| 摘要 |
Web splicing apparatus employs a pair of driven nip rolls which controllably feed web from a running roll into a festoon as web is drawn out of the festoon at a constant rate by a downstream web consuming machine. The nip rolls are driven by a DC motor connected in a closed loop servo system which compares the speed of the web entering the festoon with the web line speed to develop a command signal for the motor. During normal operation, the command signal includes a web velocity trim signal developed by monitoring the position of the festoon dancer relative to a selected reference position so as to minimize tension upsets and to maintain the dancer within its control range. During a splice sequence, the command signal comprises a deceleration ramp having a selected slope to provide controlled deceleration of the web to minimize tension upsets and to permit actuation of the splicing nips prior to actual web stop. After the splice is made, the command signal comprises an acceleration ramp whose slope is automatically adjusted to apply the least necessary tension to the ready web for new roll acceleration consistent with a given splicing speed. Further with this arrangement, the gain of the system is independent of the changing size of the expiring roll.
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