JP2004025602A - Method of manufacturing undercut molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an undercut molded product by which the undercut molded product can be manufactured using a material which is friendly to environments. <P>SOLUTION: The mold used for this method is constituted of a parallel core 5, formed in the approximately analogous shape to a cavity 4, which is arranged inside the cavity 4 formed by clamping a cavity side half 2 and a movable half, a core main body 11 and a movable core 12 which is housed in a fitting recessed part 13 of an approximately inverted truncated cone shape formed in the core main body 11. The movable core 12 is afloat from the fitting recessed part 13 by blowing air from an opening formed at the bottom of the recessed part 13 and the air flowing out of a gap between the inner wall face of the recessed part 13 and the outer wall face of the movable core 12, flows to the inside of a molded product A formed on the peripheral face of the parallel core 5. Consequently, the molded product A is expanded to facilitate the release of the molded product A from the parallel core 5. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an undercut molded product.
[0002]
[Prior art]
Conventionally, when molding the body, head, arms, legs, etc. of a hollow doll, resin is injected into the cavity of a rotation mold or slash mold, and in the case of a rotation mold, the entire mold is rotated. After uniformly forming a resin layer on the inner peripheral surface of the cavity and curing the resin in that state, the molded article is taken out of the rotation mold. In the case of a slush mold, a resin is injected into a heated mold, excess resin that does not adhere to the inside of the mold is poured out, and the adhered resin is reheated and cured to be removed from the slash mold.
[0003]
[Problems to be solved by the invention]
However, PVC (vinyl chloride) is generally used as the resin used in the above-mentioned molding method. However, it has been pointed out by environmental protection groups that this PVC may have a bad effect on the human body. Since it was also used for a doll used as a play object, the emergence of a molded article using an alternative resin was desired.
[0004]
An object of the present invention is to provide a method of manufacturing an undercut molded product which can solve the above-mentioned problems and enables the production of an undercut molded product using an environment-friendly material.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a method for producing an undercut molded product according to the present invention is characterized by having the following requirements.
(B) The placing core is placed in a cavity formed when the fixed mold and the movable mold are arranged so as to be relatively separated from each other. Is substantially similar to the cavity, and a fixed distance is set between the molding surface of the fixed mold and the movable mold and the molding surface of the placing core while being arranged in the cavity. And the resin injected into the cavity is made to have a certain thickness. (C) The placing core is accommodated in a core body and a substantially inverted truncated conical recess formed in the core body. The bottom of the concave portion has an opening at one end of a through-hole penetrating outside the core body, and air is blown into the concave portion through the through-hole to move the movable core into the concave portion. From the inner wall of the recess and the outer wall of the movable core Is flown from the gap to the inside of the molded article, to facilitate release of the molded product from the core placed inflate the molded article [0006]
In addition, if the resin is a thermoplastic styrene-based elastomer and is suitable for injection molding, it is preferable that an undercut molded product can be molded and an environmentally friendly molded product can be produced.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an example of an injection molding die applied to a method of manufacturing an undercut molded product according to the present invention. The injection molding die 1 will be described in the case where the molded product is a doll head. The movable mold 3 is disposed so as to be separable from the fixed mold 2, and is disposed in a cavity 4 formed when the fixed mold 2 and the movable mold 3 are clamped. The fixed core 5 has a fixed distance between the molding surfaces of the fixed mold 2 and the movable mold and the molding surface of the fixed core 5. As described above, the cavity 4 is formed similar to the cavity 4 and slightly smaller, and is formed by the molding surfaces 2a and 3a of the fixed mold 2 and the movable mold 3 and the molding surface 5a of the placing core 5. When a resin is injected, a molded product having a substantially constant thickness is formed.
[0008]
Then, after the resin is cured, the mold is opened, the movable mold 3 is separated from the fixed mold 2, and the placing core 5 with the molded product A covered from the movable mold 3 is removed. The molded product A can be extracted from the core 5.
[0009]
The placing core 5 is composed of a core body 11 and a movable core 12 supported by a support base 10, and has the shape of a doll's head as a whole (see FIG. 3A). The movable core 12 is formed in an inverted truncated conical shape having the same shape as the inverted truncated conical fitting recess 13 formed in the core main body 11 (see FIG. 3B), and formed in the core main body 11. The side surface 12a of the movable core 12 is tightly attached to the inner peripheral surface 13a of the fitting recess 13 at the time of fitting. 12b is formed to be flush with the upper surface 11b of the core body 11 (see FIG. 3C).
[0010]
One end of a through hole 14 penetrating from the bottom surface to the outside of the core body 11 is opened at the bottom surface 13b of the fitting recess 13 of the core body 11, and a nozzle 15 is attached to the other end of the through hole 14. The air blown from the nozzle 15 is blown into the fitting recess 13 from the opening 16 through the through hole 14. In the through hole 14, the diameter of the portion of the support base 10 is slightly increased, and a step 17 is formed.
[0011]
By the way, the shaft body 20 is attached to the movable core 12. The shaft body 20 has a screw portion 21 at the front end and a bulging flange portion 22 at the rear end, and is inserted into the through-hole 14 from the opening 18 on the support base 10 side to be inserted into the through-hole 14. Is screwed into the screw hole 23 of the movable core 12 so that the shaft body 20 is fixed to the movable core 12 so that the shaft body 20 can slide left and right in the through hole 14 in FIG. Has become. The length from the bottom of the movable core 12 to the flange 22 is set so that the sliding amount of the shaft body 20 is about 1 mm. That is, when the movable core 12 is fitted into the fitting recess 13 of the core body 11, the shaft body 20 is set so that the distance between the flange 22 and the step 17 of the through hole 14 is about 1 mm. Is formed, and the upper surface 12b of the lower moving core 12 protrudes from the upper surface 11b of the core body 11 by about 1 mm when the flange portion 22 slides rightward until it contacts the step portion 17. I have.
[0012]
As shown in FIG. 4A, when air is blown from the nozzle 15, the shaft body 20 is pushed forward (to the right in FIG. 4B), and the upper surface 12b of the movable core 12 is Air that protrudes from the upper surface 11b of the main body 11 and forms a gap between the inner peripheral surface 13a of the fitting concave portion 13 and the outer peripheral surface 12a of the movable core 12 is fitted by the air passing through the clearance between the through hole 14 and the shaft body 20. It is arranged to pass through a gap between the recess 13 and the movable core 12 and to squirt out of the core 5.
[0013]
When air is blown from the nozzle 15, the movable core 12 is pushed out, but the swelling portion 22 of the shaft 20 abuts the step 17 of the through hole 14, and the sliding amount of the shaft 20 is limited. The amount of protrusion of the upper surface of the movable core 12 from the upper surface of the core body 11 is limited to about 1 mm.
[0014]
Next, a molding method for molding a molded product using the injection mold having the above-described configuration will be described.
[0015]
When the core 5 is placed on the movable mold 3 and the mold is clamped, the support base 10 of the core 5 is clamped between the fixed mold 2 and the movable mold 3, and the fixed mold 2 is fixed. The core 5 is set in the cavity 4 formed by the metal mold 3 and the movable mold 3 (see FIG. 1). In this state, a space having a substantially uniform thickness is formed between the molding surfaces 2a and 3a of the fixed mold 2 and the movable mold 3 and the molding surface 5a of the placing core 5, and this space is used for the doll. The thickness of the head (molded product) is formed.
[0016]
A thermoplastic styrene-based elastomer (SBS or SEBS is used in the present invention) as a molding material is accommodated in the cavity 4 in a hopper (not shown) in a pellet state, and a screw disposed below the hopper is rotated to rotate the hopper. The pellets inside are sent to a mold and the periphery of the screw is heated by a heater to dissolve the pellets. A molten molding material (for example, SBS) is injected into the cavity 4 from the runner 24 under pressure. The inside is filled with dissolved SBS.
[0017]
When the SBS is cured, the mold is opened, and the movable mold 3 is retracted from the fixed mold 2 (see FIG. 4A). When the mold is opened, the placing core 5 is fixed to the movable mold 3, so that the push-up pin 25 is operated to bring the placing core 5 up from the movable mold 3 (FIG. 4 (b)). )), And remove the placing core 5 from the movable mold 3 by hand.
[0018]
As shown in FIG. 5 (a), the detached core 5 is covered with a molded product serving as the head of the doll, so that an air gun is brought into contact with the nozzle 15 and air is blown from the nozzle 15. The shaft 20 is pushed by the air pressure, but the movable core 12 is pushed out together with the shaft 20 until the flange 22 of the shaft 20 comes into contact with the step 17 of the through hole 14 (see FIG. 5B). .
[0019]
When the movable core 12 is pushed out, the fitting recess 13 is formed in an inverted truncated cone shape, so that a gap is formed between the inner peripheral surface 13 a of the fitting recess 13 and the side peripheral surface 12 a of the movable core 12. Then, air is ejected from the gap to the outside of the core 5. Since the peripheral surface of the placing core 5 is covered with the molded product A, air is blown between the inner peripheral surface of the molded product A and the outer peripheral surface of the placing core 5, and The molded product A expands due to the air, and the air flows out from the opening of the molded product A, so that the molded product A can be easily placed and pulled out from the core 5, and the mold release from the placed core 5 Can be easily performed.
[0020]
As described above, the molded article A can be easily removed from the placed core 5 by placing the molded article A on the peripheral surface of the core 5 and blowing air into the molded article A. Even if the resin is not suitable for conventional rotation molding or slush molding, a hollow molded article can be molded.
[0021]
In addition, although it is an environmentally friendly material, SBS and SEBS are in the form of pellets and are solid at room temperature, so they cannot be poured into a rotation mold. SBS that does not solidify on average, cannot be stored for a long period of time due to deterioration or discoloration due to deterioration or discoloration of the heater, and is not suitable for rotation molding due to poor moldability, but undercut with SBS or SEBS In the case of manufacturing a molded product of the above, it is possible to obtain a molded product of SBS, which is an environmentally friendly material, by an injection molding method using the above-mentioned injection molding die 1, thereby providing a safer molded product to consumers. be able to.
[0022]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, even if it is resin which is not suitable for rotation molding or slush molding, a hollow molded article can be shape | molded. This makes it possible to perform injection molding for a resin that is an environmentally friendly material but is not suitable for rotation molding or slush molding.
[0023]
Further, since SBS can be used as the resin, the molded resin product can produce an environmentally friendly molded product.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing an example of an injection molding die applied to a method of manufacturing an undercut molded product according to the present invention. FIG. 2 is a cross-sectional view of a main part of the injection molding die disassembled. FIGS. 3 (a) to 3 (c) are side views and cross-sectional views of main parts for explaining the configuration of the placing core. FIGS. FIG. 5 (a) and FIG. 5 (b) are explanatory diagrams of a state in which an undercut molded product is released from a placing core.
DESCRIPTION OF SYMBOLS 1 Injection mold 2 Fixed side mold 3 Movable mold 4 Cavity 5 Placing core 11 Core body 12 Moving core A Molded product

Claims (2)

A method for producing an undercut molded product, comprising the following requirements.
(B) The placing core is placed in a cavity formed when the fixed mold and the movable mold are arranged so as to be relatively separated from each other. Is substantially similar to the cavity, and a fixed distance is set between the molding surface of the fixed mold and the movable mold and the molding surface of the placing core while being arranged in the cavity. And the resin injected into the cavity is made to have a certain thickness. (C) The placing core is accommodated in a core body and a substantially inverted truncated conical recess formed in the core body. The bottom of the concave portion has an opening at one end of a through-hole penetrating outside the core body, and air is blown into the concave portion through the through-hole to move the movable core into the concave portion. From the inner wall of the recess and the outer wall of the movable core Is flown from the gap to the inside of the molded article, to facilitate release of the molded article from the core placed inflate the molded article The method for producing an undercut molded product according to claim 1, wherein the resin is a thermoplastic styrene-based elastomer.

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