Basic Research On Hybrid Processing Of Laser Beam Machining Combined With Jet Electrochemical Machining

With the development of modern manufacturing technology, integrated innovation has become the focus of innovation in manufacturing technology. The hybrid processing of jet electrochemical machining and laser beam machining (JECM-LBM) is a new processing method which is combined with laser processing and electrochemical machining based on the idea of manufacturing innovation. The method bases on the application of a jet electrolyte, being aligned coaxially with the focused laser beam, on the workpiece surface. The processing principle is that material is removed mainly by laser processing and the recast layer is removed by the effect of jet electrolyte which consists of cooling to workpiece, transporting debris and electrochemical reaction with materials. The research of the new processing method involves some interdisciplinary knowledge points to be studied such as the laser attenuation in the electrolyte, the mechanical effect of the metal target by the laser in the electrolyte, and the interaction between the thermal physical process of laser and electrolytic process of jet electrolyte.The achievement of the new technology of JECM-LBM was the main goal in this research subject and the main research contents were included:1. According to the theoretical analysis of laser absorption and scattering of solution, the properties of laser attenuation in the electrolyte and the influence coefficient with concentration & temperature were researched with self-designed and manufactured set up. The results of the laser attenuation in the electrolyte provided the theoretical and experimental basis for the design of the JECM-LBM experimental system.2. According to the theoretical analysis of laser-induced mechanical effect of metal target in liquid, the vibration of stainless cantilever target by laser in the electrolyte were tested based on the test mechanism of piezoelectric accelerometer. The processing mechanism with the thermal- mechanical effects of laser in JECM-LBM was analyzed by the test. It was revealed that laser-induce mechanical effect of metal target has the benefit to carry debris away and reduce the recast layer.3. The general technical requirements for experimental system of JECM-LBM were summarized based on the analysis on the characteristics of JECM-LBM. The experimental system was developed by the general technical requirements, the results of research on the laser attenuation and laser-induced mechanical effect in the electrolyte. The jet equipment, the key component of the experimental system, was analyzed and optimum designed.4. According to the thermal-mechanical effect of laser and electrochemical effect of ECM, a two-dimension mathematical model for JECM-LBM was proposed based on the theory of temperature field and electric field. Based on the model, the shape of the machined holes by JECM-LBM was simulated by FEM software with the method of independent computing in time domain and superposition transform on boundaries. The simulation results have been verified by the experimental results. This modeling and experimental verification revealed the processing mechanism of JECM-LBM and laid the basis for the subsequent processing experimental research.5. Using the self-developed experimental system, JECM-LBM experiments were performed on stainless and nickel-based superalloy with nanosecond infrared laser and millisecond green laser. The experimental results were confirmed that JECM-LBM is feasible. Under the premise of maintaining a relatively high processing efficiency, the new hybrid process can reduce the thickness of recast layer to be less than 5μm, obtain high machining quality with none heat affected zone and better machining accuracy. The basic processing rules have been summarized by the comparison of the experimental results with different process parameters.The above theoretical analysis and experimental investigation were shown that JECM-LBM successfully combines laser beam machining and jet electrochemical machining and obtains the high machining quality & efficiency. The hybrid process has great potential as a new technical approach for the cooling holes in aeroengine hot components.