| 摘要 |
1325483 Automatic length control R W SCHMIDT 19 Aug 1970 [20 Aug 1969] 39895/70 Heading G3R The lengths of pieces cut from a continuouslyfed sheet are compared with a desired length and any error used to effect correction by adjusting the time of cut, each adjustment being terminated when its magnitude corresponds to the error. As applied to controlling the drive to a pair of counter-rotating blades arranged above and below the path of corrugated board so that it is cut into lengths as it is fed forward, a wheel 75, Fig. 3, engaging the board, produces a speed signal which is integrated at 78 for periods between successive cuts determined by signals produced by operation of the blades at 77. The resulting analogue or digital signals corresponding to the lengths cut are compared at 80 with a signal from 82 corresponding to a desired length so that a servomotor 58 is operated in a direction corresponding to the error to adjust at 56 the speed ratio of a Reeves drive 20 to the cutting blades. A pulse generator 66 produces a number of pulses corresponding to the extent of adjustment which is divided by a factor from 68 corresponding to the adjustment setting so that a number of pulses bearing a linear relationship to the change of speed is compared at 72 with a number of pulses corresponding to the error. When each speed correction corresponds to the error servomotor 58 is stopped. |
