Key Engineering Materials Vol. 615

Abstract: Nowadays there is a huge interest in new and improved three-dimensional techniques of surface finishing degree measuring and behaviour investigation. Several fields of application are mainly dependent of advances in surface metrology, as for instance aerospace and rail transport, telecommunications or micro-technology. All 3D measuring tools must be designed starting from a bi-dimensional basis and keeping a clear knowledge of their operating principle. This is then the key that defines the borders of this works path. Looking at the finishing degree of three differently obtained surfaces, preliminary comparison of results in two and three dimensions will be finally presented. All constraints defined by this problems conditions must be taken in consideration once the results are analysed.

Abstract: Some manufacturers of 3D digitizing systems are developing and market more accurate, fastest and affordable systems of fringe projection based on blue light technology. The aim of the present work is the determination of the quality and accuracy of the data provided by the LED structured light scanner Comet L3D (Steinbichler). The quality and accuracy of the cloud of points produced by the scanner is determined by measuring a number of gauge blocks of different sizes. The accuracy range of the scanner has been established through multiple digitizations showing the dependence on different factors such as the characteristics of the object and scanning procedure. Although many factors influence, accuracies announced by manufacturer have been achieved under optimal conditions and it has been noted that the quality of the point clouds (density, noise, dispersion of points) provided by this system is higher than that obtained with laser technology devices.

Abstract: The number of factors influencing the CT process for metrology applications increases its complexity and cause the loss of accuracy during CT measurements. One of the most critical is the edge detection also called surface extraction or image segmentation, which is the process of surface formation from the CT`s volume data. This paper presents different edge detection methods commonly used in areas like machine and computer vision and they are analyzed as an alternative to the commonly and commercially used for CT metrology applications. Each method is described and analyzed separately in order to highlight its advantages and disadvantages from a metrological point of view. An experimental comparative between two of them is also shown.

Abstract: This paper aims to present different methods of volumetric verification in long range machine toll with lineal and rotary axes using a commercial laser tracker as measurement system. This method allows characterizing machine tool geometric errors depending on the kinematic of the machine and the work space available during the measurement time. The kinematic of the machine toll is affected by their geometric errors, which are different depending on the number and type of movement axes. The relationship between the various geometrical errors is different from relationship obtained in machine tool whit only lineal axes. Therefore, the identification strategy should be different. In the same way, the kinematic chain of the machine tool determines determines the position of the laser tracker and available space for data capture. This paper presents the kinematic model of several machine tools with different kinematic chains use to improve the machine tool accuracy of each one by volumetric verification. Likewise, the paper thus presents a study of: the adequacy of different nonlinear optimization strategies depending on the type of axis and the usable space available.

Abstract: During machining operations on machining centres, there are a large number of internal and external factors that act on the technological system. They generate errors that influence the manufacturing cost, productivity, and machining accuracy. The monitoring and control system developed for machining centres presented in this paper consists of 3D touch probes, a device for registering a contact between the cutting tool and workpiece, devices for measuring the geometric accuracy of the machine tool and for calibrating the touch probe in the spindle, parameterised CNC programmes, computer and software for data processing and database management. The developed system guarantees monitoring of the machining accuracy, low cost, high level of productivity, low number of preparatory work and measurements, increased reliability due to reduced scrap rate by reducing the probability of cutting tool breakage, the possibility of automating the measurements and processing the data, and wide applicability.

Abstract: Roll testing is the most direct way and simple method of checking the functional accuracy of the gear by means of the geometric and rolling parameters obtained in the test. Nevertheless, for the time being there is no standard calibration procedure which could be applied to this type of rolling testers. In spite of trying to reproduce the tests in the three double flank roll testers under the same testing conditions and procedure, big variations in the results obtained were detected. This demonstrates the need to create a norm which could give a unique trazability procedure for this kind of tests and their testers calibration.

Abstract: In recent years there has been a considerable interest in microsystems, named as MEMS (Micro Electromechanical Systems). Its continuing expansion is expected, derived from the trend towards miniaturization of components and the increasing applications for these micro devices. To overcome this, the technology to produce these products known as microsystem technology (MST), has been improving in order to allow the manufacturing of this type of parts becoming of growing importance over the past years. Micro gears are commonly used in electronics industry where the miniaturization process follows a constant evolution with multiple use advantages despite their small size. In this work the study and analysis of the existing verification techniques for micro gears together with the definition of a double flank rolling test focused on these gears is presented.

Abstract: This work shows an experimental procedure aimed to generate a graph with the optimal roughness parameters in order to obtain the best roughness measurements of an optoelectronic profilometer. The optimal parameters have been determined taking into account the grade of agreement between the optical roughness values and the equivalent values of traditional contact devices. The working parameters of the optoelectronic profilometer are based on computational filters which are controlled by software working with a 3D stratified colour map (chromatic fragmentation of the white light). However, these parameters substantially differ from the usual contact profilometers that work with 2D roughness profiles (cut-off, evaluation length and contact stylus radii). This work pursues to find the optical profilometer parameters, and its values, that ensure the best quality measurement for a wide range of machining process and testing several ISO roughness intervals.

Abstract: The nanotechnology field has been developing strongly in recent years and ultra-precision measuring systems are nowadays required. A new two-dimensional moving platform with 50x50 mm range of travel, nanometer resolution and sub micrometer accuracy is being designed by the authors in order to be integrated with an Atomic Force Microscope (AFM). In this work the definition, design and experimental characterization of a homing sensor system for this 2D moving platform is presented. The homing sensor system will allow the generation of an absolute 2D reference for the platform (X-Y axis and θz rotation), defining an initial cero for the measuring system, which is based on laser encoders.