Patent GB-1194483-A (GB)
Title: System for Synchronously Driving Units of a Press Without Mechanically Interlinking Them
IPC: B21D43/05
Filed: 1968-02-13
Abstract: 1,194,483. Control of several A.C. motors. DANLY MACHINE CORP. 13 Feb., 1968 [7 Aug., 1967], No. 6996/68. Heading H2J. The various components of an automatic power press, e.g. the slide 13, the unloader 17 and the conveyer 19, are driven in synchronism by an arrangement of polyphase wound-rotor induction motors comprising a first motor 23 whose rotor is mechanically coupled to the press drive 43, 45, 46 and electrically connected to the windings of the rotors of motors 27, 29 which respectively drive the unloader 17 and conveyer 19, the stator windings of the motors being supplied from a common source L1. L2, L3 and the rotors of motors 27, 29 following the movement of the rotor of motor 23 after an initial synchronization to bring the windings of these three rotors into the same position with respect to their stator windings and to bring the drive shafts 14, 18, 20 of the slide, unloader and conveyer into the correct alignment. The positional errors between the shafts 14, 18 and 14, 20 are respectively derived from conventional synchros 59, 61 and 55, 57 whose outputs are respectively fed to fine and coarse error detectors 73, 81 and 71, 79 which respectively control the electrical connection between the rotor windings of the pairs of motors (contacts MR41, MR61) and the electrical connection between the supply L1, L2, L3 and the stator windings of the pairs of motors (contacts MR11, MR21, MR31). Synchronization is effected manually by intermittent operation of the clutch 45 to rotate the rotor of motor 23 until it is aligned with the rotor of motor 27 or 29 and until shafts 14, 18 or 14, 20 are aligned, the former condition being indicated by a zero reading of voltmeter 109 or 111 and the latter condition being indicated by a (near) zero reading of the meter supplied from fine error detector 73 or 71 and by energization of a lamp. When simultaneous zero readings occur on the voltmeter and error detector meter associated with a particular motor, e.g. the motor 27, contacts MR41 are manually closed to synchronize motors 23, 27. Further intermittent operation of the clutch 45 allows contacts MR61 to be manually closed to synchronize motors 23, 29 when the appropriate meters simultaneously read zero. Thereafter the clutch 45 is continuously energized and synchronous operation of the press occurs. Should the output of detector 71 or 73 exceed a predetermined position error, contacts MR61 or MR41 are automatically opened. Similarly if the output of coarse error detector 79 or 81 exceeds a predetermined value, contacts MR11, MR31 or MR11, MR21 are automatically opened. In either of the latter events the press drive 43 is automatically disengaged by de-energization of the clutch 45. Provision is also made for synchronization of one or other of the motors 27, 29 or for individual operation of these motors (using resistors 113-115) to actuate the unloader 17 or conveyer 19. Each error detector comprises an A.C. to D.C. converting stage and and a triggered oscillator output stage, Figs. 4 (d) and 4 (e) (not shown). The relay control and interlock circuits are described in detail, Figs. 4 (b) and 4 (c) (not shown). have holes 4, spaced at half the pitch of the end tongues 5 and are so designed that any consecutive three holes can accommodate the two tongues 5 and bolt 6 of a ring.