JPH0471729A - Manufacture of cam shaft - Google Patents

Abstract

PURPOSE:To obtain the cam shaft of light weight and high strength by forming the cam piece being the cam shape on its circumferential surface of the pipe material, temporarily setting the piece to stop the rotation fittable for the inner surface of its projecting part at the inner surface of the projecting part, inserting the pipe material, expanding and fixing the pipe material with buldging work. CONSTITUTION:The forming of the cam pieces 1, 1 is that the long size pipe material is formed to the shape of the cam like section area with drawing and cut in round slices with prescribed length or that the pipe material is formed to the cam shape with pressing after cutting it to the prescribed length. The piece to stop rotation 2 is that the rod steel is drawn, and formed to the shape so that its one surface 2a is fitted to the shape of the inner surface 1b of the projecting surface 1a of the cam piece 1, and this is cut to almost the same length with the thickness T of the cam piece 1. Next, the piece to stop rotation 2 is set on the inner surface 1b of the projecting surface 1a of the cam piece 1 temporarily, the pipe material 3 is inserted in these cam pieces 1 and entered in the buldging die 4, the pipe material 3 is expanded with buldging and pressed and fixed to the inner circumferential surface of the cam piece 1 and the piece to stop rotation 2.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a camshaft.

(Prior technology) Camshafts that operate the intake and exhaust valves of engines have traditionally been manufactured by casting or forging, but this method requires a large amount of material and is heavy, so in recent years, camshafts have been installed on the circumferential surface of the vibrator. A camshaft that is lightweight by fixing it is attracting attention.

In this case, it is important to secure the cam piece to the pipe material so that they do not rotate relative to each other in order to maintain the correct opening and closing timing of the valve.
Therefore, a spline-like groove is formed on the inner circumferential surface of the cam piece, and a pipe material is press-fitted into this groove during bulge processing to prevent rotation (Japanese Patent Application Laid-open No. 59-130632). A type in which a protrusion is provided and the protrusion is press-fitted into the pipe material to prevent it from rotating when it is fixed to the pipe material, and also to prevent unreasonable expansion and deformation of the pipe material (Japanese Patent Laid-Open Publication No. 144532/1983), etc. There is.

(Problem to be Solved by the Invention) However, in all of the above methods, in order to provide grooves and protrusions on the inner circumferential surface of the cam piece, it is necessary to integrally mold the cam piece with a sintered alloy or a casting, and the force There is a problem that the cost increases.

In view of this, the present invention has been made for the purpose of providing a method of manufacturing a camshaft that can be obtained at low cost.

(Means for Solving the Problems) As a means for solving the problems of the above-mentioned prior art, the present invention provides the following:
A cam piece whose circumferential surface has a predetermined cam shape is formed from a pipe material, and the cam piece is formed into a cross-sectional shape that matches the inner surface shape of the portion that becomes the convex portion, and has a length approximately equal to the thickness of the cam piece. A stopper piece is provided, and this stopper piece is temporarily attached to the inner surface of the convex portion. Then, pipe materials are inserted through these cam pieces and housed in a bulge mold, and the pipe material in all parts where the cam piece is fitted is bulged by bulge processing. This feature is characterized in that the cam piece is pressed and fixed in accordance with the shape of the inner circumferential surface of the cam piece and the rotation prevention piece.

(Function) The cam piece is obtained by cutting the pipe material into a length corresponding to the thickness of the cam and by molding the outer peripheral surface shape to the specified shape as the cam, so it is extremely inexpensive, and this cam piece has a uniform wall thickness, and the amount of bulge deformation due to the bulge processing of the part of the pipe material that is inserted into the shaft that corresponds to the convex part of the cam becomes large, but since this part is filled with the rotation stopper piece, the unreasonableness of the pipe material There is no bulge, and there is no cracking or thinning of the pipe material at the joint.

(Example) The present invention will be described below with reference to embodiments shown in the drawings.

Cam piece 1, 1. ... is obtained by cutting a pipe material into a length corresponding to the thickness of the cam and molding the outer peripheral surface into the specified shape of the cam. Select any method such as forming the cross section into a cam shape by processing and cutting it into rings to a predetermined length, or cutting the pipe material to a predetermined length and then forming it into a cam shape by press working. I can do it. The peripheral surface of the cam piece material thus formed is subjected to surface hardening treatment such as polishing and quenching to form the cam piece 1 (
Figure 2).

The anti-rotation piece 2 is made of, for example, a steel bar, and one surface 2a of the bar is formed by drawing the steel bar into the cam piece 1.
It can be obtained by molding it into a shape that matches the shape of the inner surface 1b of the convex portion 1a, and cutting it into a length approximately equal to the thickness T of the cam piece 1 (FIG. 3).

One surface 2a of the detent piece 2 thus formed is temporarily attached to the inner surface 1b of the convex portion 1a of the cam piece 1 by adhesive, resistance welding, etc., as shown in FIG. By fitting the several cam pieces 1, 1... into the pipe material 3 that becomes the shaft, and placing the cam pieces 1, 1... in the position of each cam mold in the bulge mold 4, the cam pieces 1゜1... Determine the installation angle relationship.

Then, by injecting pressure liquid from one end of the pipe material 3 or by performing a bulging process using a rubber bulge, the cam pieces 1, 1, . The pipe material 3 in the portion where the ... is fitted bulges out, and as shown in Figure 5, the cylindrical inner circumferential surface of the cam piece 1 as well as the convex portion 1 to which the detent piece 2 is temporarily attached are formed.
The inner surface 1b of a is bulged and integrated. At this time, a detent piece 2 is attached to the inner surface 1b of the convex portion 1a of the cam piece 1.
is temporarily attached, the pipe material 3 only slightly enters both sides of the anti-rotation piece 2 and bulges out, and the amount of deformation of the swollen portion 3a of the pipe material 3 is extremely small and prevents rotation. The piece 2 is fixed in an immovable state, and the cam piece 1, the anti-rotation piece 2, and the pipe material 3 are completely integrated.

In addition, since the pipe members 3 on both sides of the cam piece 1 also bulge out slightly, the cam piece 1 is fixed against any displacement in the axial direction.

Therefore, since the cam piece 1 can be integrated by reducing the amount of bulge of the pipe material 3, the amount of thickening of the pipe material 3 between the cam pieces 1.1 is also small, and the cam pieces 1, 1...
- There is no cracking or thinning of the bulging portion 3a of the pipe material 3 in the portion to which it is fixed.

When the shape of the inner surface 1b of the convex portion 1a of the navigator beam 1 is a circular arc or a shape close to it, the detent piece 2 can be used as a round steel without drawing or the like.

〔Effect of the invention〕

As explained above, according to the present invention, the cam piece is obtained by cutting pipe material into rounds, so it is extremely inexpensive.
In addition, since the cam piece has a uniform wall thickness, the increase in the amount of bulge due to bulging of the pipe material used as the shaft is suppressed by filling in the anti-rotation piece temporarily attached to the inner surface of the convex part of the cam piece. The cam piece can be prevented from rotating and firmly fixed without causing forced local bulging deformation. Furthermore, since the pipe material bulges on both sides of the cam piece, there is no axial movement of the cam piece, making it possible to obtain a camshaft that is inexpensive, suitable for mass production, and lightweight and strong.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a part of a camshaft obtained according to the present invention, Fig. 2 is a perspective view of a cam piece formed from pipe material, Fig. 3 is a perspective view of a detent piece formed from a steel bar, and Fig. 4 5 is a perspective view showing a state in which a rotation stopper piece is temporarily attached to a cam piece, and FIG. 5 is a sectional view showing a state in which the cam piece is fixed to a pipe material by a bulge type. DESCRIPTION OF SYMBOLS 1... Cam piece, 1a... Convex part, 1b... Inner surface of convex part, 2... Stopper piece, 3... Pipe material,
3a...Bulge part, 4...Bulge type.

Claims (1)

[Claims] A cam piece whose circumferential surface has a predetermined cam shape is formed from a pipe material, and the cam piece is formed into a cross-sectional shape that matches the inner surface shape of the portion that becomes the convex portion, and has a length approximately equal to the thickness of the cam piece. A stopper piece is provided, this stopper piece is temporarily attached to the inner surface of the convex portion, and then pipe materials are inserted through these cam pieces and housed in a bulge mold, and the pipe material at the cam piece fitting portion is bulged by bulge processing. A method for manufacturing a camshaft, characterized in that the camshaft is press-fitted in accordance with the inner peripheral surface shape of the cam piece and the rotation prevention piece.