JP3873275B2 - Sliding parts and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sliding component such as a bearing and a manufacturing method thereof.
[0002]
[Problems to be solved by the invention]
As this type of sliding parts, there is a bearing that supports a rotating shaft. As a manufacturing method of this bearing, after compressing raw material powder mainly made of metal to form a green compact, this green compact is sintered. Sintered oil-impregnated bearings are widely used.
[0003]
The sintered oil-impregnated bearing is formed using iron-based or copper-based raw material powder, and if iron-based raw material powder is used, a bearing excellent in strength can be obtained. If a material is used, and the same type of material is used for the bearing and the rotating shaft in this way, the frictional resistance becomes large, causing welding wear and impairing durability. On the other hand, if 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.
[0004]
Thus, in the case of sintered impregnated bearings, as in general bearings, products that can reduce frictional resistance and improve durability are being developed. For example, iron powder plated with copper or copper alloy is used as a raw material. A sintered oil-impregnated bearing used for powder is known, and in this bearing, a structure in which copper and iron are mixed reduces frictional resistance and improves durability compared to the conventional one.
[0005]
However, in recent years, in bearings and the like, in addition to requirements related to wear and life, there has been a further increase in the demand for noise generation. So, it was difficult to meet this demand.
[0006]
Therefore, an object of the present invention is to provide a sliding component capable of reducing frictional resistance and improving durability and preventing noise from being generated, and a manufacturing method thereof.
[0007]
[Means for Solving the Problems]
In order to achieve the object, the sliding component of claim 1 fills the filling portion of the molding die with iron-based and copper-based raw material powder, presses the raw material powder to form a green compact, In the sliding part formed by sintering the 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 from the surface side to the inside. The ratio of copper decreases and the ratio of iron increases .
[0008]
Using flat powder as the copper-based raw material powder, filling this flat powder and iron-based raw material powder into the filling part and applying vibration, the copper-based flat powder segregates on the surface side, and the resulting sliding The part has a concentration gradient in which the surface side is covered with copper and the ratio of copper decreases and the ratio of iron increases from the surface side toward the inside.
[0009]
Therefore, when a bearing is constituted by 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 is possible. Thus, predetermined strength and durability can be obtained. Further, in this structure, even if the surface side on which the rotating body slides is worn, copper is contained at a predetermined ratio below the surface side, so that the durability of the sliding portion is excellent.
[0010]
The invention of claim 2 is the sliding portion article of claim 1, the surface of copper coverage of the sliding part is 60% or more.
[0011]
Thereby, the friction coefficient of a sliding part can be suppressed very low.
[0012]
According to a third aspect of the present invention, in the sliding component of the first or second aspect, the flat powder has an aspect ratio of 10 or more.
[0013]
By making the aspect ratio of the flat powder 10 or more, 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 is obtained.
[0014]
According to a fourth aspect of the present invention, in the sliding component of the second aspect, the ratio of the copper-based raw material powder is 20 to 70% by weight.
[0015]
When the proportion of the copper-based raw material powder is less than 20% by weight, the proportion of copper on the surface side decreases, the frictional resistance increases, and when it exceeds 70% by weight, the proportion of the copper-based material as a whole increases. It is disadvantageous in strength. Therefore, by adopting the above ratio, it is possible to obtain a sliding component having reduced frictional resistance and excellent strength.
[0016]
In order to achieve the object, the sliding part manufacturing method according to claim 5 fills a filling part of a molding die with iron-based and copper-based raw material powder, pressurizes the raw material powder, and compacts the green compact. In the method for manufacturing a sliding part formed by sintering the 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 vibration is generated in the filling portion. The copper-based raw material powder is segregated on the surface side of the green compact.
[0017]
By using this method, a sliding component having a low friction coefficient and excellent durability can be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
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.
[0019]
First, the production 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 for the iron-based raw material powder 1. On the other hand, as shown in FIG. 3, flat powder is used for the copper-based raw material powder 2, and the aspect ratio (diameter D / thickness T) of the flat powder is 10 or more, preferably 20 to 40. Moreover, as the copper-based raw material powder 2, a powder mainly composed of copper powder and 2 to 30% by weight of tin powder can be used.
[0020]
As shown in FIG. 4, the bearing 5 has a substantially cylindrical shape, and a substantially cylindrical sliding surface 51 on which a rotating shaft (not shown) as a rotating body rotates and slides is formed at the center. Parallel and flat end surfaces 52 and 53 are provided on both sides in the length direction of the sliding surface 51, and the outer peripheral surface 54 is formed in a cylindrical shape.
[0021]
The mixed (S 1) iron-based and copper-based raw material powders 1 and 2 are filled in the filling portion 16 of the molding die 11.
[0022]
FIG. 5 shows an example of the molding die 11. The molding die 11 has an up-down direction as an axial direction (press up-down axis direction), and includes a die 12, a core rod 13, a lower punch 14, and an upper punch 15. . The die 12 has a substantially cylindrical shape, and a substantially cylindrical core rod 13 is coaxially positioned in 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 movable up and down from above and detachably. A filling portion 16 is formed between the die 12, the core rod 13, and the lower punch 14. The inner peripheral surface of the die 12 forms the outer peripheral surface 54, and the upper surface of the lower punch 14 forms the end surface 53. The lower surface of the upper punch 15 forms the end surface 52, and the outer peripheral surface of the core rod 13 forms the sliding surface 51.
[0023]
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 vibrations (S2) are applied to these raw material powders 1 and 2. In this case, the upper portion of the filling portion 16 is closed by the upper punch 15 and the filling portion 16 is vibrated at an acceleration of about 0.01 to 3 G without being pressurized by the punches 14 and 15. When subjected to vibration, the copper-based raw material powder 2 that is a flat powder segregates outside the filling portion 16, overlaps in the thickness direction, and matches the direction intersecting the thickness with the length direction on the surface side. After that, the green compact 6 is formed (S3) by pressurizing the raw material powders 1 and 2 in the filling portion 16 with the upper and lower punches 15 and 14. As shown in FIG. 6, the green compact 6 has a copper-based raw material powder 2 which is a flat powder gathered on the surface side, and the ratio of the iron-based raw material powder 1 increases toward the inside. The sintered compact 5 is formed by sintering (S4) the green compact.
[0024]
As an example, a flat powder having an aspect ratio of 20 to 40 is used as the raw material powder 2 and the ratio of the iron-based raw material powder 1 and the copper-based raw material powder 2 is 40:60 (weight ratio). After applying vibration of about 0.05 to 0.1 G for 0.5 seconds, the green compact 6 was formed by pressurization, and in the sintered bearing 5, 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 points that are equally spaced between the sliding surface 51 and the outer peripheral surface 54. did. In FIG. 7, the measurement locations are marked with x, and the copper concentration at each measurement location is shown in the graph on the drawing. Thus, it turned out that the surface side can be made into 100% of copper by using 60 weight% or more of flat powder of the copper-type raw material powder 2. FIG. In this case, the surface copper coverage of the sliding surface 51 and the outer peripheral surface 54 is almost 100%.
[0025]
The surface copper coverage is calculated by taking a color photograph of the surface (magnification × 100), overlaying a frame of a predetermined 2 mm square trace paper on the photograph, and calculating the area ratio of the copper part.
[0026]
Further, the ratio of the iron-based raw material powder 1 and the copper-based raw material powder 2 is changed, so that the surface copper coverage is about 90% at 50:50, the surface copper coverage is 80% at 60:40, and at 70:30. When the surface copper coverage was 70% and 80:20, the surface copper coverage was 60%.
[0027]
In the test where the surface copper coverage of the sliding surface 51 is 100%, the frictional resistance is the lowest, and the rotating shaft is started at a temperature of -40 degrees, no noise is observed, and the surface copper coverage is 90%. A similar effect was obtained to the extent. On the other hand, even if the surface copper coverage is 100%, if the proportion of the copper-based raw material powder 2 exceeds 70% by weight, the strength decreases, so the proportion of the copper-based raw material powder is 20 to 70 of the entire raw material. % By weight.
[0028]
Thus, in this embodiment, corresponding 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 pressurized. In the bearing 5 which is a sliding part formed by molding the green compact 6 and sintering the green compact 6, the copper-based raw material powder 2 is a flat powder having a larger aspect ratio than the iron-based raw material powder 1. Copper segregates on the sliding surface 51 side, which is the surface, and the ratio of copper decreases from the surface side to the inside and the ratio of iron increases . By filling the raw material powder 1 in the filling portion 16 and applying vibration, the copper-based flat powder segregates on the surface side, and the obtained bearing 5 is covered with copper on the surface side, and is directed from the surface side to the inside. Concentration gradient in which the ratio of iron is higher than copper .
[0029]
Therefore, the rotating body slides on the sliding surface 51 which is the surface covered with copper, the friction coefficient between the rotating shaft and the sliding surface 51 is low, and smooth rotation is possible, and at the same time, the iron has a predetermined strength and durability. Sex can be obtained. In this structure, even if the sliding surface 51 on which the rotating body slides is worn, copper is contained under the sliding surface 51 at a predetermined ratio, so the durability of the sliding portion is excellent. It will be.
[0030]
As described above, in this embodiment, corresponding to claim 2, the surface copper coverage of the sliding surface 51 as the sliding portion is 60% or more, so that the friction coefficient of the sliding surface is extremely low. Can do.
[0031]
As described above, in this embodiment, the aspect ratio of the flat powder is 10 or more, corresponding to claim 3, so that when the vibration is applied, the flat powder is well segregated on the surface side, and the copper on the surface side A bearing 5 having a high concentration can be obtained.
[0032]
In this way, in this embodiment, since the ratio of the copper-based raw material powder 2 is 20 to 70% by weight of the whole, corresponding to claim 4, the bearing 5 having both low frictional resistance and strength is provided. Obtainable.
[0033]
Thus, in this embodiment, corresponding 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 pressurized. In the manufacturing method of the bearing 5 that is a sliding part formed by forming the green compact 6 and sintering the green compact 6, the copper-based raw material powder 2 has a larger aspect ratio than the iron-based raw material powder 1. Since flat powder is used and the copper-based raw material powder 2 in the filling portion 16 is segregated on the surface side of the green compact 51 by vibration, the bearing 5 for sintering the green compact 51 has a low friction coefficient and durability. Excellent in properties.
[0034]
In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible. For example, the flat powder includes a rod-shaped powder, and in this case, the ratio of length to diameter is the aspect ratio.
[0035]
【The invention's effect】
In the sliding part of claim 1, the raw material powders of iron and copper are filled in the filling part of the molding die, the raw material powder is pressed to form a green compact, and the green compact is sintered. The copper-based raw material powder is a flat powder having a larger aspect ratio than the iron-based raw material powder, copper is segregated on the surface side, and the proportion of copper is low from the surface side toward the inside. At the same time, the ratio of iron increases , and frictional resistance can be reduced and durability can be improved, and a sliding component can be provided.
[0036]
In addition to the effect of the first aspect, the invention of claim 2 has a surface copper coverage of 60% or more at the sliding portion, and the friction coefficient of the sliding portion can be kept extremely low.
[0037]
In addition to the effect of the first or second aspect, the invention of claim 3 has an aspect ratio of the flat powder of 10 or more. When vibration is applied, the flat powder is well segregated on the surface side. A sliding part having a high copper concentration can be obtained.
[0038]
In addition to the effect of claim 2, the invention of claim 4 is characterized in that the ratio of the copper-based raw material powder is 20 to 70% by weight of the whole, reducing frictional resistance, and having excellent strength. A moving part can be obtained.
[0039]
According to a fifth aspect of the present invention, there is provided a sliding part manufacturing method comprising filling a filling portion of a molding die with iron-based and copper-based raw material powder, pressurizing the raw material powder to form a green compact, and forming the green compact. In the manufacturing method of the sliding part formed by sintering, 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 the copper-based raw material powder in the filling portion is vibrated by vibration. This is a method of segregating 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 the drawings]
FIG. 1 is a flowchart for explaining a manufacturing method according to an embodiment of the present invention.
FIG. 2 is a front view of the iron-based raw material powder.
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 cross-sectional view of the molding die.
FIG. 6 is a cross-sectional view of the green compact, partly enlarged.
FIG. 7 is a cross-sectional explanatory view of a 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 Bearing 6 Green compact
11 Mold
16 Filling part
51 Sliding surface (sliding part)

Claims (5)

In a sliding part formed by filling iron-type and copper-type raw material powder into the filling part of a molding die, pressing the raw material powder to form a green compact, and sintering the green compact, the copper The raw material powder is a flat powder having an aspect ratio larger than that of the iron-based raw material powder, copper is segregated on the surface side, and the ratio of copper decreases from the surface side toward the inside and the ratio of iron increases. Sliding parts characterized by 2. The sliding component according to claim 1, wherein the sliding portion has a surface copper coverage of 60% or more. The sliding component according to claim 1 or 2, wherein an aspect ratio of the flat powder is 10 or more. The sliding component according to claim 2, wherein a ratio of the copper-based raw material powder is 20 to 70% by weight of the whole. A method for producing a sliding part comprising filling a molding die with iron-based and copper-based raw material powder, pressing the raw material powder to form a green compact, and sintering the green compact Wherein 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 the copper-based raw material powder in the filling portion is segregated on the surface side of the green compact by vibration. A manufacturing method of sliding parts.

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