| 摘要 |
1,266,132. Drilling machine. A. P. L. THOMAS. 12 March, 1969 [12 Dec., 1967], No. 56308/67. Heading B3C. [Also in Division F2] A self-contained machining head comprising a threaded spindle 14 drivable by motor M and axially movable by a lead nut 11 drivable by motor F, the spindle and lead nut being rotatable in the same direction, is provided with a master switch which, in one embodiment (as shown), upon actuation, connects the motor F to a current supply, and two further switches subsequently operated in succession in response to changes in the axial position of the spindle, respectively to connect the motor M and one of the motors via manually adjustable thyristors or equivalent electronic devices to the supply, and disconnect the motor F from the supply. In a second embodiment (not shown), the hand of the threads of the lead nut and spindle are opposite to those of the first embodiment, the master switch connects motor M to the current supply, and the two further switches respectively operate to connect motor F and disconnect motor M. The motors may be mounted coaxially (Fig. 1) or side-by-side (Fig. 2). The spindle 14, which is splined to the rotor 6 of motor M is connected through a gear-box 17 to one or more guide bars 15 axially movable with the spindle, the two further switches being located adjacent one guide bar for actuation thereby. The positions of the switches are adjustable relative to the guide bar. The motor which is first disconnected from the supply may, at such time, be connected to a D.C. supply to stop it instantaneously. Means may be provided for inching each motor independently to permit correct positioning of the three switches relative to the guide bar 15. The gear-box may include one or more toolcarrying spindles 18. A clutch may be provided to cause simultaneous rotation of the spindle and lead nut at the same speed; the clutch engaging after disconnection of the one motor and before disconnection of the other. As shown in Fig. 2 the clutch comprises a part 37 secured to the lead nut and a part 36 rotatable with the spindle. Where the motors are arranged side-by-side, the motor offset from the axis of the spindle may be connected by toothed belt 32 either to the lead nut or to the spindle. When both motors are running the speeds are such that the spindle is fed axially slowly toward the work. A third switch can be provided for disconnecting the second-actuated motor from the supply. |
