机械制造专业英语

The machining of materials by cutting is carried out by means of cutting tools The characteristic feature of all such tools is the wedge shaped working part called the tool point Tools with wedge shaped points may be used for parting off or for generating shapes The difference between these two operations is that in parting off the layer separated from the material is usually small and is totally or for the most Part of it plastically deformed The workpiece being machined and the cutting tool must preserve their correct positions during the machining process and must carry out suitable motions in relation to each other The workpiece and tool are fixed on a machine called machine tool by means of jigs and fixtures The machine tool also provides the necessary motions of the tool and workpiece The theory of machining by cutting depends upon several basic sciences which are often interconnected At present the following machining theories independent though interconnected have been developed a cutting of materials particularly of metals in various media this theory has considerable fundamental importance b machine tool design kinematics and dynamics c cutting tool design and the study of tool materials d design of machining jigs and fixtures e dimensioning and workshop measurements workshop metrology The theory of metal cutting comprises research and scientific induction concerning the phenomena of the cutting process based on the principles of physics and other basic sciences research on important practical characteristics of cutting comprising cutting forces and energy cutting heat and temperature tool wear geometrical and physical properties of the surface layer being machined workpiece accuracy and the kind of waste produced chip preparation of instructions for a scientifically and technically justified choice of machining conditions in order to optimize the industrial machining process 2 Turning is a method of machining by cutting in which the workpiece carries out a rotary motion and the tool a plane linear motion Depending on the orientation of the axis of workpiece rotation horizontal turning shortly called turning because of the commonness of its application and vertical turning are distinguished Both the outer and inner surfaces can be turned Turning of outer surfaces is called external turning Turning of inner surfaces is called internal turning or boring Further division of turning into various types is carried out on the basis of the mutual situation of the basic motions The basic motions of turning are the primary motion which is the rotary motion of the workpiece the auxiliary motion which is the plane motion of the tool also called the feed motion The axis of rotation constituting the primary motion is called the turning axis The following kinematic types of turning are distinguished external and internal straight turning when the direction of auxiliary motion is parallel to the turning axis external and internal taper turning when the direction of auxiliary motion intersects with the turning axis external and internal transverse turning when the direction of auxiliary motion is perpendicular to the turning axis Transverse turning is further divided into facing and radial cutting Facing both external and internal may be carried out in the direction from the turning axis outwards and is then called centrifugal facing or toward the turning axis and is then called centripetal facing 3 机械加工是指通过各种机械对工件的外形尺寸或性能进行改变的过程 其 含义有多种理解 机械加工广义指能用机械手段制造产品的过程 狭义指用车 床 铣床 钻床 磨床 冲压机 压铸机等专用机械设备制作零件的过程 按 被加工工件处于的温度状态 分为冷加工和热加工 一般在常温下不引起工件 的化学或物相变化的加工 称冷加工 同样的 高于或低于常温状态而且会引 起工件的化学或物相变化的加工 称热加工 冷加工按加工方式的差别可分为 切削加工和压力加工 热加工常见有热处理 煅造 铸造和焊接 4 机器生产过程是指从原材料 或半成品 制成产品的全部过程 对机器生 产而言包括原材料的运输和保存 生产的准备 毛坯的制造 零件的加工和热 处理 产品的装配 及调试 油漆和包装等内容 生产过程的内容十分广泛 现代企业用系统工程学的原理和方法组织生产和指导生产 将生产过程看成是 一个具有输入和输出的生产系统 能使企业的管理科学化 使企业更具应变力 和竞争力 5 在生产过程中 凡是改变生产对象