A nozzle touch mechanism which does not allow an injection unit to move
back by the force of inertia at the time of acceleration of injection and
prevents leakage of the molten resin. A damper is arranged between the
injection unit and a stationary platen secured to a base, so as to
generate a strong braking force only at the time of high acceleration of
the injection unit. A ball screw is rotated by driving an electric motor
to move forward a nut member screwed onto the ball screw, whereby the
injection unit is moved via a spring. When the injection unit is stopped
by contacting a nozzle to a metal mold, the spring is contracted. When
the amount of contraction of the spring reaches a predetermined value,
the motor is stopped and locked such that the nozzle touch force
corresponding to the amount of contraction of the spring is generated.
Even though the injection unit undergoes the force working to move back
the unit due to the inertia force at the time of acceleration of the
injection, the injection unit is not moved back because the damper
substantially prevents the movement back of the unit and the leakage of
molten resin.