JPH10180366A - Deep drawiing die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die which needs no additional process accompanied by a high priced installation investment and change of installation line nor induces deterioration of productivity by cooling a blank in the die during forming process. SOLUTION: This deep drawing die is provided with a punch, a die and a blank holder for forming deep drawing products through a plurality of processes. In this case, the punch 11 is equipped on its wall with gas blowing outlet 11a to blow out cooling gas so as to blow out the cooling gas against the inner surface of lower part of the formed port out of the gas blowing outlet 11a when the die 12 arrives at the bottom dead center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a drawing process in which the temperature of a blank due to friction and internal strain is suppressed by cooling gas during drawing in a drawing process which is carried out through a plurality of steps, whereby the drawability in the next step can be significantly improved. It relates to a drawing mold.

[0002]

2. Description of the Related Art As a method of manufacturing three-dimensional products such as various containers from a flat metal plate (hereinafter referred to as a blank), there is a deep drawing method of press working. During this forming process, the blank slides between the blank holder and the die and heats up due to friction when passing over the die shoulder. Further, in the above-mentioned forming process, the temperature of the blank itself rises due to internal strain caused by plastic working.

[0003] The rise in temperature of the blank greatly affects the material property values of the molded article, for example, the r value and the tensile strength. In particular, it is known that the tensile strength of the temperature-raising portion on the wall surface connected to the flange portion is greatly reduced.

[0004] In such a situation, when continuous drawing in a plurality of steps is performed continuously, the effect of the heating temperature of the blank in the initial step of drawing on the drawing in the subsequent step is particularly remarkable.

[0005] For this reason, due to a decrease in the tensile strength of the heated portion of the blank, the blank breaks without being able to withstand the tensile force generated at the time of drawing in a later step.

[0006] Further, the heating temperature of the blank is conducted and accumulated in the drawing die in the subsequent process, causing a reduction in the die clearance, increasing the tensile force applied to the blank, and breaking the blank.

Therefore, in the prior art, a step of cooling the blank is set between the drawing steps and the blank is formed.

[0008]

In the prior art described above, the addition of a cooling step lowers productivity and requires special cooling equipment. As a result, the cost of the product also increases.

[0009] It is an object of the present invention to cool a blank in a molding process die, thereby eliminating the need for expensive equipment investment and additional processes involving line changes, and without reducing productivity. Is to provide a type.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, a deep drawing die according to the present invention is a press die having a punch, a die and a blank holder for forming a deep drawn product through a plurality of steps. An ejection port 11a for ejecting a cooling gas is provided on a wall surface of the punch 11, and the cooling gas is ejected from the ejection port 11a toward the lower inner surface of the molded article when the die 12 reaches a bottom dead center. It is characterized by having done. Further, the punch 11 is provided with a plurality of ejection ports 11a.

[0011]

The cooling gas is blown from the punch side to the heating section of the blank, in particular, the lower part of the side wall of the molded article rising from the blank holder, and a part of the blank is cooled to about room temperature. As a result, since the breaking resistance at the time of forming in the next step is higher than that at the time of raising the temperature, it is formed without breaking in the next step.

In addition, since the heat of heating the blank during continuous molding does not accumulate in the molding die in the next step, the clearance of the die is narrowed and molding can be continued without applying an excessive tensile force to the blank.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2 (a), a press die used in the deep drawing forming method of the present embodiment is a rectangular tube-shaped steel plate blank 1 having a bottom 1a and a flange 1b. A container is formed.

FIG. 1 shows the structure of a press mold.
This will be described in detail with reference to FIG. In the figure, 11 is a punch and 12 is a die. Reference numeral 13 denotes a lower base plate for fixing the punch 11,
The lower die plate 13 is fixed on a bolster (not shown) of the press. Reference numeral 14 denotes a die holder for fixing the die 12. Reference numeral 15 denotes an upper base plate for fixing the die holder 14,
The upper die plate 15 is fixed to a slide (not shown) of the press. Accordingly, the die 12 / die holder 14 and the upper base plate 15 operate integrally with the vertical movement of the press slide. A blank holder 16 is mounted on a cushion pin 17 protruding from the press bolster, and operates with the up and down movement of the cushion pin 17.

In the punch 11, a pipe portion 1 through which a cooling gas passes is provided.
1b and the ejection port 11a are set.

In the drawing, reference numeral 18 denotes a cooling gas supply device, which is connected to a pipe portion 11b of the punch. The gas supply amount can be adjusted by a control valve (not shown).

Next, a method of processing a rectangular cylindrical container using the deep drawing mold of the present invention will be described.

First, the periphery of the rectangular plate 1 (the portion to be the flange 1b of the product container) is held between the die 12 and the blank holder 16. As the press slide descends, the plate 1 is formed into a flanged container having a bottom. Thereafter, when the press slide is formed to a predetermined depth, the press slide reaches the lower limit and rises.

Before and after the lower limit of the press slide,
By jetting the cooling gas from the jet port 11a of the punch 11, the temperature rising part of the blank, that is, the lower part of the side wall of the molded product rising from the blank holder is cooled to room temperature in a short time.

Thereafter, the blank is released from the mold by raising the punch and the blank holder, and is conveyed to the next-step drawing die and formed.

As described above, in the mold of the present step, the blank is cooled to room temperature, thereby recovering the strength to withstand the tensile force in the molding of the subsequent step, and since the temperature of the blank does not rise, the mold of the subsequent step is cooled. Does not increase the temperature and does not narrow the clearance of the mold due to thermal expansion.

Next, a specific example based on this embodiment will be described. As an example of the present invention and a comparative example, rectangular steel containers having the same bottom and flange portions were formed under the same forming conditions using the same steel plate material.

The molding conditions are as follows. The plate material (blank 1) is a deep drawn material of cold-rolled steel plate SCP270D, and the thickness is 1.2 mm. The forming process is a two-step drawing, and the shape of the first drawing is a rectangular tube shape and some corners are acute angles as shown in FIG. 3A and 3B are schematic diagrams of the cross-sectional shape of FIG. 2, FIG. 3A is a schematic diagram of the XX cross-sectional shape of FIG. 2A, and FIG. It is a schematic diagram of a Y section shape. In such a product, the temperature rise of the corner portion Z after the first drawing is remarkably high. Therefore, for points A to G shown in FIGS. 3A and 3B, the temperature and thickness of the blank before and after the second drawing are used as comparison data, and whether or not cooling in the first step is performed. evaluated. Table 1 shows the measurement results.

[0024]

[Table 1]

According to Table 1, it can be seen that the product container of the present invention example is excellent in molding without an extreme local decrease in the plate thickness as compared with the product container of the comparative example. In particular, the plate thickness of the first product at the measurement points D and E is almost the same as the original plate thickness in the present embodiment, but the plate thickness is significantly reduced when the cooling step is omitted.

Further, the temperature rise of the mold by continuous production is suppressed in the case of the present embodiment, and it can be said that this is effective for stabilizing the mold clearance. From Table 1, it can be seen that when the cooling step is omitted, the decrease in the sheet thickness increases with the increase in the number of continuous production, particularly at the measurement points D and E, leading to breakage.

[0027]

As described above, according to the deep drawing forming method of the present invention, in the deep drawing forming process in the upstream process,
By injecting a cooling gas to the part where the temperature rise after processing is remarkable and cooling it to room temperature, deep drawing in the downstream process is performed,
Breakage of the product and reduction of the plate thickness can be eliminated. Further, since the clearance of the mold does not become narrow due to the temperature rise of the mold, it is possible to continuously produce products.

[Brief description of the drawings]

FIG. 1 shows a schematic configuration of a press die (first step) used in an embodiment of the deep drawing forming method of the present invention, and FIG.
FIG. 4 is a cross-sectional view showing a state before processing, and FIG. 4B is a cross-sectional view showing a state immediately after processing (press bottom dead center).

FIG. 2 shows a perspective view of a drawn container.
(A) is a perspective view showing a container of the first step, and (b) is a perspective view showing a container of the second step.

3 shows a schematic view of the cross-sectional shape of FIG.
-X sectional drawing, (b) is YY sectional drawing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Blank 1a Bottom 1b Product flange 11 Punch 11a Spout 11b Piping 12 Die 13 Lower die plate 14 Die holder 15 Upper die plate 16 Blank holder 17 Cushion pin 18 Cooling gas supply device

Claims (2)

[Claims] 1. A press die having a punch, a die and a blank holder for forming a deep drawn product through a plurality of steps, wherein a jet port 11a for jetting a cooling gas is provided on a wall surface of the punch 11, and a die is provided. A deep drawing mold, wherein a cooling gas is ejected from the ejection port 11a toward the lower inner surface of the molded article when the nozzle 12 reaches a bottom dead center. 2. A plurality of ejection ports 11
The deep drawing mold according to claim 1, wherein a is provided.