FILED OF INVENTION
The invention relates to a testing apparatus for conducting destructive test on
seam welded sheets. More particularly, the invention relates to a device
mountable on standard testing system for conducting destructive test on seam
welded thin sheets.
BACKGROUND OF THE INVENTION
Butt welding of thin sheets which are welded by seam welding process is
employed widely in a variety of industries and notably in automobile industries.
The quality of such seam welds need to be assessed by destructive testing
before employing the welded component for production purposes. The IS
standard specifies some destructive tests for example Erichsen tests for
evaluating the quality of the seam welds. The Erishsen test is intended to
determine the ductility of the welded sheet and their ability to withstand a
bending operation. The test is generally conducted on a seam welded sheet
specimen of about 100mm long and the test comprises forcing a forming tool on
the specimen, which is supported at the bottom. The forming tool is forced into
the sheet till the entire tool is forced and the material is deformed to a shape of
a sphere without any cracking. The IS standard has recommended tool and
apparatus to conduct the test.

The forming tool and apparatus normally used for Erichsen test are required to
be adaptable to the known universal testing machine. Different tools with various
diameters must be made available for carrying out the test on sheets of varying
thickness from 1 mm to 5 mm.
However, a device for conducting the test on seam-welded then sheets is not
available in the art.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a device mountable on
standard testing system for conducting destructive test on seam welded thin
sheets, which eliminates the disadvantages of prior art.
Another object of the invention is to propose a device mountable on standard
testing system for conducting destructive test on seam welded thin sheets, the
forming tool of the device being mountable on the standard testing system.
A further object of the invention is to propose a device mountable on standard
testing system for conducting destructive test on seam welded thin sheets, the
apparatus of the device being capable to hold a specimen during destructive test.
These and other objects and advantages of the invention will be apparent from
the ensuing description.

SUMMARY OF THE INVENTION
Accordingly, there is provided a device for conducting destructive testing of seam
welded sheets of thickness of 5.00 mm, comprising:
- a set of forming tools (4) mountable on a standard testing system (1); and
- an apparatus having a top plate comprising a central hole (2) and a bottom
plate (3) comprising a central conical hole for housing the seam welded thin
sheet (5).
At the outset of the description, which follows, it is to be understood that the
ensuring description only illustrates a particular form of this invention. However,
such a particular form is only an exemplary embodiment and the teaching of the
invention is not intended to be taken restrictively.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 shows an embodiment of the device for conducting destructive testing
of seam welded thin sheets according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in figure-1, the device comprises at least one forming tool (4) to be

selected from set of tools depending upon thickness of the sheet, and an
apparatus. The forming tool (4) is inserted into a compression disc (1) of a
standard testing system. The seam welded sheet (5) to be tested is enclosed
within a top plate (2) and a bottom plate (3) of the apparatus, and tightened by
bolts and nuts. The top plate (2) has a cylindrical hole, which is slightly higher
than the diameter of the forming tool (4) whereas the bottom plate (3) has a
conical hole, which enables an easy removal of the tested specimen. Slots are
also provided in the top plate (2) and bottom plate (3) to enable correct location
of the weld at the center of the apparatus. The apparatus is kept over the base
of the standard testing system (1) directly under the forming tool (4). During
testing, the forming tool (4) is lowered and forced till the sheet is formed to a
shape of a hemi sphere without developing any crack. If any crack is observed,
the test is stopped and the seam welded sheet is removed from the apparatus. If
the specimen (5) is able to withstand the test without developing any crack, then
the test is continued and the specimen (5) is deformed further forcing the
forming tool (4) into the sheet (5). The correct location of the weld in the center
is ensured by providing slots in the top plate (2) and bottom plate (3). The test is
continued till a crack is observed. The location of the crack (welded or base
metal and longitudinal or transverse tearing etc) is evaluated if any crack is
noticed. After the testing is completed, the compression disc (1) is raised from
the testing system, and the sheet specimen (5) is removed from the apparatus.
The provision of a conical hole in the bottom plate (3) enables easy removal of
the tested specimen (5).

While the prior art forming tool is gripped in the jaw faces of a universal testing
machine, but the forming (4) tool of the invention on the other hand, is provided
with a threaded portion of diameter about 16mm, which can be threaded to the
compression disc (1) of the standard testing system. This enables a correct
positioning of the forming tool (4), which is important for testing.
While the prior art apparatus is provided with a bottom plate with cylindrical hole
only. This poses problems in the removal of the specimen. In the new device a
conical hole is provided in the bottom plate (3), which enables easy removal of
the tested specimen (5). The prior art apparatus is not provided with any slot.
During testing, if the weld moves off center, if cannot be detected and corrected.
But in the new apparatus slots are provided in the top and bottom plates (2,3)
and the movement of the sheet specimen (5) with the weld in the exact center
can be evaluated for crack development at all stages.

WE CLAIM
1. A device for conducting destructive test on seam-welded thin sheets
adaptable to standard universal testing machine, the machines having a
compression disc (1), the device comprising:
- a forming tool (4) mountable on the compression disc (1), the tool (4) being
capable of getting positioned through threads on the outer surface;
- a apparatus for accommodating a seam welded sheet (5) to be tested, the
apparatus having a top plate (2) and a bottom plate (3), the apparatus being
disposed on the base of the machine (1);
- the forming tool (4) during the testing is caused to vertically move to deform
the test specimen (5) till the seam welded sheet (5) deformed to a hemi
spherical shape without developing any crack,
characterized in that the forming tool (4) is configured with a threaded
portion corresponding to the threaded area provided on the compact disc (1),
in that the bottom plate (3) is provided with a conical hole, and in that the
top and bottom plates (2,3) of the apparatus each configured with at least
one slot.
2. A device for conducting destructive test on seam-welded thin sheets
adaptable to standard universal testing machines as substantially described
and illustrated herein with reference to the accompanying drawings.

The invention relates to a device for conducting destructive test on seam-welded
thin sheets adaptable to standard universal testing machine, the machines
having a compression disc (1), and a base (6), the device comprising a forming
tool (4) mountable on the compression disc (1), the tool (4) being capable of
rotatably and vertically movable along its axis; a apparatus for accommodating a
seam welded sheet (5) to be tested, the apparatus having a top plate (2) and a
bottom plate (3), the apparatus being disposed on the base (6) of the machine;
the forming tool (4) during the testing is caused to rotatably and vertically move
to penetrate the test specimen (5) till the seam welded sheet (5) deformed to a
hemi spherical shape without developing any crack, the forming tool (4) is
configured with a threaded portion corresponding to the threaded area provided
on the compact disc (1), in that the bottom plate (3) is provided with a conical
hole, and in that the top and bottom plates (2,3) of the apparatus each
configured with at least one slot.