JPH06238698A - Hollow molded body molding equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] A gas can be smoothly and surely injected into the unsolidified resin, and the unsolidified resin can be prevented from remaining unnecessarily. Provided is a molding device having a configuration. [Structure] A vertically long cavity 18 is formed between a fixed die 14 and a movable die 16 which compose a die 12, and the cavity 18 is formed on the upper portion of the cavity 18.
A molten resin injection means 24 for injecting and injecting a molten resin from above to below is provided.
4, gas injection means 35 for injecting gas from above to below is provided inside the unsolidified resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow molded body molding apparatus for molding a molded body having a hollow portion by injecting a molten resin into a cavity in a mold and then injecting a gas.

[0002]

2. Description of the Related Art Conventionally, a molding apparatus for obtaining a resin molded body having a hollow portion by injection molding has been known.
In this type of molding equipment, after the molten resin is injected and filled into the cavity of the mold, a gas with a relatively large pressure (nitrogen gas, etc.) is blown into it to fill the gas inside the unsolidified resin and make it hollow. And a hollow molded body is molded by solidifying the resin.
8-41264, etc.).

Therefore, for example, the molding die disclosed in Japanese Patent Laid-Open No. 215516/1990 has a vertically long mold cavity 2 as shown in FIG. 4, and the mold cavity 2 is provided below the mold cavity 2. The inlet 3 communicates with the gate 4, and the resin reservoir 6 communicates with the upper portion of the mold cavity 2 through the discharge port 5. In such a structure, when the molten resin is injected from the inlet 3 into the mold cavity 2 and then gas is injected from the inlet 3, the gas is filled inside the resin to form a hollow portion. It

[0004]

However, in the above-mentioned conventional technique, the inlet portion 3 provided in the lower portion of the mold cavity 2 is used.
Since molten resin and gas are injected from the mold, this gas counteracts the weight of the resin and forces the resin into the mold cavity 2
Try to push out to the resin reservoir 6 provided on the upper part of the. Therefore, the unsolidified resin easily falls due to its own weight, and the unsolidified resin remains in the mold cavity 2. As a result, it has been pointed out that the desired hollow portion cannot be obtained and the residual resin solidifies to cause defects such as shrinkage.

The present invention solves this kind of problem, and allows the gas to be smoothly and surely injected into the unsolidified resin and prevents the unsolidified resin from remaining unnecessarily. It is an object of the present invention to provide a molding device for a hollow molded body that is capable of performing and has a simple structure.

[0006]

In order to achieve the above-mentioned object, the present invention provides a method of injecting a molten resin into a vertically long cavity formed in a mold, and then injecting the molten resin into the interior of the unsolidified resin. A molding apparatus for molding a hollow molded article by injecting gas into the cavity, the molten resin injection means being provided at an upper portion of the cavity and injecting a molten resin from above the cavity downward. Gas injection means for injecting gas into the unsolidified resin from above to below is provided in the vicinity of the molten resin injection means.

Further, according to the present invention, a hollow molded body is molded by injecting a molten resin into a vertically long cavity formed in a mold and then injecting a gas into the unsolidified resin. And a molten resin injection means for injecting and injecting a molten resin from above the cavity to above the cavity, and a molding device provided in the vicinity of the molten resin injection means for unsolidifying. Gas injection means for injecting gas from above into the inside of the resin, and an overflow chamber provided at the lower part of the cavity so as to be openable and closable.

[0008]

In the molding apparatus for a hollow molded body according to the present invention, after the molten resin is injected and injected downward from above the cavity which is long in the vertical direction, the resin is injected into the unsolidified resin from above to below. Gas is injected. Therefore, the unsolidified resin smoothly and reliably moves to the lower side of the cavity via its own weight and gas pressure, and the unsolidified resin does not remain unnecessarily. Therefore, a desired hollow molded body can be molded with high precision.

Further, when an overflow chamber that can be opened and closed is provided below the cavity, the uncoagulated resin is smoothly discharged from the cavity into the overflow chamber by injecting gas. This makes it possible to mold a hollow molded body having a particularly large hollow volume with high accuracy and reliability.

[0010]

EXAMPLES Examples of the molding apparatus for hollow molded articles according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a molding apparatus according to the first embodiment of the present invention. This molding device 10
Includes a mold 12, and a fixed mold 1 that constitutes the mold 12.
The movable mold 16 and the movable mold 16 are arranged such that their mating surfaces are oriented in the vertical direction, and between the fixed mold 14 and the movable mold 16, a vertically long cavity 18 is formed.
The fixed mold 14 is fixed to the mounting base 20, while the movable mold 16 is fixed to the mounting base 22.

A molten resin injection means 24 for injecting and injecting a molten resin from the upper side to the lower side of the cavity 18 is provided above the cavity 18. The molten resin injection means 24 is provided with an injection nozzle 28 that communicates with the hot runner 26.
8 communicates with the upper portion of the cavity 18 via the spool 30, the runner 32, and the weir 34.

Gas injection means 35 for injecting gas downward from above is provided inside the unsolidified resin in the vicinity of the molten resin injection means 24. This gas injection means 35
Comprises a hydraulic cylinder 36 fitted in the movable mold 16,
Inside the hydraulic cylinder 36, the piston 3 can move back and forth freely.
8 is integrally provided with a pin portion 40. The length of the pin portion 40 is selected so as to fit into the hole portion 42 formed in the movable die 16 and the tip end portion thereof can be inserted into the cavity 18. The hydraulic cylinder 36 has
A chamber 44 is formed so as to surround the pin portion 40, and one end of the gas passage 46 communicates with the chamber 44. This gas passage 4
The other end side of 6 extends from the movable die 16 to the outside and communicates with a high pressure gas supply source (not shown).

A hole 50 is formed in the movable die 16 below the gas injection means 35, and the hole 5 is formed.
A push-out pin 52 is movably arranged at 0, and the push-out pin 52 is fixed to a take-out plate 54 which can move forward and backward with respect to the mounting base 22 via an actuator (not shown).

An overflow chamber 5 is provided below the cavity 18.
6 is provided to be openable and closable. An outflow passage 58 is formed between the cavity 18 and the overflow chamber 56,
A pin 62 constituting the opening / closing means 60 is fitted in the outflow passage 58 to shut off the cavity 18 and the overflow chamber 56. The pin 62 is configured to be movable back and forth in the left-right direction via a hydraulic cylinder 64.

The fixed mold 14 and the movable mold 16 are provided with a plurality of cooling holes 66 on the lower end side thereof, and the cooling water flows from a cooling water supply source (not shown) into the cooling holes 66. It

Next, the molding apparatus 10 configured as described above.
The operation of will be described.

First, the fixed mold 14 and the movable mold 16 constituting the mold 12 are clamped, the hole portion 42 is closed by the pin portion 40 constituting the gas injection means 35, and the opening / closing means 60 is constituted. The pin 62 is fitted into the outflow passage 58 to disconnect the cavity 18 from the overflow chamber 56. Therefore, from the injection nozzle 28 that constitutes the molten resin injection means 24, the spool 30, the runner 32, and the weir 34 are provided.
The molten resin is injection-filled into the cavity 18 via (see FIG. 2A). At that time, high-pressure gas is introduced into the chamber 44 from a high-pressure gas supply source (not shown) through the gas passage 46.

The molten resin injected into the cavity 18 is
While flowing from the upper side to the lower side of the cavity 18 and being cooled from the portions contacting the wall surfaces of the fixed die 14 and the movable die 16, a solidified portion 80 is formed on the product surface side, while a molten portion 82 is formed inside. Provided (FIG. 2B)
reference).

Next, the piston 38 moves to the left under the action of the hydraulic cylinder 36, and the tip of the pin portion 40 projects into the cavity 18 by a predetermined amount.
Small holes are formed on the surface of the resin before it solidifies inside. After that, the pin portion 40 moves to the right through the piston 38, and the hole portion 42 communicates with the chamber 44. Therefore, the high-pressure gas is introduced into the resin inside the cavity 18 through the hole 42 (see FIG. 2C).

At this time, the hydraulic cylinder 64 constituting the opening / closing means 60 is driven, and the pin 62 is moved rightward so that the cavity 18 and the overflow chamber 56 communicate with each other. As a result, the molten portion 82 in the cavity 18 is led out from the outflow passage 58 to the overflow chamber 56 side via the pressing force of the high-pressure gas, and the hollow portion 84 is formed in the cavity 18 (see FIG. 2D).

In this case, in the first embodiment, the gas injection means 35 is arranged near the molten resin injection means 24 on the upper side of the cavity 18, and the gas injection means 35 is provided.
From above, gas is injected into the unsolidified resin (melted portion 82) in the cavity 18 from above to below.
Therefore, in the cavity 18 elongated in the vertical direction, the flow direction of the melting portion 82 due to its own weight becomes the same as the flow direction of the melting portion 82 due to the gas pressure, and the melting portion 82 is smoothly moved to the overflow chamber 56 side. It can be introduced reliably. Therefore, the melted portion 82 does not remain unnecessarily in the cavity 18, and the hollow molded body having a large volume of the hollow portion 84 can be molded with high quality.

Next, a molding apparatus 10a according to a second embodiment of the present invention will be described below with reference to FIG. The same components as those of the molding apparatus 10 according to the first embodiment are designated by the same reference numerals, and the detailed description thereof will be omitted.

The molding apparatus 10a according to the second embodiment.
Is particularly preferably used when molding a hollow molded body having a relatively small volume in the hollow portion, and has no overflow chamber. Other configurations are the molding apparatus 10
A molten resin injecting means 24a for injecting and injecting molten resin from above the cavity 18a downward is provided on the upper portion of the cavity 18a which is long in the vertical direction. Gas injection means 35a for injecting gas from the upper side to the lower side inside the unsolidified resin is provided in the vicinity.

Therefore, the molding apparatus 10 according to the second embodiment.
In a, as in the molding apparatus 10, the unsolidified resin in the cavity 18a moves smoothly and reliably to the lower side of the cavity 18a via its own weight and gas pressure, and the unsolidified resin remains unnecessarily. There is nothing to do. Therefore, an effect that a desired hollow molded body can be molded with high precision can be obtained.

[0026]

EFFECTS OF THE INVENTION According to the molding apparatus for hollow molded articles of the present invention, the following effects and advantages are obtained.

After the molten resin is injected and injected into the cavity which is long in the vertical direction, the gas is injected into the unsolidified resin from the upper side to the lower side. It smoothly and reliably moves to the lower side of the cavity via the gas pressure, and the unsolidified resin does not remain unnecessarily. Therefore, a desired hollow molded body can be molded with high precision.

Furthermore, when an openable and closable overflow chamber is provided below the cavity, the uncoagulated resin is smoothly discharged from the cavity into the overflow chamber by injecting gas. This makes it possible to mold a hollow molded body having a particularly large hollow volume with high accuracy and reliability.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional explanatory view of a molding apparatus according to a first embodiment of the present invention.

2A and 2B are explanatory views when a hollow molded body is molded by the molding apparatus according to the first embodiment, FIG. 2A is a state in which molten resin is filled in the cavity, and FIG. 2B is a solidified portion in the cavity. FIG. 2C is an explanatory view of a state in which a molten portion is formed, FIG. 2C is a state in which a high-pressure gas is supplied inside the resin, and FIG. 2D is an explanatory view of a state in which a hollow portion is formed.

FIG. 3 is a schematic vertical cross-sectional explanatory view of a molding apparatus according to a second embodiment of the present invention.

FIG. 4 is a schematic vertical cross-sectional explanatory view of a molding apparatus according to a conventional technique.

[Explanation of symbols]

 10, 10a ... Molding device 12, 12a ... Mold 14, 14a ... Fixed mold 16, 16a ... Movable mold 18, 18a ... Cavity 24, 24a ... Molten resin injection means 35, 35a ... Gas injection means 36, 36a ... Hydraulic cylinder 40, 40a ... Pin portion 42, 42a ... Hole portion 56 ... Overflow chamber 62 ... Pin 64 ... Hydraulic cylinder

Claims (2)

[Claims] 1. A molding apparatus for molding a hollow molded body by injecting a molten resin into a vertically long cavity formed in a mold and then injecting a gas into the unsolidified resin. There is a molten resin injection means provided on the upper part of the cavity for injecting and injecting a molten resin from above the cavity to a lower part, and provided inside the unsolidified resin provided close to the molten resin injection means. A molding apparatus for a hollow molded article, comprising: a gas injection unit for injecting gas from above to below. 2. A molding apparatus for molding a hollow molded body by injecting a molten resin into a vertically long cavity formed in a mold and then injecting a gas into the unsolidified resin. There is a molten resin injection means provided on the upper part of the cavity for injecting and injecting a molten resin from above the cavity to a lower part, and provided inside the unsolidified resin provided close to the molten resin injection means. A hollow molding body molding apparatus comprising: a gas injection unit for injecting gas from an upper side to a lower side; and an overflow chamber provided at a lower portion of the cavity so as to be openable and closable.