機械英漢翻譯-機械設(shè)計概論(文件)
【正文】 isting products of rival panies? (3)Is it economical to produce? (4)Can it be readily maintained? (5)Will it sell and make a profit? Only time will provide the true answers to the preceding questions， but the product should be designed， manufactured and marketed only with initial affirmative answers． The design engineer also must municate the finalized design to manufacturing through the use of detail and assembly drawings． Quite often， a problem will occur during the manufacturing cycle． It may be that a change is required in the dimensioning or tolerancing of a part 80 that it can be more readily produced． This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected． In other eases， a deficiency in the design may appear during assembly or testing just prior to shipping． These realities simply bear out the fact that design is a living process． There is always a better way to do it and the designer should constantly strive towards finding that better way． A new machine is born because there is a real or imagined need for it． It evolves from Someone’s conception of a device with which to acplish a particular purpose． From the conception follows a study of the arrangement of the parts， the location and length of links (which may include a kinematic study of the linkage)， the places for gears， bolts， springs， cams， and other elements of machines． With all ideas subject to change and improvement， several solutions may be 3 and usually are found， the seemingly best one being chosen． The actual practice of designing is applying a bination of scientific principles and a knowing judgment based on experience． It is seldom that a design problem has only one right answer， a situation that is often annoying to the beginner in machine design． Engineering practice usually requires promises． Competition may require a reluctant decision contrary to one’s best engineering judgment； production difficulties may force a change of design； etc． A good designer needs many attributes， for example： (1)A good background in strength of materials， SO that the stress analyses are sound． The parts of the machine should have adequate strength and rigidity, or other characteristics as needed． (2)A good acquaintance with the properties of materials used in machines． (3)A familiarity with the major characteristics and economics of variou
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