Patent GB-468779-A (GB)
Title: Improvements in apparatus for producing a uniform tension in winding devices
IPC: B65H23/18
Filed: 1935-10-10
Abstract: 468,779. Fluid-pressure servomotorcontrol systems. BRETSCHNEIDER, M. Oct. 10, 1935, No. 28012. Convention date, Oct. 11, 1934. [Class 135] [Also in Group XVI] A servomotor device for maintaining a constant tension in material being wound to and fro by winding devices, particularly those used in jigger dyeing machines, has the driving mechanisms for the winding rollers fitted with hydraulic, pneumatic, electrical or mechanical braking devices operating against resistances regulated by mechanism controlled by the tension of the material so arranged that whichever roller is for the time being acting as the winding-on roller an increase in tension causes the resistance regulating the winding-on roller to increase whilst the resistance regulating the winding-off roller is decreased. In the form shown in Fig. 1, hydraulic brakes are used controlled by a fluid-pressure servomotor system. The web 5 tensioned by an oscillating device 6 passes from a roll 3 to roll 4 or vice versa through a dye bath 10. Rollers 11, 12 resting in the web are mounted in a frame 13 carried by a rod 14 partly counter balanced by a weighted lever 16 and fitted with an adjustable dashpot 92. A lever 19 pivoted to the rod 14 is formed with a slotted extension 21 having a cam part 23 adapted to actuate a three-armed lever 25 with a slotted part 27 coupled by a link 29 to a floating lever 31. This lever is pivoted at one end to a piston control valve and at the other end is slotted to engage a pin on a rod 59 fitted with centralizing loading springs 63, 64. A dashpot piston 58 on the rod 59 works on a dashpot cylinder 57 which is fitted with an adjustable byepass 61 and is mounted on the piston rod of the main servomotor. Motive fluid is supplied by a pump 45 to a reservoir 41 from which it passes through a piston shut-off valve 42 and adjustable throttle 43 to the control valve 39. The main servomotor comprises a pair of pistons 53, 55 arranged to actuate a piston valve 54 adapted to control a port tapered at each end. This port controls the discharge pipes 74, 79 from two gear pumps 70, 75 operated synchronously with the rolls and adapted to act as hydraulic brakes under the control of the piston valve 54. Each pump is fitted with four non-return valves 72 arranged so that one conduit is always the discharge pipe whichever direction the pumps are rotated. In a modification, dynamos replace the gear pumps, dry or wet rectifiers the non-return valves, switches the control valve 39 and electrically operated resistances the main valve 54. When the direction of winding is to be reversed the rod 33 is moved causing the pin 28 to move to the opposite end of the slot 27. The Specification as open to inspection under Sect. 91 comprises also an oscillating tensioning device, Fig. 2 (Cancelled), in which the supporting shaft is adjustable in height parallel to itself. The tensioning rollers 113, 114 are carried by parallel arms 112 on a tubular member rotatably mounted by ball bearings on a shaft 9. This shaft slides in slots in the main frame and at each end carries pinions 118 meshing with fixed racks 117 so that when the shaft is rotated it is raised or lowered. The shaft may be counterbalanced by a weight suspended from a cord passing over a pulley on the shaft. A modification is described in which the shaft is supported by pistons working in liquid pressure cylinders under the control of a screw-operated piston valve. This subjectmatter does not appear in the Specification as accepted.