JPS58176411A - Manufacturing method of combined type outer sleeve/cam follower assembly of hydraulic valve lifter for internal-combustion engine - Google Patents

Abstract

PURPOSE:To make easy a machining operation and improve a mass-producibility, by manufacturing an outer sleeve and cam follower separately and then jointing them together by welding, in an oil tappet for use in an air intake/exhaust valves driving system of an internal-combustion engine. CONSTITUTION:A lower edge of an outer sleeve stock 10 is ground and then formed an annular projection 12 thereon, and furthermore has its carburized case removed at a portion adjacent to the projection 12 for obtaining the outer sleeve stock 10. A cam follower stock 18 is obtained by casting an alloy cast iron into a desired shape and then performing an end-face finish on its upper and lower surfaces. In this manner, a precast outer sleeve stock and a cam follower stock are abutted each other, and then jointed together by welding with a condenser type resistance welding machine. This manufacturing process can allow the outer sleeve stock and the cam follower stock both to select a suitable material for their intended applications.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a main body portion of a hydraulic pulp lifter used in a pulp train of an overhead pulp type internal combustion engine.

In some overhead internal combustion engines, a hydraulic pulp lifter is installed between the cam and the one-way rod to absorb the thermal expansion of the pulp train and compensate for the wear of the components over time to maintain the pulp clearance at zero. It has been inserted. An example of such a pulp lifter is the one described in Japanese Patent Publication No. 54-43125. The valve lifter has a main body part that constitutes its outer shell, and the main body part consists of an outer sleeve part having a cylindrical inner hole, the outer sleeve part and a bottom plate part, and this bottom plate part is connected to the camshaft. It constitutes a cam follower part that abuts and follows the cam. A plunger, a pusher rod seat, etc. are slidably housed in the inner hole of the outer sleeve portion. The valve lifter constructed in this way is slidably inserted into the hole between the cam and the bushing rod, where the valve lifter mounting hole is formed on the encoder block. During operation of the engine, the lower surface of the cam follower is subjected to wear and impact by the cam, and the outer peripheral surface of the outer sleeve portion is subjected to wear due to sliding with the hole in which the valve lifter is attached.

For this reason, it is desirable to use materials suitable for each of the outer sleeve portion and the cam follower portion, and to perform surface treatments suitable for each.

The knoll prelifter main body, which is an assembly of an outer sleeve part and a cam follower part, can be roughly divided into an integral casting type and a joining type, depending on the manufacturing method.

In the former manufacturing process, both the outer sleeve part and the cam follower part are cast integrally in a single casting process, and the inner and outer diameters of the thus formed casting are adjusted to the desired dimensions and shape. The final product is obtained by polishing, heat treating, and any necessary final polishing. deer')
However, in this method, since the outer sleeve part and the cam follower part are integrally cast from the same material, the material of the main body part is determined preferentially in relation to the cam.
The material selection of the outer sleeve portion is secondary to the valve lifter attachment, which should be determined based on the relationship with the hole. As a result, alloy cast iron is mainly used as the material to obtain a cam follower sliding surface that has excellent wear resistance and pitting resistance against the cam. Alloy cast iron has poor machinability, and machining the inner diameter of the outer sleeve is particularly difficult.
The integrally cast outer sleeve/cam follower assembly has poor quality and is expensive, and is not suitable for mass production.

The latter joint type outer sleeve/cam follower m-3D eliminates these drawbacks, and when manufacturing it, the outer sleeve part and the cam follower part can be manufactured separately in advance from materials that are suitable for each. . That is, the cam follower part is manufactured by casting using alloyed cast iron, and the outer sleeve part is made of carbon steel, etc., which has good machinability and fits the hole for mounting the valve lifter in the cylinder block. The outer sleeve portion and cam follower portion thus manufactured in advance are joined by brazing to form an assembly as shown in FIG. 1, which is subjected to necessary machining and then subjected to appropriate surface treatment. This surface treatment involves hardening the cam follower part to obtain a sliding surface with the desired wear resistance and pitting resistance, and carburizing and hardening the outer sleeve part to give the outer peripheral surface the desired properties. The purpose is to impart wear resistance, etc. In the production of conventional bonded outer sleeve/cam follower assemblies, brazing is first carried out by maintaining the entire assembly at a predetermined carburizing temperature and carburizing the outer sleeve portion, and then brazing to a predetermined quenching temperature. The outer sleeve part and cam follower part were hardened at this hardening temperature by lowering the temperature. However, in this method, in the brazing filler metal and
During the carburizing process, the cam follower part is exposed to high temperatures for a long time, so the cementite in the cast alloy base material of the cam follower part decomposes and graphite precipitates or grows in the base material, causing the cam follower to become damaged. reduce the quality of the parts. In order to avoid this, if carburizing is carried out at a hardening time and temperature that does not cause deterioration of the cam follower part, the carburizing atmosphere will not be able to penetrate deep into the inner hole of the outer sleeve because it is done after brazing. A satisfactory, uniform, and desired carburizing depth cannot be obtained, resulting in a decrease in quality. There is also the problem of corrosion due to improper cleaning of the flux used during waxing.

The present invention was devised in view of the above-mentioned problems of the prior art, and it is possible to use materials suitable for each of the cam follower part and the outer sleeve part, and to perform surface treatments suitable for each. Another object of the present invention is to provide a method for manufacturing a bonded outer sleeve/cam follower assembly that is of high quality and suitable for mass production at low cost.

In order to achieve the above object, the method for manufacturing a joint type outer sleeve/cam follower assembly of the present invention includes carburizing a pre-formed outer sleeve to form a carburized layer of uniform depth on the surface, and then slowly cooling it. Next, the lower edge of the outer sleeve material is machined to form an annular 10-gear extension along the lower edge, and at the same time, the carburized layer in the projection area that adversely affects welding is removed, and the preformed cam follower material and After forming an outer sleeve/cam follower assembly by welding the above outer sleeve part material using a 10-judge welding process that does not deteriorate the cam follower and eliminates the need for brazing filler metal, flux, etc. and is suitable for mass production,
Machining is performed as necessary, and the entire outer sleeve/cam follower assembly is quenched under quenching conditions that do not deteriorate the cam follower and give the necessary hardening to the image material, and then tempered as necessary, followed by finishing processing. It is characterized by: Here, carburizing treatment does not only include carburizing treatment in a narrow sense, but also broadly includes carbo-nitriding treatment in which nitriding progresses at the same time as carburizing, and similarly, carburized layer also means carbonitrided layer. do.

As described above, according to the method of the present invention, the outer sleeve part and the cam follower part are manufactured separately, and since the outer sleeve part is carburized in advance before welding with the cam follower part, it is difficult to join them after welding. By simply quenching the body at a predetermined quenching temperature and then subjecting it to tempering as necessary, the quenching process suitable for each of the outer sleeve portion and the cam follower portion is completed at the same time. Therefore, since the cam follower part is not exposed to high-temperature carburizing treatment, graphite in the cam follower part base material does not precipitate or grow. In addition, since the outer sleeve part and the cam follower part are manufactured separately, it is possible to enjoy the advantage of the joint type in that materials suitable for each can be used, and the inner diameter of the outer sleeve can be easily machined. .

The capacitor set projection welding method is known as a welding method suitable for welding dissimilar metals (Special Publication No. 53-1).
No. 0935), this welding method is particularly suitable for welding the outer sleeve and cam follower of the valve lifter according to the invention. By applying the capacitor complete projector welding method instead of conventional brazing, there is no problem of corrosion caused by insufficient cleaning of flux and graphite precipitation and growth due to the heat during brazing the outer sleeve/cam follower assembly. , it is possible to mass produce in a shorter time. In addition, the carburized layer of the welded part which adversely affects the welded part, which is often caused by carburizing before welding, can be removed at the same time as the machining for forming the projection, so there is no problem at all.

In the present invention, it is preferable to use alloy cast iron as the cam follower material, and to use cold forged steel or pipe material as the outer sleeve material.

Next, the present invention will be described in detail with reference to the accompanying drawings. The outer sleeve material 10 is a cold forged product (for example, S1
5C) or a pipe material (for example, STKMI 2 ), and is formed by machining or the like as shown in FIG. 2. Next, this outer sleeve material is subjected to carburizing treatment or carbo-nitriding treatment by a conventional method, and then slowly cooled by air cooling or furnace cooling. Preferably, the carburizing temperature is about 900°C and the treatment time is about 3 to 4 hours. The reason for slow cooling was to facilitate the subsequent machining. Next, as shown in FIG. 3, the lower edge of the outer sleeve material 10 is cut to form an annular projection 12 along the lower edge, and a carburized layer (or carbo-nitrided layer) 14 is formed. Of these, a portion 16 near the projection is removed.

The reason why the carburized layer 16 in the vicinity of the projection is removed is because the carburized layer 16 to be welded also has a high carbon content, and if this is left, cracks will occur near the weld joint. The shape of the projection 12 is such that the taper angle α of the tip is 30° to 60', and the W of the projection tip is 0.
It is suitable that the length is 2 to 0.7 m. In this way, the outer sleeve material 10 shown in FIG. 3 (f3) is obtained.

On the other hand, as shown in FIG. 4, the cam follower member material 18 is obtained by casting alloy cast iron into a desired shape and finishing the upper and lower surfaces. The four parts of the cam follower material may be left as cast.

The outer sleeve part material and the cam follower part material formed in advance are brought into contact with each other, and while applying high pressure, a large current value having a current flow waveform as shown in Fig. 5 is applied using a capacitor set resistance welding machine. Instantly energizes and performs projection welding. Current rise time T8 is approximately 4~gms
ec and the current application time T are preferably about 10 to 20 m5ec.

After welding, the outer sleeve part and cam follower are machined to form oil grooves on the outer periphery of the outer sleeve part and machined to remove burrs as necessary, and the entire joint is maintained at approximately 830 to 880'O for about 1 to 2 hours to remove the outer sleeve part and cam follower. Both parts are quenched and tempered at the same time. Finally, finishing is performed to obtain the final product of the outer sleeve/cam follower assembly 1. Figure 6 shows the configuration of a hydraulic pulp lifter using the outer sleeve/cam follower assembly manufactured by the method of the present invention. 20 is an outer sleeve/cam follower assembly, 22 is a projection welding part, 24 is a plunger, 26 is a check pole,
28 is a check pole retainer, 30 is a return spring, and 32 is a bushing rod seat.

As is clear from the above, according to the method of the present invention, the outer sleeve portion and the cam follower portion are joined by separately manufactured edge welding, so it is possible to use materials suitable for each. Additionally, since the outer sleeve part is carburized before welding, the cam follower part is not exposed to excessively high temperatures during subsequent processing.
Graphite does not precipitate or grow in the base material of the cam follower part. Further, since the outer sleeve portion is carburized before welding, it is possible to easily form a carburized layer with a sufficiently uniform depth on the inner hole wall. Therefore, it is possible to obtain an inner circumferential surface having a sliding surface with excellent wear resistance against the plant gear. Furthermore, a material that is easy to machine can be used for the outer sleeve, and since the outer sleeve is slowly cooled after being carburized, machining is easy. Therefore, according to the present invention, high quality outer sleeve/cam follower assemblies can be mass-produced at low cost. In addition, since capacitor-type glojection welding is used instead of conventional brazing, there is no need for brazing filler metal or flux, making it cheaper, and there is no need to worry about corrosion caused by flux. There is no problem with deterioration.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a joint type outer sleeve/cam follower assembly using the conventional brazing method, Fig. 2 is a cross-sectional view of the outer sleeve according to the method of the present invention, and Fig. 3 (c) is a projection of the outer sleeve material. Enlarged cross-sectional view, 3rd
) in the figure is a cross-sectional view of the outer sleeve material with the 10th diagonal in Figure 3 (4), Figure 4 is a cross-sectional view of the cam follower material, Figure 5 is a graph showing the energization waveform, and Figure 6 1 is a schematic cross-sectional view of a hydraulic pulp lifter using an outer sleeve/cam follower assembly manufactured by the method of the present invention. DESCRIPTION OF SYMBOLS 10... Outer sleeve part material, 12... Projection, 14... Carburized layer, 16... Carburized layer of projection area, 18... Cam follower part material. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A pre-formed outer sleeve material is carburized at a predetermined temperature to form a carburized layer on the surface, then slowly cooled, and the lower edge of the outer sleeve material is machined to create an annular projection along the lower edge. At the same time as forming the sleeve, the carburized layer in the projection area is removed, and the ridge of the outer sleeve/cam follower assembly is formed by projection welding the preformed cam follower material and the above outer sleeve material. Outer sleeve/
A method for manufacturing a jointed outer sleeve/cam follower assembly for an hydraulic pulp lifter for an internal combustion engine, which comprises quenching the entire cam follower assembly, tempering it if necessary, and then finishing it.