激光热辅助磨削石英玻璃的实验研究

采用正交实验研究了工艺参数对石英玻璃激光热辅助磨削后的表面粗糙度、表面形貌和砂轮磨损情况的影响.结果表明:激光热辅助磨削可以提高临界磨削深度、石英玻璃的表面磨削质量及效率.激光功率对激光热辅助磨削表面粗糙度影响最大,但不呈线性关系,最优激光功率为175 W,对应粗糙度为0.262.通过激光辅助,实验过程中玻璃脆性下降,塑性提高,实现了石英玻璃的塑性域磨削,减轻砂轮磨损,降低了磨削表面的剥落坑.

激光热辅助磨削超硬合金表面质量研究

为改善超硬合金磨削加工的表面质量,引入激光进行热辅助磨削加工。以YG6X型超硬合金为研究对象,在正交实验的基础上,借助极差分析法,分别研究了激光功率、进给速率、砂轮转速、磨削深度对加工表面质量的影响规律。研究结果表明:激光热辅助磨削可以提高超硬合金的表面质量;表面粗糙度随着激光功率的增大而减小,随工件进给速度的增大而增大,随砂轮转速的增大而先减小后增大,随磨削深度的增大而先减小后增大。所确定的最佳工艺参数为:激光功率150 W、工件进给速度1 mm/s、砂轮转速140 r/s、磨削深度30μm。加工后超硬合金的表面粗糙度达到了0.562μm。

陶瓷材料激光加热辅助切削温度场分析

对激光加热辅助切削时的温度场进行了分析研究 .在建立激光加热及切削温度场数学模型的基础上 ,利用有限元数值分析的方法 ,对激光加热辅助切削时的温度场进行了分析计算 .计算的结果表明 ,激光加热辅助切削时 ,由于激光加热温度场和刀具切削温度场的叠加作用 ,使切削区的温度很高 ,其高低的程度和激光加热点到刀具的距离以及切削速度有关 。

热辅助纳秒脉冲激光抛光试验研究

为提升纳秒脉冲激光抛光加工的质量及效率,对基于热辅助的纳秒脉冲激光抛光开展了试验研究。定性分析了工件热辅助对激光抛光的热影响;以通过增材制造的Ti-6Al-4V原始表面为试验对象,利用共焦显微镜、扫描电子显微镜和能谱仪,对在不同激光能量密度及补偿温度下抛光后的表面及横截面进行了分析,揭示了工件补偿温度、激光能量及表面加工质量间的关系;进一步利用维氏硬度计测量了其维氏硬度,分析了重结晶层及熔融层对表面硬度的影响规律。研究结果表明:在较高的补偿温度下,热辅助激光抛光获得与无热辅助条件下相似的表面粗糙度只需较低的能量密度;这也表明了在相同的激光输出功率下,热辅助激光抛光补偿温度越高,加工速度越高,其抛光效率也会得到有效提升。

面向铝合金的热辅助激光黑化试验研究

为改善传统表面黑化加工存在的污染严重、成本高等缺点,以6061铝合金表面为试验对象,对基于热辅助的激光黑化加工开展试验研究。首先,利用反射光谱仪测量黑化表面的反射光谱,并结合扫描电子显微镜及轮廓仪对试件在不同温度、扫描速度下照射区的表面形貌演变进行了深入分析,揭示了补偿温度、激光能量、扫描速度及表面形貌间的关系。进一步,利用三维测量激光扫描共聚焦显微镜及电子色散X射线分析,对热辅助激光黑化烧蚀区域氧化情况进行了分析。结果表明:对于热辅助激光黑化,在较高的补偿温度下,激光能量的利用率及黑化效率显著提高,便于大规模生产应用。

能量场辅助激光诱导等离子体加工透明硬脆材料的研究现状及发展趋势

能量场辅助激光诱导等离子体加工技术是一种新兴的制造技术。基于传统的激光加工技术,通过引入热场、电场、磁场、化学场等能场进行创新,提高激光加工过程的可控性,不仅实现了透明硬脆材料纳米级甚至亚纳米级高精度制造,也有利于满足超精密制造的高质量、低损伤要求。从热场、磁场、电场、化学场分别具体阐述了不同的能量场辅助对激光加工技术的影响,通过分析激光机理和能量场辅助机理总结热场、电场、磁场和化学场对激光加工中的热能、光能、动能和表面能的影响原理,并介绍了能量场辅助激光加工的设备及工艺方法,最后总结能量场辅助激光加工技术目前存在的不足及未来面临的挑战,为进一步发展多能场复合辅助激光诱导等离子体加工技术奠定基础。

Estimation of deformed laser heat sources and thermal analysis on laser assisted turning of square member

Laser assisted machining （LAM） has difficulties in estimating temperature after applying a LAM process due to its very small heat input area, large energy and movement. In particular, in the case of laser assisted turning （LAT） process, it is more difficult to estimate the temperature after preheating because it has a shape of ellipse when a laser heat source is rotated. A prediction method and thermal analysis method for heat source shapes were proposed as a square shaped member was preheated. The temperature distribution was calculated according to the rotation of the member. Compared with the results of the former study, the maximum temperature of the calculation results, 1 407.1 ℃, is 8.5 ℃ higher than that of the square member, which is 1 398.6 ℃. In a LAT process for a square member, the maximum temperature is 1 850.8 ℃. It is recognized that a laser power control process is required because square members show a maximum temperature that exceeds a melting temperature at around a vertex of the member according to the rotation.

Prediction of preheating conditions for inclined laser assisted machining

For laser assisted machining,shape of preheating laser heat source is changed irregularly because of complexity of material shape.So,the preheating temperature should be controlled by adjusting the feed rate or the laser power.Thermal analyses of the laser assisted machining process for inclination planes were performed.By analyzing the obtained temperature profile,a proper feed rate control method was proposed according to the inclination angles.In addition,the temperature distribution of the cross section after feed rate control was predicted.The correlation equation between inclination angles and adjusted proper feed rate was proposed.The results of this analysis can be used to predict the preheating effect on workpiece and can be applied as a preheating temperature control method in laser assisted machining processes.

Numerical study of thermal history in laser aided direct metal deposition process

Temperature evolution in the laser aided direct metal deposition (LADMD) process has considerable influence on the micro-structure and properties of the final part. A 3D transient finite element model was developed to study the temperature evolution during the multilayer LADMD process. To make the property analysis from thermal history easier, a critical temperature specific to thermal history was defined and the distribution of it in the part was also discussed. The simulation results indicated that the critical temperature can make the property analysis from thermal history easier. Thermal history of all the deposited materials was similar. It was also concluded that process parameters needed to be time-varying according to the real-time temperature field during the process.