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During machining occurring losses conduct into the machine tool and lead to deformations that im-pair the machining accuracy. Thus, high effort is invested into the compensation of thermo-elastic er-rors. One new approach is to use the information extractable from part programs in combination with CNC controller systems to forecast occurring losses in terms of a look ahead function. The method al-lows the evaluation of part programs with respect to its thermal influence on the machine tool. There-fore, the method is applied on selected part programs, resulting loss distributions are discussed in terms of their thermal impact, and potential follow-up strategies are stated.

To control the thermal behavior of machine tools, numerous measures are used today. With the help of thermal machine models, well-founded predictions can be made for the selection and design of these measures. For creation and simulation of thermo-elastic models of structural components and a high effort is still necessary. In the paper, a procedure is presented to reduce this effort. A combination of existing methods and new approaches is used. This includes methods of mathematical model order reduction to reduce computing costs and robust mesh algorithms that process even slightly defective geometries.

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.

Computer models, which simulate the thermo-elastic behavior of machine tools, are used for optimizing machine designs and more recently for controller-integrated online corrections. Sufficiently accurate corrections of errors caused by the thermal machine behavior require quick and precise identification of uncertain and irregularly distributed parameters based on measurements. The paper presents a systematic approach to conduct parameter identification during machine commissioning. In particular, the acquisition of required data for parameter adjustment and model optimization is addressed. Finally, the procedure is demonstrated on the example of a machine tool's feed axis.

In machine tools, in-process force measurement is required by many manufacturing applications, where a particular demand for spatial measurements in up to 6 degrees of freedom (DoF) is growing. Beside expensive commercial 6 DoF force/torque sensors or vague drive current evaluation, sensor integration as part of machine components or joints has been discussed for a long time. The approach presented here, integrates 6 cost-efficient commercial 1 DoF force sensors in hexapod structures and kinematics, that are particularly suitable for sensor integration due to the absence of friction, the presence of mainly longitudinal forces and the availability of 6 DoF. These sensors can be placed at different positions, whereby this article focuses on a rigid hexapod-based end-effector. As the end-effector is not an independent measuring system, but part of a machine, that moves dynamically through the workspace and carries workpieces or tools, a suitable measurement model is necessary that addresses all those influences. After a brief literature overview and introduction to the approach, this work presents the dynamic measurement model including sensor and quasi-static error parameters, aspects about optimal framework design and several steps of validation and evaluation of the new measuring system. These include application of static loads, workspace analysis, dynamic transfer behaviour, rigid body dynamics compensation and, finally, process force measurement during a milling process.

As an unfavorable factor of machining process, chatter threatens the machined quality of workpiece, which determines the assembly and fatigue performance of the workpiece. During the interaction between machine tool and thin-walled workpiece, the process damping effect, multiple modes response and dynamic changes caused by the material removal of the in-process workpiece (IPW) will make the machining process more complicated and introduce great difficulties to dynamic modeling and performance prediction. In this paper, we considered the process damping determined by the indentation volume between flank face of milling tool and machined surface, and used multi-mode model to describe this behavior. In order to establish the assembled material removal model of the IPW dynamics with multiple modes, the structure dynamic modification (SDM) and finite element method (FEM) were combined together. The updated third-order full discretization method was applied to solve the dynamic equation in modal space. Then, the three-dimensional stability lobe diagrams (SLDs) with and without material removal along the tool path were obtained respectively by enveloping multiple modes of the IPW and milling tool together. Finally, the cutting tests were carried out. The experiments showed that the assembled model could predict the dynamics of IPW accurately, and the proposed stability analysis model was relatively close to experimental results. Besides, the modes of thin-walled workpiece with weak rigidity do not always play a dominant role in the process of machining. Although the material removal rate is limited by considering the multiple modes of the system, the processing quality can be ensured.

Nowadays, feed axes are often equipped with multiple parallel-acting actuators in order to increase the dynamics of the machine tool. Also, additional actuators for active damping are widely used. Normally, the drives or actuators are controlled independently without consideration for the impact on each other. In contrast, by using the modal space control, the system can be decoupled and the modal control loops can be adjusted independently. This control approach is particularly suitable for motion systems, such as machine tools, which have more drives or actuators than degrees of freedom of movement. This paper deals with the pre-investigation of the modal-based vibration control for machine tools with additional actuators. The object of investigation is an elastic system with a movable saddle. The modal-based control is compared with a local control approach. The results obtained experimentally on the test rig are presented. The modal control is superior since, with the modal approach, each control loop corresponds to a specific vibration mode, and the control law for this loop is designed to provide the desired performance of the control system at the corresponding resonance frequency. The parameterisation of the control loops is simplified by modal control, since the modes can be controlled independently.

Growing power densities in the main spindle of machine tools caused by approaches to increase the productivity lead to deflections of the tool-center-point (TCP) and thus limit the achievable accuracy. In order to optimize the operating point of a spindle in the context of these contrary requirements, effective tools need to be developed. By modeling thermo-elastic effects using a FE approach, interactions of heat sources and sinks can be investigated deeply on the one hand and a model based correction of TCP deflections can be established on the other hand. For a practical use, short computing times as well as precise simulation results are core requirements. In the present paper, an online thermal simulation model is developed, parameterized and validated.

Within 200 years since the industrial revolution manufacturing systems have often changed their faces. Emerging nations, new markets, new inventions and the changing needs of the society forced them to adapt. Until today, the arising challenges are immensely diverse: highly individualized products, decreasing manufacturing time, limited resources and critical ecological footprints are only a few of them. Oftentimes solutions for these issues and other future requirements can be found by interrogating nature. Applying knowledge of biological principles to industrial manufacturing processes is recently referred to as „biological transformation of manufacturing systems“. Hereby three levels of a biological transformation are introduced, starting from inspiration over integration to the interaction of biological and technical systems. The paper illustrates the idea of biological transformation with specific examples for each level. On the inspiration-level the design of manufacturing systems with elements of natural ecosystems is described. Thus flexibility is increased, material cycles are closed and waste will be reduced. Furthermore the integration-level is illustrated by the use of microorganisms in cutting fluids. Finally, evolutionary computing within an automatic joining cell is shown as an example for the interaction-level.

It is a well-known problem of milling machines, that waste heat from motors, friction effects on guides and most importantly the milling process itself greatly affect positioning accuracy and thus production quality. An economic and energy-efficient method of correcting this thermo-elastic positioning error is to gather sensor data from the machine tool and the process and to use that information to predict and correct the resulting tool center point displacement using high dimensional characteristic diagrams. On the one hand, the selection of which and how many input variables to use in the characteristic diagrams is critical to their performance. On the other hand, however, there are often a great number of possible variable combinations available and testing them all is practically impossible. This paper will discuss the suitability of many different input variable types and present a new method of input variable selection which will be compared to existing methods and demonstrated on measurements performed on a machine tool.

Nowadays, the thermo-energetic design of a machine tool also includes the thermal stabilization of its machine components. In the past, thermal stability was irrefutable connected to minimizing the temperature gradient of machine tools by air conditioning the entire machine or even the factory hall. Today, thermal stability also defines minimal inhomogeneities in the temperature field of the machine tool due to higher energy efficiency requirements. Fluidic tempering systems of machine components offer considerable potential concerning the minimization of thermo-elastic displacements with acceptable energy demand. Hence, intelligent algorithms are required to combine tolerable geometric deviations with minimal energy effort. The scope of this paper is the integration of a demand-oriented fluidic temperature control system into a machine bed. The resulting multi-input-multi-output (MIMO) systems and varying boundary conditions are challenges, which are addressed. Therefore the paper compares two control approaches, a decentralized single-loop control and a multi-loop control by decoupling the control loops and especially focus on the distribution of the jointly used actuating variable, combined with the variation of different boundary conditions.

Part complexity increase the ratio of manual tasks on machine tools, i.e. feeding, to maintain high productivity. Mobile robot cells automate these tasks but require cost-intensive retrofittings for additional interfaces. This paper focuses on a new mobile robot cell without any mechanical or electrical connection to the machine tool. Therefore, the solution uses a camera system for wireless machine tool localization and signal transmission.

Thermo-elastic errors in machine tools have a significant influence on the machining accuracy. The error at the tool center point can be determined with the structure model based correction, which uses physical based models like finite element models. The output of the structure model is the volumetric thermo-elastic error in the workspace of the machine tool. The correction values of the machine axes are determined based on the volumetric error with the help of a kinematic model. Therefore, three variants are presented in this article and their influence on the correction accuracy is estimated. The evaluation is based on typical thermo-elastic errors in the workspace of machine tools. The influence of the different variants on the correction accuracy is estimated with the Monte Carlo method based on randomly generated errors in the workspace of the machine.

In this paper, we present a measuring approach to assessing the volumetric accuracy of machine tools or kinematics with more than 3 interpolating feed axes. It is based on an inexpensive Double Ballbar and suitable for fast performance-tests in an operational state of the machine. The novelty is the recording of large amounts of data in a very short period while continuously moving along measuring paths with up to 6DoF. In order to facilitate this measuring approach, we developed a Double Ballbar with extended measuring range based on an optical sensor and a series of systematic methods, like kinematic error modeling, optimal design of 6D measuring paths as well as post-processing and evaluation of the captured data. We demonstrate that our approach is universally applicable to different types of kinematic structures such as 5-axis machine tools, industrial robots or even parallel kinematics. By experiments, we will also show that the measured data are essentially more informative than those of standardized circular DBB tests are. Moreover, the measuring procedure is automatable and to be carried out under production conditions in the workshop, what makes it practically applicable in various evaluation and decision scenarios.

One of the main errors in the machining accuracy of machine tools is the displacement through thermal induced deformation. Modern design and construction methods aim to optimize the heat flow in the machine to achieve minimum displacement. To enable a further improvement it is essential to know the displacement state of the complete machine structure. However, most measurement methods that are used to capture the influence of a thermal load only measure the displacement of the TCP or individual axes. This paper presents a methodology to capture the complex spatial displacement condition of a state of the art machine tool in one measuring cycle using a multichannel laser interferometer. It describes the development of the measurement model as well as the measurement setup in the workspace of the machine. With measurements according to the presented procedure, it is possible to uncover weak points in the structure of a machine tool and to derive warm-up and cooling strategies.

This chapter presents a mechatronic system concept for highly productive and accurate machine tools. Using the example of an experimental machine called ‘MAX’, it will be demonstrated that the working precision of a machine can be increased whilst the effort required for machining and assembly of its mechanical components is kept to a minimum. Firstly, a novel machine structure is introduced, which allows a high reproducibility with low manufacturing effort and provides the necessary degrees of freedom for the correction of motion deviations as well as the additional actuators required for the compensation of dynamic excitations. The simplified requirements for production and assembly of the machine presented leads inevitably to large geometric and kinematic errors. These errors are modelled using rigid-body kinematics. Circularity tests and angular measurements are performed to verify the machine’s ability to correct its geometric-kinematic deviations. For a highly dynamic engraving process, the reduction of the dynamic excitation caused by the drive reaction forces is demonstrated using the principle of impulse compensation. Finally, an approach to the correction of elastic and thermo-elastic errors and the comprehensive modelling and simulation-based analysis of the experimental machine are outlined.

Thermo-elastic deformations represent one of the main reasons for positioning errors in machine tools. Investigations of the thermo-mechanical behaviour of machine tools, especially during the design phase, rely mainly on thermo-elastic simulations. These require the knowledge of heat sources and sinks and assumptions on the heat dissipation via convection, conduction and radiation. Forced convection such as that caused by moving assemblies has both a large influence on the heat dissipation to the surrounding air. The most accurate way of taking convection into account is via computational fluid dynamics (CFD) simulations. These simulations compute heat transfer coefficients for every finite element on the machine tool surface, which can then be used as boundary conditions for accurate thermo-mechanical simulations. Transient thermo-mechanical simulations with moving assemblies thus require a CFD simulation during each time step, which is very time-consuming. This paper presents an alternative by using characteristic diagrams to interpolate the CFD simulations. The new method uses precomputed thermal coefficients of a small number of load cases as support points to estimate the convection of all relevant load cases (i.e. ambient conditions). It will be explained and demonstrated on a machine tool column.

The current trend in machine tools requires higher efforts for process setup and process monitoring. Hence, digital models gain importance in the field of feed drives. To constantly adjust them to the real counterpart, parameter identification methods, which are suitable to be utilized during operation of the machine, are of primary importance. One of their main drawbacks is that their results strongly depend on the present system excitation. The paper focusses on the accuracy and presents an identification method as well as approaches to reduce excitation dependency. Subsequently, one combination of modules is applied to the NC-axes of a turning-milling-centre.

Thermo-elastic effects are one of the major reasons for positioning errors in machine tools. Next to friction and waste heat from drives, the heat exchange with the machine's surroundings influences the temperature field inside the machine tool significantly. The thermal parameters necessary to describe this heat transfer can be obtained through computational fluid dynamics (CFD) simulations. This paper presents a new method aimed at decoupling these CFD simulations from the thermo-elastic simulations in order to provide the heat transfer parameters quickly and efficiently for transient environmental conditions. This is done by defining a suitable set of load scenarios for the CFD simulations, clustering the resulting parameters with radial basis functions and interpolating them using characteristic diagrams.

The article describes a correction approach for thermally induced motion errors of machine tools that utilizes physically based models of the thermal and thermo‐elastic behavior of machine tools. After a classification and presentation of the functional principle of the model based approach functional core aspects, possible implementation variants and resulting requirements regarding the control are clarified. Examples are presented for which the functionality of the approach was proved and evaluated as well as compared to other model based thermal correction approaches.

New manufacturing processes and extended movability of modern machine tools, such as five-axis kinematics or hexapods, increase the demand for in-process measurement of spatial forces and torques in up to 6 degrees of freedom (DoF). The approach proposed in this paper is based on the idea of integrating 6 single-axis force sensors into the machine’s structure and converting these sensor forces to spatial forces and torques at the tool centre point (TCP) using a measurement model. This concept is advantageous to costs, ruggedness and available workspace when compared to state-of-the-art 6 DoF force/torque transducers. At the same time, the achievable measuring accuracy is similar and also significantly better than the accuracy of drive current based force evaluation. On the other hand, structure and machine influences have to be addressed by suitable measurement models. This article presents design, parametrization, verification, and characterisation of these measurement models on the example of four integration concepts, two in rigid bar frameworks and two in bar kinematics. Further, experimental results are shown which are classified in comparison to a 6 DoF F/T sensor and drive current based force measurement. Finally, other influences, such as structural design and deformations, as well as the integration of sensors and models into the machine’s control software are discussed.

In machining up to 75% of the geometrical variations of work piece, features are caused by thermally induced deformations of machine components [1]. Since in dry cutting up to 80% of the thermal energy is stored in the chips [2], we expected a significant effect of these process-dependent heat sources on the machine accuracy. Based on preliminary simulation results, we systematically applied determined quantities of heated chips to a machine table to understand their impact on the temperature field. Temperature sensors where used to measure the temperature change on the tables surface and in the structure. Length measuring probes measured the corresponding deformations at 24 points distributed over the table. The measurements show a temperature change of 4 K at the surface and 3 K in the structure near the heat source after 6 minutes of exposure to 500°C chips. In this case, the impact on the temperature field is local but causes the bending of the table. We recorded 8 micron of thermo-elastic deformations. The results suggest that high-accuracy processes with large energy input, such as hard turning, require the heat induced into the machine structure by hot chips to be implemented into compensation methods and correction algorithms.

Models are increasingly applied to improve the thermo-elastic behavior of machine tools. The most universal models are those with physically based approaches. They are used for analysis in the design process of the machines and for determining correction values in machine control during operation. In order to achieve sufficient accuracy, the models must be adjusted with metrological support. This is due to some model parameters, which have a high degree of uncertainty and overall effect. Because of the large number of parameters with very different characteristics, the determination of the parameters relevant for the adjustment is manually and computationally time-consuming. This article presents a systematic method of parameter selection that reduces this effort. The procedure is demonstrated exemplarily by the example of the thermo-elastic model of a hexapod strut axis.

Predicting mobile machine tool dynamics prior to moving the machine to a new part and/or location is essential to guide first-time-right in situ machining solutions. This paper considers such a priori prediction of assembled dynamics under varying base/part/contact characteristics by applying dynamic substructuring procedures. Assembled dynamics are predicted by substructural coupling of the machine's known free-free response with the known response of any base/part measured at location. Since obtaining the machine's free-free response remains non-trivial, we instead extract the machine's dynamics using substructure decoupling procedures. Substructuring is carried out using measured frequency response functions. Methods are tested for robustness, and are experimentally validated.

Based on the method of adaptive finite elements (FEM) a correction approach has been considered to identify the influence of thermo-elastic workpiece deformations during the production process milling. The paper presents a simulation-based tolerance variation calculation of cutting paths, which is caused by the heat input of the machine tool. Therefore a mathematical method is developed to numerically depict the progress of the miller with different curves A(t), B(t) and C(t). These curves are used to map the state of the milling path during the production process as well as to compare the current workpiece contour and the target workpiece contour. The tool center point (TCP) correction results from mapping of time-dependent deformation fields from the FE simulation. The aim is, on the one hand, to make statements before the production about keeping the tolerance, and on the other hand, to derive other correction approaches for the adaption of the cutting path coordinates.

In situ machining of large workpieces is made possible by moving mobile machines to workpiece locations. To guide and enhance on site machining performance, dynamics of the assembled system must be predicted beforehand. Beforehand prediction of assembled response requires dynamics of the mobile machine in its free-free configuration be coupled with response of base/workpiece measured at location. Since obtaining the free-free response of the machine is non-trivial, this paper presents a substructure decoupling scheme that instead extracts the machine's response from known dynamics of the machine mounted on a base, and from information of a substructural base system. Simulation driven investigations show the decoupling scheme to be robust even under the vagaries of measurement noise and changes in the residual substructural base system. Extracted dynamics of the machine can be subsequently synthesized with known dynamics of other bases/workpieces for a priori prediction of assembled dynamics to guide first-time-right on site machining.

Die Leistungsfähigkeit und Ressourceneffizienz moderner Produktionssysteme wird wesentlich durch ihr dynamisch-mechatronisches Verhalten bestimmt. Um quantitative Aussagen hinsichtlich auftretender Bahnabweichungen zu erhalten, hat sich die kombinierte Simulation von mechanischer Struktur und Antriebsregelung etabliert. Während der Verfahrbewegung ändert sich jedoch das mechanische Strukturverhalten durch die Verlagerung von Komponenten wesentlich. In der flexiblen Mehrkörpersimulation (MKS) existieren verschiedene Ansätze dynamische Bahnbewegungen abzubilden, welche jedoch komplexe, genauigkeitsreduzierende Reduktionen der FEM (Finite-Elemente-Methode)-Submodelle und/oder aufwendige, zeitsynchronisierte Co-Simulation in unterschiedlichen Simulationsumgebungen erfordern. Innerhalb geschlossener FEM-Umgebungen bieten transiente Rechnungen eine hohe Abbildungsgüte für die Zeitbereichssimulation, die Berechnungsdauer für große Modelle schließt jedoch Parameterstudien und die Integration der Regelung de facto aus. Es wird ein alternativer Ansatz unter Nutzung holistischer FEM-Modelle beschrieben, welcher innerhalb der Grenzen der linearen Modalanalyse eine effiziente Simulation des dynamischen Bahnverhaltens unter Berücksichtigung großer Verfahrbewegungen erlaubt. The capabilities of state-of-the art machine tools are significantly limited by their dynamic-mechatronic system properties. The combined simulation of the mechanical structure and control has been established to determine dynamic tool-path inaccuracies. While machining a work piece, the structural components of a machine tool change their position towards each other, which as a result leads to a different mechanical system. There exist different strategies to include that position dependent behavior within the coupled multi body simulation. However complex model-reduction methods for the flexible FEM substructures are necessary. Furthermore a time-synchronized parallel simulation between the simulation of the mechanical structure and the simulation of the control - typically carried out as digital block simulation - is necessary. On the other hand transient simulation approaches in the FEM environment of the overall structure are theoretically capable to represent realistic models but are by fare to complex and time-consuming to be implemented for time domain simulations including control. Based on these inadequatenesses the paper shows a new approach to consider the changing system behavior due to large movements of structural components based on holistic FEM-models. It allows an efficient integrated simulation inside the digital block simulation within the limits of a linear modal analysis.

Structural deformations of machine tool components that translate and/or rotate relative to each other to realize tool motion results in tool point dynamics varying along the tool path. These changing dynamics interact with the cutting process and the control loop of the drives to limit machine performance, making it necessary to virtually characterize these interactions such as to guide design decisions. To facilitate rapid evaluation of these varying dynamics, this paper describes a generalized frequency-based substructuring approach that combines the position-invariant component level receptances at the contacting interfaces between substructures to obtain the position-dependent tool point response. Receptances at the contacting interfaces are approximated by projecting them to a point to facilitate a multiple point receptance coupling formulation. Complete machine behavior is represented by just a few sets of receptances, making the model computationally more efficient than full-order finite element models and other dynamic substructuring methods. Position-dependent dynamic behavior for a representative three axis milling machine is simulated and numerically verified. Rapid investigations of the varying dynamics assist in virtually characterizing machine performance before eventual prototyping.

Mobile machining solutions use autonomous machining units that can be transported to different part locations, making possible easy maintenance and repair of large industrial equipment. Every new part and location results in different boundary conditions for the mobile machine tool-part system; influencing the dynamics of the combined system and necessitating different strategies for part/machine referencing and clamping. To facilitate efficient mutability and modularity in mobile machining solutions, this paper presents a dynamic substructuring strategy that combines the response characteristics of the mobile machine unit with that of two different simulated base models under varying levels of contact stiffness and damping to obtain the synthesized mobile machine tool dynamic response. Numerical verification of the approach is provided. Framework presented can also combine measured response of parts for which models may not be available a priori. Methods presented provide experimental guidelines for establishing strategies for part/machine referencing, and planning of machining strategies based on the evaluated dynamics.

Improved drive dynamics decisively boost productivity and accuracy of machine tools. Linear motors have advantages to overcome drawbacks of electromechanical drives, but are limited by their power density. Reaction forces of linear motors cause undesired excitation of the machine structure. Current research approaches focus on impulse decoupling and compensation as well as on force reduction. The paper presents a new design approach, characterised by two mechanically coupled and opposite driving linear motors. This arrangement improves the static and dynamic properties by force distribution which leads to an impulse-free feedback system. In order to have an effective use of the gained dynamics various control structures for coupled drives are investigated. Tuning methods as well as simulation and experimental results are discussed.

Typically, the feed dynamics of machine tools are limited to reduce excitations of machine structure oscillations. Consequently, the potential increase in productivity provided by electrical direct drives cannot be exploited. The novel approach of the Kinematically Coupled Force Compensation (KCFC) combines the principles of redundant axes and force compensation to achieve an increase in the machine&rsquo, s feed dynamics. Because the drive reaction forces are directly applied to the machine frame, they cancel out each other perfectly if the relative motion at the Tool Centre Point (TCP) is split according to the mass ratio of the slides. In this paper, the principle of KCFC is introduced briefly and possible improvements in the design of machine structures and control are presented. The results of experimental investigations obtained by means of a 1D-KCFC Test Bed illustrate the effectiveness of the principle. Moreover, a further increase of the compensation quality can be achieved by decoupling the force flow from the machine frame, by means of elastic elements. Finally, an outlook on future research with reference to the 1D-implementation as well as possible applications of the KCFC in highly productive processes is given.

This article deals with the structure model-based correction approach for thermal errors at machine tools. Structure models are physically-based models of the thermo-elastic behaviour of machine to...

This paper reviews the design, engineering principles and applications of machine tools specially developed for large parts. Large workshop machines are commonly used for manufacturing, where the impact of the general engineering principles differs substantially from those applied to conventional size machines. Portable machines are used during assembly and operation due to mobility, agility and energy constraints. Such large dimensions produce an amplification factor of any error source, so verification and calibration of such large or portable machines becomes even more critical than in conventional machines. The paper also includes future trends and unsolved challenges.

This paper presents a characteristic diagram based approach to the correction of thermally induced tool center point displacements of machine tools. The entire process from the introduction of the correction principle to the issues arising in the online capable application of this correction method will be discussed, with special focus on the improvement and optimization of the calculation, input selection and grid structures of the characteristic diagrams.

One possibility to increase the performance of machine tools is the achievement of higher accelerations and jerks of moved slides and stands. By this the energy consumption and machining-costs can be optimized. Nowadays machine tool structures are already optimized and further enhancements are not easily achieved. The paper deals with the mechatronic system optimization of a large-scale HSC- and HPC- portal milling centre for e.g. forming tools. This includes the identification of dynamic limiting structures and the following optimization by mechatronic system-monitoring. From process necessities a machining-time reduction by higher accelerations and improved process stability is intended. The system parameters where achieved by the implementation of a redundant axis and the usage of up-to-date lightweight design by reinforced plastics.All over the design phase the structure was constantly monitored regarding their dynamic behaviour. Furthermore a model was used – using a state space – to prejudge the machining time for a concrete example cycle. So even before any physical prototype exists the mechatronic system-behaviour of the machine tool was pre estimated using a virtual mechatronic model. This allows for a virtual product design with a new and improved quality of safety in achieving the pre-defined goals.

Machine tool performance, production accuracy and energy efficiency are interdependent design criteria. To solve this design conflict, bionics – this means technical interpretation of long-term optimized biological principles – could be an effective way to accelerate innovation loops in modern machine tool development processes. In the paper, these aspects will be discussed, and selected solutions will be presented in detail.

Complete processing in one machine calls for a configuration targeting major process stability as well as a structure geared towards accuracy and dynamism. The compromise between potential dynamism and machine size can be improved by using redundant drives. The advantageous use requires the specialization on partitioning of the complete motion. With the presented algorithm the reactive sectioning of a multidimensional motion into two components with different dynamic characteristics succeeds. This provides a useful basis for the application of the principle of dynamic sectioning for a suitable design of drive redundant machine structures. This paper describes models, simulation tools and the method of the development process.

This paper reports on a novel electro-hydraulic actuator that attenuates and isolates ground motion to keep dynamic excitations transmitted to machine tools below permissible levels. The first part describes the working principle of the actuator. The actuator is a classic example of a valve-controlled piston. Flow to the actuator is regulated to move the actuator and the machine that the actuator supports to compensate for ground motion experienced by the machine. Dynamics of this electro-hydraulic actuator are described in the second part of the paper. The third part describes experimental characterization of a physical prototype to identify unknown system parameters. Experimentally updated model is coupled to a virtual model of a flexible machine tool in the fourth part. Simulation driven investigations for the controlled transmissibility show the actuator to be effective in a frequency range of 1–100 Hz with case specific attenuations ranging from 5 to 25 dB. The actuator is designed with a high passive stiffness to support inertial loads of the machine. The device can be operated on demand when high precision is required, making it an energy efficient solution.

Thermal boundary conditions, such as heat flux, play an important role in the overall context of representing machine tools’ thermal behaviour and their interactions with the environment in a way that is close to reality. In this contribution, the machine tool–environment interface is represented based on the finite-element method and the required parameters are assigned. The term “environment” refers in this paper to the surrounding atmosphere and sometimes the foundation. The approach includes the determination of the relevant environmental boundary conditions, such as convection and heat radiation, and the description of how to integrate them systematically into the finite-element model.

Parallel structures are characterized by closed kinematics chains. Compared with conventional structures, which have serially arranged axes and are thus characterized by open kinematics chains, parallel structures have a variety of advantages. These primarily include lower moved mass, high dynamics, the high number of possible repeating parts, and the advantageous integration of measures in the control system that are relevant to accuracy. The following presentation classifies parallel structures with six degrees of freedom according to the type of drive used. Based on free-form surface machining in die and mold making, kinematics requirements will be explained and various concepts regarding kinematics, structure. loading, and stiffness will also be discussed. Finally, a preferable solution will be provided in the summary.

One trend in mechanical engineering is the orientation towards large scale technical systems. If conventional machining is used, large work pieces have to be placed inside the machine tool workspace which can lead to extreme disproportions between theoretically appropriate and actually needed system size. Hence, inefficient utilisation of resources occurs in many cases. A practicable approach to solve the problem is to use small mobile units to carry out such machining operations. This concept is pursued concerning two aspects. First, local mobility, which means the positioning of small machining units locally on the work piece area to be machined. Secondly, global mobility, which becomes manifested in the transportability of the machining units between different sites of operation. This paper will focus mainly on the key aspects in characterising such machines, especially position allocation between mobile machine and work piece.

The demand for high productivity and quality combined with the need for decreasing energy consumption will substantially affect machine tool design in the future. This development is driven by a modification of process chains which is focused on resource conservation. One important contribution for that purpose is the transition towards complete machining. This approach calls for a configuration targeting major process stability as well as a structure geared towards accuracy and dynamism. The compromise between potential dynamism and machine size can be improved by using redundant drives. This paper describes models, simulation tools and the method of the development process for redundant kinematics. To highlight the different aspects of designing such machine tool structures, their development process is demonstrated on the basis of two examples, complete machining for tool- and die making and an adaptive spindle holder for micro contouring and -structuring.Copyright © 2011 by ASME

The need of reliable structural properties of machine tools in the development phase are becoming increasingly important due to mounting accuracy demands and shrinking development periods. The finite element method is the most established tool applied in this context. Currently, calculating thermal properties and compensation of thermally caused shifts are mainly the focus of simulation studies due to high performance and the usage of dry processing. The accuracy with which thermal properties can be mapped today is measurably lower than current static and dynamic properties. The reason is due to strong interaction of the specific physical effects and the complexity of pertinent constraints. With constrained parameters the impact caused is defining the convective heat transmission. The heat transmission coefficient can be calculated analytically or numerically. This article is presenting a method that allows permanent adaptation of this coefficient to make it possible to better apply convective heat transmission to time-variable thermal simulations especially for mechanical based finite element models.

This paper reviews current developments in mechatronic systems for metal cutting and forming machine tools. The integration of mechatronic modules to the machine tool and their interaction with manufacturing processes are presented. Sample mechatronic components for precision positioning and compensation of static, dynamic and thermal errors are presented as examples. The effect of modular integration of mechatronic systems on the reconfigurability and reliability of the machine tools is discussed along with intervention strategies during machine tool operations. The performance and functionality aspects are discussed through active and passive intervention methods. A special emphasis was placed on active and passive damping of vibrations through piezo, magnetic, and electro-hydraulic actuators. The modular integration of mechatronic components into the machine tool’s structure, electronic unit, and CNC software system is presented. The paper concludes with the current research challenges required to expand the application of mechatronics in machine tools and manufacturing systems.Copyright © 2008 by ASME

Today, the dynamics, especially acceleration and jerk, of machine tools are limited in order to reduce excitations of machine structure vibrations to an acceptable level. A novel approach - the Kinematically Coupled Force Compensation (KCFC) - combines the principles of redundant axes and force compensation to further increase machines’ dynamics. In this paper, the new principle is introduced and possible control concepts are compared based on an analysis in frequency and time domain. Simulations, using a simple multi-body simulation model implemented in MATLAB/Simulink ® , show, that machine structure vibrations can be reduced significantly by KCFC.

In situ machining of large parts using mobile machines that are moved to part location(s) allows these parts to be machined, repaired and maintained directly on the site of operation. However, every new part and location that the machine is moved to results in different boundary conditions for the machine-part system which singularly influences the dynamics of the combined system and makes for difficult planning of first-time right machining solutions. To facilitate the planning of in situ machining solutions, this paper presents a dynamic substructuring framework that can predict assembled system dynamics by combining measured and/or modelled substructural response of the individual components under varying base/part/contact/configuration characteristics. Substructural coupling is formulated in the frequency and the continuous-time domains for representative examples of the mobile machine being connected to two different part/base models. The frequency based substructuring approach is used to predict tool point dynamics, results of which are instructive for designing of machining strategies to ensure stable productive cutting conditions. State-space substructural coupling predicts the changing nature of the plant model under the varying influences, which provides guidelines for designing appropriate control strategies and selection of appropriate CNC control parameters. Methods presented aid establishment of experimental guidelines for planning of first-time right in situ machining solutions.