KR100361270B1 - lubricant composite for bearing - Google Patents

Abstract

In the present invention, the lubricating composition for bearings has a ratio of 1 to 95 parts by weight of ultra high molecular weight polyethylene having an average molecular weight of 1 x 10 ⁶ to 5 x 10 ⁶ and a grease of 1 to 95 parts by weight having a dropping point higher than the melting point of the ultra high molecular weight polyethylene. It is made by heat-treating the mixture, which is maintained at a desired position without natural flow even during heat treatment or heating. .

Description

Lubricant composition for bearings

The present invention relates to a lubricating composition for bearings and, more particularly, to a lubricating composition for bearings composed of a mixture of ultra high molecular weight polyethylene (average molecular weight of about 1 x 10 ⁶ to 5 x 10 ⁶ ) and grease or oil.

Generally, semi-solid grease is used for lubrication of rolling bearings. In lubrication by this grease, the bearing flows out during rotation, so the bearing must be sealed with a sealing device such as a seal.

Therefore, it was difficult to adopt grease lubrication for small bearings. When the centrifugal force acts on the bearing, grease is scattered and sticking occurs in a short time.

In order to prevent such a phenomenon, a lubricating composition has been developed that does not have a seal and does not scatter lubricant even when the bearing is centrifugally moved. That is, as such a lubricating composition, a lubricating composition is developed which is filled with a liquid and semi-solid mixture obtained by mixing lubricating oils such as polyethylene and grease or mineral oil in the bearing space, and then solidified by heat treatment with the bearing. It is becoming.

By the way, the lubricating composition as described above is the whole or only lubricating oil before it is filled and heated in the bearing, so when applied to the bearing, the mixture is artificially in the inner space between the outer ring, until the lubricating composition is cured There was a problem to maintain.

In addition, since the lubricating composition naturally fills the inner space of the bearing before solidification, partial filling becomes impossible, which increases the torque of the bearing, and in particular, increases the torque of the bearing when the bearing temperature decreases. There was this.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to maintain a desired position without natural flow even during heat treatment or heating, as well as good workability and strong self-lubrication of the bearing applied It is to provide a lubricating composition for a bearing that can maintain a long term.

1 is a schematic configuration diagram of a rolling bearing to which the lubricating composition of the present invention is applied;

2 is a graph of the starting torque of the rolling bearing to which the lubricating composition according to the present invention is applied;

3 is a graph showing the operating torque of the rolling bearing to which the lubricating composition according to the present invention is applied;

Figure 4 is a graph showing the weaning rate for the centrifugal force of the rolling bearing applied lubricating composition according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: outer ring 2: inner ring

3: ball 4: lubricating composition

The lubricating composition for bearings according to the present invention is a grease 1 having 1 to 95 parts by weight of ultra high molecular weight polyethylene having an average molecular weight of 1 x 10 ⁶ to 5 x 10 ⁶ and a dropping point higher than the melting point of the ultra high molecular weight polyethylene. ~ 95 parts by weight of the mixture characterized in that made by heat treatment.

The lubricating composition for bearings according to the present invention comprises 1 to 95 parts by weight of ultra high molecular weight polyethylene having an average molecular weight of 1 x 10 ⁶ to 5 x 10 ⁶ and 5 to 95 parts by weight of oil having a flash point higher than the melting point of the ultra high molecular weight polyethylene. It may also be achieved by heat treatment of the mixture formed in proportion.

The ultra high molecular weight polyethylene and grease or oil mixture is preferably added 1 to 50 parts by weight of an additive including a viscosity index improver to prevent oil from seeping.

The heat treatment of the mixture of the ultra high molecular weight polyethylene and the grease or oil is performed by heating to a temperature above the melting point of the ultra high molecular weight polyethylene and then cooling and solidifying the mixture.

On the other hand, the lubricating composition for bearings according to the present invention has 1 to 50 parts by weight of ultra high molecular weight polyethylene having an average molecular weight of 1 x 10 ⁶ to 5 x 10 ⁶ , and a low molecular weight having an average molecular weight of 2 x 10 ³ to 1 x 10 ⁵ . The mixture of 1 to 50 parts by weight of polyethylene and 5 to 95 parts by weight of grease or oil having a dropping point higher than the melting point of the low molecular weight polyethylene may be formed by heat treatment. It is preferable that 1-50 weight part of additives containing a viscosity index improver which prevents oil from seeping into this mixture are added.

The heat treatment of the mixture of the ultrahigh molecular weight polyethylene, the low molecular weight polyethylene, and the grease or the oil is performed by heating to a temperature above the melting point of the low molecular weight polyethylene and then cooling and solidifying the mixture.

The polyethylene is mixed as a powder of 60 ~ 150 mesh.

The grease is soap-based grease such as lithium-ester grease, lithium-mineral grease, sodium-mineral grease, lithium-diester grease, soap-mineral grease, soap-ester grease, soap Soap-based greases such as polyol ester grease and soap-poly alphaolefin grease are used. The soap consists of urea, organic treated clay, silica gel, polytetrafluoroethylene and the like.

The oil is a mineral oil or a synthetic oil, and as the synthetic oil, poly alpha olefin oil, ester oil, alkyl benzene oil, poly alkylene glycol oil, polybutene oil and the like are used.

The grease (or oil) contains about 5% by weight of additives based on the total weight of the grease (or oil). The additive may be added separately.

The additives include antioxidants, rust inhibitors, extreme pressure agents, abrasion resistant agents, adhesive improvers, viscosity index improvers and the like. As the antioxidant, diphenylamine, phenyl alpha-naphthylamine, and the like are used, and as the anti-rust agent, sulfonates sodium nitride are used, and the extreme pressure agent is fused at high load. Organic compounds containing chlorine, phosphorus, sulfur, etc. are used, and anti-wear agents include tricresyl phosphate, Zn-DTP (Zinc dialkyldithiophosphates) and polyisobutylene. Various polymers, such as polyisobutylene, are used. As the viscosity index improver, olefin copolymers (OCP) such as ethylene-propylene copolymers, alkyl methacrylates, and the like are used. The viscosity index improver accounts for about 50% by weight of the additive as a whole.

Since the melting point of the ultra high molecular weight polyethylene or the low molecular weight polyethylene is generally 80 ⁰ C to 150 ⁰ C, the heat treatment temperature of the mixture is preferably 150 ⁰ C to 200 ⁰ C. The heating time is preferably about 20 minutes to 1 hour.

The heat treatment may be performed after filling the mixture between polyethylene and grease or oil in the space between the inner and outer rings of the rolling bearing, or before filling the space between the inner and outer rings of the rolling bearing.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described.

Example 1

A mixture of 2.5 g of a low molecular weight polyethylene powder (100 mesh) having an average molecular weight of 24,000 and 7,5 g of a lithium-ester grease was heated at 150 to 160 ⁰ C for 30 minutes to obtain a mass of 10 g of a porous compressive strength of 3 kg / cm ² . . As the lithium-ester-based grease, a grease composed of 20 wt% lithium, 75 wt% ester, and 5 wt% additive was used.

Example 2

A mixture of 5 g of ultra high molecular weight polyethylene (average molecular weight 2 x 10 ⁶ ) powder and 15 g of grease was heated at 160 to 200 ⁰ C for 30 minutes to obtain 20 g of agglomerate having an excellent compressive strength of 20 to 40 kg / cm ² . In this case, when the lithium-mineral grease or the sodium-mineral grease was used, it became a lump of about 40 kg / cm ² in compressive strength, and about 20 when the lithium-diester grease or the lithium-diester-mineral grease was used. It became a mass of compressive strength of kg / cm ² .

Example 3

A mixture of 2 g of ultra high molecular weight polyethylene (average molecular weight 2 x 10 ⁶ ) powder, 1 g of low molecular weight polyethylene (average molecular weight 50,000) and grease 17 g is heated at 160 to 180 ⁰ C for 30 minutes to give a mass of 20 g of compressive strength of 10 to 15 kg / cm ² . Got. In this case, when the lithium-mineral grease or the sodium-mineral grease was used, it became a mass of compressive strength of about 15 kg / cm ² , and about 10 when the lithium-diester grease or the lithium-diester-mineral grease was used. It became a mass of compressive strength of kg / cm ² .

[Test Example 1]

After filling the lubricating compositions of Examples 2 and 3 in the space between the outer ring and inner ring of the inner groove inner bearing (# 6203) having an inner ring diameter of 17 mm and heating at 160 to 180 ⁰ C for 30 minutes, the measured starting torque was measured. 2 is shown graphically. At this time, the measurement conditions were 1kg of bearing load and 25 ⁰ C of ambient temperature.

In view of the fact that the starting bearing of the conventional lubricating composition using polyethylene has a starting torque of 70 g.cm under the same measurement conditions, the starting torque of Examples 2 and 3 is 35 g.cm on average, and the starting torque is remarkably high. You can see little.

[Test Example 2]

The lubricating compositions of Examples 2 and 3 were filled in the space between the outer and inner rings of the inner groove bearing (# 6203) having an inner diameter of 17 mm, heated at 160 to 180 ⁰ C for 30 minutes, and measured up to 40 minutes after starting. One operating torque is shown graphically in FIG. At this time, the measurement conditions were 1kg bearing load, the ambient temperature was 25 ⁰ C, and the rotational speed was 3600 rpm.

In view of the fact that the ball bearing to which the lubricating composition using the conventional general polyethylene is applied is about 20 minutes after starting under the same measurement conditions, the operating torque of the lubricating composition of Example 2 is 90 g. g.cm, and the operating torque of the lubricating composition of Example 3 is 80 g.cm, which shows that the operating torque is remarkably small.

[Test Example 3]

A graph of the results of testing the lubricating composition of Example 3 with a centrifugal force 3000G and testing the weaning rate (development of oil from grease, unit wt%) for 4 hours is shown in FIG. Although the wetting ratio of the lubricating composition using the conventional general polyethylene will be 20 weight%, the wetting rate of this Example 3 is only 10 weight% at most.

On the other hand, when comparing the composition consisting of low molecular weight polyethylene and grease as in Example 1, and the composition consisting of ultra high molecular weight polyethylene and grease as in Examples 2 and 3, the composition of Example 1 is the composition of Examples 2 and 3 The composition of Examples 2 and 3 was less scattered of the oil than the composition of Example 1 when compared to the composition of Example 1 and the composition was filled in the bearing space and the bearing was rotated (10,000 rpm). Thus, it can be seen that lubricating compositions containing ultra high molecular weight polyethylene are more preferred than low molecular weight polyethylene.

And as a result of measuring the weaning rate after 15 hours of heating the lubricating compositions of Examples 2 and 3 at 160 to 180 ⁰ C, the wetting rate of Example 2 was 7%, and the wetting rate of Example 3 was only 4.5%. . This wetting rate is significantly lower than the wetting rate of the conventional lubricating composition using polyethylene.

Fig. 1 shows a state in which the lubricating composition 4 of the present invention is filled in the space between the outer ring 1 and the inner ring 2 of a rolling bearing. This lubricating composition is filled between the ball 3 and the ball 3 held at regular intervals by a retainer (not shown).

In the present invention, the composition having an ultra high molecular weight polyethylene of 50 parts by weight or more can be used as a bearing material, particularly as a retainer.

According to the lubricating composition for bearings according to the present invention, since the mixture before the heat treatment has a grease shape without natural flow under the dropping point of the grease, it is easy to handle and the solids after the heat treatment are supplied by supplying a suitable lubricant to the raceway surface of the bearing. Lubricate. In addition, the oil is bleeding out slowly and stably due to the strong holding force, so that self-lubrication of the bearing can be maintained for a long time. This effect can lower the weaning rate for centrifugal forces acting during long-term operation by adding additives to prevent oil from seeping out.

Claims (6)

delete delete 1 to 50 parts by weight of ultra high molecular weight polyethylene having an average molecular weight of 1 x 10 ⁶ to 5 x 10 ⁶ , 1 to 50 parts by weight of low molecular weight polyethylene having an average molecular weight of 2 x 10 ³ to 1 x 10 ⁵ , Grease or oil having a dropping point higher than the melting point of the low molecular weight polyethylene 5 to 95 parts by weight of the mixture composition is characterized in that the bearing is made by heat treatment. The method of claim 3, Lubricating composition for bearings, characterized in that it further contains a viscosity index improver to prevent oil from seeping in a proportion of 1 to 50 parts by weight, based on the total weight of the mixture. delete The method of claim 3, The lubricating composition is a lubricating composition for a bearing, characterized in that the composition is made by a heat treatment for heating to a temperature higher than the melting point of the low molecular weight polyethylene and then cooled to solidify