JPS60209608A - Manufacture of rocker arm - Google Patents

Abstract

PURPOSE:To obtain the cam follower surface requiring no abrasive processing and the like after sintering by a method wherein the cam follower surface of a rocker arm tip is formed by direct pressing of ceramic powder by a punch surface. CONSTITUTION:In a punch 4 having a punch surface 4a of which surface roughness is finished less than 1.5S, a ceramic powder is pressed in crossing direction for a cam follower surface 7a, then a rocker arm tip 7 is formed by sintering, the chip 7 is fixed to a light alloy rocker arm by casting. The punch surface forms directly the cam follower surface, consequently, the follower surface can be formed under surface roughness condition correspond to the punch surface, accordingly, the follower surface having an excellent surface roughness can be obtained by sintering without requiring abrasive processing and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a rocker arm tip in which the cam sliding surface is made of Reramix and the arm body is made of a light alloy such as an aluminum alloy.

The above-mentioned type of rocker arm tip generally includes a pre-formed ceramic tip in a mold, and a molten light alloy is poured into the mold to integrate the tip and the arch body to form the rocker arm. However, after this, the boss hole of the rocker arm and the rocker shaft fitting hole are machined, and after that, the cam follower surface of the chip is machined (polished) using these machined parts as a reference.

By the way, the machining allowance for the cam 7407 surface of the above-mentioned chip is usually about 0.2 mm to 0.5 mm, but lamic chips generally have poor workability, and if the machining allowance is applied to the above-mentioned machining allowance, There has been a problem in that the chips tend to chip, break, crack, etc. In addition, in recent years, after the cam follower surface of the chip has been polished and ground,
It has also been attempted to integrate it with the arm body, but in this case as well, problems such as cracks are unavoidable as in the above case. Note that if the cam follower surface of the tip has a rough finish, the problem of wear will occur on the cam with which the tip comes into contact.

In addition, as shown in Fig. 1, ceramic powder is placed in a mold Δ in which a mushroom-shaped molding hole a is formed, and compressed in the direction of the arrow in Fig. 1 by a bunch (not shown). It is formed by machining.The cam follower surface of the chip is formed by the curved surface of the bulk part of the mushroom-shaped molding hole a of C1 in b.However, the cam follower surface of the chip is formed by When molding is carried out, dents are created mainly in the middle heat zone after sintering due to the difference in compactness between the top, middle heat zone, and bottom of the chip along the pressurizing direction. The cap that ends up on the cam floor surface of the chip (
), the deformation becomes large (the shrinkage rate of Reramix reaches over 10%), and it cannot be used as is, so it is necessary to process it after forming the chip. J: Problems such as sea urchin cracking could not be avoided.

Furthermore, when molding is performed using the above mold, J:
There is a problem in that the ceramic powder rubs against the curved surface of the bulk portion of the molding hole a, causing wear of the curved surface, thereby reducing the surface roughness of the cam follower surface of the chip.

The present invention was made in view of the above circumstances, and the cam 74
The rocker arm chip was formed by compression molding in the direction crossing one surface, and the cam 7407 with a good surface texture was formed by putting the horn J tour tip into a mold with molten light alloy and 5. It is an object of the present invention to provide a method for manufacturing a rocker arm, which makes it possible to obtain a rocker arm having a tip with a surface.

The present invention will be explained below based on the drawings.

[Prior to forming one arm, first, a one-piece arm tip ≠ base piece γ is manufactured by molding as shown in FIG. The above-mentioned molding 418 is inserted into a molding hole 3a having a planar rectangular shape that is formed by vertically penetrating the mold 3 installed on the base 12, the central part of this mold 3, and the base 2 below. It includes an upper bunch 4, a lower outer punch 5, and a lower inner bunch 6.

The upper bunch 4 has a prismatic shape that is inserted into the molding hole 3a of the mold 3 from above.The lower end surface of the upper bunch 4 is a concave bunch surface 4a, and the surface roughness of the bamboo 4a is 1°5S.
It is completed below. The lower outer bunch 5 is a rectangular cylindrical member that is pushed into the molding hole 3a of the mold 3 from below, and the mill inner bunch 6 is inserted into the lower outer bunch 5. Then, insert the lower outer bunch 5 with the lower inner bunch 6 into the molding hole 3a of the mold 3 from below, pour a predetermined amount of ceramic powder from the soil into the molding hole 3a, and then) insert the upper punch 4 into the molding hole 3a. The ceramic powder is put into the molding hole 3a and compressed and formed using the upper punch 4, the C core outer bunch 5, the lower inner bunch 6, etc. as shown in FIG. A rocker arm tip base piece 7' having a mushroom-shaped side surface is manufactured. This rocker arm chip base piece 7
' is taken out from the mold 3 and sintered to form the cam 7 shown in FIG.
4) Turn the face 7a'' to the right []] to obtain the thick sintered piece 7. By the way, the punch face 4 of the upper punch 1
Since the angle of 111 degrees (plane a) was set to 1.5S or less, the surface roughness of the lower surface 7a of the lower surface 7a of the rod base piece 7' can be set to a value corresponding to the surface roughness of the punch surface/la. On the monkey soil,
By sintering, the surface roughness of the cam follower surface 78'' of the rocker arm depth sintered piece 7'' can be reduced to 0.8S or less.

Although the punch surface /la of the upper pan 7-4 directly forms the cam follower surface 7a-, the friction generated between the punch surface /I#1 and the ceramic powder due to pressure is almost eliminated, and the punch surface 4a has very little wear, so the cam 7707 surface 7a' with good surface roughness is (
can do. d3, in this respect, in the conventional method, the cam 7707 surface of the rocker arm tip is along the pressing direction, and the cam 770 is formed on the peripheral wall of the molding hole a of the conventional mold S.
Seven surfaces are formed, and the peripheral wall of the forming hole wears out each time pressure is applied, making it impossible to improve the surface roughness of the cam follower surface. Furthermore, since the 7J Muff A lower surface with good surface roughness can be obtained after sintering as described above, it is no longer necessary to perform processing such as Iζ polishing, which was previously required. Therefore, there is no possibility of cracks or cracks occurring on the surface of the cam 7707. In addition, dents, deformations, etc. in the two-utral zone portion caused by density differences in the green compact hardly appear on the surface of the cam 7107.

In addition, the rocker arm chip base piece 7- is the cam 7107 surface 7.
A'' side is pressurized with one punch and the opposite side is pressurized with two punches. Since the central part of - and the mounting part 7B' are respectively pressurized by the lower inner bunch 6 and the upper punch 4, the rocker arm chip base piece 7 is compressed at different compression ratios at the central part and the peripheral part of the umbrella part 7A''. ′ by molding. For this reason,
The curvature of the cam follower surface 7a' is formed to be different between the central part and the peripheral part of the cam follower, thereby making the central part of the lower surface 7a' different from the curvature of the cam follower surface 7a. 8 curvature゛1
By forming a curved surface with a radius of curvature to the right, and by forming the white end side around surface 7a- into a curved surface with a small radius of curvature, the sliding characteristic with the cam is This makes it possible to obtain an advantageous cam follower surface.

Then, after sintering, the mounting portion 7B'° of the sintered piece 7'' of the rocker arm chip is processed to obtain the rocker arm chip 7 having the cam follower surface 7a angled portion 7Δ and the mounting portion 7B as shown in FIG. .

Next, this rocker arm body 17 is attached to a rocker arm shaping mold, and a molten metal of a light alloy such as an aluminum alloy is poured into this mold to integrate the arm body 8 with the rocker arm boot tab 7. After that, the boss hole 9 and the azirest screw screw hole 10 are formed in the rocker arm.
A rocker arm R as shown in FIG. 5 is obtained as a product.

In the above way? ! 16 types of rocker arms including
0oCC,, OHC gasoline] We conducted a wear test by incorporating it into a carrot and operating it continuously for 200 hours at an oil type of 5W-20, a rotation speed of 200 rpm, and an oil temperature of 95°C. Examined. Nad
), rocker arm chips were manufactured using a conventional method such as B'-3IALON, Zr2O3, etc. for comparison, while the rocker arm chips were manufactured using a conventional method without using the method of the present invention, and a cam follower was manufactured by polishing. Each test chip with a finished surface was also manufactured, a rocker arm was formed around each chip, and the above wear test was conducted. The results are shown in Table 1.

From Table 551, it is clear that the rocker arm manufactured using the method of the present invention has a lower wear surface than the conventional rocker arm J3, rocker arm tip J3, and cam wear. It can be seen that no cracks occur.

In the present invention described above, a rocker arm chip is formed by compression molding Relamic powder in a direction crossing the cam 7407 surface using a punch that also has a bamboo surface with a surface roughness of 1.5S or less. This rocker arm chip is formed by placing it in a mold together with a light alloy molten metal such as aluminum alloy, and the cam follower of the rocker arm chip is formed by directly pressing the hiramic powder. The surface of the cam 7407 can be made to have a surface roughness suitable for punching, and by rough sintering, it is possible to obtain a lower surface with good surface roughness that does not require polishing. . Also, since there is no need for polishing, etc.
Forces that could not be avoided with conventional methods l) The separation of cracks, etc. on the 7701 surface is eliminated. In other words, according to the present invention, it is possible to obtain a rocker arm having a lower surface that is free from defects such as cracks and has excellent wear characteristics against any friction of the cam.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a mold used in an example of a conventional rocker arm chip manufacturing method, FIG. 2 is a sectional view of a mold used in an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a mold used in an embodiment of the present invention. A perspective view of a rocker arm chip sintered piece manufactured by carrying out an example of
FIG. 4 is a perspective view of a rocker arm depth produced by processing the sintered rocker arm chip shown in FIG. . 4...Upper punch 4a...Punch 7...Rocker arm tip 7a...
...Cam follower R...Rocker arm Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] This is an IN method for a rocker arm equipped with a rocker arm tip that moves the cam follower surface that contacts the cam to the right, and the roughness of one surface is reduced to 1.5S or less. A method for manufacturing a rocker arm chip characterized by forming a J-horn J-arm chip by compression molding in the cross-overlapping direction and placing the rocker arm chip in a mold together with a molten metal of a light alloy such as an aluminum alloy. .