JP3560816B2 - Control method for quantitative cutout of powder - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control method for quantitatively cutting out powder.
[0002]
[Prior art]
Conventionally, when powder is cut out and transported, for example, Japanese Patent Laying-Open No. 4-125214 proposes a method of automatically cutting out powder and transporting it quantitatively. That is, in this method, as shown in FIG. 8 , a piezoelectric element 32 that is means for generating ultrasonic vibration is attached to one end of a hollow pipe 31 made of, for example, acrylic, and an AC voltage is applied by an AC power supply 33. Vibration in the radial direction is given by the piezoelectric element 32, and a traveling wave is generated in the longitudinal direction by the vibration, and the traveling wave is attenuated toward the other end, so that the inside of the hollow pipe 31 is indicated by an arrow F. It is intended to convey the powder in the direction.
[0003]
[Problems to be solved by the invention]
However, when trying to cut out a small amount of powder by the above-described conventional method, there is a disadvantage that it takes time to adjust the AC voltage applied to the piezoelectric element 32. In particular, when applying to a batch process that cuts out a fixed amount at a time, it is time-consuming because it is necessary to check the accuracy by weighing each time with a weighing scale or an electronic scale.Therefore, accuracy is sacrificed in the mass production process. The reality is that the speed and efficiency have been improved.
[0004]
The present invention has been made in order to solve the problems of the conventional technology as described above, and provides a method for controlling the quantitative cutout of powder that can be performed with high accuracy without impairing the efficiency even in a batch process. With the goal.
[0005]
[Means for Solving the Problems]
According to the present invention, the powder stored in the stack is cut out by a powder supply device into a horizontal portion of a powder transporting cylinder, and the flow rate of the powder is reduced while the powder is naturally dropped through a vertical portion of the powder transporting cylinder. It is measured by the flow rate sensor and input to the powder flow rate arithmetic and control unit, and based on the calculation result of the powder flow rate arithmetic and control unit, the quantitative cutout of the powder to be filled into the powder container so as to obtain a predetermined quantitative amount. In the control method, the calculation process of the powder flow rate calculation control device includes a calibration step of cutting out an arbitrary flow rate of the powder of the brand in advance and converting it into an actual weight, and a step of setting a target cutout amount of the powder as a fixed amount. And, instructing the powder supply device to start cutting out the powder, activating the powder supply device to drop the powder, and calculating a passing amount of the powder in the gradually increasing start end region, Cut out a certain amount Calculating the passage amount of the powder in the constant flow rate region in which is performed, and assuming that the passage amount of the gradually decreasing end region is equal to the passage amount in the start end region, predicting the gate-off time; and Stopping the powder supply device when reaching the above, simultaneously predicting the cut-out end time, and, when reaching the cut-out end time, calculating the total amount of passing of the powder and ending the cut-out This is a method for controlling quantitative cutout of powder .
[0006]
Note that, in the calibration step, the gate-off time is fixed to an arbitrary value, powder cutting of the brand is performed, and the cutting coefficient is measured with an electronic balance to determine a relation coefficient for converting the amount into an actual weight. Is good.
Further, regarding the prediction of the gate-off time, after obtaining the predicted gate-off time, the time of the corresponding predicted end point before the gate-off time was obtained, and when the time of the predicted end point was reached, the measurement was performed by that time. The actual gate-off time may be set based on the flow rate .
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of one embodiment of the present invention.
In this figure, 1 is a stack for accommodating powder 2. Reference numeral 3 denotes a powder transporting cylinder made of a cylindrical tube of acrylic or the like for transporting the powder 2, and an upper end opening thereof is connected to a lower end supply port 1 a of the stack 1.
[0008]
Reference numeral 4 denotes a powder supply device attached to the horizontal portion 3a of the powder transport cylinder 3, for example, an ultrasonic vibration device using a piezoelectric element, a screw feeder, a table feeder, a belt conveyor, or the like.
Reference numeral 5 denotes a powder flow sensor which is attached to the vertical portion 3b of the powder transporting cylinder 3 and falls down the vertical portion 3b of the powder transporting cylinder 3, for example, a so-called electrostatic device utilizing the principle of capacitance. A capacitive flow sensor is suitable. Reference numeral 6 denotes a powder container such as a capsule.
[0009]
Reference numeral 7 denotes a powder flow rate arithmetic control device such as a microcomputer, which inputs a flow rate signal from the powder flow rate sensor 5 through an AD converter or the like, based on a predetermined target cutout amount W (g). The level of the applied voltage to be applied to the powder supply device 4 is calculated, and a control signal is output to the powder supply device 4 based on the calculated value, and the amount of powder to be fed into the powder container 6 in a feedback manner Control.
[0010]
Here, an example of the capacitance type flow sensor 10 used for the powder flow sensor 5 will be briefly described. As shown in FIGS. The measuring electrode 12 to be detected as a change and the reference electrode 13 used for correcting environmental conditions are provided in parallel.
The measurement electrode 12 is provided between a cylindrical tube 14 such as a quartz glass tube serving as a flow path of the powder and a pair of curved source electrodes 15 and sense electrodes 16 arranged to face the outer periphery thereof. The reference electrode 13 includes a pair of curved source electrodes 19, a sense electrode 20, and a pair of guard electrodes 21 which are disposed to face each other on a cylindrical tube 18 such as a quartz glass tube and the outer periphery thereof. It consists of. Air is supplied to the reference electrode 13 from an air supply device 23 via an air supply pipe 22.
[0011]
The dielectric constant ε of the powder to be measured is set as a circuit constant in the powder flow rate arithmetic and control unit 7 in advance, and air is supplied from the air supply device 23 to the reference electrode 13 prior to the measurement. The environmental condition of the atmosphere where the body is placed is measured and given as a correction value to the powder flow rate arithmetic control unit 7.
Next, the flow rate of the powder supplied from the stack 1 to the powder transporting cylinder 3 is measured by the measurement electrode 12, and is processed by the powder flow rate calculation control device 7. In this manner, by correcting the atmospheric environmental conditions using the reference electrode 13, the zero point drift of the capacitance type flow sensor can be suppressed low, and the linearity can be dramatically improved. Becomes possible .
[0012]
By configuring the powder flow rate sensor 5 in this manner, the powder 2 contained in the stack 1 is sent out to the horizontal portion 3a of the powder transfer cylinder 3 by activating the powder supply device 4, and The powder 2 that has passed through the body supply device 4 falls naturally through the vertical portion 3b, passes through the powder flow sensor 5, and is filled in the powder container 6. The amount of the powder 2 filled in the powder container 6 is measured by the powder flow rate arithmetic and control unit 7 collecting and analyzing the output signal of the powder flow rate sensor 5, and the powder supply unit 4 is controlled each time. By doing so, quantitative cutout is performed.
[0013]
Next, the concept of the procedure of the powder flow rate calculation control unit 7 by quantitative cutout control of the powder, will be described with reference to FIG. FIG. 4 exemplifies a typical temporal transition of the cut-out flow rate of the powder.
As shown, the powder is cut is started at time T _S, the instantaneous value of the cut-out flow rate R is increased almost linearly in time T _BS reaches the constant flow, the time T _BE from time T _BS until cut in Teiryuryo F, it is assumed that clipping is completed at time T _bE after almost linearly decreased by the time T _E. The constant flow rate F is an amount physically determined by the driving strength of the powder supply device 4. In the case of an ultrasonic vibrator, the constant flow rate F is determined by an applied voltage or vibration. In that case, it will be restricted by the traveling speed.
[0014]
Here, the time zone from the time T _S to the time T _BS is defined as the start end area A, the time zone from the time T _BS to the time T _{BE is} defined as the constant flow rate area B, and the time zone from the time T _BE to the time T _E is defined. Let it be a termination area C. Note that T _ON is a gate-on time at which the powder supply device 4 is started, and T _OF is a gate-off time at which the powder supply device 4 is stopped. T _END is the cutout end time, and indicates the time when the powder has completely stopped falling.
Step (1) : As a calibration step, using a powder of the same brand as the powder used for the measurement, the gate-off time T _OF is fixed to an arbitrary value, and an arbitrary flow rate is cut out, and the cut-out is performed. A relation coefficient for measuring the amount with an electronic balance and converting the amount into an actual weight is obtained in advance.
Step (2) : Set the target cutout amount W of the powder.
Step (3) : At time T _ON , a command is issued to the powder supply device 4 to start cutting out the powder.
Step (4): Start powder supplying device 4 by dropping the powder predetermined passage amount Q _A of the powder in the initial region A from time T _S and the time T _BS by powder flow rate sensor 5 Interval Is calculated.
Step (5): Time performs clipping in T _BS since constant flow F, passes the performs computation of throughput Q _B of the powder in the constant flow area B, passing amount Q _C of the end region C at the start area A The gate-off time T _OF is predicted, assuming equal to the quantity Q _A.
Step (6): a gate-off time the powder supplying device 4 when it reaches the T _OF stop, predicts the end time T _END cut simultaneously.
Step (7) : When the cut-out end time T _END has been reached, the total amount of passage Q _T of the powder (= Q _A + Q _B + Q _C ) is calculated.
Step (8) : End the cutout.
[0015]
FIG. 5 shows a flow of this series of powder cutting control.
In the above example, the prediction of the gate-off time T _OF is performed in step (5) . However, if it is desired to predict the gate-off time T _OF more accurately, at the time T _{BS in} step (4) , Although not shown, first, the expected gate-off time T _OFL is obtained, then the end predicted point time T _ADJ is obtained, and when the end predicted point time T _ADJ is reached, the gate-off time T _OF is predicted again. Good to do.
[0016]
【Example】
Hereinafter, the content of the specific operation when applied to the present invention method the actual process will be described in detail with reference to FIG.
1) In a calibration step, the gate-off time T _OF is fixed to an arbitrary value in advance, and a powder of a specified brand is cut out at a predetermined flow rate and measured, and the cut-out amount is measured by an electronic balance. Then, the average weight coefficient K _VGN , the average fall time ratio K _DLYN , and the average end area time P _KEDN required for the calculation for converting to the actual weight are obtained as follows.
[0017]
Average weight coefficient K _VGN = _Cutout amount actual measurement value / End integral value Average head time ratio K _DLYN = Moving average value of head time ratio K _DLY (= End head time / Start head time) (N times calibration)
Moving average value of average end area time P _KEDN = end area time P _KED (= fall end time-constant flow end time) (N times of calibration)
2) Set the target cutout amount W _TAG of the powder. Then, from the given target cutout amount W _TAG , a target integral value S _TAG is obtained by the following equation (1).
S _TAG = W _TAG / K _VGN ……………… (1)
Here, K _VGN is an average weight coefficient obtained by calibration.
[0018]
3) In response to the cut-out start command, the voltage output V of the powder flow sensor 5 is read a predetermined number of times while the powder is not flowing, and averaged to obtain an offset voltage V _OFS . By using this offset voltage, it is possible to prevent the powder flow rate sensor 5 from changing its sensitivity due to powder adhesion.
[0019]
4) The applied voltage is output (gate on) to the powder supply device 4 to start cutting out the powder. This gate-on time is set to T _ON , and the integrated value S is accumulated from this time.
5) Thereafter, the output data of the powder flow sensor 5 is collected and analyzed at regular time intervals and used for cutout control. Collect the following data until the end of clipping. Note that n = 1, 2, 3,...
[0020]
5-1) The output V _RED (n) of the powder flow sensor 5 is read, the offset voltage V _OFS is reduced, and the obtained read value V (n) is stored in the memory.
V (n) = _VRED (n) _−VOFS (2)
5-2) Add the read value V (n) to the integral value S.
S (n) = S (n-1) + V (n) (3)
[0021]
5-3) Calculate the moving average value V _AVE of the read values (the average of the past m values at the time point n).
V _AVE (n) = (V (n-m + 1) + ... + V (n-2) + V (n-1) + V (n)) / m
……………… (Four)
5-4) Each time difference value V _DIF of the moving average is obtained by the following equation (5).
V _DIF (n) = V _AVE (n) −V _AVE (n−1) ……………… (5)
Here, n = 2, 3, 4,..., V _DIF (1) = 0.
[0022]
6) Obtain the time T _{S at} which the powder starts to pass from the analysis of the collected data.
The start of the passage is determined based on the moving average value V _AVE ≧ start level L _S , and corresponds to the instantaneous fluctuation of the data. Further, by using the end head time obtained from the start head time and the average head time ratio, it is possible to cope with the detection delay of the powder flow sensor 5 due to the natural fall of the powder. Further, it is possible to cope with a change in the distance between the powder supply device 4 and the powder flow sensor 5 and a change in the type of the powder.
[0023]
6-1) With the time at this point as the fall start time TS, a start fall time _PTS is obtained by the following equation (6).
_{P TS = T S -T ON ..................} (6)
6-2) The end fall time _PTE is obtained by the following equation (7).
P _TE = P _TS・ K _DLYN ……………… (7)
Here, K _DLYN is an average head time ratio obtained by calibration.
[0024]
7) obtaining a throughput Q _A at time T _BS and initial region A constant flow passage start of powder from the analysis of the collected data. Here, the detection of the start of the passage of the constant flow rate is determined by the following equation (8), and the detection position is stabilized and the movement is enabled.
Each time difference value of moving average of data V _DIF ≦ peak of difference value × end point level L _BS
……………… (8)
Therefore, when the difference value V _DIF of the moving average falls below the end point level L _BS after passing through the peak, the following processing is performed to obtain the estimated gate-off time T _OFL and the time T _ADJ of the end prediction point.
[0025]
7-1) the time of this point to the constant flow start time T _BS.
7-2) Store the read value V _BS and the integral value S _S at this point in the memory.
7-3) assuming the amount Q _C in the terminal region C the same as the amount Q _A of initial region A, the following (9) to (11) by the integrated value S _B at constant flow region B, to the gate-off The time P _BL and the expected off time T _OFL are obtained.
[0026]
S _B = S _TAG −S _S・ 2 ……………… (9)
P _BL = S _B / V _BS .................. (10)
T _OFL = T _BS + P _BL -P _TE (11)
Here, S _{TAG is a} target integrated value (quantitative value), and S _S is an integrated value of the start region A.
[0027]
7-4) Further, a time T _{ADJ of the} predicted end point is obtained.
T _ADJ = T _BS + (T _OFL −T _BS ) · K _ADJ ............ (12)
Here, K _{ADJ is} a movement coefficient of the predicted end point (= 0.2 to 0.8).
8) When the time T _ADJ at the predicted end point is reached, the following processing is performed to obtain the already passed amount of the powder and to obtain and change the gate-off time T _OF again. By changing the gate-off time T _OF, the cutout accuracy can be improved.
[0028]
8-1) Store the integrated value S _ADJ at this point in the memory.
8-2) The amount (integral value) of the terminal area C is predicted from the average value of the quantitative area B according to the following equations (13) to (15), and the gate-off time T _OF is obtained.
a) The average value V _ADJ of the read values in the constant flow rate region is obtained by the following equation (13).
V _ADJ = (S _ADJ -S _S ) / (T _ADJ -T _BS ) (13)
expected integral value S _E of b) termination region by either a calculation using the or termination factors and initial region and the same amount, to select the next b-1) or b-2).
[0029]
b-1) S _E = S _S
b-2) S _E = V _ADJ・ P _KEDN・ K _E
Here, P _KEDN : average termination area time obtained by calibration, and K _E : termination adjustment coefficient.
[0030]
c) The constant flow area remaining time P _B is obtained by the following equation (14).
P _B = (S _TAG −S _ADJ −S _E ) / V _ADJ (14)
d) The gate-off time T _OF is obtained by the following equation (15).
T _OF = T _ADJ + P _B -P _TE (15)
9) At the gate-off time T _OF , output 0 voltage (gate-off) to the powder supply device 4 to stop cutting out the powder.
10) The end of the passage of the powder is detected from the analysis of the collected data, and the cutout end time T _END is obtained.
[0031]
That is, the passage end is determined based on the moving average value V _AVE ≦ start level L _S and corresponds to the instantaneous fluctuation of the data.
10-1) and the time of this point fall end time T _E.
10-2) Obtain the cutout end time T _END by the following equation (16).
T _END = T _E + (T _E −T _OF ) (16)
11) When the cutout end time T _END is reached, the total amount of powder that has passed is obtained. End integration value S _ALL Is stored in the memory, and the total cutout amount W _ALL is obtained by the following equation (17).
W _ALL = S _ALL・ K _VGN …………… (17)
[0032]
12) Obtain the time T _BE at the end of the constant flow of the powder from the analysis of the collected data.
The detection of the end of the passage of the constant flow rate is determined by the following (18), and the detection position is stabilized and the movement is enabled.
Each time difference value V _DIFX of the moving average viewed from the end direction ≤ difference value peak x end point level L _BS ... (18)
The average falling time ratio K _DLYN and the average terminal area time P _KEDN related to the _gate- off time prediction are learned. Thus, it is possible to cope with a change in the operation status and improve the cutout accuracy.
[0033]
12-1) The time at this point is defined as the constant flow end time T _BE .
12-2) The end fall time _PTE is obtained by the following equation (19).
P _TE = T _BE -T _OF .................. (19)
12-3) The fall time ratio K _DLY is obtained by the following equation (20), and the average fall time ratio K _DLYN is updated.
[0034]
K _DLY = P _TE / P _TS …………… (20)
12-4) The terminal area time P _KED is obtained by the following equation (21), and the average terminal area time P _KEDN is updated.
P _KED = T _E −T _BE …………… (21)
The setting of the presence / absence of updating (learning) of the average head time ratio and the average end area time is enabled.
13) Finish cutting out.
[0035]
Using the method of the present invention, powder of light calcium carbonate S-10, which is one of the standard powders of the standard of the APPIE (Japan Powder Industry Technology Association) standard, is quantified at 2 g, 4 g, 6 g, and 8 g. As a result, as shown in FIG. 7 , high-precision results of 4.7% maximum, 0.1% minimum, and 2.5% average were obtained.
[0036]
【The invention's effect】
As described above, according to the present invention, when a fixed amount of powder is cut out using the powder supply device, the feedback control is performed using the powder flow rate sensor. It is possible to control the cutout of the fixed amount.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a side view partially showing a structure of a capacitance type flow sensor as a powder flow sensor used in the present invention.
FIG. 3 is a sectional view taken along the line II of FIG. 2;
FIG. 4 is a characteristic diagram showing a temporal transition of a cut-out flow rate of powder in the present invention.
FIG. 5 is a flowchart of a powder cutting control according to the present invention.
FIG. 6 is a characteristic diagram showing a temporal transition of a cut-out flow rate of powder when the method of the present invention is applied to an actual process.
FIG. 7 is a characteristic diagram showing a measurement example according to the method of the present invention.
FIG. 8 is a perspective view showing a conventional example of powder conveyance.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stack 2 Powder 3 Powder transfer cylinder 3a Horizontal part 3b Vertical part 4 Powder supply device 5 Powder flow sensor 6 Powder container 7 Powder flow calculation control device
10 Capacitive flow sensor
11 outer cylinder
12 Measurement electrode
13 Reference electrode
14, 18 Cylindrical tube
15, 19 Source electrode
16, 20 sense electrode
17, 21 Guard electrode
22 Air supply pipe
23 Air supply device
31 hollow pipe
32 Piezoelectric element
33 AC power supply

Claims (3)

The powder contained in the stack is cut out by a powder supply device into a horizontal portion of the powder transport cylinder, and the flow rate is measured by a powder flow sensor while naturally falling through the vertical portion of the powder transport cylinder. And input to the powder flow rate arithmetic and control unit, based on the calculation result of the powder flow rate arithmetic and control unit, in a fixed quantity cutout control method of the powder to be filled in the powder container so as to obtain a given quantity in advance , The calculation process of the powder flow rate calculation control device is a calibration step of cutting out an arbitrary flow rate of the powder of the brand in advance and converting it into an actual weight, a step of setting a target cutout amount of the powder as a quantitative amount, Instructing the supply device to start cutting out the powder, activating the powder supply device to drop the powder, calculating the amount of passage of the powder in the gradually increasing starting end region, and cutting out a fixed amount of the powder. Made Calculating the passage amount of the powder in the constant flow rate region, assuming that the passage amount of the gradually decreasing end region is equal to the passage amount in the start end region, and predicting the gate-off time; and Stopping the powder supply device, simultaneously predicting the cut-out end time, and, when the cut-out end time is reached, calculating the total amount of passing of the powder and ending the cut-out, Control method for quantitative cut-out of powder. In the calibration step, the gate-off time is fixed to an arbitrary value, powder is cut out of the brand, the cut-out amount is measured with an electronic balance, and a relation coefficient for converting to an actual weight is obtained. 2. The method according to claim 1 , wherein the powder is quantitatively cut out. The prediction of the gate-off time is performed by obtaining the predicted gate-off time, obtaining the time of the end prediction point corresponding to the time before the gate-off time, and based on the flow rate actually measured up to that time when the time of the end prediction point is reached. quantitative cutout control method of a powder according to claim 1, wherein setting the actual gate-off time Te.

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