Laser-assisted arc welding method for butt joint of shaft parts

Abstract

The invention discloses a laser-assisted arc welding method for butt joint of shaft parts, which comprises the following steps: firstly, mechanically polishing and cleaning the end surface of a shaft to remove an oxide layer and impurities, and then aligning and reserving a gap; two laser beams are used for irradiating the end face at a certain angle to form metal steam, and an arc striking device is used for triggering an electric arc; the electric arc continuously heats and melts the welding area in the laser scanning process; and closing the laser, quenching the electric arc, enabling the two shafts to oppositely move and contact, and applying an upsetting force to form a welding joint. According to the method, beveling and welding material filling are not needed, heating is uniform, the speed is high, a welded joint is compact, the joint quality and the welding efficiency can be remarkably improved, and the method is suitable for welding of various shaft parts made of the same or different materials.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a laser-assisted arc welding method for butt-jointing shaft parts. Background Art

[0002] Shaft parts play an important role in mechanical transmission, rotating mechanisms and high-precision equipment, and are widely used in the fields of automobile transmission shafts, aircraft engine shafts, industrial machinery spindles, etc. Welding is one of the important processes in the manufacture of shaft parts. For large, complex or special-purpose shaft parts, the overall manufacturing is often limited by equipment capacity, material supply or economic cost, and welding is often required to splice multiple sections of parts into a complete shaft. Some shaft parts also need to use different materials in different parts, and welding is used to connect different materials to optimize the performance and cost of the shaft. These shaft parts usually work under high load, strong impact or high-speed rotation conditions, and the quality of their welded joints directly affects the performance and operational reliability of the equipment. Therefore, improving the quality of welded joints and welding efficiency is a key research direction in the field of welding technology.

[0003] The existing welding of shaft parts mainly adopts arc welding method. For example, Xiao Dezheng proposed a welding process in the welding machine journal "Study on Assembly Welding Process of Main Drive Shaft of Rolling Mill Coupling", which adopts gas shielded welding for base, submerged arc welding for filling and covering, and controls welding deformation through a reasonable welding sequence to ensure the coaxiality of shaft parts. Patent document CN101898271A proposes a welding method for solid shafts, which realizes welding through tire support and internal pads, and adopts manual arc welding for base and submerged arc welding for filling. The above arc welding methods all require pre-grooving on the shaft, and use multi-layer and multi-pass methods to complete welding. The welding efficiency is low and welding defects are easy to occur. In addition, since the welding rod or welding wire is used to heat the welding surface laterally during the welding process, it is easy to cause axial asymmetry in the welded joint. In the context of the rapid development of the current manufacturing industry, a new method that can ensure the quality of welded joints and improve welding efficiency is urgently needed. Summary of the invention

[0004] In order to solve the problems of welding defects, low efficiency and axial asymmetry that are prone to occur in traditional shaft parts welding methods, the purpose of the present invention is to provide a laser-assisted arc welding method for butt-jointing shaft parts, which is a welding method that does not require groove opening and filling of welding materials. Through the synergistic effect of direct arc starting between the shafts, laser-assisted heating and axial pressure upsetting, high-quality and high-efficiency welding is achieved. Direct arc starting between the two shaft end faces ensures good axial symmetry of heating, while avoiding the complex operation of groove design and welding material filling; the addition of laser can guide the arc, increase heat input, make the heating of the welding area more uniform and controllable, and also have an etching effect on the welding end face to form a serrated bite structure; upsetting after heating is completed puts the weld joint in a compressive stress state, effectively improves the bonding strength of the joint, realizes uniform heating and efficient welding of the welding end face, significantly improves the quality of the weld joint and welding efficiency, and can meet the welding needs of various shafts of the same or different materials.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a laser-assisted arc welding method for butt-jointing shaft parts, comprising the following steps:

[0007] Step 1: Mechanically grind the end faces of the two shafts to remove the oxide layer and impurities, clean the end faces with a cleaning fluid, align the end faces of the two shafts, leave a certain gap between the end faces, and introduce protective gas to protect the welding area;

[0008] Step 2: Use two laser beams to irradiate the end faces of the two shafts at a certain angle, so that the end face materials form metal vapor under the irradiation of the laser, and use an arc-starting device to induce an arc between the two shafts;

[0009] Step 3: While maintaining the two laser beams irradiating, control the laser to scan the end surface along a certain path, and the arc continues to heat and melt the welding area during the laser scanning process;

[0010] Step 4: Turn off the laser, extinguish the arc, and at the same time, move the two axes toward each other and contact each other, and apply a forging force to form a welding joint.

[0011] Preferably, in step one, the cleaning solution includes propanol or an alcohol solution, which is used to remove oil stains on the surface of the weldment.

[0012] Preferably, in step one, the end face clearance ranges from 0.5 to 5.0 mm, which is adjusted according to the material and size of the shaft parts.

[0013] Preferably, in step 1, the protective gas is argon, helium or carbon dioxide.

[0014] Preferably, in step 2, the angle between the laser and the end face of the weldment is 30°-60°, the laser power range is 200-3000W, and the laser spot diameter is 0.5-2.0mm.

[0015] Preferably, in step 2, the arc starting device is a high-frequency high-voltage arc starting device or a high-voltage arc starting device.

[0016] Preferably, in step three, the laser scanning path is in a zigzag or spiral shape, and the scanning paths of the two end faces are offset up and down by 0.5-2.0 mm.

[0017] Preferably, in step three, the current of the welding arc is 300-2000A, and the arcing time is 1-5s.

[0018] Preferably, in step 4, the upsetting pressure is 0.5-5.0 kN, and the upsetting pressure action time is 0.5-2 s.

[0019] Compared with the prior art, the present invention provides a laser-assisted arc welding method for butt-jointing shaft parts as described above, which has the following beneficial effects:

[0020] 1. The present invention does not require beveling and filling welding materials, does not require multi-layer and multi-pass welding, and adopts a direct arc starting method between two shafts, which significantly improves welding efficiency.

[0021] 2. The present invention utilizes the induction effect of laser on the arc to make the heating of the welding end face uniform and controllable. The compressive stress formed by the upsetting after welding and the serrated bite structure formed by the laser etching significantly improve the bonding strength and fatigue resistance of the welded joint.

[0022] 3. The present invention directly heats the two vertical end faces without using an external welding rod or welding wire for heating. The axial symmetry of the heating is good, and the axial deformation is effectively reduced.

[0023] 4. The present invention can flexibly adapt to the welding of shaft parts of various materials of the same material (such as nickel-based alloy, stainless steel, high-strength steel, etc.) and dissimilar materials (such as nickel-based alloy-stainless steel, dissimilar steel, etc.) by optimizing welding parameters (such as laser power, welding current, laser scanning path, etc.), and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the structure of a laser-assisted arc welding device for butt-jointing shaft parts in an embodiment;

[0025] Figure 2 Schematic diagram of the effect of laser on arc induction in the embodiment;

[0026] Figure 3 This is a schematic diagram of the laser fold line scanning path in the embodiment;

[0027] Figure 4 Schematic diagram of the laser spiral scanning path in the embodiment;

[0028] Figure 5 A schematic diagram of the macroscopic structure of a welding joint in an embodiment;

[0029] Figure 6 A schematic diagram of the microstructure of a welded joint in an embodiment;

[0030] The accompanying drawings are marked as follows: 1-left axis, 2-right axis, 3-chuck, 4-welding power supply, 5-protective gas cylinder, 6-gas meter, 7-laser transmitter head 1, 8-laser transmitter head 2, 9-laser fixing device, 10-laser 1, 11-laser 2, 12-laser 1, 13-laser 2, 14-laser 1 optical fiber, 15-laser 2 optical fiber, 16-laser 1 power cord, 17-laser 2 power cord, 18-controller, 19-drive machine Structure, 20-computer, 21-left shaft end face, 22-right shaft end face, 23-inter-axis arc, 24-left shaft folded line laser light path, 25-right shaft folded line laser light path, 26-left shaft spiral laser light path, 27-right shaft spiral laser light path, 28-welded joint, 29-selective area welded joint, 30-serrated bite structure, 31-left shaft melted part, 32-right shaft melted part, 33-left shaft unmelted part, 34-right shaft unmelted part. DETAILED DESCRIPTION

[0031] The present invention is described below in conjunction with the accompanying drawings and specific embodiments.

[0032] The following embodiment provides a laser-assisted arc welding method for butt-jointing shaft parts, comprising the following steps:

[0033] Step 1: Mechanically grind the end faces of the two shaft parts to remove the oxide layer and surface impurities, and clean them with propanol or alcohol solution to ensure the cleanliness of the welding area; align the end faces of the two shaft parts and adjust the gap between the end faces (range 0.5mm to 5mm), and pass high-purity protective gas (such as argon, helium or carbon dioxide) into the welding area to avoid oxidation or impurities during welding.

[0034] Step 2: Use two laser beams to irradiate the end faces of the two shafts at a certain angle (30° to 60°) so that the end face material forms metal vapor under laser irradiation, and use an arc-starting device to initiate an arc between the two shafts. Since metal vapor is more conducive to arc generation, the arc-starting position is the laser irradiation position. The laser parameters are adjusted according to the specific material size and type. The laser power range is 200W to 3000W, and the laser spot diameter range is 0.5mm to 2.0mm.

[0035] Step 3: Two laser beams scan the end faces of the two shafts in a zigzag or spiral path. The scanning range covers the entire end face, and the scanning speed is 6mm / s to 12mm / s. In order to form a serrated bite structure on the end face, the scanning paths of the two end faces are offset by 0.5mm to 2.0mm up and down as a whole. While the laser is scanning, the arc continues to heat the welding area. Due to the laser induction effect, the arc ignition point of the arc keeps moving along the laser scanning path. In order to ensure that the welding end face is evenly heated, the arc burning time is adjusted according to the material size and type, ranging from 1s to 5s.

[0036] Step 4: After a period of time, extinguish the arc and turn off the two laser beams, and at the same time, push the two shafts to move axially toward each other through the driving mechanism to make the end faces of the welding joint contact. Then apply a certain upsetting pressure to complete the butt welding of the two shafts. The upsetting pressure ranges from 0.5kN to 5kN, and the upsetting pressure action time is 0.5s to 2.0s.

[0037] like Figure 1 As shown, the following embodiment provides a laser-assisted arc welding device for butt joint of shaft parts, including: a left shaft 1 and a right shaft 2, a chuck 3, a welding power source 4, a protective gas cylinder 5, a gas meter 6, two laser emission heads 7 and 8, a laser head fixing device 9, two lasers 12 and 13, a controller 17, and a computer 18. The chuck 3 is used to fix the left shaft 1 and the right shaft 2 to ensure the coaxiality and stability of the workpiece; the protective gas cylinder 5 provides gas protection to prevent the welding area from being polluted by air at high temperature; the laser head fixing device 9 fixes the laser emission heads 7 and 8 and adjusts the laser emission angle; the computer 18 controls the welding process through the controller 17, including laser emission, arc starting, arc burning and welding material pressing.

[0038] The effect of laser on arc induction is as follows Figure 2 As shown, two laser beams 10 and 11 are respectively irradiated to the left shaft end face 21 and the right shaft end face 22 through the laser emitting heads 7 and 8 to heat the welding end faces. Since the metal vapor generated by laser heating is easier to ionize than the shielding gas, it is a good conductive channel for the arc. The arc burning point always follows the movement of the laser irradiation point. The laser scans the two shaft end faces as a whole, and the arc also heats the entire end face accordingly.

[0039] The laser scanning path has two modes:

[0040] Same pattern Figure 3As shown, two laser beams scan the two shaft end faces 21 and 22 along the paths of broken lines 24 and 25, respectively, and the laser scanning path covers the entire end face. Since the laser scanning area has a deeper melting depth, while the non-scanning area has a shallower melting depth, the laser scanning paths on the two end faces are offset up and down by a certain distance as a whole, so that the more melted area of ​​the left shaft and the less melted area of ​​the right shaft overlap exactly, forming a serrated bite joint, which is suitable for welding of smaller shaft parts.

[0041] Mode 2 Figure 4 As shown, two laser beams scan the two shaft end faces 21 and 22 respectively along the paths of spiral lines 26 and 27, and the laser scanning path covers the entire end face. The laser scanning paths on the two end faces are generally offset up and down by a certain distance, and the spiral scanning path can form a more complex sawtooth bite structure on the welding end face, which is suitable for welding larger shaft parts.

[0042] Figure 5 The figure is a schematic diagram of the macroscopic structure of the welded joint. After welding, the left shaft 1 and the right shaft 2 are heated by the combined action of the inter-axial arc 23 and the lasers 10 and 11, and forged to form a compact welded joint 28. When using alternating current, the heat input of the positive and negative electrodes is relatively balanced, the shape of the welded joint is usually more symmetrical, and the distribution of the melting area is also more uniform; under direct current welding conditions, due to the significant difference in heat input between the positive and negative electrodes, the amount of melting on the left is significantly greater than that on the right, and the welded joint is asymmetric. When the current size and laser power are inconsistent on the left and right, it will also affect the amount of melting, resulting in asymmetry in the welded joint.

[0043] Figure 5 The microstructure of the weld area selected by the dashed line is shown in Figure 6 As shown, the details of the weld area are shown. The left shaft 1 includes a melted portion 31 and an unmelted portion 33, and the right shaft 2 includes a melted portion 32 and an unmelted portion 34. The joint between the left and right shafts is a serrated structure 30. The joint between the two shafts often has chemical composition inhomogeneity, which is often the weakest link of the welded joint. This serrated bite structure greatly increases the contact area of ​​the interface and improves the interface bonding strength.

[0044] Example 1

[0045] Laser-assisted arc welding was used to butt-weld two shafts of different materials. The first shaft was made of nickel-based alloy Inconel 718, and the other shaft was made of 35CrMo steel. Both shafts are cylindrical, with a diameter of 40 mm and a length of 100 mm. During the welding process, the nickel-based alloy was connected to the positive pole of the power supply, and the 35CrMo steel was connected to the negative pole of the power supply. The welding parameters were an arc current of 700 A, and the laser power was 600 W on the nickel-based alloy side and 900 W on the steel side to balance the heat input on both sides. The laser scanning path adopted a zigzag path with a scanning speed of 7 mm / s. The zigzag path design can achieve uniform heat distribution in the welding area and avoid local overheating. At the same time, a wavy structure is formed on the welding end face to improve the mechanical properties and fatigue resistance of the joint.

[0046] Before welding, a mechanical grinding tool is used to grind the surface of the weldment to remove the oxide layer and surface impurities. Subsequently, the surface of the weldment is cleaned with propanol and alcohol solution respectively to remove oil stains, ensure the cleanliness of the welding area, and provide a good metal contact surface for the subsequent welding process. During operation, the nickel-based alloy and the steel parts are fixed on the welding device through the chuck 3 to ensure that the two end faces are coaxial and maintain a 2mm gap. At the same time, 99.999% high-purity argon gas is introduced to protect the welding area. After starting the laser, the laser emitters 7 and 8 irradiate the welding end faces on both sides respectively, and the lasers 10 and 11 heat the welding area at high temperature and evaporate to form laser steam. The generation of laser steam prompts the high-frequency arc ignition device to successfully trigger the inter-axial arc 23. The arc burning point of the arc always follows the movement of the laser irradiation point. The laser scans the two shaft end faces as a whole, and the arc also heats the entire end face. The arc and the laser synergistically heat the welding area to form a stable molten pool. After the welding time reaches 5s, the arc and the laser are turned off at the same time. Subsequently, the left shaft 1 and the right shaft 2 are pushed to move toward each other in the axial direction by the driving mechanism 18, and are in contact and maintained for 3 seconds under the action of an axial pressure of 2 kN, thereby finally forming a welded joint with good density and high bonding strength.

[0047] Example 2

[0048] Laser-assisted arc welding is used for butt welding of shaft parts, and the welding materials are 304 stainless steel and 45 steel dissimilar metal materials. The shaft parts of the two materials are round shaft parts with a diameter of 80mm and a length of 150mm. During the welding process, alternating current is used, the welding parameters are set to an arc current of 750A, the laser power is 600W on the stainless steel side and 400W on the 45 steel side, the laser scanning path is a spiral path, and the scanning speed is 5mm / s. The design of the spiral path can form a complex serrated bite structure on the welding end face, enhancing the bonding strength and fatigue resistance of the weld.

[0049] Before welding, the weldment surface is polished and cleaned to ensure the welding quality. During operation, the stainless steel and 45 steel parts are fixed on the welding device through the chuck 3 to ensure that the two end faces are coaxial and maintain a gap of 2.5 mm, and high-purity argon gas is introduced to protect the welding area. The laser emitters 7 and 8 are started, and the lasers 10 and 11 heat the welding area at high temperature and form metal vapor. Subsequently, the inter-axial arc 23 is triggered by the high-frequency arc ignition device, and the welding is carried out in coordination with the laser. After the welding time reaches 4s, the arc and the laser are turned off in turn. Subsequently, the two shaft parts are pushed to move toward each other in the axial direction through the driving mechanism 18, and the contact is maintained for 4s under the axial pressure of 3kN, and finally a stable and high-quality welded joint is formed. If the joint forming size requirements are high, the weld area can be adjusted and optimized through subsequent machining (such as turning, milling or grinding). Machining can effectively remove excess material on the weld surface and eliminate dimensional deviation or asymmetry caused by differences in melting amount.

[0050] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser-assisted arc welding method for butt-jointing shaft parts, characterized in that: The following steps are involved: Step 1: Mechanically grind the end faces of the two shafts to remove the oxide layer and impurities, clean the end faces with a cleaning fluid, align the end faces of the two shafts, leave a gap between the end faces, and introduce protective gas to protect the welding area; Step 2: Use two laser beams to irradiate the end faces of the two shafts at a certain angle, so that the end face materials form metal vapor under the irradiation of the laser, and use an arc-starting device to induce an arc between the two shafts; Step 3: While maintaining the two laser beams irradiating, control the laser to scan the end surface according to the set path, and the arc continues to heat and melt the welding area during the laser scanning process; Step 4: Turn off the laser, extinguish the arc, and at the same time, move the two axes toward each other and contact each other, and apply a forging force to form a welding joint.

2. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step 1, the cleaning solution includes propanol or alcohol solution, which is used to remove oil stains on the surface of the weldment.

3. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step 1, the end face clearance ranges from 0.5 to 5.0 mm, which is adjusted according to the material and size of the shaft parts.

4. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step 1, the protective gas is argon, helium or carbon dioxide.

5. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step 2, the angle between the laser and the end face of the weldment is 30°-60°, the laser power range is 200-3000W, and the laser spot diameter is 0.5-2.0mm.

6. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step 2, the arc starting device is a high-frequency high-voltage arc starting device or a high-voltage arc starting device.

7. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step three, the laser scanning path is in a zigzag or spiral shape, and the scanning paths of the two end faces are offset by 0.5-2.0 mm up and down.

8. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step three, the current of the welding arc is 300-2000A, and the arc burning time is 1-5s.

9. The laser-assisted arc welding method for butt-jointing shaft parts according to claim 1, characterized in that: In step 4, the upsetting pressure is 0.5-5.0 kN, and the upsetting pressure action time is 0.5-2 s.

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