KR100550589B1 - a composition of lubrication for bearing - Google Patents

Abstract

The present invention relates to a lubricating composition for bearings, wherein the lubricating composition is solidified by heat treatment with a bearing, and has a urethane group (-NH-COO-) of 3 to 10% by weight and an average molecular weight of 1 x 10 ⁴ to 6 x. 1 to 95% by weight of polyurethane which is 10 ⁴ and 1 to 95% by weight of grease or oil having a dropping point (or flash point) higher than the melting point of the polyurethane, and naturally flowing even during heat treatment or heating. It is maintained at a desired site and position without good work as well as a strong holding force and has the effect of maintaining the self-lubrication of the applied bearing for a long time.

Description

Lubrication composition for bearings {a composition of lubrication for bearing}

1 is a schematic perspective view of a ball bearing to which a lubricating composition according to the present invention is applied;

Figure 2 is a perspective view of the incision of the ball bearing to which the lubricating composition according to the present invention is applied,

3 is a graph showing the starting torque of the ball bearing to which the lubricating composition according to the present invention is applied compared with the ball bearing to which the conventional lubricating composition is applied;

4 is a graph showing the operating torque of the ball bearing to which the lubricating composition according to the present invention is applied compared with the ball bearing to which the conventional lubricating composition is applied;

5 is a graph showing the weaning rate by the centrifugal force of the ball bearing to which the lubricating composition according to the present invention is applied as compared to the ball bearing to which the conventional lubricating composition is applied;

Figure 6 is a graph showing the high temperature endurance test results of the ball bearing to which the lubricating composition according to the present invention is compared with the ball bearing to which the conventional lubricating composition is applied.

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

1: bearing outer ring 2: bearing inner ring

3: retainer 4: ball

5: lubricating composition

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lubricating compositions for bearings, and more particularly, to lubricating compositions which solidify by heat treatment with bearings.

Generally, semi-solid grease is used for lubrication of rolling bearings. In lubrication by this grease, leakage occurs during the rotation of the bearing, so a sealing device such as a seal is necessary.

And especially in the case of small bearings, it was difficult to adopt grease lubrication. In addition, when the centrifugal force acts on the bearing, grease is scattered and breakage occurs in a short time.

In order to prevent this phenomenon, a lubricating composition has been developed that does not have a seal and prevents the lubricant from leaking or scattering even when the bearing is centrifugally moved. That is, as such a lubricating composition, a lubricating composition obtained by filling a bearing space with a liquid or semisolid mixture obtained by mixing a lubricating oil such as polyethylene and grease or mineral oil in a bearing space, and then heat-processing with a bearing has been developed and applied. .

By the way, in the conventional solidified lubricating composition, the limit of use temperature is limited to 100 degrees C or less.

In the conventional lubricating composition for bearings, only the whole or lubricating oil is automatically flowed before the bearing is filled and heated. Therefore, when applied to a bearing, the mixture must be artificially maintained in the inner space between inner and outer rings until the lubricating composition hardens. There was a problem.

In addition, prior to solidification, the lubricating composition naturally fills the interior space of the bearing, making partial filling impossible, thereby increasing the torque of the bearing, especially when the temperature of the bearing decreases, thus increasing the torque and There was a problem that could not be used.

Therefore, 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 naturally flowing even during the heat treatment or heating, the operation is good, as well as the heat-resistant lubricating composition has a strong holding power It is to provide a lubricating composition for bearings that can maintain the self-lubricating properties of the bearing to be applied even at high temperature for a long time.

The lubricating composition for bearings according to the present invention is a lubricating composition which is heated and solidified together with a bearing, having a urethane group (-NH-COO-) of 3 to 10% by weight and an average molecular weight of 3 x 10 ⁴ to 6 x 10 ^It is characterized in that it is composed of 1 to 95% by weight of ⁴ phosphorus and 1 to 95% by weight of grease having a dropping point higher than the melting point of the polyurethane of the molecular weight.

The high-temperature bearing lubricating composition according to the present invention is a lubricating composition which is heated and solidified together with a bearing, wherein the urethane group (-NH-COO-) has 3 to 10% by weight and an average molecular weight of 3 x 10 ⁴ to 6 x It may be formulated at a ratio of 1 to 95% by weight of polyurethane which is 10 ⁴ and 5 to 95% by weight of oil having a higher flash point than the polyurethane having the above molecular weight.

1 to 50% by weight of an additive including a viscosity index improver for preventing oil from seeping is added to the mixture of the polyurethane and the grease or the oil.

The heat treatment of the mixture of the polyurethane and the grease or oil is carried out by heating to a temperature above the melting point of the polyurethane and then cooling and solidifying.

On the other hand, the lubricating composition for bearings according to the present invention, in the lubricating composition which is heated and solidified with the bearing, has an average molecular weight of 3 x 10 ⁴ to 6 x 10 ⁴ of 1 to 50% by weight of polyurethane and an average molecular weight 1 to 50% by weight of low molecular weight polyurethane of 1 x 10 ⁴ to 2 x 10 ⁴ and 5 to 95% by weight of grease or oil having a dropping point (or flash point) higher than the melting point of the low molecular polyurethane. It may be.

It is preferable to add 1 to 50% by weight of an additive including a viscosity index improver to prevent oil from seeping into the mixed composition of the polyurethane, low molecular polyurethane, grease or oil.

The heat treatment of the mixture of the polyurethane, the low molecular polyurethane, the grease or the oil is carried out by heating to a temperature above the melting point of the low molecular polyurethane and then cooling and solidifying the mixture. The polyurethane is mixed as a powder of 100 to 200 ㎛.

Examples of the greases include soap greases such as lithium + ester grease, lithium + mineral oil grease, sodium + mineral oil grease and lithium + ester grease, soap + mineral oil grease, soap + ester grease and soap. Soap-based greases such as polyol ester-based grease and soap + polyalphaolefin-based greases are used. Soap systems are urea, organoclay, silica gel, PTFE (polytetrafluoroethylene) and the like.

The oil is made of mineral oil or synthetic oil. As the synthetic oil, polyalpha olefin oil, ester oil, phenyl ether oil, silicone oil, polyalkylene glycol oil and the like are used.

The grease (or oil) contains about 5 wt% 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, adhesion improvers, viscosity index improvers and the like. As the antioxidant, diphenylamine, phenyl alpha naphthylamine, and the like are used, and as a rust inhibitor, sulfonates sodium nitride, etc., are used at high loads. Organic compounds containing chlorine, phosphorus, sulfur, etc. are used to prevent fusion. Tricresyl Phosphate (Zn-DTP) and zinc dialkyldithiophosphates (Zn-DTP) are used as the antiwear agent. Various polymers, such as polyisobutylene, are used. As the viscosity index improver, olefin copolymers such as ethylene-propylene copolymers (OCP), alkyl methacrylates (Alkyl methacrlates) and the like are used. Viscosity index improvers account for about 50 wt% of the total additive.

Since the melting point of the polyurethane and the low molecular polyurethane is generally 100 ~ 180 ℃ heat treatment temperature of the mixture is preferably set to 180 ~ 250 ℃. The heat treatment time is preferably about 30 minutes to 1 hour.

The above heat treatment may be carried out before the mixture of polyurethane and grease or oil is filled in the space between the inner and outer rings of the rolling bearing.

Example 1

A mixture of 3 g of polyurethane powder (particle 100 μm) having an average molecular weight of 10,000 and 7 g of lithium + ester grease was heated at 180 to 250 ° C. for 30 minutes to prepare a composition having a porous compressive strength of 40 kg / cm 2 or more. The applied grease was a lithium + ester-based grease, a lithium thickener 20wt%, ester oil 75wt% and 5wt% additives was used.

Example 2

A mixture of 5 g of polyurethane (average molecular weight 3 × 10 ⁴ ) powder and 15 g of grease was heated at 180 to 250 ° C. for 30 minutes to obtain a composition having a compressive strength of 60 kg / cm 2 or more having excellent elasticity. The grease used was lithium + ester-based grease.

Example 3

A mixture of 2 g of polyurethane (average molecular weight 3 × 10 ⁴ ) powder, 1 g of low molecular weight polyurethane (average molecular weight 10,000) and grease 17 g was heated at 180 to 250 ° C. for 30 minutes to obtain a composition having a compressive strength of 50 kg / cm 2 or more. The grease applied at this time used a lithium + ester-based grease.

[Test Example 1]

After filling the lubricating composition (T2, T3) of Examples 2 and 3 in the space between the outer ring and the inner ring of the inner groove inner diameter 12mm deep groove ball bearing (# 6001) and heated for 30 minutes at 180 ~ 250 ℃ Starting torque of the bearing is shown graphically in FIG. 3. The measurement conditions were tested with a bearing load of 0.5 kg and 25 degreeC of ambient temperature.

In the case of a ball bearing to which a conventional lubricating composition (G) using general polyethylene is applied, the starting torque is 50 g · cm under the same measurement conditions, whereas the starting torques of Examples 2 and 3 are 20 g · cm and 30 g · cm, respectively. As a result, a small value of the starting torque was obtained.

[Test Example 2]

Bearing samples prepared by filling the lubricating compositions (T2, T3) of Examples 2 and 3 in the space between the outer ring and the inner ring of the deep groove ball bearing # 6001 having an inner ring inner diameter of 12 mm and heating at 180 to 250 ° C. for 30 minutes. The running torque after starting for 30 minutes is shown graphically in FIG. The measurement conditions at this time were tested with a bearing load of 0.5 kg, 25 degreeC of ambient temperature, and 3,600 rpm.

The ball bearing to which the conventional lubricating composition (G) using polyethylene is applied has the operating torque of 100 g · cm in the normal state after the operation under the same measurement conditions, whereas the operating torque of the lubricating composition applied bearings of Examples 2 and 3 Are 50 g · cm and 60 g · cm, respectively, indicating that the operating torque values are remarkably small.

[Test Example 3]

The bearings filled with the lubricating compositions (T2, T3) of Examples 2 and 3 were loaded with a centrifugal force of 3000G to test the weaning rate (oil deviating from the lubricating composition, unit wt%) after the test for 4 hours. A graph of is shown in FIG. The wetting ratio of the conventional lubricating composition (G) using polyethylene is about 15% by weight (wt)%, and Examples 2 and 3 show results of up to 5% by weight and 6% by weight, respectively.

[Test Example 4]

In order to evaluate and evaluate bearing durability at high temperature, bearings (# 6001) into which the lubricating compositions (T2 and T3) of Examples 2 and 3 were injected were tested at a test temperature of 130 ° C, a rotational speed of 3,400 rpm, and an axial load (accumulation). Medium): Durable life test was conducted under the condition of 50 kgf. The test results are shown in FIG. As a result of the test, the bearing manufactured by injecting the lubricating composition of Example 2 and Example 3 showed a life time result of more than 1,000 hours in both samples, whereas in the case of a ball bearing to which a lubricating composition (G) using conventional polyethylene was applied, Indicated. As shown in FIG. 6, the lubricating compositions (T2, T3) of Examples 2 and 3 show a long life three times longer than the conventional lubricating composition (G).

1 and 2 show a state in which the lubricating composition 5 according to the present invention is filled in the space between the outer ring 1 and the inner ring 2 of the rolling bearing. The lubricating composition according to the present invention is a retainer 3. It is filled between the ball (4) and the ball (4) that is maintained at a constant interval by the). 2 is a cutaway view of a bearing to which the lubricating composition of the present invention is applied.

According to the lubricating composition for bearings according to the present invention, since the mixture before the heat treatment does not flow naturally below the dropping point of the grease and shows a grease shape, it is easy to handle and the lubricating composition after the heat treatment supplies an appropriate lubricant to the raceway surface of the bearing. Smooth lubrication of the bearings. In addition, the oil retained by the holding force is gradually and stably performed, so that the self-lubrication of the bearing can be maintained for a long time even at a high temperature (130 ° C). This effect can lower the weaning rate for centrifugal forces acting for longer periods of time by adding appropriate additives to prevent oil from seeping out.

Claims (5)

In the lubricating composition to be solidified by heat treatment with a bearing, Grease 5 having 3 to 10% by weight of urethane group (-NH-COO-) and 5 to 95% by weight of polyurethane having an average molecular weight of 3 x 10 ⁴ to 6 x 10 ⁴ and a dropping point higher than the melting point of the polyurethane. Lubricating composition for bearings, characterized in that the mixture consists of a ratio of ~ 95% by weight In the lubricating composition to be solidified by heat treatment with a bearing, 5 to 95% by weight of polyurethane having 3 to 10% by weight of urethane group (-NH-COO-) and an average molecular weight of 3 x 10 ⁴ to 6 x 10 ⁴ and an oil having a flash point higher than the melting point of the polyurethane. Lubricating composition for bearings, characterized in that the mixture consists of a ratio of ~ 95% by weight In the lubricating composition to be solidified by heat treatment with a bearing, 1 to 50% by weight of polyurethane having an average molecular weight of 3 x 10 ⁴ to 6 x 10 ⁴ , 1 to 50% by weight of low molecular weight polyurethane having an average molecular weight of 1 x 10 ⁴ to 2 x 10 ⁴ , and the low molecular weight poly Lubricating composition for bearings, characterized in that the mixture consists of a ratio of 5 to 95% by weight of grease having a dropping point higher than the melting point of urethane. In the lubricating composition to be solidified by heat treatment with a bearing, 1 to 50% by weight of polyurethane having an average molecular weight of 3 x 10 ⁴ to 6 x 10 ⁴ , 1 to 50% by weight of low molecular weight polyurethane having an average molecular weight of 1 x 10 ⁴ to 2 x 10 ⁴ , and the low molecular weight poly Lubrication composition for bearings, characterized in that the mixture consists of a proportion of 5 to 95% by weight of oil having a flash point higher than the melting point of urethane The method according to any one of claims 1 to 4, The mixture contains an additive including a viscosity index improver and the like, wherein the additive is contained in an amount of 1 to 50% by weight based on the total weight of the mixture.

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