Systems of automatic vibration monitoring in machine tools

Szulewski, Piotr; Śniegulska-Grądzka, Dominika

doi:10.17814/mechanik.2017.3.37

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…In terms of practical use of the results of the study, a promising and useful combination of results with the use of control over feedback signals from vibration sensors used in OKUMA NAVI technology [15]. With an increase in the level of vibrations, the search for a new value of the cutting speed is considered appropriate to carry out in the direction of the greatest productivity, using the SLD designed according to the developed method, which will increase the efficiency of such adaptive control.…”

Section: Discussion Of the Frequency Time Approach To Enabling The St...mentioning

confidence: 99%

A time-frequency approach to ensuring stability of machining by turning

Petrakov

Danylchenko

2022

EEJET

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This paper reports a new approach to ensuring the stability of the turning process, which is based on the frequency-time characteristics of the technological machining system (TMS). The approach uses a mathematical model of the turning process as a single-mass system with one degree of freedom, taking into account negative feedback on the normal coordinate and positive feedback with a delay in cutting depth. A new criterion for the stability of the cutting process as a system with a delay in positive feedback is proposed, based on the analysis of frequency characteristics in the form of a Nyquist diagram. It is proved that such a system will be stable when the chart of its Nyquist diagram does not cover a point with coordinates [+1, 0] on the complex plane. The validity of the new criterion has been confirmed by comparing the simulation results in the time range with the location of the Nyquist diagram on the complex plane. Based on the new criterion of stability, an algorithm for automatic construction of a Stability Lobes Diagram (SLD) has been developed. The necessary a priori parameters of TMS, the ranges of frequency change, and the calculation step for constructing such a characteristic in the coordinates "cutting depth – spindle rotational speed" have been determined. The adequacy of the obtained results is confirmed by a full-scale experiment to assess the roughness of machined parts under cutting modes that fall into the area of stability and instability on the SLD chart. The full-scale experiment proved the possibility of a significant reduction in roughness according to the Rz parameter, from 43 µm to 18 µm, while increasing productivity by 1.28 times. The use of a stability lobes diagram is especially effective when programming CNC lathes where it is possible to select the spindle speed in a wide range.

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Section: Discussion Of the Frequency Time Approach To Enabling The St...mentioning

confidence: 99%

A time-frequency approach to ensuring stability of machining by turning

Petrakov

Danylchenko

2022

EEJET

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“…Methods of active vibration suppression (ACC) involve the creation of automatic control systems with feedback. For example, machining Navi by Okuma uses a set of functions (software and hardware) that optimize cutting mode on a CNC machine directly in the process of machining [7] based on vibration signals. The hardware part consists of two independent modules (Fig.…”

Section: Problem Status Analysismentioning

confidence: 99%

Assignment of the cutting mode when boring holes on CNC machine

Petrakov,

Danylchenko

2023

Mech. Adv. Technol.

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Due to structural limitations, the processes of boring holes are performed in a low-rigidity machining system, which predetermines their susceptibility to vibrations. The article is devoted to the study of the process of boring holes on CNC machines, and the subject of the study is the effect of the cutting mode on the stability of the machining. The mathematical model of the machining system is presented in the form of a two-mass dynamic system, which forms a closed loop structure with negative feedback by elastic displacement. In addition, positive feedback is taken into account through the delay argument function, which represents machining along traces. It has been proven that this process provokes the emergence of regenerative oscillations in the machining system. The application of the system’s approach made it possible to obtain a mathematical model in the form of state variables, which is acceptable for the use of numerical modeling methods in both time and frequency space. An applied engineering program for determining the stability diagram in "cutting depth - spindle speed" coordinates has been created. The program uses a new criterion of stability of systems closed through positive feedback loop with a delay argument function. For the first time, the validity of such a criterion was proved for systems described by differential equations of the fourth order. The importance of taking into account the results of the study in the form of a stability lobes diagram when assigning a cutting mode, especially in the area of high speeds, is proven. Thus, according to the results of the experiments, a change in speed of only 7% from 2150 rpm to 2320 rpm with the same cutting depth of 0.4 mm allows the process to become stable. The use of the created program is possible in the system of automatic control of the online cutting mode when the machine is equipped with vibration sensors with appropriate systems for identifying the dynamic parameters of the machining system, which will significantly increase the machining efficiency.

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“…The offline procedure is carried out according to the following plan: chatter detection, deactivation of feed, adjustment of spindle speed, recommencement of cutting. The procedure for the online method is based on continuous chatter control and immediate adjustment of spindle speed should chatter occur -the entire process does not involve the interference in feed [19].…”

Section: State Of the Artmentioning

confidence: 99%

Effect of technological parameters on vibration acceleration in milling and vibration prediction with artificial neural networks

Zagórski

Kulisz

2019

MATEC Web Conf.

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This paper reports on the study of vibration acceleration in milling and vibration prediction by means of artificial neural networks. The milling process, carried out on AZ91D magnesium alloy with a PCD milling cutter, was monitored to observe the extent to which the change of selected technological parameters (vc, fz, ap) affects vibration acceleration ax, ay and az. The experimental data have shown a significant impact of technological parameters on maximum and RMS vibration acceleration. The simulation works employed the artificial neural networks modelled with Statistica Neural Network software. Two types of neural networks were employed: MLP (Multi-Layered Perceptron) and RBF (Radial Basis Function).

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Systems of automatic vibration monitoring in machine tools

Cited by 7 publications

References 8 publications

A time-frequency approach to ensuring stability of machining by turning

A time-frequency approach to ensuring stability of machining by turning

Assignment of the cutting mode when boring holes on CNC machine

Effect of technological parameters on vibration acceleration in milling and vibration prediction with artificial neural networks

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