扫描路径规划对激光弯曲成形影响的实验研究

在三维激光成形中,扫描步距、扫描的先后次序、扫描线距自由端的距离等扫描路径规划参数对最终变形量都有影响。实验表明：当扫描线距自由端的距离L′增加时,弯曲角度随之增大,但当L′继续增加时,板料的弯曲角度却减小,最后逐渐趋于平缓。当扫描步距太小,板料的总体弯曲效果并不好,而且由于重叠加热,使板料硬度降低。随着扫描步距的继续增大,板料的最终弯曲效果只是每次扫描的弯曲变形量的简单迭加。而且实验发现,先采用大的步距对板料进行扫描,然后在两条扫描线之间再插入扫描线,此时的弯曲效果比顺次加热的弯曲效果要好。     

数控激光切割机光路补偿措施的探讨

基于对高斯光束空间传输和聚焦特性的理论分析,说明了激光切割机光路长度变化对焦点大小和焦点深度的影响,并对光束准直、可变曲率半径镜片、等光程三种光路补偿方法进行分析比较,提出了通过伺服电机驱动的等光程设计方案。     

UG在模具电极NC程序编制中的应用

以LNUP2 2 0 6 -Z模具槽型电极加工为例 ,介绍了UG中编制NC程序的过程和方法。根据LNUP2 2 0 6 -Z模具槽型的特点 ,通过对比分析 ,提出了构建其槽型电极模型和编制其NC程序的合理方法 ,并经过F35机床加工得到了验证。     

方截面轻体件的内高压成形研究

管坯内压液力成形工艺由于能够节省材料、降低成本、提高零件机械性,因此近年来在汽车、航空航天等领域中得到了广泛应用。本文针对目前该工艺存在的轴向量与内压之间的匹配关系问题,通过有限元模拟手段分析了由圆柱管坯成形空心方截面零件过程中加载路径对工艺的影响,为该工艺面向生产提供了一定的参考依据。     

Texture evolution of high purity tantalum under different rolling paths

Deformation behavior and texture evolution of the material can be significantly affected by strain path change. For this reason, two rolling methods, unidirectional rolling (UR) and clock rolling (CR), were employed to manufacture tantalum plates. Texture evolution during unidirectional rolling and clock rolling was studied respectively by orientation distribution function (ODF). Related annealed microstructures were investigated by orientation image map (OIM). Usually, unidirectional rolling led to a strengthening of the main texture component with increasing strain, but for tantalum dominant texture component {0 0 1} θ-fiber was stable after 70% deformation, while minor texture component {1 1 1} γ-fiber was enhanced with increasing strain. In clock rolling, both of the two fibers were not stable any more for their intensity varied with rolling pass. After the final deformation, a similar texture was produced by the two rolling methods. However, recrystallization texture revealed a big difference. Such different texture development was contributed to microstructural change resulted from rolling path change.     

凝固路径对Al-4.5%Cu合金显微偏析参数影响的数值模拟

通过对Al-4.5%Cu合金铸锭显微偏析形成的数值模拟,研究了凝固路径对凝固后铸锭不同位置处显微偏析参数的影响.在显微偏析模型中考虑了树枝晶粗化、固相溶质逆扩散、枝晶尖端过冷、随温度变化的溶质扩散系数等影响显微偏析形成的动力学因素.数值方法中采用变网格技术跟踪移动界面,通过迭代求解溶质扩散方程和溶质守恒方程计算显微偏析参数.结果表明,对于Al-Cu合金,固相扩散主要由溶质扩散速率控制,而非局部凝固时间.显微偏析参数不仅取决于局部凝固时间,还要考虑凝固路径的影响.     

Smooth trajectory generation for five-axis machine tools

This paper presents a smooth spline interpolation technique for five-axis machining of sculptured surfaces. The tool tip and orientation locations generated by the CAM system are first fitted to quintic splines independently to achieve geometric jerk continuity while decoupling the relative changes in position and orientation of the cutter along the curved path. The non-linear relationship between spline parameters and displacements along the path is approximated with ninth order and seventh order feed correction splines for position and orientation, respectively. The high order feed correction splines allow minimum deviation from the reference axis commands while preserving continuous jerk on three translational and two rotary drives. The proposed method has been experimentally demonstrated to show improvements in reducing the excitation of inertial vibrations while improving tracking accuracy in five-axis machining of curved paths found in dies, molds and aerospace parts.     

一种新型管材液压胀形装置的设计

开发了一种简单实用、可在单动压力机上使用的管材液压胀形装置,用于薄壁金属管材的自由胀形、轴压胀形和异形截面中空件的液压胀形.该装置不需要复杂的外部供液系统,通过增压活塞挤压缸体中液体的方式来为管材成形提供液压力和轴向力,通过设计增压缸体和控制增压活塞的行程等来实现两个载荷的合理匹配.试验表明,该装置结构简单、操作方便、工作可靠;合理的载荷匹配能显著地提高管材液压胀形的成形性能.     

The effect of through-thickness strain distribution on the static recrystallization of hot rolled austenitic stainless steel strip

The accumulation of strain and the evolution of the microstructures at the surface and centre of thin hot rolled 304 austenitic stainless steel strips were studied by comparing their recrystallisation behaviour and recrystallised grain sizes. It appears that the evolution of microstructure can be predicated using a simple approach and that the accumulated strain depends only on the amount of strain, and not on the strain path (ie. the effect of strain reversal in the roll gap.) This was confirmed by the observation that the time for 50% recrystallisation and the recrystallised grain size were found to be approximately a log linear function of strain when the strain in the centre of the hot rolled strips was calculated from the rolling reduction and the strain in the surface region was estimated from the predicted ratio of surface strain to axial strain obtained from FE modelling using the commercial package ABAQUS.     

管件液压成形中加载路径的优化设计方法研究

确定合理的加载路径是管件液压成形工艺设计的关键。文章较为系统地介绍了管件液压成形中加载路径的优化设计方法,比较分析了各种方法的优缺点与适用对象,讨论了研究过程中存在的主要问题和研究的发展方向。     

Efficient Tool Paths and Part Orientation for Face Milling

High speed machining is pushing the limits of feeds and speeds. A different approach for high throughput is described here. The focus is on the maximum feed that can be obtained for a segment; the feed rate losses due to sharp changes in tool path are minimized. The interdependency of individual axis drive speeds for a tool path segment are analyzed. There exists an optimum work angle relative to the axes that reduces losses and increases allowable feeds for particular segments, saving valuable cycle time and balancing feed drive loads. Face milling and roughing steps of end milling are the most attractive application areas.     

基于测量数据直接生成NC加工轨迹的方法研究

直接基于测量数据的数控加工技术，可以满足日益增长的产品高质量、高生产率的要求．顺应快速制造的发展趋势，具有重要的实用价值，本文对基于测量数据的NC刀位轨迹生成技术的研究状况进行了概括和总结．指出了传统的通过曲面重构方法生成刀位轨迹存在的弊端，阐述了由STL数据模型生成刀位轨迹以及直接由云数据生成刀位轨迹的关键技术，并指出了其今后的发展方向及研究重点。     

圆柱形坯料与凹形坯料镦粗过程中典型点的加载轨迹及应力分布的对比

利用有限元法对圆柱形坯料及凹形坯料镦粗过程的数值模拟结果，给出了工件变形区中典型点在屈服表面上的加载轨迹，通过对加载轨迹的研究，揭示了凹形坯料缴粗不易出现纵向裂纹的原因。     

基于改进CC路径截面线法的机器人铣削加工刀具轨迹生成方法

机器人铣削加工技术是当前机器人技术发展的重要方向之一,而刀具轨迹的自动生成是实现机器人铣削加工的一个关键环节。以Open Cascade为几何造型技术开发平台,以改进的CC路径截面线法为轨迹生成方法,通过对约束面间距进行动态调整,改进了传统CC路径截面线法刀轨疏密不一致的问题,从而能够提高机器人铣削加工精度。在此基础上,开发出相应的CAD/CAM软件系统,实现了自由曲面精粗加工刀具轨迹的自动生成。最后,通过仿真和实验对生成的刀具轨迹进行了验证,验证了方法的可行性和准确性。     

基于动态规划算法的孔群加工路线优化

孔群加工路线优化,对于提高多孔类零件的加工效率和质量具有重要意义。通过数控机床上孔群加工工艺路线的分析,利用动态规划算法,对数控机床孔群加工路线进行了优化计算。最后通过实例验证此优化方法在孔群加工中明显提高了数控加工的效率、降低了加工成本。     

Solidification path calculations of Al-Zn-Mg alloys in Al-rich corner

The solidification paths of Al-Zn-Mg alloys in the Al-rich corner were investigated. The thermodynamic data for the calculation are obtained by direct coupling with the CALPHAD software Thermo-Calc via its TQ6-interface and the COST2 database. The influences of the initial compositions and the extent of solid back diffusion on the solidification path were numerically investigated by sample calculation of the ternary Al-Zn-Mg alloys. The calculation results of solidification paths of the selected alloys: Al-Zn-3 Mg(in wt.%), Al-5 Zn-10 Mg, Al-2.5Zn-15Mg, Al-10Zn-20.5 Mg, Al-8Zn-25 Mg, were: L→(L+α-Al), L→(L+α-Al)→(L+α-Al+TAU), L→(L+α-Al)→(L+α-Al+Al Mg_β), L→(L+α-Al)→(L+α-Al+TAU)→(L+α-Al+TAU+Al Mg_β), L→(L+α-Al)→(L+α-Al+Al Mg_β)→(L+α-Al+TAU+Al Mg_β), respectively. The results show that the initial compositions and the extent of solid back diffusion have a great influence on solidification path, and the amounts of eutectic phase increase with the decrease of the solid back diffusion coefficient. The equilibrium solute partition coefficients for Zn and Mg in alloys are also calculated and their influence on micro-segregation in the primary solidification of Al-5Zn-10 Mg alloy is analyzed.     

INTERFACIAL REACTIONS OF THE EXPLOSIVELY WELDED TITANIUM-STEEL COMPOSITE DURING HEAT TREATMENT

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基于特征技术的检测模型及其轨迹规划算法

介绍了基于特征技术的检测信息模型,建立了基于特征测面的零件检测数据模型.同时,对测头的检测运动轨迹进行了规划,实现了自动检测功能.     

基于CAXA制造工程师特征造型与MasterCAM 9模具加工应用实例

应用CAXA制造工程师完成模具的特征造型,转换格式后调入MasterCAM软件中生成加工轨迹和G代码,快速高效地制造出模具产品。     

用辅助曲面优化曲面刀具路径

从曲面特点及加工难点出发,分析了如何使用MasterCAM软件编制合理的刀具路径,使加工质量大为改善。