Research On Precision Polishing Of Hard And Brittle Materials And Its Automatic Control Technology

With the development of industrial technology,hard brittle materials are widely used in military,national defense and civilian fields due to their excellent characteristics,such as high strength,high hardness,high wear resistance,corrosion resistance,heat insulation and chemical stability.But at the same time,because of its brittleness,easy to damage the surface layer and so on,it also brings more difficulties to the processing.Chemical mechanical polishing is one of the few methods that can be used for ultra-precision machining for most hard and brittle materials.In this paper,aiming at study the technology of chemical mechanical polishing of hard and brittle materials,polishing removal rate in the process is theoretically calculated,traditional polishing machine is remodeled for automatic processing and a chemical mechanical polishing experiment system is established.Then taking K9 glass as an experiment example,we study the effect of different processing parameters on the removal rate and processing quality,and summed up the change rules.At the same time,on the basis of theoretical analysis and experimental system,the plane and aspheric processing of K9 glass are completed.In the first chapter,the commonly used machining methods of hard and brittle materials at present are introduced as well as the realistic requirement of hard and brittle materials applied in many critical situations in several fields.By analyzing their advantages and disadvantages,chemical mechanical polishing using fixed particles is indicated to be applied to almost any type of hard and brittle materials.Then the relevant research situations at home and abroad are introduced from two aspects of processing technology and computer-controlled.Finally the weak links existing in the current study are summarized,the main research content is proposed,and the research meaning is pointed out.In the second chapter,the basic principle of chemical mechanical polishing is introduced firstly.Then a mathematical model is established for the removal process and the influence of the eccentricity rate and the speed ratio on the processing results is analyzed.Based on this analysis,the resident time is solved.Finally,the whole design idea of computer controlled polishing is briefly described.In the third chapter,the automatic transformation of CNC polishing machine is introduced which is the basis for the follow-up experiment of automatic processing.First,the design of the mechanical part is introduced,and the key parameters,such as the polishing pressure and the friction torque,are calculated and checked.Secondly,the design of the control part is introduced,including the algorithm of the single axis speed curve control and the multi axis path synchronization control.In the fourth chapter,the influence of processing parameters,such as spindle speed,polishing pressure,abrasive particle size and flow rate of polishing fluid on removal rate and machining quality is analyzed synthetically.And then a set of effective polishing process parameters is summed up to provide some theoretical guidance for the actual processing operator.In the fifth chapter,the key problems in polishing process and their solutions are introduced.Then,the polishing process of aspherical K9 glass is taken as an example,and the complete processing technology of chemical mechanical polishing and the algorithm of aspheric automatic processing are described in detail.In the sixth chapter,the main research work is summarized,the shortages existing in the research are pointed out,and relevant assumptions and prospects for further study are put forward.