JP3100454B2 - Method and apparatus for molding foamed plastic products - 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 and an apparatus for molding a foamed plastic product characterized by a cooling step.

[0002]

2. Description of the Related Art For example, as a method for molding a foamed plastic product such as foamed polystyrene, a cavity formed between a pair of molds is filled with pre-foamed raw material beads and steam supplied to a chamber portion. After cooling and blowing, cooling water is sprayed on the chamber portion, the mold is cooled by the temperature drop by this spraying and latent heat of vaporization of residual water performed under reduced pressure, and then the product is taken out from the cavity.

However, in the conventional molding method, the residual water on the back side of the mold has a large variation in a part after the water cooling step using a spray nozzle or the like, and the residual water is evaporated from the variation in the next reduced pressure cooling step. There is a problem that the degree of latent heat varies and uniform cooling cannot be performed. In addition, since the cooling water sprayed during the water cooling process cools unnecessary parts other than the mold such as the master frame, a large amount of heat is required to heat the mold again for the next molding cycle. Energy and time are required, and there is a problem that, contrary to energy saving, a molding cycle is lengthened and molding efficiency is deteriorated. Further, the amount of cooling water used in the water cooling process is very large, and the cooling water supply device is of a pressurized type, which causes a problem that the whole device is large and complicated.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and can uniformly and uniformly cool the entire mold by using an extremely small amount of cooling water in a short time. That the entire mold can be reheated to a predetermined temperature in a short time and uniformly for the next molding cycle, and that there is cooling water that could not evaporate because it did not overcool. Dry and high-quality products can be efficiently molded without any problems, greatly shortening the molding cycle and promoting energy savings, realizing economical production, and using cooling water. The present invention has been completed for the purpose of providing a molding method and a molding apparatus for a foamed plastic product which can be reduced in size and a cooling water supply device can be small and simple.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a pre-foamed raw material bead supplied to a cavity formed between a pair of dies, and a chamber on the back side of the dies. In the method of molding a foamed plastic product in which the foam is heated and foamed by the heating fluid supplied to the part, and then cooled from the back side of the mold, a water retaining material is attached to a required portion of the back face of the mold, and the heat foaming is performed. After that, the cooling water is sucked and held in the water holding material while the chamber is depressurized,
A method for molding a foamed plastic product, characterized in that cooling is performed by the latent heat of evaporation of the cooling water held in the water retention material, and the back surfaces of a pair of molds that are opposed to and separated from each other are formed in a heating chamber portion. In a molding device for a foamed plastic product, a cooling water pipe provided with a number of distribution holes is provided on a required portion of the back surface of the mold via a water retaining material, and the cooling water pipe is connected to a cooling water source. And an apparatus for molding a foamed plastic product.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. In the figure, reference numeral 1 denotes a mold composed of a pair of male and female molds which are movably opposed to each other so as to form a molding cavity 1a;
Reference numeral 2 denotes a master frame that supports the mold 1, reference numeral 3 denotes an aluminum plate that covers the back side of the master frame 2, and reference numeral 4 denotes a heating chamber formed on the back side of the mold 1.

In the present invention, a required portion on the back side of the mold 1 is connected to a cooling water source 5 via a supply amount adjusting valve 5a, and is connected via a water retaining material 7 such as a polyester-based nonwoven fabric. In addition, a cooling water pipe 6 having many distribution small holes 6a is provided. The cooling water pipe 6 is a pipe which is densely piped to a portion where the temperature rises sharply during heating and is roughed to other portions so that the mold 1 can be cooled uniformly. The water retention material 7 can be appropriately designed in accordance with the molding conditions and the molding conditions.
As shown in FIG. 3, the cooling moisture pipe 6 is supported by a wire 6b or the like while being attached to the back surface of the mold 1, or the outer periphery of the cooling moisture pipe 6 is covered as shown in FIG. Mounting method can be adopted. The small distribution hole 6a may be formed by forming a drill hole or a slit hole in a portion of the cooling water pipe 6 which is in contact with the water retention material 7.
May be maintained at atmospheric pressure or slight pressure.

[0008]

The thus constituted one is a cavity in which pre-expanded raw material beads are formed between a pair of dies 1, 1.
1a, the mold 1 is heated and foamed with a heating fluid supplied to the chamber 4 on the back side of the mold 1, and then the mold 1,
1 is similar to the conventional one in which the foamed plastic product is molded by cooling from the back side, but the cooling step, which is a characteristic configuration of the present invention, is performed by using a spray nozzle or the like as in the prior art. Instead of cooling by spraying, the cooling water is sucked and held by the water holding material 7 from the cooling water source 5 maintained at atmospheric pressure or slightly pressurized while the chamber section 4 is depressurized, and the cooling water held by the water holding material 7 is held. Is cooled by the latent heat of evaporation. That is, when a predetermined amount of cooling water is supplied from the cooling water source 5 to the water retaining material 7 and the pressure in the chamber portion 4 is reduced by the operation of the vacuum pump 8, the water holding material 7 is attached to a predetermined portion of the back surface of the mold 1. The cooling water is evaporated from the water retaining material 7 and the latent heat thereof cools the mold 1 to a predetermined temperature. In this case, since there is no variation in the residual water on the back surface of the mold 1 as in the related art, extremely uniform cooling is performed in a short time, and further, since cooling by spraying water is not performed, the master frame 2 is cooled. No temperature drop due to water adhesion, etc.
Along with the uniform cooling of the mold 1, the time for reheating the entire mold to a predetermined temperature for the next molding cycle can be shortened and made uniform, so that high quality products can be efficiently molded. Becomes In the cooling, a water retention material 7 is used.
Since only a predetermined amount of cooling water is supplied to the system, the amount of cooling water used can be reduced, and the cooling water can be supplied under substantially atmospheric pressure. It can be.

When the mold 1 is cooled only by the latent heat of evaporation of the cooling water supplied to the water retaining material 7 as in the present invention, the mold temperature is uniformly cooled to less than 1 degree. ,
It was confirmed that there was a remarkable effect as compared with the conventional case where the temperature difference was about 20 degrees. Also, it was confirmed that the amount of cooling water to be used was about 1/20 to 1/8 as compared with the conventional method (when a spray nozzle having an original pressure of 6 kgf / cm ² was used).

[0010]

As is clear from the above description, the entire mold can be cooled uniformly and efficiently in a short time by using only a very small amount of cooling water. The entire mold can be reheated to the specified temperature for a molding cycle in a short period of time and uniformly, and high-quality products are dried without excessive cooling, so there is no cooling water that could not evaporate. The molding can be performed well, and the production cycle can be shortened significantly and energy saving can be promoted to realize production with excellent economical efficiency. The cooling water supply device can be efficiently performed, and the size of the entire device can be reduced by making the cooling water supply device small and simple. Therefore, the present invention greatly contributes to the development of industry as a molding method and a molding apparatus for foamed plastic products that have eliminated the conventional problems.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view showing an attached state of a water retention material.

FIG. 3 is a partially cutaway perspective view showing an attached state of another water retaining material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 4 Chamber part 5 Cooling water source 6 Cooling water piping 6a Distribution small hole 7 Water retention material

Claims (3)

(57) [Claims] 1. A pre-foamed raw material bead is supplied to a cavity formed between a pair of dies, and heated and foamed by a heating fluid supplied to a chamber on the back side of the mold, and then the back side of the mold. In the method of molding a foamed plastic product to be more cooled, a water retention material is attached to a required portion on the back surface of the mold, and after the heating and foaming, the cooling water is suction-held in the water retention material in a state where the chamber is depressurized. And cooling by the latent heat of vaporization of the cooling water held in the water retention material. 2. The molding of a foamed plastic product according to claim 1, wherein cooling water is supplied by a predetermined amount through a cooling water pipe connecting the water retaining material in the depressurized chamber portion and a cooling water source substantially under the atmosphere. Method. 3. A pair of molds (1) opposed to each other so as to freely contact and separate from each other,
In the molding device for a foamed plastic product in which the back surface of (1) is formed in the heating chamber (4), a large number of small holes (5) are provided in a required portion of the back surface of the mold (1) via a water retention material (7). A molding apparatus for a foamed plastic product, characterized in that a cooling water pipe (6) provided with 6a) is attached thereto and the cooling water pipe (6) is connected to a cooling water source (5).