Vertical form, fill and seal packaging machine with improved back-up bar

Abstract

A package making machine of the vertical form, fill and seal type has a tube former for receiving packaging material in thin flat strip form and for juxtaposing opposite side edges thereof in parallel vertically extending and overlapped relationship to provide a depending tube open at the top. A product dispenser discharges measured quantities of product to the tube interior space, a lower end portion thereof being sealed transversely by an end sealing apparatus. Tube advancing means may comprise intermittently operable vertically extending vacuum belts or, alternatively, the end sealer may be reciprocated vertically to draw the strip material downwardly through the former. At a longitudinal seam sealing station beneath the former a vertically elongated sealing bar moves to engage and to seal the overlapped longitudinal edges of the tube. A sealing back-up bar within the tube is pivotally supported at its mid-point by a depending support member and freely adjusts angularly to provide precise parallelism and uniform pressure distribution between and throughout the length of the sealing and back-up bars. Narrow elongated tube spreaders depend within the tube to maintain the tube open in cooperation with the back-up bar and its support member, a relatively unobstructed product fall space thus being provided.