Abstract: An extruder for synthetic material is disclosed which includes an extruder housing provided with at least two worm conveyer shafts, each having one or more helices thereon. An inlet opening is provided in the housing at the extruder input for introducing the synthetic material and a degassing outlet is provided in the housing downstream of the inlet. Intermediately of the material inlet and degassing outlet, distributing members are arranged on the worm shaft peripheries, the distributing members comprising intermeshing tooth-shaped heightened parts of generally hemispherical configuration.

Abstract: The invention relates to a sandwich tube comprising an inner and an outer fiber reinforced layer of thermosetting resin and an intermediate layer therebetween consisting of inorganic filler material coated with thermosetting resin and obtained by spraying a finely divided resin into a case of loosely laid inorganic filler material. A non woven is present between the intermediate layer and the outer fiber reinforced layer.

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: Method for automatically removing a synthetic resin article from the die of an injection moulding machine, whereby this article during the time that the die halves are in the open position, is removed and conveyed into a particular direction by a grab, whereupon a lateral transfer and supporting member discharges the article.

Abstract: A pipe connection for plastic pipes particularly fiber reinforced synthetic pipes made of thermosetting resin, comprising a female pipe part with a widened end of which the inside tapers from the free end and adjoins a longitudinally extending recess in the inner wall of the female pipe, the male pipe part having a protruding part adapted to this recess and having a first end face that on its end adjoins a conical end face which is adapted to the conical shape of the inside of the aforementioned widening, and a glue layer extends from the inside of the pipe connection as far as the outside of the male pipe part. Preferably the protruding part consists of an inner, chemically resistant, layer of a fiber reinforced synthetic resin pipe, which on its outside carries a fiber reinforcement and the inner side of the conical widening has a greater inner circumference which is considerably greater than the outer circumference of the male pipe part.

Abstract: A pipe having an annular ring of a foam plastic material on its outer surface and a covering layer of thermoplastic material on the outer surface of the foam plastic ring. An opening between two free ends of foam plastic layer ring lying opposite each other of adjoining pipes is closed by a connecting layer which cooperates sealingly with the covering layers. A ring of rigid material is positioned under the covering layer at the point where the connecting layer is clamped onto the covering layer.

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: Device for making a perforation in film material, especially plastics film material, said device comprising a reciprocatable support beam for a plurality of perforating blades the cutting edges of which are saw-tooth shaped. A driving means moves, simultaneously with the support beam a series of suction members in the direction of the operative position and back, said series extending with minor spacing substantially parallel to the perforating blades. Means are provided for the support beam and the series of suction members to perform, during displacement between the operative position and the rest position, but at a distance from the operative position, a relative displacement in the longitudinal direction, such that the top film layer is cut through while the other layer remains just perforated.

Abstract: Plastic socket of fibre reinforced thermosetting material comprising an inner push edge, a first recess at each end for positioning sealing means, which are held by means of a retaining ring which is accommodated in a second recess. The inner wall between the first recess and the push edge tapers outwardly.

Abstract: A device for manufacturing profiled hollow tubing comprising an extruder and two endless rows of die halves guided over guiding wheels provided with first recesses having one depth and second recesses which are shallower, such that subsequent moulds halves contact each other before coming into contact with the plastics tube as extruded.

Abstract: A method and apparatus for butt welding two surfaces of different polyethylenes by heating the two surfaces up to different temperatures at which the viscosities of the two different polyethylenes of the two surfaces are equal. The heating device for heating the polyethylene surfaces comprises two separate plates which can be heated up to different temperatures. The device is also provided with pressure regulating means for controlling the pressure at which the two surfaces are pressed onto each other.

Abstract: A foam plastic layer is sprayed onto a metal pipe, whereafter a tape of polyethylene at the extrusion temperature is helically wound around the foam layer.

Abstract: A plastic bag with zig zag plies provided with a tubular valve foil sealed on the one hand to an outwardly folded tubular foil part originally situated between two incisions along zig zag ply edges and on the other hand to an end seal of the tubular foil and at last to the tubular foil by a seal extending between the end points of the said incisions and said end seal.The plastic bag may be provided with an outer lining or covering bag for protecting the bag. The covering bag is provided with an opening for passage of the tubular valve foil.

Abstract: The invention relates to a method for providing a thermoplastic pipe with an inner groove, by subjecting a heat plasticized pipe to the action of some rotatably supported deforming rollers which are expanded and rotated by means of a mandril. A relative rotating motion between said deforming rollers and the pipe is maintained until the pipe is no longer permanently deformable and the relatieve rotating motion is maintained to strengthen the walls of said groove.

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 manufacturing a plastic tube with transverse or helical grooves consisting of an extruder, two movable halves of die with an inner ribbed profile and being capable of forming a hollow mould, said halves of die each provided with circular elongations for heating the region between the opening of the extruder and the beginning of the mould, an inflatable member in the tube for conforming the tube to the profile of the mould. The inflatable member comprises a movable cylinder having two expandable end discs, an inlet and an outlet for compressed medium being situated between the two end discs, the valve closing said outlet being loaded by a spring such that only pressure medium will escape after the end discs have formed a closed space with the inner side of the tube.

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.

Abstract: An extruder for synthetic material with at least two mixing and conveying worms, comprising an extruder housing, an extruder inlet, a driving member for driving one of the worms and a gearing for driving the second worm, said gearing comprising two gear wheels with inclined toothings. These gear wheels are mounted on either side of the mixing and conveying worm and cooperate therewith.