JP5885559B2 - Injection molding equipment - Google Patents

Description

The present invention relates to an injection molding apparatus used resin products when injection molding.

  Injection molding is a general method for molding plastics, in which a resin material melted in a high-heat cylinder is poured into a mold and cooled for a certain time to solidify to produce a molded product.

By injection molding, to produce a good quality product stable, the mold design, it is necessary to finely set the molding conditions or the like, relates to the structure and forming the shape condition of the mold, have been various measures ing. One of them is a gate structure for injecting molten resin into a cavity in a mold.

  When injection molding a relatively large resin product, a method of injecting molten resin into a single cavity formed in a mold through a plurality of gates (hereinafter referred to as a multi-point gate method). Has been adopted.

  When a plurality of products are manufactured at the same time, a method (hereinafter, referred to as “multiple manufacturing”) in which a molten resin flow path is connected to each of a plurality of cavities is employed.

In the case of a multi-point gate, the molten resin that has flowed in from each gate during resin molding merges in the cavity of the mold and is fused before they are completely melted to form a weld line. In the multipoint gate, due to the characteristics of resin molding, it is inevitable that a weld line is generated on the surface of the product.

  However, because the weld line is formed by the collision of molten resin that has flowed from different directions, the weld line is generated where the orientation of the resin structure of the resulting resin product is uneven and the strength is weak. There is an inconvenience that it is easy.

  In addition, since the weld line impairs the appearance, it is necessary to adjust the place where the weld line occurs to a part that does not cause a problem in appearance. For this reason, the position of the weld line is adjusted by adjusting the amount of molten resin flowing from each gate.

  On the other hand, in the case of a large number of molds where injection molding is performed by injecting molten resin into multiple cavities during mass production, the amount of molten resin flowing from each gate is adjusted so that the filling time for each cavity is uniform. There is a need to. If the inflow state of the molten resin is different between the cavities, it may cause burrs or defective molding.

  As described above, it is necessary to adjust the inflow amount of the molten resin flowing from the gate in either case of multi-point gates or multi-piece gates.

  In the following Patent Document 1, the amount of molten resin is adjusted by using a valve gate provided with a valve at each gate. However, this method has the disadvantage that it is expensive due to the complexity of the equipment.

  Therefore, as shown in Patent Document 2 below, the inflow amount of the molten resin is adjusted by adjusting the thickness of each gate indicated by the opening cross-sectional area into the cavity. According to this method, there is an advantage that the inflow amount of the molten resin can be adjusted with a relatively simple configuration, but there is a problem that clogging occurs in a gate having a small opening cross-sectional area (so-called thin thickness).

JP 55-86727 A JP 2001-179786 A

  It is an object of the present invention to eliminate clogging of molten resin in an injection molding apparatus when adjusting the amount of molten resin flowing in by reducing the gate thickness and reducing the opening cross-sectional area into the cavity. And

The present invention provides an injection molding apparatus in which a cavity formed by two injection molds and a flow path of molten resin are communicated with each other by a plurality of gates. At least one of the plurality of openings having a relatively small opening area communicates with the cavity, and has a flow rate adjustment unit having a predetermined thickness and an opening area as compared with the flow rate adjustment unit. A small solidification suppressing portion, wherein the solidification suppressing portion is provided so as to extend in the flow direction of the molten resin in a convex shape in the flow rate adjusting portion.

  According to the present invention, since the solidification suppressing portion is provided on the flow rate adjusting portion, the distance from the surface where the molten resin contacts the mold to the center of the flow path of the molten resin is increased at the center of each gate. Therefore, it is possible to suppress heat from being taken away from the mold. Thereby, it is possible to suppress clogging even when the flow of the molten resin in the gate becomes slow.

  Moreover, since the part which gives the thickness of an opening area as a solidification suppression part is small, since the increase in the supply amount of molten resin can be suppressed, defects, such as a wrinkle, do not arise. Accordingly, there is no need to make a significant change with respect to setting of molding conditions.

  In this invention, it is preferable that the said solidification suppression part is provided so that it may protrude on the up-and-down both sides of the said flow volume adjustment part.

By providing the solidification suppression part so as to protrude on both the upper and lower sides of the flow rate adjustment part provided with a constant thickness, the distance from the surface part in contact with the mold to the center of the molten resin flow path is further increased at the gate center. Therefore, the occurrence of clogging or the like can be further suppressed.

The end view of an injection mold. (A) shows the gate shape of Embodiment 1 which has a solidification suppression part, (B) is sectional drawing which shows the gate shape of Embodiment 2 which has a solidification suppression part on both sides. (C) Sectional drawing of the conventional gate shape.

  Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an end view of one of a plurality of gates of an injection mold. The high temperature molten resin flows from the nozzle 1 and flows in the molten resin flow path 2 and flows into the cavity 5 formed by the first and second two injection molds 3 and 4 and solidifies. To do. At this time, it is necessary to adjust the amount of resin flowing in from the plurality of gates 6 to adjust the position where the weld line is generated to a position where there is no problem in terms of the appearance and strength of the product, or to prevent the generation of burrs. There is. For this reason, the amount of the molten resin flowing from the plurality of molten resin flow paths 2 is adjusted by the size of the opening area of the joint portion of the gate 6 with the cavity 5 (so-called “gate thickness”).

  In general, a gate called “restricted gate” is used in injection molding. In the gate 6, a portion having a reduced cross-sectional area is provided between the molten resin flow path 2 and the cavity 5 to adjust the flow rate of the molten resin so that the above-described problems such as weld lines and burrs do not occur. It is to do.

  As described above, the gate 6 that needs to adjust the flow rate of the molten resin according to the shape of the molded product or the like adjusts the inflow resin amount according to the thickness. Therefore, the dimensions and shape of the gate are closely related to each element such as the shape and size of the molded product, resin, molding conditions, product accuracy, and the design of the gate is important in injection molding.

  FIG. 2 shows the gate shape at the section II-II in FIG.

  A cross-sectional shape of a normal gate 6 is shown in FIG. The opening where the gate 6 is connected to the cavity 5 is provided with only the flow rate adjusting portion 8, and the thickness is kept constant. In each gate 6, the area of the opening is adjusted by adjusting the thickness d of the flow rate adjusting unit 8, and the amount of molten resin flowing into the cavity 5 is adjusted.

  The thickness of the gate varies depending on the product to be manufactured, but is usually designed to be 1 mm or less. Therefore, in the pressure holding process, when the flow of the molten resin is delayed with respect to the gate having a small thickness, the molten resin is easily affected by the temperature of the mold, which causes clogging.

On the other hand, the gate shape in the first embodiment shown in FIG. 2 (A), the gate 6, a convex solidification suppression unit 9 is provided to extend in the flow direction of the molten resin at flow rate regulator 8. According to this embodiment, since the distance from the portion where the molten resin is in contact with the mold to the center of the molten resin flow path can be increased, the molten resin is prevented from being cooled by the mold, and clogging or the like occurs. Can be prevented.

  In this embodiment, the gate thickness d is about twice the thickness of the opening of the flow rate adjusting unit 8 in the portion where the convex solidification suppressing unit 9 is provided on one side of the flow rate adjusting unit 8.

Further, since the gate thickness d is thick only at the center of the gate 6 , the opening area of the opening on the cavity 5 side of the gate 6 is the opening area of the flow rate adjusting unit 8 and the opening of the solidification suppressing unit 9. It is the sum of the areas. Therefore, the amount of the molten resin flowing into the cavity can be reduced as compared with the case where the gate thickness is increased to a constant thickness over the entire opening. As a result, in order to suppress an increase in the amount of the molten resin flowing into the cavity 5 while suppressing the cooling of the molten resin, the occurrence of molding defects such as wrinkles is suppressed.

In Embodiment 2 shown in FIG. 2 (B), the solidification suppression part 9 is provided in the up-and- down both sides of the flow volume adjustment part 8. FIG. Thus, the thickness of the gate 6 can be further increased by forming the gate shape having the solidification suppressing portions 9 on both sides. According to this shape, the gate thickness can be increased by about three times compared to the gate having a constant thickness shown in FIG. Therefore, the resin is not easily affected by the temperature of the mold, and clogging of the resin can be prevented.

  The gate of the above embodiment does not require a special structure like a valve gate, and can prevent clogging during injection molding with a very simple configuration in which the solidification suppressing portion 9 is provided at the opening of the gate. . In addition, the amount of molten resin flowing into the cavity 5 can be kept low as compared with the case where the gate thickness is made constant and thick by the conventional method, so that problems such as wrinkles do not occur.

  In addition, the shape of the gate according to the present embodiment is versatile, which can be used for both “multi-point gate” and “multiple gate”.

DESCRIPTION OF SYMBOLS 1 ... Nozzle 2 ... Molten resin flow path 3 ... 1st metal mold | die 4 ... 2nd metal mold | die 5 ... Cavity 6 ... Gate 8 ... Flow control part 9 ... Solidification suppression unit

Claims (2)

In an injection molding apparatus in which a cavity formed by two injection molds and a flow path of a molten resin are communicated by a plurality of gates,
The plurality of gates communicate with the cavity through openings having different opening areas,
Among the plurality of openings, at least one of the openings having a relatively small opening area includes a flow rate adjusting unit having a predetermined thickness and a solidification suppressing unit having an opening area smaller than that of the flow rate adjusting unit. Prepared,
The solidified reduction unit, an injection molding apparatus characterized in that it is provided to extend in the flow direction of the convex to the molten resin in said flow rate regulator. The injection molding apparatus according to claim 1,
The said solidification suppression part is provided so that it may protrude in the up-and-down both sides of the said flow volume adjustment part, The injection molding apparatus characterized by the above-mentioned.

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