Dynamic Behavior of Long Turned Workpieces

2014 ◽  
Vol 657 ◽  
pp. 78-82 ◽  
Author(s):  
Neculai Eugen Seghedin ◽  
Mihăiţă Horodincă ◽  
Dragos Chitariu ◽  
Radu Drosescu

One of the most important parameters used in the evaluation of machining technological systems is the dynamic quality, represented by the system stability and the specific feature of the reaction to the external factors, during the machining process. The dynamic quality of the machining system is given by the dynamic quality of the machine tool, cutting tool, cutting tool holding device, workpiece fixture. The dynamic behavior of the machining system is given by the behavior of the elastic subsystem of the workpiece and tool. In the case that the deformation of the machine tool is negligible in relation with the two subcomponents of the technological system, mentioned, these can be studied separately. It is important to determine which is the weakest link of the technological system or to determine which is the component that can lead to the loss of the stability of the entire system. In the paper it is studied the dynamic behavior of the turned long, flexible workpieces. The workpieces are clamped in the lathes chuck and in the tailstock. The natural vibrational frequencies are determined according to a series of parameters as the diameter of the workpieces, axial forces applied by the tailstock.

2020 ◽  
Vol 51 (8) ◽  
pp. 1170-1179
Author(s):  
Z. Murčinková ◽  
K. Vasilko ◽  
J. Živčák ◽  
J. Murčinko

Author(s):  
Frédéric Cugnon ◽  
Luke Berglind ◽  
Denys Plakhotnik ◽  
Mikel Armendia

This paper focusses on the dynamic modeling of the machine tool including its Computer Numeric Control (CNC), and its interaction with the machining process. To properly simulate modern machine tools in machining condition, which show close interaction between the dynamic behavior of the mechanical structure, drives, and the CNC, we use an integrated methodology that combines control and MBS capabilities in a nonlinear FEA solver called SAMCEF Mecano. To fully capture the dynamic behavior of the machine, force interactions between the cutting tool and the workpiece are also considered. A strong coupling between the mechatronic model of the machine tool and a machining simulation tool is implemented. A specialized cutting force element has been developed. It considers the dynamics of the tool tip combined with the tool workpiece engagement to generate cutting forces. The use of such digital twin model is demonstrated considering some industrial machining operations.


2016 ◽  
Vol 686 ◽  
pp. 174-179
Author(s):  
Zuzana Murčinková ◽  
Karol Vasilko

The paper analyzes static stiffness of technological system machine tool - cutting tool - workpiece as one of factors affecting machined part accuracy. It focuses on turning and milling and their tool and workpiece characteristics as size, geometry, stiffness, tool wear, clamping etc. The paper identifies inaccuracies as a result of deformation of elastic component joints during acting the cutting and clamping forces. The paper provides final shapes and its deviations from ideal shape. The analysed results are obtained either by numerical simulation or by experiment. Finding the deviations generating mechanisms, it is possible to link dimensional, geometric and surface accuracy of workpiece to specific elements of technological system that is the significant point of the machine and tool design.


Author(s):  
Xiao-Jin Wan ◽  
Cai-Hua Xiong ◽  
Lin Hua

In machining process, machining accuracy of part mainly depends on the position and orientation of the cutting tool with respect to the workpiece which is influenced by errors of machine tools and cutter-workpiece-fixture system. A systematic modeling method is presented to integrate the two types of error sources into the deviation of the cutting tool relative to the workpiece which determines the accuracy of the machining system. For the purpose of minimizing the machining error, an adjustment strategy of tool path is proposed on the basis of the generation principle of the cutter location source file (CLSF) in modern computer aided manufacturing (CAM) system by means of the prediction deviation, namely, the deviation of the cutting tool relative to the workpiece in computer numerical control (CNC) machining operation. The resulting errors are introduced as adjustment values to adjust the nominal tool path points from cutter location source file from commercial CAM system prior to machining. Finally, this paper demonstrates the effectiveness of the prediction model and the adjustment technique by two study cases.


2014 ◽  
Vol 903 ◽  
pp. 252-258
Author(s):  
Paul Helmut Nebeling

This paper introduces some closer aspects of mechatronical and process oriented machine tool design. Basis of the considerations are the demands of the machining process and the workpiece dimensions and material. The machining area, the axis and the technical features are designed on characteristic parameters. The forces, torque and speed are derived out of these parameters. Control technique is adapted to the process specific demands of the machine and the workpiece. The machine tool behavior is adapted to the process demands so that the costs and energy consumption are minimized. Some examples are included to present properties concerning accuracy, dynamic behavior and influencing parameters.


The quality of a machined part strongly depends on the state of wear and the cutting tool. This wear is a major problem in the field of industry. This depends on several factors such as the material to be machined, the cutting tool, the cutting conditions and the machining process. All these factors have the corollary of a significant production of heat at the tool-chip interface. This heat induces accelerated wear of the cutting tool, which considerably limits the performance of the machine tool and is mainly detrimental to both the workpiece and the cutting tool. In this study, the main objective is to contribute to the study of the mechanisms of degradation of the tool by carrying out from an experimental approach based on the techniques of thermocouples located in places studied in order to avoid the influence of parasitic and undesirable parameters such as surface regeneration vibrations, etc. This approach is carried out experimentally by measuring the temperature of the cutting face (friction tool / chip interface). From the results collected during the experiment, we can understand the effects of different turning parameters on the temperature developed on the face of the tool and the appropriate turning conditions to obtain a maximum material removal rate at a lower temperature. The results obtained are represented and analyzed graphically.


2021 ◽  
Vol 2074 (1) ◽  
pp. 012071
Author(s):  
Liyao Li

Abstract Cutting chatter is a strong relative vibration between cutting tool and work piece in machining process, which will reduce cutting quality and cutting efficiency, and shorten the service life of cutting tool and machine tool. As long as cutting is carried out in production, vibration will occur, and chatter is a strong self-excited vibration between machining work piece and cutting tool. Flutter problem will occur in almost all cutting processes, which will cause a series of problems such as the reduction of dimensional accuracy of machined work pieces, tool damage and so on. In the dynamic design and dynamic analysis of machine tool structure, in order to evaluate and improve the ability of machine tool to resist chatter, and to select the cutting conditions without chatter, it is necessary to judge the cutting stability of machine tool. How to improve the advanced technology of manufacturing industry is an important topic for manufacturing researchers, and the research on the detection of cutting chatter stability has important practical significance for promoting the development of cutting manufacturing industry to high-end technology.


2021 ◽  
Author(s):  
Arameh Eyvazian ◽  
Farayi Musharavati ◽  
Afrasyab Khan ◽  
Mohsen Soori ◽  
Tamer A. Sebaey ◽  
...  

Abstract To enhance the quality of machined parts, virtual machining systems are presented in this study. In the turbine blades, the minimization of the surface roughness of the blades can decrease the Reynolds number to decrease the loss of energy in power generation. Due to difficulties of polishing process in minimizing the surface roughness of machined blades, the optimized machining parameters for minimizing the surface roughness is an effective solution for the problem. In this study, a virtual machining system is developed to predict and minimize the surface roughness in 5-Axis machining operations of gas turbine blades. To minimize the surface roughness, the machining parameters were optimized by the Genetic algorithm. To validate the developed system, the turbine blades were machined using a 5-Axis CNC machine tool and the machined blades were measured using the CMM machine to obtain the surface roughness of machined parts. So, a 41.29% reduction in the measured surface roughness and a 42.09% reduction in the predicted surface roughness are obtained using the optimized machining parameters. The developed virtual machining system can be applied in the machining process of turbine blades to enhance the surface quality of machined blades and thus improve the efficiency of gas turbines.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
S. Sarath ◽  
P. Sam Paul

Purpose A new cutting tool is always well-defined and sharp at the onset of the metal cutting process and gradually losses these properties as the machining process advances. Similarly, at the beginning of the machining process, amplitude of tool vibrations is considerably low and it increases gradually and peaks at the end of the service period of the cutting tool while machining. It is significant to provide a corresponding real-time varying damping to control this chatter, which directly influences accuracy and quality of productivity. This paper aims to review the literature related to the application of smart fluid to control vibration in metal cutting and also focused on the challenges involved in the implementation of active control system during machining process. Design/methodology/approach Smart dampers, which are used as semi-active and active dampers in metal cutting, were reviewed and the research studies carried out in the field of the magnetorheological (MR) damper were concentrated. In smart materials, MR fluids possess some disadvantages because of their sedimentation of iron particles, leakage and slow response time. To overcome these drawbacks, new MR materials such as MR foam, MR elastomers, MR gels and MR plastomers have been recommended and suggested. This review intents to throw light into available literature which exclusively deals with controlling chatter in metal cutting with the help of MR damping methods. Findings Using an MR damper popularly known for its semi-active damping characteristics is very adaptable and flexible in controlling chatter by providing damping to real-time amplitudes of tool vibration. In the past, many researchers have attempted to implement MR damper in metal cutting to control vibration and were successful. Various methods with the help of MR fluid are illustrated. Research limitations/implications A new cutting tool is always well-defined and sharp at the onset of metal cutting process and gradually losses these properties as the machining process advances. Similarly, at the beginning of the machining process, amplitude of tool vibrations is considerably low and it increases gradually and peaks at the end of service period of cutting tool while machining. Application of MR damper along with the working methodology in metal cutting is presented, challenges met are analyzed and a scope for development is reviewed. Practical implications This study provides corresponding real-time varying damping to control tool vibration which directly influences accuracy and quality of productivity. Using an MR damper popularly known for its semi-active damping characteristics is very adaptable and flexible in controlling chatter by providing damping to real-time amplitudes of tool vibration. Social implications This study attempts to implement smart damper in metal cutting to control vibrations. Originality/value It is significant to provide corresponding real-time varying damping to control tool vibration which directly influences accuracy and quality of productivity.


2006 ◽  
Vol 315-316 ◽  
pp. 656-660
Author(s):  
Song Zhang ◽  
Xing Ai ◽  
Jun Zhao ◽  
J.G. Liu

During high-speed machining, in order to make cutting tools work reliably and obtain ideal machining quality, not only good static characteristics, but also good dynamic characteristics are necessary. In this paper, with the help of the close combination of experimental research and modal parameter identification technique, the dynamic characteristics of the machine tool/cutting tool system were analyzed. Experimental results indicated that studying the effect of the dynamic characteristics on cutting force, machining accuracy and surface roughness could provide theoretical basis for effectively excluding the resonance zone that obviously destroyed machining quality and then optimizing cutting parameters further.


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