A rotating volume method multi-material gradient three-dimensional printer and printing method

Abstract

The application discloses a rotary volume method multi-material gradient three-dimensional printer and a printing method, and the three-dimensional printer comprises a printer base, an outer material pool, an inner material pool, a motion system, a support structure and a light source assembly; the outer material pool and the support structure are fixed on the printer base, the inner material pool is located inside the outer material pool, and the top end of the inner material pool is fixed on the motion system, and the motion system is fixed on the support structure; the light source assembly is arranged on one side of the outer material pool; the inner material pool contains inhomogeneous ink with a photo-cured hydrogel as a matrix material, and the outer material pool contains a hydrogel without containing a photo initiator; the motion system can control the rotation and lifting movement of the carrier rod along an axis. The application can realize the free and high-precision distribution of various materials in space according to a design structure, supports the simultaneous printing of materials with a large modulus span, and supports the controllable distribution of the three-dimensional space density of heterogeneous multi-particle-size bone powder; and is suitable for the integrated printing of various materials, and greatly improves the efficiency of multi-material photo-cured 3D printing.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing, specifically relating to a rotating volumetric multimaterial gradient 3D printer and printing method. Background Technology

[0002] With the gradual maturation of 3D printing technology, various printing devices for biomedical applications have emerged in recent years. These include 3D printing equipment based on principles such as fused deposition modeling, extrusion, photopolymerization, and laser sintering, using metals, alloys, ceramics, plastics, and hydrogels as printing inks. These devices are applied to bone implants, dental implants, bone guides, and medical teaching instruments. For example, when using inorganic materials as printing inks to construct biomimetic bone structures, ceramic slurries are typically formed through high-temperature sintering or photopolymerization. However, these existing methods suffer from several drawbacks. First, they use very fine-grained, uniform slurries for printing. Second, they rely on auxiliary rollers or scrapers to process the printing surface of each layer. This results in a crude and unreliable feeding process with poor repeatability. Furthermore, because water-insoluble particles in the slurry settle due to gravity, the uniformity of the material in the structure is difficult to guarantee, leading to a significant waste of raw materials. Summary of the Invention

[0003] The purpose of this invention is to design a rotary volumetric multi-material gradient 3D printer and printing method, solving the problem of controlling the density of water-insoluble inorganic materials in existing 3D printing technologies, and completely abandoning the existing methods that rely on auxiliary rollers or doctor blades to process the printing surface of each layer. It achieves rapid, density-controllable, particle-size-controllable, high-precision, high-efficiency printing with flexible material gradient distribution switching.

[0004] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0005] A rotating volumetric multimaterial gradient 3D printer includes a printer base, an outer material tank, an inner material tank, a motion system, a support structure, and a light source assembly.

[0006] The outer material tank and the support structure are fixed on the printer base. The inner material tank is located inside the outer material tank, and the top of the inner material tank is fixed on the motion system. The motion system is fixed on the support structure. The light source assembly is arranged on one side of the outer material tank. The inner material tank contains heterogeneous ink with photocurable hydrogel as the matrix material, and the outer material tank contains hydrogel that does not contain photoinitiator.

[0007] The motion system includes an angular contact bearing, a lifting assembly for a loading rod, a vibration control assembly, a clamping device, a housing, a driven gear, a driving gear, a loading rod base, and a bushing. The angular contact bearing, driven gear, driving gear, and bushing are located inside the housing. The bushing is fitted inside the inner ring of the angular contact bearing, and the outer ring of the angular contact bearing is nested in the central hole of the housing. The loading rod base is fixed to the bottom of the central hole of the bushing, and the lifting assembly for the loading rod is fixed to the loading rod base. The driven gear is fixed to the top of the outer ring of the bushing, and the shaft of the driving gear is fixed to the housing. The driving gear and the driven gear cooperate to form a gear pair that drives the inner ring of the angular contact bearing. The bottom end of the bushing extends out of the housing, and the upper end of the clamping device is fitted onto the bottom end of the bushing, clamping the inner material pool. The vibration control assembly is fitted around the outer periphery of the clamping device.

[0008] Furthermore, the lifting assembly of the carrying pole includes a carrying pole and a gear and rack lifting mechanism, the gear and rack lifting mechanism is connected to the carrying pole, and the carrying pole is positioned at the axial center inside the inner material tank during operation; the light emitted by the light source assembly intersects perpendicularly with the carrying pole in the working state, and the carrying pole is located within the imaging plane of the light source assembly.

[0009] Furthermore, the support structure includes a lifting slider, a lifting bracket, and a lifting platform. The lifting bracket is fixed on the printer base, the lifting platform is mounted on the lifting bracket via the lifting slider, and the motion system is fixed on the lifting platform.

[0010] Furthermore, the outer casing includes a housing and a top cover.

[0011] A printing method for a multi-material gradient 3D printer based on the rotational volume method includes the following steps:

[0012] (1) Before printing begins, mix the various printing materials and put them into the inner material pool, and put the hydrogel into the outer material pool. The inner material pool is submerged in the hydrogel in the outer material pool.

[0013] (2) Turn on the oscillation control component to drive the inner material pool to generate a controllable amplitude vibration, eliminate air bubbles in the ink inside the inner material pool, and at the same time make the printing material suspend in different positions in the hydrogel in layers.

[0014] (3) Start printing, adjust the distance of the light source so that the rotation axis of the inner material pool is located within the focal plane of the light source imaging, so that the ink in the focal plane area that is illuminated solidifies to form a thin layer structure, and the light source stops illuminating this layer; then, the inner material pool rotates a certain angle along the central axis, and the solid thin layer structure formed last time also rotates a certain angle along the central axis from the fixed focal plane. Next, the light source emits the image of the next cross-section to the focal plane. At this time, the liquid ink at the focal plane cross-links and solidifies due to the light imaging to form a thin layer structure. The thin layer structure of this cross-section and the thin layer structure solidified in the previous cross-section are both fixed on the carrier rod; in this way, the process of rotating the inner material pool by a certain angle and solidifying is repeated. When the entire inner material pool rotates 180°, the printing of the entire three-dimensional structure is completed.

[0015] The beneficial effects of this invention are as follows:

[0016] As long as the material can be distributed in layers within the cylindrical inner material pool, the multi-material gradient 3D printer using the rotating volume method of this invention can achieve multi-material gradient printing. This method supports the curing of large-particle materials that are insoluble in water, solving the problems of existing photopolymerization methods where large-particle structures, such as bone powder, cannot be leveled using auxiliary rollers, scrapers, etc., and cannot be printed. The oscillation time is very fast, and the efficiency is far higher than that of auxiliary rollers, scrapers, etc. Furthermore, by adjusting the hydrogel type of the solution, it can support stable suspension of the solute, reducing the number of times oscillation is required for uniform printing, which greatly improves the printing efficiency.

[0017] The printer of this invention can realize the free and high-precision distribution of various materials in space according to the designed structure, support the simultaneous printing of materials with large modulus range, especially the on-demand mixing and printing of low modulus hydrogels and high modulus bone powder, and support the three-dimensional spatial density controllable distribution of heterogeneous multi-particle-size bone powder.

[0018] Compared to conventional rotational volumetric printing, this invention is suitable for integrated printing of multiple materials, greatly improving the efficiency of multi-material photopolymer 3D printing. Compared to conventional multi-material photopolymer printing methods, the carrier rod and the formed body of this invention are immersed in liquid material and remain relatively stationary throughout the printing process. Therefore, it supports high-precision printing of feature structures that do not have self-supporting capabilities in air, resulting in a short working cycle, high efficiency, and low cost. Attached Figure Description

[0019] Figure 1 This is a perspective view of a rotating volume method multi-material gradient 3D printer according to an embodiment of the present invention.

[0020] Figure 2 This is a front view of a rotating volumetric multimaterial gradient 3D printer according to an embodiment of the present invention.

[0021] Figure 3The images show the top view and AA section view of the motion system 4.

[0022] Figure 4 This is an exploded view of the rotating components inside motion system 4.

[0023] Figure 5 This is an enlarged structural diagram of the lifting assembly 42 on the load-bearing pole.

[0024] Figure 6 A schematic diagram of the process for printing a non-homogeneous gradient distribution structure using a printer.

[0025] In the diagram, the components are: printer base 1, outer material tank 2, inner material tank 3, motion system 4, support structure 5, light source assembly 6, angular contact bearing 41, lifting assembly of the loading rod 42, vibration control assembly 43, clamping device 44, outer shell 45, driven gear 46, driving gear 47, loading rod base 48, bushing 49, housing 451, top cover 452, loading rod 421, gear and rack lifting mechanism 422, center hole 50, lifting slider 51, lifting bracket 52, and lifting platform 53. Detailed Implementation

[0026] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0027] like Figure 1 and 2 As shown, the rotating volume method multi-material gradient 3D printer of this embodiment includes a printer base 1, an outer material pool 2, an inner material pool 3, a motion system 4, a support structure 5, and a light source assembly 6.

[0028] The printer base 1 is stably placed on the ground or platform surface via fixed feet. The outer material tank 2 and the support structure 5 are mounted on the printer base 1 and are fixed by a mechanical structure, providing a foundation for rotational volumetric multi-material gradient 3D printing. The inner material tank 3 is located inside the outer material tank 2 and is fixed to the motion system 4, which is also mounted on the support structure 5. The cylindrical inner material tank 3 contains heterogeneous ink with photocurable hydrogel as the matrix material, such as a resin solution containing bone meal particles. The bone meal density is higher near the bottom of the cylindrical inner material tank 3 and lower near the top. The outer material tank 2 contains hydrogel without photoinitiator.

[0029] like Figure 3 and 4As shown, the motion system 4 includes an angular contact bearing 41, a lifting assembly 42 for a carrying rod, an oscillation control assembly 43, a clamping device 44, a housing 45, a driven gear 46, a driving gear 47, a carrying rod base 48, and a bushing 49. The housing 45 includes a shell 451 and a top cover 452. The angular contact bearing 41, bushing 49, driven gear 46, and driving gear 47 are located inside the housing 45. The bushing 49 is fitted inside the inner ring of the angular contact bearing 41, and the outer ring of the angular contact bearing 41 is nested in the central hole of the housing 451. The carrying rod base 48 is fixed to the bottom of the central hole 50 of the bushing 49, and the lifting assembly 42 is fixed to the carrying rod base 48. The driven gear 46 is fixed to the top of the outer ring of the bushing 49, and the shaft of the driving gear 47 is fixed to the housing 451. The driving gear 47 and the driven gear 46 cooperate to form a gear pair that drives the inner ring of the angular contact bearing 41. The bottom end of the bushing 49 extends out of the outer shell 45, and the upper end of the clamping device 44 is fitted onto the bottom end of the bushing 49, clamping the inner material pool 3. The vibration control component 43 is fitted around the outer periphery of the clamping device 44, providing controllable vibration for the clamping device 44 and the inner material pool 3. Before and after printing, ultrasonic vibration can be used to achieve multi-material stratification and defoaming in the ink inside the inner material pool 3. The drive gear 47 is rotated by a motor, which in turn drives the driven gear 46, bushing 49, carrier rod base 48, carrier rod lifting component 42, vibration control component 43, clamping device 44, and inner material pool 3 to rotate.

[0030] The oscillation control component 43 can cause the ink inside the inner material pool 3 to vibrate through mechanical motion or ultrasonic oscillation. The oscillation frequency and amplitude can be set according to the specific printing material used. After each curing, the ink layer structure inside the inner material pool is kept stable by rapidly applying oscillation, which prevents the water-insoluble material in the ink from sinking due to gravity, thereby causing a significant change in the material density of the cured area.

[0031] like Figure 5 As shown, the lifting assembly 42 includes a lifting rod 421 and a rack and pinion lifting mechanism 422. The rack and pinion lifting mechanism 422 is connected to the lifting rod 421, which is positioned at the axial center inside the inner material tank 3 during operation. When the lifting assembly 42 is driven to rotate, the lifting rod 421 can rotate around its axial center and can also be raised and lowered. The end of the lifting rod 421 extending into the inner material tank 3 moves up and down within the cylindrical inner material tank 3. The light projection can be cured, i.e., printed, at the bone powder resin mixture of different densities within the material tank. As the end of the lifting rod moves from high (up) to low (down), it is possible to first print the structure with lower bone powder density and then print the structure with higher bone powder density, thereby achieving integrated gradient printing.

[0032] like Figure 2As shown, the support structure 5 includes a lifting slider 51, a lifting bracket 52, and a lifting platform 53. The lifting bracket 52 is fixed to the printer base 1, and the lifting platform 53 is mounted on the lifting bracket 52 via the lifting slider 51. The motion system 4 is fixed to the lifting platform 53. A motor drives the lifting bracket 52, which in turn drives the lifting platform 53 and the motion system 4 to move vertically, causing the inner ink reservoir 3, held in the motion system 4, to move vertically within the outer ink reservoir 2. At its lowest point, the lower surface of the motion system 4 is higher than the top of the outer ink reservoir 2 fixed to the printer base 1. By adjusting the motion system and its clamping device using the support structure 5, the level of the layered ink in the inner ink reservoir 3 can be kept horizontal, preventing uncontrollable density distribution due to tilting.

[0033] The light source assembly 6 is fixed to one side of the outer material pool 2. Its axially emitted light is perpendicularly incident on one side of the outer material pool 2. The axially emitted light intersects perpendicularly with the working material rod 421. The material rod 421 is located within the imaging plane of the light source assembly 6.

[0034] The principle of printing using the rotating volume method multi-material gradient 3D printer of the present invention is to slice the 3D structure into multiple projection areas along the central axis, rotate the material pool through the rotation system, and cure the photocurable material in the required area by the light source until the printing is completed after rotating 180°.

[0035] Before printing begins, various printing materials are mixed and placed into the inner material pool 3. Taking bone powder and hydrogel of various particle sizes as an example, bone powder and hydrogel are added to the inner material pool 3 with a crosslinking agent in proportion. The hydrogel is placed into the outer material pool as a medium to ensure that the printing light source is incident in parallel. After the inner material pool 3 is clamped on the clamping device 44, the inner material pool 3 is immersed in the hydrogel in the outer material pool 2. This process can ensure that the imaging light of the light source can be incident through the air-liquid plane interface of the outer material pool and imaged at the focal plane.

[0036] Subsequently, the vibration control component 43 is activated, causing the inner material tank 3 to vibrate with controllable amplitude. Ultrasonic vibration eliminates air bubbles in the ink within the inner material tank 3. Crucially, the vibration causes the bone powder in the multi-material ink to stratify and suspend at different positions within the hydrogel according to its particle size. Smaller bone powder particles, due to their lower buoyancy-gravity, settle at the bottom of the inner material tank, while larger particles, due to their higher buoyancy-gravity, remain suspended at the top. By adjusting the height of the carrier rod 421 within the inner material tank, structures requiring different particle sizes of bone powder ink can be formed. Figure 6 As shown in a, after the small-particle-size bone powder + hydrogel ink is formed in the bottom area of ​​the inner material tank 3, the height of the carrier rod is raised to the medium-particle-size bone powder area, and the printing steps are repeated, as shown in a diagram. Figure 6As shown in b, the process then moves to the large-particle-size bone powder area, where the molding of the large-particle-size bone powder + hydrogel ink can continue. Figure 6 As shown in c in the figure. Multiple particle size bone powder + hydrogel material layered structures can be printed without switching feeders, as shown in the printing results. Figure 6 As shown in d in the figure. Similarly, inks of different densities can also be used to print heterogeneous structures using this method.

[0037] The specific printing process for each layer is as follows: By adjusting the distance of the light source, the rotation axis of the inner material pool 3 is located within the focal plane of the light source imaging, so that the ink that receives light in the focal plane area solidifies to form a thin layer structure, and the light source stops printing this layer.

[0038] Subsequently, the inner material tank 3 rotates a certain angle along the central axis. The solid thin-layer structure formed in the previous curing also rotates a certain angle along the central axis from the fixed focal plane. Next, the light source emits an image of the next cut surface to the focal plane. At this time, the liquid ink at the focal plane cross-links and cures due to the light imaging, forming a thin-layer structure. The thin-layer structure of this cut surface and the thin-layer structure cured in the previous cut surface are both fixed on the carrier rod 421. This process of rotating the inner material tank 3 by a certain angle and curing is repeated. When the entire inner material tank rotates 180°, the printing of the entire three-dimensional structure is completed.

[0039] Unlike traditional projection-based photopolymerization printing methods, which involve vertically stacking multiple parallel imaging slices to form a three-dimensional structure, this printing method uses a central axis relative to the center of the target printed structure as a rotation axis. All slices are centered around this rotation axis to form the desired three-dimensional structure. The angle between the slices can be compared to the layer height in traditional projection-based photopolymerization printing methods.

[0040] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A rotational volumetric multi-material gradient 3D printer, characterized in that, It includes a printer base (1), an outer material tank (2), an inner material tank (3), a motion system (4), a support structure (5), and a light source assembly (6); The outer material tank (2) and the support structure (5) are fixed on the printer base (1). The inner material tank (3) is located inside the outer material tank (2), and the top of the inner material tank (3) is fixed on the motion system (4). The motion system (4) is fixed on the support structure (5). The light source assembly (6) is arranged on one side of the outer material tank (2). The inner material tank (3) contains heterogeneous ink with photocurable hydrogel as the matrix material, and the outer material tank (2) contains hydrogel without photoinitiator. The motion system (4) includes an angular contact bearing (41), a lifting assembly for the carrying pole (42), an oscillation control assembly (43), a clamping device (44), a housing (45), a driven gear (46), a driving gear (47), a base for the carrying pole (48), and a bushing (49); wherein, the angular contact bearing (41), the driven gear (46), the driving gear (47), and the bushing (49) are located inside the housing (45), the bushing (49) is sleeved in the inner ring of the angular contact bearing (41), and the outer ring of the angular contact bearing (41) is nested in the central hole of the housing (45); the base for the carrying pole (48) is fixed to the bottom of the central hole of the bushing (49). The lifting assembly (42) of the loading rod is fixed on the base (48) of the loading rod; the driven gear (46) is fixed on the top of the outer ring of the bushing (49), and the shaft of the driving gear (47) is fixed on the outer shell (45). The driving gear (47) and the driven gear (46) cooperate to form a gear pair that drives the inner ring of the angular contact bearing (41) to move; the bottom end of the bushing (49) extends out of the outer shell (45), the upper end of the clamping device (44) is sleeved on the bottom end of the bushing (49), and the bottom end of the clamping device (44) clamps the inner material pool (3); the vibration control assembly (43) is sleeved on the outer periphery of the clamping device (44).

2. The rotating volumetric multi-material gradient 3D printer according to claim 1, characterized in that, The lifting assembly (42) for the carrying pole includes a carrying pole (421) and a rack and pinion lifting mechanism (422). The rack and pinion lifting mechanism (422) is connected to the carrying pole (421). When working, the carrying pole (421) is placed at the axial position inside the inner material pool (3). The light source assembly (6) emits light that intersects perpendicularly with the carrying pole (421) in the working state. The carrying pole (421) is located within the imaging plane of the light source assembly (6).

3. The rotating volumetric multi-material gradient 3D printer according to claim 1, characterized in that, The support structure (5) includes a lifting slider (51), a lifting bracket (52) and a lifting platform (53). The lifting bracket (52) is fixed on the printer base (1). The lifting platform (53) is mounted on the lifting bracket (52) via the lifting slider (51). The motion system (4) is fixed on the lifting platform (53).

4. The rotating volumetric multi-material gradient 3D printer according to claim 1, characterized in that, The outer casing (45) includes a housing (451) and a top cover (452).

5. A printing method for a multi-material gradient 3D printer based on any one of claims 1 to 4 using the rotational volume method, characterized in that, Includes the following steps: (1) Before printing begins, mix various printing materials and place them in the inner material tank (3), and place the hydrogel in the outer material tank (2). The inner material tank (3) is submerged in the hydrogel in the outer material tank (2). (2) Turn on the oscillation control component (43) to drive the inner material pool (3) to generate a controllable vibration, eliminate air bubbles in the ink inside the inner material pool (3), and at the same time make the printing material layered and suspended in different positions in the hydrogel. (3) Start printing, adjust the distance of the light source so that the rotation axis of the inner material pool (3) is located within the focal plane of the light source imaging, so that the ink in the focal plane area that is illuminated solidifies to form a thin layer structure, and the light source stops the illumination of this layer printing; then, the inner material pool (3) rotates a certain angle along the central axis, and the solid thin layer structure formed by the previous solidification also rotates a certain angle along the central axis from the fixed focal plane. Next, the light source emits the image of the next cut surface to the focal plane. At this time, the liquid ink at the focal plane cross-links and solidifies due to the light imaging to form a thin layer structure. The thin layer structure of this cut surface and the thin layer structure solidified by the previous cut surface are both fixed on the carrier rod (421); in this way, the process of rotating the inner material pool (3) by a certain angle and solidifying is repeated. When the entire inner material pool (3) rotates 180°, the printing of the entire three-dimensional structure is completed.

Images