DE4137723A1 - SINTER GLEITLAGER - Google Patents

Description

This invention relates to a sintered sliding bearing, and more particularly a sintered plain bearing for use in a high temperature environment exercise, eg. B. as a bearing for a heat roller in a copying machine.

As a sintered alloy plain bearing for motors with small dimensions gene and electrical household appliances have been mostly ölge soaked sintered bearings used, d. H. Sintered bearings whose pores with be soaked in a lubricating oil.

The oil-impregnated sintered bearings have the disadvantage that when they are in a high temperature environment of e.g. B. about 250 ° C used be, the soaking oil leaking out of the pores and then his Lubricating property loses or burns, causing the bearing no longer usable.

A commonly used measure to that described above Disadvantage to avoid is either the use of a sinter alloy, which is not impregnated with oil, but a solid Lubricant, such as graphite or molybdenum disulfide, in the Legie matrix, or the use of a ball bearing, in which is a special, more stable at high temperatures Lubricant is injected.

However, it is sintered alloys which rely on solid lubricants are supported, to obtain sufficient Schmierwir necessary, add a large amount of solid lubricant inflict what a deterioration of the strength of the mate rials. Furthermore shows a bearing with a solid lubricant by nature a high coefficient of friction in comparison for storage with liquid lubricants. These disadvantages narrow the Use of bearings. The bearing has solid lubricant Furthermore, the disadvantage that the production costs are higher as those of oil-soaked bearings.  

The use of a ball bearing has on the other side the Disadvantage that it is much more expensive than the usual Sintergleit camp is.

An object of this invention is to provide a sintered plain bearing for To provide which excellent sliding properties in a high temperature environment and is inexpensive.

Another object of this invention is to provide a sintered slide To provide bearings for high temperature applications is suitable and has a long service life.

Another object of this invention is to provide a sintered slide stock to provide, which is a low wear in the temperature range from normal temperatures to high Temperatures shows.

These and other objects, which are described in the following de Detailed description can be made according to the invention be achieved by a sintered sliding bearing, which has a porous Sin terlegierung comprises, wherein at least the pores of the upper surface layer of the sliding side with a thermoplastic Resin are filled, wherein the thermoplastic resin is a melt viscosity at 250 ° C of 10 to 2000 mPa · s has.

As a porous sintered metal Fe-Cu-C alloys, Co and / or a carbide-forming element containing iron alloys, Cu-Sn alloys, Al alloys or the like used become.

The incorporation of a solid lubricant in this Sinterlegie ments can bring about even more excellent sliding properties. A sintered metal comprising at least one member of Graphite, molybdenum disulfide, tungsten disulfide, lead, boron nitride and Magnesium silicate existing group, which in the matrix of a  Copper alloy or an iron alloy is dispersed particularly preferred.

The content of the solid lubricant in the sintered alloy is preferably not higher than 20% by volume. A content of solid Lubricant exceeding 20% by volume may cause the strength of the material is too low.

Preferably, most of the pores of the sintered metal are with the impregnated thermoplastic resins. However, the camp is also working good, if only the pores of the surface layer or even just the Pores of the inner surface layer, d. H. the surface layer the sliding side of the bearing, are soaked.

The impregnating agent made of thermoplastic resin is characterized in addition to a melt viscosity of 10 to 2000 mPa · s by the fact that it hardly ver its lubricating property ver when subjected to repeated heating / cooling. Besides, it has no corrosive properties. Therefore, a such thermoplastic resin as a "synthetic wax" be be drawn.

The reasons why the above-mentioned melt viscosity range be is preferable, are the following. When the melt viscosity at 250 ° C is less than 10 mPa · s, then the resin prone to being out during use at high temperatures run out of the camp, so that the life of the camp verrin will be. Is the melt viscosity on the other side at 250 ° C more than 2000 mPa · s, it becomes difficult to Warehouse with the resin because of its excessively high viscosity soak, even if the resin is at the highest possible temperature within the temperature range in which the resin is its Lubricating properties does not lose, is heated.

Examples of a thermoplastic resin which are the above possesses ten properties, are polyolefins with a low  Molecular weight, such as polyethylene and polypropylene. A polythy len with a molecular weight (MW) of 2000 to 9000 is FITS ders preferred. A polyethylene with MW of less than 2000 has a low heat resistance, such as for example indicates that it decomposes on heating. Furthermore its viscosity is too low for high temperature applications. On Polyethylene having a molecular weight of more than 9000 has on the other hand, too high a melt viscosity.

The sintered sliding bearing of this invention may e.g. B. by the melt zen of the thermoplastic resin with the above enamel Viscosity and impregnation of the pores of the sintered alloy with the be prepared molten resin.

The sintered sliding bearing of this invention, wherein the pores instead of the oil used in the oil-soaked sintered bearing special thermoplastic resin are filled because of the Liquid lubrication effect of softened or liquefied Har with a suitable viscosity at high temperatures low coefficient of friction when it is in a high temperature turumgebung of z. B. 200 to 300 ° C is used.

If the sintered alloy of the bearing of the invention a solid lubricant such as graphite or molybdenum disulfide contains, the solid lubricant lowers the wear during the operation at normal temperatures and resembles the unzurei liquid lubrication through the resin at normal temperatures out. Furthermore, the solid lubricant is used at high temperature to reduce the coefficient of friction and wear in conjunction with the liquid lubrication by the Resin.

As explained above, the sintered sliding bearing according to the invention has excellent qualities and is furthermore inexpensive, compared to ball bearings. Therefore, the invention is Sin slide bearing as a warehouse for photocopiers,  High temperature devices, conveyors and the like, in which the bearing is used at high temperatures, ge Therefore, the field of application of sintered bearings can be improved you.

This invention is further exemplified by the following examples shows. In the examples, the impregnation agent is thermo plastic resin referred to as "wax".

example 1

In each experiment, a sintered body having a composition was prepared of 9 wt .-% Sn, 3 wt .-% Co, remainder of a dimensioning Cu and un a bearing with an inner diameter of 10 mm, an outer diameter of 16 mm, and a length of 10 mm and a porosity of 20% by volume. Subsequently was Soaked the stock with one of the following waxes or oils:

• 1. Polyethylene wax with a MW of 4000.
• 2. Polyethylene wax with a MW of 2000.
• 3. Polyethylene wax with a MW of 1000.
• 4. Perfluoropolyalkyl ether oligomer having a MW of 7500 (PEPE; fluoro-oil).
• 5. Perfluoropolyalkyletheroligomer having a MW of 6300 (Fluoroöl).
• 6. Poly-α-olefin synthetic oil.

The bearings obtained in the experiments were in air at 250 ° C for 3 h kept and then cooled. After that, the Ausblu the wax or oil from the warehouse.

The results are in Table 1 together with the viscosities the impregnant shown. The table corresponds to the Number of the experiment of the above infusion number.  

Table 1

The bearings of Experiments Nos. 4 and 5, in which the conven synthetic oils (fluoro oils) were used a considerable leakage of the soaked oil.

This results from the fact that the oils low Viskosi Although they have relatively high molecular weights aufwei sen.

The bearing of Experiment No. 6, in which a common lubricating oil is used, is completely unacceptable because the oil is viscous  has been.

With respect to the bearings from the experiments Nos. 1 to 3 is from the Results in the table clearly show that when using Po lyethylenwachs with a viscosity of 10 mPa · s at 250 ° C no leakage of impregnated wax occurs.

Example 2

In each experiment, a mixed powder was added of 9% by weight Sn, 3% by weight Co, balance Cu with 5% graphite dust mixed; the resulting mixture was compacted, ge Sintered and dimensioned to a bearing, which made the camp Example 1 was similar to form. The surviving camps were soaked with one of the aforementioned waxes or oils.

The friction coefficient of each of the obtained bearings was over Check by touching the bearing with one made of carbon steel (S45C Japanese steel grade) made shaft and the Rotating in an environment of 200 ° C studied.

The experimental conditions were the following:

Sliding speed: 9 m / min Bearing pressure: 20 kgf / cm² Operating time: 500 h.

The test results are shown in Table 2. In the Ta belle corresponds to the test number of the abovementioned Trennmit two positions.

Table 2 Experiment No. coefficient of friction 1 0.03 2 0.05 3 0.20 4 0.15 5 0.17 6 0.35

The invented bearings of Experiments Nos. 1 and 2 showed each have a low coefficient of friction while the La eng of experiment No. 3, in which a non-inventive Low viscosity wax was used, and the bearings Experiments Nos. 4 and 5, in which a conventional syntheti oil was used, each with a high coefficient of friction cient.

The reason for the high values of experiments Nos. 3 to 5 is the Loss of lubricating oil due to leakage from the bearing taken. The camp of experiment No. 6, in which a conven Liche lubricating oil was used, showed a very high Rei environment coefficient. The reason for this is assumed that the Lubricating effect of the oil was almost completely gone and hence the lubrication only by the solid lubricant graphite was effected.  

In experiments using 1.5 wt% copper the sintered iron alloy was carried out as the stock material the results showed an outcome to that shown above similar tendency.

Further, when the experiments were conducted by varying the solid lubricant added to the backing material, graphite showed the lowest friction coefficient even though there was no large difference in the friction coefficient between the various solid lubricants used. The value of the friction coefficient increased in the following order:
(low) graphite <molybdenum disulfide <tungsten disulfide <boron nitride <magnesium silicate <lead (high).

Claims (8)

A sintered plain bearing comprising a porous sintered alloy which at least the pores of the surface layer of the sliding side are filled with a thermoplastic resin, wherein the thermoplastic resin has a melt viscosity of 10 to 2000 mPa · s at 250 ° C has. 2. sintered plain bearing according to claim 1, characterized in that the thermoplastic resin is a low-polyolefin resin Is molecular weight. 3. sintered plain bearing according to claim 2, characterized in that the low molecular weight polyolefin resin Polyethylene having a molecular weight of 2,000 to 9,000. 4. sintered plain bearing according to one of claims 1 to 3, characterized characterized in that the sintered alloy at least one of graphite, molybdenum disulfide, tungsten disulfide, lead, Boron nitride and magnesium sulfide selected group selected Member which dismounts in a matrix of an alloy is pergitated, wherein the alloy consists of a group consisting of copper alloys and iron alloys.   5. sintered plain bearing according to claim 1, characterized in that the sintered sliding bearing can be used at high temperatures. 6. sintered plain bearing according to claim 5, characterized in that it as a bearing in a device in which the bearing in a high temperature environment is used, is usable. 7. Sintergleitlager according to claim 6, characterized in that the device is selected from the group consisting of Ko piergers, high-temperature equipment and conveyors exists. 8. sintered plain bearing according to claim 6, characterized in that it can be used as a bearing for heat rollers in a copying machine is.