Researches On New Type Control System And Key Techniques Of Sls Rapid Prototyping

As an important branch of Rapid Prototyping, Selective Laser Sintering (SLS) is fallowed with great interest by the researchers in the field of manufacturing for it is widely usage in the sintering of metal polymer, ceramic and other powder.The control system and the key techniques of a new SLS rapid prototyping are studied systematically. And some innovative researches and conclusive works in the thesis are presented as follows:1. According to the technique characteristic of SLS rapid prototyping, an open type CNC system that consist of a PC computer and NC function board is used, and a new. SLS control system method is developed successfully. In this system, not only a single CPU concentrate control and the multiple task parallel processing method are employed, but also the advantages of comical programmable logic part and CPU control are used, so that, the good generality, expansibility and real time characteristly of the system developed can be obtained, and the hardware integrity and the credibility can be improved.2. According to the servo system feature of SLS rapid prototyping and parameter optimization of PID controller, the determination of following errors and smooth correction of order are carried out to reduce location errors and to enhance properties of servo system. High accurate dual-closed-loop control method is also investigated in detail, in order to issuer high accurate prototyping parts..3. A numerical computation model for predicting the sintered depth in selective laser sintering is built up. The factors of the material thermal physical properties with temperature and un-uniformed distribution of laser intensity across the beam diameter have been taken into account in the model. The problem was formulated by a three-dimensional transient heat transmission model and the transient heat transfer differential equation is solved by a finite differentiate method. The results show that the model can be used to estimate the sintered depth and to control accuracy of prototyping parts.4. Process of technique SLS Rapid Prototyping are studied systematically. The rapid manufacturing of fusible pattern for precise casting mould with investment casting is carried out successfully. This offeres a new technology of applying SLS in precise casting. The rapid manufacturing of molding tool and electro dischargemachining electrode mould are achieued successfully. This method offers a new way for EDM electrode manufacturing.All of works in this thesis show that the combination of SLS and conventional or non-conventional machining is an effective mean to obtain the rapid manufacturing of metal part, and it will be a certain developing trend of SLS too.