Patent GB-739804-A (GB)
Title: Improved control mechanism for lathes
IPC: B23Q1/00
Filed: 1952-04-25
Abstract: 739,804. Change-speed control. BOEHRINGER GES., GEB. April 25, 1952 [April 28, 1951], No. 10529/52. Class 80 (2). [Also in Groups XXII and XXXVII] A control mechanism for a lathe having change-speed mechanisms for the spindle and/or the tool feed comprises a plurality of presettable devices co-ordinated to at least one of such transmissions, each of said devices being adapted, when activated, to set up the transmission for a predetermined speed ratio, the presettable devices being adapted to be successively activated by stepwise movable means actuated by a member movable upon completion of one stage of operation to cause the next device to determine the speed ratio of the transmission for the next stage of operation, manually operable selector means being provided to perform the dual function of inactivating the presettable devices and of setting up the speed ratio irrespective of the setting of the devices until the latter are activated again. Headstock and feed drives. In the application of the invention to a turret lathe, a reversible electric motor 48, Fig. 3, which may be of constant speed or two-speed type, drives through gears 226-228 the gears 229-231 respectively associated with electromagnetic multi-disc clutches K2, K1, K3. A fourth gear 233 loosely mounted on the shaft 232 carrying the magnetic clutches &c. may be clutched thereto by a further electromagnetic clutch K4 and meshes with a gear 234 fixed to a shaft 210. Driving connection between shafts 232 and 210 may also be established by a pinion 235 attached to shaft 232 and meshing with a gear 236 loosely mounted on shaft 210, but, adapted to be clutched thereto by electromagnetic clutch K5. This shaft 210 may be driven at six different speeds using a constant speed motor. The shaft 210 drives a shaft 237 through gears 216, 217, the latter shaft carrying loose gears 223, 219 driven from shaft 237 and gears 218, 222 respectively. The loose gears may be selectively clutched to shaft 238 by electromagnetic clutches K6, K7, and the twelve speeds thus obtained transferred to the workspindle 200. For a high finish the spindle 200 may alternatively be driven from a shaft 239 by belt means 241 similar to the manner described in Specification 707,243, [Group XXII], the shaft 239 being driven from the gear 223 on shaft 238 which engages a gear 242 splined on shaft 239 and moved into engagement by a handle 243, Fig. 2, arranged on the headstock. The feed transmission. A shaft 244, Fig. 3, having gears 245-247 fixed thereto may be driven from a shaft 208 through any one of three gears meshing with the gears 245-247 and adapted to be clutched to shaft 208 by electromagnetic clutches KI, KII and KIII respectively. Shaft 244 drives the feed shaft 18 through similar pairs of gears selectively operated by the clutches KIV, KV, KVI, thus providing nine feed speeds. A motor 266 serves for the high speed return movement of the turret slide. Electrical control and operations. Dual means are provided for selecting the clutches to be energized either (a) manual controllers 22. 23, Fig. 2, which override the automatic means and give the required spindle speed and tool feed, or (b) a presettable system which may comprise a jack panel 24 in which the circuits to switches for the clutches are manually prepared for a particular operation. In the automatic control a stepwise movable means constituted by the lathe tool turret successively activates the pairs of rows of jacks which select the clutch combinations. The turret may be manually or automatically rotated and a punched card may be used for initially setting up the plugs 25 of the jack panel. After setting up the machine is started by pressing the buttons 29, 29a, Figs. 6 and 7 (forming together a complete circuit diagram), the main switch 42 having been previously turned on. The switches 30- 35 are cam-operated by the stepwise rotation of the turret and similarly with the jacks 25 and selector switches 22, 23, control the electromagnets for the clutches through the intermediary of relays. The jack board comprises three fields of jacks designated S, D, V, for controlling the clutches of the spindle speeds, sense of spindle rotation and rate of feed respectively. Each field comprises six horizontal rows corresponding to the six indexible positions of the turret and the switches 30-35. In the field D each horizontal row comprises two jacks, the left for forward rotation and the right for reverse rotation of spindle 200, shaded positions show the pre-set arrangement of jack plugs. Depression of buttons 29, 29a closes following circuits-from negative terminal of a. two-way rectifier 43 with a voltage of 24 volts which is connected to a suitable source of A.C. via a transformer 44 through wires 45 and 46, relay switch 47 of a thermic overload relay protecting the main spindle motor 48, wire 49, stop button 50, wire 51, relay 52, wire 53, switch 54, wire 55, operating contacts of button 29a, wire 56, brake button 57, wires 58 and 59 and a " disengage " switch 60 to the positive rectifier terminal. A holding circuit is completed through button switch 29a and a relay 52 closes contacts 1152 and 1262, the latter energizing a red signal lamp 30<SP>1</SP> indicating that the automatic control of the spindle speed is effective. Further contacts and relays operate the appropriate clutches for the selected speeds direction of rotations and feeds until the turret is returned at high speed and indexes 60 degrees to release the switch 30 and close switch 31. On the next forward feed movement of the turret, a new set of relays and switches incorporating the second horizontal row of the jack fields is rendered operative. Successive stages of operation will be performed in accordance with the schedule set up by the plugs of the jack board. A brake button 57 is provided for making an abrupt stopping of the lathe and the electromagnetic clutches are equipped with the customary arc-quenching condensers and resistances which slow down the disengagement of the clutches upon de-energization thereof.