Method for forming insulating electrical conductor

Claim 1

A method of forming an insulation layer upon an electrical conductor comprising: passing the conductor along a feedpath through a passage of a die insert with lateral clearance, towards an outlet orifice of the die insert and also, with lateral clearance, through the outlet orifice while lying in contact with a part only of the surface of the insert which defines the orifice, and passing the conductor through a die orifice to extrude onto it elastomeric material for forming the layer while contact of the conductor with said surface part of the insert guides the conductor into a particular lateral position as it passes through the orifice; monitoring the radial position of the conductor within the layer; and controllably moving the conductor laterally of its feedpath at a position upstream from the outlet orifice of the die insert dependent upon the eccentricity of the conductor by combining movements of the conductor in two planes so as to cause the conductor to change its angle of approach to the outlet orifice to alter the angle of departure from the outlet orifice and hence its lateral position within the die orifice to achieve concentricity of the conductor within and surrounding clearance from a surface defining the die orifice.

Claim 2

A method of forming an insulation layer upon an electrical conductor comprising: passing the conductor along a feedpath through a passage of a die insert with lateral clearance, towards an outlet orifice of the die insert and also, with lateral clearance, through the outlet orifice while lying in contact with a part only of the surface of the insert which defines the orifice, and passing the conductor through a die orifice to extrude onto it elastomeric material for forming the layer while contact of the conductor with said surface part of the insert guides the conductor into a particular lateral position as it passes through the orifice; monitoring the radial position of the conductor within the layer; and controllably moving the conductor laterally of its feedpath at a position upstream from the outlet orifice of the die insert dependent upon the eccentricity of the conductor by combining movements of the conductor in two planes so as to cause the conductor to change its angle of approach to the outlet orifice to alter the angle of departure from the outlet orifice and hence its lateral position within the die orifice to achieve concentricity of the conductor within and surrounding clearance from a surface defining the die orifice.