JPS61288002A - Production of cam shaft - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce a cam shaft which is securely scorified by metallurgical joining with a shaft and sintered cam lobes by subjecting a steel shaft to a carburization treatment then assembling the sintered cam lobes thereto and sintering the same in a furnace. CONSTITUTION:The steel shaft 1 consisting of a carbon steel or alloy steel, etc. contg. carbon at a relatively low ratio is machined with journal parts 2 as necessary and is then subjected to the carburization treatment to form a carburized layer 11. The sintered cam lobes 3 are then assembled thereto and the assembly is sintered in the furnace. Diffusion is thereby induced from the sintered cam lobes 3 to form an alloy layer so that the joint parts between the shaft 1 and the sintered cam lobes 3 are securely scorified by the metallurgical joining. The cam shaft having the journal parts 2 which are highly resistant to wear is thus obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses a steel shaft that has been carburized in advance to strengthen the connection between the shaft and a sintered cam lobe (hereinafter referred to as sintering). The present invention relates to a method for manufacturing a camshaft in which the shaft is formed into a Ku shaft to improve the wear resistance of the journal portion when the shaft is used as a journal by cutting.

(Prior Art) In recent years, internal combustion engines are required to be lighter in weight from the viewpoint of energy conservation, and at the same time, higher speed and higher output are also required. Along with this, the camshaft also
Currently, there is a demand for camshafts that are lightweight, have excellent strength and wear resistance, and are also highly productive.

Conventional camshafts are relatively low-load monomer forged camshafts. However, as the performance of internal combustion engines improves, hardened or chilled cast iron camshafts, which have better wear resistance, are generally used. There is.

However, cast iron camshafts are generally heavy and not particularly strong, and furthermore,
When casting a large camshaft, bends and casting defects are likely to occur, and in addition, special techniques are required to control the chilled layer and quenching, which is often technically difficult to manufacture.

In order to improve strength and weight, the sliding parts of the camrozo etc. were made of sintered alloy, and the stem was made of steel pipe. That is, camshafts in which each member is made of different materials are known. For example, when assembling the camrozo to the stem, sinter the stem and camrozo in the following state,
- If the camshaft is defective in any of these places, the entire camshaft will become unusable. Furthermore, even if a sintered alloy is attempted to be joined to a steel stem by normal welding, weldability is poor. Furthermore, when brazing, there is no suitable brazing agent, and there are concerns about joining by brazing.

Furthermore, when cutting out a shaft and using it as a journal part, high carbon steel or alloy steel has conventionally been used as the shaft material in consideration of wear resistance. However, these materials not only have high material costs and are difficult to manufacture into shafts, but also have poor workability.

The cost was getting high.

(Means for Solving the Problems) In order to solve the above problems, the present invention carburizes a steel shaft, then assembles a sintered camrozo and sinters it in a heating furnace. It is not only possible to improve the seizing rate by strongly baking the shaft and sintered cam lobe through metallurgical bonding, but also to improve the wear resistance of the journal when the shaft is used as a journal by cutting. It is an object of the present invention to provide an improved method of manufacturing a camshaft.

In order to achieve the above object, the present invention has been developed to manufacture a powder alloy camshaft in which a sintered camrozo is baked onto a steel shaft, and a steel shaft having a journal portion formed by cutting in advance. After carburizing (tm), the shaft is assembled with a sintered camrozo and sintered in a heating furnace, so that the joint between the shaft and the sintered camrozo is firmly sintered by metallurgical bonding, and the shaft is When used as a journal by cutting, it is characterized by improving the wear resistance of the journal portion.

(Example) Hereinafter, an example of the manufacturing method of the present invention will be specifically described with reference to the drawings.

As shown in the figure, a steel shaft 1 is provided with a journal portion 2 formed in advance by cutting. The steel type of the shaft 1 used in the present invention is not particularly limited, but carbon steel or alloy steel with a relatively low carbon content, which is as cheap as possible and has good workability, is preferably used as long as it is allowed in terms of strength. Ruru.

In order to form the journal portion 2 on the shaft 1, it is first rough-machined by cutting, and then carburized. As a result, a low-cost journal portion 2 with excellent wear resistance can be completed by simply performing polishing after sintering. In addition, if the shaft has a small machining allowance, it can be used as it is as a journal part.

The steel shaft 1 is carburized using a sintered camrod 6 to form a carburized layer 11 on the surface and its vicinity, and is then assembled to the shaft 1.

The sintering of the sintered camrozo 6 and the carburized shaft is carried out in a heated furnace. 6) First, when the sintered camrozo 6 is inserted into a 1ft heating furnace, the sintered camrozo 6 with a high carbon content is inserted into the 1ft heating furnace. 3 to shaft 1 with low carbon content
The spread begins. Eventually, as the carbon concentration at the joint between the sintered camrozo 3 and the shaft 1 rises, a liquid phase is partially generated at the joint due to the high temperature inside the furnace, forming an alloy layer, and the sintered camrozo 3 and the shaft 1 are bonded together. is baked with a strong metallurgical bond. Therefore, as in the present invention, by performing carburizing treatment to a certain thickness on the surface layer of the shaft 10 in advance to form the carburized layer 11, the burning progresses quickly and stronger and more stable burning can be obtained. Node Ruru.

In the present invention, it goes without saying that the degree of carburizing treatment can be adjusted depending on the type of steel or its intended use. Moreover, the method of carburizing treatment is not particularly limited.

In the above embodiment, the description is based on an example in which the shaft is machined and used as a journal. Since the carburizing treatment was performed in advance, the sintering between the shaft and the sintered camrozo proceeded quickly in the heating furnace, and since the sintering was caused by metallurgical bonding, the sintering between the shaft and the sintered camrozo was prevented. It will become stronger.

Further, since the journal portion is formed by cutting the shaft in advance and then carburized, the wear resistance of the journal portion can be improved.

Furthermore, in the present invention, since carbon steel or alloy steel with a relatively low carbon content can be used for the shaft, the camshaft can be manufactured at low cost and easily.

[Brief explanation of the drawing]

FIG. 1 Fi is a partially cutaway vertical side view showing an embodiment of the camshaft manufacturing method of the present invention. In the figure. 1...Carburized powder alloy shaft% 11...
・Carburized layer, 2...Journal part, 3...Sintered Camrozo No.1! l! ! I

Claims (2)

[Claims] (1) In a camshaft formed by baking a sintered cam lobe onto a steel shaft, after carburizing the shaft,
A method for manufacturing a camshaft, characterized in that a sintered cam lobe is assembled and sintered in a furnace, and the joint between the shaft and the sintered cam lobe is firmly sintered by metallurgical bonding. (2) The method for manufacturing a camshaft according to claim 1, wherein the steel shaft is cut to form a journal portion, and then carburized.