Thermodynamic entropy model in metal cutting system

2012 ◽  
Author(s):  
Lijing Zou
Keyword(s):  
Metal Cutting ◽  
Entropy Model ◽  
Thermodynamic Entropy ◽  
Cutting System

Synergetic Concept of Software Control of Machining Processes on Metal-Cutting Machines

2021 ◽  
pp. 24-36
Author(s):  
V.L. Zakovorotny ◽  
V.E. Gvindzhiliya
Keyword(s):  
Tool Wear ◽  
Metal Cutting ◽  
Wear Testing ◽  
External Control ◽  
Machining Processes ◽  
Cutting Zone ◽  
Output Characteristics ◽  
The Cost ◽  
And Control ◽  
Cutting System

High precision metal-cutting machines ensure that the programmed machine actuator trajectories correspond to the real ones. For lathes these are the trajectories of the longitudinal and transverse calipers of the system, as well as the spindle. The purpose of processing is to produce parts of a given quality while minimizing the manufacturing costs. The condition of the dynamic cutting system, determined by the trajectories of forces and deformations, affects the quality indicators of parts and the cutting efficiency, which depends on the intensity of tool wear. The properties of the system change depending on the phase trajectory of the power of irreversible transformations of the energy supplied to the cutting zone by the work performed. Their changes related with the evolution of the parameters of the dynamic link formed by cutting are manifested in the development of tool wear and changes in the quality of the part. Thus, the power of irreversible energy transformations is one of the internal factors causing changes in the output characteristics of processing and the state of the process. In this regard, when processing on machine tools, there is a problem of synergistic coordination of external control (for example, the CNC program) with internal one, the source of which is the irreversible transformation of the energy supplied to the cutting zone. The article considers the problem of synergetic coordination of external and internal controls during cutting process, the solution of which will allow increasing the efficiency of processing on CNC machines. A mathematical model of a controlled dynamic cutting system and control algorithms are proposed to improve the efficiency of processing parts of a given quality while minimizing the intensity of tool wear. Testing of the developed algorithms has shown that their use reduces the cost of manufacturing parts by 1.2.

Determination of optimal coordinates for switching processing cycles on metal-cutting machines

2021 ◽  
Vol 23 (1) ◽  
pp. 56-67
Author(s):  
Vilor Zakovorotny ◽  
◽  
Valery Gvindjiliya ◽  
Keyword(s):  
Metal Cutting ◽  
Cutting Speed ◽  
Subject Area ◽  
Cnc System ◽  
Machining Processes ◽  
Processing Efficiency ◽  
Tool Replacement ◽  
Cutting Path ◽  
The Given ◽  
Cutting System

Introduction. One of the ways to improve the efficiency of processing on machines is to coordinate the CNC program with the changing properties of the dynamic cutting system. If this takes into account the tool wear and the associated with it changes in the parameters of the dynamic cutting system, then the cutting speed to ensure the minimum wear rate is reduced along the cutting path. The corresponding feed rate is reduced even faster, since it is necessary to ensure a constant deformation displacement of the tool relative to the workpiece. The evolution of the properties of the cutting process (for matching with which the trajectories of the operating elements of the machine are corrected) depends on the power of irreversible transformations of the energy supplied to cutting. This reduces the processing efficiency. Therefore, a new for the considered subject area problem of determining the coordinates of the tool movement relative to the workpiece is formulated, starting from which further processing is economically inexpedient. In this case, it is necessary, after processing the next part, to ensure the replacement of the tool and carry out its changeover. Subject. A metal-cutting machine of a turning group, the trajectories of the executive elements of which are controlled, for example, by a CNC system. The purpose of the work. Mathematical simulation and methods for determining the coordinates at which it is necessary to replace the tool. Method and methodology. The necessary conditions for the optimality of determining these coordinates are proved. Mathematical tools are provided that allow calculating the coordinates at which the given manufacturing costs take the minimum value according to the given trajectories. The probabilistic characteristics of evolutionary trajectories are taken into account. Results and discussions. The analysis of the efficiency of using the technique in industry depending on the cost of the machine and tool together with its replacement and readjustment is given. The proven optimality conditions and the given mathematical tools complement the knowledge about the optimization of controlled machining processes on machines. Conclusions. The results of the study show new options for the organization of tool replacement, aimed at improving the efficiency of processing by software methods using a CNC system.

scholarly journals Experimental Complex for Assessing the Effect of Wear on the Temperature and Vibration of the Tool when Turning Metals

2021 ◽  
Vol 2131 (5) ◽  
pp. 052019
Author(s):  
Viktor Lapshin ◽  
Ilya Turkin ◽  
Stanislav Noda ◽  
Valera Golodze
Keyword(s):  
Numerical Experiments ◽  
Metal Cutting ◽  
High Efficiency ◽  
Vibrational Energy ◽  
Mutual Influence ◽  
Full Scale ◽  
Measuring System ◽  
Back Surface ◽  
Coordinate Changes ◽  
Cutting System

Abstract The work is devoted to the development of an experimental measuring complex designed for conducting experiments to assess the mutual influence of tool wear, temperature during cutting and vibration activity of the tool when turning metals on metal-cutting machines. In this paper, it is proposed to place three vibration transducer sensors on the tool holder itself, as well as to insert an artificial thermocouple inside the cutting plate. The introduction of the thermocouple is made in such a way that temperature measurements are made close to the back surface of the tool formed during cutting. The conducted studies have shown the high efficiency of the measuring system and the possibility of its use for the identification of mathematical models of the cutting system. Research methods full-scale and numerical experiments in which the Matlab package of mathematical programs was used for data processing and analysis. Results and discussion. The results of full-scale and numerical experiments are presented, in particular, graphs of coordinate changes describing tool deformation, and data sets are obtained that reflect the dependence of the vibrational energy of tool movements on the reaction time of the thermodynamic subsystem of the cutting system.

Evaluation of the influence of the reaction rate of the thermodynamic subsystem on the dynamics of the cutting process in metalworking

2021 ◽  
Vol 23 (2) ◽  
pp. 17-30
Author(s):  
Victor Lapshin ◽  
◽  
Roman Rusanovsky ◽  
Ilya Turkin ◽  
◽  
...  
Keyword(s):  
Numerical Experiments ◽  
Metal Cutting ◽  
Vibrational Energy ◽  
Dimensional Accuracy ◽  
Full Scale ◽  
Cutting Process ◽  
Qualitative Assessment ◽  
Vibration Load ◽  
Coordinate Changes ◽  
Cutting System

Introduction. Modern metalworking machines with CNC, allow to achieve a qualitatively new level of metal processing by cutting in metal turning. At the same time, it is possible to achieve the required shape, dimensional accuracy, as well as the relative position of the surfaces of the part, but such an indicator of the processing quality as the roughness of the treated surface, associated with the vibration activity of the tool, does not always meet the specified requirements. The factor determining the vibration mode of cutting in a metal-cutting lathe is the self-excitation factor of the cutting system, which is caused by additional feedbacks formed during the cutting process, one of which is the thermodynamic subsystem of the cutting system, which is the subject of research. Purpose of the work: due to the formation of a consistent model of the relationship between the subsystems that describe the force, heat and vibration reactions of the tool, an adequate description of the mechanism for reducing the vibration load on the cutting process is obtained. The paper studies the process of metal turning on metal-cutting machines with a detailed description of the interaction between the thermodynamic, power and vibration subsystems of the cutting system. Research methods: full-scale and numerical experiments in which the Matlab package of mathematical programs is used for data processing and analysis. Results and discussion. The results of full-scale and numerical experiments are presented, in particular, graphs of coordinate changes describing tool deformation, and data sets are obtained that reflect the dependence of the vibrational energy of tool movements on the reaction time of the thermodynamic subsystem of the cutting system. A qualitative assessment of the results of a full-scale experiment allows us to confirm the adequacy of both the model itself and the results of its modeling. The scope of application of the results obtained in the study is related to the possibility of preliminary preparation of the cutting wedge, which will provide a set value of the time constant of the thermodynamic subsystem, which in turn ensures the minimization of vibration energy. Conclusion: the mathematical model proposed in this paper adequately describes the mechanism of temperature influence on the vibration load of the turning process.

Synergetic approach to improve the efficiency of machining process control on metal-cutting machines

2021 ◽  
Vol 23 (3) ◽  
pp. 84-99
Author(s):  
Vilor Zakovorotny ◽  
◽  
Valery Gvindjiliya ◽  
Keyword(s):  
Dynamic System ◽  
Internal Control ◽  
Metal Cutting ◽  
A Priori ◽  
Machining Process ◽  
External Control ◽  
Processing Efficiency ◽  
Cutting System ◽  
Required Quality

Introduction. The efficiency of processing on metal-cutting machines is evaluated by the reduced cost of producing a batch of parts while ensuring the required quality. In modern production, parts are usually made on CNC machines. Today the CNC program and the trajectories of the machine tool actuators match each other with high accuracy, which, however, does not yet guarantee quality and efficiency of production. The definition of the CNC program is based on the knowledge base of rational modes, tools, coolant and etc. during processing. This base reflects some averaging over the set of machines, tools and processing conditions, and does not take into account changes in the properties of the dynamic system in the process of cutting. Subject. The paper deals with the synergistic matching of external control (CNC programs) and cutting dynamics (internal control). The internal control factors can be set a priori, as well as determined as a result of the influence of irreversible energy transformations in the cutting zone. The purpose of the work is to determine the law of controlling the trajectories of the machine's executive elements in such a way that, with changing properties of the dynamic cutting system, the required surface quality of the part and minimizing the intensity of tool wear are ensured during the processing of the part. Method and methodology. Mathematical simulation of the controlled dynamic system, which properties change due to the a priori set laws of variation of subsystem parameters, as well as changes in the cutting properties conditioned by the power of irreversible energy transformation is presented. Consideration of the power of irreversible energy transformations is necessary for predicting back-edge wear, changes in dynamic coupling parameters, and evolutionary restructuring of cutting dynamics. Results and Discussion. The regularity of matching the CNC program with the changing properties of the cutting process, which allows increasing the processing efficiency while ensuring the required quality of parts, is disclosed. A number of properties of the dynamic cutting system caused by changing trajectory of the longitudinal feed rate of the tool during processing of the shaft, the stiffness change of which is given, are revealed and analyzed.

Mixed Time Series Models for Time-Varying Metal Cutting Process

1991 ◽  
Author(s):  
Wu Ya ◽  
Ke Shiqiu ◽  
Yang Shuzi ◽  
Xu Shanxiang ◽  
Li Weiguo ◽  
...  
Keyword(s):  
Time Series ◽  
Metal Cutting ◽  
Damping Ratio ◽  
Time Variability ◽  
Time Interval ◽  
Time Varying ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Cutting Chatter ◽  
Cutting System

Abstract The concept of time-varying metal cutting chatter is developed in this paper and the AR and SETAR models based on the segmented time series are introduced to describe the time-variability, which is applied in analyzing the chatter in a type Mx-4 lathe. The emphasis of this work is placed on four aspects: the AR spectrum, the chatter modal damping ratio, the eigenvalues of a time-varying system and the limit cycle for a steady chatter. It is pointed out that, for time-varying chatter, its time interval is quite short compared with ordinary chatter and it will wither away owing to the time-varying parameters of the system. It is also shown that the machine cutting system under steady chatter is still stable and its damping is not equal to zero. The results can well explain the special phenomenon of chatter in Mx-4 lathe and is helpful to the study of time-varying metal cutting chatter.

scholarly journals Bases of variational method for calculating of metal-cutting systems accuracy

2018 ◽  
Vol 224 ◽  
pp. 01038
Author(s):  
Olesya Anikeeva ◽  
Alexander Ivakhnenko ◽  
Oleg Erenkov
Keyword(s):  
Mathematical Model ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Cutting Tools ◽  
Variation Method ◽  
Joint Influence ◽  
Processing Accuracy ◽  
General Mathematical Model ◽  
First Time ◽  
Cutting System

The bases of a variation method to calculate the metal-cutting systems accuracy for the first time are systemically stated in this paper. The main attention is paid to a problem of joint influence of geometrical accuracy of machine tools and cutting tools parameters on the details processed surfaces accuracy. The general mathematical model of metal-cutting systems accuracy is presented in this work. The general model is the basis to develop the full mathematical model of turning metal-cutting system accuracy. The results of accuracy modeling at turning with a wide cutter are received when studying nature of influence of the lathe and the cutting tool geometrical errors on processing accuracy of cylindrical and face surfaces. The directions of further researches in the field of calculations of metal-cutting systems accuracy at difficult surfaces processing by the shaped cutting tool and also when accounting rigidity of the systems elements and the proceeding processes are revealed in the presented work.

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