| 摘要 |
Heated seal bars are located on opposite sides of an elongated strip of heat sealable material adapted to be advanced with a step-by-step motion. When the strip dwells, the bars are shifted linearly inwardly into engagement with the strip to form a heat seal and then are retracted linearly a short distance away from the strip to permit the strip to advance through its next step. If an abnormal condition prevents the strip from advancing, the bars are retracted linearly to a parked position in which the bars are spaced a substantial distance away from the strip in order to prevent the heat radiating from the bars from damaging the stopped strip.
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