An auxiliary transition deposition device and method for melt near-field direct-write tubular scaffold fabrication

Abstract

The application discloses an auxiliary transition deposition device and method for preparing a melt near-field direct-writing tubular stent, solves the problem that when a square structure, a negative Poisson structure, a snake-shaped structure and other non-closed path patterns are printed on a tubular receiver surface, there is an axial position or circumferential phase offset between the end position of a single-layer target path and the start position of the next layer, and when returning to the start position, an additional return path needs to be passed through, which is easy to cause non-target fiber deposition, and thus the non-target fiber deposition is difficult to be effectively separated from the main structure of the tubular stent. The auxiliary transition deposition platform is arranged laterally on the tubular receiver, a transition deposition area independent of the main structure of the tubular stent is constructed, and transition deposition fibers formed in the layer-to-layer return process can be connected, cut off and stably transitioned in the area. The auxiliary transition deposition platform realizes the switching of the deposition area between the tubular receiver and the device through a newly-added Y-axis movement device, so that the transition deposition fibers are spatially separated from the main stent, and the structural integrity, the appearance consistency and the forming precision of the tubular stent are improved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to an auxiliary transition deposition device and its usage method for interlayer repositioning of non-closed paths during the printing of tubular supports in melt electro-writing (MEW) near-field direct writing. Background Technology

[0002] Melt Electro-Writing (MEW) is an additive manufacturing technology that uses an electric field to drive a jet of molten polymer to achieve ordered deposition of micron-sized fibers. It features controllable fiber diameter, precise spatial arrangement, and designable pore structure. It has gradually expanded from the construction of traditional planar tissue engineering scaffolds to the precise manufacturing of three-dimensional complex structures and tubular biomimetic configurations.

[0003] In MEW printing of tubular supports, a cylindrical mandrel is typically used as the receiver. Through coordinated control of the mandrel's axial movement and rotation, a two-dimensional design path is mapped onto the cylindrical surface, enabling the construction of various periodic structures such as rhombuses, squares, and negative Poisson structures. During tubular MEW printing, path planning must consider the periodic constraint of the mandrel's circumference. That is, after the path extends one full circle (circumference πd), it returns to its initial spatial phase position. Therefore, unlike planar structures, the tubular receiver surface is not an infinitely expanding domain in the circumferential direction, but rather a periodically closed finite mapping space. Under this constraint, for some patterns with circumferential periodic closure characteristics, such as rhombus structures, the single-layer printing path has consistent start and end positions in the circumferential direction. That is, after the path completes one full circle, the end point and start point are spatially aligned. Therefore, after a single layer is printed, it can directly connect to the starting position of the next layer, thus achieving continuous interlayer deposition. However, for non-closed path patterns such as grid structures, negative Poisson structures, and serpentine structures, due to the geometric constraint of the circumference πd of the tubular support, the endpoint of a single-layer target path after deposition around the circumference is often difficult to align directly with the starting position of the next layer, requiring an additional repositioning or relocation process, thus making it difficult to achieve continuous interlayer deposition. If interlayer repositioning is performed directly on the surface of the cylindrical mandrel, non-target deposition paths are easily formed on the main body of the tubular support; if repositioning is performed along an existing path, local fiber re-deposition is likely to occur. As the number of printed layers increases, re-deposition accumulates layer by layer, causing the local fiber accumulation height to gradually exceed that of the surrounding area, forming obvious height unevenness. The MEW jet deposition trajectory is highly sensitive to the local electric field distribution. An increase in local height will shorten the distance between the deposition structure and the nozzle, enhance the local electric field intensity in that area, and thus form a "high-point attraction" effect. As the height difference further accumulates, this effect will continue to disturb the stable deposition of the jet, causing jet deflection or even backflow, ultimately affecting printing accuracy.

[0004] Another feasible approach is to replan the printing path for adjacent layers. This involves using the endpoint of the first layer as the starting position for the second layer after the target path of the first layer is completed. By adjusting the path order, printing direction, or cell connection method of the second layer, the target path of the second layer returns to the initial position of the first layer upon completion, thus achieving path repositioning in two or more layer cycles. While this method can avoid repeated deposition of the jet on existing target paths to some extent, it requires re-establishing path closure relationships for different pattern structures, mandrel sizes, cell periods, and interlayer stacking methods, significantly increasing the complexity of path design and G-code generation.

[0005] Therefore, existing tubular MEW printing methods still suffer from problems when processing non-closed path patterns, such as difficulty in effectively separating interlayer return paths from the main structure of the tubular support, the tendency of interlayer return paths to cause local repeated deposition, and complex and insufficiently versatile multilayer path reconstruction. There is an urgent need to provide an auxiliary transition deposition device and its usage method that can do so without changing the basic path of the target pattern, without relying on complex interlayer path reconstruction, and without significantly increasing equipment complexity. Summary of the Invention

[0006] This invention aims to provide an auxiliary transition deposition device and method for the fabrication of tubular scaffolds using near-field direct writing of melt, solving the problem that when non-closed path patterns such as grid structures, negative Poisson structures, and serpentine structures are printed on the surface of a tubular receiver, there is an axial position or circumferential phase offset between the end position of the single-layer target path and the starting position of the next layer. When returning to the starting position, an additional return path is required, which easily leads to the deposition of non-target fibers, making it difficult to effectively separate them from the main structure of the tubular scaffold.

[0007] To solve the above technical problems, the following technical solution is adopted:

[0008] An auxiliary transition deposition apparatus for near-field direct writing of molten tubular supports includes a molten jet forming unit, a tubular receiver, and a multi-axis cooperative motion control unit. It also includes an auxiliary transition deposition unit, which serves as an auxiliary receiving area during the interlayer repositioning process. The auxiliary transition deposition unit includes an auxiliary transition deposition platform and a blade component connected to the platform. The platform receives transition deposition fibers formed during the interlayer repositioning process, and the blade component passively cuts the bridging fibers formed between the tubular receiver unit and the platform.

[0009] Furthermore, the auxiliary transition deposition platform is located on one side of the tubular receiver and is arranged parallel to the axial direction of the tubular receiver. The deposition surface of the auxiliary transition deposition platform is flush with the radial top of the tubular receiver. The distance between the auxiliary transition deposition platform and the tubular receiver is 2~10 mm.

[0010] Furthermore, the blade component is located on the side of the auxiliary transition deposition platform near the tubular receiver, the cutting edge height of the blade component is flush with the deposition surface of the auxiliary transition deposition platform, and the cutting edge of the blade component faces the tubular receiver; the included angle between the cutting edge of the blade component and the auxiliary transition deposition platform is 0°~5°.

[0011] A method for fabricating a melt near-field direct-write tubular scaffold based on an auxiliary transition platform device comprises the following steps:

[0012] (1) Preset receiving distance and axial addition: The receiving distance between the needle tip of the heating needle tube and the tubular receiver is adjusted in advance, and then a Y-axis motion device is added on the basis of the original X-axis motion device and R-axis motion device.

[0013] (2) Arrangement of auxiliary transition deposition platform: The auxiliary transition deposition platform is set in the lateral position of the tubular receiver, and the blade component is set on the side of the auxiliary transition deposition platform close to the tubular receiver.

[0014] (3) Program compilation and path integration: compile the main deposition path according to the structural pattern of the target tubular support, and compile the auxiliary transition path according to the relative positional relationship between the end position of the single-layer main deposition path and the starting position of the next layer; integrate the main deposition path and the auxiliary transition path into the same G-code control program.

[0015] (4) Main support path printing: Execute the main deposition path instruction in the G code control program, start the melt near-field direct writing device, and through the coordinated movement of the X-axis motion device and the R-axis motion device, make the melt near-field direct writing jet deposit layer by layer on the surface of the tubular receiver according to the preset deposition trajectory, and gradually build up the target tubular support main structure.

[0016] (5) Three-stage auxiliary transition path execution: After the single-layer main deposition path is executed to the preset end position, the G-code control program executes the auxiliary transition path. The auxiliary transition path includes an auxiliary platform deposition section, a platform switching and separation section, and a jet stabilization transition section.

[0017] In the auxiliary platform deposition section, the tubular receiver continues to move a preset distance along the axial direction, so that the relative position of the heating needle tip is away from the effective forming area of ​​the support; then, the receiving base translates along the Y-axis, so that the auxiliary transition deposition platform enters the area below the heating needle tip, and the continuous jet is deposited on the surface of the auxiliary transition deposition platform to form transition deposition fibers.

[0018] In the platform switching and separation section, the receiving base moves in the opposite direction, so that the receiving area below the needle tip of the heating needle tube is switched from the auxiliary transition deposition platform back to the tubular receiver side, and a bridging fiber is formed between the auxiliary transition deposition platform and the tubular receiver. The bridging fiber contacts the blade component and is cut off under the rotational traction of the tubular receiver, thereby realizing the separation of the auxiliary transition deposition fiber from the tubular support body.

[0019] In the jet stabilization transition section, the heated needle tip continues to move relative to the non-effective forming area of ​​the tubular receiver and prints according to the preset jet stabilization transition path, so that the jet returns to a stable stretching state before entering the next main deposition path.

[0020] (6) Path reset and cyclic printing: After the three-segment auxiliary transition path is completed, the G code control program executes the reset command to move the starting position of the next layer or the next deposition unit to below the heating needle tip and continue to execute the main deposition path; repeat steps (4) to (6) until the printing of the target tubular support is completed.

[0021] The above technical solution has the following beneficial effects:

[0022] (1) Constructing a planar non-substrate deposition area: By setting an auxiliary transition deposition platform on the side of the tubular receiver, a non-substrate deposition area similar to that in planar printing is formed during the tubular MEW printing process, so that non-target paths such as interlayer repositioning can be completed in the auxiliary area, thereby avoiding interference with the accumulation of the tubular scaffold main fiber.

[0023] (2) Achieve separation of transitional deposition fibers: By setting up an auxiliary transitional deposition platform, the transitional deposition fibers formed during the interlayer repositioning process are deposited outside the main structure of the tubular support, so as to avoid affecting the fiber arrangement and pore structure of the target support.

[0024] (3) Avoid local repeated deposition: This invention does not require repeating the existing main path to achieve repositioning, which can reduce the repeated superposition of local fibers and improve the structural uniformity and forming accuracy of the tubular support.

[0025] (4) Reduce the complexity of equipment modification: By adding a Y-axis control channel on the basis of the original X-R motion control system, the switching between the tubular receiver and the auxiliary transition deposition platform can be realized with only one independent motion axis added.

[0026] (5) Improve the adaptability of printing complex patterns: This invention is applicable to non-closed path patterns such as grid structure, negative Poisson structure, and serpentine structure, reducing the complexity of interlayer path replanning and improving the versatility and process controllability of melt near-field direct writing tubular support printing. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings:

[0028] Figure 1 A schematic diagram of an auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt.

[0029] Figure 2 A schematic diagram for an auxiliary transition platform;

[0030] Figure 3 This is a schematic diagram of a three-stage auxiliary transition path;

[0031] Figure 4 Topographical diagrams of the support structure printed for two path methods: repeated path return and auxiliary transition return.

[0032] The attached figures are labeled as follows: pneumatic device 1, high voltage power supply 2, tubular receiver 3, heating needle tube 4, insulating cover 5, heating collar 6, main control computer 7, controller 8, X-axis motion device 9, Y-axis motion device 10, R-axis rotation device 11, receiving base 12, auxiliary transition deposition platform 13, and blade component 131. Detailed Implementation

[0033] This invention aims to provide an auxiliary transition deposition apparatus and method for the fabrication of tubular scaffolds using near-field direct writing in melt. An auxiliary transition deposition platform is positioned laterally on the tubular receiver, constructing a transition deposition region independent of the main structure of the tubular scaffold. This region allows the transition deposition fibers formed during interlayer repositioning to complete their reception, truncation, and stable transition. The auxiliary transition deposition platform device achieves switching with the tubular receiver below the heating needle tip via a newly added Y-axis motion mechanism, thereby realizing spatial separation of the transition deposition fibers from the main scaffold and improving the structural integrity, morphological consistency, and forming accuracy of the tubular scaffold.

[0034] like Figure 1As shown, this embodiment provides an auxiliary transition deposition device for the fabrication of near-field direct-write tubular supports for melt, including a melt jet forming unit, a tubular receiver 3, an auxiliary transition deposition unit, and a multi-axis cooperative motion control unit. The melt jet forming unit includes a pneumatic device 1, a high-voltage power supply 2, and a printhead. The printhead is assembled from a heating needle tube 4, an insulating cover 5, and a heating ring 6. The heating needle tube 4 is located at the center of the printhead and is used to store and output molten polymer material; the heating ring 6 is located outside the heating needle tube 4 and is used to heat and melt the polymer material; the insulating cover 5 is located on the outermost side and is used to cover the heating needle tube 4 and the heating ring 6 to form a printhead structure with both insulation and heat preservation functions. The high-voltage power supply 2 is electrically connected to the heating needle tube 4 and is used to establish an electric field between the tip of the heating needle tube and the receiving area; the pneumatic device 1 is connected to the heating needle tube 4 and is used to apply air pressure to the molten material and drive its continuous extrusion. The tubular receiver 3, the printhead, and the multi-axis cooperative motion control unit are all connected to a main control computer 7 and controlled by the main control computer 7.

[0035] The tubular receiver 3 is installed on the receiving base 12 to carry and receive the polymer jet ejected from the needle tip of the heated needle tube 4 layer by layer, forming a tubular support structure under electrostatic traction.

[0036] The auxiliary transition deposition unit includes an auxiliary transition deposition platform 13 and a blade assembly 131, such as Figure 2 As shown. The auxiliary transition deposition platform 13 is also mounted on the receiving base 12, positioned laterally adjacent to the tubular receiver 3. Its length direction is parallel to the axial direction of the tubular receiver 3 (i.e., the X-axis direction), and its deposition surface is flush with the top outer surface of the tubular receiver 3 in the vertical direction. Specifically, the height of the auxiliary transition deposition platform 13 is 24 mm. The blade component 131 is located at the edge of the auxiliary transition deposition platform 13 near the tubular receiver 3, with its cutting edge height flush with the deposition surface of the auxiliary transition deposition platform 13 and facing the tubular receiver 3. The angle between the cutting edge of the blade component 131 and the receiving surface of the auxiliary transition deposition platform 13 is 0° to 5°. The distance between the auxiliary transition platform and the tubular receiver 3 is 2 to 10 mm, ensuring that the jet can be stably transferred from the tubular receiving area to the auxiliary transition deposition area, while avoiding mechanical interference due to too small a distance or fiber free stretching and displacement due to too large a distance, thus increasing the time required for stabilizing the jet.

[0037] The multi-axis coordinated motion control unit includes an X-axis motion device 9, a Y-axis motion device 10, an R-axis rotation device 11, and a controller 8. The X-axis motion device 9 drives the receiving base 12 to translate axially along the tubular receiver 3 (i.e., along the X-axis direction), the Y-axis motion device 10 drives the receiving base 12 to translate perpendicularly to the axial direction of the tubular receiver 3 (i.e., along the Y-axis direction), and the R-axis rotation device 11 drives the tubular receiver 3 to rotate around its own axis. The computer 7 coordinates the motion of each axis through the controller 8, enabling the receiving base 12 and the auxiliary transition deposition platform 13 to translate synchronously along a preset trajectory, and the tubular receiver 3 to rotate, thereby controlling the layer-by-layer deposition process of the jet on the surface of the tubular receiver 3.

[0038] The method for fabricating melt near-field direct-write tubular scaffolds using the above-mentioned auxiliary transition deposition apparatus includes the following steps:

[0039] (1) Preset receiving distance and axial addition: Before printing, the receiving distance between the heating needle 4 and the tubular receiver 3 is first adjusted by the original Z-axis lifting function to meet the requirements of stable jet deposition during the near-field direct writing of melt. After the receiving distance is preset, a Y-axis motion device 10 is added to the original X-R axis motion device, so that the control system can independently output the Y-axis translation command to realize the control of the Y-axis motion. In the above way, the X and R axis two-axis coordinated control in the original near-field direct writing tubular device of melt is converted into X, Y and R three-axis coordinated control. Thus, with the addition of an independent motion axis, the Y-axis translation motion is defined as the deposition area switching execution unit to realize the lateral switching between the tubular receiver 3 and the auxiliary transition deposition platform 13.

[0040] (2) Arrangement of auxiliary transition deposition platform 13: The auxiliary transition deposition platform 13 is set at a lateral position of the tubular receiver 3, and a preset distance of 2~10 mm is maintained between it and the tubular receiver 3 to avoid interfering with the axial translation and rotation of the tubular receiver 3; the length direction of the auxiliary transition deposition platform 13 is parallel to the axial direction of the tubular receiver 3, and its length is not less than the effective printing length of the tubular support, and its width covers the projection range of the interlayer return path in the Y-axis, and is used to receive the transition deposition fibers formed during the interlayer return process; the deposition surface of the auxiliary transition deposition platform 13 is flush with the height of the tubular receiver 3. Further, a blade component 131 is provided on the side of the auxiliary transition deposition platform 13 near the tubular receiver 3, and the cutting edge of the blade component 131 is flush with the deposition surface of the auxiliary transition deposition platform 13, and is used to cut off the bridging fibers formed between the tubular receiver 3 and the auxiliary transition deposition platform 13.

[0041] (3) Programming and path integration: Before the printing operation begins, a continuous G-code control program is pre-programmed to integrate the target tubular support main body deposition path and the three-stage auxiliary transition path into the same control program. Based on the target support structure and auxiliary transition requirements, key process parameters are preset, including the distance the tubular receiver 3 continues to move along the X-axis in the auxiliary platform deposition section, the distance the receiving base 12 moves in the Y direction, the moving speed of the receiving device in the auxiliary platform deposition section, the rotation speed of the R-axis during the switching process from the platform to the tubular receiver 3, and the duration of the jet stabilization transition section.

[0042] (4) Main support path printing: Execute the G code program to start the target tubular support main body deposition path instruction. Under the action of the high voltage power supply 2, the pneumatic device 1 squeezes the polymer melted in the heating needle tube 4 from the needle tip of the heating needle tube 4 to form a stable jet, which is deposited on the movable tubular receiver 3 to form the target tubular support structure.

[0043] (5) Three-stage auxiliary transition path execution: When the single-layer main deposition path reaches the end point of the preset deposition unit, the G-code control program automatically executes the three-stage auxiliary transition path, such as... Figure 3 As shown. The controller 8 synchronously drives the multi-axis cooperative motion control unit according to the instruction, causing the tubular receiver 3 to continue moving a preset buffer distance, preferably 5 mm, along the X-axis, so that the jet from the needle tip of the heated needle tube 4 leaves the effective forming area of ​​the support and enters the non-effective forming area. Subsequently, the receiving base 12 moves a preset distance, preferably 10 mm, along the Y-axis, so that the auxiliary transition deposition platform 13 enters the area below the needle tip, and the jet continuously formed at the needle tip is deposited on the surface of the auxiliary transition deposition platform 13. Further, the receiving base 12 moves in the opposite direction along the Y-axis, causing the jet to be drawn back from the auxiliary transition deposition platform 13 to the edge area of ​​the tubular receiver 3, forming a bridging fiber between the auxiliary transition deposition platform 13 and the tubular receiver 3. The bridging fiber contacts the blade component 131 under the traction generated by the rotation of the tubular receiver 3 and is passively cut off by the cutting edge of the blade component 131. After the bridging fiber is cut off, the needle tip continues to perform a jet stabilization transition section relative to the non-effective forming area of ​​the tubular receiver 3, so that the jet returns to a stable deposition state before entering the next main deposition path.

[0044] (6) Path Reset and Loop Printing: After completing the three auxiliary transition paths, the G-code program continues to execute subsequent reset instructions in sequence. The controller 8 drives the multi-axis cooperative motion control unit to execute the reset instruction, so that the starting position of the deposition unit moves back to below the print head, and then continues to execute the main deposition path of the next deposition unit.

[0045] (7) After each main deposition path is completed, repeat steps (4)–(6) above until the entire tubular scaffold is printed. After auxiliary transition path processing, as shown Figure 4 As shown, the transitional deposited fibers were guided to the auxiliary transition area, and no local layer height accumulation phenomenon occurred in the main area of ​​the tubular support. The fiber deposition state was stable, and the tube wall structure remained intact.

[0046] To further optimize the auxiliary transition effect, the parameters of the moving speed during the auxiliary transition process, the rotation speed of the tubular receiver 3 during the switching process from the platform to the tubular receiver 3, and the duration of the jet stable transition section can be optimized. Multiple sets of control samples are printed to evaluate the auxiliary transition deposition effect. The optimized auxiliary transition process parameters are determined by evaluating fiber morphology, interlayer alignment, and the occurrence rate of forming defects.

[0047] The present invention will be described in detail below with reference to specific embodiments:

[0048] Example 1

[0049] The following uses a grid structure as an example:

[0050] Before the printing operation begins, a continuous and seamless G-code control program is written, which integrates the target support body deposition path and the three-segment auxiliary transition path. Subsequently, based on the required support structure, key process parameters are preset in the control program, including the distance the tubular receiver 3 continues to move 5 mm in the X direction in the deposition section of the auxiliary transition deposition platform 13, the distance the receiving base 12 moves 10 mm in the Y direction, the moving speed of the receiving base 12 in the deposition section of the auxiliary transition deposition platform 13, the rotational speed of the R axis during the switching process from the auxiliary transition deposition platform 13 to the tubular receiver 3, and the duration of the jet stabilization transition section. The receiving distance between the needle part and the tubular receiver 3 is preset by adjusting the Z axis.

[0051] Execute the G-code program to initiate the target scaffold body deposition path instruction, and start printing the grid deposition unit scaffold according to the program instructions. Polycaprolactone material is used during the printing process. The temperature of the heating needle tube 4 is maintained at 85°C. The vertical distance between the needle tip and the tubular receiver 3 is 2.5 mm. The applied voltage is 4.2 kV, the applied air pressure is 0.65 MPa, and the printing speed is set to 280 mm / min.

[0052] After the single-layer main deposition path is printed and reaches the preset deposition unit end point, the G-code program automatically executes a three-stage auxiliary transition path instruction. The control unit drives the multi-axis coordinated motion control unit according to the code, causing the entire receiving device to move along the path set by the G-code program. After completing the three-stage auxiliary transition path, the G-code continues to execute subsequent instructions, driving the multi-axis coordinated motion control unit to reset, causing the starting position of the deposition unit to move back below the needle tip, and then continuing to execute the main deposition path of the next deposition unit. This cycle continues until the entire printing task is completed.

[0053] To optimize the process, after completing the printing and neutralization processes described above, the system can also explore parameters such as the moving speed during the transition return process, the rotational speed of the tubular receiver 3 during the switching process from the auxiliary transition deposition platform 13 to the tubular receiver 3, and the duration of the jet stabilization transition section. For example, the moving speed during the transition return process can be adjusted to the initial value, twice the speed, and three times the speed, respectively; the rotational speed of the tubular receiver 3 during the switching process from the auxiliary transition deposition platform 13 to the tubular receiver 3 can be adjusted to the initial value, twice the speed, and three times the speed; the duration of the jet stabilization section can be set to 0.5 times the printing time of the main deposition unit, 1 time the printing time of the main deposition unit, and 2 times the printing time of the main deposition unit. Multiple sets of control samples are printed to evaluate their fiber morphology, interlayer alignment, and other indicators, and finally, the optimal parameters that can maximize printing accuracy and stability are determined.

[0054] Through the above-described embodiments, the present invention successfully achieved high-precision printing of grid structure supports, demonstrating the effectiveness and practicality of this strategy in expanding the application scope of MEW technology methods, realizing the reception, cutting and jet stabilization control of redundant fibers, and improving the morphological consistency and molding quality of the support structure.

[0055] Example 2

[0056] The following uses a serpentine structure as an example:

[0057] Before the printing operation begins, a continuous and seamless G-code control program is written, which integrates the target support body deposition path and the three-segment auxiliary transition path. Subsequently, based on the required support structure, key process parameters are preset in the control program, including the distance the tubular receiver 3 continues to move 5 mm in the X direction in the deposition section of the auxiliary transition deposition platform 13, the distance the receiving base 12 moves 10 mm in the Y direction, the moving speed of the receiving base 12 in the deposition section of the auxiliary transition deposition platform 13, the rotation speed of the R axis during the switching process from the auxiliary transition deposition platform 13 to the tubular receiver 3, and the duration of the jet stabilization transition section. The receiving distance between the needle part and the tubular receiver 3 is also preset by adjusting the Z axis to a preset distance.

[0058] Execute the G-code program to initiate the target scaffold body deposition path instruction, and start printing the grid deposition unit scaffold according to the program instructions. Polycaprolactone material is used during the printing process. The temperature of the heating needle tube 4 is maintained at 85°C. The vertical distance between the needle tip and the tubular receiver 3 is 2.5 mm. The applied voltage is 4.2 kV, the applied air pressure is 0.65 MPa, and the printing speed is set to 280 mm / min.

[0059] After the single-layer main deposition path is printed and reaches the preset deposition unit end point, the G-code program automatically executes the three-stage auxiliary transition path instructions. The control unit drives the multi-axis coordinated motion control unit according to the code, causing the receiving base 12 to move along the path set by the G-code program. After completing the three-stage auxiliary transition path, the G-code continues to execute subsequent instructions, driving the multi-axis coordinated motion control unit to reset, causing the starting position of the deposition unit to move back below the needle tip, and then continuing to execute the main deposition path of the next deposition unit. This cycle continues until the entire printing task is completed.

[0060] To optimize the process, after completing the printing and neutralization processes described above, the system can also explore parameters such as the moving speed during the transition return process, the rotational speed of the tubular receiver 3 during the switching process from the auxiliary transition deposition platform 13 to the tubular receiver 3, and the duration of the jet stabilization transition section. For example, the moving speed during the transition return process can be adjusted to the initial value, twice the speed, and three times the speed, respectively; the rotational speed of the tubular receiver 3 during the switching process from the auxiliary transition deposition platform 13 to the tubular receiver 3 can be adjusted to the initial value, twice the speed, and three times the speed; the duration of the jet stabilization section can be set to 0.5 times the printing time of the main deposition unit, 1 time the printing time of the main deposition unit, and 2 times the printing time of the main deposition unit. Multiple sets of control samples are printed to evaluate their fiber morphology, interlayer alignment, and other indicators, and finally, the optimal parameters that can maximize printing accuracy and stability are determined.

[0061] Through the above-described embodiments, the present invention successfully achieved high-precision printing of serpentine structure supports, demonstrating the effectiveness and practicality of this strategy in expanding the application scope of MEW technology methods, realizing the reception, cutting and jet stabilization control of redundant fibers, and improving the morphological consistency and molding quality of the support structure.

[0062] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. An auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt, comprising a melt jet forming unit, a tubular receiver, and a multi-axis cooperative motion control unit, characterized in that: It also includes an auxiliary transition deposition unit, which serves as an auxiliary receiving area during the interlayer repositioning process; the auxiliary transition deposition unit includes an auxiliary transition deposition platform and a blade component connected to the auxiliary transition deposition platform, the auxiliary transition deposition platform is used to receive transition deposition fibers formed during the interlayer repositioning process, and the blade component is used to passively cut off the bridging fibers formed between the tubular receiving unit and the auxiliary transition deposition platform.

2. The auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt according to claim 1, characterized in that: The auxiliary transition deposition platform is located on one side of the tubular receiver and is arranged parallel to the axis of the tubular receiver. The deposition surface of the auxiliary transition deposition platform is flush with the radial top of the tubular receiver. The distance between the auxiliary transition deposition platform and the tubular receiver is 2~10 mm.

3. The auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt according to claim 1, characterized in that: The blade component is located on the side of the auxiliary transition deposition platform near the tubular receiver. The cutting edge height of the blade component is flush with the deposition surface of the auxiliary transition deposition platform, and the cutting edge of the blade component faces the tubular receiver. The included angle between the cutting edge of the blade component and the auxiliary transition deposition platform is 0° to 5°.

4. The auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt according to claim 1, characterized in that: The melt jet forming unit includes a high-voltage power supply, a pneumatic device, and a print head. The print head includes a heating needle tube, an insulating cover, and a heating ring. The heating needle tube is located at the center of the print head and is used to store and output molten polymer material. The heating ring is located outside the heating needle tube and is used to heat and melt the polymer material. The insulating cover is located on the outermost side of the print head. The high-voltage power supply is electrically connected to the heating needle tube, and the pneumatic device is connected to the heating needle tube.

5. The auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt according to claim 1, characterized in that: Both the tubular receiver and the auxiliary transition deposition platform are mounted on the receiver base.

6. The auxiliary transition deposition apparatus for near-field direct-write tubular scaffold fabrication of melt according to claim 1, characterized in that: The multi-axis coordinated motion control unit includes an X-axis motion device, a Y-axis motion device, an R-axis rotation device, and a controller. The X-axis motion device is used to drive the tubular receiver and the auxiliary transition deposition platform to translate along the X-axis. The Y-axis motion device is used to drive the tubular receiver and the auxiliary transition deposition platform to translate along the Y-axis. The R-axis rotation device is used to drive the tubular receiver to rotate around its own axis. The controller is used to coordinate and control the X-axis motion device, the Y-axis motion device, and the R-axis rotation device.

7. A method for fabricating a melt near-field direct-write tubular scaffold as described in any one of claims 1-6, characterized in that... The steps include: (1) Preset receiving distance and axial addition: Pre-adjust the receiving distance between the heating needle tip and the tubular receiver, and then add a Y-axis motion device on the basis of the original X-axis motion device and R-axis motion device; (2) Arrangement of auxiliary transition deposition platform: Set the auxiliary transition deposition platform in the lateral position of the tubular receiver, and set the blade component on the side of the auxiliary transition deposition platform close to the tubular receiver; (3) Program compilation and path integration: Compile the main deposition path according to the structural pattern of the target tubular support, and compile the auxiliary transition path according to the relative positional relationship between the end position of the single-layer main deposition path and the starting position of the next layer. The main deposition path and the auxiliary transition path are integrated into the same G-code control program; (4) Main support path printing: The main deposition path instruction in the G-code control program is executed to start the melt near-field direct writing printing process. The melt near-field direct writing jet is deposited layer by layer on the surface of the tubular receiver according to the preset structural path through the coordinated movement of the X-axis motion device and the R-axis motion device to form the target tubular support structure; (5) Three-stage auxiliary transition path execution: When the single-layer main deposition path is executed to the preset end position, the G-code control program executes the auxiliary transition path; the auxiliary transition path includes the auxiliary platform deposition section, the platform switching and separation section and the jet stabilization transition section; (6) Path reset and cyclic printing: After the three-stage auxiliary transition path is completed, the G-code control program executes the reset instruction to move the starting position of the next layer or the next deposition unit to below the needle part of the heating needle tube and continue to execute the main deposition path; repeat steps (4) to (6) until the printing of the target tubular support is completed.

8. The method for fabricating a melt near-field direct-write tubular scaffold according to claim 7, characterized in that: In step (2), the auxiliary transition deposition platform maintains a preset distance of 2-10 mm from the tubular receiver. The length direction of the auxiliary transition deposition platform is parallel to the axial direction of the tubular receiver, and its length is not less than the effective printing length of the tubular support. Its width covers the projection range of the interlayer return path in the Y-axis, and is used to receive the transition deposition fibers formed during the interlayer return process. The deposition surface of the auxiliary transition deposition platform is flush with the height of the tubular receiver. The cutting edge of the blade component is flush with the deposition surface of the auxiliary transition deposition platform.

9. The method for fabricating a melt near-field direct-write tubular scaffold according to claim 7, characterized in that: In step (3), preset parameters are included in the program, such as the length of the path of the auxiliary platform deposition section in the X-axis direction, the length of the path of the platform switching and cutting section in the Y-axis direction, the moving speed when executing the three-segment auxiliary transition path, and the duration of the jet stabilization transition section.

10. The method for fabricating a melt near-field direct-write tubular scaffold according to claim 6, characterized in that: Step (5) includes: in the auxiliary platform deposition section, the receiving base continues to move a preset distance along the axial direction of the tubular receiver, so that the relative position of the needle part of the heating needle tube leaves the effective forming area of ​​the support; subsequently, the receiving base translates along the Y-axis, so that the auxiliary transition deposition platform enters the area below the needle part of the heating needle tube, and the continuous jet is deposited on the surface of the auxiliary transition deposition platform to form transition deposition fibers; in the platform switching and cutting section, the receiving base translates in the opposite direction, so that the receiving area below the needle part of the heating needle tube is switched from the auxiliary transition deposition platform back to the side of the tubular receiver, and a bridging fiber is formed between the auxiliary transition deposition platform and the tubular receiver; the bridging fiber contacts the blade component and is cut off under the rotational traction of the tubular receiver, thereby realizing the separation of the auxiliary transition deposition fiber from the tubular support body; in the jet stabilization transition section, the needle part of the heating needle tube continues to move relative to the non-effective forming area of ​​the tubular receiver and prints according to the preset jet stabilization transition path, so that the jet recovers a stable stretching state before entering the next body deposition path.

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