BALL SCREW DEVICE, POWER CONVERSION MECHANISM, ELECTRICALLY-DRIVEN POWER STEERING DEVICE, AND PROCESS OF MANUFACTURE OF BALL SCREW DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a ball screw device of which quality evaluation is easy.SOLUTION: This ball screw device comprises a screw shaft having a thread groove formed at its outer circumferential surface, and a cylindrical nut 60 threadably connected to the thread groove of the screw shaft through a plurality of balls. The nut 60 is formed with a pair of fixing holes to each of which a deflector is installed, and a communication groove 67 communicated with a pair of fixing holes, opened to an outer circumferential surface 64 of the nut 60 and having a ball 62 rotatable there. A width W of an opening part 67a in the communication groove 67 is shorter than a diameter D1 of the ball 62.