Method for electrochemical machining

Abstract

The present invention relates to electrochemical machining (ECM) of conductive materials and can be used for manufacturing stamps, mould tools and other workpieces of complex shape at the finishing stage of the machining process. Method for electrochemical machining with an oscillating machining electrode comprises the step of applying rectangular microsecond current pulses synchronized with the moment when a machining electrode and workpiece electrode are moved to a minimum distance towards each other. During the machining process, the amplitude of current pulses is increased and the pulse duration is adjusted in such a manner that the trailing edge of each pulse corresponds to the moment of maximum electrical conductivity of the interelectrode gap, the amplitude being increased until a predetermined roughness of the surface to be machined is achieved. The present invention is aimed at optimizing the finishing stage of the electrochemical machining process by achieving a predetermined surface roughness with a minimum current intensity.

1 . A method of electrochemical machining using an oscillating machining electrode, the method comprising a step of applying rectangular microsecond current pulses synchronized with the moment of maximum approach between the said machining electrode and a workpiece electrode, wherein the machining process is performed within the following parameter range: pulse duration t=5 . . . 500 μs, amplitude current intensity j=200 . . . 10 000 A/cm 2 , wherein the amplitude and pulse duration are adjusted so as to make the trailing edge of each pulse corresponding to the moment of maximum electrical conductivity of an interelectrode gap. 
     
     
         2 . The method according to  claim 1 , characterized in that the maximum electrical conductivity of the interelectrode gap is determined by first increasing the amplitude or duration of current pulses until a precipitous voltage raise associated with a decrease of electrical conductivity of the interelectrode gap is observed, and then decreasing the amplitude or duration of the current pulses until reaching the value, at which the voltage value at the end of each pulse is minimal. 
     
     
         3 . The method according to  claim 1 , characterized in that maximum electrical conductivity of the interelectrode gap is determined by first increasing the amplitude or duration of voltage pulses until a precipitous current decrease associated with a decrease of electrical conductivity of the interelectrode gap is observed, and then by decreasing the amplitude or duration of the voltage pulses until reaching a value at which the voltage value at the end of each pulse is maximal. 
     
     
         4 . The method according to  claim 1 , characterized in that a predetermined roughness of the machined surface is achieved during the machining process by increasing the amplitude of current pulses while adjusting the pulse duration in such a manner that the trailing edge of each pulse corresponds to the moment of maximum electrical conductivity of the interelectrode gap, the amplitude being increased until the predetermined roughness of the machined surface is achieved. 
     
     
         5 . An apparatus for electrochemical machining of a workpiece electrode using a machining electrode, the apparatus comprising
 a current pulse generator, the current pulse generator generating rectangular microsecond current pulses synchronized with the moment of maximum approach between the machining electrode and the workpiece electrode, wherein the process is performed within the following parameter range: pulse duration t=5 . . . 500 μs, amplitude current intensity j=200 . . . 10 000 A/cm 2 , and   a pulse and amplitude regulator, the pulse and amplitude regulator adjusting the amplitude and pulse duration so as the trailing edge of each pulse corresponds to the moment of maximum electrical conductivity of an interelectrode gap.   
     
     
         6 . An article of manufacture obtained by a process of  claim 1 , characterized by low roughness of the machined surface. 
     
     
         7 . The article of manufacture of  claim 6 , which is a stamp, mould, or other workpiece having complex shape.