Heavy reduction sector section used for overcoming plate blank looseness and shrinkage defects and application method thereof

The invention relates to the field of accessory equipment used for conducting posttreatment or postprocessing on cast blanks on site during metal continuous casting, in particular to a heavy reduction sector section used for overcoming the plate blank looseness and shrinkage defects and an application method thereof. The heavy reduction sector section used for overcoming the plate blank looseness and shrinkage defects comprises an upper frame (11) and a lower frame (12) and is characterized by further comprising a pair of big loose rolls (21), a pair of driving rolls (22), at least three pairs of small loose rolls (23), big loose roll reduction oil cylinders (31), horizontal oil cylinders (32), a driving roll reduction oil cylinder (33) and a water pipe (4). The application method of the heavy reduction sector section used for overcoming the plate blank looseness and shrinkage defects is characterized in that the method is implemented in the following steps that a casting blank is pulled into the sector section; extrusion is conducted, specifically, the rolling reduction no less than 10 mm is applied to the casting blank; and the casting blank is pulled out of the sector section. According to the heavy reduction sector section used for overcoming the plate blank looseness and shrinkage defects and the application method thereof, the quality of the casting blank is high, and the looseness and shrinkage defects barely occur.