JPS5936085B2 - Manufacturing method of valve rocker arm for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a valve head mechanical arm for an internal combustion engine, which has excellent wear resistance and productivity, and is lightweight.

As is well known, the valve rocker arm for internal combustion engines, which converts the rotational motion of the camshaft into reciprocating motion and opens and closes the engine valves, has a high degree of wear resistance and toughness on the part that contacts the cam of the camshaft, that is, the pad surface. Although various measures have been taken in the past to meet this demand, nothing satisfactory has yet been achieved.

Measures to reduce wear on the pad surface of valve rocker arms for internal combustion engines have been considered, such as applying wear-resistant materials and reducing valve spring loads. Rocker arms joined by overlaying, brazing of chilled cast pieces, etc. have been put into practical use.

The latter can be achieved by reducing the weight of the rocker arm, which can be achieved in part by downsizing the rocker arm and changing the material, for example from a steel forging to an aluminum alloy. ing. Although the weight reduction effect of using aluminum alloy for valve rocker arms is large and will likely increase in the future, such aluminum alloy rocker arms have the disadvantage of providing sufficient wear resistance to the rocker pad surface. ing. Current aluminum alloy rocker arms in Europe have cast iron chips cast in aluminum alloy on the rocker pad surface, but these do not have sufficient wear resistance. Conventionally, chrome plating, self-fusing alloys, or heat-treated steel found in general iron rocker arms cannot be used for the pad surface of aluminum alloy rocker arms.

That is, in the case of chrome plating, the plating layer thickness is as thin as around 50 microns, making it impossible to obtain sufficient durability and reliability, and in the case of self-fluxing alloys, the melting point of the aluminum alloy is 1000 to 1100, which is higher than the melting point of aluminum alloy after thermal spraying. ℃, and there was a risk that the casting temperature of heat-treated steel would be much higher than the melting point of the aluminum alloy, making both methods impractical. In view of the above-mentioned drawbacks of conventional valve rocker arms for internal combustion engines, particularly aluminum alloy rocker arms, the present invention aims to manufacture an improved valve rocker arm for internal combustion engines having a pad portion with sufficient wear resistance. The purpose is to provide law.

According to the present invention, this purpose is to form a wear-resistant coating layer by spraying a self-fusing alloy on the outer peripheral surface of a metal cylindrical body while rotating it around its central axis; Fusing the coating layer, then cutting the cylindrical body into pieces having a predetermined width in the axial direction and a predetermined length in the circumferential direction to obtain a curved metal piece element, and converting the metal piece element into the curved shape. This is achieved by a method of manufacturing a valve rocker arm for an internal combustion engine, which is characterized in that the valve rocker arm is joined to the pad portion of the rocker arm main body at the concave side of the curved shape while maintaining the shape.

According to the manufacturing method of the Valprotska arm according to the present invention, the surface of the pad portion is formed into a wear-resistant coating layer by joining the metal piece elements, and the joining is performed by joining the metal piece elements to steel, alloy steel, steel, alloy steel, etc.
If it is made of cast iron or cast steel, this can be achieved by casting, brazing, or welding the metal and the rocker arm body at a relatively low temperature, and therefore, one side may be chrome plated, overlaid with self-fusing alloy, or By joining a metal piece element with a wear-resistant coating layer to the rocker arm body by brazing a chill cast piece, etc., the rocker arm body can be made with a low melting point and light self-weight while providing sufficient wear resistance to the pad part. It is possible to provide a rocker arm that is made of a light alloy such as aluminum or an alloy thereof, and is lightweight and wear-resistant.

Moreover, according to this manufacturing method, problems such as the yield of the overlay material layer, the workability of overlay, and the Grinding and finishing processability of the built-up portion can be greatly improved.

According to the detailed characteristics of the manufacturing method of the present invention, when the wear-resistant coating layer on the outer circumferential surface of the cylindrical body is formed by thermal spray overlay of a self-fusing alloy, it is preferable to perform a fusing treatment after the thermal spray overlay. . Further, according to the manufacturing method of the present invention, the formation of the wear-resistant coating layer on the outer circumferential surface of the cylindrical body and the subsequent fusing treatment are performed while rotating the cylindrical body around its central axis, so that the outer circumferential surface of the cylindrical body A wear-resistant coating layer having a uniform thickness can be formed over the entire wear-resistant coating layer, and the fusing treatment thereof can also be performed uniformly over the entire wear-resistant coating layer.

An example of a method for manufacturing a valve locking arm for an internal combustion engine according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side view showing an example of a valve rocker arm for an internal combustion engine according to the present invention. In the figure, 1 is a rocker arm body, which in this case is manufactured by casting, for example, an aluminum alloy.

The rocker arm main body 1 has a circular hole 2 formed in its center, through which the rocker shaft passes, and is connected to the stem of the engine valve at the right end in the figure, while the left end contacts the cam of the camshaft. The pad portion 3 is designed to A metal piece element 5, which has been previously coated with a wear-resistant coating layer 4 on one surface, is joined to this pad portion 3 with the other surface by appropriate means such as casting, brazing, or welding. The substantial surface of the pad portion is defined by a round circumferential surface curved at a predetermined curvature by the wear-resistant coating layer 4. The wear-resistant coating layer 4 may be composed of a chrome plating layer, a thermally sprayed overlay of Ni-based, CO-based, or Fe-based self-fluxing alloy, or a layer of chilled cast iron, and the metal piece element 5 is made of carbon steel. , alloy steel, cast iron, or cast steel. FIG. 2 is an explanatory drawing showing the manufacturing process of a valve locking arm for an internal combustion engine according to the present invention, which will be explained step by step below. First, as shown in FIG. 2, a cylindrical body 10 made of a carbon steel pipe material having a curvature (smaller diameter) larger than the curvature of the pad surface of the rocker arm by a predetermined amount is prepared, and this is degreased with triclean and thoroughly dried. The outer peripheral surface of the cylindrical body is roughened by shot blasting with post-fired alumina (grid diameter of about 1 to 3 nm).

Next, while rotating the cylindrical body 10 around its axis, a self-fusing alloy powder of 0.3 to 0.717% is applied to the outer peripheral surface by thermospraying or plasma spraying. The cylindrical body 1 is coated uniformly to a thickness of approximately L as shown in FIG.
The entire outer circumferential surface of 0 is covered with a wear-resistant coating layer 4 made of a thermally sprayed overlay layer of the self-fluxing alloy powder. Next, in order to increase the adhesion between the cylindrical body 10 and the coating layer 4 and the bonding strength of the coating layer itself, fusing treatment is performed by high frequency heating, heating with an acetylene flame, heating in a furnace, etc., and at the same time, a uniform coating layer is formed. obtain. Incidentally, in order to further improve the adhesion between the cylindrical body 10 and the coating layer 4, grooves 11 are formed on the outer peripheral surface of the cylindrical body 10 by lathe processing or the like, as shown in FIG.
It would be better if it had some unevenness. For example, using the thermospray method, Ni
self-fusing alloy of the system (65.5%Ni-17.0%Cr-
0.6%C-3.5%B-4.4%Si-4.
When thermally spraying powder (0%Fe-2.0%MO-3.0%Cu), it is preferable to preheat the cylindrical body 10 to 150 to 250°C with an oxygen-acetylene burner, and after thermal spraying. 1100'C again with oxygen-acetylene burner
It is preferable to fuse the self-fusing alloy sprayed layer by heating the sprayed layer to a temperature close to The self-fluxing alloy for thermal spraying constituting the coating layer is a CO-based stellite alloy (66% CO-
26% Cr - 5% W - 1% C) powder may be used, and when such a stellite alloy powder is thermally sprayed, it is thermally sprayed by a plasma spraying method, and immediately after thermal spraying, it is heated by high frequency to 130%
Fusing treatment may be performed by reheating to 0 to 1350°C. Further, as the self-fluxing alloy for thermal spraying, Fe-based (2
5%Cr-2%B-1%Si-3.5%C-10%M
O- 2%W- 2.5%Ni-25%CO-Remaining Fe
) Alloy powder may be used, and when this alloy powder is sprayed by plasma spraying, 115% is applied in a hydrogen atmosphere after spraying.
Fusing treatment may be performed by heating in a furnace to 0 to 1200°C. Thus, as shown in FIG.
Once the coating layer 4 of a predetermined thickness is formed on the outer circumferential surface of the pad by thermal spraying, the outer circumferential surface of the coating layer 4 is then cylindrically ground to a predetermined dimension such that the outer circumferential surface curvature is equal to the predetermined pad surface curvature. Finish by grinding.

Next, the cylindrical body 10 is cut to the width of the rocker pad surface as shown in FIG. 2, and then further cut to a predetermined length in the circumferential direction as shown in FIG. A metal strip element 5 is completed, which is provided with a wear-resistant coating layer 4. The thus completed metal piece element 5 is held on the side on which the coating layer 4 is not applied and is placed in the pad portion 3 of the rocker arm body (indicated by reference numeral 1 in FIG. 1) by casting or other appropriate means. Then, they are joined together to obtain a valve locking arm as shown in FIG. Incidentally, when the metal piece element 5 is joined to the rocker arm main body 1 by casting, a cylindrical body 10 having an uneven shape on the inner circumferential surface as shown in FIG. 4 may be used to increase the strength of the joint. In this case, the cylindrical body 10 is FCG3
It may be manufactured by casting O. Conventionally, when spraying a self-fusing alloy onto the pad of the valve head noka arm,
The Rocker arm bodies are lined up in parallel, degreased, dried, shot blasted, preheated, sprayed overlay, and fused, and then the sprayed overlay is finished by grinding. The yield of self-fusing alloy powder when spraying overlay on the pad part is very poor, and depending on the shape of the rocker arm, the yield is 40 to 50%.
It may be about %.

On the other hand, in the case of the present invention, since the self-fusing alloy powder can be thermally sprayed continuously on the outer peripheral surface of the cylindrical body without any intervals, the thermal spraying efficiency (yield) reaches 75% to 85%. Next, when performing fusing treatment after thermal spraying, conventionally it is necessary to heat the pad surface of the rocker arm, but it is difficult to uniformly heat just that pad surface, and even if it were possible to heat evenly, the rocker pad surface must be heated to the rocker body. There is a large energy loss due to heat conduction. In the case of the present invention, by heating the cylindrical body while rotating, it is possible to easily and uniformly heat the pad, and the energy required for heating only the pad portion is also minimal, which is useful in the current situation where energy costs are rising. This is one of the big advantages. In addition, when thermal spraying is applied directly to the pad of the rocker arm body as in the past, during the fusing process, the thermal spraying must be done in two steps to prevent peeling from the pad corner. ,
Furthermore, during the fusing treatment, the thermal sprayed build-up layer bulges in the center due to surface tension, making it impossible to obtain a build-up layer of uniform thickness. On the other hand, in the case of the present invention, since the ring is thermally sprayed on the outer peripheral surface of the ring, uniform heating can be obtained, and since it is a continuous body, there is no fear of peeling.
Since a sprayed overlay layer of approximately wL can be easily and uniformly fused, the grinding allowance after fusing can be minimized. This is particularly effective in the case of self-fusing alloys such as Fe-based and CO-based self-fusing alloys, which are prone to surface sagging and are difficult to undergo fusing treatment. In addition, the coating layer can be ground using a cylindrical grinder.
The grinding work becomes easy and high precision grinding can be performed.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a valve locking arm for an internal combustion engine according to the present invention, FIG.
4 and 4 are explanatory diagrams showing other embodiments of the cylindrical body used for manufacturing the Valprock arm of the present invention. 1... Rocker arm body, 2... Hole, 3... Pad portion, 4... Wear-resistant coating layer, 5... Metal Piece element, 10...Cylindrical body, 11...Groove.

Claims (1)

[Claims] 1. While rotating a metal cylindrical body around its central axis, a self-fusing alloy is thermally sprayed on the outer peripheral surface of the metal cylinder to form a wear-resistant coating layer, and the wear-resistant coating layer is further subjected to a fusing treatment,
Thereafter, the cylindrical body is cut into pieces having a predetermined width in the axial direction and a predetermined length in the circumferential direction to obtain a curved metal piece element, and the rocker arm body is obtained while maintaining the curved shape of the metal piece element. 1. A method of manufacturing a valve rocker arm for an internal combustion engine, the method comprising joining a valve rocker arm to a pad portion of the valve rocker arm at the concave side of the curved shape.