JPS6252685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method and apparatus for maintaining a powder or pellet-like molding material at a constant temperature before supplying it to an extruder for molding, and supplying the material to an extruder. It is related to.

When molding a material into a product with a certain shape, the material is heated and melted in an extruder prior to extrusion molding, but fluctuations in the melting position of the material within the extruder have a great effect on the quality of the product. For example, when a compound of synthetic resin, particularly thermoplastic resin, is fed into an extruder, the compound rises in temperature under a certain temperature gradient within the extruder, reaches a melting temperature at a certain point, and is melted and molded. However, if the temperature of the supplied compound is not constant, the melting position will also shift, causing unevenness in the amount of melt extruded during molding, and having a negative impact on the quality of the molded product.

Therefore, conventional attempts have been made to maintain the material at a uniform temperature by leaving the material in a constant temperature room for a long time, or by putting the material into a container at a constant temperature and stirring it with a blade or the like. However, in the former case, it takes an extremely long time for the temperature of the material to stabilize at a certain set value, and this tendency is particularly noticeable in thermoplastic resins because of their low thermal conductivity. In addition, in the latter method, since the material is stirred under pressure, air bubbles are removed from the material and the mixed state and density become uneven, resulting in an adverse effect during molding, which is preferable. It cannot be called a method.

The present invention solves the above-mentioned conventional drawbacks and allows the material to be transferred to the extruder without applying pressure.
The object of the present invention is to provide a method and apparatus for maintaining the temperature at a constant temperature and supplying the same to the extruder.

The present invention has a device in which a powder or pellet-like molding material is transferred and supplied from a material feeding device to an extruder by a pressurized air flow in a transfer tube, in which the transfer tube is a heat medium kept at a constant temperature. A method and apparatus for supplying a material to an extruder at a constant temperature by penetrating a fillable closed container and performing heat exchange between the material and a heat medium, and as a result, a good molded product with a uniform and stable molten state is provided. It was designed so that it could be obtained.

The embodiments shown in the drawings will be described below. 1 is a tank in which material 11 is stored at room temperature. 2 is a material feeding device that connects the tank 1 and pipe 1 through a valve 12 that adjusts the supply amount.
Connected by 3. A drive source for feeding the material 11, such as a compressed air intake pipe 21 that takes in compressed air, is connected to the material delivery device 2 via a valve 22 that adjusts the amount of air. A transfer pipe 3 for transferring the material is connected to the lower part of the material delivery device 2, and the transfer pipe 3 passes through a closed container 4 to transfer the material 11 to a hopper 5 where it is temporarily stored in preparation for supply to the extruder 6. connected. The hopper 5 is connected to supply the material to the extruder 6. The extruder 6 has a heating section (not shown) that heats and melts the material before the extrusion molding process, and is equipped with a die at its outlet for extruding and molding the melt.

To explain the sealed container 4 in more detail, the container is filled with and sealed with a heat medium 45.
This heat medium 45 performs heat exchange by flowing a heat supply fluid, such as hot water or steam, through pipes 41 and 42 connected to the closed container 4.
It is always kept at a constant temperature. Here, it is also possible to use the heat medium itself as the heat supply fluid. Further, in the above description, a heat supply fluid was used as an example for heating the material, but when it is necessary to cool the material and maintain a constant temperature, cold water or the like is used. The heat supply fluid is circulated by a pump 46. The closed container 4 is further equipped with a temperature control device 43 for controlling the opening degree of a valve 44 that detects the temperature of the heat medium 45 and adjusts the supply amount of the heat supply fluid to keep the temperature constant. There is.

In another embodiment, it is preferable that the transfer tube 3 is spirally wound in order to minimize the space volume within the closed container 4 (spiral portion 31). In order to meet this requirement, the closed container 4 would have a cylindrical shape. Furthermore, the heat medium 45
When the heat capacity is high, the amount of the heat medium 45 is small, so in such a case, the closed container 4 may be a hollow double cylinder that accommodates the spirally wound transfer pipe. can.

Next, a description will be given of how the above device supplies the material to the extruder at a constant temperature. There are various materials melted here depending on the molded product, but
As mentioned above, it is a material (powder-like or pellet-like) whose quality of molded products is affected by temperature changes before melting, and is particularly effective for thermoplastic resins and thermoplastic resin compounds.

First, the material 11 enters the material delivery device 2 with the amount set appropriately by the valve 12, and then passes through the transfer pipe 3.
A closed container 4 is sent out by a pressurized air flow flowing through
pass through the inside. When passing through the container 4, the material exchanges heat with the heating medium 45 through contact between the transfer pipe 3 and the heating medium 45, so that when it leaves the closed container 4, it has almost reached the temperature of the heating medium. There is. Moreover, since the heat medium 45 is always kept at a constant temperature by the temperature control device 43, the material is also kept at a constant temperature. After that, the material is Hopper 5.
It is then fed to the extruder.

As described above, in the present invention, the temperature of the material is kept constant before it is fed to the extruder for molding, so the melting position of the material within the extrusion device is reliably fixed, and the product after molding is It has become possible to improve the quality and ensure its uniformity.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. 2...Material sending device, 3...Transfer pipe, 4...
... airtight container, 45 ... heat medium, 6 ... extruder.

Claims (1)

[Claims] 1. Before the extrusion process, the thermoplastic resin material to be extruded is passed through a transfer pipe that passes through a closed container filled with a heating medium kept at a constant temperature, together with a flow of pressurized air. A method in which the molding material is fed to an extruder at a constant temperature. 2. Claim 1, wherein the thermoplastic resin material is a thermoplastic resin compound.
A method of feeding the molding material described in Section 1 to an extruder at a constant temperature. 3. A method for feeding a molding material according to claim 1 or 2 to an extruder at a constant temperature, wherein the thermoplastic resin material is in the form of powder. 4. A method for feeding a molding material according to claim 1 or 2 to an extruder at a constant temperature, wherein the thermoplastic resin material is in the form of pellets. 5 In a device having a transfer pipe for transferring and supplying the material from a thermoplastic resin material delivery device to an extruder using a pressurized air flow, the transfer pipe 3 is a closed container filled with a heat medium 45 maintained at a constant temperature. 4. A device for feeding a molding material to an extruder at a constant temperature. 6. An apparatus for feeding a molding material to an extruder at a constant temperature according to claim 5, wherein the transfer pipe 3 is spirally wound within a closed container 4. 7. An apparatus for feeding a molding material to an extruder at a constant temperature according to claim 5 or 6, wherein the closed container 4 is a cylindrical body. 8. An apparatus for supplying a molding material to an extruder at a constant temperature as set forth in claim 7, wherein the closed container 4 is a hollow double cylindrical body housing a spirally wound transfer tube 3. .