SU1677518A1 - Ultrasonic measurement of diameter of round parts - Google Patents

Abstract

The invention relates to a control and measuring technique and can be used to determine the diameter and coordinates of the center of cylindrical objects, for example, moving timber, in particular, tree trunks and logs. The purpose of the invention is to increase the measurement accuracy with an inhomogeneous product surface. The goal is achieved by conducting echo-location by two independent measuring channels, in each of them in three directions, with six echoes simultaneously, the minimum time of propagation of the echoes from the product surface is measured and, taking into account the measured speed ultrasound calculate the diameter of the circular products. 2 Il.

Description

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The invention relates to a measurement and control technique and can be used to determine the Diameter and coordinates of the center of cylindrical objects, for example, moving timber, and particularly, tree trunks and logs.

The purpose of the invention is to improve the accuracy of measuring the diameter with a non-uniform product surface.

Figure 1 presents the measurement scheme proposed by the method; figure 2 is a device that implements the proposed method.

The device contains a controller 1, which controls the operation of the device and all computational operations to determine the diameter of the product, a display 2, a master clock 3, a divider 4 frequencies and two blocks 5, forming a probing message and making the selection of echo signals of sensor 6. Sensor 6 consists of two identical measuring channels and one reference one. The ultrasound transducer 7 is coupled to a 4 frequency divider. The fixed reflecting surface 8 constitutes the reference channel. Three ultrasonic transducers 9 constitute the main measuring channel, and three similar transducers 10 constitute an additional measuring channel. Position 11 denotes the object to be monitored. The conveyor 12 provides the possibility of moving the object in the transverse and longitudinal directions relative to the axis of the sensor 6. The electronic switches 13 connect the controller 1 to the corresponding high-Q bandpass filter 14.

The method is as follows.

ABOUT

1 VJ ate

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The echo location is carried out by two independent measuring channels and by three minimum distances from the measuring channel to the object of measurement, and the diameter and coordinates of the center are calculated. The distances are determined by the delay time of the echo signals of one reference and two measuring channels. In the reference channel, the rate of propagation of ultrasound at the time of measurement is limited. The diameter determination is possible only when echo signals are received by all ultrasonic transducers entering the sensor, otherwise it is necessary to change the position of the measurement object relative to the sensor (as the log moves along the conveyor, this condition is automatically satisfied). The diameters obtained from both measurement channels are averaged to reduce the effect on the final result of the presence of knots, chipped bark and sagging. Analyzing the coordinates of the center of the measurement range, it is possible to additionally determine the deflection of the measurement object (log), which for roundwood is a widespread defect, the detection of which significantly affects the quality of products. Each sensor measuring channel consists of three ultrasonic transducers located one in the other on a straight line and a fixed distance a between themselves. Ultrasonic transducers of one channel each operate at their own frequency, three different frequencies are chosen so that ultrasonic transducers receive only their own reflected signals from the object and do not react to others, since measurement is possible if there are three minimum distances from each other to the object 11 measurements. The difference in operating frequencies is also determined by the bandwidth of the device: the wider the bandwidth, the more frequencies must differ. In the main measuring channel, the ultrasound transducers 9 are located at a distance from one another, for example, the outermost of them is located at the beginning of the Cartesian coordinate system, while the others are located on the abscissa axis with the coordinates X a; Y: o and X 2a; Y 0. Additional measuring channel is located mainly with a shift of 0.5a, the coordinates of ultrasonic transducers 10, respectively, X 0.5a; Y O, X 1.5a; Y 0 and X 2.5a, Y 0. The distance a depends on the range of possible diameters of the object to be measured. So that the ultrasonic transducers 9 of the main and additional measuring channels of the sensor operating at the same frequency do not affect the operation of each other, their X 0 coordinates; Y O and X 1,5a; Y O, X a; Y OnX 2.5a; Y O, X 2a; Y — 0 and X 0.5 a; Y 0. The location of all ultrasonic transducers on the abscissa axis simplifies the calculation formulas, and also removes restrictions on the movement of the measurement object 11 relative to the sensor. The reference channel consists of an ultrasound transducer 7 and a fixed reflecting surface 8 located at a fixed distance known in advance (La).

The controlled object 11, in particular the log, moves along the conveyor 12 in the transverse or longitudinal direction relative to the axis of the sensor 6. The controller 1 connects the electronic switch 13 to the ultrasonic converter 7 clock frequency from splitter 4, after a certain time the controller 1 switches off the same switch 1J3 from the converter 7, the clock frequency and connects the converter 7 to the high-quality band-pass filter 14, tuned to the selection of the frequency of the probe pulses. The ultrasonic pulses emitted by the transducer 7 are reflected from the fixed reflecting surface 8 located at a fixed and previously known distance C, after a certain time interval te, the pulses are received back by the transducer 7, the controller 1 records this time through the filter 14 and calculates the speed distribution of ultrasound in medium C at the moment by the formula

2U (1)

Te

Having determined the speed of ultrasound C at the time of measurement, controller 1 starts to execute a program for determining the diameter and coordinates of the center of the object. The controller 1, controlling the electronic switches 13, connects to the ultrasonic transducers of both measurement channels the signals of different frequencies generated by the divider 4, after a certain period of time, the controller 1 finishes forming the probing package, turns on the software checkout time counter and simultaneously switches the ultrasonic transducers of both measurement channels to high-quality (with a narrow bandwidth) bandpass filters 14, tuned to the allocation of frequencies to the frequency of the radiation of the corresponding pref -.

educator If during the control time (it is equal to the time of receiving the echo signal from the surface of the conveyor 12) all six echo signals are received, then the minimum measured distance LI from the object under test 11 to the corresponding ultrasonic transducer is determined.

-2U

te, l

rr u (2)

if the echo signals are not received from all the transducers, after some time the controller 1 tries again to receive all six echo signals (this time depends on the speed of the conveyor 12). If the measurement is successful, controller 1 determines the diameter and coordinates of the center of the measurement object using the formulas

n -OR -L + LS-2LS-2a2., 3)

Dx - 2RX2L2 - Li - U (3)

 (Li 4- RJ |) + a2 - (L2 + Rx).

Y - yi x; -Ј. .;. (d

 2a l W

(Li + Rx) 2-X2. (5)

These formulas are the result of solving a system of three equations: X2 + Y2 (L. + Rxf; (X-a) 2 + Y (L2 + Rx) 2; (X - 2a) 2 + Y2 (La + R x) 2.

The equations are based on the fact that the radiation pattern of the ultrasonic transducers in the measurement zone can be considered circular (in fact, it is approximately 50 °). After determining the delay time from the ultrasonic transducers of the main and additional measuring channels to the object, the minimum distances of the main Li, La, l – z and additional Li1, La1 Ls1 channels are determined. The resulting distances Li, L.2, J, Li, L2, are the radii of the circles tangent to the object of measurement. Since the tangent to the circle is perpendicular to its radius drawn to the point of tangency, the resulting radii Li, L.2, L3, U1, L21, Lj 1 are on the same straight line with the desired radius Rx of the object. If we construct additional circles with the same centers and radii (Li + Rx), (L2 + Rx), + RX), then these circles will intersect at one point, which is the desired center of the object's circle (for an additional channel, similarly). In the calculations, it is assumed that the leftmost transducer is located at the beginning of the Cartesian coordinate system, and all transducers are located on the x-axis. From the 1st equation of system (6) are

ten

15

20

25

thirty

35

40

45

50

55

X and substitute this value in the 2nd and 3rd equations.

V (Li + R -f-V2-af + Y2 - (L2 f Rx) 2:

(V (Li + Rx) 2 - Y2 - 2af + Y2 - (U + R.f. From the first equation of the obtained system, find Y and substitute it in the 2nd equation. Perform the transformation, get

2a - (Li + RxT + 2 (L2 «Rx) (U Rx) - 0.

„Production of the transformation, get the calculated formula (3) for the diameter of the object Dx. Formulas (4) and (5) are also obtained by the joint solution of the system of equations (6). By the same formulas (3), (4). (5) the calculation is also carried out for an additional measuring channel, but the coordinate system is preliminarily shifted along the abscissa by a / 2 so that the coordinates of the center of the object belong to the same coordinate system. For an object with a smooth surface, the coordinates of the center and the diameter obtained from both measurement channels are the same, for such objects a single channel is sufficient, and for an objector with an uneven surface (for logs, knots, chipped bark, napyvy) also more.

The program controller averages the results from both measurement channels. The final diameter value is the arithmetic average of the diameters obtained from the measuring channels. This measure makes it possible to increase the accuracy of determining the diameter and reduce the effect on the final result for round timber in the presence of knots, chipped bark, sagging. The values received enter the display 2 and the process control device (UUTP)

Claims (1)

The invention The ultrasonic method of measuring the diameter of round products, which consists in measuring the propagation speed of ultrasound in the environment where the product is placed, echoes the product in one direction in three directions, at different angles, determines the minimum propagation time of the echo. signals from the surface of the product and taking into account the speed of ultrasound, determine the diameter of the circular products, characterized in that, in order to increase the measurement accuracy with a non-uniform product surface, simultaneously with the fundamentals th carried echo location in three directions of an additional article izopredel dissolved diameter in the additional measurement channel, the primary and secondary echo-location is carried out at different frequencies for each channel, and for diafig .1 the meter of the product being tested takes an arithmetic average of the diameters calculated in the primary and secondary measurement channels, About 0.1 0.1 0.3 LS Scale5 0.1m