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Continuous and discrete curve — (a) Curvature graph of continuous curve and discrete curvature at discrete points of the curve, (b) Curvature and length of arc of continuous curve and discrete curvature and length of segment at discrete points of the curve along the developed length of the curve
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Efficient and productive manufacturing of freeform shapes requires a suitable three-dimensional CAD model at the entrance to the CAM system. The paper deals with the impact of NURBS or B-spline CAD model geometric continuity on the accuracy and productivity of 5-axis ball-end milling of freeform surfaces. The relationship between a different order...
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Simplification of Computer-Aided-Design models plays an important role in reducing the complex features of man-made objects produced according to engineering needs. This paper proposes an efficient feature preserving method to simplify CAD models by extracting sharp edges and decomposing the original mesh model into low varying curvature sub-region...
Citations
... It is usual that WAAM produces blanks that are further machined [2]. However, increasing the precision of WAAM can save costs spent on further machining and allow the possibility of manufacturing more complex geometrical shapes like the ones mentioned in [12] where the influence of precision of the CAD model on the finish milling process is investigated. ...
Wire arc additive manufacturing (WAAM) is one of the most productive metal additive manufacturing methods. One of its most promising applications holds in the manufacturing of difficult-to-cut materials where production costs can be reduced with minimizing the time of machining and total tool costs. To develop a correct WAAM, technological processes for manufacturing complex-shaped components welding torch path corrections and welding power corrections have to be made especially in critical sections such as corners and sharp edges. A predictive mathematical model of the material cladding during the WAAM process has been developed for the purposes of generating an optimal toolpath of the WAAM clads. This predictive mathematical model is simplified to reflect the important physical phenomena in the weld pool but also to optimize computing time. In this paper, the principle of the mathematical model is described, and its functionality is verified by the welding experiments with five different welding power settings. For the initial calibration of the model parameters single straight-line weld clads with 5 different welding power settings (wire feeds) ranging from 5.0 to 8.6 m/min were investigated. 3D scans of these welded samples are used for the verification. With the calibrated simulation model, it was possible to predict the precise shape with a maximum deviation circa 0.20 mm. The start portions of the weld clads seem more complex having the deviation circa 0.30 mm. These are valuable results as the WAAM technology is generally considered to be reasonably rough.
... It is usual that WAAM produces blanks that are further machined [2]. However, increasing the precision of WAAM can save costs spent on further machining and allow possibility of manufacturing more complex shapes like the ones mentioned in [12]. ...
Wire Arc Additive Manufacturing (WAAM) is one of the most productive metal additive manufacturing methods. One of its most promising applications holds in manufacturing of difficult-to-cut materials where production costs can be reduced with minimizing the time of machining and total tool costs. To develop a correct WAAM technological process for manufacturing complex shaped components welding torch path corrections and welding power corrections have to be made especially in critical sections such as corners and sharp edges. A predictive mathematical model of the material cladding during WAAM process has been developed for the purposes of generating an optimal toolpath of the WAAM clads. This predictive mathematical model is simplified to reflect the important physical phenomena in the weld pool but also to optimize computing time. In this paper the principle of the mathematical model is described and its functionality is verified by the welding experiments with five different welding power settings. 3D scans of welded samples are used for the verification.
... However, it should be considered that CAD model continuity affects accuracy when machining curvy surfaces, namely B-spline and Bezier curves. In practice, CAD model continuity leads to a surface deviation that can vary up to 60 µm but does not affect surface roughness [15]. Dong the bull-nose mill's local inclination angle and tilt angle [16]. ...
The work is new due to the type of process used—ultrasonic precision machining—to determine the possible effect of spindle heating (long-term machining) on the precision of the flat surface. It was carried out on a precise ultrasonic machining machine, and the material of workpiece was ceramic Al2O3. A flat surface was machined. Such an experiment has not been feasible until now. The experiment was divided into two days. On the first day, the machining time was 4 h. It is a long enough time to create a temperature-steady state. On the second day, with a cold tool and cold machine tool, we continued where we left off on the first day. This is how we monitored the accuracy of the dimensions of the workpiece on the plane surface. We have achieved the following: The average interface depth achieved values of 0.007089 mm and 0.003667 mm for cold and heated spindles, respectively. It means that when the spindle is not heated, the depth of the interface is higher by 93% (almost double the depth). The average standard deviation of the interface depth is 0.001683 mm and 0.000997 mm for cold and heated spindles, respectively. It means that when the spindle is not heated, the process is not as stable, and the standard deviation is higher by 69%.
