JPS6153945B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for filling raw material particles in foam molding, and aims to provide a high-quality foam molded product in which the raw material particles are evenly distributed by filling the raw material to the end corners of the cavity. It is said that

Conventionally, when filling raw material particles made of expandable thermoplastic resin such as expanded polystyrene particles into the cavity of a mold, cracking was used to release the filling air. Therefore, there was a drawback that more raw material particles were packed in proportion to the amount of cracking.

The case of this conventional filling method will be explained with reference to FIG. 1. A indicates a cavity type and B indicates a core type. In the cavity type A, the box frame 11 and the inner mold 12 are attached with bolts (not shown) or the like. Core type B is box frame 2
1 and an inner mold 22 are attached with bolts or the like, and a cavity 30 is formed between the inner molds 12 and 22. When filling the raw material particles into the cavity 30 using the raw material filling device C, the cavity mold A and the core mold B are not completely closed, but a gap d of several mm is provided, and the air used for filling the raw material is Air is discharged to the outside from this gap d and passes through a core vent 23 (particularly shown enlarged in FIG. 4) attached to the inner mold 22 for the core, through an exhaust valve 24 attached to the back of the box frame 21 for the core. It is discharged to the outside through the opening 25. A part of the air was discharged to the outside by opening the drain valve 26, and at the same time, the drain valve 16 was opened and the air was discharged to the outside through the core vent 13.

Once the above-mentioned raw material filling is completed, a method is adopted in which the gap d is set to 0 and steam heating is performed to heat and expand the raw material particles to perform foam molding, and after cooling, the foam molded product is taken out. was.

However, a large amount of raw material particles with a volume equivalent to the gap of several millimeters that would cause cracking is filled (in the figure, the part corresponding to the bottom of the molded product is filled mostly), and this part becomes heavy and the specific gravity is partially reduced. The disadvantage is that foam molded products with different values can be produced (in the case shown in the figure, there is a difference in specific gravity between the bottom and rising parts of the molded product). Moreover, since a large amount of raw material particles are partially added and then the mold is closed, the mold becomes compressed, making it difficult for steam to pass through, so a large amount of steam is required for foam molding, and the cooling water is also heavy in some areas. Since it is necessary to cool down the product, it takes a long time to cool down, consumes a lot of energy, and has drawbacks that are not desirable in terms of energy conservation.

Therefore, the present invention is a filling method that can overcome the drawbacks of the conventional filling of raw material particles, and its characteristics are that the cavity of a mold is filled with a raw material made of expandable thermoplastic resin particles, In foam molding, in which a foam molded product is obtained by heating and expanding the raw material with steam, the steam hole near the filling hole allows steam, etc. to flow from the steam chamber to the cavity, but there is no flow of steam, etc. from the cavity. In addition, for the steam holes located far from the raw material filling hole, use one that allows steam, etc. to flow between the steam chamber and the cavity, and to create a negative pressure in the steam chamber when filling the raw material. By doing so, the raw material filling air is sucked through the steam hole and the raw material is filled up to the end corner of the cavity.

The method of the invention will now be illustrated with reference to the drawings together with the apparatus used for its implementation.

That is, in the method of the present invention, filling by cracking is not performed, but filling with raw material particles is performed with cavity mold A and core mold B closed. As the steam holes attached to the core inner mold 22, a special steam hole forming mechanism 40 is provided at a location near the raw material filling device C. Regarding this steam hole forming mechanism 40, when steam is supplied from the steam chambers a and b to the cavity 30 surface, the steam is supplied into the cavity 30 through the hole 42 formed in the slider 41 and through the gap t. (See Figure 5). 43 of the 40 mechanisms for forming steam holes
is a stopper provided to adjust the gap t and prevent the mover 41 from coming off.

Further, at a location farther from the raw material filler C, a core vent 23 similar to the conventional one is provided to allow steam, etc. to flow between the steam chamber and the cavity. 17,2 in the figure
7 is a water supply valve, 18 and 28 are steam supply valves, 1
9 indicates a fixed frame, and 29 indicates a moving frame.

The method of filling the raw material is to operate the pressure reducing device 50 which makes the inside of the steam chamber b a negative pressure while filling the raw material. By creating a negative pressure inside the steam chamber, the air used when filling raw materials passes through the cavity 30 and into the core vent 2.
3, and is discharged to the outside through drain valves 26 and 26'. Since the raw material particles are carried along with the air, they are filled with air to the end of the cavity far away from the raw material filling device C, so that the raw material particles can be spread to every corner of the cavity and completely filled without cracking. .

Then, in the special steam hole forming mechanism 40, the steam chamber b becomes a negative pressure by operating the pressure reducing device 50, and as a result, the mover 41 in the mechanism is sucked, and the gap t=0. Due to this steam hole forming mechanism 40, the steam holes near the raw material filling hole allow steam, etc. to flow from the steam chamber to the cavity.
There is no flow of steam etc. from the cavity.

Note that a similar special steam hole forming mechanism 40 may be attached to the cavity inner mold 12 to open the drain valve 16 and connect it to a pressure reducing device.
Since the cost is high, the case is shown in which it is installed only in the core mold B on the opposite side from the raw material filling device C. This kind of implementation can fully achieve the purpose.

However, in the illustrated embodiment, if the pressure reducing device 50 is operated and the drain valve 16 is left open, there is a risk that moisture etc. in the steam chamber a may enter the cavity 30 through the core vent 13 and cause a filling failure. Therefore, when creating a negative pressure in the steam chamber b with the line between the drain valves 26, 26' and the pressure reducing device 50, the drain valve 16
It is also better to keep the drain valve 26' for cooling water closed.

Furthermore, the foam molding performed after filling the raw material particles is the same as the conventional method. Also, the same reference numerals are given to structural parts similar to those of the conventional device in the drawings.

Furthermore, in order to compare with the method of the present invention, when the special steam forming mechanism 40 is not used and the conventionally used core vents 13 and 23 are used as a whole to suck air at negative pressure, The raw material particles enter only around the filling hole C, and the raw material particles do not evenly spread to the ends of the foamed molded product, causing a so-called bridging phenomenon.

To give an example of the method of this invention, the foam molded product is a fish box with a size of 285 x 485 x 150 mm and a wall thickness of 20 mm.
, and only the upper two rows of core type B, which are the rising parts of the foam molded product, have the same core vents 2 as before.
3 is installed, and the others are equipped with the special steam forming mechanism 40 mentioned above.On the cavity type A, only the conventional core vent 13 is installed, and the drain valve 1 is installed when filling the raw material.
6 and 26' were closed, the drain valve 26 was opened, and the suction device 50 for negative pressure suctioned and filled at a maximum static pressure of 180 mm. Complete and uniform filling was possible within a filling time of 4 seconds.

As described above, according to the method of this invention, it is possible to spread the filling of raw material particles to the end corners of the cavity without cracking, and it is possible to spread the filling of raw material particles to the end corner of the cavity without cracking. By realizing filling, it is possible to provide a homogeneous foamed molded product with no uniformity in specific gravity as a whole.

Furthermore, compared to the conventional method of cracking and filling raw material particles, it can save raw material particles, steam used, and cooling water in terms of molding, and is superior in terms of energy conservation, and can also contribute to increasing the cycle-up of foam molding.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view explaining the conventional method, Figure 2
The figure is a schematic sectional view illustrating an embodiment of the method of this invention, FIG. 3 is an enlarged sectional view of section E in the previous figure, FIG. 4 is a perspective view of the core vent, and FIG. FIG. A...Cavity type, B...Core type, 11,
21... Box frame, 12, 22... Inner type, 16, 26, 26'... Drain valve, 1
3, 23...Core vent, 30...Cavity, 40...Special steam hole forming mechanism.

Claims (1)

[Claims] 1. In foam molding, in which a raw material made of expandable thermoplastic resin particles is filled into the cavity of a mold and the raw material is heated and expanded with steam to obtain a foam molded product, the steam hole near the filling hole is placed in the cavity from the steam chamber. Use a vent that is formed so that there is a flow of steam, etc. to the cavity, but not from the cavity, and for steam holes located far away from the raw material filling hole, there should be no flow of steam, etc. between the steam chamber and the cavity. In foam molding, the material is filled to the end corner of the cavity by using a material with a flow, and by creating a negative pressure in the steam chamber when filling the material, the material filling air is sucked through the steam hole and the material is filled to the end corner of the cavity. Method of filling raw material particles.