RU1793365C - Method of determining ultrasonic transducer input angle - Google Patents

Description

The invention is intended for use in ultrasonic testing of materials, products and welded joints in mechanical engineering, energy, aviation, transport and other industries in the manufacturing processes, manufacturing, operational, output, in (one control, as well as inspection of metal structures and structures of other materials during their operational inspection to confirm the reliability and safety of further operation.

Known methods for determining the angle of entry of the ultrasonic transducer, which consists in first determining the entry point on the working surface of the transducer by finding the maximum signal from the curved surface of the segment using a sample that is a continuous connection of the box with a cylindrical hole and a 90-degree segment, which is an analog of the proposed solution, or a curved surface, using a sample in the form of a hemisphere or

VI |

SL X SL

half-disk selected as a prototype. Then, moving the converter in the first case along the working surface of the same sample, and in the second case, in the form of a parallelepiped with a cylindrical hole, the axis of which is parallel to the working face, the maximum signal from the hole surface is obtained and the input angle is determined by the trigonometric ratio of the sides of the triangle connecting the radiating center of the working surface of the transducer, the center of the cylindrical hole and the projection of the latter on the working surface of the sample .. ......

A disadvantage of these methods is the low accuracy of setting the angle of entry. This is due to the fact that, on the basis of the mentioned trigonometric relations (for example, the cathetus hypotenuse of the triangle), a scale of angles is plotted on the working surface of the sample, and, under the conditions of the transducer placement on the working face of the sample (in the middle of the sample width), there is a significant reference parallax - the first sight of the VOMKM input and the mark. angle scales on the lateral face of the sample. It increases the error of the inconvenience of performing such a reference (it is necessary to simultaneously monitor the flaw detector screen to find the maximum signal amplitude, manually move the transducer along the sample, determine the coordinate of the transducer on the eye by eye, etc.). In addition, the exit exit point itself is set inaccurately by first applying it to the transducer, since there is an inaccuracy in determining the location of the beam exit point on the converter, since only one projection of the beam exit point can be plotted from the used sample {accurate to the canopy; the width of the transducer in a reciprocating frequency;

The purpose of the invention is to increase accuracy, simplify and accelerate measurements.

For this purpose, a method for determining the angle of entry of an ultrasonic transducer is to move the transducer along the flat working face of the first sample, having the shape of a hemisphere or half disk, to obtain the maximum signal from the curved surface of the sample, then along the working surface of the second sample having the shape of a parallelepiped with a cylindrical hole, the axis of which is parallel to pa

side, before receiving the maximum signal from the surface of the hole, and the input angle is determined by the trigonometric aspect ratio of the triangle connecting the emitting center of the working surface of the transducer, the time of arrival of the maximum signals from the curved surface of the first sample and from the hole of the second sample is additionally measured, and the angle input is determined from the formula

Arccos {H / cl / 2 + c2 (T2 - Ti + 2 Ј-),

C1

5

0

5

0

5

0

5

0

5

where n is the radius of the curved surface of the first sample;

d is the diameter of the hole in the second sample;

C1, C2 are the speed of sound in the first and second samples, respectively;

Ti, T2 — arrival time of the maximum signal, respectively, in the first and second samples;

H is the distance to the axis of the hole from the working surface of the second sample.

The method is illustrated in FIG. 1 and 2.

Fig. 1 shows schematically a sample in the form of a hemisphere 1 with a flat diametrical surface 2, a curved (sphere or cylinder) surface 3, a center mark 4. A flaw detector transducer 5 (not shown) (not shown), an ultrasonic beam b is installed on it (through a layer of contact lubricant) introduced at an angle a to normal 7, reflected from surface 3, returned to transducer 5, converted to a signal observed on a flaw detector (not shown). The maximum signal, as you know, corresponds to the correct placement of the transducer 5 on the surface 2, when the input point of the transducer (beam exit point) coincides with the mark 4, while the signal arrival time according to (Fig. 1) is

Ti, (1)

where n is the radius of the surface 3; ci is the ultrasound velocity in the sample material (in which the wave travels along path 6 in both directions), T0 is the delay time of the ultrasound in the transducer (and the signal in the electronic path of the device).

It is important that in order to measure time, it is not necessary to mark the converter to indicate the point of entry (beam exit) on it. Through the use of a hemispherical sample, the most precise alignment of the entry point with the center 4 is established and Ti is measured. Then measurements are taken on the second sample.

In FIG. 2 shows a sample 1 with an opening 2 and a working surface 3, a transducer 4 moving along the working surface 3, and to the maximum echo position from the surface of the hole 2 observed on a flaw detector (not shown). according to the drawing (the beam is marked with the number 5) we have the equation of the signal arrival time

T2

That + 2 I,

C2

(2)

where Г2 is the distance along the ray 5 from the input point to | hole surface 2; C2 is the ultrasound velocity in the sample material and the equation of the triangle formed by the leg N (depth from the surface 3 to the axis of the hole 2), the hypotenuse length (Г2 + d / 2), where d is the diameter of the hole, and the leg X of the projection of this hypotenuse onto the surface 3 will be (r2; + d / 2) cos and N. (3) From (1) we get that

Unknown To Ti - 2 - (4)

From | (1) and (2), excluding by subtracting the time That, have

 G2 PS2 / C1 + C2 (T2 - Tl) / 2

 c2 (T2 - TO / 2. (5) From | (3) and (5) we obtain the desired dependence

cos + c2 (T2-To) / 2 + PS2 / C1 + c2 (T2 - TO / 2. (6)

FORMULA AND SECTION

A method for determining the angle of entry of an ultrasonic transducer, which is that I move the transducer along the flat working face of the first sample, having the shape of a hemisphere or half-disk, to obtain the maximum signal from the curve of the curved surface of the sample, then move the transducer along the working surface of the second sample, having the shape of a parallelepiped with a cylindrical with an aperture, whose axis is parallel to the working face, to obtain the maximum signal a from the surface of the products, and the input angle is determined by the trigo the numerical relationship {| the sides of the triangle connecting the radiating center of the working surface of the transducer, characterized in that, in order to improve accuracy, simplify and accelerate the measurement

5

0

5

0

from which automatically follows the expression indicated in the subject invention for this new method.

The method was checked using the transducer complete with a UD2-12 flaw detector, which allows measuring time using a digital readout chalice with a dividing price of 10 μs of СОа and СОЗ samples according to GOST 14782-87. For the transducers from the flaw detector kit, when determining the input angles, they received:

a) according to the method of GOST 14782-86 39.51.72 ° with an error of plus - minus 1 °,

b) by the proposed method: 40 °, 50 °, 30, 70 °, 40 with an accuracy of 0.5 °.

In this case, dependence (5) was used in the form of a graph or calculation using a pocket calculator MK-61. The determination time was reduced by about 2 times with increased accuracy and convenience of operations for determining the input angle due to the fact that it is not necessary to mark the input point on the converter, as well as to read the angle on the scale of sample CO2. There is also no need to apply a scale of angles to the CO2 sample. In order to achieve the greatest accuracy of the method, the time Ti and T2 should be measured for equal signal amplitudes (on the screen of the flaw detector). For this, the amplitudes are equalized by the attenuator at the input of the flaw detector.

SRI / additionally measure the time of arrival of the maximum signals of the curved surface of the first sample and from the hole of the second sample, and the input angle D is determined from the formula:

and arccos (H / d / 2 + ca-Og - Ti + 2 Ј-),

C1

where n is the radius of the curved surface of the first sample;

d is the diameter of the hole in the second sample;

d, C2 — sound velocities respectively in the first and second samples;

Ti. T2 is the arrival time of the maximum signal, respectively, in the first and second samples;

H is the distance to the axis of the hole from the working surface of the second sample.

FIG. 1

FIG. 2