Tolerance Geometrical Interference Analysis of Specific Movement Mechanism Under Thermal Strain

Abstract

In sensitive mechanisms, achieving the required accuracy of the final parts at the most suitable price is a complex process. The tolerance design process is essential in design and manufacturing to achieve a quality and low-cost product. Allocation of appropriate tolerances is always time-consuming and challenging, especially for complex products, as it involves many aspects of design, manufacturing, and quality issues. In this research, a program has been written in MATLAB, in which by only one geometry model, all possible interferences of assembled parts for all tolerances and nominal sizes in different production modes have been investigated. By using this program, it is possible to add or reduce applied tolerances to nominal sizes and check the interference of parts for all tolerances. Also, temperature effects must be considered when designing a product that operates in a wide temperature range. This approach could ensure that the values of the output parameters of the mechanism remain stable with various temperature changes. The considered case study is particular clock whose structural parameter tolerances often significantly affect the accuracy of the timing output of the entire movement of the mechanism in the program; the tolerance of the parts of the delay clock mechanism has been studied. By analysing the tolerance of geometric non-interference and considering the strain of the parts due to the operating temperature of the mechanism, 24% of the examined sizes should be reduced to avoid interference and the tolerance of the axis position of the clock should be reduced to ±0.01.

Keywords

• geometric interference analysis
• mechanism
• operating temperature range
• operational tolerance
• tolerance analysis