- Email: [email protected]
Control of the research stand for electrochemical machining
ScienceDirect ScienceDirect Procedia Manufacturing 00 (2018) 204–209
Available online at www.sciencedirect.com
Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procedia online Manufacturing 00 (2018) 204–209
www.elsevier.com/locate/procedia
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia
Procedia Manufacturing 22 (2018) 196–201 Procedia Manufacturing 00 (2017) 000–000
www.elsevier.com/locate/procedia 11th International Conference Interdisciplinarity in Engineering, INTER-ENG 2017, 5-6 October 2017, Tirgu-Mures, Romania 11th International Conference Interdisciplinarity in Engineering, INTER-ENG 2017, 5-6 October 2017, Tirgu-Mures, Romania
Control of the research stand for electrochemical machining Control Engineering of the research standa, for electrochemical machining b, Manufacturing Society International Conference 2017, MESIC 2017, 28-30 June Jarosław Zdrojewski Tomasz Paczkowski * 2017, Vigo (Pontevedra), Spain P
P
P
P0F
Jarosław Zdrojewskia, Tomasz Paczkowskib, *
a
Department of Digital Technology, Faculty of Telecommunications and Electrical Engineering , UTP, 85-796, Bydgoszcz, Poland Department of Production Engineering, Faculty of Mechanical Engineering, University of Science and Technology, Bydgoszcz, Poland a Department of Digital Technology, Faculty of Telecommunications and Electrical Engineering , UTP, 85-796, Bydgoszcz, Poland b Department of Production Engineering, Faculty of Mechanical Engineering, University of Science and Technology, Bydgoszcz, Poland P
P
P
b
P
P
P0F
Costing models for capacity optimization in Industry 4.0: Trade-off between used capacity and operational efficiency P
P
P
P
P
P
Abstract
A. Santana , P. Afonso , A. Zanin , R. Wernke Abstract The paper presents control method of the research process for erosion machining and construction of the stand. The stand has a modular design, with separated electrodes drive and machining area,Guimarães, which greatly expands its research capabilities. The stand University of Minho, 4800-058 Portugal b The paper ispresents control methodparameters of the research for machining and construction of the stand. The standThis has controller supplying machining and itprocess consists of erosion a Chapecó, PC program communicating with the PLC I/O modules. Unochapecó, 89809-000 SC, Brazil modular design, with separated electrodes and machining area, which expands its research capabilities. stand arrangement allows initial referencing of thedrive electrodes before machining and,greatly based on measurements of the electrolyteThe pressure, controller is supplying machining and of it consists of a electrode, PC program communicating with the PLC synchronization I/O modules. This on-line control for parameters suchparameters as: feed rate the working electrode oscillation frequency, of arrangement allows initial referencing of the machining and,machining based on measurements the type electrolyte pressure, electrodes oscillation, the inter electrodes gapelectrodes thickness.before Conducting erosion experiments onofthis of stand allows Abstract on-line for parameters as: process feed rateand of lets the to working oscillation frequency, synchronization of to verifycontrol a mathematical modelssuch of the developelectrode, an activeelectrode type of on-line control, connecting the theoretical electrodes the inter electrodesduring gap thickness. Conducting erosion machining experiments on this type of stand allows results withoscillation, measurements of parameters machining. to verifythe a mathematical of the process and lets toprocesses develop anwill active of on-line connecting the theoretical Under concept of models "Industry 4.0", production be type pushed to becontrol, increasingly interconnected, results of parameters during © 2018with The measurements Authors. Published by Elsevier B.V.machining. information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization Peer-review under responsibility ofof thecapacity scientificmaximization, committee of the 11th International Conference Interdisciplinarity goes beyondAuthors. the traditional aim contributing also for organization’s profitabilityinand value. © Published by B.V. © 2018 2018 The The Authors. Publishedand by Elsevier Elsevier B.V. improvement approaches suggest capacity optimization instead of Engineering. Indeed, lean management continuous Peer-review under responsibility of the scientific committee of the 11th International Conference Interdisciplinarity in Engineering. Peer-review under responsibility of the scientific committee of the 11th International Conference Interdisciplinarity in maximization. The study of capacity optimization and costing models is an important research topic that deserves Engineering. Keywords: electrochemical machining; computer simulation; border states; ECM machining experiments; active on-line control. a
a,*
b
b
contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model forelectrochemical capacity management based on different costing (ABC experiments; and TDABC). generic model has been Keywords: machining; computer simulation; border states;models ECM machining activeA on-line control. developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s 1. Introduction value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency. 1. Introduction Technological evolution is the cause for industrial use of materials that are harder, more durable, and resistant to
© 2017 The Authors. Published by Elsevier B.V. corrosion, high temperatures and other factors. At the same time, high quality standards are set, most frequently in Peer-review under responsibility thecause scientific Technological evolution isofthe for committee industrial of usetheofManufacturing materials thatEngineering are harder,Society more International durable, andConference resistant to 2017.
corrosion, high temperatures and other factors. At the same time, high quality standards are set, most frequently in
Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency
* Corresponding author. Tel.: +48-523-408-130; fax: +48-523-408-030.
1.E-mail Introduction address: [email protected]
* Corresponding author. Tel.: +48-523-408-130; fax: +48-523-408-030. The cost of idle capacity is a fundamental for companies and their management of extreme importance E-mail address: [email protected] 2351-9789 © 2018 The Authors. Published by Elsevier information B.V. Peer-review responsibility of theInscientific committee of the 11th International Conference Interdisciplinarity in Engineering. in modern under production systems. general, it is defined as unused capacity or production potential and can be measured 2351-9789 2018 The Authors. Published by Elsevier B.V.hours of manufacturing, etc. The management of the idle capacity in several©ways: tons of production, available Peer-review underTel.: responsibility the761; scientific committee the 11th International Conference Interdisciplinarity in Engineering. * Paulo Afonso. +351 253 of 510 fax: +351 253 604of741 E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 11th International Conference Interdisciplinarity in Engineering. 10.1016/j.promfg.2018.03.030
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
197 205
terms of macro and micro-geometric structure parameters, in relation to machined surfaces, including curvilinear surfaces as well. Erosive machining, and especially electro-discharge machining (EDM) and electrochemical machining (ECM), effectively solve numerous problems connected with the machining process, since they give the possibility of machining parts with complex shapes and made out of troublesome, current-conducting materials. The main method in EDM, and especially in ECM, is drilling with a tool electrode. In an EDM process, removal of material from machined part occurs through erosion due to electrical discharges between the electrodes in a fluid state of the dielectric environment. Erosion products are expelled into the dielectric as a stream of liquid metal [3, 5]. In the case of ECM, the process is based on the phenomenon of anode dissolving of the machined surface, therefore the Machined Item (MI) should be connected to the positive pole of DC source, and the Tool Electrode (TE) to the negative one. To the inter-electrode gap (IEG) electrolyte is injected under pressure, conducting electric current in the form of water solutions of acids and bases. Secretion of machining products on the machined item electrode causes the electrolyte conductivity to be variable in time [1, 6]. ECM research confirm the complexity of phenomena connected with the internal structure of electrochemical machining. They include electrode processes, carrying of the electric charge, momentum and energy mass transfer, hydrodynamics and others [1-2, 6]. Described technologies place high importance on research on model research stations. Such research allows to define technological characteristics, necessary for conducting computer simulations, and deviations between conducted computer simulations and experimental research. Acquired results will allow for eventual correction of mathematical and software models [12]. 2. Research station construction During the designing of the research station its modular build was assumed [10]. Inputs and outputs were identified [4]. It was assumed, that the machining process will be realized in so called machining units, constituting a separate construction set (Fig.1). The use of machining units allows unlimited modeling of the machining chamber, so that the process can be conducted in model conditions. Machining units are fixed onto the station body, which is responsible for the realization of complex electrode kinematics: • machining with a tool electrode, • machining with a tool electrode vibrating across the IEG, • machining with a tool electrode vibrating along the IEG, • machining with a tool electrode with a complex vibrating movement possibility of its synchronization, • machining with a tool electrode with the possibility of inducing rotary motion.
Fig. 1. Machining unit: 1 – machined item, 2 - tool electrode, 3 – gaps leading the electrolyte to the IEG.
The body of the research station is made up from four plates mounted on leading columns (Fig. 2). Two farthest plates 1 and 2 are bound to leading columns 3 permanently, and two middle plates 4 and 5 are mounted in a sliding way, realizing set kinematic movements as: • First point downward feed motion, • And so on vibrating motion alongside IEG.
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
198 206
Fig. 2. Research station body.
Vibrating motion alongside IEG is realized with the use of the mechanism placed on the top mobile plate. Specific drive systems are presented in Table 1. Table 1. Station drive systems. Drive
ID
Location
Main tool electrode feed V f speed Servo drive
1
Lead screw with toothed belt drive
2
Mobile plate mounted on leading columns
3
Transverse tool electrode vibrations drive: Servo drive with an eccentric cam
1
Support mounted through rails on mobile plate
2
Support pressure on the eccentric cam
3
Longitudinal electrode vibrations drive: servo drive with an eccentric cam
1
vibrating beam with thrusters
2
beam pressure on the eccentric cam
3
thruster
4
mobile plate mounted on leading columns
5
In the case of erosion machining the station must be equipped in systems of DC power supply and electrolyte supply. 3. Station control system Station control and process monitoring takes through a special created ExECM program for a PC. Basic functions of the ExECM program are presented in Tab 2.
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
199 207
Table 2. Functions of the ExECM program. Function
Software details
Vertical oscillation and Horizontal oscillation: Enable initialization the drives through passing to limit switches and turning on correct oscillations, and their mutual synchronization with a set phase shift. Oscillation – remembered positions: Enables remembering six different mutual locations of eccentric cams which are the starting point for electrode vibration synchronization. Electrode– remembered positions: Enables setting of IEG value through recording six different mutual positions of the tool electrodes. Useful in research with multiple repetitions. Movement from the electrode: Enables setting a velocity and time for the machining. Start and stop execution: The field for starting the test panel, stopping or exiting the program.
Synchronization of vertical (along IEG width) and horizontal (alongside IEG) vibrations is possible due to the use of optical sensors. Thanks to the optical sensors, after launching the drives responsible for each of the vibration modes, the basing of eccentric cams and then their rotation by a set value of the angular displacement of vibration. In the last field of the software, a possibility of testing communication and "manual" drive control is provided. For this purpose, a VECM panel-communication tester was created (Fig. 3). The base tasks of the panel are: • start-up tool, allowing for individual control of the axes. Basing, movement to a set position or immediate stop. It allows verification of end switches functioning, initial axis positioning in the motion range, or movement to a set position for a set modifiable feed; • station service tester, tasks as above. Used in case of a breakdown for restoration of functionalities.
Fig. 3. VECM panel - communication tester and communication code sample (initialize and move axis).
200 208
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
System for monitoring and control of machining process parameters was designed basing on the Mitsubishi FX 3U controller and a PC. FX 3U controller was places alongside other necessary controlling and safety elements in the controls cabinet. The system comprises of (Fig. 4): • PC computer with implemented ExECM program 1, • controls cabinet: • servo for each axis - 2, 3, 4, • Mitsubishi FX 3U controller with in/out FX 3U-232-BD mode - 5, • other elements necessary for the functioning of the system, such as: VS 116K relays, contactors, 24V DR 7524 power supply, power protection, • DC motors (servo drives) 6, • electrolyte pressure sensors 7, • end switches 8, • optical sensor 9.
Fig. 4. Control and monitoring system of machining process parameters.
It should be underlined, that presented servo-drive control system enables them to work with a constant feed speed and constant load. Consequently, depending on set mode process research can be conducted maintaining a constant machining speed or constant average pressure in the IEG. Next to the mechanic system we can distinguish the following components of the station (Fig. 5): • electrolyte feed speed, • DC power supply.
Fig. 5. Erosion machining research station (1 - electrolyte feed speed, 2 - DC power supply).
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
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4. Conclusions Presented research station enables researchers to deepen the knowledge about erosion machining processes conducted in conditions with complex electrode kinematics. It mainly applies to machining of complex surfaces with curvilinear generators. In case of such surfaces, the removal of machining products from the inter-electrode gap is highly difficult. These difficulties often lead to the so called machining critical states, that is the occurrence of electrical discharge (in the case of ECM), the occurrence of an electric arc, or electrode short circuit [7]. It is mainly connected to electrochemical machining, in which products of dissolution change the machining parameters along the inter-electrode gap in a significant degree. These factors cause difficulties in defining machining parameters and in designing the right shape of the cathode tool surface. One of the factors that influence the stability of machining is induction of tool electrode vibrations. Such vibrations lead to interruption of the pre short-circuit processes and at the same time allow periodical rinsing of the machining area. Analysis of electrolyte pressure measurements additionally enables on-line modifications of the controllable machining parameters: ER feed speed, electrode vibrations frequency, electrode vibrations synchronization, IEG width. Achieved results form a basis for development of various kinds of mathematical modelling concepts for the machining, and bilateral joining of such theoretical models with the process controls [8,9,11]. It should be stressed that all the research possibilities presented above can be freely developed due to the modular build of the station and the use of programmable controllers. References [1] L. Dąbrowski, Podstawy komputerowej symulacji kształtowania elektrochemicznego, (Computer simulation basics of electrochemical shaping), Prace Naukowe, Mechanika, z. 154, Wydaw. Politechniki Warszawskiej, Warszawa, 1992. [2] L. Dąbrowski, T. Paczkowski, Computer simulation of two-dimensional electrolyte flow in electrochemical machining, Russian Journal of Electrochemistry. 41(1) (2005) 91-98.. [3] L. Dąbrowski, R. Świercz, Struktura metalograficzna powierzchni po obróbce elektroerozyjnej, (Metallographic structure of the surface after electro-erosion machining), Inżynieria Maszyn. 16 (2011): 16-23. [4] J. Ditrich, System i konstrukcja, (System and design), Warszawa WNT, 1980. [5] M. Gostimirovic, P. Kovac, Influence of dis charge energy on machining characteristics in EDM, Journal of Mechanical Science and Technology. 6(1) (2012) 173-179. [6] J. Kozak, Kształtowanie powierzchni obróbką elektrochemiczną bezstykową (ECM), (Surface shaping by contactless electrochemical machining), Pr. Naukowe PW, Mechanika nr 41, Wydawnictwo Politechniki Warszawskiej, Warszawa, 1976. [7] K. Łubkowski, Stany krytyczne w obróbce elektrochemicznej, (Critical states in electrochemical machining), Prace naukowe, Mechanika, z.163, Oficyna Wydawnicza PW, Warszawa, 1996. [8] T. Mikolajczyk, T. Fas, A. Klodowski, M. Matuszewski, A. Olaru, S. Olaru, Computer Aided System for Superfinishing Process Control, Procedia Technology. 22 (2016) 48-54 [9] T. Paczkowski, J. Zdrojewski, Boundary conditions analysis of ECM machining for curvilinear surfaces, Journal of POLISH CIMAC. 6(3) (2011) 193-198. [10] T. Paczkowski , Konstrukcja stanowiska do badań obróbki elektrochemicznej powierzchni krzywoliniowych, (Electrochemical machining for curvilinear surfaces research station design), Prace naukowe SNOE, z.14, PAN KBM SPT, Warszawa 2008. [11] T. Paczkowski, J. Zdrojewski, Monitoring and control of the electrochemical machining process under the conditions of a vibrating tool, Journal of Materials Processing Technology. 244 (2017) 204–214. [12] T. Paczkowski, J. Zdrojewski, The Mechanism of ECM Technology Design for Curvilinear Surfaces, 18th CIRP Conference on Electro Physical and Chemical Machining (ISEM XVIII), Procedia CIRP, 42 (2016): 356-361.
Available online at www.sciencedirect.com
Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procedia online Manufacturing 00 (2018) 204–209
www.elsevier.com/locate/procedia
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia
Procedia Manufacturing 22 (2018) 196–201 Procedia Manufacturing 00 (2017) 000–000
www.elsevier.com/locate/procedia 11th International Conference Interdisciplinarity in Engineering, INTER-ENG 2017, 5-6 October 2017, Tirgu-Mures, Romania 11th International Conference Interdisciplinarity in Engineering, INTER-ENG 2017, 5-6 October 2017, Tirgu-Mures, Romania
Control of the research stand for electrochemical machining Control Engineering of the research standa, for electrochemical machining b, Manufacturing Society International Conference 2017, MESIC 2017, 28-30 June Jarosław Zdrojewski Tomasz Paczkowski * 2017, Vigo (Pontevedra), Spain P
P
P
P0F
Jarosław Zdrojewskia, Tomasz Paczkowskib, *
a
Department of Digital Technology, Faculty of Telecommunications and Electrical Engineering , UTP, 85-796, Bydgoszcz, Poland Department of Production Engineering, Faculty of Mechanical Engineering, University of Science and Technology, Bydgoszcz, Poland a Department of Digital Technology, Faculty of Telecommunications and Electrical Engineering , UTP, 85-796, Bydgoszcz, Poland b Department of Production Engineering, Faculty of Mechanical Engineering, University of Science and Technology, Bydgoszcz, Poland P
P
P
b
P
P
P0F
Costing models for capacity optimization in Industry 4.0: Trade-off between used capacity and operational efficiency P
P
P
P
P
P
Abstract
A. Santana , P. Afonso , A. Zanin , R. Wernke Abstract The paper presents control method of the research process for erosion machining and construction of the stand. The stand has a modular design, with separated electrodes drive and machining area,Guimarães, which greatly expands its research capabilities. The stand University of Minho, 4800-058 Portugal b The paper ispresents control methodparameters of the research for machining and construction of the stand. The standThis has controller supplying machining and itprocess consists of erosion a Chapecó, PC program communicating with the PLC I/O modules. Unochapecó, 89809-000 SC, Brazil modular design, with separated electrodes and machining area, which expands its research capabilities. stand arrangement allows initial referencing of thedrive electrodes before machining and,greatly based on measurements of the electrolyteThe pressure, controller is supplying machining and of it consists of a electrode, PC program communicating with the PLC synchronization I/O modules. This on-line control for parameters suchparameters as: feed rate the working electrode oscillation frequency, of arrangement allows initial referencing of the machining and,machining based on measurements the type electrolyte pressure, electrodes oscillation, the inter electrodes gapelectrodes thickness.before Conducting erosion experiments onofthis of stand allows Abstract on-line for parameters as: process feed rateand of lets the to working oscillation frequency, synchronization of to verifycontrol a mathematical modelssuch of the developelectrode, an activeelectrode type of on-line control, connecting the theoretical electrodes the inter electrodesduring gap thickness. Conducting erosion machining experiments on this type of stand allows results withoscillation, measurements of parameters machining. to verifythe a mathematical of the process and lets toprocesses develop anwill active of on-line connecting the theoretical Under concept of models "Industry 4.0", production be type pushed to becontrol, increasingly interconnected, results of parameters during © 2018with The measurements Authors. Published by Elsevier B.V.machining. information based on a real time basis and, necessarily, much more efficient. In this context, capacity optimization Peer-review under responsibility ofof thecapacity scientificmaximization, committee of the 11th International Conference Interdisciplinarity goes beyondAuthors. the traditional aim contributing also for organization’s profitabilityinand value. © Published by B.V. © 2018 2018 The The Authors. Publishedand by Elsevier Elsevier B.V. improvement approaches suggest capacity optimization instead of Engineering. Indeed, lean management continuous Peer-review under responsibility of the scientific committee of the 11th International Conference Interdisciplinarity in Engineering. Peer-review under responsibility of the scientific committee of the 11th International Conference Interdisciplinarity in maximization. The study of capacity optimization and costing models is an important research topic that deserves Engineering. Keywords: electrochemical machining; computer simulation; border states; ECM machining experiments; active on-line control. a
a,*
b
b
contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model forelectrochemical capacity management based on different costing (ABC experiments; and TDABC). generic model has been Keywords: machining; computer simulation; border states;models ECM machining activeA on-line control. developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s 1. Introduction value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity optimization might hide operational inefficiency. 1. Introduction Technological evolution is the cause for industrial use of materials that are harder, more durable, and resistant to
© 2017 The Authors. Published by Elsevier B.V. corrosion, high temperatures and other factors. At the same time, high quality standards are set, most frequently in Peer-review under responsibility thecause scientific Technological evolution isofthe for committee industrial of usetheofManufacturing materials thatEngineering are harder,Society more International durable, andConference resistant to 2017.
corrosion, high temperatures and other factors. At the same time, high quality standards are set, most frequently in
Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency
* Corresponding author. Tel.: +48-523-408-130; fax: +48-523-408-030.
1.E-mail Introduction address: [email protected]
* Corresponding author. Tel.: +48-523-408-130; fax: +48-523-408-030. The cost of idle capacity is a fundamental for companies and their management of extreme importance E-mail address: [email protected] 2351-9789 © 2018 The Authors. Published by Elsevier information B.V. Peer-review responsibility of theInscientific committee of the 11th International Conference Interdisciplinarity in Engineering. in modern under production systems. general, it is defined as unused capacity or production potential and can be measured 2351-9789 2018 The Authors. Published by Elsevier B.V.hours of manufacturing, etc. The management of the idle capacity in several©ways: tons of production, available Peer-review underTel.: responsibility the761; scientific committee the 11th International Conference Interdisciplinarity in Engineering. * Paulo Afonso. +351 253 of 510 fax: +351 253 604of741 E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 11th International Conference Interdisciplinarity in Engineering. 10.1016/j.promfg.2018.03.030
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
197 205
terms of macro and micro-geometric structure parameters, in relation to machined surfaces, including curvilinear surfaces as well. Erosive machining, and especially electro-discharge machining (EDM) and electrochemical machining (ECM), effectively solve numerous problems connected with the machining process, since they give the possibility of machining parts with complex shapes and made out of troublesome, current-conducting materials. The main method in EDM, and especially in ECM, is drilling with a tool electrode. In an EDM process, removal of material from machined part occurs through erosion due to electrical discharges between the electrodes in a fluid state of the dielectric environment. Erosion products are expelled into the dielectric as a stream of liquid metal [3, 5]. In the case of ECM, the process is based on the phenomenon of anode dissolving of the machined surface, therefore the Machined Item (MI) should be connected to the positive pole of DC source, and the Tool Electrode (TE) to the negative one. To the inter-electrode gap (IEG) electrolyte is injected under pressure, conducting electric current in the form of water solutions of acids and bases. Secretion of machining products on the machined item electrode causes the electrolyte conductivity to be variable in time [1, 6]. ECM research confirm the complexity of phenomena connected with the internal structure of electrochemical machining. They include electrode processes, carrying of the electric charge, momentum and energy mass transfer, hydrodynamics and others [1-2, 6]. Described technologies place high importance on research on model research stations. Such research allows to define technological characteristics, necessary for conducting computer simulations, and deviations between conducted computer simulations and experimental research. Acquired results will allow for eventual correction of mathematical and software models [12]. 2. Research station construction During the designing of the research station its modular build was assumed [10]. Inputs and outputs were identified [4]. It was assumed, that the machining process will be realized in so called machining units, constituting a separate construction set (Fig.1). The use of machining units allows unlimited modeling of the machining chamber, so that the process can be conducted in model conditions. Machining units are fixed onto the station body, which is responsible for the realization of complex electrode kinematics: • machining with a tool electrode, • machining with a tool electrode vibrating across the IEG, • machining with a tool electrode vibrating along the IEG, • machining with a tool electrode with a complex vibrating movement possibility of its synchronization, • machining with a tool electrode with the possibility of inducing rotary motion.
Fig. 1. Machining unit: 1 – machined item, 2 - tool electrode, 3 – gaps leading the electrolyte to the IEG.
The body of the research station is made up from four plates mounted on leading columns (Fig. 2). Two farthest plates 1 and 2 are bound to leading columns 3 permanently, and two middle plates 4 and 5 are mounted in a sliding way, realizing set kinematic movements as: • First point downward feed motion, • And so on vibrating motion alongside IEG.
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
198 206
Fig. 2. Research station body.
Vibrating motion alongside IEG is realized with the use of the mechanism placed on the top mobile plate. Specific drive systems are presented in Table 1. Table 1. Station drive systems. Drive
ID
Location
Main tool electrode feed V f speed Servo drive
1
Lead screw with toothed belt drive
2
Mobile plate mounted on leading columns
3
Transverse tool electrode vibrations drive: Servo drive with an eccentric cam
1
Support mounted through rails on mobile plate
2
Support pressure on the eccentric cam
3
Longitudinal electrode vibrations drive: servo drive with an eccentric cam
1
vibrating beam with thrusters
2
beam pressure on the eccentric cam
3
thruster
4
mobile plate mounted on leading columns
5
In the case of erosion machining the station must be equipped in systems of DC power supply and electrolyte supply. 3. Station control system Station control and process monitoring takes through a special created ExECM program for a PC. Basic functions of the ExECM program are presented in Tab 2.
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
199 207
Table 2. Functions of the ExECM program. Function
Software details
Vertical oscillation and Horizontal oscillation: Enable initialization the drives through passing to limit switches and turning on correct oscillations, and their mutual synchronization with a set phase shift. Oscillation – remembered positions: Enables remembering six different mutual locations of eccentric cams which are the starting point for electrode vibration synchronization. Electrode– remembered positions: Enables setting of IEG value through recording six different mutual positions of the tool electrodes. Useful in research with multiple repetitions. Movement from the electrode: Enables setting a velocity and time for the machining. Start and stop execution: The field for starting the test panel, stopping or exiting the program.
Synchronization of vertical (along IEG width) and horizontal (alongside IEG) vibrations is possible due to the use of optical sensors. Thanks to the optical sensors, after launching the drives responsible for each of the vibration modes, the basing of eccentric cams and then their rotation by a set value of the angular displacement of vibration. In the last field of the software, a possibility of testing communication and "manual" drive control is provided. For this purpose, a VECM panel-communication tester was created (Fig. 3). The base tasks of the panel are: • start-up tool, allowing for individual control of the axes. Basing, movement to a set position or immediate stop. It allows verification of end switches functioning, initial axis positioning in the motion range, or movement to a set position for a set modifiable feed; • station service tester, tasks as above. Used in case of a breakdown for restoration of functionalities.
Fig. 3. VECM panel - communication tester and communication code sample (initialize and move axis).
200 208
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
System for monitoring and control of machining process parameters was designed basing on the Mitsubishi FX 3U controller and a PC. FX 3U controller was places alongside other necessary controlling and safety elements in the controls cabinet. The system comprises of (Fig. 4): • PC computer with implemented ExECM program 1, • controls cabinet: • servo for each axis - 2, 3, 4, • Mitsubishi FX 3U controller with in/out FX 3U-232-BD mode - 5, • other elements necessary for the functioning of the system, such as: VS 116K relays, contactors, 24V DR 7524 power supply, power protection, • DC motors (servo drives) 6, • electrolyte pressure sensors 7, • end switches 8, • optical sensor 9.
Fig. 4. Control and monitoring system of machining process parameters.
It should be underlined, that presented servo-drive control system enables them to work with a constant feed speed and constant load. Consequently, depending on set mode process research can be conducted maintaining a constant machining speed or constant average pressure in the IEG. Next to the mechanic system we can distinguish the following components of the station (Fig. 5): • electrolyte feed speed, • DC power supply.
Fig. 5. Erosion machining research station (1 - electrolyte feed speed, 2 - DC power supply).
Jarosław Zdrojewski et al. / Procedia Manufacturing 22 (2018) 196–201 Jarosław Zdrojewski and Tomasz Paczkowski / Procedia Manufacturing 00 (2018) 204–209
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4. Conclusions Presented research station enables researchers to deepen the knowledge about erosion machining processes conducted in conditions with complex electrode kinematics. It mainly applies to machining of complex surfaces with curvilinear generators. In case of such surfaces, the removal of machining products from the inter-electrode gap is highly difficult. These difficulties often lead to the so called machining critical states, that is the occurrence of electrical discharge (in the case of ECM), the occurrence of an electric arc, or electrode short circuit [7]. It is mainly connected to electrochemical machining, in which products of dissolution change the machining parameters along the inter-electrode gap in a significant degree. These factors cause difficulties in defining machining parameters and in designing the right shape of the cathode tool surface. One of the factors that influence the stability of machining is induction of tool electrode vibrations. Such vibrations lead to interruption of the pre short-circuit processes and at the same time allow periodical rinsing of the machining area. Analysis of electrolyte pressure measurements additionally enables on-line modifications of the controllable machining parameters: ER feed speed, electrode vibrations frequency, electrode vibrations synchronization, IEG width. Achieved results form a basis for development of various kinds of mathematical modelling concepts for the machining, and bilateral joining of such theoretical models with the process controls [8,9,11]. It should be stressed that all the research possibilities presented above can be freely developed due to the modular build of the station and the use of programmable controllers. References [1] L. Dąbrowski, Podstawy komputerowej symulacji kształtowania elektrochemicznego, (Computer simulation basics of electrochemical shaping), Prace Naukowe, Mechanika, z. 154, Wydaw. Politechniki Warszawskiej, Warszawa, 1992. [2] L. Dąbrowski, T. Paczkowski, Computer simulation of two-dimensional electrolyte flow in electrochemical machining, Russian Journal of Electrochemistry. 41(1) (2005) 91-98.. [3] L. Dąbrowski, R. Świercz, Struktura metalograficzna powierzchni po obróbce elektroerozyjnej, (Metallographic structure of the surface after electro-erosion machining), Inżynieria Maszyn. 16 (2011): 16-23. [4] J. Ditrich, System i konstrukcja, (System and design), Warszawa WNT, 1980. [5] M. Gostimirovic, P. Kovac, Influence of dis charge energy on machining characteristics in EDM, Journal of Mechanical Science and Technology. 6(1) (2012) 173-179. [6] J. Kozak, Kształtowanie powierzchni obróbką elektrochemiczną bezstykową (ECM), (Surface shaping by contactless electrochemical machining), Pr. Naukowe PW, Mechanika nr 41, Wydawnictwo Politechniki Warszawskiej, Warszawa, 1976. [7] K. Łubkowski, Stany krytyczne w obróbce elektrochemicznej, (Critical states in electrochemical machining), Prace naukowe, Mechanika, z.163, Oficyna Wydawnicza PW, Warszawa, 1996. [8] T. Mikolajczyk, T. Fas, A. Klodowski, M. Matuszewski, A. Olaru, S. Olaru, Computer Aided System for Superfinishing Process Control, Procedia Technology. 22 (2016) 48-54 [9] T. Paczkowski, J. Zdrojewski, Boundary conditions analysis of ECM machining for curvilinear surfaces, Journal of POLISH CIMAC. 6(3) (2011) 193-198. [10] T. Paczkowski , Konstrukcja stanowiska do badań obróbki elektrochemicznej powierzchni krzywoliniowych, (Electrochemical machining for curvilinear surfaces research station design), Prace naukowe SNOE, z.14, PAN KBM SPT, Warszawa 2008. [11] T. Paczkowski, J. Zdrojewski, Monitoring and control of the electrochemical machining process under the conditions of a vibrating tool, Journal of Materials Processing Technology. 244 (2017) 204–214. [12] T. Paczkowski, J. Zdrojewski, The Mechanism of ECM Technology Design for Curvilinear Surfaces, 18th CIRP Conference on Electro Physical and Chemical Machining (ISEM XVIII), Procedia CIRP, 42 (2016): 356-361.