Grease composition and rolling device

Abstract

As a grease composition maintaining a low torque over a wide temperature range and further hardly inducing white texture flaking, the present invention provides a grease composition comprising a base oil having a dynamic viscosity at 40° C. of 20 to 50 mm2 / s, a urea compound as a thickening agent in an amount of 8 to 30% by weight with respect to total weight of the grease, at least one antirust additive selected from carboxylic acids, carboxylate salts, and ester-based antirust additives in an amount of 0.1 to 10% by weight per single additive with respect to total weight of the grease and in an amount of 0.1 to 15% by weight in total of the additive with respect to total weight of the grease, and a rolling device comprising the grease composition which works with a low torque, hardly induces white texture flaking, and is excellent in durability.

Description

TECHNICAL FIELD [0001] The present invention relates to a grease composition particularly excellent in anti-flaking performance and anti-seizure performance in a wide temperature range of from a low temperature to a high temperature and having a low torque performance. Moreover, the invention relates to a rolling device such as a rolling bearing, a ball screw device, or a linear guide device into which such a grease composition is charged. BACKGROUND ART [0002] In rolling bearings for use in motors and the like and ball screw devices and linear guide devices for use in machine tools and the like, a small torque, a maintenance-free property (durability for a long period of time), and the like characteristics are required for enhancing working efficiency. In these rolling devices, grease compositions have been generally used for lubrication. In order to satisfy such requirements, a lithium soap grease (e.g., “Multemp SRL” manufactured by Kyodo Yushi Co., Ltd.) containing a low viscosi...

AI Technical Summary

Benefits of technology

[0005] In order to achieve the above object, the present invention provides a grease composition comprising a base oil having a dynamic viscosity at 40° C. of 20 to 50 mm2 / s; a urea compound as a thickening agent in an amount of 8 to 30% by weight with respect to total weight of the grease; at least one antirust additive selected from carboxylic acids, carboxylate salts, and ester-based antirust additives in an amount of 0.1 to 10% by weight per single additive with respect to total weight of the grease and in an amount of 0.1 to 15% by weight in total of the additive with respect to total weight of the grease, and a rolling device into which the above grease composition is charged.

Problems solved by technology

However, such a grease composition achieves a low torque but ester-based synthetic oil are generally insufficient in heat resistance and are problematic in seizure life.

Moreover, rolling bearings have widely been used in engine auxiliaries of automobiles, such as an alternator, but they have many chances to come into contact with water.

However, the sulfonate salt has a problem that it promotes generation of hydrogen owing to degradation of a grease composition and is apt to induce flaking involving white texture change caused by the hydrogen (hereinafter referred to as “white texture flaking”).

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