JPH1179411A - Fixed quantity picking control method for powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixed quantity picking control method for powder which can be accurately performed without deteriorating efficiency even in a batch process. SOLUTION: Powder 2 received in a stack 1 is picked by a powder supplier 4 to a horizontal location 3a of a powder conveying cylinder unit 3, via a vertical location 3b of the powder conveying cylinder unit 3, while naturally dropped down, this amount is measured by a powder flow sensor 5, to be input to a powder flow rate arithmetic control device 7, based on an arithmetic result of this powder flow rate arithmetic control device 7, a powder vessel 6 is charged with the powder so as to obtain a previously given fixed amount W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for quantitatively cutting out powder.

[0002]

2. Description of the Related Art Conventionally, when powder is cut out and transported, for example, Japanese Patent Application Laid-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. 9, a piezoelectric element 32 which 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]

However, when a small amount of powder is cut out by the above-mentioned 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. The reality is that the speed and efficiency have been improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and has a method for controlling the quantitative extraction of powder that can be performed with high accuracy without impairing the efficiency even in a batch process. The purpose is to provide.

[0005]

According to the present invention, powder stored in a stack is cut out by a powder supply device into a horizontal portion of a powder transporting cylinder, and is cut through a vertical portion of the powder transporting cylinder. While allowing the powder to flow naturally, the flow rate is measured by a powder flow rate sensor and input to the powder flow rate calculation control device. This is a method for controlling the quantitative cutout of powder, characterized by filling the container.

In addition, the calculation process of the powder flow rate calculation control device in the present invention 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 quantifying a target cut-out quantity of the powder. Setting, and instructing the powder supply device to start cutting out the powder, and activating the powder supply device to drop the powder, and calculating the amount of the passage of the powder in the gradually increasing starting end region. And calculating the passage amount of the powder in the constant flow rate region where a fixed amount of cutting is performed, and assuming that the gradually decreasing passage amount in the end region is equal to the passage amount in the start end region, and setting the gate-off time to Predicting, stopping the powder supply device when the gate-off time is reached, and simultaneously predicting the cut-out end time, and calculating the total amount of powder passing when the cut-out end time is reached. And the stage to end the cut-out, so it is preferable to consist of.

In the calibrating step, the gate-off time is fixed to an arbitrary value, powder is cut out of the brand, the cut-off amount is measured with an electronic balance, and the coefficient is converted into an actual weight. It is better to ask. Further, in the prediction of the gate-off time, it is preferable that the time of the predicted end point is obtained after obtaining the predicted gate-off time, and the gate-off time is predicted when the time of the predicted end point is reached.

The powder flow sensor used in the present invention is provided with a measuring electrode for detecting a flow rate of the powder as a change in capacitance and a reference electrode for correcting environmental conditions in parallel. It is preferable to use a capacitance type flow sensor constituted by: The measurement electrode is composed of a pair of curved source electrodes and a sense electrode that are disposed to face the outer periphery of a cylindrical tube that is a flow path of powder, and a guard electrode that is provided therebetween. The reference electrode may be composed of a pair of curved source electrodes, a sense electrode, and a pair of guard electrodes that are arranged to face the outer periphery of the cylindrical tube into which the atmosphere is sent. It is preferable that the source electrode and the sense electrode are spirally wound around the outer circumference of the cylindrical tube at an angle of 45 ° so as to make one round or an integral multiple thereof.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below 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. Numeral 3 is a powder conveying cylinder formed of a cylindrical tube made of acrylic or the like for conveying the powder 2, and an upper end opening thereof has a lower end supply port 1 a of the stack 1.
Connected to.

Reference numeral 4 denotes a powder feeder attached to the horizontal portion 3a of the powder transporting cylinder 3, such as an ultrasonic vibrator 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 transport cylinder 3 and falls down the vertical portion 3b of the powder transport cylinder 3, for example, a so-called electrostatic device using the principle of capacitance. A capacitive flow sensor is suitable. Reference numeral 6 denotes a powder container such as a capsule.

Numeral 7 denotes a powder flow rate arithmetic control unit such as a microcomputer, which inputs a flow rate signal from the powder flow rate sensor 5 through an AD converter or the like, and outputs a predetermined target cutout amount W (g). , The level of the applied voltage to be applied to the powder supply device 4 is calculated based on the calculated value, and a control signal is output to the powder supply device 4 based on the calculated value, and is fed into the powder container 6 in a feedback manner. Controls the amount of powder.

Here, the structure of the capacitance type flow sensor 10 used for the powder flow sensor 5 will be briefly described. As shown in FIGS. A measurement electrode 12 for detecting a change in capacitance and a 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 or the like 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 arranged to face each other around 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.

The dielectric constant ε of the powder to be measured is set as a circuit constant in the powder flow rate arithmetic control unit 7 in advance, and air is supplied from the air supply unit 23 to the reference electrode 13 prior to the measurement. Then, the environmental conditions of the atmosphere where the powder is placed are measured and given to the powder flow rate calculation control device 7 as a correction value. Next, the flow rate of the powder supplied from the stack 1 to the powder transporting cylinder 3 is measured by the measuring 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.

By the way, the source electrode 15 and the sense electrode 16 of the measuring electrode 12 are formed by being spirally wound at an angle θ with respect to the tube axis of the cylindrical tube 14 as shown in FIG. For example, Japanese Patent Application Laid-Open No. 8-271301 discloses a configuration in which the winding angle θ is set to 45 ° because the measured value of the passing position is less affected and the powder flow rate can be measured more accurately. . However, Japanese Patent Application Laid-Open No. 8-271301 does not specifically limit the length L of each of the source electrode 15 and the sense electrode 16.

Therefore, as a result of repeated experiments and studies by the present inventors, the length L of each of the source electrode 15 and the sense electrode 16 goes around the cylindrical tube 14 when the angle θ is 45 °.
We found that it would be better to have a 360 ° length.
That is, by setting the angle to 360 °, even if there is a difference in the density of the powder in the plane of one cross section when passing through the inside of the cylindrical tube 14, the source electrode 15 and the sense electrode 16 arranged at 360 ° Since the positions of all the electric flux densities are recorded and the electric power passes through the entire distance once, it is detected as an averaged value. If its length L is 36
If the angle is smaller than 0 °, the distance across the electrodes becomes shorter, which causes an error.On the other hand, if the angle is larger than 360 °, the position of the same flux density will be re-recorded, so it is not meaningful in terms of accuracy. Will not be.

In the above-described example, a circle 36 around the cylindrical tube 14 is provided.
Although described as 0 °, if it is set to be an integral multiple of 360 °, the measurement accuracy can be further improved because the same powder will surely record over all positions of the electric flux density under the same conditions. Therefore, it can be said that it is preferable. Further, when the length L of the source electrode 15 and the sense electrode 16 of the measurement electrode 12 is limited as described above, the measurement conditions of the reference electrode 13 are naturally adjusted to match the measurement electrode 12. It is desirable that the lengths of the source electrode 19 and the sense electrode 20 be similarly limited.

With this configuration, the powder 2 stored in the stack 1 is sent out to the horizontal portion 3a of the powder transporting cylinder 3 by activating the powder supply device 4, and
The powder 2 that has passed through the powder supply device 4 falls naturally through the vertical portion 3b, passes through the powder flow sensor 4, 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.

Next, the concept of the procedure for the quantitative cutout control of the powder by the powder flow rate arithmetic control unit 7 will be described with reference to FIG. FIG. 5 exemplifies a typical temporal transition of the cutout flow rate of the powder. As shown,
Powder 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, from time T _BS and the time T _BE Teiryuryo F At time T _E , and decreases substantially linearly after time T _BE.
It is assumed that the cutout ends with. The constant flow rate F is an amount physically determined by the driving strength of the powder supply device 4, and is determined by the applied voltage or vibration in the case of an ultrasonic vibrator, the number of revolutions in the case of a screw feeder or a table feeder, and the rotation speed of a belt conveyor. In that case, it is restricted by the traveling speed.

Here, the time T_STo time T_BSTime to
The band is defined as the start end area A, and the time T_BSTo time T_BETime to
The zone is defined as constant flow area B, and time T_BETo time T_EUntil
The interzone is defined as a termination region C. Note that T_ONIs the powder supply device 4
Gate on time to activate_OFStops the powder supply device 4
It is the gate-off time to stop. Also, T_ENDCut out
The end time indicates when the powder has completely dropped.
You. Step: Used as a calibration step in advance for measurement.
Use the same brand of powder as
Time T_OFFixed to an arbitrary value and cut out an arbitrary flow rate.
And the cut-out amount is measured with an electronic balance and converted to the actual weight.
A relation coefficient for performing the calculation is obtained in advance. Step: Set a target cutting amount W of powder. Step: Time T_ONCuts powder into powder supply device 4
Command to start. Step: Activate powder supply device 4 to drop powder
And time T_STo time T _BSIn starting area A up to
Body Q_AAt predetermined intervals by the powder flow sensor 5
calculate. Step: Time T_BSAfter that, cut out at constant flow rate F,
The amount Q of powder passing through in the constant flow rate region B_BWhen you calculate
In both cases, the passing amount Q of the termination region C_CIs the passing in the starting area A
Quantity Q_AAnd the gate off time T_OFPredict
I do. Step: Gate off time T_OFPowder supply when it reaches
The apparatus 4 is stopped, and at the same time, the cutout end time T_ENDPredict
I do. Step: Extraction end time T_ENDWhen you reach the powder
Total body passage Q_T(= Q _A+ Q_B+ Q_C) Is calculated. Step: End the extraction.

FIG. 6 shows a flow of a series of control for cutting out the powder. In the above example, the gate-off time T
_Although the prediction of _OF is performed in steps, if it is intended to more accurately predict the gate-off time T _OF , the predicted gate-off time T _OFL is first obtained (not shown) at the time T _BS of the step. From the predicted end point T
Seeking _ADJ, it is preferable to so predict again gated off time T _OF upon reaching the time T _ADJ of the estimated end point.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a specific operation when the method of the present invention is applied to an actual process will be described below in detail with reference to FIG. 1) In the calibration step, the gate-off time T _OF is fixed to an arbitrary value in advance, and the powder of the designated brand is cut out at a predetermined flow rate and measured, and the cut-out amount is measured with 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.

Average weight coefficient K _VGN = measured value of cutout amount /
End integration value Average head time ratio K _DLYN = Moving average value of head time ratio K _DLY (= End head time / Start head time) (N times of calibration) Average end area time P _KEDN = _End area time P _KED (= Drop Moving average (end time-constant flow end time) (N times of calibration) 2) Set the target cutout amount W _TAG of the powder. And
From the given target cutout amount W _TAG , the target integral value S
_TAG is _calculated by the following equation (1).

S _TAG = W _TAG / K _VGN (1) Here, K _VGN is an average weight coefficient obtained by calibration. 3) In response to the cutout 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.

4) The applied voltage is output to the powder supply device 4 (gate on) to start cutting out the powder. The gate-on time is set to T _ON , and the integrated value S is accumulated from this point. 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,...

5-1) Output V _RED (n) of 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) = V _RED (n) −V _OFS (2) 5-2) Add the read value V (n) to the integral value S. S (n) = S (n-1) + V (n) (3) 5-3) Calculate the moving average value V _{AVE of the} read values (the average of the past m numbers at the time point n). .

V _AVE (n) = (V (n−m + 1) +... + V (n−2) + V (n−1) + V (n)) / m (4) 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,..., And V _DIF (1) = 0.

6) The time T _{S at} which the powder starts passing is obtained from the analysis of the collected data. This passing start is based on the moving average value V
_AVE ≧ start level L _S , which corresponds to instantaneous fluctuation of 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 powder.

6-1) With the time at this point as the fall start time T _S , the start fall time P _TS is obtained by the following equation (6). _{P TS = T S -T ON ..................} (6) 6-2) below (7) determining the end drop time P _TE by formula. P _TE = P _TS · K _DLYN (7) where K _DLYN is an average head time ratio obtained by calibration.

7) From the analysis of the collected data, the
Overstart time T_BSAnd the passing amount Q in the start end area A_AGet
You. Here, the detection of the constant flow passage start is determined by the following equation (8).
To stabilize the detection position and enable its movement.
You. Each time difference value V of moving average of data_DIF≤ peak of difference value x end point level L_BS …………… (8) Then, each time difference value V of the moving average_DIFIs the end through the peak
Point level L_BSIf the following occurs, perform the following processing to
Sou gate off time T_OFLAnd time T of the end prediction point _ADJSeeking
Confuse.

7-1) The time at this point is defined as the constant flow start time T _BS
And 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.

[0031] _{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 integral value (quantitative value), and S _S is an integral value of the start end area A. 7-4) Further, a time T _ADJ at the predicted end point is obtained.

T_ADJ= T_BS+ (T_OFL-T_BS) ・ K_ADJ ............ (12) where K_ADJ: Movement coefficient of end prediction point (= 0.2 to 0.8
 ). 8) Time T of predicted end point_ADJWhen it becomes,
Thus, the amount of powder that has passed has been obtained, and the gate-off time T
_OFIs asked again and changed. This gate-off time T _OFStrange
By doing so, the cutout accuracy can be improved.

8-1) The integrated value S _ADJ at this point is stored 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 by the following equations (13) to (15), and the gate-off time T
_Ask for _OF . a) The average value V _ADJ of the read values in the constant flow rate region is obtained by the following equation (13). Using _{V ADJ = (S ADJ -S S} ) / (T ADJ -T BS) .................. (13) b) or termination factors predicted integration value S _E of the termination region and the starting end region and the same amount Depending on the calculation, the following b-1) or b-2)
Select

[0034] b-1), where _{S E = S S b-2} ) S E = V ADJ · P KEDN · K E, P KEDN: Average termination region time obtained by calibration, K _E: is at the end adjustment factor . c) The constant flow region 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) When the gate-off time T _OF comes, 0 is supplied to the powder supply device 4.
Outputs voltage (gate off) and stops cutting 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.

That is, the passing end is determined by the moving average value V_AVE≤
Start level L_SAnd respond to instantaneous fluctuations in data.
You. 10-1) The time at this point is defined as the fall end time T_EAnd 10-2) Extraction end time T_ENDIs calculated by the following equation (16). T_END= T_E+ (T_E-T_OF) ............ (16) 11) Cutout end time T_ENDWhen the powder reaches
Get the quantity. End integral value S _ALLAnd store it in memory
W_ALLIs obtained by the following equation (17).

W _ALL = S _ALL · K _VGN (17) 12) The time T _BE at the end of the passage of the powder at the constant flow rate is obtained 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. Peak × endpoint level L _BS each time the difference value V _DIFX ≦ difference value of the moving average as seen from the end direction .................. (18) gate-off time expected in the associated average fall time ratio K _dLYn,
Learn about the average termination region time P _{KE DN} . Thus, it is possible to cope with a change in the operation status and improve the cutout accuracy.

12-1) The time at this point is set to the constant flow end time T _BE
And 12-2) The end fall time _PTE is obtained by the following equation (19). P _TE = T _BE −T _OF (19) 12-3) The falling time ratio K _DLY is obtained by the following equation (20), and the average falling time ratio K _DLYN is updated.

K _DLY = P _TE / P _TS (20) 12-4) The end area time P _KED is obtained by the following equation (21), and the average end area time P _KEDN is updated. P _KED = T _E −T _BE (21) It should be noted that the setting of the presence / absence of updating (learning) of the average head time ratio and the average terminal area time is enabled. 13) Finish cutting out.

Using the method of the present invention, light calcium carbonate S-10 powder, which is one of the standard powders according to the APPIE (Japan Powder Industry Technology Association) standard, was quantified at 2 g, 4 g, and 6 g.
As a result of performing the clipping control n = 5 times for each of the four patterns g and 8g, as shown in FIG.
%, Minimum: 0.1%, average: 2.5%.

[0041]

As described above, according to the present invention,
When a fixed amount of powder is cut out by using the powder supply device, feedback control is performed using the powder flow rate sensor, so that a fixed amount of cutout control can be performed with high accuracy and at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a side view partially showing the 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 side view showing another configuration example of the measurement electrode used in the capacitance type flow sensor.

FIG. 5 is a characteristic diagram showing a temporal transition of a cutout flow rate of powder in the present invention.

FIG. 6 is a flow chart of a powder cutting control according to the present invention.

FIG. 7 is a characteristic diagram showing a temporal transition of a cutout flow rate of powder when the method of the present invention is applied to an actual process.

FIG. 8 is a characteristic diagram showing a measurement example according to the method of the present invention.

FIG. 9 is a perspective view showing a conventional example of powder conveyance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stack 2 Powder 3 Powder transport 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 tube 23 Air supply device 31 Hollow pipe 32 Piezoelectric element 33 AC power supply

Claims (7)

[Claims] The powder contained in a 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 dropping naturally through a vertical portion of the powder transporting cylinder. It is measured by a body flow 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 powder is filled into the powder container so as to obtain a predetermined amount. Control method for quantitative cut-out of powder. 2. 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 setting a target cut-out amount of the powder as a fixed amount. A step of instructing the powder supply device to start cutting out the powder, and a step of activating the powder supply device to drop the powder, and calculating a passage amount of the powder in the gradually increasing starting end region. Calculating the passage amount of the powder in the constant flow rate region where a fixed amount of cutting is performed, and predicting the gate-off time by assuming that the passage amount of the gradually decreasing end region is equal to the passage amount in the start end region. Stopping the powder supply device when the gate-off time is reached, and simultaneously predicting the cut-out end time; and, when the cut-out end time is reached, calculating the total amount of the powder passed and terminating the cut-out. 2. The method according to claim 1, further comprising the steps of: 3. The step of calibrating, wherein the gate-off time is fixed to an arbitrary value and powder cutting of the brand is performed;
3. The method according to claim 2, wherein a relationship coefficient for converting the cut-out amount with an electronic balance and converting the cut-out amount into an actual weight is obtained. 4. The method according to claim 2, wherein the prediction of the gate-off time is performed by obtaining a predicted gate-off time and then obtaining a time of an end predicted point, and predicting a gate-off time when the time reaches the end predicted point. Control method for quantitative cutout of powder. 5. The powder flow sensor is provided with a measuring electrode for detecting a flow rate of powder as a change in capacitance and a reference electrode used for correcting environmental conditions provided in parallel. 2. The method according to claim 1, wherein a capacitance type flow sensor is used. 6. The measurement electrode is composed of a pair of curved source electrodes and sense electrodes disposed opposite to the outer periphery of a cylindrical tube serving as a powder flow path, and a guard electrode provided therebetween. Wherein the reference electrode comprises a pair of curved source electrodes, a sense electrode, and a pair of guard electrodes which are arranged to face the outer periphery of the cylindrical tube into which the air is sent. 6. The method for controlling quantitative cutout of powder according to 5. 7. The measurement electrode according to claim 1, wherein the source electrode and the sense electrode are wound around the outer circumference of the cylindrical tube at an angle of 45 ° so as to make a single spiral or an integral multiple thereof. Item 6. The method for controlling quantitative cutout of powder according to Item 6.