Abstract: An injection molding machine having a simple structure and adapted to quickly operate for injection molding without taking in air bubbles is provided. The injection molding machine comprises a plunger and a nozzle for injecting the molten metal fed from the plunger into a metal mold. The plunger has a cylinder section with a through hole bored through an upper portion of its lateral wall for introducing the molten metal, and a piston for slidingly reciprocating within the cylinder section. A communication hole is bored through the piston and communicates with the through hole at a predetermined position. The communication hole runs from the lateral wall of the piston through the inside thereof and has a non-return valve arranged therein to allow only a flow from the lateral wall of the piston.

Abstract: In a mold for molding a slide fastener slider, a first template has a first part of a cavity for molding a rear section of an outer contour of the slider body except an upper surface portion of an upper wing and also has a first core for molding a rear section of an element guide channel of the slider body; a second template which is movable toward and away from the first template has a second cavity part for molding a front section of the outer contour of the slider body and also has a second core for molding a front section of the element guide channel; and a third template which is slidable on the first and second templates has a third part of the cavity for molding a pull-tab attaching lug of the slider body and an outer contour of the upper surface portion/shape of the upper wing. For molding, these templates are brought together to form the cavity, and then molten molding material is poured into the cavity via a channel and a sprue.

Abstract: An injection molding machine having a simple structure and adapted to quickly produce molded products without significant flaws on the surface is provided. It comprises a plunger being adapted to introduce the molten metal into the cylinder section, a nozzle for injecting the molten metal fed from the plunger into a metal mold and a piston arranged within a cylinder section of the plunger to slidingly reciprocate. It includes a piston drive unit for driving the piston to slidingly reciprocate, a stopper member for controlling the retracted position of the piston drive unit and a position selecting unit for defining a projected position and a retracted position for the stopper member.