JP4920772B2 - Flanged metal pipe manufacturing apparatus, manufacturing method thereof, and blow mold - Google Patents

Description

  The present invention relates to a hot blow molding technique for metal pipes.

  Conventionally, a pillar member of a vehicle is a member having high strength from various viewpoints such as ensuring safety when the vehicle falls and ensuring rigidity of a vehicle body, and is strongly demanded to be a particularly lightweight member because of its high mounting position. It has been.

  In order to satisfy these demands at a high level, the inventor heats a metal pipe such as high-tensile steel to near the quenching temperature by energization, and then blow-molds it with a blow mold and simultaneously quenches the surface. Has invented an apparatus and method capable of performing the above (see Patent Document 1).

  With reference to FIGS. 9 to 10, blow molding using a manufacturing apparatus 100 substantially the same as the manufacturing apparatus disclosed in Patent Document 1 will be described. This manufacturing apparatus 100 blows a high-pressure gas into a metal pipe 200 and blow-molds it into a desired shape (here, the middle portion is swollen), and a pipe product 200 (see FIG. 10B). A blow molding die 101 including an upper die 102 and a lower die 104, and a pipe support mechanism 106 that horizontally supports a metal pipe 200 between the upper die 102 and the lower die 104 so as to be movable up and down. The heating mechanism 120 that energizes and heats the pipe 200 supported by the pipe support mechanism 106, the gas blowing mechanism 130 that blows high-pressure gas into the heated pipe 200, and the pipe 200 is heated to the quenching temperature. And a control unit (not shown) for performing a series of controls for closing the blow molding die 101 and blowing high pressure gas into the heated pipe 200. An apparatus for manufacturing a pipe product characterized by Rukoto.

  The heating mechanism 120 is provided with an electrode 122 that can be fitted and sealed to the end surface of the pipe 200, and further, a gas passage 122 a serving as a passage for the high-pressure gas is formed in the electrode 122. The electrode 122 communicates with the gas blowing mechanism 130 through the insulator 123. The gas blowing mechanism 130 is integrated with the actuator 134, and the heating mechanism 120 (electrode 122) can be moved forward and backward with respect to the end surface of the pipe 200 as necessary.

  As a manufacturing procedure, the pipe 200 is prepared so that the pipe 200 is not brought into contact with the blow molding die 101, and the pipe 200 is disposed between the upper mold 102 and the lower mold 104 (FIG. 9A) and energized. The pipe is heated to the quenching temperature (FIG. 9B), and the heated pipe is sandwiched between the upper mold 102 and the lower mold 104, and then high pressure gas is blown into the pipe 200 to perform blow molding (FIG. 10A). )), To obtain a pipe product 200 as a molded product (FIG. 10B). By performing blow molding with such an apparatus and procedure, the pipe which is blow-molded and simultaneously swelled by high-pressure gas comes into contact with the mold surface (maintained at a low temperature) and is quenched. That is, it is possible to create a pillar member having a desired shape that has been surface-treated using high-tensile steel and has no seams.

  On the other hand, even a pillar member made in this way is rarely used alone. That is, in actual use, it is necessary to have a flange for connection (welding) with other parts. Therefore, until now, for example, necessary blank members X and Z are welded to the pipe material Y blow-molded by the apparatus of Patent Document 1 to form a flange α, and the flange α is used to connect with other parts. (See FIG. 11).

JP 2009-220141 A

  However, since the pipe created by the apparatus (method) of Patent Document 1 is a high-tensile steel formed seamlessly, the blank member cannot be easily welded. That is, even though the blank member can be brought into contact with the pillar member (pipe product) and welded from the blank member side (outside), it is very difficult to sandwich and weld from the inside of the pipe product at the same time. On the other hand, there is a problem that not only a sufficient welding strength cannot be secured by welding only from the outside, but also that the pipe product is distorted if the temperature during welding is increased in order to ensure the welding strength.

  The present invention has been made to solve such problems, and it is possible to perform blow molding with a blow mold and subsequently form a necessary flange using the same mold (blow mold). An object of the present invention is to provide a flanged metal pipe manufacturing apparatus, a manufacturing method thereof, and a blow molding die.

In order to solve the above-mentioned problems, the invention according to claim 1 is a metal pipe manufacturing apparatus in which a flange is formed along the longitudinal direction, and includes first and second molds. In a predetermined position before the first and second molds are completely clamped, in addition to the main cavity, the subcavity connected to the main cavity is closed as a space, but the first and second molds are closed. When the entire mold is brought close as it is and completely clamped, the blow molding mold configured so that the subcavity disappears, the heating mechanism for heating to a temperature that softens the metal pipe, and the heated A blow mechanism that seals both ends of the metal pipe and blows high-pressure gas into the metal pipe, and a temperature at which the heating mechanism softens the metal pipe. The high pressure gas is applied to the metal pipe softened by heating by the heating mechanism in a state where the blow mechanism is in a predetermined position before the first and second molds are completely clamped. The metal pipe is blow-molded so as to enter the sub-cavity by inflating the metal pipe so as to enter the sub-cavity side and then closing the first and second molds. The finished product is obtained by crushing and forming the flange.

  That is, the position of the mold at the time of blow molding is not a position where the first and second molds are completely closed, but a position where a predetermined separated state is maintained. In this state, a subcavity recessed in a concave shape is formed in a part of the cavity, so that the metal pipe heated and injected with the high-pressure gas also enters the subcavity. After that, when the first and second molds that are maintained at a certain distance are moved in the abutting direction, the volume of the formed subcavity portion is reduced, and at the same time, the metal made into the subcavity is made of metal. Crush the pipe. By this crushing, the flange is integrally formed on the metal pipe.

The invention described in claim 2 is an invention that captures the invention of claim 1 from a different viewpoint, and is a method of manufacturing a metal pipe in which a flange is formed along the longitudinal direction. It has a second mold, and in a predetermined position before the first and second molds are completely clamped, a state in which a subcavity connected to the main cavity is closed as a space in addition to the main cavity However, when the entire first and second molds are brought close to each other and completely clamped, the blow mold is configured so that the subcavity disappears, and the temperature is such that the metal pipe is softened. A heating mechanism that heats the metal pipe and a blow mechanism that seals both ends of the heated metal pipe and blows high-pressure gas into the metal pipe. The heating mechanism is heated to a temperature at which the metal pipe is softened, and the blow mechanism is in a predetermined position before the first and second molds are completely clamped. The high-pressure gas is blown into the metal pipe softened by heating by expanding the metal pipe so as to enter the subcavity side, and then the first and second molds are closed to close the metal pipe. an invention relates to a method for producing a blow-molded flanged metal pipe, wherein Rukoto give finished products by crushing press the metal pipe to form the flange so as to enter into the sub-cavity.

  According to the present invention, a metal pipe with a flange is formed in the same apparatus by blow-molding a metal pipe using a blow-molding die and using the blow-molding die as it is as a press die. It becomes possible.

It is a schematic block diagram of the metal pipe manufacturing apparatus with a flange as an example of embodiment of this invention. It is a schematic sectional drawing (mold position at the time of blow molding) of the blow molding die from the direction along the arrow II-II line in FIG. It is the figure which showed the manufacturing process of the manufacturing apparatus which concerns on this invention, Comprising: (a) is the figure which showed the state by which the metal pipe was set in the metal mold | die, (b) is the metal pipe clamped by the electrode. It is the figure which showed the state. It is the figure which showed the blow molding process of the manufacturing apparatus which concerns on this invention, and the subsequent flow. It is the enlarged view of an electrode periphery, Comprising: (a) is the figure which showed the state which clamped the metal pipe, (b) was the figure which showed the state which the blow mechanism contact | abutted to the electrode, (c) is an electrode FIG. It is the state figure which paid its attention to the movement of a blow molding metallic mold, and the change of the shape of a metal pipe, (a) is the state at the time of setting a metal pipe to a metallic mold, (b) is the state at the time of blow molding (C) is the figure which showed the state in which the flange was formed by press. FIG. 3 is a state diagram focusing on the movement of a blow molding die (second example) and a change in the shape of a metal pipe, in which (a) shows a state at the time when the metal pipe is set in the die; (b) Is a state at the time of blow molding, and (c) is a view showing a state in which a flange is formed by pressing. FIG. 9 is a state diagram focusing on the movement of the blow molding die (third example) and the change in the shape of the metal pipe, in which (a) shows the state when the metal pipe is set in the die; (b) Is a state at the time of blow molding, and (c) is a view showing a state in which a flange is formed by pressing. It is the schematic block diagram of the conventional manufacturing apparatus, Comprising: (a) is the state in which the material (pipe) was thrown in, and (b) was the figure which showed the state currently heated by supplying with electricity. It is the figure which showed the blow molding process and the subsequent flow in the conventional manufacturing apparatus. It is the figure which showed the example in which the pipe product manufactured with the conventional manufacturing apparatus is utilized as a pillar member of a vehicle, Comprising: (a) is a perspective view, (b) is sectional drawing which follows a beta-beta line.

  Hereinafter, a flanged metal pipe manufacturing apparatus 10 will be described in detail as an example of an embodiment of the present invention with reference to the accompanying drawings. For ease of understanding, the size, thickness, etc. may be partially exaggerated and may not necessarily match the actual product.

<Configuration of manufacturing equipment>
As shown in FIG. 1, the flanged metal pipe manufacturing apparatus 10 includes a blow molding die 13 including an upper die (first die) 12 and a lower die (second die) 11, and an upper die. A pipe support mechanism 30 that horizontally supports a metal pipe (hereinafter sometimes simply referred to as a “pipe”) 14 between the mold 12 and the lower mold 11 and the pipe 14 supported by the pipe support mechanism 30 are energized. A heating mechanism 50 for heating, a gas blowing mechanism 60 for blowing high-pressure gas into the heated pipe 14, and a blow molding die 13 when the pipe 14 is heated to a quenching temperature (AC3 transformation point temperature or higher). And a control unit 70 for performing a series of controls such as blowing high pressure gas into the heated pipe 14 and a water circulation mechanism 72 for forcibly cooling the blow molding die 13 with water.

  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 pipe 14 are formed (see FIG. 5C). The pipe 14 can be placed so as to fit into the 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 serve as a pipe support mechanism 30, and the pipe 14 can be horizontally moved between the upper mold 12 and the lower mold 11 so as to be lifted and lowered. Can support. 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 is suspended by the pressure cylinder 26 and guided by the guide cylinder 27 so as not to sway laterally. 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. Semi-circular concave grooves 17a and 18a corresponding to the upper outer peripheral surface of the pipe 14 are formed on the lower surfaces of the first and second electrodes 17 and 18 (see FIG. 5C). The pipe 14 can be fitted to 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. That is, when the pipe 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 pipe 14 can be surrounded so as to be in close contact with the entire circumference.

  Next, FIG. 2 shows a schematic cross section of the blow molding die 13 viewed from the side surface direction. 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. When viewed from the side, both the upper mold 12 and the lower mold 11 have complex steps formed on their surfaces.

  On the surface of the upper mold 12, a first protrusion 12b, a second protrusion 12c, and a third protrusion 12d are formed when the surface of the cavity 24 of the upper mold 12 is taken as a reference line LV1. A first protrusion 12b that protrudes most to the right side (right side in FIG. 2) of the cavity 24 is formed, and a second protrusion 12c and a third protrusion 12d are formed stepwise on the left side of the cavity 24 (left side in FIG. 2). . On the other hand, the surface of the lower mold 11 is the first recess 11b on the right side of the cavity 16 (right side in FIG. 2) and the left side of the cavity 16 (left side in FIG. 2), where the surface of the cavity 16 of the lower mold 11 is the reference line LV2. A first protrusion 11C is formed.

  Further, the first protrusion 12 b of the upper mold 12 can be fitted with the first recess 11 b of the lower mold 11. Further, the first protrusion 11b of the lower mold 11 can be fitted to the step portion of the second protrusion 12c and the third protrusion 12d of the upper mold 12. As a result of such a configuration, as shown in FIG. 2, a sub-cavity SC having a small volume is formed beside the main cavity MC at the mold position during blow molding.

  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 gas blowing mechanism 60 includes a high-pressure gas source 61, an accumulator 62 that stores 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 A pressure control valve 64 and a switching valve 65 interposed in the tube 63, a second tube 67 extending from the accumulator 62 to the gas passage 46 formed in the seal member 44, and the second tube 67 And an on / off valve 68 and a check valve 69. A tapered surface 45 is formed so that the tip of the sealing member 44 is tapered, and the sealing member 44 has a shape that can be fitted and brought into contact with the tapered recesses 17b and 18b of the first and second electrodes (see FIG. (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.

  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 manufacturing equipment>
Next, the operation of the flanged metal pipe manufacturing apparatus 10 will be described. FIG. 3 shows from the pipe feeding process as a material to the current heating process. As shown in FIG. 3A, a quenchable steel type pipe 14 is prepared, and this pipe 14 is provided with first and second electrodes 17 and 18 provided on the lower mold 11 side by a robot arm or the like (not shown). Place on top. Since the concave grooves 17a and 18a are formed in the first and second electrodes 17 and 18, the pipe 14 is positioned by the concave grooves 17a and 18a. Next, as shown in FIG. 3 (b), an actuator (not shown) that allows the electrodes 17 and 18 to move forward and backward is actuated to bring the first and second electrodes 17 and 18 positioned above and below to approach and contact each other. Make contact. By this contact, both ends of the pipe 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 pipes 14 are 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.

  Subsequently, the switch 53 of the heating mechanism 50 is turned ON. If it does so, electric power will be supplied to the pipe 14 from the power supply 51, and the pipe 14 itself will generate | occur | produce with the resistance which exists in the pipe 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 flow of obtaining the pipe 14 with the flange 14a as a finished product by molding the flange 14a by pressing the pipe 14 after blow molding. First, as shown in FIG. 4A, the blow molding die 13 is closed with respect to the heated pipe 14, and the pipe 14 is disposed and sealed in the cavity of the die 13. Thereafter, the cylinder unit 42 is operated to seal both ends of the pipe 14 with the seal member 44 which is a part of the blow mechanism 60 (see also FIG. 5). This seal is not performed by the seal member 44 directly contacting the both end surfaces of the pipe 14 and sealing, but indirectly through the tapered concave surfaces 17b and 18b formed on the first and second electrodes 17 and 18. Is called. By doing so, 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 is prevented, and further, the crushing of both end faces of the pipe 14 is effectively prevented. . After the sealing is completed, high-pressure gas is blown into the pipe 14 to deform the pipe 14 softened by heating so as to follow the shape of the cavity. Thereafter, as shown in (b), a press operation is performed to form the flange 14a on the pipe 14 after blow molding (details will be described later), and when the mold is opened, the flange 14a is attached as a finished product. A metal pipe 14 is completed.

  The pipe 14 is softened by being heated to a high temperature (around 1000 ° C.), and can be blow-molded at a relatively low pressure. Specifically, when compressed air of 4 MPa and normal temperature (25 ° C.) is employed as the high-pressure gas, the compressed air is eventually heated to around 1000 ° C. in the sealed pipe 14. The compressed air expands thermally and reaches about 16-17 MPa based on Boyle-Charles' law. That is, the 1000 ° C. pipe 14 can be easily blow-molded.

  The outer peripheral surface of the pipe 14 swelled by blow molding is brought into contact with the cavity 16 of the lower mold 11 and rapidly cooled, and at the same time, is brought into contact with the cavity 24 of the upper mold 12 and rapidly cooled (the upper mold 12 and the lower mold 11 are Since the heat capacity is large and the temperature is controlled at a low temperature, if the pipe 14 comes into contact, the heat of the pipe surface is taken away to the mold side at once, and quenching is performed. Such a cooling method is called mold contact cooling or mold cooling. Immediately after being quenched, austenite transforms into martensite. In the latter half of the cooling, the cooling rate was reduced, so that the martensite transformed into another structure (truthite, sorbite, etc.) due to recuperation. Therefore, it is not necessary to perform a separate tempering process.

  As shown in FIG. 6, in the apparatus 10 according to the present invention, the blow molding is not performed in a state where the upper mold 12 and the lower mold 11 are completely closed (clamped). That is, by maintaining a constant separation state, blow molding is performed in a state where the subcavity SC is formed beside the main cavity MC. As a result, the pipe 14 softened by heating and injected with the high-pressure gas enters not only the main cavity MC but also the sub-cavity SC and expands (FIG. 6B).

  Then, the separated upper mold 12 and lower mold 11 are brought close to each other after blow molding or in the middle of blow molding. By this operation, the volume of the subcavity SC becomes smaller and eventually disappears. That is, as the upper and lower molds 11 and 12 approach, a part of the pipe 14 entering the subcavity SC is pressed and crushed (FIG. 6C). As a result, a flange 14 a is formed on the outer peripheral surface of the pipe 14 along the longitudinal direction of the pipe 14. The time from blow molding to flange formation is approximately 1 to 2 seconds depending on the type of the metal pipe 14.

  Further, due to the approach of the upper and lower molds 11 and 12 after blow molding, not only the metal pipe 14 entering the subcavity SC but also the metal pipe 14 in the main cavity MC portion is crushed, but is heated. Since it is softened, the product can be finished without loosening or twisting by adjusting the mold closing speed and compressed gas.

  In the above description, an example in which the flange is formed only on one side of the metal pipe is described, but the present invention is not limited to this. For example, as shown in FIG. 7, the blow molds 211 and 212 can be configured such that two sub-cavities SC are formed during blow molding, and two flanges 214a are formed during pressing. .

  In the above description, the completed metal pipe has a rectangular cross section, and a flange is formed at substantially the center of one side of the cross section. However, the present invention is not limited to this. For example, as shown in FIG. 8, the flange 314 a can be formed at one corner of the cross section of the metal pipe 314.

  Moreover, in the said manufacturing apparatus 10, although the heating mechanism 50 which can be heat-processed between upper and lower metal mold | dies was provided and the metal pipe 14 was heated using the Joule heat by electricity supply, it is not limited to these. . For example, the heat treatment may be performed at a place other than between the upper and lower molds, and the heated metal pipe may be carried between the molds. In addition to using Joule heat by energization, radiant heat from a heater or the like may be used, or heating using high-frequency induction current is also possible.

  As the high-pressure gas, non-oxidizing gases such as nitrogen gas and argon gas can be mainly used, but these are expensive. In this respect, if it is compressed air, it is inexpensive, and even if it leaks into the atmosphere, there is no actual harm and handling is extremely easy. Therefore, the blowing process can be executed smoothly.

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

DESCRIPTION OF SYMBOLS 10 ... Metal pipe manufacturing apparatus 11 with a rib 11 ... Lower mold 12 ... Upper mold 13 ... Blow mold 14 ... Metal pipe 14a ... Flange 17 ... 1st electrode 18 ... 2nd electrode 42 ... Cylinder unit 43 ... Cylinder rod 44 ... Sealing member 46 ... Gas passage 50 ... Heating mechanism 60 ... Blow mechanism MC ... Main cavity SC ... Subcavity

Claims (2)

A metal pipe manufacturing apparatus in which a flange is formed along the longitudinal direction,
First, Ri name a second mold, the first, as a spatial sub-cavity connected with the main cavity in addition to the main cavity in a predetermined position before the second die is completely clamped Although it is in a closed state, when the entire first and second molds are approached as they are and completely clamped, the blow mold configured to disappear the subcavity and the metal pipe are softened. A heating mechanism that heats to a temperature of about, and a blow mechanism that seals both ends of the heated metal pipe and blows high-pressure gas into the metal pipe,
The heating mechanism is heated to a temperature that softens the metal pipe,
In a state where the blow mechanism is in a predetermined position before the first and second molds are completely clamped, the high pressure gas is blown into the metal pipe softened by heating by the heating mechanism. Expand the metal pipe so that it enters the subcavity side,
Then, by closing the first and second molds, the metal pipe that has been blow-molded so as to enter the subcavity is crushed to form the flange, thereby obtaining a finished product. Manufacturing equipment for metal pipes with flanges. A method of manufacturing a metal pipe having a flange formed along a longitudinal direction,
  In the predetermined position before the first and second molds are completely clamped, the subcavity connected to the main cavity is closed as a space in the predetermined position before the first and second molds are completely clamped. However, when the entire first and second molds are brought close to each other and completely clamped, the blow molding mold configured to disappear the subcavity and the degree to soften the metal pipe Utilizing a manufacturing apparatus comprising a heating mechanism that heats to a temperature of and a blow mechanism that seals both ends of the heated metal pipe and blows high-pressure gas into the metal pipe,
  The heating mechanism is heated to a temperature that softens the metal pipe,
  In a state where the blow mechanism is in a predetermined position before the first and second molds are completely clamped, the high pressure gas is blown into the metal pipe softened by heating by the heating mechanism. Expand the metal pipe so that it enters the subcavity side,
  After that, by closing the first and second molds, the metal pipe that has been blow-molded so as to enter the subcavity is crushed to form the flange, thereby obtaining a finished product.
  A method of manufacturing a flanged metal pipe.

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