Continuous kneading device and control method thereof

Abstract

To provide an excellent continuous kneading device. [Solution] A continuous kneading device according to one embodiment includes a first temperature sensor provided in a cylinder for measuring the temperature of the molten resin from which the resin pellets are melted, and a controller for feedback-controlling a heating unit based on the temperature of the molten resin measured by the first temperature sensor.

Description

[Technical Field]

[0001] The present invention relates to a continuous kneading apparatus and a control method thereof. [Background technology]

[0002] Resin extrusion molding devices and injection molding devices are equipped with a continuous kneading device that heats resin pellets fed into a cylinder with a heater and kneads them with a screw. As disclosed in Patent Document 1, the inventors have developed a continuous kneading device that measures the temperatures of parts of the cylinder heated by each of multiple heaters with a temperature sensor and feedback-controls each heater based on the measured temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-067240 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have encountered various problems in developing a continuous kneading device. For example, the quality of the molded resin depends on the temperature of the molten resin discharged from the continuous kneading device, and the temperature of the molten resin is affected not only by the heat absorption from the cylinder but also by the shear heat generated by the screw.

[0005] However, in continuous mixers, the heaters are feedback-controlled based on the measured temperatures of the parts of the cylinder heated by the heaters, which makes it difficult to accurately grasp the temperature of the molten resin discharged from the continuous mixer, and this can result in a long time being required to stabilize the quality of the molded resin, and can also waste resin material. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0006] A continuous kneading device according to one embodiment includes a first temperature sensor provided in a cylinder for measuring the temperature of the molten resin from which the resin pellets are melted, and a controller for feedback-controlling the heating unit based on the temperature of the molten resin measured by the first temperature sensor.

[0007] A control method for a continuous kneading device according to one embodiment is a control method for a continuous kneading device provided with a first temperature sensor disposed in a cylinder for measuring the temperature of the molten resin from which resin pellets have been melted, and includes the steps of (a) feedback-controlling the heating unit based on the temperature of the molten resin measured by the first temperature sensor. [Effects of the Invention]

[0008] According to the embodiment, an excellent continuous kneading device can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of a continuous kneading device according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the configuration of a continuous kneading device according to a comparative example. [Figure 3] FIG. 10 is a block diagram showing the configuration of a controller 70 according to a second embodiment. [Figure 4] 10 is a flowchart showing a control method for a continuous kneading device according to a second embodiment. [Figure 5] FIG. 10 is a block diagram showing the configuration of a controller 70 according to a modified example of the second embodiment. [Figure 6] FIG. 10 is a schematic cross-sectional view showing the configuration of a continuous kneading device according to a third embodiment. [Figure 7] 10 is a flowchart showing a control method for a continuous kneading device according to a third embodiment. [Figure 8]FIG. 2 is a schematic cross-sectional view of a continuous kneading apparatus in a cylinder temperature control mode. [Figure 9] FIG. 2 is a schematic cross-sectional view of a continuous kneading device in a resin temperature control mode. [Figure 10] FIG. 2 is a schematic cross-sectional view of a continuous kneading device in a resin temperature control mode (cascade control). DETAILED DESCRIPTION OF THE INVENTION

[0010] Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been simplified as appropriate.

[0011] (First embodiment) <Configuration of continuous kneading equipment> First, the configuration of the continuous kneading device according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing the configuration of the continuous kneading device according to the first embodiment. As shown in FIG. 1, the continuous mixer according to the first embodiment includes a cylinder 11, a screw 12, a hopper 13, a heater 14, a temperature sensor 61, and a controller 70.

[0012] Naturally, the right-handed XYZ Cartesian coordinate system shown in Figure 1 and other drawings is for the convenience of explaining the positional relationships of the components. Normally, the positive direction of the Z axis is the vertically upward direction, and the XY plane is the horizontal plane, which is common among the drawings. Furthermore, the continuous kneading device according to this embodiment is used in, for example, an extrusion molding device, but may also be used in an injection molding device. In the case of an injection molding device, the screw 12 is configured to be movable in the X-axis direction to perform the injection operation.

[0013] The cylinder 11 is a cylindrical member extending in the X-axis direction. The screw 12 extends in the X-axis direction and is rotatably housed in the cylinder 11. Although not shown, a motor is connected to the screw 12 as a rotation drive source via a reducer, for example.

[0014] The extrusion molding device may have a single or multiple screws 12. For example, if there is one screw 12, it is called a single-screw extrusion molding device, and if there are two screws 12, it is called a twin-screw extrusion molding device.

[0015] Hopper 13 is a cylindrical member for feeding resin pellets 81, which are the raw material for the resin molded product to be manufactured, into cylinder 11. Hopper 13 is provided above the end of cylinder 11 on the positive X-axis direction side.

[0016] As shown in Fig. 1, the heater 14 is a circular or rectangular annular heater provided to cover the outer peripheral surface of the cylinder 11. The heaters 14 arranged in a row along the longitudinal direction (x-axis direction) of the cylinder 11 constitute a heating unit. As an example, in Fig. 1, four heaters 14 are provided on the tip side (positive x-axis direction side) of the hopper 13. Each of the multiple heaters 14 can be individually controlled by a controller 70. The number of heaters 14 in the heating unit is not limited in any way, and may be one or more.

[0017] The temperature sensors 61 are provided in the cylinder 11 and measure the temperature of the molten resin 82 obtained by melting the resin pellets 81. Although not particularly limited, the temperature sensors 61 are provided between the tip of the screw 12 and the discharge port 11a, for example, as shown in FIG. 1. The temperature sensors 61 are, for example, thermocouples. In the example shown in FIG. 1, each temperature sensor 61 is inserted into a through-hole formed in the cylinder 11 and provided so as to come into contact with the molten resin 82.

[0018] The controller 70 performs feedback control of the heater 14 based on the temperature of the molten resin 82 measured by the temperature sensor 61 (measured resin temperature). More specifically, the controller 70 controls the output of the heater 14 so that the resin temperature measured by the temperature sensor 61 approaches a set temperature (target temperature). Although not limited thereto, the controller 70 is called, for example, a PLC (Programmable Logic Controller). The controller 70 may also be, for example, a PC (Personal Computer).

[0019] Although not shown, the controller 70 includes a calculation unit such as a CPU (Central Processing Unit) and memories such as RAM (Random Access Memory) and ROM (Read Only Memory) that store various programs and various data, etc. In other words, the controller 70 functions as a computer and controls the heater 14 based on the various programs, etc.

[0020] 1 can be configured as hardware using the CPU, memory, and other circuits. Furthermore, the controller 70 can be implemented as software using programs stored in memory. In other words, the controller 70 can be implemented in various forms using a combination of hardware and software.

[0021] In the continuous mixer according to the first embodiment, resin pellets 81 supplied from a hopper 13 are heated by a heater 14 inside a cylinder 11, and are sheared and melted by a rotating screw 12, turning into a molten resin 82. The molten resin 82 is extruded by the rotating screw 12 from the base side to the tip side of the screw 12 (in the positive direction of the X-axis), and is discharged from a discharge port 11a.

[0022] <Configuration of a continuous kneading device according to a comparative example> Here, the configuration of a continuous kneading device according to a comparative example will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view showing the configuration of a continuous kneading device according to a comparative example. 2, the continuous mixer according to the comparative example is provided with a temperature sensor 62 instead of the temperature sensor 61. In other words, the continuous mixer according to the comparative example is not provided with the temperature sensor 61.

[0023] 2, the temperature sensors 62 measure the temperatures of the portions of the cylinder 11 that are heated by the heaters 14. The temperature sensors 62 are, for example, thermocouples. In the example shown in FIG. 2, each temperature sensor 62 is inserted into a through-hole formed in the heater 14 and is provided so as to be in contact with the cylinder 11.

[0024] 2, in the continuous mixer according to the comparative example, the controller 70 feedback-controls the corresponding heaters 14 based on the measured temperature of each part of the cylinder 11 measured by each temperature sensor 62. More specifically, the controller 70 controls the output of each heater 14 so that the measured temperature of each part of the cylinder 11 measured by each temperature sensor 62 approaches the respective set temperature (target temperature).

[0025] Here, the quality of the molded resin depends on the temperature of the molten resin 82 discharged from the continuous kneading device, but the temperature of the molten resin 82 is affected not only by the heat absorption from the cylinder 11 but also by the shear heat generated by the screw 12 on the resin pellets 81.

[0026] In the continuous mixer according to the comparative example, each heater 14 is feedback-controlled based on the measured temperature of the portion of the cylinder 11 heated by each heater 14. As a result, the temperature of the molten resin 82 discharged from the continuous mixer cannot be accurately determined, and it takes a long time to stabilize the quality of the molded resin, and resin material is wasted in some cases.

[0027] 1 is provided with a temperature sensor 61 that is provided in the cylinder 11 between the tip of the screw 12 and the discharge port 11a and that measures the temperature of the molten resin 82 formed by melting the resin pellets 81. Therefore, the continuous kneading device according to this embodiment can more accurately grasp the temperature of the molten resin 82 being discharged compared to the continuous kneading device according to the comparative example, and can reduce the time and resin material required to stabilize the quality of the molded resin.

[0028] (Second embodiment) Next, a continuous kneading device according to a second embodiment will be described. The overall configuration of the continuous kneading device according to the second embodiment is similar to the overall configuration of the continuous kneading device according to the first embodiment shown in Fig. 1, so a description thereof will be omitted. The continuous kneading device according to this embodiment differs from the continuous kneading device according to the first embodiment in the internal configuration of the controller 70.

[0029] <Configuration of the controller 70 according to the second embodiment> The configuration of the controller 70 according to the second embodiment will be described in detail with reference to Fig. 3. Fig. 3 is a block diagram showing the configuration of the controller 70 according to the second embodiment. As shown in Fig. 3, the controller 70 according to this embodiment includes a state observing unit 71, a control condition learning unit 72, a storage unit 73, and a control signal output unit 74.

[0030] The controller 70 of this embodiment, like the controller 70 of the first embodiment, feedback controls the heaters 14 based on the temperature of the molten resin 82 (measured resin temperature) measured by the temperature sensor 61, and also learns the control conditions of each heater 14.

[0031] Each functional block constituting the controller 70 can be configured in hardware by a CPU, memory, and other circuits, and can be realized in software by a program loaded into memory, etc. Therefore, each functional block can be realized in various forms by computer hardware, software, or a combination thereof.

[0032] The state observing unit 71 calculates the control deviation for each heater 14 from the measured temperature value pv acquired from each temperature sensor 61. The control deviation is the difference between the target value and the measured value pv. Here, the target value is the target temperature set for each heater 14. On the other hand, the measured value pv is the measured temperature value acquired from the temperature sensor 61 corresponding to the target heater 14.

[0033] Then, for each heater 14, the state observing unit 71 determines the current state st and the reward rw for the previously (for example, last) selected action ac based on the calculated control deviation. The state st is set in advance to divide the infinitely possible control deviation values ​​into a finite number. As a simple example for explanation, if the control deviation is err, -4.0°C≦err<-3.0°C is set as state st1, -3.0°C≦err<-2.0°C is set as state st2, -2.0°C≦err<-1.0°C is set as state st3, -1.0°C≦err<1.0°C is set as state st4, 1.0°C≦err≦2.0°C is set as state st5, 2.0°C≦err≦3.0°C is set as state st6, 3.0°C≦err≦4.0°C is set as state st7, and 4.0°C≦err≦5.0°C is set as state st8. In practice, many more finely divided states st are often set.

[0034] The reward rw is an indicator for evaluating the action ac chosen in the previous state st. Specifically, if the absolute value of the calculated current control deviation is smaller than the absolute value of the previous control deviation, the state observing unit 71 determines that the previously selected action ac is appropriate, and sets the reward rw to a positive value, for example. In other words, the reward rw is determined so that the previously selected action ac is more likely to be selected again in the same state st as before.

[0035] Conversely, if the absolute value of the calculated current control deviation is larger than the absolute value of the previous control deviation, the state observing unit 71 determines that the previously selected action ac is inappropriate, and sets the reward rw to a negative value, for example. In other words, the reward rw is determined so that the previously selected action ac is less likely to be selected again in the same state st as before. Specific examples of the reward rw will be described later. The value of the reward rw can be determined as appropriate. For example, the value of the reward rw may always be a positive value, or the value of the reward rw may always be a negative value.

[0036] The control condition learning unit 72 performs reinforcement learning for each heater 14. Specifically, the control condition learning unit 72 updates the control conditions (learning results) based on the reward rw, and selects an optimal action ac corresponding to the current state st from the updated control conditions. The control conditions are combinations of the state st and the actions ac. Table 1 shows simple control conditions (learning results) corresponding to the above-mentioned states st1 to st8. In the example of FIG. 3, the control condition learning unit 72 stores the updated control conditions cc in the storage unit 73, which is a memory, for example, and reads out the control conditions cc from the storage unit 73 to update them.

[0037] [Table 1]

[0038] Table 1 shows the control conditions (learning results) of Q-learning, which is an example of reinforcement learning. The top row of Table 1 shows the eight states st1 to st8 mentioned above. That is, each of the second to ninth columns shows the eight states st1 to st8. On the other hand, the leftmost column of Table 1 shows five actions ac1 to ac5. That is, each of the second to sixth columns shows the five actions ac1 to ac5.

[0039] In the example of Table 1, an action to reduce the output (e.g., voltage) to the heater 14 by 1.0% is set as action ac1 (output change: -1%). An action to reduce the output (e.g., voltage) to the heater 14 by 0.5% is set as action ac2 (output change: -0.5%). An action to maintain the output to the heater 14 is set as action ac3 (output change: 0%). An action to increase the output to the heater 14 by 0.5% is set as action ac4 (output change: +0.5%). An action to increase the output to the heater 14 by 1.0% is set as action ac5 (output change: +1.0%). The example in Table 1 is merely a simple example for the purpose of explanation, and in reality, many more detailed actions ac are often set.

[0040] In Table 1, the value determined from the combination of state st and action ac is called value Q(st, ac). After an initial value is given to value Q, it is sequentially updated based on reward rw using a known update formula. The initial value of value Q is included in the learning conditions shown in FIG. 3, for example. The learning conditions are input by, for example, an operator. The initial value of value Q may be stored in memory unit 73, or, for example, past learning results may be used as the initial value. In addition, the learning conditions shown in FIG. 3 also include, for example, states st1 to st8 and actions ac1 to ac5 shown in Table 1.

[0041] The value Q will be explained using state st7 in Table 1 as an example. In state st7, the control deviation is greater than or equal to 3.0°C and less than 4.0°C, so the heating temperature of the target heater 14 is too high. Therefore, the output of the target heater 14 needs to be reduced. Therefore, as a result of learning by the control condition learning unit 72, the value Q of actions ac1 and ac2 that reduce the output to the heater 14 has increased. On the other hand, the value Q of actions ac4 and ac5 that increase the output to the heater 14 has decreased.

[0042] In the example of Table 1, when the control deviation is 3.5° C., for example, the state st is state st7. Therefore, the control condition learning unit 72 selects the optimal action ac2 in state st7, which has the maximum value Q, and outputs it to the control signal output unit 74. Based on the input action ac2, the control signal output unit 74 reduces the control signal ctr output to the heater 14 by 0.5%. The control signal ctr is, for example, a voltage signal.

[0043] If the absolute value of the next control deviation is smaller than the absolute value of the current control deviation, 3.5°C, the state observing unit 71 determines that the selection of action ac2 in the current state st7 is appropriate and outputs a positive reward rw. Therefore, the control condition learning unit 72 updates the control conditions so as to increase the value of action ac2 in state st7, +3.6, in accordance with the reward rw. As a result, in the case of state st7, the control condition learning unit 72 continues to select action ac2.

[0044] On the other hand, if the absolute value of the next control deviation is greater than the absolute value of the current control deviation, 3.5°C, the state observing unit 71 determines that the selection of action ac2 in the current state st7 is inappropriate and outputs a negative reward rw. Therefore, the control condition learning unit 72 updates the control conditions so as to reduce the value of action ac2 in state st7, +3.6, in accordance with the reward rw. As a result, if the value of action ac2 in state st7 becomes smaller than the value of action ac1, +2.6, the control condition learning unit 72 selects action ac1 instead of action ac2 in state st7.

[0045] The timing for updating the control conditions is not limited to the next update, and can be determined appropriately taking into account factors such as time lag. Furthermore, in the early stages of learning, the action ac can be selected randomly to promote learning. Furthermore, while Table 1 describes reinforcement learning using simple Q-learning, there are various learning algorithms available, including Q-learning, AC (Actor-Critic) learning, TD learning, and Monte Carlo methods, and the present invention is not limited to these. For example, if the number of states st and actions ac increases and a combinatorial explosion occurs, an AC method or other method can be used depending on the situation.

[0046] Furthermore, AC methods often use a probability distribution function as the policy function. This probability distribution function is not limited to a normal distribution function; for example, a sigmoid function or softmax function may be used for simplification. The sigmoid function is the function most commonly used in neural networks. Reinforcement learning is a type of machine learning, just like neural networks, so the sigmoid function can be used. Another advantage of the sigmoid function is that the function itself is simple and easy to handle. As described above, there are various learning algorithms and functions to use, but it is sufficient to select the most suitable one for the process.

[0047] As described above, the continuous mixer according to the second embodiment does not use PID control, so there is no need to adjust the PID control parameters when the process conditions change. Furthermore, the controller 70 updates the control conditions (learning results) based on the reward rw through reinforcement learning, and selects the optimal action ac corresponding to the current state st from the updated control conditions. Therefore, even when the process conditions are changed, the time and resin material required for adjustment can be reduced compared to the first embodiment.

[0048] <Method for controlling a continuous kneading device> Next, the control method for the continuous mixer according to the second embodiment will be described in detail with reference to Fig. 4. Fig. 4 is a flowchart showing the control method for the continuous mixer according to the second embodiment. In the description of Fig. 4, Fig. 3 will also be referred to as appropriate.

[0049] First, as shown in Fig. 4, the state observation unit 71 of the controller 70 shown in Fig. 3 calculates a control deviation for each heater 14 from the temperature measured by the corresponding temperature sensor 61. Then, based on the calculated control deviation, the current state st and a reward rw for a previously selected action ac are determined (step S1). Note that at the start of control, a previously selected action ac does not exist (for example, the last time), and therefore the reward rw cannot be determined, so only the current state st, i.e., the state at the start of control, is determined.

[0050] Next, as shown in Fig. 4, the control condition learning unit 72 of the controller 70 updates the control condition, which is a combination of the state st and the action ac, based on the reward rw. Then, the optimal action ac corresponding to the current state st is selected from the updated control conditions (step S2). Note that at the start of control, the control conditions remain at their initial values ​​and are not updated, but the optimal action ac corresponding to the state st at the time of control start is selected. Then, as shown in FIG. 4, the control signal output unit 74 of the controller 70 outputs a control signal ctr to the heater 14 based on the optimal action ac selected by the control condition learning unit 72 (step S3).

[0051] If the production of the resin molded product has not been completed (step S4 NO), the process returns to step S1 to continue the control. On the other hand, if the production of the resin molded product has been completed (step S4 YES), the process ends. That is, steps S1 to S3 are repeated until the production of the resin molded product is completed. The other configurations are the same as those in the first embodiment, and therefore the description will be omitted.

[0052] (Modification of the second embodiment) Next, a continuous kneading device according to a modified example of the second embodiment will be described with reference to Fig. 5. The overall configuration of the continuous kneading device according to the modified example of the second embodiment is similar to the overall configuration of the continuous kneading device according to the first embodiment shown in Fig. 1, and therefore description thereof will be omitted. The continuous kneading device according to the modified example of the second embodiment differs from the continuous kneading device according to the second embodiment in the configuration of the controller 70.

[0053] Fig. 5 is a block diagram showing the configuration of a controller 70 according to a modification of the second embodiment. As shown in Fig. 5, the controller 70 according to the modification of the second embodiment includes a state observing unit 71, a control condition learning unit 72, a storage unit 73, and a PID controller 74a. That is, the controller 70 according to the modification of the second embodiment includes the PID controller 74a as the control signal output unit 74 in the controller 70 according to the second embodiment shown in Fig. 3. The PID controller 74a is also one form of the control signal output unit.

[0054] As in the second embodiment, the state observing unit 71 determines the current state st and the reward rw for the previously selected action ac for each heater 14 based on the calculated control deviation err. Then, the state observing unit 71 outputs the current state st and the reward rw to the control condition learning unit 72. Furthermore, the state observing unit 71 according to the modification of the second embodiment outputs the calculated control deviation err to the PID controller 74a.

[0055] The control condition learning unit 72 also performs reinforcement learning for each heater 14, as in the second embodiment. Specifically, the control condition learning unit 72 updates the control conditions (learning results) based on the reward rw, and selects an optimal action ac corresponding to the current state st from the updated control conditions. Here, in the second embodiment, the content of the action ac selected by the control condition learning unit 72 is to directly change the output to the heater 14. In contrast, in the modified example of the second embodiment, the content of the action ac selected by the control condition learning unit 72 is to change the parameters of the PID controller 74a.

[0056] 5, the parameters of the PID controller 74a are successively changed based on the behavior ac output from the control condition learning unit 72. On the other hand, the PID controller 74a outputs a control signal ctr to the heater 14 based on the input control deviation err. The control signal ctr is, for example, a voltage signal. The other configurations are the same as those in the second embodiment, and therefore the description will be omitted.

[0057] As described above, the continuous mixer according to the modified example of the second embodiment uses PID control, and therefore parameter adjustment is required when process conditions change. In the continuous mixer according to the modified example of the second embodiment, the controller 70 uses reinforcement learning to update the control conditions (learning results) based on the reward rw, and selects an optimal action ac corresponding to the current state st from the updated control conditions. Here, the action ac in reinforcement learning is a change in the parameters of the PID controller 74a. Therefore, even when process conditions change, the time and resin material required for parameter adjustment can be reduced compared to the second embodiment.

[0058] (Third embodiment) <Configuration of continuous kneading equipment> Next, a continuous mixer according to a third embodiment will be described with reference to Fig. 6. Fig. 6 is a schematic cross-sectional view showing the configuration of a continuous mixer according to the third embodiment. As shown in Fig. 6, the continuous mixer according to this embodiment includes a temperature sensor 62 in addition to the cylinder 11, screw 12, hopper 13, heater 14, temperature sensor 61, and controller 70 shown in Fig. 1.

[0059] That is, the continuous mixer according to this embodiment has a configuration that combines the continuous mixer according to the first embodiment shown in Fig. 1 and the continuous mixer according to the comparative example shown in Fig. 2. In the continuous mixer according to this embodiment, the controller 70 is configured to be able to switch between a resin temperature control mode (first control mode) and a cylinder temperature control mode (second control mode).

[0060] In the resin temperature control mode, similar to the continuous kneading device according to the first embodiment shown in FIG. 1, the controller 70 feedback-controls the heating unit, i.e., the heater 14, based on the temperature of the molten resin 82 measured by the first temperature sensor 61.

[0061] On the other hand, in the cylinder temperature control mode, similar to the continuous kneading device according to the comparative example shown in FIG. 2, the controller 70 feedback controls the heater 14 based on the temperature of the heated portion of the cylinder 11 measured by the second temperature sensor 62.

[0062] In the continuous kneading device according to the first embodiment shown in FIG. 1, when the cylinder 11 is not filled with molten resin 82, such as when the continuous kneading device is started up, the temperature sensor 61 cannot measure the temperature of the molten resin 82, and the heater 14 cannot be feedback-controlled.

[0063] 6, when the cylinder 11 is not filled with the molten resin 82, the heater 14 can be feedback-controlled based on the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62. After the cylinder 11 is filled with the molten resin 82, the heater 14 can be feedback-controlled based on the temperature of the molten resin 82 measured by the temperature sensor 61. The other configurations are the same as those of the first embodiment, and therefore description thereof will be omitted. Also, the third embodiment and the second embodiment may be combined.

[0064] <Method for controlling a continuous kneading device> Next, details of a control method for a continuous kneading device according to a third embodiment will be described with reference to Figs. 7 to 9. Fig. 7 is a flowchart showing a control method for a continuous kneading device according to a third embodiment. Fig. 8 is a schematic cross-sectional view of a continuous kneading device in a cylinder temperature control mode. Fig. 9 is a schematic cross-sectional view of a continuous kneading device in a resin temperature control mode. In the description of Fig. 7, Figs. 8 and 9 will be referred to as appropriate.

[0065] First, as shown in Fig. 7, after starting up the continuous kneading device, the cylinder temperature control mode is started (step S11). As shown in Fig. 8, in the cylinder temperature control mode, the controller 70 feedback-controls the heater 14 based on the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62.

[0066] Next, if the temperature of the cylinder 11 reaches the target temperature (YES in step S12), raw material, i.e., resin pellets 81, is charged into the cylinder 11, and the rotation of the screw 12 is started (step S13) while continuing the cylinder temperature control mode. On the other hand, if the temperature of the cylinder 11 does not reach the target temperature (NO in step S12), raw material is not charged into the cylinder 11, and the cylinder temperature control mode continues as is.

[0067] Here, in the cylinder temperature control mode, if the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62 exceeds a predetermined upper limit temperature, the controller 70 may output an alarm. Also, if the deviation between the target temperature of the cylinder 11 and the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62 exceeds a predetermined upper limit value, the controller 70 may output an alarm.

[0068] Although not particularly limited, an alarm may be expressed by, for example, characters, symbols, figures, sounds, a combination thereof, etc. When an alarm is expressed by characters, symbols, figures, etc., it is displayed on a display unit (not shown) such as a monitor.

[0069] Next, after step S13, when the inside of the cylinder 11 is filled with the molten resin 82, the cylinder temperature control mode is switched to the resin temperature control mode. That is, the resin temperature control mode is started (step S14). As shown in Fig. 9, in the resin temperature control mode, the controller 70 feedback-controls the heating unit, i.e., the heater 14, based on the temperature of the molten resin 82 measured by the temperature sensor 61.

[0070] Next, if the temperature of the molten resin 82 is within the appropriate range (YES in step S15), the resin temperature control mode is continued and the production of the resin molded product, i.e., the product, is started (step S16). On the other hand, if the temperature of the molten resin 82 is not within the appropriate range (NO in step S15), the resin temperature control mode is continued as is without starting the production of the resin molded product, i.e., the product.

[0071] Here, even in the resin temperature control mode, if the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62 exceeds a predetermined upper limit temperature, the controller 70 may output an alarm.

[0072] (Modification of the third embodiment) Next, a continuous mixer according to a modified example of the third embodiment will be described with reference to Fig. 10. The overall configuration of the continuous mixer according to the modified example of the third embodiment is similar to the overall configuration of the continuous mixer according to the third embodiment shown in Fig. 6, and therefore description thereof will be omitted.

[0073] As shown in Figure 10, in the continuous kneading device of the modified example, in the resin temperature control mode, the controller 70 performs cascade control using not only the resin temperature measured by the temperature sensor 61 but also the temperature of the cylinder 11 measured by the temperature sensor 62.

[0074] More specifically, first, the controller 70 determines the set temperature of the heater 14 based on the temperature of the molten resin 82 measured by the temperature sensor 61. For example, the controller 70 determines the set temperature of the heater 14 based on the deviation between the target resin temperature and the temperature of the molten resin 82 measured by the temperature sensor 61.

[0075] Next, the controller 70 feedback-controls the heater 14 based on the determined set temperature and the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62. For example, the controller 70 feedback-controls the heater 14 based on the deviation between the determined set temperature and the temperature of the heated portion of the cylinder 11 measured by the temperature sensor 62.

[0076] In the continuous mixer according to the modification of the third embodiment, the temperature of the discharged molten resin 82 can be controlled more accurately by the above-mentioned cascade control than in the continuous mixer according to the third embodiment. As a result, the time and resin material required to stabilize the quality of the molded resin can be further reduced. The other configurations are the same as those of the third embodiment, and therefore description thereof will be omitted. Also, the modified example of the third embodiment may be combined with the second embodiment.

[0077] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the embodiments already described, and various modifications are possible within the scope of the gist of the invention. [Explanation of symbols]

[0078] 11 cylinders 11a Discharge port 12 screws 13 Hopper 14 Heater 61, 62 Temperature sensor 70 Controller 71 Status Observation Unit 72 Control condition learning section 73 Memory section 74 Control signal output section 74a PID controller 81 Resin pellets 82 Molten Resin

Claims

1. a cylinder into which resin pellets are fed; a screw housed in the cylinder and kneading the resin pellets; a heating unit provided to cover an outer peripheral surface of the cylinder and configured to heat the resin pellets; a first temperature sensor provided in the cylinder for measuring a temperature of the molten resin obtained by melting the resin pellets; a controller that feedback-controls the heating unit based on the temperature of the molten resin measured by the first temperature sensor, Continuous kneading equipment.

2. the first temperature sensor is provided in the cylinder between the tip of the screw and the discharge port; The continuous kneading apparatus according to claim 1 .

3. a second temperature sensor for measuring the temperature of a portion of the cylinder heated by the heating unit; The controller an alarm is output when the temperature of the heated portion measured by the second temperature sensor exceeds a predetermined upper limit temperature; The continuous kneading apparatus according to claim 1 .

4. a second temperature sensor for measuring the temperature of a portion of the cylinder heated by the heating unit; The controller a first control mode in which the heating unit is feedback-controlled based on the temperature of the molten resin measured by the first temperature sensor; a second control mode in which the heating unit is feedback-controlled based on the temperature of the heating portion measured by the second temperature sensor; The continuous kneading apparatus according to claim 1 .

5. In the first control mode, determining a set temperature of the heating unit based on the temperature of the molten resin measured by the first temperature sensor; determining an output of the heating unit based on the set temperature and the temperature of the heating portion measured by the second temperature sensor; The continuous kneading apparatus according to claim 4.

6. When the continuous kneading device is started, the controller executes the second control mode and then executes the first control mode; The continuous kneading device according to claim 4 or 5.

7. the heating unit is composed of a plurality of annular heaters arranged along the longitudinal direction of the cylinder, the second temperature sensor is provided for each of the plurality of annular heaters; The continuous kneading device according to claim 3 or 4.

8. a cylinder into which resin pellets are fed; a screw housed in the cylinder and kneading the resin pellets; a heating unit provided to cover an outer peripheral surface of the cylinder and configured to heat the resin pellets; a first temperature sensor provided in the cylinder and configured to measure a temperature of the molten resin obtained by melting the resin pellets, (a) feedback-controlling the heating unit based on the temperature of the molten resin measured by the first temperature sensor; A method for controlling a continuous kneading device.

9. the first temperature sensor is provided in the cylinder between the tip of the screw and the discharge port; A method for controlling a continuous kneading apparatus according to claim 8.

10. the continuous kneading device further includes a second temperature sensor that measures the temperature of the portion of the cylinder heated by the heating unit; In the step (a), an alarm is output when the temperature of the heated portion measured by the second temperature sensor exceeds a predetermined upper limit temperature. A method for controlling a continuous kneading apparatus according to claim 8.

11. the continuous kneading device further includes a second temperature sensor that measures the temperature of the portion of the cylinder heated by the heating unit; (b) feedback-controlling the heating unit based on the temperature of the heating portion measured by the second temperature sensor; A method for controlling a continuous kneading apparatus according to claim 8.

12. In the step (a), determining a set temperature of the heating unit based on the temperature of the molten resin measured by the first temperature sensor; determining an output of the heating unit based on the set temperature and the temperature of the heating portion measured by the second temperature sensor; The method for controlling the continuous kneading device according to claim 11.

13. When the continuous kneading device is started, the step (b) is carried out, and then the step (a) is carried out. A method for controlling the continuous kneading apparatus according to claim 11 or 12.

14. In the continuous kneading apparatus, the heating unit is composed of a plurality of annular heaters arranged along the longitudinal direction of the cylinder, the second temperature sensor is provided for each of the plurality of annular heaters; A method for controlling the continuous kneading apparatus according to claim 10 or 11.

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