学习啦【英语散文】 韦彦时间：2016-09-14 16:54:13我要投稿
Machine Tool Technology for NC
Each of the five machining processes is carried out on a machine tool designed to perform that process. Turning is performed on a lathe, drilling is done on a drill press, milling on a milling machining, and so on.
There are several different type of grinding operations with a corresponding variety of machines to perform them.
Numerical control machine tools have been designed for nearly all of the machining processes. The list includes:
Milling machines, vertical spindle and horizontal spindle
Turning machines, both horizontal axis and vertical axis
Horizontal and vertical boring mills
Profiling and contouring mills
Surface grinders and cylindrical grinders
In addition to the machining process, NC machine tools have also been developed for othermetalworking processes. These machines include:
Punch presses for sheet metal hole punching
Presses for sheet metal bending
The introduction of numerical control has had a pronounced influence on the design andoperation of machine tools.
One of the effects of NC has been that the proportion of time spent by the machine cuttingmetal under program control is significantly greater than with manually operated machines.
This causes certain components, such as the spindle, drive gears, and feed screws, to wearmore rapidly. These components must be designed to last longer on NC machines。
Second, the addition of the electronic control unit has increased the cost of the machine,therefore requiring higher equipment utilization.
Instead of running the machine on only one shift, which was the convention with manuallyoperated machines, NC machines are often operated two or even three shifts to obtain therequired payback.
Also, the NC machines are designed to reduce the time consumed by the non-processingelements in the operation cycle, such as loading and unloading the workpart, and changingtools.
Third, the increasing cost of labor has altered the relative roles of the operator and themachine tool. Consider the role of the human operator.
Instead of being the highly skilled worker who controlled every aspect of the part production,the tasks of the operator have been reduced to part loading and unloading, tool changing, chipclearing, and the like. In this way, one operator can often run two or three automatic machines.The role and functions of the machine tool have also changed.
NC machines are designed to be highly automatic and capable of combining several operationsin one setup that formerly required several different machines. These changes are bestexemplified by a new type of machine that did not exist prior to the advent and development ofnumerical control: the machining center. 数控需要设计成高度自动化具有需要在不同车床加工
The machining center, developed in the late 1950s, is a machine tool capable of performingseveral different machining operations on a workpart in one setup under program control.
加工中心是在20 世纪50 年代发展起来的具有在程序控制下在一个工件上一次裝夹完成几种不同的加工能力的机床。
The machining center is capable of milling, drilling, reaming, tapping, boring, facing, and similaroperations.