JPH07269311A - Working method for rocker arm - Google Patents

Abstract

PURPOSE:To improve dispersion of the size of a row material and smoothness of a surface with some efficienct method. CONSTITUTION:In the work method for a rocker arm 1 which is formed in such constitution that the nearly center part of a rocker arm whose one end is formed as a support part and the other end is formed as a valve push-pressing part is separated in width direction so as to form a roller storing part, the clearance between rocker arm both side surfaces 13a for forming the roller storing part in a raw material step is manufactured in a rather narrow width, a pair of sizing blocks 6, 6 are inserted inside of both side surfaces 13a, a push fitting 7 is struck in the middle and the sizing blocks 6, 6 are push-opened so as to improve the clearance between both side surfaces and smoothness of the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a rocker arm used in a valve train of an internal combustion engine, and more particularly to a method for dimensioning a space for inserting a roller provided in a main body of the rocker arm.

[0002]

2. Description of the Related Art First, a rocker arm according to the present invention will be described with reference to FIGS. FIG. 5 shows
An example of a partial cross-sectional view of an internal combustion engine showing a configuration of a rocker arm and its vicinity described in Japanese Patent Laid-Open No. 2-199205, in which 1 is a rocker arm, 11 is a fulcrum thereof, 12 is a cam follower,
Reference numeral 14 is also a valve pressing portion, 31 is a cam, 32 is a pivot, and 33 is a valve shaft of an intake valve or an exhaust valve.

The rocker arm 1 is a valve mechanism of an internal combustion engine, that is, the rotational movement of a cam 31 which rotates in conjunction with a crankshaft, and causes the valve shaft of an intake valve or an exhaust valve of the internal combustion engine.
33 is a member that constitutes a part to be converted into reciprocating motion,
Normally, it is made of metal, and there are some structures that are slightly different depending on the design, but in the example of FIG.
A center cam follower 12 that comes into contact with the cam 31 in the middle of the fulcrum 11 at the right end that engages with the valve presser 14 at the left end that presses the valve shaft
The respective parts are provided.

FIG. 3 is a plan view showing the rocker arm 1, FIG.
Is a front view of the same thing. In this rocker arm 1, the contact between the cam follower 12 and the cam 31 is a rolling contact, and in order to prevent the wear of both, the rocker arm in the substantially central portion, which is the cam follower 12, is separated in the width direction to form a roller accommodating portion. 13 is formed, and the roller 2 is accommodated therein. Further, since two intake valves or two exhaust valves are provided, the valve pressing portion 14 is also separated at two positions in the width direction, and the planar shape is substantially U-shaped or substantially Y-shaped.

Since such a rocker arm 1 has a complicated shape, it has been conventionally manufactured by a sintering method of sintering metal powder. However, since the sintering method has good dimensional accuracy, it has a low production efficiency and significantly increases the cost. Therefore, in recent years, an efficient precision casting method or die forging method has been attempted as an alternative manufacturing method. Manufacturing methods such as precision casting and die forging are efficient, but since they are processing methods that include high-temperature processes and thermal contraction cannot be avoided, dimensional accuracy is low, and valve pressing parts that come into contact with valves are There are new problems such as variations in the spacing and the spacing of the inner surface of the roller accommodating portion to which the rollers are attached, and the rough surfaces.

In order to solve these problems, JP-A-3-
According to Japanese Patent No. 110040, a method of manufacturing a rocker arm main body is described in which a correction block is inserted into a roller accommodating portion (roller mounting hole) and pressed from the outside, and the entire rocker arm is slightly plastically deformed and corrected. There is. This will be described with reference to FIGS. 6 and 7. FIG. 6 is a front view showing this straightening work, FIG. 7 is a plan view, 1 is a rocker arm (however, here is an intermediate stage of manufacturing), 13 is a roller accommodating portion thereof,
Reference numeral 5 is a receiving fitting, 6 is a correction block, and 7 is a pushing fitting.

The rocker arm 1, which is an intermediate stage of precision casting, is placed on the metal fitting 5 so that the roller accommodating portion 13 faces the horizontal direction, and the correction block 6 is inserted into the roller accommodating portion 13. The outer surface of the roller accommodating portion 13 is pressed from above by the pressing fitting 7. Here, the distance between the upper and lower surfaces 6a, 6a of the correction block 6 in FIG. 6 is the finished dimension of the roller accommodating portion 13, and the inner side surface 13 of the roller accommodating portion 13 at the casting stage.
The space between a and 13a shall be slightly wider than this.

When the portion of the roller accommodating portion 13 is pressed from above by the pressing metal fitting 7, the outer surfaces 12a, 12a of the rocker arm 1 near the roller accommodating portion 13 are joined by the receiving metal fitting 5 and the pressing metal fitting 7 through the correction block 6 in the middle. By pushing inward and causing plastic deformation, the distance between the inner side surfaces 13a, 13a of the roller accommodating portion 13 is corrected to a predetermined accuracy, and at the same time, the smoothness of this surface is improved.

[0009]

However, this Japanese Patent Laid-Open No.
In the correction method described in Japanese Patent No. 110040, since the entire width of the rocker arm 1 is pressed from the outside of the rocker arm 1, there is a problem that a strong pressing force is required and the residual stress after deformation is large, and the roller is pressed by pressing. Inner surface 13 of the storage unit 13
There is also a problem that it is difficult to remove the a and 13a from the correction block 6 after pressing because they are in close contact with each other.

An object of the present invention is to provide a method for processing a rocker arm that solves these problems and is excellent in productivity, dimensional accuracy and surface smoothness.

[0011]

According to the present invention, a cam is formed by separating a substantially central portion of a rocker arm, which is a fulcrum portion having one end serving as a swinging fulcrum and the other end serving as a valve pressing portion for pressing a valve shaft, in a width direction. A method for processing a rocker arm, which comprises forming a roller accommodating portion for accommodating a roller that comes into contact with a roller, wherein a space between both inner side surfaces of the rocker arm forming the roller accommodating portion is slightly narrower than a finished dimension at a material stage. In advance, two straightening blocks are inserted on the inner side of both inner surfaces of the rocker arm, and a pressing member is driven in the middle of the two straightening blocks to push the two straightening blocks open to open the rocker arm. This is a method of processing a rocker arm, characterized in that the space between both inner surfaces is corrected to a finished size.

[0012]

[Operation] In the present invention, since the inner side surface distance is corrected in the direction in which the roller accommodating portion 13 is pushed and expanded from the inside, the surface that requires dimensional accuracy is directly corrected. Instead, the inside of the roller accommodating portion 13 may be locally deformed, so a small pressing force is required.
Since the correction block 6 and the pressing metal fitting 7 used for pressing are also wedge-shaped and divided, they can be easily removed after pressing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view showing this embodiment, and FIG. 2 is AA of FIG.
In the sectional view taken along the arrow, as in FIGS. 6 and 7, 1 is a rocker arm (also an intermediate stage of manufacturing here), 13a is an inner surface of a roller accommodating portion provided at the substantially central portion, 4 is a pressing block, 5 Is a receiving fitting, 6 is a correction block, and 7 is a pushing fitting.

The rocker arm 1, which is a precision-cast material (intermediate stage of manufacturing), is mounted on the inner surfaces 13a, 13a of the roller accommodating portion.
Place it on the bracket 5 so that a is vertical, and
Hold down a and 12a and fix them with blocks 4 and 4. Outer side 12
If you need to control the finishing intervals of a and 12a,
The distance between the pressing blocks 4 and 4 may be set to this distance.

Then, two (one pair) straightening blocks 6, 6 are inserted into the roller accommodating portion 13. Correction block 6
Is a vertical surface on the side facing the inner surface 13a of the roller accommodating portion 13, that is, on the outer side, but on the inner side is a sloped surface that is open upwards. Grooves are formed. Into this groove-shaped portion, a push-fitting member 7 having a V-shaped cross section whose both surfaces have a slope corresponding to this groove is inserted, and an arrow a
When pressed like this, a pair of straightening blocks 6, 6
Is pushed open in the direction of arrow b, and the inner surface of the roller housing 13 is
At the same time that 13a and 13a are pushed outward, the smoothness of this surface is improved.

After the pressing is completed, the pair of straightening blocks 6, 6 can be easily taken out from the roller accommodating portion 13 by pulling up the pressing fitting 7. The means for pressing the push fitting 7 is not particularly limited, but a hydraulic press, a die forging machine, or the like is preferable. As is clear from the above description, in the manufacturing method of the present invention, the distance between the inner side surfaces 13a 1 and 13a 2 of the rocker arm 1 of the roller accommodating portion 13 is slightly smaller than the desired finished size in the casting stage of the material.
For example, in the case of a rocker arm in which the distance between the inner side surfaces 13a, 13a is about 20 mm, casting is performed so that it is narrower by 0.2 to 0.5 mm.

When the pressing metal fitting 7 is pressed and the roller accommodating portion 13 is expanded, it is important to control the finished size. For example, one of the following methods may be used. 1) The relationship between the expansion allowance and the pressing force is obtained in advance by experiments, and the pressing force of the pressing member 7 or the pressing pressure is controlled to a predetermined value to perform the pressing. 2) A step portion 6a in the horizontal direction is provided at the lower end of the sloping surface of the straightening block 6, and the stroke is restricted so that the lower end portion 7a of the pressing metal fitting 7 hits against this and the pressing metal fitting 7 does not fall below a certain position corresponding to the finished size. To do.

[0018]

EFFECTS OF THE INVENTION According to the present invention, it is possible to improve the dimensional variation of materials and the smoothness of the surface by an efficient means, and to manufacture a rocker arm of excellent quality at a low cost. Play.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a plan view showing a rocker arm according to the present invention.

FIG. 4 is a front view showing a rocker arm according to the present invention.

FIG. 5 is a vertical cross-sectional view showing a part of the internal combustion engine near the rocker arm according to the present invention.

FIG. 6 is a front view showing a conventional technique.

FIG. 7 is a plan view showing a conventional technique.

[Explanation of symbols]

 1 Rocker arm 2 Roller 4 Holding block 5 Receiving metal fitting 6 Correcting block 7 Pushing metal fitting 11 Support point 12 Cam driven part 12a Outer side surface 13 Roller accommodating part 13a Inner side surface 14 Valve pressing part 31 Cam 32 Pivot 33 Valve shaft

Claims (1)

[Claims] 1. A roller for accommodating a roller, which has a fulcrum portion having one end serving as a swing fulcrum and the other end having a substantially central portion of a rocker arm, which is a valve pressing portion for pressing a valve shaft, separated in the width direction and contacting a cam. A method of processing a rocker arm having a storage part formed therein, in which a gap between both inner side surfaces of the rocker arm that forms the roller storage part is manufactured to be slightly smaller than a finished size at a material stage, and both of the rocker arms are formed. Insert two straightening blocks on the inside of the inner surface, press a metal fitting in the middle of the two straightening blocks, and push the two straightening blocks open to finish the space between both inner surfaces of the rocker arm. A rocker arm processing method characterized by straightening to