This paper addresses the issue of over-constrained assembly in mechanical designs using hole-pin patterns. When two hole-pin pairs are used, they can cause interference between components, leading to assembly failures. To mitigate this, designers often enlarge holes relative to pins to have a large float. However, when functional requirements do not permit significant float, field design engineers tend to add more assembly features, hoping them to mutually limit the float allowed by others. This numerical study employed two commercial tolerance analysis programs to demonstrate that these design changes could not sufficiently reduce float to justify added costs. Instead, this paper proposed an exactly-constrained design by replacing one of the holes with an elongated hole. Numerical analysis showed that this approach significantly reduced float compared to current design practices. This paper logically explains why this must be the case. It is hoped that this study contributes to the advancement of mechanical assembly design practices by adopting the exact constraint concep.

The Steer-by-Wire (SbW) system is a system that eliminates the physical connection structure of the steering system. Instead, it steers the tires through electrical communication that transmits the driver’s intention to the motor. However, the SbW system poses a significant risk in the event of a system failure. This highlights the need for effective failure backup strategies.In our study, we propose a new estimation technique. This technique accurately predicts the magnitude of the front wheel steering angle, which is determined by the vehicle motion. This prediction is particularly useful when rear wheel steering and differential braking are applied to facilitate vehicle steering in the event of a fatal SbW system failure. The estimation model is derived based on the single track model. To construct the prediction model using only measurable states, we replaced the side slip angle with the lateral acceleration signal. Additionally, we incorporated compensation for changes in cornering stiffness due to differential braking. This enhances the accuracy of the model. We validated the proposed steer angle estimation model in a virtual environment using CarSim SW and MATLAB/Simulink.

The robot industry has greatly improved over the past 50 years. It is expected that in the era of the 4th industrial revolution the field of applying robots will expand. Motors are essential in order to operate and control robots. However, robots’ precision requires the application of robot reducers. In particular, many types of harmonic drive reducers have been applied to robots. Harmonic drive reducers have theoretically zero-backlash, but they actually exist for tolerances of Oldham coupling parts. In this paper, dynamic analysis adapted dimensional tolerances of oldham coupling was used to figure out the system backlash characteristics of harmonic drives.

The automobile horn system is an essential part that produces sound for safety reasons. Production of horn system is classified based on two main processes. One of them is the caulking process which makes body assembly and forms the lower part of the horn system. The control dimension of body assembly is a crucial factor for quality control as the sound of the horn is largely determined by the control dimension. In this paper it has been found that plastic deformation of body and its restoration after caulking process is the main reason for the change in control dimension. Typically, 100 specimens of the body assembly were employed and the results were compared (Restore the Length of the Body) with another data set that had the same body but different parts in the assembly. Monte carlo simulation was used for tolerance analysis of control dimension for the body assembly including the deformation of the body in the caulking process. The simulation was identified as a good model to predict the satisfaction ratio of the control dimension with high accuracy and was observed to be useful in designing parts of the assembly and equipment used in the caulking process.

The manufacture of BLAC motor requires the motor stator (electric steel plate) and the motor case (aluminum die casting material) maintain strong contact to support the resistance of rotating moments against the rotational moments of the rotor. If there is small reverse rotational moment, the motor stator rotates easily, and damages the motor. To prevent a strong reverse rotational moment, interference fit between the motor stator and the motor case manufactured through heat shrinkage is required. This study, considers the tolerances that may occur in the manufacturing process of assembling stator and case, the contact pressure range that can occur in the heat shrinkage and the moments that can be supported by the motor stator. These are verified through the finite element analysis. The result validates finite element analysis as compared with theoretical values.

In order to help design engineers to adopt the Geometric Dimensioning & Tolerancing (GD&T), this paper develops a stepby-step method for tolerance design based on the function of the product and its parts. The procedure of this method consists of (1) analysis of functions using Key Characteristics (KC) and Datum Flow Chain (DFC), (2) selection of datum features, and (3) the selection of geometric tolerance types based on the functions. The rules and guidelines for the two latter steps are given and explained in detail, in order that the design engineer can understand the reasons for the rules and use them effectively. The method presented in this paper differs from other previous work, as it is based on the functions, whereas we note that previous work typically focuses on the automation of the tolerancing task without due consideration of functions. The paper also illustrates the developed method through two case studies: an axle-wheel assembly model and a simplified refrigerator model. This geometric tolerance design method is not complete yet in the coverage of various tolerances, e.g. size tolerances and profile, but may assist the beginning design engineer developing a mastery over GD&T.