JPH04350307A - Manufacture of cam shaft and device thereof - Google Patents

Abstract

PURPOSE:To improve productivity in the manufacturing process of a cam shaft by machining a raw material of cam configuration using a shaving die, thereby finishing the raw material to the complicated cam configuration needed in designs with precision accuracy and in a short time. CONSTITUTION:When a cam shaft is manufactured, a bar material is first cut, and a cam raw material 1 for the inner and outer peripheral surfaces of which machining allowance is made, and is manufactured by forging. Then, a prepared hole provided to the cam raw material 1 is machined by broaching or turning, and finished by grinding to form a reference hole. The reference hole 1b is then put onto a reference pin 12 provided to a female die 14, and positioned by a knock pin 13. Thereafter, a shaving die 11 is moved to machine the outer peripheral surface of the cam raw material 1 into a designed configuration. A cam 10 machined in this manner is fixed, by shrinkage fit, to a specified position of a shaft 20 obtained by finishing machining utilizing turning and grinding of a pipe material and journals 21 are attached to the shaft so as to complete the manufacture of a cam shaft.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention is utilized for finishing the shape of a cam curved surface of a camshaft that opens and closes intake and exhaust valves of an internal combustion engine.

The present invention relates to a method and apparatus for manufacturing a camshaft using a cam whose outer shape is formed by a shaving die.

0003

[Prior Art] In order to subtly and effectively control the opening and closing operations of intake and exhaust valves that intake and exhaust combustion gas in internal combustion engine cylinders, the outer periphery of the cam is machined into a curved surface designed using extremely complex mathematical formulas. In conventional technology, the cam material is assembled onto the shaft, and the cam surface and shaft outer circumference are ground using numerical control based on both shaft centers to maintain the accuracy of the cam curved surface relative to the shaft center. Ta.

0004

[Problems to be Solved by the Invention] This method of obtaining precision through grinding requires special equipment because it is necessary to assemble the cam material onto the shaft and further perform grinding to form the camshaft. In addition, there are restrictions on the profile shape of the cam due to machining, which requires more machining time, which does not increase productivity, and causes design problems and the inability to reduce manufacturing costs.

The present invention solves these problems by reducing restrictions on the shape of the cam profile, improving engine performance, and shortening the machining time for cam curved surfaces, improving productivity and reducing costs. The purpose is to provide a method and manufacture that can measure the

[0006]

[Means for Solving the Problems] The present invention includes a step of forming a cam material into a designed cam shape, which is cut from a bar material, cold-forged, heat-treated, and subjected to primary processing of the shape. In the method of manufacturing a camshaft, the step of forming the cam into the cam shape includes inserting a shaving die having a curved surface corresponding to the designed cam shape into the cam material. It is characterized by including a shaving step performed by moving in a direction parallel to the axis of.

[0007] It is preferable that the shaving step is carried out with reference to the inner diameter of the insertion hole of the shaft for the manufacture of one cam, and the outer periphery of the cam is formed using a shaving die having a curved surface corresponding to the designed shape; The shaving die can be formed using a manufacturing apparatus equipped with means for moving the shaving die in a direction parallel to the axis of the cam blank.

[0008]

[Operation] A bar material is cut and cold forged, and the inner diameter of the heat-treated cam material is ground and a shaving die is formed with a curved surface that corresponds to the cam shape designed based on this inner diameter. Shaving is performed by moving the cam in a direction parallel to the axis of the material.

[0009] This makes it possible to form the cam shape with high accuracy relative to the shaft center, and furthermore, since grinding can be eliminated, machining time is shortened, improving productivity and reducing manufacturing costs. can do.

0010

Embodiments Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a perspective view illustrating the curved surface processing of a cam using a shaving die according to the present invention, FIG. 2 is a flowchart showing the flow of the process of manufacturing a camshaft according to the present invention, and FIG. 3(a)
is a perspective view showing the appearance of the cold-forged cam material;
b) is a perspective view showing the appearance of the cam after being processed by a shaving die, and FIG. 4 is a perspective view showing the completed state of the camshaft.

The apparatus according to the embodiment of the present invention includes a shaving die 11 formed with a curved surface corresponding to the designed cam shape;
A lower mold 14 provided with a reference pin 12 and a knock pin 13 for positioning, and means for placing and fixing the lower mold 14 and moving the shaving die 11 parallel to the axis of the cam blank 1 are provided. A press machine can be used as a means for moving.

Next, the manufacturing process of the camshaft shown in FIG. 2 will be explained.

First, a bar material is cut and a cam blank 1 with allowances for machining on the inner and outer peripheries as shown in FIG. 3(a) is produced by cold forging. Next, the pilot hole 1 provided in the cam material 1
After machining a by broaching or turning, the reference hole 1b is further finished by grinding as shown in Fig. 3(b).
will be established.

The reference pin 12 provided on the lower mold 14 is inserted into the reference hole 1b, and the position is determined by the dowel pin 13, and the shaving die 11 is moved in the direction of the arrow shown in FIG. 1 to design the outer periphery of the cam material 1. Process into the desired shape.

FIG. 3(b) whose outer periphery has been processed in this way
) The cam 10 shown in FIG. 4 is fixed by shrink-fitting to a predetermined position of a shaft 20 which is finished by turning and grinding a pipe material as shown in FIG. 4, and a journal 21 is attached thereto.

A feature of the present invention is that the cam shape is finished with a die formed based on the insertion hole of the shaft, and this allows processing to correspond to the cam shape required in the design with high precision. can be done in one step.

[0017]

As explained above, according to the present invention, by forming the cam shape using a shaving die during the camshaft manufacturing process, the complex cam shape required for design can be formed with high precision. It can be processed in a short time, which has the effect of improving productivity and reducing manufacturing costs.

[0018]

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating cam curved surface machining using a shaving die according to the present invention.

FIG. 2 is a flowchart showing the flow of steps for manufacturing a camshaft according to the present invention.

FIG. 3(a) is a perspective view showing the appearance of a cold-forged cam material.

FIG. 3(b) is a perspective view showing the appearance of the cam after being processed by the shaving die according to the present invention.

FIG. 4 is a perspective view showing the completed state of the camshaft.

[Explanation of symbols]

1 Cam material 1a Prepared hole 1b Reference hole 10 Cam 11 Shaving die 12 Reference pin 13 Dowel pin 14 Lower mold 20 Shaft 21 Journal

Claims (2)

[Claims] Claim 1: A process of forming a cam material into a designed cam shape by cutting a cam material from a bar, cold forging, heat treatment, and primary processing of the shape, and a process of forming a cam formed by this process into a shaft. In the method of manufacturing a camshaft, the step of forming the cam shape includes moving a shaving die on which a curved surface corresponding to the designed cam shape is formed in a direction parallel to the axis of the cam material. A method for manufacturing a camshaft, the method comprising a shaving step. 2. The method of manufacturing a camshaft according to claim 1, wherein the shaving step is performed with reference to the inner diameter of the insertion hole of the shaft for manufacturing one cam. 3. A camshaft manufacturing apparatus comprising: a shaving die formed with a curved surface corresponding to a designed cam shape; and means for moving the shaving die in a direction parallel to the axis of the cam material.