JPH03181653A - Manufacture of cam shaft - Google Patents

Abstract

PURPOSE:To prevent the bending caused by welding of a shaft member as excellent workability is kept by welding a cam member and the shaft member through high energy beam as a cam shaft material is rotated at high speed. CONSTITUTION:After a cam member 1 is fitted to a shaft member 2, the cam member 1 is set at a fixed position on the shaft member 2, and the cam member 1 and the shaft member 2 are welded through a high energy beam 4 as a cam shaft material 3 is rotated at high speed around its central axis. Thus, in order to heat the shaft member 2 slowly and uniformly over its whole circumference, a part to be welded is welded after its whole circumference is preheated about simultaneously and at similar rate. In addition to that, since the welded part is solidified at about similar rate over its whole circumference during a cooling process after welding, a local tensile stress is difficult to occur during its solidifying process, and the occurrence of bending of the shaft member 2 can therefore be controlled.

Description

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

(Prior art) As engines have become more multi-valve, camshafts with complex shapes have become required.As a method of manufacturing camshafts, cams obtained by forging or casting, which have been known in the past, have become necessary. Instead of machining the shaft material, as shown in Japanese Utility Model Application Publication No. 48-9805,
A method has been proposed in which a cam member having a hollow portion and a shaft member are separately provided, the cam member is fitted to the outer periphery of a shaft material, and then the cam member and the shaft member are welded.

(Problem to be Solved by the Invention) However, when welding the cam member and the shaft member, as shown in FIG. 2, the camshaft material C obtained by fitting the cam member a into the shaft member When welding is performed in the circumferential direction along the hollow part of cam member a while rotating around the central axis, that is, when welding is performed with the welding speed and the rotational speed of camshaft material C matching, As shown in FIG. 3, there is a problem in that the shaft member bends at the weld. Particularly, when a vibrator is used as a shaft member due to the recent demand for lighter engines, bending and deformation of the shaft member is significant.

In addition, when welding a cam member that has undergone surface hardening treatment such as carburizing and quenching to a shaft member, if the shaft member deforms,
There is a problem that the grinding allowance for the surface of the cam member becomes large and no hardened surface layer remains, or if an attempt is made to leave a hardened surface layer, unground portions are created and a predetermined shape cannot be obtained.

Therefore, the present inventor conducted measurements to find the relationship between the movement angle of the cam member a in the circumferential direction from the welding start position and the amount of displacement of the cam member a in the radial direction. The results are shown in Figure 4, and there is a substantially constant relationship between the movement angle in the circumferential direction from the welding start position and the reading of the dial gauge indicating the amount of displacement in the radial direction. A relationship was found that as the movement angle from the starting point in the left and right circumferential directions increases, the deviation amount increases, and that the deviation amount is largest at a portion moved by 180 degrees in the circumferential direction.

On the other hand, it is also considered to determine the welding start position for each cam member while measuring the direction of deviation, that is, the directionality of bending, but in this case, it takes time and effort to determine the welding start position. Poor workability.

Another option is to place multiple high-energy beams circumferentially around the welding area and slowly rotate the camshaft material around its central axis to offset the directionality of the bending caused by welding. , in this case the setting fi
In addition to being expensive, it takes time and effort to position the camshaft material, so the workability is poor.

An object of the present invention is to prevent bending of a shaft member due to welding by a method with good workability.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides welding by rotating a camshaft material obtained by fitting a cam member to a shaft member at high speed around its central axis. This heats the entire circumference of the area approximately evenly.

Specifically, the solution taken by the present invention is to obtain a camshaft material by fitting a hollow cam member around the outer periphery of a shaft member made of a vibrator, and then rotating the camshaft material around its central axis at high speed. The cam member and the shaft member are welded together using a high-energy beam while rotating.

(Function) With the above configuration, the cam member and shaft member are welded using a high-energy beam while the camshaft material is rotated around its central axis at high speed, so the welding location of the shaft member is repeatedly heated. Since the weld is heated gradually and uniformly over the entire circumference, the welded part is preheated to the same extent over the entire circumference, and then simultaneously melted and solidified. Therefore, local tensile stress is unlikely to occur in the welded portion of the shaft member.

(Example) An embodiment of the present invention will be described below with reference to FIG.

First, a cam member 1 is obtained by machining a material made of, for example, J Is-3l5-3C into a predetermined shape, and a shaft made of pipe is obtained by machining a material made of, for example, J I S-85-8TK into a predetermined shape. Obtain member 2.

Next, after fitting the cam member 1 to the shaft member 2, the cam member 1 is set at a predetermined position on the shaft member 2 to obtain a camshaft material 3.

Next, while rotating the camshaft material 3 around its central axis at high speed, the cam member 1 and the shaft member 2 are welded together using a high-energy beam 4 such as a laser beam or an electron beam.

In this way, the entire circumference of the shaft member 2 is heated gradually and uniformly, so that the welded portion is preheated substantially simultaneously and to the same extent over the entire circumference, and then melted. Also,
Even in the cooling process after welding, the welded part solidifies to the same extent over the entire circumference, so localized tensile stress is less likely to occur during solidification, and therefore the shaft member 2 is less likely to bend.

In the above case, the rotational speed of the camshaft material 3 is:
Camshaft material 3 is applied 10 to 5 times until welding is completed.
Preferably, it rotates about 0 times. The reason for this is that when the number of rotations is less than 10 times, there is a large difference in the start time of solidification depending on the position in the circumferential direction, causing bending in the shaft member 2. When the number of rotations exceeds 50 times, heat radiation is large. Therefore, even when heated by the high-energy beam 4, the welded portion is difficult to melt, and the high-energy beam 4 is required to have a large output, which impairs economic efficiency due to energy costs.

Next, a test for measuring the amount of bending of the shaft member 2 conducted to evaluate the present invention will be described.

For specific examples and comparative examples, J Is-9l5-9
A cam member 1 made of C and a journal member (not shown) were prepared. The chemical components of the cam member 1 and journal member in this case are C: 0.02%, Si: 0
．． 26%, Mn: 0°71%, Cr: 1.01%,
Mo: 0.26%, the balance was Fe.

Also, made of JIS-5-3TK 2, outer diameter: 2
A shaft member 2 having a diameter of 8 mm and an inner diameter of 20 mm was prepared.

In this case, the chemical composition of the shaft member 2 is C
:0.16%, Si:0.25%, Mn:0.42%
, the remainder was Fe.

Next, after fitting the cam member 1 to the shaft member 2,
The cam member 1 was set at a predetermined position on the shaft member 2 to obtain a camshaft material 3.

Next, as a specific example and a comparative example, welding was performed using a laser beam under the welding conditions shown in Table 1 above.

Table 2 The results are as shown in Table 2. The camshaft obtained in the comparative example had large bending deformation and the maximum value of runout was 0.025 to 0.038 mm, whereas the specific example The obtained camshaft had small bending deformation, and the maximum value of runout was 0.010 to 01015 mm, confirming the effect of the present invention.

Table 1 (Effects of the Invention) As explained above, according to the method for manufacturing a camshaft according to the present invention, the cam member and the shaft member are connected to each other by a high-energy beam while rotating the camshaft material at high speed around its central axis. Since the welded portion of the shaft member is simultaneously melted and solidified over the entire circumference, bending of the shaft member can be prevented.

[Brief explanation of drawings]

FIG. 1 is a side view showing a method for manufacturing a camshaft according to an embodiment of the present invention, FIGS. 2 to 4 show a conventional method for manufacturing a camshaft, and FIG. 2 is a cross-sectional view showing a welding process. 3 is a sectional view showing the state after welding, and FIG. 4 is a diagram showing the relationship between the angle from the welding start position and the reading of the dial gauge. 1...Cam member 2...Shaft member 3...Camshaft material 4...High energy beam and 2 others

Claims (1)

[Claims] (1) After fitting a hollow cam member to the outer periphery of a pipe shaft member to obtain a camshaft material, the camshaft material is rotated at high speed around its central axis while the cam member and shaft A method for manufacturing a camshaft, which comprises welding parts together using a high-energy beam.