JPH01241330A - Blank for superplastic forming - Google Patents

Abstract

PURPOSE:To improve a work equipment capacity and to make a die compact by heating the blank plate to be worked thickening the circumferential seal part plate thickness more than the initial plate thickness of a forming part to a superplastic forming temp. and forming it by a gaseous pressure. CONSTITUTION:The seal part plate thickness To around the blank plate 3 to be worked is thickened more than the initial plate thickness of a forming part, the blank plate 3 to be worked thus made is set between dies 1, 2 and subjected to forming by the gas pressure led from an upper die 1 in the state of maintaining it by heating to a super plastic forming temp. The working capacity of a work equipment is thus improved and a die can be made compact.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applied to superplastic forming of spherical tank shells, which are components of fuel tanks for artificial satellite attitude control, and various aerospace equipment parts. Regarding improvement of materials.

[Conventional technology]

Conventional superplastic forming generally involves a mold 1, as shown in Figure 3.
The blank plate 3 to be machined is set between the molds 1 and 2, and while the whole is heated and maintained at the superplastic forming temperature, the blank plate 3 to be machined is lowered by the pressure of gas (for example, Ar gas) introduced from the upper die 1. It is pressed against the inner wall surface of mold 2 to perform molding. At this time, in order to maintain the molding gas pressure, a mold projection pea 5 is integrally provided on the upper die between the periphery of the blank plate 3 to be processed and the lower die 2, and this is installed around the blank plate 3 to be processed. The upper and lower molds are pressed through a gas pressure seal mechanism. As another method, as shown in FIG. 4, a wire 6 is arranged around the lower surface of the upper mold 1 and the upper surface of the blank plate 3 to be processed, and the wire 6 is inserted around the blank plate 3 to be processed. Some are also doing sealing.

[Problem to be solved by the invention]

By the way, the main function of this seal in the conventional molding method described above is to maintain the molding gas pressure as described above, but another function is to protect the workpiece against the radial tensile force associated with molding. The purpose is to prevent the entire flange part of the blank plate from flowing into the mold.

For this reason, several mold protruding beads and wires are installed as necessary, but if there is no space available due to the limitations of the processing equipment (effective zone in the furnace), such as when molding a cup product, it is necessary to It becomes necessary to perform a 7-rule near the shoulder (R part) of the profile of the molded meat product.

In this case, as shown in FIG. 5, as a result of the mold protrusion speed and biting of the wire, the thickness of the blank plate 3 to be processed is reduced near the shoulder of the forming part, so that the radial tensile force pr accompanying forming is reduced. There was a problem in that local non-uniform deformation was concentrated in that part, which eventually led to breakage, making it impossible to perform the desired molding.

The reason for this problem is that the residual thickness of the seal part of the workpiece blank after sealing is 1. However, the initial thickness of the raw plate is t. This is due to the fact that the size also inevitably becomes smaller.

[Means to solve the problem]

Therefore, in the blank for superplastic forming of the present invention, in the blank to be processed by superplastic gas pressure forming, the thickness of the sealing part around the blank before superplastic forming is determined in advance of the forming part. It is characterized by a thicker initial board thickness.

[Effect]

As shown in FIGS. 1 and 2, the above-mentioned superplastic forming blank of the present invention has a thickness T of the sealed portion of the workpiece blank in advance.

, the initial plate thickness t of the forming part. It was designed to be intentionally thicker than the original. When setting the plate thickness, even if there is a seal bite δ, the remaining plate thickness at that part t + = (To - δ)
However, the initial plate thickness of the molded part was also increased.

By using the above-mentioned blank plate, even in the sealed state, the remaining plate thickness t1 of that part becomes larger than the plate thickness of the molded part, so the concentration of radial tensile stress accompanying molding is released, and unevenness in the part is reduced. Deformation and breakage were prevented, and good molding became possible.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a method of processing a modified wall blank plate in which the present invention is applied to a spherical fuel tank for an artificial satellite.

FIG. 2 also shows another embodiment of the invention.

In Figure 1, 1 is the upper mold, 2 is the lower mold, and 3 is the blank plate to be processed. heating.

While maintaining the gas (for example, A) introduced from the upper mold 1,
Since the same means as in the prior art described above is used in that the blank plate 3 to be processed is pressed against the inner wall surface of the lower die 2 and molded into a desired shape using pressure (r gas), the details will be omitted. The feature of the present invention is that the thickness T0 of the sealing part around the blank plate 3 to be processed before superplastic forming is set in advance by the initial thickness t of the forming part. Yoshi is also intentionally made thicker.

There are four typical cutting methods for processing bare plates with altered thickness.

In another embodiment of the present invention shown in FIG. 2, a flat blank plate 3 and a separate frame plate 4 are prepared in a sealed area around the flat plate, and these are bonded using a diffusion bonding method and a seam bonding method. Possible methods include welding, electron beam welding, etc. to join metals in advance. In this case, the surrounding frame material does not need to be a superplastic material (since it is not deformed), and is therefore considered effective in reducing material costs.

〔Effect of the invention〕

As described above, according to the superplastic forming blank of the present invention, the following effects can be obtained.

(1) Problems such as premature breakage of the seal portion of the blank plate to be processed and inability to form can be solved, and it has become possible to produce large parts that are at the limit of processing equipment.

(2) In addition to effective use of existing equipment, it is possible to design compact molds, reduce mold material and manufacturing costs, and improve material yield.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the processing state of an embodiment of the present invention;
FIG. 2 is a side sectional view of another embodiment, and FIGS. 3 to 5 are side sectional views of conventional gas pressure forming. 1... Upper die, 2... Lower die, 3... Raw plate to be processed, 4
... Frame plate, To... Sealing part plate thickness, to... Initial plate thickness of molding part. Figure 1 Figure 2

Claims (1)

[Claims] (1) In the blank to be processed by superplastic gas pressure forming, the thickness of the sealing part around the blank before superplastic forming is configured to be thicker than the initial thickness of the forming part. A superplastic forming blank featuring: