Patent GB-1110626-A (GB)
Title: Improvements relating to shearing of metal sheet
Inventor: PUGH GORDON HAROLD
IPC: B23D33/00
Filed: 1966-02-24
Abstract: 1,110,626. Shearing. JOSHUA BIGWOOD & SON Ltd. 9 Feb., 1967 [24 Feb., 1966], No. 8082/66. Heading B3W. An apparatus, for shearing predetermined lengths of metal sheet from a bulk supply, comprises continuously operating feed means, a motor driving a shear blade through a clutch, the motor running continuously when the apparatus is in use, a hold-down, a back-stop retractable into an inoperative position and means to remove the cut-off length of sheet; probe means actuated by the leading edge of the sheet to cause movement of the hold-down to grip the sheet and engagement of the shear driving clutch, control means actuated during operation of the shear to control the time for which the hold-down means grips the sheet, to cause disengagement of the clutch and to cause retraction of the back-stop and further probe means actuated by the trailing edge of the cut length to return the back-stop to its operative position. Sheet 11 is drawn from an uncoiler 13 by a roll straightener 14 and passes over a humping table 18 to a shear 16, beyond the shear is a belt conveyer 63 which removes the cut-off length at twice the feed speed. A back stop assembly 64 runs on rails parallel to the conveyer. Shear construction.-The shear 16, Fig. 4, has a fixed upper blade holder 36 and a lower blade holder 30 which is reciprocated by a crankshaft 24 to which is secured a gear-wheel 26. A pinion 28 meshes with the gear-wheel and is mounted on a shaft 49 to which is secured one member 59 of a clutch and one member 60 of a brake. The driving member 57 of the clutch rotates with a fly-wheel 54 which is belt driven by a motor 28a. The anchor member 62 of the brake is fixed to a side member 22 of the shear frame. Two fluid-operated jacks 38 lift a movable hold-down member (41), Fig. 5 (not shown) into contact with a fixed abutment (42) which extends across the shear frame. Four rods 41a extend downwardly from the movable member 41 and are guided in bores through the lower blade holder 30. Cams 43, 44 fixed on the crank-shaft are associated respectively with proximity switches 45 and 46. The switch 45 causes operation of a solenoid valve which retracts the back stop and also operates a timer which controls the length of_time for which the hold-down grips the sheet. The switch 46 is operated after the switch 45 and causes disengagement of the shear driving clutch and engagement of the brake. Back-stop construction.-Two side-plates 65 are joined by a channel section 73 to form a carriage which runs on four rollers 66, 67 along the rails at each side of the conveyer 63. The back-stop 76 is raised and lowered by a fluidoperated jack 74. Also mounted on the carriage are three probes, only one of which 87, is visible in Fig. 6. Each probe is mounted on a beam 79 which is slidable in the carriage and is moved by a manually operated headscrew 81. All three probes are movable parallel to the surface of the sheet. Operation.-The sheet 11 from the uncoiler 13 passes over the humping table, through the shear and its leading edge operates the first probe 87 which is connected to a solenoid valve controlling the fluid jacks 38 which move the hold-down member 41 to grip the sheet. While the member 41 is moving the sheet travels forward until its leading edge strikes the backstop 76. During this travel the sheet operates the second probe (88) which causes the shear driving, clutch to engage and the brake to disengage. As the shear crank-shaft rotates the cam 43 operates the switch 45 which causes the back-stop to be raised and also starts an electric timer to control the time for which the hold-down remains effective. After further rotation of the crank-shaft the cam 44 operates the switch 46 to cause disengagement of the shear driving clutch and application of the brake. When the crank-shaft has stopped the timer causes the jacks 38 to lower the holddown and the sheet which has formed into a hump on the table 18 begins to move through the shear. As the trailing end of the freshly cut length clears the back-stop the third probe (89) is operated and causes the back-stop 76 to be lowered into the path of the sheet. When the last portion of the sheet leaves the uncoiler the drive of the sheet is taken over by a pair of pinch rolls (not shown) in front of the holddown. The upper pinch roller is lowered to contact the sheet.