武科大机械专业英语l.ppt

Lesson 9 Rolling Contact Bearings, 22019/5/5,Terminology Text tour,机械工程专业英语教程,1,Terminology Fret To wear away, erode 磨损或腐蚀 Fretting: 微振磨损 Lubricant A substance, such as grease or oil, that reduces friction when applied as a surface coating to moving parts. 润滑剂：一种脂或油的物质，被用在运动部分表面时可减少摩擦,机械工程专业英语教程,2, 22019/5/5,Alloy A homogeneous mixture or solid solution of two or more metals, the atoms of one replacing or occupying interstitial(空隙的) positions between the atoms of the other 合金：两种或更多种金属的均匀混合物或固溶体，一种金属的原子代替或占据了另一种金属晶格中节点间隙。 Brass is an alloy of copper and zinc. 黄铜是铜和锌的合金,机械工程专业英语教程,3, 22019/5/5,Modulus 模量 A quantity that expresses the degree to which a substance possesses a property, such as elasticity 模量：一种参数，表示一种物质具有的一个特性之程度，如弹性。,机械工程专业英语教程,4, 22019/5/5,fivefold 五倍的，五重的,机械工程专业英语教程,5, 22019/5/5,stiffness 刚性，刚度，稳定性,deflection 偏差，偏移，弯曲，挠度,frictional 摩擦的，由摩擦产生的,机械工程专业英语教程,6, 22019/5/5,drag 拖，牵引，摩擦，阻碍，阻力，摩擦力，阻尼,wear 磨损，磨蚀，消耗，耗损,contaminant 沾染，杂质，污染物质，污染剂,机械工程专业英语教程,7, 22019/5/5,sealing 密封，封接,Through-harden 全部硬化，穿透淬火，淬透,HV=Vickers hardness 维氏硬度,机械工程专业英语教程,8, 22019/5/5,clearance 间隙，空隙，余地，间距,interference 干涉，干扰，妨碍，过盈，相互影响,chamfer 在开槽，倒棱，倒角，圆角,机械工程专业英语教程,9, 22019/5/5,raceway 轴承座圈，滚道,tribology 摩擦学,The concern of a machine designer with ball and roller bearings is fivefold as follows: (a) life in relation to load; (b) stiffness, i.e. deflections under load; (c) friction; (d) wear; (e) noise.,机械工程专业英语教程,10, 22019/5/5,Lesson 9 Rolling Contact Bearings 滚动轴承,For moderate（中等的） loads and speeds the correct selection of a standard bearing on the basis of load rating（等级） will usually secure satisfactory performance（行为）.,机械工程专业英语教程,11, 22019/5/5,Lesson 9 Rolling Contact Bearings 滚动轴承,Lesson 9 Rolling Contact Bearings 滚动轴承,The deflection of bearing elements will become important where loads are high, although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling（冷却） arrangements become necessary which may increase frictional drag（摩擦阻力）.,Lesson 9 Rolling and Contact Bearings滚动轴承,Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard to（考虑）the hostility（破坏，敌意） of the environment.,Lesson 9 Rolling and Contact Bearings滚动轴承,Because the high quality and low price of ball and roller bearings depends on quantity（大量的，许多） production, the task of the machine designer becomes one of selection rather than design.,Lesson 9 Rolling and Contact Bearings滚动轴承,Rolling-contact bearings are generally made with steel which is through-hardened（整体淬火） to about 900 HV, although in many mechanisms special races（轴承套） are not provided and the interacting surfaces are hardened to about 600 HV. ,It is not surprising that, owing to the high stresses involved, a predominant（突出的，主要的） form of failure should be metal fatigue, and a good deal of work is currently in progress（进展） intended to improve the reliability of this type of bearing.,机械工程专业英语教程,16, 22019/5/5,Design can be based on accepted values of life and it is general practice in the bearing industry to define（确定） the load capacity（载荷容量） of the bearing as that value below which 90 per cent of a batch （批）will exceed a life of one million revolutions（转数）.,机械工程专业英语教程,17, 22019/5/5,Lesson 9 Rolling and Contact Bearings滚动轴承,Notwithstanding（尽管）the fact that responsibility for the basic design of ball and roller bearings rests with（在于，落于）the bearing manufacturer, the machine designer must form a correct appreciation（认识） of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.,Lesson 9 Rolling and Contact Bearings滚动轴承,The fit（装配） of the bearing races（圈） onto the shaft or onto the housings is of critical importance because of their combined effect （配合影响）on the internal clearance （间隙）of the bearing as well as preserving the desired degree of interference fit（过盈配合）. Inadequate（不充分的） interference can induce serious trouble from fretting corrosion（微动腐蚀）.,Lesson 9 Rolling and Contact Bearings滚动轴承,The inner race（轴承圈） is frequently located axially by abutting（邻接）against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to allow space for this.,Lesson 9 Rolling and Contact Bearings滚动轴承,Where life is not the determining factor in design, it is usual to determine maximum loading by the amount to which a bearing will deflect under load.,Lesson 9 Rolling and Contact Bearings滚动轴承,Thus the concept of “static load-carrying capacity” is understood to mean the load that can be applied to a bearing, which is either stationary or subject to（承受） slight（轻微） swiveling（旋转）motions, without impairing（削弱，损伤） its running qualities for subsequent（连续的） rotational motion. ,Lesson 9 Rolling and Contact Bearings滚动轴承,This has been determined by practical experience as the load which when applied to a bearing results in a total deformation of the rolling element and raceway at any point of contact not exceeding 0.01 percent of the rolling-element diameter. This would correspond to（相当于，与相对） a permanent deformation of 0.0025mm for a ball 25mm in diameter.,Lesson9 Rolling and Contact Bearings滚动轴承,The successful functioning of many bearings depends upon providing them with adequate （充分的）protection against their environment, and in some circumstances the environment must be protected from lubricants or products of deterioration（恶化）of the bearing surfaces. Achievement of the corre