FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Fixture for Denting and stiffness testing for body panel of automobile


APPLICANTS
TATA MOTORS LIMITED, an Indian company
Having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTOR
Jitendra Agashe an Indian national
of TATA MOTORS LIMITED,
An Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following Complete specification particularly describes the invention and the
manner in which it is to be performed.

FIELD OF INVENTION
The invention relates to testing fixture and more particularly to fixture for testing Denting and stiffness for body panel of automobile.
BACKGROUND OF INVENTION
With the increasing need for improved fuel economy, automotive industries are trying to reduce the vehicle weight. Outer Body panels are a very important factor in reducing the vehicle weight. The demand for weight reduction has led to thinner sheets, greater use of high strength steels and a change from steel to aluminum grades. As thickness of body panel reduces, their dent resistance decreases. These optimized designs of outer body panels need to qualify several performance criteria like dent resistance, Stiffness, Oil canning etc. A dent is a permanent deformation of a body panel. Oil canning is a temporary and localized reversal of curvature of body panel under load within elastic range of material from which panel is made.
Along with stiffness, dent resistance and oil canning are the parameters on which customer feels and judges the quality of the body panels. Dent resistance is important to avoid panel damage in-plant and minimize dents and dings on external parts in service. More over poor body panel quality of vehicle is also a reason in less resale value of a used car.
There are many reasons for getting a dent on automotive body panels. One of them being various impacts under dynamic condition called dynamic denting. Secondly when there is no enough curvature of a body panel it may not be able to withstand door slamming. Thirdly creases can occur along prominent features lines.

For checking the dent resistance, stiffness and oil canning there is no generic test method adopted worldwide. For checking the dent resistances a wide range of custom built test equipments have been employed. Difference can be method of load application, speed of load application, indentor shape and size and panel assembly conditions.
In all the applications, the basic principle of applying the load on panel resulting in the deflection of body panel and plastic deformation will remain the same. Some test methods are related to repeat application and removal of force at increasing level .Some application involve continued application of steadily increasing force until the denting occurs.
Stiffness tests can be carried out with the use of same equipment but with a use of indentor having more radius to prevent the local deformation.
OBJECT OF INVENTION
The main object of the present invention is to provide a fixture for denting and stiffness test for body panel of an automobile.
Another object of the present invention is to provide a fixture for testing denting and stiffness for body panel of an automobile which is simple in construction and cost effective.
STATEMENT OF INVENTION
Accordingly the present invention discloses, a fixture for testing denting and stiffness for body panel of automobile comprising;

at least one base plate capable of being fastened to test platform on which vehicle body
is mounted and configured to move in longitudinal direction;
a first circular plate fastened horizontally on said base plate;
a first circular rotating plate with circumferential circular slots for angular positioning
of said first circular rotating plate, is fixed with said first circular plate ;
at least one vertical channel connected to said first circular rotating plate, said vertical
channel having a central longitudinal slot for vertical movement of a second circular
plate mounted in said longitudinal slot;
a second circular rotating plate having circumferential circular slots for angular
positioning of said second circular rotating plate, is fixed with said second circular
plate;;
at least one pneumatic cylinder having a loading indenter for denting and stiffness test
is mounted on said second circular rotating plate; and
a data acquiring system is coupled to said pneumatic cylinder for data acquisition.
Accordingly the present invention further discloses a fixture for testing denting and
stiffness for body panel of automobile comprises;
at least two base plates capable of being fastened to test platform on which vehicle
body is mounted configured to move in longitudinal direction, said base plates being
placed at a distance from each other;;
at least two vertical columns, each of which is fixed on each of said base plates, each of
said vertical columns having a central longitudinal slot for vertical movement of a
circular plate mounted on each of said longitudinal slots;
at least two circular rotating plates having circumferential circular slots for angular
positioning of said circular rotating plates, is fixed with said circular plates;
a horizontal member having a central longitudinal slot for mounting and movement of a
pneumatic cylinder in vehicle transverse axis, is provided between said at least two
circular rotating plates;

said pneumatic cylinder having a loading indenter for denting and stiffness test; and data acquiring system constituted to be coupled to said pneumatic cylinder for data acquisition.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 :-Shows the test fixture to be used for Side doors,fendors,tailgate. Fig.2:-Shows the test fixture to be used for bonnet
BRIEF DESCRIPTION OF INVENTION
In accordance with the first embodiment of the present invention, fixture for denting and stiffness testing for body panel of an automobile for (side doors, fenders, tailgate) comprises base, a vertical channel, first circular rotating plate, first circular plate, second circular rotating plate, second circular plate, Wherein said base can be mounted on a platform which is provided for mounting vehicle body shell. The said first circular rotating plate can be rotated in horizontal plane. The said column comprises a slot for height adjustment and is welded to said first circular rotating plate. The pneumatic cylinder is attached to the said vertical circular rotating plate.
In accordance with the second embodiment of the present invention, fixture for testing denting and stiffness for body panel of an automobile (For bonnet), said fixture comprises at least two base plates, at least two vertical column, at least two vertical circular rotating plates, at least two vertical circular plates, a horizontal joining arm, wherein the said base plates can be mounted on a platform which is provided for mounting vehicle body shell, said vertical column comprises a slot for height adjustment and is welded to said base plates, said vertical circular rotating plates are

rotatetable in vertical plane. The pneumatic cylinder is attached to the said horizontal joining arm.
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
Now referring to figure-0 1, the test fixture which is used for side doors, fenders, tailgates consists of a base (5). This base can be fixed to a platform by nuts and bolts on which the vehicle body is mounted. Attached to the base is a first circular plate (4) having holes for bolting. A similar first circular rotating plate (3) having circular slots can be fixed to first circular plate by bolting. The slots on first circular rotating plate are provided for rotation of said plate. The rotation of said plate can be achieved by loosening the bolts on first circular rotating plate by rotating it upto required angle through circular slot and again fixing it by bolting. The base (5) can be moved along the platform on which vehicle is mounted to have movement of test fixture in longitudinal direction. Thus the said test fixture is able to accommodate various testing locations in vehicle longitudinal directions.
Vertical channel (2) is welded to the first circular rotating plate (3). The channel is a having a vertical slot (12) cut through its length. A second circular plate (6) can be moved through said slot and can be fixed at a vertical location of testing by bolting. Thus the said test fixture is able to accommodate various testing locations at different heights on a vehicle body panel.

Second circular plate (6) has holes for bolt fixing. A similar second circular rotating plate (1) having circular slots can be fixed to vertical circular plate (6) by bolting. When angle need to be changed bolts can be loosened, second circular rotating plate (1) can be rotated and when required position is attained again can be fixed with bolts. Thus the said test fixture is able to accommodate various angular positions of test locations in vertical transverse plane as well as in horizontal longitudinal direction.
A pneumatic cylinder (13) with a loading indenter (15) for Denting and stiffness test can be fixed to the second circular rotating plate (1) with suitable L bracket (14). A data acquiring system can be coupled to pneumatic cylinder to acquire the data.
Now referring to figure-02, the test fixture which is used to test the bonnet consists of two base plates (7). The said base plates can be fixed to the platform on which the vehicle is mounted by bolting. The said base plates can be moved along vehicle longitudinal axis to take care of different test location and can be fixed at a location when required movement is achieved.
There are two vertical columns (8) which are welded to the two base plates and thus can be moved along with base plates. A vertical slot is provided on both the columns. There are two vertical circular plates (10) having holes for bolting which can be moved in the slots of vertical columns and can be fixed at a required point or location by bolting with column when required angular position is achieved. Thus the test fixture can accommodate different height levels of test locations.
Two vertical circular rotating plates (9) having circular slots are fixed with two vertical circular plates by bolting. The said two vertical circular rotating plates are welded to a horizontal joining arm or horizontal member (11). The said joining arm or horizontal member has a slot (17) cut through its length. A pneumatic cylinder (20) with loading

indentor (21) is fixed to the joining arm or horizontal member with suitable attachment and can be moved along the slot of horizontal member to move the cylinder in vehicle transverse axis. The said pneumatic cylinder can be attached to the said joining arm or horizontal member with a plate (18) having slot and L bracket (19) having similar slot. The said L bracket has a square hole (22) through which the said pneumatic cylinder is attached to the said L bracket and can be fixed through threaded hole (23) in L bracket.
When the angular position is required to be changed to take care of test locations at different level, then bolts are loosened, the said joining arm or horizontal member along with said vertical circular rotating plates (9) can be turned and can be fixed again when required rotation is achieved.
The said pneumatic cylinder can have angular movement in transverse plane. This is achieved by loosening the bolt which is used to fix the said plate, L bracket and the said joining arm. A data acquiring system can be coupled to pneumatic cylinder to acquire the data.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

WE CLAIM
1. A fixture for testing denting and stiffness for body panel of automobile comprising;
at least one base plate adapted to fasten to test platform on which vehicle body is mounted and configured to move in longitudinal direction;
a first circular plate fastened horizontally on said base plate;
a first circular rotating plate with circumferential circular slots for angular positioning of said first circular rotating plate, is fixed with said first circular plate;
at least one vertical channel connected to said first circular rotating plate, said vertical channel having a central longitudinal slot for vertical movement of a second circular plate mounted in said longitudinal slot;
a second circular rotating plate having circumferential circular slots for angular positioning of said second circular rotating plate, is fixed with said second circular plate;
at least one pneumatic cylinder having a loading indenter for denting and stiffness test is mounted on said second circular rotating plate; and
a data acquiring system is coupled to said pneumatic cylinder for data acquisition.
2. A fixture for testing denting and stiffness for body panel of automobile comprises;
at least two base plates adapted to fasten to test platform on which vehicle body is mounted configured to move in longitudinal direction, said base plates being placed at a distance from each other;
at least two vertical columns, each of which is fixed on each of said base plates, each of said vertical columns having a central longitudinal slot for vertical movement of a circular plate mounted on each of said longitudinal slots;
at least two circular rotating plates having circumferential circular slots for angular positioning of said circular rotating plates, is fixed with said circular plates;

a horizontal member having a central longitudinal slot for mounting and movement of a pneumatic cylinder in vehicle transverse axis, is provided between said circular rotating plates;
said pneumatic cylinder having a loading indenter for denting and stiffness test; and
data acquiring system constituted to be coupled to said pneumatic cylinder for data acquisition.
3. The fixture as claimed in claim 1, wherein said fixture is configured for performing tests on vehicle side doors, fenders and tailgates.
4. The Fixture as claimed in claim 1, wherein said base plate can be fixed to said test platform by fasteners.
5. The Fixture as claimed in claim 1, wherein said first and second circular plates have mounting holes for fastening said first and second circular rotating plates through said circular slots.
6. The Fixture as claimed in claim 1 and 5, wherein said first and second circular rotating plates are configured to rotate by a required angle through said circular slots by loosening the fasteners on said first and second circular rotating plates.
7. The Fixture as claimed in claim 1, wherein said pneumatic cylinder is mounted to said second circular rotating plate through 'L' bracket.
8. The Fixture as claimed in claim 2, wherein said fixture is configured for performing test on vehicle bonnet.

9. The Fixture as claimed in claim 2, wherein said base plates can be fixed to said test platform by fasteners.
10. The Fixture as claimed in claim 2, wherein said circular plates have mounting holes for fastening said circular rotating plates through said circular slots.
11. The Fixture as claimed in claim 2 and 10, wherein said circular rotating plates are configured to rotate by a required angle through said circular slots by loosening the fasteners on said circular rotating plates.
12. The Fixture as claimed in claim 2, wherein sliding of said circular plates on vertical columns are adjustable for acquiring required angular position of said horizontal member.
13. The Fixture as claimed in claim 2, wherein said pneumatic cylinder is mounted to said horizontal member through 'L' bracket capable of moving said pneumatic cylinder across said central longitudinal slot of said horizontal member.
14. Fixtures for testing Denting and stiffness for body panel of automobile as herein above described and as illustrated in accompanying drawings.