JP3497766B2 - Sliding member - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member containing graphite as a lubricating substance, and more particularly to a sliding member having improved strength and sliding characteristics.

[0002]

Conventionally, as a sliding member that supports a moving object with low friction without using lubricating oil, a sintered alloy layer is deposited on a back metal formed of a thin steel plate. What is formed is known. The performance of this sliding member is mainly affected by the friction coefficient, wear resistance, strength, etc. of the sintered alloy layer formed on the backing metal. However, conventional sliding members have not been satisfactory in terms of friction coefficient, wear resistance and strength. Then, the objective of this invention is providing the sliding member excellent in sliding characteristics, such as strength, a friction coefficient, and abrasion resistance.

[0003]

According to a first aspect of the present invention, a backing metal is coated with a sintered alloy layer comprising 30 to 70% by weight of copper, 5 to 15% of graphite and the balance being nickel. , Said ware
The density ratio of the bonding gold layer is 80% or more, and the graphite is
50% or more of the whole is occupied by graphite powder having a size of 75 to 900 μm.

Nickel contributes to the improvement of the strength and wear resistance of the sintered alloy layer. Copper diffuses into the nickel component and contributes to the improvement of sliding characteristics. If it is less than 30%, sliding properties such as adhesion will be deteriorated, and if it exceeds 70%, the strength of the matrix will be deteriorated.

Graphite imparts self-lubricating properties to the sintered alloy layer and contributes to improvement of sliding characteristics such as friction coefficient and wear resistance. 5
If it is less than%, the friction coefficient becomes large, and the sliding characteristics are deteriorated such that the amount of wear is increased. Since the mechanical strength of graphite is very small, if it exceeds 15%, the strength of the sintered alloy layer will decrease.

[0006] By the way, conventionally, attention has been paid to the content of graphite to improve the sliding characteristics of the sintered alloy layer, and conventionally, graphite powder of about 50 μm or less is used. However, there was no particular consideration given to its size. The present inventor has determined that the size of the graphite powder affects the strength of the sintered alloy layer, and affects not only the strength but also the sliding characteristics.

That is, when the graphite powder is large, the strength of the sintered alloy layer increases. This is considered to be due to the following reasons. That is, when a tensile test is performed on the sintered alloy layer, cracks are formed so as to connect the graphite powder scattered in the matrix. This is because the mechanical strength of graphite is very weak, and cracks occur by connecting weak points. Therefore, the longer the distance between the graphite powders, the less likely the metal matrix is to crack and the more excellent the strength. And when comparing the sintered alloy layers containing the same weight% of graphite, the one using only large graphite powder has a smaller number of graphite powder than the one using only small graphite powder, It is considered that the larger graphite powder is used, the stronger the strength is because the intervals between the graphite powders scattered in the area become large.

If the size of graphite is less than 75 μm, the strength is hardly improved, and if it exceeds 900 μm, the strength is lowered. Further, if the graphite powder having a size of 75 μm to 900 μm is less than 50% of the whole graphite, improvement in strength cannot be expected.

On the other hand, since the strength of the sintered alloy layer is improved, that is, the wear resistance of the metal matrix is improved, the abrasive wear is less likely to occur. As a result, a strong graphite coating is formed on the sliding surface and the surface of the mating material, and sliding characteristics are improved, such as a reduction in the friction coefficient and a wear amount.

[0010] In the invention of claim 1, and the density ratio of the sintered alloy layer is 80% or more. When the density ratio is less than 80%, the strength of the sintered alloy layer is lowered and the wear amount is increased. This is because when the strength of the sintered alloy layer decreases, the copper matrix is easily broken and the surface of the sintered alloy layer becomes rough.
It is considered that it is easily worn.

The invention of claim 2 is characterized in that the sintered alloy layer contains one or both of tin 2 to 8% and phosphorus 0.1 to 1% by weight. is there. Tin contributes to the improvement of strength. Less than 2% has no effect,
If it exceeds 8%, a compound of copper-tin and nickel-tin is formed, which makes it brittle. Phosphorus forms compounds such as nickel-phosphorus and copper-phosphorus, and improves strength and wear resistance. If it is less than 0.1%, its effect is not obtained, and if it exceeds 2%, it becomes brittle.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4, the sliding member 1
Is formed by depositing a sintered alloy layer 4 on a backing metal 2 formed of, for example, a thin steel plate with an adhesive layer 3 interposed therebetween. The adhesive layer 3 is for firmly bonding the sintered alloy layer 4 to the backing metal 2, and is made of, for example, nickel or copper, or an alloy of nickel and copper.

The sintered alloy layer 4 has a weight ratio of copper 30 to 70.
%, Graphite 5 to 15%, tin 2 to 8%, phosphorus 0.1 to 1%, and the balance nickel. However, one or both of tin 2 to 8% and phosphorus 0.1 to 1% may be omitted.

Here, an example of a procedure for manufacturing the sliding member 1 having the above structure will be described. First, the back metal 2 made of thin steel plate
An adhesive layer 3 made of nickel or copper, or an alloy of nickel and copper is formed on the upper surface by electroplating, thermal spraying, etc.
Deposit to a thickness of 150 μm. The adhesive layer 3 may have a structure in which a thin plate made of nickel or copper or an alloy of nickel and copper is bonded onto the backing metal 2 by a pressure contact means.

On the other hand, nickel powder, copper powder, graphite powder,
Tin powder and phosphorus powder are mixed to obtain a mixed powder for forming the sintered alloy layer 4. To specifically describe the ratio of these components,
The copper component is 30 to 70% for improving sliding properties, the graphite component is 5 to 15% for improving sliding properties, the tin component is 2 to 8% for improving strength, and the phosphorus component is strong. In order to improve wear resistance, the content is set to 0.1 to 1%, and the balance is nickel for improving wear resistance and strength. The ratio of the components is shown by weight ratio (the same applies below).

Here, the graphite is such that powder having a size of 75 to 900 μm occupies 50% or more of the entire graphite.
In this case, the graphite may be spherical or lump-shaped, but scale-shaped or flat-shaped is preferable. In addition, the size showing the size of the graphite powder is a diameter in the case of a substantially circular shape,
In the case of an almost elliptical shape, it means the long diameter, in the shape of a scale, and in the flat shape, the length of a long part.

Such a mixed powder is evenly spread to a predetermined thickness on the backing metal 2 coated with the adhesive layer 3 and sintered in a reducing atmosphere at a temperature of 800 to 1000 ° C. for 10 to 30 minutes to obtain a powder. Sinter each other and bond to the back metal 2 to form the sintered alloy layer 4
To form. Then, the sintered alloy layer 4 is rolled by a roll to densify it and adjust its thickness.
Sintering at a temperature of 000 ° C. for 10 to 30 minutes and rolling with a roll are repeated. The sliding member 1 thus obtained had a total thickness of 8.8 mm, and the sintered alloy layer 4 had a thickness of 1.4 mm.

The above rolling is carried out so that the density ratio of the sintered alloy layer 4 finally becomes 80% or more. Here, due to the manufacturing method of sintering the powder in the sintered alloy layer 4, there are holes, but the density ratio means the theoretical density of the constituent components of the sintered alloy layer 4. The value obtained by dividing by the actual density of 4 is expressed as a percentage.

The inventors of the present invention conducted a sliding characteristic test for measuring the friction coefficient and the amount of wear and a strength test for measuring the tensile strength of the product of the present invention and the comparative product having the compositions shown in FIG. The result is shown in FIG. In the sliding characteristic test, the wear amount measurement test is a change in thickness when the mating material is reciprocated 10,000 times at a surface pressure of 1 MPa on the sintered alloy layer 4 as a wear amount. .

As can be seen from FIG. 1, the product of the present invention is
Compared to the comparative product, the friction coefficient is small overall and the amount of wear is small, and it has excellent sliding characteristics. Further, the product of the present invention has high tensile strength and is excellent in strength. The details will be described below.

(1) Ratio of Graphite First, the relationship between the ratio of graphite in the sintered alloy layer 4 and the sliding characteristics and strength will be examined. Comparing the product 4 of the present invention and the comparative product 2, the product 4 of the present invention has a wear amount of 10 μm, a friction coefficient of 0.18 and a tensile strength of 118 MPa, whereas the comparative product 2 has a wear amount of 25 μm and a friction coefficient of 0.2
5. The tensile strength is 52 MPa, and the product 4 of the present invention is superior in sliding characteristics and strength.

On the other hand, in the product 4 of the present invention and the comparative product 2, the proportions of nickel, copper, tin and phosphorus in the sintered alloy layer 4 and the proportion of the graphite powder having a size of 75 to 900 μm in the graphite are almost the same. In agreement, in the product 4 of the present invention, the proportion of graphite in the sintered alloy layer 4 is 10%, whereas in the comparative product 2, the proportion of graphite is as high as 20%. From this, it is understood that when the graphite content in the sintered alloy layer 4 is too large, the sliding characteristics and the strength are adversely affected.

Considering the range of the ratio of graphite in the sintered alloy layer 4, for example, in the product 1 of the present invention, the sintered alloy layer 4 contains graphite in a relatively large amount of 14%. The tensile strength of the product 1 is 92 MPa, which is the strength required for practical use. Further, in the products 6 and 7 of the present invention, the content of graphite in the sintered alloy layer 4 was relatively small at 5%, and therefore the tensile strength was as strong as 150 MPa and 122 MPa, and the sliding characteristics were Is also excellent. Comparative product 6 has a high tensile strength of 158 MPa, but is inferior in both friction coefficient and wear amount.

From the above, it can be said that the proportion of graphite in the sintered alloy layer 4 is preferably 5 to 15% by weight in terms of strength and sliding characteristics.

(2) Size of Graphite Powder In the present invention product 6 and the comparative products 3 and 4, the proportions of nickel, copper, tin, phosphorus and graphite in the sintered alloy layer 4 are almost the same,
The size of graphite is different. That is, in the product 6 of the present invention, the graphite powder having a size of 75 to 900 μm occupies 75% of the whole graphite, but in the comparative product 3, the graphite powder of 75 to 900 μm is not included, and the graphite as a whole is less than 75 μm. Yes,
In the comparative product 4, the entire graphite is occupied by the powder exceeding 900 μm.

Regarding the sliding characteristics, the product 6 of the present invention has a wear amount of 7 μm and a friction coefficient of 0.17, whereas the comparative product 3 has a wear amount of 15 μm, a friction coefficient of 0.22 and a comparison product 4.
The wear amount is 15 μm and the friction coefficient is 0.20, and the product 6 of the present invention exhibits superior sliding characteristics. Regarding the strength, the invention product 6 has a tensile strength of 150 MPa, while the comparative products 3 and 4 have a tensile strength of 71 MPa, respectively.
a, weak at 70 MPa. From this fact, when the graphite powder having a size of 75 to 900 μm is contained in the graphite in an appropriate amount,
It is understood that the strength is strong and the sliding characteristics are excellent.

On the other hand, when the tensile test of the sintered alloy layer 4 is carried out,
The break line is generated so as to connect the graphite powder scattered in the matrix. This is because graphite has a very low mechanical strength, and cracks occur by connecting weak points. Here, the total weight of graphite is the same,
Comparing the case where the individual graphite powder is large and the case where it is small,
When the graphite powder is large, as shown in FIG.
The number of graphite powders in the sintered alloy layer is small, and the distance between the graphite powders is long. On the contrary, when the graphite powder is small, as shown in FIG.
As shown in (b), the number of graphite powders in the sintered alloy layer is large, and the distance between the graphite powders is short. Therefore, if the graphite powder is large, the breaking line (shown by the broken line in FIG. 3) of the metal matrix when the sintered alloy layer breaks becomes long,
The strength is stronger.

The product 9 of the present invention and the comparative product 5 give suggestions as to how much the graphite powder of 75 to 900 μm is contained makes the sliding property and the strength excellent. The product 9 of the present invention contains graphite powder of 75 to 900 μm in an amount of 56% of the whole graphite. On the other hand, in the comparative product 5, the graphite powder of 75 to 900 μm was used as 42% of the total graphite.
It only contains%. As a result, although the other compositions are almost the same, the product 9 of the present invention is superior to the product 5 of the comparison in both sliding characteristics and strength. From this, 75-900
It can be said that a sliding member having excellent sliding characteristics and strength can be obtained when the graphite powder of μm is contained in 50% of the entire graphite.

(3) Density Ratio of Sintered Alloy Layer In the product 6 of the present invention and the comparative product 1, the compositions of the sintered alloy layer 4 are almost the same, but the density ratio of the sintered alloy layer 4 is different. The tensile strength of the product 6 of the present invention having a density ratio of 90% is 150 MPa, whereas the tensile strength of the comparative product 1 having a density ratio of 69% is only 90 MPa, and the strength of the product 6 of the present invention having a high density ratio is higher. Excellent. From another test result of the inventor, it was found that the strength of the sintered alloy layer 4 was improved when the density ratio was 80% or more.

(4) Relationship between Thickness and Strength of Adhesive Layer The performance of the sliding member 1 also depends on the adhesiveness between the backing metal 2 and the sintered alloy layer 4. To measure this adhesion,
The present inventor uses the sintered alloy 4 having the components shown in the present invention product 7 as the back metal 2
A shearing test was conducted to examine the bonding strength between the sintered alloy layer 4 and the backing metal 2 by changing the thickness of the adhesive layer 3 variously.

FIG. 2 shows the result of the shearing force test. From this test result, it is understood that if the thickness of the adhesive layer 3 is 5 μm or more, the shear value is 80 MPa or more, which is practically sufficient. When the thickness of the adhesive layer 3 is 150 μm or more, the shear value becomes almost constant regardless of the thickness of the adhesive layer 3. From this, the thickness of the adhesive layer 3 is 5 to 150 μm.
It is understood that it is good to do.

[Brief description of drawings]

FIG. 1 is a view showing an example of the present invention, showing a composition of a sintered alloy layer of a sliding member, a sliding characteristic, and a test result of tensile strength.

FIG. 2 is a diagram showing a result of a shear test of an adhesive layer.

FIG. 3 is a sectional view of a sintered alloy layer showing a fractured state.

FIG. 4 is a sectional view of a sliding member.

[Explanation of symbols]

In the figure, 1 is a sliding member, 2 is a back metal, 3 is an adhesive layer, and 4 is a sintered alloy layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Yamamoto, 2nd Sanagecho, Kita-ku, Nagoya City, Daido Metal Industry Co., Ltd. (72) Takayuki Shibayama, 2nd, Sanagecho, Kita-ku, Nagoya City Daido Metal Industry Co., Ltd. (56) References JP-A-3-232905 (JP, A) JP-A-1-198407 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22F 7/04 B22F 5 / 00

Claims (2)

(57) [Claims] 1. A backing metal is coated with a sintered alloy layer composed of 30 to 70% by weight of copper, 5 to 15% of graphite and the balance nickel, and the density ratio of the sintered alloy layer is: 80% or more
In addition, 50% or more of the graphite is 75 to 9
A sliding member characterized by being occupied by graphite powder having a size of 00 μm. 2. The sintered alloy layer comprises tin 2 to 8 in a weight ratio.
% And phosphorus 0.1 to 1%, or both
Claim 1 Symbol mounting slide member, characterized in that it contains.