Injection mold and injection molding method using the same

An injection molding method comprising:

• supplying molten resin into an extension cylinder which is installed within an injection mold and comprises opposite first and second ends and a nozzle extending from the second end, wherein the first end of the extension cylinder is coupled to an upper clamp plate and the second end extends through the upper clamp plate, and wherein the nozzle is adapted to be inserted into a nozzle position holder that is positioned under the upper clamp plate;
• separating a gate molded part from an injection-molded part by separating a cavity plate of an object mold which comprises the cavity plate and a core plate disposed under, the cavity plate and the core plate collectively forming a cavity having a shape of the injection-molded part inside the cavity plate and the core plate, from a gate-lock-pin holder disposed under the nozzle and comprising a gate lock pin, which is interposed between the cavity plate and the nozzle position holder, and a gate stripper plate which is disposed under the gate-lock-pin-holder;
• separating the gate molded part from the gate lock pin by separating the gate stripper plate from the gate-lock-pin holder;
• and
• separating the cavity plate from the core plate disposed under the cavity plate.