JPH02142625A - Press working method - Google Patents

Abstract

PURPOSE:To prevent wrinkles and cracks from arising on a work by providing preceding pins which rise and set upward on a lower die, pressing and deforming main parts of the work with the preceding pins to an upper die and pressing the work by the cooperation of the upper and the lower die under that situation. CONSTITUTION:The preceding pins 4 rising and setting upward are provided on the lower die 3. They are energized by gas springs 5 upward. The work W is mounted on the tops of the preceding pins 4 and the upper die 2 is moved in the direction of a bottom dead center. The main parts of the work W are pressed by the preceding pins 4 to the upper die 2 and the work W is deformed by the upper die 2 and the preceding pins 4 to that it meets the working surface of the press die in advance. Under that situation the periphery of the work W is fixed and, further, the work W is pressed by the cooperation of the upper die 2 and the lower die 3. By this method, wrinkles and cracks can be prevented from arising on the work.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a press working method for pressing a workpiece by jointly using an upper die and a lower die.

(Prior art) As shown in FIG. 4, the main part of the press device is set by placing the periphery of the work W on the upper surface of the blank holder 1, and then bringing the upper mold 2 into contact with the periphery of the work W. The upper mold 2 is clamped and further lowered, and the upper mold 2 is lowered against a cushion spring (not shown), and the workpiece W is interposed on the lower mold 3 to perform press processing together with the upper mold 2. (See Utility Model Application Publication No. 58-28734). However, when the workpiece has a shape that undergoes rapid deformation, such as the toeboard of an automobile, a large amount of local elongation occurs, causing wrinkles and m-rips.

To counter this, we repeatedly changed the molding part through actual press tests to set the optimal molding part, managed the material properties of the workpiece W such as the thickness, work hardening index, and plastic anisotropy coefficient, and polished the blank holder surface. The problem is being dealt with by repairing the press mold, such as modifying the bunch radius and repairing the bead.

(Section WA that the invention seeks to solve) There are design limitations to changing the molded part by actual press tests, and managing material properties and repairing press molds requires a long time and is not only troublesome. , cannot be a definitive countermeasure.

Therefore, in view of the above-mentioned points, the present invention reduces the number of changes to the molded part through actual press tests, reduces material property management, reduces press mold repairs, and reduces local elongation of the workpiece to prevent wrinkles and cracks. The purpose of this invention is to provide a press working method that prevents this.

(Means for Solving the Problems) The present invention provides a press working method in which a workpiece is pressed by jointly using an upper die and a lower die facing the upper die, in which a leading pin is provided in the lower die and extends and retracts upward. In addition, a spring means for biasing the leading pin upward is provided, the workpiece is placed on the top end of the leading pin, the upper mold is moved toward the bottom dead center, and the main part of the workpiece is pressed against the upper mold by the leading pin. This method is characterized in that the workpiece is deformed in advance along the press die machining surface using the upper die and the leading pin, the periphery of the workpiece is fixed in that state, and the workpiece is further press-formed by the cooperation of the upper die and the lower die. shall be.

(Example) An example of the press working method of the present invention will be described below based on FIGS. 1 to 3. Note that in FIGS. 1 to 3, parts corresponding to those in FIG. 4 are given the same reference numerals for convenience of explanation. FIG. 1 is a schematic explanatory diagram of the press working method of the present invention and the conventional press working method, and shows the displacement length of the material according to the present invention and the length after press working, and the material according to the conventional press working method and after press working. It is an explanatory view explaining the displacement length of length. Reference numeral 2 in the figure is the upper mold of the press machine, and when the upper mold 2 is lowered, the workpiece W is moved between the upper mold 2 and the blank holder (
(not shown). 2a is upper mold 2
shows the state where it has moved to the bottom dead center. The length is the length from an arbitrary reference point O of the upper mold 2 to the edge of the processing surface of the upper mold 2 along the processing surface of the upper mold 2, that is, the edge of the blank holder, and l
l is the distance above the reference point O of the workpiece W when the workpiece W is pressed against the machining surface of the upper mold 2 by the top of the leading pin 4 which is provided on the lower mold according to the present invention and is urged upward so as to be freely retractable. Type 2
Since the workpiece W is pressed against the machining surface of the upper die 2 by the leading pin 4 and deformed along the heavy snow machining surface, the work W is machined from the base zero point 0 of the upper die 2. The length is approximately equal to the length along the surface to the edge of the processing surface of the upper mold 2.

No. 2 shows a conventional press state in which the leading pin 4 of the present invention is not used, and the edge of the workpiece W' is fixed by the upper die 2 and the blank holder, and from the reference point 0 to the edge of the machined surface of the upper die 2. It shows the length up to and is not deformed along the machining surface of the upper mold 2, so the above-mentioned No! , is shorter than . Each No.8. of. is in the relationship ノ=ノ,〉ノ2.

Therefore, in the press working using the leading pin 4 of the present invention, the length only increases from 11 to 0, but there is no change in the overall length. However, in conventional press working that does not use the leading pin 4, the length changes from No. 2 to No. 2 and requires a large elongation. Therefore, compared to the press working method using the leading pin 4 of the present invention, according to the conventional press working method,
It requires a lot of elongation and causes cracks and wrinkles.

An embodiment in which the pressing method using the leading pin 4 as described above is specifically applied to the toe board W for an automobile will be described based on FIGS. 2 and 3. Fig. 2 shows an automobile toe board W, the shape of which is roughly rectangular in cross section.
Wheel apron parts wa, wa and tunnel part w at both ends
It has a protruding shape. An example of a press working method will be described in which the concave portions of both sides WCI WC of the tunnel portion wb of the toe board W are deformed in advance along the working surface of the upper mold 2 by the leading pins 4.4. FIG. 3 is a sectional view of a main part of a press device for pressing the toe board W (hereinafter referred to as work W), which is the work shown in FIG. It is a diagram.

The leading pin 4 has a columnar shape that is slidably fitted into the inner surface of a hole 3b opened in the processing surface 3a of the lower mold 3, and its lower end is connected to the cylinder of a gas spring 5, which is a spring means provided in the lower mold 3. The locking portion 5d of the cylinder 5a and the flange portion 5e of the piston 5b come into contact with each other due to the repulsive force of the gas compressed and filled in the cylinder 5a. Is it touching? ! (shown by the chain line) is held by m.

Place the work W on the upper surface of the blank holder L in this cradled state, set the work W on the press device, and press the upper die (not shown).
is lowered toward the bottom dead center, and the periphery of the workpiece W is clamped and fixed between the upper die and the blank holder 1. At this time, Kiriku W
is provided on the machining surface of the lower mold 3 so as to be able to appear and retract from the machining surface of the upper mold (
(not shown), and the workpiece W is deformed and held so as to follow the shape of the machining surface of the heavy snow mold.

Further lower the upper mold and tighten the grip pin (not shown).
The upper die is lowered against the reaction force of the die cutter (not shown) through the upper die and lower y! ! The workpiece W is pressed by being held between the two parts. At this time, the top end 4a of the leading pin 4 is pushed down through the work W following the lowering of the upper mold while maintaining the pressing of the work W against the machining surface of the upper mold, and the leading pin 4 is pushed into the lower mold 3. When the upper mold is lowered to the bottom dead center position, the apex m4a is lowered to a position where it is flush with the processing surface 4a of the lower mold 4, as shown by the solid line.

When the press working of the workpiece W is completed as described above, the upper mold moves up toward the top dead center, and the blank holder 1 follows and rises, separating from the lower mold 4, and then the blank holder 1 and the upper mold are separated. Then, the workpiece W is taken out from the press device and the press operation is completed.

In the above description, the leading pin 4 is urged upward by a gas spring using gas pressure, but it is also possible to use a spring means such as a coil spring.

(Effects) According to the press working method of the present invention, a workpiece is placed on the top end of the leading pin that urges the lower mold upward, and the upper mold is lowered toward the bottom dead center, and the leading pin moves the workpiece toward the upper mold. i of
By pressing the parts, the workpiece is deformed in advance so as to follow the machining surface of the upper die, and the periphery of the workpiece is fixed in a cane shape, and then the workpiece is pressed by the upper die and the lower die. Local elongation can be reduced and wrinkles and cracks can be prevented. Therefore, it is possible to easily set the shaped part by actual press tests, and it is possible to manage the material properties of the workpiece and reduce the need for repair of the press die, etc., which has a great effect.

[Brief explanation of the drawing]

Fig. 1 is a schematic comparative explanatory diagram of the press working method of the present invention and the conventional press working method, Fig. 2 is a toe board which is an example of the workpiece of the press working method of the present invention, and Fig. 3 is the present invention. FIG. 4 is an explanatory diagram of a conventional press equipment. 1... Blank holder, 2... Upper die, 3... Lower die 4... Leading pin, 5... Gas spring. Figure 1 Figure 2 Attorney Patent Attorney 1) Osamu Shiro Figure Figure 2

Claims (2)

[Claims] (1) In a press working method in which a workpiece is pressed together by an upper die and a lower die facing the upper die, a leading pin that faces upward and retracts is provided in the lower die, and the leading pin is urged upward. A spring means is provided, the work is placed on the top end of the leading pin, the upper mold is moved toward the bottom dead center, and the leading pin presses the main part of the work against the upper mold, whereby the upper mold and the leading pin press in advance. A press working method characterized by deforming a work along a die processing surface, fixing the periphery of the work in this state, and further pressing the work by jointly using an upper die and a lower die. (2) The method according to claim 1, wherein the spring means is a gas spring, and as the upper die lowers during press working, the top end of the leading pin is pressed by the processing surface of the upper die and sinks into the lower die.