Cryogenic crushing device and cryogenic crushing method for preparing polymer powder

The invention relates to a cryogenic crushing device and a cryogenic crushing method for preparing polymer powder. The cryogenic crushing device comprises a liquid nitrogen supply unit, a feeding unit, a mechanical crushing unit, a screening unit and an exhaust unit which are communicated in sequence; the feeding unit is used for feeding a polymer material into the device and mixing the polymer material with liquid nitrogen to obtain a mixed material; the mechanical crushing unit is used for crushing the mixed material to obtain polymer powder; the screening unit is used for screening the qualified polymer powder to obtain polymer powder with various particle sizes; and the exhaust unit is used for exhausting the gasified nitrogen out of the cryogenic crushing device. By means of the device, polymer powder can be fully crushed, and repeated freezing treatment on the polymer powder is avoided, so that the crushing efficiency of the polymer powder is improved, and energy is saved. 本发明涉及制备聚合物粉末的深冷粉碎装置和深冷粉碎方法，所述深