阅读说明：本技术 铝合金的复合焊接方法以及焊接头 (Composite welding method for aluminum alloy and welded joint ) 是由 蔡得涛 韩善果 罗子艺 董春林 易耀勇 郑世达 王亚琴 弗拉基斯拉夫·哈斯金 巴比奇 于 2019-10-14 设计创作，主要内容包括：本发明涉及焊接技术领域,公开了铝合金的复合焊接方法,包括：利用复合焊接的方式对对接好的铝合金工件的连接缝处进行焊接,焊接方式为激光和等离子弧复合焊接,等离子弧为两个异极性的电极交替起弧,焊接过程中,任一极性的电极起弧形成的电弧均与激光形成共熔池。还公开了铝合金的复合焊接头,将该焊接头与激光发出机构以及两个异极性的电极装配好后可实施上述方法。本发明提供的焊接方法等离子弧和激光束协同作用,使得焊接时熔深得到有效提高,采用两个异极性电极交替起弧,可清理铝合金表面的氧化物,两个电极交替起弧相较于一个电极交替通入正、负电起弧不会损伤电极。(The invention relates to the technical field of welding, and discloses a composite welding method of aluminum alloy, which comprises the following steps: and welding the joint of the butted aluminum alloy workpieces by using a hybrid welding mode, wherein the welding mode is laser and plasma arc hybrid welding, the plasma arc is formed by alternately striking two electrodes with different polarities, and an electric arc formed by striking the arc of the electrode with any polarity and the laser form a molten pool in the welding process. The method can be implemented after the welding head is assembled with the laser emitting mechanism and the two electrodes with different polarities. The plasma arc and the laser beam of the welding method provided by the invention have synergistic effect, so that the penetration during welding is effectively improved, the two heteropolarity electrodes are adopted for alternate arcing, the oxide on the surface of the aluminum alloy can be cleaned, and the alternate arcing of the two electrodes does not damage the electrodes compared with the alternate arcing of one electrode which is alternately introduced with positive electricity and negative electricity.)

1. A hybrid welding method of an aluminum alloy, characterized by comprising:

and welding the joint of the butted aluminum alloy workpieces by using a hybrid welding mode, wherein the welding mode is laser and plasma arc hybrid welding, the plasma arc is formed by alternately striking two electrodes with different polarities, and an electric arc formed by striking the arc of the electrode with any polarity and the laser form a molten pool in the welding process.

2. The composite welding method of aluminum alloy according to claim 1, wherein the laser beam power of the composite welding is 1-5kw, one of two electrodes of different polarity is direct current positive, the current is 30-200A, and the energization time is 15-25ms each time when the arc is alternately started; the other one of the two electrodes with different polarities is in direct current reverse connection, the current is 50-220A, and the power-on time of each time during alternate arc striking is 3-8 ms;

preferably, the laser beam and the plasma arc are emitted from the same compression nozzle to form laser-alternating heteropolar plasma composite electric arc to act on the aluminum alloy workpiece, and the distance between the compression nozzle and the aluminum alloy workpiece is 2.5-3.5 mm;

preferably, the compression nozzle has the compound electric arc export that supplies laser beam and plasma arc blowout, the lateral wall of compression nozzle is provided with the protection gas blowout passageway along its circumference, the one end of protection gas blowout passageway with the inside intercommunication of compression nozzle, the other end orientation is close to the direction of compound electric arc export extends and communicates with the external world to make the protection gas follow form the protection gas cover after the protection gas blowout passageway spouts, will the laser beam with the plasma arc protection in the protection gas cover.

3. The composite welding method of aluminum alloy according to claim 1, wherein the width of the joining seam is 0 to 0.5 mm.

4. The composite welding method of aluminum alloy according to claim 1, wherein two electrodes with different polarities are respectively located on both sides of the laser beam, and during welding, along the welding direction, the direct current counter electrode is in front, and the direct current positive electrode is behind;

preferably, the arc starting end of each electrode is conical, and the tip part of the conical shape faces the connecting seam;

preferably, the distance between the arcing ends of the two electrodes of opposite polarity is less than or equal to 4 mm.

5. The hybrid welding method for aluminum alloy according to claim 1, characterized in that nitrogen or inert gas is selected as the ion gas and the shielding gas for plasma arc welding;

preferably, the gas flow is 15-20L/min.

6. The composite welding method of aluminum alloy according to claim 1, wherein the thickness of the aluminum alloy workpiece near the weld joint is 2 to 10 mm.

7. The composite welding method of aluminum alloy according to claim 1, wherein the surface of the aluminum alloy workpiece is cleaned to remove oil contamination before welding and then dried.

8. The aluminum alloy composite welding head is characterized by comprising a welding head body, wherein the welding head body is provided with a compression nozzle, a laser beam channel and two electrode accommodating cavities for accommodating two electrodes with different polarities respectively are arranged in the welding head body, the laser beam channel is provided with a laser beam outlet, each electrode accommodating cavity is provided with an electrode outlet, and the laser beam outlet and each electrode outlet face the compression nozzle;

preferably, the laser beam passage is located between two of the electrode receiving cavities.

9. The composite welding head of aluminum alloy according to claim 8, wherein the compression nozzle has a composite arc outlet for ejecting the laser beam and the plasma arc, a shielding gas ejection channel is formed in a side wall of the compression nozzle along a circumferential direction of the compression nozzle, the laser beam channel is further used for allowing the shielding gas and the ion gas to pass through, one end of the shielding gas ejection channel is communicated with the laser beam channel, and the other end of the shielding gas ejection channel extends towards a direction close to the composite arc outlet and is communicated with the outside, so that the shielding gas is ejected from the shielding gas ejection channel to form a shielding gas hood, and the laser beam and the plasma arc are protected in the shielding gas hood.

Technical Field

The invention relates to the technical field of welding, in particular to a composite welding method and a welding head of aluminum alloy.

Background

The laser welding technology is one of key technologies in engineering manufacturing process, and is widely applied to industrial production of aerospace, high-speed trains, automobiles and the like due to the outstanding advantages of high energy density, high welding speed, large depth-to-width ratio of welding seams, good joint performance, small deformation of welding structures and the like. However, the advantages of laser welding non-ferrous metals with high reflectivity, such as aluminum alloys, are greatly reduced. The aluminum alloy is active in chemical property, and a dense and infusible oxide film is covered on the surface of the aluminum alloy, so that welding defects are easily caused. Because of the high reflectivity of aluminum alloy, it is difficult to weld thicker aluminum alloy structural members by using laser alone as a heat source, and welding defects are caused by too high a cooling rate of welding. In addition to TIG welding, plasma welding and laser welding, the common aluminum alloy welding method adopts a composite heat source for welding, such as plasma-MIG composite welding, laser-TIG composite welding and laser-plasma composite welding, and due to the action of plasma arcs, the absorption effect of an aluminum plate on laser is obviously improved, and the penetration is greatly improved.

The existing composite heat source welding also has a plurality of problems, such as complex welding process, low welding efficiency, short service life of an arc starting electrode, unstable electric arc and the like.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention provides a composite welding method and a welding head of an aluminum alloy, aiming at solving at least one problem in the background technology during the welding of the existing aluminum alloy workpiece.

The invention is realized by the following steps:

in a first aspect, an embodiment of the present invention provides a composite welding method for an aluminum alloy, including:

and welding the joint of the butted aluminum alloy workpieces by using a hybrid welding mode, wherein the welding mode is laser and plasma arc hybrid welding, the plasma arc is formed by alternately striking two electrodes with different polarities, and an electric arc formed by striking the arc of the electrode with any polarity and the laser form a molten pool in the welding process.

In an optional embodiment, the power of a laser beam for composite welding is 1-5kw, one of two electrodes with different polarities is in direct current positive connection, the current is 30-200A, and the energizing time of each time during alternate arc starting is 15-25 ms; the other one of the two electrodes with different polarities is in reverse direct current connection, the current is 50-220A, and the power-on time of each time during alternate arc striking is 3-8 ms.

In an alternative embodiment, the laser beam and the plasma arc are emitted from the same compression nozzle to form laser-alternating heteropolar plasma composite electric arc to act on the aluminum alloy workpiece, and the distance between the compression nozzle and the aluminum alloy workpiece is 2.5-3.5 mm.

In an optional embodiment, the compression nozzle is provided with a composite arc outlet for ejecting the laser beam and the plasma arc, a shielding gas ejection channel is arranged on the side wall of the compression nozzle along the circumferential direction of the side wall, one end of the shielding gas ejection channel is communicated with the inside of the compression nozzle, and the other end of the shielding gas ejection channel extends towards the direction close to the composite arc outlet and is communicated with the outside, so that a shielding gas hood is formed after the shielding gas is ejected from the shielding gas ejection channel, and the laser beam and the plasma arc are protected in the shielding gas hood.

In an alternative embodiment, the width of the connecting seam is 0-0.5 mm.

In an alternative embodiment, two electrodes with different polarities are respectively positioned at two sides of the laser beam, and during welding, the direct current reverse electrode is in front and the direct current positive electrode is in back along the welding direction.

In an alternative embodiment, the arcing end of each electrode is tapered with the tip of the taper facing the joint seam.

In an alternative embodiment, the distance between the arcing ends of the two electrodes of opposite polarity is less than or equal to 4 mm.

In alternative embodiments, nitrogen or an inert gas is used as the ion gas and the shielding gas for plasma arc welding.

In an alternative embodiment, the gas flow rate is 15-20L/min.

In an alternative embodiment, the aluminum alloy workpiece has a thickness of 2-10mm near the weld joint.

In an alternative embodiment, the surface of the aluminum alloy workpiece is cleaned to remove oil contamination prior to welding and then dried.

In a second aspect, an embodiment of the present invention provides an aluminum alloy composite welding head, including a welding head body, where the welding head body is provided with a compression nozzle, the welding head body is provided with a laser beam channel and two electrode accommodating cavities for accommodating two electrodes with different polarities, respectively, the laser beam channel is provided with a laser beam outlet, each electrode accommodating cavity is provided with an electrode outlet, and the laser beam outlet and each electrode outlet face the compression nozzle.

In an alternative embodiment, the laser beam channel is located between two electrode receiving cavities.

In an optional embodiment, the compression nozzle is provided with a composite arc outlet for ejecting the laser beam and the plasma arc, a shielding gas ejection channel is arranged on the side wall of the compression nozzle, the laser beam channel is also used for allowing the shielding gas and the ionic gas to pass through, one end of the shielding gas ejection channel is communicated with the laser beam channel, and the other end of the shielding gas ejection channel extends towards the direction close to the composite arc outlet and is communicated with the outside, so that the shielding gas forms a shielding gas hood after being ejected from the shielding gas ejection channel, and the laser beam and the plasma arc are protected in the shielding gas hood.

The invention has the following beneficial effects:

according to the composite welding method for the aluminum alloy, which is obtained through the design, due to the adoption of the laser and plasma arc composite welding method, the absorption of the alloy to laser is increased by a plasma heat source, the requirements on laser power and assembly are reduced, the penetration during welding can be greatly improved by matching the laser and plasma arc composite welding method, in addition, the positive and negative electrodes are adopted for alternative welding, a direct current reverse connection electrode is arranged in front of the direct current reverse connection electrode during welding, the direct current forward connection electrode is arranged behind the direct current reverse connection electrode, the oxidation layer on the surface of the aluminum alloy can be effectively cleaned in the welding process, the welding of the large-thickness alloy can be realized, the preparation work of removing the oxidation layer of the aluminum alloy. More importantly, two electrodes with different polarities are respectively used as a positive electrode and a negative electrode for alternate arcing, compared with the method that only one electrode is used for alternately introducing positive electricity and negative electricity for arcing, the method has lower design requirements on a power supply, and the used electrode can reduce electrode burning loss without frequent polarity change, so that the service life of the electrode is greatly prolonged; the welding process ensures that the laser and the plasma arc are molten together, so that the composite welding method provided by the invention has good welding effect and is suitable for welding workpieces with large thickness.

According to the aluminum alloy composite welding head obtained through the design, through reasonable design, when welding is carried out, the welding method provided by the invention can be implemented after the laser, the electrode and the welding head are assembled, the welding of an aluminum alloy workpiece is realized, the side wall of the compression nozzle is provided with the protective gas spraying channel for multiple functions, one part of gas is used for forming a plasma arc, and the other part of gas enters the compression nozzle through the channel and plays a cooling role and also serves as the protective gas.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic view of a reverse polarity pattern in hybrid welding of aluminum alloys;

FIG. 2 is a schematic view of positive polarity pattern in hybrid welding of aluminum alloy;

FIG. 3 is a cross-sectional view of the laser-heteropolar double plasma arc hybrid welding head in cooperation with a laser beam and an electrode;

FIG. 4 is a schematic view of a heteropolar dual plasma arc current pattern;

FIG. 5 is a schematic view of a welded joint of an aluminum alloy part.

Icon: 10-composite welded joint of aluminum alloy; 101-a weld head body; 13-a compression nozzle; 131-a composite arc outlet; 14-a securing mechanism; 15-an insulating sleeve; 16-a shielding gas ejection channel; 111-laser beam path; 112-an electrode receiving cavity; 1-laser beam axis; 2-a laser beam; 3-plasma arc; 4-a first aluminum alloy workpiece; 5-a second aluminum alloy workpiece; 6-protective gas hood; 11-a first electrode; 12-a second electrode; 21-ionic gas and protective gas.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The method, nozzle and mechanism for composite welding of aluminum alloy according to the embodiment of the present invention are described in detail below.

The composite welding method of the aluminum alloy provided by the embodiment of the invention comprises the following steps:

and welding the joint of the butted aluminum alloy workpieces by using a hybrid welding mode, wherein the welding mode is laser and plasma arc hybrid welding, the plasma arc is formed by alternately striking two electrodes with different polarities, and in the welding process, the electrode with any polarity is struck to form an electric arc which forms a molten pool with the laser.

Adopt laser and plasma arc hybrid welding, the penetration obtains big promotion when can making the welding, and more important adopts the electrode of two heteropolarities to do positive electrode and negative pole alternate arcing respectively, compares in only using an electrode to let in positive electricity in turn and negative electricity arcing, and this application is lower to the design requirement of power, and the electrode that uses need not frequently take place polarity change in addition also can greatly increase the life of electrode.

The aluminum alloy workpiece has high laser welding reflectivity, the problems of small laser absorption amount and poor welding effect can be obviously solved when the method provided by the invention is adopted for welding, the aluminum alloy oxide layer does not need to be removed by acid and alkali washing before the aluminum alloy workpiece is welded, when the welding is started, the direct current reverse connection electrode is in front, the direct current forward connection electrode is behind, and during initial welding, the current is large and short, the high-melting-point oxide layer on the surface of the aluminum alloy can be rapidly removed, and meanwhile, the absorption rate of the material to laser is improved. And starting welding after the oxide layer of the aluminum alloy is removed. Therefore, when the welding workpiece is an aluminum alloy workpiece, it is not necessary to additionally treat the oxide layer of the surface before welding. It should be noted that the method provided by the invention is particularly suitable for aluminum alloy workpieces with the thickness of 2-10mm close to the welding seam, and the welding method provided by the invention has the best welding effect on the aluminum alloy workpieces with the thickness.

As shown in fig. 1 to 3, the specific welding method is as follows:

firstly, the surface of an aluminum alloy workpiece to be welded is cleaned to remove oil stains on the surface, so that adverse effects of the oil stains on welding are avoided. And drying the aluminum alloy workpiece after cleaning.

Two or more dried aluminum alloy workpieces are butted, installed and clamped, in the embodiment of the invention, a first aluminum alloy workpiece 4 and a second aluminum alloy workpiece 5 are butted, a gap at the butted position of the adjacent aluminum alloy workpieces is a connecting seam, in the application, the assembly requirement on the workpieces to be welded is not high, and the width of the connecting seam is 0-0.5 mm.

After the aluminum alloy workpieces are butted, welding is carried out along the connecting seam, the welding mode is laser and plasma arc composite welding, the plasma arc is formed by alternately striking two electrodes with different polarities, and an electric arc common melting pool formed by striking the laser and the electrode with any polarity is ensured during welding.

Preferably, in order to ensure better welding effect, the power of the laser beam of the composite welding is 1-5kw, one of two electrodes with different polarities is in direct current positive connection, the current is 30-200A, and the energizing time of each time is 15-25ms during alternate arc starting; the other one of the two electrodes with different polarities is in reverse direct current connection, the current is 50-220A, and the power-on time of each time during alternate arc striking is 3-8 ms. The electrode direct current positive connection is the negative electrode arcing, and the direct current reverse connection is the positive electrode arcing. The electrode current energization pattern is shown in fig. 4.

Preferably, in order to ensure that the laser and the plasma arc are molten together and further ensure the penetration, the laser beam 2 emitted by the laser generator and the plasma arc 3 emitted by the plasma electrode are ejected from the same compression nozzle 13, and the distance between the compression nozzle 13 and the aluminum alloy workpiece is 2.5-3.5 mm. Laser beam 2 and plasma arc 3 send from same compression nozzle, and plasma arc 3 is through electrode and laser combined action with gas ionization in compression nozzle 13, and gas ionization degree is higher, and welding effect is better.

Preferably, the two electrodes with different polarities are respectively positioned at two sides of the laser beam, and during welding, the direct current reverse electrode is in front and the direct current positive electrode is in back along the welding direction. The direct current reverse electrode enables the cathode atomization to be started at the beginning of welding, and the oxide film on the surface of the aluminum alloy is broken.

Preferably, nitrogen or inert gas, mainly argon in the present invention, is used as the plasma arc welding ion gas and the shielding gas 21, which are common gases for plasma arc welding. Preferably, the gas flow is 15-20L/min for ensuring better welding effect.

Preferably, in the embodiment provided by the present invention, the compression nozzle 13 has a composite arc outlet 131 for ejecting the laser beam 2 and the plasma arc 3, the side wall of the compression nozzle 13 is provided with a shielding gas ejection channel 16 along the circumferential direction thereof, one end of the shielding gas ejection channel 16 is communicated with the inside of the compression nozzle 13, and the other end thereof extends towards the direction close to the composite arc outlet 131 and is communicated with the outside, so that the shielding gas forms the shielding gas hood 6 after being ejected from the shielding gas ejection channel 16, and the laser beam 2 and the plasma arc 3 are protected in the shielding gas hood 6.

The design of the compression nozzle with the structure has high plasma arc stiffness, and the plasma arc and the laser beam jointly penetrate through the composite electric arc outlet for welding, so that double-heat source composite in the welding gun can be realized, and the eutectic pool welding can be realized.

After the high-frequency oscillation discharge of the electrode, a part of gas is ionized to form a plasma arc 3, and the other part of gas plays the roles of cooling gas and protective gas.

Preferably, the arc end of each electrode is tapered with the tip of the taper facing the joint seam. The tip-shaped structural design of the arc starting end can ensure that the electric arc is more stable compared with the spherical heat storage type structural design, and the arc starting end is simple in structure and lower in large-scale production cost.

Preferably, to further ensure better welding effect, the distance between the arcing ends of the two electrodes with different polarities is less than or equal to 4 mm.

As shown in fig. 1 to 3, a composite welding head 10 of an aluminum alloy according to an embodiment of the present invention includes a welding head body 101, the welding head body 101 is provided with a compression nozzle 13, a laser beam passage 111 and two electrode receiving cavities 112 for receiving two electrodes with different polarities respectively are provided in the welding head body 101, the laser beam passage 111 has a laser beam outlet, each electrode receiving cavity 112 has an electrode outlet, and the laser beam outlet and each electrode outlet face the compression nozzle 13.

During welding, two electrodes with different polarities are arranged: the first electrode 11 and the second electrode 12 are respectively installed in two electrode receiving chambers 112 of the composite welding head 10 of aluminum alloy such that the generated plasma arc 3 can pass through the compression nozzle 13; the laser is arranged above the laser beam passage 111 so that the laser beam 2 can be ejected from the compression nozzle 13 through the laser beam passage 111, the plasma arc 3 and the laser beam 2 are both ejected through the compression nozzle 13 for welding, and the laser beam outlet and each electrode outlet face the compression nozzle 13 to ensure a laser and plasma arc molten pool. The schematic view of the welded joint is shown in fig. 5.

Preferably, the laser beam passage 111 is located between two electrode receiving cavities 112. The arrangement can ensure that the direct current reverse connection electrode is arranged in front along the welding direction when welding so as to remove an oxide film on the surface of an aluminum alloy workpiece, and the direct current forward connection electrode is arranged behind, so that the welding of large-thickness aluminum alloy can be realized.

Specifically, in the preferred embodiment of the present invention, two insulating sleeves 15 are disposed above the compression nozzle 13, and two electrode receiving chambers 112 are opened in the two insulating sleeves 15, respectively. When the electrode is installed in the electrode accommodating cavity 112, the insulating sleeve 15 plays an insulating role, and the safety and the stability of the welding process are improved.

Preferably, in the present embodiment, a fixing mechanism 14 is provided between the insulating sleeve 15 and the compression nozzle 13 for fixing the insulating sleeve 15 and the compression nozzle 13.

Preferably, the compression nozzle 13 has a composite arc outlet 131 for ejecting the laser beam 2 and the plasma arc 3, a shielding gas ejection channel 16 is disposed on a side wall of the compression nozzle 13, the shielding gas ejection channel 16 is communicated with the laser beam channel 111, the laser beam channel 111 is also used for allowing the ion gas and the shielding gas to pass through, one end of the shielding gas ejection channel 16 is communicated with the laser beam channel 111, and the other end of the shielding gas ejection channel extends towards a direction close to the composite arc outlet 131 and is communicated with the outside, so that the shielding gas is ejected from the shielding gas ejection channel 16 to form a shielding gas hood 6, and the laser beam 2 and the plasma arc 3 are protected in the shielding gas hood 6.

During welding, the shielding gas and the ion gas are the same gas, the gas is introduced into the compression nozzle 13 through the laser beam 111, a part of the gas serving as the ion gas is ionized into a plasma arc 3 under the action of the laser and the electrode, the plasma arc 3 and the laser beam 2 are ejected out from the composite arc outlet 131 together, the other part of the gas serving as the shielding gas is ejected out from the shielding gas ejection channel 16, and the part of the shielding gas plays the roles of protecting the laser beam and the plasma arc on one hand and also serves as cooling gas on the other hand.

The embodiment of the invention also provides an aluminum alloy composite welding gun, which comprises a laser beam emitting mechanism and two electrodes with different polarities: the first electrode 11 and the second electrode 12, and the composite welding head 10 of aluminum alloy according to the embodiment of the present invention, the laser beam 2 emitted from the laser beam emitting mechanism passes through the laser beam passage 111 to emit the laser beam 2 from the compression nozzle 131, and the two electrodes having different polarities are respectively disposed in the two electrode receiving chambers 112 to emit the plasma arc 3 from the compression nozzle 131.

Preferably, the arc starting end of each electrode is tapered with the tip of the taper facing the composite arc outlet 131. The structural design of the arc starting end can ensure that the electric arc is more stable compared with the structural design of a spherical heat storage body type, the structure is simple, and the large-scale production cost is lower.

When the aluminum alloy composite welding gun is used, the power supply is switched on, the shielding gas enters the compression nozzle 13 from the laser beam channel 111, the laser beam 2 and the plasma arc 3 are ejected from the composite arc outlet 131 along the direction of the laser beam axis 1, namely, the gas serving as the shielding gas and the ion gas enters the compression nozzle 13 from the laser beam channel 111, a part of the gas is ionized into the plasma arc 3 under the action of the laser beam 2 and the electrode, the plasma arc 3 and the laser beam 2 are ejected from the composite arc outlet 131 together, the other part of the gas serving as the shielding gas is ejected from the shielding gas ejection channel 16 to form a shielding gas hood 6 around the plasma arc 3 and the laser beam 2 to play a role of the shielding gas, and the part of the shielding gas is also contacted with a molten pool and can play a role of cooling.

The features and properties of the present invention are described in further detail below with reference to examples.