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Method and device for testing the material of a test object in a nondestructive manner

A non-destructive, material inspection technology, applied in the direction of material analysis, analysis materials, measuring devices, etc. by electromagnetic means, which can solve problems such as consumption

Active Publication Date: 2014-06-04
INSTITUT DR FORSTER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the detector, the frequency spectrum of the signal caused by the defect in the test object depends on this relative speed, so that a relative speed-dependent filter bank is usually required for the detector signal, which entails additional expenditure.

Method used

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  • Method and device for testing the material of a test object in a nondestructive manner

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Embodiment Construction

[0020] figure 1 shows a device for the non-destructive material testing of a test object 8 which is moved with a variable relative velocity known in the device relative to the magnetic field detector 1 and which is moved by means of a magnetic field not shown in detail The generating device applies an alternating magnetic field to the test object, which is generated by means of an excitation signal, wherein the excitation signal is periodically varied with at least one predetermined excitation frequency or carrier frequency, so that the alternating magnetic field is also at least A predetermined excitation frequency or carrier frequency is changed periodically. The excitation frequency or carrier frequency can lie, for example, in the range of 1 kHz to 500 kHz.

[0021] A corresponding effective alternating magnetic field is thereby generated in the test object, so that the detector signal US has at least one carrier frequency and is modulated in its amplitude and / or phase ac...

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Abstract

The invention relates to a method for testing the material of a test object (8) in a nondestructive manner, said test object being moved relative to a probe (1) at a variable relative speed. The method has the following steps: detecting a probe signal (US) using the probe (1); converting the probe signal (US) from analog to digital in order to generate a digitized probe signal (USD) in the form of a sequence of digital words with a specified, in particular constant, word repetition frequency; decimating the word repetition frequency of the digitized probe signal (USD) or a digital demodulation signal (UM) derived from the digitized probe signal in n stages using n cascaded decimating stages (5_1 to 5_n), wherein n = 2; selecting an output signal (UA_1 to UA_n) of one of the n decimating stages (5_1 to 5_n) dependent on the current relative speed; and filtering the selected output signal using a digital filter (7) that is clocked at the word repetition frequency of the selected output signal.

Description

technical field [0001] The invention relates to a method and a device for non-destructive material inspection of inspection objects. Background technique [0002] In non-destructive material testing, defects are detected in test objects, for example in the form of metal semi-finished products. [0003] In a test method variant, a periodic electromagnetic alternating field is applied to the test object by means of a sinusoidally energized transmitting coil. The eddy currents thus induced in the test object in turn induce a periodic electrical signal in the detector, for example in the form of a coil or coil arrangement, which has a carrier oscillation as follows: When a defect arrives in the measuring range of the detector, the amplitude and / or phase of the carrier oscillation is modulated in a characteristic manner by the defect in the test object. [0004] During material testing, the test object can be moved with a variable relative speed relative to the detector, for ex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/90G01N29/36
CPCH03M1/60G01N27/9006
Inventor B.霍尔茨迈尔M.哈尔特
Owner INSTITUT DR FORSTER