Residual Stress Prediction in Turbine Blade Machining Operations Using a Virtual Machining System

Part manufacturing process using machining operations is along with residual stress due to friction, chip formation and generated heat in cutting zone. The performance of produced parts in working conditions such as fatigue life, corrosion resistance and part distortion is under the influence of residual stress which should be analyzed and minimized. To produce compressor section blades of gas turbines, machining operations can be used. The process is always with complexities and challenges. However it can be analyzed and modified in virtual environments. Residual stress due to machining operations of gas turbine blades can also be analyzed in virtual environments in order to be minimized. In the present research work, application of a virtual machining system to predict residual stress in milling operations of turbine blades is presented. Finite element analysis is implemented in order to calculate residual stress as well as strain of blades in machining operations. In order to validate the research work, experimental results are compared with the finite element results obtained from the virtual machining system. The present research work can replace the costly experimental tests by predicting the residual stress in a virtual machining environment

Virtual Machining

Virtual machining systems apply computers and different types of software in manufacturing and production in order to simulate and model the behavior and errors of a real environment in virtual reality systems. This can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased

Virtual machining considering dimensional, geometrical and tool deflection errors in three-axis CNC milling machines

Virtual manufacturing systems can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased. There are different error sources in machine tools such as tool deflection, geometrical deviations of moving axis and thermal distortions of machine tool structures. Some of these errors can be decreased by controlling the machining process and environmental parameters. However other errors like tool deflection and geometrical errors which have a big portion of the total error, need more attention. This paper presents a virtual machining system in order to enforce dimensional, geometrical and tool deflection errors in three-axis milling operations. The system receives 21 dimensional and geometrical errors of a machine tool and machining codes of a specific part as input. The output of the system is the modified codes which will produce actual machined part in the virtual environment

Virtual machining considering dimensional, geometrical and tool deflection errors in three-axis CNC milling machines

Virtual manufacturing systems can provide useful means for products to be manufactured without the need of physical testing on the shop floor. As a result, the time and cost of part production can be decreased. There are different error sources in machine tools such as tool deflection, geometrical deviations of moving axis and thermal distortions of machine tool structures. Some of these errors can be decreased by controlling the machining process and environmental parameters. However other errors like tool deflection and geometrical errors which have a big portion of the total error, need more attention. This paper presents a virtual machining system in order to enforce dimensional, geometrical and tool deflection errors in three-axis milling operations. The system receives 21 dimensional and geometrical errors of a machine tool and machining codes of a specific part as input. The output of the system is the modified codes which will produce actual machined part in the virtual environment

Detection of Legionella pneumophila in the bronchoalveolar lavage samples by real time PCR in patients with ventilator-associated pneumonia in ICU

زمینه و هدف: لژیونلا پنوموفیلا به خاطر توانایی آن در ایجاد پنومونی ناشی از ونتیلاسیون مکانیکی مورد توجه مراکز درمانی است. هدف از این مطالعه ردیابی گونه های لژیونلا پنوموفیلا در نمونه های بدست آمده از برونکوآلوئولار لاواژ با روشReal Time PCR در بیماران بستری در بخش مراقبت های ویژه ی بیمارستان الزهرا(س) اصفهان می باشد. روش بررسی: در یک مطالعه توصیفی تحلیلی سی و نه نمونه برونکوآلوئولار لاواژ در بیماران مبتلا به پنومونی همراه با ونتیلاتور بستری در بخش مراقبت های ویژه (ICU) بیمارستان الزهرای اصفهان در سال 1390 گرفته و تا زمان آزمایش در 20- درجه سانتیگراد نگهداری شد. DNA به روش فنل کلروفرم استخراج و آزمایش Real Time PCR در 45 چرخه شامل oC95 برای 4 ثانیه و oC58 برای 30 ثانیه انجام شد. در حالی که پروب به روش Taq Man عمل می کرد. یافته ها: نتیجه برای حضور باکتری لژیونلا پنوموفیلا در همه نمونه ها منفی شد. حداقل سن افراد در مطالعه 20 و حداکثر 86 سال بوده است. مدت زمان بستری افراد مورد مطالعه در ICU حداقل 2 روز و حداکثر 65 روز است. مدت زمان ونتیلاسیون افراد مورد مطالعه حداقل 2 روز و حداکثر 65 روز بود. نتیجه گیری: این مطالعه عدم حضور لژیونلا پنوموفیلا در بیماران دچار پنومونی وابسته به ونتیلاتور در ICU بیمارستان الزهرای اصفهان رادریک مقطع زمانی نشان می دهد؛ لذا بر اساس مطالعه فوق، شناخت الگوی میکروبیولوژیک لژیونلا پنوموفیلا در سایر مراکز درمانی نیز امری منطقی به نظر می رسد

Cutting tool wear prediction in machining operations, a review

International audienceIn the machining process, tool wear is an unavoidable reason for tool failure. Tool wear has an impact on not just tool life but also the quality of the finished product in terms of dimensional accuracy and surface integrity. Tool wear is a significant element in the annual cost of machining. It happens when the tool-work contact zone experiences abrupt geometrical damage, frictional force, and heat generation. It's essential to accurately evaluate tool wear during machining so that the cutting tool can be replaced before the workpiece surface sustains significant damage. The capacity to assess tool wear is crucial for ensuring high-quality workpieces. Artificial neural network, Deep learning and Machine learning systems, heat generation analysis, image data processing, finite element method and gaussian process are used in order to accurately predict the tool wear during machining operations. In this paper, cutting tool wear prediction in machining operations is reviewed in order to be analyzed and minimized. The main purpose of the study is to provide a useful resource for researchers in the field by presenting an overview of current research on cutting tool wear prediction in machining processes. As a consequence, the research area can be progressed by reading and assessing existing achievements in published articles in order to provide new ideas and methodologies in prediction and minimization of tool wear during machining operations

Cutting Tool Path Modification to Uniform Scallop‐Height in Three-Axis Milling Operations

Scallop height, which is the uncut amount of workpiece materials in metal cutting paths, has an impact on the surface condition of manufactured products. To increase accuracy and surface quality of machined parts, the scallop height should be analyzed in order to be minimized. In this study, a virtual machining system is created to produce uniform scallop height throughout free form surface end milling. Machined surfaces are analyzed by the developed system in order to obtain the curvature of free form surfaces. Then, the machined surfaces are divided to the at, concave and convex surfaces in order to analyze and modify the cutting tool paths along milling operations. The machining parameters of step over, feed rate and spindle speed are modi ed in order to obtain uniform scallop height during milling operations of free form surfaces. As a result, the modi ed cutting tool paths can generate the uniform scallop height in order to increase surface quality of machined free form surfaces. To enhance the process of component manufacturing utilizing machining operations, the study's produced virtual machining system can raise the productivity as well as the accuracy of machined free from surfaces

Dimensional and geometrical errors of three-axis CNC milling machines in a virtual machining system

Virtual machining systems are applying computers and different types of software in manufacturing and production in order to simulate and model errors of real environment in virtual reality systems. Many errors of CNC machine tools have an effect on the accuracy and repeatability of part manufacturing. Some of these errors can be reduced by controlling the machining process and environmental parameters. However geometrical errors which have a big portion of total error need more attention. In this paper a virtual machining system which simulates the dimensional and geometrical errors of real three-axis milling machining operations is described. The system can read the machining codes of parts and enforce 21 errors associated with linear and rotational motion axes in order to generate new codes to represent the actual machining operation. In order to validate the system free form profiles and surfaces of virtual and real machined parts are compared in order to present the reliability and accuracy of the software

Minimization of Surface Roughness and Residual Stress in Grinding Operations of Inconel 718

The residual stress and surface roughness enhancement of ground surfaces can decrease the lifetime of workpiece by reducing its fatigue life. It is critical to accurately predict and minimize the residual stress and surface toughness of ground surfaces in order to enhance efficiency of part production using grinding operations. A virtual machining system is developed in the research work to minimize the surface integrity and residual stress during grinding operations of Inconel 718. The cutting temperature during grinding operations is calculated using the Inconel alloy Johnson Cook law models. Then, using the finite element method, residual stress during the grinding operation is estimated. Utilizing the established virtual machining method, the surface roughness is predicted in the study. Using the Taguchi optimization approach, the grinding parameters of depth of cut and feed velocity are optimized in order to reduce surface roughness as well as residual stress throughout grinding operations on Inconel 718 Superalloy. To confirm the effectiveness of the developed technique in the study, simulation and experimentation are conducted. As a result, the quality as well as reliability of the ground surfaces can be enhanced by using the developed virtual machining system in the study to minimize the surface roughness and residual stress of produced parts using grinding operations.The residual stress and surface roughness enhancement of ground surfaces can decrease the lifetime of workpiece by reducing its fatigue life. It is critical to accurately predict and minimize the residual stress and surface toughness of ground surfaces in order to enhance efficiency of part production using grinding operations. A virtual machining system is developed in the research work to minimize the surface integrity and residual stress during grinding operations of Inconel 718. The cutting temperature during grinding operations is calculated using the Inconel alloy Johnson Cook law models. Then, using the finite element method, residual stress during the grinding operation is estimated. Utilizing the established virtual machining method, the surface roughness is predicted in the study. Using the Taguchi optimization approach, the grinding parameters of depth of cut and feed velocity are optimized in order to reduce surface roughness as well as residual stress throughout grinding operations on Inconel 718 Superalloy. To confirm the effectiveness of the developed technique in the study, simulation and experimentation are conducted. As a result, the quality as well as reliability of the ground surfaces can be enhanced by using the developed virtual machining system in the study to minimize the surface roughness and residual stress of produced parts using grinding operations.The residual stress and surface roughness enhancement of ground surfaces can decrease the lifetime of workpiece by reducing its fatigue life. It is critical to accurately predict and minimize the residual stress and surface toughness of ground surfaces in order to enhance efficiency of part production using grinding operations. A virtual machining system is developed in the research work to minimize the surface integrity and residual stress during grinding operations of Inconel 718. The cutting temperature during grinding operations is calculated using the Inconel alloy Johnson Cook law models. Then, using the finite element method, residual stress during the grinding operation is estimated. Utilizing the established virtual machining method, the surface roughness is predicted in the study. Using the Taguchi optimization approach, the grinding parameters of depth of cut and feed velocity are optimized in order to reduce surface roughness as well as residual stress throughout grinding operations on Inconel 718 Superalloy. To confirm the effectiveness of the developed technique in the study, simulation and experimentation are conducted. As a result, the quality as well as reliability of the ground surfaces can be enhanced by using the developed virtual machining system in the study to minimize the surface roughness and residual stress of produced parts using grinding operations.</p