JPH1120005A - Discharge amount measuring apparatus and discharge amount controller for extrusion molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and quickly measure a discharge amount from an extrusion molding machine. SOLUTION: A measuring unit 33 measures a weight of a hopper for supplying material to the extrusion molding machine and outputs it to a measuring control unit 35. A rotational speed measuring unit 37 outputs a rotational speed of a main screw of the machine to the unit 35. The unit 35 calculates an upper limiter of a weight variation of the hopper from a reference rotational speed of the screw, a reference weight variation, and a real rotational speed of the screw, and calculates a discharge amount by using the limiter of the weight variation at the time of that measuring when the weight variation at the time of measuring exceeds the upper limiter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a discharge amount measuring device and a discharge amount control device which contribute to uniform quality of an extruded product from an extruder.

[0002]

2. Description of the Related Art As shown in FIG. 12, for example, as shown in FIG. 12, an extrusion molding line for extruding a long product such as a plastic pipe or a laminated product such as a plastic sheet is connected to an extruder 1 and a take-up machine 3, and the extrusion molding is performed. The molded product 5 extruded from the machine 1 is taken up by the take-up machine 3. Extruder 1
The molding machine table 11 is attached to the cylinder 9 containing the main screw 7.
The molding machine base 11 is provided with an extrusion motor 13 for driving the main screw 7 to rotate, and a rotation speed detection sensor 15 for detecting the rotation speed of the extrusion motor 13.

A hopper 17 for supplying a plastic material into the cylinder 9 is disposed on the cylinder 9, and a material storage section 19 filled with a plastic material to be refilled into the hopper 17 is disposed above the hopper 17. ing.

The hopper 17 is a material supply unit called a weighing pot or a weighing hopper. As shown in FIG. 13, a weighing unit 21 for measuring the weight of the hopper itself is connected, and the weighing data is transmitted to the control unit A ( 12 (see FIG. 12). When the remaining amount of the plastic material in the hopper 17 becomes small, the shutter 19a and the like of the material storage unit 19 (illustrated slightly different from FIG. 12) are opened by control from the control device A or manually, and the plastic material is It is designed to be refilled inside. Numerals 23 and 25 in FIG. 12 are a temperature sensor and a pressure sensor arranged on the cylinder 9.

In such an extrusion molding line, the plastic material supplied from the hopper 17 to the cylinder 9 is heated and melted, and the main screw 7 is driven to rotate to form a molded product 5 from a tip die (not shown) of the cylinder 9. And is taken out by a take-off roller 29 which is driven to rotate by a take-up motor 27 to be commercialized. The rotation speed of the take-off motor 27 is detected by a rotation speed detection sensor 31 similar to the sensor 15, and the control device A
Is output to

[0006] The control device A is composed of the weighing data from the weighing section 21 and the pushing motor 1 from the rotation speed detecting sensors 15 and 31.
3 and the rotation speed signals of the take-off motor 27 are taken in, and the rotation speeds of the motors 13 and 27 are controlled so that the discharge amount (volume) per unit time of the extruded molded product 5 becomes uniform.

Conventionally, in such an extrusion molding line, as shown in FIG. 14, for example, as shown in FIG. 14, in order to make the discharge amount from the cylinder 9, that is, the volume of the extruded molded product 5 uniform and keep the quality of the product constant. The material supply amount (consumption amount) is measured from the measurement period (extrusion period) after the material is put into the hopper 17 and the maximum and minimum values of the plastic material in the hopper 17 at the beginning and end of the measurement period. The discharge amount of the extruded molded product 5 is calculated from the relationship between the measurement result and the die cross-sectional area, etc., and the extrusion speed of the extrusion motor 13 or the take-off motor 27 is adjusted so as to approach the desired discharge amount. The take-off speed was controlled to control the discharge amount.

[0008]

However, the above-described conventional material supply amount measurement method and discharge amount control method in the extrusion molding line have the following disadvantages. That is, the plastic material in the hopper 17 is
With the rotation of the main screw 7, the plastic material extruded from the extruder 1 drops by its own weight and is supplied into the cylinder 9 in accordance with the reduced amount.

On the other hand, during rotation of the main screw 7, the vicinity of the material input port 9 a of the cylinder 9 is
Periodically passes (see FIG. 12), and when the crest 7a of the main screw 7 passes near the material inlet 9a of the cylinder 9, the crest 7a of the main screw 7 pushes up the hopper 17. As a result, the measured weight temporarily decreases, and the temporal change of the measured weight is accompanied by vibration. Therefore, when there is no replenishment of material from the material storage unit 19, the hopper weight measured by the
Since it does not change like the oblique straight line in the middle and decreases with vibration as shown by the broken line in the waveform in the same figure, measuring the material supply amount in a short section measurement tends to cause a large error, It has to be measured in a long period of time, for example, at least several minutes, and it is difficult to quickly measure an accurate hopper weight, and it is also difficult to make uniform the quality of the molded article 5 and to quickly control the change of the thickness. .

Therefore, the present inventor has proposed the operation of the extruder 1, in particular, the discharge amount from the cylinder 9 and the main screw 7.
As a result of carefully observing and studying the rotation speed of the screw, the discharge amount and the screw rotation speed are almost in a proportional relationship, and the present invention has been completed by focusing on the point that it is possible to more accurately measure the discharge amount using this relationship. Was.

The present invention has been made under such circumstances, and an object thereof is to provide a discharge amount measuring device capable of accurately and quickly measuring the discharge amount discharged from an extruder.
Further, the present invention provides a discharge amount control device capable of stabilizing the discharge amount from the extruder regardless of the difference between the discharge amount and the set value.

[0012]

In order to solve such a problem, a first configuration of a discharge amount measuring apparatus according to the present invention comprises:
Measuring unit that measures the weight of the material supply unit that supplies material to the screw side of the extruder, rotation speed measurement unit that measures the rotation speed of the screw, and the ratio of the reference weight fluctuation value to the reference rotation speed of the screw The upper limiter is obtained from the relationship between the ratio of the upper limiter of the weight fluctuation value to the rotation speed of the screw, and when the weight fluctuation value at the time of measurement does not exceed the upper limiter, the measured weight fluctuation value is used as it is, When the weight fluctuation value at the time of measurement exceeds the upper limiter, a measurement control unit that measures the discharge amount by using the upper limiter as the weight fluctuation value at the time of measurement.

A second aspect of the present invention relates to a discharge amount measuring device according to the present invention.
Consists of a measuring section that measures the weight of the material supply section that supplies the material to the screw side of the extruder, a rotation number measurement section that measures the rotation number of the screw, and a reference weight for the reference rotation number of the screw. This change rate limiter is determined from the relationship between the ratio of the change value and the ratio of the change rate limiter of the weight change value to the change in the number of revolutions of the screw, and when the weight change change value at the time of measurement does not exceed the change rate limiter, the relevant change rate limiter is determined. When the measured weight fluctuation change value is used as it is and the weight fluctuation change value at the time of measurement exceeds the change rate limiter, the weight fluctuation change value at the time of the measurement is added by adding the change rate limiter to the weight fluctuation change value at the previous measurement. And a measurement control unit that measures the discharge amount by using the control unit.

According to the second aspect of the present invention, the measurement control unit can be formed so as to calculate the change rate limiter by adding a predetermined minimum limiter. Further, in the first and second configurations, the measurement control unit may determine a ratio between a ratio of a reference weight fluctuation value to a reference rotation speed of the screw and a ratio of an upper limiter of the weight fluctuation value to the rotation speed of the screw. The upper limiter is obtained, and the upper limiter and the actual weight fluctuation value are integrated a plurality of times. When the actual weight fluctuation integrated value exceeds the upper limit limit integrated value, the reference rotation speed is calculated from the actual weight fluctuation integrated value and the upper limit limit integrated value. In addition, the discharge amount can be measured by correcting the reference upper limiter.

Further, the discharge amount control device of the present invention comprises a measuring section for measuring the weight of a material supply section for supplying the material to the screw side of the extruder, and a rotation number measuring section for measuring the rotation number of the screw. A measurement control unit for calculating an operation amount by a moving average method and a PID calculation from a discharge amount calculated based on the rotation speed of the screw and the measured weight of the material supply unit, wherein the calculated discharge amount and a preset set discharge When the deviation from the amount becomes a predetermined value or more, the number of moving averages is reduced and the operation amount is calculated with a fast response control constant. When the deviation is smaller than a predetermined value, the number of moving averages is increased and the speed is slow. A measurement control unit that calculates the operation amount with a response control constant, outputs the operation amount to at least the rotation drive motor side of the screw, and controls the discharge amount.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a discharge amount measuring device according to the present invention, together with a discharge amount control device using the same. The configuration of the extrusion molding line is the same as that of FIG.

In FIG. 1, a weighing section 33 corresponds to the weighing section 21 in FIG. 12 and is connected to a measurement control section 35, and measures the weight of the hopper 17 as a material supply section by hanging it or the like. The signal is converted into an electric signal and output to the measurement control unit 35. Since the weight of the hopper 17 does not change, by measuring the weight of the hopper 17 at a predetermined timing or continuously, the change of the measurement data changes the supply amount (consumption amount) of the material from the hopper 17 to the main screw 7 side. Will respond.

The rotation speed measuring unit 37 is a rotation speed detecting sensor for measuring the rotation speed of the main screw 7 and is a measuring control unit 3.
5, the rotational speed detection sensor 15 in FIG.
Like the case of the reference numeral 31, it is formed of a tachogenerator and a rotary encoder. The measurement control unit 35 captures the weight data from the weighing unit 33 and the rotation speed data from the rotation speed measurement unit 37 at a predetermined timing such as every several seconds or several tens of seconds, and discharges the material per unit time from the measurement data. Has the function of calculating and measuring.

That is, since the rotation speed of the main screw 7 and the discharge amount of the extruder 1 (in other words, the weight fluctuation value of the hopper 17) are in a proportional relationship, the measurement control unit 35 calculates the rotation speed and the weight fluctuation value from the rotation speed and the weight fluctuation value. It has the following three functions and others for estimating the discharge amount. The first function is to calculate the upper limiter, and when the weight variation value of the hopper 17 at the time of measurement exceeds the upper limiter, filter the weight variation value of the hopper 17 with the upper limiter. This corresponds to the main part of the first configuration.

Now, the screw rotation speed uniquely determined as a reference in the range in which the extruder 1 is normally operated is set as a reference rotation speed, and the previous measurement value and the current measurement value when the hopper weight is measured at a fixed period are determined. The difference is defined as a weight variation value (a value that can be directly converted into a “discharge amount” because it is a raw material consumption amount per unit time) and the weight variation value when the main screw 7 of the extruder 1 is operated at a reference rotation speed is calculated. The reference weight fluctuation value, a value obtained by multiplying the reference weight fluctuation value by 1.1 from an empirical rule is defined as a reference upper limiter, and the upper limit value of the weight fluctuation value at an arbitrary screw rotation speed of the extruder 1 is defined as an upper limiter. If so, the relationship between the reference rotation speed of the main screw 7 and its reference weight variation value, the relationship between the screw rotation speed and the weight variation value, and further, the relationship between the reference rotation speed and the reference upper limiter, Number and above Relationship between the limiter is as follows: the upper limit limiter is obtained by the following expression.

Reference rotation speed: Reference weight fluctuation value = Screw rotation speed: Weight fluctuation value Reference rotation speed: Reference upper limiter = Screw rotation speed: Upper limiter Therefore, upper limiter = Reference upper limiter × (Screw rotation speed / Reference) Rotation speed)

The measurement controller 35 determines the upper limiter of the (actual) weight fluctuation value from the reference rotation speed, the reference weight fluctuation value, the reference upper limiter, and the screw rotation speed at a predetermined timing, and obtains the weight fluctuation value at the time of measurement (this time). When the weight fluctuation value exceeds the upper limiter, the upper limiter is used as the weight fluctuation value at the time of measurement. When the weight fluctuation value does not exceed the upper limit limiter, the weight fluctuation value at the time of measurement is used. The current weight value is subtracted from the current weight value to obtain the current weight value. Since the reference upper limiter is automatically obtained from the reference weight fluctuation value, the upper limiter may be considered to be obtained from the reference weight fluctuation value.

In the range where the extruder 1 is normally operated, the relationship between the rotation speed of the main screw 7 and the actual weight variation value, the relationship between the reference rotation speed, the reference weight variation value, and the reference upper limiter, and furthermore, FIG. 2 shows a relationship between an arbitrary screw rotation speed and an upper limiter derived from the relationship. FIG. 3 shows a change in the upper limiter and a change in the actual weight change value when the screw rotation speed changes with the operation progress of the extruder 1.

Referring to FIG. 3, the first function is that when the actual weight fluctuation value at the time of measurement exceeds the calculation upper limiter, the weight fluctuation value at the time of measurement is replaced with the upper limiter (filtering by the upper limiter). Multiply). The second function of the measurement control unit 35 is to calculate a change rate limiter,
When the weight change change value of the hopper 17 at the time of measurement exceeds the change rate limiter, the change rate limiter filters the weight change change value, and corresponds to the main part of the above-described second configuration.

Here, the difference between the previous rotation speed and the current rotation speed of the screw rotation speed measured at the same time when the hopper weight is measured at a fixed period is defined as the screw rotation speed change, and the weight in the screw rotation speed change of the extruder 1 is determined. When the upper limit of the fluctuation change value is the change rate limiter, and the current change rate limiter recorded at the previous sample is the previous change rate limiter,
It looks like this: Number of rotations of main screw 7 and hopper 1
7, the relationship between the reference rotation speed and the reference weight variation value, the relationship between the rotation speed change of the main screw 7 and the weight variation change value, and further, the reference rotation speed and the reference upper limiter And the relationship between the rotation speed change of the screw 7 and the change rate limiter is as follows, and the change rate limiter is obtained by the following equation.

Reference rotation speed: reference weight fluctuation value = screw rotation speed change: weight fluctuation change value Reference rotation speed: reference upper limiter = screw rotation speed change: change rate limiter change rate limiter = reference upper limit limiter × (screw rotation speed change) / Reference rotation)

The measurement controller 35 obtains a change rate limiter at a predetermined timing from a change in the reference rotation speed, the reference weight change value, the reference upper limiter, and the change in the rotation speed of the main screw 7, and obtains the weight change change value at the time of measurement (this time). If the weight change change value exceeds the change rate limiter, the change rate limiter is added to the previous weight change change value to obtain the weight change value at the time of measurement. If the change value does not exceed the change rate limiter, the weight change change at the time of measurement is calculated. In addition to the function of measuring the discharge amount using the hopper 17, the present weight change value is subtracted from the weight of the hopper 17 at the time of the previous measurement to obtain the current weight value. Since the reference upper limiter is automatically determined from the reference weight fluctuation value, it may be considered that the change rate limiter is also determined from the reference weight fluctuation value.

Actually, the response of the weight fluctuation change value to the screw rotation speed change is delayed, and it is necessary to take this into consideration. Therefore, for example, in response to a step input to the extruder 1, a response is given to two thirds in the first sample, and a response to the remaining one third (one third of two thirds) in the next sample. It is preferable to add a filtering process for delay.

Further, since the extruder 1 may gradually decrease the discharge amount due to clogging of the breaker plate or the like even though the screw rotation speed is not changed, a minimum play is required to cope with this. It is necessary to have a minimum limiter that is a width, and this minimum limiter also serves as a play width for the above-described filtering process for response delay. Therefore, from these two requirements, it is preferable to set an equation for finally obtaining the change rate limiter as follows.

Change rate limiter = 2 × change rate limiter / 3
+ Previous change rate limiter / 2 + minimum limiter

The third function of the measurement control unit 35 is to automatically correct the reference rotation speed and the reference weight fluctuation value by the above-described upper limiter and the integrated value of the actual weight fluctuation value, thereby changing the raw material and the machine. Even if the relationship between the screw rotation speed and the discharge amount changes due to wear or the like, it is possible to accurately cope with the change, and corresponds to the main part of the third configuration described above. Each time the measurement control unit 35 obtains the upper limiter and the change rate limiter from the reference rotation speed, the reference weight change value, and the actual rotation speed of the main screw 7 at a predetermined timing, the actual weight change value and the upper limit limiter are set to a plurality of times, for example, 10 times. This function has a function of comparing the actual weight integrated value with the upper limit filter integrated value, and updating the reference weight fluctuation value by the following equation if the actual weight fluctuation integrated value is equal to or greater than the upper limit filter integrated value.

Reference upper limiter = Reference upper limiter +
(Actual weight integrated value-upper limit filter integrated value) / integration count

If the actual weight integrated value is less than the upper limit filter integrated value and the discharge amount is always acceptable, the measurement controller 35 has a function of correcting the reference upper limiter and the reference rotation speed by the following equation. ing.

Reference rotation = current screw rotation number Reference upper limiter = (actual weight integrated value × 1.1) / integration number

Note that the discharge amount acceptable state refers to a state in which the measured value of the discharge amount is within the acceptable range of the target discharge amount.
The judgment is made by the comparison function of the measuring unit built in this system.
Incidentally, although not shown, the measurement control unit 35 described above includes a CPU, a ROM storing an operation program of the CPU, and a RAM temporarily storing operation data and the like.
It is constituted by a microcomputer having an I / O as an interface.

Next, the operation of the above-described discharge amount measuring apparatus according to the present invention will be described with reference to the flowcharts of FIGS.

In FIG. 6, when the program starts, it is determined in step 100 whether or not the measurement time (measurement timing) of the weight of the hopper 17 and the number of revolutions of the main screw 7 has been reached. Repeat. 6 to 8, the “number” and “value” of the rotation speed, the weight value, the fluctuation value, and the fluctuation change value are omitted for convenience.

If YES in step 100, the weight of the hopper 17 is measured in step 101 as the current weight, the number of revolutions of the main screw 7 is measured and stored as the current number of revolutions, and the process proceeds to step 102. The current weight value is subtracted from the previous weight value to obtain and store the current weight fluctuation value. Step 103
Then, the current upper limiter is determined from the reference upper limiter, the current rotation speed, and the reference rotation speed, and it is determined in a succeeding step 104 whether or not the current weight fluctuation value has exceeded the upper limit limiter. When the answer is NO, the current weight value is replaced with the previous weight value for the next calculation in step 105, and the routine proceeds to step 107 in FIG.

If YES in step 104, the upper limiter is replaced with the current weight fluctuation value in step 106 and stored, and the upper limiter is subtracted from the previous weight value and stored as the previous weight value. Up to this point, the first function, that is, the calculation of the upper limiter and the filtering process by the upper limiter have been described.

Next, as shown in FIG.
Then, the previous weight fluctuation value is subtracted from the current weight fluctuation value to obtain the current weight fluctuation change value, and the previous rotation speed is subtracted from the current rotation speed and stored as the current rotation change value. In step 108, the change rate limiter is calculated from the reference upper limiter, the current rotation change value, and the reference rotation speed. In step 109, the current change rate limiter is calculated from the change rate limiter, the previous change rate limiter, and the minimum limiter. Move to 110.

In step 110, the current weight variation change value is compared with the current variation limiter. If the current weight variation change value is smaller and the result is NO, the process proceeds to step 112. If the current change in weight fluctuation is larger and step 110 is YES, in step 111 the current change rate limiter is added to the previous weight fluctuation value to obtain the current weight fluctuation value, and the current weight fluctuation value is subtracted from the previous weight value. Then, it is stored as the previous weight value, and in the following step 112, the current weight fluctuation value is replaced with the previous weight fluctuation value, and in step 113, the ejection amount is calculated. These steps 107 to 112 are the calculation of the change rate limiter and the filtering process based on the calculation.

In the following step 114, the reference rotation speed and the reference weight fluctuation value are corrected (filter automatic correction processing).
Then, the process returns to step 100 in FIG. This processing step is as shown in FIG. That is, step 1
In step 15, 1 is added to the number of times of integration to obtain the number of times of integration. In step 116, the actual weight fluctuation is added to the current actual weight fluctuation to obtain the weight fluctuation addition value. Is added to obtain an upper limit filter integrated value, and in step 117, it is determined whether or not the integrated number has reached a predetermined number. That is, every time step 116 is executed, the actual weight fluctuation integrated value and the upper limit filter integrated value are updated.

If the predetermined number of times has not been reached, step 117
In the case of O, the process ends and returns to step 100 in FIG. 6. If the number of times has reached the predetermined number and step 117 is YES, it is determined in step 118 whether or not the actual weight fluctuation integrated value is equal to or larger than the upper limit filter integrated value. If the actual weight fluctuation integrated value is equal to or more than the upper limit filter integrated value and step 118 is YES, in step 119 the reference weight fluctuation value is calculated from the reference weight fluctuation value, the actual weight fluctuation integrated value, the upper limit filter integrated value and the number of times of integration. Then, the process proceeds to step 122, where the actual weight fluctuation integrated value becomes smaller than the upper limit filter integrated value, and
In the case of O, it is determined in step 120 whether or not the ejection amount is acceptable.

If the ejection amount is rejected and step 120 is NO, the process proceeds to step 122. If the ejection amount is accepted and step 120 is YES, step 121 is executed.
The actual weight integrated value is multiplied by 1.1 and replaced by the value obtained by dividing the integrated value by the reference upper limiter, while the screw speed is now replaced by the reference speed, and the reference speed and the reference upper limiter are automatically corrected. , Step 122
Move on to In step 122, the number of times of integration, the actual weight fluctuation integrated value, and the upper limit filter are each cleared to "0", and the processing ends.

As described above, in the discharge amount measuring apparatus of the extruder according to the present invention, not only the weight fluctuation of the hopper 17 but also the rotation speed of the main screw 7 is measured to calculate the upper limiter and the change rate limiter. Since the upper limiter and / or the weight change are filtered, even if the weight value of the hopper 17 vibrates, an accurate discharge amount can be obtained quickly.

FIGS. 9 and 10 are operating characteristic diagrams showing the weight fluctuation when filtering is performed by the upper limiter or the change rate limiter, and the vibration of the calculated weight fluctuation with respect to the input weight fluctuation is suppressed. I understand. Further, FIG. 11 is a characteristic diagram showing a weight change when both the upper limiter and the change rate limiter are applied, and it can be seen that the bias is suppressed as compared with FIG.

Further, since the configuration is such that the upper limiter and the integrated value of the actual weight fluctuation value are automatically corrected based on the integrated value, there is an advantage that an accurate discharge amount can be calculated even if the relationship between the screw rotation speed and the discharge amount changes. . The method of correcting the reference rotation speed and the reference upper limiter from the actual weight fluctuation integrated value and the upper limiter integrated value is not limited to the above-described method.

Next, a discharge amount control device according to the present invention will be described with reference to FIG.
This will be described with reference to FIG. This discharge amount control device includes the measuring unit 33, the measurement control unit 35, and the rotation speed measuring unit 37 described above.
Further, a speed command unit 39, a pushing motor 41 and a take-off motor 43 are added, and the function of the measurement control unit 35 is expanded. That is, the speed command unit 39
Is a speed command signal for rotationally driving the push-out motor 41 and the take-up motor 43 similar to the push-out motor 13 and the take-up motor 27 shown in FIG. 12 according to the operation amount as the rotation speed signal based on the calculation of the measurement control unit 35. And the same speed command signal is output unless the next rotation number signal is output from the measurement control unit 35.
It has a latch function or a memory function for continuously outputting to the memory.

The measurement control unit 35 processes the deviation from the set desired discharge amount by a conventionally known moving average method based on the discharge amount obtained by the above-described discharge amount calculation function, and also performs PID constants by PID constants. It has a function of performing arithmetic processing and outputting an operation amount, and is connected to the speed command unit 39. In addition, the measurement control unit 35 is configured as shown in FIGS.
As shown in the above, when the deviation between the calculated discharge amount obtained by the above-described calculation and the set discharge amount is within a predetermined small range, that is, during stable operation, the number of moving averages is increased to, for example, 10 times. When the PID constant (constant 1) having a slow response speed is used and the deviation exceeds a predetermined small range as in the case of product switching, that is, during transition, the number of moving averages is reduced to, for example, two, and the response speed is fast. The PID constant (constant 2) can be switched.

In such a discharge amount control device of the present invention,
Since the number of processings of the moving average method and the constant of the PID operation are switched according to the magnitude of the deviation, the arithmetic processing is performed, and the rotation speed signal is output to the speed command unit 39. On the other hand, good control of stability can be obtained even when the deviation is small such as during stable operation. By the way, the deviation criterion for switching the number of times of the moving average method processing and the constant of the PID operation is preferably such that the deviation between the calculated discharge amount and the set discharge amount is within about 1 to 5% of the maximum rated discharge amount of the extruder 1.

In the present invention, the measurement control unit 35
Is not limited to the configuration in which the deviation is calculated by the moving average process or the PID calculation process using the calculated discharge amount calculated by the processes of FIGS. 6 to 8 described above, and the deviation is calculated by using the material consumption obtained by the conventionally known method. The purpose can be achieved even by a configuration in which moving average processing or PID calculation processing is performed. Further, in the discharge amount control device of the present invention, the object of the present invention can be achieved without necessarily providing the speed command unit 39. In the configuration without the speed command unit 39, the extrusion motor 41 and What is necessary is just to form so that a speed signal may be output to the take-up motor 43 side.

Further, the present invention is not limited to the case where both the extrusion motor 41 and the take-up motor 43 are controlled, and a configuration in which at least the extrusion motor 41 is controlled is also possible. Furthermore,
In the discharge amount control device of the present invention, even if the supply amount of the material to the cylinder 9 is measured almost accurately and quickly, it takes some time before the molten plastic material is extruded from the cylinder 9 by the rotation of the main screw 7. Although there is a delay, it is only necessary to control the extrusion motor 41 and the take-off motor 43 in consideration of the so-called dead time, so that the discharge amount can be controlled almost accurately.

In each of the embodiments described above, the extruder 1 having one main screw 7 has been described. However, the present invention can be applied to an extruder using a plurality of screws. Needless to say, the above-described weighing unit 33, measurement control unit 35, speed command unit 39, and the like are mounted in the control device A in FIG.

[0054]

As described above, according to the first configuration of the discharge amount measuring apparatus of the present invention, the weight of the material supply section for supplying the material to the screw side of the extruder is measured, and the rotation speed of the screw is measured. Is measured, and the upper limiter is obtained from the relationship between the ratio of the reference weight fluctuation value to the reference rotation speed of the screw and the ratio of the upper limiter of the weight fluctuation value to the rotation speed of the screw. If it does not exceed, the measured weight fluctuation value is used as it is, and if the weight fluctuation value at the time of measurement exceeds that, the upper limiter is used as the weight fluctuation value at the time of the measurement, and the rotation of the screw due to the weight fluctuation of the material supply unit Since the discharge amount is measured in consideration of the number, accurate and prompt measurement of the discharge amount is possible even if the measured weight of the material supply unit fluctuates with time. Further, a second configuration according to the discharge amount measuring device of the present invention measures the weight of a material supply unit that supplies a material to a screw side of an extruder, measures the number of rotations of the screw, and sets a reference for the screw. The change rate limiter is determined from the relationship between the ratio of the reference weight change value to the rotation speed and the change rate limiter ratio of the weight change value to the screw speed change, and the weight change change value at the time of measurement exceeds the change rate limiter. When there is no change, use the measured weight change change value as it is, and when the weight change change value at the time of measurement exceeds the change rate limiter, add the change rate limiter to the weight change change value at the previous measurement and add the weight at the time of the measurement. Since the configuration is such that the discharge amount is measured by using the change amount, the discharge amount can be measured accurately and quickly as in the first configuration. In the second configuration, in a configuration in which a change rate limiter is calculated by adding a predetermined minimum limiter, an appropriate discharge amount can be measured with a certain width even if there is no change in the number of rotations. There are advantages. Furthermore, those first
And in the second configuration, the upper limiter is obtained from the relationship between the ratio of the reference weight fluctuation value to the reference rotation speed of the screw and the ratio of the upper limiter of the weight fluctuation value to the rotation speed of the screw. When the actual weight fluctuation value is integrated multiple times and the upper limit limit integrated value exceeds the actual weight fluctuation integrated value, the reference rotation speed and the reference upper limit limiter are corrected from the actual weight fluctuation integrated value and the upper limit limit integrated value and measured. Even if the relationship between the screw rotation speed and the discharge rate changes due to a change in the raw material or the wear of the machine, the reference weight and the reference rotation speed are automatically changed, and accurate discharge over time is always achieved. Quantity measurement becomes possible. Further, the discharge amount control device of the present invention measures the weight of the material supply unit that supplies the material to the screw side of the extruder, measures the rotation speed of the screw, and determines the rotation speed of the screw and the material supply unit. Moving average method and PID from discharge amount calculated based on measured weight
When the deviation between the calculated discharge amount and a preset set discharge amount is larger than a predetermined value, the operation amount is reduced and the operation amount is calculated with a fast response control constant. Since the operation amount is calculated with a slow response control constant and the moving average number is increased when the value is smaller than the value, the discharge amount is controlled by outputting the operation amount to at least the rotation drive motor side of the screw,
For example, at the start-up of the extruder, during product switching, and during stable operation, regardless of the magnitude of the deviation of the discharge amount from the set value, stable product molding can be achieved by suppressing wasteful raw material consumption. There are advantages that are possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a discharge amount control device including a discharge amount measuring device according to the present invention.

FIG. 2 is a diagram for explaining the operation of the discharge amount measuring device of FIG. 1;

FIG. 3 is a diagram for explaining the operation of the discharge amount measuring device of FIG. 1;

FIG. 4 is a diagram illustrating the operation of the discharge amount control device of FIG. 1;

FIG. 5 is a diagram illustrating the operation of the discharge amount control device of FIG. 1;

FIG. 6 is a flowchart illustrating an operation of the discharge amount measuring device of FIG. 1;

FIG. 7 is a flowchart illustrating an operation of the discharge amount measuring device of FIG. 1;

FIG. 8 is a flowchart illustrating an operation of the discharge amount measuring device of FIG. 1;

9 is an operation characteristic diagram of the discharge amount measuring device of FIG.

FIG. 10 is an operation characteristic diagram of the discharge amount measuring device of FIG. 1;

11 is an operation characteristic diagram of the discharge amount measuring device of FIG.

FIG. 12 is a diagram illustrating an extrusion molding line.

FIG. 13 is a diagram illustrating a conventional material supply configuration.

FIG. 14 is a diagram illustrating a conventional discharge amount measuring device.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 Extrusion molding machine 3 Take-off machine 5 Molded product 7 Main screw (screw) 9 Cylinder 11 Molding machine stand 13, 41 Extrusion motor 15, 31 Rotation speed detection sensor 17 Hopper (material supply unit) 19 Material storage unit 19a Shutter 21, 33 Measuring unit 23 Temperature sensor 25 Pressure sensor 27, 43 Pickup motor 29 Pickup roller 35 Measurement control unit 37 Rotation speed measurement unit 39 Speed command unit A Control device

Claims (5)

[Claims] 1. A measuring section for measuring a weight of a material supply section for supplying a material to a screw side of an extruder, a rotation number measuring section for measuring a rotation number of the screw, and a reference for a reference rotation number of the screw. Determine the upper limiter from the relationship between the ratio of the weight fluctuation value and the ratio of the upper limiter of the weight fluctuation value to the rotation speed of the screw,
When the weight fluctuation value at the time of measurement does not exceed the upper limit limiter, the measured weight fluctuation value is used as it is, and when the weight fluctuation value at the time of measurement exceeds the upper limit limiter, the weight fluctuation at the time of the upper limit limiter is measured. A measurement control unit for measuring a discharge amount of the extruder by using the value as a value. 2. A measuring section for measuring a weight of a material supply section for supplying a material to a screw side of an extruder, a rotation number measuring section for measuring a rotation number of the screw, and a reference to a reference rotation number of the screw. The change rate limiter is obtained from the relationship between the ratio of the weight change value and the ratio of the change rate limiter of the weight change value to the rotation speed change of the screw, and the weight change change value at the time of measurement exceeds the change rate limiter. When there is no change, the measured weight change change value is used as it is, and when the weight change change value at the time of measurement exceeds the change rate limiter, the change rate limiter is added to the weight change change value at the previous measurement to perform the measurement. A measurement control unit for measuring a discharge amount of the extruder by using the change amount of the weight of the extruder, and a discharge controller for the discharge amount of the extruder. 3. The discharge amount measuring device for an extrusion molding machine according to claim 2, wherein the measurement control unit calculates the change rate limiter by adding a predetermined minimum limiter. 4. The upper limiter is determined from a relationship between a ratio of a reference weight fluctuation value to a reference rotation speed of the screw and a ratio of an upper limiter of the weight fluctuation value to the rotation speed of the screw. The upper limiter and the actual weight change value are integrated a plurality of times, and when the actual weight change integrated value exceeds the upper limit limiter integrated value, the reference rotation speed and the reference upper limiter are calculated from the actual weight change integrated value and the upper limit limiter integrated value. The discharge amount measuring device for an extruder according to claim 1, wherein the discharge amount of the extruder is measured after correction. 5. A measuring section for measuring a weight of a material supply section for supplying a material to a screw side of an extruder, a rotation number measuring section for measuring a rotation number of the screw, a rotation number of the screw and the material. Moving average method and PID from the discharge amount calculated based on the measured weight of the supply unit
A measurement control unit that calculates an operation amount by calculation, wherein when a deviation between the calculated discharge amount and a preset set discharge amount becomes a predetermined value or more, the number of moving averages is reduced and a fast response control constant is used. Calculating the operation amount, when the deviation is smaller than a predetermined value, increase the number of moving averages and calculate the operation amount with a slow response control constant, and output the operation amount to at least the rotary drive motor side of the screw. And a measurement control unit for controlling a discharge amount extruded from the extruder.