Patent GB-678161-A (GB)
Title: Improvements in copying lathes
IPC: B23Q35/12
Filed: 1948-09-27
Abstract: 678,161. Copy-turning. COMPAGNIE GENERALE DE CONSTRUCTION DE LOCOMOTIVES (BATIGNOLLES CHATILLON). Sept. 27, 1948 [Dec. 30, 1947; July 13, 1948], Nos. 25155/48 and 25156/48. Class 83 (iii). [Also in Group XXXVIII] A copying lathe has a tool 8 and feeler 42 mounted on a cross-slide 10 which is fed transversely by a hydraulic piston 9 and longitudinally by a drive having an electromagnetic clutch 6; when slopes of less than about 60 degrees are copied from a template 1 mounted between centres 2, 3, the feeler controls only a valve 14 for the hydraulic piston but, when a shoulder or steep slope is met, the feeler controls also an electric switch 49 which is opened to disengage the clutch 6 and stop the longitudinal feed. Fluid is supplied at equal pressure to both sides of the piston 9 but, when the feeler is out of contact with the template, the valve 14 is maintained open by the spring 15 so that the piston moves to the right in Fig. 2 until the lever contacts the template and tilts about a horizontal axis 17 to cause a lever 16 to depress the valve sufficiently to maintain the forces on each side of the piston equal. When slopes less than 60 degrees are met by the feeler, it tilts further about the axis 17 and closes the valve further so that the greater area of the head of the piston causes the cross-slide to move to the left and withdraw the tool and feeler. If a shoulder or steep slope is met, the feeler rotates about a vertical pin 35 against the action of a spring 47 and, through a sliding pin 51,and spring 52, opens the switch 49. The longitudinal feed is then stopped by the disengagement of the clutch 6 and, at the same time, the spring-loaded core 23 of a solenoid 21 is de-energized and descends to depress the valve 14. After the cross-slide has withdrawn sufficiently, the switch 49 closes and the operation is repeated so that a steep slope is copied in a series of small steps. Adjustment of the speed of withdrawal of the cross-slide can be made by adjusting the travel of the core 23 and, therefore, the amount of depression of the valve, by a nut 25 and lock-nut 26. The valve 14 may also be depressed manually by a handle 18 connected to a lever 20 interposed between the core 23 and the lever 16; a pin-and-slot connection between the handle and a bush 20a allows 'the core 23 to rotate the feeler without affecting the handle. A mechanical or electrical brake may be coupled to the clutch to ensure quick stopping of the feed. The Specification as open to inspection under Sect. 91 comprises also a modification in which the template is carried between spring-loaded centres 2, 3, the spring for the centre 2 being adjusted so that its compression is greater than that for the centre 3 in order that the support is normally urged to the right. When the feeler meets a shoulder or steep slope, the template moves slightly to the left and opens a switch corresponding to the switch 49 controlling the clutch 6 and solenoid 21. In a further modification, the solenoid 21 is omitted and the feeler has a cam slope engaging a fixed pin so that it pivots round the axis 17 to depress the valve 14, whenever a shoulder or steep slope causes it to pivot round the axis 35. This subject-matter does not appear in the Specification as accepted.