JP2012171006A - Hot press device, and hot press forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity of a formed body and uniformize quenching of the formed body by uniformly cooling a forming surface of a die before forming, and increasing a quenching speed of the formed body in forming.SOLUTION: The formed body 9 obtained by drawing a heated steel plate 10 by die-closing operation of a die 2 is cooled to be quenched in a die-closing condition. A bubble discharge machine 5 generates bubbles 4 by mixing high-pressure gas or high-pressure air in a frothing agent, and the generated bubbles 4 are discharged to respective forming surfaces 21a, 22a of an upper die 21 and a lower die 22 in a die-opening condition before the drawing.

Description

  The present invention relates to a hot press apparatus and a hot press molding method for cooling and quenching a molded body obtained by drawing a heated steel sheet by a mold closing operation of a mold in a mold closed state.

  In recent years, the automobile industry has demanded a lightweight and highly safe vehicle body structure. To meet this requirement, a hot press device is used to obtain a high-strength vehicle body structure without increasing the thickness. A strong molded body is obtained. For example, in Patent Document 1, a plurality of grooves are formed at predetermined intervals on a die forming surface of a die having a die and a punch, and liquid refrigerant is supplied to the grooves from a refrigerant supply device. It has become. Then, after obtaining a molded body by drawing from a steel plate heated to a high temperature using a die and a punch, the molding surface of the punch is brought into contact with the molded body by maintaining the mold closed state, and then the refrigerant supply device Quenching is performed by supplying a liquid refrigerant to the groove and cooling the molded body in contact with the liquid refrigerant flowing in the groove.

  Moreover, in patent document 2, innumerable convex parts are formed on the die forming surface, and a mist-like refrigerant is supplied from a mist generating device to concave parts between the convex parts. And similarly to patent document 1, after obtaining a molded object by drawing from the steel plate heated to high temperature using a die | dye and a punch, the shaping | molding surface of a punch is made to contact the said molded object by hold | maintaining a mold closed state. Then, quenching is performed by supplying a mist-like refrigerant from the mist generating device to the concave portion and bringing the molded body into contact with the mist-like refrigerant and cooling it.

JP 2002-282951 (paragraphs 0024-0026, FIG. 2) JP 2008-36709 A (paragraph 0040 column, FIG. 1)

  However, in the hot press apparatuses disclosed in Patent Documents 1 and 2, when the molded body is cooled and quenched, the cooling rate of the molded body is within a range where the refrigerant contacts and a range where the die and punch molding surfaces come into contact. May be different from each other, and there is a risk of occurrence of insufficient quenching.

  In addition, when the heated steel sheet is repeatedly formed, the mold temperature gradually increases, and when the mold is formed with the temperature increased, quenching is not sufficiently performed. Therefore, there is a desire to cool the molding surface of the die or punch to a predetermined temperature after completing the quenching of the molded body and before performing the next molding.

  However, even when trying to cool the mold by spraying a liquid or mist-like refrigerant on the molding surface of the die or punch, the liquid or mist-like refrigerant will flow from a location where the molding surface is inclined to a small location. If the molding surface cannot be cooled uniformly, and quenching is performed on the molding surface at a non-uniform temperature, there is a possibility that variations in quenching of the molded body may occur.

  Furthermore, in the forming of a steel sheet in a hot press, it is necessary to maintain the mold closed state for a predetermined time in order to cool the formed body, and there is a problem that productivity is poor.

  The present invention has been made in view of such points, and an object of the present invention is to uniformly cool the molding surface of the mold before molding, and to increase the quenching speed of the molded body at the time of molding. Thus, it is an object of the present invention to provide a hot press apparatus and a hot press molding method that can increase productivity and can uniformly quench the molded body.

  In order to achieve the above object, the present invention is characterized in that cooling bubbles are attached along the molding surface of the mold.

  Specifically, a mold comprising an upper mold and a lower mold is provided, and a molded body obtained by drawing a heated steel sheet by the mold closing operation of the mold is cooled and quenched in the mold closed state. In the hot press apparatus, the following solutions were taken.

  That is, in the first invention, it is provided with bubble discharge means for discharging bubbles generated by mixing high-pressure gas or high-pressure air to the foaming agent onto the molding surfaces of the upper mold and the lower mold in the mold open state. It is characterized by.

  According to a second invention, in the first invention, the bubble discharge means includes an arm part that expands and contracts between the side of the mold and the upper and lower molds in the mold open state, and the tip of the arm part And a discharge portion that discharges the bubbles.

  According to a third invention, in the first invention, the bubble discharging means includes an arm portion that protrudes and appears between at least one of the upper mold and the lower mold between the upper mold and the lower mold in the mold open state. And a discharge portion that is provided at the tip of the arm portion and discharges the bubbles.

  In the present invention, the heated steel sheet is drawn by a mold closing operation of a mold composed of an upper mold and a lower mold to obtain a molded body, and then the molded body is cooled and quenched in the mold closed state. The following solution was taken for the hot press molding method.

  That is, the fourth aspect of the invention relates to a steel plate that is heated after the bubbles generated by mixing high-pressure gas or high-pressure air with the foaming agent are discharged and adhered to the molding surfaces of the upper and lower molds in the mold opening state. Is drawn by a mold closing operation of the mold.

  In the first and fourth inventions, since the bubbles are used for cooling the mold, even if the shapes of the molding surfaces of the upper mold and the lower mold are complicated, the bubbles are formed along the molding surfaces by surface tension. It comes to adhere uniformly. Accordingly, the bubbles uniformly absorb the heat of the molding surface, and the molding surface can be uniformly cooled. In addition, since the air bubbles uniformly attached to the molding surfaces of the upper mold and the lower mold uniformly contact the front and back surfaces of the molded body at the time of drawing molding, the front and back surfaces of the molded body are uniformly cooled and the molded body is baked. The filling can be performed uniformly. Further, during the drawing, bubbles are sandwiched between the molded body and each molding surface, so that the liquid part constituting the outer wall of the bubbles is rapidly vaporized to cause an endothermic reaction, and the gas part inside the bubbles Since the heat is dissipated when the is released to the outside, the molded body can be rapidly cooled, the quenching speed can be increased, and the productivity can be increased.

  In the second invention, since the arm part expands and contracts in a substantially horizontal direction, the discharge part can easily move along the molding surfaces of the upper mold and the lower mold, so that the air bubbles adhere to each molding surface reliably and uniformly. It can be.

  In the third invention, since the arm part and the discharge part of the bubble discharge means are accommodated inside the mold when not in use, the equipment layout around the mold can be made compact compared to the second invention.

1 shows a hot press apparatus according to Embodiment 1 of the present invention. It is sectional drawing which shows the hot press apparatus which concerns on Embodiment 1 of this invention, and shows the state which has made the bubble adhere to the molding surface of a metal mold | die. It is sectional drawing which shows the hot press apparatus which concerns on Embodiment 1 of this invention, and shows the state immediately after carrying a steel plate in a metal mold | die in the state which the bubble has adhered to the molding surface of the metal mold | die. The hot press apparatus which concerns on Embodiment 1 of this invention is shown, (a) is sectional drawing which shows the state which is carrying out drawing forming of the steel plate using the metal mold | die with the bubble adhering to the molding surface, b) is an enlarged view of part A of FIG. It is sectional drawing which shows the hot press apparatus which concerns on Embodiment 1 of this invention, and shows the state immediately after removing the quenched molded object. FIG. 3 is a view corresponding to FIG. 2 according to Embodiment 2 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.
Embodiment 1 of the Invention
FIG. 1 shows a hot press apparatus 1 according to Embodiment 1 of the present invention. The hot press apparatus 1 includes a mold 2 including an upper mold 21 and a lower mold 22, and the upper mold 21 of the mold 2 is moved up and down with respect to the lower mold 22 by a lifting / lowering means (not shown). The steel plate 10 can be formed by hot pressing.

  The lower mold 22 is formed with a lower molding surface 22a that bulges upward in a sectional view and gently curves. The upper mold 21 corresponds to the lower molding surface 22a of the lower mold 22. Thus, an upper molding surface 21a that is recessed upward is formed. Then, the heated steel sheet 10 is set on the lower molding surface 22a of the lower mold 22 and drawn by the mold closing operation of the mold 2 so that the molded body 9 is cooled and baked in the mold closed state. I try to put it in.

  A bubble discharger (bubble discharge means) 5 for discharging bubbles 4 (shown in FIGS. 2 to 4) is disposed on the side of the mold 2.

  The bubble discharger 5 includes a box-shaped case 50 placed on a plate-like base member 51 extending along the ground. Inside the box-shaped case 50, high-pressure gas or high-pressure air is used as a foaming agent. A bubble generation unit 52 that generates bubbles 4 by mixing is provided. The high-pressure gas is preferably an incombustible gas such as argon gas or carbon dioxide. Further, the foaming agent is preferably a vegetable oil-based one used in a foam fire extinguisher or the like.

  The box-shaped case 50 is provided with an arm portion 53 formed of an air cylinder. The arm portion 53 includes a cylinder main body portion 53a extending in the horizontal direction disposed above the box-shaped case 50, and the box-shaped case 50 from one end in the longitudinal direction of the cylinder main body portion 53a (on the mold 2 side). A rod portion 53b that penetrates and extends outward, and the rod portion 53b expands and contracts between the side of the mold 2 and between the upper die 21 and the lower die 22 in the mold open state. ing.

  A discharge portion 54 that discharges the bubbles 4 generated by the bubble generation portion 52 is provided at the tip of the rod portion 53b.

  The discharge unit 54 includes a nozzle unit 54a connected to the bubble generation unit 52 by a pipe 55, and the nozzle unit 54a discharges the bubbles 4 generated by the bubble generation unit 52 to the outside. It has become.

  The discharge unit 54 includes a first motor 54b having a rotational axis oriented in the axial direction of the rod portion 53b, and a second motor 54c oriented in a direction intersecting the axial center of the rod portion 53b. And the discharge direction of the nozzle portion 54a can be freely changed by driving the first motor 54b and the second motor 54c, thereby forming the molding surfaces of the upper mold 21 and the lower mold 22 in the mold open state. The bubbles 4 can be discharged along the lines 21a and 22a.

  Next, a method for manufacturing the formed body 9 from the steel plate 10 by hot pressing using the hot pressing apparatus 1 will be described.

  First, as shown in FIG. 2, the arm portion 53 is extended between the upper die 21 and the lower die 22 in a state where the die is opened, and the discharge portion 54 is positioned between the upper die 21 and the lower die 22. The arms 53 are expanded and contracted, and the bubbles 4 are discharged from the nozzles 54a while rotating the first motor 54b and the second motor 54c, thereby forming the molding surfaces of the upper mold 21 and the lower mold 22. Bubbles 4 adhere along 21a and 22a. As described above, since the bubbles 4 are used for cooling the mold 2, even if the shapes of the molding surfaces 21 a and 22 a of the upper mold 21 and the lower mold 22 are complicated, the bubbles 4 are formed by the surface tension. It comes to adhere uniformly along the surfaces 21a and 22a. Accordingly, the bubbles 4 can uniformly absorb the heat of the molding surfaces 21a and 22a, and the molding surfaces 21a and 22a can be uniformly cooled.

  Further, since the arm part 53 expands and contracts in a substantially horizontal direction, the discharge part 54 can easily move along the molding surfaces 21a and 22a of the upper mold 21 and the lower mold 22, so The bubbles 4 can be adhered uniformly.

  Next, as shown in FIG. 3, the heated steel sheet 10 with the bubbles 4 attached to the molding surfaces 21 a and 22 a is carried between the upper mold 21 and the lower mold 22.

  Thereafter, as shown in FIG. 4A, the upper die 21 is lowered to draw the steel plate 10. Then, since the steel plate 10 is drawn by the mold 2 while the bubbles 4 are uniformly in contact with the entire front and back surfaces of the steel plate 10, the front and back surfaces of the formed body 9 are uniformly cooled to quench the formed body 9. Can be performed uniformly. Further, at the time of drawing, as shown in FIG. 4 (b), the bubbles 4 are sandwiched between the molded body 9 and the respective molding surfaces 21a and 22a, so that the liquid portion 4a constituting the outer wall of the bubbles 4 is formed. While rapidly evaporating to cause an endothermic reaction, the gas portion 4b inside the bubble 4 is released to the outside so that heat is dissipated, the molded body 9 is rapidly cooled, and the quenching speed is increased. And increase productivity.

  Then, after a predetermined time has passed in the mold closed state, as shown in FIG. 5, the molded body 9 that has been quenched is removed from the mold, and then the hot press molding is sequentially repeated.

In the first embodiment of the present invention, the arm portion 53 has a cylinder structure. However, the present invention is not limited to this. For example, the arm portion 53 may be extended and contracted by an arm portion of an industrial robot.
<< Embodiment 2 of the Invention >>
FIG. 6 shows a hot press apparatus 1 according to Embodiment 2 of the present invention. The second embodiment is the same as the first embodiment except that the arm portion 53 and the discharge portion 54 of the bubble discharger 5 are housed in the mold 2 except for the point that the second embodiment is the same as the first embodiment. Hereinafter, only parts different from the first embodiment will be described in detail.

  A concave portion 22b extending vertically is formed at the center of the lower mold 22, and the arm portion 53 and the discharge portion 54 are accommodated in the concave portion 22b. The arm portion 53 protrudes from the lower die 22 between the upper die 21 and the lower die 22 in the mold open state, and the arm portion 53 protrudes from the lower die 22 to discharge the discharge. By discharging the bubbles 4 from the portion 54, the bubbles 4 are attached to the molding surfaces 21a and 22a.

  In addition, since the method of manufacturing the molded object 9 from the steel plate 10 using the hot press apparatus 1 according to the second embodiment is the same as that of the first embodiment except that the arm portion 53 and the discharge portion 54 protrude from the lower mold 22. Detailed description is omitted.

  Therefore, according to the second embodiment of the present invention, the arm part 53 and the discharge part 54 of the bubble discharger 5 are accommodated inside the mold 2 when not in use, so that the periphery of the mold 2 is compared with the first embodiment. Equipment layout can be made compact.

  In the second embodiment of the present invention, the lower die 22 is provided with the recess 22b to accommodate the arm portion 53 and the discharge portion 54. However, the present invention is not limited to this. For example, the arm portion is provided inside the upper die 21. 53 and the discharge part 54 may be accommodated, and the arm part 53 and the discharge part 54 may be provided on at least one of the upper mold 21 and the lower mold 22.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a hot press apparatus and a hot press forming method for cooling and quenching a formed body obtained by drawing a heated steel sheet by a mold closing operation of a mold in a closed state.

DESCRIPTION OF SYMBOLS 1 Hot press apparatus 2 Mold 4 Bubble 5 Bubble discharge machine (bubble discharge means)
9 Formed body 10 Steel plate 21 Upper mold 21a Upper molding surface 22 Lower mold 22a Lower molding surface 53 Arm part 54 Discharge part

Claims (4)

It has a mold consisting of an upper mold and a lower mold,
A hot press apparatus that cools and quenches a molded body obtained by drawing a heated steel sheet by a mold closing operation of the mold in a mold closed state,
A hot press apparatus comprising a bubble discharge means for discharging bubbles generated by mixing high-pressure gas or high-pressure air into a foaming agent to each molding surface of an upper mold and a lower mold in a mold open state. The hot press apparatus according to claim 1,
The bubble discharging means includes: an arm part that expands and contracts between the side of the mold and the upper and lower molds in the mold open state; and a discharge part that is provided at a tip of the arm part and discharges the bubbles. A hot press apparatus comprising: The hot press apparatus according to claim 1,
The bubble discharging means is provided at the tip of the arm part that protrudes and protrudes between the upper mold and the lower mold of the mold open state from the inside of at least one of the upper mold and the lower mold. A hot press apparatus comprising: a discharge unit that discharges. This is a hot press molding method in which a heated steel sheet is drawn by a mold closing operation of a mold composed of an upper mold and a lower mold to obtain a molded body, and then the molded body is cooled and quenched in the mold closed state. And
After the bubbles generated by mixing high-pressure gas or high-pressure air with the foaming agent are discharged and adhered to the molding surfaces of the upper and lower molds in the mold open state, the heated steel plate is closed with the mold. A hot press molding method characterized in that the drawing is performed by drawing.

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