Abstract: A method for producing a tube section from thermoplastic material, in which a tube section is extruded by means of an extruder which is provided with an extruder die having an inner core, which inner core defines an axial hollow space in the tube section, the tube section coming out of the extruder die downstream of the extruder die being internally cooled by means of an internal cooling member and externally cooled by means of an external cooling device. Immediately after the tube section leaves the extruder die, the internal cooling member brings about internal cooling of the tube. The external cooling device is positioned downstream of the internal cooling member, so that the external cooling of the tube section is brought about after the internal cooling.

Abstract: A method for producing a tube section from thermoplastic material, in which a tube section is extruded by means of an extruder which is provided with an extruder die having an inner core, which inner core defines an axial hollow space in the tube section, the tube section coming out of the extruder die downstream of the extruder die being internally cooled by means of an internal cooling member and externally cooled by means of an external cooling device. Immediately after the tube section leaves the extruder die, the internal cooling member brings about internal cooling of the tube. The external cooling device is positioned downstream of the internal cooling member, so that the external cooling of the tube section is brought about after the internal cooling.

Abstract: A method for forming an integral socket to a pipe made from biaxially oriented thermoplastic material is described. The pipe has a pipe body and is provided, at one or both ends, with an integral socket. The biaxially oriented thermoplastic pipe is subjected to a socket-forming operation comprising the steps of fixing both axial ends of the unheated end part of the pipe, heating the fixed end part to a suitable socket-forming temperature in one or more steps, and expanding the axially fixed end part with the aid of a fluid pressure in the interior of the end part and/or a vacuum on the outer side of the end part, which expansion may begin as early as during the heating of the end part.

Abstract: Apparatus and method for producing a hollow plastic section by extrusion through a die in a horizontal direction. The die has an inner mandrel which forms the cavity in the section. A first sealing plug and a second sealing plug, which sealing plugs are situated at a distance from one another downstream of the inner mandrel are attached to the inner mandrel. The sealing plugs are designed, during operation of the apparatus, to lie in the hollow section, such that they are sealed against the section, so that the sealing plugs and the section delimit a compartment in the cavity of the section. The compartment is filled with a liquid during operation of the apparatus. Vent means are located in the compartment for receiving and discharging gases or vapor which collects at the highest point of the compartment.

Abstract: A method for producing a tube section from thermoplastic material, in which a tube section is extruded by means of an extruder which is provided with an extruder die having an inner core, which inner core defines an axial hollow space in the tube section, the tube section coming out of the extruder die downstream of the extruder die being internally cooled by means of an internal cooling member and externally cooled by means of an external cooling device.

Abstract: Method for treating an extruded plastic section having a hollow space and installation suitable for carrying out such a treatment. The installation includes an extruder which has a core for forming the hollow space in the section and, at a distance downstream from the extruder in the extrusion direction of the section, a closing means having a rigid circumferential wall. The installation also has a first conduit connected to a supply orifice which is provided in the circumferential wall of the closing means, a fluid feeder connected to the first conduit and a second conduit connected to a discharge orifice. The discharge orifice is upstream of the supply orifice to provide a fluid film flowing opposite to the extrusion direction between the circumferential wall of the closing means and the extruded section.

Abstract: A method for forming a socket on a pipe of biaxially oriented polyvinyl chloride including: placing a support in an end section of the pipe, heating the pipe in the region of the end section; deforming the pipe to produce a socket in the region of the heated end section, the heated end section being supported internally while the socket is being formed; cooling the pipe in the region of the end section, the end section being supported internally during the cooling operation; and removing the support from the pipe. For the purpose of heating the internally supported end section of the pipe, the end section is first heated until the end section has reached, substantially homogeneously, the glass transition temperature of polyvinyl chloride and is then further heated until the end section has reached, substantially homogeneously, a temperature near, preferably just above, the orientation temperature of polyvinyl chloride.

Abstract: A tubular profile made of thermoplastic material is formed by extrusion from an extruder. Downstream from the extruder, the tubular profile is cooled both externally and internally by an external cooling unit and an internal cooling unit mounted on the extruder. A tensile force is exerted on the cooled tubular profile downstream from the cooling units by a pulling device. When the extruder is set in operation to start the production of the tubular profile, the internal cooling unit is left out. When the pulling device applies the tensile force on the extruded and externally cooled tubular profile, the internal cooling unit is introduced into the tubular profile from the open end of the tubular profile and is mounted on the extruder.

Abstract: Method and devices for manufacturing biaxially oriented tubing from thermoplastic material. The method includes forcing the tube over a mandrel at an orientation temperature of the plastic material, which mandrel includes an expansion part which produces expansion in the circumferential direction of the tube. The forcing over the mandrel is achieved by exerting a pushing force on the tube upstream of the expansion part of the mandrel by a pushing device acting upon the outside of the tube, and by exerting a pulling force on the tube downstream of the mandrel. The pushing device acts upon the tube at a distance upstream of the mandrel, and the tube is supported between the place where said pushing device acts and the expansion part of the mandrel.

Abstract: A method for manufacturing biaxially oriented tubing from a thermoplastic material. The method includes forcing the tube over a mandrel at an orientation temperature of the plastic material, which mandrel is an expansion part which produces expansion in the circumferential direction of the tube. Downstream of the mandrel an axial pulling force is exerted on the tube, and the biaxially oriented tube is cooled down. At a distance downstream of the mandrel, the tube is drawn through a calibration opening bounded by a calibration device, the calibration opening being such that it produces a reduction in the external dimensions of the tube. Accurate regulation of the external dimensions of the tube is provided by regulating the distance between the mandrel and the calibration device, in particular depending on the external dimensions of the tube measured downstream of the calibration device.

Abstract: Welding sleeve comprising electrically conductive material embedded in the thermoplastic material of the wall of said sleeve.In a sleeve at least two connecting means are present which each comprise at least two metal parts which can cooperate in clamping contact with the electrically conductive material.One metal part is inserted from the inside of the sleeve and one part from the outside; appropriate coaxial bores being present to allow passage of a pin on the lower part and the body of the upper part.Upon mounting the upper part and lower part are connected with use of a force; the electrically conductive material is clampingly contacted.The invention also relates to a method for forming a welding sleeve according to the invention and to an equipment for use in carrying out such a method.