Study Of ELID Grinding Based On The Active Control Of Oxide Layer And Its Application

Electrolytic In-processing Dressing (ELID) is an efficient method of dressing metal bonded grinding wheels using electrolysis. It is particularly suitable for ceramics, superhard alloy and any other hard brittle materials ultra-precision grinding. The important characteristic of ELID grinding is the generated oxide layer take part in the grinding process. So, the oxide layer state directly relates to the grinding efficiency and machining quality, and has great influence in the ELID grinding.In this dissertation the oxide layer role and influencing factors in ELID grinding are analyzed firstly, the dressing current, the grinding force, and the vibration signal is used to characterize the oxide layer state respectively. The results show that the dressing current is closely agreed with the thickness, surface morphology, composition and intensity of the oxide layer. Even in the frequency domain, the grinding force and vibration signal are not associated with the oxide layer state.A new high-frequency pulse power source is proposed for ELID grinding in order to monitor and control the state of the oxide layer. It uses the superposition of big and small pulses to achieve periodical electrolysis and to adjust oxide layer state.Based on an analysis of current change with duty cycle, a pulse-base fuzzy control program is designed to control the state of the oxide layer within a certain range and the oxide layer grinding efficiency in different oxide layer states is studied. The results show that the new power source could maintain a stable grinding process, and it could control the state of the oxide layer with different grinding requirement.Base on the ELID surface grinding, an attempt of numeration for 3MZ1410 automatic bearing outer ring groove grinder is proposed. NI-7344 motion controller is used to control the servo motors which drive the ball screws to fulfill precise feeding movement. And the corresponding motion control programs are developed to meet the needs of ELID cylindrical grinding.Finally, a binding of grinding wheel, electrode and electrolytic cathode devices are designed and manufactured for ELID cylindrical grinding, and the experiments of electro-discharge truing and pre-dressing which used metal bonding CBN grinding wheel are implemented. By studying two different ELID cylindrical grinding methods, better grinding effect could be obtained when using the workpiece as the electrode. Without the complex electrolytic cathode devices, the vibration when the grinding wheel move into the workpiece can be avoided, and the grinding wheel can be dressed in real time. So it is easy to operate and use, and has wide range of applications.