Abstract
Arc spraying for rapid tooling technology is an advanced manufacturing technology on the basis of rapid prototyping combined with arc spraying technology.High melting steel-based moulds become a hot point at present. This paper makes a optimization study of high-melting rapid tooling process by theory combined with test,and trial-produces a high-melting automobile bonnet tool.
Make a research about the effect of spray current, spray voltage, wire feeding voltage on the arc, obtain the quantitative relation of them, the voltage of spraying 3Cr13 is determined; make a quantitative study on the relation of spray current and coating temperature through adjusting wire feed rate to change spray current, research the effect of spray current on the spray coating temperature. Spraying current is determined initially. Study the effect of initial pressure and grain size on the axial velocity and temperature field of jet by means of simulation and test, make a quantitative analysis on the change process of high-speed particle velocity and temperature in the jet flow, and obtain the distribution picture of jet flow velocity and temperature.
Analyze the effect of spray velocity and temperature on the coating stress by simulation. Simulate the whole transformation process of molten drop with different velocity under comprehensive consideration of hydrodynamic force and heat transfer feature in the molten drop, and get the flat degree of molten drop under different spray velocity directly. Study the thermal stress distribution of coating and substrate using layered model and Birth and Death element method; obtain the effect of temperature difference between the coating and substrate on the thermal stress in the coating.Propose some reasonable advice on reducing the coating stress, and provide reference on the selection of spray process parameters connecting the results of molten drop velocity and temperature distribution under different spray process parameters.Study the effect of spray distance and substrate preheating temperature on the bond strength between substrate and substrate. Conduct the experiment under different process conditions (contain different spray distance and substrate preheating temperature), test the bond strength between coating and substrate, study the effect of process condition on the bond strength, and observe the flat state of particle under different process conditions using scanning electron microscope. Study the relation of bond strength and substrate surface roughness through a measuring method of surface roughness.
Make use of 3Cr13 and Chlorine oxygen cement substrate under the optimization of spray process parameter, trial-produce a automobile bonnet tool. The test shows that the thickness of tool shell is 5mm, and the hardness is HRC48.
Key word Arc spraying；rapid tooling；spray process；stress；bond strength
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