Study On Geometric Features Of Surface Structure Of Mechanical Parts Based On Fuzzy Mathematics

The surface structure of Mechanical parts is closely related to its performance, which is an important indicator of evaluating the surface quality of mechanical parts, specially, with the development of the precision and miniaturization of modern machinery manufacturing technology, the identification and assessment of geometric features of the surface structure gets more and more attention in the field of the engineering technology and becomes the leading-edge research. In order to make the mechanical products at the leading-level in the world, researches on the geometric features of the surface structure are being conducted extensively.The machined surface of the mechanical parts is a kind of complex surface, which consists of a series of different spacing and height of the peaks and troughs with the irregular geometric shape, its geometric characteristics depend on both the surface roughness and the surface waviness. However, both of the geometric properties exist in the identical substance and their surface features vary, and also the technique factors caused by machining the two are different, for the purpose of researching and analyzing the processing techniques of surface and also the controlling and improving the product quality, the assessment and measurement of surface roughness and surface waviness has to be done respectively. However, there are the blend of the geometric components between the surface roughness and surface waviness and the fuzziness of the boundary between the two geometric parameters; the information and the correlation between the geometric parameters provided by the assessment parameters of the surface structure geometric characteristics when describing its characteristics are fuzzy; the single parameter has its unique advantages on the characterization of the different properties of the surface, and the information of the three-dimensional surface structure can reflect its actual characteristics of the machined surface better, that is to say, the single parameter and the three-dimensional comprehensive parameter are indispensable representing the performance of machined surface, but the relationship between the two is fuzzy. At present, there are the below fuzzy issues:the blend components of surface roughness and surface waviness existing in the identical surface can be entirely separated to evaluate them respectively; the assessment parameters are choosed from the parameters to indicate the geometric characteristic of the actual profile surface more accurately and perfectly (including height, spacing and shape); the single parameter information contained in the three-dimensional comprehensive can be gotten or the three-dimensional comprehensive can be gotten according to the foregone single parameter information to realize the exchange of the two. Nevertheless, the fuzzy issues only can be analyzed qualitatively, rather than quantitatively. It cannot meet the requirements to quantitatively ananlyze the fuzzy questions by the means of the traditional methods of mathematical statistic. In contrast, the new method of researching the geometric characteristics of the surface structure is put forward——which is based on the fuzzy mathematics theory to research the geometric characteristics of the surface structure.The main contents are:1. Quantitatively separate roughness from waviness of the actual surface directly adopting the fuzzy mathematics theory, get the actual values of the parameters according with the assessment quality; and analyze the correlation of the surface roughness and the surface waviness quantitatively.2. Evaluate the amplitude parameters, spacing parameters and shape parameters, etc. of the geometric characteristics of the surface structure with the method of fuzzy comprehensive evaluation based on the fuzzy mathematics theory respectively; quantitatively analyze the useful information and the correlation among the parameters provided by the assessment parameters indicating the surface characterization and the operational performance of the surface structure, confirm the correlation and the operational performance among the assessment parameters.3. Propose a new weighting method-the weighted method of the fuzzy clustering analysis, the values of roughness parameters measured are weighted, the weight makes the three-dimensional integrated parameter information and the single parameter information exchange by the fuzzy comprehensive evaluation successfully. The established fuzzy comprehensive evaluation and the fuzzy cluster analysis model are adopted by C #. NET language and the software program have been developed successfully. It is proved to obtain the satisfying results by experiments.4. Measure the surface roughness by the optical-type light scattering method, the collimating optical fiber sensors is proposed. The measurement system is seldom influenced by the distance change measured and the environment light, in particular, it basically eliminates the affect that light intensity fluctuations have on the output results. Experiments show that the results obtained accord with the light scattering theory proposed by P. Beckmann and other experts.The paper is based on the fuzzy mathematics theory to quantitatively separate the blend components of surface strcture geometric features from the actual surface directly, also to the correlation of the single parameters and the correlation of the single parameter and the three-dimensional comprehensive parameter of the assessing parameters, it breaks the traditional methods completely and solves the fuzzinees problems which can not be solved by the means of the traditional methods of mathematical statistic. The analysis method not only applies to the measuring field, but also has universal meaning to other scientific fields, and the established mathematical models and the software programs have a wide range of practical value.