JPH0549371B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a method for evaluating formability in a press to examine in advance whether or not a press die for drawing can reliably form a steel plate. Regarding.

(Prior art) When drawing a steel plate into a predetermined shape using a press, tensile tests, bending tests, Erichsen tests, etc. are carried out in order to know the basic forming characteristics of the steel plate that is the workpiece. I am doing it. However, when the workpiece has a complexly curved three-dimensional shape, such as a panel for an automobile body, it is necessary to draw the steel plate using a mold formed into a predetermined shape. It can be determined whether the mold has an appropriate shape. In other words, unless a steel plate is actually formed using a mold, it is not possible to evaluate the quality of the shape of the mold.

However, when the die for drawing is a large workpiece such as an automobile body panel, it is especially important to check whether the shape of the die is suitable before manufacturing the die. I need to know whether or not.

Therefore, conventionally, as shown in FIG. 3, a drawing die 1 for examination was manufactured to evaluate the formability of the steel plate. The drawing die 1 for consideration shown in FIG.
This shows the female side model, which will be the lower mold, and is made of plaster. This study model 1 includes a main body part A that corresponds to the outer surface of the product, an extra wall part B for molding the part that is bent to the back side of the part molded with the main body part A, and a mold part B. A die face portion C serving as a work supporting surface is formed.

In order to evaluate the formability in a press using such a model 1, a plate material 2 such as an iron plate or an acrylic plate is placed on top of the model 1.
This measures the distance between the plate material 2 and the main body portion A, that is, the depth, and inspects how much the center portion of the plate material 2 sags when the plate material 2 is in contact with the die face portion C. Through these studies, we determined whether or not optimal processing could be achieved when an actual workpiece was drawn using a mold with the same shape as model 1 shown in Figure 3, that is, whether or not the workpiece after drawing was drawn. We evaluate whether or not wrinkles or cracks occur in the workpiece. If it is determined that proper drawing cannot be performed with this shape, the angle and dimensions of the die face part C and extra wall part B may be adjusted by cutting off the model 1 made of plaster. Therefore, the shape of the actual press mold that should achieve smooth drawing processing is being sought.

(Problems to be Solved by the Invention) However, in such a conventional formability evaluation method, the plate material 2 is placed on the model 1 without being formed into the shape of the actual workpiece. The moldability is determined based on experience by visually observing the mounted state. Therefore, when an actual press mold is molded into a shape similar to Model 1, which was determined to be an appropriate shape by this moldability evaluation, and a panel is molded using this mold, the workpiece is May cause defects. In other words, the above-mentioned conventional moldability evaluation method cannot strictly evaluate the actual molding state, and defects cannot be found until the final panel is molded. Therefore, in the past, it was necessary to correct the actual press die after it was formed, and there was a problem in that it was costly and time consuming to correct the actual press die.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to enable evaluation of moldability by performing molding under conditions closer to actual molding.

(Means for Solving the Problems) The present invention for achieving the above object includes installing a metal mesh member between the upper and lower drawing dies to be examined, and bringing the two drawing dies close together. This is a method for evaluating formability in a press, in which the mesh member is drawn and formed, and the formability of the press is evaluated based on the displacement of the lattice of the mesh member.

(Function) Using a drawing die made of plaster etc. into a shape corresponding to the press die to be actually pressed,
When a metal mesh member is formed, the actual deformation state of the workpiece can be observed by the displacement of the mesh member, that is, the mesh lattice, and the formability can be easily evaluated.

(Example) Examples of the present invention will be described below. 1st
Figures A and B show a drawing die 10 on the female side for consideration of the present invention.
This shows the state in which the mesh member 12 is drawn using the drawing die 11 on the male side for consideration.

This drawing die 10 on the female side corresponds to the lower die of the actual press mold, that is, the die, and as in the case shown in FIG.
and a die face portion C. The male drawing die 11 is formed with a concave-convex relationship opposite to that of the female drawing die 10, and corresponds to the upper die of an actual press die, that is, the punch. Furthermore, a blank holder portion 13 corresponding to a blank holder is located at a position facing the die face portion C of the female side drawing die 10, corresponding to an actual press die. These female side drawing die 10, male side drawing die 11, and blank holder part 13 are made of gypsum material, and their surfaces are coated with resin. However, the entire body may be molded with resin, a mixture of sand and resin may be used, and furthermore, these surfaces may be coated with metal by thermal spraying or the like.

Stainless steel, copper, and brass were used as the mesh member 12, and copper and brass were used both with and without annealing. The material diameter of each mesh member 12 was 0.47 mm, and the mesh size was 2 mm.

Male and female drawing dies 10 and 11 for study as described above
In order to evaluate the formability of the press using the mesh member 12 and the mesh member 12, first, the drawing die 10
A mold release agent 14 and a resin 15 are applied to the surface of the mesh member 12, and the mesh member 12 is placed on the drawing die 10 before these are dried. Next, the blank holder part 13 is placed on the mesh member 12, and the male side drawing die 11 is placed on the mesh member 12.
The mesh member 12 is formed by the following steps. As the pressure for molding at this time, a weight or its own weight is used.
After the resin 15 is cured, the male drawing die 11 and the black holder part 13 are removed, and the molded state of the formed mesh member 12 is observed to evaluate the moldability. Note that, depending on the material of the mesh member 12, it is not necessary to freeze the shape after molding with the resin 15.

FIG. 2A shows the mesh member 12 before being molded.
FIG. 2B shows the mesh member 1 formed into a typical cylindrical shape by the evaluation method of the present invention.
2 is shown. In this way, by observing the distortion, displacement, etc. of the mesh or lattice of the mesh member 12, the inflow amount of the material, expansion and contraction, etc. in the actual press working state can be determined, and the formability can be easily evaluated. I can do it. In this example, the material diameter of the mesh member is 0.47 mm, and the mesh size is 2 mm.
However, it may be selected as appropriate depending on the drawing conditions such as the drawing depth and the thickness of the blank material to be drawn.

(Effects of the Invention) As described above, according to the present invention, a metal mesh member is installed between the upper and lower drawing dies for examination, and the upper and lower drawing dies are brought close to each other to form the mesh member. The members were drawn and formed, and the press formability was evaluated based on the displacement of the lattice of the mesh member, so the mold can be easily corrected without creating an actual press mold. , a drawing mold with a shape corresponding to a metal mold is manufactured and used to mold the mesh member, making it possible to reproduce conditions close to the actual molding conditions. This makes it possible to easily and more reliably evaluate moldability, making it possible to easily produce press molds used in actual manufacturing, shortening the mold production process and reducing costs. .

[Brief explanation of the drawing]

FIG. 1A is a sectional view showing a state in which a mesh member is being molded to evaluate the formability of the press die of the present invention, FIG. 1B is an enlarged sectional view of part I in FIG. A is a perspective view showing the mesh member, FIG. 2B is a perspective view showing the mesh member after molding, and FIG.
The figure is a sectional view showing a conventional molding method. 10... Female side drawing die, 11... Male side drawing die, 1
2...Mesh member, 13...Blank holder portion, 15...Resin.

Claims (1)

[Claims] 1. A metal mesh member is installed between the upper and lower drawing dies for consideration, and the mesh member is drawn by bringing the drawing dies close to each other, and pressed by the displacement of the lattice of the mesh member. A moldability evaluation method for PULS that evaluates the moldability of.