SU1606870A1 - Method and apparatus for weighing - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to increase the accuracy of weighing. The weighing method consists in carrying out a primary calibration of the weights with a known weight by magnetoelectric compensation of the torque of the yoke and measuring the compensation current, secondary calibration of the weights with the same weight with the maximum load on the arms of the yoke and weighing itself, while before each compensation of the torque the yoke is put into oscillation mode , measure their period and take it into account when determining the mass of the weighed cargo. The magneto-compensated weighing device contains a compensating coil located in the field of a permanent magnet and mounted on torsion hangers, an unbalance gauge of the rocker arm, connected via a control unit to an analog-to-digital converter. When pressing the buttons "Calibration 1", "Calibration 2", weights are calibrated accordingly with a minimum, maximum load on the rocker. The corresponding compensation currents and self-oscillation periods are measured. When the start button is pressed, the zero potential of the button triggers the one-shot 13. Circuit 14 measures the period of self-oscillations. The mass value of the calibration weight is pre-recorded in the memory. The arithmetic unit calculates the mass difference, which is displayed on the indicator. 2 sec. f-ly, 2 ill.

Description

The invention relates to a measurement technique and can be used to create reference and exemplary mass measurement tools.

The purpose of the invention is to increase the accuracy of weighing.

Figure 1 shows the functional diagram of the scales; FIG. 2 is a temporary diagram that explains their work.

 ..

The proposed method of weighing

based on the compensation of the torque of the rocker arm, created by the weighed load, by loading the pro-. opposite arm of the rocker arm by the counterweight of a known mass, creating a compensating moment by a coil, which bridges the compensation current supporting the beam in a horizontal position, and recalculating the current of the correction in the value of the mass difference between the weighed weight and the counterweight by the formula

m, (1)

IK where I is the compensation current;

M (is the mass of the calibration weight;

compensation compensation balancing calibration weight.

in the formula (), the compensation current balancing the calibration weight (1 h) is automatically determined at each weighing, depending on the load on the beam. To determine; The scale is calibrated twice, once with the minimum loaded rocker, and the other with maximum loaded. At each calibration, besides the values of the current balancing the calibration weight (1 "IK., The period of natural oscillations of the rocker arm (T,;, T) is measured. When weighed from the measured load, again the period of oscillation of the rocker arm T is calculated. (relative to that obtained when calibrating with a minimum load 1,), proportional to the increment of the oscillation period, determine IR from the ratio

 IlSl-IIL (2) t - t

gr

"G i

H Given the expressions () and (2), the mass difference between the weight to be weighed and the counterweight is defined as

mt / P + .LlJli, (3 M I -7t - t

IK, Ik, Tj ;,.

the proportionality of the increment of the calibration current (411 Ik IK) to the increment of the oscillation period i T T - Tk follows from the following 1x considerations.

Compensation current gauge gr for inversely proportional to the magnetic induction in the gap, V

Ikl V-l / B. .(.four)

With small displacements UX (drawdowns of the compensating coil, the change in induction with a high degree of accuracy is determined experimentally

(five)

described by equation

B-1 / (1 + k,

where K, is the coefficient, depending on

magnetic system designs.

The drawdown of a compensating coil suspended on horizontal extensions under the action of gravity by a total load of mass My is determined by the length of the stretch and the characteristics of the stretching springs and at small subsidence

 I)

AH -V jMg- (6)

the period of free oscillations of the rocker arm T is determined by

 . (7)

From expressions (4) - (7) it follows that

I. + K, T),

(eight)

k, g where K - coefficient of proportion.

Accordingly, at the minimum maximum load;

IK, - (i + KjT,),

k, h

(1 +).

The proposed weighing method is carried out by magnetoelectric compensated beam weights (FIG. 1) containing a compensating coil 1 located in the field of a constant magnet 2 and mounted on the worsion suspensions 3 with which the rocker 4 is rigidly connected with the suspensions for the measured weight and counterweight . Torsion hangers 3 are stretched by springs 5, usually made in the form of rigid plates. The balance also contains an imbalance sensor 6 of the yokes, a control unit 7 consisting of an amplifier 8, an integrator 9, a differentiation circuit 10, a key 11 and an adder 12, a single vibrator 13, a period measurement circuit 14, an ADC 15, an arithmetic unit 16, five memory devices 17-21., Display unit 22 and three formers 23,24 and 25 pulses. Separate memory cells of a single storage device can be used as storage devices 17-21. Pulse shapers 23–25 can be made in the form of buttons controlled by an operator, one of the ends of which is connected to a constant potential, for example, zero.

The unbalance sensor 6 is connected through a control unit 7 to a compensating coil 1 and an input of the ADC 15, the output of which is connected to the inputs of the storage devices 19, 20 and the first input of the arithmetic unit 16. The control input of the period measurement circuit 14 is connected to the one-vibrator output 13 and the input switching unit of control 7, information input - to code of block 7

control, and the output - to the inputs of memory devices 17, 18 and the second input of the arithmetic device 16-.

leveling and operator command

The start-up begins the weighing process, similar to the process with the first kaOstalnye inputs of the device 16 psklyu-, calibration. By pressing the operators, the buttons to the corresponding memory outputs Calibration 2 (driver 24) of the receiving devices 17–21 and the output to, to the third and fourth memory unit of the display unit 22 are pressed. Locking inputs, 20, 18 are recorded according to the devices 17 and 19 are connected with the output period of self-oscillations with a maximum of 23 pulses at the driver, and the input-Yu load on the crutch (Tf), records of devices 18 and 20 - out ...

home of the driver 24. The inputs of the amplifier 8, the integrator 9 and the differentiation circuit 10 are connected in parallel and are the input of the control unit 7, 15 vp: the amplifiers of the amplifier 8 and the integrator 9 are connected directly, and the output of the differentiation circuit 10 through the key 11 is connected to the corresponding inputs of the adder 12, the output of which is the output of control blog 7. The control input of the key 11 is the switching input of the control unit 7.

The proposed method is carried out as follows, 25

Initially scales; calibrated twice. During the first calibration, the cups are released from the load (the load on the yoke is minimal), then for one

and compensation current balancing a calibration weight (1 |). After these two calibrations, the scale is ready for weighing an unknown load. Dp of this weights are placed on one of the cups, and on the other a counterweight is selected, at which time the mass of the weight in the weighing weight and the counterweight does not exceed the range of automatic balancing. At the operator's command, the start-up begins the weighing process, as a result of which the output of the devices 15 and 14 forms the value of the current compensating for the difference between the weights of the weighed load and the counterweight (I) and the oscillation period of the rocker arm at a given load (T). In the arithmetic unit 16, taking into account the values stored

of the cups, an attestation of 30 is preset in the memory devices 17-21,

calibrated weight, the weight of which does not exceed the range of automatic balancing. The value of the mass of the calibration weight is pre-recorded in the memory 21. By the operator's command, the Start starts the process of weighing the calibration weight. The start button is usually associated with a arresting device that releases the mechanical fastening of the rocker arm. In the process of weighing, at the output of the A / D converter 15 a digital value of the compensation current balances the calibration weight when the load is minimal (the output of the period measurement circuit 14 is the self-oscillation period of the rocker arm (T). The first calibration process is completed by pressing the Calibrator 1 button (shaper 23 pulses).

the formula calculates the mass difference, which is displayed on the indicator 22.

The work of the scales in the process of weighing, which is the same as with caliber 40

IK is the value T and

with respectively in the first and second

storage devices 17 and 19.

In the second calibration, the scales are loaded with two identical weights, corresponding to the maximum load on the rocker (the maximum weighing limit is -NVW), then on. One of the cups is set for calibration, as in the measurement, is as follows.

When the operator presses the Start button (driver 25), the negative edge of the signal U (Fig. 2a) starts the one-shot 13 and through the delay time t (at its output generates a pulse with duration T (Fig. 2b). 45 Until t the balance is in the T abilization mode (key P is closed), and the rocker arm is kept in a horizontal position.

The operation of the scale in the stabilization mode is as follows.

When the rocker arm deviates from the horizontal position, the signal Up of the non-zero signal appears at the output of the unbalance sensor 6 (Fig. 2b). Unit 7 55.control converts the Up signal to the Tushki Un. Compensating control signal, which ensures the return of the rocker arms to the initial position. Block 7 provides a proportional gir and at the command of the operator

The start-up starts the weighing process similar to the one for the first calibration. By pressing the Calibration 2 button (shaper 24) to the operators in the third and fourth storage devices, 20, 18, respectively, the period of self-oscillations is recorded at the maximum load on the yoke (Tf),

librovka. By pressing the Calibration 2 button (shaper 24) to the operators in the third and fourth storage devices, 20, 18, respectively, the period of self-oscillations is recorded with a maximum load on the yoke (Tf),

and compensation current balancing a calibration weight (1 |). After these two calibrations, the scale is ready for weighing an unknown load. Dp of this is placed on one of the cups of the weighed cargo, and on the other a counterweight is selected, in which the difference of the masses in the weight and the counterweight does not exceed the range of automatic balancing. At the operator's command, the start-up begins the weighing process, as a result of which the output of the devices 15 and 14 forms the value of the current compensating for the difference between the weights of the weighed load and the counterweight (I) and the oscillation period of the rocker arm at a given load (T). In the arithmetic unit 16, taking into account the values stored

in the storage devices 17-21,

in the storage devices 17-21,

the formula calculates the mass difference, which is displayed on the indicator 22.

The operation of the scales in the process of weighing, which is the same as when calibrating

both in measurement and in the following.

When the operator presses the Start button (driver 25), the negative edge of the signal U (Fig. 2a) starts the one-shot 13 and through the delay time t (at its output it forms a pulse with duration T (Fig. 2b). 5 t the balance is in the T abilization mode (key P is closed), and the rocker arm is kept in a horizontal position.

The operation of the scale in the stabilization mode is as follows.

When the rocker arm deviates from the horizontal position, the signal Up of the non-zero signal appears at the output of the unbalance sensor 6 (Fig. 2b). The control unit 7 5. converts the Up signal into a Tushki Un. Compensating control signal, which ensures the return of the rocker arms to the initial position. Block 7 provides a proportional-integral-differentiating control. For this, the signal UM is fed to the inputs of the amplifier 8, the integrator 9 and the circuit 10 differential 4) differentiation from NIN, the output signals of which are components of the control signal. The signal component of amplifier 8 (UK, FIG. 2d), proportional to the deflection angle of the beam, provides negative feedback to the balance arm stabilizer system. The signal component of the integrator 9 (i152, FIG. 2d) is proportional to the integral of the deflection angle, and serves to eliminate static error J5, the signal component of the circuit, 10 differentiation (Ui, Fig. 2e), is proportional to the orthogonality of the changes; Ensure that the angle of rotation of the balancer is ensured. From the electronic damping, the 20 necessary dd attenuation of the system. A second control signal (U L, Fig. 2g) sets the rocker in the horizontal position. At time t, the pulse from the output of the one-shot 25 (Fig. 26) arrives at the key 10, opening it. In this case, the electronic damping component is excluded from the control signal and, for the duration of the action of the one-shot 13 (Tq) pulse, the balance system goes into the auto-oscillatory mode. Simultaneous pulse of one-shot 13 14 measurement periodically connects the circuit

and the oscillation that measures the period 35

40

self-oscillation system. At the end of the pulse (time t, the system returns to stabilization mode (key 11 closes), and the beam is stabilized in a horizontal position.

Note that the weighing operations of the calibration weight are necessary only when calibrating the balance, which is done only when adjusting the balance after manufacture or repair, since the storage time for information in the storage devices 17-21 is unlimited.

When using the proposed method, the weighing accuracy is increased by 2–5 times while simultaneously increasing the range of measured mass values and reducing the requirements for uniformity of the field in the permanent magnet system, which ensures a precise correction-weighting error due to the inhomogeneity of the magnetic field magnetoelectric & compensation of the measured mass and sagging of the coil of fflancation.

50

45

Formula of invention

1. A weighing method based on calibrating a balance by loading one of. their arms are a calibration weight followed by magnetoelectric compensation of the torque of the rocker arm and the measurement of the current. compensation, loading of the arms of the yokes with a weighed weight and counterweight, magnetoelectric compensation of the resulting torque and conversion of the compensation current into the value of the mass of the weighed cargo, characterized in that, in order to improve the accuracy, after the initial calibration of the weights, the load on the shoulders of the rocker arm, while before each compensation of the torque moment the rocker is put into oscillation mode, their period is measured, and the difference M of masses is weighed. of the load and the counterweight is determined from the expression

five

0

five

0

M M,

HO

Ji i

..

X,

T - T

Where

M 1, T

Iv, 1K (

I

J-K, J-K, 7

calibration weight; the value of the compensation current and the oscillation period of the rocker when it is loaded with a weighed weight and counterweight;

the value of the compensation current and the oscillation period of the rocker arms during the initial calibration; compensation current values. and the oscillation period of the rocker arm during the secondary calibration with the maximum load on the arm,

2. A weighing device with 5 magnetoelectric compensation,

containing a compensating coil located in the field of a permanent magnet and mounted on torsion pendants, with which is fixed a fixed wagon with pendants for measurable, crunch and counterweight, an imbalance of the rocker arm, connected through the unit, control to the compensating coil , a scarlet-digital converter, through which the compensating coil is connected with the first input of the arithmetic unit, the output of which is connected to the display unit, ----- so that

different with the purpose of raising

t

Claims (2)

Claim 1. Weighing method, based on the calibration of the balance by loading one of. the arms of the rocker arm with a calibration weight followed by magnetoelectric compensation of the rocker arm torque and measuring the compensation current, loading the arm arms with the weighed weight and counterweight, magnetoelectric compensation of the resulting torque and converting the compensation current into the weight value of the weighted load, which means that in order to increase accuracy, after the initial calibration of the balance, the calibration process is carried out a second time with the maximum load on the arms of the rocker arm, while each compensation. By means of torque, the beam is introduced into the oscillation mode, their period is measured, and the mass difference M of the weighed load and the counterweight is determined from the expression t 'T gr - PR'> -k, J-Ka. J-Ki calibration weight; values of the compensation current and the period of oscillation of the beam when it is loaded with a weighed load and a counterweight; values of compensation current and period of rocker arm oscillations during initial calibration; compensation current values · and the period of oscillation of the rocker arm during secondary calibration with a maximum load on the rocker arm. 2, Weighing device with 45 magnetoelectric compensation, containing a compensating coil located in the field of a permanent magnet and mounted on torsion suspensions; kakh, with which the beam is rigidly connected with the suspensions for the measured. , weight and counterweight, rocker balance imbalance sensor connected through the control unit to the compensating coil, an analog-to-digital converter through which the compensating coil is connected to the first input of the arithmetic device, the output of which is connected to the display unit, distinguishing-. The reason is that, in order to increase the accuracy of ⁹ 16068, it is equipped with a single vibrator, a period measuring circuit, five memory devices and three pulse shapers, while the outputs of the pulse shapers are connected. second storage devices, recording inputs of the third and fourth storage devices, the output of a single vibrator is connected to the control input of the period measurement circuit, the measuring input of which is connected to the output of the control unit. output, and with the inputs of the first and third storage devices and the second input of the arithmetic device, the output of the analog-to-digital conversion 70 ^{10 of the} developer is connected to the inputs of the second and fourth storage devices, the outputs of all storage devices are connected to the corresponding other inputs of the arithmetic device, the control unit includes an adder, the inputs of which are connected respectively to the outputs of the amplifier, integrator. and through the key, with the output of the differentiation circuit, while the parallel-connected inputs of the amplifier, integrator, and differentiation circuit are connected to the output of the rocker unbalance sensor, the control input of the key is connected to the output of the single-vibrator, and the output of the adder to the compensating coil.