机械专业外文翻译---车床及其结构(编辑修改稿)

机械专业外文翻译---车床及其结构(编辑修改稿)内容摘要：

single nut, which is fed, together with the carriage, along the bed. When the lever is disengaged, the half nuts are released and the carriage the other hand, when the feed rod is used, it supplies power to the apron through a worm gear. The latter is keyed to the feed rod and travels with the apron along the feed rod, which has a keyway extending to cover its whole modern lathe usually has a quickchange gearbox located under the headstock and driven from the spindle through a train of gears. It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers. The quickchange gearbox is employed in plain turning, facing and thread cutting operations. Since that gearbox is linked to the spindle, the distance that the apron (and the cuttingtool) travels for each revolution of the spindle can be controlled and is referred to as the feed. • Lathe Cutting Tools The shape and geometry of the lathe tools depend upon the purpose for which they are employed. Turning tools can be classified into two main groups, namely, external cutting tools and internal cutting tools. Each of these two groups include the following types of tools: Turning tools. Turning tools can be either finishing or rough turning tools. Rough turning tools have small nose radii and are employed when deep cuts are made. On the other hand, finishing tools have larger nose radii and are used for obtaining the final required dimensions with good surface finish by making slight depths of cut. Rough turning tools can be righthand or lefthand types, depending upon the direction of feed. They can have straight, bent, or offset shanks. Facing tools. Facing tools are employed in facing operations for machining plane side or end surfaces. There are tools for machining lefthandside surfaces and tools for righthandside surf。