JP6259709B2 - Copper alloy for slide bearing and slide bearing - Google Patents

Description

  The present invention relates to a copper alloy for a brass-based slide bearing and a slide bearing.

  A copper alloy containing an intermetallic compound containing Fe, Ni, Co and an oxide containing W, Mo, Cr is known (see Patent Document 1). In Patent Document 1, a copper alloy in which the intermetallic compound and the oxide are uniformly distributed is formed by blending and sintering the powders of the respective elements as raw materials of the intermetallic compound and the oxide. . Moreover, the seizure resistance and wear resistance of the copper alloy are improved by the intermetallic compound and the oxide.

Japanese Patent No. 2745695

However, when the copper alloy of Patent Document 1 is used for the sliding member with a small amount of oil supply, there is a problem that wear and seizure are likely to occur. In particular, in the sliding member using the copper alloy of Patent Document 1, wear and seizure are likely to occur during start-up and stop.
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of realizing good wear resistance and seizure resistance even when the amount of oil supply is small.

  In order to achieve the above object, the copper alloy for plain bearings of the present invention comprises 1 wt% or more and 10 wt% or more and 40 wt% or less of Zn, 10 wt% or less (greater than 0 wt%) Bi, and 0.5 vol. % And 15 vol% or less of hard particles, the balance being a copper alloy for a sliding bearing consisting of inevitable impurities and Cu. Moreover, the average particle diameter of the hard particle which the copper alloy for plain bearings of this invention contains is 1 micrometer or more and 30 micrometers or less, and the Vickers hardness of a hard particle is 700 or more.

  The copper alloy for plain bearings described above contains hard particles having an average particle diameter of 1 μm or more and 30 μm or less and a Vickers hardness of 700 or more, so that the hard particles suppress wear and improve wear resistance. be able to. By setting the content of hard particles to 0.5 vol% or more and 15 vol% or less, the hardness of the copper alloy for slide bearings can be appropriately improved, and the wear resistance can be improved. Moreover, by setting the particle size of the hard particles to 1 μm or more and 30 μm or less, it is possible to prevent coarse hard particles from attacking the mating shaft and improve seizure resistance. Moreover, by containing 1 wt% or more of soft Bi, frictional resistance can be reduced and seizure resistance can be improved. That is, both the wear resistance and seizure resistance can be achieved by the hard particles and Bi, and good wear resistance and seizure resistance can be realized even when the amount of oil supply is small. Moreover, cutting can be facilitated by containing Bi. Furthermore, by containing 10 wt% or more and 40 wt% or less of Zn, the strength of the matrix can be improved and sulfidation corrosion at high temperature can be suppressed.

  Furthermore, the average particle diameter of the hard particles is 20 μm or more, and the copper alloy for a slide bearing may be formed by sintering a sintered material in which hard particles are mixed. Thereby, hard particles having a large particle size (particle size of 20 μm or more) can be evenly distributed in the copper alloy for slide bearings. That is, since it is not necessary to flow and mold the hard particles in the alloy as in continuous casting or extrusion, hard particles having a large particle size can be evenly distributed in the copper alloy for sliding bearings.

As compounds constituting hard particles having a Vickers hardness of 700 or more, Fe ₃ P, Fe ₂ P, FeP, SiO ₂ , Al ₂ O ₃ , SiC, AlN, Si ₃ N ₄ , BN, FeB and Fe ₂ B and NiB are mentioned, and at least one of these may constitute hard particles. Furthermore, even in a slide bearing provided with the copper alloy for a slide bearing of the present invention as a copper alloy layer, good wear resistance and seizure resistance can be realized even when the amount of oil supply is small.

It is a perspective view of a thrust bearing. (2A) is an explanatory diagram of the wear test, and (2B) is a schematic diagram illustrating the wear volume. (3A) is an explanatory view of a seizure test, (3B) is a graph of specific wear amount, and (3C) is a graph of seizure surface pressure.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of thrust bearing:
(1-1) Abrasion resistance:
(1-2) Seizure resistance:
(2) Thrust bearing manufacturing method:
(3) Experimental example:
(4) Other embodiments:

(1) Configuration of thrust bearing:
FIG. 1 is a perspective view of a thrust bearing 1 as a slide bearing formed of a copper alloy for a slide bearing according to an embodiment of the present invention. The thrust bearing 1 is, for example, a turbocharger for an internal combustion engine, in which a turbine blade and a compressor blade are applied with a load acting on a mating shaft 2 (one-dot chain line) provided at both ends in the axial direction in the thrust direction (axial direction). To support. The thrust bearing 1 is formed in a cylindrical shape, and the counterpart shaft 2 passes through the inside of the thrust bearing 1. The mating shaft 2 is provided with a collar portion 2a that protrudes radially outward. The collar portion 2a and the thrust bearing 1 are in contact in the thrust direction, and a load is applied to the thrust bearing 1 from the collar portion 2a of the mating shaft 2. Is transmitted. For example, the inner diameter of the thrust bearing 1 may be 5 to 15 mm, the outer diameter may be 20 to 40 mm, and the thickness of the thrust bearing 1 may be 2 to 10 mm. An oil film of engine oil as lubricating oil is formed between the thrust bearing 1 and the collar portion 2 a of the counterpart shaft 2. As the mating shaft 2 rotates, the collar portion 2a of the mating shaft 2 slides on the sliding surface 1a which is the surface of the thrust bearing 1 in the thrust direction. Although not shown, the radial bearing that supports the load acting on the mating shaft 2 in the radial direction may also be formed of the same copper alloy as the thrust bearing 1.

Hereinafter, the copper alloy for the slide bearing constituting the thrust bearing 1 will be described. The copper alloy for a slide bearing contains 27.5 wt% Zn, contains 4 wt% Bi, contains 12 vol% hard particles, and the balance consists of Cu and inevitable impurities. In this embodiment, the hard particles are Inevitable impurities are Mg, Ni, Ti, B, Pb, Cr and the like, which are impurities mixed in refining or scrap. The content of inevitable impurities is 1.0 wt% or less as a whole. The mass of each element in the copper alloy for slide bearings was measured with an ICP emission spectroscopic analyzer (ICPS-8100 manufactured by Shimadzu Corporation). The hard particles of this embodiment were Fe ₂ P and Fe ₃ P, and the Vickers hardness of the hard particles was 789. The hard particles, Fe ₂ and P only formed by particles, and particles formed only by the Fe ₃ P, may include the particles consisting of Fe ₂ P and Fe ₃ P. The average particle size of the hard particles was 19.7 μm. The average particle diameter of the hard particles is an average particle diameter of the hard particles mixed with the material of the thrust bearing 1 when the thrust bearing 1 is manufactured.

(1-1) Abrasion resistance:
A wear test was conducted to evaluate the wear resistance of the copper alloy for the slide bearing constituting the thrust bearing 1. FIG. 3A is a schematic diagram for explaining a cylindrical flat plate type frictional wear tester used in the wear test. In the abrasion test, a test piece T is used so that a cylindrical mating material A is rotated while being partially immersed in engine oil (liquid paraffin) F as a lubricating oil, and a predetermined static load acts on the mating material A. Was brought into contact with the mating material A. The test piece T was formed under the same conditions as the plain bearing copper alloy constituting the thrust bearing 1 and formed into a flat plate shape. The mating material A was made of the same material as the mating shaft 2 that the thrust bearing 1 supports, and was specifically made of SCM415 (chromium molybdenum steel) that had been quenched. The length a of the test piece T in the rotation axis direction of the counterpart material A was 10 mm, and the radius r of the bottom surface of the counterpart material A was 20 mm. The rotational speed of the mating material A was controlled so that the relative movement speed b of the mating material A with respect to the test piece T at the sliding portion was 200 mm / sec. The static load was 139 N, the temperature of the lubricating oil was room temperature, and the test time c was 3600 sec (1 hour). After the wear test was performed under the above conditions, the profile of the depth of the sliding portion of the test piece T with the mating material A was measured with a surface roughness meter (SE3400, manufactured by Kosaka Laboratory). And the difference in depth between the flat part (non-wear part) and the deepest part in the depth profile was measured as the wear depth d.

Ｌは摺動距離であり、摩耗試験において試験片Ｔ上を摺動した相手材Ａの表面の長さである。
摺動距離Ｌは、相対移動速度ｂに試験時間ｃを乗算した値（ｂ×ｃ）である。Ｖは、摩耗試験において摩耗した試験片Ｔの体積（摩耗体積）である。（１）式に示すように、比摩耗量Ｋとは、試験片Ｔに単位荷重（１Ｎ）を作用させた場合に、単位摺動距離（１ｍｍ）あたりに摩耗した試験片Ｔの体積を意味する。比摩耗量Ｋが小さいほど、耐摩耗性が高いことを意味する。 Further, the specific wear amount K was calculated by the following equation (1).

L is a sliding distance, which is the length of the surface of the mating material A that has slid on the test piece T in the wear test.
The sliding distance L is a value (b × c) obtained by multiplying the relative movement speed b by the test time c. V is the volume (wear volume) of the test piece T worn in the wear test. As shown in the equation (1), the specific wear amount K means the volume of the test piece T worn per unit sliding distance (1 mm) when a unit load (1N) is applied to the test piece T. To do. A smaller specific wear amount K means higher wear resistance.

Next, the wear volume V will be described. FIG. 3B is a schematic diagram illustrating the wear volume V. FIG. As shown by hatching in FIG. 3B, the shape of the worn part of the test piece T can be considered to be the shape of the part of the counterpart material A that has entered the test piece T at the end of the wear test. Circular mating member A enters most deeply in the radial CP ₀ orthogonal to the sliding surface 1a of the test piece T from the center C of the bottom surface, the depth that penetrates the mating member A in the radius CP ₀ of mating member A Becomes the wear depth d. Here, on the circumference of the bottom surface of the counterpart material A, when the lower limit points of the portions that have entered the test piece T at the end of the wear test are expressed as P ₁ and P ₂ , the wear volume V is the counterpart material A Can be obtained by multiplying the area of the portion surrounded by the arc P ₁ P ₂ and the string P ₁ P ₂ by the length a of the test piece T. The area of the bottom surface of the counterpart A surrounded by the arc P ₁ P ₂ and the string P ₁ P ₂ is the sector area S ₁ surrounded by the arc P ₁ P ₂ and the radii CP ₁ and CP _2. From this, the area S _{2 of} the triangle surrounded by the chord P ₁ P ₂ and the radii CP ₁ and CP ₂ is subtracted. Therefore, the wear volume V can be calculated by the following equation (2).

ここで、θは、半径ＣＰ₁，ＣＰ₂が相手材Ａの底面の中心Ｃにてなす角度の半分を表す。なお、角度θは、以下の（４）式を満足する。

一方、前記三角形の面積Ｓ₂は図形の対称性から以下の（５）式によって算出できる。

以上のようにして、本実施形態のスラスト軸受１を構成するすべり軸受用銅合金の比摩耗量Ｋを計測したところ、３×１０^-10ｍｍ²／Ｎと良好であった。 The fan-shaped area S ₁ can be calculated by the following equation (3).

Here, θ represents half the angle formed by the radii CP ₁ and CP ₂ at the center C of the bottom surface of the counterpart material A. The angle θ satisfies the following expression (4).

On the other hand, the area S ₂ of the triangle can be calculated by the following equation (5) from the symmetry of the graphic.

As described above, when the specific wear amount K of the copper alloy for the slide bearing constituting the thrust bearing 1 of the present embodiment was measured, it was as good as 3 × 10 ⁻¹⁰ mm ² / N.

(1-2) Seizure resistance:
In order to evaluate the seizure resistance of the copper alloy for the slide bearing constituting the thrust bearing 1, a seizure test was performed. FIG. 4 is a schematic diagram for explaining a pin-on-disk tester used for a seizure test. The seizure test was performed by arranging a pair of test pieces T so as to sandwich the rotating disk-shaped counterpart material A in the thickness direction, and applying a static load between the test pieces T by the hydraulic cylinder W. The rotational speed of the mating material A was adjusted so that the relative speed between the mating material A and the test piece T at the contact portion was 15 m / sec. Further, the contact portion between the mating material A and the test piece T was lubricated by bringing the mating material A into contact with an oiling pad P that holds the lubricating oil (SAE30 CD class). The counterpart material A was formed of SCM415 that had been quenched. A pair of test pieces T was attached to the tip of a beam part E held rotatably in a plane parallel to the counterpart material A, and a load cell Y was arranged so as to prevent horizontal rotation of the beam part E. A balance weight B is attached to the end of the beam E where the test piece T is not provided, and the vertical moment generated in the beam E by the hydraulic cylinder W is offset.

  A frictional force is generated between the counterpart material A and the test piece T, and the beam E rotates horizontally by the frictional force. Therefore, a frictional force that horizontally rotates the beam portion E acts on the load cell Y, and the magnitude of the load measured by the loadcell Y means the magnitude of the frictional force generated between the test piece T and the counterpart material A. . Therefore, when the load acting on the load cell Y is equal to or greater than a predetermined threshold value, it was determined that the frictional force between the test piece T and the counterpart material A was abnormally large and seizure occurred.

The static load acting between the test pieces T by the hydraulic cylinder W is gradually increased (2 MPa / 5 min), and the static load when seizure occurs between the test piece T and the counterpart material A A certain seizure load was measured. Further, the seizing load was measured by dividing the seizing load by the contact area between the test piece T and the counterpart material A.
As described above, the seizure surface pressure of the copper alloy for the sliding bearing constituting the thrust bearing 1 of the present embodiment was measured and found to be as good as 24 MPa. In addition, it means that seizing resistance is so favorable that a baking surface pressure is large.

  As described above, in the present embodiment, by containing hard particles having an average particle diameter of 19.7 μm and a Vickers hardness of 700 or more, the hard particles suppress wear and improve wear resistance. I was able to. By setting the hard particle content to 12 vol% and the average particle size of the hard particles to 19.7 μm, it was possible to improve the wear resistance to such an extent that the seizure resistance was not deteriorated. Moreover, by containing soft Bi, frictional resistance could be reduced and seizure resistance could be improved. That is, both the wear resistance and seizure resistance can be achieved by the hard particles and Bi, and good wear resistance and seizure resistance can be realized even when the amount of oil supply is small. Further, by containing 27.5 wt% Zn, the strength of the matrix can be improved, and sulfidation corrosion at high temperature can be suppressed.

(2) Thrust bearing manufacturing method:
In the present embodiment, the thrust bearing 1 includes a. Forming a green compact; b. Sintering, c. It is manufactured by performing each process of machining in order. Hereinafter, each step will be described.

a. Formation of green compact First, powder of a copper alloy material for a slide bearing constituting the thrust bearing 1 was prepared. That is, brass is formed so that a copper alloy for slide bearings containing 27.5 wt% Zn, 4 wt% Bi, 12 vol% hard particles, and the balance of Cu and inevitable impurities can be formed. The weight ratio and volume ratio of (Cu—Zn) powder, Bi powder, and commercially available hard particle powder were adjusted. In addition, a solid metal ingot composed of Fe and P (P: 20 wt%) is solidified to form an ingot for hard particles, the ingot for hard particles is crushed into a lump, and the particle size is made uniform by sieving. Accordingly, powdered hard particles may be prepared. The powdered hard particles contain Fe ₂ P and Fe ₃ P. In addition, the size of the indentation (average value of the lengths of the two diagonals) formed on the ingot for hard particles with a load of 50 g by using a micro Vickers hardness meter (MVK-EII manufactured by Akashi Seisakusho) The Vickers hardness was measured.

  Next, each powder was mixed uniformly. Next, the mixed powder was put into a mold corresponding to the shape of the thrust bearing 1 and pressed to form a green compact.

b. Sintering Next, the green compact as a sintered material was sintered at 750 to 900 ° C. After sintering the green compact, the average particle size of the hard particles in the thrust bearing 1 was measured as follows. Any cross section of the green compact after sintering was buffed. Next, image data of an observation image (composition image) was obtained by photographing an arbitrary cross section of the green compact after sintering at a magnification of 200 times with an electron microscope (JXA-8100 manufactured by JEOL Ltd.). Then, the observation image was analyzed by an image analyzer (LUZEX AP manufactured by Nireco Co., Ltd.), thereby measuring the particle size of a plurality of hard particles, and the arithmetic average value of the particle sizes of the hard particles was measured as the average particle size. The particle diameter of the hard particles is a projected area equivalent circle diameter (HEYWOOD). In addition, since it can be considered that the shape of the hard particles does not change during machining, the average particle size of the hard particles in the green compact after sintering and the hardness in the thrust bearing 1 obtained by machining the green compact after sintering. The average particle size of the particles can be equated.
c. Lastly, the thrust bearing 1 was completed by finishing the dimensions and surface state by machining such as cutting.

(3) Experimental results:
Table 1 shows specific wear amounts K of Samples 1 to 4 in which only the content of hard particles was changed (Zn content was adjusted within a range of 25 to 30 wt%) from the copper alloy for plain bearings of the above embodiment. The result of measuring is shown. Moreover, each sample 1-4 was created by the method similar to the manufacturing method mentioned above.

  FIG. 4B is a graph showing the relationship between the hard particle content and the specific wear amount K. As shown in the figure, the specific wear amount K decreases as the hard particle content increases. In particular, as the hard particle content increases in the range of hard particle content of 0 to 3 vol%, the specific wear amount K decreases rapidly, and at least about 0.5 vol% of hard particles are contained. Abrasion can be realized. In a range where the hard particle content is 12 vol% or more, the specific wear amount K is substantially constant. Therefore, it is desirable to ensure the workability and the like of the thrust bearing 1 by suppressing the hard particle content to 15 vol% or less (preferably 15 vol% or less).

Table 2 shows the seizure surface pressure of samples 5 to 9 in which only the Bi content is changed (Zn content is adjusted within the range of 25 to 30 wt%) from the copper alloy for plain bearings of the above embodiment. The results are shown. Moreover, each sample 5-9 was created by the method similar to the manufacturing method mentioned above.

  FIG. 4B is a graph showing the relationship between the Bi content and the baking surface pressure. As shown in the figure, the baking surface pressure increases as the Bi content increases. In particular, as the Bi content increases in the hard particle content range of 0 to 2 wt%, the seizing surface pressure decreases rapidly, and it is better to contain at least Bi (preferably about 2 wt%) at least Bi. High seizure resistance. When the Bi content is in the range of 6 vol% or more, the seizing surface pressure does not increase greatly even if the Bi content increases. Therefore, it is desirable to ensure the hardness of the thrust bearing 1 by suppressing the Bi content to 10 wt% or less (preferably 6 wt% or less).

(4) Other embodiments:
In the said embodiment, although the example which formed the thrust bearing 1 with the copper alloy for slide bearings of this invention was shown, you may form another sliding member with the copper alloy for slide bearings of this invention. For example, a gear bush for a transmission, a piston pin bush, a boss bush, or the like may be formed from the copper alloy of the present invention. Moreover, the copper alloy for plain bearings of this invention does not necessarily need to be manufactured by sintering, for example, may be manufactured by casting and continuous casting. Further, the hard particles are not necessarily Fe ₃ P or Fe ₂ P, and FeP, SiO ₂ , Al ₂ O ₃ , SiC, AlN, Si ₃ N ₄ , BN, FeB, Fe ₂ B, and NiB. You may be comprised by any 1 or more types of them.

  In the above embodiment, the entire slide bearing is made of the copper alloy for the slide bearing, but the copper alloy layer formed of the copper alloy for the slide bearing of the present invention and the layer formed of another material are laminated. A sliding bearing may be formed by. For example, the slide bearing may be formed by laminating a copper alloy layer formed of the copper alloy for the slide bearing of the present invention and a back metal formed of steel. Moreover, the overlay formed with the metal or resin may be laminated | stacked on the copper alloy layer formed with the copper alloy for plain bearings of this invention.

  DESCRIPTION OF SYMBOLS 1 ... Thrust bearing, 2 ... Mating shaft, A ... Mating material, K ... Specific wear amount, L ... Sliding distance, P ... Oil supply pad, W ... Hydraulic cylinder, T ... Test piece, V ... Wear volume, E ... Beam Part, Y ... load cell.

Claims (4)

Zn of 10 wt% or more and 40 wt% or less,
Bi of 1 wt% or more and 10 wt% or less;
0.5 vol% or more and 15 vol% or less hard particles,
The balance is a copper alloy for sliding bearings consisting of inevitable impurities and Cu,
The average particle size of the hard particles is 1 μm or more and 30 μm or less,
A copper alloy for a slide bearing, wherein the hard particles have a Vickers hardness of 700 or more. While the average particle size of the hard particles is 20 μm or more,
It is formed by sintering a sintered material mixed with the hard particles.
The copper alloy for slide bearings according to claim 1. The hard particles are composed of at least one of Fe ₃ P, Fe ₂ P, FeP, SiO ₂ , Al ₂ O ₃ , SiC, AlN, Si ₃ N ₄ , BN, FeB, Fe ₂ B and NiB. The
The copper alloy for slide bearings according to any one of claims 1 and 2. Zn of 10 wt% or more and 40 wt% or less,
Bi of 1 wt% or more and 10 wt% or less;
0.5 vol% or more and 15 vol% or less hard particles,
The balance is a plain bearing made of inevitable impurities and Cu,
The average particle size of the hard particles is 1 μm or more and 30 μm or less,
A sliding bearing, wherein the hard particles have a Vickers hardness of 700 or more.

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