JP5797049B2 - Hot press forming method - Google Patents

Description

  The present invention relates to a hot press forming method for press forming a heated metal plate.

  For example, in press molded products used as panel members for automobile bodies, there is an increasing demand for higher strength in order to simultaneously reduce the weight of the vehicle body and improve the collision performance. As a technique for improving the strength of a press-formed product, hot press molding is known (for example, see Patent Documents 1 and 2). Hot press forming is performed through a heating step for heating a metal plate, a pressing step for press-forming the heated metal plate, and a cooling step for cooling the formed metal plate to perform heat treatment (for example, quenching). Done.

JP 2002-248525 A JP 2005-248253 A

  In the hot press molding described above, after the metal plate is press-molded, the metal plate is cooled by holding the molded metal plate for a predetermined time while being sandwiched by a mold. Thus, by cooling the metal plate in the mold, the molded product can be cured with high dimensional accuracy, but the press mold cannot be used while the metal plate is cooled. There was a problem that productivity was lowered.

  In view of the circumstances as described above, an object of the present invention is to improve productivity by hot press molding.

  The present invention made to achieve the above object is a press provided with a main mold attached to a press machine, and an insert mold that is detachably attached to the main mold and has a molding surface for forming a metal plate. A hot press molding method in which a heated metal plate is press-molded by a molding die, a work setting process for setting the heated metal plate in an insert die, and an insert die in which the metal plate is set as a main die A pressing step of press-molding a metal plate with an insert mold, and a cooling step of removing the insert mold from the main mold and cooling the metal plate inside the insert mold removed from the main mold, A plurality of insert molds are provided, and a pressing process is performed with another insert mold while the cooling process is performed with any of the insert molds.

  Thus, by performing the cooling process of the metal plate inside the insert mold removed from the main mold, it is possible to use the press molding mold even during the cooling process. Therefore, by providing a plurality of insert molds and performing the pressing process with other insert molds while performing the cooling process with any of the insert molds, the press mold can be used efficiently. And productivity can be improved.

  When the heated metal plate comes into contact with oxygen in the air, an oxide film (scale) is formed on the surface of the metal plate. When the oxide film is formed, coating (for example, rust prevention coating) is difficult to be fixed on the surface of the metal plate, so that problems such as generation of rust are likely to occur. Further, when the oxide film is formed, the metal plate becomes hard, so that the wear of the tool due to processing such as trimming or drilling becomes severe. Therefore, if the cooling step is performed in an inert gas atmosphere, contact between the metal plate and air can be avoided, so that formation of an oxide film on the surface of the metal plate can be reliably prevented.

  As described above, according to the present invention, productivity by hot press molding can be increased.

It is sectional drawing of a press molding die. It is sectional drawing of the insert metal mold | die provided in the said press molding metal mold | die. It is sectional drawing of the said press molding die (at the time of press completion). It is sectional drawing of the said insert metal mold | die. It is a figure which shows the hot press molding method which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The press molding die shown in FIG. 1 includes a main die 10 attached to a press machine and an insert die 20 detachably attached to the main die. The main mold 10 includes a fixed main mold 11 attached to the fixed platen 1 of the press machine and a movable main mold 12 attached to the movable platen 2 of the press machine. The insert mold 20 includes a first insert mold 21 detachably attached to the fixed main mold 11 and a second insert mold 22 detachably attached to the movable main mold 12. The fixed main mold 11 is provided with a recess 11 a for attaching the first insert mold 21, and the movable main mold 12 is provided with a recess 12 a for attaching the second insert mold 22. The recesses 11a and 12a are configured to be detachable from the side of the insert mold 20 (in a direction orthogonal to the ascending / descending direction of the movable main mold 12). Specifically, the recesses 11a and 12a include the fixed main mold 11 and An opening is made on one side of the movable main mold 12 (not shown). The first insert mold 21 and the second insert mold 22 are formed with molding surfaces 21a and 22a for molding a metal plate. In the following description, the up and down direction of the movable main mold 12 is referred to as the up and down direction.

  The insert mold 20 is provided with a guide portion 23 for guiding the first insert mold 21 and the second insert mold 22 in the vertical direction. For example, the guide portion 23 is fixed to the first insert mold 21 and is formed in a guide bar extending in the vertical direction and a second insert mold 22, and a guide hole (illustrated) into which the guide bar is fitted and inserted into the inner periphery. (Omitted).

  Next, a hot press molding method according to an embodiment of the present invention will be described. The hot press molding method of the present embodiment is performed by using the above press mold, and (0) heating step, (1) work setting step, (2) pressing step, (3) cooling step, and ( 4) Performed through the workpiece removal process.

(0) Heating process First, after trimming a flat metal plate W (for example, an iron plate) into a predetermined shape, it is put into a heating furnace (not shown) and heated to a predetermined temperature (quenching temperature) (heating process, not shown).

(1) Work setting process Next, as shown in FIG. 2, the heated metal plate W is set inside the insert mold 20 removed from the main mold 10. At this time, the first insert mold 21 and the second insert mold 22 are held in a state of being separated in the vertical direction.

(2) Pressing process The insert mold 20 on which the metal plate W is set is mounted on the main mold 10 (see FIG. 1). Specifically, the first insert mold 21 is mounted in the recess 11 a of the fixed main mold 11, and the second insert mold 22 is mounted in the recess 12 a of the movable main mold 12. In the present embodiment, since the first insert mold 21 and the second insert mold 22 are guided in the ascending / descending direction by the guide portion 23, the position of the second insert mold 22 relative to the first insert mold 21 is guaranteed. Has been. Accordingly, the fixing accuracy between the first insert die 21 and the fixed main die 11 and the fixing accuracy between the second insert die 22 and the movable main die 12 do not affect the press forming accuracy. Can be relaxed. For example, the mounting is completed by fitting the first insert mold 21 and the second insert mold 22 into the recess 11a of the fixed main mold 11 and the recess 12a of the movable main mold 12, respectively. Note that the method of attaching the insert mold 20 to the main mold 10 is not limited to the above, and may be fixed using, for example, a bolt or the like.

  When the insert mold 20 is mounted on the main mold 10, the movable platen 2 is lowered, and the movable main mold 12 and the second insert mold 22 are lowered integrally. Then, the metal plate W is sandwiched from above and below by the molding surface 22a of the second insert mold 22 and the molding surface 21a of the first insert mold 21 (see FIG. 3).

(3) Cooling step When the press forming of the metal plate W is completed, the insert mold 20 is removed from the main mold 10 while the metal plate W is sandwiched (see FIG. 4). In this embodiment, the insert mold 20 can be easily removed from the openings of the recesses 11 a and 12 a provided on one side of the fixed main mold 11 and the movable main mold 12. For example, the movable platen 2 is lifted slightly to release the pressing force of the press machine, and then the insert mold 20 with the metal plate W sandwiched therebetween is pulled out from the openings of the recesses 11a and 12a to the side. Removed from mold 10. The method for removing the insert mold 20 is not limited to this, and the insert mold 20 may be removed from the main mold 10 with the movable platen 2 raised to the top dead center, for example.

  Then, the metal plate W is cooled inside the insert mold 20 removed from the main mold 10, and the metal plate W is subjected to heat treatment (for example, quenching). The cooling step is performed, for example, by leaving the insert mold 20 with the metal plate W sandwiched between them at room temperature for about 20 seconds. Thus, the metal plate W can be hardened with high dimensional accuracy by performing quenching while the metal plate W is sandwiched between the insert molds 20. Further, by cooling the insert mold 20 after being separated from the main mold 10, it is possible to cool earlier than in the case of cooling inside the main mold 10. This cooling step is performed in an inert gas (for example, argon gas) atmosphere, and is performed, for example, in a sealed space filled with an inert gas. As a result, contact between the metal plate W and oxygen in the air is avoided, and oxidation of the metal plate W can be reliably prevented. In addition, if not only a cooling process but a press process is performed in inert gas atmosphere, the oxidation of the metal plate W can be prevented more reliably. On the other hand, when the oxidation of the metal plate W is not particularly problematic, the cooling step may be performed in an air atmosphere.

(4) Workpiece removal step When the metal plate W is cooled to a predetermined temperature or lower, the molded metal plate W is taken out from the insert mold 20. Thus, hot press molding is completed. Thereafter, the empty insert mold 20 is further cooled, and a new heated metal plate is set in the insert mold 20. Thereafter, the hot press forming of the metal plate is repeated through the same steps as described above.

  In the hot press molding method described above, the cooling process of the metal plate W is performed inside the insert mold 20 removed from the main mold 10, so that even during the cooling process, the press molding mold (press machine and main mold) is used. A mold 10) can be used. Therefore, if the above hot press molding is performed using a plurality of insert molds having the same shape, another insert mold is mounted on the main mold 10 while the cooling process is performed with any of the insert molds. Thus, the pressing process can be performed.

  For example, FIG. 5 shows a process when the above hot press molding method is performed using four insert molds A to D. In the example shown in the figure, after performing the pressing process (A2) with the insert mold A, the insert mold B is removed from the main mold while the cooling process (A3) is performed. The press process (B2) is performed after mounting on the mold. Then, while the insert mold B is removed from the main mold and the cooling process (B3) is performed, the insert mold C is mounted on the main mold and the press process (C2) is performed. Similarly, while the insert mold C is removed from the main mold and the cooling process (C3) is performed, the insert mold D is mounted on the main mold and the press process (D2) is performed. While the insert mold D is being cooled (D3), the insert mold A on which a new metal plate is set is mounted again on the main mold, and the press process (A2 ') is performed. As described above, hot press molding can be sequentially performed while circulating and using the plurality of insert dies A to D.

  Thus, according to the hot press molding method described above, a press molding die (press press) is performed by performing a press step with another insert die while performing a cooling step with any insert die. Machine) can be used efficiently, and productivity can be improved. Further, by performing the cooling step and the pressing step in parallel as described above, it is possible to sufficiently lengthen the cooling step without extending the cycle time of the entire hot press forming step.

1 fixed platen 2 movable platen 10 main mold 11 fixed main mold 12 movable main mold 20 insert mold 21 first insert mold 22 second insert mold 23 guide part W metal plate

Claims (2)

Heat for press-molding a heated metal plate by a press-molding die having a main die attached to the press and an insert die that is detachably attached to the main die and has a molding surface for molding the metal plate An intermediate press forming method,
A work setting process in which a heated metal plate is set in an insert mold, a press process in which an insert mold in which a metal plate is set is mounted on a main mold, and the metal plate is press-molded with the insert mold, and an insert mold A cooling process for cooling the metal plate inside the insert mold removed from the main mold,
Providing a plurality of insert metal mold, and the workpiece setting step using either the insert metal mold, and the cooling process using the other insert metal mold, further and said pressing step using other insert metal mold simultaneously Hot press molding method to be performed.   The hot press molding method according to claim 1, wherein the cooling step is performed in an inert gas atmosphere.

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