(4)Can carry out the nighttime over full-automatic production.
(5)Process with high efficiency, produces the article entity model and molding tools quickly.
The form follows the comparison of the method for the Rapid Prototyping Technology and tradition.
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Comparison the item
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Processing technology
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The tool machine slices to pare to process
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RP(Light shape method)process
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The method of process
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Do away with the surplus material process
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Fold the layer process
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The object of process
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Solid
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Liquid, portrait, powder
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Tool
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The tool of slice to pare
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Light beam
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Minimum processing units
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Dot’s diameter is about 1μms
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Triangles of 200μms long
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Production of spare parts
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The least processes come together the body of the unit
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The least processes come together the body of the unit
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The RP and traditions slice to pare the method comparison sheet
3. The develop of RP
Rapid prototyping technology concept that the concept RP (Rapid Prototyping Technology) could be back to 1979. the profess of Zhong Chuan Weixiong in produce and technique institute of Japanese University of Tokyo invent the method of fold the layer model, the Xiao Yu Xiunan put forward the light shape method again in 1980, after the conceive put forward, it was continued to study in 1984 by Wan Gu Yanger, and carried on to produce manufacture on a trial basis in 1987.
1988, the United States rapidly prototype 3D Systems Corporation was the first to introduce practical devices-laser three-dimensional shapes that SLA (Stereo Lightgraphy Apparatus), and annual sales growth rate 30%~40% increase in the world market. In recent years, with increasing performance scanning-a mirror, and the development of materials science and computer technology, rapid prototyping technology matures, and in 1994 to promote universal access to the formal stage. In accordance with the patterns and materials used in the different types of rapid prototyping technology currently has the following four types.
3.1 Solidification resin materials using laser light shapes law
The light shape equipment is excellent with a product of the 3D Systems company of the United States, and the formation of a monopoly. Figure 1 shows the operating principles. Issued by the laser light, the optical system to compile into a small beam, the beam in the computer controlled, selective scanning resin surface, using an ultraviolet resin Frozen mechanisms, a layer of solidification resin, each layer of solidification, precision workstations in a distance with the new layer of surface geometric information to the laser scanner for scanning reading, solidification of the new layer of resin and firmly stick to the previous layer has solidification resin, so repeatedly until the production of spare parts entities generated a model. The laser stereoscopic shape manufacturing accuracy can reach the ±0.1 mms, mainly used to provide the sample and the experiment models for the product. In addition, the SOLIFORM of the Japanese system machine developed can manufacture to inject to model the molding tool and vacuum molding tools directly.
Figure 1 Stereoscopic light shape technique principle diagram
3.2The paper folds the layer shape method
The paper folds the LOM that the layer shape method develops with the Helisys company currently applicant most widely. The devices used for roller paper from the paper heating roller cylinders connectivity, and then using the laser to cut paper, the question heating roller cylinders automatically leave, the paper will be ready by laser level requirements into shape, as shown in figure 2.
Figure 2 Principle diagram of the paper folds the layer shape
The LOM can manufacture some large spare parts and the thick wall kind pieces of the hard creation with lights shape method and create cost is cheap (about for the light shape method of 1/2), the speed is high (about manufacture time for the wood mold of below 1/5), and can simply analytic the design conceive outline and function.
3.3 meltdown shape methods
The meltdown shape method is most extensive used with the product FDM which is developed in American Stratasys,(the Fused Deposition Modeling), when it is working, the plastics material with hot extrusion sprayed directly by sprinkler head controlled by computer combine to layer to create an entity model from bottom to top according to several information of level. The biggest characteristics in FDM technical is a quick(general the model need several hours and can immediately model) and free from pollution, to get the extensive application in prototype, develop and cast wax mole and so on.
3.4 hot and fictile shape methods
The hot and fictile shape method burns the knot with the selectivity laser of the DTM company development namely the SLS (the Selective Laser Sintering) application is the most. That method is a way manufacture kind piece that burns with the CO2 laser machine controls by the calculator, carry on scanning on the material powder according to several information for faces of several pieces with horizontal each layer of the body, the powder is scanning by laser and solidify together. Then, spread up a new powder of layer, then scan to burn the knot with the laser, thus again and again, keep to go to make the kind piece which needed. As figure 3 shows.
Figure 3 The principle chart of selectivity laser sintering
The SLS technique shape speed is fast(general ware, need one or two days to complete), the shape accuracy is high(the minimum thickness of each layer powder is about 0.07 mms, the laser dynamic state accuracy can reach the ±0.09 mms, and have the automatic laser repair function), the prototype strength is high(gather its bent strength of the carbonic acid fat and can amount to the 34.5MPa,the nylon can reach 55MPa), therefore, can carry on function’s experiment and assemble the emulation with the prototype, to obtain the best curved face to match with the observation the condition.
Develop and applied aspect technically in RP, the United States and Japans are the best. In Huazhong University develops two kinds of model system machine HRP and RPSs which is research to manufacture in 1994 successful quickly, have already entered the commodity market currently, be applied in the professions extensively, such as automobile, toy, aviation aerospace, shipbuilding and the soldier work etc.
