Patent GB-612988-A (GB)
Title: Automatic feed mechanisms for tapping and other machines
IPC: B23Q5/04
Filed: 1946-06-13
Abstract: 612,988. Drilling; tapping. GAUVREAU, V. June 13, 1946, No. 17692. Convention date, June 6, 1945. [Class 83 (iii)] In an automatic feed mechanism for tapping &c. machines comprising a spindle movable axially by displacement under centrifugal action of a number of weights rotatable in unison with the spindle, means are provided for reversing the rotation of the spindle when it reaches a predetermined axial position and for automatically. holding the weights against movement under centrifugal action during the reverse rotation. The spindle 10 carries a tool collet 45 and is slidably disposed within a quill 22 having a slot 22a through which passes a key 14 connecting the spindle with a collar 13 bearing against an axial extension of a hollow conical member 19 connected for rotation with the quill by a setscrew 51 whose inner end is engaged in the slot 22a. The quill is keyed to the shaft of an electric motor 24 and is secured to a second hollow conical member 42 between which and the member 19 is a disc 37, Fig. 3, having arcuate slots 38 to accommodate the weights 20. The centre line of each slot passes a point 39 of minimum distance from the axis of rotation and extends to a point 40 at a greater distance from the axis of rotation than the point 39. A spring 12 is interposed between the collar 13 and a collar 15 which is keyed to the quill and also provides a seat for a spring 18 bearing upon the member 19. When the motor rotates the disc 37 in the direction of the arrow 46 the weights are displaced outwardly in the slots 38 axially displacing the cone 19 and the spindle 10 to a predetermined position at which the rim of the cone engages the cam end 30 of a lever extension 29 to deflect a lever 27 producing axial displacement of a rod 28 which effects operation of an electric switch 26 to reverse the motor. A spring 29a serves to return the lever to its undeflected position. During the stationary interval before the reversal of the motor, the inertia of the weights 20 causes them to roll inwardly in the slots 38 until they come to rest adjacent to the point 39. The spring 18 then returns the cone 19 to the position shown in Fig. 1. Thus, when the reverse rotation takes place, the inertia of the weights 20 holds them adjacent to the point 40. Since the point 40 is at a greater radial distance from the axis of rotation than the point 39, the weights are locked in a non- feeding position. During the reverse rotation, the spring 12 assists to return the spindle 10. The return of the cone 19 to its undisplaced position actuates a second electric switch 50 which reverses the motor to re-establish the feeding cycle or, alternatively, actuates an auxiliary unit in which event a manuallyoperated switch is provided to re-establish the cycle. For work where a higher deceleration of the spindle 10 is required, an electromechanical brake of known construction may be fitted to the motor shaft. When the mechanism is used for tapping, a lead screw attachment is added by unscrewing a sealing cap 32 and replacing it with the attachment, the housing 33, Fig. 2, of which is provided with a screw-thread for this purpose, the cap 32 being replaced at the end of the housing 33. A spindle 34 carrying a threaded collar 35 for engagement with a threaded sleeve 36 replaces the spindle 10. The motor is cooled by air induced through an inlet 49 and discharged through ducts 48 by an impeller 47.