Patent

Electric spark deburring technology

2019-06-03

EDM deburring is an advanced deburring process that meets the requirements of “green manufacturing”. The process uses a pulsed power supply instead of a DC power source and processes it in a nonlinear electrolyte.


The process has the following characteristics:


1. Since the electrolyte used in the processing is a neutral inorganic salt aqueous solution, it will not pollute the environment; 2. The gap between the pulse current and the agitation of the pressure wave improves the electric field and flow field conditions in the machining gap, and reduces the electrolysis The requirement of liquid flow characteristics is therefore conducive to obtaining a stable and ideal processing process. 3. Since there is no cutting force during processing, no additional stress and surface deterioration layer are formed, so that the micro-geometry of the machined surface and the parts can be improved. Physical, chemical and mechanical properties.


The basic principle of EDM deburring processing is shown in the figure. The workpiece is connected to the positive pole of the pulse power supply, the tool electrode is connected to the negative pole of the pulse power source, and the tool cathode is placed corresponding to the burr portion of the workpiece. When processing, first add the electrolyte in the machining gap, and then turn on the pulse power supply. At this time, the oxidation reaction will occur on the anode surface of the workpiece, and the reduction reaction will occur on the tool cathode. During processing, a very thin oxide film is formed near the anode of the workpiece to provide isolation between the anode of the workpiece and the electrolyte. The oxide film has high electrical resistance and small electrical conductivity, which can prevent further dissolution of the anode surface of the workpiece and has a certain protective effect on the anode of the workpiece. Under the rapid scouring action of the electrolyte, the oxide film on the surface of the anode surface of the workpiece is thicker due to less diffusion; the oxide film on the surface of the anode surface of the workpiece (such as burrs, microscopic bulging parts, etc.) is thinner due to easy diffusion. Since the distribution of the oxide film is not uniform, the protruding portion such as the burr is always in contact with the fresh electrolyte, so the metal dissolution rate of the burr portion is much larger than other portions of the anode surface, so that the burr is quickly dissolved and removed. In addition, according to the electric field theory, it is known that the charge on the convex portion such as the surface of the part is concentrated, and the charge is less in the surface depression. Due to the uneven distribution of power lines, the power lines of the protruding parts are densely distributed, the current density is high, and the metal is removed more; the power line distribution of the four traps is relatively sparse, the current density is low, and the metal removal is less. Since the current density at which the burrs pass is much larger than other portions of the anode surface of the workpiece, the burrs are quickly dissolved. By properly adopting the tool cathode shielding technology, the burr can be selectively removed without affecting the original dimensional accuracy and surface quality of the anode surface of the workpiece.

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