A magnetic pulse strengthening device and process for improving the performance of additively manufactured workpieces

Abstract

The present invention discloses a magnetic pulse strengthening device and process for improving the performance of additive manufacturing workpieces. The magnetic pulse strengthening device includes a base, an additive manufacturing table, and a first vertical positioning mechanism. A lifting and positioning plate is connected to the first vertical positioning mechanism. A horizontal longitudinal positioning mechanism and a second vertical positioning mechanism are respectively and fixedly arranged on the top surface of the lifting and positioning plate. A horizontal transverse positioning mechanism is arranged on the horizontal longitudinal positioning mechanism, and an arc wire additive manufacturing torch assembly is arranged on the horizontal transverse positioning mechanism. A magnetic pulse strengthening assembly is connected to the second vertical positioning mechanism. After each layer of additive deposition forming is completed by the arc wire additive manufacturing torch assembly, the magnetic pulse strengthening assembly impacts and strengthens the top surface of the workpiece through magnetic field force. The present invention innovatively applies electromagnetic forming technology to the post-treatment of the WAAM process, realizes magnetic pulse strengthening plastic deformation on the surface of the workpiece, has a relatively high depth of the affected layer, and improves the mechanical properties and uniformity of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of metal plastic processing and forming, and specifically to a magnetic pulse strengthening device and process for improving the performance of additive manufacturing workpieces. Background Art

[0002] Wire Arc Additive Manufacturing (WAAM) is an additive manufacturing method that uses an arc welding torch to melt metal and then deposit it layer by layer to finally form a blank of the target workpiece, and then achieves the dimensional accuracy and surface quality of the design target through subsequent machining. Its characteristics include high deposition efficiency, low equipment cost, high material utilization rate, and being relatively friendly to the environment. Although the mechanical properties of components produced by WAAM can be comparable to those of traditional machining counterparts in many cases, there are still some processing defects that must be addressed in critical applications. During the application of WAAM-produced workpieces, pores, high residual tensile stress, and cracks must be avoided, which will lead to a significant decline in the performance of the formed workpiece. The existence of these defects greatly restricts the further development and application of WAAM.

[0003] In addition to methods such as adjusting process parameters and subsequent heat treatment processes to improve the microstructure of the formed parts and enhance the comprehensive mechanical properties, some scholars have also introduced traditional plastic forming processes into arc additive manufacturing, forming arc additive plastic forming composite manufacturing technologies such as ultrasonic laser shock composite technology, high-frequency micro forging composite technology, and rolling composite technology. These composite technologies have a certain effect in regulating residual stress, refining grains, and improving performance, but there are also various problems such as damaging the surface quality, low influence layer depth, and high heat input. Therefore, there is an urgent need to develop new technologies with good surface integrity, high influence layer depth, and less heat input to improve the residual stress of workpieces after additive manufacturing. Summary of the Invention

[0004] In view of the above-mentioned defects and deficiencies, the present invention provides a magnetic pulse strengthening device and process for improving the performance of additive manufacturing workpieces. Based on the RLC discharge circuit, it is charged during the additive manufacturing process and then discharged. The current passes through the working coil to generate a strong magnetic field, and the special-shaped magnetic collector can control the distribution of the magnetic field, generating induced current and magnetic field in the metal workpiece, enabling the workpiece to be subjected to multi-directional magnetic field forces. Under the action of the magnetic field forces, plastic deformation occurs inside the workpiece, improving the residual tensile stress generated during the additive manufacturing process. At the same time, it can prevent the shape of the workpiece from changing greatly and reduce the subsequent machining allowance. The magnetic pulse strengthening process is non-contact, has little impact on the workpiece surface, and can improve surface integrity; the strain rate is large, and the influence layer depth is relatively deep; the action time is short, and it is not easy to cause remelting of the workpiece, which can effectively improve the structure after additive manufacturing, eliminate internal defects, and has significant advantages.

[0005] To solve the above technical problems, a technical solution adopted by the present invention is as follows:

[0006] A magnetic pulse strengthening device for improving the performance of additive manufacturing workpieces, comprising a base, an additive manufacturing table fixedly arranged on the top surface of the base, and a first vertical positioning mechanism. The positioning output end of the first vertical positioning mechanism is fixedly connected with a lifting positioning plate sleeved outside the additive manufacturing table. The top surface of the lifting positioning plate is respectively fixedly provided with a horizontal longitudinal positioning mechanism and a second vertical positioning mechanism. The positioning output end of the horizontal longitudinal positioning mechanism is fixedly connected with a horizontal transverse positioning mechanism. The positioning output end of the horizontal transverse positioning mechanism is fixedly connected with an arc wire additive welding torch assembly located above the top surface of the additive manufacturing table. The positioning output end of the second vertical positioning mechanism is fixedly connected with a lifting frame plate, and a magnetic pulse strengthening assembly is arranged at the bottom of the lifting frame plate and directly above the top surface of the additive manufacturing table.

[0007] The horizontal longitudinal positioning mechanism and the horizontal transverse positioning mechanism drive the arc wire additive welding torch assembly to perform layer-by-layer upward additive deposition on the additive manufacturing table to form a workpiece. After each layer of additive deposition is completed, the second vertical positioning mechanism drives the magnetic pulse strengthening assembly to be positioned outside the top of the already additively manufactured workpiece, and the magnetic pulse strengthening assembly impacts and strengthens the top surface of the workpiece through magnetic field force.

[0008] Further, the magnetic pulse strengthening assembly includes a magnetic collector with an inverted cone-shaped hollow structure, and a magnetic pulse strengthening coil coaxially arranged on the top surface of the magnetic collector. The bottom surface of the magnetic collector is provided with a strengthening groove matching the top contour of the cross-sectional shape of the workpiece. The magnetic pulse strengthening coil is in a spiral wire structure, and its two ends are respectively connected to two output electrodes of the magnetic pulse strengthening device.

[0009] Further, the system circuit of the magnetic pulse strengthening device includes a power supply, a capacitor, a capacitor switch, an inductor, and a resistor. One end electrode of the power supply is connected to one end of the magnetic pulse strengthening coil, and the other end electrode of the power supply is connected to the other end of the magnetic pulse strengthening coil in series with the inductor and the resistor in sequence. The capacitor and the capacitor switch are connected in series and then connected in parallel with the two electrode ends of the power supply.

[0010] Further, the maximum discharge energy of the magnetic pulse strengthening device is 100 - 150 kJ, the capacitance of the capacitor (1032) is 160 - 320 μF, and the discharge voltage is 5 - 20 kV.

[0011] Further, the bottom of the lifting frame plate is fixedly connected with a mounting frame plate, the bottom of the mounting frame plate is fixedly connected with a clamping cylinder, the bottom of the clamping cylinder is detachably connected with a clamping pressure plate, the top surface edge of the magnetic collector is clamped between the clamping pressure plate and the clamping cylinder, and the magnetic pulse strengthening coil is located inside the clamping cylinder.

[0012] There is also provided a magnetic pulse strengthening process for improving the performance of an additive manufacturing workpiece, which is applied to the magnetic pulse strengthening device for improving the performance of an additive manufacturing workpiece as described above, and includes the following steps:

[0013] S1. System initialization and device reset: The second vertical positioning mechanism drives the magnetic pulse strengthening component to rise and reset directly above the additive manufacturing area of the additive manufacturing platform, and the horizontal longitudinal positioning mechanism and the horizontal transverse positioning mechanism drive the arc wire additive manufacturing torch component to horizontally move and reset to the upper side of the additive manufacturing area of the additive manufacturing platform;

[0014] S2. Single-layer arc wire additive manufacturing: The horizontal longitudinal positioning mechanism and the horizontal transverse positioning mechanism drive the arc wire additive manufacturing torch component to move to the additive manufacturing area of the additive manufacturing platform, and drive the arc wire additive manufacturing torch component to move along a preset forming path. During the movement, the arc wire additive manufacturing torch component extrudes molten metal, and the molten metal is deposited and formed. Then, the horizontal longitudinal positioning mechanism and the horizontal transverse positioning mechanism drive the arc wire additive manufacturing torch component to move and reset;

[0015] S3. Magnetic pulse surface strengthening: The second vertical positioning mechanism drives the magnetic pulse strengthening component to move down to the outer side of the top of the already additively manufactured workpiece. The magnetic pulse strengthening component impacts and strengthens the top surface of the workpiece through magnetic field force. After reaching the preset impact strengthening time, the second vertical positioning mechanism drives the magnetic pulse strengthening component to rise and reset;

[0016] S4. Additive height feeding: The first vertical positioning mechanism drives the arc wire additive manufacturing torch component to move up by a single-layer additive manufacturing height;

[0017] S5. Cycle of additive manufacturing and strengthening process: Repeat the above steps S2 to S4 to complete the process of layer-by-layer upward additive deposition and forming of the workpiece on the additive manufacturing platform, and after each layer of additive deposition and forming, complete the impact strengthening of the top surface of the workpiece;

[0018] S6. Take out the sample: The device stops working, and the workpiece to be additively manufactured is removed from the additive manufacturing platform after cooling to room temperature.

[0019] Further, in step S3, the distance between the side surface of the strengthening groove on the bottom surface of the magnetic collector and the outer surface of the top of the already additively manufactured workpiece is 0.5 - 2 mm, and the preset impact strengthening time is 0.001 - 1 ms.

[0020] Further, after step S6, the relationship between the magnetic pulse strengthening parameters and the grain size, metallurgical defects, and residual stress is determined through metallographic observation and residual stress detection.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The present invention provides a magnetic pulse strengthening component. By means of the electromagnetic field released by the magnetic pulse strengthening coil, a magnetic force is generated to impact and strengthen the top surface of the additive manufacturing workpiece. In electromagnetic forming, the strain rate is very high (strain rate: 10 3 -10 4 s -1 ), and the high strain rate hardening effect of high-speed deformation can be utilized to improve the effect of magnetic pulse strengthening. Thus, a residual stress field and a certain degree of surface work hardening are introduced to the workpiece surface, improving the fatigue strength of the workpiece;

[0023] 2. The magnetic pulse surface impact strengthening process adopted by the present invention belongs to non-contact impact strengthening. During the strengthening process, the surface integrity of the workpiece is good, the surface quality is high, and the subsequent machining amount is reduced. At the same time, the magnetic pulse strengthening process has a short action time, only 0.001 - 1 ms, which can complete the surface strengthening of the additive manufacturing workpiece in an extremely short time, with high strengthening efficiency and not easily causing remelting of the workpiece. Under the condition of not damaging the basic shape of the additive manufacturing workpiece, the regulation of the workpiece structure and performance is realized;

[0024] 3. The present invention regulates the magnetic field distribution during the magnetic pulse strengthening process by adopting a magnetic collector with a special-shaped structure, so that the top surface of the workpiece is subjected to triaxial compressive stress during the magnetic pulse surface impact strengthening process, significantly improving the distribution of residual stress inside the workpiece, effectively refining grains, effectively repairing defects such as pores and cracks inside the workpiece after additive manufacturing, regulating its residual stress, and enhancing the comprehensive performance of the workpiece;

[0025] 4. The present invention uses an RLC circuit to charge the capacitor during the additive manufacturing process, saving the charging time and improving the working efficiency;

[0026] 5. The present invention can design the special-shaped magnetic collector into various shapes to meet the application requirements of the magnetic pulse surface impact strengthening process for additive manufacturing workpieces with different shapes, with good adaptability. Description of the Drawings

[0027] Figure 1 It is one of the three-dimensional structure diagrams of the magnetic pulse strengthening device of the present invention;

[0028] Figure 2 It is the second three-dimensional structure diagram of the magnetic pulse strengthening device of the present invention;

[0029] Figure 3 It is the three-dimensional structure diagram of the magnetic pulse strengthening component in Embodiment 1;

[0030] Figure 4 It is the working state diagram of the magnetic pulse strengthening component in Embodiment 1;

[0031] Figure 5 For Figure 4Schematic diagram of the enlarged structure of part A;

[0032] Figure 6 is Figure 4 Schematic diagram of the enlarged structure of part B;

[0033] Figure 7 Schematic diagram of the structure of the system circuit of the magnetic pulse strengthening power supply module of the present invention;

[0034] Figure 8 Workflow of the magnetic pulse strengthening process of the present invention;

[0035] Figure 9 Overall effect of performance test of applying the magnetic pulse strengthening process to the cylindrical additive workpiece in Embodiment 1;

[0036] Figure 10 Cross-sectional view effect of performance test of applying the magnetic pulse strengthening process to the additive workpiece in Embodiment 1;

[0037] Figure 11 Schematic diagram of the three-dimensional structure of the magnetic pulse strengthening component in Embodiment 2;

[0038] Figure 12 Schematic diagram of the working state of the magnetic pulse strengthening component in Embodiment 2;

[0039] Figure 13 Overall effect of performance test of applying the magnetic pulse strengthening process to the cylindrical additive workpiece in Embodiment 2;

[0040] Figure 14 Cross-sectional view effect of performance test of applying the magnetic pulse strengthening process to the additive workpiece in Embodiment 2.

[0041] In the figure: 1. Magnetic pulse strengthening component; 101. Magnetic collector; 102. Magnetic pulse strengthening coil; 103. Magnetic pulse strengthening power supply module; 1031. Power supply; 1032. Capacitor; 1033. Capacitor switch; 1034. Inductor; 1035. Resistor; 2. Additive forming table; 3. First vertical positioning mechanism; 4. Lifting positioning plate; 5. Horizontal longitudinal positioning mechanism; 6. Second vertical positioning mechanism; 7. Horizontal transverse positioning mechanism; 8. Arc wire additive welding torch assembly; 9. Lifting frame plate; 901. Mounting frame plate; 902. Clamping cylinder; 903. Clamping pressure plate; 10. Base. Detailed implementation manners

[0042] The following elaborates on the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0043] It should be noted that when a component is referred to as being "installed on" another component, it can be directly on the other component or there can also be an intermediate component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intermediate component at the same time. When a component is considered to be "fixed to" another component, it can be directly fixed to the other component or there may be an intermediate component at the same time.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of this invention herein are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0045] Embodiment 1:

[0046] Please refer to Figure 1 and Figure 2 , the present invention provides a magnetic pulse strengthening device for improving the performance of an additive manufacturing workpiece, including a base 10, an additive manufacturing platform 2 fixedly arranged on the top surface of the base 10, and a first vertical positioning mechanism 3. The positioning output end of the first vertical positioning mechanism 3 is fixedly connected with a lifting positioning plate 4 sleeved outside the additive manufacturing platform 2. The top surface of the lifting positioning plate 4 is respectively fixedly provided with a horizontal longitudinal positioning mechanism 5 and a second vertical positioning mechanism 6. The positioning output end of the horizontal longitudinal positioning mechanism 5 is fixedly connected with a horizontal transverse positioning mechanism 7. The positioning output end of the horizontal transverse positioning mechanism 7 is fixedly connected with an arc wire additive manufacturing torch assembly 8 located above the top surface of the additive manufacturing platform 2. The positioning output end of the second vertical positioning mechanism 6 is fixedly connected with a lifting frame plate 9. The bottom of the lifting frame plate 9 is provided with a magnetic pulse strengthening assembly 1 located directly above the top surface of the additive manufacturing platform 2.

[0047] This device relates to the arc wire additive manufacturing process. Therefore, the arc wire additive welding torch assembly 8 of this device uses an existing commercially available product. The first vertical positioning mechanism 3, the horizontal longitudinal positioning mechanism 5, the second vertical positioning mechanism 6, and the horizontal transverse positioning mechanism 7 respectively adopt linear modules of the ball screw nut pair type driven by servo motors. The first vertical positioning mechanism 3, the horizontal longitudinal positioning mechanism 5, and the horizontal transverse positioning mechanism 7 respectively achieve the positioning of the arc wire additive welding torch assembly 8 in the z-direction, x-direction, and y-direction. The second vertical positioning mechanism 6 is used to drive the lifting movement of the magnetic pulse strengthening assembly 1. Through the logical coordination with the movement of the arc wire additive welding torch assembly 8, the processes of additive forming and magnetic pulse surface strengthening are completed. Therefore, a corresponding servo motion control system needs to be configured to achieve the corresponding logical control, as well as consumables such as metal wires, to form an arc wire additive manufacturing device. The control technologies involved are all existing technologies and will not be elaborated here. Only the innovative points of the present invention will be described in detail below.

[0048] Specifically, the first vertical positioning mechanism 3 includes a vertically established first linear module and three first guide rod assemblies, which are respectively fixedly installed at the four corners of the top surface of the base 10 through fixed brackets. The four corners of the top surface of the lifting positioning plate 4 are respectively fixedly connected with first connection angle seats. The side surfaces of the vertical sections of the first connection angle seats are respectively fixedly connected to the side surface of the positioning table of the first linear module and the side surfaces of the guiding blocks of the three first guide rod assemblies. Under the driving of the first linear module and the guiding action of the three first guide rod assemblies, the vertical lifting and precise positioning of the lifting positioning plate 4 are realized, thereby realizing the z-direction feeding of the arc wire additive welding torch assembly 8 (i.e., the vertical height increases layer by layer). A through hole is opened in the middle of the lifting positioning plate 4, and the additive forming table 2 is located in the through hole, so that the additive forming table 2 will not interfere with the lifting of the lifting positioning plate 4.

[0049] The horizontal longitudinal positioning mechanism 5 includes a second linear module and a second guide rod assembly arranged along the horizontal longitudinal direction ( Figure 1 the x-direction shown in the figure). The left and right sides of the top surface of the lifting positioning plate 4 are respectively fixedly connected with gantry frames. The second linear module and the second guide rod assembly are respectively fixedly installed at the tops of the two gantry frames. The side surface of the positioning table of the second linear module and the side surface of the guiding block of the second guide rod assembly are respectively fixedly connected with "L"-shaped brackets. The horizontal transverse positioning mechanism 7 includes a third linear module arranged along the horizontal transverse direction ( Figure 1 the y-direction shown in the figure). The two ends of the bottom surface of the third linear module are respectively fixedly connected to the top surfaces of the horizontal sections of the two brackets. The top surface of the positioning table of the third linear module is fixedly connected with an "L"-shaped moving frame plate, and the arc wire additive welding torch assembly 8 is fixedly installed on the side surface of the vertical section of the moving frame plate, and the welding torch outlet of the arc wire additive welding torch assembly 8 is vertically downward.

[0050] The second vertical positioning mechanism 6 includes a vertically arranged fourth linear module and a third guide rod assembly, which are respectively fixedly installed at the left and right ends of the top surface of the lifting positioning plate 4 through fixed brackets. Both ends of the lifting frame plate 9 are respectively fixedly connected to the side surface of the positioning table of the fourth linear module and the side surface of the slider of the third guide rod assembly. Under the drive of the fourth linear module and the guiding action of the third guide rod assembly, the vertical lifting and precise positioning of the lifting frame plate 9 can be driven, so as to realize the z-direction feeding and retraction of the magnetic pulse strengthening component 1. Since the horizontal longitudinal positioning mechanism 5 and the second vertical positioning mechanism 6 are both fixedly arranged on the lifting positioning plate 4, the synchronous equidistant step-by-step upward movement of the magnetic pulse strengthening component 1 and the arc wire feeding additive manufacturing torch assembly 8 is realized. When the magnetic pulse surface strengthening parameters of the magnetic pulse strengthening component 1 remain unchanged, the stroke of the fourth linear module driving the magnetic pulse strengthening component 1 to vertically descend each time is fixed and unchanged, that is, to ensure that the relative position of the magnetic pulse surface strengthening working area of it and the top strengthening area of the workpiece 100 obtained by layer-by-layer upward additive deposition forming on the additive forming table 2 is the same in each strengthening process.

[0051] Both sides of the lifting frame plate 9 are "n"-shaped arched structures, which can prevent the lifting frame plate 9 from generating movement interference with the horizontal longitudinal positioning mechanism 5 during the downward movement; the bottom surface of the middle section of the lifting frame plate 9 is fixedly connected with a mounting frame plate 901 through a stud, and the magnetic pulse strengthening component 1 is fixedly connected to the bottom surface of the mounting frame plate 901 through screws, which is convenient for the assembly and disassembly operations of the magnetic pulse strengthening component 1 on the lifting frame plate 9.

[0052] As Figure 3 shown, the magnetic pulse strengthening component 1 includes a magnetic collector 101 with an inverted cone-shaped hollow structure, and a magnetic pulse strengthening coil 102 coaxially arranged on the top surface of the magnetic collector 101. A strengthening groove matching the top contour of the cross-sectional shape of the workpiece 100 is opened on the bottom surface of the magnetic collector 101. The magnetic pulse strengthening coil 102 is a spiral wire structure, and its two ends are respectively connected to the two output electrodes of the magnetic pulse power supply module 103. In this embodiment, the workpiece 100 formed by layer-by-layer additive deposition by the arc wire feeding additive manufacturing torch assembly 8 is a thin-walled cylindrical part, especially a thin-walled cylindrical cylinder. Therefore, the contour of the strengthening groove is circular, and the cross-section matches the cross-sectional shape of the side wall top part of the workpiece 100, so that when the magnetic pulse strengthening component 1 descends to the working position, the top of the side wall of the workpiece 100 is located in the strengthening groove, and the top surface and both side surfaces of the workpiece 100 are respectively arranged parallel to the groove bottom surface and the groove wall surfaces on both sides of the strengthening groove, and gaps are left, as Figure 4 and Figure 5 shown. Preferably, the gap distances on all three sides are 1 mm. Figure 5In [the figure], for the workpiece 100, the part below the dashed line is the strengthened part, and the part above the dashed line is the part to be strengthened. Since the height of a single layer of additive deposition during the layer-by-layer additive deposition forming process of the arc wire feeding additive manufacturing gun assembly 8 is less than the groove depth of the strengthening groove, each additive layer can undergo multiple magnetic pulse surface strengthening processes, making the surface strengthening uniform and sufficient.

[0053] As Figure 4 and Figure 6 shown, a clamping cylinder 902 is fixedly connected to the bottom of the mounting plate 901. A clamping pressure plate 903 is detachably connected to the bottom of the clamping cylinder 902. The top edge of the magnetic collector 101 is clamped between the clamping pressure plate 903 and the clamping cylinder 902, and the magnetic pulse strengthening coil 102 is located inside the clamping cylinder 902. In this embodiment, the clamping cylinder 902 is a cylindrical cylinder, and connecting flanges are provided on both the upper and lower sections of the side wall. The upper flange is fixedly connected to the bottom surface of the mounting plate 901 through a bolt pair. The clamping pressure plate 903 is an annular plate and is detachably assembled with the lower flange of the clamping cylinder 902 by means of a bolt pair or hanging, etc., facilitating the rapid assembly and disassembly of the magnetic pulse strengthening assembly 1. An embedding groove is provided at the inner edge of the top surface of the clamping pressure plate 903, and a clamping flange is fixedly provided at the top edge of the magnetic collector 101. The clamping flange is nested in the embedding groove. After the clamping pressure plate 903 and the clamping cylinder 902 are assembled, the magnetic collector 101 is tightly fixed.

[0054] As Figure 7 shown, the system circuit of the magnetic pulse strengthening power supply module 103 includes a power supply 1031, a capacitor 1032, a capacitor switch 1033, an inductor 1034, and a resistor 1035. One end electrode of the power supply 1031 is connected to one end of the magnetic pulse strengthening coil 102, and the other end electrode of the power supply 1031 is connected to the other end of the magnetic pulse strengthening coil 102 after being connected in series with the inductor 1034 and the resistor 1035 in sequence. The capacitor 1032 and the capacitor switch 1033 are connected in series and are connected in parallel with the two electrode ends of the power supply 1031. In this embodiment, the maximum discharge energy of the magnetic pulse strengthening power supply module 103 is 100 - 150 kJ, the capacitance of the capacitor 1032 is 300 μF, and the discharge voltage is 5 - 20 kV. During the arc wire feeding additive manufacturing process, the power supply 1031 of the magnetic pulse strengthening device is turned on, the capacitor switch 1033 is opened, and the capacitor 1032 starts to charge, and the current flows through the resistor 1035 and the inductor 1034; as time goes by, the voltage in the capacitor 1032 gradually increases, and the current reaches the maximum; after one layer of additive manufacturing is completed, the magnetic pulse strengthening device is moved above the top of the side wall of the already additively manufactured workpiece. The capacitor switch 1033 is turned off, and the capacitor 1032 discharges. Through the electromagnetic field released by the magnetic pulse strengthening coil 102, a magnetic force is generated to impact the top surface of the additively formed workpiece 100, thereby introducing a residual stress field and a certain degree of surface work hardening to the surface to improve the fatigue strength of the workpiece.

[0055] Please refer to Figure 8 , the present invention also provides a magnetic pulse strengthening process for improving the performance of additively manufactured workpieces, which is applied to the magnetic pulse strengthening device for improving the performance of additively manufactured workpieces as described above, and includes the following steps:

[0056] S1. System initialization and device reset: The second vertical positioning mechanism 6 drives the magnetic pulse strengthening component 1 to rise and reset to directly above the area to be additively manufactured on the additive manufacturing table 2, and the horizontal longitudinal positioning mechanism 5 and the horizontal transverse positioning mechanism 7 drive the arc wire additive manufacturing torch assembly 8 to horizontally move and reset to the upper side of the area to be additively manufactured on the additive manufacturing table 2.

[0057] Before system initialization, install the wire and other consumables onto the arc wire additive manufacturing torch assembly 8. After system initialization, conduct necessary debugging on the device to ensure that the motion systems and controls of the arc wire additive manufacturing torch assembly 8 and each positioning mechanism work properly. At the same time, conduct a power-on test on the system circuit of the magnetic pulse strengthening power module 103 to ensure normal use.

[0058] S2. Single-layer arc wire additive manufacturing: The motion control system starts the horizontal longitudinal positioning mechanism 5 and the horizontal transverse positioning mechanism 7 to work, drives the arc wire additive manufacturing torch assembly 8 to move to the area to be additively manufactured on the additive manufacturing table 2, and drives the arc wire additive manufacturing torch assembly 8 to move along a preset forming route. The arc welder inside the arc wire additive manufacturing torch assembly 8 heats and melts the wire to form a molten pool, and the high temperature generated by the welding arc keeps the wire in a molten state before contacting the base 10 (the bottom layer of additive manufacturing) or the previous layer. The torch of the arc wire additive manufacturing torch assembly 8 extrudes the molten metal during movement, and the molten metal deposits and forms, forming a required structure of one layer along the preset forming route. Then, the horizontal longitudinal positioning mechanism 5 and the horizontal transverse positioning mechanism 7 drive the arc wire additive manufacturing torch assembly 8 to move and reset, completing the single-layer additive manufacturing process.

[0059] S3. Magnetic pulse surface strengthening: During the process of arc wire additive manufacturing, the capacitor 1032 completes the charging process. After completing single-layer additive manufacturing, the second vertical positioning mechanism 6 drives the magnetic pulse strengthening component 1 to move down to the outer side of the top of the additively manufactured workpiece 100. The capacitor switch 1033 disconnects, and the capacitor 1032 discharges. The electromagnetic field released by the magnetic pulse strengthening coil 102 generates a magnetic force to impact and strengthen the top surface of the additively manufactured workpiece 100. After reaching the preset impact strengthening time (0.001 - 1 ms in this embodiment), the second vertical positioning mechanism 6 drives the magnetic pulse strengthening component 1 to rise and reset.

[0060] S4. Additive height feeding: The first vertical positioning mechanism 3 drives the arc wire additive manufacturing torch assembly 8 to move up by a single-layer additive manufacturing height to achieve step feeding in the z direction.

[0061] S5, cyclic additive and strengthening process: repeat the above steps S2 to S4 to complete the additive deposition forming process of the workpiece 100 on the additive forming table 2 layer by layer, and after each layer of additive deposition forming, complete the impact strengthening of the top surface of the workpiece 100.

[0062] S6. Removing the sample: After the last magnetic pulse surface impact strengthening is completed, the power supply of the device is disconnected to stop the device from working, and the additively formed workpiece 100 is removed from the additive forming table 2 after cooling to room temperature.

[0063] For the machined workpiece 100, the relationship between the magnetic pulse strengthening parameters and the grain size, metallurgical defects and residual stress is determined through metallographic observation and residual stress detection, providing a control basis for further magnetic pulse strengthening microstructure control and residual stress control.

[0064] In the simulation software, the above magnetic pulse surface impact strengthening process is simulated, and finally the distribution of the surface equivalent stress of the additive workpiece after magnetic pulse strengthening is obtained, such as Figure 9 and Figure 10 As shown in the simulation results, it can be seen that when the additive workpiece is strengthened by magnetic pulse, its top surface is subjected to a large impact force, and the side surface is also subjected to a certain pressure due to the special structure of the magnetic collector, which ensures the integrity of the workpiece as a whole and has a certain depth of the affected layer to achieve the purpose of improving performance.

[0065] Obviously, the anisotropic magnetic collector can be designed into a variety of shapes to meet the application needs of the magnetic pulse surface impact strengthening process for additive workpieces with different cross-sectional shapes (not limited to cylindrical barrels).

[0066] Embodiment 2:

[0067] See also Figure 11 and Figure 12 The difference between this embodiment and the first embodiment is that the outer shape of the magnetic collector 101 is a hollow quadrangular pyramid structure, the cross-section of the strengthening groove is a rectangular horizontal groove, which runs through both ends of the bottom surface of the magnetic collector 101, the pulse strengthening coil 102 is correspondingly a rectangular spiral disk structure, the clamping tube 902 and the clamping pressure plate 903 are correspondingly hollow square frame structures, and the remaining structures are basically the same as those in the first embodiment.

[0068] In specific use, the workpiece 100 formed by the layer-by-layer additive deposition of the arc fuse additive welding gun assembly 8 is a thin plate, especially a thin plate with a rectangular cross-section, so the cross-section of the strengthening groove matches the cross-sectional shape of the top portion of the side wall of the workpiece 100, so that when the magnetic pulse strengthening assembly 1 is lowered to the working position, the top end of the side wall of the workpiece 100 is located in the strengthening groove, and the top surface and the two side surfaces of the workpiece 100 are respectively arranged in parallel with the bottom surface of the strengthening groove and the groove wall surfaces on both sides, and gaps are left, such asFigure 11 and Figure 12 As shown. Preferably, the gap distances on the three sides are all 1 mm. Since the height of a single layer of additive material is less than the depth of the strengthening groove during the layer-by-layer additive deposition forming process of the arc fuse additive welding gun assembly 8, each additive layer can undergo multiple magnetic pulse surface strengthening processes, so that the surface strengthening is uniform and sufficient.

[0069] Similarly, for the machined workpiece 100, the relationship between the magnetic pulse strengthening parameters and the grain size, metallurgical defects and residual stress is determined through metallographic observation and residual stress detection, providing a control basis for further magnetic pulse strengthening microstructure control and residual stress control.

[0070] In the simulation software, the above magnetic pulse surface impact strengthening process is simulated, and finally the distribution of the surface equivalent stress of the additive workpiece after magnetic pulse strengthening is obtained, such as Figure 13 and Figure 14 As shown in the simulation results, it can be seen that since the central strengthening part of the additive workpiece is a solid structure, which is different from the hollow cylindrical structure of the first embodiment, when the additive workpiece is strengthened by magnetic pulse, the impact force on the center of its top surface is larger than that on both sides, but the side surfaces are also subject to a certain pressure due to the special structure of the magnetic collector, which ensures the integrity of the workpiece as a whole and has a certain depth of the affected layer to achieve the purpose of improving performance.

[0071] The present invention innovatively applies electromagnetic forming technology to the post-processing of the WAAM process, and utilizes the RLC circuit discharge process coil to generate a magnetic field, so that a magnetic field force is generated inside the workpiece to achieve plastic deformation of the workpiece surface. In the additive process, the RLC circuit is charged and then discharged to achieve magnetic pulse strengthening, saving working time and improving efficiency; for the magnetic pulse strengthening process, its strain rate is high and the energy released is large, so it has a higher depth of the affected layer; there is no contact, and the surface quality of the formed workpiece is relatively good. In addition, high-frequency magnetic pulse strengthening can also refine the grains and eliminate microscopic void defects, thereby improving the mechanical properties and uniformity of the material. Since the workpiece will be subjected to a large electromagnetic force during the magnetic pulse strengthening process, in order to avoid a large deformation of the workpiece during this process, the shape of the magnetizer is designed so that the workpiece can be subjected to compressive stress on the side while being subjected to the top impact. While ensuring that the shape of the workpiece does not change too much, it is subjected to three-way compressive stress and improves the mechanical properties.

[0072] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above are only embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included within the patent protection scope of the present invention.

Claims

1. A magnetic pulse strengthening device for improving the performance of additively manufactured workpieces, characterized in that: It includes a base, an additive manufacturing platform fixedly arranged on the top surface of the base, and a first vertical positioning mechanism. The positioning output end of the first vertical positioning mechanism is fixedly connected with a lifting positioning plate sleeved outside the additive manufacturing platform. The top surface of the lifting positioning plate is fixedly provided with a horizontal longitudinal positioning mechanism and a second vertical positioning mechanism respectively. The positioning output end of the horizontal longitudinal positioning mechanism is fixedly connected with a horizontal transverse positioning mechanism. The positioning output end of the horizontal transverse positioning mechanism is fixedly connected with an arc wire additive manufacturing torch assembly located above the top surface of the additive manufacturing platform. The positioning output end of the second vertical positioning mechanism is fixedly connected with a lifting frame plate. A magnetic pulse strengthening assembly is arranged at the bottom of the lifting frame plate and is located directly above the top surface of the additive manufacturing platform. The magnetic pulse strengthening assembly includes a magnetic collector with an inverted cone-shaped hollow structure and a magnetic pulse strengthening coil coaxially arranged on the top surface of the magnetic collector. The bottom surface of the magnetic collector is provided with a strengthening groove matching the top contour of the cross-sectional shape of the workpiece. The unilateral vertical cross-sectional shape of the strengthening groove is an inverted "U". The magnetic pulse strengthening coil is in a spiral structure and its two ends are respectively connected with two output electrodes of the magnetic pulse strengthening device. The arc wire additive manufacturing torch assembly deposits and forms the workpiece layer by layer upward on the additive manufacturing platform. After each layer of additive deposition and forming is completed, the magnetic pulse strengthening assembly is positioned outside the top of the workpiece that has been additively formed. The magnetic pulse strengthening assembly simultaneously impacts and strengthens the top three-side surfaces of the workpiece through magnetic field force.

2. The magnetic pulse strengthening device for improving the performance of an additive manufacturing workpiece according to claim 1, wherein: The system circuit of the magnetic pulse strengthening device includes a power supply, a capacitor, a capacitor switch, an inductor, and a resistor. One electrode end of the power supply is connected to one end of the magnetic pulse strengthening coil. The other electrode end of the power supply is connected to the other end of the magnetic pulse strengthening coil in series with the inductor and the resistor in sequence. The capacitor and the capacitor switch are connected in series and are connected in parallel with the two electrode ends of the power supply.

3. The magnetic pulse strengthening device for improving the performance of an additive manufacturing workpiece according to claim 2, wherein: The maximum discharge energy of the magnetic pulse strengthening device is 100 - 150 kJ, the capacitance of the capacitor is 160 - 320 μF, and the discharge voltage is 5 - 20 kV.

4. A magnetic pulse strengthening device for improving the performance of an additive manufacturing workpiece according to claim 1, characterized in that: The bottom of the lifting frame plate is fixedly connected with an installation frame plate. The bottom of the installation frame plate is fixedly connected with a clamping cylinder. The bottom of the clamping cylinder is detachably connected with a clamping pressure plate. The top surface edge of the magnetic collector is clamped between the clamping pressure plate and the clamping cylinder. The magnetic pulse strengthening coil is located inside the clamping cylinder.

5. A magnetic pulse strengthening process for improving the performance of additively manufactured workpieces, which is applied to the magnetic pulse strengthening device for improving the performance of additively manufactured workpieces as described in any one of claims 1 to 4, characterized in that, It includes the following steps: S1. The magnetic pulse strengthening assembly rises and resets to directly above the area to be additively manufactured, and the arc wire additive manufacturing torch assembly horizontally moves and resets to the upper side of the area to be additively manufactured. S2. The arc wire additive manufacturing torch assembly moves to the area to be additively manufactured, moves according to the preset forming route, and moves and resets after completing the single-layer molten metal deposition and forming. S3. The magnetic pulse strengthening assembly moves down to the outside of the top of the workpiece that has been additively formed, impacts and strengthens the upper surface and the two side surfaces of the top of the workpiece through magnetic field force. After reaching the preset impact strengthening time, the magnetic pulse strengthening assembly rises and resets. S4. The arc wire additive manufacturing torch assembly moves up by a single-layer additive height. S5. Cycle the additive manufacturing and strengthening processes: Repeat steps S2 to S4 to complete the layer-by-layer upward additive deposition and forming of the workpiece on the additive manufacturing platform and the impact strengthening of the top surface. S6. The device stops working, and after the workpiece to be additively manufactured is cooled to room temperature, it is removed from the additive manufacturing platform.

6. A magnetic pulse strengthening process for improving the performance of an additive manufacturing workpiece according to claim 5, characterized in that: In step S3, the distance between the side surface of the strengthening groove on the bottom surface of the magnetic collector and the outer surface of the top of the additively manufactured workpiece is 0.5 - 2 mm, and the preset impact strengthening time is 0.001 - 1 ms.

7. A magnetic pulse strengthening process for improving the performance of an additive manufacturing workpiece according to claim 5 or 6, characterized in that: After step S6, the relationships between the magnetic pulse strengthening parameters and the grain size, metallurgical defects, and residual stress are determined through metallographic observation and residual stress detection.

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