Papers by Keyword: Turning Process

Abstract: Many of the previous studies on cutting properties have compared various steels with a same heat treatment, and there are almost no studies that focus on the differences in heat treatments of a same material. In this report, the influence of different heat treatments on tool wear of high-carbon steel (C55) is experimentally investigated in turning process. This study focused on three heat treatments: quenching and tempering, normalizing, and spheroidization annealing. We divided flank wear into 3 areas (corner, middle area and groove wear) for observation and analyzed each characteristic. It is found that for C55, regardless of heat treatment types, wear at the corner of the insert tip is highly dependent on cutting speed, whereas the dependence is lower where it is far away from the corner. This result is considered to be due to the adhesion that occurs while cutting. Therefore, selecting the cutting speed that minimizes flank wear at the corner can control tool wear and extend tool life. In terms of real-time monitoring for tool replacement, the correlation coefficient between the flank wear and the sensing data (spindle current, feed-axis servo motor current, and cutting sound) is also considered to depend on the adhesion condition at the insert tip. If adhesion occurs, the correlation coefficient is not stable and it’s likely to be difficult to predict wear trend to check the end of a tool life. Adhesion makes tool wear prediction using the sensing data difficult.

Abstract: The variable pitch twin-screw vacuum pump has more advantage than the uniform pitch twin-screw vacuum pump. Its energy efficiency and volumetric compression ratio are specifically high. Under the cyclic gas pressure and working temperature, the rotors of vacuum pump often deform and interfere that lead to noise, vibration and rotor abrasion. In this paper, a 3D model of the variable pitch rotor generating by CNC turning process is constructed to reasonably estimate the rotor load and deformation in operation. The contact force have been analyzed to show the advantages of variable pitch rotors.

Abstract: The twin-screw vacuum pump is widely used in low and medium-low vacuum applications. Its core element consists of a pair of rotors rotating in opposite direction on parallel axes. Screw rotors with uniform pitch are usually finished by the form grinding method, but the rotors with variable pitch are not. In this paper, a manufacturing process for generating the tooth profile of the screw rotor with variable pitch by CNC lathe turning is proposed. The initial position of turning tool and normal profile error of the manufactured screw rotors are derived and verified numerically. Numerical examples are presented to validate the proposed method. The simulation results reveal that the proposed CNC turning process is feasible and flexible.

Abstract: In this paper, there is an attempt to monitor and evaluate machining parameters when turning 34CrNiMo6 material under different cooling and lubrication conditions. The machining parameters concerned are temperature of the cutting tool and the workpiece, level of vibrations of the cutting tool, surface roughness of the workpiece, noise levels of the turning process and current drawn by the main spindle motor. Four different experimental machining scenarios were completed, specifically: conventional wet turning process, dry cutting and two additional modes employing cooling by cold air. Experimental data were acquired and recorded by an optimally designed network of sensors. Experimental data were statistically analyzed in order to reach conclusions. According to the research that has been done, although, overall, minimum cutting tool and workpiece temperatures were observed under wet machining, cold air cooling is capable of achieving comparable cooling results to wet machining. The lowest values of surface roughness were achieved by wet machining, whereas the lowest level of cutting tool vibrations were observed under cold air cooling.

Abstract: The paper presents the simulation model of turning the process of C45 non-alloy steel with a tool made of carbide insert. A 3D final element model used a lagrangian incremental type and re-meshing chip separation criterion was experimentally verified by measure cutting forces using piezoelectric dynamometer. In addition, stresses and temperature in the tooltip were predicted and examine. This work could investigate failure the tooltip, which would be great interest to predict wear and damage of cutting tool.

Abstract: Design of Experiments is employed to study the stimulus of cutting parameters such as feed rate, spindle speed, depth of cut in the turning operation of AISI-310 and optimizing the value of those parameters for getting the higher material removal rate (MRR) and minimal surface roughness. A prediction model has been developed by using the above influencing parameters. For the purpose of parameters optimization we investigate the parameters using Response Surface Methodology (RSM). It is shown that feed rate is the main parameter in influencing the surface roughness, which is being followed by spindle speed and depth of cut. It is found that surface roughness and feed rate were directly proportional to each other for some extent. The confirmation tests were carried out to with the optimum set of parameters and are verified with test results. The comparison of above two results were found to be good with maximum error within 5% on comparing it with the predicted model.

Abstract: In machining operation, the quality of surface finish is an important requirement for many turned work pieces. cutting temperature is one of the most important parameters in determining the cutting performance and tool life. the objective for this work is to estimate the cutting temperature in 3D model on tool-chip interface and the interface temperature during turning process, using the digital simulation software COMSOL Multiphysics.The tool–chip interface temperature results obtained from experimental results by using C45 medium carbon steel work piece with natural contact tools, without the application of cooling and lubricating agents and a K type thermocouple technique was used for estimating cutting temperatures in a turning operation.This procedure facilitates the determination of the temperature at tool-chip interface in dry turning process, which is still a challenge for existing experimental and numerical methods.

Abstract: The paper presents a method which combines experimental and theoretical approach, to derive an expression for estimating the power of thermal source in a turning process. This method uses a finite element mesh overlapped on infrared images (obtained from the cutting process), in order to extract the nodal temperatures corresponding on. A reverse formulation for a finite element analysis is used, knowing the nodal temperatures and boundary conditions, and deriving the thermal load which produces the measured thermal distribution. This experiment has concentrated to allied steel.

Abstract: The paper presents the method basing on engineering knowledge and experience for adding selection of cutting tools and parameters in a turning process. In this method, the system is built basing on a hybrid architecture that combines an advisory system and the CBR (Case Based Reasoning) method. It is presented the structure of the advisory system, and the functioning of the CBR method. Attention has been paid to the problem of an “empty database” in relation to systems basing on the CBR method. The paper also presents the possibility of integrating the developed method with a CAM system.

Abstract: In this paper, we comparatively present two heuristics search methods – Simulated Annealing and Weighted Sum Genetic Algorithm, in order to find optimal cutting parameters in turning operation. We consider five different constraints aiming to achieve minimum total cost of machining. We developed a customizable software application in Microsoft Visual Studio with C# source code, flexible and extensible that implements the optimization methods. The experiments are based on real data gathered from S.C. “Compa” S.A Sibiu, a company that manufactures automotive components and targets improving of product quality and reducing cost and production time. The obtained results show that, although the Weighted Sum Genetic Algorithm does not guarantee the optimality of finals solution despite of a high probability to be, it is superior to that provided by Simulated Annealing.