JPH0673449U - Grease lubricated rolling bearing for high loads - Google Patents

Abstract

(57) [Summary] [Purpose] Sufficient durability is obtained under a high load in a vacuum.
In addition, the grease-lubricated bearing has good workability and safety in the coating formation process. [Structure] A hard layer 7 made of a coating layer of TiN or TiCN is formed on a surface of a bearing component where rolling friction or sliding friction occurs. For example, the hard layer 7
Is applied to the rolling surfaces of the inner ring 2 and the outer ring 3 and the surface of the rolling element 4. Further, grease is sealed between the bearing components, and the grease lubricating film 8 is formed on the surface of the hard layer 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a grease lubricated rolling bearing which is required to have durability under severe conditions such as high load and vacuum.

[0002]

[Prior art]

 General grease cannot be used for rolling bearings used in vacuum. For this reason, the surfaces of bearing parts that cause rolling or sliding friction, such as the rolling surfaces of inner and outer rings and the surfaces of rolling elements, are made of soft metals such as gold, silver, and lead, and layered materials such as molybdenum disulfide. A solid lubricating film is formed to lubricate the bearing. However, the solid lubricating coating has a problem of poor durability. On the other hand, a grease that can be used under vacuum has also been developed, and its use has been put to practical use.

Under normal load conditions, grease-lubricated rolling bearings have greater durability than rolling bearings with a solid lubricating coating, but at high loads, boundary lubrication occurs and wear powder from metal contact causes When mixed with the grease, it deteriorates the grease and sufficient durability cannot be obtained. As described above, under a high load, it is difficult to obtain sufficient durability with both grease lubrication and the solid lubricating coating.

As a solution to such a problem, a hard layer coated with TiC is formed on the surface of the bearing component, and a solid lubricating coating is formed on the hard layer, so that a high load can be obtained. Proposals have been made to improve the durability of solid lubricating coatings.

[0005]

[Problems to be solved by the device]

 However, when a hard layer of TiC is formed by ion plating or the like, it is necessary to use acetylene gas or methane gas, and these gases are highly flammable and it is difficult to control the gas pressure. Therefore, there are problems in terms of formation conditions and workability. As a solid lubricating coating, a bearing with a TiN layer formed on the rolling surface of the raceway has also been proposed. According to this, there is no problem in terms of flammability because the inert gas nitrogen gas is used. . However, it is considered that it is difficult to obtain sufficient durability under high load, because lubrication is performed only by the solid lubricating coating without using grease.

An object of the present invention is to provide a grease-lubricated rolling bearing for high load, which has sufficient durability under high load and has good workability and safety in the process of forming a coating.

[0007]

[Means for Solving the Problems]

 The grease-lubricated rolling bearing for high loads of the present invention has a hard layer made of a coating layer of TiN or TiCN formed on the surface of the bearing component where rolling or sliding friction occurs, and the grease is interposed between the bearing components. It was made to.

[0008]

[Action]

 The hard layer of TiN or TiCN formed on the friction surface of the bearing component does not easily deform even under a high load and reliably supports the load. Moreover, since it is grease lubricated, the lubricating action is maintained for a long period of time while the base oil is retained by the thickener, and sufficient durability can be obtained. It is considered that grease lubrication under high load is in a boundary lubrication state in which metal contact and lubricant are mixed, but the hard layer of TiN or TiCN suppresses local peeling and wear due to metal contact. This prevents the grease from deteriorating. Because of these, the durability can be improved when used under severe conditions such as vacuum and high load.

Further, the hard layer is made of TiN or TiCN, and an inert nitrogen gas is used for its formation, so that it is safe to handle, the gas pressure is easily controlled, and the formation conditions and workability are low. The problem of can be solved.

[0010]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a grease-lubricated rolling bearing in which the present invention is applied to a deep groove ball bearing. The bearing 1 is made up of bearing components such as an inner ring 2, an outer ring 3, a plurality of rolling elements 4 interposed between the inner and outer rings 2 and 3, and a cage 5 for holding the rolling elements 4 at predetermined positions. A hard layer 7 made of a coating layer of TiN (titanium nitride) or TiCN (titanium carbonitride), which has the same high rigidity as TiC, is formed on the rolling surfaces of the inner ring 2 and the outer ring 3 and the surface of the rolling element 4. The grease lubrication film 8 is formed on the surfaces of the bearing parts by enclosing grease between the parts. The hard layer 7 is formed by ion plating to have a thickness of about 1 to 5 μm. In addition to this, the hard layer 7 can be formed by a physical vapor deposition (PVD) sputtering method, a chemical vapor deposition (CVD) method, a plasma CVD method, or the like.

FIG. 2 shows the result of a test conducted to confirm the effectiveness of the hard layer 7 made of TiN. This test was conducted using a bearing life tester for outer space, and the durability of untreated bearings without coating and bearings with a TiN hard layer formed on the inner and outer rings and rolling elements under grease lubrication under high load was tested. It is a comparison. The durability was measured by the method of stopping the operation when the detected torque value reached the peak value. The test bearings and test conditions are as follows. Test bearing: Angular ball bearing (inner diameter 25 mm, outer diameter 47 mm, width 12 mm) Lubricant: Fluorine vacuum grease (Braycoat 601 (trade name)) Rotation speed: 300 rpm In FIG. 2, for comparison with a solid lubricating coating, Results of Pb-treated bearings on the inner and outer races and rolling elements are also attached. The Pb coating was formed by ion plating.

As is clear from FIG. 2, the TiN-treated bearing exhibits the highest durability, which is twice or more that of the untreated bearing and 6 times or more of that of the Pb-treated bearing. As described above, the effect of the hard layer 7 made of TiN is remarkably exhibited under a high load.

When the hard layer 7 is made of TiCN, the experimental results are omitted, but it is assumed that the same durability as TiN can be obtained. Moreover, the coating of the hard layer of TiN or TiCN by the ion plating method can be easily performed by using the inert nitrogen gas as described above, and the workability is high, so that the productivity of the bearing is also improved.

Although the hard layer 7 is formed on the inner and outer races 2 and 3 and the rolling element 4 in the above embodiment, it may be formed only on the rolling element 4 or only on the rolling surfaces of the inner and outer races 2 and 3. . Further, the present invention can be applied not only to ball bearings but also to all types of rolling bearings such as roller bearings. When it is applied to a roller bearing, it is desirable to apply the above-mentioned hard layer to the roller end surface that becomes a sliding friction surface, the collar surface of the bearing ring, and the like.

[0015]

[Effect of device]

 Since the high-load grease-lubricated rolling bearing of the present invention has a hard layer made of a coating layer of TiN or TiCN on the friction surface and grease is interposed, this hard layer and the use of grease are mixed. As a result, it is possible to improve durability when used under severe conditions such as under high load. Moreover, since the hard layer is made of TiN or TiCN, the gas used for its formation is an inert nitrogen gas, which makes it safe to handle and easy to control the gas pressure. Can solve the problem of reliability and improve the productivity of bearings.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a bearing according to an embodiment of the present invention.

FIG. 2 is a comparison diagram of durability between this device and a conventional example.

[Explanation of symbols]

2 ... Inner ring, 3 ... Outer ring, 4 ... Rolling element, 5 ... Cage, 7 ... Hard layer, 8 ... Grease lubricating film

Claims (1)

[Scope of utility model registration request] 1. A high-load grease lubrication in which a hard layer made of a coating layer of TiN or TiCN is formed on a surface of a bearing component that causes rolling friction or sliding friction, and grease is interposed between the bearing components. Rolling bearing.