JPS59220227A - Forming method of thin plate - Google Patents

Abstract

PURPOSE:To obtain a formed product of high dimensional accuracy by pressing the straight side of a product to be formed from side to bend inside by specified amount in the final stage of drawing of a square tube, and returning to a specified shape by spring back after taking out the formed product. CONSTITUTION:Grooves 1d are formed at specified positions of four faces of a hole 1a of a forming die 1, and pressing tools 8 that fit to the grooves 1d are provided. Recessed parts 4b are formed at specified positions on four faces of a punch 4, and the periphery of a thin plate 2 to be formed is pressed between the flat part 1c of the die 1 and a wrinkle presser 3. Then, it is drawn by a punch 4 and a formed product 2a is obtained. Straight side 4 of the formed product 2a is bent to the inside by the pressing tool 8 and a pressure ram 9. The pressing tool 8 is returned to the groove 1d and the presser 3 is raised and the formed products 2 is removed. The straight side of the formed product 2a is returned to a specified shape by spring back. Thus, the square tube drawing of very thin plate or a plate having large deformation resistance can be made with high dimensional accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a thin plate, and is particularly aimed at improving the dimensional accuracy of a molded product.

Processing that deforms and forms materials generally utilizes the plastic deformation of the material, but no material is a perfect plastic body; it always has elasticity to varying degrees, and elasticity remains even after forming. Therefore, when the external force is removed, a so-called springback phenomenon occurs, which causes deterioration of dimensional accuracy and shape defects of molded products. The larger the material and the smaller the elastic modulus, the larger the material.For example, a molded product made by drawing a thin plate into a rectangular cylinder is shown in Figure 1.
Partial springback occurs, making it impossible to obtain the desired shape and dimensions. In other words, as shown in the same figure (A), springback occurs at a predetermined angle (16) at the right side, and no springback occurs at the corner.
/J In square tube drawing, usually the right side part (A)
In the vicinity of the leg (b), the tensile stress is mainly due to simple bending, and the degree of working is small, so there is a large proportion of remaining elasticity.On the contrary, in the vicinity of the leg (b), there is a large stress caused by a mixture of compressive stress and return stress. The degree of processing is low, and the remaining elasticity is low.

Therefore, it can be said that the springback of a molded product depends on the degree of processing.

As an example of a conventional method for preventing springback in this way, there is a rectangular tube drawing method as shown in FIG. That is, in the same figure, (1) is the mold, (La) is the square hole provided in the center of the mold 1), (1b) is the bottom of the hole (Ia), and (Lc) is the mold. 11) is a plane formed on the upper surface, (2) is a plane formed on the upper surface of the mold (1) (lo
), (2a) is the molded product, (8)
1. is a wrinkle presser that presses the peripheral edge of the thin plate (2) to be formed.
(8a) is a square through hole provided in the center of the wrinkle presser (3), and (4) is a through hole (4) of the wrinkle presser (8).
A square forming punch guided by 8a), (41) a convex bead formed at the corner of the lower end surface of the forming punch (4), and (5) lifting and pressing the forming punch (4). The main pressurizing ram (6) is operated by another pressurizing device (not shown), and the auxiliary pressurizing ram (γ ) is a support for the mold f1).

In FIG. 2 configured as above, the thin plate to be formed (
Appropriate wrinkle-pressing pressure to prevent wrinkles from forming is applied to the peripheral edge of 2) by the auxiliary pressure ram (6) via the flat part (le) of the mold (1) and the wrinkle-pressing device (8). .

Next, the hole (1a) of the mold (1) is squeezed downward by the main pressure ram (6) via the mold punch (4). At the final stage of processing, as shown in Figure 2(b), the bottom inner surface of the molded product (2a) is pressed against the molding punch (4).
is coined between the bead (4tL) and the inner bottom (Lb) of the mold (1). Therefore, the inner surface of the bottom part of the molded product (2a) has a locally large degree of processing, and the springback after the molded product (2a) is taken out is reduced.

However, if the material to be formed is an extremely thin plate material or a plate material with high deformation resistance, the coining process will be impossible, and even if coining is possible, the bottom inner surface of the molded product (2a) will be damaged. Since the part becomes thin due to the coining process, it has drawbacks such as problems in terms of strength and design of the molded product.

The present invention eliminates the drawbacks of conventional processing methods as described above. In other words, in the present invention, in the final stage of rectangular tube drawing, only the right sides of the molded product where springback occurs are pressed from the sides and bent inward, and after the molded product is taken out, the springback causes the molded product to be shaped into a predetermined shape. 8 to 5 showing one embodiment thereof will be described below.

In the figure, (La) is the hole (1a) of the mold (1).
The grooves (4b) formed at predetermined positions on the surface are formed using a forming punch (
4) recessed notches formed at predetermined positions on the four sides; (8) is a pusher fitted into the groove (la) of the square shape (1);
These machining rams (9) K are directly connected to each other and are operated by other pressurizing devices (not shown), and are adapted to move in and out of the hole (La).

By the way, as shown in FIG. 8, the molded product (2a) has a flat part ((C) and a wrinkle presser (8) on the periphery of the thin plate to be molded (2).
The material is squeezed with a forming punch (4) while applying a suitable wrinkle pressing pressure. When the above-mentioned drawing process is completed, the molded product (2a) is formed as shown in Fig. 4.
The right side &l (the 4th side is the pressurizing ram (9
) is bent inward. The amount of bending is determined according to the amount by which the molded product (2a) returns to a predetermined shape due to springback after being taken out.

Next, as shown in FIG. 5, after the processing ram (9) is moved back and the pusher (8) is stored in the groove (d), the crease presser 13) is raised, and the forming punch (4) is moved up. It is raised by the main pressure ram (6). The molded product (2a) is then removed, but since the right side of the molded product (2a) has returned to its predetermined shape due to springback, it can be easily removed.

In addition, although the above embodiment shows a structure in which the mold is fixed and the molding punch is moved, it is possible to fix the molding punch and move the molding punch.
A drawing device in which the mold and wrinkle presser are moved in conjunction with each other may be adopted, and the operation of the presser (8) may be changed by using a cam slide machine groove instead of a pressurizing ram. is free, and is not limited to rectangular cylinder drawing.

As described above, according to the present invention, at the final stage of processing, the right side part of the molded product where springback occurs is pressed from the side and bent inward, and after the molded product is taken out, it returns to the shape. Even if the material to be molded is an extremely thin plate material or a plate material with high deformation resistance, a molded product with good dimensional accuracy can be provided by simple operations. Furthermore, since the springback can be adjusted appropriately by the amount of bending from the other side, even if the plate thickness or material of the molded product is changed, it can be handled with the same mold.

[Brief explanation of the drawing]

Figure 1(a) is a plan view showing the deformation caused by springback when a thin plate material is generally drawn into a rectangular tube.
b) is a cross-sectional view taken along line b-b in the same figure, Figure 2 (FL) is a vertical cross-sectional view showing the state in the middle stage of machining, Figure 2 (FL) is a vertical cross-sectional view showing the state in the final stage of machining, and Figures 3 to 5 8 shows an embodiment of the present invention, FIG. 8 is a longitudinal sectional view showing the state at the end of drawing process, FIG.
The figure is a longitudinal sectional view showing the molded product taken out. In the figure, (1) is the mold, (La) is the hole, (Lo) is the plane, (1d) is the groove, (2) is the thin plate to be formed, (2a) is the molded product, and (8) is the wrinkle presser. , (8a) is a through hole, (4) is a forming punch, (41)) is a recessed notch, and (8) is a push tool. Note that the same reference numerals in the figures indicate the same or corresponding parts. To the substitute land Masuo Oiwa No. 7314 Figure 4 Figure 5 Procedural amendment (voluntary) h' To the Commissioner of the Office of Public Affairs 1, Indication of the case Patent Application No. 1987-97187 2, Title of invention Method for forming thin plates 3, Name of the person making the amendment Name (601) Mitsubishi Electric Co., Ltd. Representative Hitoshi Katayama 4, Agent 5, Detailed explanation of the invention in the specification to be amended 6, Description of the contents of the amendment, page 2, 10 Correct the line ``leg (b)'' to ``corner (b)''. seven

Claims (1)

[Claims] In the final process of drawing a rectangular cylindrical product, etc., the right side of the shaped product is pressed from the side to bend it inward by a predetermined amount, and after the molded product is taken out, it is returned to the predetermined shape using a shrink pack. A thin plate forming method characterized by: