Stopper for reliable gas injection

摘要

The present invention relates to a mono-block stopper adapted to deliver gas during pouring of molten metal comprising a stopper body having an internal chamber (1) and a gas discharge port (2), a bore (3) connecting the internal chamber (1) to the gas discharge port (2), calibrating means (4) being provided in the bore (3) to provide a restricted path. This stopper is characterized by the fact that the calibrating means comprise a rod (4) reaching above the internal chamber (1) bottom and having at least one axially-extending gas passage. The gas passage or gas passages having a section such as to offer a predetermined resistance to flow.; Disclosed is also a process for the manufacture of the above-described stopper, the process comprising steps of introducing a refractory material into an appropriate mould; pressing the refractory material into the mould; removing the pressed stopper from the mould; firing the pressed stopper and introducing a rod (4) into the bore.