Abstract: Induction heating is used to heat a moving strip (4) of non-ferrous material by causing it to form a short-circuited loop acting as the secondary winding of a transformer (1), the loop passing over pulleys (6, 9, 5 or 16). In one arrangement, one of the pulleys (16) has a double groove and the strip (4) passes over one groove (18), around another of the pulleys (19) and back to the other groove (20) of the double grooved pulley (16). This enables the strip to enter or leave the inside of the loop without colliding with the other side of the loop. In an alternative arrangement, the strip enters or leaves the inside of the loop at an angle to the plane of the loop and is prevented from contacting the other side of the loop by an insulating spacer (7).

Abstract: A method for controlling a cellular foam cable coating extrusion process wherein the quench point or temperature of the foamed coating being extruded onto the core material, and the ratio of speed of extrusion to line speed of the extrusion process are simultaneously adjusted respectively in response to two error signals indicative of a variation in relative permittivity and annular area of extruded coating from required specified values. The method results in a faster process than possible heretofore while at the same time a tighter tolerance on deviation from required parameters is possible.

Abstract: It is known to anneal non-ferrous strip material by passing the strip continuously around a pair of spaced pulleys and effecting a short circuit between the incoming and outgoing strip material to form a closed electrical loop of continuously moving strip material around the pulleys. The material in the closed moving loop is heated to anneal temperature by inserting an induction coil in the run around the pulleys so that under electrical inductive effects a current is induced in the loop thus raising its temperature. The incoming and outgoing strip material overlaps in the groove of one of the pulleys, the incoming material being fed into the loop formation at the point of overlap in a spiralling path which leads or directs the strip laterally and towards the plane of the annealing loop. Loading of the pulleys is thus made easier, arcing and sparking is avoided at overlap, and the life of the system is extended.