| 摘要 |
PROBLEM TO BE SOLVED: To make any plastic deformation hard to take place in an intermediate part by forming a hardened layer across the total width of the intermediate part positioned between adjacent inner raceway tracks from the inner raceway track parts in plural lines and making the outer diameter of a hardened layer formed on this intermediate part smaller than the outer diameter of a hardened layer formed in inner raceway track parts in plural lines. SOLUTION: The outer diameter of a hardened layer 12 in an intermediate portion 15 is smaller than the outer diameter of the hardened layer 12 formed on the surfaces of respective inner raceway tracks 10, 10. Therefore, thickness and size of parts other than the hardened layer 12 including raw part, etc., existing on the circumference of the hardened layer 12 formed on the inner peripheral surface of the intermediate portion 15 can be secured sufficiently. Also the hardened layer 12 is provided from inner raceway tracks 10, 10 parts in plural lines formed on the inner peripheral surface of an outer ring 5 to an intermediate part 15 exiting between both inner raceway tracks 10, 10. Therefore, the hardness of the intermediate part 15 is increased, and even when any excessive moment is applied to the outer ring 5 and roller bodies 3, 3 ride on the intermediate part 15, plastic deformation is made to hardly take place in this intermediate part 15.
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