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对液体环境条件下的同轴水射流辅助激光加工技术及其加工机理进行了初步研究,并建立了加工实验装置,分别研究了加工效率和加工锥度随激光能量、水射流流速、喷口与工件间隙的变化规律。实验结果表明:同轴水射流辅助激光加工效率随着激光能量、水射流流速的增加而提高,当喷口与工件间隙约为3 mm时加工效率较高;加工微孔的锥度随着激光能量、水射流流速的增加而减小、随着喷口与工件间隙的增加而增大,当间隙大于5 mm时锥度基本保持不变。最终,利用优化的工艺参数,加工出锥度约为2°且无热影响层、再铸层和微裂纹的表面完整性好的微孔。 相似文献
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随着微孔加工技术的逐渐成熟,激光微孔加工的应用越来越广泛,但依靠单一激光束进行微孔加工仍存在一些问题,尤其是在深孔加工方面,出现了以激光束为主、多能量场辅助的复合打孔技术,并逐渐成为了热点。针对液体辅助激光微孔加工研究领域,总结了水基辅助激光打孔、水基超声振动辅助激光打孔、水基超声?磁场辅助激光打孔和电解液/水射流辅助激光打孔等方法。在水基的基础上,加入了超声、磁场和温度场,使得辅助场变得多元化,在多层面上进行复合加工。介绍了不同辅助加工方法的去除材料机理及加工后材料特性的变化,水起到冷却的作用,但在水层下会形成空化气泡,超声振动可以击溃气泡,磁场和温度场为材料残渣提供了能量,具体表现在热效应、材料去除速率、打孔深度、重铸层及裂纹等方面。影响微孔质量的因素有微孔锥度、深径比、孔的圆度、重铸层厚度、热影响区、微裂纹和粗糙度等,主要对微孔锥度、深径比及其他指标进行了分析,总结了加工方法对微孔质量的影响。 相似文献
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目的 优化激光路径填充方式以减少皮秒加工圆凹坑底部的堆积现象,并探究基于该激光路径填充方式的皮秒激光关键参数对Ni60/WC涂层表面圆形凹坑形貌参数的影响规律。方法 采用搭建的紫外皮秒激光微加工平台在Ni60/WC涂层表面加工预先规划的直径为230μm的圆凹坑,通过白光干涉仪测试加工所得圆凹坑的整体三维形貌对圆凹坑底部形貌进行表征。采用同心圆网格复合激光路径填充方式对圆凹坑底部堆积现象进行优化,并通过单因素法分析该路径下皮秒激光关键参数,即加工功率、扫描次数、扫描速度对圆形凹坑深度、直径和圆度系数的影响规律。结果 通过优化的同心圆网格复合激光路径填充方式加工所得圆凹坑材料去除体积为7.59×106μm3,轮廓算术平均高度为21.37μm,对比原始的网格激光路径填充方式,加工的圆凹坑底部无明显堆积;基于此激光路径填充方式,在测试工艺参数范围内,圆凹坑深度、直径和圆度系数随激光功率的增大呈二次函数增大;随着扫描速度的增大,圆凹坑深度、直径呈线性减小,圆度系数呈线性增大;圆凹坑深度、直径和圆度系数随扫描次数的增加均呈线性增大。结论 同心圆网... 相似文献
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基于TC4复合材料研究了大余量去除和大直径孔的电解钻孔加工技术。首先,设计了工具阴极结构,在工具阴极侧面绝缘基础上采用电场仿真研究了工作圈高度对加工效果的影响,再针对不同钻孔深度进行流场仿真分析,揭示电解钻孔加工流场分布规律并探究了工具阴极端面出液孔数量对加工稳定性的影响;其次,对陶瓷绝缘和电泳绝缘两种不同绝缘方式下的工具耐用性进行了试验对比,结果表明:高电压下陶瓷绝缘层的耐用度明显优于电泳绝缘层;然后,采用陶瓷绝缘工具阴极对不同加工参数下的电解钻孔深度、入口直径、圆度、锥度等性能进行比较并优化了加工参数;最后,利用优选的参数加工得到入口直径21.43 mm、孔深39.19 mm、圆度误差0.028 mm和锥度0.068°的盲孔。 相似文献
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采用正交试验研究并分析了飞秒激光制孔参数激光功率、单层作用时间、单层进给量对DD6高温合金孔型、效率及冶金质量的影响规律.研究发现:在一定范围内随着功率增大,微孔加工效率有所提升,但受激光能量密度与去除材料量的影响,微孔孔型呈现从正锥到倒锥再到正锥的规律,且重熔层出现的几率及厚度也相应增加;当单层作用时间越小或单层进给量越大时,材料与激光焦点作用容易形成倒锥,且激光制孔效率越高,重熔层厚度越小.通过试验验证,在功率为15 W、单层进给时间600 ms、单层进给量0.04 mm的条件下,飞秒激光在DD6单晶高温合金上可获得孔型较好、孔壁周围无重熔层、无微裂纹及热影响热影响区的微孔. 相似文献
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Modelling and analysis of pulsed Nd:YAG laser machining characteristics during micro-drilling of zirconia (ZrO2) 总被引:1,自引:0,他引:1
A.S. Kuar B. Doloi B. Bhattacharyya 《International Journal of Machine Tools and Manufacture》2006,46(12-13):1301-1310
Pulsed Nd: YAG laser beam has great ability for micro-machining of ceramic materials because of high laser beam intensity at low mean beam power, good focusing characteristics due to very small pulse duration, small kerf widths and narrow heat effected zones. In the paper, experimental investigations into CNC pulsed Nd:YAG laser micro-drilling of zirconium oxide (ZrO2) have been carried out. Influence of laser machining parameters on the HAZ thickness and phenomena of tapering of the machined micro-holes has been experimentally investigated. Response Surface Methodology-based optimal parametric analysis has been performed to determine the optimal setting of process parameters such as pulse frequency and pulse width, lamp current, assist air pressure for achieving minimum HAZ thickness and taper of the micro-hole machined by pulsed Nd:YAG laser. Minimum HAZ thickness has been obtained as 0.0675 mm when the lamp current, pulse frequency, assisted air pressure and pulse width are set at optimal parametric setting i.e. 17 amp, 2.0 kHz, 2.0 kg/cm2 and 2% of the duty cycle, respectively. Minimum taper has been achieved as 0.0319 at optimal parametric setting i.e. the lamp current of 17 amp, pulse frequency of 2.0 kHz, assisted air pressure of 0.6 kg/cm2 and pulse width of 2% of the duty cycle. Analysis has also been carried out for multi-optimisation of both the responses i.e. HAZ thickness and taper during pulsed Nd:YAG laser micro-drilling on ZrO2. 相似文献
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激光表面微织构工艺试验及应用研究 总被引:3,自引:3,他引:0
在声光调Q二级管泵浦固体光源Nd:YAG激光器基础上,采用"单脉冲同点间隔多次"激光微加工工艺,对45#钢试样表面进行激光微织构加工。分析了离焦量、泵浦电流、重复频率及重复次数对微织构形貌的影响规律。工艺试验表明,微凹腔的直径和深度随着泵浦电流的增大而增大,随着重复频率的增加呈减小的趋势,微凹腔深度随脉冲次数的增加呈近似线性增加,而微凹腔直径呈缓慢减小趋势。通过对某型号四缸汽油机的台架性能试验研究,表明与传统平顶机械珩磨相比,采用激光珩磨技术的汽油机机油耗要比原机降低56%,燃油耗降低1.94%~4.5%。 相似文献
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0 IntroductionLaserbeamweldingisoneoftheadvancedweldingtechniqueswidelyappliedtoindustryandscienceresearch.Becauseofmanysuperiorityoflaserweldingincludinghighefficiencyandspeed,smalldeformation,deeppenetration(highratioofpenetrationtowidthofweld),fewdef… 相似文献
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Yinzhou YanLingfei Ji Yong BaoYijian Jiang 《Journal of Materials Processing Technology》2012,212(6):1257-1270
A major challenge in laser percussion drilling of thick-section ceramics is to obtain a low taper and low spatter deposition hole leading to high quality post-processing. In order to achieve the fine hole drilling, it is important to understand the mechanism of laser percussion drilling. In this paper, an experimental and numerical study on laser percussion drilling was carried out. A two-dimension (2D) axisymmetric finite element (FE) model for simulation of temperature field and proceeding of hole formation during percussion drilling was developed. The FE model was validated by the corresponding experiment. Furthermore, a theoretical model for evaluation of temperature at melt front and velocity of melt ejection was presented in order to further validate the FE model and study the spatter deposition. The effects of laser peak power, pulse duty cycle and pulse repetition rate on hole diameter and spatter deposition were investigated by the developed models and experiments, in which the simulated results were in good agreement with the experiments. The study indicated that the size and temperature of the melt front significantly affected the hole diameter formation and spatter deposition during laser percussion drilling. The characteristic of melt front was mainly determined by the employed laser peak power, pulse repetition rate and pulse duty cycle. Based on the experimental and numerical study, the process parameters were optimised and a drilled-hole with low taper and low spatter deposition was obtained using a 3.5 kW CO2 laser. A microstructural and element compositional study was also performed in this work, by which the characteristics of microstructure and element composition in HAZ around laser drilled hole were revealed. 相似文献
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针对脉冲过渡熔化极气体保护焊(gas metal arc welding,GMAW)电弧和短路过渡GMAW 电弧,通过保持 GMAW 电弧正常态,Nd:YAG 激光水平逐层、逐点扫描穿过脉冲电弧区域的试验方式,获得了Nd:YAG 激光穿过GMAW 电弧后的激光折射和散射结果.试验发现,波长为1.064μm的Nd:YAG激光穿过脉冲GMAW 电弧激光光斑会略微变小,并且不同电弧区域对激光的影响能力基本相同;激光穿过短路GMAW电弧后激光光斑也会略微变小,不同电弧区域对激光的影响也基本相同.结果表明,GMAW电弧可以近似看作各项同性的激光传输介质,还可以近似认为GMAW电弧对波长1.064μm的Nd:YAG激光是透明的.Abstract: By keeping gas metal arc welding(GMAW)arc normal position and Nd: YAG laser parallel crossing GMAW arc,refrangibility of GMAW arc to Nd: YAG laser was measured.The results indicate that when Nd:YAG laser crosses pulse GMAW arc,laser radius will decrease slightly.And the influence of pulse GMAW arc of different part to Nd : YAG is almost same.Similarly,when Nd: YAG laser crosses short-circuiting pulse GMAW arc,the radius of the laser will decrease slightly too.By considering this phenomenon from welding point of view,GMAW arc can be regarded as transparent substance and optic isotropy to Nd:YAG laser. 相似文献
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The present study investigates the relationships and parameter interactions between six controllable variables on the hole taper and circularity in laser percussion drilling. Experiments have been conducted on stainless steel workpieces and a comparison was made between stainless steel and mild steel (IMechE Part B: J. Eng. Manufact. (in press)). Laser peak power, laser pulse width, pulse frequency, number of pulses, assist gas pressure and focal plane position were selected as independent process variables. The central composite design (CCD) was employed to plan the experiments in order to achieve required information with reduced number of experiments.The process performance was evaluated in terms of equivalent entrance diameter, hole taper and hole entrance circularity. The ratio of minimum to maximum Feret’s diameter was considered as circularity characteristic of the hole. The models of these three process characteristics were developed by linear multiple regression technique. The initial models were computed according to the least squares procedure and were finalised by stepwise regression method. The significant coefficients were obtained by performing analysis of variance (ANOVA) at 1, 5 and 7% levels of significance. The final models were checked by complete residual analysis and finally were experimentally verified.It was found that the pulse frequency had a significant effect on the hole entrance diameter and hole circularity in drilling stainless steel unlike the drilling of mild steel where the pulse frequency had no significant effect on the hole characteristics. 相似文献