A laser-assisted arc welding method for butt welding of shaft parts

Abstract

This invention discloses a laser-assisted arc welding method for butt welding of shaft parts. First, the end faces of the shafts are mechanically ground and cleaned to remove oxide layers and impurities. Then, they are aligned and a gap is left. Two laser beams are used to irradiate the end faces at a certain angle, forming metal vapor, which is then ignited by an arc-starting device. During laser scanning, the arc continuously heats and melts the welding area. The lasers are turned off, the arc is extinguished, and the two shafts move towards each other to contact and apply upsetting force, forming a welded joint. This method eliminates the need for beveling and filler material, provides uniform and rapid heating, and produces a tight weld joint. It significantly improves joint quality and welding efficiency and is suitable for welding shaft parts of various materials, both similar and dissimilar.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically relating to a laser-assisted arc welding method for butt welding of shaft parts. Background Technology

[0002] Shafts play a vital role in mechanical transmissions, rotating mechanisms, and high-precision equipment, and are widely used in automotive transmission shafts, aircraft engine shafts, and industrial machinery spindles. Welding is one of the key processes in shaft manufacturing. For large, complex, or application-specific shafts, integral manufacturing often faces limitations in equipment capacity, material supply, or economic costs, frequently requiring welding to join multiple sections into a complete shaft. Some shafts also require the use of different materials in different areas, achieving the connection of these materials through welding to optimize shaft performance and cost. These shafts typically operate under high loads, strong impacts, or high-speed rotation conditions, and the quality of their weld joints directly affects the equipment's performance and operational reliability. Therefore, improving weld joint quality and welding efficiency is a key research direction in the field of welding technology.

[0003] Currently, welding of shaft parts mainly employs electric arc welding. For example, Xiao Dezheng, in his article "Research on Assembly and Welding Process of Main Drive Shaft of Rolling Mill Coupling" published in the welding machine journal, proposed an assembly and welding process that uses gas shielded welding for the root pass, submerged arc welding for the fill pass, and cap pass. By controlling welding deformation through a reasonable welding sequence, the coaxiality of the shaft parts is ensured. Patent document CN101898271A proposes an assembly and welding method for solid shafts, using a rotating support and internal backing plate for welding, and employing manual electric arc welding for the root pass and submerged arc welding for the fill pass. Both of these electric arc welding methods require pre-beveling the shaft and using multiple layers and passes, resulting in low welding efficiency and a high risk of welding defects. Furthermore, the use of welding rods or wires to laterally heat the welding surface during welding easily leads to axial asymmetry in the weld joint. In the context of the rapid development of the current manufacturing industry, there is an urgent need for a new method that can guarantee the quality of weld joints and improve welding efficiency. Summary of the Invention

[0004] To address the problems of welding defects, low efficiency, and axial asymmetry that are common in traditional shaft welding methods, this invention aims to provide a laser-assisted arc welding method for butt welding of shaft parts. This method eliminates the need for beveling and filler material, achieving high-quality and high-efficiency welding through the synergistic effect of direct arc initiation between the shafts, laser-assisted heating, and axial pressure upsetting. Direct arc initiation between the two shaft end faces ensures good axial symmetry of heating while avoiding the complex operations of beveling and filler material. The addition of laser guides the arc, increases heat input, and makes the heating of the welding area more uniform and controllable. It also has an etching effect on the welding end faces, creating a serrated interlocking structure. Upsetting after heating places the weld joint in a compressive stress state, effectively improving the joint strength. This achieves uniform heating and efficient welding of the welding end faces, significantly improving the quality and efficiency of the weld joint, and meeting the welding needs of various shafts made of the same or different materials.

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

[0006] This invention provides a laser-assisted arc welding method for butt welding of shaft-type 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 cleaning solution, 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 material forms metal vapor under the laser irradiation, and use an arc-initiating device to induce an electric arc between the two shafts.

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

[0010] Step 4: Turn off the laser and extinguish the arc. At the same time, the two axes move towards each other and make contact, and apply upsetting force to form a welded joint.

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

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

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

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

[0015] Preferably, in step two, the arc-initiating device is a high-frequency high-voltage arc initiation device or a high-voltage arc initiation device.

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

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

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

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

[0020] 1. This invention eliminates the need for beveling and filler materials, and eliminates the need for multi-layer and multi-pass welding. It adopts a direct arc initiation method between two axes, which significantly improves welding efficiency.

[0021] 2. This invention utilizes the induction effect of laser on electric arc to make the welding end face heat up evenly and controllably. The compressive stress formed by post-weld upsetting and the sawtooth interlocking structure formed by laser etching significantly improve the bonding strength and fatigue resistance of the welded joint.

[0022] 3. This invention directly heats the two vertical end faces without using external welding rods or wires, resulting in good axial symmetry of the heating and effectively reducing axial deformation.

[0023] 4. By optimizing welding parameters (such as laser power, welding current, laser scanning path, etc.), this invention can flexibly adapt to the welding of shaft parts made of various materials (such as nickel-based alloys, stainless steel, high-strength steel, etc.) and dissimilar materials (such as nickel-based alloys-stainless steel, dissimilar steel, etc.), and has strong applicability. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the laser-assisted arc welding device used for butt welding of shaft parts in the embodiment.

[0025] Figure 2 This is a schematic diagram illustrating the arc-inducing effect of laser in the embodiment;

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

[0027] Figure 4 This is a schematic diagram of the laser spiral scanning path in the embodiment;

[0028] Figure 5 This is a schematic diagram of the macroscopic structure of the welded joint in the embodiment;

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

[0030] The attached diagram is labeled as follows: 1-Left axis, 2-Right axis, 3-Chuck, 4-Welding power source, 5-Safety gas cylinder, 6-Gas gauge, 7-Laser emitter head 1, 8-Laser emitter head 2, 9-Laser fixing device, 10-Laser 1, 11-Laser 2, 12-Laser 1, 13-Laser 2, 14-Fiber optic cable for Laser 1, 15-Fiber optic cable for Laser 2, 16-Power cable for Laser 1, 17-Power cable for Laser 2, 18-Controller, 19-Driver Structure, 20-Computer, 21-Left axis end face, 22-Right axis end face, 23-Interaxial arc, 24-Left axis zigzag laser optical path, 25-Right axis zigzag laser optical path, 26-Left axis spiral laser optical path, 27-Right axis spiral laser optical path, 28-Welding joint, 29-Selective area welding joint, 30-Serrated interlocking structure, 31-Left axis molten part, 32-Right axis molten part, 33-Left axis unmelted part, 34-Right axis unmelted part. Detailed Implementation

[0031] The present invention will now be described in conjunction with the accompanying drawings and specific embodiments.

[0032] The following embodiments provide a laser-assisted arc welding method for butt welding of shaft-type 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. Clean 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 (ranging from 0.5mm to 5mm). Introduce high-purity protective gas (such as argon, helium, or carbon dioxide) into the welding area to prevent oxidation or impurities from entering during the welding process.

[0034] Step 2: Irradiate the end faces of the two shafts with two laser beams at a certain angle (30° to 60°), causing the end face material to form metal vapor under laser irradiation. An arc is then ignited between the two shafts using an arc-initiating device. Since metal vapor is more conducive to arc generation, the arc-initiating position is the laser irradiation position. Laser parameters are adjusted according to the specific material size and type, with laser power ranging from 200W to 3000W and laser spot diameter ranging from 0.5mm to 2.0mm.

[0035] Step 3: Two laser beams scan the two end faces of the axes in a zigzag or spiral path, covering the entire end face, at a scanning speed of 6 mm / s to 12 mm / s. To create a serrated interlocking structure on the end faces, the scanning paths of the two end faces are offset vertically by 0.5 mm to 2.0 mm. Simultaneously with the laser scanning, an electric arc continuously heats the welding area. Due to laser induction, the arc ignition point moves continuously along the laser scanning path. To ensure uniform heating of the welded end faces, the arc ignition time is adjusted according to the material size and type, ranging from 1 second to 5 seconds.

[0036] Step 4: After a period of time, extinguish the electric arc and turn off the two laser beams. Simultaneously, drive the two shafts to move axially towards each other through the drive mechanism, so that the end faces of the weld 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 application time is from 0.5s to 2.0s.

[0037] like Figure 1 As shown in the following embodiment, a laser-assisted arc welding device for butt welding of shaft parts is provided, 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 gauge 6, two laser emitters 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, ensuring the coaxiality and stability of the workpiece; the protective gas cylinder 5 provides gas protection to prevent the welding area from being contaminated by air at high temperatures; the laser head fixing device 9 fixes the laser emitters 7 and 8 and adjusts the laser emission angle; the computer 18 controls the welding process through the controller 17, including laser emission, arc ignition, arc burning, and welding material clamping.

[0038] Laser-induced arc-induced effect, such as Figure 2 As shown, two laser beams 10 and 11 are emitted by laser heads 7 and 8, respectively, and irradiate the left shaft end face 21 and the right shaft end face 22, heating the welding end faces. Since the metal vapor generated by laser heating is more easily ionized than the shielding gas, it provides a good conductive path for the electric arc. The ignition point of the arc always follows the laser irradiation point, and the laser scans the two shaft end faces as a whole, thus heating the entire end face.

[0039] There are two modes for laser scanning paths:

[0040] mode one Figure 3As shown, two laser beams scan the two end faces 21 and 22 along broken lines 24 and 25, respectively, covering the entire end face. Since the penetration depth is deeper where the laser is scanned and shallower where it is not scanned, the laser scanning paths on the two end faces are offset vertically by a certain distance. This causes the area with more melting on the left shaft to overlap with the area with less melting on the right shaft, forming a serrated interlocking joint, suitable for welding smaller shaft parts.

[0041] Mode 2, for example Figure 4 As shown, two laser beams scan the two shaft end faces 21 and 22 along spiral paths 26 and 27, respectively, with the laser scanning paths covering the entire end face. The laser scanning paths on the two end faces are staggered vertically by a certain distance, and the spiral scanning paths can form a more complex sawtooth interlocking structure on the welding end face, which is suitable for welding larger shaft parts.

[0042] Figure 5 This is a schematic diagram of the macroscopic structure of the welded joint. After welding, the left axis 1 and right axis 2 are heated by the combined action of the inter-axis electric arc 23 and lasers 10 and 11, and then forged to form a compact welded joint 28. When using alternating current, the heat input to the positive and negative poles is relatively balanced, and the shape of the welded joint is usually more symmetrical, with a more uniform distribution of the melting area. However, under DC welding conditions, due to the significant difference in heat input between the positive and negative poles, the melting amount on the left side is significantly greater than that on the right side, resulting in an asymmetric welded joint. Inconsistencies in current magnitude and laser power between the left and right sides can also affect the melting amount, leading to asymmetry in the welded joint.

[0043] Figure 5 The microstructure of the weld area selected by the dashed line is as follows: Figure 6 As shown, the details of the weld area are illustrated. The left axis 1 includes a molten portion 31 and an unmolten portion 33, while the right axis 2 includes a molten portion 32 and an unmolten portion 34. The joint between the two axes has a serrated structure 30. The joint between the two axes often exhibits uneven chemical composition, making it the weakest point in the weld joint. This serrated interlocking structure significantly increases the contact area of ​​the interface and improves the interfacial bonding strength.

[0044] Example 1

[0045] Laser-assisted arc welding was used to butt-weld two shafts made of different materials. The first shaft was made of Inconel 718 nickel-based alloy, and the other shaft was made of 35CrMo steel. Both shafts were 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 terminal of the power supply, and the 35CrMo steel was connected to the negative terminal. The welding parameters were: arc current of 700 A, laser power of 600 W for the nickel-based alloy side and 900 W for the steel side, to balance the heat input on both sides. The laser scanning path adopted a zigzag path, and the scanning speed was 7 mm / s. The zigzag path design can achieve uniform heat distribution in the welding area, avoid local overheating, and form a wavy structure on the weld end face, improving the mechanical properties and fatigue resistance of the joint.

[0046] Before welding, the surface of the workpiece is ground using a mechanical grinding tool to remove the oxide layer and surface impurities. Subsequently, the surface is cleaned with propanol and alcohol solutions to remove oil and ensure the cleanliness of the welding area, providing a good metal-to-metal contact surface for subsequent welding processes. During operation, the nickel-based alloy and steel parts are fixed to the welding device using chuck 3, ensuring that the two end faces are coaxial and maintain a 2mm gap. Simultaneously, 99.999% high-purity argon gas is introduced to protect the welding area. After the laser is activated, laser emitters 7 and 8 irradiate the two welding end faces respectively, while lasers 10 and 11 heat the welding area at high temperatures and evaporate to form laser vapor. The generation of laser vapor causes the high-frequency arc ignition device to successfully ignite an inter-axis electric arc 23. The arc ignition point always follows the laser irradiation point, and the laser scans the two shaft end faces as a whole, with the arc heating the entire end face accordingly. The electric arc and laser work together to heat the welding area, forming a stable molten pool. After 5 seconds of welding, both the electric arc and laser are simultaneously turned off. Subsequently, the drive mechanism 18 pushes the left shaft 1 and the right shaft 2 to move towards each other along the axial direction, and they come into contact and remain in contact for 3 seconds under the action of 2kN axial pressure, finally forming a welded joint with good density and high bonding strength.

[0047] Example 2

[0048] Laser-assisted arc welding was used for butt welding of shaft parts, with the welding materials being dissimilar metals 304 stainless steel and 45 steel. The shaft parts, made of both materials, are circular, with a diameter of 80 mm and a length of 150 mm. During welding, AC power was used, with welding parameters set as follows: arc current 750 A, laser power 600 W for the stainless steel side and 400 W for the 45 steel side, and a helical laser scanning path at a scanning speed of 5 mm / s. The helical path design creates a complex serrated interlocking structure on the weld face, enhancing the weld's bonding strength and fatigue resistance.

[0049] Before welding, the surfaces of the workpieces are ground and cleaned to ensure welding quality. During operation, stainless steel and 45 steel parts are fixed to the welding device using chuck 3, ensuring that the two end faces are coaxial and maintain a 2.5mm gap. High-purity argon gas is simultaneously introduced to protect the welding area. Laser emitters 7 and 8 are activated, and lasers 10 and 11 heat the welding area to a high temperature, forming metal vapor. Subsequently, an inter-axial arc 23 is ignited by a high-frequency arc-initiating device, working in conjunction with the laser for welding. After 4 seconds of welding, the arc and laser are sequentially shut off. Then, the drive mechanism 18 pushes the two shaft-like parts to move axially towards each other, contacting and maintaining contact for 4 seconds under an axial pressure of 3kN, ultimately forming a stable, high-quality weld joint. If high dimensional requirements are needed for the joint, the weld area can be adjusted and optimized through subsequent machining (such as turning, milling, or grinding). Machining effectively removes excess material from the weld surface, eliminating dimensional deviations or asymmetries caused by differences in melting amount.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser-assisted arc welding method for butt welding of shaft-type parts, characterized in that, Includes the following steps: 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 solution, align the end faces of the two shafts, leaving a gap between them, and introduce a protective gas to protect the welding area. The range of the end face gap is 0.5-5.0 mm, and the end face gap is adjusted according to the material and size of the two shafts. Step 2: Use two laser beams to irradiate the end faces of the two shafts at a certain angle, causing the end face material to form metal vapor under laser irradiation. Use an arc-initiating device to ignite an electric arc between the two shafts. The angle between the laser and the end face of the shaft is 30°-60°, the laser power range is 200-3000 W, the laser spot diameter is 0.5-2.0 mm, and the arc-initiating device is a high-voltage arc initiation device. Step 3: While maintaining the two laser beams irradiating the end faces of the shafts, control the lasers to scan the end faces along a set path. During the laser scanning process, the electric arc continuously heats and melts the welding area. The laser scanning path is either zigzag or spiral, and the laser scanning paths of the two shaft end faces are offset vertically by 0.5-2.0 mm. The current of the electric arc is 300-2000 A, and the arc burning time is 1-5 s. Step 4: Turn off the laser and extinguish the electric arc. At the same time, the two shafts move towards each other and make contact, and apply upsetting pressure to form a sawtooth interlocking weld joint. The upsetting pressure is 0.5-5.0 kN and the upsetting pressure application time is 0.5-2 s. Alternating current is used in the welding process.

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

3. The laser-assisted arc welding method for butt welding of shaft parts according to claim 1, characterized in that, In step one, the protective gas is argon or helium.

4. The laser-assisted arc welding method for butt welding of shaft parts according to claim 1, characterized in that, In step two, the arc-initiating device is a high-frequency, high-voltage arc-initiating device.

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