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1

Badania stanu łożysk tocznych w maszynach technologicznych z wykorzystaniem metody impulsu uderzeniowego (SPM)

Miska Maciej, Gruszecki Wojciech, Żyłka Wojciech

Obróbka Metalu

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2024

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nr 2

34--43

PL

Przedstawiono metody monitorowania stanu łożysk tocznych z wykorzystaniem metody SPM. Przedstawiono także analizę wskazanych tą metodą różnic między działaniem nowego łożyska i używanego, stosowanych we wrzecionach maszyn technologicznych. Testy przeprowadzono przy użyciu oprogramowania Simcenter Testlab Software oraz urządzenia Leonova Emerald. Stwierdzono, że metody SPM stosowane w wykorzystywanych urządzeniach umożliwiają szybką i skuteczną detekcję uszkodzeń.

EN

Methods for monitoring the condition of rolling bearings (and the same-whole machine) using the SPM method were presented. There is also an analysis of the differences between the performance of a new bearing and an already used one, used in the spindles of processing machines. The tests were conducted using Simcenter Testlab Software and Leonova Emerald. The methods used in SPM devices allowed for fast and effective detection of existing defects.

2

Strategy for Compensation of Thermally Induced Displacements in Machine Structures Using Distributed Temperature Field Control

Pöhlmann Patrick, Müller Jens, Ihlenfeldt Steffen

Journal of Machine Engineering

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2024

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Vol. 24, No. 3

5--16

EN

Thermal deformation is a major source of machining errors in modern machine tools. In addition to optimising the machine structure, correcting the axis position values in the numerical control is a common measure to reduce these errors. Another possibility is to directly influence the temperature field of the machine tool in the process, which requires a complex thermo-elastic modelling approach as well as appropriate thermal actuation and measurement capabilities. This paper presents a strategy for controlling the temperature field based on the eigenmodes of the thermal system. The various aspects of the concept are explained using a finite element model of an exemplary structural component. The basis is the modal analysis of the thermal system, which allows the temperature field to be described by independent discrete states. In addition to the placement of thermal sensors and actuators, this work focuses on the design of a suitable control approach. Transient simulation results are used to clearly demonstrate the performance of this method.

3

Investigation of Tool Cooling and Heat Transfer Using Computational Fluid Dynamics Simulations

Naumann Christian, Schmidt Claus-Dieter, Geist Alexander, Brier Steffen, Glänzel Janine, Klimant Philipp, Ihlenfeldt Steffen, Dix Martin

Journal of Machine Engineering

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2024

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Vol. 24, No. 4

5--26

EN

Thermal errors remain one of the biggest challenges for the precision of cutting machine tools. Aside from optimizations in the machine tool design and behaviour, optimal cutting process parameters and targeted usage of cutting fluid or alternative methods of tool cooling are required for improved process efficiency with minimal energy demand and maximal tool life. A simulation-based study is presented which compares both different methods of tool cooling, specifically air cooling, flooded cooling and minimum quantity lubrication and also different simulation methods and models. Using a case study, which models an existing thermal test stand comprised of motor spindle, tool holder, tool and coolant nozzle, different cooling scenarios were tested and compared. The simulations were performed in ANSYS CFX. Comparisons were made between simulations with and without buoyancy, with and without tool rotation, transient and steady-state, with laminar flow and with different turbulence models and between the different cooling scenarios. Some insight on different time step sizes and the resulting increase in simulation time and precision was also gained. These results will make future studies on the thermal behaviour of both tool and cutting process easier by showing suitable simulation techniques and viable model simplifications.

4

Development of FEM thermal simulation technology for machine tool with enclosures and its application

Tanabe Ikuo, Suzuki Naohiko, Ishino Yoshiaki, Isobe Hiromi

Journal of Machine Engineering

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2024

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Vol. 24, No. 1

17--28

EN

These days, most machine tools are interlocked by an enclosure for safety control. At that time, internal heat generation in machine tools first causes thermal deformation of the machine structure, which reduces the machining accuracy of the workpiece. Furthermore, the internal heat generation heats the air inside the enclosure, causing a heat build-up phenomenon, and the trapped heat causes re-thermal deformation of the machine tool structure. As a result, machine tools with enclosures are subject to extremely complex thermal deformation. On the other hand, we would like to use FEM thermal simulation to study thermal deformation countermeasures for machine tools with enclosures at the design stage, but it is difficult to analyse the heat build-up phenomenon usingconventional FEM thermal simulation. In this research, the new FEM thermal simulation technology for the heat build-up phenomenon was developed and heat build-up phenomenon in a CNC lathe with enclosure was calculated using the proposed FEM simulation technology. As a result, it had been concluded that the proposed FEM simulation could calculate with high accuracy for the phenomenon of heat build-up in a CNC lathe with enclosure, and the proposed technology is very effective in the design.

5

Concept of Integrating a Hybrid Thermal Error Compensation Into an Existing Machine Tool Control Architecture

Geist Alexander, Yaqoob Muhammad Faisal, Friedrich Christian, Naumann Christian, Ihlenfeldt Steffen

Journal of Machine Engineering

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2024

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Vol. 24, No. 3

32--36

EN

Thermal error compensation via a numeric control (NC) system is a proven option for upgrading the precision of machine tools. The main advantage is the generally cost-effective application, as no changes to the machine design are necessary. Since modern machine tools are equipped with standard numeric controls along with additional functions and integrated temperature sensors in the machine, compensation methods such as a characteristic diagram (CD) based compensation can be implemented. To increase the applicability and reliability of this CD regression method, a hybrid model approach with a virtual thermo-elastic finite element (FE) machine model and a real-time computable structural model of a machine tool was developed. The structural model uses model order reduction to calculate the current load case in real-time using continuously recorded machine data (motor current, axis position, temperatures). It acts as a virtual monitoring application to check, whether the current machine condition still matches the current CD based prediction. If the current load case is not suitable to the active CDs or any other stored CDs, the generation of new CDs is automatically triggered. In this article, the integration of the hybrid compensation method using an FE model and a structural model of a machine tool is methodically demonstrated. The main focus is on the integration of different software and hardware architectures and their interaction.

6

Wykorzystanie obróbki plastycznej we współczesnych procesach wytwórczych

Styp-Rekowski Michał, Matuszewski Maciej, Polishchuk Oleg

Obróbka Metalu

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2023

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nr 2

52--57

PL

W artykule wskazano cechy obróbki plastycznej, które powodują, że ta technika obróbki jest szeroko stosowana we współczesnych procesach produkcyjnych. Ukazano także możliwości wspomagania tego rodzaju obróbki innymi technikami, np. laserem, w wyniki czego realizowane procesy nabierają charakteru hybrydowego. Zaprezentowano maszyny, narzędzia i procesy technologiczne, które powodują takie duże zainteresowanie tą techniką ze strony przemysłu.

EN

In this paper the features of plastic forming that make this processing technique widely used in modern production processes were described . The possibilities of supporting this type of processing with other techniques, e. g. laser, were also shown. The reason for this is that the implemented processes becoming a hybrid character. Machines, tools and technological processes that cause such great interest in this technology from the industry were presented.

7

Uncertainty evaluation of multilateration-based geometric error measurement considering the repeatibility of positioning of the machine tool

Liu Xingbao, Xia Yangqiu, Rui Xiaoting

Metrology and Measurement Systems

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2023

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Vol. 30, nr 1

49--63

EN

The sequential multilateration principle is often adopted in geometric error measurement of CNC machine tools. To identify the geometric errors, a single laser tracker is placed at different positions to measure the length between the target point and the laser tracker. However, the measurement of each laser tracker position is not simultaneous and measurement accuracy is mainly subject to positioning repeatability of the machine tool. This paper attempts to evaluate the measurement uncertainty of geometric errors caused by the positioning repeatability of the machine tool and the laser tracker spatial length measurement error based on the Monte Carlo method. Firstly, a direct identification method for geometric errors of CNC machine tools based on geometric error evaluation constraints is introduced, combined with the geometric error model of a three-axis machine tool. Moreover, uncertainty contributors caused by the repeatability of positioning of numerically controlled axes of the machine tool and the laser length measurement error are analyzed. The measurement uncertainty of the geometric error and the volumetric positioning error is evaluated with the Monte Carlo method. Finally, geometric error measurement and verification experiments are conducted. The results show that the maximum volumetric positioning error of the machine tool is 84.1 μm and the expanded uncertainty is 5.8 μm (𝑘 = 2). The correctness of the geometric error measurement and uncertainty evaluation method proposed in this paper is verified compared with the direct geometric error measurement methods.

8

Recent advances in precision, sustainability and safety of machine tools

Uhlmann Eckart

Journal of Machine Engineering

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2023

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Vol. 23, No. 3

5--25

EN

Machine tools are the main driver of economic, environmental and social sustainability in industrial production. The ongoing shift from mass production to highly individualized, small batch manufacturing requires machine tools to be more flexible to changing needs while maintaining at least the same level of productivity. However, flexibility and productivity are at odds with the necessity for resource and energy efficiency. At the same time, more sophisticated workpiece specifications are pushing the boundaries regarding precision and dynamics of machine tools. In such a high-performance context, machine safety plays a major role and is becoming increasingly challenging due to higher kinetic energies of moving components. This paper examines recent advances in machine tool precision, sustainability, and safety. Six comprehensive case studies are provided to illustrate how these improvements contribute to an increased productivity. Hardware and software solutions for pose-controlled robotic manufacturing and thermoelectrically tempered high-performance spindles will be presented. Modular machine tool frames based on building blocks and an adaptive cooling system with thermoelectric generators for linear direct drives demonstrate their major impact on resource and energy efficiency. Machine safety is addressed through an analysis of potential hazards as well as improved protective measures. Model-based predictions precisely identify critical process parameters that lead to unbalance-induced failure of slim tool extensions, while on the protection side, new statistical models are applied to assess the protective performance of safeguards much more accurately. The cutting-edge technologies for machine tools presented in this paper will help manufacturers to cope with current and future challenges in industrial production.

9

Handling ambient temperature changes in correlative thermal error compensation

Naumann Christian, Geist Alexander, Putz Matthias

Journal of Machine Engineering

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2023

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Vol. 23, No. 4

43--63

EN

Thermal errors are one of the leading causes for positioning inaccuracies in modern machine tools. These errors are caused by various internal and external heat sources and sinks, which shape the machine tool’s temperature field and thus its deformation. Model based thermal error prediction and compensation is one way to reduce these inaccuracies. A new composite correlative model for the compensation of both internal and external thermal effects is presented. The composite model comprises a submodel for slow long- and medium-term ambient changes, one for short-term ambient changes and one for all internal thermal influences. A number of model assumptions are made to allow for this separation of thermal effects. The model was trained using a large number of FE simulations and validated online in a five-axis machine tool with measurements in a climate chamber. Despite the limitations, the compensation model achieved good predictions of the thermal error for both normal ambient conditions (21°C) and extreme ambient conditions (35°C).

10

An investigation of the relationship between encoder difference and thermo-elastic machine tool deformation

Brecher Christian, Dehn Mathias, Neus Stephan

Journal of Machine Engineering

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2023

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Vol. 23, No. 3

26--37

EN

New approaches, using machine learning to model the thermo-elastic machine tool error, often rely on machine internal data, like axis speed or axis position as input data, which have a delayed relation to the thermo-elastic error. Since there is no direct relation to the thermo-elastic error, this can lead to an increased computation inaccuracy of the model or the need for expensive sensor equipment for additional input data. The encoder difference is easy to obtain and has a direct relationship with the thermo-elastic error and therefore has a high potential to improve the accuracy thermo-elastic error models. This paper first investigates causes of the encoder difference and its relationship with the thermo-elastic error. Afterwards, the model is presented, which uses the encoder difference to compute the thermo-elastic error. Due to the complexity of the relationship, it is necessary, to use a machine learning approach for this. To conclude, the potential of the encoder difference as an input of the model is evaluated.

11

Orthotropic model of rolling bearing in modeling lathe spindle dynamics

Tomaszewski Jan, Dunaj Paweł, Powałka Bartosz, Jasiewicz Marcin

Journal of Theoretical and Applied Mechanics

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2022

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Vol. 60 nr 1

17--31

EN

This paper presents a method for simplified modeling of bearing nodes of a lathe spindle using the finite element method. The proposed modeling methodology is based on the use of an orthotropic material model, which is used to reflect the stiffness properties of the bearing, both in the radial and axial directions. The modeling results have been experimentally verified. This resulted in full agreement of the mode shapes, an average relative error of the natural frequency values of 1.48% and high agreement of the receptance function.

12

Spatial compliance measurement of a clamping table with integrated force sensors

Friedrich Christian, Ihlenfeldt Steffen

Journal of Machine Engineering

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2022

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Vol. 22, No. 1

70--83

EN

Force sensor integration into machine components is a promising approach to measure spatial process forces, especially, when regarding hexapod structures and kinematics. Rigid still-standing hexapod frameworks, such as clamping tables, are particular suitable for this approach, as no dynamic influences need to be taken into account within the measurement model and they allow a measurement in 6 degrees of freedom. On the other hand, the stiffness of rigid frameworks is reduced by force sensor integration significantly. In addition, many approaches apply joints or flexure hinges to reduced lateral forces and improve the measuring quality, which reduce the stiffness even more. In this contribution, the compliance of a clamping table with integrated force sensors and flexure hinges is determined by experimental measurements using a multiline laser interferometer, by analytic calculation, and by finite element simulation. In conclusion, the amount of stiffness reduction by force sensors and flexure hinges is quantified and different methods for compliance determination are compared.

13

Optimization of characteristic diagram based thermal error compensation via load case dependent model updates

Naumann Christian, Glänzel Janine, Dix Martin, Ihlenfeldt Steffen, Klimant Philipp

Journal of Machine Engineering

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2022

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Vol. 22, No. 2

43--56

EN

The compensation of thermal errors in machine tools is one of the major challenges in ensuring positioning accuracy during cutting operations. There are numerous methods for both the model-based estimation of the thermal tool center point (TCP) deflection and for controlling the thermal or thermo-elastic behavior of the machine tool. One branch of thermal error estimation uses regression models to map temperature sensors directly onto the TCP-displacement. This can, e.g., be accomplished using linear models, artificial neural networks or characteristic diagrams. One of the main limitations of these models is the poor extrapolation behavior with regard to untrained load cases. This paper presents a new method for updating characteristic diagram based compensation models by combining existing models with new measurements. This allows the optimization of the compensation for serial production load cases without the effort of computing a new model. The new method was validated on a 5-axis machining center.

14

Integration of OPC UA information models into Enterprise Knowledge Graphs

Weiss Arno, Ihlenfeldt Steffen

Journal of Machine Engineering

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2022

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Vol. 22, No. 2

138--147

EN

Building repositories of data relevant for enterprise operations requires harmonization of formats and semantics. OPC UA’s nodes-and-references data model shares basic elements with well-established semantic modeling technologies like RDF. This paper suggests the use of transformed OPC UA information models on the higher level of Enterprise Knowledge Graphs. It proposes good practice to integrate the separate domains by representing OPC UA servers as RDF-graphs and subsequently attaching them to Digital Twins embedded in Enterprise Knowledge Graph structures. The developed practice is implemented, applied to combine a server’s structure with an existing knowledge graph containing an Asset Administration Shell and released open source.

15

Accuracy assessment of articulated industrial robots using the Extended- and the Loaded-Double-Ball-Bar

Marwitz Johann August, Theissen Nikolas Alexander, Gonzalez Monica Katherine, Friedrich Christian, Hellmich Arvid, Archenti Andreas, Ihlenfeldt Steffen

Journal of Machine Engineering

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2022

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Vol. 22, No. 2

80--98

EN

This research paper outlines the methodology and application of geometric and static accuracy assessment of articulated industrial robots using the Extended Double Ball Bar (EDBB) as well as the Loaded Double Ball Bar (LDBB). In a first experiment, the EDBB is used to assess the geometric accuracy of a Comau NJ-130 robot. Advanced measuring trajectories are investigated that regard poses or axes configurations, which maximize the error influences of individual robot components, and, in this manner, increase the sensitivity for a large number of individual error parameters. The developed error-sensitive trajectories are validated in experimental studies and compared to the circular trajectories according to ISO 203-4. Next, the LDBB is used to assess an ABB IRB6700 manipulator under quasi-static loads of up to 600 Newton using circular testing according to ISO 230-4. The stiffness is identified from the loaded circular trajectories. Then, the stiffness is used to perform a reverse calculation to identify the kinematic errors on the path deviations. The concept is validated in a case study of quasi-static loaded circular testing using the LDBB compared to a Leica AT960 laser tracker (LT).

16

Systemy mocowania do obrabiarek

Świat Obrabiarek i Narzędzi

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2021

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R. 16, nr 1

13

17

Systemy mocowania do obrabiarek

Świat Obrabiarek i Narzędzi

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2021

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R. 16, nr 2

26

18

Modułowa konstrukcja MAXXTURN 65 G2

Świat Obrabiarek i Narzędzi

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2021

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R. 16, nr 3

31

19

JUNKER wyznacza nowe trendy w produkcji wałów wirnikowych

Świat Obrabiarek i Narzędzi

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2021

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R. 16, nr 3

30

20

Development and verification of a high-precision laser measurement system for straightness and parallelism measurement

Xu Peng, Li Rui Jun, Zhao Wen Kai, Chang Zhen Xin, Ma Shao Hua, Fan Kuang Chao

Metrology and Measurement Systems

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2021

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Vol. 28, nr 3

479--495

EN

A laser measurement system for measuring straightness and parallelism error using a semiconductor laser was proposed. The designing principle of the developed system was analyzed. Addressing at the question of the divergence angle of the semiconductor laser being quite large and the reduction of measurement accuracy caused by the diffraction effect of the light spot at the long working distance, the optical structure of the system was optimized through a series of simulations and experiments. A plano-convex lens was used to collimate the laser beam and concentrate the energy distribution of the diffraction effect. The working distance of the system was increased from 2.6 m to 4.6 m after the optical optimization, and the repeatability of the displacement measurement is kept within 2.2 m in the total measurement range. The performance of the developed system was verified by measuring the straightness of a machine tool through the comparison tests with two commercial multi-degree-of-freedom measurement systems. Two different measurement methods were used to verify the measurement accuracy. The comparison results show that during the straightness measurement of the machine tool, the laser head should be fixed in front of the moving axis, and the sensing part should move with the moving table of the machine tool. Results also show that the measurement error of the straightness measurement is less than 3 m compared with the commercial systems. The developed laser measurement system has the advantages of high precision, long working distance, low cost, and suitability for straightness and parallelism error measurement.