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1、机械专业英语 学习要求 1、了解科技英语的表达方式和方法,能够 阅读和翻译较简单的本专业相关的科技文 章。 2、了解英语科技文章的结构，掌握与本 专业有关的英语词汇和专业术语。 3、在学习专业英语的同时，掌握获取外 文专业资料及阅读能力。 Part 1 Materials it can provide parts with uniform physical and mechanical properties through out and , depending on the particular material being cast, the design of the part, and
2、 the quantity being produced, its economic advantages can surpass other processes. Lesson 11 Forging Vocabulary： press 压力机；压锻 forging 锻造，锻造的 closed impression dies 封闭式型腔模具 stroke 冲程 冲击 ram 锤头；冲头 dies 模具，模子 cavity 腔；中空 block 坯料；毛坯 drop forging 落锤锻 roughly 粗糙地；大体上 Vocabulary： desire 愿望；要求 shape 形状；模形
3、exact 精确的；强制要求 the finished piece 成品 drawing the dies together 使两模合拢 forced to take this form 压力成形 brass 黄铜；黄铜制品 hydraulic 液压的；液压传动装置 instead of 代替着；而不是 draft 牵引力 complicate 使复杂化 extrude 挤压，模压 impact 碰撞；冲击 Vocabulary： hammer 落锤，锤头 symmetrical 对称的 irregular 不规则的 sizing operations 精锻工艺 indicate 指示；显示
4、by a press goes deeper 深度持续施压 can take 能处理（拿下） rolling 压光，扎制 the final forging 终锻；精锻 overheat 过热 judge 判断 furnace （熔，炼，高）炉 pyrometer 高温计 Forging Processes Metal flow during the forging process normally falls into two categories:upsetting and extrusion. Upsetting occurs when the metal is compressed p
5、arallel to the longitudinal axis of the workpiece. This action enables the metal to flow freely in one direction as in open-die forging, or it can be restrained as in impression-die forging. Extrusion occurs when the metal is compressed parallel to the longitudinal axis of the workpiece and allowed
6、to flow through an orifice(孔) in the die cavity. 锻造工艺中，金属流动通常分为两类：镦粗和挤压。当 金属沿平行于工件纵轴线方向被压缩时是镦粗。这一行 为使金属能沿一个方向自由流动如开式模锻，或者方向 被限制如模膛模锻。当金属沿平行于工件纵轴线被压缩 且允许沿模腔的孔流动时是挤压。 自主学习安排 翻译 Lesson 12 下次上课上交 预习 Lesson 15 and Lesson 18 Lesson 15 Introduction of Mechanism mechanism kinematic kinematic chain link defi
7、nite constrained unconstrained linkage joint pin revolute prismatic nonlinear four-bar-linkage prime mover coupler pivot configuration inversion slider-crank mechanism multiloop sketch skeleton diagram envision binary ternary ternary links quaternary quaternary links cam can followers gear sprocket
8、belt pulley spherical helical three-dimensional intuitively synthesis kinematician innate A kinematic chain is a system of links, that is , rigid bodies, which are either jointed together or are in contact with one another in a manner that permits them to move relative to one another. 运动链是一个构件系统装置，即
9、若干刚体，它们或者互相铰 接或者互相接触，方式上是允许它们彼此间产生相对运动。 A mechanism or linkage is a constrained kinematic chain,and is a mechanical device that has the purpose of transferring motion and /or force from a source to an output. 机构或连杆构件是一个可约束的传动链而且是一个从输入到 输出以传递运动或力为目的的机械装置。 3. The simplest closed-loop linkage is the fo
10、ur-bar linkage, which has three moving links(plus one fixed link) and four pin joints. 最简单的封闭式的连杆机构就是四杆机构，四杆机构有三个 运动构件（加一个固定构件）并且有四个销轴。 四杆构件 The link that is connected to the power source or prime mover and has one moving pivot and one ground pivot is called the input link. 连接动力源或第一动件并且具有一个移动铰和一个固 定
11、铰的构件叫做输入构件。 The slider-crank(or crank and slider) mechanism is a four-bar chain with a slider replacing an infinitely long output link. 曲柄滑块（即曲柄和滑块）机构是一个以一个滑块替 换一个无限长的输出件的四杆机构. The skeleton diagram serves a purpose similar to that of the electrical schematic or circuit diagram in that it displays on
12、ly the essential skeleton of the mechanism, which, however, embodies the key dimensions that affect its motion. 示意图用于电路图解类似的目的，即仅仅表 示机构本质的意图，然而，它要体现影响其运 动的关键的尺寸。 By degree of freedom we mean the number of independent inputs required to determine the position of all links of the mechanism with respec
13、t to ground. 依据自由度，我们可以预定需要的独立输入 的数目，以确定所有构件相对于地面的位置， In kinematic analysis, a particular given mechanism is investigated based on the mechanism geometry plus possibly other known characteristics(such as input angular velocity, angular acceleration, etc) 在运动分析中，根据机构的几何形状加上可 能知道的其他特性（如输入角速度，角加速度 等）来研
14、究确定一个具体的机构。 8. The ability to visualize relative motion, to reason why a mechanism is designed the way it is, and the ability to impove on a particular design are marks of a successful kinematician. 想象相对运动的能力，能推想出之所以这样设 计一个机构的原因和对一个具体设计进行改进 的能力是一个成功机构学家的标志。 Four-bar mechanism When one of the members
15、 of a constrained linkage is fixed, the linkage becomes a mechanism capable of performing a useful mechanical function in a mechine. On pin-connected to the fixed link; the input and output links are usually pivotally connected to the fixed link;the connecting links(couplers) are usually neither inp
16、uts nor outputs. Since any of the links can be fixed, if the links are of different lengths, four mechanisms,each with a different input-output relationship, can be obtained with a four-bar linkage. These four mechanisms are said to be inversions of the basic linkage. 当受约束的连杆机构的一个构件被固定时，连杆机构就变成机器里一个可 能完成某种有用机械功能的机构。在销接的连杆机构上，输入和输出连杆 通常铆接在固定连杆上，连接连杆通常即不是输入连杆也不是输出连杆。 由于任一连杆都可以固定，如果连杆长度不同，通过一个四连杆机构可以 获得4种机构，每
