Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Nitrogen and heavy metal – or nitrogen and aluminum – in the...
Patent
1997-06-23
1999-07-13
Howard, Jacqueline V.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Nitrogen and heavy metal, or nitrogen and aluminum, in the...
508272, C10M13518, C10M13700
Patent
active
059226544
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to lubricant compositions for application to rotating members and sliding members of various industrial machines, vehicles, etc. In particular, this invention relates to lubricant compositions which are suitable for application to parts required to have load bearing properties and extreme-pressure properties or parts susceptible to wear, such as parts placed under a high load or having a high specific sliding, and are also suitable for application to machines and apparatus which are used at high temperatures.
More specifically, the present invention relates to lubricant compositions which are suitable for use as greases to be applied to rolling mechanical parts and mechanical parts which roll while sliding, such as rolling bearings, e.g., tapered roller bearings and four-point contact ball bearings, constant-velocity joints (CVJ), linear guides (L/G) for use in positioning apparatus, ball screws (B/S), and cross roller bearings for use in megatorque motors, for the purposes of improving the seizure resistance of rolling parts and parts which roll while sliding (hereinafter referred to as rolling/sliding parts), inhibiting the heat generation caused by sliding friction, etc., and are also suitable for use as various lubricating oils such as engine oils and gear oils.
BACKGROUND ART
Greases as a kind of lubricant compositions are being extensively used for rolling members and sliding members of various industrial machines, vehicles, etc. However, especially in the aforementioned apparatus which are used under a high load or have rolling/sliding parts required to be lubricated, if the use conditions therefor become severe (load increase, oil film deficiency due to sliding friction, etc.), the lubrication of the rolling parts thereof, in particular, the rolling/sliding parts thereof, is apt to become boundary lubrication. As a result, galling, seizure due to thermal deterioration of the lubricant, etc. occur to significantly reduce the lubricity life of the parts. For maintaining satisfactory lubrication in such environments, it is indispensable to improve lubricity life by improving load bearing properties or reducing frictional resistance to inhibit heat generation, but the attainment thereof largely depends on the properties of greases.
For example, in tapered roller bearings, the lubricity life of the inner-ring cone back face rib and of the edge of each roller, which bear an axial load, becomes a problem. Namely, since the life of a tapered roller bearing is considerably influenced by the sliding speed and the contact area pressure at the rib, the grease used therein is required to inhibit heat generation and have load bearing properties. In a CVJ, a rolling/sliding movement occurs because the driving shaft on the differential gear side forms an angle with the idler shaft on the wheel side. For the reason, the lubrication in a CVJ is apt to become boundary lubrication and the friction generated therein influences the efficiency of power transmission and heat generation. Hence, use of a grease effective in improving frictional properties and inhibiting heat generation improves the performance of a CVJ and leads to the prolongation of durability life.
A generally employed expedient for mitigating the problem described above is to incorporate an extreme-pressure additive to a grease. Known extreme-pressure additives for greases include solid lubricants such as MoS.sub.2, sulfur, phosphorus, or sulfur-phosphorus organic compounds, organomolybdenum compounds such as a molybdenum dialkyldithiocarbamate (MoDTC) and a molybdenum dialkyldithiophosphate (MoDTP), and a zinc dialkyldithiophosphate (ZnDTP). MoDTC's, MoDTP's, and ZnDTP's are regarded as more effective than MOS.sub.2 and sulfur-phosphorus organic compounds.
Many proposals have been disclosed on the technique of incorporating extreme-pressure additives comprising organomolybdenum compounds or ZnDTP's into greases to obtain grease compositions having different properties according to the intended uses. For
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Iso Kenichi
Kuraishi Jun
Naka Michiharu
Yamazaki Masahiko
Yokouchi Atsushi
Howard Jacqueline V.
NSK Ltd.
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