Parts are the basic elements that make up the machine, and are the inseparable individual parts that make up the machine and the machine.
Parts are not only a discipline for the research and design of mechanical basic parts in various equipment, but also a general term for parts and components.
The research and design of mechanical basic parts in various equipment is also a general term for parts and components. The specific content of parts as a discipline includes:
1. The connection of parts (parts). Such as threaded connection, wedge connection, pin connection, key connection, spline connection, interference fit connection, elastic ring connection, riveting, welding and gluing, etc.
2. Belt drive, friction wheel drive, key drive, harmonic drive, gear drive, rope drive, screw drive and other mechanical drives that transfer motion and energy, as well as the corresponding shafting zeros such as drive shafts, couplings, clutches and brakes (part.
3. The supporting parts (parts), such as bearings, cabinets and bases.
4. Lubrication system and seal etc. with lubrication function.
5. Other parts (parts) such as springs. As a discipline, parts start from the overall mechanical design and comprehensively use the results of various related disciplines to study the principles, structures, characteristics, applications, failure modes, load-bearing capacity and design procedures of various basic parts; study the theory of design basic parts , Methods and guidelines, and thus established a theoretical system of the subject combined with reality, which has become an important foundation for the research and design of machinery.
Since the emergence of machinery, there have been corresponding mechanical parts. But as a discipline, mechanical parts are separated from mechanical structure and mechanics. With the development of the machinery industry, the emergence of new design theories and methods, new materials, and new processes, mechanical parts have entered a new stage of development. Theories such as finite element method, fracture mechanics, elastohydrodynamic lubrication, optimization design, reliability design, computer-aided design (CAD), solid modeling (Pro, Ug, Solidworks, etc.), system analysis and design methodology have gradually For the research and design of mechanical parts. The realization of the integration of multiple disciplines, the integration of macro and micro, the exploration of new principles and structures, the use of dynamic design and design, the use of electronic computers, and the further development of design theories and methods are important trends in the development of this discipline.
Surface roughness is an important technical indicator that reflects the microscopic geometric shape error of the surface of the part. It is the main basis for testing the surface quality of the part; whether it is selected reasonably or not is directly related to the quality, service life and production cost of the product. There are three methods for selecting the surface roughness of mechanical parts, namely, calculation method, test method and analogy method. In the design of mechanical parts, analogy is commonly used, which is simple, rapid and effective. The application of analogy requires sufficient reference materials, and various existing mechanical design manuals provide more comprehensive materials and documents. Commonly used is the surface roughness that is compatible with the tolerance level. Under normal circumstances, the smaller the dimensional tolerance requirements of mechanical parts, the smaller the surface roughness value of mechanical parts, but there is no fixed functional relationship between them.
For example, the handles on some machines, instruments, handwheels, sanitary equipment, and food machinery are modified surfaces of certain mechanical parts. Their surfaces are required to be processed smoothly, that is, the surface roughness is very high, but their dimensional tolerances are very demanding. low. In general, there is a certain correspondence between the tolerance level and the surface roughness value of the parts with dimensional tolerance requirements.