To provide a screw and a driver bit in which when a tip of a driver bit is to be engaged with a screw driving slot, even though a little displacement is found between the axes of the screw driving slot and the driver bit, they can be easily engaged with each other, and transmission of the driving torque is improved to achieve a smooth screw tightening work.
A three-pronged screw driving slot 4 having three engagement grooves 41 is formed on the head of the screw. The sectional shapes of an engagement internal wall 412 of the engagement groove 41 and an engagement side face 812 of an engagement vane 81 of the driver bit 6 are respectively hyperbolic in form. The shape of the hyperbola is determined so that in the state in which a drive projection 8 of the driver bit is coaxially engaged with the driving slot 4, and a clearance is left between the engagement internal wall 412 and the engagement side face 812, and the engagement vane 81 is rotated to be brought into contact with the engagement internal wall 412 of the engagement groove 41 at external peripheral side positions S1-S3 for driving torque transmission.
COPYRIGHT: (C)2010,JPO&INPIT
ISHIHARA MASAKAZU
TOYOOKA TOSHIMASA
| JP2000170729A | 2000-06-20 | |||
| JP2006068891A | 2006-03-16 | |||
| JPS51156596U | 1976-12-13 | |||
| JPH07506300A | 1995-07-13 |