JPH07106587B2 - Molding method of thick cap and its cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for molding a thick-walled cap used as a cap for perfume bottles, etc., and a thickness free from wrinkles or sink marks on the outer surface molded by the method. It is about meat caps.

<Prior Art> A technology developed for the purpose of preventing sink marks and deformation from occurring on the surface of a plastic molded product is Japanese Patent Application Laid-Open No. 54-65760 or 49-17838 developed by the applicant of the present patent. Japanese Patent Publication No. 52-133029 and the like are known.

These techniques include, for example, providing a closing pin, a protruding pin, etc. in a part of the cavity as illustrated in FIG. 4, and applying a pressure in the cavity by the closing pin, the protruding pin, etc. at the time of resin molding. This is a technique that prevents sink marks and deformation from occurring on the surface of molded meat products.

<Problems to be Solved by the Invention> However, in the above-mentioned known technique, since pressure is applied to the inside of the cavity at the time of molding the resin by the predetermined pin, it is possible to prevent the sinking or deformation of the surface of the molded product to some extent. However, when the resin is injected onto the surface of the molded product, there are drawbacks such as wrinkles and swirl patterns or patterns such as these corresponding to the rapid flow of the resin appearing on the outer surface, significantly reducing the commercial value of the molded product. It was

The molding method and the cap thereof according to the present invention relate to a completely new technique developed in view of these drawbacks of the related art.

<Means for Solving Problems> According to the present invention, a cavity is formed by a split mold cavity, a base mold, and an ejector pin mounted so as to be extruded into the base mold, and a resin is injected into the cavity space to increase the thickness. In the method of molding a meat cap, a predetermined protrusion is formed at the tip of the protrusion pin, and the resin injected into the cavity space is dispersed and filled into the cavity space while injecting from the gate toward the protrusion. Then
Further, the present invention relates to a method of molding a thick cap, which is characterized in that an injection resin is pressure-molded while the ejection pin is projected into the cavity space, and a cap molded by the molding method.

<Operation> In the present invention, as described above, a predetermined protrusion is provided at the tip of the protrusion pin that forms the cavity space, and the injection resin injected from the gate is abutted against the protrusion and then the cavity space is formed. The resin is dispersed and filled inside, and the resin is pressed and molded while projecting the ejector pins during molding, so the resin injected and injected into the cavity space is swirled while entraining air. It is possible to prevent the occurrence of so-called jetting phenomenon, which means that the outer surface of the molded product is free from sink marks and deformation, and it is also possible to prevent the appearance of other wrinkles, swirl patterns or patterns. Can be done.

<Embodiment> An embodiment of the molding method according to the present invention will be described in detail with reference to the drawings. In FIGS. 1 to 3, reference numerals 1 and 2 denote split mold cavities arranged on the left and right, respectively. A base die 3 is disposed below the base die 3, and a protrusion pin 4 is slidably mounted on the base die 3. Reference numeral 5 denotes an eggplant-shaped cavity space for molding a molded product formed by the split mold cavities 1 and 2, the base mold 3 and the ejection pin 4. Triangular pyramidal protrusion 4a is formed at the center of the tip of the protruding pin 4.
Is projected. Reference numeral 6 denotes a tunnel gate for injecting resin into the cavity space 5. The tunnel gate 6 is provided at a position shown in FIG. 1 at a lateral position corresponding to the protrusion 4a of the protrusion pin 4. It is configured so that the injected resin can flow into the cavity space 5 while abutting against the protrusion 4a and dispersing. Reference numeral 7 is a runner communicating with the tunnel gate 6, 8 is an eggplant-shaped thick cap made of resin molded in the cavity space 5, and the lower bottom surface thereof corresponds to the triangular pyramidal protrusion 4a. The concave portion 8a is provided so as to project, and the packing 9 is provided on the outer peripheral surface of the lower portion.
A ring groove 8b for fitting the upper edge 9a is formed.

Next, the molding method of the present invention will be described in the order of steps. In the present invention, the split mold cavities 1 and 2 and the base mold 3 are closed to form a cavity space 5 and the protrusion pin 4 is firstly formed.
At the position shown in the figure, the resin is ejected from the tunnel gate 6 toward the protrusion 4a of the pin 4, and the injected resin is dispersed while abutting against the protrusion 4a so as to flow into and fill the cavity space 5. Then, as shown in FIG.
While gradually ejecting the ejection pin 4 toward the cavity space 5, pressure is applied to the cavity space 5 to gradually cool and solidify the molded product in the cavity space 5, and to reduce the shrinkage reduction amount due to the volume contraction caused by the temperature drop. By replenishing, the outer surface of the molded product can be kept in close contact with the inner peripheral surface of the cavity space 5 at all times to prevent wrinkles, sink marks, deformation and the like from occurring on the surface of the molded product.

Therefore, when the molding method of the present invention is carried out, as described above, it is possible to mass-produce high-precision and high-quality molded products having no sink marks or deformation and no wrinkles, spiral patterns or patterns in a short cycle. .

The thick cap 8 which is a molded product molded in this way has a third
As shown in the figure, a separately prepared packing 9 is fitted into the ring groove 8b at the lower portion of the upper edge 9a so that the lower portion of the cap 8 can be covered with the packing 9 to form the whole. In addition, it can be used by inserting the lower packing 9 into the bottle mouth 10 of a perfume bottle or the like.

Since the thick-walled cap according to the present invention is manufactured by the method as described above, there is no sink mark, deformation, wrinkle, spiral pattern or pattern on the outer surface, and a cap having an extremely smooth and beautiful outer surface is obtained. Can be configured.

<Effect of the Invention> Since the molding method according to the present invention and the thick cap molded by the molding method have the above-described configuration and action, the resin injected and injected into the cavity space flows in a spiral shape while entraining air. It is possible to prevent the resin from being injected into the cavity space by the action of the protruding portion of the ejector pin while smoothly dispersing and injecting the resin into the cavity space. It has the feature that it is possible to fundamentally prevent the appearance of wrinkles, swirl patterns or patterns of these on the surface of the molded product.

[Brief description of drawings]

1 and 2 are cross-sectional explanatory views illustrating the molding method according to the present invention, FIG. 3 is an explanatory view showing a molded product, and FIG. 4 is an explanatory view showing a conventional example. 1, 2 are cavities, 3 are base molds, 4 are protruding pins, 4
a is a protrusion, 5 is a cavity space, 6 is a gate, and 9 is a packing.

Claims (2)

[Claims] 1. A method of forming a cavity space by a split mold cavity, a base mold, and an ejecting pin mounted in the base mold so as to be extrudable, and injecting a resin into the cavity space to mold a thick wall cap. In addition, a predetermined protrusion is provided at the tip of the protrusion pin, and the resin injected into the cavity space is dispersed and filled in the cavity space while injecting the resin toward the protrusion from the gate. A molding method for a thick cap, characterized in that the injection resin is pressure-molded while projecting into the space. 2. A thick-walled cap having a recessed portion corresponding to the protrusion of a protruding pin on the lower bottom surface thereof, and innumerable wrinkles, sink marks, deformations and the like due to injection molding do not appear on the outer surface.