GB707087A - Improvements in or relating to sheet-cutting apparatus - Google Patents

Abstract

707,087. Cutting-machines. LAWSON CO., Inc., E. P. Aug. 24, 1951, No. 20027/51. Class 31 (1) A machine for cutting paper sheets comprises a vertically-reciprocating knife 25, Fig. 7, a vertically-reciprocating work clamp 66, means connected between the knife-driving mechanism and the clamp for driving the clamp, a fluid-filled coupling 52 disposed in the latter connection and consisting of elements which are movable with respect to each other independently of the knife-driving mechanism, electric means for controlling the elements of the coupling, and means operable by the knifedriving mechanism for controlling the energization of the latter means. The knife bar 25 is reciprocated from a shaft 18, Fig. 12, which is driven from a shaft 15 adapted to be clutched to a motor-driven flywheel 14 rotatable thereon. A gear 16 on the shaft 15 drives a gear 17 on a sleeve 150 which is rotatable on the shaft 18, and a gear 153 on the sleeve acts through a planetary gear 154 carried by a plate 152 to drive an internal gear 156 fixed to the shaft 18. A crank 20, Fig. 7, on the shaft 18 is pivotally connected by a rod 22 to one end of the knife bar 25; the opposite end of this bar is pivoted to an arm 27 which is rocked by a lever 44 pivoted by a pin 43 to one end of a compound connecting rod 37 pivoted to a second crank 35 on the shaft 18. The length of the rod 22 is adjustable, and the arm 27 is connected to the bar 25 by an eccentric pin 28 which is rotatable by worm gearing to adjust the position of the connection. Should the knife encounter excessive resistance, the gear 154 causes the plate 152 to rotate around the sleeve 150 agaiiist the action of a spring 157. One end of the clamp 66, Fig. 7, is carried by a link 64 which is connected through a bell-crank 61, link 59 and levers 57, 55 to one end 53 of a hydraulic cylinder 52 ; the piston rod 50 of the cylinder is connected to the pin 43. The other end of the clamp is connected through a link 78, a bell-crank 74 and link 72 to the bell-crank 61. The cylinder 52 is included in a hydraulic circuit comprising a reservoir 81, Fig. 5, enclosing a pressure-fluid container 84 in which fluid is maintained at the desired pressure by a spring-pressed piston 83. The hydraulic circuit also comprises a pump 103 for initially building up pressure in the system, check valve F, handcontrolled pressure regulator G, and four solenoid-controlled valves B, A2, A1, C. With the valves B, A1 closed and valves A2, C open, and the knife-operating means actuated to lower the knife, the piston 51 moves to the right so as to compress the fluid in the righthand of the cylinder 50 and moves the latter to the right to lower the clamp ; the cylinder operates to lower the clamp ahead of the knife because of the pressure fluid flowing through the check valve F and valve C to the right-hand end of the cylinder. The clamp stops when it reaches the paper but continued movement of the knife bar and connecting rod 37 acts on the piston 51 to increase clamping pressure, which is maintained by the check valve F. As the continued action of the knife-actuating mechanism raises the knife bar, the rotation of the crank 44 is reversed but, since the fluid in the left-hand end of the cylinder is at reservoir pressure, the clamp is not raised until the setting of the valves is reversed towards the end of the cycle. The valves are mounted in a block 150, Fig. 3, disposed on top of the reservoir 81, and the valves B, A2, A1, C are combined to provide a single four-way valve constituted by an axially-movable spindle having lands controlling fluid pressure openings ; the plunger of a solenoid moves the spindles to set the valves as desired. The operation of the machine is controlled from a hand-operated shaft 201, Fig. 3, which is movable axially to cause a clutch 202 to link the flywheel 14 to the shaft 15 whereby the knife starts its cycle. This movement of the shaft also allows a switch 205 to close and energize the valve solenoid for setting the valves to lower the clamp. A second switch 226 provides a maintaining circuit for energising the solenoid so that the shaft 201 may be moved to disengage the drive of the knife without affecting the clamp. Near the end of a cycle, a cam 220 on the shaft 15 serves to operate the second switch to de-energize the solenoid and set the valves to raise the clamp, and the shaft 201 is later moved to stop the knife. A foot lever 600, Fig. 3, is connected by a.cable 705 with a lever acting through a pin directly upon the plunger of the valve solenoid so as to permit the operator to control the valves and thereby the operation of the clamp independently of the knife. The valve G controlling the clamping pressure is operable by a knob 729, Fig. 3, through shafting and gearing 720 ... 727.