Control principle and application of flash curing

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Control principle and application of UV curing rapid prototyping technology

Abstract: UV curing rapid prototyping technology is a new processing method, which integrates modern numerical control technology, cad/CAM technology, laser technology and new material technology, breaks through the traditional processing mode, greatly shortens the production cycle of products, and has a wide range of applications in molding, visual analysis and testing products and medicine. This paper summarizes the principle and application of UV curing rapid prototyping technology

key words: UV curing rapid prototyping; Principle; Control; The application of

rapid prototyping technology is one of the rapidly developing manufacturing technologies in the world today. This method can simply and automatically produce complex three-dimensional shapes that are difficult to be produced by various processing methods, and has an epoch-making role in the field of processing technology [1, 2]

stereolithography apparatuses (SLA) is an advanced manufacturing method developed in the mid-1980s, which is widely used in rapid prototyping methods. Its breakthrough lies in the improvement of the traditional "removal" processing method (parts made by removing excess parts from blanks) to the increase processing method (parts formed by accumulating materials layer by layer). SLA is more and more widely used in the casting, mold and plastic processing industries because of its convenience and short production cycle [3 ~ 5]

1 forming principle

the light curing rapid prototyping manufacturing technology is different from the traditional material removal manufacturing method. Its forming principle [6 ~ 8] is: SLA converts the three-dimensional calculated image data of the designed part into a series of thin model section data, and then on the rapid prototyping machine, with a controllable ultraviolet laser beam beyond this, according to the two-dimensional graphic contour trajectory of each layer of thin sheet obtained by the computer slicing software, The liquid photosensitive resin is scanned and cured to form a continuous curing point, thus forming a thin cross-section of the model. The next layer is made in the same way. The process starts from the bottom thin section of the part, and continues one layer at a time until the three-dimensional model is made. Generally, the thickness of each layer is 0.076 ~ 0.381mm. Finally, take the product out of the resin solution, carry out the final hardening treatment, and then polish, electroplate, spray or dye it. Figure 1 shows the schematic diagram of SLA control principle

Figure 1 SLA control principle

in order to realize UV curing rapid prototyping, the selection of photosensitive resin is also critical. It must have appropriate viscosity, reach a certain strength after curing, and have small shrinkage, distortion and deformation during and after curing. More importantly, in order to manufacture a part with high speed and precision, the photosensitive resin must have appropriate photosensitivity. It should not only be cured under low light energy, but also the curing depth of the resin should be appropriate

2 molding process and control

the process of UV curing rapid prototyping is divided into three stages: pretreatment, layered overlay molding and post-processing. The specific steps are shown in Figure 2

Figure 2 SLA process

the rapid prototyping machine can only accept the three-dimensional model constructed by the computer before slicing. Therefore, computer-aided 3D design software should be used on the computer to design 3D models according to the requirements of products or convert the 2D and 3D views of existing products into 3D models

The more complex the product is, the more difficult it is to construct a three-dimensional model. The computer-aided design software used to construct the model is very critical, which requires a strong three-dimensional modeling function. At present, the commonly used computer-aided software systems in the rapid prototyping industry mainly include pro/engineer, AutoCAD, etc. Among them, pro/engineer software has strong solid modeling and surface modeling functions, and can construct very complex models, so it is highly praised by many users, but its price is expensive, the system is relatively large, and the user interface is not friendly enough. New users often need a process of familiarity and experience accumulation. Although AutoCAD has low price and simple operation, it is difficult to form complex products, and the design is labor-consuming and time-consuming. SolidWorks launched in recent years is relatively cheap, can basically meet the requirements of three-dimensional modeling, and has a friendly interface, which is easy to master, so many users are interested in this software

there are many output formats of model files generated by the above-mentioned computer-aided design software, among which the common ones are IG made in China 2025 top-level design, basic completion of new materials, priority development of ES (International graphics exchange standard), HPGL (HP graphics language), step (standard for the exchange of product), DXF, STL (stereo graphics interface specification), etc. STL format is a model file output format often used by rapid prototyping machines

3 has significant economic, social and ecological benefits application

to successfully put a new product into the competitive market, it needs its fast product development and short production cycle. Only the combination of rapid and flexible manufacturing process can achieve the desired effect. SLA integrates the achievements of modern control technology, cad/cam technology, laser technology and new material science, breaks through the traditional processing mode, greatly shortens the production cycle of products, and improves the market competitiveness of products. At present, the applications of UV curing rapid prototyping technology mainly include:

(1) making molds with SLA

the three-dimensional resin mold quickly made by SLA process can replace the wax mold for crusting. When the shell is roasted, the resin film is removed to obtain a hollow shell, which can be poured into an alloy casting with high dimensional accuracy, geometric shape and surface finish, or a cavity directly used to make injection mold, which can greatly shorten the molding process, Shorten the product development cycle and reduce manufacturing costs

(2) intuitive analysis of sample shape and size design

in the stage of new product design, although the product can be evaluated with the help of design drawings and calculation simulation, it is not intuitive, especially for products with complex shapes, and it is often difficult to make correct and timely judgments because it is difficult to imagine their real morphology. Using SLA can quickly manufacture samples for designers and users to measure intuitively, and can quickly modify and manufacture repeatedly, which can greatly shorten the design cycle of new products and make the design meet the expected shape and size requirements

(3) use SLA parts for product performance testing and analysis

in plastic product processing enterprises, because SLA parts have good mechanical properties, they can be used for partial performance testing and analysis of products, so as to improve the reliability of product design

(4) manufacturing of single piece or small batch products

in some special industries, some parts only need a single piece or a small batch of less than 50. Such products are reproduced by molding, with high cost and long cycle. Generally, SLA can be directly used for molding, with low cost and short cycle

(5) application in medicine

surgeons have used the data obtained from CT and MRI to make models with SLA in order to plan head and face surgery. They also use SLA models to practice complex surgery, and design templates for surgery such as tooth and bone transplantation

4 conclusion

sla technology is a new molding method. Although it came out soon, it has been widely used in many fields of the national economy and has brought huge economic benefits to many industries. Especially with the continuous progress of science and technology, the production cycle of products is required to be shorter and shorter, which brings a great opportunity for the production and development of UV curing rapid prototyping. Moreover, the UV curing system is a new green technology, which conforms to the national environmental protection policy and will bring rich returns to the mold, plastic and other industries, and its own development will also be greater. At present, SLA technology is widely used in developed countries such as Europe, America and Japan. Only some colleges and universities and relevant manufacturers in China have developed UV curing rapid prototyping machines on the basis of absorbing and digesting foreign technology, but there is still a large gap between China and foreign countries in terms of quality and quantity, as well as in the application field. Only by continuously promoting and improving SLA technology can we catch up with and surpass developed countries in this field


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