JPS62271914A - Sintered cam shaft - Google Patents

Abstract

PURPOSE:To improve the workability and the wear and abrasion resistance of component material by specifying the components of sintered alloy such as C, P, S, Mn, Si, and Fe when making assembly pieces except a cam piece of the sintered alloy. CONSTITUTION:The components of sintered material for assembly pieces except a cam piece are specified as follows: C: 1.0-5.0%, P: 0.2-0.8%, S: 0.5% or less, Mn: 1.0% or less, Si: 2.0% or less, Fe as remainder in weight percentage. As the need arises, Mo: 0.1-2.0%, or separately from this, one component or more of Ni: 0.5-3.0%, Cr: 0.1-2.0%, B: 0.01-1.0%, Cu: 0.5-3.0% may be added to the said components. Thus, the assembly pieces made of the said sintered alloy can be improved in their wear and abrasion resistance, and also machinability.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a camshaft for an internal combustion engine, specifically a cam lobe and a journal piece that are both made of a sintered alloy and joined to a steel shaft. Regarding the camshaft.

[Prior Art] In a camshaft in which cam pieces, journal pieces, etc. are individually manufactured and joined to a steel shaft, most of the journals, gears, etc. other than the cam piece are manufactured from steel. However, while steel is relatively easy to finish, it requires many steps to join it to the shaft, such as FIO machining and brazing, which makes the manufacturing cost of this type of camshaft high. Ta.

Furthermore, when used as a sliding member, especially a journal, the problem of low wear resistance has often been encountered.

[Structure of the Invention] An object of the present invention is to provide a camshaft that can be manufactured at low cost and has good wear resistance,
This purpose is to assemble the assembly pieces other than the cam piece in terms of weight ratio: C: 1.0 to 5.0%, P: 0, 2 to 0.8%, S:
0.5% or less, Mn: 1.0% or less, Si: 2.0
% or less, the balance is Fe, or in addition to the above composition, Ho: 0.1 to 2.0%, and/or N
i: 0.5-3.0%, Cr2 0.1-2.0%, B
C0: 0.01 to 1.0% and C0: 0.5 to 3.0%.

In addition, this sintered alloy has good self-lubricating properties and machinability when carbide and graphite are distributed in the pearlite base structure.

The reasons for limiting the numerical values of each component in the assembly pieces other than the cam piece of the present invention are as follows.

When C is in the range of 0 to 5.0%, part of it dissolves in the base and strengthens the base, and the rest forms carbide or graphite with carbide, but if it is less than 1.0%, this effect cannot be obtained. Wear resistance and self-lubricating properties decrease. Moreover, if it exceeds 5.0%, the carbide becomes coarse and further interacts with P to generate an excessive liquid phase, making it impossible to maintain the shape of the assembly piece.

P produces Fe-C-P eutectic steadite and contributes to wear resistance, but if it is less than 0.2%, there is no addition effect;
If it exceeds 8%, the amount of precipitated steadite becomes excessive, resulting in poor rigidity and further embrittlement.

When S is distributed throughout the base in the form of S alone or )In3, it acts as a free-cutting component and improves machinability, but 0.
When it exceeds 5%, the strength decreases significantly and becomes brittle. It also hinders the progress of sintering.

The reason for keeping Mn below 1.0% is! -1n is 1.0%
If it exceeds this, the progress of sintering is suppressed, resulting in coarse pores remaining and powder formability also being reduced.

The reason for setting the Si content to 2.0% or less is that if the Si content exceeds 2.0%, the matrix becomes brittle, the compactability of the powder decreases, and deformation during sintering increases.

Depending on the sintering conditions, diffusion between particles may not follow during liquid phase sintering at high temperatures, resulting in wrinkles and cracks near the surface. Therefore, by adding l-1o in a range of 80.1 to 2.0%, diffusion can be aided and wrinkles and cracks can be prevented. This effect cannot be obtained at less than 0.1%, and 2.0%
%, the altitude increases due to the formation of Ho2G and the strengthening of the base, resulting in poor machinability.6Furthermore, Ni: 0
．． 5-3.0. Cr: 0.1-2.0%, B: 0
．． 01 to 1.0%, Cu: 0.5 to 3.0%, and may contain one or more of 0.5 to 3.0%, and these components may be added in appropriate amounts to parts used under conditions where wear occurs. By doing so, it is possible to strengthen the base and carbide. However, if each component falls below a limited range, there will be no addition effect, and if it exceeds the upper limit, hardness increases and machinability decreases.

This sintered alloy has C: 1.5-4.0%, P: 0.4-0
．． By selecting the sintering temperature and time within the range of 7%, a structure containing carbide and graphite simultaneously in the pearlite base can be obtained. As a result, like cast iron materials, the self-lubricating effect of graphite makes it a wear-resistant material that is less aggressive towards mating materials. In addition, machinability is also improved accordingly.

The sintered camshaft of the present invention is produced by compacting the sintered material and assembling it onto a steel shaft.
Sintering and joining is carried out at a temperature of 0.000'C, but in order to reduce manufacturing costs, it is necessary to join the assembly pieces under the same conditions. Therefore, as a sintered material for the cam piece, for example, a wear-resistant sintered alloy (C: 1.5%, s: 0.5~
1.2%, Nn: 1.0% or less, P: 0.2-0.
8%, Cr: 2.0-20%, )to: 0.5-2.5
%, Ni: 05-2.5%, balance Fe and impurities) or this sintered alloy is further supplemented with Sn, Bi, Sb.
, 0.01 to 5.0 of one or two or more of Co
It is preferable to use a wear-resistant sintered alloy containing %.

[Example] Hereinafter, the performance confirmation test results of the present invention will be explained based on Examples and Comparative Examples.

As shown in Table 1, as assembly pieces other than cam pieces,
Sintered alloy of the present invention having a composition of No. 1 to 9, No. 1
0.11 comparative sintered alloy, and no.

Twelve test specimens made of comparative steel material (30M440) were obtained. The sintered alloy was press-formed with a press surface pressure of 4 to 6 t/cm, then placed in a furnace in an ammonia decomposition gas atmosphere, and sintered at a temperature of 1050 to 1200'C (average 1120'C) for 1 to 2 hours. The steel used was one obtained through a sintering furnace under the same conditions as the sintered alloy described above.

1. Abrasion Test 1. The surface hardness of each sample material was measured and an Amsura set abrasion test was conducted. The test material is a rotating piece in a plane contact sliding wear tester, and these rotating pieces are brought into contact with a fixed piece of a flat sample (mate material) made of A1 alloy, and lubricating oil is constantly supplied to the contact surface. I rotated it.

The test conditions are as follows.

Rotating piece outer diameter...φ4Qmm, lubricating oil...10W-3
0, oil temperature -80'C1 oil! -0.5f/min, load...100KJf, sliding speed "-2.5m/SeC
, driving time...150 hours.

As shown in Table 1, the sintered alloy of the present invention, together with its counterpart material, showed a significant reduction in the amount of wear compared to the comparative material.

Single-chip life test - Process each sample material into a cylinder with a diameter of 48# and a thickness of 25#,
The tip life was measured by cutting with a lathe using a bite tip.

The test conditions are as follows.

Work rotation speed: 800 rpm, feed speed: 0.
32rev, storage allowance...1#, water-soluble cutting agent used.

A comparison was made of the number of times that a single tip can cut with a machining allowance of 11 runs, and as shown in Table 1, it was shown that the bite tip could be used for a significantly longer life when cutting the sintered alloy of the present invention. .

FIGS. 1 and 2 show microscopic photographs (nital liquid corrosion, 200x magnification) of sintered alloys as assembly pieces other than the cam piece of the present invention.

Figure 1 shows the sintered alloy with composition No. 2 in Table 1.
It is obtained by sintering at 0 to 1130'C for 1 to 1.5 hours, and contains network-like carbides (B) (cementite and steadite) that contribute to wear resistance in the pearlite base (A). Graphite (C) is distributed to improve machinability and lubricity.

Figure 2 shows the sintered alloy with the composition No. 1 in Table 1.
It was obtained by sintering at 0 to 1160'C for 1.2 to 1.7 hours, and network-like carbide (B) is distributed in the pearlite base (A).

[Effects of the Invention] As described above, the sintered camshaft of the present invention uses an assembly piece of a sintered alloy that can be joined to the shaft with -1 sintering process and has excellent wear resistance. This is a camshaft with excellent productivity, especially since the assembly pieces other than the cam piece are made of sintered alloy with good machinability.

[Brief explanation of drawings]

FIGS. 1 and 2 are photographs of the metallographic microstructure of a sintered alloy as an assembly piece other than the cam piece of the present invention.

Claims (4)

[Claims] (1) Assembly pieces other than the cam piece have a weight ratio of C:1
．． 0-5.0%, P: 0.2-0.8%, S: 0.5%
Hereinafter, a sintered camshaft formed of a sintered alloy containing Mn: 1.0% or less, Si: 2.0% or less, and the balance consisting of Fe. (2) Assembly pieces other than the cam piece have a weight ratio of C:1
．． 0-5.0%, P: 0.2-0.8%, S: 0.5%
Below, Mn: 1.0% or less, Si: 2.0% or less, Mo
:0.1 to 2.0%, and the balance is Fe. (3) Assembly pieces other than the cam piece have a weight ratio of C:1
．． 0-5.0%, P: 0.2-0.8%, S: 0.5%
The following contains Mn: 1.0% or less, Si: 2.0% or less, and further includes Ni: 0.5 to 3.0%, and Cr: 0.1 to
2.0%, B: 0.01-1.0%, Cu: 0.5-3
．． Contains one or more of 0%, and the remainder F
A sintered camshaft made of a sintered alloy made of e. (4) Assembly pieces other than the cam piece have a weight ratio of C:1
．． 0-5.0%, P: 0.2-0.8%, S: 0.5%
Below, Mn: 1.0% or less, Si: 2.0% or less, Mo
:0.1 to 2.0%, and further contains Ni:0.5 to 2.0%.
3.0%, Cr: 0.1-2.0%, B: 0.01-1
．． 0%, Cu: one or two of 0.5 to 3.0%
A sintered camshaft formed of a sintered alloy containing at least 100% of Fe, with the remainder being Fe.