Research On Properties Of Laser Welding Of Prepared High Transmission Black Thermoplastic

With the development of science technology and improvement of living standards, consumers put forward higher requirements of products on lightweight、safety、beautiful appearance and environmental protection。Meeting on basis of the previous requirements, engineer plastics change to replace wood、steel, and quickly develop. The shape and structure of especially complex products often can’t be a one-time injection molding, injection molded parts are connected through using a variety of connection technology. In recent years, compared with the traditional connection method of plastic, laser transmission welding is rapid rise in industrial production, with advantages of good quality, high degree of automation, high economic benefits.Because laser transmission welding of plastics have special requirements on the optical properties of materials, it’s limits the extensive use of technology. the paper products two kinds of black plastics which are applied to laser transmission welding, and analyses the performance of laser welding based on search for suitable to plastic of laser weldingIn this paper, by studying influence of different additives on laser characteristics of the plastics, a method preparing black plastics of laser transmission is described, high transmittance black plastic injection molding is making through adding anthraquinone and perinone to polycarbonate with different proportion. Mixing 1% carbon black and PC particles prepare absorbing light PC component. According to the optical test, it found that light transmittance of 0%, 2%, 4%, 6%, 8% additive of PC are respectively 91%, 87%, 81%, 76%, 71%, and absorption efficiency of PC components with absorbing light can reach more than 96%, in line with requirements of laser transmission welding plastics.The effects of the welding quality affected by parameters of laser transmission welding process is studied based on the approach combining both numerical simulation and experiments. Qualitative analysis by experiment shows functional relationship of how tensile strength, weld bead width and depth of the welded junction are influenced by laser power, welding speed, transmittance, and defocusing amount.Mathematic model has been developed for quantitative prediction of welding strength and welding process parameters via response surface method. Taking this model as objective function, particle swarm algorithm is applied to achieve multi-objective optimization. Numerical simulations of temperature fluctuations and thermal stress during the laser welding process are conducted by FEM. The temperature fluctuations which explain the causes of fluctuations of weld quality and welding area defects observed in experiments. The validity of numerical simulations is verified with the comparison between welding beam width computed in simulations and the width measured in experiments. It indicates the reason of different fault location via thermal stress analysis.The study shows that it could obtain satisfactory results manufacturing black PC components of either high transmission or absorption characteristic with laser transmission welding process. Parameters of laser transmission welding process do have an important effect on the quality of welding, welding area defects could be reduced to the least when welding temperature is controlled between 230℃-360℃. The result of the multi-objective optimization is P=35, V=5mm/s, T=91%, L=120mm, having a little error value comparing to the experimental value, which could also provide the basis and reference for industrial parameter optimization.