SU1657961A1 - Device for measuring dimensions of transparent tubes - Google Patents

Abstract

This invention relates to instrumentation technology. The purpose of the invention is to improve the accuracy by taking into account the light rays that have passed through the controlled pipe, and to increase the information content by measuring the internal diameter of the pipe. The device consists of a source of light 1, a diffuser 2, a slit diaphragm 3, a lens 4 and a phase receiving receptacle 5. When the tube 25 is lumen with light scattered by a diffuser 2, the intensity distribution on the photodetector 5 depends on both the external and internal diameters pipe 25. 4 Il.

Description

The invention relates to instrumentation technology and can be used to control the diameter of transparent pipes.

The purpose of the invention is to improve the accuracy by taking into account the light rays that have passed through the controlled pipe, and to increase the information content by measuring the internal diameter of the pipe.

FIG. 1 shows a block diagram of the device; in fig. 2 - dependence of the beam entry angle on the output coordinate and the signal on the photodetector; in fig. 3 - scattering geometry of rays by a transparent tube; in fig. 4 - time diagrams of the operation of the device blocks.

The device consists of optically coupled light source 1, scatterer 2, slit diagram 3, lens 4 and photodetector 5, video processing unit 6, consisting of

inverter /, whose input is connected to the output of photodetector 5, trigger 8, the counting input of which is combined with the input of inverter 7, trigger 9, the counting input of which is connected to the output of inverter /, trigger 10, the counting input of which is connected to the forward output of trigger 8, trigger 11, the counting input of which is connected to the forward output of the trigger 9, the trigger 13, the counting input of which is connected to the forward output of the trigger 10, trigger 14, the counting input of which is connected to the forward output of the trigger 11, element 15 OR-LF, the inputs of which are connected to direct output t the trigger 3 and the inverse output of the trigger 9, respectively, of the element 16 OR NOT, the inputs of which are connected to the output of the element 15 OR-NOT and the inverse output of the trigger 12, the element G / OR-CHE, whose inputs are connected to the inverse outputs of the trigger 13 and 14, sequentially the connected counter 13, the input of the permission of which account is connected to the output of the element 16 OR-NOT, and the register 14, connected in series with the counter, the input of the permission of the account of which is connected to the output of the element 1 / OR-НК, and the register .11, and the generator .., the output of which is connected to the counting inputs counters 18 and .O, the computing unit 23, made in the form of a programmable controller, the synchronization input of which is connected to the synchronization output of the photoreceiver 5, the information inputs are connected to the outputs of registers 14 and 21, the first synchronization output of the Start of measurement is connected to the 8– 14 and counters 18 and 20, the second synchronization output. The end of measurement of which is connected to the clock inputs of registers 19 and .1, whose input is connected to the output of block 23 and indicator 24.

The device works as follows.

The flux of light from the source 1, diffused by the diffuser,. and bounded from two sides relative to the plane in which the registration is located and the axis of the transparent pipe 25, with diaphragm 3, illuminates the transparent pipe 25. Objective 4 transfers the image of the object under study to the analysis plane in which there is a discrete photodetector 5. Thus, from the stream scattered rays passing through the transparent tube 5, using lens 4, emit a beam of paraxial rays that entered the transparent tube 5 in the sector bounded by planes passing through the inner edges of the slit diaphragm 3 and transparent tube 5. Fixing the beam of paranoia rays of rays, COCYOHI OTO from light and dark stripes, is carried out by the photointerface 5 and the plane perpendicular to the axis of the transparent tube 25. At the output of the YouTube receiver 5 (the video signal normalized to Fig. 15 is normalized There are no RAYS OF BEAMS whose angles of entry into the ghost tube 5, the specimen registration line and the pins passing through the edge of the diaphragm 3 and the transparent tube .. t, exceed in absolute value ± 0

-9, „, ± 0

P

72L

Ep

 , 9gp and Qi, n gh) e

0

Actual values of the angles of entry into the transparent tube 25 of the rays, respectively, passing through the two walls of the tube 25 and its internal opening (see graphs L and A1 in Fig. 2a and beam A in Fig. 3), experienced the phenomenon of total internal reflection at the boundary of the inner holes (see graphs B and B in Fig. 2a and rays B and B in Fig. 3) and those that have only passed through the wall of pipe 25 (see graphs C and C in Fig. 2a and beam C in Fig. 3).

A plot of the angle of entry of optical rays in a transparent tube 25 on the coordinates of the output rays of the rays parallel to the line of registration shown in FIG. 2a, built on the basis of dependencies:

l., x. X. X (Y, 2 (arcsin- -arcsin- + arcsin-- pa

-arcsiorJ;

nb (o

X X 9 2 (arcsin1-arcsin - + arcsin-- x -arcsin-);

b

0

five

0

five

0

five

e, -c

where b, is the angle of entry of the rays passing through the two walls of the pipe 25 and the inner opening; the angle of entry of the rays passing through the wall of the pipe 25 and experiencing the appearance of total internal reflection at the boundary of the internal opening of the pipe 2.5; 9 the angle of entry of the rays passing only through the wall of the pipe 25 and not entering the internal opening; n is the refractive index of the material of the pipe 25 (the refractive index of the air surrounding the pipe and the inner hole is 1); - a and 2b are the inner and outer diameters of the transparent pipe 25, X is the coordinates of the exit relative to the line of registration of rays passing through the pipe 25 and extending parallel to the line of registration.

Relations (1), (2), (3) are obtained on the assumption that the centers of the inner bore and the outer circumference of the pipe 25 coincide.

The graph in FIG. 2a indicates that when clipping rays, the angles of entry into the transparent tube 25 exceed the corresponding values of i0w, t9in, t0w, result in their absence in the beam of rays, the output tsikh from pro51b

transparent pipe 15 parallel to the registration line.

The absence of rays in the beam leads to the formation of dark bands, which corresponds to the level of the;;) signal on the FU.IXO- de photodetector 5 (Fig. 2). The rays that enter the transparent tube 25 inside the sectors bounded by the angles of ± 9 (1, ...) n form bright bands of light in the beam of paraxial rays, which corresponds to the level 1 of the signal at the output of the photodetector 5 (Fig. 2).

According to equations (1), (2), O) the position of the borders of light and shade depends

1ft

from the parameters 5 and the dimensions of the diaphragm 1, which specifies the limiting angles of entry of the rays and the measured object. Therefore, the position of the borders of light and shade can be judged on one of the parameters of the transparent tube 25, fixing the remaining parameters of the object and the position of the limited faces of the diaphragm 3.

For example, fixing the values of the refractive index of the material of the pipe 25, its outer diameter, the limiting angle P2c of the entrance of the rays into the pipe 25 and the position of the light and shadow edges ± X- (Fig. 3), find the value of the internal diameter of the pipe 25 by equation (2):

2X2.

. , , - 2 nsin (aresin1 + arcsinn

The values of the outer diameter are determined by the position of the luminosity i X (Fig. 3), formed by the outer edges of the tube 25, according to the formula

(five)

To determine the numerical values of the distances between the edges of light and shade 2X, Ј, and X., a video signal processing unit is used, whose operation diagrams are taken from FIG. 4. Pulses of duration are formed by the element 16 OR-NOT from the signals at the output of the trigger 12 and L (at the output of the element 15 OR-NOT. The pulses are of the duration (formed by the element

1 / OR-NK from U signals

ABOUT

and u

AND

at the output of the flip-flops 13 and 14. The number of pulses proportional to the duration of the pulses t and t are counted by the counters 18 and 20, respectively. At the information outputs of the registers 19 and 21, the digital values of the pulse durations are generated by the CI signal

Nz tlЈ0 2X2f0) (6)

N t..fft

4. 4- О Ч- О

(7)

where fQ is the oscillator frequency 22. i

In block 23, the calculations, after the end of the video signal formation cycle by the photodetector 5, taking into account equations (4) - (7), the values of the inner d and outer O diameters of the transparent tube 25 are calculated.

The results of the calculations are indicated by the indicator 24.

. 2Hg 02p. arcsin-- - ---) i) 2

(four)

,

five

0

five

0

The value of the limiting angle (set during calibration of the device, the position of the diaphragm 3 is fixed. The device is calibrated using a reference sample of pipe 25 with known values of internal and external diameters.

To ensure device operability, the diaphragm 3 dimensions must exceed the maximum external diameter of the measured pipes 25. It is advisable to set the value of the limit angle Q in of the entrance of the rays to the pipe 25, experiencing the appearance of total internal reflection at the boundary of the internal opening, established experimentally as well as analytically by calculating the dependences of the entrance angles of the rays passing through the object under study on the coordinate of their exit from the object parallel to the recording line for different the ratio of external and internal diameters of transparent pipes. For the one shown in FIG. 2a examples) °.

Claims (1)

Invention Formula A device for measuring the geometrical dimensions of transparent tubes, comprising an optically coupled light source, lens and photodetector, and an indicator, characterized in that, in order to increase accuracy and informativeness by measuring the internal diameter of the pipe, it is equipped a diffuser and a slit diaphragm installed between the lens and the light source, connected in series by a video signal processing unit, the input of which is connected to the photoreceiver output, and a calculation unit, the output of which is connected to the indicator input.