PURPOSE: To prevent a sand blockade by a method wherein a switch valve is installed at a communication part between a hopper and a hollow pipe and the air in the hollow pipe is obstructed to escape from the hopper and further, the air in the hollow pipe is compressed.
CONSTITUTION: A hopper 8 and a short pipe 9 are coupled through a flange; and the short pipe 9 and a hollow transmission shaft 6 are coupled through a rotary joint 10 and a seal 11, thus, even when the hollow transmission shaft 6 rotates, the turning effort is not transmitted to the short pipe 9 and further, together with this, an air tight structure is provided. And further, a switch valve 12 obstructs the air escape from a hopper 8 and when compressed air is supplied from a pipe 13 for supplying the compressed air, the switch valve 12 closes automatically and when air is exhausted from a pipe 14 for the exhaust use, the switch valve 12 opens automatically. As result thereof, sand blockade is prevented and together with this, the hopper does not rotate, thus, sand supply is performed easily and stabilized.
TSUJI TERUHIRO
TANIMURA KIMITAKA
