Selbstauskuppelnder Werkzeughalter

1,128,968. Tap-holders. ERICKSON TOOL CO. 18 Sept., 1967 [4 May, 1967], No. 42404/67. Heading B3N. A self-releasing tap-holder comprises a housing 2, Fig. 3, adapted to be located in a machine spindle, a collet 41 for holding the tap 44, located in a body 6, and a drive member 8 for transmitting rotation from the housing to the collet. Drive member 8 has dogs 16 which cooperate with dogs 17 on body 6, and pins 11 in the housing co-operate with grooves 9 in member 8. A one-way clutch 46, Fig. 5, comprises a groove 47 in body 6, a pin 50 supporting a spring-urged roller 51, and a groove 52 in housing 2. In operation, housing 2 is rotated in the required direction and drives the tap through drive member 8, body 6, and collet 41. The tap is pulled into the workpiece until housing 2 engages a stop, and dogs 16, 17 are disengaged. Drive member 8 is moved forward slightly against a spring 30 until it abuts a flange 34, but pins and grooves 9, 11 are still in engagement. Accordingly, when the dogs 16, 17 are disengaged and no further torque is transmitted, spring 30 forces drive member 8 to the right, Fig. 3, thus preventing any contact between the dogs, and the drive member and housing continue to rotate. The tap is backed out of the hole by reversing the direction of rotation of housing 2, so that groove 52 rotates until it is engaged by roller 51, whereupon with the dogs disengaged, the housing rotates the collet and tap until the latter moves out of the workpiece, and a spring 19 moves body 6 to again engage the dogs.