جستجوی مقالات مرتبط با کلیدواژه "flatness" در نشریات گروه "مکانیک"

There is a requirement to find accurate parameters to accomplish precise dimensional accuracy, excellent surface integrity and maximum MRR. This work studies the influence of various cutting parameters on output parameters like Cutting force, Surface roughness, Flatness, and Material removal rate while face milling. A detailed finite element model was developed to simulate the face milling process. The material constitutive behavior is described by Johnson-Cook material model and the damage criteria is established by Johnson-Cook damage model. The result indicate significant effects of all three cutting parameters on MRR and both feed rate and depth of cut have significant effect on cutting force. Also, feed rate has significant effect on PEEQ and none of the parameters have effect on flatness.

In this study an experimental analysis is conducted to explore the effects of the distance placement of a trailer model on the dynamic of flow and the higher-order parameters of velocity like flatness and skeweness in the wake of a Notch back car model. In addition, the changing trends of Strouhal number and the mixed length scale are depicted. All the experiments are conducted in the aerodynamic laboratory of Hakim Sabzevari University. In order to measure the property of flow, the researchers have made use of the wind tunnel device and hot wire anemometer produced by Farasanjesh-e-Saba Company. The results indicated that the values of skewness in the lower heights (near to ground) are less than their values in the upper heights (near to roof of model) and this issue is in contrast as the distance from the car increases. The values of flatness also gradually decrease by an increase in the distance from the car. The Strouhal number often reduces by increase in the distance of car from trailer and the mixed length scale in the width of trailer often has one or two maximum peaks. The wake of trailer in positions near the car is not effective in the formation of maximum peaks of mixed length scale sites.

Lapping is one of the most important polishing processes which can be used to fabricate flat and smooth surfaces. In this paper, the effect of lapping characteristics and mesh number of abrasive particles are studied on the surface roughness and flatness for the machining of hardened AISI 52100 rings. The most significant lapping characteristics are pressure, lap plate speed and time. Scanning electron microscopy and optical microscopy are used to investigate micro cracks and surface textures. Results showed that surface roughness increased by rising the lapping pressure and plate speed. Also, reduction of the lapping time and mesh number of abrasive particles led to lower surface roughness. Application of lapping process decreased the flatness to 1.2 µm and surface roughness (Ra) from 0.58 to 0.051 µm. The lapping pressure was a significant factor on the surface roughness; and the lapping time was a significant factor on flatness. However, surface roughness increased with rising of mesh number and lapping time, and increased with decreasing the lapping pressure. The minimum surface roughness was 0.051 μm which was obtained in lapping pressure of 7 kPa, lapping speed of 0.164 m/s, time of 15 min and mesh number of 600.The flatness decreased with lapping speed, and reduced with increasing the pressure, mesh number and lapping time.