Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1998-07-02
2001-01-23
Thibodeau, Paul (Department: 1773)
Bearings
Rotary bearing
Plain bearing
C384S286000, C384S288000
Reexamination Certificate
active
06176621
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a rotary slide bearing part of a rotary slide slit bearing for supporting a rotary shaft thereon in a rotatable manner on an axis, and a producing method therefor.
A conventional rotary slide slit bearing has a pair of rotary slide bearing parts to which the rotary slide slit bearing is divided by a split plane in which an axis of the bearing is arranged. At least one of the rotary slide bearing parts has a circumferentially extending groove in a cylindrical bearing surface of the bearing.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a rotary slide bearing part of a rotary slide slit bearing for supporting a shaft thereon in a rotatable manner on an axis, by which part a cavitation of a lubricant between a bearing surface and the shaft to be borne thereon is restrained, and to provide a method for producing the rotary slide bearing part.
A rotary slide bearing part of a rotary slide slit bearing for supporting a rotary shaft thereon in a rotatable manner, comprises a first bearing surface portion adapted to be arranged adjacent to a second bearing surface portion of another rotary slide bearing part of the rotary slide slit bearing, a load from the shaft to be borne by the first bearing surface portion being larger than a load from the shaft to be borne by the second bearing surface portion, wherein
the first bearing surface portion includes a fluidal pressure generating surface facing close to the shaft to generate a fluidal pressure between the fluidal pressure generating surface and the shaft, a main groove arranged at an circumferential end of the first bearing surface portion adjacent to the second bearing surface portion, and a sub-groove extending from the main groove in a circumferential direction of the first bearing surface portion, and an axial width of the sub-groove is smaller than that of the main groove.
A combination of the main groove arranged with a relatively large axial width at the circumferential end of the first bearing surface portion adjacent to the second bearing surface portion, and the sub-groove extending with a relatively small axial width from the main groove in the circumferential direction of the first bearing surface portion releases through the sub-groove to the main groove an abrupt lubricant pressure change or surge caused by a significantly large variation of a load from the shaft or of a position of the shaft on the first bearing surface portion so that a lubricant cavitation is restrained, and prevents a load bearing capacity of the first bearing surface portion from being significantly deteriorated by the release of the pressure from the first bearing surface.
When the second bearing surface portion includes another fluidal pressure generating surface facing close to the shaft to generate a fluidal pressure between the another fluidal pressure generating surface and the shaft, and a lubrication groove arranged adjacent to the first bearing surface portion or the main groove and extending in a circumferential direction of the second bearing surface portion, it is preferable for the axial width of the sub-groove to be smaller than that of the lubrication groove, so that the released abrupt lubricant pressure change or surge from the first bearing surface is absorbed effectively by the lubrication groove.
It is preferable for the sub-groove to extend continuously circumferentially on the first bearing surface in such a manner that both of circumferential ends of the sub-groove communicate fluidally to the second bearing surface portion, so that the abrupt lubricant pressure change or surge from the first bearing surface is released effectively to the second bearing surface portion through both of the circumferential ends of the first bearing surface, and the abrupt lubricant pressure change or surge at a circumferential intermediate or central point of the first bearing surface portion can be released securely.
When the main groove is arranged adjacent to the lubrication groove, the pressure release from the sub-groove is performed more effectively.
It is preferable for a radial depth of the main groove and/or sub-groove from the fluidal pressure generating surface decreases gradually in a direction from the circumferential end of the first bearing surface portion toward the circumferential intermediate or central point of the first bearing surface portion, so that a turbulent flow on the main groove and/or sub-groove is restrained.
When a surface of the rotary shaft moves on the first bearing surface portion from the circumferential end of the first bearing surface portion toward another circumferential end thereof, that is, the surface faces close to the sub-groove just after passing the main groove, the pressure in the sub-groove is kept appropriate. It is preferable for the sub-groove to be prevented from extending axially to an axial end of the first bearing surface portion, so that the pressure in the sub-groove is prevented from decreasing significantly.
When the radial depth of the sub-groove from the fluidal pressure generating surface is minimum at the circumferential or central intermediate point of the first bearing surface portion, the lubricant pressure at the circumferential or central intermediate point of the first bearing surface portion is kept high to increase the load bearing capacity of the first bearing surface portion. It is preferable for an imaginary line extending between or joining both of the circumferential ends of the first bearing surface portion to be prevented from being substantially parallel to a direction of a maximum load.
A method of the present invention for producing a rotary slide bearing part of a rotary slide slit bearing for supporting a rotary shaft in a rotatable manner on an axis, comprises the steps of:
forming a curved bearing surface portion on the rotary slide bearing part, and
moving a first machining portion of a machining tool along a first curved machining line to make a main groove circumferentially extending in the curved bearing surface portion, and a second machining portion of the machining tool along a second curved machining line within an axial width of the main groove to form a sub-groove circumferentially extending in the curved bearing surface portion,
wherein a curvature radius of the first curved machining line is smaller than that of the second curved machining line, and the axial width of the first machining portion is larger than that of the second machining portion.
The machining tool is a cutter for cutting process, and/or a die(s) of a press machine for plastic deformation process. The curved bearing surface portion may be formed by the cutter, die(s), and/or molding.
Since the curvature radius of the first curved machining line is smaller than that of the second curved machining line, and the axial width of the first machining portion is larger than that of the second machining portion, the main groove and the sub-groove are formed easily without a mechanical interference therebetween.
When a center of curvature of the first curved machining line is substantially identical to that of the second curved machining line, the first and second curved machining lines are easily formed. When a center of curvature of the curved bearing surface portion is apart from centers of curvatures of the first and second machining line, desirable shapes of the main groove and the sub-groove are formed easily. When the center of curvature of the curved bearing surface portion is between the curved bearing surface portion and centers of curvatures of the first and second machining line, desired tapered shapes of the main groove and the sub-groove are formed easily.
When the second curved machining line extends circumferentially in the rotary slide bearing part from a circumferential end of the curved bearing surface portion to another circumferential end thereof to form the sub-groove, a continuous machining along the second curved machining line in the rotary
Ito Noriyoshi
Kimura Arihiro
Kuroda Koji
Murakami Hiroshi
Naitoh Hiroshi
Browdy and Neimark
Daido Metal Company Ltd.
Rickman Holly
Thibodeau Paul
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