JP2006258240A - Method for manufacturing sintered slide bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly and stably retain a porosity of 1.0% or less without raising a density of a bearing material. <P>SOLUTION: In the method for manufacturing the sintered slide bearing, pores of a porous sintered body is impregnated/cured with a thermoset resin to perform sealing treatment and the sealing treatment by the resin are performed two times or more at the final step of the manufacturing of the bearing of the porous sintered body. Specifically, the method comprises a sintering step for sintering a pressure-molded powder body to manufacture the porous sintered body; a re-compression step for re-compressing the sintered body; and a sealing treatment step in which sealing operations in which pores of the re-compressed sintered body are impregnated/cured with a resin are performed two times or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In particular, the present invention relates to a method for manufacturing a sintered plain bearing in which pores of a sintered body are impregnated and cured by sealing with resin.

  Among the sintered bearings, a fluid type sliding bearing is one in which lubricating oil is filled and supplied around the bearing as described in JP-A-64-83920, for example, a disk drive spindle motor for high-speed rotation, etc. It is used for. In this sliding bearing, pores such as the bearing surface are blocked or reduced in order to further increase the dynamic pressure action. As this sealing treatment, as described in Patent Document 1, a method of sealing the bearing by various blasting or tumbling treatment or impregnating and hardening resin in the pores is adopted. Further, in the sealing treatment with resin, as described in Patent Document 2, resin is put into pores of a sintered body obtained by sintering a compacted body or a porous sintered body obtained by pre-sizing the sintered body. After impregnating and curing, it is preferable to reduce or close the gaps in the pores caused by the curing shrinkage of the resin or the like by plastic processing in which the sintered body is put into a mold and pressure is applied.

JP-A-11-62948 JP 2002-333023 A

Among the sealing treatment for impregnating the resin, in the method of Patent Document 1, since the impregnated resin shrinks when cured in the pores, the surface opening ratio or the porosity is further increased due to variations in the impregnation amount and the shrinkage rate. It is difficult to reduce or stabilize. As countermeasures, it may be possible to reduce the viscosity of the resin used and employ vacuum impregnation, but it takes time and becomes inefficient. In the method of Patent Document 2, the pores of the porous sintered body are impregnated with a resin and hardened, and the resin is put into a mold and subjected to plastic processing, so that the resin in the pores is in a tightly packed state by shrinkage deformation of the pores. The gap can be reduced. However, as a result of further examination of this method, the present applicants have found that this method differs depending on the density, impregnation method, etc., but the porosity is about 3% at most under normal production conditions, and the porosity is 1%. It was found that the density of the sintered body had to be 7.2 g / cm ³ or more to make it below. Further, as the bearing member, when the density is set to 7.2 g / cm ³ or more, the deformation resistance of the bearing is increased, the transfer accuracy when the dynamic pressure groove is transferred to the inner diameter side of the bearing is deteriorated, and the axial cylindricity is reduced. The correction becomes insufficient and the accuracy of the axial cylindricity is lowered. Accordingly, an object of the present invention is to solve the above-described problems so that the porosity can be reliably and stably manufactured to 1.0% or less without increasing the density of the bearing material.

In order to achieve the above object, the present invention provides a method for manufacturing a sintered sliding bearing in which pores of a porous sintered body are impregnated and cured with a thermosetting resin and sealed, in which the porous sintered body is manufactured. The sealing process with the resin is performed twice or more in the final step.
In the above invention, as specified in claim 2, a sintering step of sintering a green compact to produce a porous sintered body, a recompression step of recompressing the sintered body, It is preferable to pass through a sealing treatment step in which a sealing operation for impregnating and curing the resin in the pores of the recompressed sintered body is performed twice.

  The resin impregnation and curing described above is preferably performed by sealing the sintered body that has been recompressed (including coining, sanding, and other plastic working) as a sintered body. This is because if the sintered body before re-compression is subjected to sealing with resin, the pores are filled with resin, resulting in an increase in deformation resistance of the bearing, for example, a decrease in the transfer accuracy of the dynamic pressure groove on the inner diameter side of the bearing. Because. The resin used is preferably an acrylic thermosetting resin having wettability and low viscosity, for example, from the viewpoint of impregnation. As the sealing treatment, when pores of the sintered body are sealed by resin impregnation, spaces or gaps in the pores are reduced by the cured resin, but the porosity is at most 2 to 3 in one resin impregnation. Stay at%. The porosity can be reliably reduced to 1% or less by the subsequent second resin impregnation. The first resin impregnation and the second resin impregnation can be carried out by the same method and continuously in operation, so that the number of manufacturing steps and equipment costs can be reduced.

  In the production method of the present invention, the pores of the porous sintered body are impregnated with resin and cured twice or more, so that the gaps in the pores are always reduced or closed to the same extent, and the bearing material The porosity can be reduced to 1.0% or less while suppressing the density. As a result, the present invention can reliably seal the pores of the bearing surface without complicating the production, and can contribute to the improvement of the quality of the sliding bearing having no oil content and oil permeability.

  Hereinafter, after explaining in order of the sintering process, the recompression process, and the sealing treatment process as a manufacturing method of the sliding bearing of the present invention, the bearing characteristics will be mentioned.

(Sintering process) In this process, raw material powders such as iron and copper are compressed in a molding die (for example, a die with a die hole, a core rod inserted into the die hole, and upper and lower punches), and compacted. Manufactured as a molded body. Thereafter, the green compact is produced as a porous sintered body by sintering under a predetermined atmosphere.

(Recompression step) In this step, the porous sintered body is manufactured as a porous sintered body having a designed bearing shape by recompression, that is, plastic processing such as coining and sanding, so that the pores are not completely crushed.

(Sealing treatment step) In this step, the operation of impregnating the resin in the pores of the sintered body obtained in the sintering step or the sintered body obtained in the recompression step and curing is repeated twice or more. Here, it is preferable that the resin to be used has durability against lubricating oil and is excellent in heat resistance and sliding characteristics. Specific resins include impregnated to heat curable resin liquids, and thermoplastic resin liquids that have been reduced in viscosity by the addition of a solvent. From the comparative test, acrylic thermosetting resins are generally good. It is. An example of this resin is a product name LESINOL-90C manufactured by Henkel Japan. The impregnation method is preferably normal pressure impregnation, but may be atmospheric pressure impregnation, and more preferably, pressure impregnation is performed after the pressure impregnation. In addition, it is preferable that the sintered body is impregnated with the resin liquid and then washed with hot water or water to remove excess resin on the surface, and then cured in boiling water. Thereby, a bearing in which pores of the sintered body are filled and cured with resin is obtained. The resin is preferably filled in the pores in the center of the sintered body, but the resin may be filled in the pores in the surface layer and the center may be incomplete.

(Bearing characteristics) Sintered plain bearings obtained by the above processes are not oil-impregnated or oil-permeable, and when operated with lubrication oil on the sliding surface with the rotary shaft, Since the oil pressure in the sliding portion does not decrease due to the oil being sucked into the bearing, the sliding characteristics are good even with a bearing element having a high surface pressure. The sintered sliding bearing is suitable for a bearing element provided with an oil supply mechanism, and is provided with an external oil supply device or an aspect in which a lubricating oil is filled in a bearing storage container like a spindle motor bearing. Used in Further, even when this manufacturing method is applied to a bearing having a smooth sliding surface without a dynamic pressure groove, if it is used as a bearing element having a structure in which lubricating oil is constantly supplied to the bearing sliding portion, the above-described hydraulic pressure action can be achieved. An effect is obtained. The most suitable application is a bearing with a dynamic pressure groove in the sliding part, in particular a spindle bearing. Since the groove of the bearing sliding surface is sealed and the hydraulic pressure escape is completely eliminated, a higher dynamic pressure effect can be obtained.

  Here, in order to clarify the usefulness of the method of the present invention, a cylindrical powder compact having a predetermined size obtained by compressing a copper iron-based raw material powder, the above-described sintering step, the above-described recompression step, the above-mentioned An example will be given when the density-porosity relationship of the manufactured sintered plain bearing is examined through a sealing treatment step in which the sealing operation is performed once (Comparative Example) or twice (Example).

In the recompression process, each sintered body was sized so that the density was 6.8 g / cm ³ , 7.0 g / cm ³ , and 7.2 g / cm ³ . In the sealing treatment step, Resinol 90C manufactured by Nippon Loctite Co., Ltd. was impregnated under the same conditions as an acrylic thermosetting resin, and after impregnation, cured in boiling water, washed with water, and then similarly dried.

In the comparative example of FIG. 1 (b), by performing the sealing operation only once, for example, in a bearing having a density of 6.8 g / cm ³ , the porosity becomes 3.0%, and the porosity becomes 1.0% or less. It can be seen that the bearing must have a density of about 7.4 g / cm ³ or more. On the other hand, in the embodiment of FIG. 1A, the porosity is reduced to 1.0% or less in a bearing with a density of 6.8 g / cm ³ , for example, by performing the sealing operation twice. Therefore, it can be seen that the method of the present invention can reliably and stably produce a porosity of 1.0% or less without increasing the density of the bearing.

(A) is an Example and (b) is a density-porosity graph showing a comparative example.

Claims (2)

  In a method of manufacturing a sintered sliding bearing in which pores of a porous sintered body are impregnated and cured with a thermosetting resin and sealed, the sealing treatment with the resin is performed in the final step of manufacturing the porous sintered body. A method for producing a sintered plain bearing, which is performed twice or more. Sintering the green compact to produce a porous sintered body, a recompressing step for recompressing the sintered body, and impregnating the pores of the recompressed sintered body with resin. The manufacturing method of the sintered sliding bearing of Claim 1 which passes through the sealing process process which performs the sealing operation which hardens | cures twice.

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