JPH11309734A - Method for foam molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate packing density nonuniformity in each process of packing, heating, cooling, and demolding, the delay of temperature increase and temperature decrease, or a water leakage phenomenon. SOLUTION: In a method for foam molding in which raw material beads are packed into a cavity 1 for foaming surrounded by a pair of molds 21, 31, and the beads are heated and expanded into a foamed molding, which is cooled and demolded, when the molds 21, 31 are closed, in the mating places of mold peripheral parts 21a, 31a located the peripheral end part 1a of the cavity 1, by using an intermold passage 12 which is formed to communicate with an external utility port 13, various kinds of utility such as steam supply, pressurization/evacuati on, compressed air supply are operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a foam molding method for producing a heat insulating container or a construction material made of a foamed resin such as polystyrene or a heat insulating floor substrate.

[0002]

2. Description of the Related Art An outline of a foam molding method as a background of the present invention will be described. The arrangement of the mold apparatus used in this conventional foam molding is such that a convex mold 3 is formed so as to form a cavity 1 in which a foamed product is filled and molded as shown in a schematic sectional view of FIG.
1 and the concave mold 21 are fixed to and opposed to the frames 23 and 33, and the concave mold 21 is usually fixed. However, the convex mold 31 is located inside the concave mold 21 as shown in FIG. It is arranged so as to move horizontally (to the right in FIG. 2) from the state where the cavity 1 is formed, and to be able to take out the molded foam. The molds 21 and 31 are provided with a large number of vent holes 22 and 32 so that utilities such as heating steam described later can pass therethrough.

A concave chamber 2 and a convex chamber 3 to which utilities such as steam are supplied are formed on the back side of the concave and convex molds 21 and 31. In this case, upper chambers 24 and 34 for supplying steam for heating and the like are provided at the upper part of each chamber 2 and 3, and lower chambers 25 and 35 are provided at the lower part. And
It is connected to a pressure reducing pump or a drain pipe (neither is shown).

In practice, the large number of vent holes 22 and 32 provided in the molds 21 and 31 have an outer diameter of 7 to 12 in which 10 to 20 vent holes of about 0.5 mmφ are provided.
A core vent made of an aluminum alloy having a cylindrical body having a lid of 2 mm is fitted in a core vent mounting hole formed in the surfaces of the molds 21 and 31 at a pitch of 20 to 30 mm.

[0005] The outline of the foam molding method using such a mold apparatus for foam molding is as follows. (1) First, a mold is closed to form a cavity 1, and a pre-foamed material such as polystyrene is formed in the cavity 1. Filling the raw material beads. Next, (2) a heating step in which the raw material beads are heated by heating steam and melted and foamed.
(3) Then, a cooling step of cooling and solidifying the foam,
(4) After the cooling, the mold is opened, and the mold is released from the mold apparatus as a foamed molded article having a predetermined shape.

Here, each of these steps will be further described. (1) Raw Material Bead Filling Step This is a step in which raw material beads are fed from an external raw material service tank (not shown) into the cavity 1 through the feeder 26 and filled therein, which includes a cracking filling method, a pressure filling method, or a filling method. There are pressure compression filling methods and the like, but in each case, compressed air for transporting the raw material beads is extracted from the cavity 1 to the chambers 2 and 3 through the vent holes 22 and 32 and discharged to the outside. Or concave and convex molds 21,
31 is not completely closed, and the mold outer peripheral portions 21a, 31a
When a certain amount of gap is temporarily left, that is, when cracking is provided, the compressed air is also discharged from the cracking gap.

In such a filling method without cracking, there is a problem that the raw material beads are not easily filled in the outer peripheral end portion 1a of the cavity 1 and density unevenness is likely to occur. Also, if the cracking is provided for that,
Although the density unevenness at the tip end can be avoided to some extent, when the raw material beads are compressed by the amount of the mold closing margin by closing the mold after filling, the compressibility differs between the side surface portion and the flat surface portion of the cavity 1, and as a result, There is a problem that the packing density varies. Further, since the cracking communicates with the atmospheric pressure, there is a problem that the back pressure is high and the pressurized compression filling method cannot be performed.

(2) Heating step In this case, the heating steam supplied from one chamber, for example, the convex side chamber 3 is sent into the cavity 1 through the vent hole 32 of the convex mold 31 and is filled. After heating the raw material beads, the raw material beads pass through the vent hole 22 of the concave mold 21, exit to the concave side chamber 2, and are discharged to the outside.

In this case, the outer peripheral tip portion 1 of the cavity 1
Since a has a dead end shape, it is difficult for steam to reach it, and heat flows into the outer peripheral portions 21a, 31a of the concave and convex dies 21, 31 having a relatively large heat capacity. Since the temperature of the raw material beads at the outer peripheral tip portion 1a is hard to rise, and the temperature rise is considerably delayed compared to other portions, the time of the heating step has to be lengthened.
There was a problem that the total molding time was long.

(3) Cooling Step After the heating step, when cooling, the cooling water is poured into the concave and convex molds 21 and 31 from the respective chambers 2 and 3 sides, or the pressure is similarly reduced to reduce the mold pressure. The attached water and the water in the cavity 1 are evaporated, and the heat of vaporization at that time cools the foamed molded body together with the molds 21 and 31. Also at this time, for the same reason as in the previous heating step, the temperature of the outer peripheral portions 21a and 31a of the mold is hardly lowered, and the portion of the foam molded body located at the outer peripheral end portion 1a of the cavity 1 is sufficiently cooled. There was a problem that it took time.

(4) Release process In this release process, the convex mold 31 is moved to the right (FIG. 2), and then the foam molded body is ejected from the back side of the concave mold 21 with an eject pin (not shown). Is extruded rightward (FIG. 2), and the foam molded article is taken out of the mold. In this case, when the convex mold 31 is opened, water that has accumulated in the inter-cavity 11 that is a seam of the mold apparatus and that is surrounded by the mold outer peripheral portions 21a and 31a and the frames 23 and 33 flows down. There was a problem that the foamed molded product as a product was wet.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made in consideration of the following problems.
Mold outer peripheral parts 21a and 31 in each step of cooling and releasing
The present invention provides a foam molding method capable of eliminating uneven packing density, delay in temperature rise and temperature fall, or water phenomena caused by the outer peripheral tip portion 1a of the cavity 1 or the cavity 1.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the foam molding method of the present invention is directed to a foam molding cavity formed by being surrounded by a pair of dies having a chamber disposed on the back side. Filling the raw material beads, heating and foaming it to form a foamed molded article, a foaming molding method for cooling and releasing the mold, and when the pair of molds is closed, It is characterized by operating various utilities such as steam supply, pressurization and decompression, and supply of compressed air by using the inter-mold passage formed to communicate with the outside at the joint of the mold located around the cavity. It is assumed that.

According to still another embodiment of the present invention, there is provided a foam molding method, wherein the foam molding method includes at least one of the following operations using the inter-mold passage. . 1) An operation of exhausting filling air through a mold-to-mold passage formed at a joint of the molds when filling the raw material beads. 2) An operation of adjusting the pressure in the cavity through the inter-mold passage when filling the raw material beads. 3) At the time of heating the filled raw material beads, steam is introduced into the inter-mold passage to heat the periphery of the inter-mold passage, and is also fed into the cavity to heat the raw material beads around the cavity. The operation to supplement. 4) During the cooling, an operation of reducing the pressure in the cavity through the inter-mold passage to promote cooling by vaporizing moisture. 5) The operation of discharging the drain from the inter-mold passage at the time of the mold release operation for removing the foamed molded product.

[0015]

Next, an embodiment of the foam molding method of the present invention will be described with reference to FIG. FIG. 1 shows a cross section of a main part of a foam molding die apparatus to which the foam molding method of the present invention can be applied. A large number of vent holes are formed so as to form a cavity 1 into which foaming material beads are filled and molded. A convex mold 31 having concave portions 22 and 32 and a concave mold 21 are fixed to frames 23 and 33 and are arranged to face each other.
On the back side of these concave and convex molds 21 and 31, a concave chamber 2 and a convex chamber 3 to which utilities such as steam are supplied are formed. In this case, each of the chambers 2 and 3 is formed. Upper ports 24, 34 for supplying steam for heating are provided at the upper part, and lower ports 25, 35 for the lower part are provided at the lower part. The structure of the mold apparatus described above is not particularly different from the conventional apparatus described above.

A characteristic point of this mold apparatus is that when the molds 21 and 31 are closed, the outer peripheral end portion 1a of the cavity 1 communicates with the external use opening 13 provided on the frame 23 side. The inter-mold passage 12 and the inter-mold cavity 11 are
It is formed at the joint of the mold outer peripheral portions 21a and 31a and the frames 23 and 33. In this case, the inter-model passage 12 and the inter-model cavity 11 shown in the upper part of FIG.
Are also represented in the lower part of FIG. Also,
The external service opening 13 is a frame 33 instead of the frame 23.
May be provided on the side of.

Further, as the inter-cavity 11, a conventionally existing one can be used.
May be formed in a band shape over the entire circumference of the outer peripheral end portion 1a of the cavity 1, or may be formed intermittently. The width dimension of the cavity 1 side opening of the inter-mold passage 12 needs to be set to be equal to or less than the outer diameter of the raw material beads to be filled. In the example of FIG. 1, a steam supply pipe S is connected to the external use port 13 communicating with the mold cavity 11, and at the same time, a drain pipe D and a vacuum exhaust pipe V or, if necessary, compressed via a valve. An air pipe (not shown) and the like are branched and connected, and operations such as supply of various utilities are provided so as to be able to be performed independently and separately from a conventional normal operation performed through the vent holes 22 and 32. .

The foam molding method in this embodiment utilizes the above-described mold apparatus shown in FIG.
Raw material beads are filled in the foam molding cavity 1 formed by being surrounded by the pair of concave and convex molds 21 and 31, and heated and foamed to form a foam molded body, which is cooled and then released. And forming a pair of the concave and convex molds 21 and 31 when the molds are closed.
At the joint of 1a, various utilities such as steam supply, pressurization and decompression, and supply of compressed air are operated by using the inter-model passage 12 formed so as to communicate with the external utility port 13 through the inter-cavity 11. That is, a method of supplying each utility and adjusting its pressure.

In this case, the utility operation using the inter-mold passage 12 is performed independently and independently of the utility operation using the vent holes 22, 32 of the dies 21, 31, or in conjunction therewith. Whether to perform the operation in common can be appropriately selected according to the molding conditions. However, when the operation is performed independently as in the former case, the operation can be performed with high accuracy, which is a more preferable method.

Further, the present invention can be embodied as a foam molding method including at least one of the following operations using the inter-mold passage in the above foam molding method.

1) In the step of filling the raw material beads, an operation for discharging the filling air for feeding the raw material beads from the service tank through the inter-mold passage 12 formed at the joint of the dies is performed. In this case, the concave and convex molds 2
Since the air is exhausted from the outer peripheral tip portion 1a of the cavity 1 together with the air exhausted from the vent holes 22 and 32 of the bases 1 and 31, it is possible to prevent the raw material beads from spreading sufficiently without providing cracking and to cause uneven packing density. Can be prevented. Further, even when the foamed molded article is a deep container or a tip portion has a complicated shape, the advantage that the filling property of the raw material beads is improved can be obtained.

2) In the step of filling the raw material beads, not only the gas is exhausted as described above, but also the operation of adjusting the pressure in the cavity 1 through the inter-mold passage 11 is performed. That is,
By adjusting the back pressure to the desired pressure with respect to the pressure of the filling air for feeding the raw material beads from the service tank, the back pressure is reduced to below atmospheric pressure in addition to the pressure filling method, the pressure compression filling method, etc. The most preferable filling method, such as a suction filling method and a vacuum filling method, can be adopted.

3) In the heating step of the filled raw material beads, steam is introduced into the inter-mold passage 12 to heat the periphery of the inter-mold passage 12 and to heat the cavity 1.
To compensate for the heating of the raw material beads around the cavity.

In this case, the mold outer peripheral portions 21a and 31a of the concave and convex molds 21 and 31 are directly heated because the heat capacity is relatively large and the temperature is difficult to increase. Since the temperature of the raw material beads at the outer peripheral end portion 1a can be rapidly increased, the advantage that the total molding time can be reduced is obtained.

In addition, the outer peripheral tip portion 1a formed by steam
The air purge of the mold can be reliably performed, or the pressure can be independently adjusted through the inter-mold passage 12, so that the temperature balance in the mold can be set to the most preferable state by controlling the chamber pressure, such as plus or minus. A significant cycle time reduction or energy saving effect can be expected.

4) In the cooling step, in addition to injecting the cooling water, the inside of the cavity 1 is depressurized through the inter-mold passage 12 so as to promote the cooling by vaporization of the water that has entered the cavity 1 by the injection and to drain the water. Perform the operation to discharge. Also in this case, since the temperature of the outer peripheral portions 21a and 31a of the mold having a large heat capacity and hardly decreasing can be promoted, the cycle time can be greatly reduced.

5) In the mold release step of removing the foamed molded product, an operation of discharging the drain accumulated in the inter-mold passage 12 and the inter-mold cavity 11 is performed. As a result, the drains accumulated in the inter-mold passages 12 and the inter-mold cavities 11 caused by the water injection during the cooling can be removed. Problems such as wetting can be eliminated.

[0028]

Since the foam molding method of the present invention is constituted as described above, the outer periphery of the cavity of the foam molded article in each of the steps of filling, heating, cooling, and releasing from the foam molding method. It is possible to eliminate uneven packing density, delay in temperature rise and temperature fall, or water phenomena occurring in a portion corresponding to the front end portion, thereby improving quality and shortening a molding operation cycle time.

In addition, since independent pressure control using the inter-mold passage can be performed from the pressure adjustment operation of the chamber, the degree of freedom of operation is increased, and the pressure / temperature in the mold can be controlled in a well-balanced manner. Has an excellent effect. Therefore, the present invention has a very large industrial value as a foam molding method which has solved the conventional problems.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a foam molding die apparatus applicable to the present invention.

FIG. 2 is a schematic cross-sectional view of a main part of a conventional foam molding die apparatus.

[Explanation of Signs] 1 cavity, 1a outer peripheral tip, 11 inter-cavity, 12 inter-mold passage, 13 external port, 21 concave mold, 21a outer mold, 22 vent hole, 23
Frame, 31 convex mold, 31a Mold outer peripheral part, 32
Vent hole, 33 frames, S steam piping, D
Drain piping, V decompression piping.

Claims (2)

[Claims] A raw material bead is filled in a foam molding cavity formed by being surrounded by a pair of dies having a chamber disposed on the back side, and is heated and foamed to form a foam molded body, which is cooled. And a mold formed so as to communicate with the outside at the joint of the molds located around the cavity when the pair of molds is closed. A foam molding method characterized in that various utilities such as steam supply, pressurization and decompression, and supply of compressed air are operated using the inter-passage. 2. The foam molding method according to claim 1, wherein
A foam molding method characterized by including at least one of the following operations using the inter-mold passage. 1) An operation of exhausting filling air through a mold-to-mold passage formed at a joint of the molds when filling the raw material beads. 2) An operation of adjusting the pressure in the cavity through the inter-mold passage when filling the raw material beads. 3) At the time of heating the filled raw material beads, steam is introduced into the inter-mold passage to heat the periphery of the inter-mold passage, and is also fed into the cavity to heat the raw material beads around the cavity. The operation to supplement. 4) During the cooling, an operation of reducing the pressure in the cavity through the inter-mold passage to promote cooling by vaporizing moisture. 5) The operation of discharging the drain from the inter-mold passage at the time of the mold release operation for removing the foamed molded product.