JP3865249B2 - Extruder discharge rate control device - Google Patents

Description

  The present invention relates to an improvement in a discharge amount control device that contributes to uniform quality of an extruded product from an extruder.

  An extrusion line for extruding a long product such as a plastic pipe or a laminate such as a plastic sheet is formed by connecting a take-up machine 3 to an extruder 1 and extruding from the extruder 1 as shown in FIG. The molded product 5 is taken up by the take-up machine 3.

  The extrusion molding machine 1 places a cylinder 9 incorporating a main screw 7 on a molding machine base 11, and an extrusion motor 13 that rotationally drives the main screw 7 on the molding machine base 11 and the rotation speed of the extrusion motor 13. A rotation speed detection sensor 15 for detecting the above is disposed.

  A hopper 17 that supplies plastic material into the cylinder 9 is disposed on the cylinder 9, and a material storage portion 19 that is filled with a plastic material that is replenished into the hopper 17 is disposed above the hopper 17.

  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 weighing data is transmitted to the control device A (see FIG. 12). ) Is output.

  When the remaining amount of plastic material in the hopper 17 decreases, the shutter 19a of the material storage unit 19 (slightly changed from FIG. 12) is opened by the control from the control device A or manually, and the plastic material is transferred to the hopper 17. It is designed to be refilled inside.

  Reference numerals 23 and 25 in FIG. 12 are a temperature sensor and a pressure sensor arranged in 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 is extruded as a molded product 5 from a tip die (not shown) of the cylinder 9 by the rotational drive of the main screw 7. The product is taken up by a take-up roller 29 driven to rotate by a take-up motor 27 and commercialized.

  The rotational speed of the take-up motor 27 is detected by a rotational speed detection sensor 31 similar to the sensor 15 and is output to the control device A.

  The control device A takes in the weighing data from the weighing unit 21 and the rotation number signals of the extrusion motor 13 and the take-off motor 27 from the rotation number detection sensors 15 and 31, and discharges the extruded product 5 per unit time. The rotational speeds of the motors 13 and 27 are controlled so that the amount (volume) is uniform.

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

  However, the above-described conventional discharge amount control method in the extrusion line has the following disadvantages.

  That is, the plastic material in the hopper 17 falls by its own weight according to the decrease in the plastic material extruded from the extruder 1 as the main screw 7 rotates, and is supplied into the cylinder 9.

  On the other hand, the crest 7a of the main screw 7 periodically passes near the material charging port 9a of the cylinder 9 during rotation of the main screw 7 (see FIG. 12), and the crest 7a of the main screw 7 inputs the material of the cylinder 9. When passing through the vicinity of the mouth 9a, the peak portion 7a of the main screw 7 pushes up the hopper 17, and the measured weight is temporarily reduced, and the temporal change of the measured weight is accompanied by vibration. Become.

  Therefore, the hopper weight measured by the weighing unit 21 does not change as shown by the diagonal line in FIG. 14 when there is no material replenishment from the material storage unit 19, and vibrates as indicated by the broken line of the waveform in FIG. Therefore, if the material supply amount is measured in a short interval measurement, a large error is likely to occur, and it must be measured in a relatively long period, for example, a few minutes at the shortest. It was difficult to measure, and it was difficult to make the quality of the molded product 5 uniform and to quickly change the thickness.

  Therefore, as a result of careful observation and examination of the operation of the extrusion molding machine 1, particularly the discharge amount from the cylinder 9 and the rotation speed of the main screw 7, the discharge amount and the screw rotation speed are approximately proportional to each other. The present invention has been completed by paying attention to the fact that the discharge amount can be more accurately controlled using the relationship.

  The present invention has been made under such circumstances, and a discharge amount control device capable of stabilizing the discharge amount from the extrusion molding machine regardless of the deviation between the discharge amount and the set value. Is to provide.

In order to solve such a problem, the discharge amount control device of the present invention includes a measuring unit that measures the weight of a material supply unit that supplies material to the screw side of an extruder, and a rotation that measures the number of rotations of the screw. A measurement control unit for calculating an operation amount by a desired set moving average method and PID calculation from a number measurement unit and a discharge amount calculated based on a rotation number of the screw and a measured weight of the material supply unit, When the deviation between the calculated discharge amount and the preset set discharge amount is equal to or greater than a predetermined value, the operation average is calculated with a quick response control constant in the PID calculation while reducing the moving average number in the moving average method , when the deviation is smaller than a predetermined value, calculating the operation amount of slow response control constants in the PID calculation with increasing the moving average frequency in the moving average method , And a measurement control section for controlling the discharge amount and outputs the operation amount to at least the rotary drive motor side of the screw.

  In the discharge amount control apparatus of the present invention, as the measurement control unit, the ratio of the reference weight fluctuation value to the reference rotation speed of the screw and the ratio of the weight fluctuation value of the material supply unit to the screw rotation speed equal to this ratio. And the ratio of the reference upper limiter obtained from the weight fluctuation value to the reference rotational speed and the ratio of the upper limiter limit of the weight fluctuation value to the screw rotational speed equal to this ratio, the upper limiter 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.When the weight fluctuation value at the time of measurement exceeds the upper limit limiter, the upper limit limiter is used as the weight at the time of the measurement. The calculation discharge amount can be calculated by using it as a fluctuation value.

  In the discharge amount control apparatus of the present invention, as the measurement control unit, the ratio of the reference weight fluctuation value to the reference rotation speed of the screw and the ratio of the weight fluctuation value of the material supply unit to the screw rotation speed equal to this ratio. And the ratio of the reference upper limit limiter obtained from the weight fluctuation value with respect to the reference rotational speed and the ratio of the change rate limiter of the weight fluctuation value with respect to the screw speed change equal to this ratio, When a change rate limiter is obtained, and when the weight fluctuation change value during measurement does not exceed the change rate limiter, the measured weight fluctuation change value is used as it is, and when the weight fluctuation change value during measurement exceeds the change rate limiter Can be configured to calculate the calculated discharge amount by adding the change rate limiter to the weight fluctuation change value at the previous measurement and using it as the weight fluctuation change value at the time of the measurement. It is.

  Furthermore, in the discharge amount control apparatus of the present invention, the measurement control unit can be configured to calculate the change rate limiter by adding a predetermined minimum limiter.

  Furthermore, in the discharge amount control device of the present invention, as the measurement control unit, the ratio of the reference weight fluctuation value to the reference rotation speed of the screw, and the weight fluctuation value of the material supply section with respect to the screw rotation speed equal to this ratio. The ratio of the reference upper limit limiter obtained from the weight fluctuation value with respect to the reference speed and the ratio of the upper limit limiter of the weight fluctuation value with respect to the screw speed equal to this ratio The upper limiter is obtained, and this upper limiter and the actual weight fluctuation value are integrated several times. When the actual weight fluctuation integration value exceeds the upper limiter integration value, the reference speed and the actual weight fluctuation integration value and the upper limiter integration value are calculated. The reference upper limiter may be modified to calculate the calculated discharge amount.

  In the discharge amount control apparatus according to the present invention, the weight of the material supply part that supplies the material to the screw side is measured, the rotational speed of the screw is measured, and the discharge calculated based on the rotational speed and the measured weight of the material supply part The operation amount is calculated from the amount by the moving average method and the PID calculation, and when the deviation between the calculated discharge amount and the preset set discharge amount is larger than the predetermined value, the moving average number is reduced and the operation amount is set with a quick response control constant. When the deviation is smaller than the predetermined value, the moving average number is increased and the operation amount is calculated with a slow response control constant, and the operation amount is output to at least the rotational drive motor side of the screw to control the discharge amount. Because of the configuration, for example, at the time of startup of the extrusion molding machine, at the time of product switching and at the time of stable operation, no matter whether the deviation of the discharge amount from the set value is large or small. There is an advantage that it is possible to stable product molded by suppressing a raw material consumed in.

  Then, the measurement control unit determines the relationship between the ratio of the reference weight fluctuation value to the reference rotation speed, the ratio of the weight fluctuation value of the material supply section to the rotation speed equal to the ratio, and the weight fluctuation with respect to the reference rotation speed. This upper limit limiter is obtained from the relationship between the ratio of the reference upper limit limiter obtained from the value and the ratio of the upper limiter limit of the weight fluctuation value to the rotation speed equal to this ratio, and the weight fluctuation value at the time of measurement is the upper limit limiter. If the measured weight fluctuation value is used as it is, and the weight fluctuation value at the time of measurement exceeds the upper limit limiter, the calculated discharge amount is measured using the upper limit limiter as the weight fluctuation value at the time of measurement. In this configuration, even if the measured weight of the material supply unit oscillates with time, it is possible to calculate the discharge amount accurately and promptly. From this point also, the discharge amount of the extruder can be reduced. It becomes possible to achieve reduction.

  In addition, the measurement control unit has a relationship between a ratio of the reference weight fluctuation value to the reference rotation speed of the screw and a ratio of the weight fluctuation value of the material supply unit to the rotation speed equal to the ratio, and the reference rotation speed. The change rate limiter is obtained from the relationship between the ratio of the reference upper limit limiter obtained from the weight fluctuation value to the ratio and the ratio of the change rate limiter of the weight fluctuation value to the rotation speed change equal to this ratio, and the weight at the time of measurement is obtained. When the fluctuation change value does not exceed the change rate limiter, the measured weight fluctuation change value is used as it is, and when the weight change change value during measurement exceeds the change rate limiter, the weight change change value at the previous measurement is In a configuration that is configured to measure the calculated discharge amount using the change rate limiter and using it as the weight fluctuation change value at the time of the measurement, similarly, the calculation of the discharge amount can be performed accurately and quickly. Possible and it also becomes possible to stabilize the discharge amount of the extruder in this respect.

  Further, the measurement control unit is configured to calculate the change rate limiter by adding a predetermined minimum limiter, so that an appropriate discharge amount can be measured with a certain width even if there is no change in the rotational speed. There is an advantage that becomes possible, and this also contributes to the stability of control.

  Furthermore, the measurement control unit is configured so that the ratio of the reference weight fluctuation value to the reference rotation speed of the screw and the ratio of the weight fluctuation value of the material supply section to the rotation speed equal to the ratio and the reference rotation The upper limiter is obtained from the relationship between the ratio of the reference upper limiter obtained from the weight fluctuation value to the number and the ratio of the upper limiter of the weight fluctuation value to the number of revolutions equal to the ratio, and the upper limiter and the actual weight are obtained. When the fluctuating value is accumulated several times and the actual weight fluctuation accumulated value exceeds the upper limit limiter accumulated value, the reference rotation speed and the reference upper limiter are corrected from the actual weight fluctuation accumulated value and the upper limiter accumulated value, and the above calculated discharge amount In the configuration that is configured to measure the load, even if the relationship between the screw rotation speed and the discharge amount changes due to changes in raw materials or machine wear, these Is changed weight and reference speed over time always enables accurate discharge amount calculation, it is possible to stabilize the discharge amount of the extruder.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a discharge amount control apparatus according to the present invention. In addition, since the structure of an extrusion molding line is the same as that of FIG. 12 mentioned above, this is referred.

  First, for convenience, the discharge amount measuring function of the discharge amount control apparatus according to the present invention will be described.

  In FIG. 1, the weighing unit 33 corresponds to the weighing unit 21 in FIG. 12 and is connected to the measurement control unit 35. The weighing unit 33 measures the weight of the hopper 17 as a material supply unit and measures the 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 in the measurement data becomes the supply amount (consumption amount) of the material from the hopper 17 to the main screw 7 side. Will respond.

  The rotational speed measurement unit 37 is a rotational speed detection sensor that measures the rotational speed of the main screw 7 and is connected to the measurement control unit 35. Similar to the rotational speed detection sensors 15 and 31 of FIG. It is formed from an encoder.

  The measurement control unit 35 takes in the weight data from the weighing unit 33 and the rotation number data from the rotation number measurement unit 37 at a predetermined timing such as every few seconds or every several tens of seconds, and discharges the material per unit time from the measurement data. It has a function to calculate and measure.

  That is, since the rotational 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 determines the discharge amount from the rotation speed and the weight fluctuation value. It has the following three functions to be estimated.

  The first function is to calculate an upper limiter and filter the weight fluctuation value of the hopper 17 with the upper limiter when the weight fluctuation value of the hopper 17 during measurement exceeds the upper limiter.

  Now, the screw rotation number uniquely determined as a reference within the range in which the extruder 1 is normally operated is set as the reference rotation number, and the difference between the previous measurement value and the current measurement value when the hopper weight is measured at a constant cycle is weighted. The fluctuation value (the value that can be converted into the “discharge amount” as it is the raw material consumption per unit time) is used, and the weight fluctuation value when the main screw 7 of the extruder 1 is operated at the reference rotation speed is the reference weight fluctuation. Value, a value obtained by multiplying the reference weight fluctuation value by 1.1 from the rule of thumb as a reference upper limit limiter, and further, if the upper limit value of the weight fluctuation value at any screw speed of the extruder 1 is an upper limit limiter, The relationship between the reference rotation speed of the main screw 7 and its reference weight fluctuation value, the relationship between the screw rotation speed and the weight fluctuation value, between the reference rotation speed and the reference upper limit limiter, the screw rotation speed and the upper limit limiter With The relationship 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

further,
Reference speed: Reference upper limiter = Screw speed: Upper limiter

Therefore,
Upper limiter = reference upper limiter x (screw speed / reference speed)

  The measurement control unit 35 obtains the upper limiter of the (actual) weight fluctuation value from the reference rotation speed, the reference weight fluctuation value, the reference upper limit limiter and the screw rotation speed at a predetermined timing, and the weight fluctuation value at the time of measurement (current weight fluctuation value). ) Exceeds the upper limit limiter, the upper limit limiter is used as the weight fluctuation value at the time of measurement. When the upper limit limiter is not exceeded, the weight fluctuation value at the time of measurement is used, and the current weight from the previous weight value of the hopper 17 at the previous measurement is used. It has the function of subtracting the value to obtain the current weight value.

  Since the reference upper limit limiter is automatically obtained from the reference weight fluctuation value, it may be considered that the upper limit limiter is obtained from the reference weight fluctuation value.

  Then, in the range in which the extruder 1 is regularly operated, the relationship between the rotational speed of the main screw 7 and the actual weight fluctuation value, the relation between the reference rotational speed, the reference weight fluctuation value, and the reference upper limiter, and further derived from these relations. The relationship between the arbitrary screw rotation number and the upper limiter is shown in FIG.

  Further, FIG. 3 shows an upper limit limiter change and an actual weight fluctuation value change when the screw rotation speed is changed with the operation of the extruder 1.

  Referring to FIG. 3, when the actual weight fluctuation value at the time of measurement exceeds the calculation upper limit limiter, the first function replaces the weight fluctuation value at the time of measurement with the upper limit limiter (filtering with the upper limit limiter). It will be.

  The second function of the measurement control unit 35 calculates a rate of change limiter, and when the weight fluctuation change value of the hopper 17 at the time of measurement exceeds the rate of change limiter, the weight rate change value is filtered by the rate of change limiter. It is something to hang.

  Here, the difference between the previous rotational speed and the current rotational speed of the screw rotational speed measured at the same time when the hopper weight is measured at a fixed period is defined as the screw rotational speed change, and the weight fluctuation change value in the screw rotational speed change of the extruder 1 When the change rate limiter is used as the upper limit and the current change rate limiter recorded at the previous sample is the previous change rate limiter, the following is obtained.

  Since the rotation speed of the main screw 7 and the weight fluctuation value of the hopper 17 are in a proportional relationship, the relationship between the reference rotation speed and the reference weight fluctuation value, the relationship between the rotation speed change of the main screw 7 and the weight fluctuation change value, The relationship between the reference rotational speed and the reference upper limit limiter and between the rotational 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 limit limiter = screw rotation speed change: change rate limiter change rate limiter = reference upper limit limiter × (screw rotation speed change / reference rotation number)

  The measurement control unit 35 obtains a change rate limiter from changes in the reference rotation speed, the reference weight fluctuation value, the reference upper limit limiter, and the rotation speed of the main screw 7 at a predetermined timing, and the weight fluctuation change value at the time of measurement (current weight fluctuation change). Value) exceeds the change rate limiter, the change rate limiter is added to the previous weight fluctuation change value to obtain the weight change value at the time of measurement, and when the change rate limiter is not exceeded, discharge using the weight change change at the time of measurement. While measuring the amount, it has a function of subtracting the current weight change value from the weight of the hopper 17 at the previous measurement to obtain the current weight value.

  Since the reference upper limit limiter is automatically obtained from the reference weight fluctuation value, it may be considered that the change rate limiter is also obtained from the reference weight fluctuation value.

  Actually, since the response of the weight fluctuation change value is delayed with respect to the screw rotation speed change, it is necessary to consider it.

  Therefore, for example, in response to a step input to the extruder 1, a response that responds to two-thirds in the first sample and a remaining one-third (one-half of two-thirds) in the next sample responds. It is preferable to add a filtering process for delay.

  Furthermore, the extrusion machine 1 has a minimum play width in order to cope with this because the discharge amount may gradually decrease even though the screw rotation speed does not change due to clogging of the breaker plate or the like. It is necessary to have a minimum limiter, and this minimum limiter also works as a play width for the filter processing part for the response delay.

  Therefore, the formula for finally obtaining the change rate limiter from these two requirements is preferably set 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 rotational speed and the reference weight fluctuation value with the above-described upper limiter and the integrated value of the actual weight fluctuation value, thereby changing the raw material, machine wear, etc. Even if the relationship between the screw rotation speed and the discharge amount changes, it can be accurately handled.

  Each time the measurement control unit 35 obtains the upper limit limiter and the change rate limiter from the reference rotation speed, the reference weight fluctuation value, and the actual rotation speed of the main screw 7 at a predetermined timing, the measurement controller 35 calculates the actual weight fluctuation value and the upper limit limiter a plurality of times, for example, 10 times. Or 30 times, the actual weight integrated value is compared with the upper limit filter integrated value, and if the actual weight variation integrated value is equal to or greater than the upper limit filter integrated value, the reference weight variation value is updated by the following equation.

Reference upper limiter = Reference upper limiter
+ (Actual weight integrated value-upper limit filter integrated value) / number of integrations

  And the measurement control part 35 has a function which correct | amends a reference | standard upper limit limiter and a reference | standard rotation speed by following Formula, if an actual weight integrated value is less than an upper limit filter integrated value, and always discharge amount pass state.

Reference rotation = Current screw speed Reference upper limit limiter = (Actual weight integrated value x 1.1) / Number of integration

  The discharge amount acceptance state refers to a state where the measured value of the discharge amount is within the target discharge amount acceptance range, and is determined by the comparison function of the measurement unit built in the system.

  By the way, although not shown, the measurement control unit 35 described above includes a CPU, a ROM that stores an operation program of the CPU, a RAM that temporarily stores operation data and the like, and an I / O that is an interface. It is composed of a microcomputer.

  Next, the operation of the above-described discharge amount measuring function will be described with reference to the flowcharts of FIGS.

  In FIG. 6, when the program is started, it is determined in step 100 whether or not it is the measurement time (measurement timing) of the weight of the hopper 17 and the rotational speed of the main screw 7. If NO, this is repeated until YES.

  In addition, in the rotation speed, the weight value, the fluctuation value, and the fluctuation change value in FIGS. 6 to 8, the display of “number” and “value” is omitted for convenience.

  When step 100 becomes YES, the weight of the hopper 17 is measured to be the current weight in step 101, the rotational speed of the main screw 7 is measured and stored as the current rotational speed, and the process proceeds to step 102. In step 102, the previous weight value is measured. From this, the current weight value is subtracted to obtain and store the current weight fluctuation value, and the routine goes to Step 103.

  In step 103, the current upper limit limiter is obtained from the reference upper limit limiter, the current rotation speed and the reference rotation speed. In the following step 104, it is determined whether or not the current weight fluctuation value has exceeded the upper limit limiter. 104 becomes NO, and the current weight value is replaced with the previous weight value for the next calculation in step 105, and the process 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. The processing up to here is the first function, that is, the calculation of the upper limiter and the filter processing by this.

  Next, as shown in FIG. 7, in step 107, 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. To do.

  In step 108, the change rate limiter is calculated from the reference upper limit limiter, the current rotation change value and the reference rotation speed, and 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 NO, the process proceeds to step 112.

  If the current weight change is larger and step 110 is YES, the current change rate limiter is added to the previous weight change value in step 111 to obtain the current weight change value, and the current weight change value is subtracted from the previous weight value. Then, in step 112, the current weight fluctuation value is replaced with the previous weight fluctuation value, and in step 113, the discharge amount is calculated.

  These Step 107 to Step 112 are the calculation of the change rate limiter and the filter processing by this.

  In the following step 114, the reference rotation speed and the reference weight fluctuation value are corrected (filter automatic correction process) and the process is terminated, and the process returns to step 100 in FIG. This processing step is as shown in FIG.

  That is, in step 115, 1 is added to the number of integrations to obtain the number of integrations, and in subsequent step 116, the actual weight fluctuation is added to the actual weight fluctuation integrated value to obtain the weight fluctuation addition value, and the upper limit filter integrated value is set. The upper limit filter is added this time to obtain an upper limit filter integrated value, and it is determined in step 117 whether or not the number of integration has reached a predetermined number. Each 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 is not reached and step 117 is NO, the process ends and returns to step 100 in FIG. 6. If the predetermined number of times is reached and step 117 is YES, the actual weight fluctuation integrated value is converted to the upper limit filter in step 118. It is determined whether or not the integrated value is exceeded.

  If the actual weight fluctuation integrated value is equal to or greater 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 integrations. If the actual weight fluctuation integrated value is less than the upper limit filter integrated value and step 118 is NO, it is determined in step 120 whether or not the discharge amount is acceptable.

  If the discharge amount is not acceptable and step 120 is NO, the process proceeds to step 122. If the discharge amount is acceptable and step 120 is YES, the actual weight integrated value is multiplied by 1.1 in step 121. At the same time, the value divided by the integrated value is replaced with a reference upper limit limiter, while the current screw rotation number is replaced with a reference rotation number, the reference rotation number and the reference upper limit limiter are automatically corrected, and the routine proceeds to step 122.

  In step 122, the number of integrations, the actual weight fluctuation integration value, and the upper limit filter are each cleared to “0” and the process ends, and the process returns to step 100 in FIG.

  As shown in FIG. 1, the discharge amount control apparatus according to the present invention includes a speed command unit 39 and a measurement unit 33, a measurement control unit 35, and a rotation speed measurement unit 37 that perform the discharge amount measurement function described above. While having the motor 41 for extrusion and the motor 43 for taking over, the measurement control part 35 is comprised also with the following functions.

  That is, the speed command unit 39 sets the push-out motor 41 and take-up motor 43 similar to the push-out motor 13 and take-up motor 27 in FIG. A latch that outputs a speed command signal for rotational driving and continues to output the same speed command signal to the extrusion motor 41 and the take-off motor 43 unless the measurement control unit 35 outputs the next rotation speed signal. Has a function or memory function.

  The measurement control unit 35 has a function of processing by a conventionally known moving average method from a deviation from a set desired discharge amount based on the discharge amount obtained by the discharge amount calculation function described above, and PID by a PID constant. It has a function of performing arithmetic processing and outputting an operation amount, and is connected to the speed command unit 39.

  Moreover, as shown in FIGS. 4 and 5, the measurement control unit 35 operates when the deviation between the calculated discharge amount obtained by the above-described calculation and the set discharge amount that is set is within a predetermined small range, that is, stable operation. Sometimes the moving average number is increased to 10 times, for example, and a PID constant (constant 1) having a slow response speed is used, and when the deviation exceeds a predetermined small range as in product switching, that is, when moving, The number of times is reduced to, for example, 2 times, and a PID constant (constant 2) having a fast response speed can be switched.

  In such a discharge amount control apparatus of the present invention, the number of moving average method processing and the constant of PID calculation are switched according to the magnitude of the deviation and the rotation number signal is output to the speed command unit 39. When a large deviation is large, control can be performed with a quick response. On the other hand, when the deviation is small as in stable operation, control with good stability can be obtained.

  Further, in the discharge amount control device of the present invention, not only the weight fluctuation of the hopper 17 but also the rotation speed of the main screw 7 is measured and the upper limiter and the change rate limiter are calculated to calculate the upper limiter and / or the weight. Since the filter is applied to the change, an accurate discharge amount can be obtained quickly even if vibration occurs in the weight value of the hopper 17, and it is possible to stabilize the discharge amount of the extruder from this point. Become.

  FIG. 9 and FIG. 10 are operation characteristic diagrams showing weight fluctuations when filtered by the upper limiter or the change rate limiter, and it can be seen that the vibration of the calculated weight fluctuation is suppressed with respect to the input weight fluctuation. .

  Further, FIG. 11 is a characteristic diagram showing the weight fluctuation when both the upper limiter and the change rate limiter are applied, and it can be seen that the bias is also suppressed compared to FIG.

  Further, since the upper limiter and the integrated value of the actual weight fluctuation value are automatically corrected, there is an advantage that an accurate discharge amount can be calculated even if the relationship between the screw speed and the discharge amount changes.

  The method for correcting the reference rotational speed and the reference upper limiter from the actual weight fluctuation integrated value and the upper limiter integrated value is not limited to the method described above.

  Further, in the measurement control unit 35, the deviation standard for switching the moving average method processing number and the PID calculation constant is 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. It is preferable that

  In the present invention, the measurement control unit 35 is not limited to a configuration that performs a moving average process or a PID calculation process using a calculated discharge amount calculated by the processes of FIGS. The object can be achieved even in a configuration in which a moving average process or a PID calculation process is performed using the material consumption obtained by the above.

  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 in which the speed command unit 39 is not provided, the measurement control unit 35 to the extrusion motor 41 or What is necessary is just to form so that a speed signal may be output to the take-out motor 43 side.

  Further, the invention is not limited to controlling both the extrusion motor 41 and the take-off motor 43, and a configuration for controlling at least the extrusion motor 41 is also possible.

  Furthermore, in the discharge amount control device according to the present invention, even if the amount of material supplied to the cylinder 9 is measured almost accurately and quickly, the molten plastic material is somewhat extruded from the cylinder 9 by the rotation of the main screw 7. However, since it is sufficient to control the extrusion motor 41 and the take-up motor 43 in consideration of the so-called dead time, the discharge amount can be controlled almost accurately.

  In each of the above-described embodiments, the description has been given using the extruder 1 having one main screw 7. However, the present invention can be applied to an extruder using a plurality of screws.

  And it cannot be overemphasized that the measurement part 33 mentioned above, the measurement control part 35, the speed instruction | command part 39, etc. are mounted in the control apparatus A in FIG.

It is a block diagram which shows embodiment of the discharge amount control apparatus which concerns on this invention. It is a figure explaining operation | movement of the discharge amount control apparatus of FIG. It is a figure explaining operation | movement of the discharge amount control apparatus of FIG. It is a figure explaining operation | movement of the discharge amount control apparatus of FIG. It is a figure explaining operation | movement of the discharge amount control apparatus of FIG. 2 is a flowchart for explaining the operation of the discharge amount control device of FIG. 1. 2 is a flowchart for explaining the operation of the discharge amount control device of FIG. 1. It is a flowchart explaining operation | movement of the discharge amount control apparatus of FIG. FIG. 2 is an operation characteristic diagram of the discharge amount control device of FIG. 1. FIG. 2 is an operation characteristic diagram of the discharge amount control device of FIG. 1. FIG. 2 is an operation characteristic diagram of the discharge amount control device of FIG. 1. It is a figure explaining an extrusion molding line. It is a figure explaining the conventional material supply structure. It is a figure explaining the conventional discharge amount control apparatus.

Explanation of symbols

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

Claims (5)

A weighing unit for measuring the weight of the material supply unit for supplying the material to the screw side of the extruder,
A rotational speed measurement unit for measuring the rotational speed of the screw;
A measurement control unit that calculates an operation amount by a desired moving average method and PID calculation from a discharge amount calculated based on a rotation speed of the screw and a measured weight of the material supply unit, and the calculated discharge amount and When the deviation from a preset set discharge amount becomes a predetermined value or more, the number of moving averages is reduced in the moving average method and the manipulated variable is calculated with a quick response control constant in the PID calculation. When the value is smaller than a predetermined value , the moving average is increased in the moving average method, the operation amount is calculated with a slow response control constant in the PID calculation, and the operation amount is output to at least the rotational drive motor side of the screw. A measurement control unit for controlling a discharge amount extruded from the extrusion molding machine;
A discharge amount control device for an extrusion molding machine. The measurement control unit includes a relationship between a ratio of a reference weight fluctuation value to a reference rotation speed of the screw, a ratio of a weight fluctuation value of the material supply unit to a rotation speed of the screw equal to the ratio, and the reference rotation speed. The upper limit limiter is obtained from the ratio of the reference upper limit limiter obtained from the weight variation value with respect to the relationship between the ratio of the upper limit limiter of the weight variation value to the rotational speed of the screw that is equal to this ratio, and the measurement at the time of measurement. When the weight fluctuation value does not exceed the upper limit limiter, the measured weight fluctuation value is used as it is.When the weight fluctuation value at the time of measurement exceeds the upper limit limiter, the upper limit limiter is used as the weight fluctuation value at the time of measurement. The discharge amount control device for an extrusion molding machine according to claim 1, wherein the calculated discharge amount is calculated. The measurement control unit has a relationship between a ratio of a reference weight fluctuation value to a reference rotation speed of the screw, a ratio of a weight fluctuation value of the material supply unit to the screw rotation speed equal to the ratio, and the reference rotation speed. The change rate limiter is obtained from the relationship between the ratio of the reference upper limit limiter obtained from the weight fluctuation value and the ratio of the change rate limiter of the weight fluctuation value to the screw speed change equal to this ratio. When the weight fluctuation change value of the measurement does not exceed the change rate limiter, the measured weight fluctuation change value is used as it is, and when the weight fluctuation change value at the measurement exceeds the change rate limiter, the weight fluctuation at the previous measurement is used. The extrusion molding according to claim 1, wherein the calculated discharge amount is calculated by adding the change rate limiter to a change value and using the change rate limiter as a weight fluctuation change value at the time of the measurement. The discharge amount control device. The discharge amount control device for an extrusion molding machine according to claim 3, wherein the measurement control unit calculates the change rate limiter by adding a predetermined minimum limiter. The measurement control unit includes a relationship between a ratio of a reference weight fluctuation value to a reference rotation speed of the screw, a ratio of a weight fluctuation value of the material supply unit to a rotation speed of the screw equal to the ratio, and the reference rotation speed. The upper limit limiter is obtained from the ratio of the reference upper limit limiter obtained from the weight fluctuation value to the ratio and the ratio of the upper limit limiter of the weight fluctuation value to the number of rotations of the screw equal to the ratio. When the actual weight fluctuation value is integrated several times and the actual weight fluctuation integration value exceeds the upper limit limiter integration value, the calculation is performed by correcting the reference rotation speed and the reference upper limiter from the actual weight fluctuation integration value and the upper limit limiter integration value. The discharge amount control device for an extrusion molding machine according to any one of claims 2 to 4, wherein the discharge amount is calculated.

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