JPS59216021A - Weighing machine - Google Patents

Abstract

PURPOSE:To obtain a weighed value accurately through simple operation by calculating pressure applied to a weighing container and subtracting it from the output of a load detector together with the weight of the container. CONSTITUTION:A multiplier multiplies the output of a manometer 56 by -R2/R1 (R2/R1: difference in cross-sectional area between expansion joint 24 for feeding and expansion joing 50 for discharge) to obtain the polarity-inverted total reaction force applied to the sealed weighing container. This value, polarity-inverted weight of the sealed weighing container, and output of the load detector are summed up by an added to obtain the weight of raw material thrown in the sealed weighing container 20 from a raw material tank 42.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a weighing machine, and particularly to a weighing machine that measures the weight of powder, liquid, etc. after putting it into a closed weighing container. A cover like the one shown in the figure. In the figure, 1 is a closed weighing container, 2 is a load detector, and is attached to the closed weighing container 1. 3 and 4 are telescopic joints for input, 5 and 6 are input valves, 7.8 is a tank for raw materials, 9 is a discharge valve, 10 is a telescopic joint for discharge, 11 is a closed container, such as a mixer, and 12 is a pressure equalization pipe. be.

This weighing machine charges raw materials from the raw material tank 7 into the closed weighing container 1 (for example, by opening the input valve 5) and when the output of the load detector 2 reaches a predetermined first set value. When the input valve 5 is closed and the input valve 6 is opened to input another raw material from the raw material tank 8, and the output of the load detector 2 reaches a predetermined second set value, the input valve is closed. 6, open the discharge valve 9, and release 1 airtight container.
This is to transfer two raw materials into the tank.

By the way, when one of the input valves 5 and 6 is opened to input raw materials, the input telescopic joint 3 and
The reaction force of 4 is in the direction of ・The reaction force of the ejection telescopic joint 10 is
The weight is applied in each direction, resulting in a weighing error. Therefore, a pressure equalizing pipe 12 is provided, and the sum of the cross-sectional areas of the input expansion joints 3.4 and the cross-sectional area of the discharge expansion joints 10 are made equal, and each reaction force is canceled out to eliminate the influence of pressure. I was about to do it.

However, it is impossible to make the sum of the cross-sectional areas of the loading expansion joint 3.4 and the cross-sectional areas of the ejection bending and contraction joints completely equal due to mechanical precision, and it is impossible to completely make it equal to the cross-sectional area of the expansion joint 3.4. was difficult to remove.

The purpose of the present invention is to provide a weighing machine that solves the above problems, and for this reason, unlike the conventional weighing machine described above, which is provided with a charging valve 5.6 and a charging telescopic joint 3, 4, at least one A pair of input valves and an expansion joint for input are provided, a pressure gauge is provided on the measuring container, a self-weight setting device in which the weight of the measuring container is set, and a cross-sectional area of the expansion joint for input and the expansion joint for discharge is provided. An area setting device with a difference set is provided, and the pressure applied to the measuring container is calculated by multiplying the setting value of the area setting device and the output of the pressure gauge with a multiplier, and then the pressure applied to the measuring container is calculated from the output of the load detector. This configuration includes an arithmetic unit that subtracts the output of the multiplier and the set value of the area setter.

In this way, the pressure applied to the weighing container is calculated and subtracted from the output of the load detector along with the container's own weight, making it possible to accurately The weight value can be obtained.

Hereinafter, this invention will be explained in detail based on two embodiments shown in FIGS. 2 to 4. A first embodiment is shown in FIGS. 2 and 3. In FIG. 2) 20 is a closed weighing container supported by a load detector 22 such as a load cell. This closed world Rgz.

The upper part of the tank is connected to the atmosphere or to the raw material tank 42X44% 46 via the input telescopic liquid hand 24.26% 28) input valve 30% 32.34 and three-way switching valves 38 and 40.

As is clear from Fig. 2, the input telescopic joints 24 and 26
% 28 and its placement position is different. That is, the dosing telescopic joint 24 is directly connected to the closed weighing container 20, whereas the other dosing telescopic joints 26, 28 are connected to the closed weighing container 20 via the dosing valves 32, 34. 0 48 is a discharge valve, 50 is a discharge expansion joint, 52 is a pressure equalizing pipe, and 54 is a mixer. Since these are constructed in the same way as the conventional one shown in Fig. 1, detailed explanations are omitted. do.

A pressure gauge 56 measures the pressure inside the closed measuring container 20. The output of this pressure gauge 56 is supplied to a multiplier 58 as shown in FIG. This multiplier 58 includes an operational amplifier 60, a resistor 62 with a resistance value R1 connected to this input side, and an on/off switch 6 between the input and output of the operational amplifier 60.
The respective resistance values connected through 4.66.68 are R
2, R3, ■ (consisting of resistors 70, 72, and 74, which are 1. When only the open/close switch 64 is closed) the multiplier of this multiplier 58 is 12/horse, 2/B, 117) value The value of R2%F is selected such that is the difference in cross-sectional area between the loading telescopic joint 24 and the discharging telescopic joint 50. Similarly, when only the open/close switch 66 is closed, the multiplier +;!
'-'3/R, and the values of R3 and R1 are selected so that the value of R3/ is the sum of the cross-sectional areas of the input telescopic joints 24 and 26 minus the cross-sectional area of the discharge telescopic joints 50. Similarly, when only the open/close switch 68 is closed, the multiplier becomes -R4/horse, and the value of horse/R1 is calculated from the sum of the cross-sectional areas of the input telescopic joints 24 and 28, and the cross-sectional area of the discharge telescopic joint 50. R4, R,
The value of is selected.

The output of this multiplier 58 and the output of the load detector 22 are supplied to an adder 76. In addition to this, the adder 76 is also supplied with the self-weight of the closed weighing container 20 set in the self-li setting device 78 with the polarity reversed. The adder 76 is
It consists of an operational amplifier aO, four resistors 82, 84, 86, 88 each having the same resistance value, and an inverter 90.

In the weighing machine configured in this manner, for example, assume that the three-way switching valves 38 and 40 are switched to communicate the closing telescopic joints 26 and 28 to the atmosphere, and only the open/close switch 64 is closed. . In this state, the input valve 30 is opened and the input of raw materials from the raw material tank 42 into the sealed measuring container 20 is started. In this state, the insertion telescopic joint 26
．． Since the pressure inside 28 is atmospheric pressure, the reaction force against these closed measuring containers 20 is zero. Therefore, the downward reaction force of the filling telescopic joint 24 and the upward reaction force of the discharge joint 50 are applied to the closed measuring container 20. Here, the pressure nozzle J in the input expansion joint 24 and the discharge expansion joint 50 are shown.
The pressure inside is equal to the pressure indicated by the pressure gauge 56. Therefore,
In the multiplier 58, the output of the pressure gauge 56 and -E2/horse(R
When z/R is multiplied by the difference in cross-sectional area between the charging expansion joint 24 and the discharge expansion joint 50, the output of the multiplier 58 is the inverted polarity of the total reaction force applied to the closed weighing container 20. is obtained.

When this, the polarity of the self-weight of the closed weighing container is reversed, and the output of the load detector 22 are added by the adder 76, the weight of the raw material being put into the closed weighing container 20 from the 1 raw material tank 42 is calculated by the adder 76. obtained as output. This is because the output of the 1-load detector 22 consists of the algebraic sum of the weight of the raw material, the weight of the closed weighing container 20, and the reaction force applied to the closed weighing container.

When the value of the adder 76 reaches a predetermined first value, the λ official pulp 30 is closed and , +-'-2 '-'
The switch 64 is opened and the open/close switch 66 is closed.

At this time, the three-way switching valve 40 maintains the state in which the closing telescopic joint 28 is communicated with the atmosphere side, and the one-opening/closing match 68 remains in the open state. In this state, the loading telescopic joints 24 and 26 generate a downward reaction force against the closed weighing container 20, and the discharging telescopic joint 50 causes the closed weighing g R? Generates an upward reaction force against aO. Here, the multiplier of the multiplier 58 is changed to 12/R (the sum of the cross-sectional areas of the input telescopic joints 24 and 26 minus the cross-sectional area of the discharge telescopic joint 50), so the above-mentioned Similarly, the weight of the raw material in the closed weighing container 20 is obtained from the adder 76.

When the value of the adder 76 reaches a predetermined second value, the telescopic joint 26 for closing the three-way switching valve 38 communicates with the atmosphere, simultaneously opening the on-off switch 66 and closing the switch 68. At this time, the input pulp 30 remains closed, and the open/close switch 64 remains open. In this state, the charging telescopic joints 24 and 28 produce a downward reaction force, and the discharging telescopic liquid hand 50 produces an upward reaction force in the closed measuring container 2G. Here) the multiplier of the multiplier 58 is −R
3/R, (the sum of the cross-sectional areas of the input expansion joints 24 and 28 minus the cross-sectional area of the discharge expansion joint 50), so the inside of the closed weighing container 20 is changed in the same way as described above. Is the weight of the raw materials added? J! 1i76.

When the value of the adder 76 reaches a predetermined third value, the input valve 34 is closed, the discharge valve 48 is opened, and each raw material is transferred from the closed container 20 into the mixer 54.

In the second embodiment, as shown in FIG. 4, the calculations performed analogously in the first embodiment are digitally performed. 92) 94 is an A/D converter for converting the output of the pressure gauge 561 and the load detector 22 into a digital signal. 96.98.100 is an area setter for providing a multiplier to the multiplier 102. The area setter 96 is set with the difference between the input telescopic joint 24 and the discharge telescopic joint 50, and the area setting device 98 is used to calculate the difference between the discharging telescopic joint 50 from the sum of the cross-sectional areas of the charging telescopic joint 24 and 26. The value obtained by subtracting the cross-sectional area is set, and the same 100 includes the expansion joint 24 for input
- The value is set by subtracting the cross-sectional area of the discharge telescopic joint 50 from the sum of the cross-sectional areas of 28. 104 is a self-weight setting device in which the dead weight of the sealed weighing container is set, and 106 is a subtractor.

This embodiment also operates in the same manner as the first embodiment.

In the above example, there are three raw material tanks 42s 44% 4
Although raw materials were introduced from No. 6 onwards, the number of tanks can be increased or decreased depending on the situation, and the minimum number of tanks may be only one. In that case, either of the input valve and the expansion joint for input may be connected to the closed container 20 side. Also, in the above embodiment, the connection order of the input valve 30 and the input telescopic joint 24 was made different from the connection order of the other input valves 32.34 and the input expansion joint 26.28; The connection order may be unified. Furthermore, for example, the area setter 100 is set to the sum of the areas of the charging telescopic joints 24.26 minus the area of the discharging telescopic joint 50, but the charging and discharging telescopic joints 24.50 are always Since a reaction force is generated, the first
and second and third setting devices that set the areas of the closing telescopic joints 26.28 are provided, and the valves 30.32.
The multiplier 102 combines these according to the opening/closing status of the
may be given to

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a conventional weighing machine, Fig. 2 is a schematic diagram of a first embodiment of a weighing machine according to the present invention, Fig. 3 is a lock diagram of the first embodiment, and Fig. 4 is a schematic diagram of a conventional weighing machine. is a block diagram of the second embodiment. 20... closed measuring instrument, 22... load detector, 24.
26.28... Telescopic joint for insertion, 30.32.34.
°・Input valve, 48... Discharge valve, 50... Discharge expansion joint, 52... Pressure equalization pipe, 56... Pressure gauge,
58.102... Multiplier, 62.70.72.74.
96.98.100・1 area setting 2θ vessel, 76.10
6...Arithmetic unit, 78,104...Self weight setting device. 1 figure, 2 figures

Claims (1)

[Claims] (1) A closed measuring container, a load detector coupled to the sealed measuring container, at least one charging valve and a charging telescopic joint provided in series on the upper part of the sealed container, and the sealed container. a discharge valve provided at the bottom of the discharge valve; a discharge expansion joint that connects the discharge valve to a closed container other than the closed measuring container; and a pressure equalization pipe that communicates the inside of the closed measuring container with the inside of the discharge expansion joint. and a pressure gauge for measuring the pressure inside the sealed measuring container; and an area setting device in which the difference in cross-sectional area between the input expansion joint and the discharge expansion joint is set; 1) A multiplier that multiplies the set value of the area setting device; a dead weight setting device in which the dead weight of the sealed weighing container is set; and 1) the output of the multiplier and the setting value of the dead weight setting device from the output of the cylinder weight detector A weighing machine consisting of a calculation unit that subtracts .