| 摘要 |
1292577 Automatic control of speed REGGIANI SpA 19 April 1971 [22 June 1970] 26877/71 Heading G3R [Also in Division B6] In a machine wherein material such as fabric is temporarily attached to a belt 1 as by glueing and is fed past at least one rotatable printing screen 6, the belt is driven by a motor-driven driving-pulley 2 and the screens 6 are rotated by a motor 18 through transmission gear 7, the speed of the motor 18 being regulated by transducer means producing output signals representative of the speed of the belt 1 so that the screens 6 rotate with a surface speed equal to that of the belt 1. As shown, a wheel 8 engaging and driven by the belt 1 is coupled by a shaft 27 to an electromechanical transducer 9 which produces a series of pulses with a frequency proportional to the belt speed. These pulses pass to an amplifier converter 10 controlling a step-by-step motor 11 which rotates through a constant angle for each pulse. The motor 11 through gears 12, 13 rotates a screw 14 causing axial displacement of a nut 15 which operates a hydraulic distributer 16 to connect a pump 17 to the hydraulic motor 18 which drives the screens 6. The motor 18 is coupled to the nut 15 by a transmission 19 so that during rotation of the motor, the nut tends to move towards its initial position until a stable position is reached wherein the motor 18 rotates at the required speed. The axis of the wheel 8 is adjustable in a horizontal plane, Figs. 2, 3 (not shown) so that the speed of the wheel can be regulated in relation to that of the belt 1 to compensate for errors due to slippage. An optical displacement sensor may be used instead of the wheel 8. When printing is interrupted by stopping the belt 1 and lifting the screens 6, the screens continue to be driven to prevent dripping of ink, etc., this being effected by a variable frequency squarewave generator 20 connected to the amplifier 10 and which automatically starts to operate when printing stops. |
