Methods of and apparatus for making an insulated transmission medium

A method of making an insulated elongated transmission medium, said method comprising the steps of:

• moving an elongated transmission medium along a path of travel in a direction along the longitudinal axis of the elongated transmission medium;
• while
• applying a molten plastic insulating material to the elongated transmission medium;
• directing each of a plurality of spray patterns of a coating material which comprise a first group of spray patterns toward the elongated transmission medium in such a manner that the coating material of each spray pattern of the first group is distributed in a generally conical configuration;
• and then
• directing each of a plurality of spray patterns of the coating material which comprise a second group of spray pattern toward the moving elongated transmission medium in such a manner that the coating material of each one of the spray patterns of the second group has a substantially planar distribution as the coating material of each spray pattern of the second group is directed into engagement with the elongated transmission medium and such that the direction of each of the spray patterns of the second group is at a predetermined angle to the path of travel with the direction of each of the spray patterns of the second group having a horizontal component in a direction opposite to the direction in which the elongated transmission medium is moved the spray patterns of said second group being staggered along and spaced generally equiangularly about the path of travel and cooperating to prevent unintended undulations of the moving elongated transmission medium as the coating material is applied thereto, the second group being spaced from the first group in a direction along the path of travel
• subsequently exposing the plastic insulating material to a cooling medium;
• and
• taking up the insulated elongated transmission medium.

An apparatus for making an insulated elongated transmission medium, said apparatus comprising:

• moving means for advancing successive increments of length of an elongated transmission medium along a path of travel;
• extruder means for applying a plastic insulating material to the elongated transmission medium;
• means for cooling the plastic insulating material;
• means for taking up the elongated transmission medium;
• a source of colorant material;
• first spray means disposed between said extruder means and said means for cooling the plastic insulating material connected to said source for directing each of a plurality of spray patterns of the colorant material toward and into engagement with the plastic insulating material, the distribution of the coating material of each of the spray patterns of said first spray means being in a generally conical shape;
• and
• second spray means disposed between said extruder means and said cooling means connected to said source and positioned after said first spray means in the direction of movement of the elongated transmission medium along the path of travel for directing a plurality of spray patterns of the colorant material toward and into engagement with the plastic insulating material, the spray patterns of said second spray means being staggered along the path of travel, spaced generally equiangularly about the moving elongated transmission medium and directed in different radial directions to the path of travel with the coating material of each of the spray patterns of said second spray means having a distribution which is substantially planar and being effective to stabilize the elongated transmission medium to prevent undulations of successive increments of length thereof as the colorant material is applied to the plastic insulating material, each of said plurality of spray patterns of said second spray means being directed to have a horizontal component in a direction opposite to the direction of movement of the elongated transmission medium.