JPS6254665B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam hole mounting mechanism in a foam molding apparatus, which prevents cooling water during cooling from entering the mold through the steam holes.

In general, a foam molding device in which expandable thermoplastic resin particles are filled in a mold cavity between molds, and the particles are heated and expanded using steam as a heating medium to thermally fuse and mold the particles, Water used during cooling tends to enter the inner surface of molds, etc., mainly through steam holes, which hinders the filling of raw materials. Therefore, extra cracking is taken and filling is performed while blowing out water. There is. However, if cracking occurs too much, the weight of the foamed molded product becomes heavier, and both heating time and cooling time become longer, which also causes an increase in product cost.

Therefore, it is necessary to have a steam hole in the inner surface of the mold to prevent water from leaking, but in the conventional case, a slit part 2 with a steam slit 1 formed at the tip as shown in FIGS. 1 to 3 is used. The most common method is to drive (core vents) into the foam molds 10' and 20', but in places where the slit parts 2 cannot be driven, drilled holes 3 with a diameter of 1 to 2 mm are formed by drilling. Ta.

The disadvantages of the above conventional method are that water accumulates in the slit part 2 located on the top surface of the mold, and water accumulates in the slit part 2 located on the mold side surface, as is clear from Figure 2 showing the installation state of the slit part 2. Part 2
Water accumulated below the inner surface of the mold, and when the foamed molded product 40' was removed from the mold cavity 30', this accumulated water entered the mold. On the other hand, even in the case of using the drilled holes 3 illustrated in FIG. 4, it takes time and effort to drill a large number of drilled holes 3.
Since it is technically difficult to drill a hole (0.8 mmφ) and there is a problem that the drill hole may break, the drill hole 3 had to be made large, making it difficult to prevent water from entering.

Therefore, the present invention attempts to provide a steam hole mounting mechanism that can eliminate all of the drawbacks of the prior art described above, and its configuration is as follows:
A columnar body for steam holes having a large number of small pores is driven and fitted into a foam molding mold, and the part of the columnar body facing the molded product is aligned with the inner surface of the mold, and the opposite part is with the outer surface of the mold. It is characterized by being aligned or slightly protruding from the outer surface of the mold.

Next, regarding embodiments of this invention, FIGS.
An example will be given below with reference to FIG. 10,2
0 is a mold by a metal mold, 30 is a mold cavity, 11, 21
40 is a molded product, 50 is a mold 10, 2
This is a cylindrical columnar body for a steam hole that is driven into the interior of the steam hole. The columnar body 50 for steam holes has a large number of small holes 51 that serve as steam holes. The fitted state of the steam hole columnar body 50 is such that the part facing the molded product 40 is aligned with the inner surface of the mold, and the opposite part of the mold outer surface that is exposed to water is made to protrude higher than the mold outer surface to prevent water from entering. There is no infiltration. Also, 0.8 in the experiment
In the case of the small holes 51 having a diameter of mmφ or less, it was confirmed that water does not enter the small holes 51 due to the surface tension of water unless the inner surface of the mold is open. Since the inner surface of the mold is filled with particles of polystyrene foam or the like that has the foaming power to effect fusion, there is no risk of the mold becoming open. Furthermore, the columnar body 50 for the steam hole can be processed separately from the mold and has a different purpose, but currently the drilling technology is 0.4mm for a columnar body of 10mmφ.
A technology has been perfected that allows the formation of countless φ-sized holes (approximately 100), and the length can be freely selected, making it even easier to form steam holes. It is convenient to form a slip prevention part by knurled grooves, sandblasting or other processing on the outer periphery of the side 52 of the columnar body 50 that is closer to the outside surface of the mold, and the shape of the columnar body 50 is Although a cylindrical shape is most suitable because it is easy to implement, other cylindrical shapes are also possible. In the figure, steam supply holes, cooling water supply holes, drain holes, etc. are omitted.

By adopting the above-mentioned steam hole mounting mechanism, water will not enter the mold as described above, so it is possible to fill the raw material without cracking during molding, and depending on the thickness of the foam molded product. Although it varies somewhat, it can result in raw material savings of about 5-7%. For example, when foam-molding a 30 mm thick plate, removing 3 mm of cracking results in approximately 10% overfilling, so it is extremely effective to be able to fill the material without cracking. In addition, even if the unit price of the columnar bodies for steam holes is twice that of conventional products, the price increase can be limited to about 1% of the total mold, so the raw materials used in foam molding will gradually increase. The economic benefits of savings are far greater.

Furthermore, in terms of foam molding, the present invention has an advantage of 0.2 mm compared to conventional slits.
Since it is possible to form small holes of ~0.3 mmφ, the residue caused by the contact of the molded product surface with the steam holes becomes almost inconspicuous, and beautiful surface molding is promoted. As an embodiment of this invention, 80 small holes of 0.5 mmφ are drilled in a steam hole columnar body with a diameter of 10 mmφ and a length of 12 mm, and steam holes are installed at a pitch of 45 mm in a mold with a thickness of 10 mm (9.8 to 9.9 mmφ). ), the molded product dimensions are external dimensions 350 x 500 mm, 150 mmH, average wall thickness 25
When a mold capable of molding a molded product with 50 times the foaming size was manufactured and carried out, in the case of this invention, the material was filled by removing cracking of 3 mm, but in the case of this invention, the inner surface of the mold was no longer wet. Can be molded without cracking, conventional heating time is 38 seconds and cooling time is 47 seconds.
However, in this invention, the heating time was 32 seconds, the cooling time was 41 seconds, and the weight of the molded product was 185 g.
The reduction was 16% in the heating time, 13% in the cooling time, and 18g in the weight of the molded product.

This result also shows that in this invention, the steam holes are installed using a columnar body for the steam holes that can maintain the inner surface of the mold in a dry state, and it is possible to fill the raw materials without cracking, control the weight of the molded product, and heat the mold. It is clear that the time and cooling time can be shortened, and the profitability of foam molding technology can be greatly improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of a conventional device equipped with a slit part, Fig. 2 is an enlarged sectional view of part A in the previous figure during molding, Fig. 3 is a perspective view of the slit part, and Fig. 4 is a drilled hole. 5 is a schematic sectional view of a conventional device provided with steam holes according to the present invention, FIG. 6 is an enlarged sectional view of part B in the previous figure during molding, and FIG. 7 is a schematic sectional view of a device provided with steam holes according to the present invention. It is a perspective view of the columnar body for steam holes used. 10, 20... Foaming mold, 30... Mold cavity, 4
0... Molded product, 50... Columnar body for steam hole, 51...
...Small hole serving as a steam hole, 52...Side close to the outer surface of the mold.

Claims (1)

[Scope of Claims] 1. A columnar body for steam holes having a large number of small holes penetrated is driven and fitted into a mold for foam molding, and a portion of the columnar body facing the molded product is aligned with the inner surface of the mold; An attachment mechanism for a steam hole in a foam molding apparatus, characterized in that the opposite point is aligned with the outer surface of the mold or slightly protrudes from the outer surface of the mold. 2. A steam hole attachment mechanism in a foam molding apparatus according to claim 1, wherein the large number of small holes penetrated are 0.8 mmφ or less.