Continuous extrusion of lead cable-sheaths

The paper deals primarily with a new development in methods of producing lead cable-sheaths, in which the pressure required to extrude the lead is obtained by means of a motordriven screw member instead of by the ram of a hydraulic press which has hitherto been universal practice. The author´s experiments were commenced in 1929 when the first lead pipe was extruded by a continuous process, and the development has continued steadily up to the present day, and to the stage where commercial continuous lead-extrusion machines are now being delivered. After reviewing in detail the disadvantages of former methods in order to explain the reasons for the development, the paper describes the construction and operation of the continuous lead-extrusion machine, and from considerations of the physical and metallurgical properties of the sheath demonstrates the improvements in the product achieved. As the advantages attendant on the use of the continuous lead-extrusion machine are associated to some extent with the methods employed in melting the lead, and in the handling of the cable as it comes from the machine, special attention has been given to these features alongside the development of the machine itself. The paper describes improved lead handling and melting equipment and automatic reeling mechanism for he finished cable.