to each other; a shaft portion 82A connected to the slider 81A; and a cylinder portion 83A for guiding the shaft portion 82A. The cylinder portion 83A is a cylindrical member extending in the vertical direction and having a lower opening. At least the upper end side portion of the cylinder portion 83A is disposed in the upper base bottom 120. Here, the cylinder portion 83A is disposed substantially over the entire length in the upper base portion 120, and only a part of the lower end side protrudes from the upper base portion 120. The shaft portion 82A extends downward from the lower opening of the cylinder portion 83A and is connected to the slider 81A. As the shaft portion 82A reciprocates in the vertical direction while being guided by the cylinder portion 83A, the slider 81A and the upper die 12 reciprocate in the vertical direction. The shaft portion 82A is driven by a driving force such as a hydraulic pressure transmitted from the driving source 85A.

The drive mechanism 80B includes: a shaft portion 82B that moves the lower mold 11 in a direction in which the upper mold 12 and the lower mold 11 are closed to each other; and a cylinder portion 83B for guiding the shaft portion 82B. The cylinder portion 83B is a cylindrical member extending in the vertical direction and having an upper opening. The cylinder portion 83B is disposed in the lower base portion 110. The cylinder portion 83B is disposed below the base 111, and the entire cylinder portion is disposed in the lower base portion 110. The shaft portion 82B extends upward from the upper opening of the cylinder portion 83B and is connected to the lower die 11. The lower mold 11 reciprocates in the vertical direction as the shaft portion 82B reciprocates in the vertical direction while being guided by the cylinder portion 83B. The shaft portion 82B is driven by a driving force such as a hydraulic pressure transmitted from the driving source 85B.

The electric heating unit 50 includes a power supply unit 55, a power supply wire 52 for electrically connecting the power supply unit 55 and the electrodes 17 and 18, and the electrodes 17 and 18. The power supply unit 55 includes a dc power supply and a switch, and the power supply unit 55 can supply power to the metal tube material 14 through the power supply line 52 and the electrodes 17 and 18 in a state where the electrodes 17 and 18 are electrically connected to the metal tube material 14. Here, the feed line 52 is connected to the lower electrodes 17 and 18.

In the electric heating unit 50, a direct current output from the power supply unit 55 is transmitted through the power supply line 52 and input to the electrode 17. Then, a direct current is input to the electrode 18 after passing through the metal tube material 14. Then, the direct current C is transmitted through the power supply line 52 and input to the power supply portion 55.

The pair of gas supply mechanisms 40 each include: a cylinder unit 42; a piston rod 43 that moves forward and backward in accordance with the operation of the cylinder unit 42; and a seal member 44 connected to the end of the piston rod 43 on the tube holding mechanism 30 side. The cylinder unit 42 is mounted on and fixed to the base 111. A tapered surface 45 that tapers toward the tip is formed at the tip of the seal member 44, and the tapered surface 45 is configured in a shape that matches the tapered concave surfaces 17b, 18b of the electrodes 17, 18 (see fig. 3). The seal member 44 is provided with a gas passage 46, the gas passage 46 extending from the cylinder block 42 side toward the tip end, specifically, as shown in fig. 3 (a) and (b), the gas passage 46 is through which high-pressure gas supplied from the gas supply portion 60 flows.

The gas supply unit 60 includes: a gas source 61, a gas tank 62 for storing gas supplied from the gas source 61, a 1 st pipe 63 extending from the gas tank 62 to the cylinder unit 42 of the gas supply mechanism 40, a pressure control valve 64 and a switching valve 65 provided in the 1 st pipe 63, a 2 nd pipe 67 extending from the gas tank 62 to the gas passage 46 formed in the seal member 44, a pressure control valve 68 and a check valve 69 provided in the 2 nd pipe 67. The pressure control valve 64 functions as follows: the cylinder unit 42 is supplied with gas of a working pressure corresponding to the thrust of the sealing member 44 against the metal tube material 14. The check valve 69 functions as follows: preventing the high pressure gas from flowing backward in the 2 nd pipe 67. The pressure control valve 68 provided in the 2 nd pipe 67 functions as follows: the gas of the working pressure for expanding the metal tube material 14 is supplied to the gas passage 46 of the sealing member 44 by the control of the control portion 70. The pair of gas supply mechanisms 40 are disposed to face each other in the X-axis direction so as to sandwich the lower mold 11.

The control unit 70 controls the pressure control valve 68 of the gas supply unit 60 so that gas of a desired operating pressure can be supplied into the metal tube material 14. The control unit 70 controls the driving mechanisms 80A and 80B, the power supply unit 55, and the like.

< method for Forming Metal tube Using Forming device >

Next, a method of forming a metal pipe using the forming apparatus 10 will be described. First, a cylindrical metal pipe material 14 of quenchable steel is prepared. For example, the metal tube material 14 is placed (thrown) on the electrodes 17 and 18 provided on the lower die 11 side by a robot arm. Since the grooves 17a, 18a are formed on the electrodes 17, 18, the metal tube material 14 is positioned by the grooves 17a, 18 a.

Next, the control unit 70 controls the driving mechanism 80A and the tube holding mechanism 30 so that the tube holding mechanism 30 holds the metal tube material 14. Specifically, the upper mold 12 and the upper electrodes 17 and 18 held on the slider 81A side are moved toward the lower mold 11 by driving of the driving mechanism 80A, and the vicinity of both side ends of the metal tube material 14 is held from above and below by the tube holding mechanism 30 by operating an actuator capable of moving the upper electrodes 17 and 18 and the like provided in the tube holding mechanism 30 forward and backward. Since the grooves 17a and 18a formed in the electrodes 17 and 18 and the grooves formed in the insulating members 91 and 101 are present in this clamping, the metal tube material 14 is in close contact with the entire circumference in the vicinity of both side ends thereof.

In addition, at this time, as shown in fig. 3 (a), the electrode 18 side end portion of the metal tube material 14 protrudes further toward the sealing member 44 side than the boundary between the groove 18a and the tapered concave surface 18b of the electrode 18 in the extending direction of the metal tube material 14. Likewise, the electrode 17 side end portion of the metal tube material 14 protrudes more toward the sealing member 44 side than the boundary between the groove 17a and the tapered concave surface 17b of the electrode 17 in the extending direction of the metal tube material 14. The lower surfaces of the upper electrodes 17 and 18 and the upper surfaces of the lower electrodes 17 and 18 are in contact with each other. However, the electrodes 17 and 18 may be configured to abut against a part of the metal tube material 14 in the circumferential direction, instead of being configured to abut against the entire circumference of both end portions of the metal tube material 14.

Next, the control portion 70 heats the metal tube material 14 by controlling the electric heating portion 50. Specifically, the control unit 70 controls the power supply unit 55 of the electric heating unit 50 to supply electric power. In this way, the electric power transmitted to the lower electrodes 17 and 18 via the power supply wire 52 is supplied to the upper electrodes 17 and 18 sandwiching the metal tube material 14 and the metal tube material 14, and the metal tube material 14 itself generates heat based on joule heat based on the electric resistance of the metal tube material 14. That is, the metal tube material 14 is in an electrically heated state.

Next, the control section 70 controls the driving mechanisms 80A and 80B to close the die 13 with respect to the heated metal tube material 14. Thereby, the cavity 16 of the lower mold 11 and the cavity 24 of the upper mold 12 are combined with each other, and the metal tube material 14 is arranged and sealed in the cavity portion between the lower mold 11 and the upper mold 12.

Then, the cylinder unit 42 of the gas supply mechanism 40 is operated to advance the sealing member 44, thereby sealing both ends of the metal tube material 14. At this time, as shown in fig. 3 (b), the sealing member 44 presses the electrode 18 side end portion of the metal tube material 14, and a portion protruding toward the sealing member 44 side than a boundary between the groove 18a and the tapered concave surface 18b of the electrode 18 is deformed in a funnel shape like the tapered concave surface 18 b. Similarly, the sealing member 44 presses the electrode 17 side end portion of the metal tube material 14, and a portion protruding toward the sealing member 44 side with respect to the boundary between the groove 17a and the tapered concave surface 17b of the electrode 17 is deformed in a funnel shape similar to the tapered concave surface 17 b. After the sealing is completed, high-pressure gas is blown into the metal tube material 14, so that the metal tube material 14 softened by heating is formed into the same shape as that of the cavity portion.

Since the metal tube material 14 is softened by being heated to a high temperature (around 950 ℃), the gas supplied into the metal tube material 14 is thermally expanded. Therefore, as the supply gas, for example, compressed air is supplied, and the metal tube material 14 at 950 ℃ can be easily expanded by the compressed air thermally expanded.

The outer peripheral surface of the metal tube material 14 expanded by blow molding is rapidly cooled by contact with the cavity 16 of the lower mold 11 and rapidly cooled by contact with the cavity 24 of the upper mold 12 (since the heat capacities of the upper mold 12 and the lower mold 11 are large and controlled to be low temperature, heat on the tube surface is immediately taken away by the mold side as long as the metal tube material 14 is in contact with the upper mold 12 or the lower mold 11), and quenching is performed. This cooling method is called mold contact cooling or mold cooling. Immediately after being rapidly cooled, austenite is transformed into martensite (hereinafter, a phenomenon in which austenite is transformed into martensite is referred to as martensite transformation). Since the cooling speed becomes slow at the latter stage of cooling, martensite is transformed into another structure (troostite, sorbite, etc.) by regenerative heating. Therefore, a separate tempering treatment is not required. In the present embodiment, instead of the mold cooling, for example, a cooling medium may be supplied into the cavity 24 to perform the cooling, or in addition to the mold cooling, for example, a cooling medium may be supplied into the cavity 24 to perform the cooling. For example, the metal tube material 14 may be cooled by being brought into contact with the dies (the upper die 12 and the lower die 11) up to the start temperature of the martensitic transformation, and then the dies may be opened and a cooling medium (cooling gas) may be blown into the metal tube material 14 to cause the martensitic transformation.

As described above, the metal pipe material 14 is cooled after being blow molded, and then opened to obtain a metal pipe having, for example, a substantially rectangular cylindrical body portion.

(Structure relating to magnetic field of Molding apparatus)

The forming device 10 electrically heats the metal tube material 14. At this time, since a high current flows through the feeding wire 52 and the energized portions such as the electrodes 17 and 18, a magnetic field is formed around the energized portions. Therefore, at the time of electric heating, the magnetic flux density inside the member around the energized portion becomes large. Next, a structure relating to the magnetic field generated in the molding device 10 will be described.

First, the bus bars 130A and 130B constituting the power feeding line 52 for supplying electric power to the electrodes 17 and 18 will be described with reference to fig. 4 and 5. Fig. 4 is a view of the structure around the mold 13 as viewed from above. Fig. 5 is a view of the bus bars 130A and 130B as viewed from the front side in the X-axis direction. The bus bar 130A supplies electric power to the electrode 17. The bus bar 130B supplies electric power to the electrode 18. The pair of bus bars 130A and 130B are disposed on the positive side (one side) of the mold 13 in the Y-axis direction orthogonal to the X-axis direction and the vertical direction in which the pair of electrodes 17 and 18 face each other. Therefore, the negative side region of the mold 13 in the Y axis direction is a region in which the influence of the magnetic field of the bus bars 130A and 130B is reduced by the presence of the mold 13. By disposing various sensors, cylinders, and other devices in this area, the influence of the magnetic field on the devices can be reduced.

The extending portions 131A and 131B of the bus bars 130A and 130B extend from the positive side to the negative side in the Y-axis direction toward the lower base portion 110 at the height position on the lower end side of the lower base portion 110. The extending portions 132A, 132B of the bus bars 130A, 130B extend upward from the lower end side to the upper end side of the lower base portion 110 along the side surface on the Y-axis direction positive side of the lower base portion 110 (see fig. 5, in particular). The extending portions 133A, 133B of the bus bars 130A, 130B extend from the upper ends of the extending portions 132A, 132B to the negative side in the Y axis direction to a position above the lower base portion 110. The extending portions 131A, 131B, 132A, 132B, 133A, 133B extend in parallel with each other. Thus, at this position, the bus bars 130A, 130B can cancel each other's magnetic field. The branch portion 134A of the bus bar 130A branches from the end of the extension portion 133A at a position above the lower base portion 110, extends to the negative side in the X-axis direction, and is then bent to the negative side in the Y-axis direction and connected to the electrode 17. The branch portion 134B of the bus bar 130B branches from the end of the extension portion 133B at a position above the lower base portion 110, extends to the positive side in the X-axis direction, and is then bent to the negative side in the Y-axis direction and connected to the electrode 18.

The extended portions 131A, 131B, 132A, 132B, 133A, 133B of the bus bars 130A, 130B are covered with a cover 136 in order to suppress leakage of a magnetic field. Further, a bracket 137 (see fig. 5) for blocking a magnetic field and fixing the bus bars 130A and 130B is provided on the side surface of the lower base 110 at a position facing the extension portions 132A and 132B of the bus bars 130A and 130B. The bracket 137 suppresses leakage of the magnetic field to the inside of the lower base portion 110. The material of the cover 136 and the bracket 137 is electromagnetic soft iron, silicon steel, permalloy, amorphous, or the like, which can block a magnetic field.

The molding device 10 includes various sensors at various locations. In the present embodiment, the sensor is disposed at a position that is less susceptible to the influence of the magnetic field. Specifically, as shown in fig. 2, the molding device 10 includes a sensor 140A disposed inside the upper base portion 120. The sensor 140A is a linear sensor for detecting the position of the shaft portion 82A. The sensor 140A is provided inside the upper base portion 120 in the cylinder portion 83A and the shaft portion 82A. The rod portion 140Aa of the sensor 140A is disposed inside the cylinder portion 83A and connected to the shaft portion 82A. The detection unit 140Ab of the sensor 140A is disposed at the upper end of the cylinder portion 83A.

The molding device 10 includes a sensor 140B disposed inside the lower base bottom 110. The sensor 140B is a linear sensor for detecting the position of the shaft portion 82B. The sensor 140B is provided in the cylinder portion 83B and the shaft portion 82B inside the lower base portion 110. The rod 140Ba of the sensor 140B is disposed inside the cylinder portion 83B and connected to the shaft portion 82B. The detection unit 140Bb of the sensor 140B is disposed at the lower end of the cylinder portion 83B.

As shown in fig. 4, the molding device 10 includes a sensor 140C in a region on the negative side in the Y axis direction with respect to the mold 13. This region is a region of the mold 13 on the opposite side of the region where the bus bars 130A and 130B are arranged. Thus, the sensor 140C is less susceptible to the magnetic field from the bus bars 130A, 130B. The sensor 140C is, for example, a thermometer (radiation thermometer) for measuring the temperature of the mold or the metal tube material 14, a measuring instrument (position sensor, contact switch, etc.) for measuring the expansion length of the metal tube material 14, a gauss meter for measuring a magnetic field, or the like.

The molding device 10 may be provided with a plurality of sensors of different types or different detection methods for the same measurement target. When the same measurement target object is measured but the sensors show values that are greatly different from each other, one of the sensors may be affected by the magnetic field and fail. Thus, the control section 70 acquires and compares detection results from the plurality of sensors. When the detection results from the sensors are significantly different, the control unit 70 detects that a failure has occurred. For example, in addition to the sensor 140A, a position detection sensor having a different measurement method from that of the linear sensor, such as an encoder, may be provided to the cylinder portion 83A and the shaft portion 82A.

As shown in fig. 1 and 4, the molding apparatus 10 includes a pillar portion 150 as a member for absorbing magnetic flux generated around the mold 13. The material of the pillar portion 150 is steel or the like. The material of the lower base portion 110 and the upper base portion 120 is steel, and may be the same as or different from the material of the pillar portion 150. As shown in fig. 1, the pillar portion 150 is erected between the lower base portion 110 and the upper base portion 120, and is disposed at least at positions corresponding to the lower mold 11, the upper mold 12, and the slider 81A in the vertical direction. As shown in fig. 4, four pillar portions 150A, 150B, 150C, 150D are arranged near four corners of the lower base portion 110. The pillar portion 150A is disposed at a corner portion located on the positive side in the Y-axis direction and the negative side in the X-axis direction. The pillar portion 150B is disposed at a corner portion located on the positive side in the Y-axis direction and the positive side in the X-axis direction. The pillar portion 150C is disposed at a corner portion located on the negative side in the Y-axis direction and the negative side in the X-axis direction. The pillar portion 150D is disposed at a corner portion located on the negative side in the Y-axis direction and the positive side in the X-axis direction.

The support portions 150A and 150B are disposed at positions separated from the positive side end in the Y axis direction of the mold 13 to the positive side in the Y axis direction. The support portions 150C and 150D are disposed at positions separated from the negative side end portion of the mold 13 in the Y axis direction to the negative side in the Y axis direction. The distance separating the pillar portions 150A, 150B from the positive side end portion of the mold 13 in the Y-axis direction and the distance separating the pillar portions 150C, 150D from the negative side end portion of the mold 13 in the Y-axis direction may be set to about 100mm to 3000 mm. This allows the column parts 150A, 150B, 150C, and 150D to absorb the magnetic flux generated around the mold 13 satisfactorily. The support portions 150A and 150C are disposed at positions separated from the negative side end portion of the mold 13 in the X axis direction toward the negative side in the X axis direction. The support portions 150B and 150D are disposed at positions separated from the positive side end in the X axis direction of the mold 13 toward the positive side in the X axis direction. The distance separating the pillar portions 150A, 150C from the negative side end portion of the mold 13 in the X-axis direction and the distance separating the pillar portions 150B, 150D from the positive side end portion of the mold 13 in the X-axis direction may be set to about 100mm to 3000 mm. This allows the column parts 150A, 150B, 150C, and 150D to absorb the magnetic flux generated around the mold 13 satisfactorily.

As described above, the pillar portion 150 absorbs the magnetic flux generated in the periphery of the mold 13. Therefore, when the electric heating portion 50 is electrically heated, the magnetic flux density inside the pillar portion 150 is higher than at least one of the magnetic flux density at the center P1 (see fig. 1) of the lower surface 110b of the lower base portion 110 and the magnetic flux density at the center P2 (see fig. 1) of the upper surface 120b of the upper base portion 120. The centers P1, P2 are central positions in the Y-axis direction and the X-axis direction in the respective surfaces 110b, 120 b. The magnetic flux density inside the pillar portion 150 is preferably higher by 50% or more than the magnetic flux density at the center P1 of the lower surface 110b of the lower base portion 110 and the center P2 of the upper surface 120b of the upper base portion 120. With this structure, the pillar portion 150 can sufficiently absorb the magnetic flux around the mold 13. Fig. 6 is a model diagram showing the intensity of magnetic flux density in the vicinity of the pillar portions 150A, 150C. In fig. 6, the gray portion is a portion where the magnetic flux density is 0.1T (tesla) or more. As shown in fig. 6, in the pillar portion 150, the magnetic flux density in the region between the upper surface 110a of the lower base portion 110 and the lower surface of the slider 81A is 0.1T or more.

The magnetic flux density inside the pillar portion 150 during electric heating is higher than the average of the magnetic flux densities on the four side surfaces of the lower base portion 110 and the average of the magnetic flux densities on the four side surfaces of the upper base portion 120. The magnetic flux density inside the pillar portion 150 is higher than the magnetic flux density near the outer peripheral portion of the upper surface 110a of the lower base portion 110 and the lower surface 120a of the upper base portion 120 that is separated from the mold 13 toward the outer peripheral side.

Here, the "magnetic flux density inside the pillar portion 150" means: when the reference position is set in the vertical direction of the pillar portion 150, the average value of the magnetic flux density in the cross section of the pillar portion 150 at the reference position is obtained. Alternatively, the magnetic flux density actually measured on any surface of the pillar portion 150 may be set as the magnetic flux density on the pillar portion 150. The reference position in the vertical direction may be arbitrarily set, and for example, may be set at a central position in the vertical direction between the upper surface 110a of the lower base portion 110 and the lower surface of the slider 81A. Alternatively, the center position in the vertical direction between the lower surface of the lower mold 11 and the upper surface of the upper mold 12 in the state where the mold 13 is closed may be set. As the reference position, a position of an arbitrary surface of the pillar portion 150 may be set.

Next, the operation and effect of the molding apparatus 10 according to the present embodiment will be described.

According to the molding apparatus 10, the column part 150 is disposed between the lower base part 110 provided on the lower side of the lower mold 11 and the upper base part 120 provided on the upper side of the upper mold 12. When the electric heating unit 50 performs electric heating, the magnetic flux density inside the pillar portion 150 is higher than the magnetic flux density at the center P1 of the lower surface 110b of the lower base portion 110 and the magnetic flux density at the center P2 of the upper surface 120b of the upper base portion 120. The fact that the magnetic flux density increases when the electric heating is performed means that the pillar portion 150 is configured to absorb the surrounding magnetic flux around the mold 13. In this way, since the pillar portion 150 absorbs the magnetic flux generated around the mold 13, the magnetic flux toward the other sensors can be reduced by that amount. As described above, the influence of the magnetic field on the sensors and the like around the mold 13 can be reduced.

The molding device 10 further includes sensors 140A and 140B disposed inside the upper base portion 120 and the lower base portion 110. The inner sides of the upper base portion 120 and the lower base portion 110 are portions that are not easily affected by a magnetic field. Therefore, by disposing the sensors 140A and 140B at this position, the influence of the magnetic field on the sensors 140A and 140B can be reduced.

In the molding device 10, the electrical heating unit 50 includes the pair of electrodes 17 and 18 that are in contact with the metal tube material 14 during electrical heating, and the pair of bus bars 130A and 130B that supply power to the pair of electrodes 17 and 18, and the pair of bus bars 130A and 130B may be disposed on one side of the mold 13 in the Y-axis direction orthogonal to the X-axis direction and the vertical direction in which the pair of electrodes 17 and 18 face each other. The pair of bus bars 130A and 130B are portions through which a large current flows when electrical heating is performed. By disposing two such bus bars 130A, 130B on one side of the mold 13 in the Y axis direction, the other side region of the mold 13 becomes a region where the magnetic field generated from the bus bars 130A, 130B is blocked by the mold 13. Therefore, by disposing a sensor or the like in this region, the influence of the magnetic field can be reduced.

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

For example, the shapes and the arrangements of the lower base portion, the upper base portion, and the pillar portion may be changed as appropriate without departing from the scope of the present invention. The number of the strut members is not particularly limited, and five or more strut members may be provided. The shapes and arrangements of the mold, the electric heating unit, the gas supply unit, and other components may be changed as appropriate.

Description of the symbols

10-forming device, 11-down, 12-up, 13-die, 14-metal tube material, 50-electric heating part, 110-lower base part, 120-upper base part, 140A, 140B-sensor, 150A, 150B, 150C, 150D-pillar part, 17, 18-electrode, 130A, 130B-bus bar.