GB568184A - A mould for moulding articles made of rubber and other thermoplastic and thermosetting materials and a method of making the mould - Google Patents

Abstract

568,184. Glass articles. GOULD, C. T. May 8, 1943, No. 7304. [Class 56] [Also in Group V] A mould for shaping rubber and other thermoplastic and thermosetting materials comprises two complementary glass bodies which are moulded in and surrounded by metallic jackets having a coefficient of expansion substantially equal to that of the glass bodies over the working temperature range of the mould. The metallic jackets may be made from an alloy known as " Kovar A " (Registered Trade Mark), and the glass may be "hard" glass or boro-silicate glass. Fig. 2 illustrates the manufacture of a mould for making spheres. Two half-spherical pattern sections 5, 6 are secured to a separating plate (or plates) 7, and the plate is disposed between ledges 9, 11 on metallic jackets 3, 4. The jackets and pattern are heated to a temperature above the melting point of the glass to be used, and the jackets are filled with glass 1, 2. The whole is then placed under pressure and allowed to cool slowly, the plate with its pattern sections being finally removed. In modified procedures : (1) the jackets, sealed and filled with preformed glass in rod or other form, are heated under pressure ; (2) the cold jackets are charged with molten glass, the assembly being then pressed and heated simultaneously ; (3) the pressure may be applied after the assembly has been removed from the furnace ; and (4) the cold jackets are charged with powdered glass, which has previously been heated to expel moisture, and the assembly heated. The heat and pressure may be applied in a vacuum or in inert gas, and excess glass may be allowed to escape through apertures in the pressing tool or in the jackets. Fig. 5 illustrates the manufacture of a mould for making an article, Fig. 6, of varying configuration having an axial recess 14 at one end and a lateral screwthreaded hole 16. Two pattern sections 12, 13, integral with or separate from a separating plate (not shown) receive a cylindrical plug 17 and a screw-threaded tool 18. The plug is cast in the glass mould bodies and forms the recess 14 in the article. The tool 18 forms the hole 16 and is removable ; it is guided in a sleeve 18a. A heating and cooling coil 20 and other metal components may be cast 'in the glass.