JPH03223627A - Fluid measuring method - Google Patents

Abstract

PURPOSE:To improve accuracy by actually measuring the amount of a head during measurement, and correcting the amount of the head. CONSTITUTION:When an apparatus is started, a screw feeder 20 performs feeding at a large-quantity feeding up to a switching quantity in the vicinity of a target quantity. Then the feeding is switched into small-quantity feeding. At the switching time point, the feeding in 50 - 95% of the target quantity is selected. The small-feeding quantity is selected at 1/2 - 1/20 of the large-feeding quantity. When the measured value reaches a head-measuring quantity by the small-quantity feeding, the feeder 20 is stopped, and a timer is started. The feeding is stopped during a specified time sufficient for the complete fall of head quantity. Thus the head quantity is measured. The same minute quantity of feeding is supplied into a container 30 again. The head quantity is operated and subtracted from the target value. Thus the finishing value is obtained. When the measured value of a platform scale 40 reaches the finishing value, the feeding is finished. A control part 100 starts the timer at the same time. When the difference between the measured value after a specified time sufficient for the complete fall of the head from the finish and the target value is within a control width, the completion of measurement is judged. Thus, the accurate measurement can be realized with a simple system.

Description

Detailed Description of the Invention [Field of Application 1] The present invention relates to a fluid measuring method in which a fluid such as powder or liquid is charged into a measuring tank from an input port at a predetermined height and measured, and particularly relates to a method for measuring a fluid with high precision. This invention relates to a method for measuring fluid suitable for fields where it is necessary.

[Prior art] Powder, i'? When measuring fluids such as H4 using a measuring tank, a part of the supply fluid in the supply path from the stop valve to the input port and the supply fluid in the air from the input port to the measuring tank are finally measured at the end of charging. Since it is poured into the tank, this amount, ie, the amount of head, has a large effect on measurement accuracy.

On the other hand, Japanese Patent Application Laid-Open No. 1-263524 discloses that the input flow rate of the supply fluid is measured in advance by Test 1, and the head weight is calculated as the product of the falling time and the input flow rate and corrected. How have you been employed?

This method is excellent in terms of head correction, but
In practice, there are the following problems.

In other words, it is necessary to measure the falling time by testing the fluid side, and whenever there is repair or change of piping, etc., it is necessary to measure the falling time by the test.
There are problems in that preparatory work before measurement requires a lot of manpower and time, and that changes over time due to foreign matter adhering to the fluid supply path cannot be corrected, resulting in large errors.

[Object of the Invention] The present invention was made in view of the above-mentioned problems, and therefore aims at a highly accurate fluid measuring method that does not require any preparatory work and is capable of correcting changes over time in the amount of head.

[Structure and operation of the invention] The above object is achieved by the present invention as described below. That is,
The present invention is a fluid measuring method in which fluid is continuously supplied to a measuring container from an input port at a predetermined height, and a predetermined target amount is measured based on the weight of the fluid. The method of measuring fluid is characterized in that the target amount is corrected by the head amount to determine the end amount, and the supply of fluid is ended when the measured value reaches the end amount.

Here, the head amount is the amount of fluid that falls into the measuring container after the supply of driftwood is stopped, and specifically, for example, a part of the fluid in the supply path from the fluid stop valve to the inlet or the conveyance path. It is the sum of the fluid injected due to the inertia of , and the fluid in the air from the inlet to the measuring container. Furthermore, after the supply is stopped,
Changes caused by switching from a dynamic load to a static load, or simply shaking of the measuring container, can cause errors, and the six or more fluids included in the head amount can be supplied continuously, such as powder, granules, two liquids, etc. Not particularly limited.

As mentioned above, in the present invention, the amount of head is actually measured and corrected during measurement, so there is no need for any preparatory work as in the prior art, and changes over time due to foreign matter deposited in the supply channel etc. 6. Implementation C, which can be reliably corrected and highly reproducible and highly accurate, can be fully automated using a simple microcomputer and can be realized at low cost.

In addition, in the present invention described above, it is preferable to measure the head amount during measurement using the same supply flow rate as at the end of measurement, since this improves accuracy and reproducibility and eliminates the need for conversion. Although the time GJ will be longer, if the supply amount during a predetermined time period before the end of measurement is set to a small flow rate smaller than the previous flow rate and the head amount is measured and corrected, further accuracy and reproducibility can be achieved. Improvement can be obtained.

Hereinafter, the details of the present invention will be explained based on an example in which the present invention is applied to the measurement of powder and granular materials. Fig. 1 is an explanatory diagram showing the overall configuration of the example. FIG. 2 is a flow chart diagram showing the control configuration of the embodiment;
FIG. 3 is a graph of the metering pattern of this example.

As shown in the figure, the main body of the measuring device of this example includes a storage tank 10
A transportable weighing container 30 is placed on a platform scale 40 embedded in the floor F of the weighing means. It is designed so that it can be metered in predetermined target amounts.

Here, the content of the storage tank 10 can be controlled by a load cell 12. Note that the powder to be measured is replenished into the storage tank 10 from a raw material bag 60 via a powder supply device 50 for gas transportation, similar to the known system.

The screw feeder 20 can control the amount of feed by controlling the rotation speed of its drive motor 21.The scale 40 has a data transmission function that can exchange data such as weighing value data and operation commands. Something,
In this example, a commercially available embedded high-precision platform scale (manufactured by Shimadzu Corporation) was used.

The main body section is controlled by a control section 100. The control unit 100 is a central processing bag! (CPU) 110, a memory 120 for storing data and programs,
A first I10 boat 130 consisting of a load cell amplifier etc. that collects data from the load cell 120 in the main body, and a second I10 boat 140 consisting of a control unit etc. that controls the rotation speed of the drive motor 21 of the screw feeder 20.
, a third 110 boat 150 consisting of an operation unit etc. that starts and stops the powder transport device 50, and a fourth r10 consisting of an R3232C that exchanges data with the platform scale 40.
An operation panel 1 consisting of buttons 1 to 160, pushbutton switches for supporting necessary operations, a keyboard for inputting data, etc.
70, a display panel such as a liquid crystal panel for displaying necessary data, and output display means 180 such as a printer, the river in FIG. 0 is a common data bus. The control unit 100 is programmed to perform the following metering operations. The weighing operation will be explained below with reference to FIG. 2 together with the weighing hand Ill.

First, the measuring container 30 is set on the platform scale 40, the target amount and "under management" are inputted from the keyboard (not shown) of the operation panel 170, and the start button (not shown) of the operation panel 170 is turned on. Then, the tare button (not shown)
The lamp flashes. Check the set state of the weighing container 30, and if it is good, turn on the tare button. Then, the control unit 100 turns on the tare button and performs taring, and also displays the data necessary for weighing, such as the measured value and the amount stored in the storage tank 10, on the display panel of the output display means 180 during the target amount management. , the lamp of the start button (not shown) blinks. Check the displayed content, and if it is normal, turn on the start button. Then, the start button lights up and the screw feeder 20 is started. The screw feeder 20 supplies powder and granular material according to the metering pattern shown in FIG. That is, large supply is provided until a switching amount close to a preset target amount, and thereafter the supply is switched to non-supply. Specifically, the closer the switching amount is to the target amount at the time of switching to small supply, the shorter the metering time can be. Furthermore, the smaller the supply amount of the small supply, the better the accuracy and reproducibility of measurement.

The switching point, the switching amount, and the selection of each supply amount should be made to ensure that the supply amount per unit time is sufficiently stable based on the required measurement accuracy, reproducibility, the supply means used, the shape of the measuring container, and the consistency with the process before and after 1. Generally, the determination is made so that the head measurement can be carried out at the same time. Normally, the switching point is about 50 to 95% of the target amount, and the small supply amount is 1/2 to 1/2 of the large supply amount.
/Selected 20th place. In this example, each supply amount and switching amount are set as necessary using keyboard 1< on the operation panel 170.

When the measured value reaches a head difference measurement amount that is a certain amount smaller than the target amount during small supply, the screw feeder is stopped and timer T1 is started to stop the supply until the head difference has completely fallen. Measure the head after stopping for a certain period of time sufficient for

This amount of head is the memorized weighing (a) of the platform scale at the end of the stop.
It is obtained by subtracting the measured value M at the time of the start of stopping from M2. Note that instead of stopping for a certain period of time, it may be possible to detect that there is no increase or decrease in the measured value, that is, that it has stabilized.This has the effect of shortening the measuring time.

Next, the screw feeder 20 supplies the powder to the measuring container 30 again at the same minute supply amount. At the same time, the head amount is calculated and subtracted from the target amount to obtain the end amount, and this is compared with the measured value from the platform scale 40. When the measured value reaches the end amount, the screw feeder 20 is stopped and the supply ends. . At the same time, the control unit 100 starts the timer T2, reads the measured value after a certain period of time sufficient for the head to completely fall from the end, and stores it as M3, similar to the head measurement.
The difference from the target amount is determined, and if the difference is within the managed amount, the lamp of the completion button (not shown) on the operation panel 170 is blinked to indicate that the measurement is complete. When you press the completion button, the final weighing value is 1.
Data necessary for management, such as target amount, error, management status, measurement date and time, etc., are stored in the memory and simultaneously printed by the printer of the output display means 180, reset to the initial state, and measurement is completed. The weighing container 30 is then conveyed to the next process, and the next weighing container 30 is set. In addition, when the final weighing value M3 is out of control, the output display means 180 displays a weighing error with a lamp and a buzzer, so after resetting the error, check the display panel and correct it as obtained.
After completing the correction, turn on the correction button on the operation panel 110.

This results in normal processing.

The data obtained by measuring the lactose powder using the above configuration is shown below.
Weighing target amount 1350 including tare weight as 00.7 minutes
kg, the switching point from large supply to small supply is set as the point when 1 kg is less than the target amount, and as a result of weighing, the accuracy is ±40.
gr, standard deviation of 10.3 gr, results with very high accuracy and good reproducibility were obtained. The amount of head difference was measured by stopping for several seconds when the amount was 500gr below the target amount.Although the present invention has been described based on examples, it is to be understood that the present invention is not limited to such examples. This is clear from the purpose of the invention.

As described above, in the present invention, the head is corrected by stopping the supply once during measurement to actually measure the head, and then stopping the supply at the end amount that corrects the target amount by the amount of head. There is no need for preparatory work as in the conventional example, and excellent effects can be obtained in that highly accurate measurement can be achieved with a simple system. Furthermore, even if the measurement target is changed, it can be handled simply by changing the necessary operating conditions, and it can be widely applied to fluid measurement in various fields.

[Brief explanation of drawings]

FIG. 1 is an illustration of the overall configuration of the embodiment. FIG. 2 is an operation flowchart of the control section of the embodiment, and FIG. 3 is a graph of the measurement pattern of the embodiment. 10: Storage tank 20 Niscrew feeder 30: Weighing container 40: Platform scale 100: Control unit diagram time

Claims (1)

[Claims] 1. In a fluid measuring method in which fluid is continuously supplied from an inlet at a predetermined height to a measuring container and a predetermined target amount is measured based on its weight, the supply is temporarily stopped during measurement. A method for measuring fluid, characterized in that a head amount is measured, a target amount is corrected by the head amount to obtain an end amount, and supply is ended when the measured value reaches the end amount. 2. The fluid measuring method according to claim 1, wherein the head amount is measured at the same supply amount as at the end of the supply. 3. The fluid measuring method according to claim 2, wherein the supply amount during a predetermined time period before the end of measurement is set to a constant flow rate smaller than the previous supply amount, and the head amount is measured during this period.