JP2003221606A - Sliding parts and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce the frictional resistance and improve the durability, in a sliding member. <P>SOLUTION: These sliding parts are manufactured by means of charging raw powders 1 and 2 of iron-base and copper-base, respectively, into a charging part 16 of a forming die 11, pressurizing the raw powders 1 and 2 into a green compact 6, and sintering the green compact 6 into a bearing 5, wherein the copper-base raw powder 2 is a flat powder having a larger aspect ratio than that of the iron-base powder 1, and is segregated in a sliding face 51 side by vibration. The provided bearing 5 has the sliding face 51 covered with copper, and has an iron content increasing from the sliding face 15 toward the inside. When a rotating shaft slides on the sliding face 51 covered with the copper, the rotation is smooth, because coefficient of friction between the rotating shaft and the sliding surface 51 is low. Simultaneously, predetermined strength and durability can be provided by iron. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding component such as a bearing and a manufacturing method thereof.

[0002]

As a sliding component of this type, there is a bearing that supports a rotary shaft. As a method of manufacturing this bearing, a raw material powder containing a metal as a main raw material is compressed to form a green compact. Later, a sintered oil-impregnated bearing obtained by sintering this green compact is widely used.

The sintered oil-impregnated bearing is formed by using an iron-based or copper-based raw material powder, and if an iron-based raw material powder is used, a bearing excellent in strength can be obtained. When the same material is used for the bearing and the rotary shaft as described above, friction resistance becomes large, welding wear occurs, and durability is impaired. On the other hand, when the copper-based raw material powder is used, the frictional resistance between the bearing and the rotating shaft becomes extremely small, but the wear on the bearing side becomes large and the durability is impaired.

In this way, also in the sintered impregnated bearings, similar to general bearings, products capable of reducing frictional resistance and improving durability are being developed, and for example, iron plated with copper or copper alloy is used. A sintered oil-impregnated bearing using powder as a raw material powder is known. In this bearing, a structure in which copper and iron are mixed can reduce frictional resistance and improve durability as compared with the conventional one.

However, in recent years, in addition to the demands for wear and life of bearings, the demand for noise generation has increased, and for example, at a low temperature of -40 degrees,
Performance that does not generate noise at the time of starting is required, and it has been difficult for conventional products to meet this requirement.

[0006] Therefore, an object of the present invention is to provide a sliding component capable of reducing frictional resistance and improving durability and preventing generation of noise, and a manufacturing method thereof.

[0007]

A sliding part according to claim 1 is
In order to achieve the above-mentioned object, iron-based and copper-based raw material powders are filled in a filling portion of a molding die, the raw material powders are pressed to form a green compact, and the green compact is sintered. In the sliding component, the copper-based raw material powder is a flat powder having a larger aspect ratio than the iron-based raw material powder, and copper is segregated on the surface side.

A flat powder is used as the copper-based raw material powder, and the flat powder and the iron-based raw material powder are filled in a filling portion and vibration is applied, whereby the copper-based flat powder is segregated on the surface side and obtained. The surface of the sliding component is covered with copper, and a concentration gradient in which the proportion of copper decreases and the proportion of iron increases from the surface side toward the inside is formed.

Therefore, in the case where the bearing is composed of this sliding component, the rotating body slides on the surface side covered with copper, the coefficient of friction between the rotating shaft and the surface side is low, and smooth rotation becomes possible. At the same time, iron provides a predetermined strength and durability. Further, in this structure, even if the surface side on which the rotating body slides is worn, since copper is contained in a predetermined proportion below the surface side, the durability of the sliding portion is excellent.

According to a second aspect of the present invention, in the sliding member according to the first aspect, the surface copper coverage of the sliding portion is 60% or more.

As a result, the coefficient of friction of the sliding portion can be kept extremely low.

The invention of claim 3 is the same as claim 1 or 2
In the sintered part, the flat powder has an aspect ratio of 10
That is all.

By setting the aspect ratio of the flat powder to 10 or more, when vibration is applied, the flat powder is satisfactorily segregated on the surface side, and a sliding component having a high copper concentration on the surface side can be obtained.

According to a fourth aspect of the present invention, in the sintered component according to the second aspect, the ratio of the copper-based raw material powder is 20% of the whole.
Is about 70% by weight.

When the proportion of the copper-based raw material powder is less than 20% by weight, the proportion of copper on the surface side is lowered and the frictional resistance is increased, and when it exceeds 70% by weight, the proportion of the copper-based material as a whole is reduced. It increases, which is disadvantageous in terms of strength. Therefore, by adopting the above ratio, it is possible to reduce frictional resistance and obtain a sliding component excellent in strength.

In order to achieve the above object, in the method for manufacturing a sliding component according to a fifth aspect, iron-based and copper-based raw material powders are filled in a filling portion of a molding die, and the raw material powders are pressurized. In a method of manufacturing a sliding component formed by molding a green compact and sintering the green compact, a flat powder having an aspect ratio larger than that of the iron-based raw material powder is used for the copper-based raw material powder, and In this method, the copper-based raw material powder in the filling part is segregated on the surface side of the green compact.

By using this method, a sliding component having a low friction coefficient and excellent durability can be obtained.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 7 show an embodiment of the present invention.

First, the manufacturing method of the present invention will be described. The iron-based raw material powder 1 and the copper-based raw material powder 2 are mixed at a predetermined ratio (S1). As shown in FIG. 2, a substantially spherical irregularly shaped powder such as atomized powder is used as the iron-based raw material powder 1. On the other hand, as shown in FIG. 3, flat powder is used as the copper-based raw material powder 2, and the aspect ratio (diameter D /
The thickness T) is 10 or more, preferably 20-40. Further, as the copper-based raw material powder 2, a mixture containing copper powder as a main component and tin powder in an amount of 2 to 30% by weight can be used.

As shown in FIG. 4, the bearing 5 has a substantially cylindrical shape, and in the center thereof, a substantially cylindrical sliding surface 51 on which a rotating shaft (not shown), which is a rotating body, slides is formed. On both sides in the length direction of the sliding surface 51, which is the sliding portion, parallel and flat end surfaces 52,
53 is provided, and its outer peripheral surface 54 is formed in a cylindrical shape.

The mixed (S1) mixed iron-based and copper-based raw material powders 1 and 2 are filled in the filling portion 16 of the molding die 11.

FIG. 5 shows an example of the molding die 11. The molding die 11 has an up-down direction as an axial direction (press vertical axis direction), and includes a die 12, a core rod 13, a lower punch 14 and an upper punch 15. I have it. The die 12 has a substantially cylindrical shape, and a substantially cylindrical core rod 13 is coaxially positioned inside the die 12. The lower punch 14 has a substantially cylindrical shape, and is fitted between the die 12 and the core rod 13 so as to be vertically movable from below.
The upper punch 15 has a substantially cylindrical shape, and is fitted between the die 12 and the core rod 13 so as to be vertically movable and removable from above. And die 12, core rod 13 and lower punch
14, a filling portion 16 is formed between the inner peripheral surface of the die 12 and the outer peripheral surface 54, the upper surface of the lower punch 14 forms the end surface 53, the lower surface of the upper punch 15 is the The end surface 52 is formed, and the outer peripheral surface of the core rod 13 forms the sliding surface 51.

As shown in FIG. 5, the filling portion 16 is filled with the mixed iron-based and copper-based raw material powders 1 and 2, and the raw material powders 1 and 2 are vibrated (S2). In this case, the filling part
The upper part of the upper part 16 is closed by the upper punch 15, and the filling part 16 is vibrated with an acceleration of about 0.01 to 3 G without being pressed by the punches 14, 15. When subjected to vibration, the copper-based raw material powder 2 which is a flat powder segregates to the outside in the filling portion 16 and overlaps in the thickness direction, and the direction intersecting the thickness is aligned with the length direction on the surface side. After that, the raw material powders 1 and 2 in the filling portion 16 are pressed by the upper and lower punches 15 and 14 to form the green compact 6 (S3). This green compact 6
As shown in FIG. 6, the copper-based raw material powder 2 that is a flat powder gathers on the surface side, and the ratio of the iron-based raw material powder 1 increases toward the inside. By sintering (S4) the green compact, the bearing 5 which is a sintered product is formed.

As an example, the raw material powder 2 has an aspect ratio of 2
A flat powder of 0 to 40 is used, the ratio of the iron-based raw material powder 1 and the copper-based raw material powder 2 is set to 40:60 (weight ratio), and the filling portion 16 vibrates about 0.05 to 0.1 G. 0.5
After adding for 2 seconds, pressure was applied to form a green compact 6, and in the bearing 5 obtained by sintering this, the copper concentration was measured from the surface side.
As shown in FIG. 7, the copper concentration of the sliding surface 51 and the outer peripheral surface 54 of the bearing 5 is measured, and the copper concentration is measured at seven locations at equal intervals between the sliding surface 51 and the outer peripheral surface 54. did. Note that FIG.
Then, a cross mark was added to the measurement points, and the copper concentration at each measurement point is shown in the graph on the figure. In this way, by using the flat powder of the copper-based raw material powder 2 in an amount of 60% by weight or more, the surface side is
It turned out that it can be set to 00%. In this case, the surface copper coverage of the sliding surface 51 and the outer peripheral surface 54 is almost 100%.

The above-mentioned surface copper coverage is calculated by taking a color photograph of the surface (magnification x 100), overlaying a frame of tracing paper of a 2 mm grid that has been determined on the photograph, and calculating the area ratio of the copper part. To be done.

Further, the ratio of the iron-based raw material powder 1 and the copper-based raw material powder 2 was changed, and when 50:50, the surface copper coverage was about 9
0%, 60:40 the surface copper coverage is 80%, 70: 3
In 0, the surface copper coverage was 70%, and in 80:20, the surface copper coverage was 60%.

When the surface copper coverage of the sliding surface 51 is 100%, the friction resistance becomes the minimum, and no noise is observed in the test in which the rotating shaft is started at a temperature of -40 degrees. Up to about 90%, a similar effect was obtained. on the other hand,
Even if the surface copper coverage is 100%, copper-based raw material powder 2
When the proportion of exceeds 70% by weight, the strength decreases,
The proportion of copper-based raw material powder is 20 to 70% by weight of the whole raw material
And

As described above, in this embodiment, according to claim 1, the iron-based and copper-based raw material powders 1 and 2 are filled in the filling portion 16 of the molding die 11, and the raw material powders 1 and 2 are filled. In the bearing 5, which is a sliding component formed by pressurizing to form the green compact 6, and sintering the green compact 6, the copper-based raw material powder 2 is the iron-based raw material powder 1
Since the flat powder has a larger aspect ratio and copper is segregated on the sliding surface 51 side, which is the surface, the copper-based raw material powder 2 and the iron-based raw material powder 1 which are the flat powders are filled in the filling portion 16. By filling and vibrating, the copper-based flat powder segregates on the surface side, and in the obtained bearing 5, the surface side is covered with copper, and the ratio of copper is higher than that of iron from the surface side to the inside. Make a concentration gradient.

Therefore, a sliding surface which is a surface covered with copper
The rotating body slides on the 51, the friction coefficient between the rotating shaft and the sliding surface 51 is low, and smooth rotation is possible, and at the same time, predetermined strength and durability can be obtained by the iron. Further, in this structure, even if the sliding surface 51 on which the rotating body slides is worn, the sliding surface 51
Since copper is contained in the lower part in a predetermined ratio, the sliding part has excellent durability.

As described above, in this embodiment, the surface copper coverage of the sliding surface 51, which is the sliding portion, is 6 according to claim 2.
Since it is 0% or more, the friction coefficient of the sliding surface can be kept extremely low.

As described above, in this embodiment, since the aspect ratio of the flat powder is 10 or more in accordance with claim 3, when the vibration is applied, the flat powder segregates favorably on the surface side, The bearing 5 having a high copper concentration on the side can be obtained.

As described above, in the present embodiment, the proportion of the copper-based raw material powder 2 is 20 to 20% of the whole, corresponding to claim 4.
Since it is 70% by weight, the bearing 5 having both low frictional resistance and strength can be obtained.

As described above, in this embodiment, according to claim 5, the iron-based and copper-based raw material powders 1 and 2 are filled in the filling portion 16 of the molding die 11, and the raw material powders 1 and 2 are filled. In a method of manufacturing a bearing 5 which is a sliding component formed by pressurizing the green compact 6 and sintering the green compact 6, the copper-based raw material powder 2 has an aspect ratio larger than that of the iron-based raw material powder 1. Using a flat powder with a large ratio, the copper-based raw material powder 2 in the filling part 16 is pressed by vibration.
Since the segregation occurs on the surface side of 51, the bearing 5 that sinters the green compact 51 has a low friction coefficient and excellent durability.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, the flat powder includes a rod-shaped powder, and in this case, the aspect ratio is the ratio of length to diameter.

[0035]

In the sliding part according to the first aspect of the present invention, iron-based and copper-based raw material powders are filled in the filling portion of the molding die, and the raw material powders are pressed to form a green compact. In a sliding part formed by sintering a body, the copper-based raw material powder is a flat powder having a larger aspect ratio than the iron-based raw material powder, and copper is segregated on the surface side, and friction resistance It is possible to provide a sliding component that can reduce the number of components and improve the durability.

In addition to the effect of claim 1, the invention of claim 2 has a surface copper coverage of the sliding portion of 60% or more,
The friction coefficient of the sliding portion can be kept extremely low.

The invention of claim 3 is the same as claim 1 or 2.
In addition to the above effect, the flat powder has an aspect ratio of 10 or more, and when vibration is applied, the flat powder is well segregated on the surface side, and a sliding component having a high copper concentration on the surface side can be obtained.

In addition to the effect of claim 2, the invention of claim 4 is such that the ratio of the copper-based raw material powder is 20 to 7 of the whole.
Since it is 0% by weight, friction resistance can be reduced and a sliding component excellent in strength can be obtained.

According to a fifth aspect of the present invention, in the method for manufacturing a sliding component, iron-based and copper-based raw material powders are filled in a filling portion of a molding die, and the raw material powders are pressed to form a green compact. In a method for manufacturing a sliding component formed by sintering a green compact, a flat powder having an aspect ratio larger than that of the iron-based raw material powder is used as the copper-based raw material powder, and the copper-based raw material in the filling part is vibrated. This is a method in which powder is segregated on the surface side of the green compact, and a sliding component having a low friction coefficient and excellent durability can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a front view of the iron-based raw material powder.

FIG. 3 shows a copper-based raw material powder, FIG. 3 (A) is a side view, and FIG. 3 (B) is a front view.

FIG. 4 is a perspective view of the bearing.

FIG. 5 is a sectional view of the molding die of the above.

FIG. 6 is a sectional view of the green compact, showing a part of it in an enlarged manner.

FIG. 7 is a cross-sectional explanatory view of the bearing and a graph showing copper concentration.

[Explanation of symbols]

1 Iron-based raw material powder 2 Copper-based raw material powder (flat powder) 5 bearings 6 green compact 11 Mold 16 Filling section 51 Sliding surface (sliding part)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16C 33/14 F16C 33/14 A F term (reference) 3J011 SB02 SB03 SB19 4K018 AA04 AA29 BA02 BB01 CA05 CA14 HA03 KA03

Claims (5)

[Claims] 1. An iron-based and copper-based raw material powder is filled in a filling portion of a molding die, and the raw material powder is pressed to form a green compact,
In a sliding component formed by sintering this green compact, the copper-based raw material powder is a flat powder having an aspect ratio larger than that of the iron-based raw material powder, and copper is segregated on the surface side. And sliding parts. 2. The sliding component according to claim 1, wherein the surface copper coverage of the sliding portion is 60% or more. 3. The sliding component according to claim 1, wherein the flat powder has an aspect ratio of 10 or more. 4. The ratio of the copper-based raw material powder is 20% of the whole.
The sliding component according to claim 2, wherein the sliding component is about 70% by weight. 5. A slide obtained by filling an iron-based and copper-based raw material powder into a filling portion of a molding die, pressurizing the raw material powder to form a green compact, and sintering the green compact. In the method of manufacturing a moving part, a flat powder having a larger aspect ratio than the iron-based raw material powder is used for the copper-based raw material powder, and the copper-based raw material powder in the filling portion is oscillated on the surface side of the green compact. A method for manufacturing a sliding component, characterized by segregating.