GB748829A - Web tension control systems for printing presses - Google Patents

Abstract

748,829. Band-brakes. GOSS PRINTING PRESS CO. July 16, 1953 [April 27, 1953], No. 19769/53. Class 103 (1). [Also in Group XVI] A belt brake 20 for controlling the tension in a web 11 fed from a paper roll 12 is operated by a fluid-pressure actuator 21 supplied with fluid at variable pressure by an adjustable pressure regulator 40 under the control of an element 41 responsive to changes in the tension of the web so that the tension of the web is maintained at a predetermined value, auxiliary means 67 operative under emergency conditions being provided to put the input of the regulator 40 in full communication with the outlet thereof so that the maximum braking pressure is applied. The regulator 40 comprises a diaphragm 70 adjacent a pressure chamber 71 and loaded against the pressure in the pressure chamber by a spring 42 and valve means 72, 75 coupled to the diaphragm for connecting the outlet side of the valve to a source of pressure when the pressure in the chamber 71 is below a predetermined value and for bleeding fluid from the outlet side of the valve when the pressure in the chamber 71 is above the predetermined value. The auxiliary means 67 comprises a valve for connecting the pressure chamber to the outlet side of the valve under normal operating conditions, and for venting the chamber 71 to atmospheric under emergency conditions so that the spring 42 moves the valve means 72, 75 to put the source of fluid pressure in full communication with the outlet side of the regulator 40. The valve means comprise an inlet valve 75 in the form of a poppet 76 co-operating with a fixed seat 76 and an exhaust valve 72 in the form of a tubular seat member 74 co-operating with a poppet 73 rigid with the poppet 76 and urged towards the closed position by a spring 83. The inlet pressure on the poppet 76 is balanced by the pressure on a piston 78 connected to the poppet 76 by a rod 79. The tubular member 74 has exhaust ports 74a. The auxiliary valve means 67 is operated by a solenoid 98 and normally a passage 67a connects the chamber 71 with the outlet side of the main valve through lines 68, 69. When the solenoid is energized in an emergency, the passage 67e vents the chamber 71 to atmosphere so that the spring 42 pushes the inlet valve fully open. The fluid actuator 21 is supplied from the regulator 40 by a pipe 43. The spring 42 of the regulator is adjusted by a rod 41 coupled to pendulum-like arms 52 carrying a floating roller 50 round which the web passes. The reaction of the spring 42 on the arms 52 is neutralized by a piston 64 supplied from the outlet side of the regulator 40 through a pipe 82. The roller 50 moves in response to variations in tension and so adjusts the regulator 40. The desired tension is adjustable by means of a loading cylinder 55 supplied through an adjustable pressure regulator 60 supplied from the same source as that supplying the regulator 40. This source is itself fitted with an adjustable pressure regulator 31 and an accumulator 35. In an emergency, the solenoid 98 is energized by the closing of a switch 99 either manually or automatically as by a web break detector. Specification 743,351, [Group XVI], is referred to.