Lost foam riser

The evanescent mode riser comprises a riser body with the bottom used for being connected with a casting and a heating shell arranged around the outer wall of the riser body, the heating shell is sequentially provided with a heat conduction material layer, a heating material layer and a heat preservation layer from inside to outside, and the top of the heating shell is provided with a cover body for sealing and covering the heat conduction material layer, the heating material layer and the heat preservation layer. A gas guide pipe extending out of the heating shell is arranged at the position, close to the bottom of the heating shell, of the riser body, and a sealing head is detachably arranged at the end, extending out of the heating shell, of the gas guide pipe. Negative pressure in the riser body can be effectively avoided, so that after the top in the riser body is solidified, metal at the bottom in a liquid state can still play a role in feeding, and the feeding capacity of the riser is improved. 一种消失模冒口