GB1212855A - Cutting, creasing and embossing presses - Google Patents

Abstract

1,212,855. Machinery guards. WILLIAM CROSLAND Ltd. 24 Sept., 1968 [27 Sept., 1967], No. 43979/67. Heading F2J. A cutting, creasing, and embossing press having a platen 11 movable towards and away from a fixed platen 24 by a drive including an electrically engaged clutch 14, includes a photoelectric guard 25 comprising a light source 26 and a detector 27, interruption of the light beam, e.g. by an operator having a part of his person so positioned that trapping thereof by the press is possible, causing disengagement of the clutch 14 and application of a brake 20 to stop the press. The photo-electric guard 25 may be mounted just above the swept arc of the platen 11, as shown, on a U-frame 46, 50 pivoted at 47 to the press frame 10 and having transparent side guards 51, or it may be located in front of the press, about 2 feet above the floor (Fig. 1, not shown). A shaft 21 carrying the clutch 14 output member and acted upon by the brake 20 and a "fail-safe" brake (not shown) is geared to a crank-shaft 13 coupled to the platen 11 by connecting-rods 12. The control circuit in Fig. 3 is very similar to that described in Specification 789,183. The rectified output of a transformer 31 is controlled by relay contacts 30 to energize a solenoid 15 to engage the clutch 14, or a solenoid 22 to apply the brake 20. Contacts 30 are biased to supply the brake solenoid 22 when the relay coil 37 is not energized. Provided that the light beam is not interrupted, closure of a starting switch 16 energizes the coil 37 to close a holding switch 38 and to move contacts 30 to energize the clutch solenoid 15 and de-energize the brake solenoid 22. Interruption of the light beam de-energizes the coil 37. A relay coil 41, energized by the transformer 31, holder contacts 42 to energize a solenoid 43 which holds the "failsafe" brake released. A power failure allows contacts 42 to open, for application of the "failsafe" brake. A single stroke/continuous run selector switch 39 and a limit switch 40 are provided. In an alternative control circuit, Fig. 5, 67 is the "fail-safe" brake solenoid, 70 is the brake solenoid, and 71 the clutch solenoid. The switch 30 of Fig. 3 is replaced by switches 68, 69 both biased towards the positions shown. The control circuit of the press drive motor 19 includes stop and start switches 58, 59, the main motor contactor 76, and a motor running warning light 74. A holding switch 61 in parallel with the start switch 59 is closed while the motor is running. Energization of the clutch/brake control circuit is controlled by a guard switch 60 which is closed while the light beam is not interrupted. Relays 81, 82 controlling the switch 69, and a relay 85 controlling the switch 68 must be energized simultaneously for clutch engagement and brake 20 disengagement. Energization of relays 81, 82 also closes a holding switch 84 and a switch 87 in the circuit of relay 85. Energization of relay 85 also closes a switch 104. A rotary switch 88 has four positions:-97 for single cycle working, in which contacts 89, 93 are connected, 98 for continuous working, in which contacts 90, 94 are connected, 99 for dwell working, with a dwell at some stage in the pressing cycle, in which contacts 89, 93; 91, 95; and 92, 96 are connected, 100 for inching, with no connections. Each change of the rotary switch opens a switch 83 momentarily to ensure that operation is recommenced at the start of a fresh cycle. A limit switch 103, the contacts 101, 102 of which are never open simultaneously, is operated at the open position of the platen 11 to terminate operation in single stroke working. A timer 109 controls a switch 107 for dwell operation. Press operation is initiated, or, in the case of inching, controlled by a clutch start switch 79 having contacts 78, 86, 108. The "fail safe" brake solenoid 67 is de-energized by a switch 65 when the relays 81, 82 are de-energized, when the mains supply fails, or when the photo-electric guard is obstructed. In the Fig. 2 embodiment, movement of the U-frame 46, 50 to a position in alignment with the fixed platen 24 also applies the "fail-safe" brake.