Another object of this invention is to propose an improved method of welding
non-ferrous flexible foils to a metal plate by Friction Stir Welding (FSW) which
reduces the defect rate and improve the quality of the job.
A still another object of this invention is to propose an improved method of
welding non-ferrous flexible foils to a metal plate by Friction Stir Welding (FSW)
which reduces the cycle time of production including the number of process
steps.
A further object of this invention is to propose an improved method of welding
non-ferrous flexible foils to a metal plate by Friction Stir Welding (FSW) which
eliminates the use of electrode and gases.
A sill further object of this invention is to propose an improved method of
welding non-ferrous flexible foils to a metal plate by Friction Stir Welding (FSW)
which implements a non-fusion welding process for flexible foils to plate without
oxidization in the weld.
SUMMARY OF THE INVENTION
Accordingly there is provided an improved method of welding non-ferrous flexible
foils to a metal plate by Friction Stir Welding (FSW).

According to the proposed method, a bunch of foils made of a particular
material (s) to be welded or joined with the plate formed of the same
material (s) or dissimilar material (s) of same or varying thickness at other end,
can be carried - out. A device is developed and provided to hold the foils and the
plate to ensure a zero gap between the abutting surfaces before welding as well
as during welding.
A tool made of harder metal than the base material (s), is plunged in the joint
fit-up. The tool pin (7) is rotated at high rotational speed and allowed to plunge
into the joint line. After completion of a full plunging a traverse motion is
imparted (either to the tool or to the job) so that both the plate and flexible foils
got welded.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure A - shows and innovating holding device to hold a plate and flexible foils
before joining by FSW process.
Figure B - shows a rotating FSW tool plunging into the joint line of the plate and
foils.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
The welding method of the flexible foils to the plate by friction stir welding
(FSW) is illustrated in Figures A and B. Figure A describes the method of holding
a plate (1) and flexible foils (2) of same thickness level with a zero gap between
joining surfaces, under optimum pressure from the holding device. Figure B
describes a rotating FSW tool (6) plunging into the joint line until its pin (7)
reaches at optimum plunge depth. After completion of the plunging, FSW tool
shoulder (6) touches the joint (1 & 2) top surface with optimum pressure on the
top surface. After that the FSW tool / job starts a traverse movement along the
required welding direction. Thus, the friction stir welding of the flexible foils to
the plate takes place.
First, the plate (1) and foils (2) are clamped so as to maintain their position
during welding. Figure - A describes the method of holding the plate (1) and
flexible foils (2) at same thickness level with zero gap between a joining surface
under optimum pressure from the holding device (3, 4 and 5). Figure - B
describes the welding process. A Rotating Tool (6) is plunged at a RPM with a
defined plunge rate into a joint line until its pin (7) reaches at the optimum
plunge depth. After completion of the plunging, the FSW tool shoulder (6)
touches top surface of the joint with optimum pressure, and after full plunging
traverse motion is started along the weld line of either the sub-assembly of plate
foils or the tool. Thus both parts (1 and 2 ) got welded.

As positioning of the foils with zero gap is difficult, a holding device is developed
for positioning of the foils (2). The device comprising a base member (4)
attached with two longitudinal members (5) having a shape of inverted V. A
second horizontal member (3) is disposed on the base member (4) which holds
the plate (1). The flexible foils (2) interposed between the longitudinal members
(5) and the plate member (1).

WE CLAIM:
1. An improved method of welding non-ferrous flexible foils to a metal plate
by Friction Stir Welding (FSW), the method comprising the steps of :
- providing a holding device having a horizontal base member (4) attached
at two ends one each longitudinal member (5) formed in a shape of
inverted 'L' shape, the base member (4) provided on upper surface a
second horizontal member (3);
- clamping a plate (1) and multiple non-ferrous foils (2) in a horizontal
direction at identical thickness level with a zero-gap between their joining
surface through application of pressure, the assembly (1, 2) having placed
on the second horizontal member (3) and the longitudinal members (5);
- locating a friction stir welding tool (6) with a rotating pin (7) over the
plate and foil assembly (1, 2);
- causing the tool to rotate upon touching the joining surface and allowing
plunging of the pin under optimum pressure to enable the pin (7) to
progressively reach the full-depth on the upper surface of the joining line
(1, 2);

- imparting a traverse motion making the tool including the welded
component (1, 2) along the welding direction to complete the welding;
and
- removing the welding component (1, 2) from the device.

2. The method as claimed in claim 1, wherein the traverse motion is
imparted on one of the tool (6) and the assembly (1, 2).
3. The method as claimed in claim 1, wherein the tool (7) is made of harder
material(s) than that of the part (1, 2) being weld.
4. The method as claimed in claim 1, wherein welding of nonferrous
material (s) such as Aluminum, copper, brass can be performed for similar
or dissimilar materials.
5. The method as claimed in claim 1, wherein the optimum pressure is
applied on the components (1, 2) by the rotating tool so that it gets
plunged into the metal and welding is started at plastic temperature.
6. The method as claimed in any of the preceding claims, wherein an orbital
motion of the rotating tool allows the tool to plunge into the job.

7. The method as claimed in claim 3, wherein different types of contour,
different types of material(s) with various thickness, can be produced.
8. The method as claimed in claim 1, wherein different type of joints for
example, butt, fillet and corner can be implemented.
9. The method as claimed in claim 1, wherein different thickness of plates
and foils irrespective of their size and numbers can be welded.
10. The method as claimed in claim 1, wherein the oxidization of the welding
joint can be eliminated.

ABSTRACT

The invention relates to an improved method of welding non-ferrous flexible foils
to a metal plate by Friction Stir Welding (FSW), the method comprising the steps
of providing a holding device having a horizontal base member (4) attached at
two ends one each longitudinal member (5) formed in a shape of inverted 'L'
shape, the base member (4) provided on upper surface a second horizontal
member (3); clamping a plate (1) and multiple non-ferrous foils (2) in a
horizontal direction at identical thickness level with a zero-gap between their
joining surface through application of pressure, the assembly (1, 2) having
placed on the second horizontal member (3) and the longitudinal members (5);
locating a friction stir welding tool (6) with a rotating pin (7) over the plate and
foil assembly (1, 2); causing the tool to rotate upon touching the joining surface
and allowing plunging of the pin under optimum pressure to enable the pin (7) to
progressively reach the full-depth on the upper surface of the joining line
imparting a traverse motion making the tool including the welded component (1,
2) along the welding direction to complete the welding; and removing the
welding component (1, 2) from the device.