A paper folding structure and a method of manufacturing a paper folding structure
By creating slots in the sheet substrate and utilizing an electrothermal structure, combined with 3D printing technology, the problems of low manufacturing efficiency and difficulty in controlling the folding direction in existing origami structures have been solved, enabling rapid and precise manufacturing of origami structures.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN JIAOTONG LIVERPOOL UNIV
- Filing Date
- 2026-06-05
- Publication Date
- 2026-07-21
AI Technical Summary
Existing technologies for manufacturing origami structures suffer from problems such as poor repeatability, low manufacturing efficiency, low crease accuracy, and difficulty in precisely controlling the folding direction. This is especially true for thin-walled origami structures, where the layer-by-layer stacking manufacturing method is time-consuming.
The first and second slots are made on the sheet substrate using 3D printing technology, and an electrothermal structure is set on the connecting layer. By generating heat by passing electricity through the connecting layer or embedding an electrothermal wire, the folding direction can be precisely controlled by utilizing the local stress concentration and bending stiffness difference caused by geometric asymmetry.
It significantly shortens the manufacturing time of complex origami structures, improves crease accuracy, and enables precise control of the folding direction without complex tools. The system is miniaturized and has a fast response time.
Smart Images
Figure CN122425888A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of additive manufacturing technology, and in particular to an origami structure and a method for manufacturing the origami structure. Background Technology
[0002] Shape memory polymers (SMPs) are polymeric materials with shape memory properties. In modern manufacturing, SMPs have been used to create origami structures through folding, and are commonly applied in soft actuators, mechanical metamaterials, and functional structures.
[0003] Regarding the manufacturing of origami structures, existing technologies mainly include the following two methods: The first is the traditional method of manually folding thin film materials. Although this method can form complex three-dimensional shapes, it suffers from problems such as poor repeatability, low manufacturing efficiency, low crease accuracy, difficulty in precisely controlling the folding direction, and difficulty in accurately forming complex crease patterns. The second method is to directly form origami structures using 3D printing technology. Although this method can manufacture complex structures, for thin-walled origami structures, the layer-by-layer manufacturing process is time-consuming.
[0004] Therefore, there is an urgent need to provide an origami structure and a method for manufacturing the origami structure to solve the above problems. Summary of the Invention
[0005] The purpose of this invention is to provide an origami structure and a method for manufacturing the origami structure, which significantly shortens the manufacturing time of complex origami structures, improves crease accuracy, and achieves precise control over the folding direction.
[0006] To achieve this objective, the present invention adopts the following technical solution: An origami structure is formed by folding a planar structure, the planar structure being formed by 3D printing, the planar structure including a sheet substrate having a first surface and a second surface disposed opposite to each other; A plurality of first slots are formed on the first surface. The depth of the first slots is less than the thickness of the sheet substrate. A first connecting layer is formed at the bottom of the first slot. The first connecting layer connects the sheet substrate on both sides of the first slot. The second surface has a plurality of second slots, which are staggered with the first slots. The depth of the second slots is less than the thickness of the sheet substrate. A second connecting layer is formed at the bottom of the second slot. The second connecting layer connects the sheet substrate on both sides of the second slot. The sheet substrate can be bent around the first connecting layer and toward the opening of the first slot, and can also be bent around the second connecting layer and toward the opening of the second slot.
[0007] As an optional solution, along the length direction of the first slot, the first connecting layer is provided with a plurality of spaced first through holes, and the plurality of first through holes divide the first connecting layer to form a plurality of first connecting arms; Along the length of the second slot, the second connecting layer is provided with a plurality of spaced second through holes, which divide the second connecting layer into a plurality of second connecting arms.
[0008] As an optional solution, both the first connecting layer and the second connecting layer are provided with an electrothermal structure, which is configured to generate heat when energized, so as to heat up and soften the first connecting layer and the second connecting layer.
[0009] As an alternative, the electrothermal structure is a conductive paste, and the surface and periphery of the first connecting layer and the surface and periphery of the second connecting layer are coated with the conductive paste, which can form a continuous conductive circuit.
[0010] As an optional solution, the heating structure is a heating wire, and the heating wire is embedded in both the first connecting layer and the second connecting layer along the length direction.
[0011] As an optional solution, the depth of the first slot is 70% to 80% of the thickness of the sheet substrate; and / or The depth of the second slot is 70% to 80% of the thickness of the sheet substrate.
[0012] A method for manufacturing an origami structure, comprising the following steps: Step S10: Using shape memory polymer as substrate, the planar structure corresponding to the target origami structure is printed using 3D printing technology. When printing the sheet substrate, the first slot is formed at a preset position on the first surface and the first connecting layer is retained, and the second slot is formed at a preset position on the second surface and the second connecting layer is retained. Step S20: After printing is completed, an external excitation is applied to cause the sheet substrate to bend around the first connecting layer and toward the opening direction of the first slot, and around the second connecting layer and toward the opening direction of the second slot, ultimately forming the target origami structure.
[0013] As an optional solution, step S10 further includes: during printing, integrating an electrothermal structure on the first connecting layer and the second connecting layer; In step S20, applying external excitation includes applying external force and energizing the electrothermal structure. When energized, the electrothermal structure generates heat to heat up and soften the first connecting layer and the second connecting layer.
[0014] As an optional solution, the electrothermal structure is a conductive paste; Step S10 specifically includes: printing the planar structure using a dual-nozzle 3D printer. The dual-nozzle 3D printer includes a first nozzle and a second nozzle. The first nozzle is used to print the sheet substrate, and the second nozzle is used to deposit the conductive paste on the surface and periphery of the first connecting layer and the surface and periphery of the second connecting layer, respectively.
[0015] As an optional solution, the electrothermal structure is a heating wire; Step S10 specifically includes: when printing the sheet substrate, inserting and embedding the heating wire in each of the first connecting layer and each of the second connecting layers, so that the heating wire is arranged along the length direction of the first connecting layer and the second connecting layer.
[0016] The beneficial effects of this invention are: This invention provides an origami structure formed by folding a planar structure. The planar structure includes a sheet substrate with a first surface and a second surface disposed opposite to each other. By forming a first slot on the first surface and a second slot on the second surface, the first and second slots weaken the local cross-sectional stiffness of the sheet substrate. Stress concentration is easily generated at the first and second slots, so deformation first appears in the slots. Moreover, the bending resistance is weaker on the opening side of the first and second slots. Therefore, when an external excitation is applied, the bending of the sheet substrate toward the opening direction of the first slot and the opening direction of the second slot will be preferentially promoted. That is, the sheet substrate naturally bends toward the opening direction of the first slot and the opening direction of the second slot, where the stiffness is weakest. The above method significantly reduces the manufacturing time of thin-walled complex structures, by about one-tenth compared to direct 3D printing of origami structures, and improves crease accuracy. Based on the target crease position, a slot with a depth less than the sheet thickness is made at the crease position of the sheet substrate. The slots are staggered on the first and second surfaces of the sheet according to the target crease direction, which uniquely determines the folding direction after the external excitation is applied, thereby achieving precise control of the folding direction. This method utilizes the local stress concentration and bending stiffness difference caused by geometric asymmetry to achieve the goal of controllable folding direction without complex tools. This principle does not depend on a specific crease pattern and can be widely applied to various origami structures.
[0017] The present invention also provides a method for manufacturing an origami structure, which can significantly shorten the manufacturing time of complex origami structures, improve crease accuracy, and utilize the local stress concentration and bending stiffness differences caused by geometric asymmetry to achieve the purpose of controllable folding direction without complex tools. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of a planar structure provided in an optional embodiment of the present invention; Figure 2 This is a schematic diagram of a first planar structure provided in an optional embodiment of the present invention; Figure 3 This is a schematic diagram of an origami structure formed by folding a first planar structure, provided in an optional embodiment of the present invention; Figure 4 This is a schematic diagram of another origami structure formed by folding a first planar structure, provided in an optional embodiment of the present invention; Figure 5 This is a schematic diagram of a second planar structure provided in an optional embodiment of the present invention; Figure 6 This is a schematic diagram of an origami structure formed by folding a second planar structure, provided in an optional embodiment of the present invention; Figure 7 This is a schematic diagram of a third planar structure provided in an optional embodiment of the present invention; Figure 8 This is a schematic diagram of an origami structure formed by folding a third planar structure, provided in an optional embodiment of the present invention; Figure 9 This is a schematic diagram of conductive paste integrated on a planar structure according to an optional embodiment of the present invention; Figure 10 This is a schematic diagram of promoting the bending of a planar structure after applying current to conductive paste, provided by an optional embodiment of the present invention; Figure 11 This is a schematic diagram of an optional embodiment of the present invention, showing an integrated heating wire on a planar structure. Figure 12 This is a schematic diagram of promoting the bending of a planar structure after the heating wire is energized, according to an optional embodiment of the present invention.
[0019] In the picture: 100. Origami structure; 10. Planar structure; 20. Dual-nozzle 3D printer; 201. First nozzle; 202. Second nozzle; 1. Sheet substrate; 101. First surface; 102. Second surface; 11. First slot; 12. First connecting layer; 121. First connecting arm; 13. Second slot; 14. Second connecting layer; 141. Second connecting arm; 15. First through hole; 16. Second through hole; 2. Electrothermal structure; 21. Conductive paste; 211. Conductive wire; 22. Heating wire. Detailed Implementation
[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0022] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0024] Example 1 This embodiment provides an origami structure 100, which is formed by folding a planar structure 10. The planar structure 10 is formed by printing using a 3D printer based on FDM (Fused Deposition Modeling) technology.
[0025] Specifically, such as Figure 1As shown, the planar structure 10 includes a sheet substrate 1, which is made of shape memory polymer. The sheet substrate 1 has a first surface 101 and a second surface 102 disposed opposite to each other. A plurality of first slots 11 are formed on the first surface 101, the depth of the first slots 11 being less than the thickness of the sheet substrate 1. A first connecting layer 12 is formed at the bottom of the first slots 11, and the first connecting layer 12 connects the sheet substrates 1 on both sides of the first slots 11. A plurality of second slots 13 are formed on the second surface 102. The second slot 13 and the first slot 11 are staggered. The depth of the second slot 13 is less than the thickness of the sheet substrate 1. A second connecting layer 14 is formed at the bottom of the second slot 13, connecting the sheet substrate 1 on both sides of the second slot 13. The first slot 11 and the second slot 13 are connected at both ends along their length. The sheet substrate 1 can be bent around the first connecting layer 12 and toward the opening direction of the first slot 11, and can also be bent around the second connecting layer 14 and toward the opening direction of the second slot 13. Optionally, the cross-section of the first slot 11 and the second slot 13 can be square or inverted isosceles trapezoid, without specific limitation.
[0026] First, based on the origami structure 100 to be formed, the origami structure 100 is unfolded into a planar structure 10 with creases in dedicated software. According to the target crease position and the target folding direction, the distribution of the first slot 11 and the second slot 13 is determined, thereby determining the 3D printing path of the planar structure 10. According to the 3D printing path, the granular or filament shape memory polymer is melt-deposited on the forming platform by the 3D printer to form a two-dimensional sheet substrate 1. During the printing of the sheet substrate 1, the first slot 11 is formed at the preset crease position on the first surface 101 and the first connecting layer 12 is retained, and the second slot 13 is formed at the preset crease position on the second surface 102 and the second connecting layer 14 is retained. The first slot 11 and the second slot 13 are staggered. After printing, by applying external excitation, the sheet substrate 1 can be folded at the positions of the first slot 11 and the second slot 13 in the target folding direction. That is, the sheet substrate 1 tends to bend around the first connecting layer 12 and towards the opening direction of the first slot 11, and around the second connecting layer 14 and towards the opening direction of the second slot 13, and finally forms the target origami structure 100.
[0027] The first slot 11 and the second slot 13 weaken the local cross-sectional stiffness of the sheet substrate 1. Stress concentration is easily generated at the first slot 11 and the second slot 13, so deformation will first appear at the slot position. Moreover, the bending resistance of the opening side of the first slot 11 and the second slot 13 is weaker. Therefore, when an external excitation is applied, the bending of the sheet substrate 1 toward the opening direction of the first slot 11 and the bending toward the opening direction of the second slot 13 will be preferentially promoted. That is, the sheet substrate 1 naturally bends toward the opening direction of the first slot 11 and the opening direction of the second slot 13 where the stiffness is weakest, thereby determining the folding direction after the external excitation is applied.
[0028] The above method significantly shortens the manufacturing time of thin-walled complex structures, reducing it to about one-tenth compared to direct 3D printing of origami structure 100. It also improves crease accuracy. Based on the target crease position, a slot with a depth less than the thickness of the sheet substrate 1 is made at the crease position. The slots are misaligned on the first surface 101 and the second surface 102 of the sheet substrate 1 according to the target crease direction. This uniquely determines the folding direction after applying external excitation, thereby achieving precise control of the folding direction. This method utilizes the local stress concentration and bending stiffness differences caused by geometric asymmetry to achieve the goal of controllable folding direction without complex tools. This principle does not depend on a specific crease pattern and can be widely applied to various types of origami structures 100.
[0029] In an optional embodiment, such as Figure 1 As shown, along the length of the first slot 11, the first connecting layer 12 has a plurality of spaced first through holes 15, which divide the first connecting layer 12 into a plurality of first connecting arms 121; along the length of the second slot 13, the second connecting layer 14 has a plurality of spaced second through holes 16, which divide the second connecting layer 14 into a plurality of second connecting arms 141. By constructing the first connecting layer 12 as a plurality of first connecting arms 121 and the second connecting layer 14 as a plurality of second connecting arms 141, the sheet substrate 1 is easier to bend towards the opening direction of the first slot 11 and towards the opening direction of the second slot 13, thereby achieving precise control of the folding direction.
[0030] In one optional embodiment, the depth of the first slot 11 is 70% to 80% of the thickness of the sheet substrate 1. In another optional embodiment, the depth of the second slot 13 is 70% to 80% of the thickness of the sheet substrate 1. In this embodiment, the depths of the first slot 11 and the second slot 13 are preferably the same, but they can also be different, as long as they are within the above-mentioned ratio range. This embodiment uses the example of the same depth for illustration.
[0031] Example 1: The total thickness of the sheet substrate 1 can be 1.2 mm, the depth of both the first slot 11 and the second slot 13 can be 0.9 mm, and a 0.3 mm thick base material is reserved as the first connecting layer 12 and the second connecting layer 14. The minimum width of both the first slot 11 and the second slot 13 can be selected as 0.5 mm. Example 2: The total thickness of the sheet substrate 1 can be 1.0 mm, the depth of both the first slot 11 and the second slot 13 can be 0.7 mm, and a 0.3 mm thick base material is reserved as the first connecting layer 12 and the second connecting layer 14. The minimum width of both the first slot 11 and the second slot 13 can be 0.3 mm. Example 3: The total thickness of the sheet substrate 1 can be 1.0 mm, the depth of both the first slot 11 and the second slot 13 can be 0.8 mm, and a 0.2 mm thick base material is reserved as the first connecting layer 12 and the second connecting layer 14. The minimum width of both the first slot 11 and the second slot 13 can be 0.4 mm.
[0032] This application has verified that the above-described planar structure 10 can be applied to various origami structures 100. Example 1, such as... Figure 2 As shown, this is the first planar structure 10 provided in this embodiment. Folding this planar structure 10 can form a shape as shown in the figure. Figure 3 The origami structure 100 shown is also called a Creslin structure, and can also be formed as follows: Figure 4 The origami structure 100 shown is an example. Example 2, as... Figure 5 As shown, this is the second planar structure 10 provided in this embodiment. The planar structure 10 has four pairs of opposing first surfaces 101 and second surfaces 102. Folding the planar structure 10 can form a shape as shown in the figure. Figure 6 The origami structure shown is 100. Example 3, as shown... Figure 7 As shown, this is the third planar structure 10 provided in this embodiment, which can be folded to form the following... Figure 8 The origami structure 100 is shown.
[0033] In the existing technology, external excitation is mainly applied to the sheet substrate 1 by external driving devices (such as pneumatic drive, external heat sources such as hot air guns, ovens, etc.), which requires continuous energy supply and large external equipment, resulting in large system size and slow response speed.
[0034] To address the aforementioned issues, in one optional embodiment, such as Figure 9 and Figure 10As shown, the planar structure 10 also includes an electrothermal structure 2. Both the first connecting layer 12 and the second connecting layer 14 are equipped with the electrothermal structure 2. The electrothermal structure 2 is configured to generate heat when energized, thereby heating and softening the first connecting layer 12 and the second connecting layer 14. By integrating the electrothermal structure 2 onto the first connecting layer 12 and the second connecting layer 14, both the planar structure 10 and the final origami structure 100 possess self-heating capabilities, eliminating dependence on external heat sources and achieving system miniaturization and rapid response. It should be noted that since the structures on the first connecting layer 12 and the second connecting layer 14 are identical, therefore... Figure 9 and Figure 10 Only the structure of the first connecting layer 12 is shown in the diagram.
[0035] The above configuration utilizes the temperature response characteristics of SMP (shape memory polymer). When the temperature is higher than the glass transition temperature Tg of SMP, SMP softens (rubber state) and can undergo directional controllable folding deformation along a preset slot under external force. When the temperature drops below Tg, SMP hardens (glass state), and the shape of the origami structure 100 formed after deformation is locked. It can maintain its shape without continuous energy supply. Reheating can soften SMP and restore its original planar structure 10. Through temperature control, functions such as reversible deformation and stiffness adjustment can be achieved.
[0036] In an optional embodiment, such as Figure 9 and Figure 10As shown, the electrothermal structure 2 is a conductive paste 21. The surface and periphery of the first connecting layer 12 and the surface and periphery of the second connecting layer 14 are coated with the conductive paste 21, ensuring its continuity and forming a continuous conductive circuit. When the conductive circuit is energized, it generates heat, causing the first connecting layer 12 and the second connecting layer 14 to soften. This makes it easier for the sheet substrate 1 to bend towards the opening direction of the first slot 11 and towards the opening direction of the second slot 13, thereby achieving precise control of the folding direction. The conductive paste 21 can be selected from copper paste, silver-copper composite paste, etc. In this embodiment, a dual-nozzle 3D printer 20 is used to print a planar structure 10 and achieve automated deposition of conductive paste 21. The dual-nozzle 3D printer 20 includes a first nozzle 201 and a second nozzle 202. During the printing process, the first nozzle 201 is used to print the sheet substrate 1, and the second nozzle 202 is used to extrude the conductive paste 21 and deposit it on the surface and periphery of the first connecting layer 12 and the surface and periphery of the second connecting layer 14, respectively, to form a conductive circuit. Conductive wires 211 extend from both ends of the conductive paste 21. When the conductive wires 211 are energized, the conductive circuit formed by the conductive paste 21 generates Joule heat, causing the temperature of the first connecting layer 12 and the second connecting layer 14 to rise above the glass transition temperature Tg of the SMP. The material enters a highly elastic state and softens. With the assistance of a slight external force, the sheet substrate 1 can be folded in the target folding direction to form an origami structure 100. After the power is turned off, the origami structure 100 cools at room temperature for about 30 seconds, and the temperature drops below Tg. The origami structure 100 hardens and is stably locked in the folded state. After being energized and heated again for about 20 seconds, the origami structure 100 can be restored to the planar structure 10 of the initial unfolded state.
[0037] In another alternative embodiment, such as Figure 11 and Figure 12 As shown, the heating structure 2 is a heating wire 22, and the first connecting layer 12 and the second connecting layer 14 are both embedded with heating wires 22 along their length. When the heating wire 22 is energized, it generates heat, causing the first connecting layer 12 and the second connecting layer 14 to heat up and soften, making it easier for the sheet substrate 1 to bend towards the opening direction of the first slot 11 and towards the opening direction of the second slot 13, thereby achieving precise control of the folding direction. During the printing of the sheet substrate 1, heating wires 22 are inserted and embedded between each first connecting arm 121 of each first connecting layer 12, and between each second connecting arm 141 of each second connecting layer 14, so that the heating wires 22 are arranged along the length direction of the first connecting layer 12 and the second connecting layer 14. By inserting heating wires 22 into the first connecting layer 12 and the second connecting layer 14, the Joule heat generated by the energization can also be used to heat and soften the first connecting layer 12 and the second connecting layer 14, achieving a change in state, which will not be elaborated further here.
[0038] Example 2 This embodiment provides a method for manufacturing an origami structure, used to manufacture the origami structure 100 in Embodiment 1. The specific steps include: Step S10: Using shape memory polymer as substrate, 3D printing technology is used to print the planar structure 10 corresponding to the target origami structure 100. When printing the sheet substrate 1, a first slot 11 is formed at a preset position on the first surface 101 and a first connecting layer 12 is retained, and a second slot 13 is formed at a preset position on the second surface 102 and a second connecting layer 14 is retained. Step S20: After printing is completed, an external excitation is applied to cause the sheet substrate 1 to bend around the first connecting layer 12 and toward the opening direction of the first slot 11, and around the second connecting layer 14 and toward the opening direction of the second slot 13, ultimately forming the target origami structure 100.
[0039] Specifically, firstly, based on the origami structure 100 to be formed, the origami structure 100 is unfolded into a planar structure 10 with creases in dedicated software. According to the target crease position and the target folding direction, the distribution of the first slot 11 and the second slot 13 is determined, thereby determining the 3D printing path of the planar structure 10. According to the 3D printing path, the shape of the granular or filament material is melted and deposited onto the forming platform by the 3D printer to form a two-dimensional sheet substrate 1. During the printing of the sheet substrate 1, the first slot 11 is formed at the preset crease position on the first surface 101 and the first connecting layer 12 is retained, and the second slot 13 is formed at the preset crease position on the second surface 102 and the second connecting layer 14 is retained. The first slot 11 and the second slot 13 are staggered. After printing, by applying external excitation, the sheet substrate 1 can be folded at the positions of the first slot 11 and the second slot 13 in the target folding direction. That is, the sheet substrate 1 tends to bend around the first connecting layer 12 and towards the opening direction of the first slot 11, and around the second connecting layer 14 and towards the opening direction of the second slot 13, and finally forms the target origami structure 100.
[0040] It should be noted that the first slot 11 and the second slot 13 weaken the local cross-sectional stiffness of the sheet substrate 1. Stress concentration is easily generated at the first slot 11 and the second slot 13, so deformation will first appear at the slot position. Moreover, the bending resistance of the opening side of the first slot 11 and the second slot 13 is weaker. Therefore, when an external excitation is applied, the bending of the sheet substrate 1 towards the opening direction of the first slot 11 and the bending towards the opening direction of the second slot 13 will be preferentially promoted. That is, the sheet substrate 1 naturally bends towards the opening direction of the first slot 11 and the opening direction of the second slot 13, where the stiffness is weakest, thereby determining the folding direction after the external excitation is applied.
[0041] The above method significantly shortens the manufacturing time of thin-walled complex structures, reducing it to about one-tenth compared to direct 3D printing of origami structure 100. It also improves crease accuracy. Based on the target crease position, a slot with a depth less than the thickness of the sheet substrate 1 is opened at the crease position. The slots are misaligned on the first surface 101 and the second surface 102 of the sheet substrate 1 according to the target crease direction. This uniquely determines the folding direction after applying external excitation, thereby achieving precise control of the folding direction. This method utilizes the local stress concentration and bending stiffness differences caused by geometric asymmetry to achieve the goal of controllable folding direction without complex tools. This principle does not depend on a specific crease pattern and can be widely applied to various types of origami structures 100.
[0042] In an optional embodiment, the selected SMP material is a polyurethane-based shape memory polymer with a glass transition temperature (Tg) of 60°C. The printing layer height can be set to 0.2 mm, the printing speed to 30 mm / s, the print head temperature to 220°C, the total thickness of the sheet substrate 1 to 1.0 mm, the depth of the first slot 11 and the second slot 13 to 0.8 mm, a 0.2 mm thick bottom layer material is reserved as the first connecting layer 12 and the second connecting layer 14, and the minimum width of the first slot 11 and the second slot 13 to 0.4 mm. After printing, the sheet substrate 1 can be placed in a heating environment to raise the temperature to 80°C, which is higher than the glass transition temperature (Tg) of the material, causing the material to soften. Utilizing the local stress concentration caused by the geometric asymmetry of the slots, by applying external tensile or compressive forces, the planar structure 10 is rapidly and precisely folded along the preset slots, transforming into the desired three-dimensional origami structure 100. After the origami structure 100 is cooled to room temperature (approximately 25°C) and locked, the compressive modulus changes from approximately 50 MPa in the unfolded state to approximately 200 MPa in the folded state, thus realizing the function of adjusting the mechanical stiffness through the folded state. It should be noted that the solution in this embodiment is the solution without the electric heating structure 2.
[0043] In an optional embodiment, step S10 may further include: during printing, integrating the electrothermal structure 2 onto the first connecting layer 12 and the second connecting layer 14; in step S20, applying external excitation includes applying external force assistance and energizing the electrothermal structure 2. The energized electrothermal structure 2 generates heat, causing the first connecting layer 12 and the second connecting layer 14 to heat up and soften. Then, applying external force assistance allows the planar structure 10 to be quickly and precisely folded along a preset slot. By integrating the electrothermal structure 2 onto the first connecting layer 12 and the second connecting layer 14, both the planar structure 10 and the final origami structure 100 possess self-heating capabilities, eliminating dependence on external heat sources and achieving system miniaturization and rapid response.
[0044] In an optional embodiment, such as Figure 9 and Figure 10 As shown, the electrothermal structure 2 is conductive paste 21; step S10 specifically includes: printing the planar structure 10 using a dual-nozzle 3D printer 20. The dual-nozzle 3D printer 20 includes a first nozzle 201 and a second nozzle 202. The first nozzle 201 is used to print the sheet substrate 1, and the second nozzle 202 is used to deposit the conductive paste 21 onto the surface and periphery of the first connecting layer 12 and the surface and periphery of the second connecting layer 14, respectively. In this embodiment, polycaprolactone-based shape memory polymer can be used as the material of the sheet substrate 1, with a glass transition temperature Tg of 55°C. The total thickness of the sheet substrate 1 can be set to 1.0 mm, the depth of the first slot 11 and the second slot 13 can be set to 0.7 mm, and a 0.3 mm thick bottom layer material is retained as the first connecting layer 12 and the second connecting layer 14. The width of the first slot 11 and the second slot 13 can be set to 0.3 mm. When using a dual-nozzle 3D printer 20, the first nozzle 201 (diameter selectable 0.4mm) is responsible for printing the sheet substrate 1, with the printing temperature set to 210℃ and the printing speed set to 25mm / s. The second nozzle 202 (diameter selectable 0.2mm) is responsible for applying the conductive paste 21 (optional silver-copper composite conductive paste, with a volume resistivity of approximately 5×10⁻⁶). -5 Ω·cm) is directly deposited on the surface and periphery of the first connecting layer 12 and the surface and periphery of the second connecting layer 14 to form a continuous conductive circuit.
[0045] During operation, a 12V operating voltage is applied to the conductive circuit through the conductive wires 211 at both ends, generating a current of approximately 1A to 1.5A. Joule heating rapidly raises the temperature of the first connecting layer 12 and the second connecting layer 14 to approximately 70°C (above Tg), causing the material to enter a highly elastic state and soften. With the assistance of a slight external force (approximately 1N to 3N), the sheet substrate 1 can be folded according to the target folding direction to form the origami structure 100. After power is turned off, the origami structure 100 cools at room temperature (approximately 25°C) for approximately 30 seconds, and the temperature drops below Tg. The origami structure 100 hardens and is stably locked in the folded state. Upon reheating for approximately 20 seconds, the origami structure 100 returns to its initial unfolded planar structure 10. This embodiment achieves a rapid response of the self-heating origami structure 100, with a heating response time of approximately 15 to 20 seconds, requiring no external heat source, and exhibiting high system integration.
[0046] In another alternative embodiment, such as Figure 11 and Figure 12As shown, the heating structure 2 is a heating wire 22; step S10 specifically includes: when printing the sheet substrate 1, inserting and embedding the heating wire 22 into each first connecting layer 12 and each second connecting layer 14, so that the heating wire 22 is arranged along the length direction of the first connecting layer 12 and the second connecting layer 14. In this embodiment, an epoxy-based shape memory polymer can be used as the material of the sheet substrate 1, with a glass transition temperature Tg of 75°C. The total thickness of the sheet substrate 1 can be set to 1.2 mm, the depth of the first slot 11 and the second slot 13 can be set to 0.9 mm, and a 0.3 mm thick bottom layer material is retained as the first connecting layer 12 and the second connecting layer 14. The width of the first slot 11 and the second slot 13 can be set to 0.5 mm. During the printing process, the heating wire 22 is inserted and embedded along the length direction in the first connecting layer 12 and the second connecting layer 14. The heating wire 22 can be selected as a nickel-chromium alloy heating wire with a diameter of 0.1 mm and a resistivity of approximately 1.5 × 10⁻⁶. -6 The heating wire 22 embedded in each connecting layer is approximately 20 mm long and has a single wire resistance of approximately 3 Ω·m.
[0047] During operation, a current of 0.5A to 1.5A (voltage approximately 1.5V to 4.5V) is applied to the heating wire 22, causing the temperature of the first connecting layer 12 and the second connecting layer 14 to rise to approximately 85°C, and the material enters a highly elastic state and softens. With the assistance of a slight external force (approximately 5N), the sheet substrate 1 can be folded according to the target folding direction to form an origami structure 100. After power is turned off, the origami structure 100 cools at room temperature (approximately 25°C) for approximately 30 seconds, and the temperature drops below Tg. The origami structure 100 hardens and is stably locked in the folded state. Due to the change in geometry, the macroscopic compressive modulus of the structure changes from approximately 80MPa in the unfolded state to approximately 350MPa in the folded state, and the load-bearing capacity increases from approximately 50N in the unfolded state to approximately 120N in the folded state. Re-energizing the origami structure 100 restores the initial unfolded planar structure 10.
[0048] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A paper-folding structure, characterized in that, Formed by folding a planar structure (10) by 3D printing, the planar structure (10) includes a sheet substrate (1) having a first surface (101) and a second surface (102) disposed opposite to each other. A plurality of first slots (11) are provided on the first surface (101). The depth of the first slots (11) is less than the thickness of the sheet substrate (1). A first connecting layer (12) is formed at the bottom of the first slots (11). The first connecting layer (12) connects the sheet substrate (1) on both sides of the first slots (11). The second surface (102) has a plurality of second slots (13), the second slots (13) and the first slots (11) are staggered, the depth of the second slots (13) is less than the thickness of the sheet substrate (1), a second connecting layer (14) is formed at the bottom of the second slots (13), the second connecting layer (14) connects the sheet substrates (1) on both sides of the second slots (13), the sheet substrates (1) can be bent around the first connecting layer (12) and toward the opening direction of the first slot (11), and can be bent around the second connecting layer (14) and toward the opening direction of the second slots (13).
2. The origami structure according to claim 1, characterized in that, Along the length direction of the first slot (11), the first connecting layer (12) is provided with a plurality of spaced first through holes (15), and the plurality of first through holes (15) divide the first connecting layer (12) to form a plurality of first connecting arms (121). Along the length direction of the second slot (13), the second connecting layer (14) is provided with a plurality of spaced second through holes (16), and the plurality of second through holes (16) divide the second connecting layer (14) to form a plurality of second connecting arms (141).
3. The origami structure according to claim 1, characterized in that, Both the first connecting layer (12) and the second connecting layer (14) are provided with an electric heating structure (2). The electric heating structure (2) is configured to generate heat after being energized, so as to heat up and soften the first connecting layer (12) and the second connecting layer (14).
4. The origami structure according to claim 3, characterized in that, The electrothermal structure (2) is a conductive paste (21). The surface and periphery of the first connecting layer (12) and the surface and periphery of the second connecting layer (14) are coated with the conductive paste (21). The conductive paste (21) can form a continuous conductive circuit.
5. The origami structure according to claim 3, characterized in that, The heating structure (2) is a heating wire (22), and the heating wire (22) is embedded in both the first connecting layer (12) and the second connecting layer (14) along the length direction.
6. The origami structure according to claim 1, characterized in that, The depth of the first slot (11) is 70% to 80% of the thickness of the sheet substrate (1); and / or The depth of the second slot (13) is 70% to 80% of the thickness of the sheet substrate (1).
7. A method for manufacturing an origami structure, characterized in that, The steps for manufacturing the origami structure as described in any one of claims 1 to 6 include: Step S10: Using shape memory polymer as substrate, the planar structure (10) corresponding to the target origami structure is printed using 3D printing technology. When printing the sheet substrate (1), the first slot (11) is formed at a preset position on the first surface (101) and the first connecting layer (12) is retained, and the second slot (13) is formed at a preset position on the second surface (102) and the second connecting layer (14) is retained. Step S20: After printing is completed, an external excitation is applied to make the sheet substrate (1) bend around the first connecting layer (12) and toward the opening direction of the first slot (11), and bend around the second connecting layer (14) and toward the opening direction of the second slot (13), so as to finally form the target origami structure.
8. The method for manufacturing the origami structure according to claim 7, characterized in that, Step S10 further includes: during printing, integrating an electrothermal structure (2) on the first connecting layer (12) and the second connecting layer (14); In step S20, applying external excitation includes applying external force and energizing the electrothermal structure (2). After being energized, the electrothermal structure (2) can generate heat to heat up and soften the first connecting layer (12) and the second connecting layer (14).
9. The method for manufacturing the origami structure according to claim 8, characterized in that, The electrothermal structure (2) is a conductive paste (21); Step S10 specifically includes: printing the planar structure (10) using a dual-nozzle 3D printer (20). The dual-nozzle 3D printer (20) includes a first nozzle (201) and a second nozzle (202). The first nozzle (201) is used to print the sheet substrate (1), and the second nozzle (202) is used to deposit the conductive paste (21) on the surface and periphery of the first connecting layer (12) and the surface and periphery of the second connecting layer (14), respectively.
10. The method for manufacturing the origami structure according to claim 8, characterized in that, The electrothermal structure (2) is a heating wire (22); Step S10 specifically includes: when printing the sheet substrate (1), inserting and embedding the heating wire (22) into each of the first connecting layer (12) and each of the second connecting layer (14) so that the heating wire (22) is arranged along the length direction of the first connecting layer (12) and the second connecting layer (14).