Papers by Keyword: Process Parameter

Abstract: Recently the problems of resistance spot welding (RSW) stainless steel railway vehicles are causing more attention for poor surface quality. Lap laser welding of stainless steel is investigated with OED(Orthogonal experimental designing ) in this study to replace RSW with the aim of to increase the aesthetics of the car body by eliminating visible indentation on the surface and the flatness of the skin reducing welding deformations. After welding tensile tests and microstructure analysis are performed. The optimization of process parameters were: laser power =2.5kW；welding speed=2.2m/min, focal position=0mm. The fusion zone is symmetrical about the axis of the laser beam and no welding cracks or porosity can be found in any of the welds. This work has great significance of improving the manufacturing level of stainless steel railway vehicles.

Abstract: In this paper, with the milling processing of aluminum-alloy thin-walled parts as the research object, using software AdvantEdge, a milling simulation model is developed to study milling parameters affect on the cutting force, heat and catenation. It is found that by adjusting the ratio of milling parameters, the effects of cutting forces and heat can turn to the favorable direction of workpiece. In addition, we combine numerical simulation with experiments to explore the law of optimization of process parameters. It is discovered that the method of improving the milling speed and reducing the cutting depth properly can ensure the milling efficiency and the quality of the workpiece, providing a scientific insight for achieving high-quality, low-cost and efficient thin-walled parts manufacturing.

Abstract: In order to improve effect of VSR（vibration stress relief）for large machine tool body, the VSR process parameters must be optimized. This paper studies mechanism of VSR and determination principle of process parameters. Using finite elements method, the vibration modal analysis of large machine tool body are applied to determine VSR frequency, exciting position, supporting position and detecting sensor position. Based on analysis above, the harmonic response analysis is applied to work out relationship between exciting force and dynamic stress. In this way, the exciting force can be determined. The experiment result shows the determination method of VSR process parameter in this paper is feasible and effective. This method is worthy of application and dissemination for large size castings.

Abstract: The dimensional accuracy and mechanics properties of parts made by Selective Laser Sintering depend greatly on the sintering process parameters. The influence of process parameters on warping weight of parts sintered by blends of polyamide (PA12) and high density polyethylene (HDPE) was studied. The relationship between the process parameters and the warping height was presented. The surface morphology of the part and uniformity of powder mixed were analyzed by SEM. The optimum parameters of minimum warping height were obtained: preheat temperature 110°C, scan speed 300mm/s, laser power 21W, thickness of single layer 0.2mm.

Abstract: Aimed at the disadvantages of the lateral wire feeding in direct laser deposition (DLD), a novel device with coaxial inside-beam wire feeding is applied in the process based on the patent technology of “hollow laser beam and internal wire feeding’’. During the laser cladding process, laser beam can be coupled with wire accurately. The comparison experiments of laser cladding are carried out on the substrate of 45# steel with different process parameters. The effects of crucial process parameters, such as laser power, scanning speed and wire delivery rate on the cladding layer are dicussed. The optimum laser cladding process and related parameters are obtained. Microstructure of the cladding layer is characterized by scanning electron microscopy (SEM). Experimental results show that, wire melts adequately; the cladding layer is symmetrical and smooth; the microstructure is uniformly distributed with no porosity; firm combination with substrate is achieved.

Abstract: Porous NiTi shape memory alloys were fabricated by thermal explosion method using different Ti and Ni powder as initial materials. The effect of process parameters including heating rate, and particle size of Ti on pore characteristic and phase composition was analyzed. Microstructure, phase composition, and mechanical properties were studied by SEM, XRD, and compression test, respectively. The mechanism of thermal explosion reaction was studied. The results show higher heating rate and smaller Ti particle size result in higher porosity and bigger pores. The thermal explosion reaction starts with the melting of a eutectic between β-Ti(Ni) and Ti2Ni and the main phases of as-reacted products are TiNi phase which are the desired phases. NiTi2 and TiNi3 phases are also present in small amounts. The content of TiNi phase increases with increasing heating rate or decreasing Ti particle size. The compressive strength and Young’s modulus of compacts decrease with the increase of the porosity.

Abstract: The extrusion of a space frame must be followed by forming operations of some kind to obtain the desired shape/curvature, for example a stretch bending process. Therefore, one has to face with problems as production tolerances and cross-sectional distortions of the curved product. In house experience combined with trial–and–error procedures have been traditionally used to cope with the said problems. Aircraft frames show significant residual stresses as a consequence of plastic forming processes. A great number of variables, such as initial frame length and/or final additional stretch, can influence the stress state of frames determining their life and efficiency under operating loading conditions. In the present paper, we refer about the experimental evaluations of the residual stress state of aircraft frames which have carried out taking into account different process parameters. The experimental results obtained and discussed show some interesting trends: they demonstrate that the residual stresses of the formed component can be controlled and reduced.

Abstract: Discussed in detail using BP neural network to establish the quantitative relationship model between the process parameters and components density on the laser direct rapid forming (LDRF) metal parts, in which input of single-pass sintering model is: laser power (P), scanning speed (V ) and powder feeding rate (G), performance indicators to measure the width of the sintered layer (W) and height (H); input of multi-pass multi-sintering model is: P、V、G、scan spacing (D) and layer thick ( ), the performance measure for the density of sintered parts，And neural network simulation results and experimental results are analyzed and compared. The results show that using BP neural network model can quantitative analyze the effect on sintering process parameters and the sintering performance, the model for the optimization of LDRF process parameters has built the foundation.

Abstract: Multiscale visualization approaches are proposed to efficiently assist designers not familiar with statistical mathematics in determining the optimal process parameter schemes for achieving desired part quality in injection molding, based on which the parameters’ relative importance to part quality and their influence on either single quality index or comprehensive part quality can be visually described by the map of the sum of squared deviations, response surface diagram and distribution map of comprehensive part quality. The proposed visualization approaches are universal for analyzing the effects of process parameters on the quality of any injection-molded plastic parts although the mobile phone cover is utilized as an example in the presentation of our work.

Abstract: Laser transmission joint between biocompatible, dissimilar materials have the potential for application in biomedical and their encapsulation process. This paper is devoted to laser transmission joint between 0.1mm thick PET films and 0.1mm thick Titanium using near-infrared diode lasers. Response surface methodology (RSM) is used to develop mathematical models between the joining process parameters. The developed mathematical models are tested for adequacy using analysis-of-variance (ANOVA) method. In addition, the main effect of each parameter and the interaction effects with other process parameters are analyzed. Finally, the experimental results agree with those predicted indicate that the developed mathematical models can predict the responses adequately.