| 摘要 |
A drilling or milling head, especially for printed circuit board milling machines and/or engraving machines, having a collet chuck (11) which can be actuated by a rapid change mechanism and which is driven by a transmission. The collet chuck is opened by an axial displacement relative to a clamping sleeve (50), with the force necessary for the displacement being transmitted via a friction clutch. The transmission includes a ball bearing (9) whose balls (12) are moved around a common axis in a concentric manner by a driving part (6) fixed on a motor drive shaft (5). In addition, the balls are mounted between two bearing surfaces (13, 14) which are aligned in a concentric manner with regard to the axis and which have a circular cross-section. The balls are at least partially engaged with the bearing surfaces in a positive manner. The bearing surfaces, one of which can rotate and the other of which is fixed, are axially aligned and symmetrical to one another, and they are concavely curved with the maximum distance between the convex surfaces being equal to the ball diameter. The balls are subjected to an axial force. The drilling or milling head of the invention makes it possible to drive the collet chuck at a different speed than that of the motor.
|
