Process and apparatus for direct chill casting

Abstract

A process and apparatus are described for direct chill casting. The apparatus comprises an open ended mould cavity formed by a casting surface with an upper and lower end. A refractory sleeve is located at the upper end of this mould cavity and has an inner diameter less than the inner diameter of the mould, whereby the sleeve forms an overhang with the mould cavity. This sleeve is adapted to receive molten metal. Below the lower end of the mould, means are provided for supplying coolant to chill the descending hot metal body thereby forming an ingot. A permeable wall element is disposed in the peripheral wall of the mould cavity below the overhang and this element has an inner wall forming part of the cavity. Means are provided for feeding gas into and through the permeable wall element to discharge through its inner wall. An annular oil plate is mounted between the overhang and the permeable wall element and this oil plate has grooves in its bottom face thereby providing access for lubricating oil to the mould cavity. An oil supply means for feeding a volumetrically controlled amount of lubricating oil through the grooves to the mould cavity. In this way, oil and gas are supplied to the mould cavity to form an oil and/or gas layer between the metal and the wall of the mould.