the present invention relates to a rubber injection molding nozzle , and an injection molding machine and method using the nozzle , used mainly for the injection molding of rubber articles such as rubber vibration insulators for automobiles . it is aimed to increase the molding efficiency and productivity of rubber products and to reduce production cost . at least one portion of an injection channel extending through the injection molding nozzle is formed as an orifice having a non - circular flattend cross section , such that , at least at around major axial ends , a dimension measured orthogonal to its major axis gradually decreases as either of major axial ends is approached . for example , in the cross section , two opposed curved interior wall faces join together to form an acute - angled corner , at major axial ends . this construction enhances the effect of the internal heat generation of the rubber passing through the non - circular cross - sectional portion , facilitating the temperature rise even at center core portion of the rubber . thus , curing time is shortened thanks to temperature rise of the whole rubber due to the internal heat generation .