Abstract: The invention is embodied in bag-making apparatus wherein a tubular web of thermoplastic film is intermittently advanced, in bag-length increments. In the dwell between successive advances, there is a cycle of sealing, cut-off and stack accumulation, the accumulation being onto needles to form a stack.The needles comprise a single group, forming part of a single transfer mechanism, operative (a) to transfer to a conveyor each successive needled stack, into partially lapped relation with the previously transferred stack, (b) to disengage its needles from the transferred stack, and (c) to return the needles to normal needling position, for anchored accumulation of bags as they are formed for the next stack.

Abstract: The invention contemplates an improved deflection-switch mechanism for a conveyor system which continuously handles a succession of articles, such as like sheets or sheet-like workpieces, on a first conveyor, and which sorts them in alternation to one and then to the other of two further conveyors, whereby in each of the further conveyors the sorted articles are more greatly separated and therefore can be subjected to more effective deceleration prior to their uniformly stacked accumulation. The deflection mechanism of the switch is vacuum-operative upon individual articles, relying upon their spatial distribution in the first conveyor as a basic determinant of whether a particular article is to be automatically deflected or switched, by effectively synchronous commutation, into one or into the other of the two further-conveyor paths.

Abstract: A conveyor surface for carrying off separated sheets in a web welding and separating machine is displaced from a welding gap between a welding roller having a welding tool and an opposing roller in the direction of the axis of the opposing roller. As the leading edge of a thin web passes beyond the welding gap, it tends to stay close to the surface of the opposing roller until it has been borne a substantial circumferential distance past the welding gap, whereupon it separates therefrom. A guide plate bridges a space between the opposing roller and the conveyor surface to smoothly transfer the separated sheets to the conveyor surface. An elastically compressible strip on the welding roller is optionally used to improve the separation of the leading edge of the web from the welding tool and to closely press it against the opposing roller.

Abstract: In an apparatus for forming and separating the side edges of plastic bags of the type which have opposed interlocking closure strips, an intermittent transport device transports a half-tube of thermoplastic sheeting to a welding device. The sheeting is stopped while welding is performed. At a milling station upstream of the welding device, a milling apparatus is actuated while the half-tube is stopped to mill off a short length of each of the opposed closure strips at a position which coincides with the position at which welding will later be performed.

Abstract: A first drive apparatus for a thermoplastic web operates at an automatically adjusted, substantially constant, speed to deliver the thermoplastic web to a welding tool which rotates with a second pair of rollers. The second pair of rollers are driven at a cyclically variable speed in which the minimum speed is attained at the time when the welding tool is in contact with the thermoplastic web. An automatic control system adjusts the speed of the feed rollers to correspond to the speed of the welding tool at the instant during which welding is performed. Adjustment of the ratio of the maximum to the minimum speed of the cyclically variable speed of the second pair of rollers controls the length of thermoplastic web between welds without changing the speed of the driving input to the second pair of rollers.

Abstract: A displacement device in a thermoplastic web welding apparatus withdraws the leading edge of the web from the welding apparatus during pauses in feeding and/or production to prevent melting and sticking of the leading edge.

Abstract: A step in a film bag conveyor for a bag making machine protects the unwelded ends of a stack of film bags being conveyed away from disturbance by web support air jets. The step optionally permits the welded bag ends to overhang and thereby reduce stack height.