Journal of Modern Processes in Manufacturing and Production
Volume:8 Issue: 3, Summer 2019

Burnishing is a chip-less finishing process, in which a hard roller or ball presses the surface layer of part to perform plastic deformation in the surface layer and produce improved finish, enhanced hardness and compressive residual stresses on the surface of special materials such as Aluminum and Brass. In the following research, the effect of input parameters such as feed rate, cutting speed, number of passes , burnishing force and cooling system which is applying by minimum quantity of lubrication (MQL) on surface roughness and micro-hardness in roller burnishing of Aluminum alloy 6061 has been investigated. Taguchi method is used for design of experiments and special burnishing tool is used for this research. The optimization results show that the effect of feed rate and burnishing speed is significant on surface roughness and burnishing force and the number of passes plays important role in micro-hardness. The minimum surface roughness in burnishing of aluminum alloy 6061 was 0.138 μm and the maximum was 0.475 μm. The maximum micro-hardness in roller burnishing Aluminum alloy 6061was found 122 HB and the minimum was 100 HB.

Nowadays, the role of light weight materials has grown up in important industries such as aerospace and biomechanics, but before the appliance, their strength should be increased. A modern way to increase this factor along with the lightweight factoris using bimetal sheets, hence, the design of multilayer sheets has been very much considered recently. In this study, explosive welded Cu/St/Cu multilayer sheets were used in the incremental forming process to determine the springback phenomenon on different layers. The results indicated that rotational speed, feeding rate, and vertical step parameters can affect spring back in single point incremental forming process (SPIF).Three levels of vertical step size, tool rotational speed, and feed rate have been considered as the input process parameters and spring back as the output.In order to design a better experiment and analyze the data, the Taguchi method was selected on the basis of DOEin Mini-Tab software andthe results have been analyzed by two states. In the first state,the value which was closest to the nominal value is considered to be the optimal result which obtained for spring back angles with parameters of 0.75 mm for the vertical step down, 200 rpm for the rotational speed and 500 and 1000 mm/min for the feeding rate. In the second state, the least amount is considered as the optimal result in which the values of 0.5 and 1 mm of the vertical step down, 150 and 100 rpm of the rotational speed, and 1500 and 500 mm/min of the feeding rate formed the optimal outcome.

Formation of the burrs in the industrial parts after manufacturing processes such as blanking, punching, machining, cutting and etc. is inevitable. The burring phenomenon decreases the geometrical and dimensional tolerance and makes assembling parts together difficult. Radiusing the corners of workpieces is a common technique to reduce the stress concentrations at corners and also facilitate their assembly. By means of barrel finishing, a number of workpieces undergo deburring and radiusing coincidently in one process. In barrel finishing which is one of the mass finishing techniques, many workpieces with abrasive media are loaded in a rotary barrel. By rotation of the barrel, the parts and abrasive media are collided to each other and rub themselves, resulting in deburring and polishing the workpieces. The working time of this process is normally long. The aim of this study is to decrease the working time by using proper abrasive media. Here, a number of experiments is designed on combination of three abrasive media: steel balls, ceramics and aluminum oxide particles, in different working periods, to achieve appropriate radius and reducing burrs height of CK45 steel alloy samples in reduced working time.

Johnson cook constitutive equation was utilized to model the 10100 copper alloy wires at the cold wire drawing process. Johnson cook parameters were determined using several quasi-static tensile tests at different strain rates. The wire drawing experiments carried out at seven drawing conditions with two areal reductions and four drawing speeds caused the strain rate ranged from 37 to 115 s-1. Wire Drawing forces were measured using a load cell connected to the die. Analytical and finite element with VUHARD subroutine solutions were implemented to calculate the drawing forces using the Johnson cook parameters as well. Results showed that the Johnson cook model with parameters determined from a quasi-static condition was not able to predict the material behavior at the wire drawing process with a moderate strain rate. Inverse analysis using the Newton- Raphson method to minimize the objective function was carried out to modify the Johnson cook parameters. Updated Johnson cook parameters showed much more correlation with experimental results.

In this research, the effects of three important input parameters of roller burnishing process, namely burnishing speed, feed rate and the number of passes on the surface integrity (surface roughness and surface micro-hardness) of Ti-6Al-4V alloy are investigated. The design of the experiment is carried out using a full factorial method. Measurement of process outputs is carried out with precise methods and the results are recorded and examined. The results showed that the parameters studied have a very significant effect on the surface roughness and micro-hardness of Ti6Al4V alloy. The feed rate is the most effective parameter on the surface roughness and the burnishing speed is the most effective parameter on the surface micro-hardness. Generally concluded, the roller burnishing process improves the final surface quality and increases surface micro-hardness. It also concluded that increasing the number of the burnishing passes from 1 to 2 would excel both of the output parameters while increasing of this parameter further has no significant effect or; in certain cases; an inverse effect on the surface roughness and surface micro-hardness.

A comprehensive comparison between regressor-free control and direct adaptive fuzzy control of flexible-joint robots is addressed in this paper. In the proposed regressor-free controller, two critical practical situations are considered: the fact that robot actuators have limited voltages, and limitation on the number of measurement devices. However, in the article "decentralized direct adaptive fuzzy control for flexible-joint robots," these limitations have been neglected. It should be noted that a few solutions for the voltage-bounded robust tracking control of flexible joint robots have been proposed. In this paper; we contribute to this subject by presenting a new form of voltage-based controllers. The closed-loop control system stability is proved, and uniformly boundedness of the joint position errors is guaranteed. As a second contribution of this paper, we present a robust adaptive control scheme without the need for computation of the regressor matrix with the same result on the closed-loop system stability. Experimental results of the proposed controller and the decentralized direct adaptive fuzzy controller are produced using MATLAB/SIMULINK external mode control on a single-link flexible-joint electrically driven robot. Experimental and analytical results demonstrate the high performance of the proposed control scheme.