JP3055831B2 - Foam molding method for foamed resin - 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 for foaming a foamed resin, which can greatly reduce the foaming time.

[0002]

2. Description of the Related Art Expanded polystyrene (hereinafter abbreviated as EPS) is one of the most widely used fusion foaming moldings using pre-expanded granules as a raw material.

[0003] As a foaming method for increasing the internal fusion of EPS, there are a vacuum heating method and a flow-through heating method.

In the former vacuum heating method, pre-expanded particles of foamed resin are filled in a cavity formed between a closed moving mold and a fixed mold, and each of the moving mold and the fixed mold is filled. After the residual air in the steam chamber and cavity is evacuated by vacuum, high-temperature steam flows between the pre-expanded particles in the cavity from one side to the other at high pressure.
A high-temperature steam is passed from one mold to the other mold at a steam pressure of about 0.3 to 0.5 kg / cm ² for a predetermined time to carry out flow heating for rapidly foaming and molding the pre-expanded particles. If necessary, reverse flow heating is also performed to promote internal fusion. Thereafter, closing the steam outlet of the molds, 0.7~0.8kg / cm ²
The double-sided heating of baking the surface of the foam molded body in the cavity with high pressure vapor pressure is performed. Depending on the shape and thickness of the molded product, the internal fusion is further promoted by using a vacuum during flow heating. In some cases.

In the latter flow-flow heating method, pre-expanded particles of a foamed resin are filled in a cavity formed between a closed moving mold and a fixed mold, and the moving mold and the fixed mold are individually charged. to perform mold heated through high-temperature steam, after which the one mold at 0.3~0.5kg / cm ² about the vapor pressure as between the pre-expanded particle is high-temperature steam flowing in the high pressure in the cavity After expelling the air inside the compact with high-pressure steam toward the other mold, promote internal heating, perform reverse-flow heating as necessary, promote internal fusion, and then close the steam outlets of both molds. That is, double-sided heating in which the surface of the foam molded body in the cavity is baked with steam having a pressure higher than that of flow heating.

In either method, high-temperature steam is passed between the pre-expanded particles in the cavity in the flow heating step to promote internal fusion of the molded body, and then both sides are heated with steam at a higher pressure than the flow heating. Then, the surface of the foamed molded body in the cavity is baked, so that the molded state of the surface of the molded body is excellently finished.

However, in these methods, high-pressure steam penetrates into the molded body due to the high vapor pressure when both sides are heated, and heating energy is trapped inside the molded body which is a heat insulating material. If the cooling in the mold is not performed sufficiently, there is a problem that the molded body is deformed. Therefore, in the heating method, although an excellent foam molded article can be produced, the cooling time becomes longer,
Therefore, there was a problem that the foam molding time was long.

The problem to be solved by the present invention is as follows.
An object of the present invention is to reduce the foam molding time by suppressing the surface pressure of the molded body.

[0008]

Accordingly, in the foam molding method of the present invention, the pre-expanded particles of the foamed resin are placed in the cavity 3 formed between the movable mold 1 and the fixed mold 2 whose molds are closed. 4 and high-temperature steam is passed through each of the movable mold 1 and the fixed mold 2 so that the high-temperature steam flows between the pre-expanded particles 4 in the cavity 3 at a high pressure after the completion of the mold heating. 0.8 ~ 1.0kg / c
At a vapor pressure of m ² , high-temperature steam is passed from one mold to the other mold for a predetermined time to carry out flow heating for rapidly foaming and forming the pre-expanded granules 4. Close the steam outlets 5 and 6 of both molds 1 and 2 and
A double-sided heating for baking the surface of the foam molded body in the cavity 3 with a vapor pressure of 4 to 0.5 kg / cm ² is performed. The technical means of;

[0009] Thus, there is no difference in heating energy between flow heating and double-side heating, and high energy does not penetrate, so that the surface pressure of the molded body does not increase, and the molded body in the mold does not rise. The cooling time can be greatly shortened, thereby shortening the foaming molding time.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a schematic cross-sectional view of a main part of a foam molding machine. A fixed die 2 is mounted on a fixed die plate 7, and a movable die plate 9 reciprocates on tie bars 8 attached to four corners of the fixed die plate 7. The movable die 1 is mounted on the movable die plate 9.

Further, a cylinder plate 10 is mounted on the end of the tie bar 8 at the back of the movable die 1, and the movable die plate 9 is moved together with the movable die 1 by a driving cylinder 11 mounted on the cylinder die plate 10. It is designed to reciprocate. A filler 12 for supplying the pre-expanded particles 4 to the cavity 3 is mounted on the back surface of the fixed mold 2, and a hopper storing the pre-expanded particles 4
13 is connected.

Next, the structure of the dies 1 and 2 will be described.
The molds 1 and 2 are the same on both the fixed side and the movable side.
The mold bodies 1a and 2a mounted on the mold 9, the male mold 1b and the female mold 2b constituting the cavity 3, and the hollow portions are steam chambers 1d and 2d. Drain pipes 5a and 6a having drain valves 5 and 6 serving as steam outlets are connected to each other. The female and male molds 1b, 2b are provided with a large number of steam ejection holes 1e, 2e, and the steam introduced into the dies 1, 2 passes through the steam ejection holes 1e, 2e into the cavity 3. It gushes (or passes).

The steam pipe 14 led out of the steam supply source 15 is branched into four pipes on the way, two of which are paired, each having a high-pressure steam valve 16a, 16b and a low-pressure steam valve 1 respectively.
7a and 17b are connected. At the outlets of the high-pressure steam valves 16a, 16b and the low-pressure steam valves 17a, 17b, the high-pressure steam valve 16a and the low-pressure steam valve 17
a are merged, connected to the branch pipe 14a, and connected to the male mold 1. On the other hand, the high-pressure steam valve 16b and the low-pressure steam valve 17b are merged and connected to the branch pipe 14b, and are connected to the female mold 2.

The branch pipe 14a is provided with a pressure gauge 18 for indicating the steam pressure in the steam chamber 1d. This pressure gauge
Reference numeral 18 is provided with a pressure setting device and functions to close the high-pressure steam valve 16a when the steam pressure in the steam chamber 1d reaches the set pressure.

The drive cylinder 11 is operated to close the mold with a gap between the molds 1 and 2 such that the pre-expanded granules 4 do not protrude, and the filler 12 is actuated into the cavity 3. The pre-expanded particles 4 of the foamed resin are filled. The pneumatic air flows out of the gap between the two dies.

The drain valve 5 of the movable mold 1 and the fixed mold 2
6 is opened, and both high-pressure steam valves 16a and 16b are opened to allow high-temperature steam to flow through the molds 1 and 2 at a large flow rate.
Heat the mold to discharge the air in d and 2d.

When the heating of the mold is completed, the drain valve 5 of the steam chamber 1d is closed, and the high-pressure steam valve 16a is fully opened with the drain valve 6 of the steam chamber 2d open (at this time, the other high-pressure steam valve 16b is A large amount of steam is allowed to flow from the steam chamber 1d through the gap of the pre-expanded particles 4 filled in the cavity 3 to the steam chamber 2d, and then discharged through the drain valve 6.

In accordance with the thermal expansion of the pre-expanded particles 4 in the cavity 2, the flowing steam pressure as a resistance when flowing through the steam chamber 1d increases, and the indicated value of the pressure gauge 18 with the contact also increases. Will come. When the flowing steam pressure reaches the set value of the pressure gauge 18, the pressure gauge 18 is operated, the high-pressure steam valve 16a is closed, and the flowing heating is completed. If necessary, reverse flow heating may be performed to complete the flow heating. In the present invention it is flowing vapor pressure above set higher, for example 0.8~1.0kg / cm ² (typically 1.0 kg / cm ² is used). Thereby, the pre-expanded particles 4
Heat is rapidly transmitted to the center of the steel to promote internal fusion.

When the flow heating is completed in this manner, the drain valve 6 which has been opened is also closed (the drain valve 5 is closed from the beginning), and both high-pressure steam valves 16a and 16b are closed. Instead, both of the low-pressure steam valves 17a and 17b are opened to heat the foam molded body 4a from both sides, and a double-side heating step of baking the surface of the foam molded body 4a is started. Sided steam chamber 1d, the vapor pressure of 2d when the heating 0.4~0.6kg / cm ² (typically 0.5 kg / cm ²
Degree). The heating time for double-sided heating is controlled by a timer. The double-sided heating promotes fusion of the surface of the molded body 4a. That is, although the temperatures of the molds 1 and 2 are heated by mold heating or flowing heating, since the temperature is lower than that of the molded body 4a, the surface of the molded body 4a is deprived of heat by the molds 1 and 2. , The fusion is slightly worse than inside. Thus, by the above-mentioned double-sided heating, the fusion of the surface of the molded body 4a is made almost the same as the fusion inside.

In other words, the reason why a small amount of low-pressure steam is supplied from both sides of the cavity in this double-sided heating step is that the compact inside the cavity has already been uniformly heated by the high-flow-rate high-pressure steam in the flow-through heating step. The foam fusion is almost complete,
Here, it is only necessary to adjust the heating non-uniformity of the surface portion near the cavity wall of the molded body, and it is only necessary to finish the appearance of the molded body. In this process, it is no longer necessary to provide a large amount of high-pressure steam from both sides of the cavity as in the past by the flow-through heating process, and instead, the molding surface pressure is increased and the next cooling cycle time is lengthened. It is disadvantageous just to put it away.

By the above two-sided heating method using low-pressure steam, the surface pressure of the foam to be expanded further at the final point of the foaming heating can be reduced as much as possible, and the cooling cycle time can be shortened. The method can be made much shorter than in the method described above.

After completion of such double-sided heating, a cooling device
(Not shown) to spray cooling water into both the dies 1 and 2 to rapidly cool the back surfaces of the male mold 1b and the female mold 2b constituting the cavity, and then cool by a vacuum device Promote.
When the cooling is completed, the mold is opened to take out the foamed molded foam 4a.

According to the method of the present invention, the internal fusion of the molded body in the cavity is completed by using high-pressure, large-flow steam during the flow heating, and then the double-sided heating is performed by the low-pressure steam. The surface pressure of the body can be reduced, and the cooling time in the mold can be shortened, so that the foaming molding time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a foam molding machine according to the present invention at the time of flowing heat.

[Explanation of symbols]

 1… Movable mold 1a… Mold body 1b… Male mold 1d… Movable steam chamber 1e… Steam jet small hole 2… Fixed mold 2a… Mold body 2b… Female mold 2d… Fixed steam chamber 2e… Steam jet Small holes 3 ... Cavities 4 ... Pre-expanded particles 5 ... Steam outlet (drain valve) 6 ... Steam outlet (drain valve)

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-60-116432 (JP, A) JP-A-63-21133 (JP, A) JP-A-3-23929 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B29C 44/00-44/60 B29C 67/20

Claims (1)

(57) [Claims] 1. A pre-expanded foam of foamed resin is filled in a cavity formed between a closed moving mold and a fixed mold, and high-temperature steam is passed through each of the moving mold and the fixed mold. Heating is performed so that high-temperature steam flows at high pressure between the pre-expanded particles in the cavity after the completion of mold heating.
High-temperature steam is allowed to flow from one mold to the other mold at a vapor pressure of 8 to 1.0 kg / cm ² for a predetermined time, and a flow heating for rapidly foaming and molding the pre-expanded particles is performed. After that, the steam outlets of both molds are closed, and a double-sided heating is performed to bake the surface of the foamed molded body in the cavity with a vapor pressure of 0.4 to 0.5 kg / cm ^2. .