| RB-SiC and alumina ceramics are widely used in the fields of mechatronics,aerospace,due to their high thermal conductivity,high wear resistance and chemical stability.RB-SiC and alumina ceramics have high hardness and brittleness,which are typical difficult-to-machine materials.Therefore,grinding with diamond wheels are the most important method for the machining of advanced ceramic.The selection and optimization of precision grinding and dressing of diamond grinding wheels are the main factors,affecting the surface precision and surface quality of RB-SiC.In this paper,an in-process precision abrasive waterjet dressing system for diamond grinding wheels was designed based on the precision machining requirements of RB-SiC mirrors and alumina ceramic battery separators.This system was used for in-process and on-machine dressing of metal-based diamond grinding wheels precisely.The processing parameters of grinding wheel dressing and two advanced ceramic materials precision grinding was optimized.Firstly,needs of the abrasive waterjet dressing of diamond grinding wheel,an in-process abrasive waterjet dressing system for precision forming grinding machine and machining center was developed.The system consists of a jet boost and regulate pressure system,an XY two-axis motion and control system.The control system includes two modes of manual and automatic control.The minimum feed resolution is 2μm.The system is well-matched with the machine tool,and the dressing precision is high.The effect of jet pressure and grains size on the surface morphology of the grinding wheel was studied,and the high-precision dressing of the two-grain size bronze-bonded diamond wheels was realized.The 120#bronze-bonded diamond wheel was dressed with jet pressures of 30 MPa,40 MPa,and 50 MPa,respectively.The three-dimensional surface roughness parameters were used to evaluate the abrasive protrusion height and distribution on the surface of the grinding wheel quantitatively.When the jet pressure is 40 MPa,the average height of the abrasive grains obtained is more than 1/3 of the diameter of the abrasive grains of the grinding wheel,and the number of effective abrasive grains on the surface of the grinding wheel is the largest.The 1500#diamond grinding wheel was dressed by abrasive water jet with SiC abrasives of 300#,700#,and 1500#respectively.The surface morphology of the dressed grinding wheel shows that the abrasive water jet with 700#SiC abrasive can obtain optimal dressing effect.The orthogonal grinding experiments of RB-SiC and alumina ceramics were carried out by employing 120#and 1500#bronze-bonded diamond wheels diamond grinding wheels after high-pressure abrasive waterjet dressing.The grinding process parameters and grinding surface roughness were analyzed.With the objective of minimum grinding force and minimum surface roughness respectively,the optimal processing parameters for two kinds of ceramic materials were obtained by grinding with the coarse and fine grained diamond wheels.The grinding mechanism of the two materials was analyzed and compared.The composite removal mechanism of ductile removal and brittle removal was mainly existed on the surface of RB-SiC.The surface of alumina ceramic was mainly brittle removal.The in-process dressing of abrasive water jet was investigated.The influence of the parameters of abrasive water jet on the grinding force,the surface topography of the grinding wheel when grinding RB-SiC was discussed.The validity of in-process dressing of the abrasive water jet was verified.The RB-SiC ground surface obtained by the in-process dressing method was observed,it was found that the ductile removal trace of RB-SiC surface was eroded and the diameter of the broken pit became smaller. |
PDF Full Text Request