【正文】 nents. Control system for CNC machine tool operation, management and control, by entering the media data are available, interpretation of these data and puting as well as machine tools have an effect。 this term was first used in connection with industrial robots ． Verticalspindle machining centers , or vertical machining centers , are suitable for 畢業(yè)設(shè)計(jì)◆英文翻譯原文 第 3 頁 共 6 頁 performing various machining operations on flat surfaces with deep cavities — for instance , mold and die making ． A verticalspindle machining center , which is similar to a verticalspindle milling machine , is shown in ． The tool magazine is on the left of the figure and all operations and movements are directed and modified through the putercontrol panel on the right ． Because the thrust in vertical machining are directed downward , such machines have high stiffness and produce parts with good dimensional accuracy ． These machines are generally less expensive than horizontalspindle machines ． Horizontalspindle machining centers , or horizontal machining centers , are suitable for large as well as tall workpieces that require machining on a number of their surfaces ． The pallet can be swiveled on different axes to various angular positions ． Another category of horizontalspindle machines is turning centers , which are putercontrolled lathes with several features ． A threeturret puter numericalcontrolled turning center is shown in Fig． 4． 8． This machine is designed with two horizontal spindles and three turrets equipped with a variety of cutting tools used to perform several operations on a rotating workpiece ． Universal machining centers are equipped with both vertical and horizontal spindles ． They have a variety of features and are capable of machining all surfaces of a workpiece (vertical , horizontal , and diagonal ) ． Characteristics and Capabilities of Machining Centers The following are the major characteristics of machining centers : ? They are capable of handling a variety of part sizes and shapes efficiently , economically , and with repetitively high dimensional accuracy 。 ( in.) ． ? The machines are versatile , having as many six axes of linear and angular movements , and are capable of quick change over from one type of product to another , so the need for a variety of machine tools and floor space is significantly reduced． ? The time required for loading and unloading workpiece,changing tools , gaging , and troubleshooting is reduced , so productivity is improved , reducing labor requirements( particularly for skilled labor ) and minimizing production costs ． ? They are highly automated and relatively pact , so that one operator can attend two or more machines at the same time ． ? The machines are equipped with toolcondition monitoring devices for the detection of tool breakgage and wear , as well as probes for toolwear pensation and for tool positioning ． ? Inprocess and postprocess gaging and inspection of machined workpieces are now features of machining centers ． Machining centers are available in a wide variety of sizes and features , and their costs range 畢業(yè)設(shè)計(jì)◆英文翻譯原文 第 4 頁 共 6 頁 from about $50,000 to $1 million and higher ． Typical capacities range up to 75kw (100 hp) and maximum