JPS62216734A - Process for foam molding of thermoplastic resin - Google Patents

Abstract

PURPOSE:To attain the improvement of productivity, by applying a pulsation to a supplied steam with an on-off valve for pressure reducing operation provided at a steam supplying path to a chamber part in a male mold and a female mold. CONSTITUTION:In a molding process where a foamable thermoplastic resin particle is foamed to be welded under heating in a mold, an on-off valve 5 having a pressure controlling part 4 is set up as interposing in a steam supplying pipe 3. As the pressure controlling part 4, a diaphragm is used and is connected with a piping 6 as it is possible to introduce secondary steam from a male mold 1 and a female mold 2. An air source P is provided with a piping 7 for pressure controlling air and a piping 8 having a solenoid valve 9 and a pressure reducing valve 10 as for supplying an air for the on-off of the valve. The steam supplying pipe 3 is regulated over the range from full-opened state to full- enclosed state, and a steam supplied by the on-off valve 5 is applied with a pulsation at the time of aging and supplied to chamber parts 11, 21. Therewith the degassing of beads is made easy and also feed in under pressure of steam into the mold can quickly be performed, so productivity is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to manufacturing a foam molded product in a mold by controlling heating steam when molding a thermoplastic synthetic resin foam such as a plastic foam. The present invention relates to a foam molding method.

[Prior art]

To manufacture foam molded products, a mold is used to pre-foam expandable thermoplastic resin particles (beads), or they are filled into the mold without pre-foaming, heated and molded, and then cooled and released from the mold. Drying is common.

In this conventional foam molding, a steam chest method is often used in which beads are filled into a mold, heated with steam, foam molded, cooled with low-temperature cooling water such as tap water, and then released from the mold.

However, in foam molding equipment made using this method, the volume of the heating steam chamber is constant, so the steam temperature in the chamber is directly proportional to the tea pressure, so the steam pressure is adjusted to adjust the steam temperature. That is, in the conventional device, as shown in FIG. 3, two valves, an on-off valve device V1 and a pressure reducing valve device V, are arranged adjacent to each other in the cool air supply passage A, and accordingly, the pressure reducing valve device V2 is reduced in pressure. This is done with an adjustment nut B for adjusting the opening degree of the valve body.

[Problem that the invention seeks to solve]

However, when the steam pressure is adjusted by a valve device, the pressure regulating mechanism is kept constant, so only a constant amount of steam can be supplied at all times, and the heating molding cycle time including degassing of the raw material beads takes around 10 to 25 seconds. - Not only was there a limit for each cycle, making it impossible to increase productivity, but the positional relationship was inconvenient, making it difficult to adjust the steam supply.

The present invention aims to eliminate these conventional drawbacks by making it easier to degas the beads, significantly shortening the steam supply time, speeding up the molding operation, improving production efficiency, and making adjustment work easier. The purpose of the present invention is to provide a method that allows automatic adjustment without having to perform it every time, has an inexpensive structure without complicated restrictions in terms of equipment, and allows safe and stable foam molding work.

[Means for solving problems]

The present invention provides a foam molding method in which expandable thermoplastic resin particles are heated and foam-fused in a mold formed by a male mold and a female mold, in which a chamber portion in the male mold and the female mold is provided. This method of foam molding thermoplastic resin is characterized in that heated steam is supplied by applying pulsation to the steam supplied by an on-off valve that is interposed in a steam supply path and operated by reducing pressure.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.
Inner plate and chamber with ventilation holes1. ．． 2.
A mold is constituted by a pair of a male mold 1 and a female mold 2, which have frames that face each other so that they can be freely approached and separated so that a cavity is formed between the two molds 1. The chamber parts are each attached to the body! A steam supply pipe 3 for supplying heated steam from a heating steam source S to + and L is connected and provided, and an on-off valve is provided in the steam supply pipe 3 to the side of a pressure regulating section 4 that communicates with an air source P. 5 is interposed.

Further, the pressure regulating part 4 uses a diaphragm to form the male mold 1.
A pipe 6 is connected to introduce the secondary steam from the female mold 2, and a pressure regulating air pipe 7 is connected to the air source P.
A solenoid valve 9 and a piping 8 with a pressure reducing valve IO are provided for supplying valve opening/closing air, and the heating steam supply pipe 3 is adjusted from fully open to fully open, and the steam supplied by this opening/closing valve 5 is provided. During ripening, pulsation is applied to the chamber parts 11, 2. It is intended to be supplied to In this case, it is preferable to discharge pressurized air from a pneumatic device in accordance with the vapor pressure in the mold chamber, and in any case, the on-off valve 5 is operated using pressure-regulated air. Due to fluctuations in the air pressure balance between the valve opening/closing air regulated from the pressure reducing valve lO and the opening/closing solenoid valve 9 in the pressure regulating part 4 of the diaphragm 13, the secondary side steam communicated with the mold, and the pressure regulating air. However, this pulsation is not limited to one period such as during ripening, but may be applied separately at the beginning and end, or may be applied continuously.

As shown in FIG. 2, the opening/closing valve 5 has a valve body having an opening/closing part of a piston 12 by a single acting spring cylinder 11, and
It is equipped with a stopper valve/secondary side pressure regulating valve 14 which is integrated with a diaphragm 13 for regulating the pressure of the second side steam, and a constant pressure and a constant amount of air are supplied to the valve opening/closing rate 8. When the piston 12 is pushed up against the spring 15, the on-off valve 5 moves away from the valve seat 20, and the steam on the primary side flows into the mold through the steam supply pipe 3. When the secondary steam pressure in the mold is lower than the regulated air pressure, the on-off valve 5 is fully open, but as the secondary steam pressure approaches the regulated air pressure, the on-off valve 5 becomes fully open. Next side steam pressure,
The balance between the regulating air pressure and the valve opening/closing air pressure is lost, and the valve opening/closing air escapes from the exhaust hole 16 by the regulating valve 14 in the pressurized air flow passage 17 . As the amount of air escaping increases, the force pushing up the on-off valve 5 weakens, and the spring 15
Due to the force, the piston 12 descends and the on-off valve 5 lowers to restrict the flow of steam on the primary side, thereby regulating the steam pressure in the mold. At this time, the opening degree of the on-off valve 5 In order to introduce a large amount of steam (a large amount of heat), there is a time difference between the pressure inside the molds 1 and 2 and the pressure in the diaphragm 13 until they reach the same pressure. 2, the beads can be easily degassed, and steam can be quickly forced into the mold. In addition, when heating the mold 1.2, the on-off valve 5 is normally closed with the spring 5, but depending on the foam molded product, it may be necessary to open the on-off solenoid valve 9 and make the steam pressure pulsate. When there is no valve, the pressure of the valve opening/closing air can be set low using the pressure reducing valve 10 in the pipe 8 to prevent pulsation. However, the heating time will be slightly longer.

For example, the set pressure when pulsating is 3 to 4 k+r/c
Ill, but when not pulsating, 1.5 to 2.3
kg/-. Furthermore, when performing normal molding, it varies depending on the expansion ratio, but for example when the expansion ratio is 50 to 60 times, the steam pressure is often around 0.5 to 0.8 kg/cd, which is ± to the set value.
This is effective because it provides pulsation at around 0.15 kg/cd. Furthermore, the heating time was previously 15 seconds for the fixed side (female mold) and 10 seconds for the moving side (male mold), but now it can be shortened to 5 seconds for the fixed side and 4 seconds for the moving side. There is.

Although the exhaust hole 1G in the spring cylinder 11 is open to the atmosphere, it may be connected to a muffler or steam recycling mechanism.

Further, when the steam temperature (steam pressure) in the molds 1 and 2 decreases, the dungeon phragm 13 is pushed down by the pressure regulating air, and the pressurized air flow passage 17 is pushed down by the support shaft 22 of the dungeon phragm 13.
Press the regulating valve 14 located above to stop the pressurized air from flowing into the atmosphere. As a result, the air pressure below the piston 12 increases, the piston 12 rises against the spring 15, and the opening of the on-off valve 5 expands, allowing a larger amount of steam to flow from the heating steam source S into the chambers of the molds 1 and 2. ,,2. It can be supplied to

〔Effect of the invention〕

The present invention provides heated steam by supplying heated steam by giving pulsations to the steam supplied by an on-off valve that is operated by reducing pressure and is interposed in a steam supply path to a chamber part in a male mold and a female mold. The supply into the mold is carried out smoothly and reliably in a short period of time, and the degassing of the beads is also facilitated, greatly shortening the fusion molding cycle and significantly improving productivity.In addition, the temperature of the heating steam can be adjusted easily. It is easy to maintain, maintain, and secure, and has the effect that it can be configured as an inexpensive simple quiz.

[Brief explanation of drawings]

FIG. 1 is a system explanatory diagram of an embodiment of the present invention, FIG. 2 is a vertical sectional view of an on-off valve, and FIG. 3 is a system explanatory diagram of a conventional example. S...Steam source, P...Air source, 1...Male mold,
2... Female mold, 3... Steam supply pipe, 4... Pressure regulating section, 5... Opening/closing valve, 6... Secondary side steam piping, 7
...Pressure regulating air piping, 8...Valve opening/closing air piping. Patent applicant Yoshihiko Seki Patent attorney Yoshihiro Pharmacist Minoru Patent attorney Yori 1
) Takatsugu Department Patent Attorney Tadashi Takagi
Row figure 2

Claims (1)

[Scope of Claims] 1. A foam molding method in which expandable thermoplastic resin particles are heated and foam-fused in a mold formed by a male mold and a female mold, wherein the male mold and the female mold A method for foam molding thermoplastic resin, characterized in that heating steam is supplied by pulsating the steam supplied by an on-off valve that is interposed in a steam supply path to a chamber portion and operated by reducing pressure. 2. The opening/closing valve is operated by using a pressure regulating valve that can adjust the steam passage from fully open to fully closed using a pneumatic device, and by flowing pressurized air from the pneumatic device in accordance with the steam pressure in the mold chamber. A foam molding method according to claim 1. 3. The operation of the opening/closing valve is performed by pressure regulating air, and the valve opening/closing air regulated from the pressure reducing valve and the opening/closing solenoid valve is connected to the pressure regulating part of the diaphragm, and the secondary side is connected to the mold. The foam molding method according to claim 1 or 2, wherein the foam molding method is carried out by changing the air pressure balance between steam and pressure regulating air. 4. Any one of claims 1 to 3, wherein the steam supply step can be performed by setting a pulsating effect on the steam pressure using a pressure reducing valve that adjusts the pressure of valve opening/closing air. Foam molding method described.