String mould plant including arrangement for preventing shrinkage voids in metal castings

摘要

In a string of molds (32) with vertical parting surfaces, each mold cavity (35) is connected through a wide throat with its own after- feeding reservoir (36). When the mold has been poured, a gas pressure is applied through a channel (43) and a passage (41) to a lower metal surface in the after-feeding reservoir (36). This gas pressure is not allowed to exceed the metallostatic pressure in the mold at the surface, at which the pressure is applied, until the metal in the ingate (37) has solidified or the ingate has been blocked in some other way. At the location where the passage (41) opens into the after-feeding reservoir, it is covered by an element (42) that is impermeable to the metal having been poured but permeable to the pressurized gas. When the metal in the ingate (37) has solidified or the ingate has been blocked in some other way, the gas pressure may be increased.