Patent GB-770270-A (GB)
Title: Improvements in and relating to copying machines
IPC: G05B19/42
Filed: 1952-08-29
Abstract: 770,270. Electrically-controlled copying machines. SOC. AUTOMATA. Aug. 29, 1952 [Aug. 31, 1951], No. 21842/52. Class 40 (1). [Also in Group XXII] In a feeler-controlled copying machine, a series of contacts operated respectively, at successively increased deflections of the feeler, switch corresponding frequency generators into the circuit of a recording head, the record so produced, preferably on a magnetic tape, being subsequently used for controlling a copying tool. As applied to a milling machine, Fig. 1, the cutter 9 and its driving motor 8 are carried by a head 6 moved radially along an arm 2 by a motor 7, the arm 2 being rotated about a column 1 by a motor 3. Feeler construction, Fig. 2. Fixed to the casing of the motor 8 driving the cutter 9, is a ring 10 in which the feeler ring 13 is gimbal mounted for limited universal movement. Lateral movements of the feeler by the pattern 19 are transmitted through arms 15, passing outside the motor 8, to a rod 16 the pointed end of which through a rod 17 deflects successively, spring biased levers 20, 21, Fig. 3. In the neutral position of the feeler, contacts 22a, 22c are closed and 22b, 22d open. Contacts 22a open, contacts 22b close, contacts 22c open and contacts 22d close, in succession, as the feeler deflection from neutral gradually increases. Recording, Fig. 3. The contacts 22a . . . 22d control respective relays 23, 24, 25, 26. Initially, assuming the feeler to be at neutral, the relays 23, 25 are energized over their respective contacts 22a, 22c. Relay 23 energizes a holding relay 27 and a magnet 28a which steps a controller 29 to position I, whereupon an electromagnetic coupling 7a is energized so that motor 7 is coupled to drive the feeler radially towards the pattern, outwards in the case of interior copying. At the same time, over contacts of the operated relays 23, 27, 25, frequencies F1, F2, F3 derived from a multifrequency generator 31 are connected to the recording head 33, When the feeler contacts the pattern, the contacts 22a open to release relay 23, whereupon frequencies F2, F3 only are recorded and the motor 3 is also coupled, at 3a, to drive the feeler in azimuth. The radial coupling 7a remains energized until the feeler deflection increases to close contacts 22b to energize relay 24 which releases relay 27. Coupling 7a is thereby disconnected and the frequency F3, only, is connected to the recording head 33. Should the feeler deflection increase to open contacts 22c, coupling 7b is energized to drive the feeler radially in the reverse direction, and while these conditions obtain, none of frequencies F1-F4 is connected to the recording head. Should the feeler deflection increase sufficiently to close contacts 22d, relay 26 operates to connect the frequency F4 to the recording head, and deenergizes the coupling 3a to stop the azimuthal feeler feed. Relay 26 also energizes a magnet 28b which drives the controller back one step. During normal operation, each time the feeler returns to its neutral position the magnet 28a is energized to step the controller, the contacts of which are so connected that in the successive positions I . . . IV thereof the roles of the couplings 3a, 3b, 7a, 7b are changed so that the pattern may be explored over its whole periphery. The record tape is helically wound on a drum 34 driven at constant speed and the recording head is moved axially of the drum through gearing driven by the drum in accordance with the pitch of the tape winding as disclosed in Specification 770,269. Reproduction. To control the milling cutter 9 from the record, the switch 32 is opened and switch 35 closed. The recorded signals are picked off at 36 and fed to relays 38, 39, 40, 41 responsive, respectively, to frequencies F1, F2, F3, F4. These relays control the magnets 28a, 28b and the couplings 3a, 3b, 7a, 7b in a manner similar to their control by the relays 23 . . . 26 during recording, so that the movements of the cutter, both radial and azimuthal correspond to those of the feeler during recording.