Optimization of an autonomous robotic drilling system for the machining of aluminum aerospace alloys

This paper aims to identify the capability of a highly flexible industrial robot modified with a high-speed machine spindle for drilling of aluminum 6061-T6. With a focus on drilling feed rate, spindle speed, and pecking cycle, the hole surface roughness and exit burr heights were investigated using the Taguchi design methodology. A state of the art condition monitoring system was used to identify the vibrations experienced during drilling operation and to establish which robot pose had increased stiffness, and thus the optimum workspace for drilling. When benchmarked against a CNC machine the results show that the CNC was capable of producing the best surface finish and the lowest burr heights. However, the robot system matched and outperformed the CNC in several experiments and there is much scope for further optimization of the process. By identifying the optimum pose for drilling together with the idealized settings, the proposed drilling system is shown to be far more flexible than a CNC milling machine and when considering the optimized drilling of aerospace aluminum this robotic solution has the potential to drastically improve productivity.

Research on Self-Aligning Flanges Based on Piezoelectric Actuators Applied to Precision Grinding Machines

Laser fusion research requires a large number of high-precision large-diameter aspherical components. To improve the grinding efficiency in the component production process, the manual operation time during the grinding process needs to be reduced. The grinding process requires the installation of the dressed grinding wheel onto the grinding machine spindle, and the off-line dressing results in installation errors during the loading and unloading process, which requires more time for manual alignment. To achieve self-aligning, the circumferential contour of the grinding wheel was first restored by the reversal method, then noise reduction and circle fitting were performed to obtain the eccentricity value and eccentricity position between the flange and the spindle, and finally, the flange was adjusted finely by three piezoelectric actuators installed inside the flange to reduce the eccentricity. Three repetitive experiments were conducted to verify that the self-aligning flange can reduce the eccentricity value by retracting the piezoelectric actuators so that the proper alignment between the flange and the spindle could meet the requirements; the average eccentricity value of the three experiments decreased by 74%, which greatly improved the efficiency of the grinding wheel alignment.

MECHATRONIC CLAMPING MECHANISM WITH ELECTRO-HYDRAULIC ACTUATOR FOR MACHINE SPINDLE UNITS

The design of the clamping mechanism for fixing workpieces and tools in the spindle assemblies of machines that is equipped with an additional subsystem to provide the possibility of programmable settings to the required clamping force is presented. The electronic unit and electromechanical energy converters provide the possibility of reconfiguration by reprogramming the clamping mechanism according to the different tasks comparatively easily. The obtained results help to expand the functionality of clamping mechanisms, and consequently the functionality of machine tools and their technological flexibility.

Optimization of an Autonomous robotic drilling system for the Machining of Aluminum Aerospace Alloys

This paper aims to identify the capability of a highly flexible industrial robot modified with a high-speed machine spindle for drilling of Aluminum 6061-T6. With a focus on drilling feedrate, spindle speed and pecking cycle, the hole surface roughness and exit burr heights were investigated using the Taguchi design methodology. A state of the art condition monitoring system was used to identify the vibrations experienced during drilling operation and to establish which robot pose had increased stiffness, and thus the optimum workspace for drilling. When benchmarked against a CNC machine the results show that the CNC was capable of producing the best surface finish and the lowest burr heights. However, the robot system matched and outperformed the CNC in several experiments and there is much scope for further optimization of the process. Overall the proposed drilling system is far more flexible than a CNC milling machine and when considering the optimized drilling of aerospace aluminum this robotic solution has the potential to drastically improve productivity.

Ermitteln von Lagefehlern bei Einlippenbohrern/Determination of position errors in single-lip drills

Dieser Beitrag stellt eine berührungslose Messmethode zur Feststellung von Lagefehlern bei Einlippenbohrern vor, die auf der Verwendung eines Laser-Profilsensors basiert. Durch die Messung von Verlagerungen an mehreren Positionen entlang des langsam rotierenden Werkzeugschafts kann die Lage des Werkzeugs in Polarkoordinaten abgebildet werden. Das System bietet die Möglichkeit sowohl herstellungsbedingte Fehler als auch durch Bearbeitungskräfte und -momente verursachte Formänderungen des Werkzeugs nach verschiedenen Schnittwegen feststellen zu können.   This article introduces a non-contact measuring method, based on the use of a laser profile sensor to determine position errors in single-lip drills. By measuring displacements at several positions along the tool shaft with the machine spindle rotating slowly, the actual position of the tool can be mapped in polar coordinates. The system thus offers the potential to identify manufacturing-related errors as well as changes in the shape of the tool caused by machining forces and torques after different cutting paths.