实心/空心高速滚珠丝杠轴承副热变形研究

随着机床滚珠丝杠进给系统速度的提高,滚珠丝杠轴承副摩擦产生的热量传递到丝杠,并引起了滚珠丝杠的热变形。通过分析轴承发热原理及理论计算方法,以及实例计算轴承副生热,运用有限元分析软件ANSYS仿真,得到实心滚珠丝杠和空心滚珠丝杠的温度分布和热变形,并分析热变形对滚珠丝杠变形的影响,得出通有冷却液的空心滚珠丝杠可以有效的抑制滚珠丝杠温升并减小热变形的理论,为空心滚珠丝杠热特性研究提出理论依据。     

滚珠丝杠用高刚度固定支承牵拉机构的创新设计

在高精度大型、重型数控机床上,用推力轴承+向心轴承+推力轴承组合,固定支承牵拉滚珠丝杠,给滚珠丝杠施加拉应力,补偿丝杠热变形,维持滚珠丝杠导程不变,从而保证机床精度稳定性。     

数控加工中心丝杠专用轴承单元

通过分析现有丝杠支撑轴承结构及其组配、安装方式,提出了数控加工中心丝杠专用轴承单元化设计理念,介绍了轴承单元结构设计、主参数优化设计和预载间隙设置等方法。     

进给系统参数对丝杠振动频率的影响

考虑轴承的支承刚度,建立了丝杠在两端弹性支承条件下纵向振动、扭转振动和横向振动的频率方程。对于纵向振动和扭转振动,分析了轴承支承刚度对其振动频率的影响。对于丝杠的横向振动,采用Timoshenko模型,综合考虑了转动惯量、涡动效应和预拉伸力对丝杠振动的影响,分析了轴承支承刚度、旋转速度和预拉伸力对丝杠横向振动频率的影响,分析了丝杠在启动过程中的共振,为回转系统减少或消除共振提供了理论依据。     

高速实心/空心滚珠丝杠热变形受轴承副摩擦热影响分析

机床高速高精度的发展方向,迫切需要提高机床滚珠丝杠的进给速度,然而随着滚珠丝杠进给速度的提高,轴承副摩擦热也在急剧增加,增大了滚珠丝杠的热变形,进而降低了滚珠丝杠的定位精度,为了解决这一问题,文中提出采用通入冷却油的空心滚珠丝杠抑制温升。先对轴承摩擦生热、热边界条件及滚珠丝杠变形进行理论计算,再通过刚度计算得到与给定空心滚珠丝杠等刚度的实心滚珠丝杠外径,运用有限元分析软件分别对空心、实心滚珠丝杠轴承副热特性进行分析,得出通入冷却油的空心滚珠丝杠可以有效地抑制温升和热变形,最后对不同载荷不同转速下实心滚珠丝杠和空心滚珠丝杠的热特性进行分析,为空心滚珠丝杠的设计和研究提供理论依据。     

手扳压力机压头的改进

用手扳压力机对变形的热处理工件校直时,常常发现压力机的丝杠和铜压头固定在一起。加压时丝杠和压头同时转动,工件易出现位置滑动或松动现象。给操作者带来了麻烦和不便。为此,我们将压头部分的结构加以改革(见图);在丝杠顶端镶上了一个204轴承,然后又按照轴承的外径制做了压头轴承套。把铜制压头放在轴承套里,     

滚珠丝杠螺母副的故障诊断与维修

论述了滚珠丝杠在运行中出现定位精度下降,反向间隙过大,机械爬行,轴承磨损严重和噪音过大等故障产生的原因,并通过检测与修理滚珠丝杠螺母副及支撑系统间隙,轴承、丝杠螺母副的润滑不良,伺服电机的驱动问题解决了故障。     

滚珠丝杠支承端的结构改进设计

通过对原有数控机床滚珠丝杠支承端轴承易损坏的现象总结分析,找出造成数控机床定位精度不稳定及滚珠丝杠支撑端个别轴承损坏的主要原因,提出了滚珠丝杠传动支撑端结构改进设计方案和应采取的措施。通过设计改进后实际测试结果验证了改进的效果,将改进的结构成功应用于多种同类型数控机床的滚珠丝杠传动中,提高了滚珠丝杠传动的可靠性,保证了数控机床定位精度的稳定。     

“等高差法”测量轴承孔与端面垂直度

我公司日常生产中经常进行数控机床滚珠丝杠轴承孔与端面垂直度的测量,滚珠丝杠轴承孔与端面所应用的加工方法是：镗床主轴安装固定镗刀镗削孔,刮面刀刮削或应用万能刀架单刀铣削加工孔两端面,保证滚珠丝杠轴承孔与两端面垂直度要求。装配时用专用工装垂直度检具及测量桥板配合复检,复检合格后再进行滚珠丝杠装配。     

大滑板的改进

通过简化和优化滚珠丝杠的传动结构,减少了滚珠丝杠定位轴承的数量,降低了机床的成本,减少了滚珠丝杠的综合误差,提高了上滑板的数控进给精度。     

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...     

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.     

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。     

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。     

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。     

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.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

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...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....