JPH0717853Y2 - Sintered oil-impregnated thrust bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improved sintered oil-impregnated thrust bearing, for example, a small thrust bearing such as a bearing for audio equipment or office equipment having a shaft diameter of about 1 to 5 mm. It is about.

[Conventional technology]

In a method of use in which the end surface of a sintered oil-impregnated bearing receives a thrust load, it is known that the oil lubrication on the end surface of the bearing is poor and the friction coefficient is high and the bearing is easily worn.

Normally, the thrust receiving end surface of the bearing is a flat surface that is perpendicular to the shaft. However, due to the above-mentioned circumstances, some devices have been devised to keep the oil supply to the sliding surface to generate hydraulic pressure. For example, Japanese Examined Patent Publication No. 44-22322 in which a spiral shallow groove is provided on the end surface, Japanese Patent Publication No. Sho 48-31164 in which a concave portion larger than a shaft hole is formed on the end surface, and several radial grooves are provided from the concave portion, Concentric or radial concave and convex parts on the end face
-53787 publication etc. are mentioned.

[Problems to be solved by the device]

Conventional thrust bearings with grooves on these end faces have almost the same action and excellent effects, but in the case of bearings that are quite small, such as bearings for audio equipment and office equipment, It was difficult to form the groove with a die with high dimensional accuracy.

It is an object of the present invention to provide a thrust bearing having less oil consumption and frictional resistance.

[Means for Solving the Problems]

The present invention was developed in view of the above circumstances, and the thrust receiving end surface of the ring-shaped sintered oil-impregnated bearing is a flat surface or a convex surface only in the vicinity of the outer periphery, and a uniform cone from the flat surface or the convex surface toward the inner diameter side. A sintered oil-impregnated thrust bearing characterized in that the surface exposed porosity of the thrust receiving end surface is 15% or less in area ratio. The amount of exposed pores on the end face of 15% or less in area ratio can be obtained by crushing the end face.

[Action]

The space formed between the bearing end surface thus configured and the mating rotary shaft flange end surface is filled with lubricating oil to generate hydraulic pressure in a direction away from the shaft due to rotation of the shaft and to cause sliding of the end portion of the bearing toward the outer diameter. It is considered that the surface is lubricated, the scattering of lubricating oil is small, the bearing life is long, and the coefficient of sliding friction is small.

The thrust receiving sliding surface is a flat surface or a convex surface only in the vicinity of the outer circumference of the bearing end surface, and the friction coefficient is kept at a low level by supplying the lubricating oil.

The surface of the tapered end face, which is concave on the inner diameter side, limits the exposed holes to 15% or less in area ratio. If the porosity exceeds 15%, the hydraulic pressure formation will be insufficient. 15% of pores by rubbing or polishing the surface
If the mesh is crushed below, the coefficient of friction is lowered with the effect of increasing the hydraulic pressure.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

FIG. 1 is a sectional view of an essential part for explaining an embodiment of the present invention, in which a bearing housing and the like are omitted.

The shaft 4 has a flange portion 5 having a thrust surface perpendicular to the shaft, and the end surface of the bearing 1 which faces the shaft 4 has a concave taper on the inner diameter side to form a space 3. The taper has an angle of about 1 to 2 degrees with the thrust surface of the shaft, and the shaft diameter for office machines and audio equipment is about 1 to 5 mm. Therefore, considering the size of the bearing used, the space 3 The widest place has a gap size of 0.
It will be about 05 to 0.1 mm. If the space size of the space 3 is too small, the oil film formation will be inadequate, which is almost the same as in the case of a flat surface bearing, whereas if the space size of the space 3 is too large, it will be difficult to form hydraulic pressure.

The end face on the thrust side is surface-blunted before sizing. This treatment can be achieved by means such as a means for press-sliding a polishing disk or a disk having radial projections on its end surface.

Example 1 A 10% Sn bronze-based sintered body having a sintering density of 6.6 g / cm ³ was subjected to end face crushing processing, and then subjected to normal stamping sizing as shown in FIG. 2 (a).
As shown in (d), the thrust receiving end surface is (a) flat (b) concave slope (inverse taper) toward the inner diameter side (c) convex slope (taper) toward the inner diameter side (d) medium-high convex Shaped (convex) ring-shaped thrust bearing sample of 4 types,
Each was impregnated with a synthetic oil corresponding to a viscosity grade of 100.

The size of the bearing sample is φ3.53 × φ9 × 4 mm, and the surface exposed pore area ratio of each sample is 8 to 9% for the inner diameter and 12 to 15% for the thrust receiving end surface.

In addition, the measurement of the amount of voids is obtained by observing an image of the sample surface with a microscope using an image analyzer manufactured by Buehler.

Next, these samples were fitted with the thrust receiving shaft 4 having a diameter of 3.5 mm as shown in FIG. 1 and the consumption rate of the bearing impregnated oil was measured after operating for 1000 hours at 120 rpm.

As shown in Table 1, the oil consumption is small in the embodiment (b) of the present invention having the concave taper on the inner diameter side.

Example-2 Using a bronze-based sintered body of the same material as in Example 1, samples having different exposed surface pores were prepared by polishing the end faces before sizing, and FIGS. 2 (a) and 2 (b) were prepared. Sized to the shape of.

The amount of pores on the inner diameter surface and the impregnated lubricating oil are the same as in Example 1.

Next, the same test method as in Example 1 was used for each sample, and the drive motor current values after 100 hours of operation were compared.

As shown in the measurement results in Table 2, the bearing shape of the present invention has a lower driving current than the flat end surface, and the samples with exposed end surface holes of about 15% or less show a markedly smaller friction coefficient. ing.

[Effects of the Invention] As described above, since the sintered thrust bearing of the present invention has the sliding end face formed in an inverted conical shape, a molding die can be easily manufactured, and a small bearing can be easily molded. In addition, the hydraulic action of an appropriate gap formed with the mating shaft has the characteristics of a small friction coefficient and little oil consumption, so it can be used, for example, in VTRs, sound machines, CD players, office equipment, etc. There is a great effect on the improvement.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining the bearing of the present invention, and FIG. 2 is a schematic sectional view of the bearing shape of the embodiment. 1 ... Sintered oil-impregnated bearing 2 ... Thrust receiving end face 3 ... Space 4 ... Shaft 5 ... Flange

Claims (1)

[Scope of utility model registration request] 1. A ring-shaped sintered oil-impregnated bearing thrust receiving end surface is a flat surface or a convex surface only in the vicinity of the outer circumference, and has a uniform conical concave taper from the flat surface or the convex surface toward the inner diameter side, A sintered oil-impregnated thrust bearing, wherein the surface exposed porosity of the thrust receiving end surface is 15% or less in area ratio.