Institute for Control Engineering of Machine Tools and Manufacturing Units ISW

Stuttgart, Germany

Institute for Control Engineering of Machine Tools and Manufacturing Units ISW

Stuttgart, Germany
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Altintas Y.,University of British Columbia | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Brecher C.,RWTH Aachen | Pritschow G.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
CIRP Annals - Manufacturing Technology | Year: 2011

This paper reviews the design and control of feed drive systems used in machine tools. Machine tool guides designed using friction, rolling element, hydrostatic and magnetic levitation principles are reviewed. Mechanical drives based on ball-screw and linear motors are presented along with their compliance models. The electrical motors and sensors used in powering and measuring the motion are discussed. The control of both rigid and flexible drive systems is presented along with active damping strategies. Virtual modeling of feed drives is discussed. The paper presents the engineering principles and current challenges in the design, analysis and control of feed drives. © 2011 CIRP.


Vivanco J.M.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Keinert M.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Lechler A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Fraunhofer Gesellschaft
Procedia CIRP | Year: 2016

Multi-core processors offer a performance increment compared to single-core platforms. This leap in performance is desired to be ported to computerized numerical controls. However, in order to profit of the benefits multi-core processors can bring, the software has to be tailored to real parallel execution. In this paper a concept is proposed for partitioning numerical control software functions for being concurrently executed on multi-core systems. Specifically, the interpreter and the cutter radius compensation modules have been analyzed for devising a feasible parallel architecture. The parser algorithm has been implemented following the proposed scheme in a thread-based approach. Experiments were conducted under a real time Linux kernel extension utilizing the PREEMPT-RT patch. The results were compared against its serial version in terms of execution times to validate the concept. © 2016 The Authors.


Frey S.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Dadalau A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Production Engineering | Year: 2012

Ball screw feed drives are the most commonly used mechanism to provide linear motion in high speed machine tools. Position accuracy and the achievable closed loop bandwidth of such drive systems are usually limited by the structural vibration modes of the mechanical components. Higher order plant models allow for a better understanding of the system dynamics, improve the design process of feed drives and are essential for the development of sophisticated control strategies. The ball screw shaft, describing a complex flexible structure, is probably the most significant component concerning structural vibration modes of a feed drive. In this paper, the behavior of the shaft and its dominant influence at different operating and coupling conditions is particularly addressed. Using a hybrid modeling technique, the main characteristics of the shaft are derived and projected onto a clearly arranged and versatile lumped mass model. Simulative and experimental examinations are conducted and a parameter analysis is performed. The presented model proofs to be accurate for a great range of parameters and in addition allows for a physical interpretation of the dominant structural vibration modes of a feed drive. © 2012 German Academic Society for Production Engineering (WGP).


Dadalau A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Groh K.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Reuss M.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Production Engineering | Year: 2012

Today's machine tools are highly complex mechatronic systems capable to exert large translational and rotatory movements. In most cases rolling bearings are used to connect the moving parts to each other. As full FE models of rolling bearings can consume a large amount of degrees of freedom (DOF) efficient methods for reducing the DOF consuming rolling elements to more simple equivalent models are needed. As an example a linear guide system is used. A special feature of the considered linear guide is that the runner block consists of three separate parts, which are hold together only by pretension and friction. FE simulations of such linear guide system were not reported before in the literature. Beside the full FE model three equivalent contact models are presented. The first two equivalent contact models feature novel characteristics. Advantages and disadvantages of the equivalent models are discussed using as reference a slice of the full model and simulation results of static stiffness. The validation of the numerical models is also done using the general analytical solution of Hertz. © 2011 German Academic Society for Production Engineering (WGP).


Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Lechler A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Schlechtendahl J.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Production Engineering | Year: 2012

Current developments in automation technology deal with "cyber physical systems". These cyber physical systems have sensors and actors and can make decisions based on their own intelligence as well as partially adapt to changing conditions. For a versatile and networked production cyber physical systems are of limited value. Precisely where the available sensors and actuators have to be combined flexibly due to ever new conditions, these systems find their limits because of their insularity. Limited computing hardware resources and lacking interfaces confine the possibilities of cyber physical systems in production environment. This paper explains how cyber physical systems need to be developed further in order to meet the requirements of a versatile and networked production plant. © 2012 German Academic Society for Production Engineering (WGP).


Dadalau A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Production Engineering | Year: 2012

In this work a new efficient finite element (FE) model for rolling contact [RiBEM (rigid ball with equivalent material)] is shortly presented. The RiBEM model is used to efficiently compute the eigenmodes of a linear guide system. Experimental modal analysis of the real linear guide shows with 5 % error a very good correlation with the numerical results. Although the new contact model reduces computational time by more than ten times compared with the standard FE model, it is still too expensive for use within whole machine tool models. For this reason an equivalent, mesh independent and geometrically scalable model (rolling contact spring) based on the Hertz theory is introduced and also validated with the help of modal measurements. As a justification for the presented work, results with stiffness data from the manufacturer are also presented and less correlation with the experiment is found in this case. © 2012 German Academic Society for Production Engineering (WGP).


Eberspacher P.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Procedia CIRP | Year: 2013

Industrial manufacturing has started focusing on the topic of energy efficiency already some years ago. Nowadays, even machine controls are equipped with possibilities to switch the machine into energy saving modes or even to shut it down entirely based on fixed time intervals or manually. The developed combination and modification of state-based consumption modeling with graph-based optimization theory enables the control to choose the energy-optimal state sequence for given unproductive times. The approach is presented in detail and its saving potential is demonstrated by a usage scenario from an industrial setup. © 2013 The Authors.


Dadalau A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Mottahedi M.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Groh K.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Production Engineering | Year: 2010

In the product development process numerical optimization can successfully be applied in the early product design stages. In the very common case of ball screw drives, the dynamical behavior is most depending on the geometrical shape of the ball screw itself. Properties like axial and torsional stiffness, moment of inertia, maximum velocity and acceleration are determined not only by the servo motor but also by screw diameter, slope and ball groove radius. Furthermore coupling effects between the design variables make the optimization task even more difficult. In order to capture these effects, efficient numerical (usually FEM or MBS) models are needed. In this work a new more accurate and efficient method of computing the axial and torsional stiffness of ball screw spindles is presented. We analytically derive parametric equations which depicts most of the dependencies of stiffness on geometrical parameters of the screw. Furthermore, we enhance the analytical model with an identified function, which increase the accuracy even more. The presented analytical model is validated against FEM model and catalog data with the help of numerous examples. © German Academic Society for Production Engineering (WGP) 2010.


Frey S.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Walther M.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
Production Engineering | Year: 2010

The preloading is a main characteristic for the functionality of a ball screw. The path of preloading during operation with no thrust load is an indicator for the actual inner forces, the friction produced by the ball screw and finally for the quality of the unit. Due to manufacturing tolerances the preloading over the useful travel of the ball screw differs from its specified value. However, not only the overall loading of a ball screw varies, but also the local load distribution within the nut. This is expressed by a periodic variation of the internal forces which has an effect on the alignment of the nut and therefore on the uniformity and the motion characteristics of a ball screw feed drive. The following paper deals with the occurrence of these periodic force variations and offers an explanation for this particular phenomenon. © 2010 German Academic Society for Production Engineering (WGP).


Sekler P.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Vo M.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW | Verl A.,Institute for Control Engineering of Machine Tools and Manufacturing Units ISW
International Journal of Advanced Manufacturing Technology | Year: 2012

Lightweight design of production machines results in a problematically high inclination of vibration. Existing control techniques can avoid those vibrations based on the knowledge of the instantaneous system behavior, which is highly nonlinear and dependent on the machine's pose. One possibility is to calculate the machine behavior using a model of the machine on the control device. By this, additional and expensive sensors in the machine structure are avoided but it requires a fast and efficient algorithm of model-based system behavior identification calculated online on the control device. In this paper, we describe a new approach for model-based system behavior calculation on the control device for the vibration reduction. Emphasizes lies on the integration of the method into the engineering process, which is shown in the fact that standard models out of the engineering process are used. The approaches and benefits of the technique are shown on a two-axes machine structure. © 2011 Springer-Verlag London Limited.

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