JPH071554A - Method and apparatus for heating cylinder of extruder - Google Patents

Abstract

PURPOSE:To hold the temp. in a cylinder to a predetermined temp. range while holding the temp. of a heater coil to predetermined temp. or less and to dispense with other cooling equipment by measuring the temp. in the cylinder to control a supply current and measuring the surface temp. of the heater coil to control a supply current. CONSTITUTION:The temp. at the temp. detection point 1a in the cylinder of a cylinder block B is measured to control the supply current to an induction heater H on the basis of the measured value to hold the temp. of the cylinder block B to a predetermined temp. range. The transmission of heat to heater coils 31-34 from the heated cylinder block B is cut off and the temps. at the coil surface temp. detection points 3a of the heater coils 31-34 are measured and the supply current to the induction heater H is controlled on the basis of the measured values. By this constitution, the temps. of the heater coils 31-34 can be held to predetermined temp. or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating method and a heating device for heating a cylinder of an extruder in which a resin is melted, kneaded, and molded and extruded in a cylinder whose outer edge has a rectangular cross section.

[0002]

2. Description of the Related Art FIG. 4 is a schematic perspective view of a conventional heating device having a cooling fan 76.

Conventionally, a screw type extrusion molding machine is generally a cylinder 1 shown in FIG. 2, a screw rotated in the cylinder 1, a hopper 9 for supplying a resin raw material 11 to the cylinder 1, and a tip portion of the cylinder 1. , A motor for driving the screw, a heater for melting and gelating the resin inside the outer peripheral portion of the cylinder, a temperature control device for the cylinder 1, and the like. Conventionally, various heating methods have been adopted. Among them, when a large amount of heat is required,
Instead of resistance heating methods such as aluminum casting heaters, brass casting heaters, and band heaters, induction heating type ones are used. When the cylinder 1 has a circular cross section in the induction heating method, a coil is wound around the cylinder 1 in the form of a solenoid to allow AC power to flow and generate an eddy current in the cylinder 1.
This heat is used.

Therefore, particularly in the case of a twin-screw extruder having a cylinder 1 whose outer edge has a rectangular cross section, a flat heater coil is used to prevent imbalance in the alternating magnetic flux. However, in the case of this method, since the temperature rise of the heater coil is likely to occur, it is necessary to take measures to prevent the temperature from being lower than the allowable temperature. Therefore, by providing a jacket for flowing a cooling fluid or a cooling fan 76,
In some cases, a method of cooling the coil has been adopted.

[0005]

However, the above-described method of cooling the coil by the jacket or the cooling fan is not preferable because the apparatus becomes large and the equipment cost and the operating cost increase. Therefore, an object of the present invention is to provide a heat insulating material to prevent heat transfer from the cylinder to the heater coil,
Extrusion that can maintain the temperature of the cylinder within a specified range and the temperature of the coil below a specified temperature by providing an automatic temperature adjustment mechanism for the cylinder and an automatic alarm mechanism for the heater coil temperature. A method and a device for heating a cylinder of a machine are provided.

[0006]

According to the method for heating a cylinder of an extruder of the present invention, the temperature inside the cylinder is measured, and the supply current to an induction heating device having a heater coil is controlled based on the measured value. As a result, the temperature of the cylinder is maintained within a predetermined range, heat transfer from the heated cylinder to the heater coil is cut off, the temperature of the surface of the heater coil is measured, and the induction heating device is based on the measured value. The method is characterized by including a method of maintaining the temperature of the heater coil at a predetermined temperature or lower by controlling the current supplied to the heater coil.

Further, the heating device for the cylinder of the extruder includes a heat insulating material for preventing heat transfer from the heated cylinder to the heater coil, and an electromagnetic controller for supplying a current to the induction heating device having the heater coil. A temperature sensing element that measures the temperature inside the cylinder, a temperature controller that sends a control signal of the current supplied to the induction heating device to the electromagnetic controller based on the measured value, and the temperature of the surface of the heater coil A temperature sensor,
An alarm device for transmitting a control signal of a current supplied to the induction heating device to the electromagnetic controller based on the measured value is provided, and the temperature of the cylinder is maintained within a predetermined temperature range by these facilities, and a heater coil is provided. Is characterized in that it can be maintained below a predetermined temperature.

[0008]

Function: The temperature inside the cylinder block is measured by the temperature sensing element, and if the measured temperature deviates from the predetermined range, a control signal is sent from the temperature controller to the electromagnetic controller, and the heater coil of the induction heating device is The amount of heating is adjusted by adjusting the electric current. As a result, the operating temperature of the cylinder block quickly returns to the predetermined range.

Further, the heat of the cylinder block, which is generated by the dielectric, is not transmitted to the heater coil of the induction heating device arranged outside by the heat insulating material. However, the temperature of the heater coil surface is measured by the temperature sensing element in response to the self-heating of the heater coil, and when the measured temperature reaches the set point, the alarm sends a control signal such as reduction or cutoff to the electromagnetic controller. , The current supplied to the induction heating device is controlled.

As a result, the working temperature of the cylinder is maintained within a predetermined range, and the temperature of the heater coil is maintained below a predetermined value.

[0011]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 (a) is a schematic perspective view of a cylinder block B and its induction heating device H of an embodiment of a heating device for a cylinder of an extruder according to the present invention, and FIG. 1 (b) is a schematic view of its operating principle. 2 is a schematic view showing the heating control system of this embodiment, and FIG. 3 is a graph showing the temperature changes of the cylinder and coil of this embodiment.

The heating device for the cylinder of the extruder of the present invention comprises:
An eddy current is induced in the cylinder 1 having a structure in which the resin raw material 11 supplied into the cylinder 1 having an outer edge of a cross section is heated, pressurized, melted, kneaded, and extruded from the molding die 10. Therefore, it has a flat heater coil 3 provided near the outer surface of the cylinder 1 and to which a high-frequency current is applied.

The cylinder 1 is of a biaxial type and is horizontally arranged, as is apparent from FIGS. 1 (a), 1 (b) or 2. A hopper 9 for receiving the resin raw material 11 is provided at the left end of the cylinder 1, and a molding die 10 for extruding a plastic molded product is provided at the right end. The cylinder 1 is composed of eight cylinder blocks B _{1 to} B _{8 having} substantially the same length, and induction heating devices H _{1 to} H ₉ are provided on each of them together with the molding die 10.

The induction heating device H is shown in FIG.
Flat heater coils 3 on the right, top, left, and bottom
₁ , 3₂ , 3₃ , 3_Four Are placed, and these four heater
IL 3 ₁ ~ 3_Four Are connected 2 by 2 and 3 by 3₁ , 3₂ When
Three₃ , 3_Four It has become. These two sets of heater coils
Three₁ , 3₂ , And 3₃ , 3_Four Is two L-shaped coils
Support plate 4₁ , 4₂ Is supported inside each of.
And the coil support plate 4₁Coils passing inward
The heater coil 3 is formed by the lead wires 22, 23, 24, 25.
₁ And 3₂ Connection between and heater coil 3₁ , 3₂ And electromagnetic
The connections between the controllers 2 are made. Heater coil 3₃ ，
Three_Four The relationship between the corresponding electromagnetic controller 2'and
Since it is exactly the same, illustration and description thereof are omitted.

The cylinder 1 includes a cylinder block B, and the induction heating device H, a heat insulating material 7 surrounding the periphery since heat from the cylinder block B to the heater coil 3 ₁ to 3 ₄ is prevented from being transmitted, the cylinder thermocouple 5 ₀ for measuring the temperature inside the cylinder internal temperature detection point 1a of the block B, the heater coil 3 ₁ to the solenoid control unit 2 receives the measured value
3 and temperature controller 6 for controlling the current supplied to the _4, receives the thermocouple 5 ₁ to 5 ₄ for measuring the temperature of the heater coil 3 ₁ to 3 ₄ coil surface temperature detecting points 3a, the measurement electromagnetic An alarm device 8 for controlling the current supplied from the controller 2 to the coils 3 _{1 to} 3 ₄ is provided, and by these functions, the temperature of the cylinder internal temperature detection point 1a of the cylinder 1 falls within a predetermined range, for example, 220 ° C. Maintained within the range of 250 ° C, and
The temperature of the heater coils 3 _{1 to} 3 ₄ is a predetermined temperature, for example, 17
It is set so that it can be maintained below 0 ° C.

This is because the molding operation temperature is 220 to 250 ° C.
This is because the litz wire serving as the heater coil has an allowable temperature of 180 ° C. and a desired operating temperature of 170 ° C.

The temperature at the cylinder surface temperature detection point 1b is also measured by a thermocouple (not shown), and the measured values of the temperature at the cylinder internal temperature detection point 1a of the cylinder 1 and the temperature at the heater coil surface temperature detection point 3a are measured. Related data is used as reference data for management. This measurement data is also electromagnetic controller 2
It is also possible to arrange so as to be combined with.

The same structure is representatively described for each of the cylinder blocks B _{1 to} B ₈ and the molding die 10.

Next, the operation of this embodiment will be briefly described because it is considered to be almost clear from the above-mentioned equipment configuration.

The resin raw material 11 supplied from the hopper 9 is
An upstream cylinder block inserted into cylinder 1 of the extruder
B₁ Cylinder block B downstream from₈ Melts in between,
Kneaded, molded from the molding die 10 and extruded
However, each cylinder block B ₁ ~ B₈ And molding machine
The operation to keep the temperature of b within the specified range is as follows.
It is Ri.

The cylinder block B is controlled by the temperature controller 6.
The working temperature control range is set to, for example, 180 to 220 ° C. Thermocouple temperature inside 1a of the cylinder block B 5 ₀
If the temperature is out of the set range, a control signal is transmitted from the temperature controller 6 to the electromagnetic controller 2, and by adjusting the current of the heater coils 3 _{1 to} 3 ₄ of the induction heating device H, The heating amount is adjusted. As a result, the working temperature of the cylinder block B quickly returns to the predetermined range. Therefore, it is maintained within a predetermined temperature range.

Further, the heater coil 3₁ ~ 3_Four Coil wire
Since the allowable temperature of the litz wire is 180 ° C, use
The temperature is to be maintained below 170 ° C. Dielectrically
The heat of the cylinder block B that generates more heat is due to the surrounding heat insulating material.
Heater coil 3 because there is 7 ₁ ~ 3_Four Is not transmitted to
Yes. However, the heater coil 3₁ ~ 3_Four Is due to self-heating
Since the temperature rises, the temperature of the coil surface temperature detection point 3a
Thermocouple 5₁ ~ 5_Four Measured by, if reached 170 ℃
, A control signal is transmitted from the alarm device 8 to the electromagnetic controller 2,
Heater coil 3₁ ~ 3_Four Reduce the current to or
Cut off. This keeps the coil temperature below 170 ° C.
Be done.

The above operations can be individually performed in each of the cylinder blocks B _{1 to} B ₈ and the molding die 10 and each of the induction heating devices H _{1 to} H ₉ as required.

FIG. 3 is a graph showing a state in which these temperatures are controlled mainly at the time of start-up heating. In this way, proper and stable operation can be obtained.

[0026]

As described above, according to the present invention, a heat insulating material is provided on the outer surface of the cylinder of an extruder, and a signal for controlling the current supplied to the heater coil when the temperature inside the cylinder deviates from a predetermined range is electromagnetic. By providing a temperature controller that sends to the controller and an alarm that sends a signal that controls the current supplied to the heater coil to the electromagnetic controller when the temperature of the heater coil exceeds a predetermined temperature, the cylinder internal temperature is Heating of the cylinder of an extruder, which can be maintained within a predetermined temperature range, the temperature of the heater coil can be maintained below a predetermined temperature, and there is no need to install large equipment for other cooling methods. There is an effect that the device can be provided.

[Brief description of drawings]

FIG. 1 (a) is a schematic perspective view of a cylinder block B and its induction heating device H of an embodiment of a heating device for a cylinder of an extruder of the present invention, and FIG. It is a perspective view which shows typically.

FIG. 2 is a schematic diagram showing a heating control system of the present embodiment.

FIG. 3 is a graph showing changes in temperature of a cylinder and a coil according to this embodiment.

FIG. 4 is a schematic perspective view of a conventional heating device including a cooling fan.

[Explanation of symbols]

1 cylinder 1a, 1a ₁ to 1A ₉ cylinder internal temperature detecting points 1b, 1b ₁ ~1b ₉ cylinder surface temperature detecting points 2,2 ', 2 ₁ to 2 ₉ solenoid controller 3, 3 _1, 3 _{2, 3} 3, 3 _4, 53 heater coil 3a, 3a ₁ to 3 A ₉ coil surface temperature detection point 4 _1, 4 ₂ coil supporting plate 5 _0, 5 _1, 5 _2, 5 _3, 5 _4, 55 temperature sensing element (thermocouple) 6 temperature controller 7 and 57 thermal insulator 8,8 _{1-8 9} alarm 9 hopper 10 molding die 11 resin material 22～25,72,75 coil lead wire 76 cooling fan 77 air passage 78 air B, B ₁ ~B ₈ , B ₅₁ Cylinder block H, H ₁ ~ H ₉ , H ₅₁ Induction heating device S power supply

Claims (2)

[Claims] 1. A cylinder (1) having a rectangular outer edge in cross section.
In order to induce an eddy current in the cylinder (1) of the extruder having a structure in which the resin supplied therein is heated, pressurized, melted, kneaded, and extruded from the molding die (10), the cylinder ( In the method of heating a cylinder of an extruder by an induction heating device (H) having a flat heater coil (3) provided near the outer surface of 1) to which a high-frequency current is applied, the temperature inside the cylinder of the cylinder block (B) Detection point (1
By measuring the temperature of a) and controlling the supply current to the induction heating device (H) based on the measured value, the temperature of the cylinder block (B) is maintained within a predetermined range and heated. The heat transfer from the cylinder block (B) to the heater coil (3) is cut off, and the temperature at the coil surface temperature detection point (3a) of the heater coil (3) is measured, and based on the measured value. A method for heating a cylinder of an extruder, comprising a method of maintaining a temperature of the heater coil (3) at a predetermined temperature or lower by controlling a current supplied to the induction heating device (H). 2. A cylinder (1) having a rectangular outer edge in cross section.
In order to induce an eddy current in the cylinder (1) of the extruder having a structure in which the resin supplied therein is heated, pressurized, melted, kneaded, and extruded from the molding die (10), the cylinder ( In a heating device for a cylinder of an extruder by an induction heating device (H) having a flat heater coil (3) provided near the outer surface of 1) and to which a high-frequency current is applied, from a heated cylinder block (B) A heat insulating material (7) for preventing heat transfer to the heater coil (3) and an electromagnetic controller (2) for supplying a current to the induction heating device (H).
If, temperature element for measuring the temperature of the cylinder internal temperature detection points of the cylinder block (B) (1a) and (5 _0), the supply current of the to the induction heating-up Reel (H) based on the measurement value temperature controller for transmitting a control signal electromagnetic controller to (2) and (6), said temperature sensing element to measure the temperature of the coil surface temperature detection points of the heater coil (3) (3a) (5 1 ~5 4)
And an alarm device (8) for transmitting a control signal of a current supplied to the induction heating device (H) to the electromagnetic controller (2) based on the measured value, and the cylinder ( A heating device for a cylinder of an extruder, wherein the temperature of 1) can be maintained within a predetermined temperature range, and the temperature of the heater coil (3) can be maintained below a predetermined temperature.