Method and apparatus for forming thermoplastic bags

Abstract

Abstract AN INFLATED SEAMLESS THERMOPLASTIC TUBE IS CONTINUOUSLY EXTRUDED FROM A THERMOPLASTIC MELT AND IS CONTINUOUSLY FLATTENED INTO A FLATTENED WEB OF SUCH TUBING, THE WEB BEING SIMULTANEOUSLY CONTINUOUSLY LONGITUDINALLY FED AT A SUBSTANTIALLY CONSTANT SPEED. THE LONGITUDINALLY FEED AT A OF THE CONTINUOUSLY FED WEB IS INTERMITTENTY STOPPED AND TRANSVERSELY HEAT SEALED AND PERFORATED WHEN IT IS STOPPED TO PROVIDE THE WEB WITH LONGITUDINALLY SPACED HEAT SEALS AND PERFORATIONS DEFINING SEPARABLY CONNECTED BAGS THEREIN. THE HEAT SEALED AND PERFORATED WEB IS CONTINUOUSLY LONGITUDINALLY WITHDRAWN AT A SUBSTANTIALLY CONSTANT SPEED CORRESPONDING TO THE SUBSTANTIALLY CONSTANT FEEDING SPEED. SLACK IS PROVIDED IN THE CONTINUOUSLY FED WEB AND THE CONTINUOUSLY WITHDRAWN WEB TO ALLOW STOPPING OF TH WEB FOR HEAT SEALING AND PERFORATING PURPOSES. THE SLACK IN THE FED WEB IS PAID OUT AN IN THE WITHDRAWN WEB IS TAKEN UP EQUALLY WHEN WEB IS NOT STOPPED AND THE SLACK IN THE WITHDRAWN WEB IS PAID OUT AND IN THE FED WEB IS TAKEN UP EQUALLY WHEN THE WEB IS STOPPED FOR EQUALIZING AND MAINTAINING SUBSTANTIALLY CONSTANT TENSION IN THE ENTIRE FED AND WITHDRAWN WEB. THE CONTINUOUSLY WITHDRAWN HEAT SEALED AND PERFORATED WEB IS PREFERABLY WOUND IN A ROLL FOR EASE IN SUBSEQUENT HANDLING.

Inventors

• 👤 J Abler

Bibliographic Details