Patent GB-701001-A (GB)
Title: Improvements in or relating to feeler controlled machine tools, particularly copyinglathes
IPC: B23Q35/121
Filed: 1951-04-16
Abstract: 701,001. Copy-turning. HARBECK, M., HARBECK, M., STEFFEN, H., and STEFFEN, E., [trading as HEIDENREICH & HARBECK]. April 16, 1951 [May 2, 1950], No. 8755/51 Class 83 (3). [Also in Group XXXVIII] In a feeler-controlled machine tool, e.g. a copying lathe, the feeler actuates electronic switches which control a hydraulic servo-motor driving the tool. As shown, Fig. 5, applied to a copying lathe the feeler 8 and cutter 23 are both carried on the transverse slide 9 which is moved longitudinally at constant velocity, and moved transversely by a fluid-pressure operated piston 11 under the control of the pressure exerted by the feeler on the fixed template 7 whereby the work 22 is cut according to the template. In another embodiment, both longitudinal and transverse feeds of the slide areeffected by fluid pressure servo-systems controlled by a single feeler, Fig. 6 (not shown). Construction, and mounting of tracer.-The feeler comprises a feeler point 64, Figs. 11, 12, 14, 15, adjustably secured in the end of the feeler body 46 which is of T-section, the vertical arm of which is in the form of a tube 46 guided for longitudinal movement by roller bearings 50 ... 53, Fig. 15. The horizontal arms of the T-section are also guided by three pairs of roller bearings 58 ... 59, 60 ... 61, 62 ... 63, the roller bearings being carried on eccentric bolts 69 for adjustment. A tension spring 71, Fig. 11, urges the feeler forwards, and the feeler, through an angle member 72, moves a contact tongue 75 about its blade-spring pivot 74. When the feeler point is not contacting the template, the spring 71 moves the contact tongue 75 into engagement with a fixed but adjustable contact 76 which, as described below, causes the feeler to be advanced (transversely) until it engages the template 7, whereupon the feeler moves back, relative to its mounting, thereby opening the contact 76 to stop the transverse advance. The constant speed longitudinal drive now being connected, the feeler will be moved transversely forwards or backwards according to the template shape to close contact 76 or 77 which, as described below, control respectively the forward and reverse (transverse) drive of the slide carrying the feeler and cutter. The play of the feeler is controlled by adjusting the contacts. 76, 77. If the reverse drive does not operate quickly enough the increased retraction of the feeler actuates through a pin 84 " alarm contacts, Fig. 13 (not shown), which cause rapid retraction of the feeler. Thermionic switching and hydraulic servo control.-The contacts 76, 77, Fig. 11, are each connected in the grid circuits of respective triodes 34, Fig. 19. With the contact 76, e.g. open, the triode is blocked by the bias from battery 38. Closure of the contact 76 raises the grid to earth potential whereupon the triode conducts, its anode current energizing a relay, e.g. 116, Fig. 7. In a similar manner closure of contact 77 causes the associated valve to conduct and energize a relay 117, Fig. 7. The two relays operate, in opposite senses, a control valve 89 in the hydraulic system to admit pressure fluid to the appropriate side of the piston 11, Fig. 5, to drive the slide carrying the feeler and cutter in the appropriate sense. The control valve is spring biased, Fig. 16 (not shown) to its normal inoperative position. Should the alarm contacts referred to above be actuated, a relay 85, Fig. 7, is de-energized to move a further valve 86 to the left whereupon pressure fluid is admitted to the appropriate side of the piston 11 rapidly to retract the feeler and cutter. Controlling to-and-fro and another motion.- When both transverse and longitudinal feed of the cutter is to be controlled the feeler actuates the transverse drive control contacts in the above described manner, and in addition, actuates a further contact tongue 152, Fig. 21, which cooperates with fixed contacts 155, 156 to control the forward and reverse longitudinal drive in a manner similar to that of the transverse drive. The transverse and longitudinal controls may be reversed to effect transverse copying. Specification 701,002 is referred to.