Air valve fitted to plastics bag - by punching and welding head opposite support plate on which bag rests

摘要

Appts. for fitting an air valve to a thermoplastic sheet already in the form of a partly completed bag, comprises a support plate, having a central bore connected to an air suction line and arranged so that the still open mouth of the plastics bag can be fitted over the support plate. Opposite to the support plate and aligned with its central bore is a plunger for forming the hole in the bag and an annular heating plate which descends onto the periphery of the thus formed hole to seal it around the valve. The valve itself is fed from the side into the insertion and welding position through a feed duct. Pref. this valve feed duct has a transverse branch, along which the valve is pushed by a lever linkage into the final position. Used esp. for fitting an air valve into a plastics bag which has already been sealed along three sides, the fourth side remaining open. The appts. ensures that any flash or waste material from the punching out of the hole is extracted via the suction duct. PS.