Study On Laser Sintering Process Parameters Of Film - Coated Sand

In the process of sand mold casting, core box and preparation is of vital importance. The preparation method of the traditional complex process, high cost and long cycle. Especially for large complex thin wall castings in sand mold, often have multiple sand mold, the mutual position size is a little mistake will lead to the casting precision is not high, the surface quality is poor, cutting processing capacity is big, not only wastes a large amount of metal materials, and increase the processing cost, low efficiency, poor economic effect. District laser sintering of precoated sand making mould has made certain achievements, and won the recognition of people, it has the molding speed, high precision molding, short time limit, the characteristics of the economic cost is low, the selection of laser sintering preparation of precoated sand mould will be after the trend of the sand mould casting.In this paper, the selective of laser sintering technology is applied in foundry resin silica sand made a systematic study, to the foundry resin sand district laser sintering process parameters for the research in detail. In the preparation stage of the resin sand, on the basis of existing research validation and optimization of the laminating process, studies the effect of factors such as temperature, sand mixing time for the effects of the resin coated by selecting the test found that effect of temperature on resin coated effect. After previous research based on the choice of the particles in different degree of three kinds of original sand according to 1.5:2.5:6.0 the mixture ratio, make the sand to fill the gap of coarse sand. The sand mixing process is concluded that effect of temperature is 120 ℃, to join the resin sand after 60 s, curing agent temperature is 95 ℃, after adding curing agent sand sand mixing technology of 35 s..Constituency in laser sintering process by orthogonal experiment method, this paper carried out a systematic research, the laser power, scanning speed, preheat temperature and thickness of the powder, such as the influence of process parameters on the forming quality of sand mold made a careful study, use the sintering equipment,SLS-500 scanning laser rapid molding machine. Experimental results show that with the increase of powder layer thickness, the tensile strength of laser sintering parts obviously decrease, increase the laser power or lower scanning speed can significantly improve the tensile strength of sintered parts, in addition, the orthogonal experiment results show that the process parameters of laser sintering parts tensile strength as follows: the influence of laser power> scanning speed >spread powder thickness> preheating temperature, the best sintering process for laser power: 18 W, preheat temperature: 70 ℃, the scanning speed: 1400 mm/s, spread powder thickness: 0.2 mm, the initial tensile strength of the sand mold can reach 0.66 MPa. In this paper, the selection of precoated sand laser sintering molding precision is studied, found the main factors influencing the precision of sintering von berg systeme including the error of the data processing, equipment of mechanical error, the influence of the sintering process and the characteristic, the influence of the material in the sintering process of the influence of laser power and scanning velocity of sand mold molding size is larger, the influence of Z axis comes as deviation caused by the so-called "surplus" Z axis.To enhance the mechanical properties of sand mold, the heat preservation post-processing of sand mold have done the research, through the different heat preservation temperature and holding time are tie-in, found that more optimizing the thermal curing process parameters: heat preservation temperature 250 ℃, the heat preservation time 30 min, the tensile strength after thermal insulation can reach 3.86 MPa.This article also prepared for this kind of technology of resin sand gas evolution, calcination reduction and melting away did the study.District laser sintering technology belongs to the early development of 3 d printing, lightweight, low cost, short cycle and the characteristics of green environmental protection makes it in industrial manufacturing, aerospace manufacturing precision components manufacturing and military industry will reflect a lot of advantages, especially for complex shape parts, selective laser sintering technology can take advantage of its unique way of molding cycle greatly reduce the manufacturing difficulty and cost.Using selective laser sintering application has great potential for development in the field of sand mold casting, in addition to optimize the original sand coated process, laser sintering process and post-treatment process of sand mold mechanical performance, can also through ascension sand particle characteristics, optimization of different size than the original sand collocation etc can improve the spread powder density approach makes to further improve mechanical properties of the sand mold. This new manufacturing technology combined with traditional foundry method to improve other areas of rapid manufacturing technology has great application value.