Thrust roller bearing and cage

A cage holding a needle roller in a pocket for accommodating said needle roller, wherein the cage has an upper member and a lower member for sandwiching the needle roller between them;

• wherein the upper member and the lower member are subjected to caulking and are fixed to each other at a radially inner end portion and a radially outer end portion of each of them;
• wherein a roller holding portion provided in said pocket has a length less than a length of said needle roller, and within a range of 30% to 80% of a length in a radial direction of said pocket;
• wherein a flat portion having a height less than that of the roller holding portion, measured in a cross-section perpendicular to a plane along which the cage extends, is provided between the radially inner and outer end portions of the cage and an end portion of said needle roller;
• and
• wherein said pocket extends to the flat portion.

A thrust roller bearing, comprising:

• a plurality of rollers;
• and
• a cage made of metal and holding said roller so as to sandwich the same with an upper member and a lower member;
• wherein
• a nitrocarburized case is formed to a depth in a range larger than 3 μm and smaller than 100 μm in a surface of said cage.

A thrust roller bearing, comprising:

• a plurality of rollers;
• and
• a cage made of metal and holding said roller so as to sandwich the same with an upper member and a lower member;
• wherein
• in said cage, a hardened case is formed to a depth in a range larger than 3 μm and smaller than 100 μm in its surface,
• said upper member and said lower member are superposed and bent in at least one of a radially outer side end portion and a radially inner side end portion and subjected to caulking, and
• a nitrocarburized case plastically deforms in the caulked portion.

A cage for holding a roller, the cage comprising an upper member having a pocket for accommodating the roller and a roller holding portion in the pocket, and a lower member having a corresponding pocket and roller holding portion, to sandwich and hold the roller between the upper member and the lower member;

• wherein
• a hardened case is formed to a depth in a range larger than 3 μm and smaller than 100 μm in a surface portion of said cage;
• the upper member and the lower member are superposed on each other at inner and outer radial portions of their respective holding portions such that respective radially extending surfaces of the holding portions contact each other;
• the upper member and the lower member are caulked at the inner and outer radial portions of their respective holding portions such that an end portion of one of the upper and lower members surrounds a first face, an end face and a second face of an end portion of the other of the upper and lower members;
• the upper member and the lower member each have a flat portion having a height less than that of their respective roller holding portions, measured in a cross-section perpendicular to a plane along which the cage extends, between inner and outer radial end portions of the member and an end portion of the roller;
• and
• the roller holding portions have a length in a radial direction less than a length of the roller, and the pockets extend to the flat portion.

A cage holding a roller so as to sandwich the same with an upper member and a lower member;

• wherein
• a hardened case is formed to a depth in a range larger than 3 μm and smaller than 100 μm in a surface portion of said cage,
• said upper member and said lower member are superposed and bent in at least one of a radially outer side end portion and a radially inner side end portion and subjected to caulking, and
• said hardened case plastically deforms in the caulked portion.

A thrust roller bearing, comprising:

• a plurality of rollers;
• and
• an annular cage having a plurality of pockets for holding said rollers respectively, and a roller holding portion in each said pocket;
• wherein the cage has an upper member and a lower member for sandwiching said rollers between them;
• wherein the upper member and the lower member are subjected to caulking and are fixed to each other at a radially inner end portion and a radially outer end portion of each of them;
• wherein a flat portion having a height less than that of the roller holding portions, measured in a cross-section perpendicular to a plane along which the cage extends, is provided between the radially inner and outer end portions of the cage and an end portion of each said roller;
• wherein the roller holding portions each have a length in a radial direction less than a length of each of said rollers, and the pockets extend to the flat portion;
• wherein an end face of each of said plurality of rollers is an F end face, and
• wherein end face accuracy is at most 30 μm.

A cage for holding a roller, the cage comprising an upper member having a pocket for accommodating the roller and a roller holding portion in the pocket, and a lower member having a corresponding pocket and roller holding portion, to sandwich and hold the roller between the upper member and the lower member;

• wherein
• a hardened case is formed to a depth in a range larger than 3 μm and smaller than 100 μm in a surface portion of said cage;
• the upper member and the lower member are superposed on each other at inner and outer radial portions of their respective holding portions such that respective radially extending surfaces of the holding portions contact each other;
• the upper member and the lower member are spot-welded to each other;
• the upper member and the lower member each have a flat portion having a height less than that of their respective roller holding portions, measured in a cross-section perpendicular to a plane along which the cage extends, between inner and outer radial end portions of the member and an end portion of the roller;
• and
• the roller holding portions have a length in a radial direction less than a length of the roller, and the pockets extend to the flat portion.