JPS6039240Y2 - Sprue-cooling mechanism in injection molds - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sprue cooling mechanism in an injection mold.

When injection molding resin, a sprue is used to inject molten resin material from an injection molding machine into an injection mold.

Conventional sprue bushings include one resin passageway that is approximately circular when viewed in a plane substantially perpendicular to the axis of the resin passageway, and this resin passageway extends from the nozzle of the injection molding machine to the runner of the injection mold. We were connected.

However, in the conventional sprue structure, the cooling of the resin near the nozzle does not progress due to the influence of heat from the nozzle of the injection molding machine, and thread-like resin debris may be generated when the mold is opened.

If the next injection molding operation is performed with this filamentous resin debris adhering to the surface of the product part of the injection mold, the filamentous resin will emboss on the product surface within the injection mold, significantly impairing the quality of the molded product.

The present invention aims to solve this problem by improving the resin passage structure of the sprue bush to promote cooling of the resin between the nozzle of the injection molding machine and the injection mold. The sprue has a star-shaped polygonal shape when viewed on a plane that intersects the axis of the sprue to promote cooling of the resin in a part of the sprue and prevent the generation of filamentous debris between the nozzle part of the injection molding machine and a part of the sprue. It is.

This will be explained below with reference to the attached drawings.

Figure 1 shows the mold opening state in a conventional device, in which the injection space is formed by a fixed mold 3 and a movable mold 5 placed on the substrate 1 of the injection molding machine, and the nozzle part 7 of the injection molding machine is The resin is injected into the injection space through the resin passage (sprue) 9a in the sprue bush 9.

After cooling the injection molded product, the movable mold and sprue 9b are separated from the fixed mold 3 and the mold is opened, as shown in FIG.

However, the resin passage 9a of the conventional sprue bush 9 has a substantially circular cross section as shown in FIG. The resin in the center is not sufficiently cooled due to the thermal influence from the nozzle 7.

When the mold is opened, as shown in FIG.
Continuing as.

When the movable mold is further separated, the cut resin debris adheres to the surface of the movable mold 5 as shown by the chain line 11' due to rebound during cutting.

If the next injection molding is performed with the filamentous resin debris 11' adhered and solidified to the surface of the product part of the movable mold 5, the filamentous resin will emboss on the product surface, impairing the quality of the product.

The present invention will be explained with reference to FIG.

In the figure, the same parts as in FIG. 1 are given the same numbers and their explanations are omitted.

FIG. 3 shows the state of the apparatus of the present invention just before injection molding, and the resin passage (sprue) of the sprue bush 19 has an inlet side 19a near the nozzle 7 over a predetermined length D, as shown in FIG. It has a polygonal cross section, and the lower outlet side 1
9b has a substantially circular cross-sectional shape.

As described above, the resin at the joint between the nozzle 7 and the sprue bush 19 of the injection molding machine has a special shape so that the area of contact with the sprue bush 19 is increased. is promoted, and no filamentous layer is formed when the mold is opened.

Therefore, product defects will not occur during the next molding.

In addition, the above-mentioned length D is 3rrr! It is preferable to set n to 1-.

If it is longer than this, removal from the sprue bush 19 tends to be difficult, and if it is shorter than this, the cooling effect tends to be insufficient.

[Brief explanation of drawings]

Figure 1 is a front sectional view showing the mold opening state of the conventional device;
The figure is a view taken along the arrow ■-■ in FIG. 1, FIG. 3 is a front cross-sectional view showing the state of the device of the present invention just before injection, and FIG.
It is a TV arrow view. 3...Fixed type, 5...Movable type, 9,1
9... Sprue bush, 9a, 19a*
19b...Resin passage, 7...Nozzle,
9b sprue.

Claims (1)

[Scope of utility model registration request] In an injection mold that uses a sprue for the resin passage from the nozzle part of the injection molding machine to the product part, the resin passage of the sprue near the mating part of the nozzle part of the injection molding machine is placed on a plane that intersects the through axis. A sprue cooling mechanism for an injection mold, characterized in that the cut cross section of the sprue has a star-shaped polygonal shape to promote cooling of resin in a portion of the sprue.