[001] The present invention generally relates to manufacturing processes, such as welding process. More particularly, the present invention relates to fixtures for holding flat metal plates in a conventional CNC machine, such as lathe, for manufacturing processes.

BACKGROUND OF INVENTION
[002] Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material. Heat is generated by friction between the rotating tool and the workpiece material, which leads to a softened region near the FSW tool. FSW machines are generally costlier and have high implementation costs.

[003] Therefore, a way has been developed to use conventional lathe machine for FSW. Since, conventional lathe machine is generally used only for machining purpose and hence, separate machines are required for making a friction stir welding (FSW) tool and performing FSW operations on the conventional lathe machines. The implementation of separate machines on the conventional lathe machines led to high equipment cost, large installation space and additional lead time due to the waiting between cutting and welding operation. On the other hand, for performing straight line FSW (SLFSW) the cost of procurement of FSW machine is generally 5-50 times more than a conventional lathe machine.

[004] Hence, there is a need to perform an FSW operation conveniently on a conventional lathe machine, which is economically beneficial also.

OBJECTIVES OF INVENTION
[005] The present invention overcomes the above mentioned problems with performing Friction Stir Welding method while being economic and without compromising the efficiency of the welding method.

[006] Therefore, it is an objective of the present invention to provide an economic and efficient way to use a conventional lathe machine for carrying out FSW method, anywhere and with minimal efforts and minimum costs being incurred in installation.

[007] It is an objective of the present invention to provide a conventional lathe machine which is being used without making any constructional change to perform both machining, cleaning and maintenance of FSW tool as well as welding operation, hence saving time, money and installation space, and therefore being economically viable with equivalent quality.

[008] It is an objective of the present invention to provide a portable fixture that can readily be fixed in a tool post of a conventional lathe machine and is used for holding flat plates, to be welded, firmly during joining process.

[009] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention.

SUMMARY OF TH INVENTION

[0010] An aspect of the present invention provides a portable fixture to hold flat metal plates for performing a welding process on the flat metal plates, the portable fixture comprising: a base plate for holding the flat metal plates; a plurality of hollow clamping brackets for gripping the flat plates at the base plate restricting them from slipping from the base plate, where the clamping brackets are insertable either from a top side, a bottom side or both sides of the base plate and are bolted from backside of the base plate, using plurality of clamping bolts, to provide a grip of the flat metal plates on the base plate from a transverse direction of the flat metal plates; and one or more gripping bars attached on the base plate, where one or more of the one or more gripping bars is mounted at a tool post of a conventional lathe machine for the welding process, and wherein the portable fixture is readily held in the tool post of the conventional lathe machine with ease and without disturbing any setting or manufacturing properties/operations of the conventional lathe machine.

[0011] An embodiment of the present invention provides the portable fixture is either a single bit fixture with one gripping bar, or a double bit fixture with two gripping bars, or a multi-bit fixture with multiple gripping bars.

[0012] An aspect of the present invention includes the plurality of hollow clamping brackets having side walls for restricting lateral movement of the flat metal plates in the single bit fixture.

[0013] Another aspect of the present invention provides the portable fixture further including reinforcement ribs welded on the base plate just above and below the gripping bar in order to provide additional strength and rigidness to the portable fixture.

[0014] Yet another aspect of the present invention provides the portable fixture further including a stopper plate to stop the flat metal plates from sliding in downward direction.

[0015] An embodiment of the present invention provides the stopper plate being slidable and slides up and down in order to adjust position of flat metal plates held on the base plate.

[0016] An embodiment of the present invention provides the portable fixture is a double bit fixture with two gripping bars, and the double bit fixture further comprising: two reinforcement ribs, for each of the two gripping bars, welded at rear of base plate to provide additional strength to the double bit fixture; a slider bar, at bottom of the base plate, to stop the flat metal plates from sliding in downward direction; two slots at top or bottom half of the base plate to act as a sliding mechanism for the slider bar, where the slider bar slides and locks in a position at one of the two slots to adjust its position, and where the slider bar 308 slides and adjusts position of the bottom plate; and stopper screws fitted on the clamping brackets through threaded holes which are provided on front side of the clamping brackets, the stopper screws provide additional resistance to restrict movement of the flat metal plates in lateral direction, and wherein based on breadth of the flat metal plates, the stopper screws are fixed in either of plurality of holes which are provided in one half of the clamping brackets.

[0017] An embodiment of the present invention provides the portable fixture holds the flat metal plates for performing welding on the flat metal plates, and wherein the flat metal plates are made either of similar and dissimilar materials, and wherein the flat metal plates are made either of aluminium alloys, cooper alloys, titanium alloys, mild steel, stainless steel and magnesium alloys, or polymers

BRIEF DESCRIPTION OF DRAWINGS
[0018] FIGs. 1A-1F illustrate different views of a portable fixture that can be readily fixed in a tool post of a lathe machine, the views including perspective view, side view, front view, top view, exploded view, and arranged ready fixture, respectively, in accordance with an embodiment of the present invention;

[0019] FIG. 2 illustrates an exemplary environment showing two flat plates, which are to be welded, being arranged in the portable fixture, in accordance with an embodiment of the present invention; and

[0020] FIG. 3 illustrates an exemplary environment showing a tool held in chuck of a lathe machine and the portable fixture held in a tool post of the lathe machine, in accordance with an embodiment of the present invention;

[0021] FIG.4 illustrates an exemplary environment showing FSW process performing in the lathe machine, in accordance with an embodiment of the present invention;

[0022] FIGs. 5A-5D illustrate different views of a two-bit portable fixture that can be readily fixed in a tool post of a lathe machine, the views including front view, top view, rear view, perspective view respectively, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF INVENTION
[0023] This patent describes the subject matter for patenting with specificity to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. The principles described herein may be embodied in many different forms.

[0024] Illustrative embodiments of the invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0025] The present invention provides a portable fixture that can be readily fixed in a tool post of a conventional lathe machine with ease and without disturbing any setting or manufacturing properties/operations of the lathe machine. The portable fixture is used for holding flat plates firmly which are to be welded using a Friction Stir Welding process. The portable fixture can be used to hold the flat plates for performing welding on the flat plates. The flat plates may be of similar and dissimilar materials, which are difficult to weld by conventional methods. The flat plates may be of thickness ranging from 3mm to 20mm. Further, the plates which can be weld using this method may be of materials including and not limited to aluminium alloys, cooper alloys, titanium alloys, mild steel, stainless steel and magnesium alloys, polymers, joining of dissimilar metals such as aluminium to magnesium alloys, and the like.

[0026] According to an embodiment of the present invention, an FSW tool is firmly held in a lathe chuck of a conventional lathe machine, and rotated in anticlockwise direction at a suitable rotational speed. The plates are fed against the rotating tool by the movement of cross slide in the transverse direction to the tool axis. A carriage can be fixed by engaging a thread clutch of the machine to give the constant pressure of the tool shoulder on the abutting plate during FSW. The process facilitates to join similar and dissimilar aluminum and also aluminum- copper plates that may be used in fabrication purpose.

[0027] The portable fixture, according to the invention, may be of two types: Single bit and Double bit Fixture that can be held in Lathe machine tools post for performing FSW on flat plates. The portable fixture is either a single bit fixture with one gripping bar, or a double bit fixture with two gripping bars, or a multi-bit fixture with multiple gripping bars. It may be apparent to a person skilled in the art that the portable fixtures may be manufactured as multi-bit fixture, depending on the design, requirements of the fixture and the welding method, without deviating from the meaning and scope of the present invention.

[0028] FIGs. 1A-1F illustrate different views of a portable fixture that can be readily fixed in a tool post of a lathe machine, the views including perspective view, side view, front view, top view, exploded view, and arranged ready fixture, respectively, in accordance with an embodiment of the present invention. FIG. 1A shows different components of single-bit portable fixture 100. The portable fixture 100 is mounted in the tool post in the same manner a cutting tool is used to mount. In an embodiment, the portable fixture is made to clamp aluminum plates of 65mm breadth. Clamping brackets 102 are inserted from top and bottom of a base plate 104 and bolted on backside of the base plate 104, using clamping bolts 106, in order to provide solid grip of the flat plates 108 from the transverse direction. Lateral movement of the flat plates 108 are prevented by a side wall of the clamping brackets 102 in the single bit fixture 100.

[0029] A gripping bar 110 is attached on the base plate 104. The gripping bar 110 is mounted in the tool post of the lathe machine at the time of FSW. Reinforcement ribs 112 are welded on the base plate 10 just above and below the gripping bar 110 in order to provide additional strength and rigidness of the fixture 100 near the processing. Stopper plate 114 is used on the front side which is used to stop the flat plate 108 so that it does not slide in the downward direction. Stopper plate 114 can also slide up and down in order to adjust the height of bottom flat plate 108.

[0030] During the process of FSW, severe plastic deformation takes place in the nugget zone. It is extremely important to have solid gripping of the flat plates 108 during the process so that the plates 108 do not move during the process as it greatly influence the efficiency of a welded joint. And the solid gripping of the plates 108 is provided by the clamping brackets 104 and the bolts 106 of the fixture 100.

[0031] Referring to FIGs. 3 and 4, a schematic representation 200 of FSW process on a lathe machine for joining two plates, such as Aluminum and copper alloys is shown. The friction- stir- welded zone implies a region changed in microstructure by mechanical stirring action of the rotating tool during the FSW. A tool 202 is being held in lathe chuck 204 and the flat plates 108 are held in a tool post 206 using the portable fixture 100.

[0032] In an embodiment, dimensions of metal plates are 25 mm wide x 75mm long x 6mm thick. The shoulder of the tool was considered as 15 mm with 1mm chamfer on the outer circumference of the shoulder to minimize the obstruction between the tool 202 and the metal plates 108. Tool pin diameter and height are considered as 4mm and 4.5mm respectively. The tool 202 is rotated in anti-clockwise direction at speeds ranging from 350 rpm to 1200 rpm. The tool 202 remain fixed in chuck 204 and the plates 108 are traversed against the rotating tool in forward direction at different feed rates ranging from 10 mm/min to 60 mm/min. Tool 202 remain perpendicular to the axis of the flat plates 108.

[0033] FIGs. 5A-5D illustrate different views of a two-bit portable fixture that can be readily fixed in a tool post of a lathe machine, the views including front view, top view, rear view, perspective view respectively, in accordance with an embodiment of the present invention. FIG. 5A shows different components of the two-bit portable fixture 300.

[0034] In an embodiment, the two-bit portable fixture has two gripping bars, two reinforcement ribs, for each of the two gripping bars, welded at rear of base plate to provide additional strength to the double bit fixture; a slider bar, at bottom of the base plate, to stop the flat metal plates from sliding in downward direction; two slots at top or bottom half of the base plate to act as a sliding mechanism for the slider bar, where the slider bar slides and locks in a position at one of the two slots to adjust its position, and where the slider bar 308 slides and adjusts position of the bottom plate; and stopper screws fitted on the clamping brackets through threaded holes which are provided on front side of the clamping brackets, the stopper screws provide additional resistance to restrict movement of the flat metal plates in lateral direction, and wherein based on breadth of the flat metal plates, the stopper screws are fixed in either of plurality of holes which are provided in one half of the clamping brackets.

[0035] As shown in the FIG. 5A, the double bit fixture 300 has two gripping bars or double bits, and is designed to accommodate larger dimensions of the base metal plate which need to be joined using FSW. The fixture 300 has two bits which gets fit in to two opposite sides of the tool post and get fastened by the tool post bolts solidly. The fixture 300 is composed of several parts and each part has its specific purpose and use.

[0036] Fixture back plate 302 is the main body of the fixture 300 on which the base metal plates 108 are fixed. Back plate 302 has two holding bits 304 (shown in FIG. 5B) at the rear which are solidly fitted through press fitting and welding. Two reinforcement ribs 306(shown in FIG. 5B), for each holding bit 304, are also welded at the rear of back plate 302 which provides additional strength to the fixture 300 near the processing zone. The back plate 302 has two slots at the bottom half to act as sliding mechanism for a slider bar 308 which is used to stop the bottom plate 108 and to adjust its height.

[0037] Slider & Stopper bar 308 is fitted in the front side of the back plate 302 and it can slide in the slots provided in the back plate. The Slider bar 308 can be fixed at any height using screws on the other side of the back plate 302. The slider bar 308 is used to adjust the height of the bottom plate 108 so that the abutting surface of the bottom plate 108 remains at the center of the tool tip.

[0038] Clamping brackets 310: the Fixture 300 has two clamping brackets 310 which are used to clamp the metal plates 108. These brackets 310 get inserted into the back plate 302 from top and bottom of the back plate 302 and can be clamped at any suitable distance by fastening the screws which are mounted at the backside of the bracket 310. Once the brackets 310 are clamped, the plates 108 are solidly gripped due to large force applied on larger contact area of bracket 310 and metal plates interface.

[0039] Stopper Screws 312: Stopper screws 312 are fitted on the Clamping brackets 312 through the threaded holes provided on the front side of the bracket 312. Stopper screws have the purpose of providing additional resistance to restrict the movement of plates 108 in lateral direction. Based on the breadth of the base metal plate 108, stopper screw 312 can be fixed in different holes provided in one half of the bracket surface.

[0040] Advantageously, the present invention provides a portable fixture that can be readily clamped in a tool post of a conventional lathe machine to hold flat metal plates to be welded using a friction stir welding process, without requiring separate machines for the welding process to be performed using the lathe machine. The process is performed on a conventional lathe machine which is far economical than FSW machine and readily available in most of the workshops. The same machine is used for making FSW tool and performing the welding operation, which saves changeover time and installation space. After excessive usage of tool during welding, the tip requires maintenance and removal of seized metal from the tip. This maintenance task can be performed on the same machine without removing the fixture.

[0041] Although the present disclosure of the invention illustrates the design and shape of the portable fixture as can be seen in the FIGs. 1-5D, it should be understood that the present disclosure of the invention is not restricted to the design and shape as shown in the FIGs. 1-5D, but can include variations of design and shape that can perform the same purpose of the invention, without deviating from the meaning and scope of the present invention.

[0042] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the present disclosure. Indeed, the novel methods, devices, and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the methods, devices, and systems described herein may be made without departing from the spirit of the present disclosure.

CLAIMS:We claim:
1) A portable fixture to hold flat metal plates for performing a welding process on the flat metal plates, the portable fixture comprising:
a base plate for holding the flat metal plates;
a plurality of hollow clamping brackets for gripping the flat plates at the base plate restricting them from slipping from the base plate, where the clamping brackets are insertable either from a top side, a bottom side or both sides of the base plate and are bolted from backside of the base plate, using plurality of clamping bolts, to provide a grip of the flat metal plates on the base plate from a transverse direction of the flat metal plates; and
one or more gripping bars attached on the base plate, where one or more of the one or more gripping bars is mounted at a tool post of a conventional lathe machine for the welding process, and
wherein the portable fixture is readily held in the tool post of the conventional lathe machine with ease and without disturbing any setting or manufacturing properties/operations of the conventional lathe machine.

2) The portable fixture as claimed in claim 1, wherein the portable fixture is either a single bit fixture with one gripping bar, or a double bit fixture with two gripping bars, or a multi-bit fixture with multiple gripping bars.

3) The portable fixture as claimed in claim 2, wherein the plurality of hollow clamping brackets has side walls for restricting lateral movement of the flat metal plates in the single bit fixture.

4) The portable fixture as claimed in claim 1, wherein the portable fixture further includes reinforcement ribs welded on the base plate just above and below the gripping bar in order to provide additional strength and rigidness to the portable fixture.
5) The portable fixture as claimed in claim 1, wherein the portable fixture further includes a stopper plate to stop the flat metal plates from sliding in downward direction.

6) The portable fixture as claimed in claim 5, wherein the stopper plate is slidable and slides up and down in order to adjust position of flat metal plates held on the base plate.

7) The portable fixture as claimed in claim 2, wherein the portable fixture is a double bit fixture with two gripping bars, and the double bit fixture further comprising:
two reinforcement ribs, for each of the two gripping bars, welded at rear of base plate to provide additional strength to the double bit fixture;
a slider bar, at bottom of the base plate, to stop the flat metal plates from sliding in downward direction;
two slots at top or bottom half of the base plate to act as a sliding mechanism for the slider bar, where the slider bar slides and locks in a position at one of the two slots to adjust its position, and where the slider bar 308 slides and adjusts position of the bottom plate; and
stopper screws fitted on the clamping brackets through threaded holes which are provided on front side of the clamping brackets, the stopper screws provide additional resistance to restrict movement of the flat metal plates in lateral direction, and wherein based on breadth of the flat metal plates, the stopper screws are fixed in either of plurality of holes which are provided in one half of the clamping brackets.

8) The portable fixture as claimed in claim 1, wherein the portable fixture holds the flat metal plates for performing welding on the flat metal plates, and wherein the flat metal plates are made either of similar and dissimilar materials, and wherein the flat metal plates are made either of aluminium alloys, cooper alloys, titanium alloys, mild steel, stainless steel and magnesium alloys, or polymers.