JPS6310043A - Manufacture of piston for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the cooling effect and to reduce the weight increase onto a piston main body by fixing a salt core by a fixing member, setting the outer peripheral part to a die and cutting the outerperipheral part after casting. CONSTITUTION:A gallery part 14 is formed by fixing an annular shaped salt core 20 by a fixing member 21 and casting it. The salt core 20 is fixed by fitting it by a snap fit to the claw part 24 of a fixed leg 23. The outer peripheral part 22 of the fixing member 21 if for die setting and after casting is cut upto the position same as the outer diameter 25 of the piston shown by a two dot chain line. The salt core 20 fitted to the fixing member 21 is cast to the piston main body and after casting an oil hole is pierced and the gallery part 14 is formed by melting the salt core 20 and pouring a water into this oil hole, and the outer peripheral part 22 of the fixing member 21 is further cut. The piston on which the gallery part is formed cools the peripheral side of a top ring groove 13 directly and improves the cooling effect.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a piston for an internal combustion engine, and particularly to a method for manufacturing a piston in which a gear rally portion is formed using a salt core. used for.

(Prior art) As a prior art related to the present invention, there is
There is one described in Publication No. 46.

This conventional technology requires a cooling cavity and a ring trager in advance.
This part is cast into the piston body when the piston body is cast.

(Problems to be Solved by the Invention) The piston of the above-mentioned prior art has a gear rally made of cast iron, which has poor heat conduction, and requires a thick wall to form the gear rally plate, so it is the same as an aluminum cavity. If an attempt is made to provide this cooling effect, the gear rally section becomes larger, the cast iron section also becomes larger, and the piston itself becomes heavier.

In view of the above problems, the technical object of the present invention is to manufacture a piston that directly cools the cooling part without using a cooling member with poor heat conduction and does not increase the weight.

[Structure of the invention]

(Means to solve the problem) The technical measures taken to solve the above technical problem are:
In a method for manufacturing a piston in which a gear rally portion is formed by a salt core, the fixing member for fixing the salt core has an outer circumferential portion and a plurality of fixing legs extending inside the outer circumferential portion, and The salt core is attached and fixed by a member, and the outer peripheral part is set in a mold and cast, and then the outer peripheral part of the fixing member is cut.

(Function) As described above, the cooling effect is improved by directly cooling the parts that require cooling without going through the gear rally member, which has poor heat conduction.Also, after casting, the outer periphery of the fixed member is removed by cutting. , it is possible to reduce the weight increase on the piston body.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The piston 10 shown in FIG. 1 has a top land 12, a top ring groove 13, and a gear rally portion 14 formed around the top ring groove 13 on the top portion 11.

The gear rally portion 14 includes an annular salt core 20 shown in FIG.
It is formed by fixing to the fixing member 21 and casting.

The fixing member 21 is made of an aluminized iron plate, and as shown in FIGS. 1 and 2, it has a circular outer peripheral part 22 and an elongated member inside the outer peripheral part 22 with the tip bent into an 8-shaped strip. A plurality of fixed legs 23 having claw portions 24 are integrally formed. The salt core 20 is attached to the claw portion 24 of this fixed foot 23.
It is fixed by attaching it with a snap fit. In addition, the outer peripheral part 22 of the fixing member 21 is for mold setting, and after casting, the outer diameter 22 of the piston shown by the two-dot chain line is
Since it is removed by cutting to the same position as 5, it is deleted in the product state.

The salt core 20 attached to the fixing member 21 is cast into the piston body.

After casting, the salt core 20 has oil holes 15.1 as shown in FIG.
6 is drilled, and after drilling, water is injected into the oil holes 15 and 16 to melt the salt core 20 to form the gear rally portion 14, and the outer periphery of the fixing member 21 is The portion 22 is removed by cutting.

〔Effect of the invention〕

The piston in which the gear rally portion is formed by the above method can directly cool the area around the top ring groove 13 that requires cooling without going through the gear rally member with poor heat conduction, so cooling efficiency is improved. During casting, the outer periphery of the fixing member that fixes the salt core is cut after casting and removed in the finished product, so there is little effect on weight increase.

Furthermore, since thermal expansion is reduced due to improved cooling efficiency, it is possible to eliminate the conventionally provided struts for suppressing thermal expansion, resulting in weight reduction and cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a piston according to an embodiment of the present invention;
FIG. 2 is a plan view of a fixing member to which a salt core is fixed, and FIG. 3 is a bottom view of a piston according to an embodiment of the present invention. 10... Piston, 14... Gear rally section.

Claims (1)

[Claims] The salt core is attached to a fixing member and set in a mold, and after casting,
In a method for manufacturing a piston in which a gear rally portion is formed by injecting water and melting a salt core, the fixing member includes an outer circumferential portion and a plurality of fixed legs extending inside the outer circumferential portion. A method for producing a piston for an internal combustion engine, comprising: forming a salt core, fixing the salt core using the fixing member, setting the outer peripheral part in a mold, and cutting the outer peripheral part of the fixing member after casting.