JPH06158242A - Valve guide member made of fe base sintered alloy excellent in wear resistance - Google Patents

Abstract

PURPOSE:To provide a valve guide member made of an Fe base sintered alloy excellent in wear resistance. CONSTITUTION:The valve guide member of an internal combustion engine has a compsn. contg., by weight, 1 to 4% C, 1.5 to 6% Cu, 0.1 to 0.8% P, 0.1 to 4% Ni and 0.05 to 2% Mo and furthermore contg., at need, 0.2 to 4% Mn and 0.05 to 1% S, and the balance Fe with inevitable impurities. Moreover, it is constituted of an Fe base sintered alloy having a structure in which, in a matrix essentially consisting of pearlite, hard Fe-C-P compounds, carbides and free graphite and, according to necessary, MnS are dispersedly distributed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe-based sintered alloy valve guide member for an internal combustion engine that exhibits excellent wear resistance.

[0002]

2. Description of the Related Art It is well known that many Fe-based sintered alloys have been conventionally applied to the manufacture of valve guide members for internal combustion engines.

[0003]

On the other hand, in recent years, the high output and high speed of internal combustion engines have been remarkable, and along with this,
The usage conditions of these structural members become even more severe, and especially for valve guide members that are subject to severe sliding wear with the valve stem that is inserted into the center hole and reciprocates, the wear resistance is further improved. Is required, but many conventional Fe
The valve guide member made of a base sintered alloy does not exhibit sufficient wear resistance to cope with this, and development of a valve guide member that stably exhibits excellent wear resistance is desired.

[0004]

Therefore, the present inventors have
From the above viewpoints, as a result of research to develop a valve guide member made of an Fe-based sintered alloy having excellent wear resistance, the valve guide member of an internal combustion engine is expressed in weight% (hereinafter,
% Represents% by weight), C: 1 to 4%, Cu:
1.5-6%, P: 0.1-0.8%, Ni: 0.1
4%, Mo: 0.05 to 2%, and if necessary, Mn: 0.2 to 4%, S: 0.05 to 1%,
Containing Fe and the balance consisting of Fe and unavoidable impurities, and a base material mainly composed of pearlite, hard Fe-C-
When the P-based compound, the carbide, and the free graphite are dispersed and distributed, and when Mn and S are additionally contained, manganese sulfide (hereinafter referred to as MnS) is dispersed and distributed in the Fe-based sintered alloy. The resulting Fe-based sintered alloy valve guide member is a hard Fe-dispersed material.
The research results show that excellent wear resistance can be exhibited by improving the hardness by the C-P compound and the carbide, and by improving the self-lubricating property by the free graphite similarly dispersed in the matrix and MnS. .

The present invention has been made based on the above-mentioned research results. C: 1 to 4%, Cu:
1.5-6%, P: 0.1-0.8%, Ni: 0.1
4%, Mo: 0.05 to 2%, and if necessary, Mn: 0.2 to 4%, S: 0.05 to 1
%, With the balance consisting of Fe and unavoidable impurities, and a base body mainly composed of pearlite, and hard Fe.
A valve made of an Fe-based sintered alloy having excellent wear resistance, which is composed of a Fe-based sintered alloy having a structure in which a -CP compound, a carbide, free graphite, and optionally MnS are dispersed and distributed. It is characterized by the guide member.

Next, the reason why the composition of the Fe-based sintered alloy composing the valve guide member of the present invention is limited as described above will be explained. (A) In the CC component, pearlite of the base material is formed and strengthened, and a hard Fe-C-P-based compound and a carbide are formed to improve the hardness, and the base material is also used as free graphite. Has an effect of improving self-lubricating property and thus improving the wear resistance of the member, but if the content is less than 1%, the desired effect of the above effect cannot be obtained, while the content is If it exceeds 4%, it becomes brittle and the desired strength cannot be obtained. Therefore, the content is defined as 1 to 4%.

(B) Cu The Cu component has a function of forming a solid solution in the matrix to strengthen it and stabilize the pearlite matrix, but if the content thereof is less than 1.5%, it is desirable for the above-mentioned effect. However, even if the content exceeds 6%, no further improvement effect is obtained due to the above-mentioned action, and rather the material becomes brittle, so the content is 1.5-6. Defined as%.

(C) The P P component not only improves the sinterability and thus contributes to the strength improvement, but also has the action of forming a Fe--C--P compound as described above to improve the wear resistance. However, its content is 0.
If it is less than 1%, the desired effect cannot be obtained, while if its content exceeds 0.8%, the base material is excessively hardened and coarse Fe—C—P-based compounds are precipitated. As a result, the machinability is significantly deteriorated, so the content is set to 0.
It was set at 1 to 0.8%.

(D) Ni The Ni component has a function of forming a solid solution in the base material to improve the corrosion resistance in the heating atmosphere to which the member is exposed, but if the content thereof is less than 0.1%, the above-mentioned function is exerted. If the desired improvement effect cannot be obtained and the content exceeds 4%, the austenite phase will remain and the wear resistance will decrease, so the content was defined as 0.1-4. .

(E) Mo Mo The Mo component is solid-solved in the base material to strengthen it, and
Although it has the effect of forming carbides to improve the hardness, if the content is less than 0.05%, the desired improvement effect cannot be obtained, while if the content exceeds 2%, machinability is increased. The content of 0.05-
It was set at 2%.

(F) Mn and S Both of these components are present mainly as MnS dispersedly distributed in the base material to enhance self-lubricating property, thereby contributing to the improvement of wear resistance of the member and the action of improving machinability. However, if the content of Mn is less than 0.2% and the content of S is less than 0.05%, a slight solid solution in the matrix is unavoidable. Of less than 0.2%, the desired effect cannot be obtained in the above-mentioned action, while the content of each is Mn: 4%.
If the content of S and S exceeds 1%, the distribution ratio of MnS becomes too large, and as a result, the strength of the member decreases. Therefore, the content of Mn is 0.2 to 4% and S:
It was set at 0.05 to 1%.

[0012]

EXAMPLES Next, the valve guide member of the present invention will be specifically described by way of examples. As raw material powder, particle size:-
80mesh Fe powder, same-150mesh carbon powder, same-
Cu powder of 100 mesh, Fe-27% of -150 mesh
P alloy powder, Cu-8% P alloy powder of the same -200 mesh,
All have various particle sizes of -100 mesh, and various atomized Fe-Ni- with various contents of Ni and Mo.
Mo alloy powder and -150 mesh MnS powder were prepared, these raw material powders were compounded to the compounding compositions shown in Tables 1 and 2, and 1% zinc stearate was added and mixed in a V-type mixer for 30 minutes. After that, the green compact was press-molded at a pressure of 6 ton / cm ² , and the green compact was kept at a temperature of 650 ° C. for 20 minutes in an atmosphere of decomposition gas of natural gas for degreasing, and subsequently 1050 to 1150. By raising the temperature to a predetermined temperature within the range of ℃, holding the temperature for 60 minutes to sinter, and performing finish cutting after sintering, it has substantially the same composition as the composition and at the same time, pearlite. A hard Fe—C—P-based compound, a carbide, and free graphite are dispersed and distributed in a base material mainly composed of
It is composed of a Fe-based sintered alloy having a structure in which nS is dispersed and distributed, and has a length of 50 mm, an outer diameter of 12 mm, and an inner diameter of 6.6.
Fe-based sintered alloy valve guide member of the present invention having a dimension of mm (hereinafter referred to as the present invention sintered valve guide) 1-1.
1 and a comparative Fe-based sintered alloy valve guide member composed of an Fe-based sintered alloy having a content of one of the constituents (marked with * in Table 2) outside the scope of the present invention. 1 to 5 (hereinafter, referred to as comparative sintering valve guides) were manufactured.

[0013]

[Table 1]

[0014]

[Table 2]

Then, various sintered valve guides obtained as a result were press-fitted and attached to an Al cast cylinder head of a DOHC type engine having a displacement of 2000 cc, unleaded gasoline was used as a fuel, and a rotation speed was 6200 rpm. 30
An actual machine test of 0 hour operation was performed to measure the inner diameter at the inner surface position of 5 mm in the longitudinal direction from the edge on the valve seat side, and the change in inner diameter after the test with respect to the inner diameter before the test was measured as the wear amount. The measurement results are shown in Tables 1 and 2.

[0016]

From the results shown in Tables 1 and 2, all of the sintered valve guides 1 to 11 of the present invention show excellent wear resistance in spite of extremely high speed and continuous operation for a long time. On the other hand, as can be seen in the comparative sintered valve guides 1 to 5, it is desirable that the content of any one of the constituent components of the Fe-based sintered alloy forming the guide is out of the range of the present invention. It is clear that excellent wear resistance cannot be ensured. As described above, the Fe-based sintered alloy valve guide member of the present invention exhibits excellent wear resistance even when used under severe conditions, and can sufficiently cope with higher performance and higher speed of the internal combustion engine. It has characteristics.

Claims (2)

[Claims] 1. By weight%, C: 1 to 4%, Cu: 1.5 to 6%, P: 0.1 to 0.8%, Ni: 0.1 to 4%, Mo: 0.05 2% by weight, the balance being Fe and unavoidable impurities, and a base material mainly composed of pearlite, and hard Fe-C-
A valve guide member made of an Fe-based sintered alloy having excellent wear resistance, characterized by being composed of an Fe-based sintered alloy having a structure in which a P-based compound, a carbide and free graphite are dispersed and distributed. 2. C: 1-4% by weight, Cu: 1.5-6%, P: 0.1-0.8%, Ni: 0.1-4%, Mo: 0.05- 2%, Mn: 0.2 to 4%, S: 0.05 to 1%, with the balance consisting of Fe and unavoidable impurities, and a base body mainly composed of pearlite, and a hard Fe-C-
A valve guide member made of an Fe-based sintered alloy having excellent wear resistance, which is composed of an Fe-based sintered alloy having a structure in which a P-based compound, a carbide, free graphite, and manganese sulfide are dispersed and distributed.