组合机床外文翻译.doc

Development and application of combined machine tool
The combination of machine tools based on general parts, workpiece supported by the specific shape and design of special processing of parts and fixtures, the composition semiautomatic or automatic special machine. Combination machine generally adopts multi shaft, knife, more processes, more or multiple locations simultaneously processes, and production efficiency ratio general machine tool high several times to several times. As generic components have been standardized and serialized, may need to be flexible configuration, can shorten design and manufacturing cycle. Therefore, the aggregate machine-tool has the advantages of high efficiency and low cost, the large, mass production to be widely applied, and can be used to compose the automatic production line. Processing, workpiece generally does not rotate, by movement of the rotatable cutter and tool and workpiece relative feed movement, to achieve drilling, reaming, counterboring, reaming, boring, milling, cutting and processing of external thread face and etc.. Some combination machine adopts clamping workpiece machining head to rotate, by the tool for the feed movement, also can achieve some rotating parts ( such as car rear axle flywheel, etc.) of the face and processing.
In twentieth Century since the 70's, along with the cutting tool with indexable inserts, dense gear milling cutter, boring size automatic detection and automatic compensation for tool technology development, combination of the machining accuracy of the machine tool is improved. Milling plane plane of up to 0.05mm and1000 mm, the surface roughness can be as low as 2.5to 0.63 microns; boring accuracy up to IT7~6, hole distance precision can reach 0.03~ 0.02 micron. A dedicated machine is along with the automobile industry development. In some parts of special machine tool for repeated use, and gradually developed into a general components, resulting in a combined machine tool. The earliest combination machine is made in the United States in 1911, for the processing of auto parts. Initially, the machine tool manufacturing plant has its own general component standard. In order to improve different factory universal interchangeability of the parts, and is convenient for users to use and repair.
The Design Process
Designing starts with a need real.Existing apparatus may need improvements in durability, efficiency, weight, speed, or cost. New apparatus may be needed to perform a function previously
done by men, such as computation, assembly, or servicing. With the objective wholly or partly
In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint., namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.
When the general shape and a few dimensions of the several components become apparent, analysis can begin in earnest. The analysis will have as its objective satisfactory or superior performance, plus safety and durability with minimum weight, and a competitive cost. Optimum proportions and dimensions will be sought for each critically loaded section, together with a balance between the strengths of the several components. Materials and their treatment will be chosen. These important objectives can be attained only by analysis based upon the principles of mechanics, such as those of static for reaction forces and for the optimum utilization of friction; of dynamics for inertia, acceleration, and energy; of elasticity and strength of materials for stress and deflection; of physical behavior of materials; and of fluid mechanics for lubrication and hydrodynamic drives. The analyses may be made by the same engineer who conceived the arrangement of mechanisms, or, in a large company, they may be made by a separate analysis division or research group. Design is a reiterative and cooperative process, whether done formally or informally, and the analyst can contribute to phases other than his own. Product design requires much research and development. Many Concepts of an idea must be studied, tried, and then either used or discarded. Although the content of each engineering problem is unique, the designers follow the similar process to solve the problems.
Machinery design covers the following contents.
1. Provides an introduction to the design process , problem formulation ,safety factors.
2. Reviews the material properties and static and dynamic loading analysis ,
Including beam , vibration and impact loading.
3. Reviews the fundamentals of stress and defection analysis.
4. Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in the design of rotation machinery.
5. Discusses thoroughly the phenomena of wear mechanisms, surface contact stresses ,and surface fatigue.
6. Investigates shaft design using the fatigue-analysis techniques.
7. Discusses fluid-film and rolling-element bearing theory and application
8. Gives a thorough introduction to the kinematics, design and stress analysis of spur gears , and a simple introduction to helical ,bevel ,and worm gearing.
9. Discusses spring design including compression ,extension and torsion springs.
10. Deals with screws and fasteners including power screw and preload fasteners.
11. Introduces the design and specification of disk clutches and brakes.
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