JPS5944215B2 - injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for injection molding, and more particularly, to a mold for injection molding which is improved so that the resin part of the gate part can be cut and removed at the same time as the product is released from the mold after injection molding. It is related to molds.

The injection mold of the present invention has been known for a long time.

It goes without saying that this includes various injection molds and their improved products in general, but also a pre-molded metal material, etc. is placed in a part of the cavity, and synthetic resin is injection molded onto this to make the metal material. It also includes so-called insert molding molds for obtaining embedded synthetic resin molded products. Injection molding has been known for a long time as the most representative method for obtaining various synthetic resin molded products, and the fields of application of injection molded products tend to increase more and more.

Along with this, various improvements have been made to injection molds, but no particular changes have been made to the basic structure. For example, FIGS. 1 and 2 are longitudinal cross-sectional views of essential parts illustrating a known injection mold and an injection molding method using the same, and show the case of molding a synthetic resin pipe joint. A normal injection mold has a structure in which a fixed mold 1 and a movable mold 2 are combined, and the mold includes a spool 3 and a spool 3 into which resin is press-fitted from an appropriate injection machine (not shown). A runner 4 forms a resin flow path between the runner 4 and the cavity, a relatively small-diameter gate 5 forms a sprue between the runner 4 and the cavity, and a cavity 6 formed to correspond to the shape of the injection molded product. are provided in communication. The fixed mold 1 and the movable mold 2 are in close contact with each other with the runner 3, the gate 4, and the cavity 5 almost in the center as boundaries, and after injection molding, the movable mold 2 is moved to the right in the drawing. Therefore, the second
The molded product is released from the fixed mold 1 as shown in the figure. Thereafter, the resin hardened in the spool 3, runner 4, gate 5, and cavity 6 is ejected from the back side by ejection pins 7a, Tb, and 7c arranged in the movable mold 2, and the spool 3, etc. The molded product 8 is released from the mold together with the cured resin. Here, the inner diameters of the spool 3, runner 4, gate 5, etc. are appropriately determined depending on the type of synthetic resin material, that is, the degree of fluidity in a softened state, and a relatively highly fluid synthetic resin material such as polyethylene is used. In this case, the inner diameter should be made smaller, and in the case of using a highly fluid synthetic resin such as hard vinyl chloride resin, the inner diameter should be made larger to avoid molding defects (particularly insufficient filling of the resin into the cavity 6). is common. The molded article 8 thus formed is made into a product by cutting and removing the hardened resin at the gate 5 portion in the next step. By the way, the technology for automatically and continuously carrying out the injection molding process and the mold release process has already been established, and the production speed has been considerably increased. However, as mentioned above, no established technology has been proposed yet for the process of cutting and removing the gate resin from the molded product 8, which is one of the bottlenecks in this type of injection molding process. That is, in the past, as explained in Fig. 2, the molded product 8 released from the mold after injection molding was accompanied by resin that had hardened at the gate 5, runner 4, etc., so the resin at the gate 5 was then removed. It is removed by plucking or cutting using an appropriate blade, but this process has not yet been automated and currently relies on manual labor. In particular, when plucking is used, the plucking surface becomes rough, detracting from the aesthetic appearance of the molded product, and contributing to lower commercial value. Moreover, when using a synthetic resin with low fluidity during injection, such as hard vinyl chloride resin, the inner diameter of the gate 5 must be increased.
Simply tearing it off becomes difficult and an appropriate cutting blade must be used, but in any case, the molded product 8 after injection molding.
It is necessary to pick up the gates one by one and cut and remove the gate 5 resin, and this work is extremely frequent, and there is a strong need for the development of improved technology from the viewpoint of labor productivity. The present invention has been made with attention to the above-mentioned circumstances, and its purpose is to provide an injection molding method in which the cured resin and the molded product can be separated at the gate part etc. at the same time as the injection molded product is released from the mold. In order to provide molds, we can automate the entire process from injection molding to mold release and cutting and removing the molded product and gate resin, making it possible to perform injection molding work with high productivity. We aim to provide various types of molds.

The configuration of the mold of the present invention that achieves this purpose is that the tip of the gate in the injection mold is formed into a blade shape whose diameter decreases as it approaches the open end, and the injection molded product is made to intersect with the axis of the gate. The gist is that the injection molded product can be cut from the gate portion and released from the mold by protruding in the direction. As described above, the tip of the gate in the injection mold of the present invention is formed into a blade shape whose diameter decreases as it approaches the opening (ie, the cavity entrance).

When releasing the injection molded product, the injection molded product is released by protruding in the direction crossing the axis of the gate, as shown in Figure 2. At this time, the tip of the gate is formed in the shape of a blade whose diameter decreases toward the opening end (hereinafter sometimes referred to as the reduced-diameter blade), so when the molded product is ejected, the notch effect of the blade reduces the resin in the gate area. portion will be cut off. In this way, the resin at the gate part can be cut and removed at the same time as the molded product is released, and the injection molding, mold release, and cutting and removal of the gate resin can all be carried out continuously and automatically. Become,
This makes it possible to carry out the injection molding process extremely efficiently. The configuration and effects of the present invention will be explained below in detail with reference to drawings serving as embodiments. However, the drawings merely illustrate the most typical ones, and the design may be carried out as appropriate in keeping with the spirit of the above and later explanations. It goes without saying that modifications and implementations are possible, and any of these are included within the technical scope of the present invention.

3 to 6 illustrate an injection molding die and its operating mechanism according to the present invention, and the structure thereof can be understood in substantially the same manner as in FIGS. 1 and 2. However, in the mold of the present invention, a cavity plate 9 is arranged between the fixed mold 1 and the movable mold 2, and the cavity plate 9 moves left and right in the drawing independently of the movable mold 2. Configure it as possible. The tip of the gate 5, which is constructed by the cavity plate 9 and the movable mold 2, is shown in Fig. 5, which is an enlarged view of the chain line portion in Fig. 4.
As shown in the figure, a blade-shaped portion 10 is formed at the tip, the diameter of which decreases towards the end. When releasing the molded product 8 from the mold, first the movable mold 2 is moved to the right in the drawing together with the cavity plate q and released from the fixed mold 1. Next, when the molded product ejection pin 7c is pushed out in the direction A, the molded product 8 is released from the cavity plate 9 and the movable mold 2 and falls downward, as shown by the chain line in FIG. The resin inside the gate 5 remains supported by the cavity plate 9, and there is a diameter-reducing edge portion 1 at the open end of the gate 5 (i.e., the boundary between the gate 5 and the cavity 16).
0 is provided, this boundary part is the diameter-reduced blade part 10
It is separated from the molded article 8 by the notch effect at. The resin portion 3' hardened at the sprue 8 portion is released from the movable mold 2 by the ejector pin 7a at the same time as the molded product 8 is released from the mold, or at an appropriate time before or after the release. Next, when the cavity plate 9 is separated from the movable mold 2 and the runner and gate resin portions 41 and 5' are released from the movable mold 2 by the ejector pins 7b, the entire process of mold release is completed. After the mold release is completed, the above-mentioned steps are carried out in reverse, and after the mold is assembled to its original state, the next injection operation is carried out, and injection molding and molded product ejection can be carried out in alternating succession. be. Although the illustrated example shows and explains the molding and mold release process for one molded product 8, it is of course also possible to provide a plurality of such manufacturing processes in the mold to create a so-called multi-cavity mold. However, in reality, it is more common to adopt such a multi-capture mechanism.
The injection molding mold of the present invention is constructed as described above, for example, but its most distinctive feature is that the tip of the gate 5 is provided with a blade-like portion 10 whose diameter decreases toward the opening. When the molded product 8 is released from the mold by protruding in the direction crossing the gate 5, the gate resin portion 5' and the molded product 8 can be cut by the notch effect of the blade portion 10. It is in. Therefore, the overall structure of the mold, the operating mechanism, the shape and position of the sprue 3, runner 4, gate 5, etc. are not limited to those shown in the figures, as long as these features can be effectively exhibited. In particular, the shape of the cavity 16 should be determined appropriately depending on the shape and structure of the injection molded product, and it goes without saying that the illustrated example only shows one example. However, as mentioned above or as will be described later, it is also possible to modify and implement it for insert molding, and all of these are included within the technical scope of the present invention. The shape of the gate 5 characterized in the present invention is most commonly a circular flow path in order to make the flow of the injected resin most efficient, and a diameter-reducing blade portion 10 is formed at the opening at the tip. However, the object of the present invention can be effectively achieved even with other polygonal channels such as four-sided or hexagonal channels, or an elliptical channel whose tip opening is formed into a blade shape. That is, in the mold of the present invention, the tip opening of the gate 5 is formed into an inward blade shape, and the molded product and the gate resin are cut by the notch effect produced by the blade portion 10 during the molded product ejection process. The gist lies in that it is possible to do so, and the other configurations can be freely selected and implemented by the person who designs or uses the mold of the present invention. Figures 7 to 10 show examples in which the technology of the present invention is applied to insert injection molds.
A metal material 11 for insert is placed in a predetermined position of the cavity 16.
It is sufficient to understand the same as the example shown in FIGS. 3 to 6 except that the gate 5 is arranged in advance, and a diameter-reducing blade portion 10 as shown in FIG. 5 is formed at the opening at the tip end of the gate 5.

Therefore, when molding the insert molded product 12 using such a mold, the insert molded product 12 is preliminarily placed at a predetermined position in the cavity 16, which is surrounded by the fixed mold 1, the movable mold 2, and the cavity plate 9. The molded metal material 11 is placed, and then injection molding of synthetic resin is performed. Then, the synthetic resin is filled to fill the remaining space in the cavity 16, and as shown in FIG. 7, an insert molded product 12 in which the synthetic resin material and the metal material 11 are integrally bonded is formed. become. After that, do the same as explained in Figures 3 to 6,
First, the movable mold 2 and the cavity plate 9 are moved to release the molded product 12 and the sprue resin 3' from the fixed mold 1 (Fig. 8), and the molded product 12 is removed using the ejector pin 7c. When the mold is released, the molded product 12 and the gate resin portion 5' are cut to obtain a final product (FIG. 9). Simultaneously with the release of the molded product 12, the ejector pin 7a also operates to release the sprue resin portion 3' from the mold, but the sprue resin portion 3' obtained here is the runner resin that will be released from the mold in the next step. l and gate resin portion 5'
It is also collected together with the raw material resin and reused. The resin left on the runner 4 and gate 5 can be removed by releasing the cavity plate 9 and ejecting the pin 7b as shown in FIG.
It is released from the mold by. The insert molded product obtained in this way has a metal male screw part and a flange part on one connection side, and a synthetic resin socket part on the other connection side. It is extremely useful as a pipe joint for connecting resin pipes. As described above, the present invention can be advantageously applied not only to obtaining an injection molded product made of a synthetic resin material alone, but also to obtaining an insert injection molded product in which a synthetic resin material is combined with another member such as a metal material. . Also, as a matter of course, the metal material 11 disposed within the cavity 16
It is of course possible to obtain various insert molded products other than those illustrated by changing the shape and structure of the above, and it is extremely important that such changes do not depart from the technical scope of the present invention. Of course. Even in such an insert injection mold, if the blade part 10 is formed at the tip opening of the gate 5, the gate resin part 5' can be automatically cut and removed at the same time as the molded product 12 is ejected and released. can do. In this way, the work of stripping or cutting off the gate resin after releasing the injection molded product can be completely saved, and it is possible to provide a technology with extremely high practical value in establishing full automation of the injection molding process. It has become a matter of fact. Moreover, since the blade-shaped portion 10 provided at the opening at the tip end of the gate is formed parallel to the outer surface of the molded product and parallel to the direction in which the molded product is ejected, the cut surface cut by the notch effect is It exhibits almost the same aesthetic appearance as the surface, and can also improve the commercial value of injection molded products.
In this way, injection molding and insert injection using hard synthetic resins such as hard vinyl chloride resins, which have low fluidity when softened and require a large gate inside diameter, as well as soft synthetic resins that require a relatively small gate inside diameter. The utility value of the technology of the present invention in the field of molding is extremely high.

[Brief explanation of the drawing]

The drawings are for explaining the present invention, and FIGS. 1 and 2 are longitudinal cross-sectional views of essential parts illustrating a known injection mold and molding/mold release processes. Figures 3 to 6 show the injection mold and its molding process according to the present invention.
Figures 3, 4, and 6 are longitudinal sectional views of main parts, Figure 5 is an enlarged sectional view illustrating the structure of the gate tip opening in this mold, and Figures 7 to 10 are illustrations of the mold release process. FIG. 7 is a vertical cross-sectional view of a main part of another embodiment of the present invention when applied to an insert injection mold. 1...Fixed mold, 2...Movable mold, 3...Sprue,
4...Runner, 5...Gate, 6...
...Cavity 1, 7a, 7b, 7c...
Ejector pin, 8... Injection molded product, 9...
...Cavity plate, 10...Blade-shaped part,
11...Metal material, 12...Insert molded product.

Claims (1)

[Claims] 1. Cut the injection molded product from the gate by forming the tip of the gate in the injection mold into a blade shape that reduces in diameter as it approaches the opening end, and protruding the injection molded product in a direction that intersects with the axis of the gate. A mold for injection molding, characterized in that the mold is configured such that it can be released from the mold.