A brief introduction to the process of stereoscopi

2022-08-11
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Brief introduction to the process of stereoscopic printing rapid prototyping manufacturing

stereoscopic printing molding

this molding method is a rapid prototyping method with the most mature production technology and the most widely used in many medical equipment manufacturing enterprises with the deepest research in the world at present. In 1984, the stereo printing molding technology was still in the laboratory research stage, and in 1988, the first operable manufacturing system was commercialized. American chryster first applied this technology in engineering practice in 1989, but it did not attract enough attention until 1992. The pioneer of this technology is American 3dsystem company, which is the largest and first RP manufacturer in the world. Its product market share is about 30%. Its SLA series products are the best and form a monopoly market

1) process principle

SLA stereolithographyapparatus, also known as stereolithography, light curing, etc. Its basic process principle (as shown in Figure 4) is to carry out the three-dimensional geometric modeling of the required prototype with the help of CAD, generate data files and process them into a faceted model. The inner and outer surfaces of the model are planarized and discretized with small triangles, and the STL (mechanical property test PHY for all seamless steel tubes in stereolith GRA) file format, which is widely used in rapid prototyping manufacturing systems and defaults to the industrial standard, is obtained. Cut the model according to the treatment method of equal distance or unequal distance, and form a series of parallel horizontal section slices from the bottom to the top, that is, cut the faceted model into a series of cross sections by computer. The scan line algorithm is used to generate the best path for each section, including the profile path and the internal scan path. At the same time, the model is positioned on the forming system and the supporting structure is designed

slice information and generated path information are used as command files (CLI files) to control the molding machine, and NC instructions at all levels are compiled and sent to the molding machine. The thinner the layer is, the higher the accuracy of the generated parts is. The purpose of using unequal thickness layer is to speed up the forming speed

the laser beam in the laser forming machine can be put into use by several times, and the control command scanning enables the liquid photosensitive resin contained in the container to solidify and bond together layer by layer. The curing process starts from the first layer of liquid on the working platform. When the first layer is cured, the working platform will fall a certain distance along the z-axis direction (that is, the layer thickness, taking into account the material and process factors), so that a new layer of liquid resin is covered on the cured layer for the second layer of solidification. Repeat this process until the last layer is cured, and a three-dimensional prototype entity is generated. The liquid photosensitive resin contained in the storage tank will solidify in a certain area under the irradiation of a certain wavelength (such as 325nm) and intensity of UV laser, that is, forming a curing point. At the beginning of molding, the working platform is at a certain depth below the liquid level, such as 0.05~0.2mm. The focused laser spot is scanned point by point on the liquid surface according to the instructions of the computer, that is, solidified point by point. When a layer of scanning is completed, the resin that has not been irradiated by the laser is still liquid. Then the lifting frame drives the platform to drop another layer. The newly formed layer is covered with a layer of resin, and then the second layer is scanned to form a new processing layer and firmly connected with the cured part

compared with 2015, the main pollutants 2 sulfur oxide, nitrogen oxide and volatile organic compounds have been reduced by more than 20%

for the molding machine using laser deflection mirror scanning, the focal length and liquid surface spot size change when the laser beam is deflected, which directly affects the solidification of the thin layer. In order to compensate for the changes of focal length and spot size, the scanning speed of laser beam must also be adjusted in real time. In addition, when making each thin layer, the scanning speed must also be adjusted according to the thickness change of the processed material layer (layer thickness change)

2) system composition

generally, the stereo printing forming system is composed of lasers, X-Y motion devices or laser deflection scanners, photosensitive liquid polymers, polymer containers, control software and lifting worktables

reprinted from: Maintenance Department of Changzhou Lansheng CNC Machine Tool Sales Co., Ltd

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