Abstract: A method and device for cooling molds circulating in a horizontal plane, in which siphon action is used to pass cooling liquid from a top gutter through the molds. In this way the whole cooling system is becoming constructively simplified, such that production speeds can be increased, with the consequent greater length of the cooling system, but without its becoming unduly complicated. This effect is realized irrespective of the nature of the machine or the number of molds.Method and device are especially advantageous when applied with the manufacture of plastics tube, more particularly yet with the manufacture of plastic corrugated tube.

Abstract: Method of and device for making perforations in the inner gusset portions of a tubular web of plastics foil which is provided with side gussets. Such perforations serve to remove air from the interior of bags to be manufactured from the tubular web. According to the invention the gussets are opened over a distance sufficient to introduce, in the interior thereof, a punching member, which is activated by exerting a pressure from outside the tubular web. A device adapted to perform this method comprises a separate carrier provided at either one of its ends with rolls and adapted to be introduced into the interior of the tubular web where it is supported and maintained in its place lengthwise of the web, by two sets of rolls which are situated at the exterior of the tubular web. The carrier is provided with perforating units and the machine frame outside the tubular foil is provided with means to exert through the web material, a force and to activate the perforating units.

Abstract: A method of making seals in tubular web provided with side gussets, in which method, after making the seals, sensors for the inner gusset edges are withdrawn outwardly over a certain distance, the position of the sealing devices remaining unchanged, and after transport of the tubular web, the sensors are moved inwardly again and the new position of the inner gusset edges is observed, subsequently, when a difference is observed as compared with the previous time, the position of the sealing devices is brought into correspondence with this observation before making the next seal.

Abstract: Apparatus for making profiled plastic tube and comprising two circulating endless chains, each making a plurality of mold halves move along with a tube coming from an extruder, these mold halves pairwise constituting a mold cavity in which the tube is being given its profile. According to the invention the molds are movable relative to the chain links in a direction perpendicular to the direction of movement of the links. The machine frame is provided with guides for the mold halves, some located interiorly, others exteriorly, with respect to the chain loop, such that once closed, the cavity formed by the pairs of mold halves will remain closed and undisturbed up to the end.Preferably the transitions between curved portions and the operative portion of the path of the mold halves at the entrance and the exit ends are bending points of mathematically calculated paths and the operative straight path tangentially joins said transitional portions.

Abstract: A method for manufacturing perforated plastic pipes, in particular corrugated thermoplastic pipes of which the wave valleys are perforated by at least one punching member, to which a velocity is imparted in the direction of conveyance of the plastic pipes, which equals the rate of conveyance of these pipes. During the punching operation the punching member or members retain substantially a perpendicular position with respect to the plastic pipes.