SU1317337A1 - Photoelectric device for checking surface flaws - Google Patents

Abstract

The invention relates to the field of non-destructive testing, namely, devices for detecting defects. The invention makes it possible to increase the reliability of quality control of the products in the form of rotation bodies by eliminating the influence of useful signals (signals from defects) on the value of the variable noise level of the surface Uy that determines the threshold of the comparison circuit 8. During the first revolution of the product 2 The noise and useful signals from the photodetector 3 are fed through the amplifier 4, the rectifier 5, the first switch 6 to the first input of the switch 13 and the input of the comparator I1. Depending on the magnitude of the amplitude of the signals (noise or useful signals) at the input of the comparator 11, the switch 13 transmits to the integrator either surface noise or voltage source U, reference voltage 12, corresponding to the average statistical noise level, respectively. During the second revolution, the signal Uj.4epe3, the second key 9, enters the comparison circuit 8, where it is compared with the measured level Ujj. When the amplitude of the signal U. exceeds the noise level and the output of the comparison circuit 8, a pulse is generated. Scrap, 2 Il. with (L with YavL oo h

Description

The invention relates to the field of non-destructive testing, in particular, to devices for detecting defects on the surface of wrap-shaped products, and large-scale and mass production.

The purpose of the invention is to increase the reliability of the control.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 is one of the possible options for performing a block for setting time intervals,.

 The device contains illuminator 1, product 2 whose surface is controlled, serially connected photodetectors 3, amplifier 4, rectifier 5 and first key 6, integrator 7, output connected to the first input of comparison circuit 8, the second input of which is connected to the output of the second key 9, time interval setting unit 10, the outputs of which are connected respectively to the control inputs of the first key 6, second key 9 and integrator 7, comparator 11, reference voltage source 12, switch 13, with the output of switch 13 connected to the input ohm integrator 7, the first input is connected to the input of the comparator 11 and connected to the output of the first switch 6, the second input is connected to the output of the source 12 of the reference voltage, the control input to the output of the comparator 11, and the input of the second switch 9 is connected to the output of the rectifier mitel 5 o

Constructive execution of the time interval setting block 10 does not affect the achievement of a positive effect and it can be of any execution. For example, block 10 may be made in the form of serially connected sensors 14 for the start of control, a driver 15 for the integration time interval, a generator 16 for the monitoring time interval and a generator 17 for the Reset pulse. Here, the outputs of the drivers 15-17 are the outputs of the block 10 for setting time intervals.

The control start sensor 14 can be made in the form of an electrical interrupter 18 fixedly mounted relative to the control rotor 19 and firing when the next position 20 with item 2 enters the control zone 21. Tripping

five

0

five

0

The trap 18 comes from acting on its pusher 22 by cams 23 fixed on the control rotor 19,

The device works as follows.

Products 2 at positions 20 (Fig. 2) of the control rotor 19 are rotated at a constant angular velocity and transported through the control zone 2. When entering the next position 20 with item 2 in the zone. 21 control, the next cam 23 acts on the pusher 22 of the electrodes 18 and at the output of the control start sensor 14, a control start pulse is generated by the level zero, which affects the input of the integrator 15 for the integration time interval, and an output pulse is formed at its output one turn of the product 2. On the falling edge of the pulse T, the shaper 16 of the control interval starts up and forms the output pulse T | control, the length of which is set equal to the time of one or several revolutions of the product.

On the trailing edge of the pulse T ,, for

pulse shaper 17 is started. A reset, at the output of which a short pulse Reset is formed. Such a sequence of pulses block 10

setting the time intervals is issued each time when the next position 20 with item 2 enters the control zone 21. These pulses control the operation of the entire control device,

In zone 21 of the control, product 2 (cf. 1) is illuminated by the light beam from illuminator 1. The light flux reflected from product 2, modulated by the surface profile and a change in its reflectance, is sensed by the photodetector 3, which converts the optical signal into an electric signal. The electrical signal from the photodetector 3, containing the useful signals and noise, is amplified by the amplifier 4, converted into a unipolar signal by the rectifier 5 and fed to the input of the first switch 6, If there is a control input of the first switch 6 at the control input 6 ) the first key 6 is open, the signal U from the output of the rectifier 5 is fed to the first input

mutator 13 and comparator input 1 1; Comparator 1 1 compares the current amplitude of the electric signal U with the average statistical noise level of high frequency of monitored items 2, which 1Y is determined in advance experimentally. When the amplitude of the signal exceeds a predetermined level, a prohibition pulse T is generated at the output of the comparator 11, the duration of which corresponds to the time that the signal amplitude exceeds this level. The presence of a pulse T, says about T9M, that this part of the signal supposedly contains a useful signal.

During the time of the first revolution of the product 2 (pulse duration Tj), the signal from the output of the first key 6 through the switch 13 is fed to the integrator 7 to determine the level of noise in it. When the comparator 11 detects the Up signal in the signal at its output, the logic level 1 generates a pulse Ti, which acts on the control input of the switch 13. At the same time, the switch 1-3 interrupts the signal 11 to the input of the integrator 7 and connects the signal to the input of the integrator 7 Fig. 1 from the reference voltage source 12. The magnitude of the voltage Upn corresponds to the average noise level of the monitored products 2 and is determined experimentally from the results of monitoring the batch of usable products 2 prior to the control of the current n artery products 2, At the end of the pulse T, the switch 13 re-connects the signal Uj to the input of the integrator 7, etc. Thus, during the first turn of the product 2, the signal Uc before it arrives at the integrator 7 is converted areas that are supposedly formed from defects are cut out, and each cut area is filled with the reference voltage Uon throughout, thus eliminating the effect of useful signals on the value of the noise level measured by integrator 7.

At the end of the first revolution of product 2, a constant voltage C, is established at the output of integrator 7, the value of which corresponds to the noise level of the test surface. At the same time, the impulse T ends | and block 10 of the task of time intervals produces a pulse T ,,

control Accordingly, the first key 6 is closed, the second key 9 is opened, and the signal Uj. from the output of the rectifier 5 (the second turn of the product 2) goes through the second switch 9 to the second input of the comparison circuit 8, where the amplitude of the signal U (. is compared with the voltage level Пщ, supplied to the first input of the comparison circuit 8 from the output

integrator 7.

Defects on the test surface are detected when the amplitude signal U is exceeded. The noise level U ,. In this case, the output of the circuit 8 comparison

Marriage impulses are formed. These pulses can then be fed to a recording device to make decisions about the quality of the test surface.

At the end of the pulse T, the second key 9 is closed, and the block 10 for setting time intervals generates a short pulse Reset, which acts on the control input of the integrator 7 and brings it back to the initial zero state. The device is ready to control the next product.

The use of the proposed device (compared with the known)

improves the accuracy of measuring the noise level in the signal from the monitored surface, i.e. reduces the difference between the measured and true values of the noise level in the signal, eliminating the influence of useful signals on the measurements performed. This increases the reliability of the detection of defects, the amplitude of the signal from which by no more than 10-50% increases the noise level, beyond

depending on the presence or absence of one or several defects on the product surface with an amplitude of 1, 5 or more times. The noise level is superior. This increases the reliability of the control as a whole.

Claims (1)

Formula invented and A photoelectric device controlling surface defects containing an illuminator, along the rays of which a photodetector is installed, to the output of which an amplifier, a rectifier and a first switch, an integrator are connected in series, the output connected to the first input of the comparison circuit, the second input to which is connected to the output of the second key, task block 513 time intervals, the outputs of which are connected respectively to the control to the dim inputs of the keys and the integrator, characterized in that, in order to increase the reliability of the control, a comparator, a source of the reference voltage and a switch, the output of which is connected, are introduced into the device 73376 with the integrator input, the first input is combined with the comparator input and connected to the code of the first key, the second input is connected to the output of the reference voltage source, the control input is connected to the comparator output, and the input of the second key is connected to the output of the rectifier. Editor A, Revin Compiled by A, Churbakov Tehred A. Kravchuk Order 2416 / 39Tire already 776Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 Production and printing company, Uzhgorod, st. Project, 4 Proofreader L, Pylypenko