Manufacturing method of paper folding structure based on mold sacrifice

Abstract

The invention discloses a manufacturing method of a paper folding structure based on mold sacrifice, which comprises the following steps: mold preparation: constructing a 3D model of a sacrifice mold according to a target paper folding structure, printing layer by layer by using a plane projection micro-stereolithography technology, curing while printing, and forming a required sacrifice mold in a layer-by-layer printing mode; cleaning the mold: after the sacrificial mold is printed, soaking the sacrificial mold in a cleaning solution to remove uncured resin, and carrying out secondary curing; casting molding of a flexible material: selecting two-component platinum silica gel as a molding material, and slowly filling a cavity with mixed silica gel along an opening of the mold through an injector; and solidification of the mixed silica gel and removal of the sacrificial mold: after filling of the mixed silica gel is completed, standing is conducted at normal temperature, and after standing is completed, the sacrificial mold is dissolved through a dissolving solution so as to expose the formed target origami structure. The whole process is stable, the structure morphology is well kept, and the method is suitable for research, development and application of micro flexible structures, soft robots and the like.

Description

Technical Field

[0001] The present application relates to the technical field of flexible devices, and particularly relates to a manufacturing method of an origami structure based on mold sacrifice. Background Art

[0002] The origami structure is a typical axisymmetric origami unit, composed of alternately arranged mountain creases and valley creases, and has excellent compressibility, geometric stability, and mechanical response characteristics, and is widely used in deformable structure design, flexible electronics, space deployable structures, and intelligent drive systems. In recent years, with the rapid development of miniaturized systems and soft robots, the soft origami structure has gradually become a research hotspot. This structure combines the traditional Kresling geometric form with flexible materials, and has the advantages of light weight, high compliance, and structural reconfigurability, and is particularly suitable for deformable structure design and integrated deployment in small-scale environments.

[0003] However, most of the existing origami structure manufacturing methods at present are for rigid structures at the mesoscale or even macroscale, and mainly adopt methods such as laser cutting, numerical control machining, manual folding, or hierarchical assembly. These methods have a certain feasibility when making Kresling structures of hard materials such as paper and plastic sheets, but when facing origami structures composed of millimeter-scale and soft materials, there are the following significant technical bottlenecks:

[0004] 1. It is difficult to reduce the structure scale: As the structure size is reduced to the millimeter level, it is difficult for traditional machining or manual folding to form clear and continuous crease structures, resulting in the structure being unable to be precisely closed or deformed repeatedly.

[0005] 2. It is difficult to process flexible materials: Soft materials usually have low stiffness and strong ductility, and it is difficult to maintain the stability of the crease position under the existing preparation methods, and it is easy to warp, tear, or be unable to self-support.

[0006] 3. Three-dimensional forming is limited: The Kresling structure has complex three-dimensional folding geometry, and existing methods are difficult to complete the continuous conversion from a two-dimensional pattern to a complete three-dimensional structure at a small scale, resulting in its soft version being unable to be effectively constructed at a small size. Summary of the Invention

[0007] The present application aims to solve one of the above technical problems in the prior art. To this end, an embodiment of the present application provides a manufacturing method of an origami structure based on mold sacrifice.

[0008] According to an embodiment of the present application, there is provided a manufacturing method of an origami structure based on mold sacrifice, including the following steps:

[0009] Mold preparation: A 3D model of the sacrificial mold is constructed according to the target origami structure. The surface projection micro-stereolithography technology is used to print layer by layer and cure while printing. The required sacrificial mold is formed by layer-by-layer printing. Among them, the printing material is selected as photosensitive resin, and the sacrificial mold has a cavity for forming the target origami structure;

[0010] Mold cleaning: After the sacrificial mold is printed, the sacrificial mold is immersed in the cleaning solution to remove the uncured resin remaining on the surface of the sacrificial mold. After the sacrificial mold is cleaned, a light-curing device is used to perform secondary curing on the sacrificial mold;

[0011] Casting and molding of flexible materials: Two-component platinum silicone is selected as the molding material and mixed in a mass ratio of 1:1 for component A and component B. The mixed silicone is slowly filled into the cavity along the opening of the mold through a syringe;

[0012] Solidification of the mixed silicone and removal of the sacrificial mold: After the mixed silicone is filled, the sacrificial mold is placed at room temperature and left standing for 7 to 9 hours. After standing, a dissolving solution is used to dissolve the sacrificial mold to expose the formed target origami structure.

[0013] The above method for manufacturing an origami structure based on mold sacrifice has at least the following beneficial effects: The manufacturing method of this application can reliably construct a soft origami structure at the millimeter scale. By constructing a sacrificial mold and using flexible materials for casting and molding, and finally removing the mold by chemical dissolution, a complete soft Kresling three-dimensional structure can be obtained. The entire process is stable, and the structural morphology is well maintained, which is suitable for the research and development and application of various flexible devices such as micro flexible structures and soft robots.

[0014] According to the method for manufacturing an origami structure based on mold sacrifice described in the embodiments of the present application, the PμSL system used in the surface projection micro-stereolithography technology includes an ultraviolet LED light source, a DMD chip, a projection optical unit, and a Z-axis platform. Among them, the ultraviolet LED light source is used for curing the resin, the DMD chip dynamically regulates the illumination pattern according to the sliced image, and the pattern is reduced and projected onto the resin surface through the projection optical unit. The Z-axis platform is used to support the printed sacrificial mold.

[0015] According to the method for manufacturing an origami structure based on mold sacrifice described in the embodiments of the present application, the reference value of the exposure parameters of the ultraviolet LED light source is set to a light intensity of 35 - 45 mW / cm 2 , and the wavelength range of the ultraviolet light emitted by the ultraviolet LED light source is 365 - 405 nm.

[0016] According to the method for manufacturing an origami structure based on mold sacrifice described in the embodiments of the present application, during the printing process, the Z-axis platform completes layer-by-layer release and fluid replenishment according to the four-step cycle of "moving down, staying, moving up, staying".

[0017] According to the manufacturing method of the origami structure based on sacrificial mold of the embodiments of the present application, the first printed layer uses 4.0 s of exposure to enhance adhesion, the single-layer exposure time of the remaining printed layers is 1.5 s, and the layer thickness of each printed layer is set to 20 μm.

[0018] According to the manufacturing method of the origami structure based on sacrificial mold of the embodiments of the present application, the downward movement distance of the Z-axis platform is 4 mm, the downward movement stay time is 1 s, the upward movement distance is 3.98 mm, and the upward movement stay time is 0.2 to 0.8 s.

[0019] According to the manufacturing method of the origami structure based on sacrificial mold of the embodiments of the present application, the cleaning liquid is a fluorinated liquid, wherein the soaking duration is 6 to 8 hours.

[0020] According to the manufacturing method of the origami structure based on sacrificial mold of the embodiments of the present application, the temperature of the secondary curing is set to 80 °C, and the curing time for each surface of the formed sacrificial mold is 30 minutes.

[0021] According to the manufacturing method of the origami structure based on sacrificial mold of the embodiments of the present application, the dissolving liquid is prepared from sodium hydroxide and distilled water according to a mass ratio of 5:95.

[0022] According to the manufacturing method of the origami structure based on sacrificial mold of the embodiments of the present application, the dissolving process is carried out in a closed container and at 80 °C, and the dissolving lasts for 8 hours.

[0023] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0024] The following further illustrates the present application with reference to the drawings and embodiments;

[0025] Figure 1 is a schematic structural view of the sacrificial mold of the embodiments of the present application Figure 1 ;

[0026] Figure 2 is a schematic structural view of the sacrificial mold in the embodiments of the present application Figure 2 ;

[0027] Figure 3 is a schematic view of the origami structure in the embodiments of the present application.

[0028] Reference numerals: sacrificial mold 100, first body 110, second body 120, channel 121, cavity 130, origami structure 200, first connecting body 210, flexible connecting portion 220, deformation cavity 221. Detailed implementation manners

[0029] This section will describe in detail the specific embodiments of the present application. The preferred embodiments of the present application are shown in the drawings. The role of the drawings is to supplement the description in the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present application. However, it should not be construed as a limitation on the protection scope of the present application.

[0030] In the description of the present application, it should be understood that for orientation descriptions, such as up, down, front, back, left, right, etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the present application.

[0031] In the description of the present application, the meaning of "several" is one or more, the meaning of "multiple" is two or more, "greater than", "less than", "exceeding", etc. are understood not to include the recited number, and "above", "below", "within", etc. are understood to include the recited number. If there is a description of "first" and "second", it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0032] In the description of the present application, unless otherwise clearly defined, words such as "set", "installed", "connected", etc. should be understood in a broad sense. Those skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0033] Referring to Figure 3 , the origami structure 200 of the embodiment of the present application includes a flexible connection part 220 and two first connection bodies 210. The two first connection bodies 210 are connected by the flexible connection part 220. Among them, the flexible connection part 220 is cylindrical and has a deformation cavity 221. The outer surface of the flexible connection part 220 is provided with creases, and a reinforcing strip is arranged inside the creases. A through hole communicating with the flexible connection part 220 is arranged in the middle of the first connection body 210.

[0034] The height of the origami structure 200 provided by the present application is 7 mm, the height of the flexible connection part 220 is 5 mm, the thickness of the first connection body 210 is 1 mm, and the thickness of the reinforcing strip is 0.15 mm.

[0035] To enable the casting of Figure 3 the origami structure 200, as Figure 1 and Figure 2As shown, the present application also provides a sacrificial mold 100, so that a complete soft Kresling three-dimensional structure can be obtained by constructing the sacrificial mold 100 and casting with a flexible material, and finally removing the mold by chemical dissolution.

[0036] Among them, the sacrificial mold 100 includes a first mold body 110 and a second mold body 120. The first mold body 110 is provided with a cavity 130, and the cavity wall of the cavity 130 is adapted to the outer surface of the origami structure 200. The second mold body 120 is arranged in the middle of the cavity 130. The shape of the outer surface of the second mold body 120 is adapted to the shape of the inner surface of the origami structure 200, and a channel 121 for forming a reinforcing strip is arranged at the corresponding position of the outer surface of the second mold body 120.

[0037] The manufacturing method of the origami structure 200 based on mold sacrifice of the present application includes the following steps:

[0038] Mold preparation: Construct a 3D model of the sacrificial mold 100 according to the target origami structure 200, and use the surface projection microstereolithography technology to print layer by layer and cure while printing. The required sacrificial mold 100 is formed by layer-by-layer printing. Among them, the printing material is selected as photosensitive resin, and the sacrificial mold 100 has a cavity 130 for forming the target origami structure 200.

[0039] Adopt the surface projection microstereolithography (PμSL) technology to construct a high-precision sacrificial mold 100 for the origami structure 200. This technology combines the advantages of traditional stereolithography (SLA) and digital light processing (DLP). By using a digital micromirror device (DMD) to project a two-dimensional pattern onto the surface of the photosensitive resin, rapid and precise layer-by-layer curing is achieved, which is suitable for the manufacture of micro-scale complex structures.

[0040] The PμSL system used in the surface projection microstereolithography technology includes an ultraviolet LED light source, a DMD chip, a projection optical unit, and a Z-axis platform. Among them, the ultraviolet LED light source is used for curing the resin. The DMD chip dynamically adjusts the illumination pattern according to the sliced image, and projects the pattern onto the resin surface after reducing it through the projection optical unit. The Z-axis platform is used to support the printed sacrificial mold 100.

[0041] During the printing process, the Z-axis platform completes layer-by-layer separation and fluid replenishment according to the four-step cycle of "moving down, staying, moving up, staying".

[0042] The reference value of the exposure parameter of the ultraviolet LED light source is set to a light intensity of 35-45 mW / cm 2 , and the wavelength range of the ultraviolet light emitted by the ultraviolet LED light source is 365-405 nm to ensure the effective curing of the photosensitive resin and the structural accuracy.

[0043] The exposure of the first printing layer is strengthened by 4.0 s of exposure to enhance adhesion, and the single-layer exposure time of the remaining printing layers is 1.5 s. The layer thickness of each printing layer is set to 20 μm.

[0044] In the embodiments of the present application, the photosensitive resin is WS-Y photosensitive sacrificial resin, which has low viscosity, good photosensitivity and appropriate mechanical strength, and is suitable for the manufacture of microscale structures. Among them, the relevant parameters of WS-Y photosensitive sacrificial resin are as follows: the color is yellow, the hardness is 60 HD, the annual viscosity is 25 cPs, the tensile strength is 38 MPa, the elongation rate is 26%, and the impact strength is 114 J / m. These characteristics ensure the stability and controllability of the mold in subsequent processing.

[0045] In the present application, the reference value of the exposure parameter of the ultraviolet light intensity is set to 40 mW / cm 2 , at this value, both the fine resolution and the curing depth are considered; based on the light absorption coefficient test results of WS-Y resin in the 365–405 nm band, it is ensured that the single-layer curing depth ≈ 1.3 × layer thickness, which can avoid the step effect caused by over-curing.

[0046] Except that the exposure time of the first printing layer is set to 4 s, the single-layer exposure time of the remaining printing layers is 1.5 s, which is combined with the light intensity to make the single-layer conversion rate of the resin > 85%, ensuring interlayer bonding; the minimum feasible exposure selected through the stepped specimen experiment.

[0047] Furthermore, the layer thickness of the printing layer is set to 20 μm, and the layer thickness of the printing layer determines the Z-direction resolution; 20 μm is the best-matched layer thickness under the X-Y resolution (≈25 μm) of the PμSL device, avoiding the "sawtooth" error.

[0048] Furthermore, the formed film thickness is set to 75 μm, and the distance between the light field and the resin tank is ensured to make the self-spreading rate of the fluid < 3 s; from the rheological experiment of the resin viscosity of 25 cP.

[0049] The downward movement distance of the Z-axis platform is 4 mm. At this distance, a release gap is formed to weaken the adsorption force and prevent the first layer from tearing.

[0050] The downward movement residence time of the Z-axis platform is 1 s, which can allow the resin to fully flow back to fill the model depression, and the resin reflux completion time is measured by high-frame imaging.

[0051] The upward movement distance of the Z-axis platform is 3.98 mm. Compared with the downward movement distance, a 20-μm crack is reserved to avoid the platform from compacting again and not exhausting the bubbles.

[0052] The upward movement residence time of the Z-axis platform is 0.2–0.8 s, which cooperates with the scraper / roller of the PμSL system and is fine-tuned in real time according to the resin fluidity.

[0053] Furthermore, the number of reciprocations of the blade in the PμSL system is set to 0 - 5 times, and the number of reciprocations of the roller is set to 0 - 3 times, which is used to remove microbubbles and smooth the layer lines.

[0054] Through the above process, the fabricated sacrificial mold 100 can accurately reproduce the complex geometric features of the origami structure 200, including sharp creases, spiral shapes, and axial symmetry. Compared with traditional manufacturing methods, the sacrificial mold 100 fabricated based on the PμSL technology has higher resolution and faster forming speed, and is applicable to fields such as flexible electronics, micro-robots, and biomedical devices.

[0055] Cleaning of the mold: After the sacrificial mold 100 is printed, the sacrificial mold is immersed in a cleaning solution to remove the uncured resin remaining on the surface of the sacrificial mold 100. After the sacrificial mold 100 is cleaned, a light-curing device is used to perform secondary curing on the sacrificial mold 100.

[0056] After printing is completed, the mold is immersed in a special fluorinated solution for 6 - 8 hours to remove the uncured resin remaining on the surface. After cleaning, a Formcure curing box is used to perform secondary curing on the sacrificial mold 100. The secondary curing temperature is set to 80°C, and the curing time for each side is 30 minutes to ensure that the overall strength and thermal stability of the mold meet the requirements for subsequent silicone casting.

[0057] Casting and molding of the flexible material: A two-component platinum silicone is selected as the molding material and mixed in a mass ratio of 1:1 for component A and component B. The mixed silicone is slowly filled into the cavity 130 along the opening of the mold through a syringe.

[0058] Dragon Skin 30 type two-component platinum silicone is selected as the molding material and mixed in a mass ratio of 1:1 for component A and component B. After being evenly mixed, the mixed silicone is injected into a syringe and slowly injected along the opening of the sacrificial mold 100 until the cavity is filled. The excess material can automatically flow out from the top of the sacrificial mold 100 to ensure complete filling of the structure.

[0059] Solidification of the mixed silicone and removal of the sacrificial mold 100: After the mixed silicone is filled, the sacrificial mold 100 is placed at room temperature and left to stand for 7 - 9 hours. After standing, a dissolving solution is used to dissolve the sacrificial mold 100 to expose the formed target origami structure 200.

[0060] After the injection of the glue is completed, the sample is left to stand at room temperature for about 8 hours until the silicone is fully cured and formed. Subsequently, the formed structure together with the mold as a whole is placed in a dissolving solution for chemical demolding. The used dissolving solution is prepared by mixing sodium hydroxide and distilled water in a mass ratio of 5:95. The dissolving process is carried out in a closed container at 80°C for 8 hours. After the mold material is completely dissolved, a complete small-scale Kresling soft origami structure can be obtained.

[0061] The obtained structure geometrically replicates the spatial crease configuration of the mold, with distinct mountain and valley crease regions. The origami units exhibit standard axisymmetric Kresling characteristics. The overall size of the structure is maintained at the millimeter scale. For example, the height of the final typical Kresling module is 7 mm, the cavity height is 5 mm, the cavity thickness is 1 mm, and the crease is 0.15 mm thicker than the cavity.

[0062] Through the above method, the present application realizes the effective construction of a soft Kresling structure at the millimeter scale, with stable process and good structural morphology, which is suitable for the research and application of various flexible devices such as micro flexible structures and soft robots.

[0063] The embodiments of the present application have been described in detail above with reference to the drawings. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present application.

Claims

1. A manufacturing method of an origami structure based on mold sacrifice, characterized in that, The steps are as follows: Mold preparation: Construct a 3D model of the sacrificial mold according to the target origami structure, use the surface projection microstereolithography technology to print layer by layer and cure while printing, and form the required sacrificial mold by layer-by-layer printing. Among them, the printing material is selected as photosensitive resin, and the sacrificial mold has a cavity for forming the target origami structure; Mold cleaning: After the sacrificial mold is printed, immerse the sacrificial mold in the cleaning solution to remove the uncured resin remaining on the surface of the sacrificial mold. After the sacrificial mold is cleaned, use a light curing device to perform secondary curing on the sacrificial mold; Pouring and molding of flexible material: Select two-component platinum silicone as the molding material, mix it according to the mass ratio of component A to component B of 1:1, and slowly fill the cavity with the mixed silicone along the opening of the mold through a syringe; Solidification of the mixed silicone and removal of the sacrificial mold: After the mixed silicone is filled, place the sacrificial mold at room temperature and let it stand for 7-9 hours. After standing, use a dissolving solution to dissolve the sacrificial mold to expose the formed target origami structure.

2. The manufacturing method of the origami structure based on mold sacrifice according to claim 1, wherein: The PμSL system used in the surface projection microstereolithography technology includes an ultraviolet LED light source, a DMD chip, a projection optical unit, and a Z-axis platform. Among them, the ultraviolet LED light source is used for curing the resin, the DMD chip dynamically regulates the light pattern according to the sliced image, projects the pattern onto the resin surface after shrinking through the projection optical unit, and the Z-axis platform is used to support the printed sacrificial mold.

3. The manufacturing method of the origami structure based on mold sacrifice according to claim 2, wherein: The reference value of the exposure parameters of the ultraviolet LED light source is set to a light intensity of 35 to 45 mW / cm 2 , and the wavelength range of the ultraviolet light emitted by the ultraviolet LED light source is 365 to 405 nm.

4. The manufacturing method of the origami structure based on mold sacrifice according to claim 3, characterized in that: During the printing process, the Z-axis platform completes layer separation and fluid replenishment in a four-step cycle of "moving down, staying, moving up, staying".

5. The manufacturing method of the origami structure based on mold sacrifice according to claim 4, wherein: The first printing layer uses 4.0s of exposure to strengthen adhesion, and the single-layer exposure time of the remaining printing layers is 1.5s. The layer thickness of each printing layer is set to 20μm.

6. The manufacturing method of the origami structure based on mold sacrifice according to claim 4, characterized in that: The downward movement distance of the Z-axis platform is 4mm, the downward movement and staying time is 1s, the upward movement distance is 3.98mm, and the upward movement and staying time is 0.2-0.8s.

7. The manufacturing method of the origami structure based on mold sacrifice according to claim 1, characterized in that: The cleaning solution is a fluorinated solution, and the soaking time is 6-8 hours.

8. The manufacturing method of the origami structure based on mold sacrifice according to claim 1, characterized in that: The temperature of the secondary curing is set to 80°C, and the curing time for each side of the formed sacrificial mold is 30 minutes.

9. The manufacturing method of the origami structure based on mold sacrifice according to claim 1, characterized in that: The dissolving solution is prepared from sodium hydroxide and distilled water according to a mass ratio of 5:

95.

10. The manufacturing method of the origami structure based on mold sacrifice according to claim 1, characterized in that: The dissolving process is carried out in a closed container at 80°C for 8 hours.

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