JP2006181903A - Heating block, temperature controlling device and manufacturing method of plasticized resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating block easy to meet explosion proofness specifications, good in maintainability and substantially applicable to even a twin screw extruder, to provide a temperature controlling device good in heat responsive characteristics in controlling the temperature of an extruder, and to provide a manufacturing method of a plasticized resin. <P>SOLUTION: In the heating blocks which heat a plurality of cylinder blocks which constitute the cylinder of an extruder which holds a screw inside and kneads/plasticizes a resin raw material, there are formed a plurality of almost linear heating medium passages 5 in which the heating medium supplied from the outside flows and collecting pipes 6 which make each heating medium passage 5 communicant. The heating blocks can be fitted to the outer peripheral face of each cylinder block 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heating block for heating a cylinder of an extruder for plasticizing or kneading and extruding a resin material, a temperature adjusting device, and a method for producing a plasticized resin.

  Extruders and kneaders are often used as plastic molding equipment to produce films, sheets, or pellets, and secondary molding of various plastic molded products using these pellets as raw materials. Many injection molding machines are used for processing.

  In these apparatuses, it is necessary to heat the resin from the outside for melting and kneading the resin, and to heat the resin to a temperature higher than the melting temperature. For this, electric heaters such as band heaters, plate heaters and cartridge heaters are generally used. It is.

  However, when there is a risk of explosion due to a decomposable gas from a filler or additive mixed with the molten resin, an electric heater cannot be used and a heating medium heating method has been adopted. In addition, thermoelectric heaters have a limited watt density and require a start-up time, so heating in a heating medium system has been used particularly in large extruders.

  In Patent Document 1, as shown in FIGS. 1 and 3, a spiral groove is machined in a cylinder inner cylinder, and a pipe along the groove is spirally wound and machined. Installed in each cylinder, inserted into a cylindrical outer cylinder and fixed to an inner cylinder incorporating this pipe, and heated and cooled by flowing a heat medium such as water, oil, etc. through this pipe, independent for each zone A configuration capable of performing temperature control is disclosed.

Furthermore, according to Patent Document 2, a method of winding the same heat medium and refrigerant common pipe as in Patent Document 1 around the cylinder inner cylinder portion and then pouring cast iron into the outer cylinder portion is disclosed. Yes.
Japanese Unexamined Patent Publication No. 5-0577768 JP-A-11-198215

  However, in any of the above-described techniques, a pipe through which a heat medium or a refrigerant fluid flows is disposed between the inner cylinder and the outer cylinder, and it is difficult to bend the pipe along the cylinder, and cast iron products due to cast-in The quality during the casting process was unstable, and the heat transfer efficiency could vary due to the adhesion between the cast iron and the pipe. Further, in the configuration as described above, it may be difficult to repair or clean the leaked portion of the heat medium.

  Furthermore, there is a risk of explosion due to decomposition gas generated during heating and mixing of resin, additives, fillers, etc. as a case where the above configuration is adopted, and it is necessary to have an explosion-proof specification, and a thermoelectric electric heater is used. In most cases, it was used only in cases where it could not be used. Further, as shown in FIG. 3 of Patent Document 1, the cylinder is required to have a groove processing for filling the spiral pipe, and a special production form different from a normal cylinder processing step is unavoidable.

  In addition, since the above-described conventional technology is configured to perform both heating and cooling by using a spiral pipe wound around the outer periphery of the cylinder, a response time is required when switching from the heating medium to the cooling water, and a fixed set value is required. It was difficult to maintain the temperature, and overshoot and undershoot were inevitably large, and the thermal response characteristics were not good. Also, structurally, the spiral pipe is difficult to clean inside the pipe, and the cooling efficiency may be lowered due to the adhesion of oil and hot water to the inner wall of the pipe.

  Although the above prior art describes a method in which pipes are embedded in cylinders and outer cylinders, and a heat medium is allowed to flow therethrough, Patent Document 1 only shows a cylindrical shape, The example applied to the twin-screw extruder which has the screw storage part of the cross-sectional shape where the circular arc communicated is not shown. However, in Patent Document 2, an example applied to a twin-screw extruder is shown in FIG. 2, but the shape of the twin-screw extruder that requires high kneading and high extrusion amount is also described above in terms of the bending radius. Spiral pipes were a difficult form to apply.

  Therefore, an object of the present invention is to provide a heating block that can easily cope with explosion-proof specifications, has good maintainability, and is substantially applicable to a twin-screw extruder. It is another object of the present invention to provide a temperature adjusting device having a good thermal response characteristic and a method for producing a plasticized resin when adjusting the temperature of an extruder.

  The heating block of the present invention made to solve the above problems is a heating block that heats a plurality of cylinder blocks that constitute a cylinder of an extruder that houses a screw and kneads and plasticizes resin raw materials. A plurality of substantially straight heat medium passages through which the supplied heat medium flows and a collective pipe for communicating the heat medium passages are formed, and can be attached to the outer peripheral surface of each cylinder block.

  Since the heating block of the present invention having the above-described configuration can be attached to the outer peripheral surface of the cylinder block, even if it is a twin-screw extruder having a screw storage portion having a cross-sectional shape in which two arcs communicate with each other, The present invention can be applied to a twin screw extruder without being affected by the shape. Furthermore, by attaching the heating block of the present invention instead of the thermoelectric heating plate heater, the explosion-proof specification can be achieved without changing the mounting relationship with the main body. Moreover, since the heating block of this invention can be attached to each cylinder block, ie, it can be attached for every cylinder block, it can heat for every cylinder block.

  Further, since the shape of the heat medium passage is substantially linear, not only the processing is easy, but also the cleaning of the inside of the pipe is easy. For this reason, it is possible to prevent oil or hot water from adhering to the inner wall of the pipe, and to prevent a reduction in heating efficiency.

  The temperature adjusting device of the present invention is a temperature adjusting device that adjusts the temperature of a cylinder of an extruder that houses a screw and kneads and plasticizes a resin raw material. A cylinder block formed around the screw storage portion for storing therein a refrigerant passage through which a refrigerant supplied from the outside flows, and a plurality of heating media formed in a substantially linear shape through which the heat medium supplied from the outside flows. A plurality of heating blocks are formed on the outer peripheral surface of each cylinder block, and the amount of heat medium supplied to each heating block attached to each cylinder block. And a refrigerant flow rate adjusting valve for individually controlling the amount of refrigerant supplied to the refrigerant passage for each cylinder block.

  As described above, the temperature adjustment device of the present invention has the refrigerant passage independently of the heat medium passage. For this reason, the response time at the time of switching from the heat medium to the refrigerant, which is necessary in the case of the configuration in which the pipe through which the heat medium and the refrigerant flow is shared, is unnecessary, and the heat response characteristics can be improved. Further, the refrigerant supply amount to the refrigerant passage for each cylinder block can be individually controlled by the refrigerant flow rate adjusting valve. Thereby, temperature control for each cylinder block, that is, temperature control in the supply / transport zone, the melting / kneading zone, and the extrusion zone becomes possible.

  Moreover, the temperature control apparatus of this invention may have a heating block connection piping which connects the heat-medium channel | path of one heating block, and the heat-medium channel | path of another heating block.

  Moreover, the temperature control apparatus of this invention may be applied to a twin-screw extruder.

  The method for producing a plasticized resin of the present invention is a method for producing a plasticized resin by an extruder including a step of storing a screw inside and kneading and plasticizing a resin raw material, and a substantially linear shape in which a heat medium supplied from the outside flows. Attaching the heating block formed with the plurality of heat medium passages and the collective piping for communicating the heat medium passages to the outer peripheral surface of each cylinder block, and the heat medium to each heating block attached to each cylinder block And a plurality of refrigerant passages in which a refrigerant is formed around a screw storage portion that is connected to each other to form a cylinder and stores a screw. Individually controlling the amount of refrigerant supplied to the refrigerant passage for each cylinder block by means of a refrigerant flow rate adjusting valve.

  According to the present invention, it is easy to comply with explosion-proof specifications, good thermal response characteristics and maintainability, and can be substantially applied to a twin-screw extruder.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is an overall outline view of an example of a twin-screw extruder to which the temperature control device of the present invention can be applied. 2 is a cross-sectional view of the cylinder block taken along the line AA in FIG. 1, and FIG. 3 is a vertical cross-sectional view of the cylinder block taken along the line BB in FIG. In the following, a twin screw extruder will be described as an example, but the extruder may be a single screw extruder or an injection molding machine, and the same effect can be obtained. Further, the subscripts a to d in FIG. 2 correspond to the respective surfaces of the cylinder block 2 having a rectangular cross section.

  The twin-screw extruder 1 has a configuration in which a screw 3 is incorporated in a cylinder formed by connecting a plurality of cylinder blocks 2 with flanges, tie bars, and the like.

  As shown in FIG. 2, the cylinder block 2 has two circular arcs so that it can accommodate two screws 3 (only one is shown in FIG. 1 and omitted in FIGS. 2 and 3). A screw housing part 20 having a cross-sectional shape in communication is formed. The two screws 3 are housed so as to mesh with each other, and are rotationally driven in the same direction by a driving machine (not shown). The screw 3 includes a supply / transport zone, a melting / kneading zone, and an extrusion zone from the upstream side of the twin-screw extruder 1, and the screw configuration varies depending on each purpose.

  Further, the cylinder block 2 has a plurality of refrigerant passages 9 formed linearly so as to surround the screw storage portion 20 therein. The refrigerant passage 9 is formed in a straight line along the axial direction of the screw 3 and is not only easy to process but also easy to clean inside. Each refrigerant passage 9 extends to the vicinity of the end face of the cylinder block 2, and the plurality of refrigerant passages are integrated into one and connected to an external pipe.

  Heating blocks 4 a to 4 d are attached and fixed to the outer peripheral surface of the cylinder block 2. When the electric heater plate can be attached to the outer peripheral surface of the cylinder block 2 with a bolt, the heating block 4 may be fixed with a bolt at a common position with the electric heater plate. Conventional extruders using electric heater plates can be used without any problem unless the gas generated by thermal decomposition due to the mixing of additives, fillers, etc. into the molten resin is flammable. However, if the decomposition gas generated by thermally decomposing an additive such as a raw material resin or a filler or a chemical foaming agent is flammable, it is necessary to have an explosion-proof specification as described above. In such a case, by setting the heating block 4 so that it can be fixed with bolts at the same position as the electric heater plate, the currently used extruder can be easily changed to the explosion-proof specification.

  Cooling water is supplied to the refrigerant passage 9 from an external refrigerant supply device 12 (see FIG. 4) via a refrigerant flow rate adjusting valve 13 (see FIG. 4).

  In the heating block 4, a plurality of heat medium passages 5 are formed in parallel in the direction parallel to the wall surface of the cylinder block 2. Similarly to the refrigerant passage 9, the heat medium passage 5 has a linear shape along the axial direction of the screw 3, so that it can be easily processed and the inside can be easily cleaned. These heat medium passages 5 communicate with each other through a collecting pipe 6. The collective pipe 6 can be connected to the heating block connection pipe 8 at the end of the heating block 4. The heating block connection pipe 8 is a heat medium passage for communicating the heat medium passages 5 of the neighboring heating blocks 4. Further, external connection pipes 7a and 7b are respectively connected to the central part of the heating block 4a and the heating block 4b attached to the position facing the heating block 4a. The heating medium 4 is supplied into the heating block 4 through the external connection pipe 7a, and discharged from the external connection pipe 7b.

  The flow of the heat medium will be described below.

  The heat medium is preferably oil or steam (steam), but more preferably pressurized steam. By using pressurized steam as the heat medium, heating is possible even when a high viscosity resin is melted and kneaded, or when a large amount of heat energy is required, such as a high-speed specification or a large-capacity kneader or extruder with a large screw diameter. Capacity can be secured.

  The pressurized steam is supplied from the external heat medium supply device 10 (see FIG. 4) to the external connection pipe 7a. A pipe between the heat medium supply device 10 and the external connection pipe 7a is provided with a heat medium flow rate adjusting valve 11 (see FIG. 4) for adjusting the flow rate of the pressurized steam. By adjusting the opening degree of the heat medium flow rate adjusting valve 11, the temperature of the heating block 4a is maintained near the set temperature.

  The heat medium supplied from the heat medium supply device 10 to the external connection pipe 7a is supplied to the heat medium passage 5 of the heating block 4a. The heat medium branches to the adjacent heat medium passage 5 by the collecting pipe 6 and flows into the heating block connection pipes 8a and 8b attached to both ends of the heating block 4a.

  The heat medium flowing into the heating block connection pipe 8a flows through the heat medium passage 5b and the collecting pipe 6b of the heating block 4b and flows into the heating block connection pipe 8d, and further into the heat medium passage 5d and the collecting pipe 6d of the heating block 4d. Flowing. Similarly, the heat medium flowing into the heating block connection pipe 8b flows through the heat medium passage 5c and the collection pipe 6c of the heating block 4c and flows into the heating block connection pipe 8c, and further, the heat medium passage 5d and the collection of the heating block 4d. It flows in the pipe 6d.

  The heat medium flowing in from the heating block connection pipes 8c and 8d joins in the external connection pipe 7b attached to the central portion of the heating block 4d and is discharged to the outside.

  The heat medium flowing along the above path heats the outer peripheral surface of the cylinder block 2 almost evenly. The heat is transferred to the inner wall portion of the cylinder block 2 (the wall surface of the screw storage portion 20), and heats the resin kneaded and extruded downstream by the rotating screw 3. In addition, the flow path of piping is an example, and if it is the structure which heats the whole area of the cylinder block 2 equally, a flow path is not limited to the structure of this embodiment.

  Each of the passages 5 to 8 of the heat medium is not shared with the refrigerant passage 9 but is formed independently, so that the heat medium and the refrigerant that are necessary in the case of a configuration in which a pipe through which the heat medium and the refrigerant flow are shared are used. The response time at the time of switching is not required, and the thermal response characteristics can be improved. Moreover, the temperature control apparatus of this embodiment becomes a structure which can control heating and cooling independently.

  Each passage is also independent between each cylinder block 2 connected by a flange, a tie bar or the like. That is, since temperature control is possible for each cylinder block 2, the temperature can be controlled for each zone of the supply / transport zone, the melting / kneading zone, and the extrusion zone. In the present embodiment, as will be described later, a method of controlling the temperature in each zone by independently controlling the cooling system is adopted.

  Next, temperature control of the entire cylinder formed by connecting a plurality of cylinder blocks 2 will be described with reference to FIG. 4 which is a schematic overall configuration diagram of a temperature adjusting device for an extruder according to this embodiment. In FIG. 4, for the sake of simplicity, the supply / transport zone, the melting / kneading zone, and the extrusion zone are shown as being composed of one cylinder block.

  The temperature control system of the present embodiment includes a heating system including a heating medium supply device 10 and a heating medium flow rate adjustment valve 11, and a cooling system including a refrigerant supply device 12 and a refrigerant flow rate adjustment valve 13 independent of the heating system. And a temperature control device 14 for controlling them. The heating medium flow rate adjusting valve 11 and the refrigerant flow rate adjusting valve 13 may be electromagnetic valves that are opened and closed by an ON-OFF signal from the temperature control device 14.

  As described above, the cylinder block 2 is maintained near the set temperature by adjusting the flow rate of the pressurized steam supplied from the heat medium supply device 10. In this embodiment, the flow rate of the pressurized steam is not adjusted independently for each cylinder block 2, but all the cylinder blocks 2 constituting the entire cylinder are adjusted together.

  On the other hand, the cooling can be adjusted independently for each cylinder block. That is, for temperature control for each zone, a refrigerant flow rate adjusting valve 13 is provided for each cylinder block, and each cylinder block is independently opened and closed by opening and closing each refrigerant flow rate adjusting valve 13. It is configured to cool.

  For example, if the temperature control device 14 determines that the temperature in the melting / kneading zone is higher than the set temperature based on a signal from a temperature detection sensor (not shown), the temperature control device 14 The refrigerant flow rate adjustment valve 13 corresponding to the cylinder block 2 is opened, and cooling water is supplied from the refrigerant supply device 12 to the refrigerant passage 9. As a result, the temperature of the cylinder block 2 in the melting / kneading zone is rapidly cooled so as to be close to the predetermined molten resin temperature. Note that chiller water may be used as cooling water in order to further enhance the temperature response characteristics.

  As described above, according to the present embodiment, the following effects can be obtained.

  1. By simply replacing the electric plate heater with the heating block 4, it is possible to make a heating medium heater and easy explosion-proof.

  2. Since the heat medium passage 5 and the refrigerant passage 9 have a linear shape, processing and internal cleaning are easy.

  3. By using pressurized steam as the heat medium, heating is possible even when a high viscosity resin is melted and kneaded, or when a large amount of heat energy is required, such as a high-speed specification or a large-capacity kneader or extruder with a large screw diameter. Capacity can be secured.

  4). Since heat medium piping and cooling water piping are not used separately, they are made independent of each other, so the thermal response characteristics are good, and the resin can be melted and plasticized within the desired set temperature range. Stabilize.

  5. Since the supply of the cooling water to the cooling water pipe 9 can be controlled individually for each zone, the temperature can be controlled for each zone, and the quality of the molded product is stabilized.

  6). The resin temperature can be adjusted by simple control only by turning the refrigerant flow rate adjusting valve 13 on and off.

  7). Since the heating block is configured to be attached to the outer peripheral surface of the cylinder block, even if the screw storage part has a cross-sectional shape in which two arcs communicate with each other like a twin-screw extruder, it is affected by this shape. Can be installed.

It is the schematic of an example of the twin-screw extruder which can apply the temperature control apparatus of the extruder of this invention. It is a cross-sectional view of a cylinder block taken along line AA in FIG. It is a longitudinal cross-sectional view of the cylinder block in the BB line in FIG. It is a schematic whole block diagram of the temperature control apparatus of the extruder of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Twin screw extruder 2 Cylinder barrel 3 Screw 4a, 4b, 4c, 4d Heating block 5a, 5b, 5c, 5d Heat medium passage 6a, 6b, 6c, 6d Collective piping 7a, 7b External connection piping 8a, 8b, 8c, 8d Heating block connection pipe 9 Refrigerant passage 10 Heat medium supply device 11 Heat medium flow rate adjustment valve 12 Refrigerant supply device 13 Refrigerant flow rate adjustment valve 14 Temperature control device 20 Screw storage unit

Claims (5)

In the heating block that heats multiple cylinder blocks that constitute the cylinder of the extruder that houses the screw and kneads and plasticizes the resin raw material,
A plurality of substantially linear heat medium passages (5) through which a heat medium supplied from the outside flows, and an assembly pipe (6) communicating the heat medium passages (5) are formed, and each cylinder block (2 The heating block can be attached to the outer peripheral surface of the heating block. In the temperature adjustment device that adjusts the temperature of the cylinder of the extruder that houses the screw inside and kneads and plasticizes the resin raw material,
The cylinder is formed by being connected to each other, and a refrigerant passage (9) is formed around the screw storage portion (20) for storing the screw (3) and through which refrigerant supplied from the outside flows. A cylinder block (2);
A plurality of heat medium passages (5) formed in a substantially linear shape through which a heat medium supplied from the outside flows, and a collection pipe (6) communicating the heat medium passages (5) are formed. A plurality of heating blocks attached to the outer peripheral surface of the block (2);
A heating medium flow rate adjustment valve (11) for controlling the amount of heating medium supplied to each heating block (4) attached to each cylinder block (2);
A temperature adjusting device comprising: a refrigerant flow rate adjusting valve (13) for individually controlling the amount of refrigerant supplied to the refrigerant passage (9) for each cylinder block (2).   The heating block connecting pipe (8) for communicating the heating medium passage (5) of one heating block (4) with the heating medium passage (5) of another heating block (4). The temperature adjusting device described in 1.   The temperature adjusting device according to claim 2 or 3, wherein the extruder is a twin-screw extruder (1). In a plasticized resin manufacturing method using an extruder including a step of storing a screw inside and kneading and plasticizing a resin raw material,
A heating block (4) in which a plurality of substantially linear heating medium passages (5) through which a heating medium supplied from the outside flows and an aggregate pipe (6) for communicating the heating medium passages (5) are formed. Attaching to the outer peripheral surface of each cylinder block (2);
Controlling the amount of heat medium supplied to each heating block (4) attached to each cylinder block (2) by means of a heat medium flow rate adjusting valve (11);
A plurality of cylinder blocks (2) that are connected to each other to form the cylinder and that are formed with a refrigerant passage (9) through which a refrigerant formed around a screw storage portion (20) that stores the screw (3) flows. ) Individually controlling the amount of refrigerant supplied to the refrigerant passage (9) by means of the refrigerant flow rate adjusting valve (13).

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