Spherical valve housing - for plug valve moulded in plastics

摘要

In a mould for a spherical valve housing with an internal spherical cavity and a supply duct joining the cavity to the outside, a mobile pressure core projects into the centre of the cavity. A smooth surface is formed by allowing for the replenishment of material due to shrinkage. The pressure core forms a cone whose nose is near the centre of the mould cavity. The nose contains the supply duct. The mould cavity is carefully polished.