JPS6224495Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a mold structure for injection molding a synthetic resin molded product having holes such as insertion holes.

For molded products such as wheel covers and hub caps of vehicles such as automobiles, where marks such as ornaments and medals are attached to the center part, inserts are used to accept protruding objects such as positioning bosses and protrusions provided on the ornaments, medals, etc. A hole is provided. FIG. 1 is a perspective view showing a synthetic resin molded product for a hub cap of an automobile, where 1 is the molded product, 2 is an insertion hole provided on its upper surface, and 3 is a sprue. The insertion hole 2 is a through hole so as to be able to receive a protrusion (not shown) provided on the ornament.

FIG. 2 is a vertical cross-sectional view showing a conventional injection mold for molding the molded product 1 as described above. Core mold 5 having mold engraving on the back side of molded product 1, which is provided so as to face each other.
It consists of The cavity mold 4 has a nozzle hole 6 for receiving an injection nozzle (not shown) and a sprue 7 communicating with the nozzle hole 6, and the sprue 7 communicates with a cavity space 8 formed by the cavity mold 4 and the core mold 5. are doing. On the other hand, the core mold 5 is provided with a pin 9 for forming the insertion hole 2 for the molded product 1 so as to protrude from the mold engraving surface and come into contact with the cavity mold 4.

After the mold configured as described above is clamped as shown in FIG. 2, the injection nozzle is brought into contact with the nozzle hole 6, and the molten resin is injected into the cavity space 8 through the sprue 7 to form the molded product 1. Shape. The molded product 1 thus molded has an insertion hole 2 extending through it, as shown in FIG.

However, in such conventional injection molds, the pin 9 is driven into the mold, formed by direct processing, or uses a nesting pin, so the mold clamping pressure or injection pressure causes Within a few thousand shots, the shape of the tip of the pin 9 appears to be deformed, causing burrs, which impede the efficiency of the work of assembling other parts, and impair the aesthetic appearance.

Figure 3 is a vertical sectional view showing a conventional injection mold that can improve these problems, Figure 4 is a diagram showing the state before adjustment, and Figure 5 is a diagram showing the respective states after adjustment. FIG. 3 is a partially enlarged view, and FIG. 6 is a vertical sectional view of an improved version thereof. This injection mold is constructed almost the same as that in FIG. 2, but the pin 9 is screwed into the mold body. That is,
The pin 9 has a rod 9a on the side where the insertion hole 2 is formed, a screw 9b on the opposite end, and a core type 5.
A slide hole 10a into which the rod 9a slides is formed on the mold engraving surface side, and a screw hole 10b communicating with the slide hole 10a and into which the threaded portion 9b is screwed is formed on the outer surface side.
is inserted into the slide hole 10a, the threaded part 9
b is screwed into the screw hole 10b. The screw portion 9b has a screwdriver insertion hole 9c, and can be screwed in from the outside.

In the injection mold configured as described above, a driver is inserted into the driver insertion hole 9c, the pin 9 is rotated about its axis, and the threaded portion 9b is propelled to adjust the protruding height of the rod 9a. do. In this way, injection molding is carried out in the same manner as in FIG. 2, with the pin 9 adjusted to a height such that it contacts the cavity mold 4 during mold clamping.

As the molding is repeated, as shown in Figure 4,
The tip of the pin 9 wears out and burrs 11 are generated. When this state is reached, the pin 9 is pulled out, its tip is polished to make it perfectly flat, and the pin 9 is screwed into the core mold 5 again, and the screwing height is adjusted as shown in FIG. Such finishing and adjustment of the pin 9 is possible until the threaded portion 9b drives the screw hole 10b to the fullest extent, and the pin 9 does not need to be replaced during this time.

In FIG. 6, the spring 12 is inserted into the screw hole 10b so that a pressing force is applied to the screw portion 9b, so there is no play in the pin 9, and therefore the tip of the pin 9 is always kept in the cavity. Type 4
can prevent burrs from forming.

However, in such an injection mold, when the tip of the pin 9 wears out as shown in Fig. 4, burrs 11 are generated on the surface of the molded product 1, and each time this happens, the pin 9 is removed and polished. Therefore, the pin 9 must be constantly polished, and the carved surface of the cavity die 4 to which the pin 9 is crimped is likely to be damaged, and in this case, it is difficult to repair it. There were problems such as:

This idea was created by focusing on these conventional problems, and by screwing the pin into the cavity mold and core mold so that it can move in the axial direction, the above problems were solved and the surface of the molded product was improved. To provide an injection mold that can prevent the occurrence of burrs in the mold, reduce the frequency of pin corrections, facilitate pin corrections, and maintain the tip end of the pin in a perfect condition. The purpose is

This invention is a mold for injection molding a synthetic resin molded product having a hole, in which a pin for forming the hole is screwed to the cavity mold and the core mold so as to be movable in the axial direction, and The injection mold is characterized in that the tips of the pins face each other so as to come into contact with each other within the cavity space.

This invention will be explained below based on the drawings.

FIG. 7 is a vertical sectional view of a portion of an embodiment of the invention, and the same reference numerals as in FIGS. 1 to 6 indicate the same or corresponding parts. This injection mold is constructed almost the same as the one shown in FIGS. 3 to 5, but in addition to the pin 9, a pin 13 is provided in the cavity mold 4, and the rod 13a is inserted into the slide hole 14a. is inserted into the driver insertion hole 13c.
A threaded portion 13b having a diameter is screwed into the threaded hole 14b, and each pin 9, 13 is
a, 13a are provided facing each other so that their tips completely abut in the cavity space 8. The other configurations are the same as those shown in FIGS. 3 to 5.

In the injection mold configured as described above, the screwdriver is inserted into the driver insertion hole 9c, 13c, the pin 9, 13 is rotated about its axis, the threaded part 9b, 13b is propelled, and the rod is inserted. 9
a, the tips of 13a are brought into contact with each other, and
Injection molding is performed in the same way as in the figure.

In this case, the tips of pins 9 and 13 are shaped like cavity 4.
And since the position can be adjusted away from the die engraving surface of the core mold 5, there is no risk of burrs forming on the front or back surface of the molded product 1. Further, even if the tips of the pins 9 and 13 become worn and burrs are generated, there is no need to immediately polish them, and the burrs can be left as they are until the burrs reach the extent that they interfere with the attachment of the molded product 1.
Furthermore, since the pressing surfaces are the tip surfaces of the pins 9 and 13, damage to the carved surface of the cavity die 4 as in the prior art is prevented.

In the above embodiment, it is also possible to press the pins 9, 13 by inserting springs 12 as shown in FIG. 6 into the screw holes 10b, 14b. Further, the shapes of the pins 9 and 13 can be made into a necessary shape according to the shape of the insertion hole 2, and the screwing positions can also be changed as appropriate.

The above explanation has been given to molded products as automobile parts, but it can also be applied to injection molding molds for molded products for other purposes. The shape of the die engraving surface and pin can be selected.

As explained above, according to this idea,
Since the hole-forming pin is screwed to the cavity mold and core mold so that it can move in the axial direction, burrs will not form on the front or back surface of the molded product even if the tip of the pin is worn or damaged. Furthermore, even if burrs start to appear, there is no need to correct them immediately, and if corrections are needed, they can be easily corrected without damaging the engraved surface of the mold. Furthermore, even if the pin is damaged and becomes unusable, it is only necessary to replace the pin, and there is no need to process the mold, making mold processing easy. In addition, since the length from the cavity mold surface and core mold surface to the tip of the pin can be made shorter than the thickness of the cavity space, the bending moment generated at the base of the pin due to the pressure of the resin flowing in the cavity space can be reduced.
Therefore, even when a pin with a relatively small diameter is used, it is possible to prevent the pin from bending or twisting. In addition, if a spring is provided to press the pin, it will prevent the pin from wobbling and will have the effect of ensuring that the tips are in complete contact with each other.
If they are arranged facing each other, there are effects such as preventing burrs from appearing on the front or back surface of the molded product.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing a synthetic resin molded product for automobile hub caps, Figure 2 is a vertical sectional view showing a conventional injection mold, and Figure 3 is another conventional injection mold. Vertical cross-sectional view, Figure 4 is before adjustment,
Fig. 5 is a partial enlarged view of Fig. 3 showing each state after adjustment, Fig. 6 is a vertical sectional view showing an improved version thereof, and Fig. 7 is a partial vertical sectional view showing an embodiment of this invention. It is. In each figure, the same reference numerals indicate the same or equivalent parts, 1 is a molded product, 2 is an insertion hole, 4 is a cavity mold, 5 is a core mold, 9, 13 are pins, 9b, 13b
10b and 14b are screw holes, and 12 is a spring.

Claims (1)

[Claims for Utility Model Registration] (1) In a mold for injection molding a synthetic resin molded product having a hole, a cavity mold and a core mold are used so that a pin for forming the hole can move in its axial direction. An injection mold, characterized in that the pins are screwed into the mold, and the tips of the pins face each other so as to come into contact with each other within the cavity space. (2) The injection mold according to claim 1, wherein a threaded portion is formed at the end of the pin opposite to the hole forming portion, and is screwed to the cavity mold and the core mold. (3) The injection mold according to claim 1 or 2, wherein the pin is adjustable from the outside of the cavity mold and the core mold. (4) Claims 1 to 3 of the utility model registration claim in which the pin is prevented from rattling by a spring.
The injection mold according to any of paragraphs.