Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K9/00—Arc welding or cutting
  • B23K9/16—Arc welding or cutting making use of shielding gas
  • B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode

Definitions

• the present invention relates to a method of welding or welding, preferably robotized, with TIG torch and filler metal in the form of one or more fusible wires, in particular one or more pieces of coated steel or aluminum or aluminum.
• aluminum alloy in which the transfer of the metal from or to the solder bath is by successive drops at a controlled frequency.
• the sixth axis of the robot carrying the TIG torch is blocked and its degrees of freedom are limited since a certain directivity is necessary to guide the supply of wire in the axis of the weld joint of the makes the horizontal arrival of the wire.
• EP-A-1459831 proposes an arc welding method not posing the aforementioned problems.
• the supply of fusible wire is operated at an angle less than 50 ° relative to the axis of the electrode, preferably an angle between 15 and 35 °, and the end of the fuse wire is guided and kept permanently at a distance of less than 2 mm from the end of the tungsten electrode.
• An object of the present invention is therefore to improve the process described in document EP-A-1459831 so as to obtain an effective welding or brazing-welding especially of specific materials, in particular coated steels and aluminum, and its alloys, so as to mitigate, minimize or at least mitigate the aforementioned quality problems.
• the solution of the invention is a brazing or arc welding process using a TIG torch provided with a non-fuse electrode and a fuse wire of given diameter, in which:
• the TIG torch is fed with said fuse wire in such a way that the supply of fusible wire is operated at an angle less than 50 ° with respect to the axis of the electrode, that is to say that the axis of the end of the wire at the non-fusible electrode and the axis of said electrode form an angle less than 50 °,
• the end of the fuse wire is permanently guided and maintained at a distance of less than 2 mm, preferably at least 1 mm (about 1.5 times the diameter of the wire), with respect to the end of the electrode tungsten torch TIG,
• the transfer of metal to the weld joint is effected by successive molten metal droplets, said droplets being deposited at a frequency of between 20 Hz and 90 Hz, and the size of the drops being equal, for these frequencies respectively, 1.5 to 4 times the diameter of the fuse wire.
• droplet transfer it is meant that the transfer of metal from the end of the wire to the solder bath or brazing is by successive droplets, dissociated from each other and therefore without permanent contact between the filler wire and the molten metal.
• Tables 1 and 2 have been schematized in the attached FIG. 2 which represents a drop transfer according to the present invention obtained with a stainless steel grade wire ER308LSi and a diameter of 1.2 mm determined by: fairly open range of wire speed (diameter equal to 1.2 mm) ranging from
• Vfil minimum wire speed
• TG drop size
• FT transfer frequency
• Table 3 shows a way to adapt the drop transfer according to the invention for different configurations of joints and two types of aluminum alloys.
• the gait remains the same between clm welding and butt welding with a greater adjustment latitude in butt welding with respect to the electrode / wire distance and the generally higher wire speed.
• the transfer by droplets at a particular frequency according to the invention allows the production of cords whose aesthetic quality is similar to those achieved by manual welding, in particular on aluminum, allowing with this process a reproduction of "solidification waves" surface.
• ARCAL TM 15 is a commercial gas mixture of L'Air Liquide formed from argon and 5% by volume of hydrogen.
• This table 4 demonstrates the advantage of the drop transfer of the invention compared to conventional TIG welding of the prior art, wherein the fusion of the wire is only by conduction in contact with the melt.
• a transfer according to the invention makes it possible to significantly increase the speed of welding (Vs) since, with a transfer by drops according to the invention, the fusion of the wire is accelerated by its passage in the temperature zone of between about 5000 and 10000 0 K which imposes a 40% increase in the wire speed and therefore, a 66% increase in welding speed.
• the maximum wire feed speeds allow welding speeds of the order of 1 to 1.2 m / min.
• ARCAL TM 1 is gaseous argon marketed by L'Air Liquide and ARCAL TM 10 is a commercial gas mixture of L'Air Liquide formed by 2.5% by volume of hydrogen and argon for the remainder.
• the method of the invention may comprise one or more of the following characteristics:
• the droplet transfer frequency is preferably between 30 Hz and 80 Hz.
• the size of the drops is equal to 1.5 to 3 times the diameter of the fuse wire.
• the droplet transfer frequency is between 20 Hz and 40 Hz and the size of the drops is between 3 and 4 times the diameter of the fusible wire, preferably the frequency is of the order of 30 Hz.
• the droplet transfer frequency is the result of a pulse frequency of the wire combined with a pulsating frequency of the direct or alternating current in the case of aluminum and its alloys (or of variable polarity type) which allows more precise control of the welding and stripping phases.
• the droplet transfer frequency is between 70 Hz and 90 Hz and the size of the drops is between 1, 2 and 1.5 times the diameter of the fusible wire, preferably of the order of 80 Hz.
• the supply of fusible wire is operated at an angle between 10 and 30 ° relative to the axis of the electrode, preferably between 10 and 20 °.
• the end of the fuse wire is permanently guided and maintained at a distance of less than 1.5 mm from the end of the tungsten electrode of the TIG torch, preferably at a minimum distance of 1 mm.
• the surface of the end of the wire should not come into contact with the tungsten electrode.
• a gaseous protection is carried out with a gas chosen from argon, helium and argon / helium mixtures with or without micro-additions of nitrogen, and mixtures of argon and hydrogen.
• the method is implemented on a robotic welding arm carrying a TIG torch with a non-fuse electrode and fuse welding wire feeding means or in manual or automatic welding.
• the process is used to weld or braze one or more parts - the parts are in coated steel, in particular in galvanized or electro-galvanized steel, in austenitic or ferritic stainless steel, in nickel and nickel alloys, titanium and alloys titanium, as well as aluminum or aluminum alloys.
• the intensity of the direct current supplying the TIG torch is between 10 A and 400 A Max, and the voltage is between 10 V and 20 V.
• the wire has a diameter between 0 6 mm and 1.6 mm, preferably between 1 mm and 1.2 mm.
• the wire is cupro-sihcium alloy (Q1S1 3 ) or cupro-alummium (CuA18).
• the wire is also made of pure aluminum or aluminum alloy, for example 2000, 4000 or 5000 series.
• part of the energy of the arc is used for the melting of the end of the wire at fairly low wire speeds, typically of the order of 1 to 10 m / min, which explains that per unit of time, this energy will interest a longer wire length and thus give rise to the formation of drops which will be larger when the wire speed is low and the transfer frequency is also low; and vice versa, for a wire speed higher but lower than that of the appearance of a liquid bridge, the size of the drops will decrease and the transfer frequency will increase.
• the parameters, for a given wire diameter are linked by the relation:
• the method of the invention with droplet transfer can be applied to the welding or brazing of any assembly of coated steel, austenitic or ferritic stainless steel parts, nickel and nickel alloys, titanium and titanium alloys, aluminum or its alloys, for which aesthetic conditions are sought or favored, in particular regular striations on the surface of cords or for which important preparation tolerances must be compensated
• the method of the invention is particularly advantageous for welding very thin galvanized sheets, for example less than 1 mm, to promote degassing of ZnO vapors, or welding aluminum or its alloys to promote degassing of H 2 .
• the method of the invention is preferably implemented with a torch with fusible wire passing through the wall of the nozzle at an angle of less than 50 °, in particular the torch described in EP-A-1459831.
• the wire feed which is integrated in the torch, is at an angle of the order of generally 10 ° to 20 °, for example of the order of 15 °, compared to the axis of the non-fusible electrode and this, by maintaining a small distance between the end of the wire and the cone end of the tungsten electrode, for example 1 mm minimum or the diameter of the filler wire
• the end of the fuse wire is guided and also maintained permanently at a distance of less than about 2 mm from the end of the electrode.
• tungsten that is to say that the distance between the outer surface of the fuse wire and the electrode should not exceed 2 mm, preferably greater than 1 mm.
• the preferred wire speed is given according to the various parameters chosen by the operator: material to assemble, nature and diameter of the filler wire, intensity, shielding gas, welding speed ....
• the invention is illustrated in the attached figure which schematizes a transfer by drops according to the invention.
• the hottest part of the electric arc 6 which forms at the tip 7 of the electrode 1 makes it possible to obtain a progressive melting of the end 3 of the wire 2 in the arc zone 5
• the transfer of the molten metal from the end 3 of the wire 2 to the solder bath 8 forming the welded bead on the part 10 is done by successive drops 4 whose drop diameter is between 1.2 and 4 times the diameter.
• the yarn typically has a diameter of between 0.6 and 1.6 mm.
• the frequency of the drops is between 20 and 90 Hz.
• the frequency of the droplets is generated by a pulsation of the wire combined with a pulsation of current.
• the distance D between the tip of the electrode 1 and the surface of the parts to be welded is between 2 mm and 3 mm approximately.
• the minimum distance d between the wire 2 and the surface of the electrode 1, including at its point 7, is kept less than 2 mm but preferably greater than 1 mm.
• the wire speed range for obtaining drop transfer is wide and flexible with respect to the frequency and the size of the corresponding drops.
• the minimum wire speed (min Vf) and maximum wire speed (max Vf) are those to be applied to remain in a drop transfer. Above the maximum value, a liquid bridge transfer is achieved.
• the drop transfer method of the invention can be applied to a variety of joint configurations: butt, lap, angle, and flanged welding, for degraded preparation conditions, such as games or misalignments, as this type of transfer. can absorb more specifically, and finally for reloading operations since it controls the energy provided respectively to the filler wire and the support material.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Arc Welding In General (AREA)

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• 2006
  • 2006-08-03 FR FR0653279A patent/FR2904576B1/fr not_active Expired - Fee Related
• 2007
  • 2007-07-12 AU AU2007280344A patent/AU2007280344A1/en not_active Abandoned
  • 2007-07-12 WO PCT/FR2007/051648 patent/WO2008015353A1/fr active Application Filing
  • 2007-07-12 JP JP2009522309A patent/JP2009545449A/ja not_active Withdrawn
  • 2007-07-12 CA CA002658969A patent/CA2658969A1/fr not_active Abandoned
  • 2007-07-12 US US12/375,318 patent/US20100012638A1/en not_active Abandoned
  • 2007-07-12 EP EP07823570A patent/EP2051831A1/de not_active Withdrawn

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