WO2020206923A1 - 复合焊连续焊接方法及装置、焊接成品、车体 - Google Patents

复合焊连续焊接方法及装置、焊接成品、车体 Download PDF

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Publication number
WO2020206923A1
WO2020206923A1 PCT/CN2019/104848 CN2019104848W WO2020206923A1 WO 2020206923 A1 WO2020206923 A1 WO 2020206923A1 CN 2019104848 W CN2019104848 W CN 2019104848W WO 2020206923 A1 WO2020206923 A1 WO 2020206923A1
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Prior art keywords
laser
welding
weldment
groove
arc
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PCT/CN2019/104848
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English (en)
French (fr)
Inventor
韩晓辉
毛镇东
高月欣
郑凯
李刚卿
Original Assignee
中车青岛四方机车车辆股份有限公司
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Priority to EP19917520.9A priority Critical patent/EP3750665B1/en
Priority to JP2020548729A priority patent/JP2021521009A/ja
Priority to US17/047,685 priority patent/US11931826B2/en
Publication of WO2020206923A1 publication Critical patent/WO2020206923A1/zh

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    • 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
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/346—Working by laser beam, e.g. welding, cutting or boring in combination with welding or cutting covered by groups B23K5/00 - B23K25/00, e.g. in combination with resistance welding
    • B23K26/348—Working by laser beam, e.g. welding, cutting or boring in combination with welding or cutting covered by groups B23K5/00 - B23K25/00, e.g. in combination with resistance welding in combination with arc heating, e.g. TIG [tungsten inert gas], MIG [metal inert gas] or plasma 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
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
    • B23K26/046—Automatically focusing the laser beam
    • B23K26/048—Automatically focusing the laser beam by controlling the distance between laser head and workpiece
    • 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
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/70—Auxiliary operations or equipment
    • B23K26/702—Auxiliary equipment

Definitions

  • the present disclosure relates to the technical field of laser arc welding, in particular to a continuous welding method and device for hybrid welding, a welding product, and a car body.
  • Aluminum alloy has the advantages of high specific strength, good corrosion resistance, good plasticity, and easy processing and forming. It is widely used in car body manufacturing in the lightweight structure design of high-speed trains. Based on the needs of the integral load-bearing car body structure of high-speed trains, hollow aluminum alloy profiles are widely used in car body manufacturing and formed into a whole through tailor welding. Compared with the traditional arc welding method for welding aluminum alloy, the use of laser-arc hybrid welding method to weld aluminum alloy has strong focusing characteristics, with high energy density, fast welding speed, small welding deformation, good joint performance, and increasingly extensive engineering applications .
  • the laser welding in hybrid welding usually has no defocus or a small amount of defocus. Therefore, the laser spot falling on the surface of the workpiece is small and the energy density is large, and the laser produces the "pinhole effect" "Highlight.
  • the main driving force for maintaining the small hole is the recoil pressure of the metal vapor against the back wall. As more metal is melted, a large amount of metal vapor generated in the molten pool impacts the back wall of the molten pool, causing the molten pool to oscillate. Metal splashing is caused. If there is not enough metal to fill the weld seam and the small hole collapses, a "small hole” pore will be formed. At the same time, the laser welding speed is fast, and the air bubbles are easily formed during the cooling and solidification process. Shown in Figure 4 and Figure 5. The traditional laser-arc hybrid welding process will cause defects such as porosity and poor fusion in the weld.
  • the small hole does not penetrate the backing plate during the laser welding process, which is a typical blind welding structure.
  • the traditional laser welding process with small defocus or zero defocus has a larger depth-to-width ratio of the molten pool, a smaller molten pool, and a higher welding speed. This results in a faster cooling and crystallization rate of the molten pool, which is not conducive to the floating and escaping of bubbles and pores.
  • the existence of not only reduces the effective bearing area of the welded joint, but also causes local stress concentration, thereby reducing the strength and toughness of the welded joint, and seriously affecting the service life of the welded joint. Therefore, for butt welding of aluminum alloy with backing plate, the pore defect is still an unavoidable problem in the laser welding process.
  • the laser spot produced by the laser welding joint is usually very small (the spot diameter is less than 0.6mm) , The size of the small hole produced is also smaller (the diameter of the small hole is less than 1mm).
  • the embodiments of the present disclosure provide a composite welding continuous welding method and device, a welded product, and a car body, so as to solve the problem that welding pores are difficult to escape in the prior art, and effectively improve welding stability and reliability.
  • the present disclosure provides a hybrid welding continuous welding method, which includes: performing hybrid welding on the groove of the weldment by coupling a laser and a variable polarity arc; wherein the defocus of the laser is not less than Rayleigh length of the laser.
  • the laser is incident perpendicularly or obliquely to the groove from the front surface of the weldment, and the variable polarity arc acts on the groove from the side of the laser.
  • variable polarity arc acts on the groove from the rear side of the laser.
  • the spot of the laser is located on the groove to form a weld hole in the weld at the groove, and
  • the focal point of the laser light is located above the light spot, the defocus amount of the laser light is the distance between the focal point and the light spot, and the defocus amount of the laser light is greater than the Rayleigh length of the laser light.
  • the defocus amount of the laser is H and the Rayleigh length of the laser is Z R , then H>2Z R.
  • the method further includes:
  • a welding wire is filled into the groove to melt the welding wire in the groove to form a weld.
  • the present disclosure also provides a continuous welding device for hybrid welding, which includes:
  • An arc welding part for generating a variable-polarity arc, the arc welding part and the laser welding part are combined side-by-side, so that the laser and the variable-polarity arc are coupled to perform compound welding on the groove of the weldment ;
  • the control mechanism is respectively connected with the laser welding part and the arc welding part, and the control mechanism is used to control the laser welding part so that the defocus amount of the laser is not less than the Rayleigh length of the laser, and is used
  • the arc welding part is driven to generate a variable polarity arc.
  • the device further includes a wire feeding mechanism, and the wire feeding mechanism is compositely mounted on the side surface of the laser welding part through a side shaft.
  • the present disclosure also provides a welded product, which includes a first weldment and a second weldment with a lock bottom.
  • the first weldment is located on the lock bottom and butts with the second weldment.
  • a groove is formed at the butt joint of the first weldment and the second weldment, and a weld is formed at the groove by the method described above.
  • the present disclosure also provides a vehicle body including the welded product as described above.
  • the composite welding continuous welding method of the present disclosure includes: performing composite welding on the groove of the weldment by coupling a laser and a variable polarity arc; wherein the defocusing amount of the laser is not less than the Rayleigh length of the laser.
  • the method of the present disclosure couples the laser with the variable polarity arc, and increases the defocus amount of the laser beyond the Rayleigh length range, thereby effectively reducing the power density of the laser on the surface of the weldment and reducing the aspect ratio of the weld.
  • Fig. 1 is a welding state diagram of a hybrid continuous welding method according to an embodiment of the disclosure
  • Figure 2 is a partial enlarged view at I in Figure 1;
  • Fig. 3 is an analysis diagram of the Rayleigh length of the laser according to an embodiment of the disclosure.
  • Fig. 4 is a topography view of a weld in a comparative example in the embodiment of the disclosure.
  • Fig. 5 is a cross-sectional view of a weld in a comparative example in an embodiment of the disclosure.
  • Fig. 6 is a weld morphology diagram of an experimental example of a hybrid continuous welding method according to an embodiment of the disclosure
  • FIG. 7 is a cross-sectional view of a weld seam of an experimental example of the hybrid continuous welding method according to the embodiment of the disclosure.
  • plural means two or more.
  • the terms “upper”, “lower”, “left”, “right”, “inner”, “outer”, “front end”, “rear end”, “head”, “tail”, etc. indicate the orientation or positional relationship:
  • the orientation or positional relationship shown in the drawings is only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood To limit the present disclosure.
  • the terms “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
  • connection should be interpreted broadly. For example, they can be fixed or detachable. Connected or integrally connected; it can be mechanically or electrically connected; it can be directly connected or indirectly connected through an intermediate medium.
  • connection should be interpreted broadly. For example, they can be fixed or detachable. Connected or integrally connected; it can be mechanically or electrically connected; it can be directly connected or indirectly connected through an intermediate medium.
  • connection should be interpreted broadly. For example, they can be fixed or detachable. Connected or integrally connected; it can be mechanically or electrically connected; it can be directly connected or indirectly connected through an intermediate medium.
  • the composite welding continuous welding method provided by this embodiment includes: performing composite welding on the groove of the weldment by coupling a laser and a variable polarity arc.
  • the defocus amount H of the laser light is not less than the Rayleigh length Z R of the laser light.
  • the method can use laser-variable polarity hybrid welding to achieve continuous welding of the weldment to be welded, and use the energy coupling effect of hybrid welding to ensure welding stability, and at the same time expand the defocus of the laser beyond the Rayleigh length range of the laser, thereby It solves the problem that welding pores are difficult to escape in the prior art, and effectively improves welding stability and reliability.
  • the laser produced by it has no defocus or the defocus amount H is small, the laser spot 9 falling on the surface of the workpiece is smaller (the diameter of the spot 9 is less than 0.6mm), and the energy density of the laser (power density ) Is larger, the "small hole effect" is prominent.
  • the main driving force for maintaining the small hole is the recoil pressure of the metal vapor against the back wall. Due to the higher energy density (power density) of the laser, more metal is melted, and a large amount of metal vapor is generated in the molten pool in the weld. These metal vapors continuously impact the back wall of the molten pool and cause the molten pool to oscillate.
  • the method of the embodiment of the present disclosure utilizes the coupling effect between the laser and the variable polarity arc to perform compound welding on the groove of the weldment by means of laser-variable polarity arc hybrid welding.
  • the power density of the laser on the surface of the weldment is effectively reduced, the aspect ratio of the weld is reduced, and the weld hole 8 is increased.
  • Diameter to enhance the stability of hybrid welding and at the same time, it can effectively reduce the holes caused by the small hole collapse phenomenon of the welding molten hole 8, thereby solving the problem of welding pore defects difficult to escape in the prior art, and reducing the generation of hydrogen holes.
  • the width of the weld produced on the weldment is 2 to 3 times larger than that of the traditional laser-arc hybrid weld.
  • the method described in this embodiment can effectively solve the problems of pores and forming of aluminum alloy plates during laser welding, and can enhance the stability and reliability of laser arc welding. It is suitable for continuous welding of longer and larger thin-walled parts.
  • a high-speed train body usually involves a docking structure with a lock bottom.
  • the structure of the butt joint structure refer to the structure of the welded product described below.
  • this kind of gasket is designed to be integrated with the end of one of the weldments, and the end of the other weldment is overlapped on the gasket, and the ends of the two weldments are butt-joined.
  • a groove to be welded is formed at the butt joint of the parts, and this butt joint structure is called a "butt joint structure with a lock bottom", and the gasket is the lock bottom.
  • the above-mentioned butt joint structure with lock bottom (that is, the following welded product) is a typical blind welding structure.
  • the weld pool aspect ratio of the welding will be too large, the molten pool volume is too small, and the welding speed is too high, resulting in The cooling and crystallization speed of the molten pool is too fast, which is not conducive to the floating and escaping of bubbles.
  • the pore defect caused by welding is still an unavoidable problem in the welding process.
  • changing the laser defocus amount H will have an important influence on the welding quality. Specifically, if the other parameters are fixed during welding, the change of the laser defocus H can directly change the diameter of the laser spot 9 on the surface of the weldment, thereby affecting the amount of heat input to the surface of the weldment during the welding process. Too small defocus H will cause many adverse effects on welding quality and welding process, including the following two aspects:
  • the defocus amount H when the defocus amount H is small, a higher laser power density will be generated on the surface of the weldment, and within a microsecond time range, the surface of the weldment can be heated to the boiling point, thereby generating a large amount of vaporized metal vapor, and At the same time, the high-concentration gas moves the liquid-phase metal to the edge of the molten pool, forming a depression in the center of the molten pool, which is not conducive to the stability of the weld hole 8 and is very easy to produce pores and forming defects in the molten pool.
  • the method of this embodiment increases the defocus amount H of the laser (laser beam) in hybrid welding to a range not less than the Rayleigh radius of the laser, and will change
  • the polar arc is coupled with the laser, so that the variable polarity arc is used to increase the energy absorption rate of the weldment surface, so as to ensure that the hybrid welding described in this embodiment generates sufficient incident energy on the weldment surface and ensures the weld pool formation of the weld stable.
  • the method of this embodiment is based on the laser-variable polarity arc welding, increasing the defocus amount H of the laser to reduce the power density I on the surface of the weldment, while ensuring the structure of the weld hole 8 is stable, and effectively reducing the weld pool Porosity is generated, and forming defects are reduced, thereby improving the mechanical properties of the final welded product.
  • the laser is injected into the groove of the weldment along the arrow Z direction in FIG. 3.
  • the radius of the saddle waist ie, the position of the laser focal point A as shown in Fig. 3
  • its cross-sectional area S 0 .
  • the Rayleigh length Z R or Rayleigh range in this embodiment refers to the length from point A to point B (ie Z R as shown in Fig. 3), and the radius of the spot 9 at point B
  • the laser cross-sectional area S Z at point B is twice the laser cross-sectional area S 0 at point A.
  • the relationship between the defocusing amount H of the laser and the Rayleigh length Z R is H ⁇ Z R ; preferably, H>Z R ; more preferably, H>2Z R , so that the power density I It is small enough, and further reduces the rate of molten metal in the groove, reduces the generation of bubbles and gives sufficient reaction time for bubble overflow.
  • ⁇ is the spread angle when the laser is scattered to W(Z)
  • ⁇ is the wavelength of the laser beam
  • the laser spot area is correspondingly increased to control the weldment
  • the power density of the laser on the surface decreases accordingly. It takes several milliseconds before the surface metal reaches the boiling point. Before the surface vaporizes, the underlying metal reaches the melting point, which is easy to form a good molten weld in the groove; on the other hand, it can effectively increase the weld.
  • the width of the cross-section 7 is such that the aspect ratio of the weld produced by the method at the groove of the weldment is reduced, and the diameter of the weld hole 8 is correspondingly increased.
  • the hybrid welding described in this embodiment uses the high energy density of the laser to achieve large defocusing (the defocusing amount H reaches beyond the range of the Rayleigh length Z R ) and the large spot 9 (the diameter of the spot 9 reaches 2 mm or more) Laser deep penetration welding with laser arc hybrid welding to form a large keyhole on the surface of the weldment (the diameter of the weld hole 8 reaches 3mm or more). While realizing high-energy and high-speed welding with large penetration depth, small deformation and low stress, it obtains a large melting and wide laser arc composite weld that is different from traditional laser-arc composite weld characteristics, and its weld width is traditional laser-arc composite weld. 2 to 3 times the weld seam, which greatly enhances the gap adaptability and defect suppression capabilities of laser arc hybrid welding.
  • variable polarity arc is used as the laser coupling heat source to utilize the coupling effect of the variable polarity arc and the laser. Act on the groove of the weldment, so as to realize the stable and continuous welding of the groove of the weldment.
  • variable-polarity arc makes full use of the characteristics of the forward and reverse current values and the adjustable duty cycle to maximize the enhancement of cathode atomization to clean the oxide film on the surface of the weldment.
  • the welding process can greatly reduce the generation of hydrogen holes in the weld; on the other hand, the introduction of variable polarity arcs stabilizes the welding process, enhances the gap adaptability and the positioning weld penetration capability, and enhances engineering adaptability At the same time, the alternating positive and negative polarity of the variable-polarity arc plays a key role in ensuring the continuous and stable welding of the thin-walled aluminum alloy parts.
  • the alternating positive and negative polarity process of the variable polarity arc can effectively cool the tungsten electrode joint of the arc welding part 5, thereby further reducing the welding heat input, and can increase the energy absorption rate on the surface of the weldment.
  • the stability of Jiao’s laser welding provides a further guarantee; at the same time, the positive polarity of the arc has a cathodic atomization effect, which can fully clean the oxide film on the surface of the weldment, and its negative polarity can protect the arc tungsten electrode from being effectively cooled, thereby Form the continuous, stable and high-quality welding ability of butt weldments.
  • the laser is incident perpendicularly or obliquely from the front of the weldment to the groove, and the polarized arc acts on the groove from the side of the laser to make the laser and the groove
  • the polar arcs constitute a paraxial composite structure relationship.
  • the variable polarity arc is applied to the groove from the rear side of the laser.
  • the laser beam before the arc can make the upper surface of the weld uniform and full and beautiful, and when the arc is after the laser, the heat source on the surface of the weldment acts on a larger area.
  • the weld cools more slowly, which is beneficial
  • the gas in the molten pool overflows to avoid bubbles remaining in the weld and affect the welding quality; in addition, the heat source of the arc is located on the back side of the laser, which is equivalent to a tempering of the weld, which further improves the joint strength of the weld.
  • the spot 9 of the laser is located on the groove to form a weld hole 8 in the weld at the groove.
  • the defocus amount H of the laser is the distance between the focal point A and the spot 9, and the focal point A of the laser is located above the spot 9, that is, the defocus amount H of the laser is greater than 0, and the defocus amount H of the laser Greater than the Rayleigh length Z R of the laser.
  • the method described in this embodiment further includes: filling the groove with welding wire while the laser and the variable polarity arc are performing compound welding on the groove, so as to melt the welding wire in the groove to form a weld. It is preferable to fill the welding wire in the groove from the front side of the laser, that is, the welding wire is first placed in the groove, and then the coupling of the laser and the arc is used to act on the welding wire in the groove to melt the welding wire and fill the groove to form a weld.
  • the laser is first used to perform deep penetration welding on the weldment; the variable polarity arc is later used to preheat and stabilize the arc in the groove of the weldment during welding, thereby increasing the laser energy
  • the utilization rate enhances the interaction of the two heat sources of laser and arc, and greatly reduces the laser energy loss caused by the high reflectivity of the aluminum alloy material itself.
  • the variable polarity arc makes full use of the forward and reverse current values and the adjustable duty cycle, which maximizes the effect of cathode atomization to clean the surface oxide film, reduces the generation of hydrogen holes on the surface of the weld, and can further reduce Welding heat input, reduce the aspect ratio of the weld to improve its stability.
  • this embodiment also proposes a continuous welding device using hybrid welding.
  • the device uses the above-mentioned method to weld the weldment.
  • the device includes a laser welding part 4 for generating laser light, an arc welding part 5 for generating a variable polarity arc, and a control mechanism.
  • the arc welding part 5 and the laser welding part 4 are combined side-by-side, so as to use the aforementioned continuous welding method to couple the laser and the variable polarity arc to perform compound welding on the groove of the weldment.
  • the spot position of the laser emitted by the laser welding part 4 is used as the current welding point, and the arc generation joint of the arc welding part 5 points to the current welding point, so that the coupling of the laser and the variable polarity arc is used to make the same position in the groove ( That is, the welding wire at the current welding point is melted to fill the groove with the welding wire to form a weld.
  • the control mechanism is connected to the laser welding part 4 and the arc welding part 5, respectively. The control mechanism is used to control the laser welding part 4 so that the defocus amount H of the laser is not less than the Rayleigh length Z R of the laser, and is used to drive the arc welding part 5 to generate a variable polarity arc.
  • the laser beam generated by the laser welding part 4 is one of CO 2 laser, fiber laser or semiconductor pulse laser, and the variable polarity arc generated by the arc welding part 5 may be a non-melting electrode (TIG) arc or a plasma arc. (PA).
  • TOG non-melting electrode
  • PA plasma arc.
  • Paraxial composite means that the laser beam and the arc act together at the same position of the weldment at a preset angle, thereby performing composite welding at this position. It is understandable that, when performing hybrid welding, in addition to paraxial composite between the laser welding part 4 and the arc welding part 5, a coaxial composite structure can also be used, that is, the inside and outside of the laser welding part 4 and the arc welding part 5 Nested and coaxially arranged, so that the laser and the arc are in the same position coaxially acting on the weldment.
  • the device of this embodiment has a dedicated welding nozzle position structure. Specifically, as shown in FIG. 1, based on the laser direction emitted by the laser welding part 4, the wire feeding mechanism 6 is placed in front of the laser welding part 4 to form the welding wire front, and the arc welding part 5 is placed in the laser welding.
  • the rear part of the part 4 is arranged to form an arc rear, which utilizes the coupling between the variable polarity arc and the laser and acts together on the front welding wire.
  • the variable polarity arc plays a role in preheating and stabilizing the laser.
  • the laser is incident vertically or obliquely from the front of the weldment, the polarized arc is combined with the laser paraxially, and the welding wire is fed and melted to act on the weldment by two heat sources. In the same position of the groove, a molten pool is formed at that position.
  • the distances between the welding wire of the above-mentioned wire feeding mechanism 6 and the laser of the laser welding part 4, and the distance between the laser of the laser welding part 4 and the variable polarity arc of the arc welding part 5 are 0.5mm-1mm and 2mm-3mm, respectively ,
  • the relative inclination angle based on the laser is 25°-30° and 30°-40°.
  • the above-mentioned nozzle position structure can enhance the cooling effect of the nozzle of each welding part, and improve the continuous welding ability of the nozzle.
  • the laser beam is welded with a defocus of not less than twice the Rayleigh length Z R.
  • the defocus amount H of the laser beam is not less than 10 mm; it is further preferable to use a defocus amount H of 10 mm to 20 mm for welding.
  • the range of the defocus amount H satisfies the requirement of exceeding the range of the Rayleigh length Z R and not less than twice the Rayleigh length Z R.
  • the diameter of the spot 9 acting on the surface of the weldment is increased to 2mm and above, the diameter of the weld hole 8 is further increased to 3mm and above, and the width of the weld is not less than 9mm, then
  • the aspect ratio of the weld is appropriately reduced, and the surface area of the weld hole 8 is greatly increased to enhance the stability of continuous welding.
  • the pores in the weld can effectively escape and the weld formation and welding quality are significantly improved.
  • this embodiment also provides a welding product.
  • the welded product includes a first weldment 1 and a second weldment 2 with a lock bottom 3.
  • the first weldment 1 is located on the lock bottom 3 and is connected to the second weldment 2.
  • the first weldment 1 and the second weldment The butt joint of 2 is grooved, and the welding seam is formed at the groove by the continuous welding method as described above.
  • the lock bottom 3 is used as a protective structure for the bottom of the groove of the welded product. It uses the above-mentioned continuous welding method to connect the first weldment 1 and the second weldment 2 and between the first weldment 1 and the lock bottom 3. Tight welding effectively improves the structural strength and mechanical properties of the welded product.
  • the limited thickness range of the first weldment 1 and the second weldment 2 are both 2mm ⁇ 6mm. This is because when the thickness of the weldment exceeds 6mm, it is easy to cause the laser required for welding.
  • the power is greatly increased, the heat input is increased, the stability of the molten pool is reduced, and the porosity and welding defects are increased. Therefore, the continuous welding method of the embodiment of the present disclosure is more suitable for welding aluminum alloy profiles with a thickness of 2-6mm. The parts are welded to obtain the corresponding welded products.
  • This embodiment also proposes a vehicle body.
  • the car body includes the welded product as described above.
  • the comparative example described in this experiment adopts conventional laser-arc hybrid welding, and the experimental example described in this experiment adopts the hybrid continuous welding method described in this embodiment.
  • the comparative example and the experimental example both use two plates with a thickness of 4mm and a material of 6 series aluminum alloy as the first weldment 1 and the second weldment 2, and the second weldment 2 is connected to the first weldment 1.
  • a lock bottom 3 is provided at the butt end.
  • the laser power E 1 4500 W
  • the arc current is 220 A
  • the welding speed is 5 m/min
  • the speed of the wire feeding mechanism 6 is 5 m/min
  • the laser defocus amount H of the laser welding part 4 is 0.
  • the macro morphology of the front side of the weld of the comparative example is shown in Figure 4, and the macro morphology of the cross section of the weld of the comparative example is shown in Figure 5.
  • the welding parameters of the hybrid continuous welding method are:
  • the laser power E 2 6500W
  • the arc current is 230A
  • the welding speed is 4.8m/min
  • the wire feeding speed is 5.5m/min
  • the laser defocusing amount H is +15mm.
  • the macro morphology of the front side of the weld obtained in this experimental example is shown in Figure 6, and the macro morphology of the cross-section of the weld obtained in this experimental example is shown in Figure 7.
  • the weldment of the comparative example obtained by conventional laser-arc hybrid welding has a relatively large weld seam height, about 1.5mm-2mm; the welded seam section 7 has a narrow melting width, about At the same time, there are many pores visible to the naked eye in the weld cross section 7, and the weld pool in the weld, the weld hole 8 and the joint of the weldment groove are formed unstable.
  • the weldment of the experimental example obtained by the continuous welding method described in this embodiment has a relatively small weld reinforcement, about 0.5mm to 1mm; the weld width of the weld section 7 It is wider, about 8mm-9mm; at the same time, the pore defects in the weld cross-section 7 are basically eliminated, and the weld pool in the weld, the weld hole 8 and the joint of the weldment groove are formed uniformly and stably.
  • the hybrid continuous welding method of the present embodiment includes: coupling the groove of the weldment with a laser and a variable polarity arc to perform hybrid welding; wherein the defocus H of the laser is not less than the Rayleigh length of the laser Z R.
  • the method of the present disclosure couples the laser with the variable polarity arc, and increases the defocus amount H of the laser beyond the range of the Rayleigh length Z R , thereby effectively reducing the power density of the laser on the surface of the weldment and reducing the depth of the weld.
  • the width ratio increases the diameter of the welding hole 8 to enhance the stability of hybrid welding, and at the same time, it can effectively reduce the holes caused by the small hole collapse of the welding hole 8, thereby solving the problem of welding pore defects difficult to escape in the prior art Defects, reduce the generation of hydrogen holes, effectively improve welding stability and reliability, and improve the mechanical properties of the weld.

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  • Engineering & Computer Science (AREA)
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Abstract

一种复合焊连续焊接方法，包括：通过激光和变极性电弧耦合对焊件的坡口处进行复合焊接；其中，激光的离焦量不小于激光的瑞利长度。该方法有效降低激光在焊件表面的功率密度，减小焊缝的深宽比，增加焊接熔孔的直径，有效减少焊接熔孔因小孔塌陷现象引起的孔洞，解决现有技术中焊接气孔缺陷难以逸出的问题，降低氢气孔的产生，有效提高焊接稳定性和可靠性，并提高焊缝的力学性能。还涉及一种复合焊连续焊接装置、一种焊接成品以及一种车体。

Description

复合焊连续焊接方法及装置、焊接成品、车体
相关申请的交叉引用
本申请要求于2019年4月8日提交的申请号为201910277678.7，发明名称为“复合焊连续焊接方法及装置、焊接成品、车体”的中国专利申请的优先权，其通过引用方式全部并入本公开。
技术领域
本公开涉及激光电弧焊接技术领域，尤其涉及一种复合焊连续焊接方法及装置、焊接成品、车体。
背景技术
铝合金具有比强度高、耐蚀性好、塑性好、易于加工成型等优点，在高速列车轻量化结构设计中被大量用于车体制造。基于高速列车整体承载式车体结构的需要，在车体制造中大量采用了中空铝合金型材并通过拼焊形成一体。相比于传统的电弧焊接方法焊接铝合金，利用激光-电弧复合焊接方法焊接铝合金具有很强的聚焦特性，其能量密度高，焊接速度快，焊接变形小，接头性能良好，工程应用日益广泛。
但是目前常见的激光-电弧复合焊接方法用于大长薄壁铝合金部件焊接时，具有以下工程问题：
(1)氧化膜清理不彻底导致的焊接气孔缺陷难以逸出的问题。
传统的激光电弧复合焊接过程中，复合焊中的激光焊接通常无离焦或离焦量很小，因此落在工件表面的激光光斑较小，能量密度较大，则激光产生的“小孔效应”凸显。在激光焊接过程中，维持小孔的主要动力是金属蒸汽对后壁的反冲压力，由于更多金属被熔化，熔池中产生的大量金属蒸气冲击着熔池后壁，引起熔池震荡，造成了金属飞溅，没有足够的金属填补焊缝而造成小孔塌陷，就会形成“小孔型”气孔；同时激光焊接速度快，冷却凝固过程易形成气泡残留在焊缝中成为氢气孔，如图4和图5所示。传统的激光-电弧复合焊接过程会导致焊缝内部易形成气孔、熔合不良等缺陷。
对于高速列车车体用中空型材的带垫板铝合金对接结构，其激光焊接过程中小孔不穿透垫板，为典型的盲焊结构。采用小离焦或零离焦的传统激光焊接工艺，其熔池深宽比更大，熔池体积更小，焊接速度更高导致熔池冷却结晶速度快，不利于气泡的上浮逸出，气孔的存在不仅会降低焊接接头的有效承载面积，而且会使局部造成应力集中，从而降低焊接接头的强度和韧性，严重影响焊接接头的服役寿命。因此对于带垫板铝合金对接焊，其气孔缺陷仍然是激光焊接过程中难以避免的难题。
(2)铝合金表面高反射导致激光-电弧复合焊接过程不稳定、成型不良等工程问题。
在现有的激光-电弧复合焊接方法中，激光焊接会产生“小孔效应”，而现有的激光电弧复合焊接中，由激光焊接接头产生的激光光斑通常很小(光斑直径0.6mm以下)，则其产生的小孔尺寸也较小(小孔直径1mm以下)。由于铝合金车体结构的装配精度要求高，受铝合金自身物理特性及激光焊接小孔效应影响，激光的高反射以及高能焊接过程形成的金属蒸汽挥发造成了激光焊接稳定性变差，容易产生焊接不良等问题；而小光斑形成的小孔焊接也会导致焊接的连续稳定控制难度大；同时，在部件连续焊接过程中的坡口间隙的变化、以及组装定位焊缝的存在也给传统小光斑、小孔式的激光-电弧复合焊接的稳定性、可靠性造成不良影响。
发明内容
(一)要解决的技术问题
本公开实施例提供了一种复合焊连续焊接方法及装置、焊接成品、车体，用以解决现有技术中焊接气孔难以逸出的问题，有效提高焊接稳定性和可靠性。
(二)技术方案
为了解决上述技术问题，本公开提供了一种复合焊连续焊接方法，包括：通过激光和变极性电弧耦合对焊件的坡口处进行复合焊接；其中，所述激光的离焦量不小于所述激光的瑞利长度。
在部分实施例中，所述激光自所述焊件的正面垂直或倾斜的入射至所述坡口处，所述变极性电弧自所述激光的侧面作用于所述坡口处。
在部分实施例中，所述变极性电弧自所述激光的后侧作用于所述坡口 处。
在部分实施例中，所述激光作用于所述焊件的坡口处时，所述激光的光斑位于所述坡口上，以在所述坡口处的焊缝内形成焊接熔孔，所述激光的焦点位于所述光斑的上方，所述激光的离焦量为所述焦点与所述光斑之间的距离，所述激光的离焦量大于所述激光的瑞利长度。
在部分实施例中，所述激光的离焦量为H，所述激光的瑞利长度为Z R，则H＞2Z R。
在部分实施例中，该方法还包括：
在所述激光和所述变极性电弧对所述坡口进行复合焊接的同时，向坡口内填充焊丝，以将所述焊丝熔化于所述坡口内形成焊缝。
本公开还提供了一种复合焊连续焊接装置，该装置包括：
用于产生激光的激光焊接部；
用于产生变极性电弧的电弧焊接部，所述电弧焊接部与所述激光焊接部旁轴复合，以使所述激光和所述变极性电弧耦合对焊件的坡口处进行复合焊接；
控制机构，分别与所述激光焊接部和所述电弧焊接部连接，所述控制机构用于控制所述激光焊接部以使所述激光的离焦量不小于所述激光的瑞利长度，并用于驱动所述电弧焊接部产生变极性电弧。
在部分实施例中，该装置还包括送丝机构，所述送丝机构通过旁轴复合安装在所述激光焊接部的侧面。
本公开还提供了一种焊接成品，该焊接成品包括第一焊件和带锁底的第二焊件，所述第一焊件位于所述锁底上与所述第二焊件对接，在所述第一焊件和第二焊件的对接处形成坡口，利用如上所述的方法在所述坡口处形成焊缝。
本公开还提供了一种车体，包括如上所述的焊接成品。
(三)有益效果
本公开的上述技术方案具有以下有益效果：
本公开的复合焊连续焊接方法包括：通过激光和变极性电弧耦合对焊件的坡口处进行复合焊接；其中，激光的离焦量不小于激光的瑞利长度。本公开的方法将激光与变极性电弧相耦合，并增大激光的离焦量至瑞利长 度范围以外，从而有效降低激光在焊件表面的功率密度，减小焊缝的深宽比，增加焊接熔孔的直径，以增强复合焊接的稳定性，同时能够有效减少焊接熔孔因小孔塌陷现象引起的孔洞，进而解决现有技术中焊接气孔难以逸出的问题，降低氢气孔的产生，有效提高焊接稳定性和可靠性，并提高焊缝的力学性能。
附图说明
为了更清楚地说明本公开实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本公开的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本公开实施例的复合焊连续焊接方法的焊接状态图；
图2为图1中Ⅰ处的局部放大图；
图3为本公开实施例的激光的瑞利长度的分析图；
图4为本公开实施例中对比例的焊缝形貌图；
图5为本公开实施例中对比例的焊缝断面图。
图6为本公开实施例的复合焊连续焊接方法的实验例的焊缝形貌图；
图7为本公开实施例的复合焊连续焊接方法的实验例的焊缝断面图。
其中，1、第一焊件；2、第二焊件；3、锁底；4、激光焊接部；5、变极性电弧焊接部；6、送丝机构；7、焊缝截面；8、焊接熔孔；9、光斑；A、焦点；H、离焦量；Z R、瑞利长度。
具体实施方式
下面结合附图和实施例对本公开的实施方式作进一步详细描述。以下实施例用于说明本公开，但不能用来限制本公开的范围。
在本公开的描述中，除非另有说明，“多个”的含义是两个或两个以上。术语“上”、“下”、“左”、“右”、“内”、“外”、“前端”、“后端”、“头部”、“尾部”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本公开和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本公开的限制。此外，术语“第一”、“第二”等仅用 于描述目的，而不能理解为指示或暗示相对重要性。
在本公开的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本公开中的具体含义。
实施例
如图1和图2所示，本实施例提供的复合焊连续焊接方法包括：通过激光和变极性电弧耦合对焊件的坡口处进行复合焊接。其中，激光的离焦量H不小于激光的瑞利长度Z R。该方法能够利用激光-变极性复合焊对待焊焊件实现连续焊接，并利用复合焊接的能量耦合作用保证焊接稳定性，同时扩大激光的离焦量至超出激光的瑞利长度范围以外，从而解决现有技术中焊接气孔难以逸出的问题，有效提高焊接稳定性和可靠性。
传统激光电弧复合焊接时，其产生的激光无离焦或离焦量H很小，则落在工件表面的激光光斑9较小(光斑9直径小于0.6mm)，而激光的能量密度(功率密度)较大，“小孔效应”凸显。在复合焊的激光焊接过程中，维持小孔的主要动力是金属蒸汽对后壁的反冲压力。由于激光的能量密度(功率密度)较大，则有更多金属被熔化，焊缝内的熔池中产生了大量的金属蒸气，这些金属蒸汽不断冲击着熔池后壁从而引起熔池震荡，造成了金属飞溅，而由于没有足够的金属填补焊缝从而造成小孔塌陷，最终在焊缝截面7内形成多处“小孔型”气孔。同时，传统激光电弧复合焊接因焊接速度快，导致小孔在冷却凝固过程时易形成气泡残留在焊缝中成为氢气孔。因此，传统激光-电弧复合焊方式容易导致在焊缝内部易形成气孔、焊件坡口熔合不良等缺陷。
而本公开实施例的方法利用激光与变极性电弧之间产生耦合作用，从而利用激光-变极性电弧复合焊接的方式对焊件的坡口处进行复合焊接。该焊接过程中，通过增大激光的离焦量H至瑞利长度Z R范围以外，从而有效降低激光在焊件表面的功率密度，减小焊缝的深宽比，增加焊接熔孔8的直径，以增强复合焊接的稳定性，同时能够有效减少焊接熔孔8因小孔塌陷现象引起的孔洞，进而解决现有技术中焊接气孔缺陷难以逸出的问题 的缺陷，降低氢气孔的产生，保证气孔有效逸出，减少侧壁未熔等质量缺陷，使焊缝成形以及焊件的焊接质量和力学性能都得到很大提高。与此同时，应用本实施例所述的方法进行焊接时，焊件上产生的焊缝宽度较传统激光-电弧复合焊缝增大2～3倍，在利用焊件进行大型部件装配时，对组装间隙、定位焊缝的焊接工程适应能力大大增强。
需要说明的是，特别是对于铝合金板材，采用本实施例所述的方法，可有效解决铝合金板材在激光焊接过程中产生的气孔及成型难题，并能增强激光电弧焊接的稳定性和可靠性，适用于针对较长较大的薄壁部件的持续焊接。
高速列车车体上通常涉及有一种带锁底的对接结构。该对接结构的结构可参见下述的焊接成品的结构。在进行焊接时为防止焊缝出现焊漏和焊缝表面的咬边情况的发生，且为了形成良好的焊缝形状，通常需要在两个对接焊件在对接时形成的待焊坡口内的底部留有衬垫。通常将这种衬垫设计成与其中一个焊件的端部为一体，而另一焊件的端部搭接在该衬垫上，并且保证两个焊件的端部对接，在两个焊件的对接处形成待焊坡口，则将这种对接结构称为“带锁底的对接接头结构”，其中所述的衬垫即为锁底。
同理的，针对高速列车车体用的中空型材的带锁底的铝合金对接结构，在对该对接结构进行焊接的过程中，为了保证焊接质量，不能让激光产生的小孔穿透锁底3。故而上述的带锁底的对接结构(即下述的焊接成品)为典型的盲焊结构。当针对上述的盲焊结构进行焊接时，如果采用小离焦或零离焦的传统激光焊接工艺，则焊接的熔池深宽比过大，熔池体积过小，焊接速度过高，从而导致熔池冷却结晶的速度过快，不利于气泡的上浮逸出。而气孔的存在不仅会降低该焊件的对接结构的有效承载面积，而且会使该对接结构的局部产生应力集中，从而降低焊件的强度和韧性，严重影响焊件甚至车体的服役寿命。
因此，对于带锁底的对接结构，焊接时造成的气孔缺陷仍然是焊接过程中难以避免的难题。而焊接过程中改变激光的离焦量H的大小会对焊接质量产生重要的影响。具体的，焊接时若其余参数固定，则激光离焦量H的变化可以直接改变焊件表面激光光斑9直径的大小，从而影响焊接过程中对焊件表面的热输入量大小。离焦量H过小则会对焊接质量和焊接过程 造成诸多不利影响，包括以下两个方面的不利影响：
一方面，当离焦量H较小时，就会在焊件表面产生较高的激光功率密度，而在微秒时间范围内，焊件表层即可加热至沸点，从而产生大量汽化金属蒸气，与此同时，高浓度气体使液相金属运动至熔池边缘，在熔池中心形成凹陷，从而不利于焊接熔孔8的稳定，非常容易在熔池内产生气孔和成形缺陷。
另一方面，如果采用小离焦或零离焦的激光焊接方法对上述的对接结构进行焊接，由于该对接结构的坡口处有装配间隙的存在，使得坡口内对流传导介质的表面积相对较小，对流传导的热量在三维空间上分布不均，从而导致焊缝金属出现外溢、过熔、焊缝根部或坡口侧壁熔合不良等焊缝成形缺陷的产生。
为了消除上述的不利影响，提高焊接稳定性和质量，本实施例的方法将复合焊中的激光(激光束)的离焦量H提高至不小于该激光的瑞利半径的范围，并且将变极性电弧与激光耦合，从而利用变极性电弧提高焊件表面的能量吸收率，以保证本实施例所述的复合焊对焊件表面产生足够的入射能量，并保证焊缝的熔池成型稳定。本实施例的方法是在激光—变极性电弧焊的基础上，增大激光的离焦量H以降低焊件表面的功率密度I，同时保证焊接熔孔8的结构稳定，有效减少熔池内的气孔产生，并降低成形缺陷，从而提高最终形成的焊接成品的力学性能。
具体的，参照图3所示，本实施例所述的连续焊接方法中，激光沿图3中的箭头Z方向射入至焊件的坡口处。在光学(特别是激光学)中，设鞍腰部(即如图3中所示的激光焦点A点位置)的半径为W 0，其横截面面积为S 0。沿激光的传播方向Z所示，当激光的横截面面积S Z因为散射达到2S 0时，设该位置为图3所示的B点位置，则B点位置的激光的横截面面积S Z＝2S 0。本实施例所述的瑞利长度Z R或者瑞利射程是指从A点到B点的长度(即图3所示的Z R)，且B点位置的光斑9半径
Figure PCTCN2019104848-appb-000001
B点位置的激光横截面面积S Z为A点位置激光横截面面积S 0的2倍。
本实施例中，激光的离焦量H与瑞利长度Z R的关系为H≥Z R；优选的，H＞Z R；进一步优选的，H＞2Z R，以使得函件表面的功率密度I足够小，并且进一步降低坡口内熔融的金属速率，减少气泡的生成并给予气泡溢出充足的反应时间。具体的，图3中所示的b为共轭焦距，有b＝2Z R。W(Z) 为激光束在Z方向的半径，则W(Z)的最小值出现在A点，即有W(A)＝W 0；θ为激光散射至W(Z)位置时的展角，λ是该激光束的波长，则有：
Figure PCTCN2019104848-appb-000002
本实施例中，设激光的功率密度为I，激光能量(即激光功率)为E，激光的光斑面积为S，则有：
Figure PCTCN2019104848-appb-000003
由此可见，本公开实施例的方法中，当增大复合焊接时的激光离焦量H至达到并超出瑞利长度的范围时，一方面使得激光的光斑面积相应增大，以控制焊件表面受到的激光的功率密度相应减小，表层金属达到沸点前需要经历数毫秒，在表层汽化前，底层金属达到熔点，易在坡口内形成良好的熔融焊缝；另一方面能有效增加焊缝截面7的宽度，以使得该方法在焊件坡口处产生的焊缝的深宽比减小，而焊接熔孔8的直径相应增加。
由此可知，本实施例所述的复合焊利用激光的高能量密度实现大离焦(离焦量H达到瑞利长度Z R的范围以外)、大光斑9(光斑9直径达到2mm以上)的激光电弧复合焊，从而在焊件表面形成大匙孔(焊接熔孔8的孔径达到3mm以上)的激光深熔焊接。在实现大熔深、小变形、低应力的高能、高速焊接的同时，获得不同于传统激光-电弧复合焊缝特征的大熔宽激光电弧复合焊缝，其焊缝宽度为传统激光-电弧复合焊缝的2～3倍，从而大大增强了激光电弧复合焊接的间隙适应能力和缺陷抑制能力。
与此同时，为了避免激光离焦量H增大后的焊接过程不稳定，本实施例的方法中，将变极性电弧作为激光的耦合热源，以利用变极性电弧与激光的耦合作用共同作用于焊件的坡口处，从而实现对焊件坡口的稳定连续焊接。
在焊接过程中，一方面，变极性电弧充分利用了正、反向电流值及占空比可调的特性，以最大程度的强化阴极雾化作用来清理焊件表面的氧化膜，从而在焊接过程中能够大大减小焊缝内氢气孔的产生；另一方面，变极性电弧的引入起到稳定焊接过程、增强间隙适应能力及定位焊缝熔透能力，起到增强工程适应性的作用；同时，变极性电弧具有的正负极性的周期交替过程，对于保证对长大薄壁铝合金部件的持续稳定焊接起到了关键作用。
具体的，变极性电弧具有的正负极性交替过程可有效冷却电弧焊接部5的钨极接头，从而进一步降低了焊接热输入，并能提高焊件表面的能量吸收率，从而为大离焦的激光焊接的稳定性提供了进一步的保障作用；同时，其电弧的正极性具有阴极雾化作用，能够充分清理焊件表面的氧化膜，其负极性可以保护电弧钨极得到有效冷却，从而形成对焊件的连续、稳定、优质焊接能力。
如图1所示，本实施例所述的方法中，激光自焊件的正面垂直或倾斜的入射至坡口处，变极性电弧自激光的侧面作用于坡口处，以使激光和变极性电弧之间构成旁轴复合的结构关系。进一步的，将变极性电弧自激光的后侧作用于坡口处。激光束在电弧前可以使焊缝的上表面成形均匀且饱满美观，且电弧在激光之后时，焊件表面的热源作用的面积更大，当热源移走后焊缝冷却更慢，从而有利于熔池中的气体溢出，避免焊缝内留存气泡而影响焊接质量；此外，电弧的热源作用位于激光的后侧，则相当于对焊缝进行了一次回火，进一步提高焊缝的连接强度。
具体的，激光作用于焊件的坡口处时，激光的光斑9位于坡口上，以在坡口处的焊缝内形成焊接熔孔8。随着激光焊接部4与电弧焊接部5的同步移动，坡口内形成连续焊缝。根据图1和图7所示，在焊缝截面7上可以明显看到，焊接熔孔8形成于焊缝内。本实施例中，激光的离焦量H为焦点A与光斑9之间的距离，该激光的焦点A位于光斑9的上方，即激光的离焦量H大于0，且激光的离焦量H大于激光的瑞利长度Z R。
本实施例所述的方法还包括：在激光和变极性电弧对坡口进行复合焊接的同时，向坡口内填充焊丝，以将焊丝熔化于坡口内形成焊缝。优选自激光的前侧想坡口内填充焊丝，即焊丝先置于坡口内，再利用激光和电弧的耦合作用于坡口内的焊丝上，以将焊丝熔融填充于坡口内形成焊缝。
本实施例的方法中，激光在前用于对焊件实施深熔焊接；变极性电弧在后用于在焊接时对焊件的坡口内产生预热和稳弧作用，从而提高激光能量的利用率，增强了激光和电弧两种热源的相互作用，大大减少了铝合金材料本身对激光高反射率造成的激光能量损失。与此同时，变极性电弧充分利用了正、反向电流值及占空比可调，最大程度强化阴极雾化作用清理表面氧化膜，降低焊缝表面处氢气孔的产生，同时可进一步降低焊接热输 入，降低焊缝深宽比以提高其稳定性。在保留传统激光电弧复合焊接低应力、小变形、高能高效焊接特点的同时，熔池流动及成型过程的工程适应能力进一步增强，焊接气孔缺陷因光斑9直径及焊接熔孔8的孔径增大而得以有效排出，深熔焊接固有的侧壁未熔缺陷的抑制能力得到提高，焊缝成形及接头质量进一步改善，力学性能得到有效提高。
基于上述的方法，本实施例还提出了一种利用复合焊连续焊接的装置。该装置是利用上述的方法对焊件进行焊接。
具体的，如图1和图2所示，该装置包括用于产生激光的激光焊接部4、用于产生变极性电弧的电弧焊接部5、以及控制机构。电弧焊接部5与激光焊接部4旁轴复合，以利用上述的连续焊接方法，使得激光和变极性电弧耦合对焊件的坡口处进行复合焊接。焊接时，以激光焊接部4发射的激光射出的光斑位置为当前焊接点，电弧焊接部5的电弧产生接头指向该当前焊接点，从而利用激光和变极性电弧的耦合将坡口内同一位置(即当前焊接点)的焊丝熔融，以利用焊丝将坡口填充形成焊缝。控制机构分别与激光焊接部4和电弧焊接部5连接。控制机构用于控制激光焊接部4以使激光的离焦量H不小于所述激光的瑞利长度Z R，并用于驱动电弧焊接部5产生变极性电弧。
本实施例中，激光焊接部4产生的激光束为CO 2激光、光纤激光或半导体脉冲激光中的一种，电弧焊接部5产生的变极性电弧可以是非熔化极(TIG)电弧或等离子弧(PA)。以图1中所示的箭头方向为激光焊接部4和电弧焊接部5的同步移动方向，即为焊接方向。
本实施例所述的激光焊接部4与电弧焊接部5之间旁轴复合。旁轴复合是指激光束与电弧以预设的夹角共同作用于焊件的同一位置，从而对该位置进行复合焊接。可理解的是，在进行复合焊接时，除了将激光焊接部4与电弧焊接部5之间旁轴复合外，也可以采用同轴复合的结构形式，即将激光焊接部4与电弧焊接部5内外嵌套并同轴设置，以使激光与电弧处于同轴共同作用于焊件的同一位置。
本实施例的装置具有专用的焊接喷嘴位置结构。具体的，如图1所示，以激光焊接部4射出的激光方向为基准，送丝机构6倾斜的置于激光焊接部4的前方形成焊丝前置，电弧焊接部5倾斜的置于激光焊接部4的后方 以形成电弧后置，利用变极性电弧与激光之间发生耦合，并共同作用于前置的焊丝上。变极性电弧对激光起到了预热、稳弧的作用。以图1所示的焊件上方为焊件的正面，激光从焊件的正面垂直或倾斜入射，变极性电弧与激光旁轴复合，焊丝被送入并熔融在两个热源作用于焊件坡口处的同一位置内，从而在该位置处形成熔池。上述的送丝机构6的焊丝与激光焊接部4的激光之间、以及激光焊接部4的激光与电弧焊接部5的变极性电弧之间的间距分别为0.5mm～1mm、以及2mm～3mm，以激光为基准的相对倾斜角度分别为25°～30°、以及30°～40°。上述的喷嘴位置结构能够增强各焊接部喷嘴的冷却效果，提高喷嘴的连续焊接能力。
在采用本实施例的装置进行焊接时，根据焊件的板厚和型材本身的焊接要求，优选激光束采用不小于两倍瑞利长度Z R的离焦量进行焊接。具体的，激光束的离焦量H不小于10mm；进一步优选采用10mm～20mm的离焦量H进行焊接。该离焦量H的范围满足超出瑞利长度Z R范围，并且不小于两倍瑞利长度Z R的要求。由于增大了激光离焦量H，则作用于焊件表面的光斑9直径增大至2mm及以上，焊接熔孔8的直径进而增大至3mm及以上，焊缝的宽度不小于9mm，则焊缝的深宽比适当降低，焊接熔孔8的表面积大大增加，以增强其连续焊接的稳定性，焊缝内的气孔得以有效逸出并使焊缝成形和焊接质量得到明显改善。
基于上述的方法及装置，本实施例还提供了一种焊接成品。该焊接成品包括第一焊件1和带锁底3的第二焊件2，第一焊件1位于锁底3上与第二焊件2对接，在第一焊件1和第二焊件2的对接处形成坡口，利用如上所述的连续焊接方法在上述的坡口处形成焊缝。锁底3作为对该焊接成品的坡口底部的保护结构，其采用上述的连续焊接方法将第一焊件1与第二焊件2之间、以及第一焊件1与锁底3之间紧密焊接，有效提高焊接成品的结构强度和力学性能。
本实施例所述的焊接成品中，第一焊件1和第二焊件2的限定厚度范围均为2mm～6mm，这是由于当焊件厚度超过6mm时，容易导致焊接时所需的激光功率大大增加，热输入提高，同时熔池稳定性降低，气孔率及焊接缺陷又有所增加，因此本公开实施例的连续焊接方法更适用于对母材厚度为2-6mm的铝合金型材焊件进行焊接，以得到相应的焊接成品。
本实施例还提出了一种车体。该车体包括如上所述的焊接成品。
对比实验
以下通过对比实验，对本实施例所述的复合焊连续焊接方法的过程及效果进行详细描述。
本实验所述的对比例采用常规激光-电弧复合焊接，本实验所述的实验例采用本实施例所述的复合焊连续焊接方法。对比例和实验例均以两块厚度均为4mm、材质为6系铝合金的板材作为对接的第一焊件1和第二焊件2，且第二焊件2上与第一焊件1对接的端部设有锁底3。
本实验的对比例所述的常规激光-电弧复合焊的参数为：
激光功率E 1＝4500W，电弧电流为220A，焊接速度为5m/min，送丝机构6的速度为5m/min，激光焊接部4的激光离焦量H为0。对比例经焊接实验得到的焊缝正面宏观形貌如图4所示，对比例的焊缝横截面宏观形貌如图5所示。
本实验的实验例所述的方法中，通过增大激光离焦量H可以减少焊缝内的气孔产生，改善焊缝的成形状态。该复合焊连续焊接方法的焊接参数为：
激光功率E 2＝6500W，电弧电流为230A，焊接速度为4.8m/min，送丝速度为5.5m/min，激光离焦量H为+15mm。该实验例得到的焊缝正面宏观形貌如图6所示，该实验例得到的焊缝横截面宏观形貌如图7所示。
通过比较可以看出：
如图4和图5所示，对比例的焊件经常规激光-电弧复合焊所得的焊件焊缝余高偏大，约为1.5mm～2mm；焊缝截面7的熔宽较窄，约为3mm～4mm；同时在焊缝截面7中出现多处肉眼可见的气孔，焊缝内的熔池、焊接熔孔8与焊件坡口的衔接处成形不稳定。
如图6和图7所示，实验例的焊件经本实施例所述的连续焊接的方法所得的焊件焊缝余高较小，约为0.5mm～1mm；焊缝截面7的熔宽较宽，约为8mm～9mm；同时在焊缝截面7中气孔缺陷基本消除，焊缝内的熔池、焊接熔孔8与焊件坡口的衔接处成形均匀、稳定。
经过本对比实验还可得出：本实验例的方法所得的焊接接头结构(即上述的焊接成品)中，焊缝的焊接变形较对比例略大，但远远小于小于传 统的电弧焊，可以满足对高速列车车体用的中空型材的带垫板(锁底3)的铝合金对接结构实现连续、稳定、优质焊接的需求。
综上所述，本实施例的复合焊连续焊接方法包括：通过激光和变极性电弧耦合对焊件的坡口处进行复合焊接；其中，激光的离焦量H不小于激光的瑞利长度Z R。本公开的方法将激光与变极性电弧相耦合，并增大激光的离焦量H至瑞利长度Z R范围以外，从而有效降低激光在焊件表面的功率密度，减小焊缝的深宽比，增加焊接熔孔8的直径，以增强复合焊接的稳定性，同时能够有效减少焊接熔孔8因小孔塌陷现象引起的孔洞，进而解决现有技术中焊接气孔缺陷难以逸出的问题的缺陷，降低氢气孔的产生，有效提高焊接稳定性和可靠性，并提高焊缝的力学性能。
本公开的实施例是为了示例和描述起见而给出的，而并不是无遗漏的或者将本公开限于所公开的形式。很多修改和变化对于本领域的普通技术人员而言是显而易见的。选择和描述实施例是为了更好说明本公开的原理和实际应用，并且使本领域的普通技术人员能够理解本公开从而设计适于特定用途的带有各种修改的各种实施例。

Claims (10)

  1. 一种复合焊连续焊接方法，其特征在于，包括：
    通过激光和变极性电弧耦合对焊件的坡口处进行复合焊接；
    其中，所述激光的离焦量不小于所述激光的瑞利长度。
  2. 根据权利要求1所述的方法，其特征在于，所述激光自所述焊件的正面垂直或倾斜的入射至所述坡口处，所述变极性电弧自所述激光的侧面作用于所述坡口处。
  3. 根据权利要求2所述的方法，其特征在于，所述变极性电弧自所述激光的后侧作用于所述坡口处。
  4. 根据权利要求1所述的方法，其特征在于，所述激光作用于所述焊件的坡口处时，所述激光的光斑位于所述坡口上，以在所述坡口处的焊缝内形成焊接熔孔，所述激光的焦点位于所述光斑的上方，所述激光的离焦量为所述焦点与所述光斑之间的距离，所述激光的离焦量大于所述激光的瑞利长度。
  5. 根据权利要求4所述的方法，其特征在于，所述激光的离焦量为H，所述激光的瑞利长度为Z R，则H＞2Z R。
  6. 根据权利要求1-5任一项所述的方法，其特征在于，还包括：
    在所述激光和所述变极性电弧对所述坡口进行复合焊接的同时，向坡口内填充焊丝，以将所述焊丝熔化于所述坡口内形成焊缝。
  7. 一种复合焊连续焊接装置，其特征在于，该装置包括：
    用于产生激光的激光焊接部；
    用于产生变极性电弧的电弧焊接部，所述电弧焊接部与所述激光焊接部旁轴复合，以使所述激光和所述变极性电弧耦合对焊件的坡口处进行复合焊接；
    控制机构，分别与所述激光焊接部和所述电弧焊接部连接，所述控制机构用于控制所述激光焊接部以使所述激光的离焦量不小于所述激光的瑞利长度，并用于驱动所述电弧焊接部产生变极性电弧。
  8. 根据权利要求7所述的装置，其特征在于，该装置还包括送丝机构，所述送丝机构通过旁轴复合安装在所述激光焊接部的侧面。
  9. 一种焊接成品，其特征在于，该焊接成品包括第一焊件和带锁底 的第二焊件，所述第一焊件位于所述锁底上与所述第二焊件对接，在所述第一焊件和第二焊件的对接处形成坡口，利用如权利要求1-6任一项所述的方法在所述坡口处形成焊缝。
  10. 一种车体，其特征在于，包括如权利要求9所述的焊接成品。
PCT/CN2019/104848 2019-04-08 2019-09-09 复合焊连续焊接方法及装置、焊接成品、车体 WO2020206923A1 (zh)

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