Study On Some Key Problems Based On Selective Laser Sintering

Rapid Prototyping (RP) is an advanced forming and processing technology that is followed with interest by researchers and manufactures in recent years. Now the basic principles of five kinds of RP technology, which dominate in the world, have been integrated. To special RP systems, it is an important subject how to decrease forming time, improve the prototyping precision and extend the utilization area of prototyping without extra expensive cost. Just on the basis of all above opinions, the research on the forming precision, forming time, scanning path, post-treatment and RT of SLS on the high molecular powder materials is preceded. The result of this research has been successfully applied into the HRPS-IIIA RP system and has great effect on manufacturing qualified parts, also is a foundation of ameliorating this system.All the factors that affect the prototyping precision are intensively analyzed in this paper. Through manufacturing special pattern, using the variance analysis and range analysis of the orthogonal experiment, the effects of process parameters on prototyping size, form and position accuracy, surface roughness are discussed, the combination of process parameters are optimized, and the prototyping quality is greatly improved. The warp problem of SLS is also stressed and the fundamental cause, developing trend and settlement of this problem is advanced. The influence of the primary process parameters on the warp distortion is reviewed through the orthogonal experiments. The result and solution of this experiment have great guidance to minish the warp distortion of material SLS systems. In the dissertation, the distortion mechanism of SLS is dissertated and the comprehensive settlement of SLS distortion is proposed.The mathematical model by which the forming time can be precisely calculated is ratiocinated. This model shows that in SLS the scanning "delay" phenomenon can make the actual forming time greatly exceed the theoretical time, and the total number, total length of the scanning lines and the scanning speed have different effects on the scanning "delay". This model and the experiment solution can restrict the calculating error of the forming time to seconds which have important reference to externally quoting, arranging the working sequence and balancing the priority between the process efficiency and prototyping function of SLS provider.The prototyping quality made by annular scanning is far better than this of grating scanning. One kind of new sub-area solution that is based on annular scanning is proposed. The arithmetic of this solution is so easy that the problem of low prototyping efficiency thatis induced by complicated arithmetic has been greatly resolved.In this paper, the post-treatment problem of the prototypes that are made from the high molecular powder material is researched. The post-treatment solution such as infiltrating wax or resin is developed and this can greatly improve the capability of the prototype. The prototypes that have several different colors are successfully manufactured. All these greatly extend the application area of the high molecular material prototype.The application in rapid tooling manufacturing of the resin-infiltrated prototypes is researched. It greatly improved the utilization efficiency of the prototype using this kind of post-treatment prototype directly into manufacturing wax patterns. In addition, these kind of post-treatment patterns have been used to develop the plaster mould and ceramic mould and both have made great progress.