| 摘要 |
<p>A horizontal form-fill-seal machine has counter-rotating sealing jaws 5 and 6 whose progress is monitored by photocells PC1 and PC2 such that once the jaw 6 passes photocell PC1 the speed of the motor driving the sealing jaws is lowered to provide increased dwell time to achieve adequate seal strength without the need for high sealing temperatures, and the speed is then increased once the jaw 6 passes photocell PC2 and enters the "rest phase" before the next sealing operation. The motor speed control is such that despite varying machine throughput speeds, the dwell time of the film between the jaws 5 and 6 at the sealing station is substantially constant to provide for optimum seal strength at the optimum sealing temperature of the film being used. <IMAGE></p> |
