Molten-resin extrusion device and extrusion method as well as molten resin molding machine and molding method

Abstract

Provided is a method for extruding molten resin in a charging space from a head by converting a rotational motion of an electric motor into a linear motion of a piston disposed in the charging space through a ball screw and thus causing the piston to move vertically, the charging space being a space into which the molten resin can be charged and formed in an accumulator, the head having an extrusion port at a lower end thereof. The method includes a step of separating an upper plate from a lower plate and retracting the upper plate upward by a rotational motion of the electric motor and then charging the molten resin into the charging space with a sufficient charging pressure to push up the piston against weights of the lower plate and the piston in the charging space, the lower plate being disposed over the accumulator and coupled to the piston from above, the upper plate being engaged with the electric motor through a screwing relationship and disposed over the lower plate so as to be able to surface-contact the lower plate and a step of extruding the molten resin from the extrusion port by moving the upper plate downward with the upper plate and the lower plate surface-contacting each other by a rotational motion of the electric motor and thus moving the piston downward in the charging space.