JP2000055721A - Loss-in-weight type granule dispensing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable constant flow rate control with high precision even when a flow rate set value is very small. SOLUTION: A measuring part 5 measures and detects that granule 1 is discharged by the amount of weight reduction. On the basis of the discharge weight value calculated from the measured weight value and a previously set flow rate value a PI control means 21 performs every cycle control in such a manner that a constant amount of granule 1 is continuously supplied. When the flow rate set value is very small, a time when the measured weight changes from the flow rate set value to the minimum scale amount based on the resolution of the measuring part is calculated. By a period changing means, 23 the control period is changed to be larger than or equal to the time. As a result, erroneous control which is to be caused by erroneously judging that weight change is not present can be prevented, and precision of the constant flow rate control can be excellently maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loss-in-weight type powder / particle quantitative supply apparatus.

[0002]

2. Description of the Related Art A so-called loss-in-weight type powder / particle quantitative supply apparatus for continuously supplying a powder / particle at a constant amount while detecting that the powder / particle has been discharged by an amount corresponding to a decrease in weight is shown in FIG. As schematically shown in FIG. 1, a weighing hopper 2 into which the granular material 1 is charged, a screw feeder 3 for discharging the granular material 1 in the weighing hopper 2, and a driving motor 4 for driving the screw feeder 3 A weighing device 5 including a weighing hopper 2, a screw feeder 3, a driving motor 4, and the like, and a weighing device 5, and a controller 10 for controlling the weighing device 5.
And input means 6 including a numeric keypad for inputting various setting values to the controller 10, and display means 7 for confirming input data and indicating an operating state.

As a control method for supplying this kind of powder 1 quantitatively, a weight value (weight loss value) discharged from a measured weight value measured by a weighing device 5 is calculated, and a target supply weight value and a discharge result are calculated. Based on the sum of the parameter value proportional to the deviation from the weight value and the parameter value proportional to the integral value of the deviation,
A so-called PI for continuously controlling the supply flow rate of the granular material 1
2. Description of the Related Art A weight loss continuous control method by (proportional integration) control is known. According to this control method, generally, good responsiveness can be obtained, the actual discharge weight value of the granular material 1 can be smoothly brought close to the supply target weight value, and when a relatively small flow rate is quantitatively supplied. However, it is possible to supply a fixed amount without lowering the precision.

[0004] More specifically, the operation unit 12 of the PI control means 11 provided in the controller 10 executes a control program consisting of the following control operation formula at a predetermined fixed cycle (for example, every 0.1 second). ing.

[0005]

(Equation 1)

Here, ΔMV accelerates the driving motor 4,
The change in the deceleration signal (MV), P is a proportional constant, ε is the deviation (target supply weight value (reference value) −discharge actual weight value), I
Is the integration time. In the PI (proportional integration) control, the following operation is performed when the deviation ε occurs.

The control output is corrected instantaneously by a factor of 100 / P (P is%) of the deviation ε (proportional (P) operation). The correction of the same value as the correction value by the above-mentioned proportional operation is executed over I time (integration (I) operation).

For example, the set value of the proportionality constant P is input as "200" from the input means 6, this data is set in the proportionality constant setting means 13, and the set value of the integration time I is input as "40". When 4 seconds, which is 40 times the fixed cycle of 0.1 second, is set in the integration time setting means 14, these data are stored in the arithmetic unit 12
The PI control means 11 calculates the deviation .epsilon.
The control output correction of 5 times (= 100/200) is executed instantaneously, and the correction of the same value is executed in 4 seconds. In this way, excellent response is obtained, and at the same time, the actual discharge weight value of the granular material 1 smoothly approaches the target supply weight value.

[0009]

However, when performing the PI control as described above, when the flow rate set value is extremely small and the weight change during one cycle is smaller than the resolution of the weighing device 5, May cause the following problems. That is, since the weight change amount during one cycle is smaller than the minimum scale based on the resolution of the weighing device 5, as shown schematically in FIG. The measured weight value does not change over a plurality of control cycles even if it is present. As a result, it is erroneously recognized that there is no change in weight, and the driving motor 4 is accelerated and the accuracy of the constant flow rate control is reduced. There was something. For example, the minimum scale of the measuring device 5 based on the resolution is 0.2 g, and the flow rate setting is 0.1 k.
g / h (≒ 0.028 g / sec), 1
Since it takes about 7 seconds to change the scale, the accuracy of the constant flow rate control may be reduced during this time.

The present invention solves the above-mentioned problem, and provides a loss-in-weight type powder / particle quantitative supply apparatus capable of performing a constant flow rate control with high accuracy even when a flow rate set value is an extremely small flow rate. The purpose is to do so.

[0011]

According to a first aspect of the present invention, there is provided a method for measuring and detecting the discharge of a granular material by an amount measured by a measuring device. A loss-in weight that is controlled by the control means in each cycle so as to continuously supply the granular material in a constant amount based on the discharged weight value calculated from the measured weight value and a preset flow rate set value. This is a powdery material fixed-rate supply device of a formula, which is provided with a cycle changing means for changing a control cycle.

With this configuration, when the flow rate set value is extremely small, the time during which the measured weight changes by the minimum scale based on the resolution of the weighing device is calculated from the flow rate set value, and the control cycle is set to this time. As described above, when the weight is changed by manual operation or the like, when the control is performed in each cycle, the measured weight value that is almost equal to or greater than the minimum scale fluctuates. This prevents erroneous control from being performed, thereby maintaining the accuracy of the constant flow rate control.

According to a second aspect of the present invention, in the loss-in-weight type powder and granular material supply apparatus according to the first aspect, the cycle changing means determines the minimum value based on the resolution of the measuring device from a preset flow rate set value. This is a cycle automatic setting means for calculating a time during which the measured weight changes by the scale and automatically setting the control cycle to be longer than this time.

According to this configuration, even when the flow rate set value is changed to an extremely small flow rate, the cycle is automatically set to an appropriate control cycle by the cycle automatic setting means, and the attendant calculates or operates the cycle. Therefore, the accuracy of the constant flow rate control can be maintained satisfactorily, the work efficiency is improved, and the reliability is improved because calculation errors do not occur.

The third aspect of the present invention provides the first or second aspect.
In the loss-in-weight type particulate material quantitative supply device described in the above, the control means, a parameter value proportional to the deviation between the target supply weight value and the actual discharge weight value based on the flow rate set value,
This is a PI control means for continuously controlling the supply flow rate of the granular material based on the sum of a parameter value proportional to the integral value of the deviation. According to this configuration, the control is performed based on the deviation. PI control can be performed with high accuracy.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The components having substantially the same functions as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, a controller 20 for controlling each part of the loss-in-weight type powder and granular material quantitative supply apparatus has a weight value (weight loss weight value) discharged from the measured weight value measured by the weighing device 5. ) Is calculated based on the sum of the parameter value proportional to the deviation between the target supply weight value and the actual discharge weight value and the parameter value proportional to the integral value of the deviation. A PI (proportional-integral) control means 21 for controlling is provided. The PI control means 21 includes an operation unit 12 having the same function as that of the related art, a proportional constant setting means 1
3. In addition to the integration time setting means 14, a cycle changing means 22 for changing the control cycle is provided. Then, by inputting a control cycle from the input means 6 in a predetermined mode, the control cycle of the PI control means 21 is changed by the cycle changing means 22.

With this configuration, when the flow rate set value is an extremely small flow rate, an attendant or the like calculates the time during which the measured weight changes to the minimum scale based on the resolution of the weighing device 5 from the flow rate set value, and performs control. The control cycle of the PI control means 21 is manually changed via the cycle changing means 22 by inputting from the input means 6 so that the cycle becomes longer than this time.

For example, the minimum scale of the measuring device 5 based on the resolution is 0.2 g, and the flow rate setting is 0.1 kg / h (ｈ
0.028 g / sec), it takes about 7.14 (≒ 0.2 / 0.028) seconds until one graduation changes. Therefore, by inputting, for example, “72” as the control cycle n, The control cycle is changed to 7.2 seconds (= 0.1 sec × 72).

As a result, when the PI control means 21 controls each cycle, the measured weight value of the weighing device 5 fluctuates more than the minimum scale of 0.2 g or more. As schematically shown in FIG. 2, the measured weight value is detected as an actual value corresponding to each control cycle. As a result, the drive motor 4 can be appropriately PI controlled, and the accuracy of the constant flow rate control can be improved. It can be held well.

In the cycle changing means 22, the set value n of the control cycle (control cycle = 0.1 sec × set value n)
Can be freely set as an integer in the range of 0 to 9999, and the control cycle can be set to an integral multiple of 0.1 second as described above. Further, for example, by inputting the set value n as “1”, the control cycle 0.1 as in the related art is set.
Secondly, if the set value n is set by inputting “0”, the PI control is not performed and, for example, the movement of the measured weight loss weight value is performed several times within a predetermined period. Calculate the average value, calculate the actual discharge weight value from the value obtained by dividing the weight difference of this moving average value by the elapsed time, and control so that the calculated actual discharge weight value approaches the target supply weight value. Has become. Thereby, the control method can be switched as required.

FIG. 3 shows another embodiment of the present invention. The PI control means 31 of the controller 30 provided in the loss-in-weight type powder and granular material supply apparatus is provided with the above-described embodiment. Instead of the cycle changing means 22 of the embodiment, a time during which the measured weight changes to the minimum scale based on the resolution of the weighing device 5 is calculated from a preset flow rate set value so that the control cycle is longer than this time. A cycle automatic setting means 32 for automatically setting is provided. Specifically, when the minimum scale M (g) and the flow rate set value F (kg / h) are set, the cycle automatic setting means 31 controls the control cycle C (in units of 0.1 sec).
To the following formula

[0023]

(Equation 2)

The minimum integer that satisfies is calculated and the control cycle C is automatically set. According to this configuration, even when the flow rate set value is changed to an extremely small flow rate, the cycle automatic setting means 32 automatically sets an appropriate control cycle. Similarly to the above case, when the minimum scale of the weighing device 5 based on the resolution is 0.2 g and the flow rate setting is 0.1 kg / h, (36 × 0.2) ÷ 0.1 = 72. Therefore, the control cycle is automatically set to 7.2 seconds (= 0.1 sec × 72). Thereby, in the above embodiment, each time the flow rate set value is changed, the attendant calculates and sets the control cycle,
Although much labor and time have been required, such operations can be omitted and work efficiency can be improved. Further, in the above-described embodiment, there is a possibility that a clerk may erroneously calculate the control cycle when calculating the control cycle. However, in this embodiment, the above-described inconvenience does not occur, and thus the reliability is improved.

The automatically set control cycle is displayed on the display means 7.
May be displayed, and the control cycle may be manually changed. Instead of automatically setting the control cycle, a control cycle that is considered to be appropriate may be automatically calculated and displayed on the display unit 7, and the control cycle may be manually changed.

[0026]

As described above, according to the present invention, based on the discharged weight value calculated from the measured weight value and the preset flow rate set value, the powder and granules are continuously supplied in a constant amount. In a loss-in-weight type powder and granular material supply device controlled by the control means for each cycle, the control cycle can be changed by the cycle changing means so that the flow rate set value is extremely small. However, the accuracy of the constant flow rate control can be kept good, and the reliability is improved.

As a period changing means, a time during which the measured weight changes to a minimum scale based on the resolution of the weighing device is calculated from a preset flow rate set value, and an automatic control is performed so that the control period becomes longer than this time. By performing the setting, even when the flow rate set value is changed, the work efficiency is improved without manual operation, and the control cycle is accurately calculated, so that the reliability is also improved.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a loss-in-weight type powder / particle quantitative supply apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a measured weight value and a driving motor speed in the same granular material supply apparatus.

FIG. 3 is a view schematically showing a loss-in-weight type powder / particle quantitative supply apparatus according to another embodiment of the present invention.

FIG. 4 is a view schematically showing a conventional loss-in-weight type powder and granular material supply apparatus.

FIG. 5 is a diagram showing a relationship between a measured weight value and a driving motor speed in the conventional granular material supply device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 powder and granular material 2 weighing hopper 3 screw feeder 4 driving motor 5 weighing device 6 input means 7 display means 12 calculation unit 13 proportional constant setting means 14 integration time setting means 20, 30 controller 21, 31 PI control means 22 cycle changing means 32 Cycle automatic setting means (cycle changing means)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F046 AA00 BB02 CA01 DA03 DA07 FA13 3F075 AA08 BA01 BB01 CA04 CA06 CA09 CB01 CB03 CB04 CB05 CB12 CB15 CB16 CC03 CC05

Claims (3)

[Claims] 1. A weighing device measures and detects that a granular material has been discharged by an amount corresponding to a reduced weight, and based on the discharged weight value calculated from the measured weight value and a preset flow rate set value. A loss-in-weight type powder / particle quantitative supply apparatus in which the control means controls the cycle at a time so as to continuously supply the powder at a constant amount. Equipped with a loss-in-weight type powder and granular material supply device. 2. The cycle changing means calculates, from a preset flow rate set value, a time during which the measured weight changes by a minimum scale based on the resolution of the weighing device, and automatically controls the control cycle so as to be longer than this time. 2. The loss-in-weight type powder and granular material supply apparatus according to claim 1, wherein said automatic setting means is a period automatic setting means. 3. The control means, based on a sum of a parameter value proportional to a deviation between the target supply weight value and the actual discharge weight value based on the flow rate set value and a parameter value proportional to an integral value of the deviation, 3. The loss-in-weight type powder and granular material supply device according to claim 1, wherein the PI control means is a PI control unit that continuously controls a supply flow rate of the powder and granules. 4.