Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1999-12-16
2001-10-02
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S470000, C508S106000
Reexamination Certificate
active
06296393
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rolling bearing filled with a lubricant-containing polymer and a process for the production thereof.
BACKGROUND OF THE INVENTION
In general, the space formed by the outer race, inner race (bearing race) and rolling elements of a rolling bearing is filled with a lubricant or grease to lubricate the rolling bearing. However, such a lubricant or grease is a liquid or semisolid material that can be scattered or fluidized during the operation of the bearing. In order to prevent the scattering or fluidization of the lubricant or grease, it is arc normally practiced to seal the rolling bearing with a seal plate or the like. Therefore, it has been difficult to lubricate a small-sized bearing for special purpose with a lubricant or grease.
In order to overcome these difficulties, it has recently been proposed to fill the space formed by the inner race, outer race and rolling elements of the bearing with a polymer containing a lubricant. For example, JP-B-63-23239 (The term “JP-B” as used herein means an “examined Japanese patent application”) discloses an arrangement involving the filling of the space formed by the inner race, outer race and rolling elements of a bearing with a lubricant-containing polymer comprising a grease and a polyethylene (plastic grease).
During its operation, the above proposed rolling bearing filled with a lubricant-containing polymer allows the lubricant-containing polymer to gradually release the grease as a lubricating component so that it can be lubricated over an extended period of time.
However, this kind of a lubricant-containing polymer-filled rolling bearing is disadvantageous in that since the lubricant-containing polymer normally fills the entire part of the space formed by the outer race and the inner race excluding that occupied by the rolling elements, the rotation of the rolling elements is impeded or a powder that enters into the clearance between the rolling elements and the inner race and outer race is generated during the operation of the bearing to cause so-called biting or vibration of the entire shaft, thereby resulting in the drastic deterioration of the performance of the bearing. Furthermore, there are some cases that these troubles are accompanied by the rise in the temperature of the bearing.
In order to overcome these difficulties, JP-A-8-312652 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”)), which corresponds to U.S. Pat. No. 5,588,751, proposes an approach involving the formation of a layer made of a lubricating component between the cage and the rolling elements prior to the packing of a lubricant-containing polymer for the purpose of preventing the lubricant-containing polymer and the rolling elements from coming in direct contact with each other.
As such a lubricant-containing polymer-filled rolling bearing there is known a deep groove ball bearing comprising an inner race and an outer race the edge face of which are flush with each other, cylindrical roller bearing, self-aligning roller bearing or the like. In order to fill such a rolling bearing with a lubricant-containing polymer, a full-pack process is normally employed which comprises packing the lubricant-containing polymer in such an arrangement that the edge face of the bearing and the lubricant-containing polymer are flush with each other.
These lubricant-containing polymer-filled rolling bearings, including ordinary deep groove ball bearing, cylindrical rolling bearing and self-aligning roller bearing, have a structure such that the edge face of the inner race and the outer race are flush with each other and the case does not protrude from the edge face of these rings and thus can be relatively easily produced in the foregoing full-pack form.
However, referring to the foregoing rolling bearing having a lubricating component layer interposed between the rings and the rolling elements, there is no specifications concerning the predetermination of the kind of lubricating component to be used and the thickness of the lubricant layer, making it occasionally impossible to obtain improvement in lubricating properties. In particular, in the case where a lubricant is used as the lubricating component, a thick layer cannot be formed to occasionally result in an insufficient effect of improving the lubricating properties.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a lubricant-containing polymer-filled rolling bearing which securely allows smooth rotation over an extended period of time.
It is another object of the present invention to provide a process for the production of such a lubricant-containing polymer-filled rolling bearing.
However, unlike the foregoing ordinary lubricant-containing polymer-filled rolling bearing, a rolling bearing having a structure such that the vertical (crosswise) thickness of the inner race and the outer race differ from each other and the cage protrudes from the edge face of the inner race or outer race, that is, the axial edge face of the inner race and the outer race are not flush with each other, i.e., tapered roller bearing or the like, can be hardly produced in a form corresponding to the foregoing full-pack form by, e.g., by means of a simple method which includes heat-forming components sandwiched between flat plates.
Accordingly, it has been practically difficult to provide a lubricant-containing polymer-filled rolling bearing having such a structure.
It is therefore a further object of the present invention to provide a lubricant-containing polymer-filled rolling bearing comprising a cage covered with a lubricant-containing polymer which can be produced by a simple method even in the form of a rolling bearing having a structure such that the vertical thickness of the inner race and the outer race differ from each other and the cage protrudes from either one of the edge face of the inner race and the outer race.
It is a still further object of the present invention to provide a process for the production of such a rolling bearing.
These and other objects of the present invention will become apparent from the following detailed description and examples.
These and other objects of the present invention are accomplished with a lubricant-containing polymer-filled rolling bearing comprising a lubricant-containing polymer packed in the space formed by an outer race, an inner race and rolling elements, wherein the lubricant-containing polymer is packed with the interposition of a grease layer having a thickness of from 10 &mgr;m to 1,000 &mgr;m formed at least on the inner peripheral surface of the outer race, the outer peripheral surface of the inner race and the surface of the rolling elements.
These and other objects of the present invention are accomplished with a process for the production of a lubricant-containing polymer-filled rolling bearing, which comprises assembling a rolling bearing, forming a grease layer having a thickness of from 10 &mgr;m to 1,000 &mgr;m on at least the inner peripheral surface of an outer race, the outer peripheral surface of an inner race and the surface of rolling elements, filling the space formed by the outer race, the inner race and the rolling elements with a lubricant-containing polymer, and then allowing the lubricant-containing polymer to solidify.
The lubricant-containing polymer-filled rolling bearing according to the present invention comprises a layer composed of a grease having a predetermined thickness of from 10 &mgr;m to 1,000 &mgr;m to have assured improvement in lubricating properties. The use of a grease makes it possible to form a layer having a thickness as great as about 1,000 &mgr;m that allows a great clearance between the lubricant-containing polymer and the rolling elements or the outer and inner races and hence assures smooth rotation.
These and other objects of the present invention are accomplished with a lubricant-containing polymer-filled rolling bearing comprising a pair of races, i-e., inner race and outer race, a plurality of roll
Aihara Nariaki
Sorimachi Morio
Yabe Toshikazu
Hannon Thomas R.
NSK Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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