JPS59182719A - Saving method of steam in expansion molding machine - Google Patents

Abstract

PURPOSE:To save the amount of steam for heating during expansion molding period as well as shorten the time of heating by reducing the discharge amount of drain by adjusting the opening of the drain valve of the molding machine in molding a thermoplastic resin by one-side heat expansion. CONSTITUTION:For example, a steam valve 10 on the cavity side is opened, a steam valve 11 on the core side is closed, a drain valve 12 on the cavity side is closed, a drain valve 13 on the core side is opened, and a small drain valve 19 is opened to start up one-side heating operation. The air in the cavity side steam chamber 1, an expandible thermoplastic resin 5, e.g., expandible styrene, etc., and the core side steam chamber 3 is replaced by steam and drain discharge in the early period is finished. Afterwards, the core side drain valve 13 is closed, only the samll drain valve 19 is opened, the opening of the drain valve is adjusted to reduce the discharge amount of drain, and one-side heating is further made. The adjustment of the opening of the drain valve is preferably made only after the ending of degassing during the one-side heating period.

Description

DETAILED DESCRIPTION OF THE INVENTION The purpose of the present invention is to adjust the discharge area of the drain valve to remove waste steam that has conventionally been discharged outside the system at the stage of one-sided thermal operation in a foaming thermoplastic resin molding machine. J Concerning a Method for Reducing the Amount of Steam Used for Heating by Limiting the Emissions of Waste Steam by Reducing the Volume of Waste Steam This steam passes through the cavity steam chamber (1), the cavity mold (2), the expanded polystyrene (5), the core side mold (4), the core side steam chamber (3), and then the core side drain valve ( 18). This operation performs internal fusion by passing steam through the interior of the expanded polystyrene.

If this steam ventilation is not carried out sufficiently, sufficient internal fusion will not occur and the product quality of the foamed polynucleotide molded product will be degraded. On the other hand, in the process of performing angular heating operations, excess steam, condensate and air are discharged together. The cabin side steam and chamber steam pressure are used as a measure to determine the standard for internal fusion of expanded polystyrene, and specifically, the setting value of the cabin side pressure switch (6) is, for example, 0, 4.
kq/(zf When G is reached, an electric signal is output from here and the steam valve α0 on the side of the cabin is closed, the steam supply is stopped, and the heating operation ends.On the other hand, in an attempt to save excess steam in the case of angular heating, Even if the amount of steam supplied is reduced by the method such as (8) for regulating the pressure on the cavity side, the heating time will be extended, and as a result, the effect of saving excess steam will not be obtained.

In one heating operation of the present invention, the method for saving excess steam is as follows.

On the steam supply side, the cab side steam valve 00 is open, the core side steam valve (11) is closed, and on the drain valve side, the cab side drain valve (increase is closed, the core side drain valve θ is open, and the small drain valve is closed). 09) starts the heating operation while it is in the open state. The air in the cab side steam chamber, foamed polystyrene (5), and core side steam chamber is replaced with steam, and after the initial drainage is completed, the core side drain valve θ3) is closed and the small drain valve ◇9) is open. One-sided heating operation is performed at , and one-sided heating operation is completed when the set value of the cavity side pressure switch is reached.

In the above operation, it is preferable that the core side drain valve is open for 2 to 5 seconds, and then, after closing the drain valve, the small drain valve is used while being opened and heated. For small drain valves, 10 to 30% of the cross-sectional area of the core side drain valve is preferred.

In this way, as a method to reduce the cross-sectional area of the drain valve, instead of providing a separate small drain valve, the core-side drain valve has the function of reducing the cross-sectional area by adjusting its opening degree. You can achieve your goals.

The opening adjustment drain valve may be installed on the cavity side, on the core side, or on either side. As this valve, a known manual or automatic control valve is used.

- For example, first, the core side percutaneous adjustment discharge valve (2o) is fully opened, heating is started, the air in the mold is replaced with steam, and the initial drain is discharged (the timing for fully opening the discharge valve is 2 to 5 seconds), the core side opening degree adjusting discharge valve (2o) has an opening degree of 10-3Q% of the fully open position, and performs one-sided thermal operation.

In the one-sided heating operation described above, heating is performed by supplying steam from the cavity side, but heating may be performed from the opposite direction, that is, from the core side.

The diameter of the drain valve varies depending on the mold used, but an appropriate diameter can be determined based on past experience.

Therefore, if you use only a small drain valve instead of the conventional drain valve or reduce the opening of the discharge valve, the problem may occur due to insufficient discharge capacity of the filled air when filling the foamed thermoplastic resin. It is preferable to adjust or reduce the opening degree of the drain valve only after completion of degassing during heating, since this may cause problems such as insufficient filling and prolonged draining time due to insufficient cooling and draining capacity.

On the other hand, the second case when the opening degree of the drain valve is decreased during heating.
The effect of this is that as the steam pressure inside the mold increases, the steam heating temperature increases and the heating time is shortened.

The method of the present invention can be suitably applied to thermoplastic resins, especially expanded polystyrene. Examples will be described below. The preferred opening degree when decreasing the opening degree of the drain valve is based on the following experiment.
It can be seen that 10 to 30% when fully opened is good.

Example 1 Raw materials used; expanded polystyrene density 0.021/cc
Molded object dimensions; External dimensions = 510X295X85 Inner dimensions =
474' x 258 2G cavity side pressure regulating valve setting value; Q, 7 kq/cyn The table below shows the results when the opening degree of the 2G drain valve was changed as shown in the table below and when the core side drain valve was fully opened.

Note) Opening degree is the area percentage when the opening degree is decreased compared to fully open.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a mold, a steam system, and a drain valve system in a foam molding machine according to the present invention. 1...Cabi side steam chamber 2...Cabi side mold 3...
・Core side steam chamber 4...Core side mold 5...Polystyrene foam 6...Cabiside pressure switch 7...Core side pressure switch 8...Cabiside pressure regulation J"9...
Core side pressure regulating valve 10...cabin side steam valve 11...
Core side steam valve 12...cabin side opening adjustment valve 13.
... Core side drain valve 14 ... High pressure steam pipe 15 ...
・Cabi side steam pipe 16... Core (ltlli trachea 1
7...Cabi side drain pipe 1B...Core side drain pipe
19...Small) Run Valve 20...Core Side Intensity Adjustment Valve Patent Applicant Kanebuchi Chemical Industry Co., Ltd. Representative Patent Attorney Makoto Asano

Claims (1)

[Scope of Claims] 1. A method for saving steam in a foam molding machine, which comprises adjusting and reducing the opening degree of a drain valve used for drain discharge in one heating step in in-mold foam molding of thermoplastic resin. . 2. A claim that adopts the process of adjusting and reducing the opening degree of the drain valve and then heating the drain valve after the drain valve is fully opened and steam is heated to replace the air in the mold with steam. Steam saving method described in paragraph 1. 6. The steam saving method according to claim 1, wherein the drain valve is fully opened and steam is heated for 2 to 5 seconds, and then the opening degree of the drain valve is reduced to 10 to 30%.