Low melting point metal material injection molding method, injection molding device and body box

A metal injection molding apparatus, comprising:

• a metal mold having a first die and a second die connectable together to form an injection molding cavity defined by respective internal die surfaces of the first and second dies when the first and second dies are connected together, the respective internal die surfaces spaced apart from one another at a cavity height;
• and
• at least one convex part integrally formed with the first die and projecting from the internal die surface thereof into the injection molding cavity, the at least one convex part having, as viewed in cross-section, a base section disposed from the internal die surface of the first die at a convex part height and a pair of sidewalls with each sidewall connected to and extending from the internal die surface of the first die by a first curved portion, each sidewall tapering inwardly toward the base section and connected to the base section by a second curved portion extending between a respective sidewall and the base section, the first curved portion having a first radius with a center of radius disposed in the injection mold cavity and the second curved portion having a second radius disposed internally of the at least one convex part, wherein
• each sidewall tapers inwardly toward the base section at an inclination angle in relation to a line that extends perpendicularly to the base section in a range of approximately 3° and 5°, the convex part height is approximately 25% to 40% of the cavity height and each one of the first radius and the second radius is in a range of approximately 8% to 17% of the convex part height.

A metal injection molding apparatus, comprising:

• a metal mold having a first die and a second die connectable together to form an injection molding cavity defined by respective internal die surfaces of the first and second dies when the first and second dies are connected together, the respective internal die surfaces spaced apart from one another at a cavity height;
• and
• at least one convex part integrally formed with the first die and projecting from the internal die surface thereof into the injection molding cavity, the at least one convex part having, as viewed in cross-section, a base section disposed from the internal die surface of the first die at a convex part height and a pair of sidewalls with each sidewall connected to and extending from the internal die surface of the first die by a first curved portion, each sidewall tapering inwardly toward the base section and connected to the base section by a second curved portion extending between a respective sidewall and the base section, the first curved portion having a first radius with a center of radius disposed in the injection mold cavity and the second curved portion having a second radius disposed internally of the at least one convex part,
• wherein each sidewall tapers inwardly toward the base section at an inclination angle in relation to a line that extends perpendicularly to the base section in a range of approximately 3° and 5°, the convex part height is approximately 25% to 40% of the cavity height and each one of the first radius and the second radius is in a range of approximately 8% to 17% of the convex part height.