Research On The Technology Of Combined Micromachining Of Laser And Electrolysis

Recast layer and micro-cracks directly determined the service life and stability of parts.Laser machining had recast layer and electrochemical machining had low efficiency.In order to solve the problems,this paper proposed a new method of combined micromachining of laser and electrolysis.The mathematical model of combined micromachining was established.The reliability of the mathematical model and the feasibility of combined micromachining were verified by experiments.It had extremely vital significance in the manufacturing of key parts in aerospace and other fields.Therefore,with the purpose of engineering application,the main research contents of this paper were as follows.(1)A method of combined micromachining of laser and electrolysis of micro-holes without recast layer was proposed.For the machining of bare metal micro-holes,thermal effect of millisecond pulsed laser removed metallic materials,and small clearance electrochemical micromachining etched recast layer produced by laser.No recast layer was produced on the wall of bare metal micro-holes.Machining accuracy and efficiency were improved.For the machining of thermal barrier coated nickel based alloy micro-holes,nanosecond ultraviolet laser assisted with electrolyte removed thermal barrier coating materials,and small clearance electrochemical micromachining etched nickel based alloy materials.Coated alloy micro-holes had no recast layer.(2)The mathematical model of combined micromachining of laser and electrolysis was established.The temperature field model of laser micromachining and the electric field model of small clearance electrochemical micromachining were given.An accurate mathematical model of combined micromachining was established.The final shapes of bare metal micro-holes and thermal barrier coated nickel based alloy micro-holes were calculated.It provided the basis for the experimental research.(3)It used the experimental system of combined micromachining of laser and electrolysis to do experiments.Experimental materials included stainless steel and thermal barrier coated nickel based alloy.The reliability of the mathematical model and the feasibility of combined micromachining were verified.Firstly,the reliability of the mathematical model was verified by using ANSYS software and the experimental system of combined micromachining.The relative error of inlet diameter of numerical simulation of combined micromachining of stainless steel micro-hole was 0.84 percent and the relative error of machining depth was 12.80 percent.The relative error of inlet diameter of numerical simulation of combined micromachining of coated alloy micro-hole was 0.83percent and the relative error of outlet diameter was 1.60 percent.The relative errors were in range of 15 percent.The simulation results were the same as the experimental results.It verified the reliability of the mathematical model of combined micromachining.Secondly,combined micromachining experiments of stainless steel micro-holes and coated alloy micro-holes were studied based on metallographic microscope.The results showed that combined micromachining of stainless steel micro-holes did not have molten slag on the material surface or recast layer on the hole wall compared to single laser micromachining.Compared to single electrochemical micromachining,the efficiency and accuracy of combined micromachining of stainless steel micro-holes were improved by 51.35%and 30.43%respectively.The inlet and outlet of thermal barrier coated nickel based alloy micro-holes were clean and did not have residue.No recast layer was produced on the wall of the coated alloy micro-holes.By the research of this paper,it showed that the method of combined micromachining of laser and electrolysis had a good prospect of engineering application.It was used to guide machining of bare metal micro-holes and coated alloy micro-holes without recast layer.The experimental system of micromachining which was established in this paper laid the foundation for the engineering application of the method.