《机械专业外语》课程习题集
一、短文翻译(英译汉)
1. The solution to most design problems does ari from a t of equations, instead it is a compromi to satisfy a number of design requirements and practical limitations such as available tooling and rvicing ea. Designs are often revid to introduce new features, but as much as possible of the old design is retained for economic reasons. Producing a revid design is usually not as difficult as producing a new design becau the history of the original is available for evaluation.广州卫生学校
鸡翅煎多久能熟2. When cutting screw threads, power is provided to the gearbox of the apron by the lead screw. In all other turning operations, it is feed rod that drives the carriage. The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron. When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is feed , together with the carriage along the bed.
3. Generally, grinding is considered to be a finishing process that is usually ud for obtaining high-dimensional accuracy and better surface finish. Grinding can be performed on flat, cylindrical, or even internal surfaces by employing specialized machine tools, which are referred to as grinding machines. Obviously, grinding machines differ in construction as well as capabilities, and the type to be employed is determined mainly by the geometrical shape and nature of the surface to be ground. 任务栏不见了-e.g. cylindrical surfaces are ground on cylindrical grinding machines.
4. The dielectric rves to concentrate the discharge energy into a channel of very small crossctional area. It also cools the two electrodes, and flushes away the products of machining from the gap. The electrical resistance of the dielectric influences the discharge spark energy and time of spark initiation .if the resistance is low , an early discharge spark occurs. If it is large the capacitor will attain a higher value charge before the discharge spark occurs.古拉加斯
5.秦淮河畔 As we previously saw, CNC,DNC and computer-assisted part programming are differe
nt kinds of preplanned computerized control of machine tools. In all cas, the tool path has to be established beforehand through a program, the person who prepares the programs employs his or her experience in order to bring the processing time to minimum and not to cau any damage or distortion to the workpiece. This is, in many cas, a difficult problem that involves many factors, alternatives, and constraints. Obviously, this is exactly where an expert system is needed.
6. Equipment productively is improved becau of the better utilization of machines when CIM is implemented. We can e that factors like program ability of equipment and computerized monitoring and control of the whole manufacturing facility would largely improve the efficiency of machine utilization. Higher labor and equipment productivity would certainly result in lower product cost.
游子呤吐司的做法7. Where loads are due to contact, a pair of equal and opposite forces occur. One force acts as an external load on one contacting member. This action-reaction force pairing is one of the basic natural laws put to practical u by engineers. Tracing the power trans
mission forces through connected machine linkages is an extremely uful visualization aid for identifying machine component loads.
8. Element design is concerned with the proper sizing of machine elements to perform a given function at some stated life criterion. Mechanical designers must also be familiar with properties of materials and machining process to achieve optimal design. In addition, designers must always contend with the question of cost. The watchword should be simplicity, since a simple device is usually the least expensive.
9. The tailstock asmbly consists basically of three parts, its lower ba, an intermediate part, and the quill. The lower ba is a casting that can slide on the lathe bed along the guideways, and it has a clamping device to enable locking the entire tailstock at any desired location, depending upon the length of the workpiece. The intermediate part is a casting that can be moved transverly to enable alignment of the axis of the tailstock with that of the headstock.
10. Internal grinding is employed for grinding relatively short holed. The workpiece is held
金融产品营销方案in a chuck or a special fixture. Both the grinding wheel and the workpiece rotate during the operation and feed is applied in the longitudinal direction. Any desired depth of cut can be obtained by the cross feed of the grinding wheel. A variation from this type is planetary internal grinding, which is recommended for heavy workpieces that cannot be held in chucks. In the ca, the grinding wheel not only spins around its own axis but also rotates around the centerline of the hole that is being ground.
