Down-pressure adjustment mechanism for machine tool centre

The utility model discloses a down-pressure adjustment mechanism for a machine tool centre. The centre is fixed with a small supporting plate through an outer bracket; the small supporting plate is sleeved on a screw rod through a screw rod nut; a shaft sleeve and a spring are sleeved on the screw rod nut in a screw rod penetration hole of the small supporting plate; the spring is positioned in the shaft sleeve; the upper end of the spring is pressed against a necking section at the upper end of the shaft sleeve; the lower end of the spring is pressed on an annular boss on the wall of the screw rod penetration hole of the small supporting plate through a disk-shaped spring; an annular boss is formed on the outer wall of the upper end of the screw rod nut and used for downwards pressing the necking section of the shaft sleeve; a gasket is fixedly arranged on the upper end face of the annular boss; a screw is vertically arranged on the gasket; and a proximity switch matched with the screw is arranged on a recei