SU956786A1 - Ultrasonic sensor of mining machine capacity - Google Patents

Description

The invention relates to the automation of mining and construction work and can be used both to control the volumetric productivity of mining and construction machines having short scraper-chain overload conveyors, and in systems for automatically and automatically controlling their mode of operation.

Electron-tensometric conveyor scales are known in which the measurement of the mass of the material on the tape is carried out by two load-bearing elements on which bridges made of strain gauges are glued. The load cells are connected to the roller by the weight of the monitored material by means of two tg. this mass causes an imbalance of the bridges, and then the imbalance signal is amplified and fed to the indicator l.

The known device has the following disadvantages. Measurement of performance, provides for the mandatory presence of a moving element on the conveyor in a vertical plane, namely, the quality of the conveyor link on the roller conveyors, which

can be constructively ensured only on belt conveyors. Scraper short conveyors of mining machines with a hard chute, this construction is unacceptable. This is due to the fact that the principle of movement of cargo on the scraper conveyor is by dragging, and on the belt conveyor - by transfer. The resistance strain gages under conditions of significant vibration and

The 10 variable loads drawn by the scraper conveyors are not working reliably, the balanced measuring strain gauge needs to be constantly balanced. Therefore, the use of a known host on a mining machine leads to a decrease in the course of operation of its accuracy and reliability in measuring performance. For downhole mining machines the prevailing indicator

20 performance estimates are volume, not weight of cargo. This is due to the fact that the transport vessels of the mountain complex (trolley) are normalized in terms of volume, which

25 points of view is in good agreement with the volume of work performed by the mining machine for a specified period of time, in general, due to the indicated drawbacks of the known device, it will take

It cannot be used as a performance sensor on a scraper conveyor of a torquing machine because of its limited field of use and low measurement accuracy. . These drawbacks are partially eliminated in another known device for controlling the volumetric productivity of a rotary excavator, which contains a single vibrator, five electric switches, a delay element and a sequential master oscillator, a second one vibrator, a waiting excitation generator, transceiver. the converter, the amplifier-forma- tor, and the first trigger. The known device also includes a smoothing fixture, an integrator device and an integrator counter. In the known device, the voltage at the output of the smoothing clamp is proportional to the cross-section of the cargo flow, and its integral (with TV TV tape soon) is proportional to the volume extraction of the rotor excavator 2. A disadvantage of the known device is its great complexity associated on the one hand with the use of many measurement channels, and on the other hand with the need to sum the signals from different channels with. different weights 1 corresponding to the shape of the conveyor belt). The second disadvantage of the known device is. the impossibility of using it {without additional devices) to measure the productivity of a mining machine on its scraper conveyor for any integer number of strokes of the conveyor and to generate an appropriate control signal. . . The purpose of the invention is to simplify and extend the functionality of the doctor, which makes it possible to reduce its cost, increase reliability, and use it to measure the performance of the mountain farm on the scraper conveyor for any integer number of strokes of the conveyor and to generate the corresponding control signal. . This goal is achieved by the fact that the ultrasonic sensor of the productivity of the mining machine is equipped with four AND circuits, a second trigger, two integrators, two memory cells, a clock counter, a non-inertia link and a NOT circuit, .. connected to the first inputs of the first and second circuits AND, the third inputs of which are connected to the output of the first one-vibrator, and the input of this one-foil, combined with the second input of the first trigger, are connected via a delay element to the output of the second one of the new vibrator, also connected to the ne input Ami of the third and fourth circuits And, and the second inputs of the first and third, second and fourth circuits And soe dineny respectively with the first and. the second outputs of the second trigger connected by its input to the output of the second one-oscillator, the first and second inputs of the third electronic key are connected respectively to the outputs of the first and second circuits And through the first and second integrators, each of which is shunted by the same Electronic keys, and the control inputs of these keys are connected respectively to the outputs of the third and fourth circuits And, while the output of the third electronic key of the connection with the input of the fourth electronic key, the output of the first trigger is connected to course of the NOT circuit, the same name outputs and inputs of the fourth and fifth electronic switches are interconnected via a memory cell of the same name, between outputs. the sensor stroke and the output of the fifth electronic key include an inertia-free link, and the control inputs of the fourth and fifth electronic keys are connected to the outputs of the master oscillator via the clock counter, and the control input of the third electronic key is connected to the second output of the second trigger. Fig. 1 is a block diagram of the sensor; Fig. 2 is a process diagram of a process for measuring the performance of a mining machine and the placement of equipment thereon; Figures 3 and 4 are diagrams of signals at the outputs of sensor units} on F1IG, 5 results of evaluating the accuracy of measuring the volumetric productivity of a mining machine as a function of the number of measurement cycles and the properties of the material being submerged. The optimum number of sensor operation cycles in terms of maximum relative integral measurement accuracy of a performance sensor is determined in accordance with FIG. The sensor (figure 1) consists of the following functional blocks. The master oscillator 1, the second one-oscillator 2, the standby oscillator 3, the receiving-emitting transducer 4, the amplifier, the driver 5, the first trigger b through the first input and the circuit NOT 7 form a series circuit of the electro-acoustic impulse signal. The second input of the first trigger 6 and the input of the first one-shot 8 are connected via delay element 9 to the OUTPUT of the second one-shot 2. First 10 and second 11 circuits And, first 12 and second 13 integrators, first 14 and second 15 electronic, third third and fourth 17 circuits And they form two parallel channels for transforming discrete-time information about the height of the load οf into a continuous signal. In these channels, the first inputs of the circuits And 10 and. 11 are connected to the output of the circuit NOT 7, the third; inputs of the same circuits and

connected to the output of the first one-shot 8, the second inputs of the circuits And 10, 11 and 17 are connected respectively to the first and second outputs of the second trigger 18, the input of which is also connected to the output of the first one-shot 8, and the first inputs of the circuits 16 and 17 are connected to the output of the second one-shot 2, The outputs of the circuits AND 10 and 11 are connected respectively via integrators 12 and 13 to the first and second inputs of the third electronic switch 19, and the inputs of the circuits (And 16 and 17 are connected to the control inputs of electronic switches 14 and 15, each of which bypasses the integrator channel output The third electronic key 19 is connected to the fourth electronic key 20 input. The same outputs and inputs of the fourth 20 and fifth 21 electronic keys are interconnected via the first 22 and second 23 memory cells of the same name Between the sensor output and the fifth electronic key 21 output Included is a disinertial link 24 into which a constant value has been introduced, which characterizes the construction of the mining machine conveyor, the property of the location method for measuring the distance and the scale for converting the volume of cargo to be passed through the conveyor belt. the optimal number of measurement cycles received in practice in the mining performance measurement unit, namely, in m. The control input of the third electronic key 19 is connected to the second input of the second trigger 18, and the control inputs of the fourth 20 and fifth 21 electronic keys are connected through a clock counter 25 to the output of the master oscillator 1.

The electronic keys 14 and 15 are closing, 19-21 are switching, the clock counter 25 is trigger and its counting volume corresponds to the optimal number of measurement cycles. The second one-shot 2 generates a time t for steady excitation of piezoceramic receiving-emitting converter 4, the delay of the pulse signal The trji delay elements 9 are equal to the gating time of the received pulse signal by the amplifier-shaper 5, the dwell time fj of the second one-shot 8 is proportional to the double distance H const from the installation point -radiating converter 4 to the chute of the conveyor 26 of the mining machine, h is the locatable distance, moreover, H hvp + h. The speed of movement of the cargo is V const, since the conveyor, which passes all the productivity of the mining machine, is unregulated. 27 cargo on the conveyor of the mining machine. Structurally, the trigger 6 is made with separate inputs, and the second trigger, Ger 18 - with a counting input.

The hearth machine (for example, a loading type 2PNB-2 with scoops 28 (FIG. 2) transfers the load 27 to the conveyor 26. The capacity sensor block 29 is fixed at a height H relative to the conveyor chute by four fastening posts 30, and electrically connected to the operating mode controller 31 of the mining machine with shielded cable 32. The sensor's installation site is selected in the tail section of the scraper conveyor, since the load at this location is distributed uniformly across the width of chute B and height hpp, and the probability of breakdown of the sensor unit 29 at this location According to us, the mining machine operation is low.

In FIGS. 3 and 4, they are indicated by: digits of the signal diagram at the outputs of the corresponding / corresponding sensor units; T is the period of one-cycle measurement of jt, 12, e

0 certain time parameters, t g time of passage of an ultrasonic wave by a distance of 2h and is proportional to this distance, 05 time proportional to the desired distance

5 2ррр, - the magnitudes of the signal amplitudes, proportional to the corresponding longitudinal double cross-section of the load for one period (cycle) of measurement T, for the optimum number of measurement cycles n.

0 and machine performance.

Sensor. Works as follows.

The performance measurement is based on the echo-location principle of measuring the height of the load hj.p on the mining machine conveyor and then converting it into a load volume moving at a constant speed (Vr, - const) along a chute with a constant width (B const) one measurement cycle, the period of which is also constant (T const) with subsequent accumulation of the result for the optimal number of measurement cycles in the sense of minimum relative measurement error

5 and with the subsequent reduction of the latter to an estimate proportional to the productivity of the mining machine in the accepted units of measurement ().

The master oscillator 1 generates a sequence of rectangular ones.

0 pulses with a period T equal to one cycle of measuring the performance of a mining machine in terms of the load volume 27 passing through the conveyor 26. The leading fronts of this sequence

5 square pulses are started by a tick counter 25, providing the optimal number of measurement cycles by counting, and the first one-oscillator 2. The latter generates a modulating pulse, which includes a standby generator 3 for a period of time T / (at the first inputs of the AND 16 and 17. A single signal is present. From the leading edge of the modulating pulse, it also triggers

delay element 9. Standby generator 3 excites the receiving and radiating pre-. the former 4, and the ultrasonic wave is sent to the surface of the load 27. Simultaneously with the beginning of the transmission of the ultrasonic wave, an electrical signal, taken from the transceiver-emitter 4, is fed to the input

amplifier 5, in which it is formed into a short pulse with a duration of less than: rem / oj j pulse signal in delay element 9. This short pulse, transmitted to the first input of the first trigger 6, transforms into the zero state at the output in those cases when he was in a single state. These switchings pre-set the sensor measuring circuit to the initial state prior to the double-distance reference cycle h, which increases the reliability of the sensor itself.

Since the delay element 9 has not yet implemented the time delay f, the first one-shot 8 is not included. Therefore, at the third inputs of circuits And 10 and 11 there is a logical zero. Circuits And 10 and 11 are not included, and. The sensor does not accumulate information in integrators 12 or 13 about the performance of the mining machine, although an ultrasonic wave already propagates to the surface of load 27. This detuning per sensor t of the sensor operation in each measurement cycle is necessary in order to compensate for the loss of time for gating the signal in the amplifier forming 5, removed from the receiving-emitting transducer - 4 with the secondary excitation of its echo-wave reflected from the surface of the load 27. The process of gating itself due to a large attenuation of ultrasound in air and distortion of the reflected signal from an acoustically not smooth surface.

The load 27 provides for removing the hardware delay time €, j, which is compensated in the delay element 9. In general, this compensation improves the accuracy of the measurement by the mining machine performance sensor.

After the time t has elapsed, the delay element 9 is turned off, and the back edge of its pulse turns on the second one-shot 8. and the first trigger, 6 through its second input, which will generate single signals at its outputs. A single signal from the output of the first one-shot B, applied to the third inputs of the circuits And 10 and 11, prepares them for inclusion. The second flip-flop 18 changes the state of its output signals by resetting the output signal of the first one-shot 8 applied to the input of this flip-flop to zero. Such clock switching of the output signals of the second trigger 18 is performed at the end of each measurement cycle and is necessary in order to prepare the operation of the discrete-time information conversion channels for the next measurement cycle. Since the second trigger 18 has a counting input, the state of its output signals, for example, is the following: at the first output - logical 1, at the second output - logical O. Therefore, for time 2 at the inputs of the AND 16 circuit, the unit signals coincide and it supplies control to the first electronic switch 14, which closes and shunts the first integrator 12. The latter resets the previously accumulated information to zero. At the inputs of the circuit And 17 matches one, there will be no signals, so the second integrator 13 will hold and transmit to the second input of the third electronic key 19-accumulated

previous information for the previous measurement cycle.

In the period from the switching on of the first trigger 6 to the reception of the ultrasonic wave by the receiving-emitting transducer 4 in both integrators 12 and 13, there is no accumulation of information, since the circuits AND 10 and 11 are disconnected due to the mismatch of the signals at their inputs. Namely, at the first inputs of circuits AND 10 and 11 there is a logical O, as a result of inversion in the circuit NOT 7 of its input single signal coming from the output of the first trigger 6 .. After the time t has expired due to self-disconnection

0 of the second one-shot 2 at the first inputs of the circuits AND 16 and 17 a logical O appears, and therefore the first electronic key 14 opens. The first integrator 12 is ready to receive new

5 information.

The duration of the pulse C at the output of the second one-vibrator 8 is equal to the time of movement of the ultrasonic wave in the forward direction from the receiving-radiating transducer 4 to the groove of the conveyor 26 and back. Taking into account the constant speed of propagation of the ultrasonic wave C const in air, time t is proportional to the double distance H, i.e. . The time t of the stay of the first trigger 6 in a single state at the output is proportional to the double located distance h, i.e. , because the echo-wave reflected from the load 27 in the receiver-emitting converter 4 and the amplifier-former 5 is converted into a single short pulse, which translates the first trigger 6 through its first input to the zero state

S at the exit. Therefore, the output circuit

NOT 7 creates a logical 1, including in the described measurement cycle only an AND 10 circuit.

The switch on time of the circuit 10 tj is proportional to the double height

2hr

because this

those. (, (

to a. with . IJ - w-

the circuit is disconnected at the third input by resetting the output signal of the first single vibrator to zero. Over time 1, the first integrator 12 accumulates the signal A proportional to the double longitudinal section of the load 27 passing through the conveyor 26 in one measurement cycle. Analytically this signal can be expressed by the following dependency

 t,

A 2hrp- 1;

where 1 is the path of the load traveled by

conveyor, in one cycle of measurement, i.e. during t with

Vrp speed. .

Taking into account the constant values, we get A, cj С Vfp.T k, Cj, where K const and is the transfer coefficient of integrators 12 and 13. Thus, during one measurement cycle, the signal A in the first integrator 12 is generated and stored transferring it for further accumulation of readings within the optimal number of measurement cycles to the second memory cell. 23 through the third 19 and fourth 20 electronic keys occurs only in the subsequent measurement cycle with a delay equal to T. In the second integrator 13 at this time the process of forming the signal A will not / because it was formed in the previous measurement cycle, but it will only occur a transmission for further processing to the second cell of memory 23 via the third 19 and fourth 20 electronic keys.

In the next measurement cycle, i.e. in the next period of work of the master. generator 1, all the described processes are repeated with the only difference that the values of the logic signals at the outputs of the second trigger 18 are reversed, hence the third electronic switch 19 switches the output to its first input, leaving the second input open. As a result, the operation of the first, channel for converting discrete-time information such as the second to the pre-measuring cycle and vice versa. For, the optimal number of measurement cycles is p pt, the second cell 23 accumulates, but does not transmit, to the output of the inertia-free link 24, a signal AJ, the value of which is proportional to the double longitudinal section of the load 27 passing along the conveyor 26 of the mining machine, during a time opt

V

BUT..

those.

"P

 I

At this time interval T ngpt, the first memory cell 22 does not accumulate, but transmits to the input of the inertia link 24 through the fifth electronic key 21 already accumulated information about the Ag signal for the preceding optimal number of measurement cycles. This mode of operation of the memory cells 22 and 23 is due to the synchronism of switching electronic keys

0 20 and 21, produced by their control inputs from the output of the clock counter 25, the counting volume of which corresponds to the optimal (in terms of max & relative relative integral measurement accuracy of the mining machine) number of cycles measured. NIA napt.

When switching the fifth electronic key 21 in the memory cell that transmitted before switching. information A2 in the disinfection link 24, an automatic reset to zero occurs, and then the memory cell will be prepared for the accumulation of a new willow formation. The reset of information A j in memory cells 22 and 23 is accomplished

the reset pulse generated in the clock counter 25.

Signal A in a non-inertia link 24 is converted to signal A, proportional to the volume output of the mining machine, expressed in conventional units for mining machines, namely MVnHH. The conversion factor K a is entered into

5 the inertia-free link 24, as a constant value, is equal to 1 "where Z is the scale factor, the drive is the gross volume of the cargo being passed through the conveyor 26 in seconds,

0 to the value of the mining machine productivity, expressed in MVwHH and also leading to the last dimension in units of measure (B). B - the width of the conveyor trough 26. After appropriate substitutions, the output signal of sensor A, coming either to the display or to the automatic control system (ACS) mode of operation of the mining machine, can be expressed

oft

O .B.I. Г h, p Z.Qn, pt.

where the volumetric productivity for the optimum number of measurement cycles is equal to „

opt 5 Q Bl I. ... hp.

The memory cells 22 and 23, which work alternately as signal accumulators A and as elements for issuing information Al, are effectively averaged over the time T.

0 readings of individual measurement cycles, which ensures the accuracy and accuracy of information AJ on the performance of the mining machine in the average sense, eliminates the variation in the results of measurements of single cycles

and enables the stable operation of systems for automatic control of the operating mode of the mining machine.

The sensor was tested under the conditions of an experimental test bench on a mining loader with 2PNB-2 type sump pads. The frequency of operation of the master oscillator 1 of the sensor was 100 Hz, which at a speed of movement of the conveyor chain, 9 m / s corresponds to the distance between measurements in the direction of movement of the load less than 1 cm. The tests were carried out for different values of the number n (different degree of averaging) and 1-E) various goods. In particular, n accepted 20, 40, 60, 80, 100 cycles / and the characteristic of the goods was as follows (see Fig. 5):

I- dry, common with related

mm size;

Ii. - wet, average with average

size of a piece is 76 mm;

Ml - dry, lumpy, with an average size of a piece of mm;

IV - wet, lumpy, with an average size of the piece a (.. p 130 mm .... F

For each cargo, the loading machine, equipped with an automatic control system of operation, ensured a productivity of I 3, 75 m5 / min; II - 3.35 mVmin; III 4, 5 MVMHH; IV - 4.05.

A volumetric method using a measuring capacitance was adopted as a reference method for measuring performance. Figure 5 shows the results of estimates of the relative measurement error D% by the mining machine performance sensor, expressed as a percentage as a function of the number of measurements and properties of the material being immersed. .

The range of rational values of the number of measurement cycles is within Prag 45-75, and the optimal number of measurement cycles is Oopt 60. The value D) opi corresponds to the minimum of the relative integral measurement error of the performance sensor.

The sensor allows you to determine and adjust the performance of the mining machine. In this case, with the help of simple means, the optimal number of cycles is selected for averaging the results, ensuring minimal error in measuring the performance. The sensor is built according to a digital measurement scheme, which eliminates the error of the digital-to-analog conversion, is simple in structure and therefore has increased reliability.

Claims (2)

1. Measuring instruments and instruments for controlling parameters of mining, machinery and technological processes. Catalog, M., TsNIEI coal, 1979, p.85. 2.Yomakin MS Automatic management of technological processes of quarries. M., Nedra, 1978, pp. 292930 (prototype). From fug. / damvoffff e / Z.J