Papers by Author: Xiao Feng Shang

Abstract: The three-Dimensional model of 40BZ6-15 centrifugal pump is built by the Solidworks software. This paper employs three-D Navier-Stokes equation and standard equation, and uses MRF and STMPLE algorithm to simulate the internal flowing of the 40BZ6 centrifugal pump. The velocity field and pressure field are gained. Through a further analysis, the rule of the internal flow of the centrifugal pump is unveiled, and then the simulative results are compared with the experimental ones, which can provide the base for the further improvement of the centrifugal pump.

Abstract: Studying how and how much the factors affect on the cooling rate of workpieces is very significant to improve the ability of vacuum high pressure gas quenching furnace. From changing the structure and technology of nozzle-type vacuum high pressure gas quenching furnace, by a large number of computer simulation, this paper discusses some factors affecting the cooling rate. By changing the number and distance of nozzles on each wind pipe, we can better control the cooling rate and uniformity of workpieces. From the perspective of improved process, the number, shape, size and placement of the workpieces have certain effects on cooling rate, in which the placement of the workpiece is very significant and significant. The simulation results for the further development of new high-pressure gas quenching vacuum device provide a theoretical basis.

Abstract: The fabrication of metal parts is the backbone of the modern manufacturing industry. Laser forming is the combination of five common technologies: lasers, rapid prototyping (RP), computer-aided design (CAD), computer-aided manufacturing (CAM), and powder metallurgy. The resulting process creates part by focusing an industrial laser beam on the surface of processing workpiece to create a molten pool of metal. A small stream of powdered alloy is then injected into the molten pool to build up the part gradually. By moving the laser beam back and forth and tracing out a pattern determined by a CAD, the solid metal part is fabricated line by line, one layer at a time. By this method, a material having a very fine microstructure due to rapid solidification process can be produced. In the present work, a type of direct laser deposition process, called Laser Metal Deposition Shaping (LMDS), has been employed and developed to fabricate metal parts. The LMDS apparatus consists of four primary components: energy supply system, motion control system, powder delivery system, and computer control system. These components have their specified functions, but work in association with each other.

Abstract: This document investigates two kinds of generation algorithm of filling path, namely the subarea parallel reciprocating scan and the contour parallel scan, and proposes a kind of generation algorithm of subarea scanning vector. In the process of the generation of scanning vector, this algorithm has no need to perform area judgment to every scanning vector, and promotes the algorithm efficiency. Meanwhile, the connecting path between scanning areas was optimized, thus reducing the empty run, increasing the machining efficiency, and further improving the forming quality of the inside of metal parts.

Abstract: This document proposes a kind of contour path offset algorithm of Laser Metal Deposition Shaping (LMDS) technology. The contour path offset is determined by both laser spot radius and post-processing allowance. Besides, the offset direction can be judged through applying the cutter offset principle of NC machining. Then the formed intersecting points of a series of equidistant lines can be connected circularly to solve the contour path offset line. Since this algorithm fully considered the near-net shaping condition of LMDS and the combined effects of laser spot radius, the precision of as-formed metal parts could be further improved.

Abstract: Laser additive direct deposition of metals is a new rapid manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The advanced technology can build fully-dense metal components directly from CAD files without a mould or tool. With this technology, a promising rapid manufacturing system called “Laser Metal Deposition Shaping (LMDS)” is being constructed and developed. Through the LMDS technology, fully-dense and near-net shaped metallic parts can be directly obtained through melting coaxially fed powder with a laser. Typically, the microstructure and mechanical properties of the as-formed thin-wall part were tested and analyzed synthetically. The results show that there are different grain categories distributing in certain position of thin-wall part, and the mechanical properties represent as anisotropy.

Abstract: Direct laser deposition shaping is a state-of-the-art rapid prototyping technology. It can directly fabricate metal parts layer-by-layer without any die, mold, fixture and intermediate, just driven by the laminated CAD model. Accordingly, how to improve the quality of as-formed parts becomes an urgent issue in this research field. It is well known that as for the hot working, the heat history can generate enormous influence on the microstructure and mechanical properties of the parts. Due to the large quantity of heat introduced by laser fabrication process, it is necessary to build a temperature measuring platform to realtime monitor and control the temperature field in the laser fabrication process. As a result, such platform was created to communicate with computer by the temperature data collecting module and interface standard converting module, and achieved the temperature acquisition in the serial communication process through the Microsoft programming software. The experimental result proves the validity of the platform, which can provide effective boundary condition and experimental verification for the numerical simulation. In addition, the desirable temperature distribution can be obtained through the realtime process monitoring and effective parameter adjusting.