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FIELD OF APPLICATION
The present invention relates to an ultrasonic probe assembly for ultrasonic
testing using ultrasonic surface wave (Rayleigh / Lamb waves).
BACK GROUND OF THE INVENTION
Ultrasonic probes are used in the Held of non-destructive evaluation and
characterization of materials. The probes can be used for the evaluation of
mechanical properties and micro-structure of semi-finished, finished flat / forged
/ cast steel products. The probes can also be used for the evaluation of surface
as well as industrial components such as rolling mill rolls, shafts, pipes / tubes
etc.
In known ultrasonic probes where same transducer works as transmitter as well
as a received, some of the information about the condition of the test object may
be missing because of the presence of missing dead zone.
When two separate ultrasonic probes are used to produce and receive ultrasonic
surface waves (Rayleigh / Lamb waves) For measurement of time of flight (TOP)
of ultrasonic waves between them, the distance between the probes has to be
measured with the help of some measuring device each time for a set of
measurements.
In this process, there is a chance for error in measurement time of flight (TOF)
because even a very slight variation in the measurement of distance between the
probes can cause a huge error in time of Right (TOF) measurement. This
manual process for keeping the probes apart at a fixed and accurate distance
needed a lot of time and concentration. Also holding the probes with both the
hands was a unergonomical practice.

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ln order to avoid and prevent the errors in measurement of time of flight (TOF)
as well as saving the time in taking accurate and precise measurement of time of
flight (TOF), there was a need for a device / assembly which can be used
effectively and economically.
SUMMARY OF THE INVENTION
The main object of the present invention therefore, is to provide an ultrasonic
probe assembly using two separate transducers as transmitter and receiver
provided at a fixed distance for not only eliminating the dead zone, but also for
more accurately measuring the time of flight of ultrasonic waves from transmitter
to receiver. This time of flight (TOF) measured can be utilized for materials
characterization.
The probe assembly of the present invention can further be used for the
evaluation of surface, as well as internal flaws.
Thus the present invention provides an ultrasonic probe assembly comprising
two transducers used as a transmitter and a receiver, said transducers arranged
at a fixed distance from one another for measurement for time of flight (TOF) of
ultrasonic waves from the surface of a test piece.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be explained with the help of the figures of the drawing,
where
Figure 1 shows in a pictorial view the ultrasonic probe assembly of the
present invention.
Figure 2 schematically shows the plan, front and side views of the
ultrasonic probe assembly of Figure 1.

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DETAILED DESCRIPTION
Figure 1 is a photographic view showing the ultrasonic probe assembly of the
present invention in use for measurement of time of flight (TOP) of ultrasonic
surface waves (Rayleigh / Lamb waves),
Figure 2 shows the ultrasonic probe assembly 1 in plan, elevation and side views.
The assembly comprises a perspex sheet 2 having two rectangular holes for
receiving two transducers, one transmitter 3 and one receiver 4. The perspex
sheet 2 is chosen because it is transparent and light in weight. The perspex
sheet 2 can be of size 200 x 30 x 10 mm and the two holes of size 30 x 16 mm
each can be arranged at a fixed distance D of say 100 mm. These holes can be
placed 20 mm away from the two edges of the perspex sheet 2.
The two rectangular holes in the perspex sheet 2 for receiving two transducers
3, 4 are made slightly over size of the transducer size. The transducers 3, 4
used as ultrasonic surface wave probes can be of 4 M Hz frequency with crystal
size of 8 x 9 mm. The transducers 3, 4 are fitted with lemo connectors 5, 6 and
fixed to the perspex sheet 2 rigidly with adhesive. The sized of the ultrasonic
probe 3,4 can be 30 x 16 x 22 mm.
While fixing the ultrasonic probes 3, 4 on to the perspex sheet 2, care is to be
taken to see that the position of the plane of the perspex sheet 2 is parallel to
the contact surface of the test piece 7 and that distance d between the
transducers 3, 4 and the test piece 7 is about 2 mm. Care should also be taken
far convenient insertion of the lemo connecting cable to the ultrasonic probes.

The main object of the present invention therefore, is to provide an ultrasonic probe assembly using two separate transducers as transmitter and receiver provided at a fixed distance for not only eliminating the dead zone, but also for more accurately measuring the time of flight of ultrasonic waves from transmitter to receiver. This time of flight (TOF) measured can be utilized for materials characterization.
The probe assembly of the present invention can further be used for the evaluation of surface, as well as internal flaws.
Thus the present invention provides an ultrasonic probe assembly for ultrasonic testing, comprising: a pair of transducers, one a transmitter and the other a receiver, said transducers arranged on a perspex sheet at a fixed distance from one another for measurement of time of flight (TOF) of ultrasonic waves from the surface of a test piece.