Patent GB-687999-A (GB)
Title: Improvements in or relating to machine tools
IPC: B23Q5/52
Filed: 1951-03-27
Abstract: 687,999. Lathes &c. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. March 27, 1951 [March 30, 1950], No. 7061/51. Class 83 (iii). [Also in Group XXIII] A lathe or other machine-tool in which the relative movement between the work and operating tool is limited by a stop is arranged so that when the moving member reaches the stop the connection between the member and its drive is interrupted and it remains urged against the stop by a predetermined force at least equal to the force which moved it to the stop. The predetermined force is maintained at least for the period necessary to complete the machining operation, e.g. a complete revolution when such operation is rotary and a complete stroke when it is rectilinear. The engagement of a stop 36 by a push-button 39 on the tool slide 32 of the lathe shown in Fig. 2 acts through control mechanism to (a) stop the motor 38 driving the feed spindle 33, (b) separate the halves of the nut 35 engaging this spindle, and (c) energize an electromagnet 37 for holding the slide against the stop. The tool slide 32 of the lathe shown in Fig. 3 is moved towards the stop 36 by a piston 48 in a fluid-pressure cylinder 46 and during this movement a forwardly-projecting member 53 of split form on the slide hooks over the enlarged end of a rod 52 projecting from the piston 47 of a second fluid-pressure cylinder 45. When the button 39 engages the stop 36, fluidpressure feeding the slide to the stop is automatically cut off from the cylinder 46 and supplied to the cylinder 45 so as to pull the slide against the stop. Return of the slide is effected by a hand-actuated button 56. The lathe shown in Fig. 4 has a latch 61 which is acted upon by a spring 60, is movable to and from the slide and co-operates with a retractable member 65. When the slide is moved towards the stop by a feed-spindle 33, the latch has been withdrawn to its outer position to allow passage of the slide and is engaged by the member 65. As soon as the slide reaches the stop, the latch is automatically moved inwardly, e.g. by a lever actuated by the slide, and the member 65 is similarly withdrawn so that the spring 60 urges the latch against a projection 64 on the slide; at the same time, the halves of the feed nut 35 are separated by the action of another lever. In another arrangement, the drive to the movable member incorporates a clutch which is constructed as described in Specification 683,792 and arranged so that when the member reaches the stop the clutch is disengaged and springs disposed in the clutch then exercise the predetermined force urging the member against the stop; this clutch is also constructed to re-engage upon reversal of the drive. The clutch comprises a control member for operating electric control devices upon a change in the conditions of the clutch, for example for changing the relative position or direction of movement of the work and tool or the rate of such movement. As applied to a lathe shown in Fig. 12 for operating upon stepped work, clutches 207a, 207b, of this kind are incorporated in the drive from a motor 206 through a feed spindle 204 to a main tool slide 209 and from a motor 211 through a feed spindle 210 to the superposed tool slide 212. In operation, the slide 212 is first moved by the motor 211 into the work until it engages a stop, whereupon the clutch 207b is automatically disengaged but its springs then urge the slide against the stop. At the same time, the control device of this clutch disconnects the motor 211 and starts the motor 206 whereby the part b of the work is machined. When the slide 209 reaches a stop 208a, the clutch 207a is automatically disengaged and the motor 211 restarted in reverse direction to withdraw the slide 212 until it engages a stop with the tool in position to machine the part d of the work upon disengagement of the clutch 207b and re-engagement of the clutch 207a. Similar operation of the clutches under control of stops provides for machining the largest portion of the work. The stops are movable to and from operation positive by electromagnets. The machine is also stated to be applicable to milling, planing, drilling and grinding machines, and machinetools employed for copying.