轧制塑性加工中的摩擦机理探究

针对轧制塑性加工中轧件金属发生塑性变形的特点,本文经过理论分析,实验验证,建立一个新的摩擦机理：滚-滑摩擦机理。     

Construction of a Precursor Model for the Concept of Rolling Friction in the Thought of Preschool Age Children: A Socio-cognitive Teaching Intervention

The aim of this study was to explore the extent to which the characteristics of two teaching interventions can bring about cognitive progress in preschoolers with regard to the factors rolling friction depends on, when it is applied to an object that is freely rolling on a horizontal surface. The study was conducted in three phases: pre-test, teaching intervention, and post-test. Two teaching strategies were compared: one inspired by Piaget’s theory (Piagetian approach) and one inspired by post-Piagetian and Vygotkian assumptions (socio-cognitive approach). A statistically significant difference was found between the pre-test and post-test, providing evidence that the socio-cognitive approach allows for the creation of a more appropriate teaching framework compared to the Piagetian one.     

Steam as coolant and lubricant in turning of metal matrix composites

Green cutting has become focus of attention in ecological and environmental protection. Steam is cheap, poilution-free and eco-friendly, and then is a good and economical coolant and lubricant. Steam generator and steam feeding system were developed to generate and feed steam. Comparative experiments were carried out in cutting AA6061-15 vol.% SiC （25 p.m particle size）, with cubic boron nitride （CBN） insert KB-90 grade under the conditions of compressed air, oil water emulsion, steam as coolant and lubricant, and dry cutting, respectively. The experimental results show that, with steam as coolant and lubricant, gradual reduction in the cutting force, friction coefficient, surface roughness and cutting temperature values were observed. Further, there was reduction in built up edge formation. It is proved that use of water steam as coolant and lubricant is environmentally friendly.     

盲竖井提升钢绳更换方法的探讨与实践

本文主要针对公司左拔矿区286中段盲竖井JKMD-2.25×4(I)E-(ZJKMD-2.25×4(I)E-(ZB)B)的实际情况制定了周密的提升绳更换方案,确定了换绳程序,成功更换了四根提升绳。实践表明,该方法可靠、实用、操作简单,可供其他矿山借鉴。     

多功能摩擦磨损试验机结构设计

对不同固体材料在不同条件下的摩擦磨损实验要求,开发设计了一种多功能摩擦磨损试验机。实现对试验数据的在线或离线采集分析处理,对各种工况可进行选择性模拟试验。能完成往复式摩擦磨损、旋转式摩擦磨损以及滚动式摩擦磨损实验一体化设计,即在同一试验台可实现三种运动方式的试件磨损试验。应用静电感应信号对摩擦磨损状态实施监控观察,并可应用于多种形状、材料夹具摩擦磨损试验,解决了目前摩擦试验机只能试验单一摩擦类型且精度不高的缺点。     

Al2O3颗粒对丁腈橡胶/316L不锈钢配副摩擦磨损行为的影响

目的：研究弹性体/金属配副在硬质颗粒环境下的摩擦磨损行为,分析有无颗粒及颗粒尺寸大小对摩擦学特性的影响,为橡塑密封设计提供参考。创新点：基于橡胶O型圈常见失效机制,模拟橡胶密封圈在颗粒介入时的摩擦磨损行为,探讨硬质颗粒及其颗粒尺寸对橡胶/金属摩擦配副的影响。方法：1.采用球/平面接触方式,开展丁腈橡胶/金属（316L）配副在Al2O3颗粒环境下的摩擦磨损行为,通过考察摩擦系数时变曲线、摩擦副磨损形貌及其损伤机制等特性,揭示 Al2O3颗粒对丁腈橡胶/316L不锈钢配副摩擦磨损行为的影响。结论：1. Al2O3颗粒进入橡胶/金属摩擦配副明显降低摩擦系数、硬质颗粒的犁削作用,加剧金属偶件的磨损;2.大尺寸的Al2O3颗粒能嵌入橡胶基体并加速橡胶的磨损,对金属有微切屑作用;然而随着颗粒尺寸的减小,颗粒反而减缓橡胶的磨损;3.在有无颗粒和不同颗粒尺寸的情况下,橡胶和金属均表现出不同的损伤机制。