WO2009016602A2 - Procédé et appareil de soudage - Google Patents

Procédé et appareil de soudage Download PDF

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Publication number
WO2009016602A2
WO2009016602A2 PCT/IB2008/053074 IB2008053074W WO2009016602A2 WO 2009016602 A2 WO2009016602 A2 WO 2009016602A2 IB 2008053074 W IB2008053074 W IB 2008053074W WO 2009016602 A2 WO2009016602 A2 WO 2009016602A2
Authority
WO
WIPO (PCT)
Prior art keywords
welding
lml
electrodes
components
welded
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2008/053074
Other languages
English (en)
Other versions
WO2009016602A3 (fr
Inventor
Luca Moioli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FOCUSWELD Srl
Original Assignee
FOCUSWELD Srl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by FOCUSWELD Srl filed Critical FOCUSWELD Srl
Publication of WO2009016602A2 publication Critical patent/WO2009016602A2/fr
Publication of WO2009016602A3 publication Critical patent/WO2009016602A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/10—Spot welding; Stitch welding
    • B23K11/11—Spot welding
    • B23K11/115—Spot welding by means of two electrodes placed opposite one another on both sides of the welded parts
    • 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
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/14—Projection welding
    • 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
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/24—Electric supply or control circuits therefor
    • B23K11/26—Storage discharge welding
    • 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
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/006—Vehicles

Definitions

  • the present invention concerns a method and an equipment for welding through discharge of a capacitive electric component, that can be used for example to assemble monoques (bodies) or parts of a bodywork of motor vehicles, home appliances or other finished or semifinished products, particularly large scale products.
  • a capacitive electric component that can be used for example to assemble monoques (bodies) or parts of a bodywork of motor vehicles, home appliances or other finished or semifinished products, particularly large scale products.
  • Figure 1 is a perspective view illustrating a welding method according to a first embodiment of the present invention
  • FIG. 2 is a perspective view illustrating a welding gun used in the welding method of Figure 1;
  • Figure 3 is an electric and electronic diagram of a circuit for feeding the welding gun of Figure 2;
  • Figure 4 is a time graph of the welding pulsed current, according to the method shown in Figure 1;
  • Figure 5 is a partially sectioned side view of the components to be assembled through the welding method of Figure 1;
  • Figure 6 is a perspective view of a welding electrode according to a second embodiment of the present invention.
  • Figure 7 is a perspective cross-section view of a welding boss employed in the welding method of Figure 1;
  • Figure 7 A shows a detail of the top transverse cross-section of the ridge of the welding boss of Figures 7 and 8;
  • Figure 7B shows a detail of the top transverse cross-section of the ridge of the welding boss according to a third embodiment of the invention
  • Figure 8 is a perspective view, partially cross-sectioned, of an welding boss used in a fourth embodiment of the invention.
  • Figure 9 is an electrical/mechanical diagram of the welding gun of Figure 2.
  • Figure 1 illustrates a first embodiment of a welding method according to the invention at a given moment.
  • Reference SC generally indicates a partially assembled (semifinished) motor vehicle bodywork - in the illustrated example, an automobile (monocoque) bodywork - to which further metal sheet components are still to be welded.
  • Reference 1 indicates a welding robot of the anthropomorphous type; with references AO, Al, A2, A3, A4 indicating the five controlled axes (freedom degrees) of the robot arm.
  • Reference 3 indicates the base through which the robot arm is secured to the floor of the shop in which it is installed.
  • a welding gun 5 is mounted to the wrist 7 of the robot.
  • the assembling of the bodywork components comprises a welding step through a discharge of capacitors (capacitor discharge welding) or through a discharge of accumulated electrical charges (storage discharge welding).
  • the welding robot 1 is set for performing a capacitor discharge welding and particularly the welding gun 5 is designed and fed to this aim.
  • the gun 5 comprises a frame 70 which in turn comprises a transformer (carrying) frame 72, a lower arm support 74 and an upper arm support 76; with the above mentioned three components being formed either from steel plates or sheets welded together, or more advantageously made of suitable light alloys such as for example Ergal, in order to reduce the gun weight.
  • a lower arm 78 and an upper arm 80 are fixed to the lower arm support 74 and to the upper arm support 76, respectively.
  • the lower arm support 74 and the upper arm support 76 are hinged (pivoted) to one another so as to open and close scissors-like the two arms 78, 80 when they are operated by the pneumatic cylinder 81 or by other suitable actuator: in other words the welding gun 5 is a so-called "pivoted gun.”
  • FIG. 3 is a general diagram of the electric and electronic circuit for feeding the gun 5 and producing a capacitor discharge welding.
  • Such circuit generally indicated by the reference 9, includes:
  • a high voltage feeding stage 92 receiving a three-phase feeding current (e.g. 380 V) through an input line 94 and supplying a DC voltage to a downwardly located bank of capacitors 98;
  • a three-phase feeding current e.g. 380 V
  • an energy storage stage 96 comprising a bank of capacitors substantially formed by a plurality of parallely connected capacitors 98 ;
  • a welding control stage 100 comprising in turn the primary and secondary windings 104, 106 of a transformer 102 and a discharge control system 108; the discharge control system 108 in turn including, in the present embodiment, a thyristor 110 and an electronic control unit 112;
  • a welding stage (or portion) 114 comprising the arms 78, 80 and the electrodes 82, 84 of the welding gun 7;
  • main control unit 116 carrying out several control functions for the above referred stages, such as for example controlling a) the DC voltage level supplied by the feeding stage to the bank of capacitors 98, b) the charging level of the capacitors 98, and actuating c) the discharge control system 108, and d) detecting and controlling the gripping force of the arms 78, 80 onto the components to be assembled, and the welding current circulating through the electrodes 82, 84 during the discharge and the position of the electrodes.
  • the transformer 102 or rather more particularly its primary and secondary windings 104 and 106, are mounted aboard the gun 5, that is they are secured to the frame 72 carrying the transformer, so that they can be moved together with the remaining of the gun 5 by the wrist of the robot 1.
  • the above mentioned feeding stage 92 and energy storage stage 96 are housed inside an electric closet resting on the floor of the shop in which the robot 1 is installed.
  • the operation of the welding robot 1 and of the welding gun 5 is as follows.
  • the welding robot 1 moves the welding gun 5 with the transformer 102 on board, so as to position the electrodes 82, 84 of the gun astride of the two components LMl, LM2 to be assembled, which in the present embodiment are two metal sheet components of the bodywork SC of a motor vehicle ( Figures 1, 5).
  • the pneumatic cylinder 81 actuates the arms 78, 80 to press the electrode 82 against the sheet component LMl and the electrode 84 against the sheet component LM2, thus packing and gripping together the two components LMl, LM2; in response to a command from the main control unit 116, the thyristor 110 short-circuits the plates of the capacitors 98 through the primary winding 104, thus discharging the capacitors.
  • the (high voltage) current circulating through the primary winding 104 during the discharge induces a (lower voltage) current circulating through the so-called “welding (or circuit) coil” SP ( Figure 9), which coil is made up by the secondary winding 106 of the transformer, by the arms 78, 80 of the gun, by the electric conductors (not shown) connecting such arms 78, 80 to the secondary winding 106, by the electrodes 82, 84 as well as by the components LMl and LM2 to be welded.
  • FIG. 4 is a qualitative time diagram of the current circulating in the welding coil SP during a discharge step. The time in milliseconds is marked on the abscissa axis and the current (in kA) on the ordinate axis.
  • the arms 78, 80 are opened and the electrodes 82, 84 are taken away from the components LMl, LM2 now welded together, and the gun is available for a new welding cycle.
  • the capacitors 98 are being recharged through the feeding stage 92.
  • this capacitor discharge welding technique it is possible to assemble the various metal sheet components of the bodywork of a motor vehicle or of other finished or semifinished products, by directly achieving a high finish welding that is practically invisible to a common observer, i.e. an observer not experienced with welding techniques or quality control; in other words thanks to this capacitor discharge welding, the visible parts of a motor vehicle bodywork can be welded together, as well as other finished or semifinished products - such as for example doors, trunk (boot) hoods or engine compartment hoods of motor vehicles, frames and carters of appliances and other products, particularly large scale products - without requiring subsequent finishing operations to eliminate the unaesthetic marks of the welding.
  • other finished or semifinished products - such as for example doors, trunk (boot) hoods or engine compartment hoods of motor vehicles, frames and carters of appliances and other products, particularly large scale products - without requiring subsequent finishing operations to eliminate the unaesthetic marks of the welding.
  • the contact (welding) electrode heads 82, 84 of the welding gun - in the present description also named “electrode heads” - have a substantially convex and rounded shape, e.g. they are shaped as a spherical cap.
  • the substantially convex and rounded shape of the electrode heads allows to perform a high finish welding in spite of the fact that the tolerances (along the vertical direction) that can be obtained using a welding gun 5 fixed to a robot arm in respect to the components to assemble, are of a greater coarseness than those obtainable with a conventional welding press secured to the ground.
  • the bending radiuses Rl, R2 of the electrode heads are in the range of about 80-100 mm and 300 mm, ends inclusive, in order to achieve appreciable aesthetical results.
  • the bending radiuses Rl, R2 of the electrode heads are comprised between about 120 mm and 300 mm both ends inclusive: the best aesthetical results being achieved with bending radiuses larger than about 120 mm, and such results comply for example with the standards of some motor vehicle manufacturers.
  • Rl, R2 equal to about 200 mm, in particular these weldings are practically invisible, or however quite difficult to be noticed.
  • Electrodes 82, 84 have preferably diameters Dl, D2 equal to or larger than 15 mm.
  • the diameters Dl, D2 of the electrodes are between about 20 mm and 30 mm.
  • the diameters Dl, D2 of the electrodes are preferably equal to or larger than the double of the diameter DB of the annular boss: this allows for an easier centering of the welding annular boss 118 in respect of the welding gun.
  • Figure 9 is an electrical-mechanical diagram of the arms 78, 80 of the welding gun 5 and of the electric circuit located between the secondary winding 106 of the transformer 102 and the welding electrodes 82, 84.
  • References 120, 122 indicate ribbon-like conductors for electrically connecting the secondary winding 106 of the transformer with the welding electrodes 82 and 84, respectively, and allowing the current flow during the welding.
  • the current of the low voltage circuit circulates through the coil (or circuit) made up by the secondary winding 106 of the transformer, the two ribbon-like conductors 120, 122, the arms 78, 80, the electrodes 82, 84, the portions of the components LMl, LM2 affected by the welding, and by the possible electric arc between the electrodes and the components to be welded LMl, LM2 (not shown in Figure 9).
  • Such coil is indicated in Figure 9 by the general reference SP.
  • the area of the welding coil SP has to be equal to or lower than about 0.15 m 2 ; more preferably, the area of the welding coil SP is equal to or lower than about 0.1 m 2 : as a matter of fact for a small-area welding coil SP the peaks of the welding current (Figure 4), with a given energy, are shorter and of increased height (value), bringing about an improved melting of the metal pieces to be joined together.
  • the area of the welding coil SP is measured with reference to the closed arms of the gun and to the surfaces of the conductors of the coil facing the inside of the coil (see the hatched area in Figure 9).
  • one or more welding projections or "bosses” are formed on one of the two parts to be welded together.
  • bosses can be formed through cold moulding (drawing).
  • Figures 5 and 7 show a first embodiment of a welding boss that is particularly advantageous for assembling bodywork or other body components through a capacitor discharge welding, such boss being a so- called “annular boss", having the shape of a circular ring member 118: such boss is formed with a ridge having a circular shape when viewed from above which is obtained through cold drawing of the sheet component LMl to be assembled.
  • the vertical cross section of such ridge can be substantially triangular or trapezoidal as shown for example in Figure 7.
  • the diameter DB of the annular boss 118 is chosen on the base of the characteristics desired for the welding - such as for example the tensile stress and the shear resistance.
  • Figure 8 shows a second embodiment of a welding boss - a so-called "linear boss" 118' - that is particularly advantageous when assembling bodyworks or other parts of a bodywork through a capacitor discharge welding: such boss comprises a ridge the profile of which is no closed, in the present embodiment being a substantially rectilinear extending ridge.
  • linear boss 118' can be formed, for example, through a cold drawing process from the metal sheet component LMl to be assembled.
  • the vertical cross section of the ridge can be substantially triangular or trapezoidal as shown in Figure 8, with a span angle ⁇ ' or an inclination angle equal ⁇ '/ 2 that are the same or similar to those the annular boss 118.
  • a linear boss, and particularly a rectilinear boss in some cases - for example for joining together two pieces LMl and LM2 to be welded with not strictly precise planar tolerances - allows for better aesthetical results than those provided for by an annular boss or anyhow by a closed boss.
  • the ridge top of a welding boss according to the invention preferably has either a rounded cross section (Figures 7, 7A) or a flat one ( Figure 7B): which shape allows for a better starting contact between the two pieces LMl and LM2 to be welded, thus improving the beginning step of the melting process, and therefore providing for a more resistant welding.
  • the bending radius RS of the ridge rounded cross section is preferably of a few tenths of mm, indicatively 0.1-0.2 mm or larger, if possible;
  • the ridge width LS is of a few tenths of mm, indicatively 0.2-0.3 mm.
  • a welding boss according to the invention preferably projects from the surface of the component to be assembled and on which it has been drawn, by a height HB, HB 1 ( Figures 7, 8) which is preferably comprised between 0.6 and 0.8 mm; still more preferably the height HB, HB' is equal to about 0.7 mm.
  • HB, HB 1 Figures 7, 8
  • Such nominal values of the boss height allow to join together, with a quite strong and high finish welding, metal sheet components LMl, LM2 having a thickness comprised between 0.7 mm and 2 mm, still using a relatively low discharge energy.
  • the span angle " ⁇ " of the ridge is lower than 90°- 100°, and still more preferably is comprised between 60° and 90°; with such values of the span angle " ⁇ " corresponding to a side slope " ⁇ /2" preferably lower than 45°-50°, and still more preferably comprised between 30° and 45° ( Figures 7, 8).
  • Such values of the opening angle " ⁇ " and of the side slope "a/2" allow for a good penetration of the boss 118, 118' into the material of the other component LM2 during the melting, and correspondingly a good resistance of the welded joint, in spite of using a relatively low discharge energy.
  • the dimensional values of the bosses reported in the present description - such as for example the opening " ⁇ ", the heights BH, HB 1 , the diameter DB etc. - are to be meant as nominal values, and therefore when carrying out the invention some deviations of the effective values of the boss are to be taken into account, due for example to the moulding tolerances and to the mould wear off.
  • the above disclosed teachings allow to carry out a capacitor discharge welding with robotized welding lines and welding guns carried by robots, i.e. using techniques until now employed for resistance and wire welding.
  • the capacitors 98 can be replaced in general by one or more capacitive electric components of a different type, as long as they are capable of releasing the stored electric charge at a sufficiently high speed; in carrying out the present invention besides the "pivoted" gun welding 5 shown in the Figures, also other types of guns, such as for example a so-called “slider” gun (not shown) can be used, and when this latter can be used better aesthetical results are obtained than those obtained with a pivoted gun.
  • a so-called “slider” gun not shown
  • the above examples and list of possible variations of the present question are not to be meant as exhaustive.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Resistance Welding (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Abstract

L'invention concerne un soudage des parties visibles de la carrosserie d'un véhicule à moteur (SC) réalisé par un soudage par décharge de condensateur. Un pistolet de soudage (5) est déplacé conjointement avec un transformateur d'impulsions par le bras d'un robot (1). A l'aide d'une bobine de soudage de dimension réduite et d'un bossage de soudage ayant des formes et dimensions correctes, le rendement de fonctionnement du transformateur et du pistolet (5) est amélioré, ce par quoi les deux dispositifs peuvent être réalisés légers et compacts, et fixés au poignet du bras de robot (1). A l'aide d'un soudage par décharge de condensateur, et de têtes d'électrode de forme appropriée, les surfaces soudées sont à peine visibles ou complètement invisibles pour l'utilisateur final du véhicule.
PCT/IB2008/053074 2007-08-01 2008-07-31 Procédé et appareil de soudage Ceased WO2009016602A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO2007A000573 2007-08-01
IT000573A ITTO20070573A1 (it) 2007-08-01 2007-08-01 Metodo e attrezzatura per saldatura

Publications (2)

Publication Number Publication Date
WO2009016602A2 true WO2009016602A2 (fr) 2009-02-05
WO2009016602A3 WO2009016602A3 (fr) 2009-06-11

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PCT/IB2008/053074 Ceased WO2009016602A2 (fr) 2007-08-01 2008-07-31 Procédé et appareil de soudage

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IT (1) ITTO20070573A1 (fr)
WO (1) WO2009016602A2 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1990123A3 (fr) * 2007-05-09 2009-11-11 Nimak GmbH Procédé de soudure par points, pince de soudage par points et liaison de soudage par points
ITBO20120246A1 (it) * 2012-05-07 2013-11-08 Tecna Spa Dispositivo di controllo e gestione della corrente elettrica, per macchine di saldatura a resistenza.
US20140062133A1 (en) * 2012-09-03 2014-03-06 Edward Schleichert Impact Beam
DE102017116089B4 (de) 2017-07-18 2023-11-30 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Roboterschweißzange

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB593459A (en) * 1942-07-27 1947-10-17 Budd Edward G Mfg Co Improvements in or relating to resistance welding method and resistance welded article
US5128511A (en) * 1990-02-06 1992-07-07 Pulsair Anstalt Welding apparatus and transformer therefor

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1990123A3 (fr) * 2007-05-09 2009-11-11 Nimak GmbH Procédé de soudure par points, pince de soudage par points et liaison de soudage par points
ITBO20120246A1 (it) * 2012-05-07 2013-11-08 Tecna Spa Dispositivo di controllo e gestione della corrente elettrica, per macchine di saldatura a resistenza.
US20140062133A1 (en) * 2012-09-03 2014-03-06 Edward Schleichert Impact Beam
US20140077522A1 (en) * 2012-09-03 2014-03-20 Edward Schleichert Bumper Beam With Losing Plate Joined Using CD Welding (Capacitor Discharge)
US9180760B2 (en) * 2012-09-03 2015-11-10 Magna International Inc. Bumper beam with losing plate joined using CD welding (capacitor discharge)
US9180759B2 (en) * 2012-09-03 2015-11-10 Magna International Inc. Impact beam
DE102017116089B4 (de) 2017-07-18 2023-11-30 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Roboterschweißzange

Also Published As

Publication number Publication date
WO2009016602A3 (fr) 2009-06-11
ITTO20070573A1 (it) 2009-02-02

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