Study On Electrochemical Machining Process Of Taper-shaped Medical Nickel-titanium Alloy Wire

Nitinol wire is widely used in medical treatment because of its super elasticity,good shape memory recovery,biocompatibility and other characteristics,and human tissue can coexist for a long time without causing harm.Due to the small cross-sectional area,special shape and soft texture of medical Nitinol wires,the traditional cutting and grinding processes are difficult and the processing efficiency and qualification rate are low.Although medical nickel-titanium alloy wire is more and more widely used in medical and other fields,there is no applicable processing method in China.Electrolytic processing process has no cathode loss,no macroscopic cutting force,high processing efficiency.From the viewpoint of the material characteristics and flexibility of taper-shaped medical Ni Ti alloy wire,electrolytic processing can be applied to the processing of taper-shaped medical Ni Ti alloy wire.In this paper,electrolytic processing process research is carried out on taper-shaped medical Ni Ti alloy wire as the research object,and the details are as follows:(1)For the technical requirements of electrolytic processing of nickel-titanium alloy wire,the law of electrolytic processing of nickel-titanium alloy wire forming was studied,and a scheme of electrolytic processing of nickel-titanium wire was proposed.In the electrolytic processing,the cathode is wrapped around the anode and moves in a straight line along the axial direction of the nickel-titanium wire,and the speed of the cathode is controlled during the movement according to the change of the diameter of the wire to form the conical shape of the alloy wire.The scheme of motion control,liquid supply,cleaning,drying,winding and releasing of nickel-titanium alloy wire for electrolytic processing is designed.(2)The design of electrolytic processing tooling for taper-shaped nickel-titanium alloy wire was carried out based on the electrolytic processing process scheme.According to the process scheme proposed earlier,the tooling such as measuring,cleaning,drying and winding device were designed to complete the overall layout of the electrolytic processing equipment for Ni Ti wire.In the cleaning program proposed to use the spray type ultrasonic cleaning cleaning method,can effectively remove the residues attached to the surface of nickel-titanium wire after electrolytic processing.(3)The electrolytic processing cathode of Ni Ti wire was designed and the flow field analysis was carried out.In order to realize the electrolytic processing of nickel and titanium wire,two cathode structure solutions were designed to meet the processing needs,conical and cylindrical,and the flow field simulation software was used to simulate the state of electrolyte entering the processing area under the two cathode solutions.(4)The conical medical nickel-titanium alloy wire electrolytic processing test was carried out.The designed tooling structure and cathode were used to build the test platform,and electrolytic processing tests were conducted on the self-developed electrolytic processing system for nickel-titanium alloy wire.According to the processing test results,the electrolytic processing parameters were adjusted and optimized several times,and the taper-shaped medical nickel-titanium alloy wire specimens that meet the requirements of the drawings were successfully processed,which verified the feasibility of the process plan.