| 摘要 |
Apparatus for heat sealing sheets of thermoplastic material is constructed with a Nichrome strip constituting the heated die element. The die strip is mounted to the movable press element, with one end fixedly secured thereto, and the other end of the strip being free to move longitudinally as the strip temperature increases. The motion of the strip is transmitted through a motion multiplying linkage to operate a movable contact out of engagement with a stationary contact when the strip has reached a predetermined temperature, which will occur after sufficient heat for sealing has been applied and prior to the application of excessive heat. The movable contact is automatically latched in the open position to maintain the flow of heating power to the strip interrupted at the end of the sealing operation. The latch releases the movable contact when the cooled strip is moved out of sealing position so that when the strip is next moved to sealing position the movable contact automatically engages the stationary contact to complete the heating circuit for the strip.
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