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Showing 2 results for Geometric Tolerances
Saeed Khodaygan, Hamed Fallahzadeh,
Volume 17, Issue 8 (10-2017)
Abstract
Because of increasing demands for using of rotating systems in high accuracy and high speed applications, in addition of specific condition of rotating systems, it is necessary to analyze these rotating systems characteristics. Tolerance analysis is a useful tool for estimating effects of dimensional and geometrical errors of effective parameters on functional characteristics in a mechanical system. Unlike other mechanical systems, in addition to the dimensional and geometrical errors, the accuracy of the rotary systems performance directly depend on the flexibility of parts and Non Repetitive Run-Out (NRRO) errors. In this paper, a new method is proposed for static and dynamic tolerance analysis of the rotary systems with the dimensional and geometrical errors, the flexibility effects, and the NRRO errors based on the tolerance zone model. First, using the small degrees of freedom concept, the dimensional and geometrical errors and the NRRO error are modeled in the tolerance zone. Then, based on a new strategy, the performance -assembly functions of the system for modeling the error propagation of the rotary system in the static and dynamic conditions are extracted. Then, using the proposed equations, sensitivities of the requirements such as the end of shaft position and the main natural frequency to tolerances are computed. To illustrate applicability of the proposed method, a rotary system is considered as a case study. Monte Carlo simulations are used for validation of the computational results from proposed method.
S. Haji Zahedi , B. Moetakef-Imani ,
Volume 20, Issue 3 (2-2020)
Abstract
With the advancement of the manufacturing processes and the continuing need for increasingly precise assemblies, consideration of dimensional and geometric tolerances has been of great importance in tolerance analysis of mechanical assemblies. Therefore, in recent decades, several methods have been developed and implemented for calculating the influences of geometric errors of components on the final performance of the assembly. One of the proposed methods for tolerance analysis is the Direct Linearization Method (DLM). However, DLM has significant advantages in dimensional tolerance analysis, due to simplifications used in this technique, it does not have the ability to solve assemblies including free form profiles. In this research, a new method has been proposed to consider the complex profiles in the process of DLM. In the proposed combination method, rational Bezier curves have been used to define component profiles such as elliptical profiles, cams, edge joints, and non-circular profiles that have a complex error variation. Then, by using principles of DLM and rational Bezier equations, the developed algorithm is successfully accomplished. In this way, we can not only use significant advantages of DLM in dimensional tolerance analysis but also it is possible to solve assemblies including a component with complex profiles without any simplification. The developed hybrid approach has been presented in detail by solving an example of assembly tolerance analysis. Finally, validation has been performed and the accuracy of the proposed approach was confirmed using Monte Carlo simulation.
