Main shaft knife loosening and unloading mechanism

The invention provides a main shaft knife loosening and unloading mechanism. The mechanism is characterized in that a gland is coaxially fixed on the rear end face of a main shaft; a nut is fixed on a broach rod; a thrust bearing of a knife loosening structure is fixed at the front end of a piston; the piston is arranged in a cylinder body; an unloading disc fixed together with the cylinder body is arranged on the upper surface of the boss of the gland to form an overlap joint; a cylinder sleeve is fixed on a headstock, and is arranged in the same mounting hole together with the cylinder body; a spring is arranged between the periphery of the tail end of the piston and the cylinder body; the cylinder body, the cylinder sleeve and an unloading mechanism installation hole on the headstock jointly form a negative closed oil cavity; an axial oil injection port is processed on the rear part of the cylinder body, and forms a positive closed oil cavity together with the piston; and a radial oil injection port is pro