JPH02241659A - Manufacture of article - Google Patents

Abstract

PURPOSE:To prevent cracking at boundary zone by beforehand forming a preforming member with reinforcing material, forming ruggedness at position corresponding to the boundary in the preforming member with a base member, impregnating molten base material onto the preforming member and forming the composite of the base material and the reinforcing material. CONSTITUTION:A columnar member (preforming member) 20 having surface shape of top part of a piston 10 is formed and further, plural annular grooves (ruggedness) 21a, 21b... having the same depth are machined on the concentric circle with the same pitch on one end face 21 of this columnar member 20. Successively, the columnar member 20 is preheated and charged to a mold 40, and Al alloy is poured in the mold 40. After forming the composite of the Al alloy and the material constituting the columnar member 20, this is solidified and the piston 10 integrally formed with the base member 11 and the composite member 12 composed of the composite material is manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method in which a base member made of a base material such as metal or plastic, and a composite member made of a composite material of this base material and a reinforcing material are integrally molded. The present invention relates to a method for manufacturing an article.

[Conventional technology]

BACKGROUND ART Nowadays, some articles that require special mechanical properties in some parts have composite members made of composite materials such as F, R, M <an reinforcing metal).

For example, aluminum alloy pistons used in the engines of automobiles and motorcycles have composite 41-fiber reinforcements such as SiC whiskers on the top surface layer, which improves wear resistance and heat resistance. is planned.

[Problem to be solved by the invention]

By the way, as mentioned above, articles containing composite materials need to be subjected to heat treatment for solution treatment or the like.

On the other hand, the two materials that make up the piston are:
A base material made of only an aluminum alloy and a composite material made of this aluminum alloy and SiC whiskers have different coefficients of thermal expansion.

Therefore, when the above-mentioned piston is subjected to heat treatment such as rapid cooling after heating, thermal stress is generated in the boundary area between the base member made of the above-mentioned base material and the composite member made of the composite material due to the difference in coefficient of thermal expansion. There is a risk that this will occur and cause a rift between them.

In view of the above-mentioned circumstances, an object of the present invention is to provide a method for manufacturing an article that can prevent the occurrence of cracks in the boundary area between a base member and a composite member even when heat treatment such as solution treatment is performed. It is about providing.

[Means to solve the problem]

In the method of manufacturing an article according to the present invention, a base member made of a base material and a composite member made of a composite material of the base material and a reinforcing material are integrally molded. The base material and the reinforcing material are formed by molding a preformed member, forming irregularities in a portion of the preformed member corresponding to the boundary with the base member, and adding a molten base material to the preformed member. I am trying to combine these.

[Function] According to the above configuration, the thermal stress generated in the boundary area between the base member and the composite member due to the difference in coefficient of thermal expansion can be alleviated by the unevenness formed on the preformed member.

[Example] Hereinafter, the present invention will be described in detail based on drawings showing examples.

FIG. 1 conceptually shows an article molded by the manufacturing method according to the present invention, and illustrates a piston 10 employed in a two-stroke engine for an automobile or a motorcycle.

This piston 10 has a base member 11 made of an aluminum alloy (base material) such as AC8A, and a composite of the aluminum alloy and SiC whiskers (reinforcing material) on the top surface layer of the base member 11 for the purpose of improving wear resistance, heat resistance, etc. The composite member 12 is manufactured by the following procedure.

First, as shown in FIG. 2, a cylindrical member (preformed member) 20 having approximately the same diameter as the top surface shape of the piston 10, that is, the piston 1o, is formed using NSiC whiskers. A plurality of annular grooves (irregularities) 2 having the same depth are formed on one end surface 21 of the member 20.
1a, 21b.

20c, 20d... with the same pitch, for example, if the diameter of the cylindrical member 20 is 60rI11, the depth is 1#
Concentrically cut the grooves at a pitch of 1.5M.

At this time, as shown in the figure, the above-mentioned cutting process can be easily performed by using a machining machine equipped with a tool 31 having a sawtooth blade at the tip of a rotary shaft 30.

Next, the cylindrical member 20 is preheated to 700° C. and placed in a mold 40 as shown in FIG. 3(a).

At this time, the cylindrical member 20 is arranged so that its uncut surface 22 corresponds to the top surface of the piston 10.

From this state, as shown in FIG. 3(b), the mold 4
When aluminum alloy is poured into the cylindrical member 2 at 700°C and 500 atm, the aluminum alloy and the cylindrical member 2
A piston 10 is produced in which a base member 11 made of an aluminum alloy and a composite member 12 made of a composite material of an aluminum alloy and SiC whiskers are integrally molded. .

As is clear from FIG. 1, the joint A between the base member 11 and the composite member 12 is an annular groove 20b, 20C formed in the columnar member 20.

20d... has a sawtooth shape.

This piston 10 is subjected to heat treatment such as solution treatment, for example, heating at 510° C. for 4 hours, followed by rapid cooling.
When heating is performed at 70° C. for 10 hours, heat is generated in the boundary area between the base member 11 and the composite member 12 due to the difference in thermal expansion coefficient of the aluminum alloy and that of the composite material of this aluminum alloy and SiC whiskers. Stress occurs.

However, in the piston 10 manufactured by the above method, since the joint between the base member 11 and the composite member 12 is configured in a sawtooth shape, the horizontal direction (radial direction of the piston 10) component of this thermal stress is is gradually reduced, and cracks are prevented from forming in the boundary area between the two members 11 and 12.

In the above embodiment, the piston 10 employed in an engine is exemplified, but the present invention can of course be applied to other articles. Further, in this article, a base member 11 made of an aluminum alloy and a composite member 12 made of a composite material of an aluminum alloy and SiC whiskers are integrally molded, but the present invention is not limited to these combinations.

Furthermore, in the above embodiment, the plurality of annular grooves 21a, 21b
, 21c, 21d, etc., the unevenness is formed by cutting, but the unevenness does not necessarily have to be formed by grooves, nor does it need to be formed by cutting.

〔Effect of the invention〕

As described above, according to the method for manufacturing an article according to the present invention, the thermal stress generated in the boundary area between the base member and the composite member due to the difference in coefficient of thermal expansion can be alleviated by the unevenness formed on the preformed member. Therefore, even when heat treatment such as solution treatment is performed, cracks can be prevented from occurring in the boundary area.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional perspective view conceptually showing an article manufactured by the method according to the present invention, FIG. 2 and FIG. 3(a).
, (b) sequentially show the steps of manufacturing an article by the method according to the present invention, and FIG. 2 is a conceptual perspective view;
Figure 3(a). (b) is a conceptual cross-sectional view. DESCRIPTION OF SYMBOLS 10... Article, 11... Base member, 12... Composite member, 20... Preformed member, 21a, 21b, 21c, 21d-... Irregularities. (a) (b) Figure 2 Figure 3

Claims (1)

[Claims] A method for manufacturing an article in which a base member made of a base material and a composite member made of a composite material of the base material and a reinforcing material are integrally molded, comprising forming a preformed member in advance with the reinforcing material, and The base material and the reinforcing material are composited by forming irregularities in a portion of the preformed member corresponding to the boundary with the base member and adding a molten base material to the preformed member. A method of manufacturing an article characterized by: