Method for excitation and reception of ultrasonic plate waves in workpieces and devices for realizing same

Claim 1

A method of excitation and reception of ultrasonic plate waves in a workpiece comprising generating a high-frequency electromagnetic field acting on the surface of the workpiece by a transducer consisting of a system of flat radiators forming a comb-like structure positioned discretely in the direction of radiation with a pitch divisible by the wavelength; applying a magnetizing field to the workpiece whose vector is parallel to the surface of the workpiece in the area of the high-frequency electromagnetic field, and orienting the vector of the magnetizing field for exciting transverse (shear) plate waves with respect to the transducer of flat radiators at an angle α relative to the direction of radiation, wherein |α| > 0.

Claim 2

A method of excitation and reception of ultrasonic plate waves in a workpiece comprising generating a high-frequency electromagnetic field acting on the surface of the workpiece by a transducer consisting of a system of flat radiators forming a comb-like structure positioned discretely in the direction of radiation with a pitch divisible by the wavelength; applying a magnetizing field to the workpiece whose vector is parallel to the surface of the workpiece in the area of the high-frequency electromagnetic field, and orienting the vector of the magnetizing field for exciting transverse (shear) plate waves with respect to the transducer of flat radiators at an angle α relative to the direction of radiation, wherein |α| > 0.

Claim 6

A method of excitation and reception of ultrasonic plate waves in a workpiece comprising generating a high-frequency electromagnetic field acting on the surface of the workpiece by a transducer consisting of a system of flat radiators forming a comb-like structure and positioned discretely in the direction of radiation with a pitch divisible by the wavelength; applying a magnetizing field to the workpiece whose vector is parallel to the surface of the test workpiece in the area of the high-frequency electromagnetic field; orienting the vector of the magnetizing field for exciting transverse (shear) plate waves with respect to the transducer of flat radiators at an angle α relative to the direction of radiation, and exciting longitudinal plate waves for simultaneous excitation and reception of pulses of transverse and longitudinal plate waves by selecting at least two excitation frequencies of the high-frequency electromagnetic field wherein the wavelengths of the transverse and longitudinal plate waves are equal according to the formula f.sub.1 = c.sub.x1 /λ.sub.1 ; f.sub.2 = c.sub.x2 /λ.sub.2 where c x1 and c x2 are phase velocities of transverse and longitudinal plate waves, respectively, and λ 1 and λ 2 are the lengths of transverse and longitudinal plate waves, respectively, the pitch between the flat radiators being determined according to the formula t = λ.sub.1 = λ.sub.2.

Claim 7

A method of excitation and reception of ultrasonic plate waves in a workpiece comprising generating a high-frequency electromagnetic field acting on the surface of the workpiece by a transducer consisting of a system of flat radiators forming a comb-like structure and positioned discretely in the direction of radiation with a pitch divisible by the wavelength; applying a magnetizing field to the workpiece whose vector is parallel to the surface of the test workpiece in the area of the high-frequency electromagnetic field; orienting the vector of the magnetizing field for exciting transverse (shear) plate waves with respect to the transducer of flat radiators at an angle α relative to the direction of radiation, and exciting longitudinal plate waves for simultaneous excitation and reception of pulses of transverse and longitudinal plate waves by selecting at least two excitation frequencies of the high-frequency electromagnetic field wherein the wavelengths of the transverse and longitudinal plate waves are equal according to the formula f.sub.1 = c.sub.x1 /λ.sub.1 ; f.sub.2 = c.sub.x2 /λ.sub.2 where c x1 and c x2 are phase velocities of transverse and longitudinal plate waves, respectively, and λ 1 and λ 2 are the lengths of transverse and longitudinal plate waves, respectively, the pitch between the flat radiators being determined according to the formula t = λ.sub.1 = λ.sub.2.

Claim 13

A device for excitation and reception of ultrasonic plate waves in workpieces, e.g. in sheets, comprising: a foundation; a magnetizing device mounted on said foundation so that it can turn in a plane parallel to the surface of the workpiece; a bracket secured on said foundation so that the workpiece is between said foundation and said magnetizing device, a lever mechanism with a lifting means connecting said bracket to said foundation; a frame secured to said lever mechanism; lever means secured on said frame; a system of flat radiators constituting a high-frequency transducer secured on said bracket by means of said lever means and pressed against the workpiece by said lever means; said high-frequency transducer being positioned coaxially with said magnetizing device; a protective device enveloping said high-frequency transducer and placed on said frame; said protective device including at least two rollers mounted in one plane and having parallel axles with an elastic electrically strong and mechanically durable ring band secured thereon and moving at the speed of the workpiece, and a layer of material covering a portion of said rollers, which is in contact with the workpiece, said layer of material ensuring reliable coupling of said rollers with the surface of the workpiece.

Claim 14

A device for excitation and reception of ultrasonic plate waves in workpieces, e.g. in sheets, comprising: a foundation; a magnetizing device mounted on said foundation so that it can turn in a plane parallel to the surface of the workpiece; a bracket secured on said foundation so that the workpiece is between said foundation and said magnetizing device, a lever mechanism with a lifting means connecting said bracket to said foundation; a frame secured to said lever mechanism; lever means secured on said frame; a system of flat radiators constituting a high-frequency transducer secured on said bracket by means of said lever means and pressed against the workpiece by said lever means; said high-frequency transducer being positioned coaxially with said magnetizing device; a protective device enveloping said high-frequency transducer and placed on said frame; said protective device including at least two rollers mounted in one plane and having parallel axles with an elastic electrically strong and mechanically durable ring band secured thereon and moving at the speed of the workpiece, and a layer of material covering a portion of said rollers, which is in contact with the workpiece, said layer of material ensuring reliable coupling of said rollers with the surface of the workpiece.

Claim 16

A device for excitation and reception of ultrasonic plate waves in workpieces (e.g. in sheets) comprising: two guides positioned along a workpiece; a platform, which is able to move with respect to the workpiece and is placed on one of said guides; a bracket mounted on said one guide and having a respective guide placed across the test workpiece and resting on said other guide placed along the workpiece; a carriage with a drive means, which is positioned on said guide of said bracket; an electric drive means mounted on said carriage; a magnetizing device with a lifting device means and a lever securing the lifting drive means on said carriage; lever means positioned on said magnetizing device; a high-frequency transducer mounted on said magnetizing device by said lever means so that the transducer can turn about an axis normal to the surface of the workpiece; said high-frequency transducer being pressed against the surface of the workpiece by said lever means; at least two welded seam position sensors mechanically connected to said high-frequency transducer; at least two electromagnetic holder means mechanically connected to said high-frequency transducer; said welded seam position sensors and said electromagnetic holder means being positioned in pairs over the edges of the workpiece for ensuring travelling of the platform with the workpiece and travelling of the high-frequency transducer along the workpiece welded seam under test by said electric drive means.

Claim 17

A device for excitation and reception of ultrasonic plate waves in workpieces (e.g. in sheets) comprising: two guides positioned along a workpiece; a platform, which is able to move with respect to the workpiece and is placed on one of said guides; a bracket mounted on said one guide and having a respective guide placed across the test workpiece and resting on said other guide placed along the workpiece; a carriage with a drive means, which is positioned on said guide of said bracket; an electric drive means mounted on said carriage; a magnetizing device with a lifting device means and a lever securing the lifting drive means on said carriage; lever means positioned on said magnetizing device; a high-frequency transducer mounted on said magnetizing device by said lever means so that the transducer can turn about an axis normal to the surface of the workpiece; said high-frequency transducer being pressed against the surface of the workpiece by said lever means; at least two welded seam position sensors mechanically connected to said high-frequency transducer; at least two electromagnetic holder means mechanically connected to said high-frequency transducer; said welded seam position sensors and said electromagnetic holder means being positioned in pairs over the edges of the workpiece for ensuring travelling of the platform with the workpiece and travelling of the high-frequency transducer along the workpiece welded seam under test by said electric drive means.

Claim 19

A device for excitation and reception of normal waves in workpieces, e.g. pipes, comprising: a vertical guide bearing with a screw drive; a movable bracket mounted on said vertical guide bearing and able to move therealong; lever means including a lifting drive secured on said movable bracket; guiding rollers in contact with the workpiece; a magnetizing device mounted on said guiding rollers and secured by the lever means on said movable bracket; said magnetizing device being constituted as a sectionalized S-shaped magnetic circuit including at least three pole shoes with a stationary central pole shoe which is interchangeable, and two other adjustable pole shoes assembled of plates oriented with respect to the axis of the test workpiece, means for moving said plates along the S-shaped magnetic circuit including screw pairs and an adjusting and fixing means to assume the shape of the surface of the workpiece under test; at least two high-frequency transducers permanently pressed against the surface of the workpiece and able to move on said magnetizing device; said high-frequency transducers being positioned symmetrically with respect to the longitudinal axis of said S-shaped magnetic circuit, and means for moving said high frequency transducers along said S-shaped magnetic circuit including screw pairs secured so that the transducers can rotate about a vertical axis in a plane parallel to the surface of the workpiece.

Claim 20

A device for excitation and reception of normal waves in workpieces, e.g. pipes, comprising: a vertical guide bearing with a screw drive; a movable bracket mounted on said vertical guide bearing and able to move therealong; lever means including a lifting drive secured on said movable bracket; guiding rollers in contact with the workpiece; a magnetizing device mounted on said guiding rollers and secured by the lever means on said movable bracket; said magnetizing device being constituted as a sectionalized S-shaped magnetic circuit including at least three pole shoes with a stationary central pole shoe which is interchangeable, and two other adjustable pole shoes assembled of plates oriented with respect to the axis of the test workpiece, means for moving said plates along the S-shaped magnetic circuit including screw pairs and an adjusting and fixing means to assume the shape of the surface of the workpiece under test; at least two high-frequency transducers permanently pressed against the surface of the workpiece and able to move on said magnetizing device; said high-frequency transducers being positioned symmetrically with respect to the longitudinal axis of said S-shaped magnetic circuit, and means for moving said high frequency transducers along said S-shaped magnetic circuit including screw pairs secured so that the transducers can rotate about a vertical axis in a plane parallel to the surface of the workpiece.

Claim 23

A device for excitation and reception of plate waves in workpieces, comprising: a magnetizing device constituted as a sectionalized magnetic circuit with two pole shoes travelling individually across and along the workpiece; means including screw drives for displacing said pole shoes along the workpiece and for fixing said shoes in definite positions; a bracket positioned on one of said pole shoes; a guide mounted in said bracket; a spring-loaded lever means mounted on said guide; a high-frequency transducer mounted on said lever means so that it can be moved along the workpiece and a frame supporting said transducer and including an elastic base assuming the shape of the workpiece surface when pressed thereto by said lever means.

Claim 24

A device for excitation and reception of plate waves in workpieces, comprising: a magnetizing device constituted as a sectionalized magnetic circuit with two pole shoes travelling individually across and along the workpiece; means including screw drives for displacing said pole shoes along the workpiece and for fixing said shoes in definite positions; a bracket positioned on one of said pole shoes; a guide mounted in said bracket; a spring-loaded lever means mounted on said guide; a high-frequency transducer mounted on said lever means so that it can be moved along the workpiece and a frame supporting said transducer and including an elastic base assuming the shape of the workpiece surface when pressed thereto by said lever means.

Claim 25

A device for excitation and reception of plate waves in workpieces, comprising: a magnetizing device with a hand drive; a high-frequency transducer mounted on said hand drive of the magnetizing device and provided with plate, a multi-link parallelogram mechanism with a separate drive installed on said plate; a discrete flat radiator constituted by a plurality of sections; L-shaped plates assembled as a pack, each of said L-shaped plates being hinged to respective links of the parallelogram mechanism and having remote ends, said flat sections of the radiator being mounted on the ends of the L-shaped plates.

Claim 26

A device for excitation and reception of plate waves in workpieces, comprising: a magnetizing device with a hand drive; a high-frequency transducer mounted on said hand drive of the magnetizing device and provided with plate, a multi-link parallelogram mechanism with a separate drive installed on said plate; a discrete flat radiator constituted by a plurality of sections; L-shaped plates assembled as a pack, each of said L-shaped plates being hinged to respective links of the parallelogram mechanism and having remote ends, said flat sections of the radiator being mounted on the ends of the L-shaped plates.