Measuring and testing – Vibration – By mechanical waves
Patent
1992-11-13
1995-12-19
Chilcot, Richard
Measuring and testing
Vibration
By mechanical waves
73634, 73159, G01N 2926
Patent
active
054760119
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to non-destructive testing, and more particularly to the non-destructive testing of sheet materials such as steel plate.
Non-destructive testing is one of the standard techniques for testing the quality of products and materials, and amongst the most common non-destructive testing techniques are ultrasonic testing techniques. Ultrasonic techniques may be used for detecting surface defects and/or internal defects and/or thickness variations.
Non-destructive testing of steel in sheet form such as steel plate (which may for example be of the order of 3 mm in thickness or greater) is a particularly important application of the technique, because such steel plate is the end product of the relevant steel production process, and the provision of testing on an automatic basis of the quality of the plate produced is of great utility to the manufacturer.
2. Description of the Prior Art
Known and existing methods of such automatic ultrasonic testing of sheet materials usually involves moving one or more testing heads in a straight line along the length of the material, although in an attempt to cover a greater area of the sheet material a sinusoidal path of the testing head or heads relative to a sheet of material has been proposed and used in some instances by transverse oscillation of the head as the sheet material moves therepast. A continuing problem with these previous proposals and existing methods is the limitation of coverage of the testing across the sheet material.
SUMMARY OF THE INVENTION
It is an object of the present invention to enable the provision of improved ultrasonic testing of sheet materials, particularly but not exclusively of steel plates.
According to one aspect of the present invention there is provided apparatus for ultrasonically testing sheet material comprising at least one ultrasonic sensor mounted on a rotatable test head for rotation about an axis of rotation thereof, said axis of rotation being arranged such as to be, in use, substantially normal to the mean plane of the sheet material as it moves therepast.
According to another aspect of the present invention there is provided a method of ultrasonically testing sheet material comprising rotating at least one ultrasonic sensor, mounted on a rotatable test head, about an axis of rotation substantially normal to the plane of the sheet material as it moves therepast.
In a preferred embodiment, in operation, the rotation of the test head occurs as the sheet material moves past on a continuous basis, the test head carries a plurality of sensors, and a plurality of test heads are disposed across the sheet material transverse to the direction of movement thereof. The plurality of test heads may be disposed in a staggered array of a plurality of rows.
The ultrasonic sensor or sensors may comprise devices ultrasonically connecting to the relevant surface of the sheet material by means of a free jet of contact fluid, or by means of appropriately configured contact shoes, which may additionally include provision for an intervening layer of contact fluid.
The ultrasonic sensors may comprise sheet thickness sensors and/or interior defect sensors and/or surface defect sensors.
In one embodiment of the invention a plurality of groups of four surface defect testing sensors may be spaced around the rotatable test head. The orientation of the groups of surface defect testing sensors may be at different angles to the normal to the axis of rotation of the rotatable head.
The testing sensors may be arranged such that during different parts of their rotation upon the rotatable head they are utilized for different sensing purposes. Thus, in a preferred embodiment, within a part of rotation of a predetermined angle on either side of the line of movement of the sheet of material, sensors may be used to detect interior imperfections, whilst in other parts of their rotation they may employed to measure the sheet thickness. In a particular embodiment in arcs extending for 45.degree.
REFERENCES:
patent: 3431774 (1969-03-01), Dory et al.
patent: 4131026 (1978-12-01), Ries et al.
patent: 4170145 (1979-10-01), Kennedy et al.
patent: 4290309 (1981-09-01), Charlebois et al.
patent: 5237874 (1993-08-01), Latimer et al.
British Steel PLC
Chilcot Richard
Felber Joseph L.
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