Abstract: In a method for manufacturing a mold of a metal hot-runner injection molding machine, a temperature gradient of metal disposed in a nozzle between a heating device of the nozzle and a tip of the nozzle is measured. Then, an area in the nozzle is selected based on the measurement of the temperature gradient such that the metal in the nozzle upon a mold opening has a temperature at which a solidified condition of the metal can be stably maintained, where the temperature is close to a melting temperature of the metal. A gate cut portion is determined in the area.

Abstract: A mold for a metal hot-runner injection molding machine includes a movable mold plate, a fixed mold plate having a nozzle for injecting molten metal into said cavity, and a heating device disposed outside the nozzle for heating metal. A gate cut portion is situated in the nozzle between the heating device and the tip. A temperature measurement device is arranged adjacent to the gate cut portion for measuring the temperature of the metal in the gate cut portion. A heating control device is connected to the heating device for controlling a temperature of the nozzle on a basis of the temperature measurement device. A heat insulation device is arranged on the nozzle to cover at least an area where the gate cut portion is formed. By controlling the temperature of the nozzle, metal injection molding without runner can be made.

Abstract: In an induction heating coil unit for a manifold in a hot runner mold, it is possible to uniformly heat a material over the entire length of a runner. Also, a coil is easily attached to and detached from the manifold. The hot runner mold includes a fixed mold and a movable mold, and a space is provided along a side surface of the manifold on which clamping force applied by the fixed mold and the movable mold does not act. A coil is wound to the side surface along an axial line of a runner of the manifold within the space such that the manifold is induction-heated from the side surface.

Abstract: In an induction heating method for a manifold in a hot runner mold, it is possible to uniformly heat a material over the entire length of a runner. Also, a coil is easily attached to and detached from the manifold. The hot runner mold includes a fixed mold and a movable mold, and a space is provided along a side surface of the manifold on which clamping force applied by the fixed mold and the movable mold does not act. A coil is wound to the side surface along an axial line of a runner of the manifold within the space such that the manifold is induction-heated from the side surface.

Abstract: An improved injection molding nozzle shows a high hardness and is chemically stable so that the inner surface thereof is not corroded nor the gas or the fluid forced to penetrate into the gap between the injection molding nozzle and the valve pin seize the valve pin regardless of the temperature and the pressure of the material to be injected. Additionally, the valve pin is not pliable and does not give rise to a collapse on the part of the valve pin. The injection molding nozzle to be used for resin and molten metal is characterized in that it is made of a ceramic material and at least part of the outer periphery is covered with metal.

Abstract: The present invention provides an induction heating method for a manifold in a hot runner mold where it is possible to uniformly heat material over the entire length of a runner and in which a coil may be easily attached to and detached from the manifold.

Abstract: The present invention provides a induction heating coil bobbin used to heat the hot runner in an injection molding machine, the bobbin comprising a substantially cylindrical body made of a metal or alloy having its low magnetic permeability, the bobbin body having at least one slit formed therein, the slit extending on the bobbin body between the opposite ends thereof through a predetermined length.