JP2004351431A - Press molding machine and press molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a press molding machine and a press molding method which can effectively equalize the blank hold pressure in a die. <P>SOLUTION: The press molding machine is composed by interposing an elastic body 13 between each cushion pin 4 and each cushion boss 5. Accordingly, each elastic body 13 is compressed by each cushion pin 4 and each cushion boss 5. The difference of a stroke amount (a flexure amount) of each elastic body 13 is generated corresponding to variations of the contact of each cushion pin 4 with each cushion boss 5. As a result, the blank hold pressure is falsely equalized in the die by absorbing the variations of the contact of each cushion pin 4 with each cushion boss 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a press molding machine and a press molding method, and more particularly to a press molding machine and a press molding method for equalizing a blank hold pressure in a mold.
[0002]
[Prior art]
In order to ensure the high quality of the press-formed product, a uniform molding pressure is applied to the product part of the work and a uniform blank hold pressure is applied to the blank part of the work held between the die and the cushion ring, It is necessary to appropriately maintain the inflow of the work to prevent wrinkles and cracks from occurring. Generally, a conventional press molding machine accommodates a die cushion supported via fluid pressure in a bed of the press molding machine, and aligns a plurality of cushion pins disposed on the die cushion with each cushion pin. It was configured such that a uniform blank hold pressure was obtained by projecting into contact with each cushion boss arranged on the lower surface of the cushion ring. However, in such a press molding machine, the contact between the cushion boss and the cushion pin is varied due to the mounting accuracy of the mold, the operation error of the ram, the processing accuracy of the cushion boss and the cushion pin, and uneven wear. As a result, the blank hold pressure varies and the molding accuracy is reduced.
[0003]
Conventionally, there has been a pressure equalizing mechanism for equalizing the blank hold pressure outside the mold. However, since the apparatus is expensive, the equipment cost increases, and the production cost increases. Thus, Patent Document 1 discloses a press molding machine in which the blank hold pressure is equalized in a mold to reduce equipment costs. In the press molding machine described in this patent document 1, a cylinder type cushion cylinder and a spring type cushion spring are disposed at a plurality of positions along a cushion ring between a cushion ring and a die plate. The cylinder and each cushion spring are stroked to equalize the blank hold pressure in the mold.
[0004]
However, in the press molding machine described in Patent Literature 1, since a cushion cylinder and a cushion spring are separately provided between a cushion ring and a die plate, a large number of cushions are provided in a limited space such as a lower surface of the cushion ring. It has been difficult to effectively arrange the cylinder and the cushion spring. Further, in the press molding machine, since the cushion spring (compression coil spring) is stroked relatively large, there is a possibility that the cushion ring is tilted and the blank hold pressure varies when an uneven load is applied.
[0005]
[Patent Document 1]
JP-A-10-113798 (paragraph numbers 0017 to 0020, FIG. 2)
[0006]
[Problems to be solved by the invention]
Accordingly, the present invention has been made in view of the above circumstances, and a first object is to provide a press molding machine capable of effectively equalizing a blank hold pressure in a mold. A second object is to provide a press molding method capable of effectively equalizing a blank hold pressure in a mold.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present invention comprises a plurality of cushion pins arranged on a die cushion, and a plurality of cushion pins arranged on the lower surface of the cushion ring in alignment with each cushion pin. And a cushion press, comprising: an elastic body interposed between each cushion pin and each cushion boss; and elastically deforming each elastic body to equalize a blank hold pressure in a mold. And a pressure equalizing mechanism.
[0008]
According to a second aspect of the present invention, in the first aspect, the elastic body is a disc spring.
[0009]
According to a third aspect of the present invention, in the first aspect of the present invention, the elastic body is configured by combining a plurality of disc springs.
[0010]
According to a fourth aspect of the present invention, in the second or third aspect of the present invention, a boss block slidable in the mold opening and closing direction with respect to each cushion boss is provided on a pressure receiving surface of each cushion boss, and each elastic body is provided with an elastic body. It is characterized by being interposed between the cushion boss and each boss block.
[0011]
The invention described in claim 5 is characterized in that, in the invention described in any one of claims 1 to 4, a single cushion plate is interposed between each cushion pin and each cushion boss.
[0012]
In order to achieve the above object, an invention according to claim 6 of the present invention is a press molding method using the press molding machine according to claims 1 to 5, wherein a method is provided between each cushion pin and each cushion boss. The elastic body interposed in the mold is elastically deformed to equalize the blank hold pressure in the mold.
[0013]
According to a seventh aspect of the present invention, in the sixth aspect of the invention, the elastic body is configured by combining a plurality of disc springs.
[0014]
Therefore, in the invention described in claim 1, the pressure equalizing mechanism elastically deforms each elastic body interposed between each cushion pin and each cushion boss to equalize the blank hold pressure in the mold. .
[0015]
In the invention described in claim 2, the pressure equalizing mechanism elastically deforms each disc spring interposed between each cushion pin and each cushion boss to equalize the blank hold pressure in the mold.
[0016]
According to the third aspect of the present invention, the pressure equalizing mechanism is configured to elastically deform an elastic body formed by combining a plurality of disc springs interposed between each cushion pin and each cushion boss, and to perform blank holding pressure. In a mold.
[0017]
In the invention described in claim 4, the pressure equalizing mechanism elastically deforms the elastic body interposed between each cushion boss and each boss block to equalize the blank hold pressure in the mold.
[0018]
In the invention described in claim 5, the pressure equalizing mechanism reduces the blank hold pressure by pressing each elastic body interposed between each cushion pin and each cushion boss through the cushion plate to elastically deform the blank. Equilibrate in the mold.
[0019]
In the invention according to claim 6, the elastic body interposed between each cushion pin and each cushion boss is elastically deformed to equalize the blank hold pressure in the mold.
[0020]
According to the seventh aspect of the present invention, an elastic body formed by combining a plurality of disc springs interposed between each cushion pin and each cushion boss is elastically deformed to equalize the blank hold pressure in the mold. Pressurized.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. The press molding machine 1 according to the present embodiment is a draw molding machine. As shown in FIG. 1, in this press molding machine 1, a blank portion of a work W is sandwiched between a die 2 and a cushion ring 3 by lowering a die 2, and the blank portion of the work W is 3 is configured to equalize the blank hold pressure held in the mold by a pressure equalizing mechanism 6 interposed between each cushion pin 4 and each cushion boss 5. Then, the press forming machine 1 abuts the die 2 and the punch 7 in a state where the blank hold pressure is equalized by the equalizing mechanism 6 so that the inflow amount of the work W is appropriately maintained. The structure ensures high molding accuracy of the product.
[0022]
As shown in FIG. 1, each cushion pin 4 is disposed on a die cushion 9 supported by a hydraulic support mechanism 8 so as to be able to move up and down, and a tip of the cushion pin 4 passes through a bolster 10 disposed above the die cushion 9. The bolster 10 protrudes from the upper surface. As shown in FIGS. 1 and 2, each cushion boss 5 is arranged on the lower surface 3 a of the cushion ring 3 in alignment with each cushion pin 4, and is formed integrally with the cushion ring 3. As shown in FIG. 3, each cushion boss 5 has a boss block formed in a ring shape and whose inner peripheral surface is slidably supported by a shaft 11 provided upright on an end surface 5 a of each cushion boss 5. 12 are provided. Thus, each boss block 12 is configured to be slidable with respect to each cushion boss 5 in the axial direction (the vertical direction as viewed in the drawing in FIG. 3). Further, an elastic body 13 configured by combining a plurality of disc springs is interposed between each cushion boss 5 and each boss block 12.
[0023]
The press forming machine 1 includes a pressure equalizing mechanism 6 including the shaft 11, the boss block 12, and the elastic body 13. As shown in FIG. 3, each boss block 12 has a step formed on the inner peripheral surface thereof is locked to a flange 11 a formed at the tip of each shaft 11, so that each boss block 12 is axially oriented (see FIG. 3). The movement is restricted in the vertical direction (as viewed in the drawing). Furthermore, the stroke of the elastic body of the disc spring constituting each elastic body 13 is set in accordance with factors such as the mounting accuracy of the mold, the operation error of the ram, and the difference in the H dimension due to the processing error of each cushion boss 5. The quantity to be combined is determined according to the stroke. Further, the spring constant of the disc spring constituting each elastic body 13 is determined according to the variation width of the load in the axial direction (up and down direction as viewed in the drawing in FIG. 3) input to each cushion boss 5.
[0024]
Then, as the die 2 descends, the cushion ring 3 is pushed down by the die 2 while the work W is held between the die 2 and the cushion ring 3 as the die 2 descends. Thereby, each boss block 12 provided on each cushion boss 5 is pushed up toward each cushion boss 5 by each cushion pin 4, and a plate interposed between each cushion boss 5 and each boss block 12 is formed. Each elastic body 13 formed by combining a plurality of springs is stroked by compression. Then, the press forming machine 1 adjusts each elastic body 13 according to the variation in the contact between the cushion pin 4 and the cushion boss 5 (in the present embodiment, the cushion pin 4 and the boss block 12 are brought into contact with each other). This causes a difference in the stroke amount (bending amount). Thereby, the press molding machine 1 has a structure in which the variation between the cushion pin 4 and the cushion boss 5 is absorbed, and the blank hold pressure is pseudo-equalized in the mold.
[0025]
For example, in a case where each elastic body 13 is configured by combining N pieces of disc springs, as shown in FIG. 4, as N (the number of combined disc springs) increases, the load (repulsive force) rises (see FIG. 4). 4), and the difference in load with respect to the difference in deflection (stroke) is gradually reduced. Therefore, the press forming machine 1 sets the rising of the load to a small value so that the load input to each cushion boss 5 is as close as possible, and the blank hold pressure is pseudo-equalized in the mold. It has a structure to make it.
[0026]
Next, the operation of the present embodiment will be described. First, before molding, the cushion ring 3 is supported by the hydraulic support mechanism 8 such that the upper surface of the cushion ring 3 is substantially the same height as the upper surface of the punch 7. The die 2 is lowered from this state, and the work W is held between the die 2 and the cushion ring 3. Furthermore, when the cushion ring 3 is pushed down by the die 2, each boss block 12 is pushed up by each cushion pin 4 against each cushion boss 5. Thereby, a compression force acts on each elastic body 13 formed by combining a plurality of disc springs interposed between each cushion boss 5 and each boss block 12, and each elastic body 13 is stroked. . Then, the difference in the stroke amount (bending amount) of each elastic body 13 is made according to the variation in the contact between the cushion pin 4 and the cushion boss 5, thereby reducing the variation in the contact between the cushion pin 4 and the cushion boss 5. It absorbs and makes the blank hold pressure pseudo-equalize in the mold.
[0027]
Then, in this state, the die 2 and the punch 7 are brought into contact with each other, and the work W is sandwiched between the molding surfaces of both the die 2 and the punch 7, whereby a high-precision molded product (product) can be obtained.
[0028]
This embodiment has the following effects.
In the press molding machine 1, an elastic body 13 is interposed between each cushion pin 4 and each cushion boss 5.
Therefore, the press molding machine 1 compresses each elastic body 13 with each cushion pin 4 and each cushion boss 5, and makes each elastic body 13 according to the variation between each cushion pin 4 and each cushion boss 5. By making a difference in the stroke amount (bending amount), the variation between the cushion pins 4 and the cushion bosses 5 can be absorbed, and the blank hold pressure can be pseudo-uniformized in the mold. . Accordingly, the press molding machine 1 prevents wrinkles and cracks from occurring in the work W, and ensures high quality of the molded product. Furthermore, equipment costs can be significantly reduced as compared with the press molding machine 1 provided with a homogenizing device for homogenizing the blank hold pressure outside the mold.
Further, the press forming machine 1 is configured by combining the elastic body 13 with a plurality of disc springs.
Therefore, as the number of disc springs to be combined increases, the rise of the load (repulsive force) becomes gentle, and the difference in load with respect to the difference in bending (stroke) is gradually reduced. The press forming machine 1 sets the rising of the load small so that the load input to each cushion boss 5 becomes as close as possible and the blank hold pressure is pseudo-equalized in the mold. Can be done. Accordingly, the press molding machine 1 prevents wrinkles and cracks from occurring in the work W, and ensures high quality of the molded product. Furthermore, equipment costs can be significantly reduced as compared with the press molding machine 1 provided with a homogenizing device for homogenizing the blank hold pressure outside the mold.
[0029]
The embodiment is not limited to the above, and may be configured as follows, for example.
The press molding machine 1 may be configured with a single cushion plate interposed between the cushion pin 4 and the boss block 12. In this case, the degree of freedom in the arrangement of the cushion bosses 5 arranged on the lower surface 3a of the cushion ring 3 is increased, and the cushion bosses 5 are more effectively arranged to equalize the blank hold pressure in the mold. can do.
In the present embodiment, the elastic body 13 is configured by combining a plurality of disc springs. However, the elastic body 13 is not limited to being configured by combining a plurality of disc springs. A nitrogen gas cylinder may be interposed between each cushion boss 5 and the gas chamber of each nitrogen gas cylinder may be connected.
[0030]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a press molding machine and a press molding method capable of effectively equalizing a blank hold pressure in a mold.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of the present press molding machine, particularly showing a schematic configuration.
FIG. 2 is an explanatory view of the present press forming machine, particularly, a perspective view of the cushion ring as viewed from the lower surface.
FIG. 3 is an explanatory view of the press forming machine, particularly showing a state in which a cushion pin and a boss block are in contact with each other.
FIG. 4 is an explanatory diagram of the press forming machine, particularly showing a pressure equalizing characteristic of a disc spring.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Press molding machine 2 Die 3 Cushion ring 4 Cushion pin 5 Cushion boss 6 Pressure equalizing mechanism 12 Boss block

Claims (7)

A press forming machine comprising: a plurality of cushion pins arranged on a die cushion; and a plurality of cushion bosses arranged on a lower surface of a cushion ring in alignment with the cushion pins. A press molding machine, comprising: a pressure equalizing mechanism in which an elastic body is interposed between a boss and each elastic body is elastically deformed to equalize a blank hold pressure in a mold. The press molding machine according to claim 1, wherein the elastic body is a disc spring. The press molding machine according to claim 1, wherein the elastic body is configured by combining a plurality of the disc springs. A boss block slidable in the mold opening and closing direction with respect to each cushion boss is provided on a pressure receiving surface of each cushion boss, and the elastic body is interposed between each cushion boss and each boss block. Item 4. The press molding machine according to item 2 or 3. The press molding machine according to any one of claims 1 to 4, wherein a single cushion plate is interposed between each cushion pin and each cushion boss. A press molding method using the press molding machine according to claim 1, wherein an elastic body interposed between each cushion pin and each cushion boss is elastically deformed to equalize a blank hold pressure in a mold. A press molding method characterized in that the method comprises: The press-forming method according to claim 6, wherein the elastic body is configured by combining a plurality of disc springs.

Images