对引进钢管生产线的改进

我们引进了一条美国精细钢管生产线,其生产的钢管直径为ф8、ф6和ф4.76.在调试和使用过程中发现该生产线有许多缺陷,故作了以下改进.一、盘管机驱动轮和导向轮的改进盘管机的钢制驱动轮和导向轮对钢管表面造成严重划伤(三个轮的工作情况见图1).发现主要原因是驱动轮和导向轮的线速度大于定径辊的线速度,使钢管与驱动轮、导向轮之间有相对滑动,造成钢管表面损伤.     

PLC在钢管自动分选生产线中的应用

在钢管生产过程中,需对不同长度范围的钢管进行分选。通过运用由光电传感器、编码器、运输辊道、翻板机、过钢台架、接近开关组成的钢管自动分选生产线,可较好的解决这一问题。在该系统中,采用西门子公司PLC控制运输辊道和翻板机将一定长度范围内的钢管放置在相应的料筐内,实现了钢管的自动分选,并使分选准确率达到100％。     

列车牵引粘着控制及其仿真

列车在牵引工况下,如果轮轨间相对滑动速度超过最佳相对滑动速度,车轮就会打滑甚至空转,损伤车轮和轨道.为避免这种现象的产生,建立轮轨牵引力矩传递的简化模型,利用干扰观测器对粘着系数以及车辆速度进行估计,运用递归最小二乘法预测切线力系数与相对滑动速度曲线的斜率,以判断当前状态是否滑动,采用模糊PID控制算法对系统进行控制.仿真结果表明,这种方法能够有效地使切线力系数保持在最大值附近,使相对滑动速度保持在最佳值附近,防止因车轮打滑而损伤轮轨,达到了期望的控制效果.     

直缝钢管轧机成形辊的失效分析

介绍对直缝钢管冷轧机的成形辊进行失效分析的过程。针对成形辊的服役环境，这里对成形辊的开裂和磨损原因进行了分析，认为成形辊与管坯相对滑动而引起的摩擦磨损、成形辊表面被反复加热和冷却而引起的热疲劳是引起成形辊磨损的主要原因。认为裂纹是由热应力引起的热疲劳开裂，从理论上推算热应力的大小，并分析其使工件热疲劳破坏的可能性，这里还将在提高成形辊寿命方面作一些探讨     

基于HMI与PLC的位移闭环控制系统在大型钢管防腐涂层自动涂装生产线上的应用

针对大型钢管防腐涂层在自动涂装生产线中由于大型钢管的行进速度变化不均造成漆膜厚度不均匀、油漆损耗过大的问题,在大型钢管防腐涂层自动涂装生产线中采用了人机界面(HMI)与可编程控制器(PLC)控制系统、激光位移传感器测速装置对大型钢管行进速度实行闭环控制,控制大型钢管匀速行进。通过实际应用分析,对比测量开环、闭环速度历史曲线变化情况,同时在喷涂参数相同的情况下,研究了闭环控制前和闭环控制后大型钢管防腐涂层漆膜厚度的变化情况。研究结果表明:基于HMI与PLC的位移闭环控制系统能有效地解决由于大型钢管在行进过程中速度变化不均所造成的漆膜厚度不均匀、油漆损耗过大的问题,漆膜厚度的变化幅度由原±30%降至±10%左右,证明基于HMI与PLC的位移闭环控制系统在大型钢管防腐涂层自动涂装生产线上的应用是可行的。     

负荷平衡在张力辊控制中的应用

针对板带生产线中张力辊控制中的负荷平衡问题,介绍张力辊在速度基准和张力调节两种模式下的解决方案,实现张力辊在全线运行中的速度和张力控制。实际生产运行中,采用该方案的带钢表面处理生产线系统运行稳定,能够满足工艺要求。     

轧钢车间辊道设计的研究与应用

阐述了如何选取轧钢车间辊道的基本参数,包括辊子直径、辊身长度、辊距、辊道速度等参数。轧钢车间辊道的传动形式可分为集体传动辊道和单独传动辊道两种,针对应用广泛的单独传动辊道,通过实例计算来介绍如何设计选型辊道电机,并对计算结果进行了验算,与以前该类辊道的计算方法相比,不仅对单独传动辊道进行了设计计算,而且还通过实例对计算结果进行了验算,这有助于提高计算结果的实际意义,实际使用结果证明该计算和验算方法有效。     

大型钢管矫直机矫直辊辊形曲面的范成加工

大型钢管矫直机矫直辊辊形曲面的范成加工高春花（太重集团公司矫正机分厂）钢管矫直机是钢管生产线上的主要设备。矫直机的工作辊是关键零件。其辊形曲面的制造精度和粗糙度直接影响到被矫直钢管的质量。早在６０、７０年代，我厂已研制成功并为用户生产了多台大型钢管矫...     

摩擦力-相对滑动速度关系的实验研究

对金属往复滑动摩擦力-相对滑动速度的关系进行了试验研究，通过设计相对滑动速度曲线实现了无摩擦振动工况下的摩擦力-相对滑动速度关系的测量。文中还对摩擦振动工况下的摩擦力的测量作了探讨。本文的试验数据可作为摩擦振动和摩擦噪声理论研究的基础数据。     

变频调速在辊涂机中的应用

在带钢的彩色涂层生产线机组中,辊涂机采用变频器调速控制,变频器通过现场总线ProfiBus与PLC控制设备联接构成通讯网络控制系统,实现对辊涂机的工艺操作及速度控制,由于采用了网络控制,使得辊涂机能够根据全线生产状态而随时调节各辊速度,以保证带钢表面涂层质量。     

Influence of different surface modification technologies on friction of conformal tribopair in mixed and boundary lubrication regimes

Moving machine assemblies are generally designed to operate in full film lubrication regime to ensure high efficiency and durability of components. However, it is not always possible to ensure this owing to changes in operating conditions such as load, speed, and temperature. The overall frictional losses in machines are dependent on the operating lubrication regimes (boundary, mixed or full-film). The present work is thus aimed at investigating the role of different surface modification technologies on friction of a sliding bearing/roller tribopair both in boundary and mixed lubrication regimes. A special test rig comprising of two bearings was built for the experimental studies. Tribological tests were conducted in a wide speed range to enable studies in boundary and mixed lubrication regimes. The influence of application of different surface modification technologies on both the sliding bearing and the roller surfaces on friction has been studied. The rollers used in these studies were provided with five different coatings (hard DLCs and a soft self-lubricating coating). Additionally, two uncoated rollers having different surface roughness were also studied. Uncoated bearings were used in all tribopairs except two. These two bearings were coated with DLC and phosphate coatings respectively and uncoated rollers were the mating counterparts. Friction measurements were made on the new as well as the previously run-in surfaces. It was found that the rollers with self-lubricating coating resulted in lowest boundary friction closely followed by the rollers with the hardest DLC coatings. The DLC coating applied on to the bearing showed lower boundary friction after running-in. Mixed friction has been found to be mainly dependent on the surface topography characteristics of both the original and the run-in surfaces of bearings and rollers. The harder DLC coatings and the phosphated bearing showed the lowest mixed friction due to an efficient running-in of the bearing surface.     

Statistical analysis of dimensional changes in thermomechanical tube-spinning process

Tube-spinning process is an effective method for manufacturing long thin-wall tubes with precision dimensions and desired mechanical property. The main objectives of this research deal with the influences of major process parameters of thermomechanical tube-spinning process such as preform thickness, thickness reduction, mandrel rotational speed, feed rate of rollers, solution treatment time, and aging treatment time on internal diameter growth and wall thickness changes for manufacturing of 2024 aluminum spun tubes using design of experiments. Experimental results are analyzed by analysis of variance and empirical models of internal diameter growth and wall thickness changes are developed. It is found that lower thickness reduction with thinner preform thickness, higher feed rate of rollers, slower mandrel rotational speed, and lower solution treatment time have advantages for obtaining smaller internal diameter growth and wall thickness changes.     

双联泵机床动力滑台新回路的PLC控制

阐述了PLC在动力滑台的液压传动控制系统中的应用,在组合机床动力滑台原液压回路的基础上,引入一种新的、用于实现动力滑台运动的二工进新回路。新回路具有独自调节与能量消耗较低等特点。     

The Frictional Properties of Newtonian Fluids in Rolling–Sliding soft-EHL Contact

A combined experimental and numerical study has been carried out to explore friction in rolling–sliding, soft-EHL contact. Experimental work has employed corn syrup solutions of different concentrations in water to provide a range of lubricant viscosities and has measured Couette friction in mixed rolling–sliding conditions over a wide range of entrainment speeds. A Stribeck curve has been generated, ranging from the boundary to full film, isoviscous-elastic lubrication regime. In the latter regime, friction coefficient is approximately proportional to the product of (entrainment speed × viscosity) raised to the power 0.55. Numerical solution of the isoviscous-elastic lubrication regime has been used to derive predictive equations for both Couette and Poiseuille friction in circular, soft-EHL contacts. This shows that in soft-EHL the Poiseuille or “rolling” friction can have magnitude comparable to the Couette friction. The calculated Poiseuille friction coefficient can be predicted from non-dimensional load and speed using a simple power law expression similar to that used for film thickness. However accurate prediction of calculated Couette friction coefficient requires a two-term power law expression. Comparison of experimental and numerical Couette friction coefficients shows quite good agreement between the two, with a similar non-dimensional speed dependence, but slightly lower predicted than measured values.     

大型对数凸形圆柱滚子磨削加工结果分析

为满足客户需求,开展了大型圆柱滚子对数凸度成形磨削加工试验,阐述了加工原理,确定了磨削加工工艺。根据圆柱滚子凸度轮廓的已知数据,结合Solidworks样条曲线拟合,得到砂轮工作面内凹曲线上相应点的修整量占比。采用直线插补原理控制金刚石笔修整轨迹,将砂轮工作面修整成内凹的对数曲线廓形,加工时将砂轮工作面形状复映到滚子素线上。试验结果表明:滚子检测技术指标均能满足产品要求,且轴向跳动和圆度误差远小于产品要求值,滚子凸度最大值为89.8μm,滚子两侧凸度偏差不超过1.5μm。     

Experimental investigation of temperature rise in elliptical EHL contacts

A toroidal traction drive continuously variable transmission (CVT) transmits power by the shearing action of lubricant film under heavy loads at contact points on the CVT rollers. In other words, rolling and sliding motions produce traction force. Furthermore, due to the geometry of the toroidal CVT, spin motion is produced at the contact points. These contact points, which are elliptical in shape, are where shear stress of the lubricant generates frictional heat. Temperature rise at the contact point has never been measured under the conditions of high rolling speed (velocity) and minute amounts of sliding (slippage), nor has the influence of spin motion on temperature rise been examined thus far. The authors et al. measured temperature distribution at contact points under conditions of high rolling speed and minute amounts of sliding, such as what is found in a toroidal CVT, using an FZG twin-disk test machine and thin-film sensors. The influence of spin motion on temperature rise was also experimentally investigated.     

Relating contact conditions to abrasive wear

Damage caused by particles within rolling/sliding contacts can severely reduce the operational life of machinery such as roller bearings, gears and pumps.Abrasive wear of spherical roller thrust bearings has been studied using a stylus apparatus and scanning electron microscopy (SEM). Both a standard bearing and a bearing with rollers coated with metal mixed amorphous carbon (Me-C:H) were studied. The SEM measurements were performed systematically across the contact surfaces so that surfaces with gradually different contact situations could be examined. These measurements were compared to the measured wear depth of the components of the roller bearing. Also, the calculated contact conditions in terms of creep, contact size and surface separation have been related to the observed wear pattern at various locations.To attempt to understand the wear behaviour of the bearing with coated rollers, the coating as well as the material content of the surfaces were examined using both SEM and energy dispersive X-ray spectrometry (EDS). This revealed that the coating did not flake off but rather was scratched off.It is possible to link the abrasive wear behaviour to the contact conditions. It is crucial to understand this relationship when building a simulation model of abrasive wear.     

三叉杆滚子式万向联轴器传动中的效率分析

通过分析三叉杆滚子式万向联轴器传动过程中球形滚子与叉杆之间的滑动摩擦损失和滚子与导向槽之间的滑动摩擦损失而得出联轴器在任意输入角时的瞬时效率,最后经过积分运算而求出三叉杆滚子式万向联轴器传动中的平均效率。     

Film-forming capability in rough surface EHL investigated using contact resistance

Highly loaded machine elements such as gears and cams have a non-smooth surface topography that is created during manufacturing. It is well known that the film-building properties of such surfaces may be different from those that are perfectly smooth. The capability to form a separating film may also be altered in time due to run-in phenomena. In this study, a smooth steel ball was loaded against rough steel discs and run under pure rolling as well as sliding conditions. Several different steel surfaces were tested under nominal EHL conditions, where the contact was monitored by means of its electrical resistance and capacitance. Each surface was first run in for 15 min, followed by a sweep-in speed determining the lift-off curve. Electrical contact measurements were continuously conducted during run in as well as lift-off. Fully formulated gear oil and its base fluid were used as test lubricants. Results show that run in of a surface seems to be a competition between conformation of surface topography and tribofilm formation. At the tested conditions, the formation of a tribofilm is dependent on the initial surface topography and is created rapidly causing less metal–metal contact. This film also seems to effectively prohibit changes in surface topography causing less structural run in than expected.     

A study of sliding between rollers and races in a roller bearing with a numerical model for mechanical event simulations

A numerical model of a roller bearing is presented in this paper. These simulations provide us with the spatial and time distributions of stress and strain values, as well as all the nodal displacements at every time step. The model was developed with the finite element method (FEM) for mechanical event simulations (MES) with the commercial code Algor^TM. The model has been validated by verifying that the contact force distributions correspond to those predicted by the analytical model of Harris-Jones.As an application, a study of sliding between the rollers and the races has been carried out. For each roller, a rolling zone can be defined in which local sliding (computed between two consecutive time steps) is negligible. According to the simulations, we conclude that the rolling zone is practically the same for all the rollers in the same simulation; that this rolling zone is smaller than the corresponding load zone, and that rolling and load zones are angularly centered with respect to each other.