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Sascha Weikert

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Januarti Jaya Ekaputri

Institut Teknologi Sepuluh Nopember

Ecole Nationale Supérieure d'architecture de Nantes

Mataram University

Barzin Mobasher

Arizona State University

University of Waterloo

Shivamanth Angadi

JNTU , hyderabad

Università degli Studi "La Sapienza" di Roma

Vatwong Greepala

Kasetsart University

Future University ,Egypt.

University of East London

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Papers by Sascha Weikert

Mit Rekonfigurierbarkeit gewinnt der Anwender

Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Un... more Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Unternehmen ihre Produktion wettbewerbsfähiger machen müssen. Die notwendigen Optimierungen betreffen sowohl die Kosten als auch technisch-organisatorische Aspekte wie die Fähigkeit, innerhalb kürzester Zeit auf Änderungen der Auftragslage und -inhalte reagieren zu können. Um unter den verschärften Rahmenbedingungen in der Serienproduktion weiterhin bestehen zu können, werden wandelbare Fertigungsmittel benötigt. Unter Wandelbarkeit versteht man Flexibilität für Arbeiten und Reaktionen innerhalb eines vorgedachten Rahmens und Rekonfigurierbarkeit für Anpassungen an unvorhergesehene neue Anforderungen. Die Wandelbarkeit geht somit deutlich über das hinaus, was heutige Systeme bieten.

Comparison of rigid body mechanics and finite element method for machine tool evaluation

Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and qui... more Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and quickly changing business environments. New tools for efficient modelling of different machine variants are required in order to facilitate and accelerate the reconfiguration of machine tools. This paper presents a software tool which allows the evaluation of the performance and conformance to requirements of machine structure variants at an early stage. In contrast to computer-aided manufacturing (CAM) tools which process numerical control (NC) code to predict the tool trajectory, this tool calculates the static and simulates the dynamic properties of the machine structure as a basis for machine evaluation. Models of different structure variants are assembled using a module library, which contains models of the available physical modules. Thus, different variants can be set up and analysed efficiently, significantly improving the data basis on which important and far-reaching decisions have to be made. An example illustrates how the tool can be used for obtaining information on the physical machine properties and how to interpret the results. The presented software tool is part of a methodology for the reconfiguration process of reconfigurable, modular machine tools.

Multi Degree Of Freedom Measurement OfMachine Tool Movements

WIT transactions on engineering sciences, 1970

Modeling and evaluation tool for supporting decisions on the design of reconfigurable machine tools

Journal of Manufacturing Systems, Jul 1, 2007

Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and qui... more Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and quickly changing business environments. New tools for efficient modelling of different machine variants are required in order to facilitate and accelerate the reconfiguration of machine tools. This paper presents a software tool which allows the evaluation of the performance and conformance to requirements of machine structure variants at an early stage. In contrast to computer-aided manufacturing (CAM) tools which process numerical control (NC) code to predict the tool trajectory, this tool calculates the static and simulates the dynamic properties of the machine structure as a basis for machine evaluation. Models of different structure variants are assembled using a module library, which contains models of the available physical modules. Thus, different variants can be set up and analysed efficiently, significantly improving the data basis on which important and far-reaching decisions have to be made. An example illustrates how the tool can be used for obtaining information on the physical machine properties and how to interpret the results. The presented software tool is part of a methodology for the reconfiguration process of reconfigurable, modular machine tools.

Face-gear drive: Meshing efficiency assessment

Mechanism and Machine Theory, 2022

Berechnung von Kronenrädern für Auslegung und Fertigung

Modelling of Moving Interfaces for Reduced-Order Finite Element Models using Trigonometric Interpolation

Flexible multi-body simulation by means of reduced-order finite element models is gathering in im... more Flexible multi-body simulation by means of reduced-order finite element models is gathering in importance for the simulation of mechanical and mechatronic systems like, e.g. machine tools or handling systems. Moving of the system’s axes involves changing of the coupling position between flexible bodies, and thus, changing of the finite element nodes involved in an interface. Because modern model reduction techniques are based on matching properties of the system’s input-output behaviour, the order of the reduced model strongly depends on the number of interfaces used. Therefore, it is not appropriate to use all finite element nodes of a potential interface area as independent inputs. The subject of this paper is a method for modelling of moving interfaces to flexible bodies which is compatible with model order reduction. First, a formalism is presented which allows the application of distributed loads onto the nodal degrees of freedom of finite element nodes. Next, elementary load d...

Operator Integrated – Concept for Manufacturing Intelligence

Journal of Machine Engineering, 2021

Increasing autonomy and sustainability are major goals in manufacturing. Main technological trend... more Increasing autonomy and sustainability are major goals in manufacturing. Main technological trends provide enablers for achieving these goals and need to be implemented and combined in manufacturing machinery in a suitable manner. The paper exposes a vision of modern manufacturing machines, where the complexity of manufacturing processes is handled within the manufacturing machine and a simplistic front end is presented to the operator, which means that major elements of operators' tasks are fulfilled by the intelligence of the machine. Research vectors paving the ground for this concept from different points of view are then discussed. Research is presented on intelligent grinding, intelligent recognition and suppression of chatter, adaptive thermal and motion error compensation exploting also self-learning abilities. It is necessary to point out, that not only intelligent mastering of process and machine becomes more and more important but communications among machine tools enabling process chain overarching intelligent approaches and creating intelligent factories.

Acclimatisation time of precise workpieces for quality inspection

During manufacturing precise parts are machined under shop floor conditions. For quality inspecti... more During manufacturing precise parts are machined under shop floor conditions. For quality inspections these parts are brought into a measuring chamber. The research presented is a simulation study investigating the acclimatisation time of a machine tool bed brought from one functional room into another. The work deals with effects of thermal memory from any previous environment as explained in the thermal effects diagram of Bryan [1]. For the study a machine tool bed is either made of cast iron or polymer concrete. The boundary conditions required for the computations, for example the convective heat transfer coefficients, are derived from computational fluid dynamics (CFD) of the conditions in the air conditioned measuring chamber. The air temperature in the measuring chamber is controlled to 20 °C. Finite element method (FEM) is used to compute the temperature distribution over time and the thermally induced deformation of the bed. The deformations due to the temperature distributi...

Dynamic loads and thermal errors on machine tools

Thermal effects on machine tools are one of the major influences on machine tool accuracy. In ord... more Thermal effects on machine tools are one of the major influences on machine tool accuracy. In order to analyze the effects of thermal deformation, numerical analysis using FEM is a common procedure. The quality of the FE analysis largely depends on the accuracy of the boundary conditions. A common heat source is the friction in machine elements as guide ways, ball screws and bearings. The friction losses in these components generally depend on the loading. In this paper multibody dynamics is coupled with FEM to compute the dynamic loads and thermal errors on machine tools. Multibody dynamics system (MBS) is used to compute the loads which are used to derive the friction losses. These friction losses are then transferred to a thermomechanical FE model of the machine tool in order to calculate the thermal errors at the TCP (Tool Center Point).

Face-gear drive: Assessment of load sharing, transmission characteristics and root stress based on a quasi-static analysis

Mechanism and Machine Theory, 2020

Tooth contact analysis Load sharing Loaded static transmission error Flank contact pressure Tooth... more Tooth contact analysis Load sharing Loaded static transmission error Flank contact pressure Tooth root stress a b s t r a c t The present manuscript expands on a procedure developed to calculate load sharing, transmission characteristics, tooth root stress and the flank contact pressure in face-gear drives. On the one hand the procedure uses the analytical determination of the contact path for meshing of rigid gears including the dimensions, and directions of the contact ellipses based on Hertzian theory of elastic contact. On the other hand it uses the determination of the load-dependant compliance of a pair of teeth by finite element analysis. The combination of these two calculation methods / approaches renders the finite element contact analysis unnecessary thus significantly shortening the required computation time. The exact geometric representation of the tooth flanks for the finite element analysis is also not required. This not only avoids a greater preprocessing effort but also enables an efficient automation of the procedure. All steps of this procedure are described in depth in this manuscript. The accuracy of the proposed semi-analytical approach is validated through a direct comparison with an FEM contact analysis carried out as an example for a face-gear drive.

Age of Compensation – Challenge and Chance for Machine Tool Industry

International Journal of Automation Technology, 2016

This paper firstly gives an introduction to the development of machining accuracy, and the contem... more This paper firstly gives an introduction to the development of machining accuracy, and the contemporarily feasible compensations in the field of machine tools. The metrological means used for primarily static and kinematic compensations are discussed. Furthermore the focus is laid on the kinematic, dynamic and thermal compensation approaches, using various examples for these fields. The different phenomena to be compensated and the associated models are discussed in detail. As conclusions to be drawn, the repeatability of the systems, the ability of the models used in the CNC to represent the systematic behavior and the capabilities of the CNC can be seen as significant prerequisite for a successful application of compensation means.

Efficient Static and Dynamic Modelling of Machine Structures with Large Linear Motions

International Journal of Automation Technology, 2018

Mechatronic structures deform under static and dynamic loads. These deformations lead to deviatio... more Mechatronic structures deform under static and dynamic loads. These deformations lead to deviations at the tool center point (TCP), affecting the reachable accuracy and/or productivity of the machines. The scope of this work is the comparison of calculations and measurements of different static and dynamic errors on a dynamic test bench. A reduced-order modelling approach is applied for the test bench modelling. It uses a combination of modal condensation and moment-matching methods with Krylov subspaces. The different modelling steps and requirements are presented. The same model is used for all static and dynamic evaluations presented within this paper. Static deformations, leading to roll and pitch deviations at the TCP of the test bench structure, are simulated using the described modelling methodology and validated by inclination measurements. The modal behavior of the system is investigated by calculation and compared to the measurements at a single axes position. The spatial ...

Estimation of Dynamic Mechanical Error for Evaluation of Machine Tool Structures

International Journal of Automation Technology, 2012

Dynamic motion errors of machine tools consist of errors in the mechanical system and the servo s... more Dynamic motion errors of machine tools consist of errors in the mechanical system and the servo system. In this study, a simple method to estimate the dynamic mechanical error is proposed to evaluate machine tool structures. The dynamic mechanical error in the low frequency range is estimated from the static deformation due to the driving force, the counter force, and the inertial force. The error in a high-precision machine tool is estimated for comparison with measurements. Two calculation tools, finite element analysis and rigid multi-body simulation, are used for the estimation. Measured dynamic mechanical errors can be correctly estimated by the proposed method using finite element analysis. The tilt of driven bodies is the major reason for dynamic mechanical errors. When the reduction factor representing the structural deformation is properly determined, the rigid multi-body simulation is also an effective tool. Use of the proposed method for modification planning is demonstra...

Distribution of motion for five-axis machine tools utilising quasi-redundancy

International Journal of Mechatronics and Manufacturing Systems, 2016

A new approach for the distribution of motion for five-axis machine tools, using quasi-redundancy... more A new approach for the distribution of motion for five-axis machine tools, using quasi-redundancy given by the tolerance values of the rotational axes, is presented in this paper. Depending on the directional manufacturing tolerances for a geometry, the tolerance space is introduced. Allowing only small rotational tolerances, the nonlinear transformations are approximated using the small angle assumption. The optimisation problem is formulated as quadratic programming problem using B-Splines to represent the optimised solution. Based on two application examples, it is shown that the machining time and the machine excitation for desired machine axes can be reduced by the algorithm presented in this paper.

Adaptive learning control for thermal error compensation of 5-axis machine tools

Journal of Manufacturing Systems, 2017

This paper presents a prediction and compensation approach for thermal errors of 5-axis machine t... more This paper presents a prediction and compensation approach for thermal errors of 5-axis machine tools, based on supervised online machine learning. Process-intermittent probing is used to identify and update a thermal autoregressive with exogenous input (ARX) model. The approach is capable of predicting and compensating thermal displacements of the tool center point based on changes in the environmental temperature, load-dependent changes and boundary condition changes and states, like dry or wet machining. The self-optimized machine tool shows very stable long-term behavior under drastically varying machining and boundary conditions. The implementation is validated on a set of thermal test pieces. The test pieces show that the major share of thermal workpiece errors are reduced by the thermal adaptive learning control.

Comparison of rigid body mechanics and finite element method for machine tool evaluation

Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and qui... more Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and quickly changing business environments. New tools for efficient modelling of different machine variants are required in order to facilitate and accelerate the reconfiguration of machine tools. This paper presents a software tool which allows the evaluation of the performance and conformance to requirements of machine structure variants at an early stage. In contrast to computer-aided manufacturing (CAM) tools which process numerical control (NC) code to predict the tool trajectory, this tool calculates the static and simulates the dynamic properties of the machine structure as a basis for machine evaluation. Models of different structure variants are assembled using a module library, which contains models of the available physical modules. Thus, different variants can be set up and analysed efficiently, significantly improving the data basis on which important and far-reaching decisions have to be made. An example illustrates how the tool can be used for obtaining information on the physical machine properties and how to interpret the results. The presented software tool is part of a methodology for the reconfiguration process of reconfigurable, modular machine tools.

Mit Rekonfigurierbarkeit gewinnt der Anwender

Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Un... more Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Unternehmen ihre Produktion wettbewerbsfähiger machen müssen. Die notwendigen Optimierungen betreffen sowohl die Kosten als auch technisch-organisatorische Aspekte wie die Fähigkeit, innerhalb kürzester Zeit auf Änderungen der Auftragslage und -inhalte reagieren zu können. Um unter den verschärften Rahmenbedingungen in der Serienproduktion weiterhin bestehen zu können, werden wandelbare Fertigungsmittel benötigt. Unter Wandelbarkeit versteht man Flexibilität für Arbeiten und Reaktionen innerhalb eines vorgedachten Rahmens und Rekonfigurierbarkeit für Anpassungen an unvorhergesehene neue Anforderungen. Die Wandelbarkeit geht somit deutlich über das hinaus, was heutige Systeme bieten.

Beitrag zur Analyse des dynamischen Verhaltens von Werkzeugmaschinen

ich für die intensive Betreuung in Form fordernder Diskussionen, detaillierter Durch¬ sicht der A... more ich für die intensive Betreuung in Form fordernder Diskussionen, detaillierter Durch¬ sicht der Arbeit und Übernahme des Referats. Bei Herrn Prof. Meinrad K. Eberle möchte mich für die kritische Durchsicht der Arbeit und die Übernahme des Korreferates bedanken. Mein Dank gilt auch Herrn Dr. Friedrich Küster, dem Leiter des Sektors Maschinen, für die beflügelnden Diskussionen im Bereich der Maschinendynamik. Speziell zum Dank verpflichtet bin ich Herrn Dr. Wolfgang Knapp der diese Arbeit durch seine grosse Erfahrung und Unterstützung im Bereich der Maschinenmesstechnik wesentlich beeinflusst hat. Herrn Dr. Zdzislav Rak ist die numerische Umsetzung des Starrkörperansatzes zu ver¬ danken, der im Rahmen der Arbeit eine zentrale Bedeutung besitzt. Hierfür und für viele kritische Diskussionen bin ich ihm zu grossem Dank verpflichtet. Bei Herrn Dipl. Betr.-Ing. ETH Otto Doka möchte ich mich besonders für die einge¬ hende Betreuung im Bereich konstruktiver Arbeiten bedanken, dessen enormer Erfah¬ rung die Umsetzung des Hexaglides erst zu verdanken ist.

Correlation of Cutting Force and Power Consumption for Ultrasonic-Vibration-Assisted Cutting of Label Paper Stacks

Volume 3: Design, Materials and Manufacturing, Parts A, B, and C, 2012

ABSTRACT Experiments comparing conventional and ultrasonic vibration assisted guillotine cutting ... more ABSTRACT Experiments comparing conventional and ultrasonic vibration assisted guillotine cutting of paper stacks have been performed on plain and aluminum coated label paper. It is shown that ultrasonic vibration assisted cutting reduces the cutting force for both paper species. Reduction of the cutting force allows the down holder force to be decreased and lowers the compression of the paper stack necessary to prevent pull-out of the top sheets of paper. Using a higher amplitude setting on the ultrasonic generator further decreases the cutting force for the paper stack. For three different cutting speeds, it is shown that ultrasonic vibration assisted cutting force reduction depends on the average speed of the tool for both paper species. A linear regression with present experimental data is done to obtain an equation for the relation between input generator power and resulting cutting force. Finally, the quality of the cutting edge is examined, quality parameters are defined, and according to these the cutting edge quality is assessed.

Mit Rekonfigurierbarkeit gewinnt der Anwender

Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Un... more Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Unternehmen ihre Produktion wettbewerbsfähiger machen müssen. Die notwendigen Optimierungen betreffen sowohl die Kosten als auch technisch-organisatorische Aspekte wie die Fähigkeit, innerhalb kürzester Zeit auf Änderungen der Auftragslage und -inhalte reagieren zu können. Um unter den verschärften Rahmenbedingungen in der Serienproduktion weiterhin bestehen zu können, werden wandelbare Fertigungsmittel benötigt. Unter Wandelbarkeit versteht man Flexibilität für Arbeiten und Reaktionen innerhalb eines vorgedachten Rahmens und Rekonfigurierbarkeit für Anpassungen an unvorhergesehene neue Anforderungen. Die Wandelbarkeit geht somit deutlich über das hinaus, was heutige Systeme bieten.

Comparison of rigid body mechanics and finite element method for machine tool evaluation

Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and qui... more Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and quickly changing business environments. New tools for efficient modelling of different machine variants are required in order to facilitate and accelerate the reconfiguration of machine tools. This paper presents a software tool which allows the evaluation of the performance and conformance to requirements of machine structure variants at an early stage. In contrast to computer-aided manufacturing (CAM) tools which process numerical control (NC) code to predict the tool trajectory, this tool calculates the static and simulates the dynamic properties of the machine structure as a basis for machine evaluation. Models of different structure variants are assembled using a module library, which contains models of the available physical modules. Thus, different variants can be set up and analysed efficiently, significantly improving the data basis on which important and far-reaching decisions have to be made. An example illustrates how the tool can be used for obtaining information on the physical machine properties and how to interpret the results. The presented software tool is part of a methodology for the reconfiguration process of reconfigurable, modular machine tools.

Multi Degree Of Freedom Measurement OfMachine Tool Movements

WIT transactions on engineering sciences, 1970

Modeling and evaluation tool for supporting decisions on the design of reconfigurable machine tools

Journal of Manufacturing Systems, Jul 1, 2007

Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and qui... more Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and quickly changing business environments. New tools for efficient modelling of different machine variants are required in order to facilitate and accelerate the reconfiguration of machine tools. This paper presents a software tool which allows the evaluation of the performance and conformance to requirements of machine structure variants at an early stage. In contrast to computer-aided manufacturing (CAM) tools which process numerical control (NC) code to predict the tool trajectory, this tool calculates the static and simulates the dynamic properties of the machine structure as a basis for machine evaluation. Models of different structure variants are assembled using a module library, which contains models of the available physical modules. Thus, different variants can be set up and analysed efficiently, significantly improving the data basis on which important and far-reaching decisions have to be made. An example illustrates how the tool can be used for obtaining information on the physical machine properties and how to interpret the results. The presented software tool is part of a methodology for the reconfiguration process of reconfigurable, modular machine tools.

Face-gear drive: Meshing efficiency assessment

Mechanism and Machine Theory, 2022

Berechnung von Kronenrädern für Auslegung und Fertigung

Modelling of Moving Interfaces for Reduced-Order Finite Element Models using Trigonometric Interpolation

Flexible multi-body simulation by means of reduced-order finite element models is gathering in im... more Flexible multi-body simulation by means of reduced-order finite element models is gathering in importance for the simulation of mechanical and mechatronic systems like, e.g. machine tools or handling systems. Moving of the system’s axes involves changing of the coupling position between flexible bodies, and thus, changing of the finite element nodes involved in an interface. Because modern model reduction techniques are based on matching properties of the system’s input-output behaviour, the order of the reduced model strongly depends on the number of interfaces used. Therefore, it is not appropriate to use all finite element nodes of a potential interface area as independent inputs. The subject of this paper is a method for modelling of moving interfaces to flexible bodies which is compatible with model order reduction. First, a formalism is presented which allows the application of distributed loads onto the nodal degrees of freedom of finite element nodes. Next, elementary load d...

Operator Integrated – Concept for Manufacturing Intelligence

Journal of Machine Engineering, 2021

Increasing autonomy and sustainability are major goals in manufacturing. Main technological trend... more Increasing autonomy and sustainability are major goals in manufacturing. Main technological trends provide enablers for achieving these goals and need to be implemented and combined in manufacturing machinery in a suitable manner. The paper exposes a vision of modern manufacturing machines, where the complexity of manufacturing processes is handled within the manufacturing machine and a simplistic front end is presented to the operator, which means that major elements of operators' tasks are fulfilled by the intelligence of the machine. Research vectors paving the ground for this concept from different points of view are then discussed. Research is presented on intelligent grinding, intelligent recognition and suppression of chatter, adaptive thermal and motion error compensation exploting also self-learning abilities. It is necessary to point out, that not only intelligent mastering of process and machine becomes more and more important but communications among machine tools enabling process chain overarching intelligent approaches and creating intelligent factories.

Acclimatisation time of precise workpieces for quality inspection

During manufacturing precise parts are machined under shop floor conditions. For quality inspecti... more During manufacturing precise parts are machined under shop floor conditions. For quality inspections these parts are brought into a measuring chamber. The research presented is a simulation study investigating the acclimatisation time of a machine tool bed brought from one functional room into another. The work deals with effects of thermal memory from any previous environment as explained in the thermal effects diagram of Bryan [1]. For the study a machine tool bed is either made of cast iron or polymer concrete. The boundary conditions required for the computations, for example the convective heat transfer coefficients, are derived from computational fluid dynamics (CFD) of the conditions in the air conditioned measuring chamber. The air temperature in the measuring chamber is controlled to 20 °C. Finite element method (FEM) is used to compute the temperature distribution over time and the thermally induced deformation of the bed. The deformations due to the temperature distributi...

Dynamic loads and thermal errors on machine tools

Thermal effects on machine tools are one of the major influences on machine tool accuracy. In ord... more Thermal effects on machine tools are one of the major influences on machine tool accuracy. In order to analyze the effects of thermal deformation, numerical analysis using FEM is a common procedure. The quality of the FE analysis largely depends on the accuracy of the boundary conditions. A common heat source is the friction in machine elements as guide ways, ball screws and bearings. The friction losses in these components generally depend on the loading. In this paper multibody dynamics is coupled with FEM to compute the dynamic loads and thermal errors on machine tools. Multibody dynamics system (MBS) is used to compute the loads which are used to derive the friction losses. These friction losses are then transferred to a thermomechanical FE model of the machine tool in order to calculate the thermal errors at the TCP (Tool Center Point).

Face-gear drive: Assessment of load sharing, transmission characteristics and root stress based on a quasi-static analysis

Mechanism and Machine Theory, 2020

Tooth contact analysis Load sharing Loaded static transmission error Flank contact pressure Tooth... more Tooth contact analysis Load sharing Loaded static transmission error Flank contact pressure Tooth root stress a b s t r a c t The present manuscript expands on a procedure developed to calculate load sharing, transmission characteristics, tooth root stress and the flank contact pressure in face-gear drives. On the one hand the procedure uses the analytical determination of the contact path for meshing of rigid gears including the dimensions, and directions of the contact ellipses based on Hertzian theory of elastic contact. On the other hand it uses the determination of the load-dependant compliance of a pair of teeth by finite element analysis. The combination of these two calculation methods / approaches renders the finite element contact analysis unnecessary thus significantly shortening the required computation time. The exact geometric representation of the tooth flanks for the finite element analysis is also not required. This not only avoids a greater preprocessing effort but also enables an efficient automation of the procedure. All steps of this procedure are described in depth in this manuscript. The accuracy of the proposed semi-analytical approach is validated through a direct comparison with an FEM contact analysis carried out as an example for a face-gear drive.

Age of Compensation – Challenge and Chance for Machine Tool Industry

International Journal of Automation Technology, 2016

This paper firstly gives an introduction to the development of machining accuracy, and the contem... more This paper firstly gives an introduction to the development of machining accuracy, and the contemporarily feasible compensations in the field of machine tools. The metrological means used for primarily static and kinematic compensations are discussed. Furthermore the focus is laid on the kinematic, dynamic and thermal compensation approaches, using various examples for these fields. The different phenomena to be compensated and the associated models are discussed in detail. As conclusions to be drawn, the repeatability of the systems, the ability of the models used in the CNC to represent the systematic behavior and the capabilities of the CNC can be seen as significant prerequisite for a successful application of compensation means.

Efficient Static and Dynamic Modelling of Machine Structures with Large Linear Motions

International Journal of Automation Technology, 2018

Mechatronic structures deform under static and dynamic loads. These deformations lead to deviatio... more Mechatronic structures deform under static and dynamic loads. These deformations lead to deviations at the tool center point (TCP), affecting the reachable accuracy and/or productivity of the machines. The scope of this work is the comparison of calculations and measurements of different static and dynamic errors on a dynamic test bench. A reduced-order modelling approach is applied for the test bench modelling. It uses a combination of modal condensation and moment-matching methods with Krylov subspaces. The different modelling steps and requirements are presented. The same model is used for all static and dynamic evaluations presented within this paper. Static deformations, leading to roll and pitch deviations at the TCP of the test bench structure, are simulated using the described modelling methodology and validated by inclination measurements. The modal behavior of the system is investigated by calculation and compared to the measurements at a single axes position. The spatial ...

Estimation of Dynamic Mechanical Error for Evaluation of Machine Tool Structures

International Journal of Automation Technology, 2012

Dynamic motion errors of machine tools consist of errors in the mechanical system and the servo s... more Dynamic motion errors of machine tools consist of errors in the mechanical system and the servo system. In this study, a simple method to estimate the dynamic mechanical error is proposed to evaluate machine tool structures. The dynamic mechanical error in the low frequency range is estimated from the static deformation due to the driving force, the counter force, and the inertial force. The error in a high-precision machine tool is estimated for comparison with measurements. Two calculation tools, finite element analysis and rigid multi-body simulation, are used for the estimation. Measured dynamic mechanical errors can be correctly estimated by the proposed method using finite element analysis. The tilt of driven bodies is the major reason for dynamic mechanical errors. When the reduction factor representing the structural deformation is properly determined, the rigid multi-body simulation is also an effective tool. Use of the proposed method for modification planning is demonstra...

Distribution of motion for five-axis machine tools utilising quasi-redundancy

International Journal of Mechatronics and Manufacturing Systems, 2016

A new approach for the distribution of motion for five-axis machine tools, using quasi-redundancy... more A new approach for the distribution of motion for five-axis machine tools, using quasi-redundancy given by the tolerance values of the rotational axes, is presented in this paper. Depending on the directional manufacturing tolerances for a geometry, the tolerance space is introduced. Allowing only small rotational tolerances, the nonlinear transformations are approximated using the small angle assumption. The optimisation problem is formulated as quadratic programming problem using B-Splines to represent the optimised solution. Based on two application examples, it is shown that the machining time and the machine excitation for desired machine axes can be reduced by the algorithm presented in this paper.

Adaptive learning control for thermal error compensation of 5-axis machine tools

Journal of Manufacturing Systems, 2017

This paper presents a prediction and compensation approach for thermal errors of 5-axis machine t... more This paper presents a prediction and compensation approach for thermal errors of 5-axis machine tools, based on supervised online machine learning. Process-intermittent probing is used to identify and update a thermal autoregressive with exogenous input (ARX) model. The approach is capable of predicting and compensating thermal displacements of the tool center point based on changes in the environmental temperature, load-dependent changes and boundary condition changes and states, like dry or wet machining. The self-optimized machine tool shows very stable long-term behavior under drastically varying machining and boundary conditions. The implementation is validated on a set of thermal test pieces. The test pieces show that the major share of thermal workpiece errors are reduced by the thermal adaptive learning control.

Comparison of rigid body mechanics and finite element method for machine tool evaluation

Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and qui... more Reconfigurable machine tools are proposed as manufacturing concepts coping with turbulent and quickly changing business environments. New tools for efficient modelling of different machine variants are required in order to facilitate and accelerate the reconfiguration of machine tools. This paper presents a software tool which allows the evaluation of the performance and conformance to requirements of machine structure variants at an early stage. In contrast to computer-aided manufacturing (CAM) tools which process numerical control (NC) code to predict the tool trajectory, this tool calculates the static and simulates the dynamic properties of the machine structure as a basis for machine evaluation. Models of different structure variants are assembled using a module library, which contains models of the available physical modules. Thus, different variants can be set up and analysed efficiently, significantly improving the data basis on which important and far-reaching decisions have to be made. An example illustrates how the tool can be used for obtaining information on the physical machine properties and how to interpret the results. The presented software tool is part of a methodology for the reconfiguration process of reconfigurable, modular machine tools.

Mit Rekonfigurierbarkeit gewinnt der Anwender

Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Un... more Die Globalisierung und der Wandel vom Verkäufer-zum Käufermarkt haben dazu geführt, dass viele Unternehmen ihre Produktion wettbewerbsfähiger machen müssen. Die notwendigen Optimierungen betreffen sowohl die Kosten als auch technisch-organisatorische Aspekte wie die Fähigkeit, innerhalb kürzester Zeit auf Änderungen der Auftragslage und -inhalte reagieren zu können. Um unter den verschärften Rahmenbedingungen in der Serienproduktion weiterhin bestehen zu können, werden wandelbare Fertigungsmittel benötigt. Unter Wandelbarkeit versteht man Flexibilität für Arbeiten und Reaktionen innerhalb eines vorgedachten Rahmens und Rekonfigurierbarkeit für Anpassungen an unvorhergesehene neue Anforderungen. Die Wandelbarkeit geht somit deutlich über das hinaus, was heutige Systeme bieten.

Beitrag zur Analyse des dynamischen Verhaltens von Werkzeugmaschinen

ich für die intensive Betreuung in Form fordernder Diskussionen, detaillierter Durch¬ sicht der A... more ich für die intensive Betreuung in Form fordernder Diskussionen, detaillierter Durch¬ sicht der Arbeit und Übernahme des Referats. Bei Herrn Prof. Meinrad K. Eberle möchte mich für die kritische Durchsicht der Arbeit und die Übernahme des Korreferates bedanken. Mein Dank gilt auch Herrn Dr. Friedrich Küster, dem Leiter des Sektors Maschinen, für die beflügelnden Diskussionen im Bereich der Maschinendynamik. Speziell zum Dank verpflichtet bin ich Herrn Dr. Wolfgang Knapp der diese Arbeit durch seine grosse Erfahrung und Unterstützung im Bereich der Maschinenmesstechnik wesentlich beeinflusst hat. Herrn Dr. Zdzislav Rak ist die numerische Umsetzung des Starrkörperansatzes zu ver¬ danken, der im Rahmen der Arbeit eine zentrale Bedeutung besitzt. Hierfür und für viele kritische Diskussionen bin ich ihm zu grossem Dank verpflichtet. Bei Herrn Dipl. Betr.-Ing. ETH Otto Doka möchte ich mich besonders für die einge¬ hende Betreuung im Bereich konstruktiver Arbeiten bedanken, dessen enormer Erfah¬ rung die Umsetzung des Hexaglides erst zu verdanken ist.

Correlation of Cutting Force and Power Consumption for Ultrasonic-Vibration-Assisted Cutting of Label Paper Stacks

Volume 3: Design, Materials and Manufacturing, Parts A, B, and C, 2012

ABSTRACT Experiments comparing conventional and ultrasonic vibration assisted guillotine cutting ... more ABSTRACT Experiments comparing conventional and ultrasonic vibration assisted guillotine cutting of paper stacks have been performed on plain and aluminum coated label paper. It is shown that ultrasonic vibration assisted cutting reduces the cutting force for both paper species. Reduction of the cutting force allows the down holder force to be decreased and lowers the compression of the paper stack necessary to prevent pull-out of the top sheets of paper. Using a higher amplitude setting on the ultrasonic generator further decreases the cutting force for the paper stack. For three different cutting speeds, it is shown that ultrasonic vibration assisted cutting force reduction depends on the average speed of the tool for both paper species. A linear regression with present experimental data is done to obtain an equation for the relation between input generator power and resulting cutting force. Finally, the quality of the cutting edge is examined, quality parameters are defined, and according to these the cutting edge quality is assessed.