FIELD OF INVENTION
The present invention relates to a non destructive testing method to predict / assess torsion value
in tyre bead wires by electromagnetic sorting technique. More particularly the invention relates to
segregate the torsion value from low to high in the tyre bead wires by electromagnetic sorting
technique for reducing the rejection due to abnormal properties of the tyre bead wires.
BACKGROUND OF THE INVENTION
Tyre bead wires (TB) are used in all types of pneumatic tyres such as motorcycles, cars, buses
trucks etc. It imparts anchorage to the tyre with wheel-rim. Torsional ductility is one of the
important property of TB wires. Presently, the torsion value is being assessed by torsion testing as
per ASTM-D 4975-04, which is destructive one. The torsion test is a useful tool in assessing wire
ductility under torsional loading. Defective wire lowers torsion resistance (Torsion resistance is
expressed as the value of full rotational turns of the wire to fracture). If the torsion value could be

predicted or assessed by non destructive technique (electromagnetic testing) then it would be
quicker as well as less costly. In addition to that, the quality of the wire for certain length can be
assessed without impairing the tyre bead wires.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a non destructive testing method to predict /
assess torsion value in tyre bead wires by electromagnetic sorting technique which is capable of
reducing the rejection due to abnormal properties of the tyre bead wires.
Another object of the invention is to propose a non destructive testing method to predict / assess
torsion value in tyre bead wires by electromagnetic sorting technique which ensures a maximum
length of wires inspection for better customer satisfaction.
A further object of the invention is to propose a non destructive testing method to predict / assess
torsion value in tyre bead wires by electromagnetic sorting technique which ensures the consistent
property of the tyre bead wires at the customer end so that the reliability of these wires can be
improved during its service.

SUMMARY OF THE INVENTION
In this invention, the torsion value for tyre bead wire is indirectly predicted / assessed using
electromagnetic sorting principle. The high and low torsion wires can be segregated well through
this technique. The work carried out so far, showed that the segregation pattern of the high and
low torsion values can be differentiated easily.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be described in detail with the help of the figures of the accompanying
drawings in which:
Figure 1 shows a graphical representation for coil no. 1 having torsion
value varied from 65 to 67 for the present invention.
Figure 2 shows a graphical representation for coil no. 2 having
torsion value varied from 66 to 70.
Figure 3 shows a graphical representation for coil no. 3
having torsion value varied from 74 to 78.
Figure 4 shows a graphical representation for coil no. 4 having torsion value less than 56.
Figure 5 shows pattern no. 1 for low and high torsion values.
Figure 6 shows pattern no. 2 for low and high torsion values.

DETAILED DESCRIPTION OF A PREFERRED
EMBODIMENT OF THE INVENTION
Electromagnetic sorting technique (ASTM E 566) is a known and existing process. The present
invention uses this technique to find an innovative way to predict / assess torsion value in tyre bead
(TB) wires.
Conventionally the torsion resistance value is normally found using torsion testing machine which is
destructive. In the present invention this torsion resistance value is found out by eddy current.
Samples of tyre bead wires of 0.965 mm is collected from different coils with same chemistry.
The chemical composition of tyre bead wires is as given below,

Initially TB wire were sorted by eddy current tester (Technofour) at 5 KHz frequency with two
encircling coils with inside diameter of 2 mm. The same were destructively tested in torsion testing
for getting torsion values as per ASTM-D 4975-04 which stands for a standard test methods for
single filament tyre bead wire made from steel.

For a given frequency and for part with identically geometry, the only variables that will affect the
flow of eddy current are the electrical conductivity and the magnetic permeability. When the
instrument is balanced with identical components in reference coil and test coil, the impedance of
the test coil will change depending upon these two attributes of the test components.
Electromagnetic sorting principle
This electromagnetic sorting method is basically comparison between wires. The total opposition to
alternating current flow is called impedance (Z). For a given coil the impedance is calculated by
vector addition of resistance and inductive resistance and is given by

The comparative coil method consists of two similar encircling coils. Two reference specimens
which were (known torsion value) kept inside of the each coil. After that the balancing of
instrument is done. One of the specimen from the encircling coil is taken out and unknown torsion
value specimen is inserted into that. The change in impedance due to this is indicated by graphical
representation.
The value of x and y was noted for each specimen.
Torsion test is also carried out on each specimen after electromagnetic sorting.

Whenever electrical conductivity and / or magnetic permeability of test component change, it
results in change of impedance of test coils. This affects balancing of system resulting in change of
voltage, which are represented in the form of x and y. X and Y represents the difference in
impedance of two coils.
Experiment
The four different coils of tyre bead wires are collected and several specimens from each coil whose
length is equal to 300 mm are made. The initial calibration is done for coil no. 1 by placing
specimen in each encircling coil. The balancing of the instrument is carried out. The point is
shown zero position in the graphical display. After balancing, the one of the known specimen is
replaced by unknown specimen. The shift in point for different specimen is measured with varying
torsion values. The shifting of the point from balancing is mainly depending on the chemistry,
microstructure, internal stresses, strain aging and inclusions of the unknown specimen. Afterwards,
the torsion testing is carried out for all the specimens of coil no. 1. The same procedure is
repeated for coil no. 2, 3 and 4 including the initial calibration. The figures 1, 2, 3 and 4 shows
different pattern for the different coils. It is observed that we could able to segregate the high
torsion values from the low torsion values in a good manner.
A standard graph is then prepared of change in impedance in terms of point representation. Now
the point with respect to high and low torsion values is compared. The size of the wire samples
taken for experiment is of 0.965 mm.

WE CLAIM
1. A non destructive testing method to predict / assess torsion value in tyre bead wires by
electromagnetic sorting technique comprising:
- collecting a plurality of different coils of tyre bead wires;
making a plurality of specimens from each coil, the said specimen being of a predetermined
length;
- collecting samples of tyre bead wires having known torsion values;
making initial calibration for coil no. 1 by placing specimen in each encircling coil;
- balancing the instrument;
replacing one of the known specimen by unknown specimen;
marking the shifting of the point from, balancing;
characterized in that,
- the torsion testing is carried out for all the specimens of coil no. 1 and the procedure is
repeated for the remaining coils including the initial calibration, when the shift in point for
different specimens with varying torsion values are measured and a plurality of graphs with
different pattern for the different coils are plotted with change in impedance in terms of
point representation wherein wires of high torsion value is segregated from wires of low
torsion value.

2. The method as claimed in claim 1, wherein wire samples of the experiment are of 0.965
mm.
3. The method as claimed in claim 1, wherein the experiment is carried out with four samples
of coil.
4. The method as claimed in claim 1, wherein the lengths of the specimen are of equal length
of 300 mm.

The present invention relates to a non destructive testing method to predict / assess torsion value in tyre bead wires by electromagnetic sorting technique and comprises of collecting a plurality of different coils of tyre bead wires and making a plurality of specimens from each coil, the said specimen being of a predetermined length. Then samples of tyre bead wires with known torsion values are collected. The instrument is then balanced and one known specimen is then replaced by the unknown specimen. When the shifting of the point from balancing is marked. The torsion testing is then carried out for all the specimen of coil no. 1 and the procedure is repeated for the remaining coils including the initial calibration. The shift in point for different specimen with varying torsion values are marked and a plurality of graphs with different pattern for the different coils are plotted with change in impedance in terms of point representation wherein wires of high torsion value is segregated from wires of low torsion value.