An electric arc additive multi-directional loading thermal force synergistic forming composite device and a control method thereof

Abstract

This invention discloses an electric arc additive manufacturing-multi-directional loading thermo-mechanical synergistic forming composite device and its control method, belonging to the field of metal additive manufacturing technology. The device includes a fixed platform, a protective cover, a turntable, a drive mechanism, a heating and insulation system, a multi-directional loading system, and a control system. The drive mechanism uses a worm gear to drive the turntable to rotate smoothly; the heating and insulation system uses a multi-layer composite insulation cover combined with closed-loop temperature control to achieve precise heating and insulation; the multi-directional loading system includes outer, inner, and top hydraulic presses, which can apply extrusion pressure from multiple directions. The control method achieves dynamic multi-directional loading under precise temperature control through an additive-rotation-extrusion cycle process. This invention organically integrates electric arc additive manufacturing, precise temperature control, and multi-directional loading, effectively refining grains, eliminating defects, improving density and mechanical properties, and is suitable for high-performance manufacturing of large and complex components such as magnesium alloys and aluminum alloys.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing technology, specifically relating to a thermo-mechanical synergistic composite device and its control method that integrates electric arc additive manufacturing, precise temperature control and multi-directional loading forming, and is particularly suitable for the integral forming manufacturing of large and complex magnesium alloy components. Background Technology

[0002] Wire Arc Additive Manufacturing (WAAM) uses an electric arc as a heat source and metal wire as raw material to 3D print metal parts by melting and depositing layers one by one. It has significant advantages such as high forming efficiency, high material utilization, and low equipment cost, and is particularly suitable for the rapid manufacturing and repair of large metal structural components. However, this process has the following bottlenecks: First, there are issues with heat accumulation and thermal stress: the repeated thermal cycling and accumulation during arc additive manufacturing can lead to severe localized overheating or undercooling of components, resulting in significant residual stress and deformation, and even defects such as cracks. Magnesium alloys, in particular, are highly reactive and heat-sensitive materials, making them more susceptible to grain coarsening, reduced fluidity of the molten metal pool, weld beads, and cold shuts due to excessive thermal gradients in additive manufacturing. These problems severely affect the structural integrity and mechanical properties of additively manufactured parts.

[0003] Second, the issue of microstructure density: conventional arc additive parts are prone to metallurgical defects such as porosity and looseness, making it difficult to meet the mechanical properties required for load-bearing components; traditional post-processing methods such as hot extrusion and forging can improve the microstructure, but they require secondary clamping and reheating, which is inefficient and destroys the thermal history.

[0004] Third, the detection and processing methods are limited: In the existing technology, the evaluation of the mechanical properties of arc additive parts is mostly carried out by placing the formed part into a hydraulic press for single-point pressure testing. The testing position is fixed, and if the force surface needs to be changed, the position of the workpiece needs to be repeatedly adjusted, which is inefficient and cannot improve the microstructure simultaneously during the additive process.

[0005] To address the aforementioned issues, the industry has attempted to combine additive manufacturing with plastic processing. However, existing equipment is mostly simple stacking, lacking the organic integration of thermo-mechanical synergy, and cannot achieve multi-directional dynamic loading under precise temperature control, thus restricting the overall manufacturing of high-performance complex components. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of the prior art and provide an electric arc additive manufacturing-multi-directional loading thermo-co-forming composite device and its control method to solve the technical problem in the prior art that it is impossible to simultaneously achieve precise temperature control and multi-directional plastic deformation during additive manufacturing, resulting in poor component microstructure and low processing efficiency.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an electric arc additive manufacturing-multi-directional loading thermo-mechanical synergistic forming composite device, comprising: The base system includes a fixed platform and a protective cover disposed above the fixed platform, wherein a processing chamber is formed inside the protective cover; A rotating load-bearing system includes a turntable rotatably disposed inside a protective cover for bearing and driving the workpiece to rotate; The drive system, located inside the fixed platform and connected to the turntable transmission, is used to drive the turntable to rotate smoothly at a preset angle and speed. A heating and heat preservation system is located above the turntable and at least partially surrounds the workpiece forming area, used for precise heating and heat preservation of the workpiece during additive manufacturing. A multi-directional loading system, located on one side of a fixed platform, includes multiple independently controlled hydraulic actuators for applying compressive force to the workpiece from different directions; The control system is electrically connected to the drive system, heating and insulation system, multi-directional loading system, and electric arc additive manufacturing equipment to achieve coordinated control of heat, force, and motion.

[0008] In a preferred embodiment of the present invention, the drive system includes a motor fixedly mounted on the bottom of the inner wall of the fixed platform. A worm gear is fixedly connected to the output end of the motor, and the worm gear meshes with a worm wheel. A drive rod is fixedly connected inside the worm wheel, and the top of the drive rod passes through the fixed platform and the protective cover before being fixedly connected to the turntable. The bottom of the inner wall of the protective cover is rolledly connected to the bottom of the turntable via multiple ball bearings. This worm gear transmission structure ensures smooth rotation and precise positioning of the turntable, while the ball bearing support converts sliding friction into rolling friction, reducing resistance and improving accuracy.

[0009] In a preferred embodiment of the present invention, the multi-directional loading system includes an extrusion table, an outer hydraulic press fixedly mounted on the extrusion table, an L-shaped plate fixedly mounted on the top of the extrusion table, an inner hydraulic press fixedly mounted on the bottom of the L-shaped plate, and a top hydraulic press disposed on the top of the inner wall of the L-shaped plate. The outer, inner, and top hydraulic presses form a multi-directional extrusion structure, allowing extrusion force to be applied to the workpiece from different angles, achieving simultaneous or sequential extrusion of the workpiece in the X, Y, and Z dimensions. The L-shaped plate provides a mounting position for the inner hydraulic press, concentrating the extrusion action on the target area. Multi-directional extrusion can improve the microstructure of arc additively formed parts and increase material density.

[0010] In a preferred embodiment of the present invention, a sliding groove is provided at the top of the inner wall of the L-shaped plate. A limiting plate is slidably connected within the sliding groove, and a movable plate is slidably connected inside the limiting plate. The bottom of the movable plate is fixedly connected to the top of the top hydraulic press. The sliding groove, limiting groove, and limiting plate cooperate to provide an adjustable mounting structure for the top hydraulic press, allowing adjustment of the extrusion position according to the workpiece size. The limiting plate and movable plate cooperate to restrict the movement trajectory of the top hydraulic press, ensuring stable extrusion direction. The adjustable top hydraulic press can adapt to workpieces of different specifications, expanding the applicability of the lifting device.

[0011] As a preferred embodiment of the present invention, the heating and heat preservation system includes a multi-layer composite heat preservation cover and a heating module; the heat preservation cover has a cover structure with an opening at the lower end, and the edge of the lower opening is sealed to a protective cover or a fixed platform to surround the workpiece forming area; the heating module is installed inside the heat preservation cover and is connected to a DC power supply through a wire.

[0012] In a preferred embodiment of the present invention, the multi-layer composite thermal insulation cover comprises, from the outside in, a high-temperature resistant outer shell, a heat insulation layer, a reflective layer, and a thermal insulation cotton layer. The high-temperature resistant outer shell is made of heat-resistant steel plate with a thickness of 2-6 mm. The heat insulation layer is made of ceramic fiber insulating material with a thickness of 20-80 mm. The reflective layer is made of metal reflective material with a thickness of 0.05-0.2 mm. The thermal insulation cotton layer is made of ceramic fiber insulating cotton with a thickness of 40-60 mm. This multi-layer structure forms a highly efficient thermal barrier, significantly reducing heat loss.

[0013] As a preferred embodiment of the present invention, the heating and heat preservation system further includes a temperature sensor, which is in close contact with or facing the surface of the component, for measuring the temperature of the forming zone in real time and feeding it back to the control system; the control system automatically adjusts the output power of the heating module according to the deviation between the preset temperature and the measured temperature, thereby realizing closed-loop temperature control.

[0014] As a preferred embodiment of the present invention, the device further includes a protective gas delivery system, which includes a gas source, an inlet pipe, and an annular gas distribution pipe. The annular gas distribution pipe is installed at the bottom inside the heat insulation cover, and exhaust holes are evenly distributed on the pipe wall to deliver protective gas to the forming area to prevent the metal material from oxidizing at high temperature.

[0015] As a preferred embodiment of the present invention, the apparatus is used for arc additive manufacturing of large and complex magnesium alloy components.

[0016] Secondly, the present invention provides a method for controlling arc additive manufacturing and multi-directional loading thermo-mechanical synergistic forming based on the above-mentioned device, comprising the following steps: Step S1, workpiece clamping and parameter setting: Fix the substrate or workpiece on the turntable, and set the heating temperature T0, holding time t1, loading pressure P, rotation angle sequence θi and extrusion sequence through the control system. Step S2, Preheating and Atmosphere Protection: Start the heating and heat preservation system to preheat the workpiece, and at the same time start the protective gas delivery system to fill the processing chamber with protective gas until the preset temperature T0 is reached and the oxygen content in the chamber is lower than the set threshold. Step S3, Arc Additive Manufacturing: Start the arc additive manufacturing equipment and stack layers one by one according to the preset path. The control system monitors the temperature of the forming area in real time. When the temperature deviates from the range of T0±ΔT, the power of the heating module is automatically adjusted to maintain the temperature stability. Step S4, Multi-directional loading forming: After each layer or several layers are stacked, the control system controls the drive system to drive the turntable to rotate the workpiece to a preset angle θi, and at the same time controls the multi-directional loading system to apply multi-directional extrusion force to the workpiece according to a preset sequence; the multi-directional extrusion force includes one or more combinations of the lateral pressure applied by the outer hydraulic press, the opposing pressure applied by the inner hydraulic press, and the vertical pressure applied by the top hydraulic press. Step S5, repeat until completion: Repeat steps S3 and S4 until the workpiece is formed; Step S6, Pressure Holding and Cooling: After forming, maintain the multi-directional loading system to apply a predetermined pressure to the workpiece, while controlling the heating and heat preservation system to cool to room temperature at a preset cooling rate, release the pressure, and remove the workpiece.

[0017] As a preferred embodiment of the present invention, in step S4, the timing of applying the multi-directional extrusion force is as follows: first, the outer hydraulic press and the inner hydraulic press are started to apply lateral pre-tightening force, then the top hydraulic press is started to apply vertical pressure, and finally, the pressure in each direction is maintained in synergy during the rotation process to achieve dynamic extrusion.

[0018] In a preferred embodiment of the present invention, in step S3, the temperature T0 is set to a range of 200-300℃, and the ΔT is set to ±10℃; when the temperature is higher than T0+ΔT, the control system reduces the power of the heating module and simultaneously reduces the arc current by 5-10A; when the temperature is lower than T0-ΔT, the control system increases the power of the heating module and simultaneously increases the arc current by 5-10A, thereby achieving coordinated optimization of heat, power, and energy.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention is the first to organically integrate three major functions: electric arc additive manufacturing, precise temperature control, and multi-directional loading, achieving dynamic thermo-mechanical coupling simultaneously during the additive manufacturing process. The intense plastic deformation generated by multi-directional extrusion can effectively break dendrites, refine grains, and eliminate porosity, while precise temperature control avoids thermal stress concentration and crack formation.

[0020] 2. This invention achieves dynamic loading of the workpiece in all directions without interrupting the additive manufacturing process or requiring secondary clamping by linking the rotation of the turntable with multi-directional extrusion. This solves the problems of low efficiency and single force surface in traditional single-point pressure testing.

[0021] 3. This invention adopts a multi-layer composite insulation structure combined with a closed-loop temperature control system, which can accurately control the temperature of the forming zone within ±10℃. It is particularly suitable for additive manufacturing of highly heat-sensitive materials such as magnesium alloys, effectively avoiding oxidation combustion and grain coarsening.

[0022] 4. The adjustable multi-directional loading mechanism of this invention can adapt to workpieces of different specifications and sizes. The worm gear drive and ball bearing support ensure the smoothness of rotation and positioning accuracy. The independent layout of each module facilitates maintenance and upgrades, and can meet the manufacturing needs of large and complex components in aerospace, rail transportation and other fields.

[0023] 5. This invention is not only applicable to magnesium alloys, but can also be extended to additive manufacturing and simultaneous strengthening of various metal materials such as aluminum alloys, titanium alloys, and high-strength steel, and has broad application prospects. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the composite device of the present invention; Figure 2 This is a schematic diagram of the turntable structure in this invention; Figure 3 This is a schematic diagram of the top hydraulic press in this invention; Figure 4 This is a schematic diagram of the movable plate in this invention; Figure 5 This is a schematic diagram of the heating and heat preservation system in this invention; Figure 6 This is a schematic diagram of the multi-layer composite structure of the heating and insulation system in this invention.

[0025] In the picture: 1. Fixed platform; 2. Protective cover; 3. Turntable; 4. Drive system; 41. Motor; 42. Worm gear; 43. Reinforcing plate; 44. Worm wheel; 45. Drive rod; 5. Multi-directional loading system; 51. Extrusion table; 52. Outer hydraulic press; 53. L-shaped plate; 54. Inner hydraulic press; 55. Top hydraulic press; 56. Sliding groove; 57. Limiting groove; 58. Limiting plate; 59. Moving plate; 6. Heating and insulation system; 61. Insulation cover; 611. High-temperature resistant shell; 612. Insulation layer; 613. Reflective layer; 614. Insulation cotton layer; 62. Heating module; 7. Control system; 8. Temperature sensor; 9. Protective gas delivery system. Detailed Implementation

[0026] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example 1

[0027] Reference Figures 1 to 6 This embodiment provides an electric arc additive manufacturing-multi-directional loading thermo-co-forming composite device, including a fixed platform 1, a protective cover 2, a turntable 3, a drive system 4, a multi-directional loading system 5, a heating and heat preservation system 6, a control system 7, a temperature sensor 8, and a protective gas delivery system 9.

[0028] The fixed platform 1 serves as the mounting base for the entire device, and a protective cover 2 is fixedly connected to its top via multiple connecting rods. The protective cover 2 has a double-layer structure, with an inner layer of heat-resistant stainless steel plate and an outer layer of carbon steel shell, filled with heat-insulating material in between, forming a closed processing chamber that effectively isolates external environmental interference.

[0029] The turntable 3 is rotatably disposed inside the protective cover 2, and its upper surface is provided with a T-slot or threaded hole for mounting workpiece fixtures. Multiple ball bearings are provided between the bottom of the turntable 3 and the bottom of the inner wall of the protective cover 2, so that the turntable 3 forms rolling contact with the protective cover 2 when rotating, reducing frictional resistance.

[0030] Reference Figure 2 The drive system 4 is located inside the fixed platform 1 and includes a motor 41, a worm gear 42, a reinforcing plate 43, a worm wheel 44, and a drive rod 45. The motor 41 is fixedly mounted on the bottom inner wall of the fixed platform 1, and its output end is fixedly connected to the worm gear 42. The end of the worm gear 42 furthest from the motor 41 is movably connected to the reinforcing plate 43 via a bearing seat. The reinforcing plate 43 is fixed to the inner wall of the fixed platform 1 to enhance the support rigidity of the worm gear 42. The worm gear 42 meshes with the worm wheel 44, which is fixedly sleeved on the drive rod 45. The bottom of the drive rod 45 is movably connected to the bottom inner wall of the fixed platform 1 via a bearing seat, and the top passes through the fixed platform 1 and the protective cover 2 before being fixedly connected to the center of the turntable 3. When the motor 41 starts, it drives the worm wheel 44 to rotate at a reduced speed via the worm gear 42, which in turn drives the turntable 3 to rotate smoothly via the drive rod 45. The large reduction ratio and self-locking characteristics of the worm gear mechanism ensure that the turntable 3 can be precisely stopped at any angle and will not shift due to external forces.

[0031] Reference Figure 3The multi-directional loading system 5 is located on the right side of the fixed platform 1 and includes an extrusion table 51, an outer hydraulic press 52, an L-shaped plate 53, an inner hydraulic press 54, and a top hydraulic press 55. The extrusion table 51 is fixedly installed on the ground or a work platform, with the outer hydraulic press 52 fixedly installed on its upper surface. The piston rod of the outer hydraulic press 52 is horizontally oriented towards the workpiece to apply lateral pressure. An L-shaped plate 53 is fixedly installed on the top of the extrusion table 51, and an inner hydraulic press 54 is fixedly installed on the bottom of the L-shaped plate 53. The piston rod of the inner hydraulic press 54 is horizontally oriented towards the workpiece and opposite to the outer hydraulic press 52 to apply counter-pressure. A top hydraulic press 55 is located on the top of the inner wall of the L-shaped plate 53 to apply vertical pressure.

[0032] Reference Figure 4 To accommodate workpieces of different sizes, a sliding groove 56 is provided on the top of the inner wall of the L-shaped plate 53, and limiting grooves 57 are provided on both sides of the inner wall of the sliding groove 56. A limiting plate 58 is slidably connected within the limiting groove 57, and a movable plate 59 is slidably connected inside the limiting plate 58. The bottom of the movable plate 59 is fixedly connected to the top of the top hydraulic press 55. By moving the limiting plate 58 along the sliding groove 56, the horizontal position of the top hydraulic press 55 can be adjusted; by moving the movable plate 59 along the limiting plate 58, the extension length of the top hydraulic press 55 can be finely adjusted to ensure that the pressure head is accurately aligned with the workpiece.

[0033] Reference Figure 5 and Figure 6 The heating and insulation system 6 includes a multi-layer composite insulation cover 61 and a heating module 62. The insulation cover 61 has a cover structure with an opening at the bottom, and a connecting flange is provided at the edge of the lower opening. It is sealed to the top of the protective cover 2 by fasteners, so that the turntable 3 and the workpiece are accommodated in the internal cavity of the insulation cover 61. The insulation cover 61 has a height of 1800-2200mm, an internal cavity height of 500-1500mm, and a 300-700mm welding torch operating space is reserved at the top.

[0034] In this embodiment, the heat insulation cover 61 comprises, from the outside to the inside, a high-temperature resistant outer shell, a heat insulation layer, a reflective layer, and a heat insulation cotton layer connected sequentially by hinges, with a thickness of 50-200 mm. The high-temperature resistant outer shell 611 is made of heat-resistant steel plate, such as ASTM A387 Grade 22, 253MA (EN 10095) or 1.4841 high-temperature alloy steel 310S stainless steel plate (ASTM A240 UNS S31008). In this embodiment, ASTM A387 Grade 22 is selected, with a thickness of 2-6 mm. In this embodiment, 3 mm is preferred. The insulation layer 612 uses insulating materials such as ceramic fibers, such as one or more combinations of aluminosilicate ceramic fibers, high-purity alumina ceramic fibers, mullite ceramic fibers, polycrystalline alumina fibers, or zirconium oxide reinforced ceramic fibers; in this embodiment, an aluminosilicate ceramic fiber blanket is selected; the thickness is 20-80 mm, and in this embodiment, it is preferably 65 mm. The reflective layer 613 is made of a metallic reflective material, such as polished aluminum plate, aluminum foil, stainless steel mirror plate or 310S stainless steel plate, etc. In this embodiment, aluminum foil is selected; the thickness is 0.05-0.2 mm, and in this embodiment, it is preferably 0.1 mm; the surface of the reflective layer may be further provided with an aluminum oxide coating or a zirconium oxide coating to improve the infrared radiation reflection efficiency and high temperature oxidation resistance. The insulation layer 614 is made of ceramic fiber insulation cotton, in the form of two layers, with the inner layer being high-purity alumina cotton and the outer layer being aluminum silicate cotton, with a thickness of 40-60mm, preferably 50mm in this embodiment.

[0035] In this embodiment, the thermal insulation cover 61 adopts a multi-layer composite structure, comprising, from the outside in, a high-temperature resistant outer shell 611, a reflective layer 613, a heat insulation layer 612, and a heat insulation cotton layer 614 to form a highly efficient thermal barrier. To facilitate manufacturing, transportation, and adaptation to components of different heights, the thermal insulation cover 61 is divided into multiple detachably connected sections along its height, with each section fixedly connected by flanges and high-temperature resistant seals. The top and bottom plates of each section (i.e., the end plates at the section connections) employ a two-layer structure: an outer layer of steel heat-resistant plate and an inner layer of insulating material plate. The top section has a through-hole in its top plate for inserting a thermocouple sensor to monitor the temperature of the top area of ​​the component.

[0036] In this embodiment, the heating module 62 is an electric heating wire or an electric heating plate, installed inside the insulation cover 61, located between the inner surface of the insulation cotton layer and the workbench. An air gap of 10-30 mm (preferably 20 mm in this embodiment) is maintained between the heating module 62 and the insulation cotton layer to prevent heat from being directly conducted to the insulation layer, causing overheating and aging, while the air layer forms a thermal buffer.

[0037] In this embodiment, the DC power supply connected to the heating module 62 adopts a low-voltage, high-current heating scheme. The DC power supply output voltage is preferably 24-60 V, and the output current is preferably 300-1200 A.

[0038] The insulation hood 61 has an operating window and an observation window on its side wall. The operating window is an openable and closable metal door structure for the arc welding torch to enter. The window edge is equipped with a high-temperature resistant sealing strip and a flexible fiber brush to maintain a basic seal when the welding torch passes through. The observation window is fitted with high-temperature resistant quartz glass for the operator to observe or for the vision system to acquire images of the molten pool. The top of the insulation hood 61 has a micro-positive pressure exhaust port with a built-in adjustable pressure valve to maintain a micro-positive pressure of 20-30 Pa inside the hood.

[0039] To reduce heat radiation loss, a high-reflectivity layer is provided on the inner wall of the insulation cover 61. In this embodiment, the reflective layer uses POREXVirtek® PTFE high-reflectivity sheet (model PMR15) with a thickness of 0.5-2.0 mm, preferably 1.5 mm, and a reflectivity ≥96%. Alternatively, a ceramic reflective coating with a dry film thickness of 0.15-0.3 mm can be used. The reflective sheet is attached to the inner wall of the insulation cover 61 using a high-temperature resistant inorganic adhesive, covering the entire inner surface area except for the heating module 62. Multiple sheets are joined by overlapping, with an overlap width of 15 mm, and sealed with high-temperature resistant tape. At the installation location of the temperature sensor 8, a corresponding opening is made in the reflective layer, and the edges of the opening are sealed with high-temperature resistant adhesive.

[0040] The temperature sensor 8 is a K-type thermocouple, embedded inside the insulation cover 61, with the probe in close contact with the workpiece surface, used for real-time measurement of the forming zone temperature. The temperature sensor 8 is covered with an insulating protective sleeve to prevent arc interference.

[0041] The protective gas delivery system 9 includes an argon gas source, an inlet pipe, and an annular gas distribution pipe. The annular gas distribution pipe is made of 310S stainless steel and is installed at the bottom inner side of the insulation cover 61, arranged circumferentially. Exhaust holes with a diameter of 2mm are evenly distributed on the pipe wall, facing the workpiece. A guide plate is provided between the annular gas distribution pipe and the inner wall of the insulation cover 61, allowing the protective gas to flow evenly upwards along the inner wall of the insulation cover, forming a stable protective atmosphere around the workpiece.

[0042] The control system 7 employs an industrial-grade PLC controller, which is electrically connected to the solenoid valves of the motor 41, the outer hydraulic press 52, the inner hydraulic press 54, and the top hydraulic press 55, the DC power supply of the heating module 62, the temperature sensor 8, the arc additive manufacturing equipment, and the valves of the protective gas delivery system 9. The control system 7 incorporates a PID control algorithm, automatically adjusting the output power of the heating module 62 based on the signal feedback from the temperature sensor 8; simultaneously, according to preset process parameters, it coordinates the rotation angle of the turntable 3 with the extrusion sequence of the multi-directional loading system 5, achieving coordinated control of heat, force, and motion. Example 2

[0043] This embodiment provides a control method for arc additive manufacturing-multidirectional loading thermo-mechanical co-forming based on the device described in Embodiment 1, using a large thin-walled component of AZ31 magnesium alloy as an example.

[0044] Step S1, workpiece clamping and parameter setting: Fix the AZ31 magnesium alloy substrate onto the turntable 3 using a fixture, and set the following process parameters through the human-machine interface of the control system 7: Heating temperature T0: 250℃; Temperature control tolerance ΔT: ±10℃; Preheating time t1: 30 min; Multi-directional loading pressure P: 20kN for the outer hydraulic press, 20kN for the inner hydraulic press, and 15kN for the top hydraulic press; Rotation angle sequence: after each layer is stacked, rotate 90°, in sequence: 0°, 90°, 180°, 270°; Extrusion sequence: First, start the outer and inner hydraulic presses to apply lateral preload and hold for 5 seconds, then start the top hydraulic press to apply vertical pressure and hold for 10 seconds, and then maintain the coordinated action of pressure in all directions during rotation.

[0045] Step S2, Preheating and Atmosphere Protection: Start the protective gas delivery system 9 to fill the insulation cover 61 with high-purity argon gas at a flow rate of 20L / min until the oxygen content in the cavity is below 50ppm. At the same time, start the heating module 62 to preheat the substrate. The control system 7 adjusts the heating power according to the feedback from the temperature sensor 8, so that the substrate temperature rises to 250℃ at a rate of 5℃ / min and is maintained for 30min.

[0046] Step S3, Arc Additive Manufacturing: Start the arc additive manufacturing equipment, using the CMT cold metal transfer process, with a welding current of 120A, voltage of 15V, and wire feed speed of 4m / min, and deposit layers according to the preset path. During the deposition process, temperature sensor 8 monitors the temperature near the molten pool in real time and feeds it back to control system 7. When the measured temperature is higher than 260℃, control system 7 reduces the power of heating module 62 and simultaneously reduces the welding current to 110A; when the measured temperature is lower than 240℃, control system 7 increases the power of heating module 62 and simultaneously increases the welding current to 130A, ensuring that the temperature of the forming zone is always maintained within the range of 250±10℃.

[0047] Step S4, Multi-directional Loading Forming: After each layer is deposited, the control system 7 pauses the arc additive manufacturing equipment and starts the control motor 41, which drives the turntable 3 to rotate the workpiece to a preset angle (90° after the first layer) via the worm gear 42 and worm wheel 44. After the turntable 3 is in position, the control system 7 controls the multi-directional loading system 5 to operate according to a preset sequence: the outer hydraulic press 52 and the inner hydraulic press 54 extend first, applying 20kN of lateral pressure and holding for 5s; then the top hydraulic press 55 extends, applying 15kN of vertical pressure and holding for 10s; during the pressure holding process, the control system 7 controls the motor 41 to drive the turntable 3 to reciprocate ±5° at a low speed (0.5rpm), causing the workpiece to undergo uniform plastic deformation under dynamic load. After extrusion is completed, each hydraulic press resets, and the control system 7 resumes the arc additive manufacturing equipment to deposit the next layer.

[0048] Step S5, repeat until completion: repeat steps S3 and S4 until the components are stacked to the designed height (a total of 100 layers).

[0049] Step S6, Pressure Holding and Cooling: After the final layer is stacked and extruded, the multi-directional loading system 5 maintains pressure on the workpiece (outer hydraulic press 10kN, inner hydraulic press 10kN, top hydraulic press 5kN), while the control system 7 controls the heating module 62 to gradually reduce its power at a preset cooling rate (3℃ / min), allowing the workpiece temperature to slowly drop to room temperature. During the cooling process, the protective gas delivery system 9 continuously introduces argon gas to prevent workpiece oxidation. Once the workpiece temperature is below 50℃, the pressure is released, the protective cover 2 and the insulation cover 61 are opened, and the formed component is removed.

[0050] Testing revealed that the AZ31 magnesium alloy components formed using the method described in this embodiment have a dense internal structure, free from defects such as pores and cracks. The average grain size has been refined from 50 μm in conventional processes to 15 μm, with a tensile strength of 280 MPa and an elongation of 12%.

[0051] The device of this invention features a compact structure and precise control, and can be directly integrated into existing arc additive manufacturing systems without significant modifications. By changing the fixtures and adjusting the process parameters, it can be adapted to the manufacturing of components of different shapes, sizes, and materials, making it particularly suitable for high-end manufacturing fields such as aerospace structural components, rail transit components, and large molds, with broad industrial application prospects.

[0052] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. An electric arc additive manufacturing-multi-directional loading thermo-mechanical synergistic forming composite device, characterized in that, include: The base system includes a fixed platform (1) and a protective cover (2) disposed above the fixed platform, wherein the protective cover (2) forms a closed processing chamber inside; The rotating bearing system includes a turntable (3) rotatably disposed inside the protective cover (2) for bearing and driving the workpiece to rotate; The drive system (4) is located inside the fixed platform (1) and is connected to the turntable (3) for driving the turntable (3) to rotate smoothly at a preset angle and speed. A heating and heat preservation system (6) is set above the turntable (3) and at least partially surrounds the workpiece forming area, for precisely heating and heat preservation of the workpiece during the additive manufacturing process; A multi-directional loading system (5) is set on one side of the fixed table (1) and includes multiple independently controlled hydraulic actuators for applying extrusion force to the workpiece from different directions; The control system (7) is electrically connected to the drive system (4), the heating and heat preservation system (6), the multi-directional loading system (5), and the electric arc additive manufacturing equipment, and is used to realize the coordinated control of heat, force, and motion.

2. The apparatus according to claim 1, characterized in that, The drive system (4) includes a motor (41) fixedly installed on the bottom of the inner wall of the fixed platform (1). The output end of the motor (41) is fixedly connected to a worm gear (42). The worm gear (42) meshes with a worm wheel (44). A drive rod (45) is fixedly connected inside the worm wheel (44). The top of the drive rod (45) passes through the fixed platform (1) and the protective cover (2) and is fixedly connected to the turntable (3). The bottom of the inner wall of the protective cover (2) is rolledly connected to the bottom of the turntable (3) through multiple balls.

3. The apparatus according to claim 1, characterized in that, The multi-directional loading system (5) includes an extrusion table (51), an outer hydraulic press (52) is fixedly installed on the extrusion table (51), an L-shaped plate (53) is fixedly installed on the top of the extrusion table (51), an inner hydraulic press (54) is fixedly installed on the bottom of the L-shaped plate (53), and a top hydraulic press (55) is provided on the top of the inner wall of the L-shaped plate (53).

4. The apparatus according to claim 3, characterized in that, The top of the inner wall of the L-shaped plate (53) is provided with a sliding groove (56), a limiting plate (58) is slidably connected in the sliding groove (56), a moving plate (59) is slidably connected inside the limiting plate (58), and the bottom of the moving plate (59) is fixedly connected to the top of the top hydraulic press (55).

5. The apparatus according to claim 1, characterized in that, The heating and insulation system (6) includes a multi-layer composite insulation cover (61) and a heating module (62); the insulation cover (61) has a cover structure with an opening at the lower end, and the edge of its lower opening is sealed to the protective cover (2) or the fixed platform (1); the heating module (62) is installed inside the insulation cover (61) and is connected to a DC power supply through a wire.

6. The apparatus according to claim 5, characterized in that, The multi-layer composite thermal insulation cover (61) comprises, from the outside to the inside, a high-temperature resistant outer shell (611), a heat insulation layer (612), a reflective layer (613), and a thermal insulation cotton layer (614); the high-temperature resistant outer shell (611) is made of heat-resistant steel plate with a thickness of 2-6mm; the heat insulation layer (612) is made of ceramic fiber insulating material with a thickness of 20-80mm; the reflective layer (613) is made of metal reflective material with a thickness of 0.05-0.2mm; and the thermal insulation cotton layer (614) is made of ceramic fiber thermal insulation cotton with a thickness of 40-60mm.

7. The apparatus according to claim 1, characterized in that, The heating and heat preservation system (6) also includes a temperature sensor (8), which is in close contact with or facing the surface of the component and is used to measure the temperature of the forming area in real time and feed it back to the control system (7); the control system (7) automatically adjusts the output power of the heating module (62) according to the deviation between the preset temperature and the measured temperature.

8. The apparatus according to claim 1, characterized in that, It also includes a protective gas delivery system (9), which includes a gas source, an air inlet pipe and an annular gas distribution pipe; the annular gas distribution pipe is installed at the bottom inside the heat insulation cover (61), and exhaust holes are evenly distributed on the pipe wall for delivering protective gas to the forming area.

9. A method for controlling arc additive manufacturing and multi-directional loading thermo-mechanical synergistic forming based on the composite device according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1, workpiece clamping and parameter setting: Fix the workpiece on the turntable (3), and set the heating temperature T0, holding time, loading pressure and rotation angle sequence through the control system (7); Step S2, Preheating and Atmosphere Protection: Start the heating and heat preservation system (6) to preheat the workpiece, and at the same time start the protective gas delivery system (9) to fill the processing chamber with protective gas; Step S3, Arc Additive Manufacturing: Start the arc additive manufacturing equipment to build up layers one by one. The control system (7) monitors the temperature of the forming zone in real time and automatically adjusts the heating power to maintain temperature stability. Step S4, Multi-directional loading forming: After each layer or several layers are stacked, the control system (7) controls the drive system (4) to drive the turntable (3) to rotate the workpiece to a preset angle, and at the same time controls the multi-directional loading system (5) to apply multi-directional extrusion force to the workpiece according to the preset sequence; Step S5, repeat until completion: Repeat steps S3 and S4 until the workpiece is formed.

10. The control method according to claim 9, characterized in that, In step S4, the timing of applying the multi-directional extrusion force is as follows: first, start the outer hydraulic press (52) and the inner hydraulic press (54) to apply lateral pre-tightening force, then start the top hydraulic press (55) to apply vertical pressure, and finally maintain the synergistic effect of pressure in all directions during rotation to achieve dynamic extrusion.

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