In a die cushion apparatus, a pressurizing force acting on a die cushion
pad is applied to a first piston of a hydraulic cylinder unit by the
operation of a slide, the first piston slides inside a first cylinder and
pressure oil in a first hydraulic chamber is pressurized. The first
hydraulic chamber is linked to a second hydraulic chamber of a booster
cylinder unit via a second check valve, so that the pressure oil of the
first hydraulic chamber is pushed out into the second hydraulic chamber.
When the pressure of the first hydraulic chamber is applied to a second
piston, the second piston slides inside the second cylinder and gas of a
gas pressure chamber is compressed, whereby a surge pressure is reduced.