Hierarchical expand tube formula buffering dust fall blanking plug of porthole

The utility model belongs to an engineering blasting porthole choked technique field, unsatisfactory for solving the stifled plug member jam effect of present porthole, explosion back dust is too high, does not reach environmental protection effect's problem, provides a hierarchical expand tube formula buffering dust fall blanking plug of porthole. Precracking I is established to tail pipe both ends symmetry, and the bayonet is established down to the both ends outer wall, and the multi -level buffer device is fixed to the tail pipe anterior segment, and the back end is a spalling section of thick bamboo, towards the big gun hole, the multi -level buffer device is a plurality of expanded tube joints, and precracking II is established to the expand tube anterior segment, and the bayonet is established down to the anterior segment outer wall, and a section of thick bamboo is inserted for glossy cylinder to the expand tube back end, and anterior segment and back end are connected by a toper section of thick bamb