JP2580466B2 - Panel product manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a panel product. More particularly, the present invention relates to a manufacturing method capable of easily forming a panel product such as a hollow high-quality pallet, flooring material, door or bathtub by a relatively simple mold.

[0002]

2. Description of the Related Art In the past, when manufacturing panel products, an injection molding method has been used. That is, by injecting the molten synthetic resin into the closed mold cavity at a high pressure, the molten synthetic resin is brought into close contact with the entire inner surface of the mold cavity. In the case of manufacturing a hollow panel product, the mold cavity is filled, and the volume of the mold cavity is increased while injecting a compressed gas into the molten resin from an injection port provided in the mold. There is known a method of moving a mold to the surface (for example, Japanese Patent Application Laid-Open No.
issue).

[0003]

In the conventional molding method by injection molding, the molten synthetic resin is injected into the mold cavity at a high pressure, so that the mold clamping pressure needs to be increased. The tightening mechanism becomes very expensive. In addition, when molding large products, a large and expensive injection device is required. As described above, according to the conventional manufacturing method, the equipment cost is high, and it is necessary to fill the corners of the cavity by injecting the molten resin from a small nozzle at a high pressure. Non-uniform pressure occurs. When it is cooled and solidified (or cooled and solidified after forming cavities) as it is, there arises a problem that the molded product is easily broken partially due to residual stress.

[0004] The present invention has been made to solve such a problem, and is provided by relatively simple and inexpensive equipment.
It is an object of the present invention to provide a method for easily producing a high quality hollow panel product.

[0005]

The manufacturing method of the present invention is a method for manufacturing a hollow panel product, which comprises the steps of: (1) pouring a synthetic resin in a molten state into an inner surface of a female mold opened upward;
(2) A male mold is fitted to the female mold, and the synthetic resin is lowered and compressed to expand the synthetic resin, thereby expanding the synthetic resin in a space formed by the male mold and the female mold, and (3) Compressed gas is injected into the synthetic resin from at least one injection portion, and a gap between the male mold and the female mold is enlarged so as to correspond to a predetermined thickness of a molded product. A cavity is formed in the cavity. (4) The synthetic resin is pressed against the entire inner surface of the cavity composed of the male mold and the female mold by the compressed gas. (5) The synthetic resin is cooled, solidified and then released. It is characterized in that a molded product is taken out.

[0006] At least one site of at least one of the male mold and the female mold can be moved separately, and after a gap between the male mold and the female mold is enlarged, a predetermined time elapses. After that, when the resin temperature falls and exhibits a predetermined viscosity, a step of forming a reinforcing rib in the cavity by utilizing the viscosity of the molten resin by moving the portion in the expanding direction is provided. Preferably.

[0007]

In the manufacturing method of the present invention, it is not necessary to inject the molten synthetic resin at a high pressure in order to fill the mold cavity, but merely to pour the molten resin into the female mold. As described above, the manufacturing method of the present invention does not require a high-pressure injection device, so that the equipment cost is low, and the cost of the product can be reduced.

In addition, since the expansion and pressure bonding of the molten synthetic resin to the entire inner surface of the cavity is performed by a compressed gas that is clamped and pressed, the clamping pressure is much lower than in the conventional injection molding method. Therefore, the mold and the mold clamping mechanism are simple, and the equipment cost can be further reduced.

Further, the pressure of the compressed gas causes the molten synthetic resin to be pressed almost uniformly on the entire inner surface of the cavity even during its cooling and solidification, so that the shape of the inner surface of the cavity is faithfully reflected on the outer shape of the product. No distortion, sink marks, warpage or dents are generated, and a thin portion due to uneven resin flow is not generated.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 is a partially cutaway perspective view showing an example of a hollow panel manufactured by the manufacturing method of the present invention, FIG. 2 is an explanatory view showing an embodiment of the manufacturing method of the present invention, and FIG. FIG. 4 is an explanatory view showing another embodiment of the manufacturing method of the present invention, and FIGS. 5 and 6 are explanatory views showing still another embodiment of the manufacturing method of the present invention.

In FIG. 1, reference numeral 1 denotes a door 1 manufactured by a manufacturing method described later, in which a plurality of columnar ribs 3 connecting a cavity 2 and an inner surface of the cavity facing each other are formed. As described above, since the front and back surfaces are formed as a single piece, they have high rigidity. However, since the ribs 3 are formed in the cavity 2, the door has sufficient strength as a door. It will be.

FIG. 2 schematically shows a process of forming the door 1. As shown in FIG. 2A, a mold 4 used for molding includes a male mold 5 and a female mold 6. At least one injection port 7 for injecting a compressed gas is formed in the male mold 5 so as to be slightly inserted into the molten resin. In this embodiment, a hollow needle (referred to as an air needle) for injecting a compressed gas is attached to the male mold 5. The injection port 7 may be formed in either male or female mold. In addition, a frame-shaped core 9 that is movable with respect to the male mold 6 to form a gap 8 between the two dies 5 and 6 around the periphery of the male mold 5.
Is provided. First, a required amount of molten resin (hereinafter referred to as resin) P is poured into the cavity 11 of the female mold 6 (see FIG. 2A).

Then, as shown in FIG. 2B, the male mold 5 is lowered and fitted to the female mold 6. Subsequently, as shown in FIG. 2C, the cavity 11 is closed, and the resin P is compressed and expanded into the cavity 11.

Next, as shown in FIG. 2D, the male mold 5 is pulled up to a predetermined thickness of the molded product while injecting a compressed gas into the resin P from the injection port 7, thereby reducing the volume of the cavity 11. The cavity 2 is formed in the resin P by enlarging. The position of the lower end of the raised male mold 5 matches the lower end of the frame-shaped core 9. By doing so, the portion of the resin P which is being brought into close contact with the inner surface of the cavity 11 and is hardening is not stretched before and after the movement of the male mold 5 (before and after the expansion of the cavity 11), so that the wall thickness is reduced. There is no unevenness. In the case of manufacturing a molded product having a small thickness, the frame-shaped core 9 is particularly preferable.
It is not necessary to form the gap 8 in advance.

Further, by appropriately adjusting the pulling time and pulling speed of the male mold 5 in accordance with the type of the resin P and the thickness of the molded product, and utilizing the viscosity of the resin P, FIG.
As shown in FIG. 7, the ribs 3 are formed by connecting the resin P at a plurality of places in the cavity 2. After the resin P is cooled and cured, the mold 4 is opened, and the molded door 1 is taken out.

FIGS. 3 (a) and 3 (b) show a method of forming the bathtub 12 in the same procedure as described above. Bathtub 12
Because the side of is inclined from the bottom with respect to the vertical direction,
By pulling up the male mold 13 (FIG. 3A), the side wall of the bathtub 12 can also be formed in a hollow shape.

FIGS. 4 (a) and 4 (b) show a method of forming a bathtub 15 whose side surface is at right angles to the bottom surface using a divisible female mold 14. FIG. In other words, the steps up to tightening the mold 16 and expanding the resin P into the cavity 17 are the same as the steps in the above embodiment (FIGS. When the mold 18 is pulled up, the side part 14a of the female mold 14 is similarly moved in the direction of increasing the volume of the cavity 17 (outside in the lateral direction) to make the side wall of the bathtub hollow.

FIGS. 5A to 5C also show the door 19
Is shown. In this molding method, the ribs 21 in the cavity 20 can be surely formed at the planned portions, and therefore, the above-described embodiments (FIGS. 2A to 2D, 3A to 3
4 (b) and FIGS. 4 (a) to 4 (b)) are different from those in which a rib forming portion cannot be set in advance.

In this molding method, as shown in FIG. 5A, a movable core 23 that can move relatively to the male mold 22 is slightly inserted into the resin P into the male mold 22. It is provided in. Then, as shown in FIG. 5B, when the male mold 22 is pulled up together with the movable core 23 while injecting the compressed gas, the resin P adheres to the periphery of the movable core 23 and is stretched. Thereafter, as shown in FIG. 5C, when the movable core 23 is pulled up, the rib 2 is moved to the planned position in the cavity 20.
1 is formed.

Alternatively, as shown in FIGS. 6 (a) to 6 (b), when the male mold 22 is pulled up while injecting compressed gas, the movable core 23 is not pulled up, but is left at the mold closing position. The resin P is adhered to the periphery of the child 23,
Even if the movable core 23 is pulled up after a lapse of a predetermined time, a rib 21 similar to that shown in FIG. 5C is formed.

In all of the above embodiments, the male type is moved. However, the present invention is not particularly limited to the male type, and the male type is fixed and the female type is moved downward. It may be a method.

Examples of the synthetic resin material used include thermoplastic resins such as polystyrene, polyethylene, acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, ethylene-vinyl acetate copolymer resin, and polypropylene.

According to the manufacturing method of the present invention, in particular, not only the above-mentioned doors and bathtubs, but also floors and wall panels such as bathrooms, lids of bathtubs or wash basins, etc., are formed with high rigidity and excellent heat insulating effect. sell. Further, it is also possible to form fittings such as bran, sill, or sill, partition panels, cupboards or walls.

[0025]

According to the manufacturing method of the present invention, a high quality hollow panel product can be easily manufactured with relatively simple equipment.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an example of a hollow panel manufactured by a manufacturing method of the present invention.

FIG. 2 is an explanatory view showing one embodiment of the production method of the present invention.

FIG. 3 is an explanatory view showing another embodiment of the production method of the present invention.

FIG. 4 is an explanatory view showing still another embodiment of the production method of the present invention.

FIG. 5 is an explanatory view showing still another embodiment of the production method of the present invention.

FIG. 6 is an explanatory view showing still another embodiment of the production method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Door 2 Cavity 3 Rib 4 Mold 5 Male mold 6 Female mold 7 Injection 11 Cavity 13 Male mold 14 Female mold 16 Mold 17 Cavity 19 Door 20 Cavity 21 Rib 22 Male mold 23 Movable core

Claims (2)

(57) [Claims] 1. A method for manufacturing a hollow panel product, comprising: (1) pouring a synthetic resin in a molten state into an inner surface of a female mold opened upward, and (2) fitting a male mold to the female mold. Let
By lowering and compressing the synthetic resin, the synthetic resin is expanded in a space composed of a male mold and a female mold, and (3)
Compressed gas is injected into the synthetic resin from at least one injection portion, and a gap between the male mold and the female mold is enlarged so as to correspond to a predetermined thickness of a molded product. (4) The synthetic resin is pressed against the entire inner surface of the cavity composed of the male mold and the female mold by the compressed gas, and (5) the synthetic resin is cooled, solidified and then released. And a method for producing a panel product, wherein a molded product is taken out. 2. The method according to claim 2, wherein at least one site of at least one of the male mold and the female mold can be moved separately, and a gap between the male mold and the female mold is enlarged.
The method of manufacturing a panel product according to claim 1, further comprising a step of forming a reinforcing rib in the cavity by moving the portion in the enlargement direction after a predetermined time has elapsed.