微细孔超声振动钻削加工方法研究

为解决采用0.5mm直柄麻花钻钻削加工高压共轨喷油器控制阀微细孔时由于微细钻头刚性差,在钻削过程中易出现偏摆和断裂现象,导致控制阀微细孔加工精度难以保证和控制的问题,应用有限元分析的方法以及超声振动原理,开展超声振动钻削过程中钻削刃运动轨迹分析及轴向振动钻削过程的分析研究。通过0.5mm微细孔超声振动辅助钻削的仿真实验研究分析与验证,选取确定适合超声振动切削参数的超声振动钻削工艺方法,可以满足高压共轨喷油器控制阀微细孔尺寸加工精度高的要求。     

精镗时提高箱体孔同轴度精度的途径

文章分析了镗削单同轴孔时镗削工艺对尺寸精度的影响、用悬臂刀具镗削孔系时孔系间的位置关系和尺寸关系对孔系加工精度的影响,并取孔同轴度误差最小为目标,对多刀镗削加工时镗杆上两刀间距离lp进行优化.指出可通过确定适当的加工工艺、孔系结构设计和优化镗杆尺寸等途径提高精镗时箱体孔同轴度.     

以铣代镗工艺研究

提出采用展成圆代替插补圆的原理设计了特殊的主轴结构,实现孔的以铣代镗加工工艺,并进行了实验验证。采用正交方法进行切削实验设计,分析不同工艺参数对孔特征精度(尺寸精度、圆度、孔壁粗糙度)的影响,验证以铣代镗加工孔的可行性,并研究得出影响孔特征精度的主要工艺参数。结果发现,在铣代镗孔加工过程中,影响孔特征精度(尺寸精度、圆度)最大的因素为轴向进给速度,其次主轴转速;而影响孔特征精度(孔壁粗糙度)最大的因素为主轴转速。最后,选取某汽车变速箱壳体类零件加工为案例进行实际验证,分别对比以铣代镗加工与镗削加工,相比较采用镗削方式加工,以铣代镗加工能够节省加工刀具成本,提高加工效率。实验结果对于先进孔加工工艺研究具有重要的参考价值。     

微细深孔超声轴向振动钻削装置的设计

超声振动钻削属于脉冲式的断续切削。在深孔加工方面具有普通孔加工技术无法比拟的工艺效果。文章介绍了作者基于高频振动切削原理设计的一台超声轴向振动钻削装置的结构。并将该装置用于立式加工中心上对铝、铜等材料进行了切削加工实验。实验结果表明，超声振动加工可提高微细深孔的加工精度和表面质量。这种方法特别适合于软质材料的微细深孔的精密和超精密加工。     

飞机交点孔超声椭圆振动精密加工技术

针对常规方法加工30mm以上的飞机翼身交点孔存在动力不足、孔径精度差和表面质量不高等问题,采用超声椭圆振动镗削的方法,研制了超声椭圆振动镗削装置,并对30mm以上不同材料的翼身交点孔进行了镗削加工,取得了很好的工艺效果,充分体现了超声椭圆振动镗削技术在飞机交点孔加工中的优势。     

高速镗削扩径头模块定位销孔的工艺实现

从零件加工的工艺要点进行分析,论述在具备高速切削能力的立式加工中心上,用具有高硬度、高热硬性和化学稳定性的PCBN刀具,采用高速镗削的工艺方法加工定位销孔。该方法满足零件高的尺寸精度、形状精度和表面质量的要求,提高了生产效率。     

振动钻削微小孔提高加工精度的研究

本文对轴向超声波振动和轴向电磁振动钻削微小孔时的加工精度进行了研究。结果表明,轴向振动钻削可明显提高微小孔加工的入钻定位精度、孔径尺寸精度和孔的圆度。     

飞机起落架300M钢轮轴加工工艺研究

通过对300M超高强度钢起落架轮轴深孔零件的性能分析,确定了合理的加工工艺.探讨了刀具振动对镗孔加工的影响,设计了镗杆的结构尺寸,并对镗杆的夹紧装置进行了改装.分析了走刀路径、切削参数对零件表面质量和刀具寿命的影响,通过试验验证,给出了最合理的切削实施方案,为300M钢的深孔镗削提供了理论依据.     

U钻在数控加工中的应用技巧

1．引言 作为现代最前沿的高性能切削工具，U钻具有其他钻削工具无可替代的优势，一方面，它使数控机床加工中高效实现插钻、镗削、螺旋插补和交叉孔镗削成为可能，并通过使用U钻获得良好的表面质量和高精度，使数控机床上钻孔不再成为阻碍生产效率提高的“瓶颈”问题。另一方面，使用转速高、刚性好、冷却系统强的数控机床为有效载体，则更好地发挥了U钻的高效性能，使U钻成为高效生产的倍增器，因此，U钻在数控加工中得到了广泛推广和应用。     

振动钻削技术的新发展——电热振动复合钻削

介绍了振动钻削技术的加工原理,综述了振动钻削加工微小孔的国内外研究现状,分析了振动钻削技术的应用前景及存在的问题。为了解决微小孔钻削时刀具磨损严重、加工精度低、表面质量差的问题,提出了一种电热振动复合钻削技术方案,从而提高了微小孔的加工质量和加工效率。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...