SU1464044A1 - Method and apparatus for controlling discrete batching by weight - Google Patents

Abstract

The method consists in tracking the current value of the weight of the scaled material and reducing the performance of the feeder whenever the difference between the value of a given dose and the current weight is less than the product of the sum of the performance of the feeder and the absolute maximum change of this performance by the lag time. In the device, unit 8 measures the performance, and unit 11 measures the absolute maximum change in performance. The signals from the outputs of these blocks are summed up in the adder 9, and then in block 10 they are multiplied by the delay time and sent to the comparison node 3, in which this signal is compared with the differential signal of the dose value setter 6 and the measuring unit 12. Signal from the comparison node 3 enters the control unit 2, the signal is output to the feeder via a digital-to-analogue converter 1, to which the signal memory block 5 of the block 11 is connected. 2 cf files, 1 slug. about and

Description

The invention relates to weighing technology.

The purpose of the invention is to improve accuracy.

In the proposed method, which consists in tracking the current weight, the feeder’s performance is reduced at times when the inequality θ holds

P - M 4 "}, +) ^ _e ,

where P is the value of a given dose;

M - the value of the current value of 15

weight of the dosed material;

- performance feeder;

ί - number of the reduction cycle;

l'z is the lag time between the moment the signal is output to the feeder to reduce the pro- ductivity and the moment 25 the beginning of the decrease in productivity;

I 40, - the absolute maximum change in performance of the feeder. ¹ 30

Since 0 77 4 0

| yo7 ^ks 1 / o, = ς & 1, _and ί, · ί.

Dosing error in - ~~ t times> _

zeζΐ

less than 0-, ή at 0, · -Ό 4 0 - * О, that

and provides increased accuracy.

The drawing shows a block diagram of a control device for weighing discs for dosing bulk materials.

The device contains a digital-to-analog converter 1, a control block 2, a comparison node 3, a difference calculation node 4, a memory block 5. Unit 6 dose quantities, unit 7 delay time, unit 8 measuring the performance of the feeder, adder 9, unit 10 multiplication, unit 11 ^of_ 5 ₀ measuring the absolute maximum change in the performance of the feeder and measuring unit 12, the input of which is connected to the load cells of the metering unit (not shown) .

The proposed method is as follows.

In the process of controlling the setting device 6, the required dose value P is set. The control unit 2 via digital-to-analog converter 1 turns on the feeder (not shown) for full performance, which is ensured by the zero code on the information inputs of the digital-analog converter 1 due to the lack of a signal from the output of the maximum measuring unit 11 absolute change in the performance of the feeder.

A signal from the output of the sensors, proportional to the current weight value, is measured by block 12. The measurement result M is fed to the input of the feeder’s capacity measurement unit 8, the unit 11 for measuring the maximum absolute change in the feeder’s performance and the second input of the difference calculating unit 4. Block 8 measures the change in величины - Δ M and generates a signal () at its output. Unit 11 measures the change in the magnitude of AND and forms at its output a signal! () ^Ma * ^s | maximum absolute change in the performance of the feeder.

The addition in the adder 9 of the signal from the output of block 11 with the signal of block 3 and the subsequent multiplication of the result of addition by the value ί} forms at the output of block 10 of multiplication the anticipation signal

Υ = (0 + | 4 (G ^ax |) 2 _Oe .

The value is preliminarily determined from experimental data specifically for each type of metering device. This value depends on various parameters of the metering unit: the drop height of the material being metered, the control method of the feeder valve (pneumatic, hydraulic, electric), the method of feeding the material into the bun, etc. but it is constant for each particular type of dispenser.

From the input of the node 4 to the calculation of the difference of the signal of the setting device 6 of the dose P, the signal M of the measuring unit 12 is subtracted, and the result of the calculation is compared in the node 3 of the comparison with the lead value режд. When performing inequality

p - CDM + NrG ^ke 1) ^

node 3 comparison generates at its output a signal to change the mode of operation of the feeder. By this signal

control unit 2 fixes in memory unit 5 the value of the signal of change in the feeder's performance Δ С? ₎ , which corresponds to the signal from the output of block 11.

1 DAC parameters are selected so that the new setpoint value corresponds to performance of the feeder maximum productivity change in absolute value of the feeder for dosing performance O · Δ t ,,. E. _(G} = Δ $,. The value of _<3? Formed on the output of memory block 5. Accounting for the value in the assumption of the end of dosing before the first decrease in the feeder’s performance leads to a dosing error of no more than Λ, | 2 | & (} ^ax I?. Such an error is possible if After the node comparing the signal to stop dispensing by node 3 and before the actual end of dispensing, the feeder capacity will be ((} ±, Др). The "+" sign in inequality guarantees the absence of overshoot in the dispensing process (reload dose).

'Inequality for dosing after the first decrease in feeder capacity and dosing accuracy at the same time

Р - М <(«) ₂ + ί С / Г ^с |

2 1a <).

For the ί th run-down cycle

Δ Ω 7 '

4, - = 2 MO? ⁱⁿ * ^with 1? _uh , considering that the condition is almost always met

rmax u! _h 1 = cond,

and according to the structure of the device ’

dosing error is

those. dosing error is (ς * 1/2) times less than the feeder capacity in the ΐth cycle of its decrease and at С? - * 0, d. 0.

Claim

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1. A method of controlling weight discrete dosing bulk materials under ma ^0, consists in the fact that the set dose value, the current value measured weight dosed material, this value is compared with a predetermined value and for comparing the results of lower feeder performance, Oh. To improve accuracy, the lag time between the moment of signal output to the feeder to reduce performance and the moment of the beginning of performance decrease is preliminarily determined, and when dosing, the maximum absolute change in the performance of the feeder is continuously measured and its performance is slowed down when the difference is values of weight and a given dose value exceeds 25 value, defined as the product of the sum of the feeder capacity and th feeder performance to change the delay time, the productivity is reduced by an amount equal to the maximum absolute change in the feeder performance measured before the feeder decrease productivity.

2. A device for controlling weight discrete dosing, containing a measuring unit, the input of which is connected to the weight measuring ₄ θ sensors, and the output - to the input of the unit. measuring the performance of the feeder, the comparison unit, the output of which is connected to the first input of the control unit, the first output of which is connected to the input unit of the dose rate, the output of which is connected to the first input of the difference calculation unit, the output of which is connected to the first input of the comparison unit, the memory unit, the first input which is connected to the second output of the control unit, and the adder, distinguishing the topics

accuracy of life

unit, measuring the maximum absolute change in the performance of the feeder and digital-to-analog converter, with the output being measured

that, in order to increase, a block of cleverness is entered into it

55

1464044

The main unit is connected to the second input of the computation node and the input of the measurement unit of the maximum absolute change in the performance of the feeder, the output of which is connected to the second input of the memory unit and the first input of the adder, to the second input of which the output of the performance measurement unit of the feeder is connected, and output ₁₀

the first input of the multiplication unit, the second input of which is connected to the output of the lag time controller, and the output to the second input of the comparison node, the inputs of the digital-to-analog converter are connected to the output of the memory block and the second output of the control unit, and the output of the digital-to-analog converter is connected to the feeder.

Claims (2)

Method.Supplies with tracking the current value of the weight of the dosed material and decreasing the performance of the feeder whenever the difference between the value of a given dose and the current weight is less than the product of the sum of the performance the feeder and the absolute maximum change in this performance for the lag time. In the device, block 8 measures the performance, and block 11 measures the absolute maximum change in performance. The signals from the outputs of these blocks are summed in the adder 9, and then in the '10 block they are multiplied by the delay time and sent to the comparison node 3, in which this signal is compared with. the difference signal setting unit 6 dose and the signal of the measuring unit 12. The signal from the comparison unit 3 enters the control unit 2, which issues a signal to the feeder through a digital-to-analog converter 1, to which the block 5 of the signal signal unit 11 is connected. 2 cff-ly , 1 Il. 8 C 1464044 > one 1464044 2