Lade...
Journal Title
Precision Engineering
3 Ergebnisse
Filter
Einstellungen
Gerade angezeigt 1 - 3 von 3
- Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Thermo-mechanical tool setting mechanism for ultra-precision milling with multiple cutting edges(2019-01); Ultra-precision milling operations are particularly ineffective machining processes, due to the fact that they are typically operated with a singular cutting edge (fly-cutting). For meeting the tight tolerances of optical and high precision surfaces, a nanometer precision tool setting mechanism is mandatory when adding more cutting edges. On the basis of a theoretical assessment of the surface generation, this paper presents a novel tool setting mechanism based on a thermo-mechanical actuator that has specific advantages compared to electrical or mechanical solutions. The prototype design for a two-tool holder for diamond milling using this actuator is presented and the choice of substrate material is assessed by FEM simulations. It was found that 1.2083 type steel potentially offers a larger stroke and therefore was chosen for the prototype. Next, the requirements for the heat input are discussed and a novel device for quasi-continuous heating during spindle rotation—an IR-LED ring light—is presented. Using the ring light, it is demonstrated that the tool holder can be selectively heated and a localized expansion of up to 1 μm is achievable at a spindle speed of 240 min-1.Wissenschaftlicher ArtikelBand:5580 57 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Holistic approximation of combined surface dataModern micro-production processes demand fast and robust inspection techniques up to 100% inspection rates. For instance, a fast acquisition of the objects surface in the needed precision and density can be realized by optical measurement systems. In order to extract the relevant geometric quantities from the surface data of prismatic workpieces, the measured data points need to be assigned to the nominal geometric primitives, e. g. cylinder, plane or sphere. For this purpose, an automatable algorithm is desired, which assigns all measured points to the corresponding geometric elements and minimizes the measurement uncertainty. Such an optimal segmentation routine of combined geometric data can either be performed by rating neighboring measurement points based on their curvature or by a holistic approximation. Whereas the first approach is sensitive to noisy data and not able to distinguish between spheres and cylinders with certain radii, the holistic approximation in combination with further statistical methods promises an automatic detection of outliers. In order to analyze the achievable measurement uncertainty with the holistic approximation approach for an object geometry composed by three-dimensional base elements (cylinder, torus, plane), the method is applied to determine the geometric features of micro deep-drawing dies. For verification, the measured geometry of the object is simulated including uniformly distributed noise within a range of ±2.5 μm. As a result, the determined radius of the cylinder (defined to 412 μm) has a standard uncertainty due to random errors below 11 nm and an uncertainty due to systematic errors less than 1.1 nm. Furthermore, real tactile measurement data are evaluated to validate the holistic approximation. In comparison to certified analysis software, which requires a manual segmentation, the results show differences below 0.25 μm for the cylinder diameter. The increased measurement deviations are caused by assumptions of the model-based evaluation, which is essential for the automated data processing. However, the achievable uncertainty qualifies the holistic approximation for a robust and automated evaluation of geometric tolerances in the field of micro-production.Wissenschaftlicher ArtikelBand:5486 54 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Diamond Micro Chiseling of large-scale retroreflective arrays(2012-06-18); ; Triple mirror retroreflectors are essential components for safety applications, communications and measurement equipment. While downscaling of characteristic dimension is possible for triangular retroreflectors, this is a challenging task for full-cube retroreflectors, due to the absence of continuous tool paths. Thus, the Diamond Micro Chiseling (DMC) process has been developed which allows the machining of full-cube retroreflectors by overlapping a series of sharp-edged pyramidal microcavities. In the past, this has been successfully demonstrated on a small-scale up to 3 mm × 3 mm with a structure size of 150 μm. Industrial applications, however, require the structuring of areas which are significantly larger than 10 mm × 10 mm. This paper will introduce the technology for machining such pattern with the help of the DMC process. Particular attention will be given to the measurement procedures and required tolerances for performing an in situ tool change as well as the optimization strategies for reducing the required process time.Wissenschaftlicher ArtikelBand:36Heft:4205 376