JPS5850182B2 - Drain removal device for pre-foaming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for eliminating the drain of a foaming chamber in a pre-foaming device for foamable thermoplastic synthetic resin particles.

Conventionally, heated steam is ejected from the bottom of the foaming tank to foam the foamable resin particles introduced into the foaming chamber, and some of the steam ejected from the bottom plate of the foaming tank condenses and accumulates on the bottom plate, causing it to eject from the bottom plate. There was a problem that a boiling state was formed around the pores and the particles were moistened.

An object of the present invention is to provide an apparatus that can eliminate drain accumulated on the bottom plate of a foaming tank and prevent moisture from adhering to resin particles.

In the following explanation, steam is used as the heating medium, but
Of course, heated air, hot water, etc. can also be used in the same way.

The expandable thermoplastic resin particles in the present invention include, for example, polystyrene, styrene and a-methylstyrene,
Particles of thermoplastic resins such as copolymers with chlorostyrene, acrylonitrile, acrylic acid, etc., polyolefins such as polyethylene and polypropylene, aliphatic hydrocarbons such as propane, butane, pentane, and hexane, and methyl chloride, dichloromethane, etc. It contains a blowing agent such as an aliphatic halogenated hydrocarbon such as chlorodifluoromethane.

In addition, the shape of the particles can be any shape, but
In particular, spherical ones are most preferably used.

The drawing shows, as an example, a situation in which the present invention is implemented in a pre-foaming device in which a certain amount of particles are put into a foaming tank, foamed, and then taken out. A constant weight is measured by a measuring device 12, and the foam is introduced from the upper part of the foaming tank 18 through the inlet 14 by the air cylinder 16.

The foaming tank 18 has a straight cylindrical shape and has an outlet 20 at its lower part, a lid 22 is pivotally fixed to the upper part of the outlet, and the iron lid 22 is connected to an air cylinder 24 to be opened and closed.

Further, a motor 26 is installed on the upper part of the foaming tank 18, and a rotating shaft 28 connected to the motor is suspended in the center of the foaming tank 18, and is extended and supported to the bottom plate 38 of the tank.

Stirring blades 30 are protruded in multiple stages from the rotating shaft 28, and fixed blades 32 are protruded from the wall of the foaming tank 18 toward the middle height of the stirring blades 30 to stir the foamed particles inside and remove the lumps. Trying to prevent formation.

Inside the foaming tank 18, a phototube, a microsinch, etc. are used to detect the presence of the foam layer at a position corresponding to the upper surface of the foam layer when a fixed amount of particles are expanded to a set expansion ratio, and the heating medium is ejected. A first detector 78 for stopping the heating medium and a second detector 80 for reducing the bubbling speed by reducing the ejection amount of the heating medium are installed slightly below the first detector 78.
．． 80 is installed so that its height can be adjusted on the wall of the foaming chamber, so that it can respond to changes in the foaming ratio and foaming capacity settings.

An exhaust port 34 is provided at the top of the foaming tank 18, and an exhaust floor is installed.
etc. are connected to exhaust the volatile gas generated inside the foaming tank and circulate the air to prevent condensation inside the foaming tank and to minimize the temperature difference in the steam between the lower and upper parts. It's getting smaller.

On the bottom plate 38 of the foaming tank, a perforated plate 41 having a slit-shaped spout 40 is disposed as shown in FIG.
It communicates with a steam chamber 42 located at the bottom.

A first steam nozzle 44 and a second steam nozzle 46 are installed in the steam chamber 42 and are connected to a main steam pipe 58 via steam pipes 48 and 50, respectively.
have a gauge 52, a throttle valve 54, and an on-off valve 56 and 57, respectively.
The on-off valve 56 of the first steam pipe 48 is connected to the first detector 7.
The opening and closing valve 5 of the second steam pipe 50 is controlled to open and close in conjunction with the valve 5 of the second steam pipe 50.
7 is connected to the second detector 80 and controlled to open and close.

Therefore, when the foam layer rises and reaches the second detector 80, the on-off valve 57 is activated to stop the steam jetting from the second steam nozzle 46, and then when the foam layer reaches the first detector 78, the on-off valve 57 is activated. This stops the steam from being ejected from the first steam nozzle 44.

Furthermore, a drain pipe 60 is connected to the lower part of the steam chamber 42 to discharge the drain accumulated in the steam chamber 42, and an air nozzle 62 is installed in the steam chamber 42, and an air pipe 64 is connected to the nozzle 6.
2, and an air supply device 68 such as an air compressor is provided upstream of the air pipe 64 via a valve 66 so as to blow air into the steam chamber 42 from small holes opened along the entire length of the air nozzle 62. Eggplant.

A plurality of drain plates 70 each having a drain lower 2 are further provided around the bottom plate 38, and each drain plate 70 is provided with a drain chamber 74 at the lower part of the bottom plate, and the drain collected on the bottom plate 38 is drained from the drain plate. 70, the water is discharged to the outside through a drain pipe 76.

First, a certain weight of foamed particles is introduced from the inlet 14, and the agitating blades 30 agitate the particles by the rotation of the rotating shaft 28. At the same time, compressed air is ejected from the air nozzle 62, and the air is ejected from the air outlet 4o of the perforated plate 41. Air is circulated within the foaming chamber through this process.

When flowing into the two steam pipes 48 and 50, a mixed flow of a large amount of steam and air from the air nozzle 62 is ejected into the foaming chamber, passes through the gaps between the particles, and flows upward while rapidly heating the particles. , and are attracted to the exhaust device 36 and discharged outside.

Particles in the foaming chamber begin to heat and foam due to the flow of steam,
Rapid foaming and expansion is carried out while being stirred by stirring blades 30 and fixed blades 32, and the upper surface of the foam layer gradually rises within the foaming chamber.

At this time, the foamed layer is constantly stirred by the fixed blades 32 and the stirring blades 30 rotating at about 7 rpm, so that the formation of lumps can be almost completely prevented.

Furthermore, even if steam condenses in the foaming chamber and generates moisture, the air ejected from the air nozzle 62 flows upward within the foaming chamber and is discharged from the exhaust port, so no moisture remains in the foaming chamber. This can be prevented, and since there is always a flow of steam, the temperature difference between the lower and upper parts of the foaming chamber is about 1°C, and uneven heating hardly occurs.

Further, the condensed water generated on the upper surface of the perforated plate 41 is removed by the stirring blade 3.
As the foamed particles move toward the outer periphery due to the centrifugal force generated by the zero rotation, they collect on the outer periphery and are forcibly discharged from the drain lower 2 to the drain chamber 74, preventing moisture from accumulating on the perforated plate 41. It is prevented.

The amount of steam ejected can also be similarly controlled by half-closing the on-off valve of one or more steam nozzles by the operation of the second detector 80 and fully closing by the operation of the first detector 78. It can be implemented.

Furthermore, it is possible to leave the first detector 78 and omit the second detector 80. In this case, the foam layer rapidly expands to the height of the first detector 78, and the detector 78 is activated. When the on-off valves 56 and 57 are closed all at once, and the steam stops, the steam expands in an inertial manner and gradually attenuates until it stops.

However, since the time from when the steam supply stops until the foaming stops is determined experimentally to be approximately constant, if the height of the first detector 78 is set appropriately, the particles can be foamed to the set foaming ratio. .

As described above, the present invention removes the drain generated on the bottom plate of the foaming chamber from the drain lower 2 to the drain chamber 74 below, so that it is possible to prevent moisture from adhering to the surface of the foamed particles, and to prevent the particles from forming inside the foaming chamber. Blocking does not occur and smooth foaming work is possible.

In addition, the drain chamber 74 communicating with the drain lower 2 is independent from the steam chamber 42, and even if steam is spouted from the steam chamber 42 into the foaming tank 18, it does not interfere with dripping of condensed water into the drain chamber. etc., have excellent effects.

It has many excellent advantages.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of the device used to carry out the present invention, Figure 2 is a cross-sectional view taken along the line ■-■ in Figure 1, and Figure 3 is an enlarged view of part (3) in Figure 1. be. 14... Input port, 18... Foaming tank, 2
0... Outlet, 38... Bottom plate, 40.
...Ejection port, 41...Perforated plate, 42.-
...Steam room, 70...Drain plate, 72.
...Drain port, 74...Drain room.

Claims (1)

[Claims] 1. A pre-foaming device with a built-in stirring device, an inlet for foamable thermoplastic resin particles at the top, an outlet at the bottom, and a steam chamber into which the heating medium flows below a bottom plate with a heating medium jet port. A drain removal device for a pre-foaming device, wherein a drain port is provided on the outer periphery of the bottom plate of the foaming chamber, and the drain port communicates with a drain chamber independent of the steam chamber.