SU1663445A1 - Method of checking conveying weigher - Google Patents

Abstract

The invention relates to weighing technology and allows for an increase in the accuracy of verification by eliminating the effect of any uneven running loads. Record the mass of material passed through the scales, located on the measuring section of the tape, indicated by the marks. To determine the actual value of the mass recorded by the weights, the sample of the material from consecutive sections of the tape is removed and weighed on sample scales, multiply the weight of each sample by a weighting factor equal to the degree of its contribution to the weight indications during the passage of the measuring section through the load receptor, and sum the obtained value. The number of sampling sites and weighting factors are established taking into account the kinematic scheme and transfer function of the load receptor as a dynamic link with delay. 3 il.

Description

The invention relates to weighing technology, in particular to methods for calibrating conveyor scales.

The aim of the invention is to improve the accuracy of verification by eliminating the influence of non-uniformity of running loads.

FIG. 1 shows a block diagram of a method for calibrating conveyor scales with a single-wheel load receptor, perceiving the load of two weight spans (sections) of the belt (tons 2).

The mass of material located on the moving conveyor belt 1 affects the weight sensor 2, the signal from which is fed to the first input of the recording equipment 3. The output of the recording equipment is connected to the input of the integrating converter 5 of the analog signal to the pulse frequency, the output of which is connected to summing counter 6 calibrated in units of mass. The counter 6 is started and stopped by the control unit 7 when passing the first mark MT1 and the second mark MT2 respectively to the sensor 8 marks. To determine the actual running load of the tape, model weights 9 are used. The marks MT1 and MT2 are located on the tape at a distance corresponding to the two weight sections I. The actual traffic flow is approximated by a series of successive pulses of rectangular pulses

about with

4 СП SP

 where V is the speed of the tape.

The amplitude of the pulse AI corresponds to the mating of the instantaneous long-running load qi (t) within each portion of the sample with a mass Mi AI V t,

Sensor 8 tags is located above the first stationary roller, determining the beginning of the load receptor, the second and third sections, in which weighed material is located in the form of square impulses with amplitudes A2, Az and masses M2 Mz AzA / T, affect the weighing device of the scale in the period a time of 2 tons, corresponding to the passage of the marks MT1, MT2 under the sensor 8 marks. Pulses M1, M4, located to the left and right of the pulses M2, M3, affect the weighing device in the time period t. With this, at the output of the weighing device weight, the signal transformed by the transfer function is reproduced due to the total effect on the input of the last four other pulses of different amplitudes (with uneven load) and the same duration m each. Moreover, the time of impact of each pulse on the weighing device of the balance, and, consequently, the degree of influence on the reading of the balance is determined by its location relative to the marks.

Consider the transient playback at the output of the weight sensor of the load-receiving device of the input pulse with amplitude A q 1 and duration t, The area of the pulse multiplied by the speed of the conveyor belt has the physical meaning of the mass of material M SV А Т V lying on the same weight region I. Single pulse action can be represented as the process of applying to the input of a cargo intake weights of two-step effects with opposite amplitudes of amplitudes equal to one, with the second step action of ts to the input of the scales relative to the first with a time delay equal to m.

Fig. 2 shows a flow chart of the playback process at the output of the weighing intake device with the transfer function W (p) of the input single pulse action. At the output of the load receptor sensor, the input right-angled pulse signal is converted, i.e. is stretched in time to the value of 3T, with the corresponding

and

ten

15

shape distortion. The area of the output signal is equal to the area of the input pulse multiplied by the static transfer coefficient of the load receptor K. Calculation of the areas of the output signal over time intervals O, g, t, 2.Ji ЈОо, 5 (/ can be performed as follows.

As is well known, the transfer function of a single-face load receptor for linear load d (p) is:

SS "X (P) (P} .A rvhZh ™ p2t

k (1-2e-rG + e-2rT), (1)

(one

) 2

where k is the static transfer coefficient

s weighing device scales (k -)

20

t -

I v

- constant delay

t maybe

cargo intake scales;

QBX (P) - image of the input function of the linear load qBx (t);

Pout (p) is the image of the output function qebix (t) corresponding to the input function of the linear load q5A- (t).

The image of the input unit pulse action function qex (t), which is two equal amplitude, but opposite in sign, step effects, following each other with a time delay, should be represented as

Yavh (R) (e-rG)

From this expression, it is possible to obtain an image of the output function when the input function W (p) affects the input function qex (p) in the following form:

) dBx (p) W (p) (l-ie-pr) (1-2e-pr + e-2pr)

R

 - (1-3e-pT-f3e-2pT-e-3pr). p hr

Having divided the image of the output of the scale into time intervals of influence on the weighing device of the scale and having carried out the corresponding transformations, we obtain

55

 2t

We divide the time of impact of the pulse to the input of the load receptor into 3 phases (Fig. 3):

1phase - 0, t - the front of the impulse has come from stationary roller support 1 to weight roller support 2;

2 phase - t, 2r J - the leading edge of the impulse passed from the weighing roller 2 to the stationary roller 3 of the intake;

3phase - 2g, Zg - rear front / m of the pulse coming off the load-bearing device seers.

Areas of the output function for all

three phases S, Sa. S; after pichis / p.e: mr composition

kr

r1 KG „1 H,

.

Then the total area of the signal at the output of the load-carrying device when applying to its input a pulse of amplitude A 1,

kg (-) will be

World Cup

 + s3 + s3 -gkr + kr +

+ .r (Ј.c),

and is equal to the area of a rectangular single impulse Su. multiplied by the static transfer coefficient of the weighing intake weights:

.Su, (Ј.c).

Thus, the transfer function of the balance, distorting the shape of the input impulse effect, completely passing through the load receptor, accurately reproduces its integral characteristics, i.e. the area of the output response of the load receptor is directly proportional to the area of the input action.

Multiplying the right and left sides of the last equality by the velocity V and dividing both expressions by k, we can represent the integral characteristics as the ratio of the masses of the input and output pulses.

/. Q. (kg)

When four successive pulses (figure 1) are passed through the scales, a signal equivalent to the total input effect of all four pulses is reproduced at the output of the balance. With the shown location of the marks MT1, MT2 and the sensor 8 marks the pulses M2, MZ with amplitudes A2, A3, which are located on the weight segment from the moment of the start of the counter b to the stop during the time 2t, transmit

m (s)

its weight to the weighing device by

; 3) J m2 (h) +1 m2 (h) | m2 (s)

Pulses Mi, M4 with amplitudes AL A / i,

from the moment of launching the counter 6 to the stop during the time rj, they transfer their mass to the load receiver

Mi (4) -lMi (4).

The pulses located to the right of Mi and to the left of M4 in the direction of movement of the tape will not affect the readings of the balance during the calibration period,

since from the moment of the start of the summing meter 6 until the moment of its stopping, they do not fall on the weighing device. From this it follows that with the kinematic

of the one-wheel weighing device intake and positioning the sensor 8 marks above the stationary roller conveyor, which determines the beginning of the device, the distance between the marks MT1 and MT2 is two weight spans (), and the total number of sampling sites, including two sites nepe / t, the first mark ( ), is S 2m 4 (Mi, M, M3, Ma. Such a Number of samples is the mass

material actually acting on the balance during the calibration period.

The actual weight of the four samples of material acting on the balance is determined by the formula

35

Md M + M + Mz1 + Ml | Mi +

+ | Mg + | M3 + M4.

In the case of use in conveyor scales of a cargo intake with a different kinematic scheme, the number of sampling stations and weights are determined in the same way as in the example, using only the corresponding

transfer function (1).

The method of checking on conveyor scales with a single-roller weighing device is carried out as follows. Preparation for calibration (figure 1). Above the stationary roller conveyor preceding the weight belt, along the belt movement, a sensor of 8 marks is installed, on the conveyor belt there are four identical, consecutive control sections.

length corresponding to the length of the weight section. The beginning of the third section and the end of the fourth section are additionally marked with marks MT1, MT2, on which the sensor of 8 marks should operate (counting of the sections is conducted against the belt stroke).

Scale verification. The conveyor is turned on and the material is loaded with the material with the entire belt, excluding the measuring section. After starting and stopping the summing meter 6, its readings are recorded in the empty measuring section (MXX). After that, the material is loaded with the entire tape, including the measuring section. After starting and stopping the summing counter, his readings are taken. Conveyor stop. Using a trimmer, the material from the four controls is removed.

plots 14. Discharged from each plot

the material is weighed on an exemplary scale 9, multiplied by a weighting factor and the actual mass value determined by the weights is determined by the formula:

Md Mi +1 Ma +1 Mz + 4 M4. oooh

The accuracy of the weights is determined by the formula

(1 (% Y

The verification process is carried out at three points of the range of variation of the linear load of 20-100% of the nominal value.

The implementation of the proposed method of calibration of belt scales provides high accuracy of calibration for any irregularity of linear loads along the length of the belt.

Claims (1)

Claims The method of calibration of conveyor scales, in which labels are applied to the mx tape, bounding the measuring section, loads the tape with material and twice from the measuring section fixed by the tag sensor, first with an unloaded measuring section, and then, with the load, the readings of the weights are taken, which are used to determine the current performance of the conveyor weights, then their actual performance is determined, the samples of the material from the successive and alternating areas of the measuring section are weighed and weighed, and the weights are measured on the current and actual performance of belt scales, characterized in that, in order to improve the accuracy of verification by eliminating the influence of irregularity of linear loads, the mark sensor has above the first stationary support of the load-receiving section of the belt scales, additionally removed and (Weigh sample samples of the material from the tape section before the first mark of the measuring section on the model scales, and the actual performance multiplying the weight of each sample by a weighting factor and a sum of the obtained values, the total number of sampling zones is chosen equal to twice the number of weight spans of the tape, moreover, the values of the weighting coefficients are determined by the transfer function of the load receptor, according to the degree of contribution of each sampling site during the time of passing through each sampling zone under tag sensor. "M v. - I fI & CM I l