JPH06246387A - Production of valve lifter made of aluminum - Google Patents

Abstract

PURPOSE:To improve the strength of a shim wall by forming a recessed part on an outside end part of a cower surface part of a lifter body after forming a skirt part of the lifter in a cylindrical shape having the cover surface part by a cold forging. CONSTITUTION:A skirt part 1b of a lifter main body 1 is formed by a cold forging. At this time, a material flows from an end surface part of the lifter main body 1 toward the skirt part 1b, and a flow 1d is made almost parallel to an axial line of the lifter main body 1. Next, a cover surface part 1a is formed by recessing the end surface part 1c of the lifter main body 1 by a cold forging. A shim wall 1e is formed in this forming, though, at this time, a flow in a diametral direction is generated in an inner circumferential part of the shim wall 1e, because the quantity of the flow is little, the flow 1d almost parallel to the axial line is maintained. Further, the shim wall 1e is finished and the final shape is obtained. Therefor, even if the shim wall 1e is applied with a load from a direction orthogonal to the axial line of the lifter main body 1 during using the valve lifter, a breakage is not generated on the shim wall 1e, and the strength of the shim wall is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum alloy valve lifter for use in an automobile engine or the like.

[0002]

2. Description of the Related Art Conventionally, an engine mounted on an automobile or the like often uses an aluminum alloy valve lifter instead of a valve lifter which is an iron-based forged product for the purpose of speeding up and improving fuel efficiency.

However, the aluminum alloy valve lifter has a drawback that it has a low wear resistance, such that the sliding portion between the valve cam and the valve rod is easily worn as compared with the iron-based forged lifter.

Therefore, in the past, for example, Japanese Patent Laid-Open No. 1-31 has been used.
As in the technique disclosed in Japanese Patent No. 5607, a lifter body is formed by cold forging an aluminum alloy,
There has been proposed a valve lifter in which a wear-resistant shim or tip is provided on a sliding contact portion with a valve cam or a valve rod, and wear-resistant iron-based metal is sprayed on an outer peripheral surface of a lifter body.

Further, in the valve lifter of the above publication, the cold forging step is regarded as one step, and in consideration of the material yield and the processing cost, as shown in (a) and (b) of FIG. Cold forging is performed on b and the crown portion c at the same time.

[0006]

However, when the skirt portion b and the crown surface portion c of the valve body a are cold forged at the same time as in the above-mentioned conventional valve lifter, the crown surface portion c side is formed first due to the difference in workability. After that, the material on the side of the crown surface c flows to the side of the skirt portion b as the skirt portion b is deformed.
The flow (grain flow line) e of the shim wall d has a large inclination in the radial direction (inclination angle θ ₁ ) as shown in FIG. For this reason, when the load F acts on the shim wall d, the shim wall d may be damaged along the flow e as shown in (b) of FIG.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a method for manufacturing an aluminum alloy valve lifter that does not reduce the strength of the shim wall.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises forming a skirt portion of a lifter body made of an aluminum alloy by cold forging into a tubular shape having a crown surface portion, and then forming a crown surface portion of the lifter body. It is characterized in that a concave portion is formed by cold forging at the outer end portion of.

[0009]

By the above method, the material flows from the end face portion of the lifter body toward the skirt portion, and the flow becomes substantially parallel to the axis of the lifter body. Next, the crown surface portion is formed by recessing the end surface portion of the lifter body, and the outline of the shim wall is formed by the molding of the crown surface portion. A flow is generated, but the amount thereof is small, so that the flow substantially parallel to the axis is maintained.

As described above, since the flow that is substantially parallel to the axis of the lifter body is formed in the shim wall around the crown surface,
Even if a load acts on the shim wall in a direction perpendicular to the axis, the shim wall is not damaged, and the strength of the shim wall can be significantly improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings shown in FIGS.

FIG. 1 is a configuration diagram showing a usage state of a valve lifter, 1 is a lifter body, 2 is a valve cam, 3 is a valve rod,
Reference numeral 4 denotes a shim made of a wear-resistant metal provided on the upper surface of the crown portion 1a of the lifter body 1, 5 denotes a tip provided on the lower surface of the crown portion 1a, and the shim 4 is a valve cam 2 and a tip. 5 is adapted to abut on the valve rod 3, respectively.

The lifter body 1 is cold forged and molded from aluminum alloy as follows. First, in the first step of cold forging, as shown in FIG.
The skirt portion 1b is molded. At this time, the material flows from the end surface portion 1c of the lifter body 1 toward the skirt portion 1b, but the flow 1d is substantially parallel to the axis of the lifter body 1.

Next, in the second step of cold forging, as shown in FIG. 2B, the end surface portion 1c of the lifter body 1 is recessed to form the crown surface portion 1a.

By forming the crown surface portion 1a, the outline of the shim wall 1e is formed. At this time, a radial flow is generated in the inner peripheral portion of the shim wall 1e, but since the amount is small, it is almost parallel to the axis line. Flow 1d is maintained.

Thereafter, as shown in FIG. 2C, the shim wall 1
Although the final shape is obtained by finishing e, as described above, the skirt portion 1b of the lifter body 1 is first formed by cold forging, and then the crown surface portion 1a is formed by cold forging. In the flow 1d of the wall 1e, the angle θ ₂ directed in the radial direction becomes small as shown in FIG.
Since it is substantially parallel to the axis line of No. 1, even if the load F acts from the direction perpendicular to the axis line during use, the shim wall 1e is not damaged and high strength can be obtained.

Further, as a method for keeping the flow 1d of the shim wall 1e parallel to the axis of the lifter body 1, FIG.
In the state of (a), that is, in the state where the skirt portion 1b of the lifter body 1 is formed in the first step of cold forging, the method for completing the cold forging step and the bottom in the state of (a) in FIG. A conceivable method is to add a large allowance to the thickness t. However, when these methods are adopted, the cold forging step is only one step, but there is a problem that the material yield is remarkably reduced and the post-processing cost is increased.

[0018]

As described in detail above, according to the method of the present invention, first, the skirt portion of the lifter main body made of an aluminum alloy is cold-forged to be formed into a tubular shape having a crown surface portion. The material flows from the end face toward the skirt, the flow becomes almost parallel to the axis of the lifter body, and then a recess is formed by cold forging at the outer end of the crown face of the lifter body to form a shim wall. In this case, a radial flow of material is generated in the inner peripheral portion of the shim wall, but the amount thereof is small, so that the flow substantially parallel to the axis is maintained.

By forming a flow in the shim wall substantially parallel to the axis of the lifter body, a load is applied to the shim wall from a direction perpendicular to the axis of the lifter body during use of the valve lifter. Even if the shim wall is not damaged, the strength of the shim wall can be significantly improved, and the material yield can be improved because it is not necessary to increase the thickness of the crown surface in advance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a usage state of a valve lifter according to an embodiment of the present invention.

2A to 2C are process diagrams showing a method of manufacturing a valve lifter according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a flow of the crown surface portion of the valve lifter manufactured by the method of manufacturing the valve lifter according to the embodiment of the present invention.

4A and 4B are explanatory views showing a valve lifter manufactured by a conventional manufacturing method.

5A and 5B are explanatory diagrams showing a flow of a valve lifter manufactured by a conventional manufacturing method.

[Explanation of symbols]

 1 Lifter body 1a Crown surface 1b Skirt portion 1d Flow 1e Shim wall

Claims (1)

[Claims] 1. A lifter main body made of an aluminum alloy is cold-forged into a tubular shape having a crown surface, and then a recess is formed by cold forging at an outer end of the crown surface of the lifter main body. A method for manufacturing an aluminum alloy valve lifter, comprising: