Experimental Study On Grinding Wheel Of Polycrystalline Diamond With Femtosecond Laser Ablation

Polycrystalline diamond(PCD),as a super hard material with high hardness,good wear resistance and stable chemical properties,is widely used in high speed nc machining tools.Because polycrystalline diamond has many excellent mechanical properties,polycrystalline diamond tool is widely used in turning and grinding of modern industry,and its life span is longer than that of ordinary cemented carbide tool.However,its difficut to process PCD due to its quality of high hardness andgood wear resistance.The traditional grinding process has a long processing cycle,low processing efficiency and other shortcomings.Long pulse laser processing has energy accumulation,serious thermal damage and other adverse effects.In this thesis,ultrashort pulse femtosecond laser is adopted.Femtosecond laser has the characteristics of extremely short pulse width and extremely high single pulse energy,and has obvious advantages for the precision machining of ultra-hard materials such as diamond.At present,polycrystalline diamond is usually used as a tool for high speed cutting of non-metallic materials and non-ferrous metals.General diamond grinding in the anterior horn is negative rake angle when grinding(grinding apex angle is greater than 90 °).The normal force is greater than the tangential force at this time,and influence on grinding surface quality.This thesis put forward the femtosecond laser ablation machining polycrystalline diamond grinding wheel,processing abrasive apex angle less than 90 ° to get positive rake angle.Therefore,the ultrashort femtosecond pulse laser ablation machining polycrystalline diamond test platform was built.The polycrystalline diamond microarray and the polycrystalline diamond microarray with positive front angle are fabricated by laser ablation with optimizing process parameters.The feasibility of grinding hard and brittle materials with positive front angle abrasive grains was verified by grinding contrast test with electroplated diamond end grinding wheel.The main contents are as follows:(1)The processing difficulties of diamond materials and the processing characteristics of femtosecond laser were introduced and the research of diamond grinding wheel at home and abroad were summarized.A test platform consisting of femtosecond laser was built.(2)According to the principle of single factor test,the ablation effects of average laser output power,laser spot overlap rate and laser repeat scanning ti mes on polycrystalline diamond were systematically studied.When the average laser power is 13.6w,the laser spot overlap rate is 81%,and the laser repeat scanning is 100 times,the processing effect is the best,and the combination of this process parame ter is used to produce microarray junction with good surface quality on polycrystalline diamond.(3)Based on the process test in the previous chapter,the microform array structure and the polycrystalline diamond end face grinding wheel with positive fron t angle were processed on the customized polycrystalline diamond end face sample,and the surface processing quality and the processing quality at the bottom of the groove were observed through the ultra-depth of field 3d microscope.(4)Polycrystalline diamond end face grinding wheel with positive front angle and electroplated diamond end face grinding wheel were respectively used to conduct plane grinding test on YG8 cemented carbide,and the surface quality of the workpiece after grinding and the wear condition of the grinding wheel on the end face after grinding were compared and analyzed.