STRAPPING MACHINE HAVING PRIMARY AND SECONDARY TENSIONING UNITS AND A CONTROL SYSTEM THEREFOR

摘要

A strapping machine and method for applying flexible heat-sealable straps around objects includes a programmable control system that receives encoder and other signals from various sensors in the machine to regulate each strapping cycle. A feed/tension unit provides primary tensioning of the strap about the object based on signals from the control system. A motor driven roller and a pinch roller in the feed/tension unit each providing separate encoder signals to the control system to assist the control system in advancing and retracting the strap during feed and tensioning sequences, respectively, and provide signals indicating an exact position of the strap. A secondary tension system provides a final high tensioning force on the strap. The control system can automatically adjust individual strapping cycles, including tensioning, to compensate for various size bundles and different types of objects. Thereafter, a sealing head heat seals the strap, and severs the sealed strap from the remaining strap coil. The control system can selectively disengage the secondary tensioning during individual strapping cycles for objects that could be damaged or deformed during such high tensioning.