| 摘要 |
685,363. Automatic tension control systems. HOE & CO., Ltd., R. June 7, 1949 [June 4, 1948], No. 15170/48. Class 38 (iv). In a web tension control apparatus the degree of wrap of a retarding belt round the web-roll is determined by the web tension, and the motor controlling the application of the belt is supplied from an impulse generating network. As shown, Fig. 1, the web 4 is unrolled from roll 3 and its tension detected by floating roller 6 supported on arm 13 mounted to rock about centre 14. Arm 13 controls, through linkage 15, a switch 16, Fig. 2, which determines the direction of motion of motor 17. Roll 3 is retarded by the endless belt 7, which is driven by gearing 11 at a speed 2 per cent lower than the speed of web 4 and the extent of wrap of the belt round 3, and therefore the braking effect, is determined by the adjustment of arm 12 by the motor 17 about axis 18. The forward and reverse coils 24, 25 of the motor are energized respectively by closure of contacts 20, 21 of switch 16 and the supply is rendered intermittent by relay 30, the coil G1 of which is energized periodically from the impulsing network A. In the latter, the condenser C is alternately charged and discharged by the contact E moved by coil D connected across C; the contact H, in series with G1 is moved with E. |
