METHOD OF HEATING MOULDS FOR THERMOPLASTICS MATERIALS AND MOULDS FOR CARRYING OUT THE METHOD

摘要

1,242,964. Moulding plastic substances &c. CEBAL G.P. AND SOC. DE TRAITEMENTS ELECTROLYTIQUES ET ELECTROTHERMIQUES. 22 July, 1969 [23 July, 1968], No. 36836/69. Heading B5A. [Also in Divisions H3-H5] In order that heat may be generated in the vicinity of the walls surrounding the mould cavity 3 of a two part metal mould 1, 2, which parts are electrically insulated from one another at their adjacent faces 11 and 21, the parts are electrically interconnected by a conductor 40 at one end and are provided with separate terminals 41, 42 at the opposite end, the terminals 41 and 42 are connected separately to the poles of a high frequency source. The use of high frequency and the mutual inductance of the parts 1, 2 of the mould confines the resistance heating path to the walls of the cavity 3 immediately adjacent the cavity. Thermoplastic material may be moulded in the cavity or a blank may be placed in the cavity. The mould may be made of magnetic or non-magnetic stainless steel. The frequency of the source may be from 100KHz-10MHz.