Controllable pulsed laser assisted hot wire TIG arc deformation hybrid additive manufacturing method

Abstract

The application provides a controllable pulse laser assisted hot wire TIG arc deformation composite additive manufacturing method, comprising the following steps: S1, setting composite additive manufacturing process parameters; S2, planning a composite additive manufacturing motion trajectory; S3, moving a laser arc composite head and a deformation mechanism to the initial positions of the respective motion trajectories; S4, arc melting of a welding wire forms a molten pool, and a pulse laser performs synchronous controllable energy rectangular trajectory scanning on the tail of the molten pool; S5, the temperature of a solidified state deposition layer is monitored in real time, and synchronous deformation adjustment is performed at the optimal forging temperature; and S6, steps S3-S5 are repeated until the part manufacturing is completed. The method provided by the application can obtain higher deposition efficiency, smaller remelting and larger width-height ratio under low arc heat input, promote the heterogeneous nucleation rate of the molten pool, inhibit deposition defects, improve the high-temperature deformation of the deposition layer and the uniformity of grain refinement, and realize high-efficiency, high-precision and high-performance composite additive manufacturing.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a method for composite additive manufacturing of a controllable pulsed laser-assisted hot filament TIG arc deformation. Background Technology

[0002] Arc additive manufacturing, based on advanced CAD and traditional mature welding processes, uses gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), and plasma arc welding as carriers. Compared with laser and electron beam additive manufacturing, it has advantages such as high deposition efficiency, low manufacturing cost, and high component density. However, the high heat input of the arc results in a large molten pool volume and a weakly constrained state, making it less resistant to external disturbances. Furthermore, it is difficult to actively and precisely control the amount of material and energy, leading to lower manufacturing precision.

[0003] It is worth noting that the beneficial effects of introducing lasers on stabilizing arc behavior and improving manufacturing precision have been widely recognized. The main methods include: (1) Stabilizing the molten pool: using an outer ring laser coupled with an inner ring induced laser to constrain the molten arc pool; using an oscillating laser to scan in front of the molten arc pool while welding or pre-cleaning the base material, with the oscillation path being ○, 8, ∞ or continuous broken lines to form specific textures, guiding and constraining the molten arc pool in a directional manner; (2) Expanding the molten pool: using a continuous single-scan laser to act on the tail of a low-heat-input single-MIG arc double-wire molten pool to widen the molten pool. (2) Refine grains: Use a pulsed single-scan laser to assist in merging pulsed current parallel double plasma arc molten pools to form an ultra-wide and ultra-thin molten pool at the tail edge; Use a symmetrical time-division pulsed double-scan laser to act on the pulsed current single plasma arc molten pool tail edge to form an ultra-wide and ultra-thin molten pool; (3) Refine grains: Use a high-frequency pulsed single micro-motion scanning laser to act on the pulsed current single arc molten pool tail for scanning. The micro-motion scanning path is a circular trajectory, an elliptical trajectory, a triangular trajectory, a crescent-shaped trajectory or a straight reciprocating trajectory. The scanning area is ≥1 / 3 of the molten pool surface area.

[0004] However, single static laser pool expansion requires a large power, and the energy at the center of the molten pool is high, which easily leads to deeper remelting; oscillating scanning laser is prone to producing sawtooth ripples at the edge of the molten pool, and the grain refinement effect is limited under high deposition efficiency conditions, making it difficult to achieve high efficiency, high precision, and high performance at the same time.

[0005] Therefore, there is a need to design an electric arc additive manufacturing method to achieve high-efficiency, high-precision, and high-performance composite additive manufacturing. Based on this, this application is proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a controllable pulsed laser-assisted hot filament TIG arc deformation composite additive manufacturing method.

[0007] This invention provides the following technical solution:

[0008] This invention provides a method for controllable pulsed laser-assisted hot-filament TIG arc deformation composite additive manufacturing, comprising the following steps:

[0009] S1. Set the composite additive manufacturing process parameters according to the material properties;

[0010] S2, planning the motion trajectory of composite additive manufacturing;

[0011] S3. The motion mechanism drives the laser-arc composite head and the deformation mechanism to move to their respective initial positions on their motion trajectories. The laser-arc composite head includes a pulsed laser head and a TIG welding torch. The pulsed laser head and the TIG welding torch are mechanically connected and always located on the same vertical plane, and remain parallel to the tangent direction of the travel trajectory.

[0012] S4. After the arc-melted welding wire forms a molten pool, it is deposited along the trajectory planned in step S2. The tail of the molten pool is scanned by a synchronously controllable energy rectangular trajectory to expand, shape and preheat the pool.

[0013] S5. Monitor the temperature of the solidified deposit layer after shaping and preheating in real time, and adjust it synchronously along the trajectory planned in step S2 at the optimal forging temperature through the deformation mechanism.

[0014] S6. After the deformation and toning of the current trajectory is completed, turn off all equipment and repeat steps S3 to S5 until the part manufacturing is completed.

[0015] This invention uses a TIG electric arc as the main heat source to melt the wire and form a molten pool, supplemented by a resistance heating wire, which can effectively improve the wire feeding rate, reduce the heat intake of the substrate, and decrease the melting depth. Combined with a controllable energy pulsed laser for pool expansion, shaping, and preheating, it can accelerate the escape of gas from the molten pool, reduce the temperature gradient of the molten pool and the heat dissipation rate of the solidified deposited layer, increase the aspect ratio of the deposited layer, break up solidified grains, and refine the edge ripples of the deposited layer. Synchronous rectangular trajectory scanning can effectively refine the edge ripples of the deposited layer caused by pool expansion, improve the surface accuracy of the deposited layer, and avoid incomplete fusion defects at the overlap. Finally, synchronous deformation is used as the final tuning force source to plastically deform the optimal forging area of ​​the solidified deposited layer. Based on real-time dynamic recrystallization and post-thermal static recrystallization, the grains can be further refined uniformly, ultimately achieving controllable, high-efficiency, high-precision, and high-performance composite additive manufacturing.

[0016] Further, in step S1, the material is a welding wire with a diameter of 1.0–2.4 mm, and the composite additive manufacturing process parameters include: laser pulse peak power of 500–4000 W, laser pulse frequency of 50–5000 Hz, laser focusing focal length of 180–300 nm, laser scanning amplitude of 0–20 mm, and laser scanning speed of 10–2000 mm / s; TIG arc current is constant current or pulsed, with a TIG arc current of 100–400 A; hot wire current is constant current, constant voltage, constant power, DC pulse, AC, or AC pulse, with a hot wire current of 10–400 A; deformation pressure of 200–30000 N, and forming speed of 2–20 mm / s.

[0017] Furthermore, in step S3, the motion mechanism includes a six-axis robotic arm and a three-axis gantry machine tool. A laser-arc composite head is installed on the six-axis robotic arm, and a deformation mechanism is installed on the three-axis gantry machine tool. Both the laser-arc composite head and the deformation mechanism can rotate in real time to the tangent direction of their respective motion trajectories, and the two do not interfere with each other during their movements.

[0018] Furthermore, the welding wire is resistance heated by short-circuiting with the component substrate. The angle between the welding wire and the horizontal plane is 5-30°. The extension line of the welding wire tip is located between the front edge of the molten pool and the center area of ​​the molten pool along the length direction. The angle between the TIG welding gun and the horizontal plane is 30-60°. The angle between the pulsed laser and the horizontal plane is 90°.

[0019] Furthermore, the welding wire is fed by a guide wire, and the feeding method is either single hot wire feeding or hot wire-cold wire, or hot wire-hot wire multi-wire combination symmetrical feeding.

[0020] Furthermore, in step S4, the length of the molten pool is 3-15 mm and the width of the molten pool is 3-12 mm; the laser rectangular trajectory scanning is controlled by a laser galvanometer, the laser spot is circular, and the width of the rectangular trajectory is the diameter of the laser spot.

[0021] Furthermore, the controllable energy is achieved by using different laser energy inputs for pool expansion, shaping, and preheating. The rectangular trajectory is symmetrical at the tail edge along the length of the molten pool, the trajectory inside the molten pool is used for pool expansion, the trajectory at the edge of the molten pool is used for shaping, and the trajectory on the solidified deposition layer side is used for preheating.

[0022] Furthermore, in step S5, the optimal forging temperature is obtained through the heat treatment diagram of the deposited layer material.

[0023] Furthermore, the deformation characteristics include rolling, ultrasonic impact, or laser impact.

[0024] The present invention has the following beneficial effects:

[0025] 1. This invention uses a TIG electric arc as the main heat source to melt the wire and form a molten pool. At the same time, a resistance heating wire is fed into the arc, which can achieve higher melting efficiency under low heat input, reduce the heat intake of the substrate, and reduce the melting depth.

[0026] 2. This invention uses a controllable energy pulsed laser as a heat source for pool expansion, shaping, and preheating. It can impact and stir the molten pool, accelerate the uniform diffusion of elements and gas escape in the molten pool, and avoid defects such as segregation cracks and pores. At the same time, it reduces the temperature gradient of the molten pool and the heat dissipation rate of the solidified deposited layer, increases the aspect ratio of the deposited layer, breaks up solidified grains and improves the heterogeneous nucleation rate, laying a good foundation for the structure, morphology and temperature uniformity of the deposited layer for subsequent high-temperature deformation. In addition, synchronous rectangular trajectory scanning can effectively refine the edge ripples of the deposited layer caused by pool expansion, improve the surface accuracy of the deposited layer, and avoid fusion defects at the overlap.

[0027] 3. This invention uses synchronous deformation as the final tuning force source to plastically deform the optimal forging region of the solidified deposition layer. Based on real-time dynamic recrystallization and post-thermal static recrystallization, the grains can be further refined uniformly, ultimately achieving controllable high-efficiency, high-precision, and high-performance composite additive manufacturing. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the process of the present invention;

[0030] Figure 2 This is a schematic diagram illustrating the operation of an embodiment of the present invention;

[0031] In the figure: 1-Pulsed laser head; 2-TIG welding torch; 3-Welding wire; 4-Pulsed laser; 5-Deformation mechanism; 6-Molten pool; 7-Hot wire power supply; 8-Deposited layer; 9-Substrate of part. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] See Figure 1The flowchart shown illustrates that this invention provides a method for controllable pulsed laser-assisted hot-filament TIG arc deformation composite additive manufacturing, comprising the following steps:

[0034] S1. Set the composite additive manufacturing process parameters according to the material properties;

[0035] S2, planning the motion trajectory of composite additive manufacturing;

[0036] S3. The motion mechanism drives the laser-arc composite head and the deformation mechanism to move to their respective initial positions on their motion trajectories. The laser-arc composite head includes a pulsed laser head and a TIG welding torch. The pulsed laser head and the TIG welding torch are mechanically connected and always located on the same vertical plane, and remain parallel to the tangent direction of the travel trajectory.

[0037] S4. After the arc-melted welding wire forms a molten pool, it is deposited along the trajectory planned in step S2. The tail of the molten pool is scanned by a synchronously controllable energy rectangular trajectory to expand, shape and preheat the pool.

[0038] S5. Monitor the temperature of the solidified deposit layer after shaping and preheating in real time, and adjust it synchronously along the trajectory planned in step S2 at the optimal forging temperature through the deformation mechanism.

[0039] S6. After the deformation and toning of the current trajectory is completed, turn off all equipment and repeat steps S3 to S5 until the part manufacturing is completed.

[0040] The present invention will be further described in conjunction with specific embodiments:

[0041] Example 1

[0042] This embodiment provides a method for controllable pulsed laser-assisted hot-filament TIG arc deformation composite additive manufacturing. A schematic diagram is shown below. Figure 2 Specifically, it includes the following steps:

[0043] S1. Select a single TC4 titanium alloy welding wire with a diameter of 1.2mm as the raw material. The target part is a straight arm with a length of 200mm, a thickness of 30mm, and a height of 100mm. Set the composite additive manufacturing process parameters.

[0044] Specifically, the process parameters include: peak power of the expansion laser pulse 3000W, peak power of the shaping laser pulse 1500W, peak power of the preheating laser pulse 800W, laser pulse frequency 100Hz, laser pulse width 10ns, laser focusing focal length 250mm, laser rectangular trajectory scanning expansion amplitude 16mm, laser rectangular trajectory scanning shaping width 6mm, laser rectangular trajectory scanning speed 1m / s; TIG arc current 200A, constant current, protective gas is 99.999% high-purity argon, gas flow rate 25L / min; hot filament current 100A, output characteristic is constant current, continuous filament feeding speed 4m / min; deformation pressure 10kN; forming speed 5mm / s.

[0045] S2. Using finite element analysis software, stress simulations were performed on straight arm parts with a length of 200mm, a thickness of 30mm, and a height of 100mm under different manufacturing strategies. The preferred composite additive manufacturing trajectory planning strategy with smaller residual stress was: linear deposition along the length direction, continuous overlapping within the layer, reversed sequence of interlayer passes and interchanged start and end points, and the deposition trajectory was consistent with the subsequent deformation trajectory.

[0046] S3. The motion mechanism drives the laser arc composite head and the deformation mechanism to their respective initial positions on their motion trajectories.

[0047] Specifically, the laser-arc composite head includes a pulsed laser head 1 and a TIG welding torch 2. The pulsed laser head 1 and the TIG welding torch 2 are mechanically connected and always located on the same vertical plane, and remain parallel to the tangent direction of the travel trajectory. The motion mechanism includes a six-axis robotic arm and a three-axis gantry machine tool. The laser-arc composite head is installed on the six-axis robotic arm, and the deformation mechanism 5 is installed on the three-axis gantry machine tool. Both the laser-arc composite head and the deformation mechanism can rotate in real time to the tangent direction of their respective motion trajectories, and the two do not interfere with each other during movement. All mechanisms are placed in a rigid inert atmosphere protection chamber, with the protective gas being 99.999% high-purity argon and the water and oxygen content being less than 100 ppm.

[0048] S4. After the arc-melted welding wire forms a molten pool 6, it is deposited along the trajectory planned in step S2. The tail of the molten pool is scanned by a synchronously controllable energy rectangular trajectory to expand, shape and preheat the pool.

[0049] Specifically, the welding wire 3 is melted by the TIG welding torch 2, and simultaneously, the welding wire 3 is connected to the hot wire power supply 7 to form a short circuit with the component substrate 9 for resistance heating. The welding wire 3 is fed in using a lead-feed method, with the angle between the welding wire and the horizontal plane being 15°. The extension line of the welding wire tip is located at the leading edge of the molten pool along its length. The initial arc molten pool length is 12mm, and the initial arc molten pool width is 11mm. The angle between the TIG welding torch and the horizontal plane is 60°. The angle between the pulsed laser and the horizontal plane is 90°. The laser rectangular trajectory scanning is controlled by a galvanometer, and the laser spot shape is circular with a spot diameter of 6mm. Figure 2As shown, the rectangular trajectory is symmetrical at the tail edge along the length of the molten pool. The trajectory inside the molten pool 6 is used for pool expansion, the trajectory at the edge of the molten pool 6 is used for shaping, and the solidified deposition layer 8 is used for preheating.

[0050] S5. The temperature of the solidified deposit layer after shaping and preheating is monitored in real time by an infrared thermal imager. The deformation mechanism performs synchronous deformation and adjustment at the optimal forging temperature along the trajectory planned in step S2. The optimal forging temperature is obtained from the hot working diagram of TC4 titanium alloy material and is set to 850~950℃. The deformation and adjustment adopts rolling rolling with a roll diameter of 28mm.

[0051] S6. After the deformation and toning of the current trajectory is completed, turn off all equipment and repeat steps S3 to S5 until the part manufacturing is completed.

[0052] Example 2

[0053] This embodiment provides a method for controllable pulsed laser-assisted hot-filament TIG arc deformation composite additive manufacturing. A schematic diagram is shown below. Figure 2 Specifically, it includes the following steps:

[0054] S1. Select 15-5PH stainless steel welding wire with a single diameter of 1.2mm as raw material. The target part is a straight cylindrical part with an outer diameter of 250mm, a wall thickness of 20mm, and a height of 80mm. Set the composite additive manufacturing process parameters.

[0055] Specifically, the process parameters include: peak power of the expansion laser pulse 2500W, peak power of the shaping laser pulse 1200W, peak power of the preheating laser pulse 600W, laser pulse frequency 100Hz, laser pulse width 10ns, laser focusing focal length 250mm, laser rectangular trajectory scanning expansion amplitude 16mm, laser rectangular trajectory scanning shaping width 6mm, laser rectangular trajectory scanning speed 1m / s; TIG arc current 230A, constant current, protective gas is 99.999% high-purity argon, gas flow rate 25L / min; hot filament current 120A, output characteristic is constant current, continuous filament feeding speed 3.6m / min; forming speed 5mm / s.

[0056] S2. Using finite element analysis software, stress simulations were performed on a straight cylindrical part with an outer diameter of 250 mm, a wall thickness of 20 mm, and a height of 80 mm, under different manufacturing strategies. The optimal composite additive manufacturing trajectory planning strategy with the lowest residual stress was: single-pass forming within the layer, with the arc starting position between layers rotating 60° sequentially; both the deposition trajectory and the post-deformation trajectory were executed by a two-axis positioner driving the substrate to rotate, while the positions of the laser composite head and the deformation mechanism remained unchanged during the deposition process.

[0057] S3. The motion mechanism drives the laser arc composite head and the deformation mechanism to their respective initial positions on their motion trajectories.

[0058] Specifically, the laser-arc composite head includes a pulsed laser head 1 and a TIG welding torch 2. The pulsed laser head 1 and the TIG welding torch 2 are mechanically connected and always located on the same vertical plane, and remain parallel to the tangent direction of the travel trajectory. The motion mechanism includes a six-axis robotic arm and a three-axis gantry machine tool. The laser-arc composite head is installed on the six-axis robotic arm, and the deformation mechanism 5 is installed on the three-axis gantry machine tool. Both the laser-arc composite head and the deformation mechanism can rotate in real time to the tangent direction of their respective motion trajectories, and the two do not interfere with each other during movement.

[0059] S4. After the arc-melted welding wire forms a molten pool 6, it is deposited along the trajectory planned in step S2. The tail of the molten pool is scanned by a synchronously controllable energy rectangular trajectory to expand, shape and preheat the pool.

[0060] Specifically, the welding wire 3 is melted by the TIG welding torch 2, and simultaneously, the welding wire 3 is connected to the hot wire power supply 7 to form a short circuit with the component substrate 9 for resistance heating. The welding wire 3 is fed in using a lead-feed method, with the angle between the welding wire and the horizontal plane being 15°. The extension line of the welding wire tip is located at the leading edge of the molten pool along its length. The initial arc molten pool length is 12mm, and the initial arc molten pool width is 11mm. The angle between the TIG welding torch and the horizontal plane is 60°. The angle between the pulsed laser and the horizontal plane is 90°. The laser rectangular trajectory scanning is controlled by a galvanometer, and the laser spot shape is circular with a spot diameter of 6mm. Figure 2 As shown, the rectangular trajectory is symmetrical at the tail edge along the length of the molten pool. The trajectory inside the molten pool 6 is used for pool expansion, the trajectory at the edge of the molten pool 6 is used for shaping, and the solidified deposition layer 8 is used for preheating.

[0061] S5. The temperature of the solidified deposit layer after shaping and preheating is monitored in real time by an infrared thermal imager. The deformation mechanism performs synchronous deformation and tuning along the trajectory planned in step S2 at the optimal forging temperature. The optimal forging temperature is obtained from the hot working diagram of 15-5PH stainless steel material and is set to 950~1050℃. The deformation tuning adopts pulsed laser shock with an average pulse power of 500W, a pulse width of 10ns, and a pulse frequency of 50Hz.

[0062] S6. After the deformation and toning of the current trajectory is completed, turn off all equipment and repeat steps S3 to S5 until the part manufacturing is completed.

[0063] The method proposed in this invention can achieve higher deposition efficiency, smaller remelting and larger aspect ratio under low arc heat input, promote heterogeneous nucleation rate of molten pool, suppress deposition defects, improve high-temperature deformation and grain refinement uniformity of deposition layer, and realize high-efficiency, high-precision and high-performance composite additive manufacturing.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controllable pulsed laser-assisted hot-filament TIG arc deformation composite additive manufacturing, characterized in that, Includes the following steps: S1. Set the composite additive manufacturing process parameters according to the material properties; S2, planning the motion trajectory of composite additive manufacturing; S3. The motion mechanism drives the laser-arc composite head and the deformation mechanism to move to their respective initial positions on their motion trajectories. The laser-arc composite head includes a pulsed laser head and a TIG welding torch. The pulsed laser head and the TIG welding torch are mechanically connected and always located on the same vertical plane, and remain parallel to the tangent direction of the travel trajectory. S4. After the arc-melted welding wire forms a molten pool, it is deposited along the trajectory planned in step S2. The tail of the molten pool is scanned by a synchronously controllable energy rectangular trajectory to expand, shape and preheat the pool. S5. Monitor the temperature of the solidified deposit layer after shaping and preheating in real time, and adjust it synchronously along the trajectory planned in step S2 at the optimal forging temperature through the deformation mechanism. S6. After the deformation and toning of the current trajectory is completed, turn off all equipment and repeat steps S3 to S5 until the part manufacturing is completed. In step S1, the material is a welding wire with a diameter of 1.0~2.4mm, and the composite additive manufacturing process parameters include: laser pulse peak power of 500~4000W, laser pulse frequency of 50~5000Hz, laser focusing focal length of 180~300nm, laser scanning amplitude of 0~20mm, and laser scanning speed of 10~2000mm / s; TIG arc current is constant current or pulsed, and TIG arc current is 100~400A; hot wire current is constant current, constant voltage, constant power, DC pulse, AC or AC pulse, and hot wire current is 10~400A; deformation pressure is 200~30000N, and forming speed is 2~20mm / s. In step S3, the motion mechanism includes a six-axis robotic arm and a three-axis gantry machine tool. A laser-arc composite head is installed on the six-axis robotic arm, and a deformation mechanism is installed on the three-axis gantry machine tool. Both the laser-arc composite head and the deformation mechanism can rotate in real time to the tangent direction of their respective motion trajectories, and the two do not interfere with each other during their movements. The welding wire is resistance heated by short-circuiting with the substrate of the part. The angle between the welding wire and the horizontal plane is 5~30°. The extension line of the welding wire tip is located between the front edge of the molten pool and the center area of ​​the molten pool along the length direction. The angle between the TIG welding gun and the horizontal plane is 30~60°. The angle between the pulsed laser and the horizontal plane is 90°. The welding wire is fed by a leader, and the feeding method is either single hot wire feeding or hot wire-cold wire, or hot wire-hot wire multi-wire combination symmetrical feeding. In step S4, the length of the molten pool is 3~15mm and the width of the molten pool is 3~12mm; the laser rectangular trajectory scanning is controlled by a laser galvanometer, the laser spot is circular, and the width of the rectangular trajectory is the diameter of the laser spot; The controllable energy is achieved by using different laser energy inputs for pool expansion, shaping, and preheating. The rectangular trajectory is symmetrical at the tail edge along the length of the molten pool. The trajectory inside the molten pool is used for pool expansion, the trajectory at the edge of the molten pool is used for shaping, and the trajectory on the solidified deposition layer side is used for preheating.

2. The controllable pulsed laser-assisted hot filament TIG arc deformation composite additive manufacturing method as described in claim 1, characterized in that: In step S5, the optimal forging temperature is obtained from the heat treatment diagram of the deposited layer material.

3. The controllable pulsed laser-assisted hot filament TIG arc deformation composite additive manufacturing method as described in claim 1, characterized in that: The deformation characteristics include rolling, ultrasonic impact, or laser impact.

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