Abstract: An electric wire that has a conductor held by spacers in a covering of polytetrafluoro-ethylene (PTFE), continuous cells being formed between the covering, the spacers, and the conductor. In an axial section, the majority of the PTFE fibers of the spacers point in a substantially radial direction, thereby imparting excellent robustness to the spacers. A method of manufacturing such an electric wire, in which method an extrudate of PTFE is caused to pass through an extrusion passage around the conductor in such a manner as to form the covering; so that: upstream from an expansion section, the covering is formed by a guide; and downstream from this section, the cells are formed by section members, the spacers being formed by filling expansion channels situated between walls of the section members.

Abstract: An electric wire comprises a non-oxidized conductor of copper alloy having no outer coating and in direct contact with a PTFE-based sheath. It is fabricated as follows: providing a copper alloy conductor without an outer coating; forming a sheath of a PTFE-based material around the conductor; and heating the wire in order to evaporate the lubricant and sinter the sheath. In order to avoid oxidizing the copper during the heating step, the wire is heated mainly in an atmosphere having a low oxygen content. The lubricant evaporation and/or sintering line for stabilizing the sheath of the electric wire comprises one or more ovens, each having an enclosure in which an atmosphere having a low oxygen content is maintained.

Abstract: An electric wire comprises a non-oxidized conductor of copper alloy having no outer coating and in direct contact with a PTFE-based sheath. It is fabricated as follows: providing a copper alloy conductor without an outer coating; forming a sheath of a PTFE-based material around the conductor; and heating the wire in order to evaporate the lubricant and sinter the sheath. In order to avoid oxidizing the copper during the heating step, the wire is heated mainly in an atmosphere having a low oxygen content. The lubricant evaporation and/or sintering line for stabilizing the sheath of the electric wire comprises one or more ovens, each having an enclosure in which an atmosphere having a low oxygen content is maintained.

Abstract: An electric cable for conveying signals, the cable having a diameter of less than 2 mm and comprising at least one conductor in an insulating sheath, the sheath having a dielectric constant ? of less than 1.7. To achieve this, the sheath is made of PTFE and it includes at least one continuous cell.

Abstract: An electric wire that has a conductor held by spacers in a covering of PTFE, continuous cells being formed between the covering, the spacers, and the conductor. In an axial section, the majority of the PTFE fibers of the spacers point in a substantially radial direction, thereby imparting excellent robustness to the spacers. A method of manufacturing such an electric wire, in which method an extrudate of PTFE is caused to pass through an extrusion passage around the conductor in such a manner as to form the covering; so that: upstream from an expansion section, the covering is formed by a guide; and downstream from this section, the cells are formed by section members, the spacers being formed by filling expansion channels situated between walls of the section members.

Abstract: An electric cable for conveying signals, the cable having a diameter of less than 2 mm and comprising at one conductor in an insulating sheath, the sheath having a dielectric constant ? of less than 1.7. To achieve this, the sheath is made of PTFE and it includes at least one continuous cell.

Abstract: Thermoforming a plastics material part, in particular a plate. According to the invention, the thermoforming unit comprises at least two molds (2, 3) of respective shapes that enable the shape of the material (1) being worked to be caused to vary progressively up to a final mold giving the desired shape. A thermoforming method using such a thermoforming unit.

Abstract: A method of manufacturing a PTFE tape whose density is less than or equal to 0.3 g/cm.sup.3, the method being characterized in that a raw PTFE tape is subjected to a first step of stretching while being heated so as to reduce its density to within the range 0.7 g/cm.sup.3 to 0.30 g/cm.sup.3, after which at least one step is performed of the type including a stage during which the tape is stabilized without changing the state of the PTFE by being passed through an oven at a temperature and for a duration that are functions of the mass to be stabilized while keeping the tape under tension so that its density does not increase, followed by a stage of stretching under heating so that the density of the tape reaches a value lying in the range 0.2 g/cm.sup.3 to 0.12 g/cm.sup.3.