A compensation method is proposed that enables the correction of temperature disturbance effects on the mechanical structure of linear displacement sensors, when measuring in environments with moderately changing temperatures. Based on the surface temperature information of the sensor housing, an open loop observer estimates the thermal error, considering the clamping configuration of the sensor with respect to the target surface. Correspondingly, the indicated value is corrected by the estimated thermal error. The validity of the correction after calibration is checked by various experiments, in which setup settings are varied and different time-temperature-sequences are tested.

The accuracy of 5-axis machine tools is a key factor to modern manufacturing of multi-axes machined work pieces. Up to 75% of errors on manufactured workpieces are caused by thermally induced errors of machine tools. In this paper a thermal test piece for evaluating thermal errors of machine tools equipped with rotary tables is introduced. In comparison to geometric test pieces, which detect geometrical errors of machine tools only, the developed thermal test piece visualizes thermally induced errors in X-, Y-and Z-direction as well as two additional angular errors at the tool center point (TCP) of 5-axis machine tools over time. Further, the thermal material expansion error of the test piece on centric clamped machined workpieces can be evaluated with the new thermal test piece. The presented thermal test piece is machined during a corresponding eight hour test cycle and tested on two 5-axis milling machines with different axis configurations. The thermal test piece can either be evaluated with a coordinate measuring machine (CMM) or manually with handheld measurement devices such as dial gauge, micrometer and straightedge. The thermal behavior of the two machine tools is also investigated, following the ISO 230-3:2007 regarding thermal errors of machine tools, under no-load or finishing conditions using the R-Test measurement setup. The resulting workpiece errors evaluated by using the thermal test piece are compared to the machine tool measurements. A good correspondence between the R-Test measurements and the thermal workpiece errors can be shown. CMM and handheld measurements are both capable to detect the thermal machine tool errors.

The efficiency of cutting is largely influenced by cutting edge radii. When considering the correct cutting edge radius in the simulations, correct cutting characteristics can be predicted and thus the cutting process optimized. Sharpening the cutting edge of the tool to a specific optimized radius subsequently will improve the service life of the tool, workpiece quality, and performance of cutting. Measuring cutting edge radii of tools already is challenging, especially when measuring cutting edge radii of diamonds cutting tools because of their transparency and their dimension in the micrometer range. Defining a sound framework for selecting the appropriate metrology of transparent objects and clarifying the correct measurement parameters, settings, and proper sample preparation are the main achievement of current work. Tactile profilometer, confocal and focus variation light microscopy, imprinting, scanning electron microscopy (SEM) stereoscopy, and atomic force microscopy (AFM) are used to measure the cutting edge radius of diamonds. The identification of the cutting edge radii are done based on the methodology of the least square circle fit over cutting edge radius, and is determined iteratively. Estimations of uncertainties of the measurements are explained in detail and compared. The same measurement techniques and methodologies can also be applied to measure other transparent or difficult to measure materials. The results of different measurement technologies for the same diamond specimens are compared. In the end, one choice from the utilized measurement methods is suggested based on Analytic Hierarchy Process (AHP), which is one of the methods in Multiple Criteria Decision Analysis (MCDA). The selection process and the proposed set of evaluation criteria can also be applied to other measurements.

The field of Large-Scale Metrology has been studied extensively for many decades and represents the combination and competition of topics as diverse as geodesy and laboratory calibration. A primary reason that Large-Scale Metrology continues to represent the research frontier is that technological advances introduced and perfected at a conventional scale face additional challenges which increase non-linearly with size. This necessitates new ways of considering the entire measuring process, resulting in the application of concepts such as virtual measuring processes and cyber-physical systems. This paper reports on the continuing evolution of Large-Scale Metrology.

Precision positioning of an object relative to a reference point is a common task in many activities of production engineering. Sensor technologies for single axis measurement, either linear or rotary, which form the fundamentals of measurement technologies for precision positioning, are reviewed. Multi-axis coordinate measurement methods such as triangulation and multilateration, as well as Cartesian and polar systems for specifying the position in a plane or three-dimensional (3D) space are then presented, followed by a discussion on traceability and standards. Some advanced applications of measurement technologies for precision positioning in manufacturing industries are also demonstrated.

Thermal errors of manufacturing machines induced by fluctuating environmental temperatures are one of the largest error sources in precision manufacturing. With the increased demand in high precision workpieces less thermal sensitive manufacturing machines are a requirement. In this paper a new simulative evaluation procedure of thermal tool centre point errors in frequency domain and its validation via measurements is presented. The approach allows evaluation of the thermal behaviour and the thermal errors influencing the positioning error of the machine. It is presented, that selective insulation of machine structure can reduce the amplitude of thermal errors at the thermal resonance frequency. (C) 2015 CIRP.

This paper presents the results of detailed thermal analysis of a 5-axis machine tool with focus on the rotary axes. The rotary axes are characterized regarding their position and orientation errors as a function of the underlying thermal load, contributing significantly to the overall accuracy. A physical model is presented, which allows the simulation of the thermal behavior of the rotary axes based on the power input to the drives of the rotary axes and the heat conduction in a swiveling rotary table unit and convection into environment. This enables an external online-compensation of thermal errors. The compensation model is verified and validated.

Thermally induced errors are responsible for up to 75% of the geometric errors on a workpiece. The demand for 5-axis machine tools is still increasing, but in the focus of thermal research there are only the influences of spindles, linear axes and the envionmental temperature change. In this article, a procedure for characterizing the thermal behaviour of rotary axes of five axes machine tools is described. Infrared camera records visualize the change of the temperature field in the machine tool structure due to underlying load cycles. Thermocouple measurements are carried out to receive detailed temperature data. They show phenomena which are typically for fast rotating axes. Displacement measurements with the measurement system R-Test enable a phenomenological modelling which can be used to predict the thermal behaviour of a rotatory axis. This can be used for a significant reduction of the total thermal error of a machine tool, and therefor to an increased accuracy.

Thermally induced errors of machine tools cause up to 75% of the geometric errors on workpieces. Research carried out in the last decades focused on influences by the environment, spindles and linear axes. With the increasing demand for five-axis machining, the rotary/swivelling axis units have to be checked and compensated for thermal errors. The R-test set-up is a proper measuring device to characterise these errors. This paper introduces a compensation approach to reduce up to 85% of the thermally induced location errors of rotary/swivelling axis units based on internal NC signals, like power supplied to drives.

Zusammenfassung Thermische Einflüsse sind für bis zu 75% der geometrischen Fehler auf Werkstücken verantwortlich. Obwohl die Nachfrage für 5-achsige Werkzeugmaschinen immer weiter steigt, stehen bis jetzt die thermischen Einflüsse von Spindeln, Linearachsen und der Umgebungstemperatur im Mittelpunkt der Forschung. Dieser Beitrag beschreibt eine Prozedur zur Charakterisierung des thermischen Verhaltens von Dreh-/Schwenkachsen von 5-achsigen Werkzeugmaschinen. Infrarotkameraaufnahmen visualisieren die Änderungen des Temperaturfeldes in der Maschinenstruktur aufgrund ausgeführter Achsbewegungen. Messungen mit Thermoelementen liefern detaillierte Temperaturdaten und zeigen spezielle Phänomene, wie sie vor allem bei schnell drehenden Rundachsen auftreten. Verlagerungsmessungen mit dem Messsystem R-Test ermöglichen zusammen mit einer phänomenologischen Modellierung die Vorhersage des thermischen Verhaltens von Rundachsen, was zu einer Reduktion des thermischen Fehlers der Maschine und somit zu einer erhöhten Bearbeitungsgenauigkeit genutzt werden kann.

Up to now, research of the thermo-mechanical deformations was focused on the environment, the spindle, the bed and the linear axes of machine tools. The thermal behavior of rotary and swiveling axes was not studied in the same detail, but they are getting more important due to the increasing requirements for 5-axis machine tools. This paper deals with the comparison of a physical and a phenomenological simulation model for a model-based compensation of thermal errors of rotary axes.

Square pyramid and conical test-pieces have been machined. Disadvantages of square pyramid in respect to conical test-piece have been shown. Following the proposal of Bossoni [1], ISO presents a test-piece for simultaneous, 5-axis movement in ISO/DIS 10791-7 [4] without specifying the exact position and orientation of the test-piece. Therefore in this paper, test-pieces milled at four different positions on a 5-axis machining center are analyzed and the results are compared with kinematic simulations. It is shown by simulation and machining, that the accuracy of the test-pieces depends not only on the geometric characteristics of the machine tool, but also on the position and orientation of the test-piece.

A new 3D-probing system is presented, whose design is not only optimized for isotropic stiffnesses at the probing element but also for most effective manufacturing and easy assembling. A deflection of the probing element results in a change in the position and/or orientation of a moveable plate in which the probing stylus is screwed. The motions of the moveable plate are measured by capacitive sensors. The geometry of the probing system is designed using a procedure based on the Finite Element Method (FEM) and is veryfied by force measurements. Therewith the stiffnesses at the probing element can be determined using FEM simulations and adapted to given specifications before realizing the probing system. By means of this verified design tool it is possible to adjust the properties of the probing system like its stiffnesses to different measuring tasks and applications, e.g. as probing system for (micro-) coordinate measuring machines or machine tools. The geometric checking of the probing system includes the determination of the linearity error in probing direction, the maximum permissible probing error, the repeatability, and the environmental variation error.

Zusammenfassung Es wird ein neues 3D-Tastsystem vorgestellt, dessen Design nicht nur bezüglich isotroper Steifigkeit am Tastelement, sondern auch bezüglich wirtschaftlicher Herstellung der einzelnen Bauteile und deren einfacher Montage optimiert ist. Eine Verlagerung des Tastelementes resultiert in einer Änderung der Position und/oder Orientierung einer beweglich gelagerten Messplatte, in welche der Taststift geschraubt wird. Die Bewegungen der beweglichen Messplatte werden mit kapazitiven Sensoren gemessen. Die Geometrie des Tastsystems wird unter Verwendung der Finite-Elemente-Methode (FEM) berechnet und mittels Kraft-Messungen überprüft. Damit steht ein verifiziertes Werkzeug zur Verfügung, mit welchem die Eigenschaften des Tastsystems, beispielsweise dessen Steifigkeiten, an vorgegebene Spezifikationen angepasst werden können. So werden verschiedene Varianten des Tastsystems vorgestellt, die für einen Einsatz auf (Mikro-) Koordinatenmessgeräten oder Werkzeugmaschinen angepasst sind. Die geometrische Überprüfung des Tastsystems umfasst die Bestimmung des Linearitätsfehlers in Antastrichtung, die maximale Antastabweichung, die Wiederholgenauigkeit sowie den Einfluss der Umgebungsbedingungen.

Thermal errors of machine tools are one of the major sources of inaccuracy. Therefore, the reduction of temperature induced deviations or the compensation of the resulting tool center point (TCP) errors have been of strong interest to the manufacturing industry for a couple of years. Up to now, the observation of the environment, the main spindle, the linear axes and the machine bed were in the focus of research, but with the rising demand for 5-axis machine tools and the increasing requirements regarding their accuracy, the analysis of the thermal behavior of rotary axes becomes more and more important. This paper gives an overview of corresponding thermal measurements of machine tools. The thermal behavior of rotary and swiveling axes is analyzed in detail. A simulation model and an approach for a phenomenological compensation of the TCP error are introduced and verified by measurements.

The influence of the cutting edge micro geometry on cutting process and on tool performance is subject of several research projects. Recently published papers focus on optimising the cutting edge rounding. The results are partly inconsistent. Unfortunately, no international standard yet exists to properly describe the cutting edge micro geometry. This is seen as the root cause for detected discrepancies. To develop a common understanding for the influence of rounded cutting edges, it is indispensable to use the same basis to characterise the edge profile. This paper gives a review on existing characterisation methods, analyses the difficulties in their application and discusses different modelling ideas to describe the cutting edge profile. Based hereon, a new algorithm and geometrical parameterisation of the cutting edge is proposed, which reduces uncertainties and difficulties in the application of currently available methods. The proposed method considers measurement uncertainties and is robust against form errors and creates thus the basis required for the study of the influence of rounded cutting edges.