Title of Invention

FLEXIBLE CONTACT TUBE FOR ROTATION ARC GMA WELDING.

Abstract

A flexible contact tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch adapted for arc rotation, said tube of comprising slots of length 37pd/8 to 5pd/8, at spacing of d/3 to d/2.5 (where d is the inside diameter of said contact tube). A device for arc rotation comprising the flexible tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch; the torch body; contact tip; means for attachment of the said tube between the torch body and contact tip; means for providing lateral motion to the contact tip and means for moving the contact tube. The said device for arc rotation yields improved weld bead geometry and penetration characteristics.

Full Text

FIELD OF INVENTION The present invention relates to a flexible contact tube comprising slots of defined length and spacing and adapted to facilitate are rotation. More particularly the invention relates to a device for arc rotation comprising the said flexible contact tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch. The present invention further relates to a device for arc rotation adapted to yield improved weld bead geometry and penetration characteristics BACKGROUND AND PRIOR ART: The first arc rotation mechanisms that rotate the electrode nozzle by a motor have been developed in Japan and Germany. These mechanisms are intended to use as an arc sensor in robotic welding. C.H.Kim and S.J.Na developed a rotating mechanism by using a hollow shaft motor. The motor is to be installed in the electrode nozzle. Na S.J, Moon o H.S and Kim C.11 obtained patent in Korea. Apparatus for rotation arc welding with hollow shaft motor. Korean pat. 236916, .5 October 1999. The other mechanisms for arc rotation use carbon brush or some other mechanism for transmitting the current to contact tip. The relative movement between the carbon brush and contact tip may result in high contact resistance and heating of contact tip (Ref. Sugitani et al Japan). The mechanism developed by Na S.J et al (Korea) requires a specially designed motor. OBJECTS OF THE INVENTION Thus the main object of the present invention is to provide a flexible tube comprising slots of defined length and spacing and adapted to facilitate arc rotation. Another object of the present invention is to provide a device for arc rotation comprising the said flexible contact tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch. 3 A further object of the invention is to provide a device for arc rotation such that the bead geometry obtained from Pulsed Gas Metal Arc Welding using the said device is improved with better penetration characteristics. SUMMARY OF INVENTION Thus according to one aspect of the present invention there is provided a flexible contact tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch adapted for arc rotation, said tube of comprising slots of length 3pd/8 to 5pd/8, at spacing of d/3 to d/2.5 Where d is the inside diameter of the flexible contact tube. According to a further aspect of the present invention there is provided a device for arc rotation comprising the flexible tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch; the torch body; contact tip; means for attachment of the said tube between the torch body and contact tip; means for providing lateral motion to the contact tip and means for moving the contact tube device for arc rotation comprising the said flexible contact tube. DETAILED DESCRIPTION OF THE INVENTION The contact flexible tube of the present invention has slots which provide flexibility to the contact tip attached to the end of this tube so that contact tip moves laterally with little force. The length of slots, spacing between the slots, the thickness of the flexible contact tube and its material are vital for imparting flexibility as well as longer life (i.e., preventing over heating and fracture of the tube). The preferred length of the slots pd/2 and they are present preferably at spacing of d/3 to d/2.5. The width of the slots is from d/15 to d/8. The thickness of material for the flexible tube is preferably d/8 to d/6. There are small holes of diameter d/8 to d/6 preferably 2mm at the end of the slots. The presence of such small circular holes at the ends of slot prevents stress concentration and avoids fracture of the tube, thus imparting longer life. The said tube is made of selectively from copper, 4 preferably high purity copper. The thickness of the tube is also an important attribute and may vary from d/8 to d/6, preferably 1.5 mm. The device of the present invention comprises of the motor, torch body, insulation, flexible contact tube, sleeves for attaching the flexible contact tube, thrust bearing and the contact tip along with other conventional features. The electrode wire is fed into the eccentric contact tip, which is rotated by an external motor. Due to the rotation of eccentric disc the contact tube and the arc rotates at high speed/The flexible contact tube provides flexibility for the lateral movement of contact tube and arc could be rotated. Simultaneously it provides path for current flow between fixed tube holder and rotating contact tube. Its. design is quite critical for satisfactory functioning of the arc rotation device. The flexible tube provides long working life as well as flexibility for movement with little force. Although the device for arc rotation comprises the motor, there could be any suitable means of moving the contact tube, which is not part of this patent application. The use of contact tube is also associated, to some extent, with the means of arc rotation used here like use of eccentric disc meant for providing lateral motion to the rigid contact tip. This means for providing lateral movement to the torch like the eccentric disk is separately fabricated arid attached to the torch body. The flexible contact tube has made it possible to have all the parts forming current path to be" rigidly connected to each other thus avoiding any contact resistance and resulting overheating when heavy current (200 - 400 amps) flow through device. The present mechanism has no relative movement between the components that transmit current. Hence there is no contact resistance in the current path. There are two sleeves, attached at the ends of the flexible contact tube so that it can be fitted in the torch between the torch body and contact tip using threads shown on sleeves. These sleeves are welded to the flexible contact tube. The threads in the tube conform to 5 the mating threads 'in GMA welding torch and its contact tip. The dimension of these threads may be varied depending upon the welding torch used. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 : The principle of arc rotation mechanism. Figure 2: Schematic diagram of the device of arc rotation of the present invention Figure 3: Schematic diagram of the flexible contact tube of the present invention Figure 3a is actual view and Figure 3b is enlarged view Figure 4: Schematic diagram of sleeves to be placed on the top and bottom of the flexible contact tube. Figure 5a: Beads deposited without arc rotation device of present invention Figure 5b: Beads deposited with arc rotation device of present invention Figure6: Beads obtained from the device of present invention rotated at various speeds. DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 depicts the principle of arc rotation. The eccentric disk (1) provides the lateral movement. The device of the arc rotation (2) with the contact tip (3) is shown to provide the semicircular penetration (4) on the weld pool (19). Figure2: The device of the invention is shown to comprise outer casing (14), inner casing (15) bearing (16), gear wheel (17), gas hole (18). The arc (5) is rotated by the motor (6). The flexible contact tube (7) is attached to the torch body (8) by means of sleeves (not shown). The insulation (9) and the thrust bearing (10) are conventional parts of the device. The contact tip (3) with the welding wire (11) is the rotated by the motor (6) with the movement of the flexible contact tube (7). The electrode wire (11) is fed into the contact tip (3), which is rotated by an external motor (6). Due to the rotation of eccentric disc (1) the contact tube (7) and the arc (5) rotates at high speed. Figure 3 gives the details of the flexible contact tube of the present invention made of copper and where 3a is actual view and 3b is enlarged view. The slots (12) arc shown to end in holes (13), which are also indicated in the figure. The length of the tube s 90 .mm with inner diameter of 12 or 13 mm and outer diameter of 15 or 16 mm. The slots are 5mm apart. These provide for the flexibility and current carrying capacity of the flexible contact tube of invention. If d is inner diameter of contact tube length of straight portion of tube is 7d to l0d ; the thickness of the tube is d/8 to d/6 ; slot width of the tube is d/15 to d/8 ; slot spacing is d/3 to d/25 ; diameter of hole at the end of slot is d/8 to d/6 ; length of the slot is 3/8 to 5/8 of perimeter. Figure 4 provides the sleeves to be fitted on top and bottom of the flexible contact tube. These sleeves are required to fit the flexible contact tube to the welding torch. The threads on these sleeves should be made to match with the threads of GMA welding torch and contact tip. Figure 5 shows the beads deposited by the present device in comparison to that without the flexible tube of present invention. It is seen that the beads obtained from the device of present invention (fig. 5b) are better than that without using the flexible contact tube (fig 5a). Beads obtained by rotating arc welding of present invention are flat and the penetration is semi circular. Figure 6 shows some beads obtained at various speeds of arc rotation. It would be seen that as speed is increased more flat beads are obtained. The flexible contact tube enables to attain such high speed and thus leads to better bead geometry and penetration. 7 WE CLAIM 1. A flexible contact tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch adapted for arc rotation, said tube of comprising slots of length 3? d/8 to 5p d/8, at spacing of d/3 to d/2.5 (where d is the inside diameter of said contact tube). 2. A flexible contact tube as claimed in claim 1 wherein the slots end in holes of diameter d/8 to d/6, preferably 2mm to bear stress and provide longevity to the contact tube (where d is the inside diameter of said contact tube). 3. A flexible contact tube as claimed in claim 1 or 2 wherein the said tube has thickness of d/8 to d/6, preferably 1.5 mm (where d is the inside diameter of said contact tube). 4. A flexible contact tube as claimed in any preceding claim wherein the said tube is made of material selected from copper, preferably high purity copper. 5. A device for arc rotation comprising the flexible tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch as claimed in any preceding claim; the torch body; contact tip; means for attachment of the said tube between the torch body and contact tip; means for providing lateral motion to the contact tip and means for moving the contact tube. 6. A device for arc rotation as claimed in claim 5 wherein the flexible contact lube provides flexibility for the lateral movement of contact tube and arc rotation with simultaneous current flow between fixed tube holder and rotating contact tube. 8 7. A device for arc rotation as claimed in claims 5 to 6 wherein the means of attachment of said flexible contact tube to the torch body and the contact tip are sleeves. 8. A device for arc rotation as claimed in claim 7 wherein the sleeves are provided with threads conforming to those on the torch body and contact tube. 9. A device for arc rotation as claimed in claims 5 to 8 wherein the means for providing lateral motion to the contact tip is the eccentric disk. 10. A device for arc rotation as claimed in claims 5 to 9 wherein the means for moving the contact tube is a motor. 11. A device as claimed in claims 5 to 10 such that it yields improved weld bead geometry and penetration characteristics. 12. A flexible contact tube as substantially described herein with reference to the accompanying drawings and a device for arc rotation comprising the same. A flexible contact tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch adapted for arc rotation, said tube of comprising slots of length 37pd/8 to 5pd/8, at spacing of d/3 to d/2.5 (where d is the inside diameter of said contact tube). A device for arc rotation comprising the flexible tube adapted to be accommodated with any conventional Gas Metal Arc (GMA) welding torch; the torch body; contact tip; means for attachment of the said tube between the torch body and contact tip; means for providing lateral motion to the contact tip and means for moving the contact tube. The said device for arc rotation yields improved weld bead geometry and penetration characteristics.

Documents:

00387-kol-2004 abstract.pdf

00387-kol-2004 claims.pdf

00387-kol-2004 correspondence.pdf

00387-kol-2004 description(complete).pdf

00387-kol-2004 drawings.pdf

00387-kol-2004 form-1.pdf

00387-kol-2004 form-18.pdf

00387-kol-2004 form-2.pdf

00387-kol-2004 form-3.pdf

00387-kol-2004 letters patent.pdf

00387-kol-2004 p.a.pdf