JP7764818B2 - Kneading device and kneading method - Google Patents

Description

The present invention relates to a kneading device and a kneading method.

For example, the desired material is produced by mixing (kneading) viscous resins such as pre-crosslinked rubber or plastic with various additives and compounding agents (fillers) using a kneading device such as a batch mixer/kneader.

Patent Document 1 discloses flow analysis of kneaded materials.

Japanese Patent Application Laid-Open No. 2018-161853

However, if the mixing conditions are not properly controlled, the mixing may not go well and may even fail.

The present invention therefore aims to provide a kneading device and kneading method that can reduce kneading failures.

In order to solve the above-mentioned problems, the present invention provides a kneading device that mixes a resin and a filler to obtain a kneaded product, comprising a kneader having a temperature sensor that can detect the temperature of the kneaded product and a rotation sensor that can detect the rotor rotation speed, and a kneader control unit that controls the kneader. The kneader control unit has a tensile strength estimation processing unit that estimates the tensile strength of the kneaded product based on the temperature of the kneaded product detected by the temperature sensor and the rotor rotation speed detected by the rotation sensor, and a kneading condition control processing unit that controls the kneading conditions of the kneader so as to minimize the deviation between the tensile strength estimated by the tensile strength estimation processing unit and a target tensile strength, which is a preset target value for the change in tensile strength of the kneaded product over time from the start of kneading.

The present invention also aims to solve the above-mentioned problems by providing a kneading method for mixing a resin and a filler to obtain a kneaded product, which uses a kneading machine having a temperature sensor capable of detecting the temperature of the kneaded product and a rotation sensor capable of detecting the rotor rotation speed, estimates the tensile strength of the kneaded product based on the temperature of the kneaded product detected by the temperature sensor and the rotor rotation speed detected by the rotation sensor, and controls the kneading conditions of the kneading machine so as to minimize the deviation between the estimated tensile strength and a target tensile strength, which is a preset target value for the change in tensile strength of the kneaded product over time from the start of kneading.

The present invention provides a kneading device and kneading method that can reduce kneading failures.

1 is a schematic configuration diagram of a kneading device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the kneading process. 1 is a graph showing both the measured values of tensile strength S and the calculated values of tensile strength S. 1 is a flow diagram of a kneading method according to an embodiment of the present invention. 1A is a flow diagram of a test manufacturing data acquisition process, FIG. 1B is a flow diagram of a relationship derivation process, and FIG. 1C is a flow diagram of a prerequisite data acquisition process. FIG. 10 is a flow diagram of a tensile strength estimation process. FIG. 10 is a flowchart of a kneading failure determination process. FIG. 10 is a flow diagram of a kneading condition control process. FIG. 10 is a graph showing an example of setting a target tensile strength and the change in the tensile strength of the kneaded material over time when this setting example is used.

[Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

Figure 1 is a schematic diagram of a kneading device 1 according to this embodiment. As shown in Figure 1, the kneading device 1 according to this embodiment is an apparatus that mixes resin and filler with a rotor to obtain a kneaded product, and includes a kneader 10 and a kneader control unit 11 that controls the kneader 10.

The kneader 10 is, for example, a batch kneader, and is configured to mix the resin and filler using a rotor that rotates within a kneading chamber. The kneader 10 is configured so that the temperature of the kneaded material and the rotor rotation speed, which is the rotation speed of the rotor, can be set, and is configured to be driven according to the set values of the temperature of the kneaded material and the rotor rotation speed.

The kneading machine 10 also has a temperature sensor 101 that can detect the temperature of the material to be kneaded, and a rotation sensor 102 that can detect the rotor rotation speed. The temperature of the material to be kneaded can be substituted by the temperature of the kneading chamber. In this embodiment, a sensor that detects the temperature of the kneading chamber is used as the temperature sensor 101.

The mixer control unit 11 has a control unit 2, a memory unit 3, a display unit 4, and an input device 5. In this embodiment, the mixer control unit 11 is configured as a personal computer.

The control unit 2 is realized by appropriately combining a CPU or other computing element, memory, interface, software, storage device, etc. In this embodiment, the control unit 2 has a setting processing unit 21, a data acquisition processing unit 22, a relationship derivation processing unit 23, a tensile strength estimation processing unit 24, a kneading condition control processing unit 25, and a kneading failure determination processing unit 26. Details of each unit will be described later.

The storage unit 3 is realized by a predetermined storage area of a memory or storage device. The display unit 4 is, for example, an LCD display, and the input device 5 is, for example, a keyboard or a mouse. The display unit 4 may be configured as a touch panel and also serve as the input device 5. The display unit 4 and input device 5 may also be configured separately from the mixer control unit 11 and configured to be able to communicate with the mixer control unit 11 via wireless communication or the like. In this case, the display unit 4 or input device 5 may be configured as a mobile terminal such as a tablet or smartphone.

(Materials to be mixed)
Although details will be described later, this embodiment formulates a process in which, as the kneading proceeds, the powdered filler gradually disperses in the resin, which is a fluid material, to form a uniform kneaded product. Therefore, this embodiment basically assumes the case in which a resin (polymer) and a powdered filler are mixed together.

Furthermore, according to the results of the inventors' research, better mixing results can be obtained when a material whose main component is a flame retardant is used as the filler. In other words, the present invention is particularly effective when a material whose main component is a flame retardant is used as the filler. Examples of flame retardants include antimony oxide, aluminum hydroxide, magnesium hydroxide, and zinc borate.

Furthermore, according to the results of the inventors' research, it was found that better mixing results can be obtained when 150 to 300 parts by mass of filler are used per 100 parts by mass of resin (plastic material). In other words, the present invention is particularly effective when 150 to 300 parts by mass of filler are used per 100 parts by mass of resin.

The materials used for kneading may also include a cross-linking aid such as trimethylolpropane acrylate (TMPT).

(Parameters that serve as indicators of the progress of kneading)
As a result of investigations, the inventors of the present invention have found that there is a very strong correlation between the degree of kneading and the tensile strength of the kneaded product. For example, when kneading is not progressing, the resin and powder (filler) are mixed in a mottled state, resulting in a low tensile strength of the kneaded product. Furthermore, as kneading progresses, the powder (filler) is crushed into smaller pieces, increasing the contact area between the powder (filler) and the resin, and increasing the tensile strength of the kneaded product. When the powder (filler) is completely and uniformly dispersed in the resin through kneading, the tensile strength reaches its maximum value and saturates. Therefore, in this embodiment, the tensile strength of the kneaded product is used as a parameter that serves as an indicator of the degree of kneading.

As shown in Figure 2, kneading can be divided into two stages: the mixing process and the dispersion process. In the mixing process, after preheating the kneader 10, only the resin (polymer) is added and melted. Then, powdered filler is added in two batches and stirred until a predetermined temperature or time is reached, integrating the resin and filler. In the subsequent dispersion process, the mixture is kneaded until it becomes uniform. The filler is then finely crushed and dispersed within the resin, resulting in a uniform distribution of the filler within the resin.

In this embodiment, the progress of the kneading in the dispersion process (i.e., how uniformly the filler is dispersed in the resin) is estimated from changes in the tensile strength of the kneaded product.

(Formulation of tensile strength of kneaded material)
The inventors have formulated the tensile strength of a kneaded material based on thermo-fluid dynamics and structural mechanics. More specifically, in this embodiment, the tensile strength S is calculated by equation (1) shown in [Mathematical Expression 1]. The derivation of this equation (1) will be described below.

During the dispersion process, the domain size L of the filler-rich phase becomes smaller due to the force F applied by the fluid (resin). Therefore, the amount of reduction in filler domain size ΔL is assumed to be proportional to the force F applied by the fluid. The filler-rich phase refers to a region containing 10% or more filler (metal powder), and can be obtained by analysis such as EDX. The domain size L of the filler-rich phase is the characteristic length of the filler-rich phase, such as the maximum width of the filler-rich phase. The amount of reduction in filler domain size ΔL refers to the amount of reduction in domain size L per kneading time Δt.

Here, it is known that the force F is proportional to the product of the shear stress τ and the square of the domain size L. The shear stress τ is expressed as the product of the material viscosity η and the shear rate γ. As the kneading progresses, the domain size L decreases, but there is a limit to how small the domain size L can be, and it can be considered that it converges to a minimum domain size L _min . In summary, the change in domain size dL(t)/dt can be expressed by equation (2) shown in [Mathematical Expression 2].

Here, it is assumed that the tensile strength S of the kneaded material is proportional to the surface area of the domain of the filler-rich phase (a function of ^L2 ) and inversely proportional to the volume of the domain (a function of ^L3 ). Then, as shown in the following formula (3), the tensile strength S of the kneaded material is inversely proportional to the domain size L(t), where a is a constant.
S(t)=a/{L(t)}...(3)
As shown in the above formula (3), the more uniformly the filler is distributed and dispersed and the smaller the domain size, the greater the tensile strength S of the kneaded product. If the tensile strength S of the kneaded product when the domain size is the minimum domain size L _min is defined as the maximum tensile strength S _max of the kneaded product, the relationship of the following formula (4) is obtained.
S _max =a/L _min ...(4)
By substituting the relationship between these equations (3) and (4) into the above equation (2), the equation (5) shown in [Equation 3] is obtained.

Here, the material viscosity η in equation (5) above is expressed by equation (6) shown in [Equation 4]. When calculating material viscosity η, the power law is used, taking into account the non-Newtonian nature of the material's flow. Furthermore, the relationship between shear rate γ and rotor rotation speed can be expressed by equation (7) shown in [Equation 5]. The shear rate coefficient k in equation (7) is a coefficient that depends on the shape of the kneading machine 10 (shape of the kneading chamber and rotor, clearance between the kneading chamber and rotor, etc.), and can be determined in advance by conducting experiments.

Substituting these equations (6) and (7) into equation (5) above and rearranging, we obtain equation (1) shown in [Equation 6].

The coefficient A in the above formula (1) is determined in advance by carrying out test production of a kneaded product under different kneading conditions, and performing fitting using the various data obtained. In this case, the viscosity constant η ₀ , temperature coefficient α, and power exponent n can be obtained by measuring the viscosity of the kneaded product using a capillary rheometer or the like (the power exponent n may be a fixed value based on experiments or experience). The temperature T of the kneaded product may be obtained by actual measurement, or by solving a thermo-fluid dynamics equation. The tensile strength S of the kneaded product can be obtained by taking a portion of the kneaded product, forming it into a sheet, and performing a tensile test. The largest tensile strength S obtained after sufficient kneading is the maximum tensile strength S _max .

By determining coefficient A in advance through fitting, it is possible to use the above equation (1) to determine the current tensile strength S of the kneaded material based on the actual measured values of rotor rotation speed N and temperature T of the kneaded material, and the initial value of tensile strength S, and to estimate the progress of kneading.

Figure 3 is a graph showing both the measured values of tensile strength S (black circles) and the calculated values of tensile strength S (solid line) obtained using equation (1) above. In the example shown in Figure 3, 100 parts by mass of ethylene vinyl acetate was used as the resin, and 200 parts by mass of magnesium hydroxide was used as the filler. The kneading machine 10 was a small kneader with a mixing capacity of 6 liters and a two-blade rotor. During kneading, the resin alone was first kneaded and melted, and then the filler was added in two batches and pre-mixed. Pre-mixing was terminated when the temperature T of the kneaded product reached 100°C. The rotor rotation speed N was then set to a predetermined value, and kneading was continued until the temperature T of the kneaded product reached 150°C.

Samples of the kneaded material were then taken from the kneading chamber when the temperature T of the kneaded material was 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and 150°C. The samples were pressed into sheets and irradiated with an electron beam at a dose of 7 Mrad to crosslink the polymer. The sheet samples (1 mm thick) were then punched into the shape of a No. 6 dumbbell and subjected to a tensile test (tensile speed: 250 mm/min) to measure the tensile strength S.

As shown in FIG. 3, the measured and calculated values of tensile strength S closely match, indicating that the tensile strength S can be accurately evaluated using the above formula (1). More specifically, the squared value R2 of the coefficient of determination (correlation coefficient), which indicates the magnitude of correlation between the measured and calculated values of tensile strength S, was a very large value of 0.995. Note that FIG. 3 also shows the time-integrated value of shear stress (dashed line), which has been conventionally used, and the squared value ^R2 of the coefficient of determination (correlation coefficient) for the measured value of tensile strength ^S was a small value of 0.598. From this, it can be said that the present embodiment can evaluate the tensile strength S with higher accuracy than the conventional method. Furthermore, as shown in FIG. 3, the tensile strength S saturates as the kneading progresses, and it can be seen that the progress of kneading can be estimated based on how close the tensile strength S is to its maximum value.

(Setting processing unit 21)
Returning to Fig. 1, each part of the control unit 2 will be described in detail. The setting processing unit 21 performs setting processing for making various settings of the mixer control unit 11. The setting processing unit 21 can set information related to various controls, such as the method of data acquisition by the data acquisition processing unit 22 and the setting of the data acquisition date and time. The setting processing unit 21 can also register, update, delete, etc., various pieces of information stored in the memory unit 3. The input device 5, etc. can be used to input various pieces of information.

(Data acquisition processing unit 22)
The data acquisition processing unit 22 performs a test production data acquisition process (see FIG. 5( a) ) to acquire various data obtained in the test production (sometimes collectively referred to as test production data) and store them in the storage unit 3. The data acquisition processing unit 22 associates the acquired various data with each sample and registers them in the test production database 31. In this embodiment, the data acquisition processing unit 22 acquires kneading condition data 61, which is data related to the kneading conditions including the rotor rotation speed N; temperature data 62, which is data related to the temperature including the temperature T of the kneaded material; viscosity data 63, which is data related to the viscosity including the viscosity constant η ₀ , the temperature coefficient _α , the power exponent n, etc.; and tensile strength data 64, which is data related to the tensile strength S and its maximum value S max. These various data may be input via the input device 5 or may be input from an external device via a network or the like. Some of the data may be acquired directly from the kneading machine 10. The data acquisition processing unit 22 may receive data other than those described above, and the test production database 31 may include data other than those described above. The data acquisition processing unit 22 may also have a function of presenting missing data, such as displaying missing data among various data on the display device 4 .

The data acquisition processing unit 22 also performs a prerequisite data acquisition process (see FIG. 5(c)) that receives data including initial value data 33, target tensile strength data 34, and failure judgment threshold data 35. These data are prerequisites for the tensile strength estimation process and kneading condition control process described below, and are therefore sometimes collectively referred to as prerequisite data. Here, the initial value data 33 refers to the set values for the temperature T of the kneaded material, the rotor rotation speed N, and the initial value of the tensile strength S of the kneaded material. The target tensile strength data 34 refers to the target tensile strength Si, which is a preset target value for the change in the tensile strength S of the kneaded material over time from the start of kneading, and is used by the kneading condition control processing unit 25 described below. The failure judgment threshold data 35 refers to the failure judgment threshold, which is the allowable value for the deviation ΔS between the tensile strength S and the target tensile strength Si, and is used by the kneading failure judgment processing unit 26 described below to determine whether kneading has failed.

(Relationship derivation processing unit 23)
The relationship derivation processing unit 23 performs a relationship derivation process (see FIG. 5( b)) to determine the relationship between the kneading conditions and the change in tensile strength S of the kneaded product based on the actual measurement values obtained in the test production, i.e., the various data registered in the test production database 31.

More specifically, the relationship derivation processing unit 23 applies each piece of data in the test manufacturing database 31 to the above equation (1) to derive the coefficient A in equation (1). The obtained coefficient A is stored in the memory unit 3 as coefficient data 32.

(Tensile strength estimation processing unit 24)
The tensile strength estimation processing unit 24 performs a tensile strength estimation process (see FIG. 6( a)) to estimate the tensile strength S of the kneaded material at the current time based on the temperature T of the kneaded material detected by the temperature sensor 101 during kneading and the rotor rotation speed N detected by the rotation sensor 102. In the tensile strength estimation process, the tensile strength S of the kneaded material at the current time is calculated in real time by the above formula (1) using the actual measured values of the temperature T of the kneaded material and the rotor rotation speed N when kneading is actually performed. The actual measured values of the temperature T of the kneaded material and the rotor rotation speed N, together with the time at which the actual measurements were performed (i.e., the kneading time), are stored in the memory unit 3 as actual measurement data 36. The tensile strength S calculated in the tensile strength estimation process is stored in the memory unit 3 together with the kneading time as estimated tensile strength data 37. Note that the "current time" means the time point of the current kneading time t. The measurement intervals for the temperature T of the kneaded material and the rotor rotation speed N, that is, the time intervals for estimating the tensile strength S, may be, for example, 10 seconds or more and 20 seconds or less.

(Kneading condition control processing unit 25)
The kneading condition control processing unit 25 calculates a deviation ΔS between the current target tensile strength Si and the tensile strength S of the kneaded product estimated by the tensile strength estimation processing unit 24 based on a preset target tensile strength Si (stored in the storage unit 3 as target tensile strength data 34 in this embodiment), and performs a kneading condition control process (see FIG. 6( b)) to control the kneading conditions of the kneader 10 so as to reduce the deviation ΔS. The deviation ΔS is the absolute value of the difference between the current tensile strength S obtained by the tensile strength estimation processing unit 24 and the current target tensile strength Si. In this embodiment, the kneading condition control processing unit 25 controls the set values of the temperature T of the kneaded product and the rotor rotation speed N as the kneading conditions.

In this embodiment, the kneading condition control processing unit 25 is configured to maintain the current kneading conditions when the deviation ΔS is equal to or smaller than a preset deviation threshold ΔS _th , and to control the kneading conditions of the kneader 10 so as to reduce the deviation ΔS when the deviation ΔS is greater than the deviation threshold ΔS _th . This is because the response when the kneading conditions (the set values of the temperature T of the kneaded material and the rotor rotation speed N) are changed is relatively slow, and therefore, if the kneading conditions are controlled too precisely, the tensile strength S of the kneaded material may deviate significantly from the target tensile strength Si. Note that the response is particularly slow when the set value of the temperature T of the kneaded material is changed (it takes time for the actual temperature of the kneaded material to match the set value (temperature T)), so it is desirable to configure the kneading condition control processing unit 25 to control the set value of the rotor rotation speed N with priority.

The kneading condition control processing unit 25 may control the kneading conditions (set values for the temperature T of the kneaded material and the rotor rotation speed N) using PID control. PID control is a combination of P (proportional control), I (integral control), and D (differential control), and suppresses vibrations and overshoots of the tensile strength S relative to the target tensile strength Si, enabling high-speed, stable control.

Incidentally, if the set value of the kneaded material temperature T or the set value of the rotor rotation speed N is set too high, it is possible that the load on the heater and rotor of the kneader 10 will increase, shortening their lifespan. For this reason, maximum allowable values may be set for the set values of the kneaded material temperature T and the rotor rotation speed N, and only values smaller than the maximum values may be set. In other words, a settable numerical range may be set in advance for the set values of the kneaded material temperature T and the rotor rotation speed N. The kneading condition control processing unit 25 stores the set values of the kneaded material temperature T and the rotor rotation speed N determined by PID control or the like in the memory unit 3 as set value data 38 and outputs them to the kneader 10 to control the kneader 10.

In this embodiment, the mixer control unit 11 is provided separately from the mixer 10 and is capable of communicating with each other, but this is not limiting; the mixer control unit 11 may also be provided integrally with the mixer 10. In this case, the mixer condition control processing unit 25 may be configured to directly control the heater and rotor so that the temperature T of the mix and the rotor rotation speed N reach the set values determined by PID control or the like.

(Kneading failure determination processing unit 26)
The kneading failure determination processor 26 performs a kneading failure determination process (see FIG. 8 ) for determining a kneading failure. In the kneading failure determination process, the deviation ΔS between the current tensile strength S and the target tensile strength Si is compared with a failure determination threshold preset as failure determination threshold data 35 to determine a kneading failure. In this embodiment, the kneading failure determination processor 26 determines a kneading failure when the deviation ΔS remains greater than the preset failure determination threshold for a predetermined period of time. More specifically, the kneading failure determination processor 26 determines that the kneading has failed when the number of consecutive times that the deviation ΔS is determined to be greater than the preset failure determination threshold is equal to or greater than a preset failure determination count. The failure determination count can be set, for example, in the range of 3 to 10 times. This kneading failure determination process is based on the inventors' finding that if the deviation ΔS remains relatively large for a long period of time, there is a high possibility that the kneaded material will not reach the desired tensile strength (the tensile strength Sg at which kneading is determined to be complete (see FIG. 9 )).

In this embodiment, the failure determination threshold is set to the same value as the deviation threshold ΔS _th . However, the failure determination threshold may be a value different from the deviation threshold ΔS _th . In this case, the failure determination threshold should be set to a value greater than the deviation threshold ΔS _th .

Furthermore, when the kneading failure determination processing unit 26 determines that kneading has failed, it issues an alarm (alert) and stops the kneader 10 to stop kneading. The specific method for issuing the alarm is not particularly limited, but the alarm may be issued by light or sound, or by sending an email to an administrator or displaying an alarm screen on the display unit 4. The alarm can be stopped by pressing a reset button (not shown) or by sending a predetermined reset signal.

(Kneading method)
Fig. 4 is a flow diagram of the kneading method according to this embodiment. As shown in Fig. 4, first, in step S1, a setting process is performed. In the setting process, for example, setting value data 38 is input from the input device 5 or the like, and the setting processing unit 21 performs various settings according to the input setting value data 38, data update processes associated with the various settings, and the like.

In this embodiment, prior to kneading, a test production is conducted in which the kneaded product is produced by changing the kneading conditions, and the relationship between the tensile strength S and the kneading conditions is derived based on the results of the test production. First, the kneading condition data 61, temperature data 62, viscosity data 63, and tensile strength data 64 obtained in the test production are input as test production data from the input device 5 or the like (step S21).

In step S2, the control unit 2 determines whether test production data has been input. If step S2 returns No (N), the process returns (returns to step S1). If step S2 returns Yes (Y), the process performs test production data acquisition processing in step S3. In the test production data acquisition processing, as shown in FIG. 5(a), in step S31, the data acquisition processing unit 22 receives the kneading condition data 61, temperature data 62, viscosity data 63, and tensile strength data 64 input as test production data, and in step S32, registers each received data in the test production database 31 and stores it in the memory unit 3. Thereafter, the process returns and proceeds to step S4 in FIG. 4.

In step S4, a relationship derivation process is performed. In the relationship derivation process, as shown in FIG. 5(b), first, in step S41, each piece of data in the test manufacturing database 31 is applied to the above equation (1) to perform fitting and derive coefficient A. Then, in step S42, the derived coefficient A is stored in the memory unit 3 as coefficient data 32. Then, the process returns and proceeds to step S5 in FIG. 4. Note that steps S2 to S4 above can be omitted if coefficient A is known.

Next, when actually performing kneading, the initial value data 33, target tensile strength data 34, and failure judgment threshold data 35 are first input as prerequisite data from the input device 5 or the like (step S22). Then, in step S5, the control unit 2 determines whether the prerequisite data has been input. If the determination in step S2 is No (N), the process returns to step S5 (waits until the prerequisite data is input). If the determination in step S5 is Yes (Y), the process proceeds to step S6.

In step S6, a prerequisite data acquisition process is performed. In the prerequisite data acquisition process, as shown in FIG. 5(c), first, in step S61, the data acquisition processing unit 22 receives the initial value data 33, target tensile strength data 34, and failure judgment threshold data 35 input as prerequisite data, and in step S62, stores the received data in the memory unit 3. Note that the prerequisite data may include various data such as the maximum values of the temperature T of the kneaded material and the rotor rotation speed N, measurement intervals, and the number of failure judgments. Thereafter, the process returns and proceeds to step S7 in FIG. 4.

In step S7, the mixing process is performed. The mixing process is a process in which the resin and filler are mixed and integrated before kneading (see Figure 2). The control unit 2 preheats the kneader 10 and stirs the added resin and filler at a predetermined temperature for a predetermined time, thereby integrating the resin and filler. In this embodiment, only the resin is added and melted, and then the filler is added in two batches. After the mixing process in step S7 is completed, kneading begins, and the initial value 0 (zero) is assigned to the variable n used to determine whether kneading has failed (step S8), after which the process proceeds to step S9.

In step S9, a tensile strength estimation process is performed. As shown in FIG. 6, in the tensile strength estimation process, first, in step S91, the tensile strength estimation processing unit 24 receives actual measurement data 36, which are actual measurement values of the temperature T and rotor rotation speed N of the kneaded material, from the temperature sensor 101 and rotation sensor 102 of the kneading machine 10. In step S92, the received actual measurement data 36 is stored in the memory unit 3 together with the time of actual measurement. Then, in step S93, the current tensile strength S of the kneaded material (at the time when the temperature T and rotor rotation speed N were actually measured) is calculated using the above equation (1) based on the actual measurement data 36. Then, in step S94, the calculated tensile strength S of the kneaded material is stored in the memory unit 3 as estimated tensile strength data 37 together with the kneading time. Then, the process returns and proceeds to step S10 in FIG. 4.

In step S10, it is determined whether kneading has been completed. In this embodiment, kneading is determined to be completed when the tensile strength S is equal to or greater than a preset tensile strength Sg (for example, a value equal to or greater than 99% of the maximum tensile strength S _max ) that is used to determine that kneading has been completed. If the determination in step S10 is Yes (Y), the kneader is stopped in step S11, and the process is then terminated. If the determination in step S10 is No (N), the process proceeds to step S12.

In step S12, a deviation ΔS between the tensile strength S of the kneaded product at the current time and the target tensile strength Si at the current time is calculated. Thereafter, in step S13, a kneading failure determination process is performed. In the kneading failure determination process, as shown in FIG. 7, first, in step S131, it is determined whether the deviation ΔS is greater than a failure determination threshold (here, ΔS _th ). If the determination in step S131 is No (N), in step S132, 0 (zero) is assigned to variable n (variable n is reset), and then the process returns and proceeds to step S14 in FIG. 4. If the determination in step S131 is Yes (Y), in step S133, variable n is incremented, and in step S134, it is determined whether variable n is greater than a preset failure determination count n _th . If the determination in step S134 is No (N), the process returns and proceeds to step S14 in FIG. 4. If the determination in step S134 is Yes (Y), it is determined that mixing has failed in step S135, an alarm is issued in step S136, and then the mixer 10 is stopped and the process is terminated (interrupted) in step S137. The alarm can be stopped by pressing a reset button (not shown) or by transmitting a predetermined reset signal.

In step S14, a kneading condition control process is performed. In the kneading condition control process, as shown in FIG. 8, first, in step S141, it is determined whether the current deviation ΔS is greater than the deviation threshold value ΔS _th . If the determination in step S141 is Yes (Y), in step S142, the set value of the temperature T of the kneaded material and the set value of the rotor rotation speed N are determined by PID control or the like according to the deviation ΔS, and stored in the memory unit 3 as set value data 38, and then the process proceeds to step S144. If the determination in step S141 is No (N), in step S143, the current set value of the temperature T of the kneaded material and the set value of the rotor rotation speed N are stored in the memory unit 3 as set value data 38, and then the process proceeds to step S144. In step S144, the set value data 38 is output to the kneader 10, and each set value of the kneader 10 is controlled. Thereafter, the process returns to step S9 of FIG. 4.

(Examples of target tensile strength Si and tensile strength S)
9 is a graph showing an example of setting the target tensile strength Si (dashed line) and the time change (solid line) of the tensile strength S of the kneaded product when this setting example is used. As shown in FIG. 9, the tensile strength S of the kneaded product calculated based on the actually measured temperature T of the kneaded product and the rotor rotation speed N closely follows the target tensile strength Si, and it can be seen that kneading is performed efficiently. The graph of the target tensile strength Si in FIG. 9 corresponds to the target tensile strength data 34. The graph of the time change of the tensile strength S of the kneaded product in FIG. 9 corresponds to the estimated tensile strength data 37.

(Functions and Effects of the Embodiments)
As described above, the kneading device 1 according to this embodiment includes a tensile strength estimation processing unit 24 that estimates the tensile strength S of the kneaded material at the current time (the time when the temperature T and the rotor rotation speed N are detected) based on the temperature T of the kneaded material detected by the temperature sensor 101 and the rotor rotation speed N detected by the rotation sensor 102, and a kneading condition control processing unit 25 that calculates the deviation ΔS between the current target tensile strength Si and the tensile strength S of the kneaded material at the current time estimated by the tensile strength estimation processing unit 24 based on a preset target tensile strength Si, and controls the kneading conditions of the kneader 10 so as to reduce the deviation ΔS.

This makes it possible to control the kneading conditions so that the change in the tensile strength S of the kneaded product (i.e., the progress of kneading) over time is as desired, thereby preventing kneading failures.

(Modification)
Although not mentioned in the above embodiment, a plurality of patterns of time-varying changes in the target tensile strength Si may be stored as the target tensile strength data 34, and the user may select which pattern to use. Also, the time-varying changes in the target tensile strength Si may be automatically generated by appropriately setting conditions such as the type of resin and the kneading time.

The mixer control unit 11 may also have a display control unit capable of displaying each piece of data, such as actual measurement data 36, estimated tensile strength data 37, and set value data 38, on the display unit 4. In this case, the display control unit may be configured to display the target tensile strength data 34 and estimated tensile strength data 37 together, as shown in FIG. 9, for example.

In addition, in the above embodiment, the mixer control unit 11 is described as a personal computer, but this is not limiting. For example, the mixer control unit 11 may be configured as a network device such as a server. In this case, the mixer control unit 11 will send and receive data with the mixer 10 via the network. In addition, for example, a terminal for controlling the mixer 10 may be provided, and communication between the terminal and the mixer control unit 11 may be performed via the network. In this case, the terminal will acquire actual measurements from the mixer 10 and control the mixer 10 using the setting values received from the mixer control unit 11.

The number of kneaders 10 controlled by the kneader control unit 11 is not limited to one, and one kneader control unit 11 may be configured to control multiple kneaders 10.

In addition, in the above embodiment, the kneader control unit 11 is configured as a single personal computer or the like, but this is not limiting. For example, some of the functions of the kneader control unit 11 may be installed in another personal computer or the like. In other words, the kneader control unit 11 does not have to be configured as a single piece of hardware, but may be configured as multiple pieces of hardware.

Furthermore, in the above embodiment, the deviation threshold value ΔS _th is set to a constant value, but the invention is not limited to this, and the deviation threshold value ΔS _th may be set to change according to the kneading time t. For example, there may be a case where the variation in kneading is large at the beginning of kneading, and kneading is judged to have failed even though it has not failed. However, by setting the deviation threshold value ΔS _th at the beginning of kneading to a relatively large value (for example, setting the deviation threshold value ΔS th to a value larger than the deviation threshold value ΔS th at a state where kneading is stable (for example, a state where the tensile strength S of the kneaded material has reached a value of 80% or more of the tensile strength _Sg at which kneading is judged to have ended)), such a problem can be prevented.

Furthermore, in the above embodiment, the number of failure determinations _nth is a constant value, but the number of failure determinations _nth may be set to vary according to the kneading time t. By setting the number of failure determinations _nth at the beginning of kneading to a relatively large value (for example, by setting it to a value larger than the number of failure determinations _nth when kneading is stable (for example, when the tensile strength S of the kneaded material has reached a value equal to or greater than 80% of the tensile strength Sg at which kneading is determined to be complete)), it is possible to prevent a problem in which kneading is determined to be a failure even when it is not a failure.

(Summary of the embodiment)
Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[1] A kneading device (1) for mixing a resin and a filler with a rotor to obtain a kneaded product, comprising: a kneader (10) having a temperature sensor (101) capable of detecting the temperature of the kneaded product and a rotation sensor (102) capable of detecting the rotor rotation speed, which is the rotation speed of the rotor; and a kneader control unit (11) for controlling the kneader (10), wherein the kneader control unit (11) controls the temperature of the kneaded product detected by the temperature sensor (101) and the rotor rotation speed detected by the rotation sensor (102). The kneading device (1) comprises: a tensile strength estimation processing unit (24) that estimates the current tensile strength of the kneaded material based on the rotor rotation speed; and a kneading condition control processing unit (25) that calculates the deviation between the current target tensile strength and the tensile strength of the kneaded material estimated by the tensile strength estimation processing unit (24) based on a preset target tensile strength, which is a target value for the time change in the tensile strength of the kneaded material from the start of kneading; and controls the kneading conditions of the kneader (10) to minimize the deviation.

[2] The kneading device (1) described in [1], wherein the kneading condition control processing unit (25) maintains the current kneading conditions when the deviation is equal to or less than a preset deviation threshold, and controls the kneading conditions of the kneader (10) so as to reduce the deviation when the deviation is greater than the deviation threshold.

[3] The kneading device (1) described in [1], wherein the tensile strength estimation processing unit (24) estimates the tensile strength of the kneaded product using equation (1) shown in [Mathematical Expression 7].

[4] The kneading machine (10) is configured to be able to set the temperature of the kneaded material and the rotor rotation speed, and the kneading condition control processing unit (25) controls the set values of the temperature of the kneaded material and the rotor rotation speed as the kneading conditions. [1] The kneading device (1) described in [1].

[5] The kneading device (1) described in [1], wherein the kneading condition control processing unit (25) controls the kneading conditions using PID control.

[6] The kneading machine control unit (11) has a kneading failure determination processing unit (26) that determines whether kneading has failed, and the kneading failure determination processing unit (26) determines whether kneading has failed when the deviation remains greater than a preset failure determination threshold for a predetermined period of time. [1] The kneading device (1) described in [1].

[7] A kneading method for mixing a resin and a filler with a rotor to obtain a kneaded product, comprising: using a kneader (10) having a temperature sensor (101) capable of detecting the temperature of the kneaded product and a rotation sensor (102) capable of detecting the rotor rotation speed, which is the rotation speed of the rotor; estimating the current tensile strength of the kneaded product based on the temperature of the kneaded product detected by the temperature sensor (101) and the rotor rotation speed detected by the rotation sensor (102); determining the deviation between the current target tensile strength and the estimated current tensile strength of the kneaded product based on a predetermined target tensile strength, which is a target value for the change in tensile strength of the kneaded product over time from the start of kneading; and controlling the kneading conditions of the kneader (10) to minimize the deviation.

(Additional Note)
Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above-described embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented within the scope of its spirit.

1... Kneading device 10... Kneader 101... Temperature sensor 102... Rotation sensor 11... Kneader control unit 2... Control unit 21... Setting processing unit 22... Data acquisition processing unit 23... Relationship derivation processing unit 24... Tensile strength estimation processing unit 25... Kneading condition control processing unit 26... Kneading failure judgment processing unit

Claims (7)

A kneading device that mixes a resin and a filler with a rotor to obtain a kneaded product,
a kneading machine having a temperature sensor capable of detecting the temperature of the kneaded material and a rotation sensor capable of detecting a rotor rotation speed, which is the rotation speed of the rotor;
a mixer control unit that controls the mixer,
The kneading machine control unit
a tensile strength estimation processing unit that estimates a current tensile strength of the kneaded material based on the temperature of the kneaded material detected by the temperature sensor and the rotor rotation speed detected by the rotation sensor;
a kneading condition control processing unit that calculates a deviation between a current target tensile strength and a current tensile strength of the kneaded material estimated by the tensile strength estimation processing unit based on a preset target tensile strength, which is a target value of a time change in the tensile strength of the kneaded material from the start of kneading, and controls the kneading conditions of the kneader so as to reduce the deviation.
Kneading equipment. the kneading condition control processing unit maintains the current kneading conditions when the deviation is equal to or smaller than a preset deviation threshold, and controls the kneading conditions of the kneader when the deviation is greater than the deviation threshold so as to reduce the deviation.
The kneading device according to claim 1 . The tensile strength estimation processing unit estimates the tensile strength of the kneaded material using equation (1) shown in [Mathematical Expression 1].
The kneading device according to claim 1 . the kneader is configured to be able to set a temperature of the kneaded material and a rotor rotation speed,
the kneading condition control processing unit controls set values of the temperature of the kneaded material and the rotor rotation speed as the kneading conditions;
The kneading device according to claim 1 . The kneading condition control processing unit controls the kneading conditions by PID control.
The kneading device according to claim 1 . The kneading machine control unit has a kneading failure determination processing unit that determines a kneading failure,
the kneading failure determination processing unit determines that the kneading has failed when the state in which the deviation is greater than a preset failure determination threshold continues for a predetermined period of time.
The kneading device according to claim 1 . A kneading method for obtaining a kneaded product by mixing a resin and a filler with a rotor, comprising:
a kneading machine having a temperature sensor capable of detecting the temperature of the kneaded material and a rotation sensor capable of detecting the rotor rotation speed, which is the rotation speed of the rotor;
estimating a current tensile strength of the kneaded material based on the temperature of the kneaded material detected by the temperature sensor and the rotor rotation speed detected by the rotation sensor;
a target tensile strength that is a preset target value of the change in tensile strength of the kneaded material over time from the start of kneading, and a deviation between the target tensile strength at the current time and the estimated tensile strength of the kneaded material at the current time is calculated, and the kneading conditions of the kneader are controlled so as to reduce the deviation.
Mixing method.