Liquid silicone rubber 3D printing rapid prototyping structure

Abstract

The utility model provides a kind of liquid silicone 3D printing rapid prototyping structure, including shell mould, including shell body, there is a solidification cavity in shell body, shell body one end is provided with an injection port, shell body is provided with several exhaust columns away from injection port one end, there is an exhaust hole for exhaust in exhaust column;Injection mechanism is connected the injection port, for liquid silicone is injected into solidification cavity, and then solidification is made into silicone product.By injection mechanism, liquid silicone is injected into shell mould, after a certain time solidification setting, the shell mould is destroyed, and silicone product can be obtained.Compared with the conventional use of silicone mould design, this method can effectively reduce the high mould manufacturing cost and long mould manufacturing cycle, and get fast and low-cost silicone product.

Description

Technical Field

[0001] This utility model relates to a rapid prototyping structure for liquid silicone 3D printing, which is applied in the field of silicone molding. Background Technology

[0002] Liquid silicone, with its excellent tear resistance, resilience, anti-yellowing properties, thermal stability, and heat and aging resistance, has been increasingly widely used in numerous industries such as medical, electronics, machinery, and sanitary ware. Injection molding is the primary method for producing liquid silicone parts, capable of manufacturing complex and high-precision components. However, in the product development stage, if silicone parts are required, currently only mold making is possible. Mold manufacturing is costly and time-consuming, often taking several weeks, which undoubtedly increases R&D costs and risks for companies and hinders the progress of new product development. Therefore, in industries such as electronics, machinery, and sanitary ware, due to cost and risk considerations, vacuum casting using polyurethane rubber is often preferred to create rapid prototypes. However, in the medical and food industries, due to strict safety requirements for parts materials, polyurethane rubber cannot replace silicone parts, thus necessitating expensive injection molding. In view of the above problems, this utility model innovatively designs a rapid prototyping structure for liquid silicone 3D printing, aiming to effectively reduce mold manufacturing costs. Utility Model Content

[0003] This invention provides a rapid prototyping structure for liquid silicone 3D printing, which can effectively solve the above-mentioned problems.

[0004] This utility model is implemented as follows: A rapid prototyping structure for 3D printing using liquid silicone, comprising: A shell mold includes a shell body, which has a solidification cavity. One end of the shell body is provided with an injection port, and the other end of the shell body away from the injection port is provided with a plurality of venting columns. Each venting column has a venting hole for venting. A ring of connecting ports corresponding to the injection mechanism is provided on the outer wall of the injection port. The thickness of the connecting ports is 1~2mm. An injection mechanism, connected to the injection port, is used to inject liquid silicone into the curing cavity, thereby curing it into a silicone product.

[0005] As a further improvement, the vent hole includes a first vent hole near one end of the curing cavity and a second vent hole connected to the first vent hole. The first vent hole is circular in shape. The overall length of the vent column is defined as L1, and the length of the first vent hole is defined as L2. Then, the length of the first vent hole L2 is 1 / 3 to 2 / 5 of the overall length of the vent column L1.

[0006] As a further improvement, the second exhaust hole is teardrop-shaped and is set on the first exhaust hole with an outward draft angle of α°, where the draft angle α = 1~2.5°.

[0007] As a further improvement, the thickness of the shell mold is 0.5~1.5mm, and the thickness of the shell mold is proportional to the size of the shell mold.

[0008] The beneficial effects of this invention are as follows: liquid silicone is injected into a shell mold via an injection mechanism, and after a certain period of curing and shaping, the shell mold is destroyed to obtain the silicone product. Compared with traditional silicone mold designs, this method can effectively reduce the high cost and long mold manufacturing cycle, resulting in fast and low-cost silicone products. Specifically, the injection mechanism can precisely control the injection volume and speed of the liquid silicone, ensuring uniform distribution of the silicone within the shell mold. During the curing process, conditions such as temperature and humidity can be precisely controlled to guarantee the quality and performance of the silicone product. Furthermore, since no specialized mold is required, this method significantly shortens the production cycle and reduces production costs, making it particularly suitable for small-batch or customized silicone product production. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the molding device provided in an embodiment of the present invention.

[0011] Figure 2 This is a top view structural diagram of the molding device provided in an embodiment of the present invention.

[0012] Figure 3 yes Figure 1 A magnified structural diagram of point A in the middle.

[0013] Figure 4 This is a schematic diagram of the molding device structure provided in another embodiment of the present invention.

[0014] Figure 5 This is a schematic diagram of the three-dimensional structure of a silicone product provided in another embodiment of the present invention.

[0015] Figure 6 This is a flow state diagram simulated using simulation software, provided in an embodiment of the present invention.

[0016] Figure 7 This is another embodiment of the present invention, which provides a flow state diagram using simulation software.

[0017] The attached diagram is labeled as follows: 11. Shell mold; 12. Shell body; 13. Curing cavity; 14. Injection port; 15. Connection port; 16. Exhaust column; 17. Exhaust hole; 18. First exhaust hole; 19. Second exhaust hole; 10. Connecting column; 11. Exhaust connection part; 20. Injection facilities. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Therefore, the following detailed description of the embodiments of this utility model provided in the accompanying drawings is not intended to limit the scope of the claimed utility model, but merely to represent selected embodiments of this utility model.

[0019] In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] This invention relates to a rapid prototyping method for liquid silicone 3D printing, comprising the following steps: Reference Figures 1-5 As shown, a three-dimensional structural model of the silicone product shell mold 10 and the injection port 12 are designed using computer-aided software. The computer-aided software includes Pro / ENGINEER, SolidWorks, CATIA, etc., which are not limited here. The three-dimensional structure is designed according to the shape provided by the requirements, and then the injection port 12 for injection molding is designed. Generally, the injection port 12 is set at the place where the product is thickest, because during the injection process, the injection port 12 may break due to the movement of the shell mold 10. However, this is not absolute, and the position of the injection port 12 may be changed according to the shape of the product and the design of the vent 14. Reference Figures 6-7As shown, the flow state of liquid silicone in the shell mold 10 is simulated using simulation software; the simulation software includes ANSYS Fluent, Autodesk Simulation CFD, Numeca, etc., and no further restrictions are imposed here.

[0021] Reference Figures 1-4 As shown, the location of the vent hole 14 is designed based on the simulated flow state of liquid silicone in the shell mold 10. The vent hole 14 is located at the end of the material flow path or at the confluence of two material flows. This part needs to be designed according to the flow state of the simulation software. If a reasonable vent hole 14 cannot be designed according to the flow simulation state of the simulation software, the location of the injection port 12 can be changed according to the actual situation. The main function of a reasonably designed vent hole 14 is to reduce air bubbles and pores. When plastic or liquid materials are filled into the curing cavity 111 of the mold, air and gas inside the material need to have an outlet, otherwise air bubbles or pores will be formed, affecting the appearance and performance of the product. Moreover, the vent hole 14 helps the material flow more smoothly into every corner of the mold, reducing resistance during the filling process and improving filling efficiency.

[0022] After designing a suitable shell mold 10, the 3D printer can be started to print the shell mold 10. In this embodiment, in order to facilitate observation of the flow state during injection, the printing molding material used in this invention needs to be a transparent, high-temperature resistant material with a heat distortion temperature as high as 100-200 degrees Celsius to ensure that the shell does not deform during the support melting process. The material also needs to have a certain degree of transparency to facilitate observation of the material's flow state within the shell during silicone material injection, so as to make timely adjustments and avoid the formation of air bubbles. In addition, the material also needs to have relatively low impact strength to reduce the difficulty of breaking the shell mold after the silicone product is molded, and to reduce damage to the internal silicone product during the breaking process. Therefore, in one embodiment, the present invention employs a photocurable material having the following composition (by weight percentage): 14% to 22% oligomers, said oligomers including one or more aminomethyl esters (meth)acrylates; 65% to 75% diluent, said diluent being selected from one of methacrylates, dimethacrylates, triacrylates, and diacrylates; 5% to 11% curing reactant, said curing reactant being selected from at least one of non-oligomeric urea (meth)acrylates and isocyanurate (meth)acrylates; and 3% to 5% photoinitiator, said photoinitiator being selected from α-cleavage photoinitiators and not containing non-reactive waxes. In this embodiment, the photocurable material is selected from 16% aminomethyl acrylate (meth)acrylate, 14% curing reactants, and diluents including 19% SR506, 8% SR833, and 40% SR205. The photoinitiator is selected from 2% α-pyrolysis photoinitiator, and there is 1% additive. The tensile modulus of this printing material is 2764 MPa, and the tensile strength is 65.3 MPa, which meets the requirements of this invention for transparent, high-hardness, and low-impact-strength materials. This material is not limited to this one; other hot-melt materials can also be used for 3D printing. In another embodiment, this invention uses a photosensitive resin material, which includes 26% octahydro-4,7-methylene-1H-inden-1,5-ylidene)bis(methylene)diacrylate, 27% (external)-2-methyl-2-acrylate 1,7,7-trimethylbicyclo[2.2.1]hepta-2-ol ester, and 26% 4-(1-oxo-2-propenyl) The material comprises morpholine, 19.4% polyether polyurethane methacrylate, 1.5% phenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and 0.1% 2,6-di-tert-butyl-p-methylphenol. It exhibits good transparency, tensile strength of 70-80 MPa, tensile modulus of 2500-3000 MPa, notched impact strength of 14-17 J / m, and a heat distortion temperature of 90-100°C at 0.45 MPa, meeting the requirements of this invention for a transparent, high-hardness material with low impact strength.

[0023] Among various 3D printing processes, photopolymer 3D printing can achieve relatively fine feature representation, smooth surface finish, and dimensional accuracy. However, regardless of whether it's a photopolymer 3D printer based on surface projection technology or laser scanning technology, it's impossible to completely avoid internal supports when printing hollow structures. These supports, being enclosed within the shell, cannot be removed. This process utilizes a photopolymer 3D printer based on material jetting technology to print hollow shells. This type of printer uses low-melting-point wax as the support material and a transparent, high-temperature resistant material as the shell forming material. After printing, the internal and external supports can be melted and removed by heating. The melted internal supports can then be expelled through vents and injection ports under gravity. The transparent shell material facilitates observation of whether the internal supports have been completely removed and also allows for monitoring of the silicone flow within the shell during silicone injection, enabling adjustments and preventing air bubbles. Therefore, using this 3D printing technology to print hollow shells eliminates the problem of internal supports not being able to be removed, effectively solving the technological difficulties in manufacturing thin-shell molds. The aforementioned material has strong thermoplasticity, and during the manufacturing process of the shell mold 10, a thinner shell mold 10 is manufactured. The material has a high heat deformation temperature, preventing heat deformation during the thermal melting of the supports.

[0024] Liquid silicone is then injected into the shell mold 10 via the injection mechanism 20. After curing, the shell mold 10 is destroyed to obtain the silicone product. In one embodiment, an appropriate amount of platinum curing agent is added to the A component of the liquid silicone to prevent the silicone from reacting with the photosensitive resin material and failing to cure. The A and B components of the liquid silicone are then mixed and stirred, and then placed in a vacuum degassing machine for degassing. The curing time of the liquid silicone after injection into the shell mold is 4-5 hours. Compared with traditional injection molds, the manufacturing cycle is greatly shortened, and silicone samples can be delivered within 1-2 days. The three-dimensional structure of the silicone product is designed using computer-aided software, then printed using 3D printing technology, and after post-processing, a hollow shell mold for liquid silicone curing is manufactured. Finally, the liquid silicone is injected into the shell mold 10 via the injection mechanism 20, and after a certain curing and shaping time, the shell mold is destroyed to obtain the silicone product. Compared with traditional silicone mold designs, the silicone product obtained by this method can effectively reduce the high mold manufacturing cost and long mold manufacturing cycle, resulting in fast and low-cost silicone products. Furthermore, silicone products made through 3D printing molds have high precision and no parting lines.

[0025] Reference Figures 1-4As shown, the present invention also relates to a rapid prototyping structure for liquid silicone 3D printing, including a shell mold 10. The shell mold 10 includes a shell body 11, and the shell body 11 has a curing cavity 111 inside. The curing cavity 111 is the same size as the silicone product to be printed. In this embodiment, the curing cavity 111 is U-shaped. One end of the shell body 11 is provided with an injection port 12, and the end of the shell body 11 away from the injection port 12 is provided with a plurality of exhaust columns 13. The exhaust columns 13 need to be arranged opposite to the injection port 13. Generally, exhaust holes 14 are provided at the end of the material flow path or at the confluence of two material flows. Each exhaust column 13 has an exhaust hole 14 for exhausting.

[0026] Reference Figure 3As shown, in this embodiment, the vent 14 includes a first vent 141 near one end of the curing chamber 111 and a second vent 142 connecting the first vent 141. The first vent 141 is circular in shape and needs to ensure uniform venting. The overall length of the vent column 13 is defined as L1, and the length of the first vent 141 is defined as L2. The length L2 of the first vent 141 is 1 / 3 to 2 / 5 of the overall length L1 of the vent column 13. In this embodiment, the overall length L1 of the vent column 13 is 20mm, and the length L2 of the first vent 141 is 6mm. The purpose of setting this length is that the first vent 141 serves as the main vent and is connected to the curing chamber 111. After molding, a silicone material bundle will be generated at both the injection port and the vent port. After cutting off the material bundle, a mark will be left on the product surface. To minimize the impact of marks on the appearance of the parts, the first vent hole should be as small as possible, while still ensuring that the internal wax material can flow out smoothly. Therefore, it is generally recommended that the diameter of the vent hole be no less than 0.5 mm. Excessively large vent holes are also not conducive to forming a certain internal pressure in the silicone filling process. Internal pressure helps to squeeze out small air bubbles generated during the silicone flow process. The diameter of the second vent hole can be appropriately increased to accelerate the discharge of internal wax material. Because the diameter of the first vent hole 141 is relatively small, generally no less than 0.5 mm, the second vent hole 142 is teardrop-shaped. The purpose of the teardrop shape is to improve the venting efficiency of the second vent hole 142. The second vent hole 142 is molded outward at an α° angle onto the first vent hole 141. The draft angle α is 1~2.5°. In one embodiment, the draft angle α is 1°. The purpose of setting this angle is to improve the venting efficiency of the second vent hole 142. If the draft angle α is greater than 2.5°, the overall thickness of the vent column 13 will increase. Since the number of vent columns 13 of the shell mold 10 is set according to the shape of the model, there may be multiple vent columns, which will increase the overall material consumption and thus increase the cost. If the draft angle α is less than 1°, the improvement in venting effect is not significant. Therefore, the draft angle α set in this embodiment is 1°, which can effectively control the material cost and improve the venting efficiency of the vent hole.

[0027] The selection of the thickness of the shell mold 10 is particularly important. The thickness of the shell mold 10 is 0.5~1.5mm, and it is directly proportional to the size of the shell mold 10. The thickness of the shell mold 10 must meet the requirements of resisting thermal deformation during the high-temperature wax melting process and reduce the difficulty of breaking the shell after molding. A thick shell is not easy to deform, but it is more difficult to break later, which may damage the molded product. For complex or large products, multi-curved surfaces, and thin-walled structures, the shell thickness should be increased uniformly to ensure the stability of the cavity shape. Setting the shell mold 10 with a thickness of 1.2~1.5mm can effectively prevent deformation or breakage during the process of heating the shell mold 10 and removing the support material. For medium-sized complex products, a moderate shell thickness (0.8~1.2mm) should be selected considering the molding difficulty and cost. For simple or small products, such as flat parts, a thinner shell (0.5~0.8mm) can be selected to make the shell mold 10 easier to break and prevent damage to the structure of the silicone product during the process of breaking the shell mold 10. In addition, the shell thickness should match the size of the vent hole and injection port.

[0028] Table 1. Relationship between shell mold thickness selection and silicone products

[0029] After selecting the shell thickness, flow simulation (such as ANSYS Fluent) is used to analyze the silicone filling state under different thicknesses, optimize the combination of vent position and shell thickness, and produce shell molds 10 with different thicknesses.

[0030] Reference Figures 1-3 As shown, the injection mechanism 20 is connected to the injection port 12 and is used to inject liquid silicone into the curing cavity 111, thereby curing it into a silicone product. The injection mechanism 20 is optional. A ring of connecting ports 121 is provided on the outer wall of the injection port 12. The thickness of the connecting ports 121 is 1~2mm. In this embodiment, the overall thickness of the shell mold is 1.5mm, and the thickness of the connecting ports 121 is 1mm. The connecting ports 121 can strengthen the strength of the injection port 12 and prevent cracks from appearing at the injection port 12 during the process of connecting the injection mechanism 20. Therefore, it is necessary to increase the connecting ports 121 to increase the strength of the shell mold 10.

[0031] Reference Figure 4As shown, in another embodiment, in order to strengthen the exhaust column 13, a connecting column 15 is added between adjacent exhaust columns 13. The connecting column 15 is a solid cylinder and is used to connect adjacent exhaust columns 13. Since the exhaust column 13 has a small size and wall thickness, the connecting column 15 can increase the strength of the exhaust column 13. The two ends of the connecting column 15 are set as spherical structures. The purpose is not only to strengthen the exhaust column's ability to resist thermal deformation when melting wax at high temperature, but also to accelerate the discharge of the supporting wax inside the shell.

[0032] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A rapid prototyping structure for 3D printing using liquid silicone, characterized in that, include: The shell mold (10) includes a shell body (11), which has a solidification cavity (111) inside. One end of the shell body (11) is provided with an injection port (12). The end of the shell body (11) away from the injection port (12) is provided with a plurality of exhaust columns (13). The exhaust column (13) has an exhaust hole (14) for exhausting air. The outer wall of the injection port (12) is provided with a ring of connecting ports (121) corresponding to the injection mechanism (20). The thickness of the connecting ports (121) is 1~2mm. The injection mechanism (20) is connected to the injection port (12) and is used to inject liquid silicone into the curing cavity (111) and then cure it to form a silicone product.

2. The liquid silicone 3D printing rapid prototyping structure according to claim 1, characterized in that, The vent (14) includes a first vent (141) near the end of the curing cavity (111) and a second vent (142) connecting the first vent (141). The first vent (141) is circular in shape. The overall length of the vent column (13) is defined as L1, and the length of the first vent (141) is L2. Then the length L2 of the first vent (141) is 1 / 3 to 2 / 5 of the overall length L1 of the vent column (13).

3. The liquid silicone 3D printing rapid prototyping structure according to claim 2, characterized in that, The second exhaust hole (142) is teardrop-shaped and is set on the first exhaust hole (141) with an outward draft angle of α°. The draft angle α = 1~2.5°.

4. The liquid silicone 3D printing rapid prototyping structure according to claim 3, characterized in that, The thickness of the shell mold (10) is 0.5~1.5mm, and the thickness of the shell mold (10) is proportional to the size of the shell mold (10).

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