4D printing device with adjustable line section

Abstract

The invention belongs to the technical field of additive manufacturing, and discloses a line section adjustable 4D printing device which comprises a first driving unit, a second driving unit, an FDM printing head and a base plate. The first driving unit is connected with the substrate and is used for driving the substrate to move in a horizontal plane; the second driving unit is connected with a moving plate and is used for driving the moving plate to lift and move; a third driving unit is mounted on the moving plate and is provided with an output shaft which is vertically and downwards placed; the FDM printing head is connected to the lower end of the output shaft, and the third driving unit is used for driving the FDM printing head to rotate around the central axis of the output shaft; the FDM printing head is located above the base plate, and the end face of the lower end of the nozzle is in an inclined slope shape. The problem that in the prior art, due to the fact that asymmetric stress distribution in a structure is difficult to directly encode in the printing process, a simple two-dimensional printing path cannot be autonomously and permanently converted into a complex three-dimensional configuration according to a preset program through single heat treatment is effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a 4D printing device with adjustable line cross-section. Background Technology

[0002] Additive manufacturing (also known as 3D printing) is an advanced manufacturing technology that shapes components by depositing materials layer by layer. Among them, fused deposition modeling (FDM) is widely used due to its low equipment cost and wide applicability of materials. In recent years, 4D printing technology based on smart materials has developed rapidly. It can further introduce a fourth dimension into the physical structure formed by 3D printing, which changes in shape and performance with time or environmental stimuli (such as heat, humidity, and light), providing new manufacturing approaches for fields such as adaptive structures and flexible robots.

[0003] Currently, most 4D printing methods based on FDM technology rely on the responsiveness of smart materials such as shape memory polymers to external stimuli. However, the deformation behavior of these methods is mainly limited by the material's own physicochemical properties, typically exhibiting overall symmetrical contraction or expansion, making it difficult to achieve localized, programmable complex deformations. More importantly, such stimulus-response deformations are often reversible; that is, when the external stimulus is removed, the structure tends to revert to its initial shape, making it impossible to obtain permanent, pre-defined complex three-dimensional configurations.

[0004] Furthermore, in existing FDM 4D printing based on shape memory polymers, to achieve specific deformations, it is often necessary to pre-deform the printed structure using external mechanical force, and then "lock" the deformation through methods such as cooling. This method is not only cumbersome and difficult to control precisely, but the deformation mode is also limited by the pre-deformation method, making it difficult to achieve the deformation effect of directly "growing" complex three-dimensional space from a simple two-dimensional path. This limits the application potential of 4D printing in the manufacturing of customized and functional structures. Therefore, existing technologies have the problem of not being able to directly encode the asymmetric stress distribution inside the structure during the printing process, resulting in the inability to autonomously and permanently transform a simple two-dimensional printing path into a complex three-dimensional configuration according to a preset program through a single heat treatment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a 4D printing device with adjustable line cross-sections, which solves the problem in existing technologies that it is difficult to directly encode the asymmetric stress distribution inside the structure during the printing process, resulting in the inability to autonomously and permanently transform a simple two-dimensional printing path into a complex three-dimensional configuration through a single heat treatment.

[0006] The objective of this invention can be achieved through the following technical solutions: An adjustable 4D printing apparatus includes a first drive unit, a second drive unit, an FDM print head, and a substrate for supporting the printed components and controlling the temperature. The first driving unit is connected to the substrate and is used to drive the substrate to move in a horizontal plane. The second drive unit is connected to a movable plate and is used to drive the movable plate to move up and down. A third drive unit is mounted on the movable plate, and the third drive unit has an output shaft that is placed vertically downwards. The FDM printhead is connected to the lower end of the output shaft of the third drive unit, which is used to drive the FDM printhead to rotate around the central axis of the output shaft. The FDM printhead is located above the substrate, with the nozzle of the FDM printhead positioned vertically downwards and the lower end face of the nozzle being inclined.

[0007] Furthermore, the angle between the lower end face of the nozzle and the horizontal plane ranges from 15° to 45°. Furthermore, the internal flow channel of the nozzle located above the lower inclined surface is cylindrical or a frustum-shaped structure with a diameter that gradually narrows from top to bottom.

[0008] Furthermore, the third drive unit is a servo motor or a stepper motor, and the output shaft of the third drive unit is placed coaxially with the nozzle.

[0009] Furthermore, the third drive unit has a hollow channel coaxial with the output shaft, through which the polymer filament for printing passes from the top and extends into the FDM printhead.

[0010] Furthermore, the first driving unit includes a base plate, on which a horizontally placed first linear driving component is mounted. A first slider is fitted on the first linear driving component. The first linear driving component is used to drive the first slider to move axially along the first linear driving component. A horizontally placed second linear driving component is fixedly mounted on the upper end of the first slider. A second slider is fitted on the second linear driving component. The second linear driving component is used to drive the second slider to move axially along the second linear driving component. The first linear driving component and the second linear driving component are perpendicular to each other. A substrate is mounted on the upper end of the second slider.

[0011] Furthermore, the substrate is detachably connected to the second slider.

[0012] Furthermore, the second drive unit includes a third linear drive component fixedly mounted on the base plate. The third linear drive component is placed vertically upward, and a third slider is provided on the third linear drive component. The third linear drive component is used to drive the third slider to move up and down. The connecting plate is fixedly connected to the third slider.

[0013] The beneficial effects of this invention are: This invention, building upon the substrate planar movement and printhead lifting achieved by the first and second drive units, adds a third drive unit capable of rotating around a vertical axis and employs a nozzle with an inclined lower end. This allows for real-time control of the direction of the extruded material flow and its deposition and spreading behavior on the substrate by adjusting the rotation angle of the third drive unit during printing. This results in a cross-sectional shape of a single printed line after curing that is no longer the symmetrical shape of traditional processes, but rather an asymmetrical structure that can be dynamically adjusted according to the rotation angle. When subsequently heated, this asymmetrical cross-section generates directional internal stress differences due to inconsistent shrinkage behavior in different areas, thereby driving predictable and complex spatial deformation of the printed structure. This method overcomes the limitations of existing 4D printing technologies that rely on the intrinsic response of smart materials or require pre-deformation by external mechanical forces. It achieves the ability to "encode" the microstructure of the lines simply by adjusting the spatial posture and motion parameters of the nozzle during printing, ultimately programmatically controlling the permanent deformation morphology of the macrostructure. This provides a novel solution for manufacturing adaptive deformable components that is simple to process, offers rich deformation possibilities, and allows for high design freedom. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 These are schematic diagrams of the overall structure of the present invention from different perspectives; Figure 3 This is a partial structural diagram of the hollow channel of the present invention; Figure 4 This is a schematic diagram of the third drive unit and part of the FDM printhead structure of the present invention; Figure 5 This is an appendix to the present invention. Figure 4 A magnified view of the structure at point A in the middle; Figure 6 This is a schematic diagram of the experimental results of Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the experimental results of Embodiment 2 of the present invention; Figure 8 This is a schematic diagram of the experimental results of Embodiment 2 of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figures 1 to 7 As shown, a 4D printing device with adjustable line cross-section includes a first drive unit 100, a second drive unit 200, an FDM print head 300, and a substrate 400 for carrying the printed components and controlling the temperature. The first driving unit 100 is connected to the substrate 400 and is used to drive the substrate 400 to move in a horizontal plane. The second drive unit 200 is connected to a movable plate 500 and is used to drive the movable plate 500 to move up and down. A third drive unit 600 is mounted on the movable plate 500. The third drive unit 600 has an output shaft 601 that is placed vertically downward. The FDM printhead 300 is connected to the lower end of the output shaft 601 of the third drive unit 600. The third drive unit 600 is used to drive the FDM printhead 300 to rotate around the central axis of the output shaft 601. The FDM printhead 300 is located above the substrate 400. The nozzle 301 of the FDM printhead 300 is placed vertically downwards, and the lower end face of the nozzle 301 is inclined. The 4D printing apparatus with adjustable line cross-section provided by this invention, based on the planar movement of the substrate 400 and the lifting and lowering of the print head achieved by the first drive unit 100 and the second drive unit 200, adds a third drive unit 600 that can rotate around a vertical axis, and uses a nozzle 301 with an inclined end face at the lower end. Therefore, during the printing process, the direction of the extruded material flow and its deposition and spreading behavior on the substrate 400 can be changed in real time by controlling the rotation angle of the third drive unit 600. This results in the cross-sectional shape of a single printed line after curing no longer being the symmetrical shape of traditional processes, but rather a non-symmetrical shape that can be dynamically adjusted according to the rotation angle. The asymmetric cross-section, when heated, will generate directional internal stress differences due to the inconsistent shrinkage behavior of different regions of the cross-section, thereby driving the printed structure to undergo predictable and complex spatial deformation. This method breaks through the limitations of existing 4D printing technologies that rely on the intrinsic response of smart materials or require pre-deformation by external mechanical forces. It enables the microstructure of lines to be "encoded" simply by adjusting the spatial posture and motion parameters of the nozzle 301 during the printing process, and ultimately programmatically controls the permanent deformation morphology of the macrostructure. This provides a new solution for manufacturing adaptive deformable components that is simple in process, rich in deformation, and has a high degree of design freedom.

[0018] It should be noted that the FDM printhead 300 typically includes an extrusion motor, a heating block, and a throat assembly; the extrusion motor clamps and pushes the printing filament through a gear or extrusion wheel mechanism; the filament then enters the throat and is conveyed into the heating block; the heating block has built-in heating elements and temperature sensors, which can precisely heat the filament to a molten state; finally, the molten material is extruded through a nozzle 301 with a specific structure connected to the lower end of the heating block under the extrusion pressure, and deposited on the substrate 400 to complete the printing.

[0019] The substrate 400 is a temperature-controlled substrate 400 with temperature control function. The substrate 400 integrates heating elements (such as silicone heating film, resistance wire, etc.) and temperature sensors (such as thermocouples, thermistors), and is connected to an external temperature control circuit, enabling the setting, monitoring, and closed-loop adjustment of the working temperature of the printing area. By stably maintaining the temperature of the substrate 400 within the molding temperature range required by the printing material (e.g., approximately 50-60℃ for PLA and approximately 90-110℃ for ABS), defects such as component warping and poor interlayer adhesion caused by temperature asymmetry or excessive heat dissipation during printing can be effectively reduced. Especially when using temperature-sensitive smart materials such as shape memory polymers, it provides crucial process assurance for the dimensional stability of the printed structure, interlayer bonding strength, and subsequent controllable thermal deformation behavior.

[0020] The angle between the lower end face of nozzle 301 and the horizontal plane ranges from 15° to 45°; this avoids the problems of increased extrusion resistance, uneven discharge, or insufficient strength of nozzle tip that may be caused by an excessively steep slope (>45°), and also prevents the defects of weak cross-section control effect and difficulty in achieving effective deformation programming due to an excessively gentle slope (<15°).

[0021] The internal flow channel of nozzle 301 located above the inclined surface at the lower end is cylindrical or frustum-shaped with its diameter gradually decreasing from top to bottom; Cylindrical flow channels maintain a constant material flow cross-section, avoiding abrupt changes in flow resistance, thus ensuring a smooth and continuous extrusion process and reducing surface defects caused by uneven flow rates. Conversely, frustum-shaped flow channels with gradually decreasing diameters from top to bottom apply symmetrically increasing extrusion pressure to the material through the gentle contraction of the flow channel cross-section, further promoting the consistency of melt plasticization and molecular chain orientation, and enhancing the overall stability and morphological controllability of the extruded material flow. Both structural designs aim to establish an orderly and predictable internal flow field before the material reaches the inclined exit, thereby significantly improving the accuracy and repeatability of the asymmetric morphology of the printed line cross-section, laying a reliable process foundation for subsequent programmed complex deformation through heat treatment.

[0022] The third drive unit 600 is a servo motor or a stepper motor, and the output shaft 601 of the third drive unit 600 is placed on the same axis as the nozzle 301. Servo motors or stepper motors can achieve high-resolution angle control and fast response, ensuring accurate positioning and dynamic adjustment of the nozzle 301 rotation angle during printing. At the same time, the coaxial arrangement of the output shaft 601 and the nozzle 301 avoids additional motion errors and vibrations caused by axis misalignment, thereby ensuring the stability and repeatability of the extrusion trajectory during high-speed rotation and start-stop, providing a reliable motion execution basis for precise control of the line cross-sectional shape through real-time rotation.

[0023] The third drive unit 600 has a hollow channel 602 that is coaxial with the output shaft 601. The polymer filament 700 for printing passes through the hollow channel 602 from the top and extends into the FDM print head 300. The hollow channel 602 allows the polymer filament 700 (solid filament) to pass directly through the inside of the third drive unit 600 and be fed into the FDM printhead 300, avoiding tangling, bending or jamming of the filament during rotation. This ensures the continuity and stability of filament feeding at any rotation angle, fundamentally solving the problem of feeding interruption that may occur in long-term, complex trajectory printing of rotary printheads, and significantly improving the process reliability of the equipment. Preferably, the polymer filament 700 can be made of shape memory materials such as polyurethane.

[0024] The first driving unit 100 includes a base plate 101, on which a horizontally placed first linear drive 102 is mounted. A first slider 103 is fitted on the first linear drive 102. The first linear drive 102 is used to drive the first slider 103 to move along the axial direction of the first linear drive 102. A horizontally placed second linear drive 104 is fixedly mounted on the upper end of the first slider 103. A second slider 105 is fitted on the second linear drive 104. The second linear drive 104 is used to drive the second slider 105 to move along the axial direction of the second linear drive 104. The first linear drive 102 and the second linear drive 104 are perpendicular to each other. A base plate 400 is mounted on the upper end of the second slider 105. The first linear drive 102, the first slider 103, the second linear drive 104, and the second slider 105 together form an XY dual-axis slide table, so as to drive the substrate 400 to adjust its position in the horizontal plane.

[0025] The substrate 400 is detachably connected to the second slider 105; Preferably, the substrate 400 can be detachably connected to the second slider 105 via bolts; the detachable connection structure facilitates quick replacement or maintenance of the substrate 400 by the user, adapts to the needs of printing platforms of different sizes, materials or surface characteristics, improves the flexibility and ease of operation of the equipment, and provides practical support for cleaning, calibration and multi-task continuous printing.

[0026] The second drive unit 200 includes a third linear drive component 201 fixedly installed on the base plate 101. The third linear drive component 201 is placed vertically upward. A third slider 202 is provided on the third linear drive component 201. The third linear drive component 201 is used to drive the third slider 202 to move up and down. The connecting plate is fixedly connected to the third slider 202. Preferably, the first linear drive 102, the second linear drive 104, and the third linear drive 201 can all be selected from linear motors, lead screw and nut mechanisms, or synchronous belt drive mechanisms, etc.

[0027] This application provides three embodiments to further verify and illustrate the 4D printing apparatus of this application; Example 1 Printing was performed on the aforementioned device using thermoplastic polyurethane (TPU) filaments; the basic printing parameters were set as follows: printing speed V = 10 mm / s, extrusion rate V of the extrusion motor in the FDM printhead 300. e = 10mm / s, Nozzle 301 temperature T t = 210℃ and substrate temperature 400T b = 20℃; such as Figure 6 As shown, the output shaft 601 is rotated by the third drive unit 600, with rotation angles ω of 0°, 90°, and 170° respectively, printing 60mm lines. First, the cross-section of each line is captured using a stereomicroscope to photograph its morphology. Then, the printed lines are heat-treated at 80°C for 5 minutes, resulting in different forms of deformation, and the deformed shapes are permanent. The deformed appearance is then scanned using a 3D scanner. Furthermore, since the material is transparent, to better demonstrate its properties, the printed lines are coated with a mixture of Rhodamine B and varnish (Rhodamine B content 1%). After fluorescence treatment, the red appearance of the lines is photographed in a dark environment using a camera equipped with a red light-transmitting film, as shown in the figure. This experiment clearly demonstrates that during the rotation of the output shaft 601 driven by the third drive unit 600, the cross-sectional shapes extruded from the inclined nozzle 301 onto the substrate 400 can achieve the initial symmetrical "semi-circle," asymmetrical "triangle," asymmetrical "concave," and symmetrical "concave" shapes. For ease of description, a three-dimensional coordinate system is established with the axis of the first linear drive 102 as the X-axis, the axis of the second linear drive 104 as the Y-axis, the axis of the third linear drive 201 as the Z-axis, and the intersection of the axes of the first linear drive 102 and the third linear drive 201 as the origin. These lines with different cross-sections exhibit different deformation modes after being heated due to the stress release caused by their internal molecular chains. In order, they are bent in the plane xoz, spiral bending in space, bent in the plane xoy, and bent in the plane xoz (to a greater extent). This demonstrates that the oblique nozzle 301 can control the shape of the line cross-section by adjusting the rotation angle during the printing process, thereby changing the deformation mode.

[0028] Example 2 To further demonstrate the innovation of this paper, the present invention designs the effect of nozzles 301 with different tilted end faces and rotation angles on the deformation of printed lines; Thermoplastic polyurethane (TPU) filaments were also used for printing on the aforementioned device; the basic printing parameters were set as follows: printing speed V = 10 mm / s, extrusion rate Ve of the extrusion motor in the FDM printhead 300 = 10 mm / s, and nozzle temperature T. t =210℃ and substrate temperature 400T b = 20℃; such as Figure 7 As shown, for nozzles 301 with the same tilt angle, the bending radius gradually decreases with increasing rotation angle, while the lifting height initially increases and then decreases back to 0. During the change of the tilt angle of nozzle 301 from 15° to 45°, the bending radius increases while the lifting height decreases. This example demonstrates how the tilt angle of nozzle 301, in conjunction with rotation, alters the deformation pattern and degree of the printed lines. Example 3 like Figure 8 As shown, in order to further demonstrate the innovation of this paper, two demonstration experiments were designed to transform a single straight line into a complex configuration. For the first method, the basic printing parameters are set as follows: V = 10mm / s, V e = 10mm / s, T t = 210℃ and Tb = 20℃; when the first section is printed 30mm, the Z-axis rotation angle ω1 = 170°; when the second section is printed 30mm, the Z-axis rotation angle ω2 = 205°; For the second type, the basic printing parameters are also designed as follows: V = 10mm / s, V e = 10mm / s, T t = 210℃ and T b= 20℃; When the first section is printed 30mm, the Z-axis rotation angle ω1 = 180°; When the second section is printed 30mm, the Z-axis rotation angle ω2 = 70°; Next, the printed lines are heat-treated at 80℃ for 5 minutes. The deformed shape is shown in the 3D scan and fluorescence image. By adjusting the parameters during the printing process, more complex deformations can be achieved, such as... Figure 8 It demonstrates complex transformations, such as straight lines transforming into "S" shapes.

[0029] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A 4D printing apparatus with adjustable line cross-section, comprising a first drive unit (100), a second drive unit (200), an FDM print head (300), and a substrate (400) for supporting the printed component and controlling its temperature, characterized in that: The first driving unit (100) is connected to the substrate (400) and is used to drive the substrate (400) to move in a horizontal plane; The second drive unit (200) is connected to a movable plate (500) and is used to drive the movable plate (500) to move up and down; A third drive unit (600) is mounted on the movable plate (500), and the third drive unit (600) has an output shaft (601) placed vertically downward. The FDM printhead (300) is connected to the lower end of the output shaft (601) of the third drive unit (600). The third drive unit (600) is used to drive the FDM printhead (300) to rotate around the central axis of the output shaft (601). The FDM printhead (300) is located above the substrate (400). The nozzle (301) of the FDM printhead (300) is placed vertically downward, and the end face of the lower end of the nozzle (301) is inclined.

2. The 4D printing device with adjustable line cross-section according to claim 1, characterized in that, The angle between the lower end face of the nozzle (301) and the horizontal plane ranges from 15° to 45°.

3. The 4D printing device with adjustable line cross-section according to claim 1, characterized in that, The nozzle (301) has an internal flow channel located above the inclined surface at the lower end. It is cylindrical or frustum-shaped with the diameter gradually decreasing from top to bottom.

4. The 4D printing device with adjustable line cross-section according to claim 1, characterized in that, The third drive unit (600) is a servo motor or a stepper motor, and the output shaft (601) of the third drive unit (600) is placed coaxially with the nozzle (301).

5. The 4D printing device with adjustable line cross-section according to claim 4, characterized in that, The third drive unit (600) has a hollow channel (602) placed coaxially with the output shaft (601) inside. The polymer filament (700) for printing passes through the hollow channel (602) from the top and extends into the FDM print head (300).

6. The 4D printing device with adjustable line cross-section according to claim 1, characterized in that, The first driving unit (100) includes a base plate (101), on which a horizontally placed first linear drive (102) is mounted. A first slider (103) is fitted on the first linear drive (102). The first linear drive (102) is used to drive the first slider (103) to move axially along the first linear drive (102). A horizontally placed second linear drive (104) is fixedly mounted on the upper end of the first slider (103). A second slider (105) is fitted on the second linear drive (104). The second linear drive (104) is used to drive the second slider (105) to move axially along the second linear drive (104). The first linear drive (102) and the second linear drive (104) are perpendicular to each other. A base plate (400) is mounted on the upper end of the second slider (105).

7. The 4D printing apparatus with adjustable line cross-section according to claim 6, characterized in that, The substrate (400) is detachably connected to the second slider (105).

8. The 4D printing apparatus with adjustable line cross-section according to claim 7, characterized in that, The second drive unit (200) includes a third linear drive component (201) fixedly installed on the base plate (101). The third linear drive component (201) is placed vertically upward. A third slider (202) is provided on the third linear drive component (201). The third linear drive component (201) is used to drive the third slider (202) to move up and down. The connecting plate is fixedly connected to the third slider (202).

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