JPS6222354Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for molding a foam from pre-expanded particles of thermoplastic synthetic resin.

When molding a foam using expandable thermoplastic synthetic resin particles (so-called pre-expanded particles) as a molding material, steam and cooling water are supplied alternately to a steam chamber provided around the outer periphery of the mold. It is common to use molding equipment in which the mold is heated and cooled. As is well known, the molding of foam using this type of molding apparatus is usually carried out in the following multi-stage operations.

Mold closing - Pre-expanded particle filling - Mold preheating - One-sided heating -
Double-Sided Heating - Water Cooling - Mold Release All heating is performed by blowing high-pressure steam into the steam chamber or by jetting steam toward the mold from a steam pipe introduced into the steam chamber. Therefore, in any case, during the preheating process, steam first fills the steam chamber and then heats the mold and the resin within the mold. The steam that fills the steam chamber is completely wasted as it is simply cooled during the water cooling process and turned into water and discharged, so a molding device that requires as little steam as possible, in other words, the space of the steam chamber, is used. Needless to say, it is preferable to use a device with as small a size as possible. However, although the steam chamber is intended to supply steam and cooling water to the entire outer circumference of the mold, it covers the entire outer circumference of the mold, so piping for steam and cooling water must be introduced into the steam chamber. In this case, the piping for filling the pre-expanded particles, the eject pin for extruding the molded product, the support (reinforcing material to prevent mold deformation due to the foaming pressure of the resin), etc. are arranged in a complicated manner, and the mold Since the outer circumferential surface of the steam chamber is not necessarily flat, there is a limit to how small the steam chamber space can be.

The present invention has succeeded in further reducing the space of the steam chamber, which is difficult to further reduce from the standpoint of equipment design, as described above. That is, the present invention is a foam molding apparatus that reduces unnecessary steam chamber space by filling the steam chamber space with a filler made of a material that can withstand the steam chamber atmosphere.

In the present invention, "a material that can withstand the steam chamber atmosphere" refers to a material that can withstand heating by high-temperature pressurized steam and rapid cooling by cooling water and maintain its shape for a long period of time. It is desirable that this material is non-water absorbent. Specific examples include glass, Teflon, ceramics, heat-resistant rubber, alumina,
Magnesia, etc. It is also desirable that the material has a low heat capacity and thermal conductivity so as not to absorb too much heat from the steam during molding.

Although the shape of the filler used in the present invention is not particularly limited, it is preferably spherical with a diameter of about 8 mm or more for handling reasons.

The drawing is a schematic cross-sectional view showing the peripheral part of a mold in an embodiment of the present invention as described above. In the same figure, 1 and 2 are mold division pieces that form a cavity when combined as shown in the figure, and 3
4 is a steam chamber, 5 and 6 are steam pipes introduced into the steam chamber (having pores that eject steam in one direction of the mold division), 7 is a pre-expanded particle filler, 8 and 9 are eject pins, 10 is support, 11
and 12 are cooling water inlets, and 13 and 14 are drain outlets, and these device components and their arrangement are not particularly different from those of conventional molding devices, and are not limited to the present invention. The difference from the conventional one is that, as shown in the figure, the space in the steam chamber that remains after being occupied by various parts is filled with the above-mentioned filler 20 (the filler 20 is Although the entire steam chamber is filled, only a portion of it is shown in the figure). Reference numerals 15 and 16 are loading ports for the filler, and 17 and 18 are outlet ports for the filler, which are closed except when filling and discharging the filler.

The foam molding method performed using this device is the same as the method using a molding device having the same structure except that the filler 20 is not filled. In the case of standard operation as described above, the steam ejected from the steam pipes 5 and 6 passes through the gap between the fillers 20 and reaches the peripheral surface of the mold. On the other hand, in the heating process, for example, steam ejected from the steam pipe 6 similarly reaches the mold segment 2 and then enters the mold cavity through a small hole penetrating the mold segment, directly damaging the pre-expanded particles. After being heated, it exits into the steam chamber 3 through the small through hole in the mold dividing piece 1 on the opposite side. If the filler 20 is a spherical particle with a diameter of approximately 8 mm or more, sufficient voids are left between the fillers for the flow of steam and the flow of cooling water in the cooling process as described above, so that heating and cooling can be performed easily. There will be no delays and longer cycle times.

The maximum diameter of the filler used in the present invention is not limited as long as it can be filled into the steam chamber. Furthermore, it is not necessary to use all the fillers of the same size, and two or more fillers of different sizes may be used in combination.

In the molding device of the present invention, the steam chamber is filled with filler material and the steam chamber space is minimized, so when heating starts, steam is not wasted to fill the steam chamber, and the Therefore, it has the advantage that the amount of steam required for molding is smaller than in the case of conventional molding equipment. Various proposals have been made in the past regarding reducing the steam chamber space, but the present invention can be easily implemented without placing restrictions on the design of the mechanism around the mold, and can be implemented easily using existing conventional methods. It is extremely advantageous in that it can be easily carried out by modifying the mold.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view showing the peripheral part of a mold in an embodiment of the present invention. 1, 2: Mold division piece, 3, 4: Steam chamber, 5,
6: Steam pipe, 7: Filler, 8, 9: Eject pin, 10: Support, 11, 12: Cooling water inlet, 13, 14: Drain outlet, 15, 16: Filler charging port, 17, 18: Filler outlet, 20:
Filling material.

Claims (1)

[Scope of utility model claims] In an apparatus for molding foam from pre-expanded particles, the space in the steam chamber is , a foam molding device characterized in that it is filled with a filler made of a material that can withstand a steam chamber atmosphere.