【作者】 王健；

【导师】 陈冰；

【作者基本信息】 湖南科技大学 ， 机械工程， 2023， 硕士

【摘要】 C/SiC复合材料由于其独特的性质,而被广泛应用于航空航天、交通制动、空间探测等领域,也正是由于其材料特性而被难以高效、精密、低损伤去除加工。目前,单一方式加工C/SiC复合材料在精度和效率上已经不能满足要求,由于纳秒脉冲激光烧蚀去除材料的效率远大于磨削加工效率,但烧蚀后的加工质量较差,而磨削加工属于超精密加工,加工质量好,但加工效率远低于激光加工。因此,本文以2.5维C/SiC复合材料为研究对象,融合高效的激光加工技术和精密的磨削加工技术,开展激光-磨削链加工2.5维C/SiC复合材料凹槽的的实验研究。首先,开展纳秒脉冲激光加工、磨削加工、激光-磨削链加工C/SiC复合材料凹槽对比实验。分析不同加工方式对C/SiC复合材料凹槽截面、底部和侧壁表面质量和微观形貌的影响,并对加工后的凹槽表面粗糙度进行测量,从理论上计算了不同方式加工凹槽所用的时间,同时揭示了C/SiC复合材料的磨削去除机理及砂轮磨损形式。其次,通过单因素控制变量实验,探究了不同激光加工参数对烧蚀后的C/SiC复合材料凹槽尺寸特征及形貌的影响。分析了激光扫描频率和扫描间距对烧蚀后的凹槽尺寸特征及形貌的影响;并对材料的烧蚀机理进行了分析;根据烧蚀凹槽质量的评价标准,优选出精度高、质量好的激光加工参数,用于后续激光-磨削链加工C/SiC复合材料凹槽中的激光加工。最后,进行激光-磨削链加工C/SiC复合材料的磨削工艺优化实验。研究凹槽侧壁锥度与磨削余量的工艺关系,设计磨削加工方案。通过正交设计方法开展了激光-磨削链加工C/SiC复合材料的磨削加工参数优化实验,对凹槽底部的表面粗糙度S_a进行了极差、响应曲线和方差分析,优选出加工质量最好的磨削参数,并探究了激光加工、激光-磨削链加工对C/SiC复合材料凹槽形貌和加工精度的影响。结果表明:当激光功率80 W、扫描速度300 mm/s、扫描频率200 k Hz、扫描间距为25μm、磨削深度30μm、磨削速度5000 r/min、进给速度10 mm/min时,激光-磨削链加工C/SiC复合材料凹槽的加工质量和加工效率最高;与激光加工和磨削加工C/SiC复合材料凹槽相比,激光-磨削链加工C/SiC复合材料凹槽后的尺寸精度、形状精度、表面质量明显更优;与磨削加工相比,激光-磨削链加工效率约为磨削加工的14/25,砂轮磨损程度轻,材料表面损伤小,实现了2.5维C/SiC复合材料凹槽的高效、精密、低损伤加工。更多还原

【Abstract】 C/SiC composites are widely used in aerospace,transportation braking,space exploration,and other fields due to their unique properties,but they are also difficult to be processed with high efficiency,precision,and low damage removal.At the moment,the single method of processing C/SiC composites cannot meet the precision and efficiency requirements,the efficiency of nanosecond pulsed laser ablation to remove the material is much greater than that of grinding processing,but the processing quality after ablation is poor,whereas grinding processing is ultra-precision processing with good processing quality,but the processing efficiency is much lower.Therefore,in this paper,we take 2.5 dimensional C/SiC composites as the research object,integrate the efficient laser processing technology and the precision grinding processing technology,and carry out the experimental study of laser-grinding chain processing of 2.5 dimensional C/SiC composite grooves.Firstly,the comparative experiments of nanosecond pulsed laser processing,grinding processing,and laser-grinding chain processing of C/SiC composite groove were carried out.The effects of various processing methods on the surface quality and microscopic morphology of the cross-section,bottom,and side walls of C/SiC composite grooves were investigated,and the surface roughness of the processed groove was measured.The time required to process the grooves using various methods was theoretically calculated,and the grinding removal mechanism of C/SiC composites and form of grinding wheel wear were also revealed.Secondly,the single factor controlled variable experiments were used to investigate the effects of different laser processing parameters on the dimensional characteristics and morphology of the ablated C/SiC composite grooves.The effects of laser scanning frequency and scanning spacing on the dimensional characteristics and morphology of the ablated grooves were investigated,as well as the ablation mechanism of the material;laser processing parameters with high precision and good quality were preferably selected for the subsequent laser processing in the laser-grinding chain for processing the grooves of C/SiC.Finally,the grinding process optimization experiments of laser-grinding chain processing C/SiC composites were conducted.The process relationship between the sidewalls taper of the groove and the grinding allowance was investigated,and the grinding processing scheme was designed.The experiments were carried out to optimize the grinding parameters for laser-grinding chain processing of C/SiC composites by the orthogonal design method.The extreme difference,response curve,and ANOVA were performed to determine the surface roughness S_a at the bottom of the groove,and the grinding parameters with the best processing quality were optimized.The results showed that the quality and efficiency of laser-grinding chain processing of C/SiC composite groove were the highest when the laser power was 80 W,the scanning speed was 300 mm/s,the scanning frequency was 200 k Hz,the scanning spacin was 25μm,the depth of cut was 30μm,the speed of cut was 5000 r/min,and the feed rate was 10 mm/min.Compared with the laser and grinding processing of C/SiC composite groove,the dimensional accuracy and shape accuracy of the laser-grinding chain processing were significantly better than those of the laser and grinding processing of C/SiC composite grooves,and compared with grinding,the processing efficiency of the laser-grinding chain was about 14/25 that of grinding,the abrasive wheel wear was light,and the material surface damage was small.Highly efficient,precise and low-damage processing of 2.5 dimensional C/SiC composite grooves were achieved.更多还原