RU2376596C2 - Method of automated ultrasonic inspection of sheets - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used in automated ultrasonic inspection of sheets. An ultrasonic transducer is used to scan in two mutually perpendicular directions: back and forth across a sheet and discontinuously along the sheet in a straight line. Ultrasonic waves are emitted and received along the sheet. Current coordinates across and along the sheet are recorded using distometres. Current coordinates of detected defects across the sheet and actual coordinates along the sheet are recorded as a sum of current coordinates from the distometre along the sheet and distance from the transducer to the defect along the sheet. Signals are generated for controlling transducer scanning during primary detection of defects in order to reduce the scanning pitch along the sheet by a value less than the distance from the transducer to the defect. An earlier detected defect is detected again during reverse cross scanning. Parametres and coordinates of the same defect obtained during primary and secondary detection are compared, upon coincidence of which parametres of the defect and coordinates are stored until the end of inspection. Simultaneously, a signal is generated for marking location of the defect on the surface of the sheet, and the scanning pitch along the sheet is returned to the previous value. After inspection results are printed on a printer in form of a defectogram and checking protocol.

EFFECT: more reliable ultrasonic inspection of sheets.

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Description

The invention relates to the field of non-destructive methods of quality control of workpieces and semi-finished products, in particular to automated ultrasonic input quality control of metal sheets, and can be widely used in various engineering industries.

A known method of non-contact ultrasonic testing of long products and pipes, including moving the control object through the scanning mechanism with the transducers installed on it, tracking and comparing the signals received from the transducers to the control unit, determining coordinates, scanning, sending commands to trigger the marker, while controlling movement the front and rear ends of the test object, the position of the transducers relative to the surface of the object, the location of the defect detected pre by the browser, it is carried out by placing along the transport line several blocks of transducers and measuring instruments for moving the control object along its movement with fixed distances from the origin of the coordinate axes, the intersection point of which lies on the axis of the optical sensor, and moving the transducers by feeding them at the moment the front end of the control object approaches and retraction at the moment of approaching the rear end of the control object, and the approach and retraction is carried out according to commands from the control unit (RF application No. 2002129062, cl. G01N, publication date 04/27/2004).

However, the method has several disadvantages:

- designed for ultrasonic testing of long products and pipes and cannot be used for sheet inspection;

- requires a complex installation design for its implementation to execute all of the above commands;

- does not contain means and methods of documenting the results of control, which reduces its reliability;

- has a sophisticated system for protecting the marker from accidental electromagnetic or acoustic interference.

There is also another method for automated ultrasonic testing of sheet metal welds, including rough scanning of an ultrasonic transducer (sensor) parallel to the surface of a controlled object in two mutually perpendicular directions in the form of reciprocating movements, processing signals from an ultrasonic transducer and track sensors, storing processing results and output them on the display, generating control signals of the scanning mechanism, while scanning first parallel to the test site in one direction, then it moves a short distance perpendicular to the site and then back, data showing the position of the transducer, amplitudes of the received signals are stored, when defects are detected, control signals are generated by scanning the transducer to move it to the defect in accordance with the exact scheme scan, similar to the rough scan scheme, but rotated 90 °, and data on the position and properties of the defect are recorded lei (US Patent No. 4294118, CL 73-620, publication date 10/13/89).

The method of ultrasonic testing of welds of sheet material has several advantages over the previous method. It is designed to control the quality of welds of sheet materials, provides more complete information about the location of the defect in two coordinates, has more complete protection against accidental acoustic or electromagnetic interference.

However, along with the available advantages, the method has its drawbacks:

- designed to control not the quality of the sheet, but only the weld of sheet materials;

- has a sophisticated program for controlling coarse scanning and precise scanning, deployed perpendicular (at an angle of 90 °) to each other;

- control results are recorded only on the display;

- there is no registration of defects on the surface of the sheet, which is especially important when monitoring large sheets;

- there is no documentation of the results of the control on a long-term storage medium, for example, on paper;

- due to switching scan programs, control performance is reduced;

- when changing the direction of the scan, it is difficult to assess that a newly discovered defect is not another defect, namely, a previously detected one.

Despite the disadvantages, the control method of the welds of sheet materials is the closest analogue of the invention and therefore adopted as a prototype.

The task of the invention is to remedy these disadvantages of the prototype and analogue which is achieved by the following technical solutions:

- reducing the step size (discrete movement) of the transducer along the sheet when a defect is detected during its movement across the sheet to a value less than the distance from the transducer to the defect;

- determination of the actual coordinates of the defect along the sheet as the sum of the current coordinate and the distance from the transducer to the defect;

- re-detection of the defect during reverse scanning of the transducer across the sheet;

- location marking upon repeated detection on the surface of a controlled sheet;

- documenting the results of control using a printer in the form of a defectogram and a control protocol.

The proposed method is illustrated graphically in figures 1 and 2, where 1 is a controlled sheet, 2 is an ultrasonic transducer, 3 is a defect in sheet 1, 4 is the scan path of the transducer 2 in the absence of a defect 3, 5 is the scan path of the transducer 2 when defects are detected 3 more than one, 6 - path sensor across the sheet 1, 7 - path sensor along it.

The method is as follows.

On the surface of the sheet 1 parallel to it, they are scanned by the ultrasonic transducer 2 along the path 4 in the absence of defects 3 or along the path 5 if they are present in the sheet 1. During the scanning process, the transducer 2 emits ultrasonic vibrations along the sheet 1, which propagate along it or go out on its paths, or are reflected from the defect 3 if it is present and returned to the converter 2. They are received, converted into electrical signals, which determine the parameters of the defect 3, the distance to it from the converter 2, the actual The dimensions of defect 3 across sheet 1, the current coordinate along the path sensor 6, along sheet 1 as the sum of the path that is current along the sensor 7 and the distance from transducer 2 to defect 3. The defect parameters are entered into RAM and a signal is generated to reduce the step of transducer 2 (values its displacement) along sheet 1 to a value less than the distance of the defect 3 from the transducer 2. After the signals from the defect 3 are finished, the transducer 2 is scanned across the sheet 1 according to the specified program until it reaches the edge. Then, the transducer 1 takes a step along the sheet 1, but the size of this step is less than the distance from the transducer 2 to the defect 3 (Fig. 2) by a predetermined amount, and scanning of the transducer across the sheet 1 in the opposite direction begins. In the process of such a scan, the transducer 2 re-detects the defect 3 and converts the acoustic waves reflected from it into electric signals, which are used to determine the parameters of the defect 3, and they are compared with its previous parameters. If the parameters in coordinates differ from the previous ones by no more than 1 mm, they are entered into the memory, which stores them until the end of the whole sheet 1. The further scanning in the absence of defects 3 is carried out with the same step. If defects 3 are detected in a subsequent scan, all operations carried out with the first defect 3 are repeated.

In the case when when transverse scanning along the sheet 1 in one direction of the transducer 2 is detected more than one defect 3, the scanning step (offset) of the transducer 2 along the sheet 1 is set less than the distance from the transverse path of the transducer 2 to the nearest defect 3 (Fig.2) . The operations carried out for each of these defects 3, during their primary and secondary detection, are carried out similarly to the operations described previously for one defect 3, except that if there are several signals generated to establish the step after the first detection of defects 3, choose the one that forms the smallest step size. After the end of the control of the whole sheet, the control results are printed on the printer in the form of a defectogram and protocol.

Thus, reducing the scanning step along the sheet after the first detection of a defect to a value less than the distance from the transducer to the defect allows you to fix the defect again and make sure that the initially fixed defect is not an obstacle, which increases the reliability of ultrasonic inspection of the sheets. The operation of the marker during the secondary detection of a defect allows without stopping the automated control to note the position of the defect on the sheet surface, which facilitates its cutting during further operations. This will maintain control performance. Documenting the results of control increases its objectivity and reliability, excluding the human factor. Printing control results on a printer allows them to be stored for many years, which is very important in the production of the most critical products.

Information sources

1. RF patent No. 2147745, cl. G01N, publication date 04/20/2002

2. RF patent No. 2140629, cl. G01N, publication date 10/27/1999

3. US patent No. 4294118, CL. GO1N, publication date 10/15/1981

4. RF application No. 2002129062, cl. G01N, publication date 04/27/2004

5. Auth. testimonial. USSR No. 548802, cl. G01N 29/04, publication date 02/28/1977

Claims (1)

A method of automated ultrasonic inspection of sheets, including scanning by an ultrasonic transducer in two mutually perpendicular directions: reciprocating across the sheet and discrete rectilinear along it, emitting and receiving ultrasonic vibrations along the sheet, reading current coordinates across the sheet and along it using path sensors, recording current coordinates, detected defects, across the sheet and the actual coordinates along the sheet, as the sum of the current coordinates for the path sensor in this the alignment and the distance from the transducer to the defect and its coordinates, the formation of control signals for scanning the transducer during the initial detection of defects to reduce the scanning step along the sheet by an amount shorter than the distance from the transducer to the defect, re-detection of a previously detected defect during reverse transverse scanning, comparison of parameters and coordinates of the same defect obtained during primary and secondary detection, if they coincide, the defect parameters and coordinates they are stored until the end of the control, at the same time a signal is generated to mark the location of the defect on the sheet surface, and the scanning step along the sheet returns to its previous value, after the end of the control, its results are printed on the printer in the form of a defectogram and control protocol.

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