JP6475437B2 - Molding equipment - Google Patents

Description

  The present invention relates to a molding apparatus.

  2. Description of the Related Art Conventionally, a molding apparatus that molds a heated metal pipe material with a mold is known. For example, the molding apparatus disclosed in Patent Document 1 includes a mold, an energizing terminal that energizes and heats the metal pipe material, and a gas supply unit that supplies gas into the metal pipe material. In this molding apparatus, the metal pipe material heated by the energizing terminal is placed in the mold, and the metal pipe material is expanded by supplying gas from the gas supply portion to the metal pipe material in a state where the mold is closed. The material is formed into a shape corresponding to the shape of the mold.

JP 2003-154415 A

  In the forming apparatus of Patent Document 1, the metal pipe material is heated in the atmosphere to a temperature range where rapid quenching can be performed. In this case, the surface of the metal pipe material is oxidized, and an oxide layer is generated on the surface. When this oxide layer is formed on the surface of the molded product, the appearance and material strength of the molded product may be affected. Therefore, it has been required to suppress the formation of an oxide layer on the surface of the metal pipe material and improve the quality of the molded product.

  This invention is made | formed in view of the said situation, and it aims at providing the shaping | molding apparatus which can improve the quality of a molded article.

  The forming apparatus according to the present invention is a forming apparatus for forming a metal pipe, and includes a heating unit that heats the metal pipe material, and a first gas supply unit that supplies the gas into the heated metal pipe material to expand it. A mold for forming the metal pipe by contacting the expanded metal pipe material, a holding portion for holding the metal pipe material in the inner space of the mold, and a second for supplying an inert gas to the surface of the metal pipe material A gas supply unit and a control unit for controlling the operation of the mold, the heating unit, the first gas supply unit, the holding unit, and the second gas supply unit. When the material is heated, the second gas supply unit is controlled such that the surface of the metal pipe material held in the inner space of the mold by the holding unit is exposed to the inert gas.

  In the molding apparatus according to the present invention, the control unit exposes the surface of the metal pipe material held in the inner space of the mold by the holding unit to an inert gas at least when the metal pipe material is heated by the heating unit. The second gas supply unit is controlled so as to be in the state. In this way, since the surface of the metal pipe material is exposed to the inert gas in the inner space of the mold, the surface of the metal pipe material is prevented from being oxidized when the heating unit performs heating. can do. This makes it possible to perform blow molding while suppressing generation of an oxide layer on the surface of the metal pipe material. As described above, the quality of the molded product can be improved.

  The shaping | molding apparatus which concerns on this invention may further be provided with the cover part which closes the internal space of a metal mold | die at the edge part side in the longitudinal direction of a metal pipe material, when a 2nd gas supply part supplies inert gas. Thereby, it can suppress that an inert gas leaks outside the metal mold | die from the edge part side in the longitudinal direction of metal pipe material.

  In the molding apparatus according to the present invention, when the second gas supply unit supplies the inert gas, the mold has a closed portion that closes the internal space in a cross section viewed from the longitudinal direction of the metal pipe material. You may be prepared. The closing portion closes the internal space in the cross section viewed from the longitudinal direction of the metal pipe material, thereby preventing the inert gas from leaking outside the mold.

  In the molding apparatus according to the present invention, the second gas supply unit includes an inner surface gas supply unit that supplies an inert gas to the inner surface of the metal pipe material, and an outer surface that supplies the inert gas to the outer surface of the metal pipe material. And a surface gas supply unit. Thereby, it can suppress that an oxide layer is produced | generated in both the inner surface and outer surface of a metal pipe material.

  In the molding apparatus according to the present invention, the inner surface gas supply unit may also be used as the first gas supply unit. Thus, the number of parts can be reduced by also using the gas supply unit.

  ADVANTAGE OF THE INVENTION According to this invention, the shaping | molding apparatus which can improve the quality of a molded article can be provided.

It is a schematic block diagram of the shaping | molding apparatus which concerns on embodiment of this invention. It is sectional drawing along the II-II line | wire shown in FIG. 1, Comprising: It is a schematic sectional drawing of a blow molding die. It is a figure which shows the manufacturing process by a shaping | molding apparatus. It is a figure which shows the blow molding process by a shaping | molding apparatus, and a subsequent flow. It is an enlarged view of the periphery of the electrode, (a) is a diagram showing a state in which the electrode holds the metal pipe material, (b) is a diagram showing a state in which the blow mechanism is in contact with the electrode, (c) FIG. 3 is a front view of an electrode. It is sectional drawing along the II-II line | wire shown in FIG. 1, Comprising: It is a schematic sectional drawing of the blow molding die in an inert gas supply process. It is a figure which shows an inert gas supply process. It is a figure which shows the inert gas supply process which concerns on a modification. It is a figure which shows the inert gas supply process which concerns on a modification. It is a figure which shows the inert gas supply process which concerns on a modification. It is a figure which shows the heating part which concerns on a modification.

<Configuration of molding equipment>
As shown in FIG. 1, a molding apparatus 10 for molding a metal pipe includes a blow molding die (die) 13 including an upper die 12 and a lower die 11, and at least one of the upper die 12 and the lower die 11. A slide 82 to be moved, a driving unit 81 that generates a driving force for moving the slide 82, and a pipe holding mechanism (holding unit) that holds the metal pipe material 14 horizontally between the upper mold 12 and the lower mold 11 30, a heating mechanism (heating unit) 50 that energizes and heats the metal pipe material 14 held by the pipe holding mechanism 30, and a blow mechanism (a first mechanism) that blows high-pressure gas into the heated metal pipe material 14 Gas supply unit) 60, drive unit 81, pipe holding mechanism 30, operation of blow molding die 13, control unit 70 for controlling heating mechanism 50 and blow mechanism 60, and blow molding die 13 are forcibly water cooled. You A water circulation mechanism 72, includes a are configured. The blow mechanism 60 also functions as an inert gas supply unit (second gas supply unit) 90 that supplies an inert gas to the surface of the metal pipe material 14 as described later. The specific configuration of the inert gas supply unit 90 will be described later together with the operation. The control unit 70 closes the blow molding die 13 when the metal pipe material 14 is heated to the quenching temperature (AC3 transformation point temperature or higher) and injects high-pressure gas into the heated metal pipe material 14. Take control. In the following description, the formed pipe is referred to as a metal pipe 80 (see FIG. 2B), and the pipe in the middle of completion is referred to as a metal pipe material 14.

  The lower mold 11 is fixed to a large base 15. Moreover, the lower mold | type 11 is comprised with the big steel block, and is provided with the cavity (recessed part) 16 on the upper surface. Further, an electrode storage space 11a is provided in the vicinity of the left and right ends (left and right ends in FIG. 1) of the lower mold 11, and a first electrode 17 configured to be movable back and forth by an actuator (not shown) in the space 11a. A second electrode 18 is provided. On the upper surfaces of the first and second electrodes 17 and 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. 5C). It can be placed so that the metal pipe material 14 fits in the concave grooves 17a and 18a. In addition, tapered front surfaces 17b and 18b whose front surfaces (surfaces in the outer side of the mold) of the first and second electrodes 17 and 18 are recessed toward the concave grooves 17a and 18a in a tapered manner are formed. Yes. A cooling water passage 19 is formed in the lower mold 11 and includes a thermocouple 21 inserted from below at a substantially central position. The thermocouple 21 is supported by a spring 22 so as to be movable up and down.

  The pair of first and second electrodes 17 and 18 located on the lower mold 11 side also serves as a pipe holding mechanism 30 so that the metal pipe material 14 can be raised and lowered between the upper mold 12 and the lower mold 11. Can be supported horizontally. The thermocouple 21 is merely an example of a temperature measuring means, and may be a non-contact temperature sensor such as a radiation thermometer or an optical thermometer. If a correlation between the energization time and the temperature can be obtained, the temperature measuring means can be omitted and configured sufficiently.

  The upper mold 12 is a large steel block having a cavity (concave portion) 24 on the lower surface and a cooling water passage 25 built therein. The upper mold 12 has an upper end fixed to the slide 82. The slide 82 to which the upper mold 12 is fixed is suspended by the pressure cylinder 26 and guided by the guide cylinder 27 so as not to shake. The drive unit 81 according to the present embodiment includes a servo motor 83 that generates a drive force for moving the slide 82. The drive unit 81 is configured by a fluid supply unit that supplies a fluid that drives 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 amount of fluid supplied to the pressurizing cylinder 26 by controlling the servo motor 83 of the driving unit 81. Note that the drive unit 81 is not limited to the one that applies a driving force to the slide 82 via the pressure cylinder 26 as described above. For example, the servo motor 83 is generated by mechanically connecting the drive unit to the slide 82. The driving force to be applied may be applied to the slide 82 directly or indirectly. In the present embodiment, only the upper mold 12 moves, but the lower mold 11 may move in addition to the upper mold 12 or instead of the upper mold 12. In the present embodiment, the drive unit 81 may not include the servo motor 83.

  Further, in the electrode storage space 12a provided in the vicinity of the left and right ends (left and right ends in FIG. 1) of the upper mold 12, as in the lower mold 11, the first is configured so that it can be moved up and down by an actuator (not shown). An electrode 17 and a second electrode 18 are provided. The lower surfaces of the first and second electrodes 17 and 18 are formed with semicircular arc-shaped grooves 17a and 18a corresponding to the upper outer peripheral surface of the metal pipe material 14 (see FIG. 5C). The metal pipe material 14 can be fitted into the concave grooves 17a and 18a. In addition, tapered front surfaces 17b and 18b whose front surfaces (surfaces in the outer side of the mold) of the first and second electrodes 17 and 18 are recessed toward the concave grooves 17a and 18a in a tapered manner are formed. Yes. In other words, when the metal pipe material 14 is sandwiched from above and below by the pair of upper and lower first and second electrodes 17 and 18, the outer periphery of the metal pipe material 14 can be surrounded so as to be in close contact with the entire circumference. Has been.

  FIG. 2 shows a schematic cross section of the blow molding die 13. This is a cross-sectional view of the blow molding die 13 taken along the line II-II in FIG. 1, and shows the state of the die position during blow molding. As shown in FIG. 2, when the reference line S is the upper surface of the lower mold 11 and the lower surface of the upper mold 12, a rectangular recess 11 b is formed on the upper surface of the lower mold 11. A rectangular recess 12 b is formed at a position facing the recess 11 b of the lower mold 11. Further, on the upper surface of the lower mold 11, a rectangular convex portion 11c is formed on one side (left side in FIG. 2) of the concave portion 11b, and the other side (right side in FIG. 2) of the concave portion 11b. ) Is formed with a rectangular convex portion 11d. A rectangular recess 12d is formed on the lower surface of the upper mold 12 at a position corresponding to the protrusion 11c of the lower mold 11, and a rectangular recess 12c at a position corresponding to the protrusion 11d of the lower mold 11. Is formed. When the blow mold 13 is closed, the concave portion 11b of the lower mold 11 and the concave portion 12b of the upper mold 12 are combined to form the main cavity portion MC that is a rectangular space. At this time, the convex part 11c of the lower mold 11 and the concave part 12d of the upper mold 12 are fitted, and the convex part 11d of the lower mold 11 and the concave part 12c of the upper mold 12 are fitted. As shown in FIG. 2A, the metal pipe material 14 disposed in the main cavity portion MC expands to come into contact with the inner wall surface of the main cavity portion MC as shown in FIG. The main cavity portion MC is formed into a shape (here, a rectangular cross section).

  FIG. 6 is a schematic cross-sectional view showing a state when the inert gas supply unit 90 supplies an inert gas. As shown in FIG. 6, when the inert gas supply unit 90 supplies an inert gas, the recess 11b of the lower mold 11 and the recess 12b of the upper mold 12 are separated from the outer surface of the metal pipe material 14, and the gap GP is formed. It will be in the formed state. The step structure of the protrusions 11c and 11d formed on the lower mold 11 and the recesses 12c and 12d formed on the upper mold 12 is such that the length of the metal pipe material 14 is increased when the inert gas supply unit 90 supplies the inert gas. In the cross section seen from the direction, it functions as a closing portion 97 that closes the internal space. Since the convex part 11c of the lower mold 11 and the concave part 12d of the upper mold 12 are fitted, and the convex part 11d of the lower mold 11 and the concave part 12c of the upper mold 12 are fitted, from the longitudinal direction of the metal pipe material 14 In the viewed cross section, the main cavity portion MC is in a closed state. That is, since the protrusion height of the convex portions 11c and 11d of the lower mold 11 is set larger than the gap GP formed between the surface of the blow molding die 13 and the outer surface of the metal pipe material 14, When the mold is opened, the main cavity portion MC does not communicate with the outside of the blow mold 13 in the cross section. Thereby, since the inert gas supplied to the internal space of the blow molding die 13 is not ejected to the side, the surface of the metal pipe material 14 can be effectively exposed to the inert gas. It becomes. Such a closing portion 97 may be provided in substantially the entire region in the longitudinal direction of the blow molding die 13. In this embodiment, the example in which the protrusions (11c, 11d) are formed on the lower mold 11 has been described. However, when the mold is opened, the main cavity MC is not in communication with the outside in the cross section. The shape of the blow molding die 13 is not limited to this. For example, one convex part may be formed on the lower mold 11 side, and one convex part may be formed on the upper mold 12 side.

  The heating mechanism 50 includes a power source 51, a lead wire 52 extending from the power source 51 and connected to the first electrode 17 and the second electrode 18, and a switch 53 interposed in the lead wire 52.

  The blow mechanism 60 includes a high-pressure gas source 61, an accumulator 62 that stores the high-pressure gas supplied from the high-pressure gas source 61, a first tube 63 that extends from the accumulator 62 to the cylinder unit 42, and the first tube 63. A pressure control valve 64 and a switching valve 65 interposed between the second tube 67 and the second tube 67 extending from the accumulator 62 to the gas passage 46 formed in the seal member 44. And an on / off valve 68 and a check valve 69. Note that a tapered surface 45 is formed so that the tip of the seal member 44 is tapered, and the sealing member 44 has a shape that can be fitted and brought into contact with the tapered concave surfaces 17b and 18b of the first and second electrodes. (See FIG. 5). The seal member 44 is connected to the cylinder unit 42 via the cylinder rod 43, and can advance and retract in accordance with the operation of the cylinder unit 42. The cylinder unit 42 is mounted and fixed on the base 15 via the block 41. For the metal pipe material 14, a high-pressure gas is supplied from the gas flow path 46, and the high-pressure gas in the metal pipe material 14 is discharged from the gas flow path 47.

  The pressure control valve 64 serves to supply the cylinder unit 42 with a high-pressure gas having an operating pressure adapted to the pressing force required from the seal member 44 side. The check valve 69 serves to prevent the high pressure gas from flowing back in the second tube 67. The control unit 70 acquires temperature information from the thermocouple 21 by transmitting information from (A) to (A), and controls the pressurizing cylinder 26, the switch 53, the switching valve 65, the on / off valve 68, and the like. .

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

<Operation of molding equipment>
Next, the operation of the molding apparatus 10 will be described. FIG. 3 shows a process from a pipe feeding process in which a metal pipe material 14 as a material is fed to an energization heating process in which the metal pipe material 14 is energized and heated. As shown in FIG. 3, a hardenable steel type metal pipe material 14 is prepared, and the metal pipe material 14 is provided on the lower mold 11 side by a robot arm or the like (not shown), 18 is mounted. Since the grooves 17a and 18a are formed in the first and second electrodes 17 and 18, the metal pipe material 14 is positioned by the 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, an actuator (not shown) that enables the electrodes 17 and 18 to move forward and backward is operated to bring the first and second electrodes 17 and 18 positioned above and below to approach and contact each other. By this contact, both end portions of the metal pipe material 14 are sandwiched by the first and second electrodes 17 and 18 from above and below. Further, this clamping is held in such a manner that the metal pipe material 14 is in close contact with each other due to the presence of the concave grooves 17 a and 18 a formed in the first and second electrodes 17 and 18. However, the configuration is not limited to the configuration in which the metal pipe material 14 is in close contact with the entire circumference, and the first and second electrodes 17 and 18 may be in contact with a part of the metal pipe material 14 in the circumferential direction. .

  Subsequently, at least when the control unit 70 heats the metal pipe material 14 with the heating mechanism 50, the surface of the metal pipe material 14 held in the internal space of the blow molding die 13 with the pipe holding mechanism 30 is inactive. The inert gas supply unit 90 is controlled so as to be exposed to the gas. The controller 70 is in a state where the metal pipe material 14 is held by the pipe holding mechanism 30, and controls the operation of the blow molding die 13 and the pipe holding mechanism 30 in the stage before heating by the heating mechanism 50. As a result, a slight gap GP is formed between the lower mold 11 and the metal pipe material 14, and a slight gap GP is formed between the upper mold 12 and the metal pipe material 14 (FIG. 6). The control unit 70 controls the inert gas supply unit 90 in this state, thereby filling the internal space of the blow molding die 13 (that is, the inside of the gap GP and the metal pipe material 14d) with the inert gas. As a result, the surface (inner surface and outer surface) of the metal pipe material 14 is exposed to the inert gas. The operation content of the inert gas supply unit 90 will be described later.

  After the surface of the metal pipe material 14 is exposed to the inert gas, 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. If it does so, electric power will be supplied to the metal pipe material 14 from the power supply 51, and metal pipe material 14 itself heat | fever-generates with the resistance which exists in the metal pipe material 14 (Joule heat). At this time, the measured value of the thermocouple 21 is constantly monitored, and energization is controlled based on the result.

  FIG. 4 shows the processing content after blow molding and blow molding. Specifically, as shown in FIG. 4, the blow molding die 13 is closed with respect to the heated metal pipe material 14, and the metal pipe material 14 is disposed and sealed in the cavity of the blow molding die 13. . Thereafter, the cylinder unit 42 is operated to seal both ends of the metal pipe material 14 with the seal member 44 which is a part of the blow mechanism 60 (see also FIG. 5). In this seal, the seal member 44 does not directly contact and seal against both end faces of the metal pipe material 14, but indirectly through the tapered concave surfaces 17b and 18b formed on the first and second electrodes 17 and 18. Done. As a result, the sealing performance can be improved because the sealing can be performed over a wide area, the wear of the sealing member due to the repeated sealing operation can be prevented, and further, the crushing of both end faces of the metal pipe material 14 can be effectively prevented. ing. After the sealing is completed, high-pressure gas is blown into the metal pipe material 14 to deform the metal pipe material 14 softened by heating so as to follow the shape of the cavity.

  The metal pipe material 14 is softened by being heated to a high temperature (around 950 ° C.), and can be blow-molded at a relatively low pressure. Specifically, when an inert gas at normal temperature (25 ° C.) at 4 MPa is adopted as the high-pressure gas, the inert gas is eventually heated to around 950 ° C. in the sealed metal pipe material 14. The inert gas thermally expands and reaches approximately 16-17 MPa based on Boyle-Charles' law. That is, the metal pipe material 14 at 950 ° C. can be easily blow-molded. In addition, in order to suppress the oxidation of the metal pipe material 14, the gas supplied by the blow mechanism 60 at the time of blow molding is also preferably an inert gas, but may be air or the like.

  The outer peripheral surface of the metal pipe material 14 blown and expanded contacts the cavity 16 of the lower mold 11 and is rapidly cooled, and simultaneously contacts the cavity 24 of the upper mold 12 to rapidly cool (the upper mold 12 and the lower mold). 11 has a large heat capacity and is controlled at a low temperature, so that when the metal pipe material 14 comes into contact, the heat of the pipe surface is taken away to the mold side at once. Such a cooling method is called mold contact cooling or mold cooling. Thereafter, when the mold is opened, the finished metal pipe 80 is completed.

<Inert gas supply process>
Here, the inert gas supply process which supplies an inert gas to the surface of the metal pipe material 14 is demonstrated in detail. For example, when the metal pipe material 14 is heated to a high temperature around 950 ° C. in the atmosphere, the surface of the metal pipe material 14 is oxidized, and an oxide layer is generated on the surface. When the oxide layer is formed on the metal pipe 80 that is a molded product, the appearance and material strength may be affected. For example, when an oxide layer remains on the surface of the metal pipe 80, the paintability and the like are affected. Further, when an oxide layer is generated on the surface of the metal pipe 80, there is a possibility of causing poor welding. Moreover, a decarburized layer in a state where carbon is removed is formed on the surface of the metal pipe 80 by oxidizing the surface. If such a decarburized layer is formed, the tensile strength and fatigue strength as a material will fall. Therefore, in the molding apparatus 10 of the present embodiment, the surface of the metal pipe material 14 is suppressed from being oxidized by heating in a state where the surface of the metal pipe material 14 is exposed to an inert gas.

  With reference to FIG. 7, an example of an inert gas supply process is demonstrated. As shown in FIG. 7, in the inert gas supply process, a slight gap GP is formed between the lower mold 11 and the metal pipe material 14, and a slight gap is formed between the upper mold 12 and the metal pipe material 14. In a state where the gap GP is formed, the metal pipe material 14 is held in the internal space of the blow molding die 13. As shown in FIG. 7A, the gap GP opens at both end portions 13 a and 13 b of the blow molding die 13 in the longitudinal direction of the metal pipe material 14. As described above, the gap GP opened at the both end portions 13 a and 13 b of the blow molding die 13 is closed by the first electrode 17 and the second electrode 18. That is, the first electrode 17 and the second electrode 18 close the inner space of the blow molding die 13 on the end side in the longitudinal direction of the metal pipe material 14 when the inert gas supply unit 90 supplies the inert gas. It functions as a lid part 96.

  FIG. 7B is a cross-sectional view taken along the line VIIb-VIIb shown in FIG. As shown in FIG. 7B, in the cross section viewed from the longitudinal direction of the metal pipe material 14, the closed portion 97 due to the step structure of the convex portions 11 c and 11 d and the concave portions 12 d and 12 c is the internal space of the blow molding die 13. Is in a closed state. Further, as shown in FIG. 7C, both end portions 96 a in the width direction of the lid portion 96 are disposed outside the closing portion 97. Accordingly, the lid portion 96 can close the entire internal space surrounded by the pair of closing portions 97.

  As shown in FIG. 7A, the inert gas supply unit 90 includes an inner surface gas supply unit 91 that supplies an inert gas GB to the inner surface of the metal pipe material 14, and an outer surface of the metal pipe material 14. An outer surface gas supply unit 92 for supplying the active gas GB. The inner surface gas supply unit 91 and the outer surface gas supply unit 92 of the inert gas supply unit 90 may use the high-pressure gas source 61 of the blow mechanism 60 or the like. Argon, nitrogen, helium, neon, etc. may be employed as the inert gas.

  The seal member 44 of the blow mechanism 60 is used as the inner surface gas supply unit 91. Thus, the inner surface gas supply unit 91 may also be used as the blow mechanism 60. The seal member 44 supplies an inert gas to the inside of the metal pipe material 14 from each end portion in the longitudinal direction of the metal pipe material 14. As a result, the metal pipe material 14 is filled with the inert gas, and the inner surface is exposed to the inert gas. Alternatively, the inert gas may be supplied from one end of the metal pipe material 14 and discharged from the other end. Further, the outer surface gas supply unit 92 is constituted by a flow path 98 formed in the first electrode 17 and the second electrode 18 and communicating with the gap GP in the blow molding die 13. An inert gas is supplied from the flow path 98 of the first electrode 17, and the inert gas is discharged from the flow path 98 of the second electrode 18. However, the flow may be reversed. As a result, the gap GP is filled with the inert gas, and the outer surface of the metal pipe material 14 is exposed to the inert gas.

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

  In the molding apparatus 10 according to the present embodiment, the control unit 70 at least when the metal pipe material 14 is heated by the heating mechanism 50, the metal pipe material held in the internal space of the blow molding die 13 by the pipe holding mechanism 30. The inert gas supply unit 90 is controlled so that the surface of 14 is exposed to the inert gas. Thus, since the surface of the metal pipe material 14 is exposed to the inert gas in the internal space of the blow mold 13, the surface of the metal pipe material 14 is heated when the heating mechanism 50 performs heating. Can be prevented from being oxidized. This makes it possible to perform blow molding while suppressing the formation of an oxide layer on the surface of the metal pipe material 14. As described above, the quality of the molded product can be improved.

  In the molding apparatus 10 according to this embodiment, when the inert gas supply unit 90 supplies an inert gas, the lid 96 closes the inner space of the blow molding die 13 on the end side in the longitudinal direction of the metal pipe material 14. Is further provided. As a result, it is possible to prevent the inert gas from leaking from the end side in the longitudinal direction of the metal pipe material 14 to the outside of the blow molding die 13.

  In the molding apparatus 10 according to the present embodiment, the blow molding die 13 closed the internal space in the cross section viewed from the longitudinal direction of the metal pipe material 14 when the inert gas supply unit 90 supplies the inert gas. A closing portion 97 to be in a state is provided. The closing portion 97 closes the internal space in the cross section viewed from the longitudinal direction of the metal pipe material 14, thereby preventing the inert gas from leaking to the outside of the blow molding die 13.

  In the molding apparatus 10 according to the present embodiment, the inert gas supply unit 90 is inert to the inner surface gas supply unit 91 that supplies an inert gas to the inner surface of the metal pipe material 14 and to the outer surface of the metal pipe material 14. And an outer surface gas supply unit 92 for supplying gas. Thereby, it can suppress that an oxide layer is produced | generated in both the inner surface of the metal pipe material 14, and an outer surface.

  In the molding apparatus 10 according to the present embodiment, the inner surface gas supply unit 91 may also be used as the blow mechanism 60. Thus, the number of parts can be reduced by also using the gas supply unit.

  The present invention is not limited to the embodiment described above.

  The configuration of the inert gas supply unit 90 is not limited to the above-described embodiment, and any configuration is possible as long as the surface of the metal pipe material can be exposed to the inert gas at least at the time of heating. May be adopted. For example, a configuration as shown in FIG. 8 may be adopted. As shown in FIG. 8, a flow path 102 for flowing an inert gas GB may be provided inside the blow molding die 13, and the flow path 102 may be used as the outer surface gas supply unit 92. The flow path 102 is provided substantially at the center in the longitudinal direction of the lower mold 11 and the upper mold 12. With this configuration, the inert gas GB is supplied to the gap GP outside the metal pipe material 14 through one of the flow paths 102 of the lower mold 11 and the upper mold 12, and is discharged from the other flow path 102. At the time of molding, the channel 102 is sealed with a pin 103, and a molding surface is secured by the tip surface of the pin 103. Further, the metal pipe material 14 may be held by pins 101 formed on the lower mold 11 and the upper mold 12 in the internal space of the blow mold 13. Further, as shown in FIG. 8B, a shutter mechanism that closes the gap between the lower mold 11 and the upper mold 12 may be employed as the closing portion 97. The closing part 97 includes a shutter 106 that closes the gap and a drive mechanism 107 that drives the shutter 106.

  Moreover, you may employ | adopt the structure shown in FIG. As shown in FIG. 9, the inert gas GB supplied from the flow path 102 may go inside the metal pipe material 14. At this time, the cover 108 is provided on the lid 96 so as to cover the end of the metal pipe material 14. Further, a flow path or the like is formed in the lid 96 so that the inert gas flowing through the gap GP outside the metal pipe material 14 flows between the cover 108 and the lid 96. As a result, the inert gas in the gap GP flows into the metal pipe material 14. An inert gas is supplied from one channel 102 of the lower mold 11 and the upper mold 12 and is discharged from the other channel 102.

  Moreover, you may employ | adopt the structure shown in FIG. As shown in FIG. 10, an inert gas is caused to flow into the gap GP from both the flow path 98 formed in the first electrode 17 and the flow path 98 formed in the second electrode 18, and then from the flow path 102 of the upper mold 12. May be discharged. The seal member 44 may supply an inert gas into the metal pipe material 14.

  In the above-described embodiment, the metal pipe material 14 is heated by energization heating using the electrodes 17 and 18, but the configuration of the heating unit is not particularly limited. For example, a configuration as shown in FIG. 11 may be adopted. In the molding apparatus shown in FIG. 11, a coil 113 around which a conducting wire is wound so as to surround the outer periphery of the metal pipe material 14 in the internal space of the blow molding die 13 constitutes a heating unit. A conducting wire 112 for supplying AC power to the coil 113 extends in the longitudinal direction, passes through one lid portion 110, and is led out to the outside. According to the said structure, the coil 113 is arrange | positioned in the internal space of the blow molding die 13 by sliding one cover part 110 and the coil 113 from the paper surface left side of FIG. When AC power is supplied to the coil 113, the metal pipe material 14 is heated by high-frequency induction heating. At this time, the lid 110 is formed of an insulating material. However, when the conducting wire is covered with an insulating material, the lid 110 can be formed of a conductive material. After the heating is completed, the one lid part 110 and the coil 113 are slid to the left side of the paper surface and pulled out from the blow molding die 13. While the one lid 110 and the coil 113 are pulled out, the inert gas GB is continuously supplied from the other lid 110 side, so that air is blown from the opening of the blow mold 13 from which the one lid 110 is removed. Intrusion can be suppressed.

  DESCRIPTION OF SYMBOLS 10 ... Molding apparatus, 13 ... Blow molding die (metal mold), 30 ... Pipe holding mechanism (holding part), 50 ... Heating mechanism (heating part), 60 ... Blow mechanism (first gas supply part), 70 ... Control part 90 ... Inert gas supply part (second gas supply part), 91 ... Inner surface gas supply part, 92 ... Outer surface gas supply part, 96 ... Cover part, 97 ... Closure part.

Claims (4)

A forming apparatus for forming a metal pipe,
A heating section for heating the metal pipe material;
A first gas supply section for supplying and expanding a gas into the heated metal pipe material;
A mold that has an upper mold and a lower mold, closes the upper mold and the lower mold, and contacts the expanded metal pipe material to form the metal pipe;
A holding part for holding the metal pipe material in an internal space of the mold;
A second gas supply unit for supplying an inert gas to the surface of the metal pipe material;
A control unit for controlling the operation of the mold, the heating unit, the first gas supply unit, the holding unit, and the second gas supply unit,
The controller is
At least when the metal pipe material is heated by the heating unit, the surface of the metal pipe material held in the internal space of the mold by the holding unit is exposed to the inert gas. And controlling the second gas supply unit,
After the heating process of the metal pipe material by the heating unit is completed , the first gas supply unit is controlled to expand the metal pipe material,
The mold is
When the second gas supply unit supplies the inert gas, the cross section viewed from the longitudinal direction of the metal pipe material includes a closing unit that closes the internal space,
The second gas supply unit is a molding apparatus that supplies the inert gas to at least a gap between the outer surface of the metal pipe and the mold in the internal space.   2. The lid according to claim 1, further comprising a lid that closes the inner space of the mold on an end side in a longitudinal direction of the metal pipe material when the second gas supply unit supplies the inert gas. Molding equipment. The second gas supply unit is
An inner surface gas supply section for supplying the inert gas to the inner surface of the metal pipe material;
The shaping | molding apparatus of Claim 1 or 2 provided with the outer surface gas supply part which supplies the said inert gas to the said outer surface of the said metal pipe material.   The molding apparatus according to claim 3, wherein the inner surface gas supply unit is also used as the first gas supply unit.

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