| 摘要 |
1,060,231. Feeding webs. MOUNT HOPE MACHINERY Ltd. April 7, 1964 [April 8, 1963 (2)], No. 14201/64. Heading B6B. [Also in Divisions F2 and G3] The tension of a web 12, Fig. 6, being unwound from a braked web-roll is detected by a roller 24, Fig. 2 (not shown), journalled to an upright 32 at one end, and supported by a pivoted lever 34 at the other end. A force balancing valve unit 40 for indicating and/or controlling the web tension comprises a pivoted flap valve member 46 loaded by a rod 41 with a force proportional to the web tension. The valve member 46 is supported by a pressure cylinder arrangement 60 including a sealing ring 64, which is supplied with high pressure air from a conduit 66. The pressure of the air in the conduit 66 is controlled by a valve 68, and the pressure gauge 70 gives an indication, when calibrated, of the mean tension of the web. A second conduit 22, with a needle valve 56, supplies a controlled flow of highpressure air to a fixed orifice in the part 49 of the valve unit 40. A resilient O-ring 50 mounted on the valve member 46 associates with the fixed orifice to provide a variable-area fluid-release orifice therebetween. Variations in the tension of the web 12, detected by the roller 24, results in variations of pressure in the conduit 22 due to the valving action of the valve member 46 on the fixed orifice. This variation of pressure is directly proportional to the tension changes from the mean tension in the web, and a suitably calibrated pressure gauge 58 is used to indicate these tension variations. The fluid cylinder 20 controlling the brake 14 of the web-roll can be connected directly to the conduit 22 to be controlled by the pressure therein. A pair of one-way check valves 80 and 84 arranged in parallel flow relation for opposed directions of flow may be incorporated to eliminate minor changes of pressure affecting the brake 14. The pressure cylinder support arrangement 60 may be replaced by a bellows, Fig. 5 (not shown). The fixed orifice and O- ring 50 arrangement may be replaced by a needle valve, Figs. 3 and 5 (not shown). In a modification, Fig. 1 (not shown), pressure cylinder support arrangement 60 is dispensed with, the flap valve member 46 being supported only by the pressure fluid emitting from the fixed orifice. The control device may be used to control a clutch forming part of a drive mechanism driving a web roll spindle when winding web. |
