Interference fits are commonly used in engineering for various applications. Optimum machining parameters were determined as 1.5 mm depth of cut, 0.1 mm/rev feed rate and 250 rpm cutting speed. The SEM images derived from chips proved that the feed rate has strong correlation with surface roughness. According to the ANOVA results, it was determined that the most effective parameter is the feed rate with 93.78% on surface roughness in the turning of the train wheel.
Experimental results were examined visually by using chip photographs and SEM images. In the experimental study, the Taguchi experimental design method, regression analysis and variance analysis (ANOVA) method were used. In this study, different depth-of-cut, feed rate and cutting speed parameters were considered in the turning process of ER8 class train wheel, and optimum machinability parameters were determined.
The surface roughness of the inner diameter of the wheel must be within 0.8–3.2 μm in order to provide the optimum shrink-fit. For this reason, it is of great importance for the safety of rail transportation that the wheel-axle assembly is carried out securely through the shrink-fit method. The train wheel is one of the elements most exposed to static and dynamic loads during the transport. To this end, this paper presents two independent experimental apparatus designed to measure the pressure dependent coefficient of friction and thermal contact conductance between typical housing and electrical steel materials under in-service conditions. However, these parameters are influenced by many factors including interface pressure, surface preparation and temperature, and are therefore difficult to predict unless experimental methods are adopted. The optimal design of such a shrink-fit represents a multi-physics problem requiring, among other data, accurate coefficient of friction and thermal contact conductance information. As the stator-housing interface lies in the main heat extraction path, an ideal shrink-fit should provide the necessary holding torque, present minimal thermal contact resistance and remain mechanically and thermally stable over the operating temperature range and life of the electrical machine. The shrink-fitting of housings on to electrical machine stators is a common, semi-permanent and low-cost method of assembly. In addition, the phenomenon of increased holding torque with loading cycle number is observed experimentally, and areas where further work needs to be conducted in order to model the situation using frictional and plastic shakedown are outlined.
The probabilistic results of a micromechanical approach are presented which show good comparison with experimental results, indicating that current design formulae are inadequately predicting holding torque. This paper examines the validity of this approach and a variant, which takes into account surface roughness conditions of the interfacing components, by comparing statistical distributions of the holding torque with those found experimentally for a sample of a particular shrink-fit configuration. The traditional approach to determine the holding torque of a shrink-fit is based on Lame's equation to predict radial pressures at the interface of the components and knowledge of the coefficient of friction and length of contact.
A shrink-fit is a semi-permanent assembly system that can resist the relative movement or transmit torque between two components through the creation of high radial pressures at the interface of its constituent parts.
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