Patent GB-459685-A (GB)
Title: Improvements in electrical feeler control systems for profiling copying machines
IPC: B23Q35/121
Filed: 1936-02-07
Abstract: 459,685. Milling-machines; electric correspondence control. SIEMENS-SCHUCKERTWERKE AKT.-GES., Siemensstadt, Berlin. Feb. 7, 1936, No. 3813. Convention date, Feb. 7, 1935. [Class 83 (iii)] [See also Group XXXVIII] In an electrically controlled copying-machine, particularly a milling-machine, wherein a deflectable tracer follows the surface of a pattern to operate electrical contacts for controlling relative feed movements between the cutter and work, the contacts are so arranged that feed movement, either forwards or backwards, is always in operation and its direction is determined by one of two possible positions which the tracer may occupy In one form the tracer (not shown), controls a lever 33, Fig. 8, pivoted at 34 and biassed by a spring so as to close contacts 35, 36 in the circuit from a generator 38 to a solenoid 39. The circuit for the " in " and " out " electromagnetic clutches 43, 44 passes through the arm of a switch 40 and one of the contacts 41, 42. When the main switch 37 is closed the solenoid 39 is energized and the switch 40 moved to actuate the clutch 43, causing " in " feed of the tool and tracer. Pressure of the pattern on the tracer rocks the lever 33 to open contacts 35, 36 thereby releasing the switch 40 and allowing its spring to close contact 42 and actuate clutch 44 for " out " feed of the cutter and tracer. The traverse feed of the cutter and tracer along the pattern is produced by a motor 45 and one of the magnetic clutches 25, 26, only one of which can be in operation at any time due to the hand controlled switch 46, and this feed may be continuous whilst the cutter is moving in and out so as to follow the pattern by a combination of these three motions. The speed of the traverse may be varied according to the steepness of the pattern by means of a second tracer mounted with the main tracer and controlling a speed regulator 47 for the motor 45, or the regulator may be operated by means of a valve control which is sensitive to the frequency of current impulses produced by the contacts 35, 36, which frequency is dependent on the steepness of the pattern. In a modified arrangement in which the traversing feed is indirectly controlled by the tracer, solenoids 48, 49, Fig. 9, are mounted in parallel with the " in " and " out " clutches 43, 44 respectively under control of the switch 40, the switches 51, 53 thereof being in series with a solenoid 50 controlling a switch 54 for one of the traversing clutches 25, 26. On closing the main switch 37 the clutch 43 is actuated for " in " feed of the cutter and tracer and the switch 51 simultaneously closed, but actuation of the switch 54 is prevented by the switch 53 being open. When the pressure of the pattern on the tracer opens the contacts 35, 36 the clutch 44 is actuated for " out " feed and the solenoid 49 is energized to close the switch 53 and actuate the clutch 25 for traverse feed, the switch 51 being held closed for a short time after the solenoid 48 is deenergized due to a parallel resistance 52. Opening of the switch 54 is also delayed after the circuit of the solenoid 50 has been broken, by means of a parallel resistance 55, and after this delay the switch 54 is opened again to stop the traverse feed. This causes a cycle of " in " feeds and combined " out " and traverse feeds as shown at I in Fig. 10a. By varying the degrees of retardation produced by the resistances 52, 55, the traverse feed may be caused to stop before the " out " feed has terminated, as shown at II in Fig. 10a, and by inserting an inductance 56 in the circuit of the solenoid 49 the starting of the traverse feed may also be delayed, producing the cycle shown at III in Fig. 10a. If the relays 48 and 49 are interchanged, the traverse feed may be caused to operate during the " in feed, giving the cycles shown in Fig. 10b corresponding to those shown in Fig. 10a and traverse feed during both the " in " and " out " feeds may be produced by providing retarding devices on both the solenoids 48, 49, thus giving the cycles shown in Fig. 10c. In another modification in which the traverse feeds take place between the " in " and " out " feeds whilst the latter are inoperative, the circuit is arranged as shown in Fig. 11, in which the control line leading to the " out " clutch 44 is broken by a switch 57 operated by the solenoid 48. The remainder of the circuit is the same as in Fig. 9, and after the clutch 43 and solenoid 48 have been energized for an " in " feed, the contacts 35, 36 are broken by pressure on the tracer and the solenoid 49 is energized for giving a traverse feed, the clutch 44 for the " out " feed being prevented from operating due to the switch 57 being held open by the effect of the retarding resistance 52 on the solenoid 48. When this solenoid is released to stop the traverse feed, the switch 57 is closed to allow the clutch 44 to be actuated for an " out feed. This arrangement produces a cyclic movement of the tracer and cutter as shown in Fig. 11a. Alternatively the traverse feed may be arranged to take place between an " in " feed and an " out " feed, and by varying the retardation of the relays 48, 49 similar cycles to those shown in Figs. 10a-10c may be produced. The speed of the traverse feed may be altered by hand when the machine has been brought to rest by means of limit switches set at points along the pattern where abrupt variations of slope occur, or the speed may be varied automatically in steps by such limit switches.