JPS60190501A - Fitting and fixing method of sintered parts - Google Patents

Abstract

PURPOSE:To fix tentatively a sintered part with high accuracy without trouble such as breakage, etc. by welding a metallic piece inserted into the through-hole provided to the sintered part to a shaft member in the stage of inserting the shaft member into the fitting hole of the sintered part and subjecting both to diffusion joining. CONSTITUTION:A fitting hole 3 for fitting a shaft 2 as a shaft member is formed to a cam 1 of, for example, an engine, as a sintered part and a through- hole 5 intersecting orthogonally with the axial direction of the hole 3 is provided to the peripheral wall part 3a of the hole 3 from the outside toward the hole 3. The shaft 2 is first inserted into the hole 3 and the relative positions of the cam 1 and the shaft 2 are set in the axial direction of the shaft 2 then in the circumferential direction. A steel ball 8 as a metallic piece having approximately the same diameter as the diameter of a hole 5 is inserted into said hole in this stage and electricity is conducted via the ball 8 to the shaft 2 by a welding electrode 9. The ball 8 is then resistance-welded to the shaft 2, and the shaft 2 and the cam 1 are restrained axially and acircumferentially by which the shaft cam are tentatively fixed to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION In addition to industrial applications, the present invention relates to a method for fitting and fixing sintered parts such as cams in engine camshafts to shaft members such as shafts, and is useful in the manufacture of automobiles and various sintered parts. It can be used in the field of manufacturing joint parts.

BACKGROUND OF THE INVENTION It is well known that sintered parts are increasingly being used as parts of automobile engines that require strong wear resistance, such as cams in valve train mechanisms. This type of cam is installed in the engine by being attached to a shaft that rotates in synchronization with the crankshaft.
Since the cam is a sintered part, there are problems when attaching it to the shaft as described below.

In other words, the cam is generally attached to the shaft by inserting the shaft into its fitting hole, but in order to time the opening and closing of the engine's pulp, the cam is attached to a certain position in the circumferential direction (so-called phase) relative to the shaft. Therefore, in the past, a V-groove along the axial direction was formed on the outer surface of the shaft, and a protrusion was formed on the inner surface of the fitting hole in the cam, and these grooves and protrusions were engaged. This method determines the phase and fixes it in the circumferential direction, and fixes it in the axial direction by caulking a part of the shaft. However, with this method, play occurs in both the circumferential direction and the axial direction, resulting in poor mounting accuracy in many cases, and the need to machine the V-groove increases costs. There's a problem.

On the other hand, there is a method of attaching the cam to the shaft by press-fitting the shaft into a fitting hole formed in the cam, and with this method, the cam and shaft can be easily attached without causing play. Can be fixed.

However, when fitting and fixing the cam and shaft,
Normally, the cam is pre-sintered before it is fitted onto the shaft, and then the main sintering process is carried out, but the dimensional precision of the cam is poor and its strength is insufficient when fitted. There is a problem in that the cam may crack due to the stress caused by press-fitting the shaft, or conversely, the inner diameter of the fitting hole into which the shaft is inserted is too large and the cam and shaft cannot be fixed to each other.

Purpose of the Invention The present invention has been made in view of the above circumstances, and it is an object of the present invention to easily and precisely fit and fix a sintered part to a shaft member without causing any inconvenience such as breakage of the sintered part such as a cam. The purpose is to provide a method that allows for

The implantation of the invention, that is, the method of fitting and fixing 4/R joint parts of the present invention is to form a fitting hole in a sintered part made by pre-sintering metal powder, and insert a shaft member into the fitting hole. Prior to joining the tA-bonded part and the shaft member by diffusion bonding by inserting and performing main sintering, the sintered part is provided with a through hole that reaches the fitting hole from the outside, and the sintering process is performed. After inserting the shaft member into the fitting hole of the component and setting the relative positions of the sintered component and the shaft member in both the axial and circumferential directions of the shaft member, in that state, the 5I of the sintered component A metal piece with approximately the same diameter as the through hole is inserted into the different hole, and the metal piece is joined to the shaft member by resistance welding to temporarily fix the shaft member to the sintered part, and then main sintering is performed. This is characterized in that the sintered part and the shaft member are bonded and fixed to each other.

Next, an embodiment of the method of fitting and fixing sintered parts according to the present invention will be described.

1 and 2 show, as an example of a sintered part, a cam 1 in a valve train of an automobile engine.

The cam 1 is made by pre-sintering metal powder, and has a fitting hole 3 formed therein for fitting a shaft 2 as a shaft member shown in FIG.

The cam 1 is provided with a hole 4 on the side surface of the convex portion 1a, and a hole 4 is provided in the peripheral wall portion 3a of the fitting hole 3. A through hole 5 is provided as shown in FIG.

To fit and fix the above cam 1 onto the shaft 2, proceed as follows.

First, as shown in FIG. 3, the shaft 2 is inserted into the fitting hole 3 of the cam 1, and the shaft 2 is aligned in the axial direction. The relative position of the cam 1 and the shaft 2 is set with the cam 1 in contact with the nib flange 6. Next, insert a suitable rod 7 into the hole 4 of the cam 1, rotate the shaft 2 while stopping the rotation of the cam 1, and measure the relative position of the cam 1 and the shaft 2 in the circumferential direction of the shaft 2. Set.

Next, in this state, a fly ball 8 is inserted into the n through hole 5 of the cam 1 as a metal piece having approximately the same diameter as the through hole 5, and the shaft 2 is energized via the steel ball 8 by the welding electrode 9. . Thereby, the steel balls 8 are resistance welded to the shaft 2, and as a result, the shirts 1 and 2 and the cam 1 are restrained from relative movement in both the axial and circumferential directions by the steel balls 8, and are temporarily fixed to each other. As shown in FIG. 4, a spherical seat 10 that contacts the steel ball 8 is provided at the tip of the welding electrode 9 in advance, and a pore 11 that reaches the spherical seat 10 from a suction device (not shown) is provided so that the cam of the steel ball 8 1. When inserting the steel ball 8 into the through hole 5, the steel ball 8 is placed in the spherical seat 10, and the steel ball 8 is held at the tip of the welding electrode 9 by suction from the small hole 11.
It is extremely convenient to insert the through hole 5 of the cam 1 and perform resistance welding as it is.

Finally, the cam 1 and the shaft 2, which have been temporarily fixed to each other as described above, are heated in that state to undergo final sintering, and are bonded and fixed to each other. When the cam 1 and shaft 2 that are temporarily fixed to each other are heated, the pre-sintered cam 1 contracts in the process, and the diameter of the fitting hole 3 also decreases. The entire circumferential surface is in close contact with the outer circumferential surface of the shaft 2, and in this state, the cam 1 and the shaft 2 are joined by a well-known heat diffusion mechanism.

In the above embodiment, a steel ball was used as the metal piece inserted into the through hole 5 of the cam 1, but the metal piece is not limited to a steel ball, and any suitable metal bottle or the like may be used. Furthermore, the method of the present invention is not limited to the case of fitting and fixing the cam 1 and the shaft 2 as in the above embodiments, but is also applicable to other shaft members and appropriate sintered parts to be fitted thereto. It can also be applied when fitting and fixing.

Effects of the Invention As described above, according to the method for fitting and fixing sintered parts of the present invention, after setting the relative position of the sintered part and the shaft member in both the axial direction and the circumferential direction of the shaft member, In this state, the metal sphere inserted into the through hole of the sintered part is joined to the shaft member by resistance welding to temporarily fix the shaft member to the sintered part, and then main sintering is performed to form the sintered part. By joining and fixing the sintered parts and the shaft member to each other, the sintered parts can be easily and precisely fitted and fixed to the shaft member without causing the inconvenience of breaking the sintered parts such as the cam. I can do it. That is, according to the method of the present invention, the fixing precision of the sintered part in the axial direction and circumferential direction of the shaft member is improved, and the machining allowance during finishing machining is accordingly reduced, resulting in improved material yield and machining efficiency. will improve. Furthermore, in this invention, the relative position n1, that is, the phase, between the shaft member and the sintered component with respect to the circumferential direction of the shaft member can be changed steplessly.
When the cam and the shaft are fitted and fixed, it is easy to change the phase of the cam, and as a result, it is possible to improve the performance of the equipment in which the cam is installed.

[Brief explanation of the drawing]

Fig. 1 is a front view of the cam in the camshaft of an engine, Fig. 2 is a view in the direction of the arrow in Fig. 1, and Fig. 3 is a cam shank left side of the cam shank shown in Figs. 1 and 2. FIG. 4 is a sectional view showing a fitted and fixed state, and FIG. 4 is a sectional view of an electrode suitable for use in implementing the present invention. DESCRIPTION OF SYMBOLS 1...Cam, 2...Shaft, 3...Fitting hole, 5...Through hole, 8...Steel ball, 9...Welding electrode. Applicant I~Yota Jikosha Co., Ltd. Agent Patent Attorney Yutaka 1) Hisashi Take (one idiot) Figure 1 Figure 2■ Figure 31 Figure 4

Claims (1)

[Claims] A fitting hole is formed in the sintered part by preliminary sintering of the metal powder, and the shaft member is inserted into the fitting hole and main sintering is performed to connect the sintered part and the shaft member. When joining by diffusion bonding, the sintered part is provided with a through hole that reaches the fitting hole from the outside, and the shaft member is inserted into the fitting hole of the sintered part, and the shaft member is aligned in the axial direction and circularly. After setting the relative position of the sintered part and the shaft member in both circumferential directions, in that state, insert a gold piece with approximately the same diameter as the through hole of the sintered part, and then insert the metal Welding the pieces together
A sintered part characterized in that the shaft member is temporarily fixed to the sintered part by being joined to the @ member, and then main sintering is performed to mutually join and fix the sintered part and the shaft member. Fitting and fixing method.