解决铸铝转子初始动平衡量较大问题的工艺改进

对某型三相交流异步电动机铸铝转子初始动平衡量较大的问题进行了分析,从提高铸铝转子浇注质量和填充率方面,提出优化压铸工艺参数、改进铸铝模具排气系统和增加冲片预烘的工艺改进措施,从而提高铸铝转子的产品质量,有效防止类似问题的再次发生。

六缸柴油机曲轴动平衡量分解方法研究

介绍了六缸曲轴动平衡量的分解方法 .对六缸曲轴确定了六个去重平面 ,在完成两面不平衡量测量后 ,依据力学原理将其分解到六个去重平面 .

基于残差修正的挠性转子动平衡量的计算方法

介绍了挠性转子平衡问题的数学模型,分析了目前工程上常用的几种计算挠性转子平衡问题的方法的缺点,提出了基于最小二乘方法的扰动算法、直接修正算法和约束算法.这些算法在一定程度上改善了原来的工程上计算挠性转子平衡问题的方法的缺点.计算实例验证了基于最小二乘方法的扰动算法、直接修正算法和约束算法可以得到更满意的结果.

235/85R16子午线轮胎动平衡量波动的原因分析及解决措施

结合 2 35 / 85R16半钢子午线轮胎生产实际 ,对导致子午线轮胎动平衡量波动的主要原因 ,即胎面材料质量分布不均、型胶配重不均及成型工艺方法欠妥等进行了分析 ,并提出了相应的工艺、设备、操作等方面的调整改进措施 ,这些措施的实施 ,使公司生产的 2 35 / 85R16轮胎动平衡A级品率从 42 %提高到 74%。

曲轴毛坯初始动平衡量的优化

本文针对曲轴线实际生产状况，采用Q—DAS数据分析软件对曲轴毛坯初始动平衡量进行分析，找出曲轴毛坯初始动平衡量需要优化的方向。通过优化曲轴毛坯重量，降低曲轴初始不平衡量，提高动平衡加工效率，降低生产节拍。

基于Q-DAS数据的曲轴动平衡质量控制优化

研究了曲轴动平衡效果的影响因素,结合Q-DAS质量数据,得出了曲轴毛坯初始不平衡量的分布趋势,作为质量前馈的手段,动态调整中心孔位置度,降低了料废率,提高了动平衡机的运行效率,综合提升了去重动平衡工艺的效能。

发动机曲轴动平衡质量分析及解决

内燃式发动机三大件中的曲轴是由活塞带动做圆周运动的高速回转件,旋转过程承受各种复杂多变的交变载荷;曲轴在加工过程中,对其轴颈直径、圆度、平行度、直线度、轴径跳动、轴径锥度、轴向距离、粗糙度、相位角、动平衡量、清洁度等都会标注各自的技术要求,而曲轴在高速旋转运动过程中自身产生的不平衡振动与其转速的平方成正比。高速转动过程中产生的高频率振动会导致轴瓦承受力负载增加及轴瓦上油膜不均匀消耗,曲轴断裂等风险。曲轴平衡精度的高低对发动机的振动、平稳运行及发动机寿命都很重要。如何去除曲轴动平衡量,这些都是我们需要分析和解决的问题。

基于单片机的机床主轴部件动平衡在线测试系统的研究

依据力学平衡理论,分析了主轴部件动平衡测试的原理。利用霍尔传感器采集数据,并用互相关技术提取有用信息,以单片机为核心构建了数据处理的硬件测试系统,并设计了测试系统的程序结构。试验结果表明:该系统的测试精度能够满足一般机械工业的使用要求,基本实现了测量自动化和分析智能化的目的。

平衡块半径变化对曲轴动平衡的影响

曲轴动平衡加工是曲轴制造过程中的难点和要点，因影响曲轴动平衡的因素众多，导致曲轴生产中极易出现最终动平衡量差超的现象。

精密电主轴装配工艺研究

给出了精密电主轴的结构原理图,阐述了其工作原理,并对该电主轴在装配时的一些关键工序进行了说明.阐述了轴承选用、油脂填充量、轴承锁紧、拉刀力、顶刀量和动平衡量,对电主轴在使用过程中出现的故障及如何排除故障进行了介绍,指出了装配电主轴关键工序的装配要点.

电主轴检测及预防性维修技术

电主轴是高速加工机床的关键重要部件,其寿命一般在10000h左右,电主轴检测、保养及预防性维修对于保证其正常运转、延长使用寿命有重要意义,本文对电主轴检测及预防性维修技术进行一些探讨。

增压器同步噪声分析优化

增压器在带来动力性和经济性提升的同时,随着顾客对汽车舒适度要求的提高,增压器的噪声也日益成为行业关注的焦点。废气涡轮增压器的噪声从大的方面可以分为自激励结构噪声和气动噪声。增压器同步噪声是增压器最常见的噪声之一,分为同步振动噪声和同步脉动噪声。专家评价法给出了增压器同步噪声的判定标准,并依据该标准确定合理的增压器转子的动平衡度和脉冲值。

CRH380D型动车组客室地板异常振动故障分析

针对CRH380D型动车组转向架上方客室地板出现的异常振动,对可能导致振动的相关部件进行了逐个排查,最终确认牵引电机的动平衡量超差是造成振动的原因,并通过更换电机及时解决了问题。

Balance Mechanism Design of Single Cylinder Engine Based on Continuous Mass Distribution of Connecting Rod

For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism. In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces to improve the engine’s noise vibration and harshness performance.

Optimal arrangement for pressure measurement points in working chamber of earth pressure balance shield

In order to exactly provide scientific basis for pressure dynamic balance control of working chamber of earth pressure balance shield (EPBS),study on optimal arrangement of pressure measurement points in working chamber was conducted. Based on mathematical description of optimal arrangement for pressure measurement points,fuzzy clustering analysis and discriminant analysis were used to divide pressure regions of nodes on bulkhead. Finally,the selection method of optimal measurement points was proposed,and by selecting d6.28 m EPBS as study object,the case study was conducted. By contrast,based on optimal arrangement scheme of pressure measurement points,through adopting weighted algorithm,the absolute error mean of equivalent pressure of working chamber is the smallest. In addition,pressure curve of optimal arrangement points presents parabola,and it can show the state of pressure distribution on bulkhead truly. It is concluded that the optimal arrangement method of pressure measurement points in working chamber is effective and feasible,and the method can provide basis for realizing high precision pressure control of EPBS.

Optimization of Rotor Assembly Process of Rotor Initial Unbalance of an Aeroengine Gas Generator

The rotor initial unbalance of an aeroengine gas generator of turboshaft engine seriously affects rotor assembly process.To reasonably optimize rotor assembly process,the effect analyses of rotor initial unbalance of single disc and combined discs on rotor dynamic characteristics are firstly implemented in respect of the dispersity of rotor initial unbalance.It is found that the most important factors contributing to rotor vibration are the unbalances of the first stage compressor disc and the second stage turbine disc.However,reducing the mass of two discs conflicts with the control of the whole gas generator rotor balance resulting from the unbalance increase of single components.Thus,we further analyze the key control factors of affecting rotor initial unbalance,and give the strict control measures of centrifugal impeller runout in the assembly process by adjusting the angle of central tie rod axis.The purpose of this measures to make the assembly process simpler and more effective for timely controlling rotor initial unbalance.The efforts of this study validate that the proposed method is workable for the rotor tightened by a central tie rod and possesses the significant meaning of practical application in engineering.

Implementation Study of Dynamic Load Balancing Algorithm of Parallel Tree Computation on Clusters of Heterogeneous Workstation

The rapid growth of interconnected high performance workstations has produced a new computing paradigm called clustered of workstations computing. In these systems load balance problem is a serious impediment to achieve good performance. The main concern of this paper is the implementation of dynamic load balancing algorithm, asynchronous Round Robin (ARR), for balancing workload of parallel tree computation depth-first-search algorithm on Cluster of Heterogeneous Workstations (COW) Many algorithms in artificial intelligence and other areas of computer science are based on depth first search in implicitty defined trees. For these algorithms a load-balancing scheme is required, which is able to evenly distribute parts of an irregularly shaped tree over the workstations with minimal interprocessor communication and without prior knowledge of the tree’s shape. For the (ARR) algorithm only minimal interprocessor communication is needed when necessary and it runs under the MPI (Message passing interface) that allows parallel execution on heterogeneous SUN cluster of workstation platform. The program code is written in C language and executed under UNIX operating system (Solaris version).

Lumped Time Distribution Function of Dynamic Equilibrium System and Its Application in Calculating Molecular Weight Distribution of Polymer

The lumped time distribution functions were proposed, which can be used for describing the dynamicsystems with two or more than two states of the end of growing polymer chain during chain addition polymerization.Numerical analysis of the lumped time distribution functions was carried out. The method for calculating molecularweight distribution of polymer in the stable free radical polymerization and more general cases was developed basedon the lumped time distribution functions.

Effects of Periodical Salinity Fluctuation on the Growth, Molting, Energy Homeostasis and Molting-Related Gene Expression of Litopenaeus vannamei

To determine the response of Litopenaeus vannamei to periodical salinity fluctuation, a 30-day experiment was conducted in laboratory. In this experiment, two salinity fluctuation amplitudes of 4(group S4) and 10(group S10) were designed. The constant salinity of 30(group S0) was used as the control. Levels of shrimp growth, molting frequency(MF), cellular energy status(ATP, ADP and AMP), as well as the expression of genes encoding molt-inhibiting hormone(MIH), crustacean hyperglycemic hormone(CHH), ecdysteroid-regulated protein(ERP), and energy-related AMP-activated protein kinase(AMPK) were determined. The results showed that periodical salinity fluctuation significantly influenced all indicators except MF which ranged from 13.3% in group S10 to15.4% in group S4. In comparison with shrimps cultured at the constant salinity of 30, those in group S4 showed a significant elevation in growth rate, food conversion efficiency, cellular energy status, ERP and MIH gene transcript abundance, and a significant reduction in CHH and AMPK transcript abundance(P < 0.05). However, salinity fluctuation of 10 only resulted in a significant variation in MIH and CHH gene expression when compared to the control(P < 0.05). According to our findings, L. vannamei may be highly capable of tolerating salinity fluctuation. When ambient salinity fluctuated at approx. 4, the increased MF and energy stores in organisms may aid to promoting shrimp growth.

High-precision inductance measurement system based on double-excitation auto-balancing bridge

In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital synthesizer(DDS)as signal generator is used as the bridge excitation source,and the bridge is automatically balanced by adjusting and measuring the voltage ratio.Using standard resistors,the system can achieve high precision measurement of four-terminal pair inductors in the frequency range of 100Hz-100kHz.Aiming at the low efficiency of bridge balancing,an iterative balancing algorithm based on the steepest descent method is proposed.In order to suppress the interference caused by the initial phase change and non-integer periodic sampling,the high-precision measurement of the complex impedance of inductance is realized based on the all-phase fast Fourier transform(apFFT).Finally,the corresponding measurement system is built and the inductance measurement experiment is carried out.The experimental results show that the relative error of the system for inductance measurement can be as low as 0.009%,and the optimal relative measurement uncertainty of the system can reach 9.89×10^(-4)compared with 5×10^(-5)of commercial impedance analyzer.