JPH0231610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a metal material having superplastic processing characteristics, and more particularly to a method for forming a thin plate material having superplastic processing characteristics.

Superplastic metals exhibit large deformability under a relatively small load in a specific temperature range, and their deformability and deformation stress greatly depend on the strain rate, so in order to produce large deformations, they must be processed in a specific strain rate range. There is a need.

For this reason, when processing superplastic metals in a superplastic state, that is, at a specific temperature range where they exhibit extremely high elongation and at a specific strain rate range, processing using compression such as coining and embossing is particularly important. When adding strain, the thinner the material to be processed, the greater the reduction in thickness, that is, the greater the deformability, and the greater the deformation stress, so the strain rate must be reduced accordingly. This not only makes it difficult to control the speed of the pressure molding equipment, but also increases the time required to mold the material, increases the fuel consumption required to maintain the material at the same temperature, and also increases the required molding load. This results in a significant decrease in mold life due to increased heat and thermal effects.

On the other hand, even if the deformation stress is maintained at a constant level with a forming speed that corresponds to the thickness of the material, a large amount of deformation is required for thin materials, such as corners or overhangs perpendicular to the material. In such areas, breakage occurs due to excessive elongation of the material, or molding defects occur due to decreased plastic flow, and furthermore,
Problems arise when an unfilled portion called a ghost occurs on the back side of the convex molded portion.

In view of the above-mentioned problems, the present invention has been developed to process a metal sheet material having superplastic processing characteristics at a speed similar to or higher than that of normal superplastic metal material processing.
The purpose of the present invention is to provide a new molding method that can accurately and easily mold down to the smallest details.

In other words, the feature of the present invention is that the apparent thickness of the thin plate material is increased by overlapping a plate material having the same superplastic processing characteristics on the back side of the thin plate material to be formed, and The purpose is to form with high processing speed.

Therefore, the details of the present invention will be explained below based on examples.

FIG. 1 shows an example of the forming process of a superplastic thin metal sheet material based on the present invention, and the symbols 1,
2 is the upper mold and lower mold used for this molding process,
The lower die 2 is carved with a concave portion 2a corresponding to a convex portion to be formed on one side of the product.

A superplastic thin metal sheet material 3 to be formed and a dummy sample 4 made of the same type of superplastic metal material that behaves in the same way as the thin metal sheet material 3 are stacked on the lower mold 2 described above, and the upper mold 1 is pressed from above. (Figure 1 A).
The above-mentioned dummy sample 4 is integrated with the thin plate material 3 in order to shorten the time required for molding.
The plate material has a large wall thickness t ₂ to make the wall thickness t ₁ of the thin plate material 3 into a wall thickness t apparently corresponding to the required strain rate. In addition, it also has the function of forming a convex shape on the thin material 3 corresponding to the concave portion 2a of the lower mold 2.

Under these conditions, the upper and lower molds 1 and 2 are heated, the thin plate material 3 and the dummy sample 4 are heated to a specific temperature range determined by the composition of the superplastic metal, and their apparent appearance is When the upper die 1 is pushed down at a processing speed corresponding to the upper plate thickness t, the thin plate 3
The dummy sample 4 and the dummy sample 4 exhibit the same deformation as that exhibited by the material having the plate thickness t, and are apparently molded as one body (FIG. 1B). In other words, in this forming process, the dummy sample 4 follows the thin plate material 3 and deforms while compensating for its plastic flow. There is no local shrinkage in the part, and furthermore, there is no ghost on the back surface of the convex part, and the molding can be performed accurately in a short time.

FIG. 2 shows an example of an embossing process based on the method of the present invention, in which a thick dummy sample 4 made of the same kind of metal is superimposed on a thin plate material 3 made of superplastic metal to be formed. These are molded into a desired shape using a male mold 11 and a female mold 12. Also in this molding method, the plastic flow of the thin plate material 3 is compensated for by the dummy sample 4, so large deformation is prevented by the uneven parts. R-shaped portions are formed in the raised portion 3a on the back surface of the thin plate material 3 that has received the support, thereby avoiding local breakage (FIG. 2B).

〔Example〕

22 wt% Al, 0.5 wt% Cu, 0.05 wt%
A thin disk-shaped material with a thickness of 0.60 mm and a diameter of 30 mm based on a Zn-22% Al eutectoid fine grain superplastic alloy containing Mg is surrounded by a dummy with a thickness of 3.60 mm and a diameter of 30 mm made of the same alloy. When the disc-shaped materials were stacked together, heated to 260℃, and processed at a processing speed of 0.01mm/sec using a mold with a concave portion on one side,
A disk-shaped product with a rectangular protrusion measuring 9 mm in length, 6 mm in width, and 1.5 mm in height could be formed under a load of 2000 kg. On the other hand, in the processing performed without using the dummy disc-shaped material, it was not possible to sufficiently form the above-mentioned rectangular convex portion on the thin disc-shaped material.

In each of the above-mentioned examples, one dummy sample made of the same type of metal was polymerized on one side of the superplastic thin metal sheet material to be formed, where the processing accuracy was not a concern. One preferred embodiment of the present invention is to use two or more dummy samples as a means for adjusting the thickness of the upper plate to correspond to the required strain rate.

As described above, according to the present invention, by polymerizing a dummy member made of the same type of metal onto a superplastic thin metal sheet material to be formed, the apparent thickness of the sheet material can be increased and the apparent amount of strain can be reduced. Because it can be made small, it does not apply large deformation stress to the thin plate material.
It is now possible to form thin plate materials at the same processing speed as normal superplastic metal processing.
Its productivity can be significantly improved. Moreover, during the forming process, the dummy member follows the thin plate material and deforms while compensating for the plastic flow, so even if the amount of deformation required of the thin plate material is excessive, the local strain that occurs in the thin plate material By dispersing the material as much as possible, it is possible to prevent the occurrence of situations that cause molding defects such as breakage, wrinkles, or shrinkage due to a decrease in wall thickness, and transfer molding can be performed with good reproducibility down to the minute parts. be able to.

[Brief explanation of drawings]

FIGS. 1A and 1B are views showing the coining process based on the method of the present invention, and FIGS. 2A and 2B are views showing the same embossing process. 1, 11, 2, 12... type, 3... superplastic metal thin plate material, 4... dummy sample made of the same kind of metal.

Claims (1)

[Claims] 1. Polymerize at least one superplastic metal sheet of the same type as a dummy on one side of the superplastic thin metal sheet material to be formed, which requires lower dimensional accuracy, and adjust the composition of the superplastic metal and both of the sheet materials. A method for forming a superplastic metal material, characterized in that both of the above-mentioned plate materials are integrally pressure-formed in a mold in a temperature range and a strain rate range determined by the combined apparent thickness of the metal material. .