JPS6257727A - Method for forging composite material reinforced with short fiber - Google Patents

Abstract

PURPOSE:To prevent occurrence of cracks in a freely forged surface, by freely forging a composite material composed of an Al or Al-alloy matrix and short-fiber dispersant under a condition where the side of the material are kept by a metallic frame which is richer in plastic-workability than the composite material. CONSTITUTION:A composite material 2 is prepared by scattering short fibers of C, SiC, Al2O3, etc., as a reinforcing material in a matrix made of Al or an Al-alloy. The freely forging surface 6 on the side of the composite material 2 which is not directly contacted with a forging tool is kept with a metallic frame 1 made of Al, Al-alloy, etc., which is richer in plastic-workability than the composite material 2. It is desirable to set the thickness 8 of the metallic frame 1 at about >=30% of its height 9 and it is appropriate to set the clearance between the frame 1 and material 2 at about <=5mm. Thereafter, a forging pressure is applied to the surface 12 of the metallic frame 1 and the surface 4 of the material 2 contacting with a forging tool (not shown in the figure) in the direction shown by the arrows by means of the forging tool. Therefore, the composite material 2 is forged together with the metallic frame 1 and occurrence of cracks in the free forging surface 6 can be prevented.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a process for forming short fiber reinforced composite materials using aluminum or aluminum alloy as a matrix and chopped fibers, whiskers, and particles such as silicon carbide, carbon, and alumina as reinforcement materials. Regarding the method of free forging in.

[Conventional technology and its problems]

Fiber-reinforced composite materials can be divided into those that use continuous fibers as reinforcing materials and those that use short fibers such as chopped fibers, whiskers, and particles. Although the former has excellent strength and heat resistance, it is impossible to form it by various types of plastic processing because it causes fiber breakage. Although the latter is inferior to the former in terms of reinforcement, there is no difference in the directionality of strength (, Ma).Both IJ and F2 are excellent in abrasion resistance, and can be formed by plastic working such as forging and extrusion.

However, in reality, in order to obtain the latter product, that is, a short fiber reinforced composite material, the machinability is very poor, so it is necessary to make it into a shape as close to the product as possible by extrusion, free forging, die forging, etc.
It is necessary to cut it. This will reduce processing costs and increase product yield.

Short fiber-reinforced composite materials are generally made using high-pressure casting or powder metallurgy, but due to equipment limitations in both cases, the shapes that can be manufactured are limited to relatively simple shapes such as cylinders and prisms. ing. Therefore, free forging is required to obtain the desired shape, and free forging is also required as a pre-process before extrusion or die forging.

Although short fiber-reinforced composite materials have plastic workability that allows them to be extruded and forged, their deformation resistance is high (and their workability cannot be said to be good. Moreover, the characteristics of this material are high elasticity and only a little elongation). When performing free forging, the forging pressure is applied to the surface of the composite material (2), as shown in Figure 2 (side view of the forging tool (3) set on the composite material (2)). The forging force applied to the composite material (2) through the contact tool surface (4) that is in direct contact with the forging tool (3) is applied to the composite material (2) as shown in Figure 2B (side view of the forging pressurized state). Metal flow (5) occurs in the composite material (2) of the workpiece, and tension (force) acts on the side of the composite material that is not directly connected to the forging tool, that is, the free forging surface (6). Therefore, forging pressure is applied. There is a problem that cracks are likely to occur on the free forging surface (6).

These problems also apply to short fiber-reinforced composite materials (hereinafter tentatively referred to as composite materials) that have aluminum or aluminum alloy as a matrix, and the object of the present invention is to find a new forging method that solves these problems. This is the purpose of

[Structure of the invention]

When free forging a composite material with a forging tool, the present invention is designed to perform free forging with a metal frame of aluminum or aluminum alloy applied or held against it so as to prevent cracking even if tension is generated on the free forging surface. It is characterized by

This will be explained in more detail with reference to FIG. FIG. 1 shows a perspective view of a metal frame (1) according to the invention, and FIG. 1B shows a prismatic composite material (2) fitted into the metal frame (1) according to the invention.
) is a perspective view of.

Figure 1C shows that the cylindrical composite material (2) is attached to a cylindrical metal frame (
1), the first diagram shows a side sectional view of the metal frame (6) to restrain the free forging surface (6).
1) is assigned. The forging pressure (arrow) is applied by the forging tool to the contact tool surface (4) and the surface 021 of the frame (1).
It is added together with.

Regarding the size of the metal frame, in order to prevent the frame from buckling during forging, the thicker the frame the better, but from the standpoint of forging workability, the smaller the length, the more efficient it is. It is both practical and economical. The wall thickness (8) of the frames of Figure 1 and Figure 1 C may be 30 inches or more of the frame height 9).

The clearance between the metal frame and the composite material depends on the type of composite material to be forged, but if it is approximately 5 mm or less, when free forging is performed, the composite material will be restrained by the metal frame before cracks occur on the free surface. Ru.

Figure 3 is a side view of the forging according to the present invention using simple upsetting. As shown in Figure 6, the composite material (2) becomes drum-shaped together with the metal frame (1), and when the frame is made thicker, it becomes as shown in Figure 6B. Therefore, the type of composite material and forging The type of aluminum alloy used as the frame and the size of the frame should be considered depending on the shape and extra length of the composite material to be used.Both aluminum and aluminum alloy used for the inner frame have better forging workability than composite materials, so
There is no problem with using anything, but JIS 2014 is recommended in terms of binding force to prevent cracking of composite materials.

2024.5056.5083.6061 . 7075
(However, the frame can be made smaller by using a high-strength alloy.

Composite materials to which the method of the present invention can be used include chopped fibers such as silicon carbide fibers, carbon fibers, alumina fibers, and boron fibers as reinforcing materials, whiskers such as silicon carbide, silicon nitride, and alumina, and silicon carbide, silicon nitride, It may be one in which one or more types of particles of alumina or the like are dispersed. The content of the reinforcing material in the matrix can be appropriately selected depending on the intended use of the product after forging.

〔Example〕

Example 1 A matrix of J-56061 with 20 vol. of silicon carbide and whisker reinforcing materials dispersed therein was cast into a diameter of 80 mm by high-pressure casting. A cylindrical composite material sample with a height of 65 mm was prepared. One of the samples was simply upset forged as shown in Figure 2B, and the height was α0.
When forged to 155 mm, cracks occurred on the free forging surface (6). Therefore, as shown in Figure 1C, another cylindrical sample (2) of the same type was prepared with a wall thickness (8) of JIS 7075 of 2.
When it was fitted into a 0mm cylindrical frame (1) and upset forged according to the present invention as shown in FIG. It did not occur.

Example 2 A 999% AI matrix containing 25vol% of a reinforcing material consisting of 5% of silicon carbide Quiscarf and 25cm of silicon carbide particles (average particle size: 4 μm) was prepared by powder metallurgy to have a diameter of 80 mm. A sample of cylindrical composite material with a height of 60 mm was forged to a height of 50 mm by simple upsetting forging as shown in Figure 2B. A crack occurred on the free forging surface (6).However, the other one (2) of the same type of cylindrical sample was made with a wall thickness of KJIS 7075 (8) 20 as shown in Figure 1C.
When it was fitted into the metal frame (1) of the nun and upset forged according to the present invention as shown in Fig. 3B, the free forging surface (6) was not cracked even if it was forged to a height of 1 (ll) of 2.5 mm. Cracks did not occur. Cracks occurred only when the forged piece had a height of 0 mm up to 20 mm.

Example 3 A prismatic composite material (length 55 mm, width 35 mm + length 10 = 100 mm) containing 25 vol% silicon carbide whisker reinforcement in a JIS 2024 alloy matrix was produced by high pressure casting. Figure 4A) was made and forged to make its length α■ 130 mm, but cracks occurred from the vertical and horizontal free forging surfaces (6), so the above was made within the frame shown in Figure 4B. When the composite material was inserted into a JIS 5083 frame with a wall thickness (8) of 65 mm and forged according to the present invention, no cracks occurred from the free forging surface (6) even when the length reached the 130 mark.

Example 4 In a matrix of JIS 6061 alloy, 15 vol of carbon fiber with a diameter of 7 μm and an average length of 1 mm was used as a reinforcing material.
50 mark vertically and 50 horizontally by powder metallurgy method.
Figure 4 A is a composite material in the form of a rectangular prism with length αω of 100 mm and a side marked 50 mm x 100 (1
1) was forged to a size of 60 mm x 130 mm, but a crack appeared on the 50 mm x 50 mm surface (6), so a J with a wall thickness (8) of 30 mm as shown in Figure 4B was used.
When the composite material was placed in an IS 6061 frame and forged, no cracks occurred on the free forging surface (6) even when the surface Ql) was 60 mm x 130 mm.

Example 5 A cylindrical composite material with a diameter of 90+nn+ and a length of 70 mm was made by containing 25 vol % of silicon carbide particles as a reinforcing material in a matrix of 7091 alloy using a powder metallurgy method, and a square piece with a width of 60 mm and a length of 120 mm was obtained. However, a crack appeared on the side surface, so when it was forged in a JIS 2024 alloy frame with a wall thickness (3) of 45 mm in the shape shown in Figure 1C, no cracks occurred.

〔Effect of the invention〕

By restraining short fiber-reinforced aluminum-based composite material with a metal frame and forging it together with the frame, it has become possible to significantly increase the amount of forging of the composite material.

[Brief explanation of the drawing]

FIG. 1A is a perspective view of a metal frame according to the present invention, FIG. 1B is a perspective view of a prismatic composite material, and FIG. 1C is a perspective view of a cylindrical composite material fitted into a metal frame according to the present invention. Figure, 1st
The figure is a side sectional view. FIG. 2A is a side view of the composite material set in a forging tool, and FIG. 2B is a side view of the composite material being applied with forging pressure. FIG. 3A is a side view of a pressurized state when a thin metal frame is used, and FIG. 3B is a side view of a pressurized state when a thick metal frame is used. FIG. 4A is a perspective view of a composite material with a prismatic shape lying on its side, and FIG. 4B is a perspective view of a metal frame for a prismatic shape, all examples of which are shown. 1: Metal frame 2: Composite material 3: Forging tool 4: Contact tool surface 5: Metal flow 6: Free forging surface 7: Tension
8: Thickness of metal frame 9: Height and length of metal frame)
10: Height and length of composite material) 11: Surface of composite material
12: Surface of metal frame Figure 1 (A) Figure 1 C
B) Figure 1 (C) Figure 1 (D) Figure 2 (A
) Figure 2 (B) Figure 3 (A)
Figure 3 (marked Figure 4 (A) J

Claims (2)

[Claims] (1) When free forging a composite material in which short fibers are dispersed as a reinforcing material in a matrix made of aluminum or aluminum alloy, the side surface of the composite material that is not in direct contact with the forging tool is A method for forging a short fiber-reinforced composite material, the method comprising restraining it with a metal frame having high plastic workability and then forging it together with the metal frame. (2) What is a metal frame that has better plastic workability than the above composite materials?
A method for forging a short fiber reinforced composite material according to claim 1, wherein the frame is made of aluminum or an aluminum alloy.