JP6984243B2 - Kneading abnormality determination method and kneading control method for unvulcanized rubber - Google Patents

Description

The present invention relates to a kneading abnormality determination method and a kneading control method for unvulcanized rubber, and more specifically, it is possible to detect unvulcanized rubber in which a kneading abnormality has occurred at an early stage with high accuracy and improve the yield. It relates to a new kneading abnormality determination method and a kneading control method that can be performed.

When manufacturing rubber products such as tires and rubber hoses, for example, a predetermined amount of raw rubber and a non-vulcanizing compounding agent such as carbon black, filler, and oil are put into a closed rubber kneader and kneaded. Thereby, unvulcanized rubber is obtained. The unvulcanized rubber is then mixed with a vulcanizing compound such as sulfur and kneaded to obtain a final kneaded rubber. By the way, an abnormally kneaded product in which the amount and type of the raw rubber and the compounding agent are erroneously kneaded cannot secure the rubber physical characteristics as set when vulcanized. If the detection of the kneading abnormality is delayed, the final kneaded rubber will be a kneaded abnormal product, and the yield will be significantly deteriorated. Therefore, it is necessary to detect the kneading abnormality as soon as possible and distinguish between the abnormal kneading product and the normal product.

For example, a method for determining the presence or absence of an abnormality in unvulcanized rubber during kneading has been proposed (see Patent Document 1). In the invention of Patent Document 1, the calculated value is calculated by dividing the integrated electric power required for driving the rotation of the rotor when kneading the kneading batch by the integrated rotation speed of the rotor at the same time as the calculated time. do. Then, based on the comparison between the calculated calculated value and the normal value grasped in advance, the presence or absence of a kneading abnormality in the kneading batch is determined during kneading of the kneading batch or immediately after the kneading is completed. Therefore, it becomes possible to detect the kneading abnormality at an early stage.

However, it has been found that the kneading abnormality of the kneading batch may not be detected by the calculated value using the above integrated electric energy and the integrated rotation speed. Therefore, there is room for improvement in order to detect unvulcanized rubber in which a kneading abnormality has occurred at an early stage and improve the yield.

Japanese Unexamined Patent Publication No. 2014-226910

An object of the present invention is to provide a new kneading abnormality determination method and a kneading control method capable of detecting unvulcanized rubber in which a kneading abnormality has occurred at an early stage with high accuracy and improving the yield. ..

In order to achieve the above object, the method for determining an abnormality in kneading of unvulcanized rubber of the present invention is to determine an abnormality in kneading of unvulcanized rubber when continuously kneading a kneading batch of unvulcanized rubber with a closed rubber kneader. In the method, the inclination angle of the stirring blade of the kneader with respect to the axial direction is set to 45 ° or more and 90 ° or less , and the ram that moves up and down inside the kneader is arranged at a predetermined lower position. The temperature of each kneading batch is detected by a temperature sensor for each stage of kneading in the state, and this detected temperature is compared with the reference temperature of the kneading batch in the case of normal kneading, which is known in advance. Based on the magnitude of the difference between the two, the presence or absence of kneading abnormality in each of the kneading batches is determined immediately after the end of each of the stages.

In the kneading control method for unvulcanized rubber of the present invention, when the kneading batch is determined to have a kneading abnormality by the above-mentioned method for determining an unvulcanized rubber kneading abnormality, the kneading of the next kneading batch of the kneaded batch is performed. It is characterized in that the kneader is controlled so as not to start.

According to the present invention, the detection temperature of each kneading batch and the detection temperature of each kneading batch are normally grasped in advance for each stage of kneading in a state where the ram that moves up and down inside the kneading machine is arranged at a predetermined lower position. Compare with the reference temperature of the kneading batch when kneaded. The temperature of the kneading batch is greatly affected by the degree of reaction between the raw rubber and the compounding agent and the amount of work input by the rotor to the kneading batch. Therefore, by using the temperature of the kneading batch as a determination index for the presence or absence of kneading abnormality, it is possible to accurately determine the presence or absence of kneading abnormality. Moreover, since the presence or absence of the kneading abnormality is determined immediately after the end of each stage, the kneading abnormality product can be detected at an early stage, and the increase of the kneading abnormality product can be prevented. Therefore, it is advantageous to improve the yield of unvulcanized kneaded rubber.

It is a vertical cross-sectional view which illustrates the internal structure of the closed type rubber kneader. FIG. 1 is a cross-sectional view taken along the line AA of FIG. It is a vertical cross-sectional view which illustrates the state which the kneading batch is kneaded by the closed type rubber kneader of FIG. It is a graph which illustrates the time series data of the detection temperature Ti of the kneading batch, the value p / n which divided the instantaneous electric energy p by the rotation speed n, and the vertical position of a ram.

Hereinafter, the kneading abnormality determination method and the kneading control method for the unvulcanized rubber of the present invention will be described based on the embodiments shown in the figure.

The closed rubber kneader 1 (hereinafter referred to as a kneader 1) exemplified in FIGS. 1 to 3 has a material input port 3 in the middle of the casing 2 in the vertical direction, and a chamber for accommodating the rotor 8 in the lower portion of the casing 3. It has a 7 and a material discharge port 4. The material input port 3 is opened and closed by the input door 3a, and the material discharge port 4 is opened and closed by the discharge port flap 5. The chamber 7 is provided with a temperature sensor 11 and two rotors 8.

Each rotor 8 has a rotor shaft 9a and a stirring blade 9b projecting from the outer peripheral surface of the rotor shaft 9a. The rotor shafts 9a are juxtaposed in parallel. The stirring blade 9b is set to a predetermined inclination angle Ag (≦ 90 °) with respect to the axial direction of the rotor shaft 9a. Each rotor 8 is rotationally driven by the rotor drive unit 10 around the respective rotor shaft 9a, and the rotation directions are opposite to each other. The type of the rotor 8 is not particularly limited, and various types such as a tangential type and a meshing type can be adopted, and the number, shape, and inclination angle Ag of the stirring blades 9b are appropriately determined.

A drive motor or the like is used for the rotor drive unit 10. The rotor drive unit 10 is provided with a tachometer 10a and a power meter 10b. From the time when the kneading batch Ri starts kneading to the time when the kneading is completed, the tachometer 10a sequentially detects the rotation speed n of the rotor 8 (rotor shaft 9), and the power meter 10b sequentially detects the instantaneous power required to drive the rotation of the rotor 8. p is sequentially detected. The data detected by the tachometer 10a and the power meter 10b is input to the arithmetic unit 12. The operation of the rotor drive unit 10 is controlled by the calculation unit 12.

A temperature sensor 11 and a warning device 13 are connected to the arithmetic unit 12. The temperature sensor 11 detects the temperature T of the kneading batch Ri that is kneaded in the chamber 7. The temperature Ti detected by the temperature sensor 11 is input to the calculation unit 12. As the warning device 13, for example, a warning light, a warning buzzer, or the like is used.

A ram 6 that moves up and down is provided above the rotor 8. When the unvulcanized rubber R is charged into the casing 2, the ram 6 is arranged at an upper standby position that does not interfere with the charging of the unvulcanized rubber R. After the unvulcanized rubber R is charged into the casing 2, it moves downward from the standby position and is arranged at a predetermined position that closes the upper part of the chamber 7 and substantially seals the chamber 7. The operation of the ram 6 is controlled by the arithmetic unit 12.

One lot of unvulcanized rubber R is put into the kneader 1 and kneaded for a predetermined time for each kneading batch Ri of a predetermined amount. The kneading batch Ri is composed of a predetermined amount of raw rubber and a predetermined amount of a non-vulcanized compounding agent such as carbon black, a filler, and oil, and is kneaded by a rotary-driven rotor 8. From the start of kneading to the end of kneading of the kneading batch Ri, for example, the ram 6 is moved upward several times. That is, the step of kneading with the ram 6 placed at a predetermined lower position is set as one stage, and a plurality of stages are repeated.

When the kneading (all stages) of the kneading batch Ri is completed, the kneading batch Ri is discharged from the material discharge port 4. When the kneading of one batch of kneading batch Ri is completed, the next kneading batch Ri is sequentially put into the kneading machine 1 to knead one lot of unvulcanized rubber R. The unvulcanized rubber R kneaded for each kneaded batch Ri is sent to the storage location. The kneaded unvulcanized rubber R is, for example, formed into a continuous sheet and stored in a storage place.

This unvulcanized rubber R to which the non-vulcanized compounding agent is kneaded is separately kneaded by the kneading machine 1 to become the final kneaded rubber. At this time, a predetermined amount of kneading batch Ri is kneaded together with a predetermined amount of sulfur, a vulcanization-based compounding agent such as a vulcanization accelerator, and the like in the same kneading step as described above.

As illustrated in FIG. 4, in the kneading abnormality determination method of the unvulcanized rubber of the present invention, the temperature T (detection temperature Ti) of the kneading batch Ri during kneading is sequentially detected by the temperature sensor 11. Here, for each stage of kneading with the ram 6 arranged at a predetermined lower position, the reference temperature Tc of the kneading batch Rc when kneaded normally is grasped in advance. Then, the reference temperature Tc grasped in advance is input and stored in the arithmetic unit 12.

In FIG. 4, the time-series data of the detection temperature Ti of the kneading batch Ri is shown by a thick solid line. The alternate long and short dash line Ld shows the time series data of the vertical position of the ram 6.

The arithmetic unit 12 compares the detected temperature Ti and the reference temperature Tc for each stage, and determines whether or not there is a kneading abnormality in each kneading batch Ri based on the magnitude of the difference between the two compared. This determination result is shown immediately after the end of each stage or immediately after the end of all stages.

It is possible to compare the two by adopting the temperature sequentially detected as the detection temperature Ti and the reference temperature Tc at the time when the sequential temperature is detected, but the temperature varies to some extent. Therefore, for example, for each stage, the arithmetic unit 12 calculates an average value Tm obtained by averaging the detection temperatures Ti that are sequentially detected. This average value Tm is used as the detection temperature Ti to be compared with the reference temperature Tc. The reference temperature Tc corresponds to the comparison target (average value Tm), and the average temperature at that stage of the kneading batch Rc when normally kneaded in the same stage is used as the reference temperature Tc.

The detection temperature Ti of the kneading batch Ri at which kneading has started greatly affects the degree of reaction between the raw rubber and the compounding agent and the amount of work (such as the amount of shearing force applied) input by the rotor 8 to the kneading batch Ri. Receive. Therefore, if the detection temperature Ti of the kneading batch Ri deviates from the reference temperature Tc (when the difference is large), the reaction between the raw rubber and the compounding agent does not proceed properly, or the kneading batch Ri is performed by the rotor 8. It can be considered that a problem such as not being applied with an appropriate shearing force has occurred. Therefore, by using the temperature Ti of the kneading batch Ri as a determination index for the presence or absence of a kneading abnormality, it is possible to accurately determine the presence or absence of a kneading abnormality.

In particular, as the inclination angle Ag of the stirring blade 9b of the rotor 8 increases, slipping due to oil or a compound having a low melting point disappears, and the power difference becomes smaller. Therefore, even if there is a kneading abnormality, the driving force (the amount of electric power required for driving) of the rotor 8 may not change. In the present invention, since the kneading abnormality is determined by using the detection temperature Ti of the kneading batch Ri, it is possible to detect even a kneading abnormality in which the driving force of the rotor 8 does not change or is unlikely to occur. Therefore, for example, the present invention is particularly effective for the rotor 8 having an inclination angle Ag of 45 ° or more. For the stirring blade 9b whose inclination angle Ag is not constant in the blade length direction but changes, the average value averaged in the blade length direction is taken as the inclination angle Ag of the rotor 8.

According to the present invention, since it is possible to determine the presence or absence of a kneading abnormality in the kneading batch Ri immediately after the end of each stage or immediately after the end of all stages, it is possible to detect an abnormal kneading product at an early stage. This eliminates problems such as kneading the abnormally kneaded product together with the vulcanization-based compounding agent to produce a further abnormally kneaded product. In this way, it is possible to prevent an increase in abnormal kneaded products and improve the yield of unvulcanized kneaded rubber.

It is presumed that the larger the difference between the detected temperature Ti and the reference temperature Tc, the higher the possibility that a kneading abnormality has occurred in the kneading batch Ri. Therefore, in the determination of the kneading abnormality, for example, when the magnitude of the difference between the detected temperature Ti and the reference temperature Tc is 10% or more of the reference temperature Tc, it is determined that the kneading batch has the kneading abnormality. The temperature in degrees Celsius (° C) is used as the numerical value of the temperature at this time. The threshold value for determining the kneading abnormality is not limited to 10%, and is set to an appropriate value, for example, between 5% and 30%.

The average value Tm of the detection temperature Ti of the kneading batch Ri when a predetermined number i (for example, 20 batches to 50 batches) of 20 or more batches immediately before the kneading batch Ri for determining the kneading abnormality is kneaded without the kneading abnormality is used as the reference temperature Tc. It can also be used. In this case, the average value of the latest predetermined number i is updated as the reference temperature Tc each time the kneading of one batch of kneading batch Ri is completed (all stages are completed).

When the reference temperature Tc is set in this way, the reference temperature Tc is set based on the data of kneading under the conditions closer to the kneading batch Ri currently being kneaded. Since the detected temperature Ti fluctuates depending on the atmospheric environment (outside air temperature, humidity, etc.), setting the reference temperature Tc in this way improves the appropriateness of the reference temperature Tc. It is empirically understood that if the kneading is normal, the detected temperature Ti does not continue to increase or decrease slightly between the kneading batches Ri. Therefore, the reference temperature Tc does not become an inappropriate value as a result of a slight increase or decrease of the reference temperature Tc continuously for a long period of time. Rather, it has been confirmed that the kneading state can be more appropriately determined by reflecting the latest detected temperature Tc in the reference temperature Tc to some extent.

In the above-described embodiment, the kneading abnormality is determined based only on the detected temperature Ti, but it cannot be said that there is no case where the kneading abnormality does not appear in the change of the detected temperature Ti. Therefore, in order to determine the kneading abnormality with higher accuracy, the amount of electric power required for rotationally driving the rotor 8 when kneading each kneading batch Ri can also be used.

Specifically, for each stage, the instantaneous power amount p required for rotational driving of the rotor 8 when kneading each kneading batch Ri is integrated by the arithmetic unit 12 to calculate the integrated power amount P. That is, the integrated electric energy P shown in the following equation (1) is calculated.
Integrated electric energy P = ∫ (p) dt ... (1)

Further, the rotation speed n of the rotor 8 at the same time (same stage) as the time T in which the integrated electric energy P is integrated is integrated by the arithmetic unit 12 to calculate the integrated rotation speed N. That is, the integrated rotation speed N shown in the following equation (2) is calculated.
Integrated rotation speed N = ∫ (n) dt ... (2)

Then, the value (P / N) obtained by dividing the integrated electric energy P by the integrated rotation speed N is calculated by the arithmetic unit 12 as the calculated value V. The arithmetic unit 12 inputs and stores a value (Pc / Nc) obtained by dividing the integrated electric energy Pc when the kneading batch Ri is kneaded for each stage by the integrated rotation speed Nc as a normal value C. ..

When the kneading batch Ri is kneaded by the kneading machine 1, the unvulcanized rubber R repeatedly has a shearing force between the clearance between the inner wall surface 7a of the chamber 7 and the rotor 8 (rotor outer diameter) that is rotationally driven. It is given and kneaded. The rotor 8 that applies a shearing force to the unvulcanized rubber R receives rotational resistance as a reaction. The rotational resistance received by the rotor 8 varies depending on the amount and type of the raw rubber to be kneaded and the amount and type of the compounding agent.

Therefore, if the amount and type of the raw rubber and the compounding agent are not as set and the kneading machine 1 is mistakenly put into the kneading machine 1 and kneaded, the rotational resistance when the rotor 8 is rotationally driven is the case where the normal product is kneaded. Will be different. That is, when there is a kneading abnormality, the electric power required for rotationally driving the rotor 8 is different from that of the normal product.

Therefore, the calculated calculated value V and the preliminarily grasped normal value C are compared by the arithmetic unit 12 for each stage. The integration of the instantaneous electric energy p, that is, the calculation of the calculated value V and the normal value C of each kneading batch Ri can be performed in the entire period of each stage, but is performed in the period in which the instantaneous electric energy p is stable. It is good.

The solid line LC of the thin line illustrated in FIG. 4 is the data that is the basis of the normal value C. In this solid line LC, for the kneading batch Ri that has been kneaded without any abnormality in the 20 batches immediately before the kneading batch Ri to be determined, the instantaneous electric energy p when each kneading batch Ri is kneaded is divided by the rotation speed n at that time. The time series data which averaged the value p / n is shown. The broken line LV shows the time series data of the value p / n obtained by dividing the instantaneous electric energy p of the kneading batch Ri to be determined by the rotation speed n at that time. That is, the broken line LV is the data that is the basis of the calculated value V.

Then, for each stage (1st stage and 2nd stage in FIG. 4), the above-mentioned equations (1) and (2) are integrated to calculate the calculated value V. The normal value C is also calculated in the same manner. Next, the calculated value V and the normal value C are compared to calculate the difference. Then, it is judged based on the magnitude of the difference, the presence or absence of kneading abnormality kneading batch Ri, immediately after the end of each immediately after the end or all stages of the stage.

By using the integrated electric energy P, which is the sum of the instantaneous electric energy p required for rotational driving of the rotor 8, as the calculated value V, which is used as a determination index for the presence or absence of a kneading abnormality, the value changes sensitively when there is an abnormal kneading. do. Further, the calculated value V is a value (P / N) obtained by dividing the integrated electric energy P by the integrated rotation speed N, and since the rotation speed n of the rotor 8 is taken into consideration, the rotation speed n of the rotor 8 is in the middle. Even if it changes, it is possible to accurately determine the presence or absence of a kneading abnormality.

It is presumed that the larger the difference between the calculated value V and the normal value C, the higher the possibility that a kneading abnormality has occurred in the kneading batch Ri. Therefore, in the determination of the kneading abnormality, for example, when the magnitude of the difference between the calculated value V and the normal value C is 10% or more of the normal value C, it is determined that the kneading batch Ri has a kneading abnormality. The threshold value for determining the kneading abnormality is not limited to 10%, and an appropriate value is set, for example, between 5% and 30%.

The present invention can be applied not only when the raw rubber is kneaded together with the non-vulcanized compounding agent but also when the raw material rubber is kneaded together with the vulcanized compounding agent to obtain the final kneaded rubber.

As the normal value C, for example, the average value of the calculated values V of the kneading batch Ri of a predetermined number i (for example, 20 batches to 50 batches) of 20 or more batches immediately before the kneading batch Ri for determining the kneading abnormality is used. In this case, the kneading batch Ri of one batch is updated to the latest normal value C of a predetermined number i every time the kneading is completed.

By updating the kneading batch Ri to the latest normal value C of a predetermined number i each time one batch kneading is completed, the normal value C can be set based on the data kneaded under conditions closer to the kneading batch Ri currently being kneaded. Therefore, the appropriateness of the normal value C can be improved.

When it is determined that there is a kneading abnormality in at least one of the determination of the presence or absence of the kneading abnormality based on the detected temperature Ti and the determination of the presence or absence of the kneading abnormality based on the amount of electric power required to drive the rotation of the rotor 8, when it is indicated that the kneading abnormality is present. It is determined that the kneading batch Ri has a kneading abnormality. That is, it is determined that there is no kneading abnormality in the kneading batch Ri only when it is determined that there is no kneading abnormality based on both the detection temperature Ti and the power amount required for the rotary drive of the rotor 8.

In the kneading control method for unvulcanized rubber of the present invention, when the kneading batch Ri is determined to be abnormal in kneading, the kneading machine 1 is controlled so as not to start the kneading of the next kneading batch Ri of the kneading batch Ri. .. For example, as soon as it is determined that the kneading abnormality is performed, the charging door 3a is controlled so as not to open, and the next kneading batch Ri is prevented from being charged into the kneading machine 1. As a result, it is possible to reliably prevent the increase of abnormal kneading products.

It is more preferable that the warning device 13 issues a warning when the kneading batch Ri is determined to have a kneading abnormality. When a warning light is used as the warning device 13, it is turned on, and when a warning buzzer is used, an alarm is issued to notify the operator of the kneading abnormality.

1 Sealed rubber kneader 2 Casing 3 Material inlet 3a Input door 4 Material outlet 5 Outlet flap 6 Ram 7 Chamber 7a Inner wall surface 8 Rotor 9a Rotor shaft 9b Stirring blade 10 Rotor drive 10a Wattmeter 10b Tachometer 11 Temperature Sensor 11 Computing device 12 Warning device R Unvulcanized rubber Ri Kneading batch

Claims (6)

In the method for determining a kneading abnormality of unvulcanized rubber when continuously kneading a kneading batch of unvulcanized rubber with a closed rubber kneader.
Kneading is performed in a state where the inclination angle of the stirring blade of the kneader with respect to the axial direction of the rotor shaft is set to 45 ° or more and 90 ° or less , and the ram that moves up and down inside the kneader is arranged at a predetermined lower position. The temperature of each kneading batch was detected by a temperature sensor for each stage in which the kneading batch was performed, and this detected temperature was compared with the reference temperature of the kneading batch in the case of normal kneading, which was known in advance, and compared. A method for determining a kneading abnormality of unvulcanized rubber, which comprises determining the presence or absence of a kneading abnormality in each of the kneading batches immediately after the end of each of the stages based on the magnitude of the difference between the two. The kneading of unvulcanized rubber according to claim 1, wherein an average value is calculated by averaging the temperatures of the kneading batches for each stage, and the average value is used as the detection temperature to compare with the reference temperature. Abnormality judgment method. The unvulcanized rubber according to claim 1 or 2, wherein when the magnitude of the difference between the detected temperature and the reference temperature is 10% or more of the reference temperature, it is determined that the kneading batch has a kneading abnormality. Judgment method of kneading abnormality. Immediately before the kneading batch for determining the kneading abnormality The average value of the detected temperatures of the kneading batch when a predetermined number of kneading batches of 20 or more are kneaded without any kneading abnormality is used as the reference temperature, and each time the kneading batch is kneaded for one batch. The method for determining a kneading abnormality of unvulcanized rubber according to any one of claims 1 to 3, wherein the latest average value of a predetermined number is updated as the reference temperature. For each stage, the instantaneous power required for rotationally driving the rotor of the kneader when kneading each kneading batch is integrated to calculate the integrated power amount, and the calculated integrated power amount is grasped in advance. Compared with the standard integrated electric energy of the kneading batch when kneaded normally, and based on the magnitude of the difference between the two, the presence or absence of kneading abnormality in each of the kneading batches is determined in each of the above stages. The method for determining a kneading abnormality of unvulcanized rubber according to any one of claims 1 to 4, which is determined immediately after the end or immediately after the end of all the stages. When the kneading batch is determined to be a kneading abnormality by the method for determining a kneading abnormality of unvulcanized rubber according to any one of claims 1 to 5, the kneading of the next kneading batch of the kneading batch is not started. A method for controlling kneading of unvulcanized rubber, which comprises controlling the kneader.

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