| Complex ring structure product is widely used in modern life, with rotation symmetry characteristics generally. Considering common characteristics of the product, as well as the special requirements of the function,the quality evaluation methods for complex ring structure product should be different from sheet metal parts or the other parts. Geometric tolerance such as circularity, parallelism, angular distribution uniformity and etc. are the quality evaluation objects in control. When considering the geometric tolerance, the size of the measuring point and function dimension in the ring-parts'quality evaluation system is very huge, which leads to low measuring efficiency. At the same time, the geometric tolerance factor is less consider in traditional deviation analysis, there have no viable deviation analysis system at present. In the actual production process, it is difficult to achieve pre-production batch product quality prediction and fault diagnosis.Because of the particular object of the ring structure products,This paper firstly deduce the position stability and position degree of freedom restrictions of the ring part;Then provide a theoretical support for ring component locating optimization. proposes a polar-coordinate based model which is non-coupling.The connective calculated results and geometric tolerance can establish a model to calculate the key geometric tolerance. We secondly compare the polar-coordinate based model with the ordinary one in practical application and obtained good result.The main work of this thesis is as follows:1 ) Propose locating quantify characterization method for the assembly process of complex ring structure product, which offers theoretic basis for locating methods optimization. Referring to determinacy locating fixture deviation model, the author deduces stability expression for locating system; introduces freedom degree and restrictiveness from robotics into locating system analysis, and deduces locating Jacobi matrix morbidity expression. Based on the above two locating quantity characterization parameter, the author conducts case study for locating methods optimization of ring structure product.2)Considering the functional feature, the author build a determinacy locating deviation analysis model under polar coordinate system for complex ring structure product.By applying polar coordination system, the author improves the traditional determinacy locating deviation analysis model for avoiding the deviation in the deviation transformation between linearity deviation and direction deviation, which is created by both couple relationship between coordination system and locating method and mathematical computation for coordination transformation. This improvement simplifies model input operation and improves deviation analysis computing efficiency.3)Propose a new morpheme error expressionPropose circular degree computational model and facial angle deviation computational model under polar coordination system, which can compute the radical and angle deviation of measure point based on complex ring structure product deviation analysis system under polar coordination, evaluate morpheme error such as circular degree, parallelism degree, uniformity degree of support plate angle, and son on, the computational model can connect deviation analysis model and morpheme error evaluation system.4)Deviation analysis case study on large-scale thin ring castingConduct whole process deviation analysis for a certain large-scale thin ring casting wax assembly, optimize wax locating method, design and optimize wax measure point and functional dimension, compute radial and angular deviation of key measure points, and evaluate flange circular degree and support plate angular uniformity of large-scale thin ring casting assembly process. The analysis results shows that the model proposed in this thesis can offer very well deviation zone predict and rapid fault diagnosis, which can improve quality evaluation efficiency of engineering ring product. |
PDF Full Text Request