Medium plays an important role in the laser and fluid corrosion combining processing. Through X-ray diffraction analysis of chemical composition on the tool steel surface after laser-chemical processing, its chemical resultant is researched and analyzed. And the chemical reaction process of the laser and chemical hybrid etching of the tool steel material is explicated. Applied electron microscopy to surface morphology observation, under the action of laser beam, the effect of different chemical media corrosion on tool steel material is studied. The chemical mechanism of material removal of combining processing of laser and chemical corrosion on tool steels is discovered.
Si3N4 is difficult to be machined due to its hard and brittle nature. In order to improve its machining quality, a new method of ultrasonic-assisted laser machining is proposed. The machining device is established including Nd: YAG pulsed laser, ultrasonic vibration stage and water flow system. Etching experiments of laser machining with and without sample vibration in anhydrous conditions and in water conditions are studied respectively. A VM-3030E two-dimensional image measuring instrument is applied to detect shape and measure dimension of the sample. Microstructure morphology of the sample is observed by a JSM-7500F scanning electron microscope. Experimental results show that there are fewer slags on inner surfaces of V-shaped grooves when laser machining with water flow. The surface quality and depth-to-width ratio of grooves machined by laser with vibration on sample are improved significantly in comparison with those without vibration. The depth-to-width ratio of groove machined by laser with 90.1W vibration power is near twice than that without vibration.
Engineering practice education is important for engineering college students, but it needs the support of infrastructure and human input. With the number of students expanding dramatically in many local colleges or universities since the 21cn, resources of practice teaching can not meet the requirements of personnel training. With the development of the society and technologies, old practical teaching model also can not adapt to the demand of human resource market. This article presents the status of the current practice teaching and sums up many problems of local colleges and universities. In addition some reform ideas and exploration are presented in Anhui University of Architecture (AUA)
A water jet assisted laser composite processing device was used to study the influence of the laser input current and low-speed jet to etching amount .It established a empirical formula for relationship between the input current and the etching amount. Tests showed: under certain water speed, as the laser input current increased , the amount of etching was also increased; and when the current was constant, the jet speed was 25.9m/s, the etching amount reached a peak. This test also analyzed the factors that influenced the etching amount of water jets.
A wavelength of 1064nm Nd: YAG laser was used to groove on silicon, then studying the affect of quality and processing efficiency by incoming jet in laser etching course of silicon: Water jet reduced doss, cracks and other defects which might be produced on the surface of groove. Software of matlab was used to restore the topography of tank’s bottom; analysis shown that the water jet had a scouring effect influence on tank’s bottom. Introduction of the water jet caused the loss of the laser energy, but it could improve processing efficiency indirectly by blowing away the slag.
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