| 摘要 |
<p>For accurately determining, in real time, the collapse of a thermoplastic workpiece (34) processed in a press, such as an ultrasonic welding apparatus (10) or a vibration welding apparatus (10), a two-phase method is used. In the calibration phase signals are generated which are responsive to the yielding or displacement of the movable press portion relative to the substantially stationary portion arising from forced engagement of the workpiece within the press. The force responsive displacement value is stored. In the subsequent workpiece processing phase, when the workpiece collapses due to the softening and flowing of thermoplastic material as the workpiece is coupled to vibrations, the previously stored force responsive displacement value is recalled as a correction signal and subtracted from the newly obtained displacement signal related to the same force. The result of the subtraction is a true on-line signal indicative of the collapse of the workpiece as it occurs.</p> |
