FRACTURE LIMIT LOAD OF CONE SHAPE PART IN DRAWING PROCESS

The deformation characters and load status of the blank＇s potential fracture zone are analyzed at the moment when blank is approaching to punch comer in drawing process of cone shape part. Based on tension instability theory, the formula for calculating fracture limit load of cone shape part in drawing process is derived. Also, the formula is analyzed and verified by experiment.

Characteristics of a Short-Term and Imminent Earthquake Precursor Field in the Northern Part of North China and Numerical Simulation of Source Process

According to studies of more than 20 earthquakes with MS≥5.0 in North China, seven features of the short-term and imminent earthquake precursors have been summarized in this paper. At the same time, taking the short-term and imminent earthquake stage as the physical process of a source’s medium softening and fault creep, we calculated temporal variation of mean stress, maximum shear stress, body strain, and pore pressure in some certain points (supposed stations) in the source area and its adjacent area by using an anisotropic and nonlinear source model and a finite element method. According to an analysis of these theoretical curves, we conclude that the short-term and imminent earthquake precursors have such characteristics as complex shapes, exponential growth of the precursor number with tune, and precursors’ migration from the outside area to the source area, which to a certain extent reveal the cause of the characteristics of the short-term and imminent earthquake precursor field.

基于PartMaker的车铣复合加工技术

车铣复合加工在现代数控加工技术中,发挥着日益重要的作用。针对典型结构件,研究了基于PartMaker的车铣复合加工技术。以典型的轴类零件为例,首先,选择加工机床,进行工艺设计;然后,利用PartMaker软件,编制数控程序并进行后置处理,生成机床加工程序,利用VERICUT软件构建了加工仿真模型,并对机床程序进行了仿真加工;最后,通过实际加工得到了合格的零件,验证了加工方法的可行性。

Joint optimization of maintenance inspection and spare provisioning for aircraft deteriorating parts

With the wide application of condition based maintenance(CBM) in aircraft maintenance practice, the joint optimization of maintenance and inventory management, which can take full advantage of CBM and reduce the aircraft operational cost, is receiving increasing attention. In order to optimize the inspection interval, maintenance decision and spare provisioning together for aircraft deteriorating parts, firstly, a joint inventory management strategy is presented, then, a joint optimization of maintenance inspection and spare provisioning for aircraft parts subject to the Wiener degradation process is proposed based on the strategy.Secondly, a combination of the genetic algorithm(GA) and the Monte Carol method is developed to minimize the total cost rate.Finally, a case study is conducted and the proposed joint optimization model is compared with the existing optimization model and the airline real case. The results demonstrate that the proposed model is more beneficial and effective. In addition, the sensitivity analysis of the proposed model shows that the lead time has higher influence on the optimal results than the urgent order cost and the corrective maintenance cost, which is consistent with the actual situation of aircraft maintenance practices and inventory management.

Assessing Strategy of Power Transformers Insulation State Based on Part-division and Entropy Method

Failure mechanisms of power transformers are complex and uncertain; it is difficult to determine index weights of insulation state. Therefore, it is a challenge to acquire an accurate assessment of insulation state of power transformers. In this paper, an assessing strategy for transformer insulation is proposed base on part-division of transformer and a comprehensive weight determination method. An index system of transformer is established on the basis of part-division of transformer. Each index’s weight is consisted of two parts, the constant weight and the variable weight, which are determined by improved analytic hierarchy process (AHP) and entropy method respectively. Af- ter categorizing insulation state into four levels and standardizing assessing indexes, a Cauchy membership function is forged, and a fuzzy algorithm is employed to simulate the uncertainty of the insulation state. Finally, a confidence criterion is employed to perform part-division based condition assessment of transformer. Case studies reveal that the proposed assessing strategy method is effective, convenient, and practical; with the new strategy, potential failures of transformers can be forecasted and insulation state of transformer parts can also be as- sessed. Furthermore, the assessing results can be used to guide condition-based maintenance.

Program Design of Graphic Realism Displaying System Based on DXF Lathe Turning Rotational Parts

For virtually realizing the graphic realism display of DXF machine parts, in AutoCAD2007 graphic drawing environment, an interactive experimental method was taken to realize the display of graphic in DXF, which was taken as the data-exchanged interface and source. Based on depth analysis of DXF data structure, take one drawing of DXF lathe turning rotational part asthe test piece. By VC＋＋6.0 programming, part＇s geometry information could be obtained. Through data processing, 3D data of the test piece could be generated, which is based on 2D data of DXF test piece. Then, OpenGL graphic processing technologies （light, material, texture, map, et al.） were applied on the 3D display of test piece from DXF files or program modules. Finally based on the test report, results of the system functions were shared to prove the realization of system design, and the feasibility of algorithms used. In the developed software, Machine Designers could get a full view of machine parts, and do some proper modifications. The study content and results of our work have some theory and practical significance on the application of program design in the practical projects.

基于机器视觉的飞机故障检查系统

针对当前飞机维修检查工作以人工目视检查为主、效率低且存在人为因素影响的情况,设计一套基于图像识别与机器深度学习的飞机部件表面无损检测系统。收集并整理了某航空公司一线飞机维修员拍摄的飞机机身及发动机部件图片,对图片集进行预处理,包括通道提取、Sobel滤波处理及二值化;最后用Blob分析对处理后的图像进行特征提取与系统分析。系统运行速度快、准确率高且可连续自动识别图像。利用机器视觉技术对飞机部件表面进行无损检测不仅可以提高生产效率,同时可以去除人为因素对航空器飞行安全的影响,使得飞机的飞行安全得到进一步提升。实践证明,该系统性能稳定可靠,具有极高的推广应用价值。

采用差分进化算法的复杂轴零件工艺路线优化

针对某复杂轴工艺路线编制不合理导致加工效率低的问题,从现有工艺路线优化方案出发,将加工特征以加工精度为加工元节点进行详细划分,构架合理加工元编码,以生产实际中装夹为依据,对工艺约束关系分组分析,获得更优的约束矩阵表达。利用差分进化算法,以机床、刀具及装夹更换最少为目标函数,合理设计差分变异、交叉及序列有效性校验与调整算法。通过对比表明,优化方案相较于优化前方案以及工艺约束不分组方案,刀具、装夹更换次数均有减少。

叶轮零件增减材复合加工工艺规划及虚拟仿真加工研究

针对叶轮零件结构复杂、加工难度大等问题,对其结构及工艺特点进行分析,制定增减材复合加工工艺规划,并基于NX软件设计增材和减材加工的刀具轨迹,最后通过在VERICUT中构建的虚拟仿真系统对加工过程进行仿真,验证增减材复合加工工艺及NC程序的正确性。虚拟仿真加工结果表明,该方法可为复杂零件高效、高质量加工提供一种新的思路和参考。

基于人工鱼群-遗传算法的多品种小批量零件数控加工工艺优化研究

基于多品种小批量零件加工成本高的问题,基于人工鱼群-遗传算法(AFSA-GA)构建了数控机床能耗模型,以实现零件加工能耗下降。首先,将数控机床功率划分为各工序功率模型,基于功率模型与工作时间关系得出机床运转能耗模型,结合产品表面粗糙度模型,对各工序能耗模型及整体粗糙度进行归一化处理,形成整体能耗模型;其次,以能耗及粗糙度为目标函数,建立AFSA-GA算法,通过对各工序能耗求解得出最适当的机床功率及其所对应的能耗和表面粗糙度;最后,针对所获得的最优功率,进行优化结果的验证,为五轴机床的实际加工提供解决方案。

车用铸铁零配件切削液的开发、应用及维护研究

文章针对铸铁内燃机等汽车零配件单机加工和集中供液加工的不同需求,采用石蜡基或环烷基基础油与乳化剂、防锈剂、油性剂等不同功能添加剂进行复配,通过一系列试验优化,研发了具有优异防锈性的铸铁单机用切削液及兼具防锈性和润滑性的集中供液切削液。开发产品不含亚硝酸钠、壬基酚等物质,符合GB/T 32812环保要求,并获得较广泛工业应用。同时文章根据应用情况,提出了切削液维护指标建议及异常排查处理建议。

盖板件高效铣削表面粗糙度预测与工艺参数优化

为了保证7075铝合金盖板件铣削表面质量和提高铣削加工效率,进行工艺参数优化,通过响应曲面法(RSM)构建铣削加工表面粗糙度预测模型,分析铣削工艺参数对表面粗糙度的影响规律。基于表面粗糙度预测模型建立高效铣削工艺参数优化目标方程,采用改进的粒子群算法(PSO)对目标方程进行优化,运用优化后的工艺参数对某盖板件进行铣削加工。试验结果表明:采用优化后的工艺参数进行盖板件铣削加工可以满足表面粗糙度要求,验证了预测模型的准确性和改进PSO方法的可行性。

一种加工薄壁壳体零件的复合浮动式工装设计

为解决某大型薄壁壳体零件在加工中存在的变形、震颤等问题,通过对零件结构和工艺进行分析,从零件加工工艺安排和装夹方案等方面采取了措施,并根据加工过程中存在问题对工装夹具进行优化,设计了一款电动轻型复合浮动式工装。工装采用分体式空心结构、轻型材料和自动化控制方式,解决了零件的加工变形和震颤问题,保证了零件的加工质量。设计的工装对产品的不同加工状态、不同壁厚具有较强的自适应性,也对相同结构不同材料的产品具有较强的自适应性,进一步扩大了工装的应用范围,降低了产品的生产成本,提高了零件的生产效率,为类似产品的加工提供了思路与方法,具有一定的推广应用价值。

基于机器人的自动化检测技术在航空制造中的应用进展

随着航空工业的发展,各类航空器的性能日益提升,对质量检测的要求也不断提高。相较于传统人工方法,基于机器人的自动化检测技术具有更高的操作精度和效率,在航空制造与检修过程中已经得到广泛应用。本文重点关注了近10年基于机器人的自动化检测技术在零件加工、成品质量检测及飞机整机维护检修等各个环节中的应用情况。对比了六轴工业机器人、移动机器人和无人机等不同种类机器人与超声、光学和其他类型检测技术的应用效果。最终总结得出,基于机器人的自动化检测技术的研究对提高航空制造与检修过程中的质量控制具有重要的实际意义,但仍面临小型化、智能化、实用化的挑战。

钛合金薄壁件铣削加工的颤振监测方法研究

钛合金薄壁件在铣削加工过程中的动态特性相对复杂,易出现颤振现象,严重影响铣削加工的质量和效率。为满足钛合金薄壁件的高效、高精度铣削加工,提出一种考虑加工动态特性的颤振识别方法,利用粒子群算法(ParticleSwarmOptimization,PSO)来优化变分模态分解(VariationalModeDecomposition,VMD)参数,实现对颤振现象的有效监测。最后利用仿真实验,证实所提出的检测方法具有科学性和有效性。

基于误差最小化的铸造不锈钢零件高速切削工艺方法研究

铸造不锈钢零件在切削过程中容易产生变形和振动,导致表面粗糙、切削尺寸偏差大。为了解决这一问题,提出基于误差最小化的铸造不锈钢零件高速切削工艺方法研究。在数控机床的支持下,采用在线测量的方式测量铸造不锈钢零件数据,将数控机床测量的坐标值转换为零件表面实测点,获取合适的测量点完成对加工路径的规划,在此基础上通过粗加工和精加工结合的形式对铸造不锈钢零件进行高速切削处理,并以误差最小为目的对加工误差进行补偿处理。实验结果表明:提出的基于误差最小化的高速切削工艺方法加工误差小、精度高,零件表面质量高,该工艺方法的实用性得到了增强。

差厚板U形件工艺孔成形性能仿真

以冷冲压差厚板U形件作为研究对象,通过有限元仿真分析了工艺孔的位置、数量、尺寸以及形状对成形性能的影响.结果表明,差厚板在薄区侧壁处开孔时有利于减少侧壁的残余应力;差厚板的回弹与工艺孔在板件中的位置分布关系不大,与工艺孔的数量、半径及形状有关.从成形性能和回弹影响角度考虑,工艺孔优先选差厚板U形件端部的厚区与过渡区区域,如果必须在侧壁开孔,优选侧壁薄区区域.在相邻区域,工艺孔的数量尽量不超过2个,工艺孔尺寸小一些更合适,工艺孔形状沿轧制方向距离越小越合适.

航天复杂薄壁零件加工工艺知识图谱构建及其应用

针对航天复杂薄壁零件加工工艺数据结构化程度低、难以重用等问题,将知识图谱引入工艺设计领域,提出了一种典型的复杂薄壁零件加工工艺知识图谱构建方法。首先,自顶向下定义工艺知识层次结构,利用本体建模构建了模式层;其次,利用知识抽取、知识融合及本体关系建立的方法自底向上构建了数据层,通过Neo4j图数据库完成了模式层与数据层的映射,并实现了工艺知识的可视化表征和快速检索;然后,在构建完成的工艺知识图谱基础上,结合零件属性和特征拓扑关系的相似度实现了工艺路线推荐;最后,搭建了复杂薄壁零件加工工艺知识图谱可视化系统,并以框段类零件为例展示了工艺知识检索与工艺路线推荐功能。研究结果表明:对基于知识图谱和相似度计算的工艺路线推荐模型进行了500次测试,有94.7%的推荐列表中存在与目标零件相符的工艺路线。这证明了该工艺知识图谱的构建方法是可行的,并且其对工艺设计工作起到辅助决策作用,可以有效提高工艺查询和设计的效率。

浅谈由零件到铸件的关键设计过程

中国大学生机械工程创新创意大赛——铸造工艺设计赛在培养学生专业素养、合作精神以及提高学生综合能力等多方面有着积极的促进作用。本文作者结合参加多届铸造工艺设计赛并获奖的经验体会,借助铸钢提升箱体和球墨铸铁小型箱体两个具体案例阐述铸造工艺设计赛中基于最小铸出孔和槽、机械加工余量和起模斜度等基本设计原则将零件变为铸件的关键设计过程,以期促进提高学生在铸造工艺设计赛中的参赛水平。