FIELD OF THE INVENTION
The present invention relates to fabrication of a device and the process of fabrication with
strain gauge being used as a sensor for recording the angular dynamic movement data of
web plate in welded T joints. During fabrication by welding such angular dynamic
movement data allow to estimate the distortion pattern of web plate of welded T joints.
More particularly, the invention relates to a device for on-line recording of dynamic
movement of a web plate during welding process of a T-joint.
BACKGROUND OF THE INVENTION
Distortion is a perennial problem in engineering applications involving welding as a
method of fabrication. The distortion encountered may lead to many undesirable
situations; particularly the angular distortion experienced by the web plate in case of
welded T joints. The angular distortion is the type of distortion that occurs perpendicular
to the weld axis. It is known that distortion cannot be eliminated but only can be
minimized. Once distortion has occurred, it is a common practice that correction of the
distortion either mechanically or thermally be adopted. There are many methods for
controlling distortion. If the pattern of distortion could be known prior to commencing the
welding, then it would be easy to apply a suitable technique to control the distortion. A
welded T joint normally consists of a horizontal plate over which another vertical plate is
welded with one or more fillet welds. After welding, the measurement of distortion is made
by using a tangent of an angle which is calculated from the height of the web plate and
horizontal displacement undergone by the web plate. Based on the distortion as
measured, a decision on correction, or rejection or acceptance is taken.
US 7441470 describes a method for measuring multi-axial force, moment, force and
acceleration with a strain gauge used as a sensor. US 7434475 describes a method of
forming a strain sensor from a polymeric film which includes the steps of selectively
irradiating a surface of the polymer with high energy radiation to change the composition
of the polymer and increase the electrical conductivity in selected portions of the
surface. US 7395727 describes a method of strain detection for automated nano-
manipulation with detection circuitry. US 7392711 discloses an invention of insertable
strain gauge spanner which comprises a spanner body having a rod body and a driving
head insertable into the rod body; the rod body being installed with a strain gauge, so that
the twisting force from the driving head can be transferred to a sensing end of the strain
gauge; the twisting force being displayed in a window of the strain gauge. US 7357037
discloses an invention that provides a system for measuring and remotely monitoring
strain in an element having a strain sensor, a telemetry circuit for transmitting strain data
to a remote location, and a reader module for transmitting energy to the telemetry circuit
and receiving said data.
US7347101 describes an invention that deals with measurement of strain in a structure
using a sensor having an electromagnetic resonator.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a device for on-line recording of
dynamic movement of a web plate during welding process of a T joint to generate angular
distortion pattern of the joint.
SUMMARY OF THE INVENTION
According to the invention, there is provided a device consisting of at least two
components used for recording the angular dynamic movement of the web plate during
welding of a T joint.
The first component is a support means consisting of two vertical tubes resting on a first
pair of block that are having holes to adjustably accommodate the tubes. Bolts are
provided in the first pair of square block for tightening and firmly securing the tubes
substantially in vertical position. On top of these two tubes, each of a square block of a
second pair of square block is mounted. The top mounted second pair of square block
each has holes drilled out so as to insert a horizontal rod through them.
The second component is a rod member which is a horizontal member that is inserted
through the holes provided in the top blocks, that is the second pair of square block
mounted on the two tubes. Two sliding collets are mounted on the rod member. At least
two steel strips are' connected to these two sliding collets. Two strain gauges are mounted
one each on the steel strips. Theses two strain gauges are connected to a strain meter in
order to record the strain readings. In addition to a strain gauge, each of these steel strips
has in them a welded stylus pin which always remains in contact with the web plate. Prior
to employing the device so formed, on the Tee joint, a calibration of the mechanical
parameters for example, the microstrains and the distortion in mm is carried out. A
correlation graph between the strain and the distortion values is drawn through the
calibration. During welding, the stylus pin is made to contact the web plate of the T joint.
During fabrication by welding, the web plate undergoes an angular distortion because of
the shrinkage forces acting in those areas where the weld gets cooled. The stylus pin is
so set that it always remains in contact with the web plate irrespective of whether the web
plate moves towards the stylus pin or away from it. This is achieved by suitably setting the
stylus pin against the web plate with a pre-tension. Since the stylus pin is in contact with
the web plate, it also bends and gets strained along with the web plate. This strain is
sensed by the strain gauge attached to it and the data is transmitted to the strain meter
for recording. The movement of the stylus pin vis-vis the web plate is a continuous
process and hence the transient angular distortion of the web plate in terms of strains is
recorded and is subsequently converted into distortion values using the calibration graph.
From the trend of the distortion, a decision on the technique to be employed to minimize
distortion is taken.
According to the invention, a device is fabricated and a strain gauge is used as a sensor,
which is installed on the device and the system as whole is used to measure on-line
dynamic angular distortion experienced by a web plate in case of welded T joints.
According to another aspect of the present invention, the strain gauge is installed on a
steel strip and the strip is mounted on the device and the assembly is used for
measurement of angular distortion of web plate during welding a T joint. The strain value
is first measured which is converted into distortion.
According to a still, another aspect of the invention, the strain gauge with the device used
for measurement of a mechanical parameter, namely the mechanical distortion, and the
measurement is taken adjacent to the weld component and the measurement is dynamic.
BREIF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The proposed invention will be better understood by the following description with
reference to the accompanying drawings:
Figure 1 shows a supporting means of the inventive device, consisting of two
tubes
Figure 2 A rod with sliding collets with steel strips containing strain gauge of the
Inventive device.
Figure 3 A schematic view of the device of the invention with the components of
Figures 1 & 2.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
As shown in figure-1, the support means consists of two identical tubes (3) that are
separated by a predetermined distance based on the length of a web plate of the T joint.
These two tubes rest on a first pair of square block (1) that have holes drilled in them in
order to accommodate the tubes. The tubes (3) are placed on the first pair of square
block (1) and firmly secured by using at least one first bolt (2). On top of each of the two
tubes (3) is placed a second pair of square block (4) that has a hole to accommodate
tubes (3). This second pair of square block (4) in addition to having a hole with axis in the
vertical direction also has a hole with axis in horizontal direction and both these axes are
perpendicular to each other.
As shown in fig-2, a member rod (10) is inserted through the horizontal holes of the
second pair of square block (4) resting on top of the two tubes (3). Two sliding collets (5)
are mounted on the rod (10). These two sliding collets (5) each has a diameter higher
than the diameter of the rod (10) and they can slide through the entire length of the rod
(10). These collets can be positioned anywhere in the rod (10) by using at least one
second bolt (6). To each of these sliding collets (5) is attached a steel strip (7) that
contains a strain gauge (8) that is used a sensor and a stylus pin (9) which always
remains in contact with the web plate of the T joint being welded. The strain gauge (8) is
connected to a stain meter (not shown) to record the strain values which are later
converted into distortion values by a calibration method. The device is calibrated by giving
a known distortion and the corresponding strains are recorded. A correlation between the
strain and the distortion is drawn through the calibration. During welding of the T joint, the
web plate undergoes an angular movement because of distortion and the distortion is
sensed by the strain gauge (8) in terms of strains.
The proposed invention as described herein above should not be read and construed in a
restrictive manner, as many modifications, adaptations and alterations are possible within
the scope and limit of the invention as herein disclosed.
WE CLAIM:
1. A device for on-line recording of dynamic movement of a web plate during welding
process of a T-joint; comprising:
- supporting means comprising at least two tubes (3) adjustably disposable at spaced-
apart relationship so as to accommodate a web plate of T-joint; a first pair of square block
(1) each having holes corresponding to the diameter of the tubes (3), and accommodating
one each tube (3) from the bottom portion; a second pair of square block (4);each of
second pair of square block (4) supporting one of the two tubes from the top portion, the
second pair of square block (4) each having a plurality of holes with axes in horizontal
and vertical direction as well;
- a rod member (10) having at least two sliding collets (5) with diameter higher than that of
the rod member (10) enabling sliding of the collets (5) along the length of the rod
member (10), the sliding collets (5) each attached to a steel strip (7) having a detachably
attached strain gauge (8) including a flexible stylus pin (9), the rod member (10) being
inserted through the second pair of square block (4) so as to rest on top portion of said
two tubes (3), wherein, the strain gauge acts as a sensor being operably connected to a
strain meter, the flexible stylus pin (9) set with a pre-tension remaining in a constant
contact mode with the web plate of the T-joint, wherein when the web-plate in the process
of welding undergoes angular distortion due to the shrinkage force acting on weld areas
getting cooled, the stylus pin (9) sustaining corresponding strain being in contact with the
web plate and being bent, and wherein the strain gauge is enabled to sense the strain
and transmit the sensed data to the strain meter for recording which being converted into
distortion value through a pre-calibrated graph.
2. A device for on-line recording of dynamic movement of a web plate during welding
process of a T-joint as substantially described and illustrated herein with reference to the
accompanying drawings.

The present invention relates to a device for on-line recording of dynamic movement of a
web plate during welding process of a T-joint; comprising -supporting means comprising
at least two tubes (3) adjustably disposable at spaced-apart relationship so as to
accommodate a web plate of T-joint; a first pair of square block (1) each having holes
corresponding to the diameter of the tubes (3), and accommodating one each tube (3)
from the bottom portion; a second pair of square block (4);each of second pair of square
block (4) each supporting one of the two tubes from the top portion, the second pair of
square block (4) each having a plurality of holes with axes in horizontal and vertical
direction as well; a rod member (10) having at least two sliding collets (5) with diameter
higher than that of the rod member (10) enabling sliding of the collets (5) along the length
of the rod member (10), the sliding collets (5) each attached to a steel strip (7) having a
detachably attached strain gauge (8) including a flexible stylus pin (9), the rod member
(10) being inserted through the second pair of square block (4) so as to rest on top
portion of said two tubes (3), wherein, the strain gauge acts as a sensor being operably
connected to a strain meter, the flexible stylus pin (9) set with a pre-tension remaining in a
constant contact mode with the web plate of the T-joint, wherein when the web-plate in
the process of welding undergoes angular distortion due to the shrinkage force acting on
weld areas getting cooled, the stylus pin (9) sustaining corresponding strain being in
contact with the web plate and being bent, and wherein the strain gauge is enabled to
sense the strain and transmit the sensed data to the strain meter for recording which being converted into distortion value through a pre-calibrated graph.