Abstract: Plastic bags are obtained from a tubular foil of thermoplastics by means of heatsealing. The heatsealing member acts upon a lower wall of the flattened non-tensioned tubular foil, and without a counter pressure to the upper wall of the foil. The entire thickness of the lower wall is plasticized but only a portion of the thickness of the upper wall is plasticized. The assembly of heated lower wall and partly heated upper wall facing each other is passed through two pressure rolls, the roller surface contacting the surface which has not been in contact with the heat sealing member consisting of metal is cooled.

Abstract: A device for manufacturing corrugated plastic tube by subjecting an internally unsupported corrugated plastic tube, at a temperature between 30.degree. and 70.degree. C, to the simultaneous action of at least two punching members in one or in two corrugations.A device comprising a guide for corrugated plastic tube, and punching means with an operating member for simultaneously acting upon at least two punching members spaced a short distance from each other.

Abstract: Plastic bags are obtained from a tubular foil of thermoplastics by means of heatsealing. The heatsealing member acts upon a lower wall of the flattened non-tensioned tubular foil, and without a counter pressure to the upper wall of the foil. The entire thickness of the lower wall is plasticized but only a portion of the thickness of the upper wall is plasticized. The assembly of heated lower wall and partly heated upper wall facing each other is passed through two pressure rolls, the roller surface contacting the surface which has not been in contact with the heat sealing member consisting of metal is cooled.

Abstract: Apparatus for continuously producing seals in tube-shaped plastics film material, comprising means for supplying the web of material, at least one heating beam travelling along with the web and subsequently returning, means for keeping the web mechanically tension-free at the location where it is warm, means for keeping the heated film layers one against the other up to a pressing station, said pressing station comprising two rollers at least one of which is provided with cooling means, and means for discharging the web. A plurality of heating beams being provided which are interconnected by flexible and longitudinally adjustable means such as belts so as to form an endless loop which is guided over and driven by appropriate adjustable tensioning rollers.

Abstract: A method for manufacturing corrugated plastic tube by subjecting an internally unsupported corrugated plastic tube, at a temperature between 30.degree. and 70.degree.C, to the simultaneous action of at least two punching members in one or in two corrugations.

Abstract: A band of bags of plastic material connected with each other by perforation lines. In the two end parts of each perforation line the number of perforations and/or the width of the perforations per unit of width is greater than in the central part of the perforation line. A device for manufacturing said band of bags comprises a perforating member with equidistantly spaced first perforating pins and second perforating pins are present on either side of a central area between the first perforating pins.

Abstract: A device for directing strips of thermoplastic material which is provided with a first roller and first movable needles or photo electric cells, for correcting the position of the strip in a longitudinal direction in which the first roller and the first needles or cells are driven at the same rate, and second movable needles or photocells and a second roller for correcting the position of the foil in a transverse direction with, the second movable needles or cells and second roller being driven at the same rate.