LT3560B - A method for making a radial bearing - Google Patents

Abstract

In the process described, metal powder is mixed with not more than approximately 20 wt.% of ceramic particles, and the mixture is pressed to obtain a bearing of appropriate shape, while retaining a pore volume of at least 15 %. The pressed part is then sintered. The bearing hole is gauged to the final dimension uniquely by passing a gauging mandrel through the hole.

Description

The invention relates to the field of machinery manufacturing.

Is known in U.S. Pat. 3137927, nac. Cl. 29-182.5, publ. 1964, describes a method of manufacturing articles made of ceramic particles contained in a metal base component by mixing a powder of a metal and a ceramic material and then sintering the resulting mixture. Products made in this way have a certain porosity.

The disadvantage of the known method is the insufficient service life.

The object of the invention is to extend the life of bearings.

The process consists of mixing metal powders and solids up to 20% by weight, compressing the mixture in a mold corresponding to the shape of the future bearing, with a porosity of at least 15%, then sintering the die and machining the bearing hole to the required dimensions. skipping a calibrated mandrel through it.

The method allows the production of bearings with solid particles distributed on the surface of the hole wall and in contact with the shaft at no cost. The result of such interaction of the shaft material with the solid particles is a very low coefficient of friction, as in the case of ceramic bearings. In addition, the process of manufacturing bearings according to the present invention is greatly simplified by the fact that solid particles on the surface of the orifice wall of a relatively soft metal core component can be pressed into it by passing a calibrated mandrel through the orifice, and without grinding or using abrasion.

This way, very precise bearings with extended service life can be produced quickly and inexpensively. Furthermore, the bearings produced by the process of the present invention have the advantage that the heat released therein can be rapidly dissipated in the surrounding environment due to the high thermal conductivity of the metal main component. This is also helped by the high porosity of the bearings, which allows them to be impregnated with oil, which further increases their heat permeability. In addition, the oil reduces the noise level when the bearings are working.

The radial bearings produced by the process of the present invention have a very long service life, even when the solids content of the metal main component is in the range of 3-10%. Such low solids content in their homogeneous metal powder mixture proved to be sufficient to reduce wear on press equipment used in the manufacture of press products.

Preferably the solids content is about 15% by weight.

The calibration process is further facilitated by the use of a high ductile metal base component, which can be achieved if the porosity of the sintered bearing is about 20-30%.

Although iron powder can also be used for metallic base weight, it is commonly used in production for bronze powder.

Aluminum oxide, silicon nitrite, or other ceramic materials are preferable as solid particulate material, although metal carbides may be used. It is important that these particles interact with the material of the shaft to obtain a low coefficient of friction.

The obtaining of homogeneous mixtures of metal powders and particulate matter is substantially simplified if the particle sizes of both materials are approximately the same order of magnitude. Ideally, the particles introduced into the parent component should not exceed 50 µm in size.

Although the angular shape of the particles introduced into the main component is preferable in terms of the sintering process and the incorporation of solids into the metal main component, it is still preferable to use spherical shaped solids as this reduces friction in the bearing even further.

The method of making radial bearings is explained in more detail in the example below.

For the bearing described in the example, a bronze powder having a particle size of 50 μτη is mixed in a ratio of 7: 1 by volume with a powder of silicon nitrite having a spherical shape of 50 μτη. This corresponds to about 5% by weight of silicon nitrite in the mixture. At this stage, it is necessary to ensure that the powdered silicon nitrite is homogeneously distributed in the mixture.

The prepared mixture is then placed in a mold corresponding to the shape of the future bearing and pressed. The resulting pressed mixture is removed from the mold and sintered.

The sintering process is usually carried out in the same way as for conventional sintered bronze bearings.

After the bearings are removed from the mold again, the orifice is calibrated in the same way as for conventional sintered bearings, namely, by passing a corresponding calibrated mandrel through the orifice.

The bearing is then impregnated in vacuo with an oil that holds such a composite material in the pores. The bearing is then ready for use.

It is apparent from the foregoing description that the bearings can be obtained in a very simple manner, essentially using the same equipment as used for the manufacture of simple sintered bearings. However, the essential advantages of this type of bearings are that they have a layer of solid silicon nitrate on the peripheral surface of the wall which, in combination with a ceramic shaft mounted in the hole, has a very low coefficient of friction. Therefore, bearings of this type, whether oil-lubricated or not, have a sufficiently long service life and can be used on non-rhythmically operated, often actuated and braked shafts.

Claims (5)

DEFINITION OF INVENTION 1. A method of manufacturing radial shaft bearings having solid particles in the main metal component and forming a part of the hole wall, wherein the metal and solid particles are mixed and the resulting mixture sintered, spun onto . . by mixing the metal powder with not more than 20% by weight of said solids, the prepared mixture is extruded in a form corresponding to a bearing shape so that the porosity of the extruded product is at least 15%, the sintered product is then sintered to the required dimensions by passing through a calibrated mandrel. 2. A process according to claim 1, wherein the solids content of the mixture is 3-10% by weight. 3. A process according to claims 1 and 2, wherein the solids content of the mixture is 5% by weight. 4. A process according to claims 1-3, wherein the sintered bearing has a porosity of 20-30%. 5. A process according to claims 1-4, wherein the metal powder is a bronze powder. 6. A method as claimed in claims 1-5, characterized in that the particulates contain alumina, silicon or other ceramic materials. 7. A way to get 1-5 points, which is different ^! Metal particles contain metal carbide. 8. A process according to claims 1-7, wherein the solid particles and the metal powder have the same dimensions. 9. The method of claims 1-8, wherein said particles are in the form of a spherical shape.