A programmable magnetic light-curing 3D printer

Abstract

A programmable magnetic photocuring 3D printer belongs to the field of 3D printing technology. The present invention is to solve the problems existing in the existing 3D magnetization printing technology. The present invention includes a collaboratively controlled photocuring system and a magnetic programming system, which work alternately. The photocuring system cures the resin layer by layer and in regions according to the pre-designed 3D printed part model. The magnetic programming system is used to discretely magnetize the 3D printed part layer by layer and in regions. The magnetic moment orientation of the magnetic powder in each region of each layer is arranged according to the settings. In the photocuring system, the demolding mechanism and the light source are respectively arranged above and below the transparent material pool at the bottom. The magnetic programming system includes a magnetic head and a translation mechanism. The magnetic head generates a point magnetic field. The translation mechanism drives the magnetic head to scan and magnetize each layer of magnetic slurry in the material pool point by point. The scanning area of each layer is determined by the shape of the preset model. Each layer of the model to be printed is divided into multiple areas to be cured. Each area to be cured is divided into multiple printing points in a grid format, and each printing point is printed one by one.

Description

Technical Field

[0001] The invention belongs to the technical field of 3D printing. Background Art

[0002] Magnetic particles are mixed evenly with a curable liquid material to form a magnetic slurry. Under the influence of an external magnetic field, the magnetic particles in the slurry are magnetized and tend to align in the direction of the magnetic field. Curing technology is then used to solidify the slurry, ultimately encoding the magnetic field within the material. Stereolithography is a widely used 3D printing technology. Currently, photocurable materials can be cured and formed through methods such as ultraviolet lithography, electron beam lithography, and surface projection micro-stereolithography.

[0003] Combining photocuring technology with magnetic programming technology can achieve precise magnetization inside an object, so that the object has magnetism with a preset distribution direction. The produced objects can quickly complete specified actions or fold into different shapes under the control of an external magnetic field. It has application prospects in the fields of bionic robotics and biomedicine.

[0004] Existing photocuring magnetic programming technology usually separates the magnetization process from the photocuring process, using permanent magnets or pulsed magnetic fields for magnetization. This method cannot achieve coordinated control of material magnetization and printing, and can only be used to print objects with simple structures and continuous internal magnetism. It cannot achieve precise, three-dimensional, discrete magnetic programming, and cannot complete magnetic programming 3D printing of complex three-dimensional structures. Although the use of three-dimensional Helmholtz coils can generate a three-dimensional, variable magnetic field and can be coordinated and controlled, due to the special structure of the Helmholtz coil, only a small uniform magnetic field is generated in the center of the coil, and the magnetic field is blocked by the coil around it, which greatly limits the size of the workpiece to be processed, and can only process small-sized workpieces. Summary of the Invention

[0005] In response to the problems existing in the existing 3D magnetization printing technology, the present invention provides a programmable magnetic light-curing 3D printer.

[0006] The programmable magnetic light-curing 3D printer described in the present invention includes a collaboratively controlled light-curing system and a magnetic programming system, which work alternately. The light-curing system cures the resin layer by layer and region by region according to a pre-designed 3D printed part model, while the magnetic programming system is used to discretely magnetize the 3D printed part layer by layer and region by region. The magnetic moment orientation of the magnetic powder in each region of each layer is arranged according to the preset arrangement.

[0007] The light curing system includes a material pool 1, a demoulding mechanism 2 and a light source 4. The demoulding mechanism 2 and the light source 4 are respectively arranged above and below the material pool 1 with a transparent bottom;

[0008] The magnetic programming system includes a magnetic head 3 and a translation mechanism 5. The magnetic head 3 generates a point magnetic field. The translation mechanism 5 drives the magnetic head 3 to scan and magnetize each layer of magnetic slurry in the material pool 1 point by point. The scanning area of each layer is determined by the shape of a preset model.

[0009] Each layer of the model to be printed is divided into multiple areas to be cured. Each area to be cured is divided into multiple printing points using a grid format. Each printing point is printed one by one. The printing and curing process is as follows:

[0010] S1, the translation mechanism 5 drives the magnetic head 3 to move and align with the printing point to be solidified;

[0011] S2, the magnetic head 3 is energized to generate a magnetic field in a preset direction in the area to be solidified, so that the magnetic moment of the magnetic powder in the area to be solidified rotates and aligns with the external magnetic field;

[0012] S3. Turn on the light source to illuminate the printed point to be cured, so that the printed point is cured.

[0013] Preferably, the magnetic head (3) adopts a magnetic tweezers structure, which is composed of m magnetic pole coils wrapped around the centripetal axis, where m is greater than or equal to 3; by inputting currents of specific directions and magnitudes into the different magnetic pole coils, a desired magnetic field of set magnitude and direction is generated at point P, and the printed point to be solidified is magnetized.

[0014] Preferably, a coordinate system is established with the magnetization center as the coordinate origin, the magnetization center as the printing point P to be solidified, and m magnetic pole coils are arranged centripetally around the z axis as the symmetry axis. The magnitude and direction of the magnetic field determine the current flowing into each pole coil;

[0015] When m=4,

[0016] The currents I1 to I4 flowing through the four magnetic pole coils of the magnetic tweezers are:

[0017]

[0018]

[0019]

[0020]

[0021] in,

[0022] B is the desired magnetic field The magnetic field strength;

[0023] k1, k2 are constants related to the head material, structure, and number of coil turns;

[0024] φ is the desired magnetic field The angle between the direction of the magnetic field intensity and the z-axis;

[0025] θ is the desired magnetic field The angle between the projection and the x-axis in the xy plane;

[0026] α is the angle between the line connecting the magnetization center and the tip of a magnetic tweezers and the z-axis.

[0027] Preferably, it further includes a frame 10, on which the ejection mechanism 2, the material pool 1 and the translation mechanism 5 are sequentially mounted from top to bottom.

[0028] Preferably, a scraper 6 is further included, which is arranged in the material pool 1 and reciprocates along the bottom of the material pool 1.

[0029] Preferably, the light source 4 is a laser light source, which is fixed on the magnetic head 3 and moves with the magnetic head 3 .

[0030] Preferably, the light source 4 adopts an LED light source assembly, which includes an LED light source 7, an LCD screen 8 and a condenser 9. The LED light source 7 is arranged on a support plate below the magnetic head 3, and the condenser 9 is arranged around the LED light source 7 for focusing light. The LCD screen 8 is a transparent screen and is arranged as a mask on the lower surface of the bottom plate of the material pool 1 above the magnetic head 3.

[0031] The beneficial effects of the present invention are as follows: The programmable magnetic light-curing 3D printer described herein enables rapid, real-time control of the material's magnetization direction during the 3D printing process, achieving precise, three-dimensional, discrete magnetization control, imparting a predetermined magnetic distribution within the object. Objects printed using this device can achieve specific motion and deformation under the influence of an external magnetic field, enabling the rapid and flexible manufacture of magnetically controlled soft robots with complex structures and diverse functions.

[0032] The magnetizing device of the present invention can generate a preset magnetic field in a small space, and magnetize each area in a scanning manner in cooperation with the translation device, thereby realizing the processing of large-sized and complex-shaped workpieces. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of a programmable magnetic light-curing 3D printer according to the present invention;

[0034] Figure 2 This is a workflow diagram of a programmable magnetic light-curing 3D printer according to the present invention;

[0035] Figure 3 This is a schematic diagram of the 3D printing process, where Figure 3 (a) is a schematic diagram of the workpiece structure to be printed. Figure 3 (b) is a layer B instance, Figure 3 (c) Figure 3 (b) BB section, Figure 3 (d) is printing area a, Figure 3 (e) is printing area b;

[0036] Figure 4 It is a schematic diagram of the magnetic field direction of the magnetic head;

[0037] Figure 5 It is a schematic diagram of two light source designs; Figure 5 (a) is the laser light source, Figure 5 (b) is the LED light source.

[0038] 1. Material pool, 2. Ejection mechanism, 3. Magnetic head, 4. Light source, 5. Translation mechanism, 6. Scraper, 7. LED light source, 8. LCD screen, 9. Spotlight, 10. Stand. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0042] Specific implementation method 1: Figures 1 to 4 This embodiment describes a programmable magnetic light-curing 3D printer comprising a collaboratively controlled light-curing system and a magnetic programming system, which operate alternately. The light-curing system cures resin layer by layer and region by region according to a pre-designed 3D print model, while the magnetic programming system discretely magnetizes the 3D print layer by layer and region by region. The magnetic moment orientation of the magnetic powder in each region of each layer is arranged according to a preset arrangement, allowing the magnetic moment of the magnetic powder in each region of the print to align in any preset direction. Furthermore, the magnetic moment orientations of the magnetic powder in adjacent regions can vary significantly, rather than being continuous. The result is a three-dimensional print.

[0043] See also Figure 1 The light curing system includes a material pool 1, a demoulding mechanism 2 and a light source 4. The demoulding mechanism 2 and the light source 4 are respectively arranged above and below the material pool 1 with a transparent bottom;

[0044] The magnetic programming system includes a magnetic head 3 and a translation mechanism 5. The magnetic head 3 generates a point magnetic field. The translation mechanism 5 drives the magnetic head 3 to scan and magnetize each layer of magnetic slurry in the material pool 1 point by point. The scanning area of each layer is determined by the shape of a preset model.

[0045] Each layer of the model to be printed is divided into multiple areas to be cured. Each area to be cured is divided into multiple printing points using a grid format. Each printing point is printed one by one. The printing and curing process is as follows:

[0046] S1, the translation mechanism 5 drives the magnetic head 3 to move and align with the printing point to be solidified;

[0047] S2, the magnetic head 3 is energized to generate a magnetic field in a preset direction in the area to be solidified, so that the magnetic moment of the magnetic powder in the area to be solidified rotates and aligns with the external magnetic field;

[0048] S3. Turn on the light source to illuminate the printed point to be cured, so that the magnetic paste of the printed point is cured.

[0049] The material pool 1 is only half shown for ease of illustration, with a transparent bottom, and contains a mixture of photosensitive resin and magnetic powder. The ejection mechanism 2 lifts the printed portion so that the printing material fills the layer to be printed.

[0050] The translation mechanism 5 can be composed of two orthogonal four-bar slides, or a mechanical structure with the same function. The translation device can drive the magnetic head 3 to move in any large space.

[0051] The magnetic head 3 adopts a magnetic tweezers structure and uses a yoke design to improve the magnetic circuit and increase the efficiency of magnetic field generation. The magnetic tweezers are composed of m magnetic pole coils that are centripetally wrapped. The m magnetic pole coils are evenly distributed circumferentially. m is greater than or equal to 3 and can be 3, 4, 5, 6, 7, 8... poles. By passing current of a specific direction and magnitude through the different magnetic pole coils, a desired magnetic field with a specified magnetic field direction can be generated at a certain point P in space to magnetize the printed point to be cured. This is a universal magnetic field generating device. The following is an embodiment of m=4, which can be placed at the center of the magnetic pole (i.e., the area to be cured, see Figure 4 The excitation at point P in the center generates a three-dimensional magnetic field in any direction.

[0052] The main body of the magnetic head 3 is made of a soft magnetic material with low coercivity and high magnetic permeability, such as ferrite, etc. The purpose of using soft magnetic materials is to amplify the magnetic field generated by the coil while minimizing the negative effects of magnetic field direction deviation caused by residual magnetism.

[0053] Establish a coordinate system with the magnetization center as the coordinate origin, the magnetization center as the printing point P to be solidified, and m magnetic pole coils are arranged centripetally with the z axis as the symmetry axis. The magnitude and direction of the magnetic field determine the current flowing into each pole coil;

[0054] When m=4,

[0055] The currents I1 to I4 flowing through the four magnetic pole coils of the magnetic tweezers are:

[0056]

[0057]

[0058]

[0059]

[0060] in,

[0061] B is the desired magnetic field The magnetic field strength;

[0062] k1, k2 are constants related to the head material, structure, and number of coil turns, and are calibration quantities;

[0063] φ is the desired magnetic field The angle between the direction of the magnetic field intensity and the z-axis;

[0064] θ is the desired magnetic field The angle between the projection and the x-axis in the xy plane;

[0065] α is the angle between the line connecting the magnetization center and the tip of a magnetic tweezers and the z-axis.

[0066] See also Figure 2 This is a schematic diagram of the curing process of the present invention. First, the printing material is configured and added to the material pool 1. Then the printed part is cured layer by layer. The curing of each layer is completed point by point. Each point needs to go through the following process:

[0067] 1. The translation mechanism 5 drives the magnetic head 3 to move and align with the point to be solidified.

[0068] 2. The magnetic head 3 is energized to generate a desired magnetic field, causing the magnetic moment of the magnetic powder in the area to be solidified to rotate and align with the external magnetic field.

[0069] 3. Use light of a certain wavelength to irradiate the point to be cured to cure it.

[0070] The settings given by the user here include the shape of the printed part, the magnetization direction of different positions of the printed part, etc. For details, please refer to Figure 3 If you want to solidify Figure 3 The structure of (a) is divided into multiple layers and printed layer by layer from top to bottom. Taking the printing layer B as an example, the magnetic moment direction of the magnetic powder in layer B is as follows: Figure 3(b) According to the instructions, the device will execute the program to divide the layer to be printed into several areas. Layer B is divided into six areas, area a, area b, etc. The desired magnetic field size and direction of each printing point in the same area are the same. Each area is divided into multiple points to be printed using a grid. The printing process is to translate the magnetic head 3 to align with a printing point in area a, and pass a current of a certain size and direction through the four magnetic pole coils to generate a magnetic field with a preset magnetization direction in area a. Make the magnetic moment of the magnetic powder in area a face the preset magnetization direction of area a, then the light source illuminates the printing point to be cured in area a, and the other printing points in area a do not receive light, so that the printing material at this point is cured while the other printing materials are not cured, such as Figure 3 Similarly, with the assistance of the translation mechanism 5, all the printed dots in area a are solidified in a scanning manner to complete the magnetization printing of area a.

[0071] After the a area is solidified, the translation mechanism 5 drives the magnetic head to align with a printing point in the b area, and starts the scanning magnetization printing of the b area. The specific process is the same as that of the a area. The difference is that the desired magnetic field of the b area is The size and direction can be different from other areas. The magnetization printing diagram of area b is as follows Figure 3 (e) shown.

[0072] By analogy, you can complete the layer B Figure 3 (c) The curing process for all areas. After each layer is printed, the ejector mechanism rises to the height of the printed layer and continues printing the next layer. After all layers are printed, the entire print is complete.

[0073] The printing material is a commercially available composite material consisting of a photosensitive resin and magnetic powder. The photosensitive resin can be any flexible, light-curable resin, such as GC3D-EBE or Godart E600. The magnetic powder can be any hard magnetic powder, such as AlNiCo, NdFeB, or Fe3O4.

[0074] After mixing the magnetic powder, use an ultrasonic mixer or other instrument to stir it evenly. Then, place it in a vacuum chamber to remove air bubbles and ensure that the magnetic powder and photosensitive resin are thoroughly mixed. After mixing, the printing material needs to be magnetized. This involves applying a pulsed strong magnetic field to the printing material. The magnetic field strength must be sufficient to nearly saturate the magnetic moment of the magnetic powder. If the magnetic powder has already been magnetized before mixing, re-magnetization is not necessary after mixing.

[0075] According to the preset magnetization pattern, the magnetic tweezers will generate a magnetic field in a specified direction at the magnetization center. The magnetic field strength is sufficient to cause the magnetic powder to rotate under the action of the magnetic torque, but will not significantly reduce the magnetic moment of the magnetic powder itself (even if the magnetic powder is demagnetized and re-magnetized). The magnetic powder in the printed material at the magnetization center will only rotate under the action of the magnetic torque, and eventually the magnetic moment of the magnetic powder will be aligned with the direction of the external magnetic field (that is, the direction of the magnetic field generated by the magnetic tweezers). The magnetic powder in the area that has been irradiated and cured by UV light will not change its magnetic moment direction because it has been fixed by the resin.

[0076] In order to prevent the magnetic powder from settling in the printing material, the rising process of the ejection mechanism 2 can be optimized by first raising it to a higher distance, then lowering it to a certain distance, and finally reaching a position one printing layer height higher than the previous printing layer. The purpose is to stir the printing material through the movement of the ejection mechanism 2.

[0077] Specific implementation method 2: The following is combined Figure 1 This embodiment further illustrates the first embodiment and further includes a frame 10 , on which the ejection mechanism 2 , the material pool 1 and the translation mechanism 5 are sequentially mounted from top to bottom.

[0078] Specific implementation method three: Figure 1 This embodiment is described as further describing the first embodiment, and further includes a scraper 6 , which is disposed in the material pool 1 and reciprocates along the bottom of the material pool 1 .

[0079] In order to ensure that the magnetic powder is always evenly distributed in the resin, a mixing mechanism is added to the device, such as a scraper 6 in the material pool 1. When the ejector mechanism 2 is raised and lowered, the scraper 6 will reciprocate horizontally at the bottom of the material pool 1 to further prevent the magnetic powder from settling in the printing material.

[0080] Specific implementation method four: the following combination Figure 5 This embodiment further explains the first embodiment. In the light curing system, the light source 4 can adopt two schemes:

[0081] Solution 1: The light source 4 is a laser light source. The laser light source is fixed on the magnetic head 3 and moves with the magnetic head 3, irradiating the area to be cured upwards ( Figure 1 In this solution), the laser light source is fixed just below the magnetic head 3 and linked to the magnetic head. Figure 3 For example, when the magnetic head 3 is aligned with a printing point in area a, the laser is also aligned with the point. The laser light source can also be fixed on a frame (not shown), and the laser is guided to irradiate the area to be cured through optical elements such as reflectors.

[0082] Option 2: The light source 4 can also be a point light source. For example, the light source 4 uses an LED light source assembly, which includes an LED light source 7, an LCD screen 8, and a condenser 9. The LED light source 7 is arranged on a support plate below the magnetic head 3, and the condenser 9 is arranged around the LED light source 7 for focusing light. The LCD screen 8 is a transparent screen and is arranged on the lower surface of the bottom plate of the material pool 1 above the magnetic head 3. In this solution, it is necessary to add an LCD screen 8 (only a part of it is shown in the figure) under the material pool 1 to serve as a mask to prevent the non-curing area from being irradiated and cured. The wavelength of the light source needs to match the photosensitive resin. For example, if the resin is Godart E600, a light source with a wavelength of 405 nanometers needs to be selected.

[0083] By combining the LED light source 7 with the LCD screen 8 (only a portion is shown in the figure), the LCD screen 8 is controlled so that only the position of the point to be printed allows the light from the LED light source 7 to pass through. At this time, the LED light source 7 needs to be fixed directly below the magnetic head 3. In order to improve the utilization rate of the light source, a condenser 9 made of a high-reflectivity material (such as aluminum or other metal materials) can be added.

[0084] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A programmable magnetic light-curing 3D printer, characterized in that: It includes a collaboratively controlled light-curing system and a magnetic programming system, which work alternately. The light-curing system cures the resin layer by layer and region by region according to the pre-designed 3D printed part model, while the magnetic programming system is used to discretely magnetize the 3D printed part layer by layer and region by region. The magnetic moment orientation of the magnetic powder in each region of each layer is arranged according to the set arrangement. The light curing system comprises a material pool (1), a demoulding mechanism (2) and a light source (4), wherein the demoulding mechanism (2) and the light source (4) are respectively arranged above and below the material pool (1) with a transparent bottom; The magnetic programming system includes a magnetic head (3) and a translation mechanism (5). The magnetic head (3) generates a point magnetic field. The translation mechanism (5) drives the magnetic head (3) to scan and magnetize each layer of magnetic slurry in the material pool (1) point by point. The scanning area of each layer is determined by the shape of a preset model. Each layer of the model to be printed is divided into multiple areas to be cured. Each area to be cured is divided into multiple printing points using a grid format. Each printing point is printed one by one. The printing and curing process is as follows: S1, the translation mechanism (5) drives the magnetic head (3) to move and align with the printing point to be solidified; S2, the magnetic head (3) is energized to generate a magnetic field in a preset direction in the area to be solidified, so that the magnetic moment of the magnetic powder in the area to be solidified rotates and aligns with the external magnetic field; S3, turning on the light source to illuminate the printed point to be cured, so that the printed point is cured; The magnetic head (3) adopts a magnetic tweezer structure, which is composed of m magnetic pole coils surrounded centripetally, where m is greater than or equal to 3; by inputting currents of specific directions and magnitudes into the different magnetic pole coils, a desired magnetic field of set magnitude and direction is generated at point P, and the printed point to be solidified is magnetized; Establish a coordinate system with the magnetization center as the coordinate origin, the magnetization center as the printing point P to be solidified, and m magnetic pole coils are arranged centripetally with the z axis as the symmetry axis. The magnitude and direction of the magnetic field determine the current flowing into each pole coil; When m=4, The currents I1 to I4 flowing through the four magnetic pole coils of the magnetic tweezers are: in, B is the desired magnetic field The magnetic field strength; k1, k2 are constants related to the head material, structure, and number of coil turns; φ is the desired magnetic field The angle between the direction of the magnetic field intensity and the z-axis; θ is the desired magnetic field The angle between the projection and the x-axis in the xy plane; α is the angle between the line connecting the magnetization center and the tip of a magnetic tweezers and the z-axis.

2. A programmable magnetic light-curing 3D printer according to claim 1, characterized in that: It also includes a frame (10), on which the demoulding mechanism (2), the material pool (1) and the translation mechanism (5) are sequentially mounted from top to bottom.

3. A programmable magnetic light-curing 3D printer according to claim 2, characterized in that: It also includes a scraper (6), which is arranged in the material pool (1) and reciprocates along the bottom of the material pool (1).

4. A programmable magnetic light-curing 3D printer according to claim 1, characterized in that: The light source (4) is a laser light source, which is fixed on the magnetic head (3) and moves along with the magnetic head (3).

5. A programmable magnetic light-curing 3D printer according to claim 1, characterized in that: The light source (4) adopts an LED light source assembly, which includes an LED light source (7), an LCD screen (8) and a condenser (9). The LED light source (7) is arranged on a support plate below the magnetic head (3), the condenser (9) is arranged around the LED light source (7) for condensing light, and the LCD screen (8) is a transparent screen and is arranged as a mask on the lower surface of the bottom plate of the material pool (1) above the magnetic head (3).

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