An additive manufacturing method for ultra-wide and ultra-thin welds using a plasma arc and laser composite heat source

Abstract

The present invention is an additive method for achieving ultra-wide and ultra-thin welds using a composite heat source of plasma arc and laser. The specific steps of the method are as follows: Step 1: Adjust the relative positions of the arc welding gun and the laser output head, set the collaborative working mode of the arc and laser, and attach two symmetrical time-sharing scanning laser heat sources behind the molten pool. Step 2: Debug the current and voltage of the equipment, select the arc power, gas type and gas flow, wire feed speed, and welding speed parameters; Step 3: Select a suitable substrate and grind the substrate surface with a grinding wheel. Then preheat the substrate to a predetermined temperature; Step 4: Start the manufacturing process, the laser will work to emit a laser beam, and the arc will start working at the same time until the forming and manufacturing are completed. The present invention utilizes two different heat sources, arc and laser scanning, and introduces two symmetrical lasers to act on the tail of the molten pool to widen the weld and reduce the weld excess height, thereby improving the weld forming quality.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-dimensional forming and manufacturing, and in particular relates to an additive manufacturing method for realizing ultra-wide and ultra-thin welds by using a composite heat source of plasma arc and laser. Background Art

[0002] Modern additive manufacturing (3D printing) technology is based on computer-aided design, material processing, and forming. Using software and numerical control systems, it builds specialized metal and non-metallic materials layer by layer, ultimately creating physical products with superior structural properties. It is hailed as a potential catalyst for the "Third Industrial Revolution." In just a few decades, this technology has achieved rapid development, with promising applications in a wide range of fields, including aerospace, microstructure manufacturing, and biomedical engineering. The technical foundation of additive manufacturing for metal components is welding / joining. Over the past 20 years, additive manufacturing has achieved two major breakthroughs both domestically and internationally: the first is the evolution from early laser rapid prototyping of non-metallic materials such as photosensitive resins to the fabrication of metal structural components; the second is the deep integration of flexible welding and forming technologies using high-energy beam heat sources such as lasers, electron beams, and arcs with computer-aided design / manufacturing information technology, enabling customized, moldless manufacturing of metal structures and establishing a new direction for industrial development.

[0003] The advantages of additive manufacturing lie in its short manufacturing cycles, suitability for individualized individual parts, ability to manufacture large, thin-walled parts, difficult-to-machine, easily thermoformed parts like titanium alloys, and complex structural parts. It offers broad potential for development in fields such as aerospace and mechanical manufacturing, during product development, in the development of computer peripherals, and in innovative education. Currently, additive manufacturing technology complements traditional mass production techniques, but it faces many new challenges and challenges compared to traditional manufacturing technologies. The application of additive manufacturing of metal components in product development still presents challenges such as high costs, low manufacturing efficiency, and unsatisfactory precision. Furthermore, the development of its processes and equipment is insufficient, and it has yet to enter large-scale industrial application.

[0004] Arc additive manufacturing offers advantages such as low cost, high efficiency, a wide range of controllable parameters, excellent mechanical properties, and wide applicability of metal materials. However, there are also challenges that need to be addressed: forming accuracy differs significantly from net-shape parts, residual stresses are high, and the controllability of the molten pool is poor. Among traditional welding technologies, gas metal arc welding offers advantages such as high welding current and high efficiency, but the arc is unstable, and the molten pool is prone to overflow and collapse during the forming process. Gas non-metal arc welding offers stable welding, but the welding current is low and the welding efficiency is low.

[0005] Arc processing in additive manufacturing offers advantages such as high thermal efficiency and droplet deposition rates. However, the high heat input of the arc can easily lead to coarsening of the grain structure within the metal structure. The open, gas-shielded arc environment also makes it easy for porosity defects to form during the forming process. Summary of the Invention

[0006] The purpose of the present invention is to provide an additive method for achieving ultra-wide and ultra-thin welds by using a composite heat source of plasma arc and laser, which can widen the weld, reduce the weld excess height, slightly improve the structural density, increase the heterogeneous nucleation rate at the tail of the molten pool, promote uniform nucleation, and significantly refine the grain growth during the solidification process of the molten pool.

[0007] The present invention uses a plasma arc and laser composite heat source to achieve ultra-wide and ultra-thin welds. The arc heat source provides the primary energy required to melt the metal wire, form droplets, and shape the metal structure. High-frequency pulsed laser energy oscillates the molten pool, widening the molten pool and the weld bead. The method includes the following steps:

[0008] Step 1: Adjust the relative positions of the arc welding gun and the laser output head so that the arc output direction is symmetrically distributed along the plumb line, the angle between the laser output direction and the arc output direction is 10 to 30 degrees, and with the forward direction of the workbench as a reference, the arc heat source action point is in front and the laser output action point is in the back, so that the laser energy acts on the tail area of ​​the arc molten pool;

[0009] Step 2: Adjust the equipment's current and voltage, selecting parameters such as arc power, gas type and flow rate, wire feed method and speed, and welding speed. Plasma arc parameters include voltage (20V ≤ U ≤ 22.5V), which refers to the continuously output AC arc voltage; current (60A ≤ I ≤ 200A), which refers to the continuously output DC or AC arc current; wire feed speed (WFS) = 4.0m / min, with either coaxial or side-axis wire feeding; welding speed (TS) = 4.5mm / s; power (1200W ≤ P ≤ 4500W); and arc diameter (8mm ≤ D ≤ 11mm).

[0010] Step 3: Use titanium alloy as the substrate and use a grinding wheel to grind the area on the substrate where the material needs to be added for a period of time to remove some stains on the surface and scrub with acetone or alcohol to remove the oxide layer; then preheat the substrate so that the overall temperature of the substrate reaches the predetermined temperature evenly. Preheating the substrate can remove hydrogen, eliminate residual stress, and reduce severe airflow convection caused by large temperature differences during addition;

[0011] Step 4: Start the additive manufacturing process. The laser starts to work and emits a laser beam with specific parameters. At the same time, the arc is struck to start the arc and the metal wire is fed to form a molten pool of a certain width. The width of the arc molten pool is 4mm≤B1 / 2≤5mm. The width of the molten pool after the composite laser is 8mm≤B2 / 2≤10mm.

[0012] Step 5: Allow the plasma arc to continue advancing along the predetermined path until a complete weld is formed.

[0013] Step 6: Repeat step 5 until the entire component is formed;

[0014] Step 7: Heat-treat the component after material addition in an argon protective atmosphere.

[0015] Furthermore, in step 1, the filament spacing, that is, the distance H between the welding wire and the laser beam, is adjusted so that the laser heat source contacts the arc molten pool but the laser output head does not collide with the arc welding gun and two weld beads are not formed because the two heat sources are too far apart; the distance between the two is: the molten pool length L≤H / 3≤2L / 3+laser scanning length M / 2, that is, 4.00mm≤H / 3≤6.00mm.

[0016] Furthermore, in step 1, two symmetrical laser beams are distributed on both sides of the rear of the molten pool with the molten pool as the axis of symmetry. The distance S between the two laser beams must satisfy the requirement that the laser heat source can contact the edge of the molten pool. However, in order to more effectively increase the weld width and prevent the two heat sources from being too far apart to form a complete weld and thus forming multiple weld beads, the overlap with the molten pool should be minimized, which affects the forming quality. The distance between the two laser beams is: the molten pool width B<S<B+laser beam d1 / 2+laser beam d2 / 2.

[0017] Furthermore, in step 1, the diameters d1 and d2 of the two laser beams and the molten pool width B should satisfy the following relationship:

[0018] 0.95<d1 / d2<1.05, 3(d1+d2) / 2≤B≤2(d1+d2), B / 3≤d1(or d2)≤B / 2

[0019] Furthermore, in step 1, the laser beam action mode is a synchronous time-sharing scanning mode, the pulsed laser beam acts on the molten pool area in a Z-shaped trajectory, the micro-scanning area is the tail of the arc molten pool, and the area of ​​the synchronous time-sharing scanning area is ≥1 / 3 of the molten pool surface area, and the synchronous time-sharing scanning frequency is proportional to the movement rate of the arc heat source.

[0020] Furthermore, in step 1, the laser pulse frequency is audible audio frequency 100 Hz to 20 kHz or ultrasonic frequency above 20 kHz, the pulse peak power is not less than 2 kW, and the arc current pulse and the laser pulse are asynchronous pulses.

[0021] Furthermore, in step 3, the preheating treatment of the substrate is specifically the following steps:

[0022] Before applying the arc, the substrate is preheated to 200-300°C within 30 minutes and kept at this temperature for 5-10 minutes before adding material;

[0023] During the additive manufacturing process, in order to improve the mechanical properties of the components and reduce the problem of heat accumulation caused by continuous heat input and the resulting coarse columnar crystals, a coolant circulation system is added under the substrate to assist in heat dissipation.

[0024] After the addition is completed, the substrate temperature is adjusted to 100-200°C and maintained for 30-40 minutes before stopping to eliminate residual stress and further improve the performance of the obtained component.

[0025] Furthermore, the collaborative working mode of the arc current pulse and the laser pulse is set: when the arc current is in a non-pulse mode, the laser pulse energy and the arc energy are arbitrarily matched; when the arc current is in a pulse mode, the energy matching of the laser pulse and the arc current pulse includes: when the arc current pulse and the laser pulse are synchronous pulses, within one energy matching cycle, the pulse energy matching is a peak-to-peak matching; when the arc current pulse and the laser pulse are asynchronous pulses, the laser pulse frequency is at least twice the arc current pulse frequency, and within one energy matching cycle, at least one pulse energy matching is a peak-to-peak matching, and the remaining pulse energy matching is a peak-to-base value matching.

[0026] The present invention discloses an additive manufacturing method for achieving ultra-wide and ultra-thin welds using a combined plasma arc and laser heat source. The method employs a combined operation mode in which the arc serves as the primary heat source and the pulsed laser serves as the auxiliary heat source, resulting in wider, thinner welds with improved performance and edge quality. The laser plasma generated by the interaction of the pulsed laser with the material suppresses the instability of the pulsed arc. The laser and arc pulses are used to achieve a full fusion of the two energy sources and improve the material's thermal absorption rate of the heat source energy. The heat provided by the pulsed MIG arc is used to melt the automatically and synchronously fed metal wire and form molten droplets, enabling accumulation and forming. The designed pulsed MIG arc pulse pattern achieves a relatively low average heat input, reducing internal stress and thermal deformation in the formed component and widening the weld bead. However, in this technique, because the pulsed laser is not the primary heat source, its frequency must be adjusted according to the diameter of the welding wire. Generally, the modulation frequency is not very high, so it cannot oscillate the molten pool, resulting in a low density weld bead structure and insignificant grain refinement.

[0027] Compared with the prior art, the present invention has the following significant advantages:

[0028] 1. This invention utilizes a plasma arc heat source to provide the primary energy required to melt metal wire, form droplets, and shape the metal structure. Pulsed laser energy simultaneously scans the areas on both sides of the arc molten pool, causing it to oscillate at acoustic or ultrasonic frequencies. The pool widens along the laser scanning area, thereby widening the weld bead. This also accelerates gas escape from the molten pool, reduces macro- and micro-porosity, and slightly improves structural density.

[0029] 2. The present invention ensures that the arc is used as a heat source and the laser beam plays the role of oscillating the molten pool by limiting the laser beam parameters and combining the coordinated working mode and energy matching method of the arc current pulse and the laser pulse. When the arc current pulse and the laser pulse are synchronous pulses, the pulse energy peak-to-peak matching will cause the laser pulse to stimulate the generation of an auxiliary vibration energy field in the molten pool while the arc current pulse generates the molten pool, and induce the generation of a pulsating shock wave in the molten pool, affecting the molten pool convection and the nucleation of grains at the solid-liquid interface, accelerating the escape of the gas phase in the molten pool and increasing the nucleation rate. When the arc current pulse and the laser pulse are asynchronous pulses, in addition to the auxiliary vibration energy field of the molten pool generated by the pulse energy peak-to-peak matching, the energy peak-to-base value matching also stimulates the generation of an auxiliary vibration energy field in the molten pool, thereby enhancing the above-mentioned effect on the molten pool.

[0030] 3. The metal deposition rate of the present invention is high, and 5-10 kg of wire can be consumed per hour. The metal component forming efficiency is high, and the internal structure of the metal obtained is dense, and the grains are uniform and fine.

[0031] 4. The arc heat source of the present invention has good stability, and the widening of the weld bead is conducive to heat dissipation, which can achieve low heat input manufacturing and only requires about 80% of the conventional energy, with low energy consumption and manufacturing costs.

[0032] 5. The present invention can control the heat input through two left-right symmetrical laser heat sources, making the weld edge smoother and the weld quality higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of an additive system using a plasma arc and laser composite heat source. 1 is the power supply; 2 is the substrate; 3 is the arc beam; 4 is the molten pool; 5 is the laser beam; 6 is the plasma arc additive device; 7 is the time-sharing scanning laser; and 8 is the weld bead.

[0034] Figure 2 Schematic diagram of the molten pool morphology and laser path after additional laser.

[0035] Figure 3 Schematic diagram of the waveforms of arc current pulses and laser pulses. The upper part is the arc current pulse, and the lower part is the laser pulse. DETAILED DESCRIPTION

[0036] The technical method of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0037] Example 1

[0038] To solve the above technical problems, this embodiment provides an additive method using a plasma arc and laser composite heat source, including the following steps:

[0039] Step 1: Adjust the relative positions of the arc welding gun and the laser output head so that the arc output direction is symmetrically distributed along the plumb line, the angle between the laser output direction and the arc output direction is 10°, and with the forward direction of the workbench as a reference, the arc heat source action point is in front and the laser output action point is in the back, so that the laser energy acts on the tail area of ​​the arc molten pool;

[0040] Adjust the filament spacing (H) between the welding wire and the laser beam so that the laser heat source can contact the arc pool without colliding with the laser head. The distance between the two is H = 15.00 mm. Two symmetrical laser beams are positioned on either side of the molten pool, with the distance between them being S = 16.00 mm. The diameters of the two laser beams are d1 = 4.00 mm and d2 = 4.00 mm.

[0041] The second step is to adjust the equipment's current and voltage, selecting parameters such as arc power, gas type and flow rate, wire feed speed, and welding speed. Plasma arc parameters include voltage U = 22V (constant AC arc voltage); current I = 150A (constant DC or AC arc current); 1.6mm thick welding wire, wire feed speed WFS = 4.0m / min, side-by-side wire feeding, and simultaneous double-sided wire feeding; welding speed TS = 4.5mm / s; power P = 3300W; arc diameter D = 11mm.

[0042] In the third step, titanium alloy is selected as the substrate, and the area on the surface of the substrate that needs to be added is polished for 3 minutes with a grinding wheel to remove some stains on the surface and the oxide layer is scrubbed with acetone or alcohol; before applying the arc, the substrate is preheated to 280°C within 40 minutes and kept warm for 10 minutes before adding material; during the addition process, in order to improve the mechanical properties of the component and reduce the heat accumulation caused by continuous heat input and the problem of coarse columnar crystals, a coolant circulation system is added under the substrate to assist in heat dissipation; after the addition is completed, the substrate temperature is adjusted to within 180°C and maintained for 30 minutes before stopping to eliminate residual stress and further improve the performance of the resulting component.

[0043] The fourth step is to start the additive manufacturing program, the laser works, and emits a laser beam with specific parameters. At the same time, the arc is struck to start the arc and the metal wire starts to be fed, and the collaborative working mode of the arc current pulse and the laser pulse is set: when the arc current is in non-pulse mode, the laser pulse energy and the arc energy are arbitrarily matched; when the arc current is in pulse mode, the energy matching of the laser pulse and the arc current pulse includes: when the arc current pulse and the laser pulse are synchronous pulses, within one energy matching cycle, the pulse energy matching is peak-peak matching; when the arc current pulse and the laser pulse are asynchronous pulses, the laser pulse frequency is at least 2 times the arc current pulse frequency, within one energy matching cycle, at least one pulse energy matching is peak-peak matching, and the remaining pulse energy matching is peak-base matching to form a molten pool of a certain width; the width of the arc molten pool is B1 = 10 mm, and the width of the molten pool after laser recombination is B2 = 18 mm.

[0044] The fifth step is to allow the plasma arc to continue to advance along a predetermined route until a complete weld is formed.

[0045] Step 6: Repeat the steps in step 5 until the entire component is formed.

[0046] In the seventh step, the component with the added material is heat treated in an argon protective atmosphere to obtain a component with better performance;

[0047] The components prepared in this example were removed, their surfaces cleaned, and then subjected to mechanical property tests, including tensile testing and hardness testing. The tensile strength and elongation after fracture of the additively manufactured components are shown in Table 1 below.

[0048] Example 2

[0049] To solve the above technical problems, this embodiment provides an additive method using a plasma arc and laser composite heat source, including the following steps:

[0050] Step 1: Adjust the relative positions of the arc welding gun and the laser output head so that the arc output direction is symmetrically distributed along the plumb line, the angle between the laser output direction and the arc output direction is 20°, and with the forward direction of the workbench as a reference, the arc heat source action point is in front and the laser output action point is in the back, so that the laser energy acts on the tail area of ​​the arc molten pool;

[0051] Adjust the filament spacing (H) between the welding wire and the laser beam so that the laser heat source can contact the arc pool without colliding with the laser head. The distance between the two is H = 14.00 mm. Two symmetrical laser beams are positioned on either side of the molten pool, with the distance between them being S = 15.00 mm. The diameters of the two laser beams are d1 = 4.00 mm and d2 = 4.00 mm.

[0052] The second step is to adjust the equipment's current and voltage, selecting parameters such as arc power, gas type and flow rate, wire feed speed, and welding speed. Plasma arc parameters include voltage U = 21V (constant AC arc voltage); current I = 100A (constant DC or AC arc current); 1.2mm thick welding wire, wire feed speed WFS = 4.0m / min, side-by-side wire feeding, and simultaneous double-sided wire feeding; welding speed TS = 4.5mm / s; power P = 2100W; arc diameter D = 10mm.

[0053] In the third step, titanium alloy is selected as the substrate, and the area on the surface of the substrate where additive manufacturing is required is polished for 3 minutes with a grinding wheel to remove some stains on the surface and the oxide layer is removed by scrubbing with acetone or alcohol; before applying the arc, the substrate is preheated to 250°C within 30 minutes and kept warm for 7 minutes before additive manufacturing; during the additive manufacturing process, in order to improve the mechanical properties of the component and reduce the problem of heat accumulation caused by continuous heat input and the generation of coarse columnar crystals, a coolant circulation system is added under the substrate to assist in heat dissipation; after the additive manufacturing is completed, the substrate temperature is adjusted to within 160°C and maintained for 35 minutes before stopping to eliminate residual stress and further improve the performance of the resulting component.

[0054] The fourth step is to start the additive manufacturing program, the laser works, and emits a laser beam with specific parameters. At the same time, the arc is struck to start the arc and the metal wire starts to be fed, and the collaborative working mode of the arc current pulse and the laser pulse is set: when the arc current is in non-pulse mode, the laser pulse energy and the arc energy are arbitrarily matched; when the arc current is in pulse mode, the energy matching of the laser pulse and the arc current pulse includes: when the arc current pulse and the laser pulse are synchronous pulses, within one energy matching cycle, the pulse energy matching is peak-to-peak matching; when the arc current pulse and the laser pulse are asynchronous pulses, the laser pulse frequency is at least 2 times the arc current pulse frequency, and within one energy matching cycle, at least one pulse energy matching is peak-to-peak matching, and the remaining pulse energy matching is peak-to-base value matching to form a molten pool of a certain width; the width of the arc molten pool is B1 = 9 mm, and the width of the molten pool after laser recombination is B2 = 17 mm.

[0055] The fifth step is to allow the plasma arc to continue to advance along a predetermined route until a complete weld is formed.

[0056] Step 6: Repeat the steps in step 5 until the entire component is formed.

[0057] In the seventh step, the component with the added material is heat treated in an argon protective atmosphere to obtain a component with better performance;

[0058] The components prepared in this example were removed, their surfaces cleaned, and then subjected to mechanical property tests, including tensile testing and hardness testing. The tensile strength and elongation after fracture of the additively manufactured components are shown in Table 1 below.

[0059] Example 3

[0060] To solve the above technical problems, this embodiment provides an additive method using a plasma arc and laser composite heat source, including the following steps:

[0061] Step 1: Adjust the relative positions of the arc welding gun and the laser output head so that the arc output direction is symmetrically distributed along the plumb line, the angle between the laser output direction and the arc output direction is 25°, and with the forward direction of the workbench as a reference, the arc heat source action point is in front and the laser output action point is in the back, so that the laser energy acts on the tail area of ​​the arc molten pool;

[0062] Adjust the filament spacing (H) between the welding wire and the laser beam so that the laser heat source can contact the arc pool without colliding with the laser head. The distance between the two is H = 12.00 mm. Two symmetrical laser beams are positioned on either side of the molten pool, with the distance between them being S = 14.00 mm. The diameters of the two laser beams are d1 = 4.00 mm and d2 = 4.00 mm.

[0063] The second step is to adjust the equipment's current and voltage, selecting parameters such as arc power, gas type and flow rate, wire feed speed, and welding speed. Plasma arc parameters include voltage U = 20V (constant AC arc voltage); current I = 70A (constant DC or AC arc current); 1.0mm thick welding wire, wire feed speed WFS = 4.0m / min, side-by-side wire feeding, and simultaneous double-sided wire feeding; welding speed TS = 4.5mm / s; power P = 1400W; arc diameter D = 8mm.

[0064] In the third step, titanium alloy is selected as the substrate, and the area on the surface of the substrate where additive manufacturing is required is polished for 3 minutes with a grinding wheel to remove some stains on the surface and the oxide layer is removed by scrubbing with acetone or alcohol; before applying the arc, the substrate is preheated to 240°C within 30 minutes and kept warm for 5 minutes before additive manufacturing; during the additive manufacturing process, in order to improve the mechanical properties of the component and reduce the problem of heat accumulation caused by continuous heat input and the generation of coarse columnar crystals, a coolant circulation system is added under the substrate to assist in heat dissipation; after the additive manufacturing is completed, the substrate temperature is adjusted to within 140°C and maintained for 40 minutes before stopping to eliminate residual stress and further improve the performance of the resulting component.

[0065] The fourth step is to start the additive manufacturing program, the laser works, and emits a laser beam with specific parameters. At the same time, the arc is struck to start the arc and the metal wire starts to be fed, and the collaborative working mode of the arc current pulse and the laser pulse is set: when the arc current is in non-pulse mode, the laser pulse energy and the arc energy are arbitrarily matched; when the arc current is in pulse mode, the energy matching of the laser pulse and the arc current pulse includes: when the arc current pulse and the laser pulse are synchronous pulses, within one energy matching cycle, the pulse energy matching is peak-peak matching; when the arc current pulse and the laser pulse are asynchronous pulses, the laser pulse frequency is at least 2 times the arc current pulse frequency, and within one energy matching cycle, at least one pulse energy matching is peak-peak matching, and the remaining pulse energy matching is peak-base matching to form a molten pool of a certain width; the width of the arc molten pool is B1 = 8 mm, and the width of the molten pool after laser recombination is B2 = 16 mm.

[0066] The fifth step is to allow the plasma arc to continue to advance along a predetermined route until a complete weld is formed.

[0067] Step 6: Repeat the steps in step 5 until the entire component is formed.

[0068] In the seventh step, the component with the added material is heat treated in an argon protective atmosphere to obtain a component with better performance;

[0069] The components prepared in this example were removed, their surfaces cleaned, and then subjected to mechanical property tests, including tensile testing and hardness testing. The tensile strength and elongation after fracture of the additively manufactured components are shown in Table 1 below.

[0070] Table 1

[0071] Tensile strength / MPa Elongation after break / Hardness / HV Example 1 1388 16.7 345 Example 2 1396 14.3 334 Example 3 1404 12.5 319

Claims

1. A method for achieving ultra-wide and ultra-thin welds using a plasma arc and laser composite heat source, characterized in that: The specific steps include: Step 1: Adjust the relative positions of the arc welding gun and the laser output head, and set the coordinated working mode of the arc current pulse and the laser pulse. Add two symmetrical time-sharing scanning laser heat sources behind the molten pool. The two laser scanning heat sources are contained within the arc molten pool and are located at the left and right edges of the tail of the molten pool. The width of the two laser heat sources should be smaller than the width of the arc molten pool. In step 1, two symmetrical laser beams are distributed on both sides of the rear of the molten pool with the molten pool as the symmetry axis. The distance S between the two laser beams must ensure that the laser heat source can contact the edge of the molten pool. However, in order to more effectively increase the weld width and prevent the two heat sources from being too far apart to form a complete weld bead and thus form multiple weld beads, the overlap with the molten pool should be minimized, which affects the forming quality. The distance between the two laser beams is: the molten pool width B<S<B+laser beam d1 / 2+laser beam d2 / 2; In step 1, the diameters d1 and d2 of the two laser beams and the molten pool width B should satisfy the following relationship: 0.95<d1 / d2<1.05, 3(d1+d2) / 2≤B≤2(d1+d2), B / 3≤d1, d2≤B / 2; Step 2: Adjust the current and voltage of the equipment, select the arc power, gas type and flow rate, wire feeding method and speed, and welding speed parameters; Step 3: Use titanium alloy as the substrate and use a grinding wheel to grind the area on the substrate where the material needs to be added for a period of time to remove some stains on the surface and scrub with acetone or alcohol to remove the oxide layer; then preheat the substrate so that the overall temperature of the substrate reaches the predetermined temperature evenly; Step 4: Start the additive manufacturing process. The laser starts to work and emits a laser beam with specific parameters. At the same time, the arc is struck to start the arc and the metal wire is fed to form a molten pool of a certain width. The width of the arc molten pool is 4mm≤B1 / 2≤5mm. The width of the molten pool after the composite laser is 8mm≤B2 / 2≤10mm. Step 5: Allow the plasma arc to continue advancing along the predetermined path until a complete weld is formed. Step 6: Repeat step 5 until the entire component is formed; Step 7: Heat-treat the component after material addition in an argon protective atmosphere.

2. The additive method for realizing ultra-wide and ultra-thin welds by using a plasma arc and laser composite heat source according to claim 1, characterized in that: In step 1, the relative positions of the arc welding gun and the laser output head are adjusted so that the arc output direction is distributed along the plumb line, the angle between the laser output direction and the arc output direction is 10~30°, and with the forward direction of the workbench as a reference, the arc heat source action point is in front and the laser output action point is in the back, so that the laser energy acts on the tail area of ​​the arc molten pool.

3. The additive method for realizing ultra-wide and ultra-thin welds by using a plasma arc and laser composite heat source according to claim 1, characterized in that: In step 1, adjust the filament spacing, that is, the distance H between the welding wire and the laser beam, so that the laser heat source contacts the arc molten pool but the laser output head does not collide with the arc welding gun and two weld beads are not formed due to the two heat sources being too far apart; the distance between the two is: the molten pool length L≤H / 3≤2L / 3+laser scanning length M / 2, that is, 4.00mm≤H / 3≤6.00mm.

4. The additive method for realizing ultra-wide and ultra-thin welds by using a plasma arc and laser composite heat source according to claim 1, characterized in that: In step 1, the laser beam action mode is a synchronous time-sharing scanning mode, the pulsed laser beam acts on the molten pool area in a Z-shaped trajectory, the micro-scanning area is the tail of the arc molten pool, and the area of ​​the synchronous time-sharing scanning area is ≥1 / 3 of the molten pool surface area, and the synchronous time-sharing scanning frequency is proportional to the movement rate of the arc heat source.

5. The additive method for realizing ultra-wide and ultra-thin welds by using a plasma arc and laser composite heat source according to claim 1, characterized in that: In step 1, the laser pulse frequency is audible audio frequency 100 Hz to 20 kHz or ultrasonic frequency above 20 kHz, the pulse peak power is not less than 2 kW, and the arc current pulse and the laser pulse are asynchronous pulses.

6. The additive method for realizing ultra-wide and ultra-thin welds by using a plasma arc and laser composite heat source according to claim 1, characterized in that: In step 2, in order to achieve the addition of welding wires of different diameters, the parameters of the plasma arc include voltage 20V≤U≤22.5V, where the voltage is the continuously output AC arc voltage; current 60A≤I≤200A, where the current is the continuously output DC arc current or AC arc current; wire feeding speed WFS=4.0m / min, where the wire feeding mode is coaxial wire feeding or side-axis wire feeding; welding speed TS=4.5mm / s; power 1200W≤P≤4500W; and arc diameter 8mm≤D≤11mm.

7. The additive method for realizing ultra-wide and ultra-thin welds by using a plasma arc and laser composite heat source according to claim 1, characterized in that: In step 3, the preheating treatment of the substrate is specifically as follows: Before applying the arc, preheat the substrate to 200-300°C within 30 minutes and keep it at this temperature for 5-10 minutes before adding material; During the additive manufacturing process, in order to improve the mechanical properties of the component and reduce the problem of heat accumulation caused by continuous heat input, which can lead to the formation of coarse columnar crystals, a coolant circulation system is added under the substrate to assist in heat dissipation. After the addition is completed, the substrate temperature is adjusted to the range of 100~200℃ and maintained for 30~40 minutes before stopping to eliminate residual stress and further improve the performance of the obtained component.

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