Atmosphere and electromagnetic assisted 3d printing of metal parts

Abstract

The application provides an atmosphere and electromagnetic auxiliary metal piece 3D printing forming device, which comprises a nozzle device, a work platform, a screw lifting mechanism, an electromagnetic stirring device and a rack, the nozzle assembly adopts a single extrusion head double-nozzle structure, and an atmosphere auxiliary device is arranged, which reduces the weight of the nozzle, expands the effective working stroke of the double nozzle, maximally utilizes the equipment space and increases the effective stroke of printing. The atmosphere auxiliary device is used for adjusting the composition of the metal solution and makes hot air flow blow to the upper layer of the 3D printed piece, the high-temperature air flow plays an instantaneous heating and pressurizing role on the surface of the part of the molten material, adjusts the flow rate of the molten liquid, improves the interlayer bonding strength of the printed sample and the performance of the product, and obtains a metal product with excellent performance. Meanwhile, the electromagnetic stirring device is installed on the work platform, the advantages of non-contact processing of the magnetic field are realized, and the performance of the FDM type molten metal powder forming part is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing, in particular to an atmosphere and electromagnetic auxiliary metal part 3D printing forming device. BACKGROUND

[0002] Fused Deposition Modeling (FDM) technology is also called extrusion forming technology. The FDM (Fused Deposition Modeling) 3D printer melts and deposits the printing material to the printing platform by heating the printing nozzle. The melted printing material quickly coagulates when it contacts the printing platform. The printing head deposits the printing material layer by layer on the printing platform along the set printing path, thereby constructing a model with a three-dimensional structure.

[0003] By taking advantage of the fullness of the atmosphere and the material contact, as well as the characteristics of easy replenishment and easy adjustment of the atmosphere, the diffusion and chemical reaction between the atmosphere and the metal in the heating area are induced, and the performance and organization of the material are controlled. The active atmosphere widely used at present takes O, N, C and other light elements as the main active components. These elements have small atomic radii and can often form interstitial solid solutions with a high atomic fraction in metal materials, improve the atmosphere protection effect in the melting and deposition process, improve and eliminate the internal stress of the additive manufacturing process, reduce defects such as cracks and pores, optimize the microstructure, improve the isotropy and comprehensive mechanical properties, adjust the composition of the metal solution and the flow rate of the liquid, etc.

[0004] With the development of modern electromagnetic technology and the proposal of "Electromagnetic Processing of Materials" (EPM), electromagnetic processing of materials refers to the combination of magnetohydrodynamics (MID) and material processing technology, and the application of electromagnetic fields in material preparation and processing to control the material process and improve the material organization and performance. In casting, the use of strong magnetic fields can change the critical nucleation core size, customize the crystal orientation, and reduce the solidification point of paramagnetic substances and increase the solidification point of diamagnetic substances.

[0005] As mentioned earlier, the main measures to improve the performance of metal powder formed parts at home and abroad are to improve material properties, optimize process and post-processing methods, etc. At present, there is no FDM type melting metal powder forming method and device under a magnetic field. If the rapid manufacturing technology of melting metal powder under a magnetic field is realized, based on the "non-contact" processing advantages of the magnetic field, it is expected to improve the performance of FDM type melting metal powder formed parts and promote the application and promotion of metal part direct rapid manufacturing technology and equipment. SUMMARY

[0006] Based on the above deficiencies of the prior art, in order to solve the technical problems of uneven material composition, obvious grain orientation, easy to produce pores and cracks in the existing metal powder rapid melting manufacturing process, the present application provides an atmosphere and electromagnetic auxiliary metal 3D printing forming device, which installs a single yoke double-tuned electromagnet at the nozzle and installs an electromagnetic stirring device on the work platform to minimize defects and improve the performance of the product. By changing the pressure of the atmosphere, the flow rate of the metal solution is adjusted. By inputting high temperature and high pressure atmosphere to the printing nozzle, the composition of the metal solution is adjusted, the hot gas stream is blown to the surface layer of the 3D printed part, and the high temperature gas stream is used to instantaneously heat and pressurize the surface of the molten material, thereby adjusting the flow rate of the molten liquid and improving the performance of the final product.

[0007] Specifically, the present application provides an atmosphere and electromagnetic auxiliary metal 3D printing forming device, which comprises a nozzle device, a work platform, a screw lifting mechanism, an electromagnetic stirring device and a rack,

[0008] The rack comprises a horizontal frame, a vertical frame, a Z-axis screw, a Y-axis light rod, an X-axis light rod, a Z-axis light rod and a bottom plate, the vertical frame is arranged vertically to the horizontal frame, the horizontal frame is a rectangular frame, the vertical frame is a door-shaped frame, the Y-axis light rod is arranged in the horizontal frame along the Y-axis direction, the Z-axis screw and the Z-axis light rod are arranged on both sides of the vertical frame, and the X-axis light rod is arranged in the vertical frame and is in sliding connection with the Z-axis screw and the Z-axis light rod;

[0009] The work platform comprises a worktable and a sliding plate, the sliding plate comprises a plate-shaped upper sliding plate and a lower sliding plate, a group of screw lifting mechanisms are fixed at the four corners of the lower sliding plate, the worktable is located at the middle position of the electromagnetic stirring device and is fixed on the lower sliding plate, the work platform is arranged on the Y-axis light rod by means of the lower sliding plate and slides along the Y-axis light rod, the screw lifting mechanisms are installed on the work platform and connected with the lower sliding plate, the upper sliding plate is fixedly connected with the four groups of screw lifting mechanisms at the four corners through screw nuts, and the upper sliding plate on which the electromagnetic stirring device is installed is vertically lifted by the bottom motor driving the screw lifting mechanisms;

[0010] The nozzle device is arranged on the X-axis light rod by means of a sliding block and slides along the X-axis light rod, the nozzle device comprises a nozzle assembly, a single yoke double-tuned electromagnet, a nozzle fixing cover and a nozzle fixing block, the nozzle assembly is arranged on the nozzle fixing block by means of the nozzle fixing cover, and the nozzle fixing block is connected with the sliding block; the nozzle assembly comprises a throat pipe, a heating block, an electromagnetic induction heating coil, a nozzle, an air inlet channel and an air outlet pipe, the nozzles are arranged in pairs, and the single yoke double-tuned electromagnet is fixed on the nozzle assembly by an L-shaped structure of two side yokes;

[0011] The throat pipe comprises a first section of the throat pipe as a material guide pipe and a second section of the throat pipe extending to the inside of the heating block; the second section of the throat pipe is connected with the nozzle, the two oblique edges of the heating block are provided with air inlet channels for inputting high-temperature and high-pressure atmosphere, the lower part of the second section of the throat pipe and the upper part of the nozzle are respectively connected with the air inlet channels, the electromagnetic induction coil is arranged on the heating block, two air outlet pipes are arranged outside each nozzle, the metal powder enters the nozzle from the material guide pipe and is heated to start melting and extrusion by the electromagnetic induction heating coil, the high-temperature and high-pressure atmosphere input by the air inlet channels contacts the metal powder discharged at the material guide pipe and applies pressure to assist the metal powder to enter the nozzle, and the high-temperature and high-pressure atmosphere discharged by the air outlet pipes protects the molten metal extruded by the nozzle and adjusts the flow rate and composition of the molten metal;

[0012] The electromagnetic stirring device is arranged on the upper slide plate of the work platform; the electromagnetic stirring device comprises a yoke, a coil, a magnetic core, a yoke back body and an adjusting nut, six yokes are arranged at intervals in the circumferential direction of the yoke back body, the outer surface of each yoke is wound with a coil, the coil is connected with a power supply, one magnetic core is connected behind each yoke, the yoke back body is in the shape of a circular ring, the yokes are uniformly arranged on the inner side of the yoke back body and extend towards the center of the yoke back body, and the yoke and the yoke back body form an E-shaped structure; the adjusting nut is mounted on the magnetic core for adjusting the distance between the yoke and the yoke back body, a processing area is formed in the central area of the yoke back body, the central area of the electromagnetic stirring device forms a processing area and is provided with a worktable, the processed material is placed in the worktable, when the power supply provides alternating current for the coil, the current flowing through the coil makes the yoke generate a magnetic field, the magnetic field generates an electromagnetic force in the circumferential direction, and the electromagnetic force can push the flow of the processed material melt to change the mass transfer and heat transfer process of the processed material;

[0013] The electromagnetic stirring device acts on the workpiece placed in the middle position of the worktable, and the position of the yoke in the electromagnetic stirring device is adjusted according to the size of the workpiece, and the specific adjustment process is as follows:

[0014] S1, calculate the electromagnetic force density of the metal solution: the electromagnetic force density of the metal solution is = , J is the electromagnetic density, B is the magnetic induction intensity; wherein the magnetic induction intensity is B=N×I / Le, N is the number of turns of the excitation coil, I is the excitation current, and Le is the effective magnetic path length of the workpiece;

[0015] S2, calculate the effective magnetic path length: measure the distance L from the workpiece to the yoke around the electromagnetic stirring device by the reflected energy method, and then calculate the effective magnetic path length according to the formula Le=πL;

[0016] S3, the sensor monitors the strength of the electromagnetic force, transmits the signal to the servo motor driving the magnetic yoke to move, so that the magnetic yoke is controlled by the servo motor to move forward or backward, and finally the magnetic yoke in the electromagnetic stirring device is moved to the appropriate position;

[0017] The screw rod lifting mechanism comprises four screw rods, four elevators, three connecting rods, three transmission mechanisms, a driving motor and four screw rod nuts; wherein the screw rod is connected with the elevator through the screw rod nut to form a set of screw rod elevators, the screw rod lifting mechanism is formed by four sets of screw rod elevators, the four sets of screw rod elevators are fixed at the four corners of the lower sliding plate, each set of screw rod elevator is connected by a connecting rod, and the four sets of screw rod elevators are simultaneously lifted through the connecting transmission mechanism, the upper sliding plate provided with the electromagnetic stirring device is fixed with the screw rod nut, and the four sets of screw rod elevators are simultaneously lifted through the driving of the driving motor to realize the lifting of the electromagnetic stirring device in the vertical direction.

[0018] The object table comprises a thin plate object table, an automatic lifting mechanism, a thick plate object table and a magnet, the lifting structure is installed at the four corners below the thick plate object table; the thin plate object table is adsorbed above the thick plate object table by the magnet, after the workpiece is completed printing, the electromagnetic stirring device is lowered to the lowest position, the object table is raised to take away the workpiece from the thin plate object table and replace the next thin plate object table.

[0019] Preferably, the material guide pipe is wrapped with the heat dissipation fins.

[0020] Preferably, the lower sliding plate is provided with screw holes at four corners, and the lower sliding plate is fixedly connected with the Y-axis light rod upper sliding block through screws.

[0021] Preferably, the heating block is provided with through holes capable of inserting temperature sensors on both sides, and the temperature sensors can real-time feedback temperature changes.

[0022] Preferably, the heating block is provided with an air pressure flow channel inside, the air pressure flow channel is connected with an air inlet channel and an air outlet pipe, four air pressure flow channels and four air outlet pipes are arranged for each nozzle, the air outlet pipes are distributed equidistantly around the nozzles and connected with the air pressure flow channels in the heating block through brazing connection; high-temperature and high-pressure atmosphere is introduced into the metal powder through the air inlet channel for pressurization, and after the action, the high-temperature and high-pressure atmosphere flows through the air pressure flow channel and is discharged through the air outlet pipe to react with the molten metal liquid.

[0023] Preferably, the single-yoke double-adjusting electromagnet comprises a yoke, electromagnet poles and an adjusting handle.

[0024] Preferably, the yoke is provided with an L-shaped structure, and the L-shaped structure is fixed on the nozzle device through screws.

[0025] Preferably, the sliding blocks connected with the nozzle device are provided with two through holes corresponding to the light rods of the X-axis at both ends.

[0026] Preferably, the nozzle device further comprises an exhaust fan arranged in front of the nozzle and connected to the nozzle through an exhaust fan fixing seat, and the fixing seat is in L-shaped structure, with the long side fixed to the exhaust fan and the short side connected to the nozzle through a U-shaped opening.

[0027] Preferably, the magnetic field auxiliary device is an electromagnetic stirring device, which comprises a magnetic yoke body and a magnetic yoke back body, wherein a cylindrical magnetic core is connected to the back of the magnetic yoke body, and an adjusting handle is connected to the cylindrical magnetic core, which is used to adjust the distance between the symmetrical magnetic yokes and thus the magnetic field strength.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) The present application provides a method and device for rapid manufacturing of metal parts under the action of a magnetic field. The electromagnetic stirring device is installed on the working platform to realize the advantage of "non-contact" processing of the magnetic field, improve the performance of FDM type melted metal powder formed parts, and promote the application of direct rapid manufacturing technology and equipment of metal parts.

[0030] (2) The nozzle of the present application adopts a single extrusion head double nozzle structure, and an atmosphere auxiliary device is arranged to reduce the weight of the nozzle, expand the effective working stroke of the double nozzle, maximize the use of equipment space, and increase the effective stroke of printing. The atmosphere auxiliary device is used to adjust the composition of the metal solution, and hot gas flow is blown to the upper layer of the 3D printed part. The high-temperature gas flow plays an instantaneous heating and pressurizing role on the surface of the part of the solid material, adjusts the flow rate of the molten liquid, improves the interlayer bonding strength of the printed sample and the performance of the product, and obtains a metal product with excellent performance.

[0031] (3) The metal 3D printer with magnetic field auxiliary function and atmosphere auxiliary function of the present application adjusts the flow rate of the metal solution by changing the pressure of the added atmosphere during the preparation process. By setting an atmosphere pressure flow channel, high-temperature and high-pressure atmosphere is input to the printing nozzle, and hot gas flow is blown to the upper layer of the 3D printed part. The high-temperature gas flow plays an instantaneous heating and pressurizing role on the surface of the part of the solid material, improves the interlayer bonding strength of the printed sample and the performance of the product, and obtains a metal product with excellent performance. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a perspective view of the atmosphere and electromagnetic auxiliary metal part 3D printing forming device of the present application;

[0033] Figure 2 It is a perspective view of the nozzle device of the present application;

[0034] Figure 3 It is a perspective view of the rack of the present application;

[0035] Figure 4 A perspective view of the nozzle of the present application;

[0036] Figure 5 A perspective view of the atmosphere assisting structure of the present application;

[0037] Figure 6 A perspective view of the electromagnetic stirring device of the present application;

[0038] Figure 7 A perspective view of the single-yoke double-tuned electromagnet of the present application;

[0039] Figure 8 A perspective view of the lead screw lifting mechanism of the present application;

[0040] Figure 9 A schematic view of the object carrier in the work platform of the present application.

[0041] Some reference numerals in the figures are as follows: 1 - nozzle device, 11 - nozzle assembly, 12 - nozzle fixing cover, 13 - exhaust fan fixing seat, 14 - exhaust fan, 15 - single-yoke double-tuned electromagnet, 16 - heating block, 17 - nozzle fixing block, 18 - sliding block, 19 - nozzle, 110 - air outlet pipe, 111 - throat pipe, 112 - cooling fin, 113 - air inlet channel, 114 - air pressure flow channel, 115 - electric induction heating coil, 116 - yoke, 117 - electromagnet pole head, 118 - adjusting handle (handle not shown);

[0042] 2 - frame, 21 - corner code, 23 - horizontal linear bearing fixing, 24 - shaft coupling, 25 - aluminum profile, 26 - stepping motor, 27 - stepping motor mounting seat, 28 - X-axis motor fixing piece, 201 - horizontal frame, 202 - vertical frame, 203 - Z-axis lead screw, 204 - Y-axis lead screw, 205 - X-axis lead screw, 206 - Z-axis lead screw, and 207 - bottom plate;

[0043] 3 - electromagnetic stirring device, 31 - magnetic yoke, 32 - coil, 33 - magnetic core, 34 - magnetic yoke back body, 35 - adjusting nut;

[0044] 4 - lead screw lifting mechanism, 41 - lead screw, 42 - lifter, 43 - connecting rod, 44 - transmission mechanism, 45 - driving motor, 46 - lead screw nut;

[0045] 5 - work platform, 51 - thin plate object carrier, 52 - automatic lifting mechanism, 53 - thick plate object carrier, 54 - magnet. DETAILED DESCRIPTION

[0046] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings.

[0047] The application provides a 3D printing forming device for metal parts under the action of a magnetic field and the atmosphere auxiliary action of a nozzle. Figure 1 As shown in the figure, the application provides a 3D printing forming device for metal parts under the action of the atmosphere and the electromagnetic auxiliary, which comprises a nozzle device 1, a work platform 5, a screw lifting mechanism 4, an electromagnetic stirring device 3 and a rack 2.

[0048] The rack 2 adopts a rectangular frame type series transmission structure, and the transmission of three orthogonal directions of XYZ jointly controls the printing process. The bottom of the rack 2 is fixedly connected by four aluminum profiles, and each adjacent two aluminum profiles are connected by vertical corner codes. In the application, a light rod is arranged in each of the three orthogonal directions of XYZ, and a lead screw is arranged in the Z-axis direction. Specifically, the rack 2 comprises a shaft coupling 24, a horizontal frame 201, a vertical frame 202, a Z-axis lead screw 203, a Y-axis light rod 204, an X-axis light rod 205, a Z-axis light rod 206 and a bottom plate 207. The vertical frame 202 is arranged perpendicularly to the horizontal frame 201, the horizontal frame 201 is a rectangular frame, and the vertical frame 202 is a door-shaped frame. The Y-axis light rod 204 is arranged in the horizontal frame 201 along the Y-axis direction. The Z-axis lead screw 203 and the Z-axis light rod 206 are arranged on the two sides of the vertical frame 202, respectively. The X-axis light rod 205 is arranged in the vertical frame 202 and is in sliding connection with the Z-axis lead screw 203 and the Z-axis light rod 206. The lead screw is driven by a stepping motor 26, and the stepping motor 26 is installed by a stepping motor mounting seat 27.

[0049] The work platform 5 comprises a carrier table and a sliding plate (not shown in the figure). The sliding plate comprises a plate-shaped upper sliding plate and a lower sliding plate. The upper sliding plate is a sliding plate for fixing the electromagnetic stirring device, and the lower sliding plate is a sliding plate for fixing the Y-axis. A group of screw lifting mechanisms are fixed at the four corners of the lower sliding plate. The carrier table is located at the middle position of the electromagnetic stirring device and is fixed on the lower sliding plate. The work platform is arranged on the Y-axis light rod by means of the lower sliding plate and slides along the Y-axis light rod. The work platform is provided with the screw lifting mechanism, and the screw lifting mechanism and the lower sliding plate are connected by four screws. The upper sliding plate and the four groups of screw lifting mechanisms at the four corners are fixedly connected by screw nuts, and the upper sliding plate for fixing the electromagnetic stirring device is lifted in the vertical direction by the bottom motor driving the screw lifting mechanism.

[0050] The nozzle device 1 is arranged on the X-axis light rod by means of a sliding block and slides along the X-axis light rod. The single-yoke double-tuning electromagnet structure at the nozzle is fixed on the nozzle device by the L-shaped structure of the two side yokes. The electromagnetic stirring device is arranged on the upper sliding plate of the work platform.

[0051] Figure 3The bottom of the frame 2 is shown in the perspective view, the front and rear aluminum profiles 25 are each provided with three through holes of the same size and equal distance, and the middle through hole is provided as a threaded hole. The Y-axis light rod is provided with a horizontal linear bearing fixed 23. The outer side of the aluminum profile at both ends is fixedly connected with the side aluminum profile through the corner code, and the upper end of the side aluminum profile is fixedly connected with the top aluminum profile through the corner code 21; the inner side of the aluminum profile at both ends is fixedly connected through the fixed corner code 21. The X-axis motor fixed part 28 is symmetrically arranged on the light rod and the lead screw at both ends and is in sliding connection with the light rod and the lead screw.

[0052] Figure 2 The nozzle device 1 shown includes a nozzle assembly 11, a nozzle fixing cover 12, and a nozzle fixing block 17, the nozzle assembly is connected with the nozzle fixing cover 12 and the nozzle fixing block 17, the nozzle fixing block 17 is further connected with a sliding block 18, the sliding block 18 is connected with the X-axis light rod and can slide on the X-axis light rod. The sliding block 18 is provided with two through holes corresponding to the X-axis light rod 205 at both ends.

[0053] The nozzle assembly 11 is a double-nozzle conical structure, including a single-yoke double-tuned electromagnet 15, a throat 111, two nozzles 19, a heating block 16, and a middle heat sink 112 connected with the nozzle assembly through a magnetic yoke 31. The single-yoke double-tuned electromagnet 15 is connected with the nozzle assembly through the magnetic yoke 31, as shown in Figure 5 The heating block 16 is heated by an inductor coil, and both sides pass through a through hole, which is a temperature sensor hole for installing a temperature sensor. The heating block 16 is provided with two circular ring holes on the two inclined sides as air inlet channels, which can be used to input high-temperature and high-pressure atmosphere to the metal powder and apply the affected atmosphere to the printed surface layer to promote the thermal pressure bonding effect of the metal material between the layers and improve the mechanical strength of the printed part in the vertical direction. Two nozzles 19 are arranged below the heating block 16, and the nozzles 19 are provided with four 110 gas outlets. The gas outlet 110 can be a ceramic gas outlet, and the four ceramic gas outlets are distributed equidistantly in the circumferential direction. The double-nozzle and its heating extrusion structure are integrated on the same extrusion head, which reduces the weight of the nozzle and greatly reduces the distance between the nozzles. A exhaust fan 14 is arranged in front of the nozzles 19 to prevent overheating and burning of the components. The exhaust fan 14 is connected with the nozzles 19 through a fan fixing seat 13. The exhaust fan 14 is arranged in front of the nozzles 19 and connected with the nozzles 19 through the exhaust fan fixing seat 13. The fan fixing seat is an L-shaped structure, the long side of the L-shaped structure is fixed with the exhaust fan 14, and the short side is connected with the nozzles 19 through a U-shaped opening.

[0054] Figure 4The schematic diagram of the nozzle assembly is shown, the nozzle assembly 11 is provided with fins 112, a heating block 16, two nozzles 19 and eight ceramic air outlet pipes, every four ceramic air outlet pipes are equidistantly arranged to form a circle and act on one nozzle, the nozzle device adopts a single extrusion head with double nozzles, and the double nozzles and the heating extrusion structure are integrated on the same extrusion head. The heating block 16 is heated by an inductor coil, and the two inclined sides are each provided with an air inlet and a circular annular air inlet channel, and a high-temperature and high-pressure atmosphere is input, wherein the throat pipe is divided into two sections, the first section of the throat pipe serves as a material guide pipe, and the outside is wrapped with fins, and the second section of the throat pipe is arranged inside the heating block. In specific applications, the heating block 16 is designed with an aluminum block.

[0055] Figure 5 The schematic diagram of the heating block and the nozzle is shown, the heating block 16 is heated by an inductor coil 115, and each side is provided with a hole as a temperature sensor mounting hole. The heating block 16 is provided with an air inlet and a circular annular air inlet channel 113 on the two inclined sides, wherein the lower part of the throat pipe 111 and the upper part of the nozzle 19 are connected with the air inlet channel respectively, a high-temperature and high-pressure atmosphere is filled through the air inlet, and the filled atmosphere flows through the ceramic air outlet pipe 110 through the air pressure flow channel 114 and is sprayed to the extruded molten metal liquid, the heating block 16 is provided below with two nozzles 19, the two nozzles 19 are surrounded by four ceramic air outlet pipes 110 respectively, and the ceramic air outlet pipes 110 and the heating block 16 are connected by brazing. The double nozzle and the heating extrusion structure are integrated on the same extrusion head by adopting a double nozzle device, and two atmosphere auxiliary nozzles are fixed outside the two nozzles, which can improve the performance of the final product.

[0056] Figure 6 The schematic diagram of the electromagnetic stirring device is shown, the electromagnetic stirring device includes a magnetic yoke 31, a coil 32, a magnetic core 33, a magnetic yoke back body 34 and a nut 35, six magnetic yokes 31 are arranged at intervals in the circumferential direction of the magnetic yoke back body 34, the outer surface of each magnetic yoke 31 is wound with a coil 32, the coil 32 is connected with a power supply (not shown in the figure), and the back of each magnetic yoke 31 is connected with a magnetic core 33, and the nut 35 is installed on the magnetic core 33 for adjusting the distance between the symmetrical magnetic yokes. The magnetic yoke back body 34 is in the shape of a circular ring, the magnetic yokes 31 are fixed on the inner side of the magnetic yoke back body 34 and extend towards the center of the magnetic yoke back body 34, that is, the magnetic yokes 31 and the magnetic yoke back body 34 form an E-shaped structure. A processing area is formed in the central region of the magnetic yoke back body 34, that is, the central region of the electromagnetic stirring device forms a processing area, and the processed material is placed in the object table. When the power supply provides alternating current for the coil 32, the current flowing through the coil 32 generates a magnetic field in the magnetic yoke 31, the magnetic field can generate an electromagnetic force in the circumferential direction, the electromagnetic force can promote the flow of the melt of the processed material, change the mass transfer and heat transfer process of the processed material, and then refine the crystal grains, improve the composition of the metal melt, make the composition of the metal melt more uniform, and improve the performance of the workpiece.

[0057] Figure 7 The single yoke double tuning electromagnet includes a yoke 116, an electromagnet pole head 117, and an adjusting handle (not shown) 118. The yoke 116 has two through holes in the middle and is connected to the nozzle 19 by screws between the heat sink 112 and the heating block 16. The electromagnet pole head can be adjusted by the adjusting handle 118 to change the air gap. Under the excitation of the excitation power supply, a closed loop magnetic field is formed, and a uniform strong magnetic field can be generated between the two poles, and the magnetic field direction is along the pole head axis.

[0058] The electromagnetic stirring device acts on the workpiece placed in the middle position of the workbench. The position of the magnetic yoke in the electromagnetic stirring device is adjusted according to the size of the workpiece. The specific adjustment process is as follows:

[0059] S1, calculate the electromagnetic force density of the metal solution: the electromagnetic force density of the metal solution is = , J is the electromagnetic density, B is the magnetic induction intensity; wherein the magnetic induction intensity is B=N×I / Le, N is the number of turns of the excitation coil, I is the excitation current, and Le is the effective magnetic path length of the workpiece. According to the inverse square law, the strength of the magnetic field decreases with the increase of the distance, and is inversely proportional to the square of the distance from the magnetic field source. Therefore, it is necessary to adjust the electromagnetic stirring device to the appropriate distance according to the size of the workpiece processing.

[0060] S2, calculate the effective magnetic path length: measure the distance L from the workpiece to the magnetic yoke around the electromagnetic stirring device by using the reflected energy method, and then calculate the effective magnetic path length according to the formula Le=πL;

[0061] S3, the sensor monitors the strength of the electromagnetic force, transmits the signal to the servo motor driving the magnetic yoke to move, and makes the magnetic yoke controlled by the servo motor to move forward or backward, and finally moves the magnetic yoke in the electromagnetic stirring device to the appropriate position; in the specific implementation process, the magnetic yoke evenly distributed in the electromagnetic stirring device is driven by the servo motor, the feedback position is controlled by the sensor to monitor the strength of the electromagnetic force, the signal is transmitted to the servo motor, and the magnetic yoke is controlled by the servo motor to move forward or backward, and finally the magnetic yoke in the electromagnetic stirring device is moved to the appropriate position.

[0062] Figure 8The schematic diagram of the screw lifting mechanism is shown, which includes four screws 41, four lifters 42, three connecting rods 43, three transmission mechanisms 44, a driving motor 45 and four screw nuts 46. The screw 41 is connected with the lifter 42 through the screw nut 46 to form a set of screw lifting mechanism, and there are four sets of screw lifting mechanisms in total, which are located at four corners respectively. The adjacent two sets of lifters are connected through the connecting rod 43, and the transmission mechanism 44 is connected in the middle of the connecting rod 43. In order to realize the simultaneous lifting of the four sets of screw lifting mechanisms, three transmission mechanisms 44 are used to connect the four sets of screw lifting mechanisms with each other. The screw lifting mechanisms connected by the connecting rods 43 on both sides are connected with the middle transmission mechanism through the transmission mechanisms on the connecting rods, and the middle transmission mechanism is connected with the driving motor 45 to realize the simultaneous lifting of the four sets of screw lifting mechanisms. The upper slide plate provided with the electromagnetic stirring device 3 is fixed with the screw nut 46, and the simultaneous lifting of the four sets of screw lifting mechanisms is driven by the driving motor 45 to realize the lifting of the electromagnetic stirring device 3 in the vertical direction.

[0063] Figure 9 The schematic diagram of the work platform is shown, which includes a thin plate carrier 51, an automatic lifting mechanism 52, a thick plate carrier 53 and a magnet 54. The automatic lifting mechanism 52 is installed at the four corners below the thick plate carrier 53 (which can be driven by a motor or a hydraulic machine), and the thin plate carrier 51 is adsorbed on the thick plate carrier 53 by the magnet 54. After the workpiece is printed, the electromagnetic stirring device 3 is lowered to the lowest position, the carrier is lifted to a position suitable for taking out the workpiece, the workpiece is taken out together with the thin plate carrier 51, and then a new thin plate carrier is placed for printing the next workpiece, which is convenient for taking and placing the workpiece and does not affect the production of the next workpiece.

[0064] The working process of the present application is further described as follows:

[0065] When working, the nozzle device is arranged on the two light poles of the X axis, the slider is connected to the light pole of the X axis to slide, the atmosphere auxiliary device is arranged on the nozzle device, the flow rate of the metal solution is adjusted by changing the pressure of the added atmosphere, and the composition of the metal solution is adjusted by inputting the high-temperature and high-pressure atmosphere to the printing nozzle. The single-yoke double-adjusting electromagnetic iron structure at the nozzle is fixed on the nozzle device through the L-shaped structure of the yoke iron on the two sides through screws. When the metal powder enters the Teflon pipe in the nozzle from the material guide pipe, the high-temperature and high-pressure atmosphere input from the outside contacts the metal powder led out from the material guide pipe and applies pressure, so that the metal powder enters the nozzle and is heated to start melting and extrusion through the electromagnetic induction heating coil. The input high-temperature and high-pressure atmosphere is output by the four ceramic gas outlet pipes around the nozzle and directly acts on the metal molten liquid extruded from the nozzle and plays a protection role. The rack is controlled by the transmission in the three orthogonal directions of XYZ to control the printing process and adjust the position of the working platform. The screw rod lifting mechanism is connected to the lower slide plate through four screws, the upper slide plate is fixedly connected to the four groups of screw rod lifting mechanisms at the four corners through screw nuts, the screw rod lifting mechanism is driven by the bottom motor to make the upper slide plate on which the electromagnetic stirring device is arranged vertically ascend and descend, so that the upper slide plate on which the electromagnetic stirring device is arranged gradually ascends according to the height of the printed workpiece, and the electromagnetic stirring device always acts on the workpiece. The magnetic field of the electromagnetic stirring device can generate an electromagnetic force in the circumferential direction, the electromagnetic force can promote the flow of the melt of the processed material, change the mass transfer and heat transfer process of the processed material, and then refine the crystal grains, improve the composition of the metal molten liquid, make the composition of the metal molten liquid more uniform, and improve the performance of the workpiece. The automatic lifting mechanism is also arranged below the thick plate carrier, and when the workpiece printing is completed, the automatic lifting mechanism of the thick plate carrier cooperates with the screw rod lifting mechanism on which the electromagnetic stirring device is arranged to work, the lifting device ascends to a position higher than the electromagnetic stirring device, and the screw rod lifting mechanism descends to the lowest position. At this time, a thin plate carrier is fixed on the four corners of the upper side through a magnet, the workpiece is printed on the thin plate carrier, and the workpiece is conveniently taken down after printing, and the whole printing process is completed.

[0066] The above-described embodiments are only used to describe the preferred embodiments of the present application, and are not used to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. An apparatus for 3D printing of metal parts with atmosphere and electromagnetic assistance, characterized in that: It includes nozzle device, work platform, screw rod lifting mechanism, electromagnetic stirring device and rack, The rack includes horizontal frame, vertical frame, Z-axis screw rod, Y-axis light pole, X-axis light pole, Z-axis light pole and bottom plate, the vertical frame is arranged vertically with the horizontal frame, the horizontal frame is rectangular frame, the vertical frame is door type frame, Y-axis light pole is arranged in the horizontal frame along Y-axis direction, Z-axis screw rod and Z-axis light pole are arranged on both sides of the vertical frame respectively, and X-axis light pole is arranged in the vertical frame and is in sliding connection with Z-axis screw rod and Z-axis light pole; The work platform includes object table and sliding plate, the sliding plate includes plate-shaped upper sliding plate and lower sliding plate, a group of screw rod lifters is fixed at each corner of the lower sliding plate, the object table is in the middle position of the electromagnetic stirring device and is fixed on the lower sliding plate, the work platform is arranged on the Y-axis light pole by means of the lower sliding plate and slides along the Y-axis light pole, the screw rod lifting mechanism is installed on the work platform and connected with the lower sliding plate, the upper sliding plate is fixedly connected with the four groups of screw rod lifters at the four corners through screw rod nuts, and the upper sliding plate with the electromagnetic stirring device is driven by the bottom motor to make vertical lifting; The nozzle device is arranged on the X-axis light pole by means of the sliding block and slides along the X-axis light pole, the nozzle device includes nozzle assembly, single-yoke double-tuning electromagnet, nozzle fixing cover and nozzle fixing block, the nozzle assembly is arranged on the nozzle fixing block by means of the nozzle fixing cover, and the nozzle fixing block is connected with the sliding block; the nozzle assembly includes throat pipe, heating block, cooling fin, electromagnetic induction heating coil, nozzle, air inlet channel and air outlet pipe, the nozzles are arranged in pairs, and the single-yoke double-tuning electromagnet is fixed on the nozzle assembly by L-shaped structure of two side yokes; The throat pipe includes first section throat pipe and second section throat pipe, the first section throat pipe is a material guide pipe, and the second section throat pipe extends to the inside of the heating block; the second section throat pipe is connected with the nozzles, air inlet channels are arranged on the two inclined edges of the heating block for inputting high-temperature and high-pressure atmosphere, the lower part of the second section throat pipe and the upper part of the nozzles are connected with the air inlet channels respectively, the electromagnetic induction heating coil is arranged on the heating block, two air outlet pipes are arranged outside each nozzle, metal powder enters the nozzles from the material guide pipe and is heated to start melting and extrusion by the electromagnetic induction heating coil, the high-temperature and high-pressure atmosphere input by the air inlet channels contacts the metal powder discharged from the material guide pipe and applies pressure to assist the metal powder to enter the nozzles, and the high-temperature and high-pressure atmosphere discharged from the air outlet pipes protects the metal molten liquid extruded from the nozzles and adjusts the flow rate and composition of the metal molten liquid. The electromagnetic stirring device is arranged on the upper slide plate of the work platform; the electromagnetic stirring device comprises a magnetic yoke, a coil, a magnetic core, a magnetic yoke back body and an adjusting nut, six magnetic yokes are arranged at the circumference of the magnetic yoke back body, the outer surface of each magnetic yoke is wound with a coil, the coil is connected with a power supply, one magnetic core is connected behind each magnetic yoke, the magnetic yoke back body is in the shape of a ring, the magnetic yokes are uniformly arranged on the inner side of the magnetic yoke back body and extend towards the center of the magnetic yoke back body, the magnetic yoke and the magnetic yoke back body form an E-shaped structure; the adjusting nut is mounted on the magnetic core and used for adjusting the distance between the magnetic yoke and the magnetic yoke back body, a processing area is formed in the center area of the magnetic yoke back body, the center area of the electromagnetic stirring device forms a processing area and is provided with a worktable, the processed material is placed in the worktable, when the power supply provides alternating current for the coil, the current flowing through the coil makes the magnetic yoke generate a magnetic field, the magnetic field generates an electromagnetic force in the circumferential direction, the electromagnetic force can promote the flow of the processed material melt, and the mass transfer and heat transfer process of the processed material are changed; The electromagnetic stirring device acts on the workpiece arranged in the middle position of the worktable, the position of the magnetic yoke in the electromagnetic stirring device is adjusted according to the size of the workpiece, and the specific adjustment process is as follows: S1, calculate effective magnetic path length: using the reflected energy method to measure the distance from the workpiece to the magnetic yoke around the electromagnetic stirring device L , and according to the formula Le = πL , the effective magnetic path length is calculated S2, calculating the electromagnetic force density suffered by the metal solution: the electromagnetic force density suffered by the metal solution is = , J is the electromagnetic density, B is the magnetic induction intensity; wherein the magnetic induction intensity is B = N × I / Le , N is the number of turns of the excitation coil, I is the excitation current, Le is the effective magnetic path length of the workpiece; S3, the sensor monitors the strength of the electromagnetic force, transmits the signal to the servo motor driving the magnetic yoke to move, and the magnetic yoke is controlled by the servo motor to move forward or backward, so that the magnetic yoke in the electromagnetic stirring device is finally moved to the appropriate position; The screw rod lifting mechanism comprises four screw rods, four elevators, three connecting rods, three transmission mechanisms, a driving motor and four screw rod nuts; wherein the screw rod is connected with the elevator through the screw rod nut to form a group of screw rod elevators, the screw rod lifting mechanism is formed by four groups of screw rod elevators, the four groups of screw rod elevators are fixed at the four corners of the lower slide plate, each group of screw rod elevators is connected by a connecting rod, and the four groups of screw rod elevators are simultaneously lifted through the connecting transmission mechanism, the upper slide plate provided with the electromagnetic stirring device and the screw rod nut are fixed, and the four groups of screw rod elevators are simultaneously lifted by the driving motor to realize the lifting of the electromagnetic stirring device in the vertical direction. The worktable comprises a thin plate worktable, an automatic lifting mechanism, a thick plate worktable and a magnet, and the lifting mechanism is installed at the lower four corners of the thick plate worktable. The thin plate worktable is adsorbed above the thick plate worktable by the magnet, after the workpiece is completed, the electromagnetic stirring device is lowered to the lowest position, the worktable is raised, the workpiece is taken away from the thin plate worktable, and the next thin plate worktable is replaced.

2. The apparatus according to claim 1, wherein: The material guide pipe is wrapped with the heat dissipation fins.

3. The apparatus according to claim 1, wherein: The lower slide plate is provided with threaded holes at the four corners, and the lower slide plate is fixedly connected with the Y-axis light rod upper slide block through screws.

4. The apparatus according to claim 1, wherein: The heating block is provided with through holes capable of inserting temperature sensors on both sides, and the temperature sensor feeds back the change of temperature in real time.

5. The apparatus according to claim 1, wherein: The heating block is internally provided with air pressure flow channels, the air pressure flow channels are connected with air inlet channels and air outlet pipes, each of the two nozzles is provided with four air pressure flow channels and four air outlet pipes, the air outlet pipes are equidistantly distributed around the nozzle and are connected with the air pressure flow channels in the heating block through brazing connection; high temperature and high pressure atmosphere is introduced into the metal powder from the air inlet channels to pressurize the metal powder, after the action, the high temperature and high pressure atmosphere flows through the air pressure flow channels and is discharged from the air outlet pipes to act on the molten metal liquid.

6. The apparatus according to claim 1, wherein: The single-yoke double-adjusting electromagnet comprises a yoke, electromagnet pole heads and an adjusting handle.

7. The device for atmosphere and electromagnetic assisted 3D printing of metal parts according to claim 6, characterized in that: The yoke is provided with an L-shaped structure which is fixed on the nozzle device by screws.

8. The apparatus according to claim 1, wherein: Both ends of the sliding block connected with the nozzle device are provided with two through holes corresponding to the light pole of the X shaft.

9. The apparatus according to claim 1, wherein: The nozzle device further comprises an exhaust fan, the exhaust fan is arranged in front of the nozzle and is connected with the nozzle through an exhaust fan fixing seat, the fan fixing seat is an L-shaped structure, the long side of the L-shaped structure is fixed with the exhaust fan, and the short side is connected with the nozzle through a U-shaped opening.

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