GB1138108A - Improvements in and relating to means for lateral guiding of a web of material - Google Patents

Abstract

1,138,108. Feeding webs. AKERLUND & RAUSING A.B. 6 July, 1967 [27 July, 1966], No. 31134/67. Heading B6B. Transverse web-registering apparatus includes a sensing member 9 which utilizes the flow of compressed air through an aperture 10 controlled by the web edge, a pressure box 13 operated by compressed air for displacing a web-roll or roller laterally and a control valve 5 and servo-valve 7 connected into a compressed air conduit system. With the web correctly aligned, its margin 70 covers the aperture 10 partly but not completely. Compressed air entering the control valve 5 from a pressure regulator 3 acts on the top surface of a diaphragm 20 and keeps it at a small distance from the contact surface on the valve housing 18 against the action of a spring. Through outlet opening 23, pipe conduit 6, chamber 53 in the servo valve 7, pipe conduit 11 and non-return valve 12, the compressed air acts on the diaphragm 15 of the pressure box 13 and is balanced by the spring 14. A small part of the compressed air escapes permanently from the servo-valve 7 through a retricted opening 59, but is replaced by new air from the control valve 5. A further part of the supplied compressed air flows through ducts 27 and 29 in the control valve 5, through a choking point 30 and duct 31 to a chamber below a diaphragm 21, from whence it flows via an opening 32 and a pipe conduit 8 to the sensing member 9. Deviation of the web causes a change in the volume of air escaping through the aperture 10. If the volume increases, the pressure acting on the diaphragm 21 decreases, so that the diaphragm moves downward and permits a needle valve 37, 39 to open more. This gives rise to a pressure drop in chamber 34, whereupon diaphragm 20 moves downward and allows a greater volume of air to pass through opening 23 to the servo-valve 7 and thence the pressure box 13. A reduction in the volume of air escaping from the aperture 10 causes a reduction in the through flow of air to the pressure box. This results in the diaphragm 15 pressing air back to the servo valve 7 via conduit 16, thereby increasing air pressure on the top side of a diaphragm 52. The diaphragm 52 therefore leaves the seat 56, allowing air to escape to atmosphere via groove 63, duct 64 and a control valve 65. The control valve 5 is designed such that in extreme cases when the diaphragm 20 shuts off the outlet opening 23 and the duct 27, the duct 27 will be opened before the outlet opening 23 is uncovered. This is achieved by having the centre of gravity of a circular washer 44 (bolted to the diaphragm) at a point opposite that part of the inside of the outer part 18 from which the duct 27 starts.