GB350227A - Improvements in and relating to the manufacture of rubber articles - Google Patents

Abstract

350,227. Cores for moulding rubber articles. SOC. ITALIANA PIRELLI, 21, Via Fabio Filzi, Milan, Italy. June 2, 1930, No. 17056. Convention date, June 7, 1929. [Class 87 (ii).] A core for moulding rubber articles, which can be readily disintegrated for removal, is formed of a waterdispersible inorganic colloidal substance. Selected clays, chalks, kaolins, and argillaceous sands are referred to as suitable materials. A proportion of non-colloidal filling material such as sawdust or fine sand may be used, in addition to binding agents such as gum arabic or casein. The formed core may be coated with paper, gauze, or thin linen, which may be used to line the core-forming mould or applied after manufacture. Two compositions suitable for making cores for hot-water bottles are (1) Moulding sand 80 parts by weight, and water 20 parts, or (2) Smectic clay 75 parts and water 25 parts. The water is added to the solid material while in a mixing machine and the plastic material moulded in a two-part mould and subsequently dried in an oven at a temperature of 150‹ C. For making tyre cores an extrusion process is used. Fig. 1a shows the material extruded between two parallel plates provided with a grooved forming ring, while Fig. 2 shows it passed through a preliminary drying chamber D on to the revolving metal rim E of a cushion tyre. Hot or cold wa,ter under pressure, compressed air and steam may be used to remove or assisting in removing the cores from the completed article.