JPS6043403A - Cam shaft consisting of sintered alloy - Google Patents

Abstract

PURPOSE:To provide a titled cam shaft by fitting and fixing a cam part consisting of a ferrous sintered body contg. an adequate ratio of cavity via a copper or copper alloy layer to a shaft part and heating the same thereby forming a copper or coper alloy impregnated layer. CONSTITUTION:A cam part 2 formed of a ferrous sintered material in such a way that cavity exist therein at 2-25% is fitted via copper or copper alloy 3 to the outside circumference of a shaft part 1 then said part is heated for prescribed time at about the temp. at which the copper or copper alloy 3 turns into a liquid phase thereby impregnating the copper or copper alloy 3 into the cam part 2. The assembly is then cooled, by which a joint part 4 is formed between the shaft part 1 and the cam part 2 and at the same time a copper or copper alloy impregnated layer 5 continuous therewith if formed. The cam shaft is obtained with which the cam part 2 is securely fixed to the shaft part 1, the cam part 2 wears less even under high surface pressure, at high temp. and in deteriorated oil and the attack to the mating member is lower.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a camshaft for an internal combustion engine, etc., in which a shaft portion and a cam portion are separated, the cam portion is made of a sintered body, and the cam portion is attached to the shaft portion 1. This relates to a camshaft that is fitted and fixed.

Recently, camshafts made of sintered bodies, which have been developed for the purpose of improving wear resistance, high temperature resistance, workability, etc., have been frequently used in camshafts for internally twisted isojings and the like. In this camshaft, a cam portion made of a sintered body made of metal powder is fitted and fixed to the outer periphery of a shaft portion made of, for example, 41.1 mm of chromium molybdenum.

In the camshaft having the above structure, the bottom cam part can be fixed to the shaft part by press-fitting the middle cam part into the shaft part. A method of generating a liquid phase from the aggregate and fixing it using this liquid phase.01D When a steel pipe is used as the shaft part, the part of the shaft part corresponding to the cam part is bulged out. The camshaft is fixed by being brought into pressure contact with the inner periphery of the cam portion.This is done by a method such as so-called bulge processing.With such a fixing structure, the camshaft has enough strength to withstand use.

By the way, in recent years, there has been a particular demand for higher speeds, higher outputs, energy savings, and more compact vehicles.As a result, camshafts, especially the cam portions, are subject to high surface pressure, high temperature, and deteriorated oil. In addition, there is a need to improve the strength of fixing the cam portion to the shaft portion.

The present inventors aimed to develop a camshaft in which the cam part is firmly fixed to the shaft part, the cam part has less wear due to high surface pressure, high temperature, and degraded oil, and is less likely to attack others. After repeated research, we came to the following findings.

As is well known, sintered bodies are produced by heating compacted metal powders, mixed powders, and alloy powders, and the solid (powder) particles form the same phase or partially form a liquid phase at a heating temperature lower than the melting temperature. It is made by mixing and bonding, and there are gaps (pores) between the bonded powders.
is formed, but the porosity (porosity) decreases with the progress of the bonding reaction (sintering). Silk (melting point: 1083°C) is used between the crystal (cam part) and the shaft part, which melts at a lower temperature than the cam and shaft parts, has high weldability, and forms alloys with many metals including iron. ) or copper alloy is interposed and heated to such an extent that the copper or copper alloy becomes a liquid phase, so that the copper or copper alloy in a liquid phase penetrates into the holes of the cam part, and just like that, The can or copper alloy is impregnated into the sintered body (cam part).

However, if the heating is stopped and the copper or copper alloy is continuously cooled, the copper or copper alloy in the liquid phase will solidify between the cam part and the Tsuchiba Yunjokoshaft part, and within the holes in the cam part connected to this. However, it has been found that this makes the fixation (joint) of the cam part to the shaft part very strong.

The present invention has been made based on the above findings. That is, the present invention places silk or copper alloy between or near the cam part (shaped and fired crystal) and the shaft part, and this
The copper alloy is heated for a predetermined period of time at a temperature that turns the copper alloy into a liquid phase, and then cooled to form the hook or the bonding layer made of the copper alloy between the cam part and the shaft part, and An impregnated layer is formed by infiltrating rust or copper alloy in a liquid phase into the borehole and solidifying it so that it is impregnated into the cam part.

The shaped sintered crystal (cam part) used in the present invention is produced by shaping an iron-based sintered material into a predetermined shape so that there are 0.2 to 25 voids. The reason why the proportion occupied by these holes is set to 0.2 to 25 inches is that when the holes are 0.2 mm deep, the can or copper alloy in the liquid phase will hardly seep into the cam part. This is because if the number of pores exceeds 25, the strength of the shaped and fired crystal (cam part) itself will decrease.

In addition, as brocade or copper alloy, Cu (non-toxic copper)
s cu-P (P; 7th section), Cn-A, g-guchi Z
11 (A, g: 2 (1, Zn: 35 '16),
Cu-Zn (Zn:40'F+ICl3-8yl
(Snj 20%), cu-N1 (Nt: 20
%).

Cu-Aff-Zn (Ag; 40%, Zn; 2
0%).

In manufacturing the sintered alloy camshaft according to the present invention,
As an example, first, as shown in FIG.
A cam portion 2 formed of iron-based sintered material with 0.2 to 25 holes is fitted on the outer periphery of the shaft portion 1, and a forceps or copper alloy 3 is inserted between the shaft portion 1 and the slope portion 2. Cover and heat. Then, the copper or copper alloy 3 becomes a liquid phase, and the copper or copper alloy in the liquid phase permeates into the holes of the cam part 2, as if the liquid phase state was in the cam part 2. mt or copper alloy 3 is impregnated. At this point, stop heating and allow to cool. When cooled, the copper or copper alloy 3 in a liquid phase solidifies between the cam portion 2 and the shaft portion 1 and within the hole of the cam portion 2 that is continuous thereto. As a result, as shown in FIG. 2, a bonding layer 4 is formed between the shirt portion 1 and the cam portion 2, and an impregnation @5 continuous to the bonding layer 4 is formed in the cam fiZ. be done. The above bonding layer 4
and shaft 1 are in a so-called brazed state and are firmly joined. On the other hand, this bonding layer 4 and the impregnated layer 5
The impregnated layer 5 and the cam portion 2 are integrally made of the same material, and the impregnated layer 5 and the cam portion 2 are intricately intertwined three-dimensionally.
A part of the bonding layer 4 is in a state of diffusion bonding with the implanted particles of the cam portion 2, and the bonding between the bonding layer 4 and the cam portion 2 is so strong that it is almost as if they were one piece. There is. Furthermore, the presence of the impregnated layer 5 improves the thermal conductivity of the cam portion 2, so that the wear resistance of the cam portion 2 is improved.

In addition, in the 1Bl manufacturing process, the amount of copper or copper alloy 3 and the heating time are adjusted to diffuse and infiltrate the copper or copper alloy 3 in a liquid phase from the shaft 1 side of the cam part 2 to the outer surface,
If the heating is stopped at this point, the impregnated layer 5 will be
It can be formed continuously from the shaft 1 side to the outer surface of the shaft. By configuring the impregnated layer 5 in this way, the iron or copper alloy is not present up to the worn surface of the cam part 2, and the conformability and anti-stick properties of the cam part 2 can be greatly improved. , thermal conductivity is further improved.

In the above configuration, the heating temperature does not need to be so high as to cause a liquid phase in the sintered body constituting the cam part 2, so that the implanted particles of the cam part 2 will not grow. Therefore, there is no fear that the dimensions of the cam portion 2 will be distorted due to heating.

In addition, in the above configuration, the cam part has been described as having already been formed and fired, but in addition to that, it is also possible to combine a calcined crystal or compacted product with the shaft part (8), and then heat it with copper or copper alloy. The cam portion may be fired at the same time as joining.

As explained above, in the camshaft according to the present invention, copper or a copper alloy is placed between or near the cam part made of a sintered body and the shirt Htt, and the temperature is such that the brocade or copper alloy becomes a liquid phase. is heated for a predetermined period of time, and then cooled to form a bonding layer made of the copper or copper alloy between the cam part and the shaft part, and brocade or copper alloy in a liquid phase in the hole of the cam part. It is made by impregnating it into the cam part and solidifying it to form an impregnated layer.
The cam part is firmly fixed to the shaft part, and there is little wear on the cam part even under high surface pressure, high temperature, and degraded oil, and the cam part is less susceptible to attack by opponents.

Next, the present invention will be explained in more detail with reference to Examples.

〔Example〕

As the sintered material for the cam part, Fe-Cr-MO-Mn-
Prepare atomized powder of (C+t)-(Nh) alloy, C powder, and F, -P (P; was prepared. 4 of these mixed powders
~710n/l, was molded into a predetermined shape (cam part/shape) with a 7.2mm diameter. 1000'D from these compacted products
(Example 7) and 1080" 0 to 1
Those sintered at 200°C (Examples 1 to 6.8 to 10) were manufactured.

On the other hand, the shaft part uses hollow steel with chromium molybdenum circles. The alignment of the shaft part and the cam part is achieved by forming a groove in the shaft part and forming a groove in the cam part as shown in FIG. A convex portion corresponding to the diameter of 1" was provided, and these grooves and convex portions were used.

The following three types of silk or copper alloy were used for joining, and these were combined with each cam part as shown in the figure.

(a) 99 purity Cu wire ←) Cu-N1 (Ni: 201) plate (c) Cu-zn (zn g 40 fy) plate The above combination Ω was heated in an ammonia-containing j9T gas at the temperature shown in the table. This was then added and joined together.

Comparative examples (conventional products) with the configurations shown in the table above were manufactured for the camshafts of Examples 1 to 100 manufactured as described above, and the appearance of each was checked. In Comparative Example 1, 30 beam bodies were Of these, 5 are made of genuine leather, and Comparative Example 2
In contrast, 7 out of 30 test specimens were made of leather.
There were no problems in the Examples.

Further, Example 8 and Comparative Example 1 were incorporated into a diesel engine, and the engine was operated for 20 (+Or, p, rn, 400 hr).

When a wear test was carried out in degraded oil, the cam wear of Comparative Example 1 was 120 μm once a time, and the arm wear was 130 μm.
In contrast, in Example 8, the cam wear was 2.
Good results were obtained with rocker arm wear of 0 μm and rocker arm wear of 40 μm.

[Brief explanation of the drawing]

1 and 2 are for explaining the present invention,
Figure 1 is a cross-sectional diagram of the camshaft before impregnation bonding, Figure 2
The figure is a cross-sectional configuration diagram of the camshaft after impregnation bonding. 1...Shaft 1ils, 2...Cam part, 3...Inertia or copper alloy, 4...Joining layer, 5...Impregnation layer. Figure 1 - Figure 1

Claims (1)

[Claims] In a camshaft in which a cam part made of sintered @ is fitted and fixed to the outer periphery of the shaft part, the cam part has a hole of 0.2 to
A bonding layer made of copper or copper alloy is formed between the cam portion and the shaft portion, and the bonding layer is formed on at least a portion of the cam portion. A sintered alloy camshaft characterized by forming continuous copper or copper alloy impregnated layers.