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Operational Assessment of Machine Tool Vibration Resistance
Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 150 (2016) 215 – 219
International Conference on Industrial Engineering, ICIE 2016
Operational Assessment of Machine Tool Vibration Resistance F. S. Sabirova,*, N. A. Kochinevb, S. S. Shemyakina b
a State Technological University STANKIN, Vadkovsky per. 1, Moscow 127994, Russia Experimental R&D Institute of Machine-Tools (ENIMS), 5-y Donskoy proezd 15, str. 8, Moscow 119991, Russia
Abstract The issues of vibration resistance of machines evaluation in a production environment based on experimental determination of dynamic characteristics of spindle units in the original software environment, of identification of model parameters according to experimental results and evaluation of the actual stiffness of the supports of the spindle have been reviewed The results of studies of several CNC lathe group are presented. Recommendations for improving rigidity of the spindle bearings are given. © 2016 byby Elsevier Ltd.Ltd. This is an open access article under the CC BY-NC-ND license 2016The TheAuthors. Authors.Published Published Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016. Peer-review under responsibility of the organizing committee of ICIE 2016
Keywords: Vibration; vibration resistance; stiffness; dynamic behavior; simulation; spindle assembly; the condition of the bearings
1. Introduction. The problems associated with vibration when machining on metal-cutting machine tool, i.e. the problem of vibration resistance, arise in any enterprise, operating metal-cutting equipment. There comes a time when the machine stops normally cut the workpiece, there are intense vibrations even at low cutting depths [1-3]. Because of this on the CNC machines necessary to introduce a correction into the program to change modes of processing, productivity falls. Often loss of vibration resistance occurs due to the wear of spindle bearings, due to the reduction of preload in the bearings, due to the decrease in the stiffness of the bearing system. The systems of operative diagnostics and monitoring of the mechanisms and machine parts are recommended [4-7]. Sometimes even new machines have low vibration. This is one of the companies imported two identical modern lathes CNC. One worked well, met all requirements, and the other lost the vibration resistance, especially on the boring operations and lateral turning [8].
* Corresponding author. Tel.: +7-499-972-9584. E-mail address: [email protected]
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016
doi:10.1016/j.proeng.2016.06.749
216
F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
The main indicator of the dynamic quality of the machine [1] is its amplitude-frequency characteristic (AFC). Currently developed sufficiently effective methods and means of measurement of amplitude-frequency characteristics, including the production environment. However, the question remains about the interpretation and evaluation of measured frequency response in the absence of any normative documents. A method is proposed for estimating experimental frequency response by matching with a certain evaluative characteristic obtained by calculation for the model of the machine. 2. The methodology of the study. We show the application of this method on the example of the lathe machining center. Numerous previously conducted dynamic studies [8, 9, and others] show that the greatest influence on the frequency response of a lathe has its spindle Assembly. Therefore, for simplicity we will consider the computational model of spindle Assembly. In a production environment were carried out to measure the frequency response of the two lathes machining centres and one of the same model. One worked without failures and censures with a maximum load of about 7 years, let's call it machine "A". Another worked for a little over a year, let's call it machine "B". To the work of both machines recently appeared to claim: in finish turning at maximum speed (2500-3200 rpm) there was a noise and vibration, significantly reduced vibration free depth of cut, a drop of vibration. Such problems associated with vibrations when cutting, arise quite often, but these cases are notable for the fact that you can compare two same design of the machine, which are operated under the same conditions and with the same load, which would seem to be very similar in production values, but they vary greatly. Spindle unit (SU) of lathes is a rotor on two supports (Fig. 1): in the front post double row radial roller bearing in combination with axial-radial ball bearing; a rear bearing double-row radial roller bearing.
Fig. 1. Spindle unit of machine tool
Experimental studies of both machines was carried out in identical conditions by the method of pulse loading with a torque hammer and measuring the response on this effect [10-12]. Were obtained the amplitude-frequency characteristic (AFC) of the elastic system spindle Assembly at blows on the workpiece near the Cams and measure the elastic response of the sensor of absolute vibrations (accelerometer) at the same point. Amplitude-frequency characteristics of the SU of two machines (Fig. 2) show that the natural frequency of the SU "A" machines below (316 Hz) than the "B" (380 Hz). Dynamic compliance on the natural frequencies from the "A" machine is almost 1.5 times higher than the "B" (5,14 and 3,44 units, respectively), i.e. the "A" machine and has a lower frequency, and more compliance.
F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
217
Fig. 2. AFR by displacement of SU lathes: 1 – the "A" machine; 2 – "B" machine
3. Modeling. Modelling SU and the calculation of its dynamic characteristics was performed using the program SpinDyna [1316] developed in MSTU "Stankin". The program allows you on bases of geometric models to calculate the host response, mode shapes and other characteristics of the spindle Assembly by finite element method. The program's interface and model SU lathe is presented in Fig. 3.
Fig. 3. The formation of models and parameters description SU lathe
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F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
In the model to describe the characteristics of the supports, we used catalog data of the stiffness of bearings. Radial stiffness radial double row roller bearing: rear bearing – 1530 N/μm, front support – 1730 N/μm. For ball thrust bearing: radial stiffness - 920 N/μm and the angular stiffness of 4.3•106 N·m/ȝm. The calculation results with a catalogue stiffness of the bearings gave AFR SU such as shown in Fig. 4 (curve 1). We will consider such a machine with evaluative characteristic. If a double row roller radial bearing stiffness to reduce to 29.5 daN/μm, i.e. almost in 6 times, and the stiffness of the thrust bearing does not change, then the response takes on a different form (curve 2), which corresponds to the experimental frequency response of a "B" machine. Hardly one year in operation, radial double row roller bearing could wear out, so the stiffness drop 6 times. Probably, when assembling SU was not provided with the required preload in the bearing. Claims to the supplier of the machine to be charged with expired warranty. Therefore the company management decided on their own to repair the machine.
Fig. 4. The calculated frequency response SU of machines. 1 – the machine with evaluative characteristic; 2 – the "B" machine; 3 – "A" machine.
If the rigidity of the double-row radial roller bearing front support to accept 17,3 daN/ȝm, i.e. 10 times less than the catalogue value, and a ball thrust bearing 65 daN/mm, that is 1.4 times smaller catalogue, we get the frequency response SU (curve 3 in Fig. 4), which is close to the natural frequency to the experimental frequency response of the "A" machine. In this case, with high probability we can assume that the decrease in stiffness of bearings front bearing was the result of wear. Additional studies have shown the presence of an axial backlash of the spindle on the "A" machine in the order of 0.03 mm. as a measure for improving the rigidity of the front support of the spindle can be recommended calibrated ring with labyrinth seal in front of radial roller bearing (Fig. 1) on the value of the order of 0.1-0.12 mm and the calibration of intermediate rings in axial-radial bearing on the magnitude of 0.03 mm. Modeling SU using SpinDyna also showed that the change in the stiffness of the rear bearing supports on spindle on dynamic performance has a small effect. In other matters, it is a known fact from research practices of the spindle units [14-16]. Thus, this study allows to make a conclusion about the lack of control of preload in the front post of the lathes at the factory. This conclusion is confirmed by the results of similar studies of new lathe model the same firm. One of the two machines worked well, the other side loses its stability in internal turning, and transverse turning. Experimental study of dynamic characteristics of SU modeling showed that the second machine stiffness of the radial roller bearing more than 6 times lower. The reason for the low hardness is the same – the lack of the necessary preload in the bearing. On the basis of the conducted researches, the company which acquired these machines, exhibited the claims of the manufacturer was forced to change all the spindle stock, incurring significant economic costs.
F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
Modeling SU using SpinDyna also showed that the change in the stiffness of the rear bearing supports on spindle on dynamic performance has a small effect. In other matters, it is a known fact from research practices of the spindle units [14-16]. Thus, this study allows to make a conclusion about the lack of control of preload in the front post of the lathes at the factory. Operational control of the dynamic characteristics of SU would prevent buyers from purchasing lowquality machine obviously, but also to monitor the status of equipment operated [17-21]. Acknowledgements This article was prepared as part of the implementation of the state task of the Ministry of education and science of the Russian Federation in the sphere of scientific activity No. 9.1429.2014/K.
References [1] V.A. Kudinov, Dynamics of machine tools, Mechanical engineering, Moscow, 1967. (in Russian). [2] Y. Altintas, M. Weck, Chatter Stability of Metal Cutting and Grinding, CIRP Annals – Manufacturing Technology. 2 (2004) 619642. [3] M.E. Elyasberg, Self-oscillations of machine tools: theory and practice, OKBS, SPb., 1993. (in Russian). [4] S.N. Grigoriev, M.P. Kozochkin, F.S. Sabirov, A.A. Kutin, Diagnostic systems as basis for technological improvement, Procedia CIRP. 1 (2012) 599604 [5] M.P. Kozochkin, F.S. Sabirov, D.N. Suslov, A.P. Abramov, Vibroacoustic Diagnostics of Spindle Bearings in High-Speed Machine Tools, Russian Engineering Research. 30 (2010) 944947. [6] M.P. Kozochkin, F.S. Sabirov, A.N. Bogan, K.V. Myslivtsev, Vibrational diagnostics of roller bearings in metal-cutting machines, Russian Engineering Research. 8 (2013) 486489. [7] M.P. Kozochkin, F.S. Sabirov, Vibroacoustic diagnostics of spindles, Engineering Research. 29 (2009) 827830. [8] F.S. Sabirov, K.V. Myslivtsev, A.N. Bogan, Simulation and experimental study on dynamic characteristics of contemporary lathes, in: Proceeding of Modern materials and technologies 2009, International Xtn Russian-Chinese Symposium, Khabarovsk. (2009) 251254. [9] E.I. Shibanov, The dependence of dynamic characteristics of spindle unit from operating conditions of the machine, Soviet Engineering Research. 8 (1976) 7477. [10] N.A. Kochinev, F.S. Sabirov, Measurement of the dynamic characteristics of machine tools by a pulse loading method, Measurement Techniques. 6 (2009) 621624. [11] N.A. Kochinev, F.S. Sabirov, Quasi-static Method of Measuring the Balance of Elastic Displacements of the Supporting System of Machine Tool, Measurement Techniques. 6 (2006) 572578. [12] N.A. Kochinev, F.S. Sabirov, M.P. Kozochkin, RU Patent 2009613214. (2009). [13] N.A. Kochinev, F.S. Sabirov, V.S. Khomyakov, RU Patent 2009611613. (2009). [14] V.S. Khomyakov, N.A. Kochinev, F.S. Sabirov, Dynamic characteristics of spindle components, Russian Engineering Research. 29 (2009) 607611. [15] V.S. Khomyakov, F.S. Sabirov, Spindle and sleeve in grinding machines, Russian Engineering Research. 32 (2012) 733737. [16] F. Sabirov, D. Suslov, S. Savinov, Diagnostics of spindle unit, model design and analysis, The International Journal of Advanced Manufacturing Technology. 62 (2012) 861865. DOI: 10.1007/s00170-011-3848-7. [17] M.P. Kozochkin, F.S. Sabirov, E.M. Durko, V.M. Davydov, V.V. Zaev, Diagnostics and monitoring of spindle bearings, Russian Engineering Research. 34 (2014) 3436. [18] F.S. Sabirov, A.N. Petrov, P.V. Lisenkov, Vibro-diagnostics of motor-spindle supports on a turning machine, in: Proceeding of Modern materials and technologies 2009, International Xtn Russian-Chinese Symposium. Proceedings, Khabarovsk. (2009) 261266. [19] M.P. Kozochkin, A.N. Porvatov, F.S. Sabirov, The fitting of technological equipment with data-measuring systems, Measurement Techniques. 55 (2012) 530534. [20] M.P. Kozochkin, A.N. Porvatov, F.S. Sabirov, Vibration Testing of Technological Processes in Automated Machining Equipment, Measurement Techniques. 12 (2014) 14141420. DOI: 10.1007/s11018-014-0393-4. [21] F.S. Sabirov, L.G. Vainer, A.V. Rivkin, Vibroacoustic diagnostics of bidirectional end milling, Russian Engineering Research. 6 (2015) 458461.
219
ScienceDirect Procedia Engineering 150 (2016) 215 – 219
International Conference on Industrial Engineering, ICIE 2016
Operational Assessment of Machine Tool Vibration Resistance F. S. Sabirova,*, N. A. Kochinevb, S. S. Shemyakina b
a State Technological University STANKIN, Vadkovsky per. 1, Moscow 127994, Russia Experimental R&D Institute of Machine-Tools (ENIMS), 5-y Donskoy proezd 15, str. 8, Moscow 119991, Russia
Abstract The issues of vibration resistance of machines evaluation in a production environment based on experimental determination of dynamic characteristics of spindle units in the original software environment, of identification of model parameters according to experimental results and evaluation of the actual stiffness of the supports of the spindle have been reviewed The results of studies of several CNC lathe group are presented. Recommendations for improving rigidity of the spindle bearings are given. © 2016 byby Elsevier Ltd.Ltd. This is an open access article under the CC BY-NC-ND license 2016The TheAuthors. Authors.Published Published Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016. Peer-review under responsibility of the organizing committee of ICIE 2016
Keywords: Vibration; vibration resistance; stiffness; dynamic behavior; simulation; spindle assembly; the condition of the bearings
1. Introduction. The problems associated with vibration when machining on metal-cutting machine tool, i.e. the problem of vibration resistance, arise in any enterprise, operating metal-cutting equipment. There comes a time when the machine stops normally cut the workpiece, there are intense vibrations even at low cutting depths [1-3]. Because of this on the CNC machines necessary to introduce a correction into the program to change modes of processing, productivity falls. Often loss of vibration resistance occurs due to the wear of spindle bearings, due to the reduction of preload in the bearings, due to the decrease in the stiffness of the bearing system. The systems of operative diagnostics and monitoring of the mechanisms and machine parts are recommended [4-7]. Sometimes even new machines have low vibration. This is one of the companies imported two identical modern lathes CNC. One worked well, met all requirements, and the other lost the vibration resistance, especially on the boring operations and lateral turning [8].
* Corresponding author. Tel.: +7-499-972-9584. E-mail address: [email protected]
1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIE 2016
doi:10.1016/j.proeng.2016.06.749
216
F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
The main indicator of the dynamic quality of the machine [1] is its amplitude-frequency characteristic (AFC). Currently developed sufficiently effective methods and means of measurement of amplitude-frequency characteristics, including the production environment. However, the question remains about the interpretation and evaluation of measured frequency response in the absence of any normative documents. A method is proposed for estimating experimental frequency response by matching with a certain evaluative characteristic obtained by calculation for the model of the machine. 2. The methodology of the study. We show the application of this method on the example of the lathe machining center. Numerous previously conducted dynamic studies [8, 9, and others] show that the greatest influence on the frequency response of a lathe has its spindle Assembly. Therefore, for simplicity we will consider the computational model of spindle Assembly. In a production environment were carried out to measure the frequency response of the two lathes machining centres and one of the same model. One worked without failures and censures with a maximum load of about 7 years, let's call it machine "A". Another worked for a little over a year, let's call it machine "B". To the work of both machines recently appeared to claim: in finish turning at maximum speed (2500-3200 rpm) there was a noise and vibration, significantly reduced vibration free depth of cut, a drop of vibration. Such problems associated with vibrations when cutting, arise quite often, but these cases are notable for the fact that you can compare two same design of the machine, which are operated under the same conditions and with the same load, which would seem to be very similar in production values, but they vary greatly. Spindle unit (SU) of lathes is a rotor on two supports (Fig. 1): in the front post double row radial roller bearing in combination with axial-radial ball bearing; a rear bearing double-row radial roller bearing.
Fig. 1. Spindle unit of machine tool
Experimental studies of both machines was carried out in identical conditions by the method of pulse loading with a torque hammer and measuring the response on this effect [10-12]. Were obtained the amplitude-frequency characteristic (AFC) of the elastic system spindle Assembly at blows on the workpiece near the Cams and measure the elastic response of the sensor of absolute vibrations (accelerometer) at the same point. Amplitude-frequency characteristics of the SU of two machines (Fig. 2) show that the natural frequency of the SU "A" machines below (316 Hz) than the "B" (380 Hz). Dynamic compliance on the natural frequencies from the "A" machine is almost 1.5 times higher than the "B" (5,14 and 3,44 units, respectively), i.e. the "A" machine and has a lower frequency, and more compliance.
F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
217
Fig. 2. AFR by displacement of SU lathes: 1 – the "A" machine; 2 – "B" machine
3. Modeling. Modelling SU and the calculation of its dynamic characteristics was performed using the program SpinDyna [1316] developed in MSTU "Stankin". The program allows you on bases of geometric models to calculate the host response, mode shapes and other characteristics of the spindle Assembly by finite element method. The program's interface and model SU lathe is presented in Fig. 3.
Fig. 3. The formation of models and parameters description SU lathe
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F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
In the model to describe the characteristics of the supports, we used catalog data of the stiffness of bearings. Radial stiffness radial double row roller bearing: rear bearing – 1530 N/μm, front support – 1730 N/μm. For ball thrust bearing: radial stiffness - 920 N/μm and the angular stiffness of 4.3•106 N·m/ȝm. The calculation results with a catalogue stiffness of the bearings gave AFR SU such as shown in Fig. 4 (curve 1). We will consider such a machine with evaluative characteristic. If a double row roller radial bearing stiffness to reduce to 29.5 daN/μm, i.e. almost in 6 times, and the stiffness of the thrust bearing does not change, then the response takes on a different form (curve 2), which corresponds to the experimental frequency response of a "B" machine. Hardly one year in operation, radial double row roller bearing could wear out, so the stiffness drop 6 times. Probably, when assembling SU was not provided with the required preload in the bearing. Claims to the supplier of the machine to be charged with expired warranty. Therefore the company management decided on their own to repair the machine.
Fig. 4. The calculated frequency response SU of machines. 1 – the machine with evaluative characteristic; 2 – the "B" machine; 3 – "A" machine.
If the rigidity of the double-row radial roller bearing front support to accept 17,3 daN/ȝm, i.e. 10 times less than the catalogue value, and a ball thrust bearing 65 daN/mm, that is 1.4 times smaller catalogue, we get the frequency response SU (curve 3 in Fig. 4), which is close to the natural frequency to the experimental frequency response of the "A" machine. In this case, with high probability we can assume that the decrease in stiffness of bearings front bearing was the result of wear. Additional studies have shown the presence of an axial backlash of the spindle on the "A" machine in the order of 0.03 mm. as a measure for improving the rigidity of the front support of the spindle can be recommended calibrated ring with labyrinth seal in front of radial roller bearing (Fig. 1) on the value of the order of 0.1-0.12 mm and the calibration of intermediate rings in axial-radial bearing on the magnitude of 0.03 mm. Modeling SU using SpinDyna also showed that the change in the stiffness of the rear bearing supports on spindle on dynamic performance has a small effect. In other matters, it is a known fact from research practices of the spindle units [14-16]. Thus, this study allows to make a conclusion about the lack of control of preload in the front post of the lathes at the factory. This conclusion is confirmed by the results of similar studies of new lathe model the same firm. One of the two machines worked well, the other side loses its stability in internal turning, and transverse turning. Experimental study of dynamic characteristics of SU modeling showed that the second machine stiffness of the radial roller bearing more than 6 times lower. The reason for the low hardness is the same – the lack of the necessary preload in the bearing. On the basis of the conducted researches, the company which acquired these machines, exhibited the claims of the manufacturer was forced to change all the spindle stock, incurring significant economic costs.
F.S. Sabirov et al. / Procedia Engineering 150 (2016) 215 – 219
Modeling SU using SpinDyna also showed that the change in the stiffness of the rear bearing supports on spindle on dynamic performance has a small effect. In other matters, it is a known fact from research practices of the spindle units [14-16]. Thus, this study allows to make a conclusion about the lack of control of preload in the front post of the lathes at the factory. Operational control of the dynamic characteristics of SU would prevent buyers from purchasing lowquality machine obviously, but also to monitor the status of equipment operated [17-21]. Acknowledgements This article was prepared as part of the implementation of the state task of the Ministry of education and science of the Russian Federation in the sphere of scientific activity No. 9.1429.2014/K.
References [1] V.A. Kudinov, Dynamics of machine tools, Mechanical engineering, Moscow, 1967. (in Russian). [2] Y. Altintas, M. Weck, Chatter Stability of Metal Cutting and Grinding, CIRP Annals – Manufacturing Technology. 2 (2004) 619642. [3] M.E. Elyasberg, Self-oscillations of machine tools: theory and practice, OKBS, SPb., 1993. (in Russian). [4] S.N. Grigoriev, M.P. Kozochkin, F.S. Sabirov, A.A. Kutin, Diagnostic systems as basis for technological improvement, Procedia CIRP. 1 (2012) 599604 [5] M.P. Kozochkin, F.S. Sabirov, D.N. Suslov, A.P. Abramov, Vibroacoustic Diagnostics of Spindle Bearings in High-Speed Machine Tools, Russian Engineering Research. 30 (2010) 944947. [6] M.P. Kozochkin, F.S. Sabirov, A.N. Bogan, K.V. Myslivtsev, Vibrational diagnostics of roller bearings in metal-cutting machines, Russian Engineering Research. 8 (2013) 486489. [7] M.P. Kozochkin, F.S. Sabirov, Vibroacoustic diagnostics of spindles, Engineering Research. 29 (2009) 827830. [8] F.S. Sabirov, K.V. Myslivtsev, A.N. Bogan, Simulation and experimental study on dynamic characteristics of contemporary lathes, in: Proceeding of Modern materials and technologies 2009, International Xtn Russian-Chinese Symposium, Khabarovsk. (2009) 251254. [9] E.I. Shibanov, The dependence of dynamic characteristics of spindle unit from operating conditions of the machine, Soviet Engineering Research. 8 (1976) 7477. [10] N.A. Kochinev, F.S. Sabirov, Measurement of the dynamic characteristics of machine tools by a pulse loading method, Measurement Techniques. 6 (2009) 621624. [11] N.A. Kochinev, F.S. Sabirov, Quasi-static Method of Measuring the Balance of Elastic Displacements of the Supporting System of Machine Tool, Measurement Techniques. 6 (2006) 572578. [12] N.A. Kochinev, F.S. Sabirov, M.P. Kozochkin, RU Patent 2009613214. (2009). [13] N.A. Kochinev, F.S. Sabirov, V.S. Khomyakov, RU Patent 2009611613. (2009). [14] V.S. Khomyakov, N.A. Kochinev, F.S. Sabirov, Dynamic characteristics of spindle components, Russian Engineering Research. 29 (2009) 607611. [15] V.S. Khomyakov, F.S. Sabirov, Spindle and sleeve in grinding machines, Russian Engineering Research. 32 (2012) 733737. [16] F. Sabirov, D. Suslov, S. Savinov, Diagnostics of spindle unit, model design and analysis, The International Journal of Advanced Manufacturing Technology. 62 (2012) 861865. DOI: 10.1007/s00170-011-3848-7. [17] M.P. Kozochkin, F.S. Sabirov, E.M. Durko, V.M. Davydov, V.V. Zaev, Diagnostics and monitoring of spindle bearings, Russian Engineering Research. 34 (2014) 3436. [18] F.S. Sabirov, A.N. Petrov, P.V. Lisenkov, Vibro-diagnostics of motor-spindle supports on a turning machine, in: Proceeding of Modern materials and technologies 2009, International Xtn Russian-Chinese Symposium. Proceedings, Khabarovsk. (2009) 261266. [19] M.P. Kozochkin, A.N. Porvatov, F.S. Sabirov, The fitting of technological equipment with data-measuring systems, Measurement Techniques. 55 (2012) 530534. [20] M.P. Kozochkin, A.N. Porvatov, F.S. Sabirov, Vibration Testing of Technological Processes in Automated Machining Equipment, Measurement Techniques. 12 (2014) 14141420. DOI: 10.1007/s11018-014-0393-4. [21] F.S. Sabirov, L.G. Vainer, A.V. Rivkin, Vibroacoustic diagnostics of bidirectional end milling, Russian Engineering Research. 6 (2015) 458461.
219