Influence of Machining Errors on the Quality of Straight Round Flexible Hinges_Hinge Knowledge_Talls

The flexible hinge is a mechanical component that utilizes the micro-elastic deformation and recovery characteristics of metal. It is a high-resolution transmission mechanism that allows for precise positioning and fine-tuning. It is commonly used in devices such as precision positioning platforms, photolithography equipment, and scanning detection microscopes.

There are several factors that can affect the performance of flexible hinges. When designing flexible hinges, some assumptions are made, such as assuming that only elastic deformation occurs at the hinge and that the rest of the structure is rigid. It is also assumed that only corner deformation occurs during operation, without any expansion or other deformations. However, the hinge itself has inherent defects, such as the center of rotation not being fixed, stress concentration, and stress magnitude changes with the position of the joint. The material properties and environmental factors can also impact the performance of the hinge.

In structural design, the combination of multiple hinges and connecting rods is common. However, the processing errors between these combinations can lead to coupling displacement of the corners and straight lines, causing the motion of the mechanism to deviate from the desired path. There have been comprehensive analyses of the error sources in flexible hinge mechanisms, including discussions on material performance, size design, vibration, interference, machining errors, etc. These analyses aim to understand the sensitivity of each variable error on the performance of the flexible hinge.

Previous research has used methods such as the Taylor series expansion, finite element method, and numerical simulations to study the displacement mechanisms and coupling caused by manufacturing errors in flexible hinges. However, most of these studies focused on individual mechanisms and had certain limitations in terms of the scope and results obtained.

This paper focuses on the analysis of three machining errors in straight circular flexible hinges: the positioning error of the incision arc in the y direction, the positioning error of the incision arc in the x direction, and the perpendicularity error of the center line of the arc axis. The stiffness calculation formulas for each type of error are derived, and the results are validated using finite element analysis (FEA). This research provides valuable insights into the parameter design and processing of hinges.

To conduct the analysis, a cantilever beam structure model is established using ANSYS software. Different design points are obtained by modifying the error parameters, and simulation calculations are carried out on these design points to obtain the stiffness errors. The results obtained from numerical analysis and finite element analysis are compared and found to be in good agreement.

The results show that the errors in the positioning of the incision arc in the y direction and the perpendicularity of the axis line have a significant impact on the stiffness of the flexible hinge. The errors in the positioning of the incision arc in the x direction have a smaller influence. Based on these findings, it is recommended to strictly control the positioning errors in the y direction and the perpendicularity of the axis line, while also considering reducing the value of t/R to minimize the impact of positioning errors in the x direction.

In conclusion, this research provides a comprehensive analysis of the machining errors in straight circular flexible hinges and their impact on stiffness. The derived stiffness calculation formulas and the validation using finite element analysis contribute to the understanding of hinge parameter design and processing. Further research can be conducted to explore other types of machining errors and their effects on the performance of flexible hinges.