GB643582A - Improvements relating to machines for making sheet material from a pulp - Google Patents

Abstract

643,582. Suction control in paper-making machines. SULZER FRERES SOC. ANON. Aug. 15, 1947, No. 22727. Convention date, May 29. [Class 96] [Also in Group XXIX] A machine for making sheet paper from pulp, has suction applied at various points 3, 6, 11, 17, Fig. 1, connected by pipes 19 ... 22 respectively to a suction pump 23, and includes regulating valves 31 ... 34 in the pipes, which valves are operated by control valves actuated by the suction in the pipes so that the suction pres. sure at the pump is maintained at a permissible minimum value when the suction points are not covered by the sheet. The valves 31 ...34 are byepassed by pipes 35 ... 3E respectively, .which have adjustable throttle valves 39 ... 42 tc enable the desired suction to be maintained at the pump when the valves 31 ... 34 are closed. These valves 31 ... 34 each comprise an expansible bladder 51, Fig. 2, con nected through a valve 53 with either atmosphere through a pipe 54 or suction through a pipe 55 Pipes 43 ... 46 connect each chamber 56 with the pressure in each suction pipe and the chamber below each valve is open to atmospheric pressure. When the suction in any pipe 19 ... 22 reaches the required value, the appropriate valve 53 rises to connect the bladder to suction, whereupon a spring 59 deflates the bladder; and when the suction decreases, the valve drops to connect the bladder to atmospheric pressure, whereupon the bladder inflates. In a modification, the valve 67, Fig. 3, is locked in a position, to cause the bladder to inflate, by a spring-loaded piston 73. When suction is applied to the rear of the piston through a pipe 76, the lock is withdrawn and a spring 77 moves the valve 67 to deflate the bladder. Each valve is pulled manually to the locked position before the machine is started. The releasing of the lock of each valve is timed by a device comprising a cylinder 80, Fig. 4, having connections 91 ... 95 with the corresponding pipes 76, Fig. 3, and a pipe 96 connected to the pump. The distances between the connections 91 ... 95 correspond to the times the sheet takes to travel from a respective suction point to the next. A piston 81 extended by a rack 83 is driven to the right by pinions 86, 85 and 84, in timed relation to the speed of the machine, -to open the connections 91 ... 95 to suction. The pinions 86, 85 are pivoted on a handle 87 which drops away from the pinion 84 when the rack completes its stroke. In another arrangement, the pistons 73, Fig. 3, may be actuated by fluid pressure.