文档介绍：毕业设计(论文)报告纸共14页第1页┊┊┊┊┊┊┊┊┊┊┊┊┊装┊┊┊┊┊订┊┊┊┊┊线┊┊┊┊┊┊┊┊┊┊┊┊┊ LATHES The basic machines that are designed primarily todo turning, facing and boring are called lathes. V ery little turning isdone on other types of machine tools, and nine can do it with equal facility. B ecause lathe can do boring, facing, drilling, and reaming in addition to turning, their versatility permits several operations tobe performed with a single setup of the workpiece. T his accounts for the fact that lathes of various types are more widely used in manufacturing than any other machine tool. L athes in various forms have existed for more than two thousand years. M odem lathes date from about 1797, when Henry Maudsley developed one with a leadscrew. It provided controlled, mechanical feed of the tool. T his ingenious Englishman also developed a change-gear system that could connect the motions of the spindle and leadscrew and thus enable threads tobe cut. L athe Construction .The ponents ofa lathe are depicted in the block diagram of - are the bed, headstock assembly , tailstock assembly, carriage assembly, quick-change gear box, and the leadscrew and feed rod. The bed is the backbone ofa lathe. It is usually made of well-normalized or aged gray or nodular cast iron and provides a heavy, rigid frame on which all the other ponents are mounted. T wo sets of parallel, longitudinal ways, inner and outer, are contained on the bed, usually on the upper side. S ome makers use an inverted V-shape for all four ways, whereas others utilize one inverted V and one flat way inone or both sets. B ecause several ponents are mounted and/or move on the ways they must be made with precision to assure accuracy of alignment. S imilarly, proper precaution should be taken in operating a lathe to assure that the ways are not damaged. Any uracy in them usually means that the accuracy of the entire lathe is destroyed. The ways on most modern lathes are surface hardened to offer greater resistance to wear an