3D printing head, 3D printer and 3D printing system

Abstract

Embodiments of the present application provide a 3D printing head, a 3D printer and a 3D printing system, which realize color mixing by driving a magnetic stirrer in a non-contact manner, achieve color mixing, provide more abundant colors, meet more printing requirements, and help improve the printing effect of the 3D printer. The 3D printing head comprises an extrusion mechanism, a heating mechanism, a mixing mechanism and a nozzle. The extrusion mechanism is used to extrude at least two printing materials to the heating mechanism. The heating mechanism comprises at least two heating channels and is used to heat the printing materials in the heating channels to a molten state. The mixing mechanism comprises a mixing body, a magnetic stirrer and a stirring driving assembly. The mixing body is provided with a stirring cavity. The stirring cavity is in communication with the at least two heating channels. The magnetic stirrer is arranged in the stirring cavity. The stirring driving assembly is arranged outside the mixing body and is used to drive the magnetic stirrer to rotate in the stirring cavity by magnetic force. The discharge port of the nozzle is in communication with the stirring cavity.

Description

Technical Field

[0001] This application relates to the field of three-dimensional object printing equipment technology, and more particularly to a 3D print head, a 3D printer, and a 3D printing system. Background Technology

[0002] Fused Deposition Modeling (FDM) 3D printers are 3D printing devices based on FDM technology. They can build three-dimensional objects by heating and melting printing materials and depositing them onto a printing platform along a predetermined path, stacking them layer by layer.

[0003] To meet the demands of multi-color printing, existing 3D printers typically print colored objects by switching between different colors of printing material. For example, if the print head is currently extruding printing material of color A, and you need to switch to printing material of color B, the non-molten printing material of color A needs to be extracted from the feed channel—that is, the portion of the printing material that did not enter the print head heating mechanism. This portion is still solid and can be retrieved for reuse. Then, printing material of color B is fed into the feed channel, and printing material B is continuously extruded from the waste outlet to flush out any remaining printing material of color A inside the print head. Printing material B can then be used to continue printing 3D objects. However, this method has certain limitations; the colors printed are restricted by the printing material, meaning the color selection is limited. Summary of the Invention

[0004] Embodiments of this application provide a 3D print head, a 3D printer, and a 3D printing system that use a non-contact driven magnetic stir bar to mix materials and achieve color mixing, thereby providing richer colors, meeting more printing needs, and helping to improve the printing effect of the 3D printer.

[0005] In a first aspect, this application also provides a 3D printing head, comprising: an extrusion mechanism, a heating mechanism, a mixing mechanism, and a nozzle; the extrusion mechanism is used to extrude at least two printing materials into the heating mechanism; the heating mechanism includes at least two heating channels and is used to heat the printing materials in the heating channels to a molten state; the mixing mechanism includes a mixing body, a magnetic stir bar, and a stirring drive assembly, wherein a stirring chamber is provided inside the mixing body, and the stirring chamber is connected to the at least two heating channels; the magnetic stir bar is disposed inside the stirring chamber; the stirring drive assembly is disposed outside the mixing body and is used to drive the magnetic stir bar to rotate in the stirring chamber by magnetic force; the outlet of the nozzle is connected to the stirring chamber.

[0006] The stirring drive assembly includes a driving component and a magnetic component; wherein the driving component drives the magnetic component to rotate circumferentially along the mixing body, and the magnetic component includes a permanent magnet.

[0007] The magnetic component surrounds the stirring chamber and is symmetrical about the central axis of the stirring chamber.

[0008] The magnetic component further includes a carrier, which is arranged around the mixing body and spaced apart from it. The driving component is driven and connected to the carrier and is used to drive the carrier to rotate around the mixing body. The permanent magnet is installed on the side of the carrier facing the mixing body and can rotate around the mixing body under the drive of the carrier.

[0009] The driving component includes a stator core and a stator coil, the stator coil being wound around the stator core, and the magnetic component being located within the region formed by the stator core. The driving component is used to generate a changing magnetic field within the region formed by the stator core to drive the magnetic component to rotate.

[0010] The driving component includes a motor and a transmission mechanism. The motor is connected to the magnetic component through the transmission mechanism. The transmission mechanism includes gears or a combination of gears and a conveyor belt.

[0011] The stirring drive assembly includes a motor stator, which generates a rotating magnetic field to drive the magnetic stir bar to rotate within the stirring chamber.

[0012] The motor stator includes at least three pole shoes.

[0013] Wherein, the magnetic induction intensity B generated by the stirring drive component relative to the stirring chamber is greater than or equal to 0.13 Tesla, or, Where η is the viscosity of the printing material when it melts in the heating channel, r is the radius of the magnetic stir bar, ω is the angular velocity of the magnetic stir bar, μ0 is the vacuum permeability, R is the radius of the stirring chamber, and B r The residual magnetic induction intensity of the magnetic stir bar.

[0014] Wherein, the magnetic direction of the magnetic stir bar is not at an angle of 0 to the rotation axis of the stirring drive assembly.

[0015] The magnetic stir bar is a multipole magnet.

[0016] The magnetic stir bar has a cross-section, and the ratio of the outer diameter of the cross-section to the inner diameter of the stirring chamber is greater than 0.6.

[0017] The magnetic stir bar is made of a high-temperature resistant permanent magnet material.

[0018] The magnetic stir bar is made of a magnetically conductive material, and its cross-section has a maximum of four axes of symmetry.

[0019] Secondly, this application also provides a 3D printer, including a frame, a printing platform, a control mechanism, and a 3D printing head as described in any of the preceding claims, wherein the printing platform and the 3D printing head are both mounted on the frame, the 3D printing head is located on the upper side of the printing platform, and the control mechanism is used to control the relative displacement between the printing platform and the 3D printing head.

[0020] Thirdly, this application also provides a 3D printing system, including a feeding device and a 3D printer as described above, wherein the feeding device is used to supply the printing material to the 3D printer.

[0021] The 3D printer head provided in this application includes a mixing mechanism. A magnetic stirrer is disposed inside the mixing body of the mixing mechanism, and a stirring drive assembly is disposed outside the mixing body. The stirring drive assembly can magnetically drive the magnetic stirrer to rotate within the mixing chamber, thereby achieving homogenization of the molten printing material within the mixing chamber. This configuration utilizes a non-contact driving stirrer for mixing, meeting the demand for more printing colors. Furthermore, compared to a contact-driven stirrer structure, the mixing chamber space can be reduced, thereby decreasing the flushing volume and flushing time required for material replacement, thus contributing to improved printing efficiency of the 3D printer. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a 3D printing system provided in an embodiment of this application;

[0023] Figure 2 yes Figure 1 A partial structural diagram of the 3D print head in the first embodiment of the 3D printer shown;

[0024] Figure 3 yes Figure 2 The diagram shows the structure of the 3D printing head at another angle.

[0025] Figure 4 yes Figure 2 The diagram shows the cross-sectional structure of the 3D printing head after it is cut open along point AA.

[0026] Figure 5 yes Figure 4 The diagram shows the structure of the magnetic stir bar in the 3D printing head.

[0027] Figure 6 and Figure 7 yes Figure 5 The diagram shows the structure of the magnetic stir bar in other embodiments;

[0028] Figure 8 yes Figure 1 A partial structural diagram of the 3D printing head in the second embodiment of the 3D printer shown;

[0029] Figure 9 yes Figure 8 The diagram shows the structure of the 3D printing head at another angle.

[0030] Figure 10 yes Figure 8 A schematic diagram showing the change of the magnetic field direction of the rotating magnetic field generated by the motor stator in the 3D printing head over time.

[0031] Figure 11 yes Figure 8 The diagram shows the phase change of the current in the first, second, and third pole shoes of the motor stator in the 3D printing head over time.

[0032] Figure 12 yes Figure 1 A schematic diagram of the structure of the 3D printing head 100a in the third embodiment of the 3D printer 100 shown;

[0033] Figure 13 yes Figure 12 A schematic diagram of the 3D printing head 100a from another angle;

[0034] Figure 14 yes Figure 2 The diagram shows the cross-sectional structure of the 3D printing head after it is cut open along point AA in the fourth embodiment.

[0035] Figure 15 yes Figure 2 The diagram shows the cross-sectional structure of the 3D printing head after it is cut along point AA in the fifth embodiment. Detailed Implementation

[0036] The specific embodiments of this application will now be clearly described in conjunction with the accompanying drawings.

[0037] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a 3D printing system 1000 provided in an embodiment of this application.

[0038] In this embodiment, the 3D printing system 1000 includes a feeding device 200 and a 3D printer 100. The feeding device 200 is connected to the 3D printer 100 and is used to supply printing material to the 3D printer 100. The 3D printer 100 can be an FDM 3D printer. The 3D printer 100 includes a 3D print head 100a, a printing platform 100b, a control mechanism 100d, and a frame 100c. Both the 3D print head 100a and the printing platform 100b are mounted on the frame 100c. The 3D print head 100a is located above the printing platform 100b and is positioned opposite to it. In this embodiment, the control mechanism 100d is mounted on the frame 100c. The control mechanism 100d is used to control the relative displacement between the printing platform 100b and the 3D print head 100a. In one possible implementation, the 3D printing head 100a and the printing platform 100b can be connected to the frame 100c by being mounted on the control mechanism 100d.

[0039] This application solution is applicable to different printing mechanism types, such as CoreXY, H-Bot, gantry, and motion bed type. The CoreXY structure generally involves dual motors coordinating the X and Y axes of the printer, achieving two-dimensional movement of the print head via a belt drive system, while the Z axis typically independently controls the lifting and lowering of the printing platform. The H-Bot structure is similar to CoreXY, but uses a single enclosed belt for synchronous movement of the X and Y axes. The gantry structure employs a fixed beam structure; the X axis is typically supported by rails on the beam, the Y-axis slider can move on the beam, and the Z axis is typically used to adjust the height of the printing platform or print head. The motion bed type design involves the printing platform moving along the Y-axis, and the print head moving along the X and Z axes. Based on the movement mode of any of the above-mentioned printing mechanism types, during a 3D printing task, the control mechanism 100d controls the motion mechanism to move the 3D printing head 100a to the printing position of the printing platform 100b, or to move the printing platform 100b so that the position to be printed on the printing platform 100b is moved to the position of the 3D printing head 100a, or to achieve relative movement between the 3D printing head 100a and the printing platform 100b so that the 3D printing head 100a is located at the printing position of the printing platform 100b. It can be understood that the movement of the 3D printing head 100a and the printing platform 100b can achieve the relative positional relationship between the 3D printing head 100a and the printing platform 100b under various motion commands. During the printing process, the feeding device 200 can provide different colored printing materials to the 3D printer 100 according to the required color, and the 3D printer 100 feeds the printing material into the 3D printing head 100a. The 3D printing head 100a heats printing materials of different colors and, after stirring, extrudes the molten printing material onto the printing platform 100b to create a three-dimensional object. The specific structure of the 3D printing head 100a is described below. The printing material includes thermoplastic materials.

[0040] Please refer to the following: Figure 2 , Figure 3 and Figure 4 , Figure 2 yes Figure 1 The diagram shows a partial structural schematic of the 3D printing head 100a in the first embodiment of the 3D printer 100. Figure 3 yes Figure 2 The diagram shown is a structural schematic of the 3D printing head 100a from another angle. Figure 4 yes Figure 2 The diagram shows a cross-sectional structure of the 3D printing head 100a after being cut along line AA. "Cut along line AA" means cutting along the plane containing line AA; similar descriptions in the following text can be understood in the same way.

[0041] In this embodiment, the 3D printing head 100a includes an extrusion mechanism 110, a heating mechanism 120, a mixing mechanism 130, and a nozzle 140. The extrusion mechanism 110 extrudes at least two pieces of printing material into the heating mechanism 120. The heating mechanism 120 includes at least two heating channels 121. Specifically, the extrusion mechanism 110 delivers at least two pieces of printing material to a corresponding heating channel 121. The heating mechanism 120 heats the printing material within the heating channel 121 to a molten state. The printing material within at least two heating channels 121 has a different color.

[0042] In this embodiment, the mixing mechanism 130 includes a mixing body 10, a magnetic stirrer 20, and a stirring drive assembly 30. The mixing body 10 contains a stirring chamber 11. The stirring chamber 11 communicates with at least two heating channels 121 of the heating mechanism 120, allowing molten printing material in the heating channels 121 to flow into the stirring chamber 11. The mixing mechanism 130 is connected to the heating mechanism 120. The mixing body 10 is connected to the bottom end of the heating mechanism 120, or it can be located at the end of the heating mechanism 120 where the molten printing material flows out. The mixing mechanism 130 can be detachably connected to the heating mechanism 120 or indirectly connected to the end of the heating mechanism 120 where the molten printing material flows out. The magnetic stirrer 20 is located inside the stirring chamber 11. The stirring drive assembly 30 is located outside the mixing body 10 and is used to drive the magnetic stirrer 20 to rotate within the stirring chamber 11 using magnetic force.

[0043] The nozzle 140 is provided with a discharge port 141, which communicates with the mixing chamber 11. In one feasible embodiment, the nozzle 140 is connected to the end of the mixing body 10 away from the heating mechanism 120. The nozzle 140 and the mixing body 10 can be integrally formed or detachably connected. Specifically, the discharge port 141 extends through the nozzle 140 along its axial direction, forming a flow channel within the nozzle, which communicates with the mixing chamber 11. The axial direction of the nozzle 140 is the direction in which its central axis extends. In this configuration, the nozzle 140 extends from the discharge port 141 towards the mixing body 10 and connects to the flow channel formed by the mixing body 10, thus forming part of the mixing chamber 11.

[0044] It is understood that by providing a magnetic stirrer 20 inside the mixing body 10 and a stirring drive assembly 30 outside the mixing body 10, the stirring drive assembly 30 can drive the magnetic stirrer 20 to rotate in the mixing chamber 11 via magnetic force, thereby mixing the molten printing material in the mixing chamber 11. In this configuration, mixing is performed by non-contact driving the magnetic stirrer 20, meeting the demand for more printing colors. Furthermore, compared to providing a contact drive in the mixing chamber 11, the non-contact drive provided in this embodiment simplifies the structure within the mixing chamber 11, avoiding excessively large mixing chamber 11 leading to large flushing volume and excessively long flushing time, thus helping to improve the printing efficiency of the 3D printer. On the other hand, the mixing mechanism 130 is located between the heating mechanism 120 and the discharge port 141, which can minimize the surface area of ​​the region where color changes occur, thereby reducing the flushing volume required during material change. Furthermore, compared to providing a contact drive in the mixing chamber 11, the non-contact drive provided in this application embodiment can avoid the need to open holes in the mixing chamber 11 for the contact drive, thereby avoiding the problem of material leakage to the outside of the mixing chamber 11 caused by the holes.

[0045] Furthermore, the outer peripheral surface of the magnetic stir bar 20 includes a bottom surface 21, a top surface 22, and a peripheral side surface 23. Along the axial direction of the magnetic stir bar 20, the top surface 22 is the side closest to the heating mechanism 120, and the bottom surface 21 is the side closest to the discharge port 141. The peripheral side surface 23 connects the top surface 22 and the bottom surface 21. The axial direction of the magnetic stir bar 20 is the direction in which its central axis extends. Exemplarily, the cross-section of the stirring chamber 11 is circular. The cross-section of the stirring chamber 11 refers to the section perpendicular to the central axis of the mixing body 10. In some other embodiments, the cross-section of the stirring chamber 11 may also be a regular polygon. The embodiments of this application do not limit this.

[0046] Please refer to the following: Figure 4 , Figure 5 , Figure 6 and Figure 7 , Figure 5 yes Figure 4 The diagram shows the structure of the magnetic stir bar 20 in the 3D printing head 100a. Figure 6 and Figure 7 yes Figure 5 The magnetic stir bar 20 shown is a structural schematic diagram in other embodiments.

[0047] In this embodiment, the cross-sectional shape of the magnetic stir bar 20 can be circular, square, or rectangular, or other polygonal shapes. The ratio of the circumscribed circle diameter of the cross-section of the magnetic stir bar 20 to the inner diameter of the stirring chamber 11 is greater than 0.6. For example, the ratio is greater than 0.65. It should be noted that the cross-section of the magnetic stir bar 20 refers to the section perpendicular to its central axis.

[0048] It should be understood that the smaller the ratio of the outer diameter of the cross-section of the magnetic stir bar 20 to the inner diameter of the stirring chamber 11, the smaller the shear strain exerted by the magnetic stir bar 20 on the molten printing material between the magnetic stir bar 20 and the chamber wall of the stirring chamber 11 when the magnetic stir bar 20 rotates once. In this case, the stirring effect of the magnetic stir bar 20 deteriorates. However, because the shear strain on the molten printing material between the magnetic stir bar 20 and the chamber wall of the stirring chamber 11 decreases, the torque required for the magnetic stir bar 20 to stir the molten printing material also decreases. Therefore, under the same magnetic force, the rotational speed of the magnetic stir bar 20 increases, thereby increasing the shear strain on the molten printing material between the magnetic stir bar 20 and the chamber wall of the stirring chamber 11, ensuring a good stirring effect. By ensuring that the ratio of the outer diameter of the cross-section of the magnetic stir bar 20 to the inner diameter of the stirring chamber 11 is greater than 0.6, the rotation speed of the magnetic stir bar 20 is kept high to compensate for the shear strain generated by the magnetic stir bar 20 on the molten printing material. This ensures that the shear strain generated by the magnetic stir bar 20 on the molten printing material is large, thereby ensuring that the stirring effect of the magnetic stir bar 20 is good.

[0049] In this embodiment, the magnetic stir bar 20 is made of a high-temperature resistant permanent magnet material. For example, the material of the magnetic stir bar 20 includes at least one of neodymium iron boron magnets, samarium cobalt magnets, alnico magnets, or iron-chromium-cobalt magnets. "High-temperature resistant permanent magnet material" means that the permanent magnet material can withstand temperatures higher than the temperature of the molten printing material. This prevents the magnetic stir bar 20 made of permanent magnet material from demagnetizing, oxidizing, or structurally damaging due to high temperatures when stirring and mixing the molten printing material, thus ensuring that the magnetic stir bar 20 has good durability and reliability. For example, the Curie temperature of the permanent magnet material is greater than or equal to 250°C.

[0050] In some other embodiments, the magnetic stir bar 20 is made of a magnetically conductive material. In this case, the cross-section of the magnetic stir bar 20 has up to four axes of symmetry. For example, the cross-section of the magnetic stir bar 20 can be a non-circular shape such as a square, rectangle, or gourd. Figure 6As shown, the magnetic stir bar 20 has a roughly rectangular cross-section and two axes of symmetry. When the magnetic stir bar 20 is made of a magnetically conductive material, its outer peripheral surface includes a magnetoresistive surface 24. The magnetoresistive surface 24 is intersecting the cross-section of the magnetic stir bar 20. In the magnetic field generated by the stirring drive assembly 30, when the magnetoresistive surface 24 is not parallel to the magnetic field direction, the magnetic reluctance of the magnetic circuit increases, thereby generating a magnetic reluctance torque. This allows the magnetic stir bar 20 to rotate along its central axis following the magnetic field when the external magnetic field rotates. For example, there are two magnetoresistive surfaces 24. The two magnetoresistive surfaces 24 are arranged opposite each other. It is understood that the magnetically conductive material itself is not magnetic. By providing magnetoresistive surfaces 24 on the peripheral surface of the magnetic stir bar 20 made of the magnetically conductive material, the radial magnetic reluctance of the magnetic stir bar 20 can change as the magnetic stir bar 20 rotates. This allows the magnetic stir bar 20 made of the magnetically conductive material to rotate under the magnetic force of the stirring drive assembly 30, thereby mixing the molten printing material in the stirring chamber 11.

[0051] In other embodiments, the magnetic stir bar 20 is made of both magnetically conductive and non-magnetically conductive materials. That is, the magnetic stir bar 20 is made of both magnetically conductive and non-magnetically conductive materials. This can also be understood as... Figure 7 As shown, the magnetic stir bar 20 includes a stirring body 20a and a stirring auxiliary body 20b. The stirring body 20a is made of a magnetically conductive material. The peripheral surface of the stirring body 20a includes a magnetoresistive surface 24, which intersects with the cross-section of the stirring body 20a. The stirring auxiliary body 20b is made of a non-magnetically conductive material and is mounted on the magnetoresistive surface 24 of the stirring body 20a. This configuration ensures that the magnetic stir bar 20, composed of the stirring body 20a and the stirring auxiliary body 20b, has a larger cross-sectional area than the stirring body 20a made of magnetically conductive material, thereby improving the mixing effect of the magnetic stir bar 20.

[0052] In this embodiment, the magnetic stir bar 20 is a pair of magnetic poles. That is, the magnetic stir bar 20 has a pair of magnetic poles. It is understood that the equivalent air gap between the magnetic stir bar 20 and the stirring drive assembly 30 is relatively large. The magnetic stir bar 20 being a pair of magnetic poles can adapt to the large air gap conditions, ensuring that the magnetic stir bar 20 can generate torque and rotate under the magnetic drive of the stirring drive assembly 30. In other embodiments, the magnetic stir bar 20 may also be a multi-pole magnet. That is, the magnetic stir bar 20 has multiple pairs of magnetic poles.

[0053] Please refer to it again. Figures 2 to 4The stirring drive assembly 30 is disposed around the stirring chamber 11 and is symmetrical about the central axis of the stirring chamber 11. It is understood that this symmetry includes central symmetry about the central axis of the stirring chamber 11. In some other embodiments, the stirring drive assembly 30 may not be symmetrical about the central axis of the stirring chamber 11, and the embodiments of this application do not impose any limitations on this.

[0054] In this embodiment, the magnetic induction intensity B generated by the stirring drive assembly 30 relative to the stirring chamber 11 is greater than or equal to 0.13 Tesla, or the magnetic induction intensity B generated by the stirring drive assembly 30 relative to the stirring chamber 11 is:

[0055]

[0056] In this configuration, the stirring drive assembly 30 can magnetically drive the magnetic stir bar 20, thereby mixing the molten printing material within the stirring chamber 11. Simultaneously, the stirring drive assembly 30 possesses strong magnetism, generating a stronger magnetic field relative to the magnetic stir bar 20. This increases the rotational torque of the magnetic stir bar 20, enabling it to rotate at high speed. This improves the color mixing uniformity of the molten printing material of different colors within the stirring chamber 11, thus enhancing the printing effect of the 3D printer 100.

[0057] The following explains the calculation process for the magnetic induction intensity B generated by the stirring drive assembly 30 relative to the stirring chamber 11:

[0058] First, a magnetic stirrer 20 with radius r and length l experiences a torque T1 in a given uniform magnetic field B, which is:

[0059]

[0060] Where B is the magnetic induction intensity generated by the stirring drive component 30 relative to the stirring chamber 11, and M is the magnetic moment of the permanent magnet. r denoted as the remanent magnetic induction intensity of the magnetic stir bar 20, and μ0 as the vacuum permeability.

[0061] Secondly, according to fluid mechanics, in a cylindrical cavity of radius R filled with a Newtonian fluid, when a cylindrical magnetic stir bar 20 of radius r and length l rotates in the cylindrical cavity, the viscous torque T2 experienced by the magnetic stir bar 20 is:

[0062]

[0063] Where η is the viscosity of the printing material when it melts in the heating channel 121, and ω is the angular velocity of the magnetic stir bar 20.

[0064] By equaling formula (1) and formula (2), the magnetic induction intensity B generated by the stirring drive component 30 relative to the stirring chamber 11 can be calculated as follows:

[0065]

[0066] For example, when the inner diameter r of the stirring chamber 11 is 7 mm, the height l is 6 mm, and the diameter of the magnetic stir bar 20 is 6 mm, the angular velocity of the magnetic stir bar 20 needs to reach approximately 8 rpm to achieve a good mixing effect. In the actual experiment, the viscosity of the molten PLA (Polylactic Acid) printing material is approximately 250 Pa·s, and the remanent magnetic induction intensity Br of the N52 grade permanent magnet used is approximately 1.5 Tesla. Substituting the above data into formula (3), we can obtain that the magnetic induction intensity B generated by the stirring drive component 30 relative to the stirring chamber 11 is greater than or equal to 0.13 Tesla.

[0067] In this embodiment, the stirring drive assembly 30 includes a driving component 31 and a magnetic component 32. The driving component 31 drives the magnetic component 32 to rotate circumferentially along the mixing body 10. The magnetic component 32 is disposed around the mixing body 10 and spaced apart from it. That is, the magnetic component 32 is disposed around the stirring chamber 11. The magnetic component 32 is centrally symmetrical about the central axis of the stirring chamber 11. In some other embodiments, the magnetic component 32 may not be centrally symmetrical about the central axis of the stirring chamber 11.

[0068] In this embodiment, the magnetic component 32 includes a carrier 321 and a permanent magnet 322. The carrier 321 is disposed around the mixing body 10 and spaced apart from it. The driving component 31 is driven and connected to the carrier 321 and is used to drive the carrier 321 to rotate around the mixing body 10. The permanent magnet 322 is installed on the side of the carrier 321 facing the mixing body 10 and can rotate around the mixing body 10 under the drive of the carrier 321. The permanent magnet 322 is used to drive the magnetic stirrer 20 to rotate. The carrier 321 can be connected to the heating mechanism 120.

[0069] Furthermore, the permanent magnet 322 exerts an axial restoring force on the magnetic stirrer 20, causing it to tend to return to its equilibrium position when it deviates from the axial magnetic equilibrium position. It should be understood that during the rotation of the magnetic stirrer 20 within the stirring chamber 11 driven by the permanent magnet 322, when the molten printing material is extruded into the outlet 141 of the nozzle 140, the magnetic stirrer 20 experiences a downward extrusion force, causing it to deviate from its axial magnetic equilibrium position. When retraction occurs during printing or the printing material extrusion pauses, the magnetic stirrer 20 is restored to its axial magnetic equilibrium position by the axial restoring force of the permanent magnet 322. This configuration effectively retracts the molten printing material, preventing leakage and stringing during printing.

[0070] In this embodiment, there are two permanent magnets 322. The two permanent magnets 322 are arranged at intervals around the mixing body 10. The magnetism of the end of one permanent magnet 322 facing the magnetic stirrer 20 is opposite to the magnetism of the end of the other permanent magnet 322 facing the magnetic stirrer 20. This arrangement allows the overall magnetic circuit of the two permanent magnets 322 to be closed, thereby enhancing the magnetic field strength. When the permanent magnets 322 drive the magnetic stirrer 20 to rotate, the magnetic stirrer 20 has efficient stirring power, which enables uniform mixing of different colors of molten printing material in the mixing chamber 11, thus helping to improve the printing effect of the 3D printer 100. Furthermore, the implementation using permanent magnets can generate a stronger rotational torque on the magnetic stirrer 20.

[0071] In some other embodiments, there may be multiple permanent magnets 322. These multiple permanent magnets 322 are divided into multiple first permanent magnets and multiple second permanent magnets. The multiple first permanent magnets are arranged around the mixing body 10. The multiple second permanent magnets are all located on one side of the multiple first permanent magnets and are arranged around the mixing body 10. The multiple first permanent magnets are joined to form a first magnet group, and the multiple second permanent magnets are joined to form a second magnet group. This arrangement allows the magnetization direction of the multiple permanent magnets 322 to be radially distributed, which helps to further enhance the drag torque of the permanent magnets 322 on the magnetic stir bar 20, further improve the stirring power of the magnetic stir bar 20, make the mixing of different colored molten printing materials more uniform, and further improve the printing effect of the 3D printer 100.

[0072] In this embodiment, the driving component 31 is connected to the magnetic component 32 and drives the magnetic component 32 to rotate circumferentially around the mixing body 10. Specifically, the driving component 31 is connected to the carrier 321 and drives the carrier 321 to rotate around the mixing body 10, thereby enabling the permanent magnet 322 to rotate around the mixing body 10.

[0073] In this embodiment, the driving component 31 includes a motor 31a and a transmission mechanism 31b. The motor 31a is connected to the magnetic component 32 via the transmission mechanism 31b. In this embodiment, the transmission mechanism 31b includes a combination of gears and a conveyor belt. Exemplarily, the motor 31a is spaced apart from the mixing body 10. The transmission mechanism 31b includes a first transmission wheel 311, a second transmission wheel 312, and a transmission belt 313. The first transmission wheel 311 is fixedly connected to the carrier 321 and is arranged around the mixing body 10, spaced apart from it. The second transmission wheel 312 is connected to the motor 31a and spaced apart from the first transmission wheel 311. The transmission belt 313 is sleeved on the first transmission wheel 311 and the second transmission wheel 312. When the motor 31a drives the second transmission wheel 312 to rotate, the second transmission wheel 312 drives the first transmission wheel 311 to rotate relative to the mixing body 10 via the transmission belt 313. At this time, the first transmission wheel 311 drives the carrier 321 to rotate relative to the mixing body 10, thereby driving the permanent magnet 322 to rotate relative to the mixing body 10, and thus driving the magnetic stir bar 20 to rotate in the mixing chamber 11.

[0074] In some other embodiments, the transmission mechanism 31b may also consist only of gears. For example, the transmission mechanism 31b may consist only of a first transmission wheel 311 and a second transmission wheel 312. The first transmission wheel 311 and the second transmission wheel 312 are meshed together. When the motor 31a drives the second transmission wheel 312 to rotate, the second transmission wheel 312, through gear meshing, drives the first transmission wheel 311 to rotate relative to the mixing body 10, thereby driving the carrier 321 to rotate relative to the mixing body 10, and further driving the permanent magnet 322 to rotate relative to the mixing body 10, thus driving the magnetic stir bar 20 to rotate within the mixing chamber 11.

[0075] Furthermore, in this embodiment, the angle between the rotation axis of the stirring drive assembly 30 and the magnetic direction of the magnetic stir bar 20 is not zero. The rotation axis of the stirring drive assembly 30 refers to the axis passing through the central axis of the stirring chamber 11. Specifically, the angle between the rotation axis of the magnetic component 32 and the magnetic direction of the magnetic stir bar 20 is not zero. This arrangement ensures that the magnetic stir bar 20 generates torque about the rotation axis of the stirring drive assembly 30, thereby ensuring that the magnetic stir bar 20 can rotate under the magnetic drive of the stirring drive assembly 30.

[0076] Please refer to the following: Figure 8 , Figure 9 and Figure 10 , Figure 8 yes Figure 1 The diagram shows a partial structural representation of the 3D printing head 100a in the second embodiment of the 3D printer 100. Figure 9 yes Figure 8 The diagram shown is a structural schematic of the 3D printing head 100a from another angle. Figure 10 yes Figure 8 A schematic diagram showing the change of the magnetic field direction of the rotating magnetic field generated by the motor stator 33 in the 3D printing head 100a over time.

[0077] The 3D printing head 100a shown in this embodiment differs from the 3D printing head 100a shown in the first embodiment in that the stirring drive assembly 30 of the 3D printing head 100a includes a motor stator 33. The motor stator 33 is used to generate a rotating magnetic field. The rotating magnetic field is used to drive the magnetic stir bar 20 to rotate within the stirring chamber 11. The direction of the rotating magnetic field changes over time as follows... Figure 10 As shown. The motor stator 33 includes at least three pole shoes 332.

[0078] In one feasible embodiment, the motor stator 33 includes a main body 331 and at least three pole shoes 332. The main body 331 is disposed around the outer periphery of the mixing body 10 and spaced apart from the mixing body 10. The at least three pole shoes 332 are all fixedly connected to the side of the main body 331 facing the mixing body 10, and are disposed around the mixing body 10 and spaced apart from each other to prevent the pole shoes 332 from being damaged by the high temperature of the outer wall of the mixing body 10. Exemplarily, each pole shoe 332 includes a winding portion 3321 and a conductive coil 3322. The winding portion 3321 is fixedly connected to the side of the main body 331 facing the mixing body 10 and spaced apart from the mixing body 10. The conductive coil 3322 is wound around the winding portion 3321.

[0079] Please see Figure 11 , Figure 11 yes Figure 8 The diagram shows the change of current phase over time in the first pole shoe 332a, the second pole shoe 332b, and the third pole shoe 33 of the motor stator 33 in the 3D printing head 100a.

[0080] In this embodiment, at least three pole pieces 332 include a first pole piece 332a, a second pole piece 332b, and a third pole piece 332c. The current phases of the first pole piece 332a, the second pole piece 332b, and the third pole piece 332c are different. For example, as shown... Figure 11 As shown, the current phase of the first pole piece 332a, the current phase of the second pole piece 332b, and the current phase of the third pole piece 332c differ by 120°.

[0081] It is understandable that when alternating currents with different phases are passed through the conductive coils 3322 of the first pole shoe 332a, the second pole shoe 332b, and the third pole shoe 332c, the magnetic fields generated by these three coils form a rotating magnetic field. When the direction of the alternating current changes, the direction of this rotating magnetic field also changes, thereby allowing the magnetic stir bar 20 to rotate within the mixing chamber 11 remotely, achieving uniform mixing of different colors of molten printing material within the mixing chamber 11. In this embodiment, mixing is performed by non-contact driving of the magnetic stir bar 20, meeting the demand for more printing colors. Furthermore, this design also avoids the mixing chamber 11 being too large, resulting in a large flushing volume and excessively long flushing time. Furthermore, by using a magnetic stirrer 20, there is no need to drill holes in the walls of the stirring chamber to achieve a contact-driven connection structure. This avoids the situation where molten printing material in the stirring chamber 11 overflows through the holes, thus enabling the molten printing material to flow out only through the flow channel formed by the stirring chamber 11 and the discharge port 141. At the same time, it avoids the problem of molten printing material remaining in the holes and being difficult to flush out, thereby helping to improve the printing efficiency of the 3D printer.

[0082] Please refer to the following: Figure 12 and Figure 13 , Figure 12 yes Figure 1 The diagram shows the structure of the 3D printing head 100a in the third embodiment of the 3D printer 100. Figure 13 yes Figure 12 The diagram shows the structure of the 3D printing head 100a from another angle.

[0083] The 3D printing head 100a shown in this embodiment differs from the 3D printing head 100a shown in the first embodiment in that the driving component 31 of the 3D printing head 100a includes a stator core 31c and a stator coil 31d, with the stator coil 31d wound around the stator core 31c. In this embodiment, the magnetic component 32 is located within the region formed by the stator core 31c. The driving component 31 is used to generate a changing magnetic field within the region formed by the stator core 31c to drive the magnetic component 32 to rotate.

[0084] In this embodiment, by controlling the direction and magnitude of the current flowing through the stator coil 31d of the driving component 31, the driving component 31 can generate a changing rotating magnetic field. The rotating magnetic field drives the magnetic component 32 to rotate, thereby driving the magnetic stir bar 20 to rotate in the stirring chamber 11 in the air, thereby achieving stirring and uniform color mixing of molten printing materials of different colors in the stirring chamber 11.

[0085] Please see Figure 14 , Figure 14 yes Figure 2 The diagram shows the cross-sectional structure of the 3D printing head 100a after it is cut along point AA in the fourth embodiment.

[0086] The 3D printing head 100a shown in this embodiment differs from the 3D printing head 100a shown in the first embodiment above in that the mixing mechanism 130 further includes a support plate 40. The support plate 40 is located on the side of the magnetic stirrer 20 facing the discharge port 141 of the nozzle 140. In this embodiment, the support plate 40 can be connected to the inner wall of the mixing chamber 11 or the inner wall of the nozzle 140; the embodiments of this application do not impose strict limitations on this.

[0087] The support plate 40 has multiple through holes 41, which penetrate the support plate 40 along its axial direction and are spaced apart from each other, connecting the stirring chamber 11 and the discharge port 141 of the nozzle 140. Furthermore, the through holes 41 prevent the magnetic stir bar 20 from passing through. That is, the diameter of each through hole 41 is smaller than the minimum cross-sectional size of the magnetic stir bar 20 to prevent it from clogging the discharge port 141 of the nozzle 140, thereby ensuring that the 3D printing head 100a can smoothly extrude molten printing material and guaranteeing the reliable operation of the 3D printer 100.

[0088] Understandably, during the stirring process, the high-speed flowing molten printing material exerts an axial force on the magnetic stir bar 20 towards the outlet 141 of the nozzle 140. By setting up the support plate 40, the support plate 40 can support the magnetic stir bar 20, preventing the magnetic stir bar 20 from moving under the action of the axial force and blocking the outlet 141 of the nozzle 140, ensuring that the 3D print head 100a can smoothly extrude the molten printing material, and ensuring the good reliability of the 3D printer 100.

[0089] Please see Figure 15 , Figure 15 yes Figure 2 The diagram shows the cross-sectional structure of the 3D printing head 100a cut along line AA in the fifth embodiment.

[0090] The 3D printing head 100a shown in this embodiment differs from the 3D printing head 100a shown in the first embodiment in that the mixing mechanism 130 further includes a rotating shaft 60 and a fixing member 50. The magnetic stirrer 20 is sleeved on the rotating shaft 60. Specifically, the magnetic stirrer 20 is fixedly connected to the rotating shaft 60 or rotatably connected to the rotating shaft 60. The fixing member 50 is located at the end of the magnetic stirrer 20 facing the discharge port 141 of the nozzle 140, and the outer peripheral surface of the fixing member 50 is connected to the inner wall of the mixing chamber 11. The connection between the outer peripheral surface of the fixing member 50 and the inner wall of the mixing chamber 11 may be partial. In a feasible embodiment, the outer peripheral surface of the fixing member 50 may also be connected to the inner wall of the nozzle 140. Again, the connection between the outer peripheral surface of the fixing member 50 and the inner wall of the nozzle 140 may be partial.

[0091] In this embodiment, one end of the rotating shaft 60 is rotatably connected to the heating mechanism 120, and the other end is rotatably connected to the fixing member 50. With this configuration, the fixing member 50 can both fix the rotating shaft 60 and axially limit the magnetic stir bar 20, preventing the magnetic stir bar 20 from moving under the action of axial force and blocking the discharge port 141 of the nozzle 140, ensuring that the 3D printing head 100a can smoothly extrude the molten material line, and ensuring the good reliability of the 3D printer 100.

[0092] In addition, the fixing member 50 is also provided with a through hole 51, which penetrates the fixing member 50 along the axial direction of the fixing member 50 and is spaced apart from the rotating shaft 60, and communicates with the stirring chamber 11 and the outlet 141 of the nozzle 140. For example, there are multiple through holes 51. Multiple through holes 51 are spaced apart around the rotating shaft 60. In this embodiment, the molten material in the stirring chamber 11 can flow from the through hole 51 of the fixing member 50 to the outlet 141 of the nozzle 140. In this configuration, the magnetic stir bar 20 is fixed in the stirring chamber 11 by the rotating shaft 60, and the rotating shaft 60 and the fixing member 50 are both located in the flow space of the molten printing material, eliminating the need to open holes in the cavity wall of the stirring chamber, thus avoiding the problem that holes can easily cause printing material to leak out of the stirring chamber 11.

[0093] It is understood that the scheme of non-contactly driving the magnetic stir bar 20 in the stirring chamber 11 to rotate by the external magnetic field generated by the stirring drive assembly 30 in this application includes the method in which the magnetic stir bar 20 is not fixedly set in the stirring chamber 11, and also includes the method in which it is fixedly set in the stirring chamber 11.

[0094] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A 3D printing head, characterized in that, include: Extrusion mechanism, heating mechanism, mixing mechanism, and nozzle; The extrusion mechanism is used to extrude at least two strips of printing material into the heating mechanism; The heating mechanism includes at least two heating channels and is used to heat the printing material in the heating channels to a molten state; The mixing mechanism includes a mixing body, a magnetic stirrer, and a stirring drive assembly. The mixing body has a stirring chamber that is connected to the at least two heating channels. The magnetic stirrer is disposed inside the stirring chamber. The stirring drive assembly is disposed outside the mixing body and is used to drive the magnetic stirrer to rotate in the stirring chamber by magnetic force. The nozzle's outlet is connected to the stirring chamber.

2. The 3D printing head according to claim 1, characterized in that, The stirring drive assembly includes a driving component and a magnetic component; wherein, the driving component drives the magnetic component to rotate circumferentially along the mixing body, and the magnetic component includes a permanent magnet.

3. The 3D printing head according to claim 2, characterized in that, The magnetic component surrounds the stirring chamber and is symmetrical about the central axis of the stirring chamber.

4. The 3D printing head according to claim 2, characterized in that, The magnetic component further includes a carrier, which is arranged around the mixing body and spaced apart from it. The driving component is driven to the carrier and is used to drive the carrier to rotate around the mixing body. The permanent magnet is installed on the side of the carrier facing the mixing body, and can rotate around the mixing body under the drive of the carrier.

5. The 3D printing head according to claim 2, characterized in that, The driving component includes a stator core and a stator coil, the stator coil being wound around the stator core, and the magnetic component being located within the region formed by the stator core. The driving component is used to generate a changing magnetic field within the region formed by the stator core to drive the magnetic component to rotate.

6. The 3D printing head according to claim 2, characterized in that, The driving component includes a motor and a transmission mechanism. The motor is connected to the magnetic component through the transmission mechanism. The transmission mechanism includes gears, or a combination of gears and a conveyor belt.

7. The 3D printing head according to claim 1, characterized in that, The stirring drive assembly includes a motor stator, which generates a rotating magnetic field to drive the magnetic stir bar to rotate within the stirring chamber.

8. The 3D printing head according to claim 7, characterized in that, The motor stator includes at least three pole shoes.

9. The 3D printing head according to any one of claims 1 to 8, characterized in that, The magnetic induction intensity B generated by the stirring drive component relative to the stirring chamber is greater than or equal to 0.13 Tesla, or... Where η is the viscosity of the printing material when it melts in the heating channel, r is the radius of the magnetic stir bar, ω is the angular velocity of the magnetic stir bar, μ0 is the vacuum permeability, R is the radius of the stirring chamber, and Br is the remanent magnetic induction of the magnetic stir bar.

10. The 3D printing head according to any one of claims 1 to 8, characterized in that, The magnetic direction of the magnetic stir bar is not at an angle of 0 to the rotation axis of the stirring drive assembly.

11. The 3D printing head according to any one of claims 1 to 8, characterized in that, The magnetic stir bar is a multipole magnet.

12. The 3D printing head according to any one of claims 1 to 8, characterized in that, The magnetic stir bar has a cross-section, and the ratio of the outer diameter of the cross-section to the inner diameter of the stirring chamber is greater than 0.

6.

13. The 3D printing head according to any one of claims 1 to 8, characterized in that, The magnetic stir bar is made of high-temperature resistant permanent magnet material.

14. The 3D printing head according to any one of claims 1 to 8, characterized in that, The magnetic stir bar is made of a magnetically conductive material, and the cross-section of the magnetic stir bar has a maximum of four axes of symmetry.

15. A 3D printer, characterized in that, The device includes a frame, a printing platform, a control mechanism, and a 3D printing head as described in any one of claims 1 to 14, wherein the printing platform and the 3D printing head are both mounted on the frame, the 3D printing head is located on the upper side of the printing platform, and the control mechanism is used to control the relative displacement between the printing platform and the 3D printing head.

16. A 3D printing system, characterized in that, It includes a feeding device and a 3D printer as claimed in claim 15, wherein the feeding device is used to supply the printing material to the 3D printer.

Images