JPH01297226A - Melting plasticizing apparatus - Google Patents

Abstract

PURPOSE:To simply and arbitrarily control the feed amount of a resin raw material, by providing a fluidized bed heating apparatus, which is internally equipped with a revolving endless belt constituted of an air permeable member and heats a raw material resin while allows the same to move on said belt in a laminar state, so as to connect the same to the raw material supply part of a melting plasticizing apparatus. CONSTITUTION:A blower 26 sucks the air of a heating tank 20 from a duct 24a and said air is heated to predetermined temp. by a heater 25 to be blown in the heating tank 20 from a duct 24b to be recirculated. The air blown in the heating tank 20 is blown up through the holes of multistage diffusion plate conveyors 28, 28... and the pellets R on said conveyors are brought to a fluidized state to be heated rapidly. A rotary valve 31 is rotated at the pellet downstream end part of each conveyor 28 in synchronous relation to the conveyor 28 and allowed to intermittently fall to improve the dispersion of the pellets R on the next stage conveyor and the passing property of hot air is secured and, at the same time, the hot air is prevented from bypassing from the end part of the conveyor belt. The pellets R fluidized on each dispersion plate conveyor to be heated to predetermined temp. enter a melting plasticizing apparatus main body 100 to be melted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for melting and plasticizing thermoplastics, which is applied to extruders, injection molding machines, and the like.

(Prior art) In order to preheat the raw material resin supplied to the melting and plasticizing equipment,
Conventionally, a packed bed type heating device as shown in FIG. 2 is installed separately from the melting and plasticizing device, and both are used off-line.

However, in rare cases, it is directly connected to the melt-plasticizing apparatus, but in general, means such as air transport are used to transfer the heated raw resin in batches to the main body of the melt-plasticizing apparatus.

That is, in FIG. 2, 1 is a filling tank, and hot air heated by a heat exchanger 5 is blown out from a distribution duct 2 at the bottom of the filling tank 1 by a fan 6, passing between the resin particles filled inside, and discharging the resin particles. Heat.

After heating the resin particles, hot air is supplied to the fan 6 from above the filling tank 1.
is sucked into and circulated. The hot air temperature at this time is controlled by detecting the hot air temperature at the outlet of the heat exchanger 5 with a temperature sensor 7, and controlling the heat exchanger temperature via the temperature adjustment device 8 and the heater power supply circuit.

The heated raw material resin is discharged through the valve 3. The problem with this type of heating device is that the discharge state of the resin in the tank cannot always be maintained constant, and therefore the residence time is uneven, so it is difficult to maintain a constant temperature distribution of the resin particles. This is difficult and requires long heating to keep the temperature of the resin particles constant. This is also one of the reasons why the heating device cannot be installed in-line.

In addition, since the heating time is unavoidable as described above, if the heating temperature is high, the resin particles in the filling tank will stick to each other, and the whole will harden into a candy shape, resulting in melting and plasticity. There is also the problem that the converting device itself cannot be fed smoothly.

However, if the apparatus can be operated under normal conditions, the capacity of the melt plasticizing apparatus can be increased by 20 to 30% by heating the resin particles in the filling tank.

Therefore, a melt plasticizer as shown in Fig. 3 was developed to take advantage of the advantages of supplying heated raw material resin to the melt plasticizer and to solve the above problems. It has already been proposed in No. 62-51498.

This device is a melting and plasticizing device that is integrally equipped with a fluidized bed heating device that heats the raw material resin while flowing it in layers, and the resin pellet R in the hopper 11 is driven by a variable speed motor 13. A desired amount is supplied into the fluidized bed heating tank by a metering feeder 12. The supplied resin pellet R is rotatable by hinges 19, 19, .
・Flows stepwise in layers from the top to the bottom and reaches the raw resin inlet of the melting plasticizer main body. While flowing, the hot air heated by the heat exchanger 5 is supplied into the fluidized bed heating tank through the duct 4 by the fan 6, and is supplied to each distribution plate 18.
a, 18b-, it flows upward while heating the resin belen) R, and circulates through the duct 4 from the return air hole 40.

Note that 7 is a hot air temperature sensor, and 8 is a temperature adjustment device.

That is, the heating device shown in FIG. 3 includes dispersion plates 18a, 18b,
・This is intended to continuously heat and transport the resin pellets (R) in a layered manner by tilting the -.

However, in the case of this equipment, the relationship between the amount of resin conveyed and the inclination angle of the dispersion plate is delicate, and when the amount of heated and melted resin is changed frequently (this condition is common in resin melting and plasticizing equipment). ), it would take a long time to set the inclination angle of the dispersion plate so as to obtain a predetermined conveyance amount while maintaining good flow conditions. Furthermore, when the operation is stopped, a small amount of pellets remains on the dispersion plate, which requires time to clean.

Therefore, although this device can be applied to large-scale film manufacturing equipment, it is not suitable for heating and plasticizing equipment where the melting amount and pellet type are changed frequently, and other measures are required.

(Problems to be Solved by the Invention) The fluidized bed heating device using the inclined dispersion plate shown in FIG.
Compared to the conventional general packed bed heating method shown in the figure, higher temperature heating is possible; for example, in the case of polypropylene resin, the packed bed method can heat 80 to 90 degrees Celsius, while the fluidized bed method can heat the material to 150 to 90 degrees Celsius.
It is possible to heat up to 160°C, and the heating time is short, which has great advantages. However, as mentioned above, there remains a disadvantage that it is difficult to adjust the inclination angle of the distribution plate according to the amount of heating.

Therefore, the present invention has been made to improve this point, and aims to provide a melting and plasticizing device equipped with a fluidized bed heating device that allows the conveyance amount of the resin raw material to be easily and arbitrarily adjusted. It is.

(Means for Solving the Problems) For this reason, the present invention provides a thermoplastic plastic melting and plasticizing apparatus that is equipped with a rotatable endless belt made of a ventilated member, and the raw resin is layered on the belt. A fluidized bed heating device that heats while moving is connected to a raw material supply section of the melting and plasticizing device main body, and this is a means for solving the above problem.

That is, the present invention is to convert the distribution plate in the previously proposed fluidized bed heating device into a belt conveyor.

Furthermore, in addition to the above configuration, a rotary valve with vanes that rotates in synchronization with the belt speed may be installed near the raw material discharge end of the conveyor, and if necessary, the accumulation of resin on the conveyor can be monitored using light transmittance. etc. to control the belt speed of the conveyor and the rotation speed of the rotary valve.

(Function) (1) When changing the fluidized bed dispersion plate from a simple flat plate to a conveyor belt and changing the supply amount of resin pellets,
By simply setting the belt speed to the optimum speed, the transfer amount can be easily changed while maintaining a good flow state of the raw material resin.

Additionally, even when the conveyor belt is stopped, all pellets can be discharged without remaining on the conveyor belt, eliminating the need for cleaning.

(2) An endless belt conveyor is used instead of a simple perforated inclined plate for the distribution plate, which increases the resistance of the distribution plate, making it difficult for hot air to pass through the conveyor, and the amount of air that blows around it and passes through the conveyor. However, by installing a roll valve at the conveyor outlet, a predetermined amount of pellets are intermittently dropped onto the lower conveyor, allowing hot air to pass through the conveyor effectively, and reducing hot air from around the conveyor. Improve energy efficiency by preventing blow-throughs.

(3) Furthermore, if a transmitted light detection sensor is provided on the conveyor, the conveyor speed can be automatically adjusted based on the detection sensor signal, and the amount of transmitted light can be controlled to be the same as in a good conveyance state. Therefore, manual adjustment of the conveyor is not required, and operation can be simplified.

(Example) Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a typical embodiment of the present invention, in which a fluidized bed heating device according to the present embodiment is connected to a raw resin inlet of a main body 100 of the melting and plasticizing apparatus.

In the figure, reference numeral 20 denotes a heating tank, and a raw material discharge port provided at the bottom of the heating tank communicates with a raw resin input port of the melting and plasticizing apparatus main body 100. At the top of the heating tank 20, a feeding hopper 21 for pellets R is provided with a feeder 22 driven by a variable speed motor 23 in between. (referred to as a plate conveyor) 28, 28... are arranged in the vertical direction, and each conveyor 28, 28- is driven by a variable speed motor 29.
It is driven by and rotates.

The distribution plate conveyor 28 is composed of a flexible perforated plate or a suitable mesh net. Further, the belt speed is adjusted by changing the rotation of each variable speed motor 29, 29-, based on a command from the motor rotation adjustment device 34.

At the downstream end of the pellet of each distribution plate conveyor 28, 28, a rotary valve 31, 31, having a desired number of blades is attached.
- is provided with its rotation axis parallel to the width direction of the distribution plate conveyor 28, 28-. This low revalve 31.31
- rotate in synchronism with the belt speed of the distribution plate conveyor 28, 28-, respectively. Moreover, light transmission sensors 32, 32- are provided at the upper part of the downstream side of the pellet of each dispersion plate conveyor 28, 28-.

In addition, in the figure, 24a is a duct connected to the return air hole 30 formed in the upper part of the heating tank 20, 24b is a duct connected to the lower part of the heating tank 20, and a blower 2 is installed between each duct.
6. A heater 25 and a temperature sensor 27 are installed to form a hot air circulation path, and the temperature sensor 27 is connected to a temperature adjustment device. These parts are substantially the same as the corresponding parts of the melt plasticizing apparatus shown in FIG. 3 and previously proposed.

In the above configuration, the resin pellets R in the hopper 21 are conveyed by the feeder 22 driven by the variable speed motor 23 and fall onto the ventilation-enabled uppermost distribution plate conveyor 28 which is rotationally driven by the variable speed motor 29.

On the other hand, the blower 26 blows the air inside the heating tank 20 into the duct 24a.
It is heated to a predetermined temperature with the heater 25, and then the duct 2
It is blown into the heating tank 20 from 4b and circulated. The air blown into the heating tank 20 blows up through the holes of the multi-stage distribution plate conveyor 28, 28, etc., and turns the pellets on the conveyor into a fluid state and rapidly heats them. A rotary valve 3 is installed at the downstream end of each conveyor 28.
1 rotates in synchronization with the conveyor 28, and the pellet R
The pellet R on the next conveyor is dropped intermittently.
At the same time, it ensures good dispersion of hot air and ensures the passage of hot air.
Prevents hot air from bypassing the ends of the conveyor belt.

The light j3 excess sensor 32 installed at the top of each dispersion plate conveyor 28, 28- can determine the flow situation based on the amount of light transmitted. Based on the sensor output, for example, if the amount of transmitted light is small and the amount of pellets is excessive, The conveyor speed can be automatically adjusted to increase the conveyor speed and decrease the conveyor speed when the permeation amount is high and the pellet amount is too low.

The pellet R, which flows on the distribution plate conveyor and rises to a predetermined temperature, enters the melting plasticizer main body 100 and is melted. In the illustrated example, the distribution plate conveyor 28 is provided in three stages, but the conveyor may be provided in one or more stages.

(Effects of the Invention) As described above in detail, according to the present invention, the raw material resin is preheated in a fluidized bed state before being introduced into the plasticizing device main body, so energy efficiency is improved and the heating device is in-line. In particular, since the pellets are flowed on a ventilated belt conveyor inside the heating tank, it is easy to adjust the operation when changing the pellet heating conditions, and even at the end of the work. Since no pellets remain in the heating tank, there is no need for cleaning, resulting in extremely excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a side cross-sectional view schematically showing a melting and plasticizing device equipped with a fluidized bed pellet heating device, which is a typical embodiment of the present invention, and Fig. 2 is a conventional packed bed pellet heating device and plasticizing device. FIG. 3 is a schematic side sectional view of a melt plasticizing apparatus equipped with a fluidized bed pellet heating apparatus proposed previously. Explanation of main parts of the diagram 2〇-Heating tank 25--Heater 26--Blower 27-Hot air temperature sensor 28--Dispersion plate conveyor 29--Variable speed motor 30-Return air hole 31-Roke valve 32- Light transmission sensor 34...-Motor rotation adjustment device 100--Melting plasticizing device main body! A1 Figure Moon 2 Figure 3

Claims (1)

[Claims] In thermoplastic plastic melting and plasticizing equipment, the main body of the melting and plasticizing equipment is equipped with a rotating endless belt made of ventilated members, and a fluidized bed heating device that heats the raw resin while moving it in layers on the belt. A melt plasticizing device characterized in that it is connected to a raw material supply section.