共查询到20条相似文献,搜索用时 203 毫秒
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本文在计算冷轧薄板接触弧长度和轧制压力时,不仅考虑轧辊弹性变形,而且也考虑轧件弹性变形。把变形区分为入口弹性区、塑性区和出口弹性区。应用弹性力学基本方程、塑性条件和平板压缩理论导出了入口弹性区和出口弹性区单位宽度轧制力公式及塑性区平均单位压力公式。应用弹性接触理论和变形区的几何关系导出了计算冷轧薄板接触弧长度公式。最后给出了考虑轧辊和轧件弹性变形时计算冷轧薄板的总的轧制力公式。该公式不仅适用于一般工程计算,而且也能为在线控制的电子计算机提供较为精确的轧制力数学模型。 相似文献
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箔带轧制的三维接触有限元分析 总被引:5,自引:0,他引:5
基于对三维多体接触问题有限元混合法基本原理及接触面的定解条件和判定条件的分析 ,本文将箔带轧机辊系及轧件组成的辊带系统视为三维多体接触问题 ,建立了接触有限元分析模型。对某厂四辊铝箔轧机初轧工况进行了数值计算 ,求得了辊缝内轧制压力的真实分布规律 ,充分揭示了箔带轧制过程中非轧制辊面存在压靠的事实。最后 ,针对来料板凸度对轧件板形的影响进行了有限元仿真分析 ,得出了与轧制规程图分析法一致的结论 相似文献
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工艺参数对多楔轧件接口质量的影响规律 总被引:3,自引:1,他引:2
楔横轧多楔成形工艺是生产长轴类零件的先进方法,但生产过程中模具工艺参数对轧件接口质量的影响比较复杂。根据楔横轧多楔模具的工艺特点,建立多楔轧制长轴类零件的三维有限元模型。基于ANSYS/LS-DYNA有限元模拟软件,在不同模具工艺参数下对多楔轧制过程进行了有限元模拟,得到模具工艺参数对轧件接口质量的影响规律。在与模拟工艺参数相同的条件下进行轧制试验,试验结果和模拟结果一致。通过对理论模拟和轧制试验获得结果的分析,得到工艺参数中过渡角对轧件的接口质量影响最大、展宽角对轧件接口质量影响最小的结论。综合考虑各工艺参数的影响,给出保证轧件接口质量良好的过渡角选择范围。研究结果为多楔成形长轴类零件的模具设计提供理论依据和参考。 相似文献
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C. Liu P. Hartley C.E.N. Sturgess G.W. Rowe 《International Journal of Mechanical Sciences》1985,27(11-12)
Strip rolling is simulated using an elastic-plastic finite element technique which includes the extent of both elastic and plastic deformation outside the nominal contact deformation zone. Solutions for non-steady and steady-state rolling are obtained. The stress and strain distributions within the workpiece, the velocity fields (absolute and relative to the roll surface), and the normal pressure and shear stress distributions along the arc of contact are calculated. Analyses are conducted with different levels of friction, material properties, workpiece dimensions and reductions. The results are compared with previous theoretical and experimental work, with which good agreement is found. The usefulness of numerical analyses for the investigation of parameters relevant to industrial rolling practice is demonstrated. 相似文献
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Fretting wear is often found at the contact surfaces of a tight assembly where small‐amplitude oscillatory movement occurs, which can be the concealed origin of some enormous accidents. Employment of solid lubrication coatings, as one of effective measurements to palliate the fretting damage, has been widely acknowledged. The present work studied the fretting behaviour of a molybdenum disulphide coating on SUS 316 stainless steel substrate by a relatively cheap and easy‐to‐use process: pressure spraying. Two contact configurations (cylinder‐on‐flat and ball‐on‐flat) were used in the tests with different displacement amplitudes (from 5 to 75 µm) and normal loads (from 100 to 400 N for ball‐on‐flat and from 400 to 1000 N for cylinder‐on‐flat). The results showed that large displacement amplitude is adverse to friction coefficient and coating lifetime and that under a critical contact pressure, coating endurance is improved contact pressure increases. Contact configuration influences friction coefficient by changing contact area and distribution of contact pressure. One master curve of average dissipated energy per cycle in initial stable stage was obtained for two contact configurations, which can be employed to approximately predict coating lifetime. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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《Wear》2007,262(5-6):666-671
In the paper, a contact element method was used to analyze a wheel rolling over a rail at high-speeds. The rolling contact of the wheel and rail was considered as a two-dimensional rolling contact in a pure rolling and steady state. The loads applied to the wheel are the different axle-loads of train and the inertia forces caused by accelerations of the wheel in its pure rolling state. The convergence of non-linear numerical analysis on frictional contact was reached through repeated contact calculations. The normal contact pressure and tangential traction on wheel/rail contact surface were obtained for the different axle-loads and the different rolling speeds. The highest rolling speed in the numerical simulation is 400 km/h. Through the detailed numerical simulation and analysis, it was found that there exist some differences between the traditional Hertzian contact pressure and the present normal pressure. With the speed increasing the normal contact pressure becomes larger in the leading area of the contact surface, and becomes smaller in the trailing area of the contact surface. However, in the trailing area the tangential traction become larger, and in the leading area becomes smaller with the speed increasing. 相似文献
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A new analysis for cold rolling of thin strip and foil is developed. This model follows the approach of Fleck et al. [8], but relaxes their assumption of a central flat neutral zone. Instead of following their inverse method to obtain the pressure distribution in this neutral zone, an explicit equation for the contact pressure variation is obtained from the sticking condition in this region. This significantly simplifies the solution method, leading to a much more robust algorithm. Moreover the method treats the cases either where the roll retains its circular arc or where there is very significant roll deformation in the same way, greatly simplifying the method of obtaining solutions. This will facilitate the incorporation of other effects such as the friction models currently being developed. Results are in line with the theory of Fleck et al. [8]. The effect of entry and exit tensions on the non-dimensional load and forward slip is investigated. It is found that the effect of equal entry and exit tensions is equivalent to reducing the yield stress of the strip by this tension stress. 相似文献
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A theoretical model is developed to study the effect of dwell time on the junction growth and static friction of a creeping
polymer sphere in contact with a rigid flat under full stick contact condition. A rapid normal loading into the elastic–plastic
contact regime is followed by a rest period during which creep takes place causing contact area growth, and stress relaxation
that can completely eliminate the plastic zone in the sphere. At the end of this rest time, an increasing tangential loading
is applied to the flat till sliding inception occurs. During this loading step, further increase of the contact area and reappearing
of a plastic zone in the sphere take place. An increase in static friction resulting from the dwell time during the creep
stage is clearly demonstrated and explained. 相似文献
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T. Czyżewski 《Wear》1975,31(1):119-140
A theoretical analysis has been carried out of changes in the stress field in the elastohydrodynamic contact zone of cylindrical surfaces due to operating variables. Their possible role in rolling contact fatigue has been assessed by accelerated rolling contact fatigue tests. The results show that changes of the elastohydrodynamic pressure distribution in the contact zone associated with increase of the viscosity-velocity parameter induce considerable changes in the stress field in the contact zone. The poor correlation of rolling contact fatigue life with material effects according to elastohydrodynamic theory and the considerable changes in rolling contact fatigue life due to lubrication effects suggests that the explanation lies outside elastohydrodynamic theory and possibly in the theory of asperity lubrication. 相似文献
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B.J. Briscoe A. Chateauminois T.C. Lindley D. Parsonage 《Tribology International》1998,31(11):701-711
The fretting wear behaviour of PMMA against a rigid counterface has been investigated under various contact zone kinematic conditions. A specific device has been used in order to achieve load axis spin or stationary rolling motions in a contact between a PMMA flat and a steel ball. Wear processes under such conditions have been investigated by means of laser profilometry and in-situ optical observations of the contact area during tests. Very different wear patterns were produced depending on the contact kinematics. For stationary rolling conditions, the progressive accumulation and compaction of debris induced the formation of a single ripple located in the middle of the contact. Very little debris was found to be eliminated from the contact and the resulting wear was quite low. On the other hand, little accumulation of debris was observed for torsional contact conditions and the wear was drastically enhanced. These results are analysed by considering the effects of contact zone kinematics on particle detachment and third body elimination. 相似文献
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将全局网络重构的有限元方法与润滑条件下的数值计算模型相结合,分析油封在润滑条件下的磨损过程中,唇口轮廓、接触压力、最大接触压力、泵吸率和摩擦扭矩等密封性能参数的变化趋势。模拟结果表明:油封磨损可以分为2个阶段,第一阶段为初期磨损阶段,该阶段唇口的磨损速率较大,最大接触压力也呈现较大的下降趋势;第二阶段为稳定磨损阶段,该阶段磨损速率较小,磨损量也较小,最大接触压力变化趋势趋于平缓;唇口轮廓的磨损程度随着磨损时间的增加而逐渐趋于平缓,并且空气侧的磨损程度比油侧更为严重;泵吸率呈现出先下降后上升的变化趋势,说明磨损会导致的唇尖材料损失,会引起油封密封性能的不稳定;摩擦扭矩由于受磨损导致的径向力和润滑油剪切作用相互变化的叠加影响,呈现上升的趋势。 相似文献