JPS63168231A - Method for forming square cylinder with drawing - Google Patents

Abstract

PURPOSE:To easily constrain the generation of a canning caused at a side wall part by providing a plane pressing plate projecting at a specific height on the die face of the side wall part in the forming of a square steel plate container. CONSTITUTION:A plane pressing plate 8 is provided on the flange face 6 of a die equiv. to the conter part of each straight side part of the hole 5 of a die 4 or on a blank holder pressing face 7. The pressing plate 8 is fitted into the recessed part 9 formed on the die 4 and the projection height is made freely adjustable by the bolt 10 screwed to the die 4. In the case of forming a square shape the projection height of the plane pressing plate 8 is projected in the range of 5-25% of the steel plate thickness by the adjusting bolt 10. The gap between the die 4 and blank holder plate pressing face 7 is therefore narrowed. Now, by performing a drawing the ironing bearing becomes larger by increasing the plate thickness so much as the flange at the center part of the side wall where a material flow is bigger and the force pulling off the bending way is increased as well, so the side wall canning at this part is constrained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to square tube drawing technology, and more specifically, when a steel plate is drawn into a die hole with a punch and formed into a square container, a problem occurs on the side wall of the square container. The present invention relates to a rectangular tube drawing method that makes it possible to suppress canning.

Background technology The shape is the right side part (side wall part) and the opposite side part (corner wall part)
In the rectangular tube drawing formed by
Compared to the lunge (2), the inflow resistance of the side wall 7 lunge (1), which simply undergoes bending deformation at the die shoulder, is weaker, and the bending received at the die shoulder is not fully returned to the side wall, leaving a bend. Wall warping or canning (3) occurs. This phenomenon is greatly aggravated by excessive wall thickness near the center of the side wall, which is far from the affected area of the corner, due to excessive inflow, and causes deterioration of the shape. This canning is similar to hat bending, and when using stainless steel or high-tensile steel plates,
This tendency is significantly exacerbated. Moreover, as the plate thickness becomes thinner and the product rigidity decreases, the drawing depth becomes deeper and the drawing becomes more severe.

On the other hand, stainless steel plates have been widely used for kitchen containers due to their rust prevention and durability, but recently stainless clad steel plates with mild steel cores have been manufactured, which is expected to reduce costs. It has become. Furthermore, thinner-walled stainless steel plates are currently being considered, and countermeasures against canning have become an important issue.

PRIOR ART Methods to prevent the above canning include: ■ A method to increase the effect of unbending by reducing the die shoulder radius on the right side, and ■ A bead on the flange of the right side (such a bead is called a drawbeat). A method of striking from a state where the occurrence of canning is suppressed is by attaching a steel sheet (known as a canning) and pulling it in the depth direction to remove the bending curls.

Problems to be Solved by the Invention The above-mentioned conventional measures taken to prevent canning
Decreasing the shoulder radius of the die increases the inflow resistance of the flange, and the reduction in plate thickness due to unbending increases the risk of drawing breakage. becomes difficult to use.

Even with the method described in (2) in which a drawing bead is provided on the flange portion of the side wall 7 and the inflow of the flange is adjusted by the strength of the bead, new body wrinkles will occur on the side wall due to the effect of repeated bending back at the bead portion and strong uneven tension. However, there is a problem that these wrinkles cannot be removed even by a restriking process. In addition, bead scratches remain on the side wall, so it is often not practical to use.

This invention was made in order to solve the above-mentioned conventional problems, and in particular, it is possible to suppress canning that occurs on the side wall of a rectangular container made of stainless clad steel plate and thin stainless steel by a simple method without requiring any man-hours. This paper aims to propose a method.

Means for Solving the Problems The present invention provides a means for solving the above-mentioned problems of the prior art by adding a plate to the flange surface of the die corresponding to the center of each right side of the die hole or to the plate holding surface of the blank holder. Thick 5
It is characterized in that drawing is performed with the flat pressure plate protruding within a range of 25%.

When forming a rectangular container, the material flows slowly into the corners where it shrinks and deforms, and the material from the side walls, which simply undergo bending deformation, easily flows in. This causes sheet deviation from a part of the corner. It is large in the center of the far side wall.

In this invention, as a means to prevent the above-mentioned rings, a method is adopted in which a flat pressure plate is provided on the flange surface of the die corresponding to the center of each right side of the die hole, or on the plate holding surface of the blank holder. be.

When this flat pressure plate is provided and molded, an appropriate squeezing surface pressure corresponding to the plate thickness change due to the slow inflow of the seven lunges is distributed, and bending back resistance effective for suppressing canning is generated.

That is, since the thickness of the flange at the center of the side wall increases where the material inflow is larger, the ironing surface pressure increases, and as a result, the force for pulling out the bending increases, which is effective in suppressing side wall canning in this area.

However, if the protruding height of the flat pressure plate is less than 5% of the thickness of the workpiece plate, there is no height to counter the increased thickness of the contracted flange at a part of the corner, so effective ironing surface pressure cannot be obtained. %
If this value is exceeded, the blank holder will lift up, causing shrinkage in some corners and increasing flange wrinkles, resulting in new defects. Therefore, in this invention, the range of effective protrusion height of the flat pressure plate is limited to 5 to 25% of the thickness of the workpiece plate.

Note that the die shoulder radius in this method does not need to be small and can be of a size that does not interfere with normal molding, so the reduction in plate thickness due to unbending is slight and the fear of breakage is eliminated.

Disclosure based on drawings of the invention FIG. 1 is a plan view of a die showing one embodiment of the invention;
FIG. 2 is an enlarged longitudinal sectional view taken along line II-I in FIG. 1.

That is, in this invention, a flat pressure plate (8) is attached to the flange surface (6) of the die corresponding to the center of each right side of the hole (5) of the die (4) or the blank holder plate pressing surface (7).
) will be established. This flat pressure plate (8) is installed by fitting it into a recess (9) formed in the die (4) and screwing the bolt (
10) is provided so that the protrusion height can be freely adjusted.

In the above apparatus, when forming a corner, the height adjustment bolt (10) is used to increase the protrusion height of the flat pressure plate (8) to a range of 5 to 25% of the plate thickness. When the flat pressure plate is protruded, the gap between the die (4) and the blank holder plate pressing surface (force) becomes partially narrow, so if drawing is performed in this state, the thickness of the flange at the center of the side wall where a large amount of material flows will be reduced. As a result, the ironing surface pressure increases and the force for pulling away the bending wrinkles also increases, so sidewall canning in this area is suppressed.

Example Using a thin stainless clad steel plate with a thickness of 0.6 mm,
A rectangular container was drawn and formed using a die equipped with a flat pressure plate in the arrangement shown in Figure 1, and the occurrence of canning was investigated by the plate thickness distribution of the side wall flange. A comparison with the results obtained is shown in Table 1. Note that the 7 lunge plate thickness measurement positions in Table 3 are
As shown in the figure.

The size of the flat pressure plate in this example is 100 mm in length x 30 mm in width on the short side of the container, and 200 mm in length on the long side of the container.
mm x width 30mm, protrusion height is 3% and 5% of the plate thickness.

It was changed to 15%, 20%, 25%, and 30%. Furthermore, the die shoulder radius was determined using IOR.

From Table 1, when canning was observed, the flange thickness was thicker than the original plate when the plate was closer to the corner. Therefore, canning was observed in the conventional method, and the protruding height of the flat pressure plate was 3% and 30% outside the scope of the invention
In the case of 3% as well, the occurrence of canning is observed as in the conventional case because no effective squeezing surface pressure can be obtained, and the other 30%
In contrast, with the blank holder lifting up, a part of the corner shrunk, flange wrinkles increased, and the corner wall broke, whereas with the method of the present invention, no canning was observed at all.
In addition, the shrinkage flange wrinkles at some corners did not increase, and a square container of good quality could be formed.

Below are the margins in Table 1. ○: No canning As described in detail of the invention, in the molding of square containers, this invention provides a flat pressure plate that protrudes from the die surface of the side wall by 5 to 25% of the thickness of the workpiece plate. By drawing and forming the die, the bending at the shoulder of the die is effectively restored, and the balance of the material inflow with the corner part is also improved, which has a great effect on suppressing canning.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a die showing one embodiment of the present invention;
Figure 2 is an enlarged vertical cross-sectional view along the line ■-■ in Figure 1, Figure 3 is a diagram showing the measurement position of the flange thickness in the example, and Figure 4 is the shape of the flange and the occurrence of canning after forming a square container. FIG. 3 is a perspective view showing the situation. 1...Side wall part 7 lange 2...Corner part flange 3...Canning 4...Dice 5...hole
6...Flange surface of die 7...Blank holder plate pressing surface 8...Flat pressure plate Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] In the method of drawing a steel plate into a rectangular cylinder using a die and punch, a flange surface of the die corresponding to the center of each right side of the die hole or a plate holding surface of a blank holder is formed within a range of 5 to 25% of the thickness of the steel plate. A rectangular tube drawing method characterized by drawing with a protruding flat pressure plate.