機(jī)械外文翻譯---機(jī)構(gòu)介紹(已修改)
2025-06-01 00:05 本頁面
【正文】 黃石理工學(xué)院 畢業(yè)設(shè)計(jì) (論文 ) 外文文獻(xiàn)翻譯 Introduction to mechanism The function of mechanism is to transmit or transform motion from one rigid body to another as part of the action of a machine. There are three types of mon mechanical devices that can be used as basic elements of a mechanism. (1) Gear system, in which toothed members in contact transmit motion between rotating shafts. (2) Cam system, where a uniform motion of an input member is converted into a nonuniform motion of the output member. (3) Plane and spatial linkages are also useful in creating mechanical motions for a point or rigid body. A kinematic chain is a system of links, which are either jointed together or are in contact with one another in a manner that permits them to move relative to one another. If one of the links is fixed and the movement of any other link to a new position will cause each of the other links to move to definite predictable position, the system is a constrained kinematic chain. Otherwise, the system is an unconstrained kinematic chain. A mechanism or linkage is a constrained kinematic chain, and is a mechanical divice that has the purpose of transferring motion and force from a source to an output. A linkage consists of links (or bar),generally considered rigid,which are connected by joints, such as pin (or revolute) or prismatic joints, to form open or closed chains (or loops). Such kinematic chains,with at least one link fixed, bee (i) mechanisms if at least two other links remain mobility, or (ii) stuctures if no mobility remains. In other words, a mechanism permits relative motion between its “rigid links”。 a structure does not. Since linkages make simple mechanisms and can be designed to perform plex tasks, such as nonlinear motion and force ransmission, they will receive much attention in mechanism study. Mechanisms are used in a great variety of machines and devices. The simplest closedloop linkage is the fourbar linkage, which has three moving links (plus one fixed link) and four pin joints. 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. The output link connects another moving povit to another ground povit. The coupler or floating link connected the two moving pivots, thereby “coupling” the input to the output link. The fourbar linkage has some special configurations created by making one or more links infinite in length。 The slidercrank （ or crank and slider） mechanism is a fourbar chain with a slinder replacing an infinitely long output link。 The internal bustion engine is built based on this mechanism。 Other forms of four bar mechanisms exist in which a slider is guided on a moving link rather than on a fixed link. These are called inversions of the slidercrank， produced when another link（ the crank， coupler， or slider） is fixed link。 Although the fourbar linkage and slidercrank mechanism are very useful and found in thousands of applications， we can see that these linkages have limited performance level。 Linkages with more members are often used in more demand
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