Large scale FE (transient and stationary) simulations are prepared in the space of technological parameters (roller and shaft diameters, feed, spindle speed, desired indentation) to determine the hyperfunction for the axles rolling force. (20/9/2019)
The PI gave a plenary talk in the Hungarian Mechanical Conference (MAMEK XIII) with the title “Marási eljárások lineáris stabilitásának vonzási tartománya”.
The PI participated in the CIRP General Assembly in Birmingham, where he met with prominent researchers in the field. The group participated on a paper and presentation in the conference with the title: “Analysis of the beating frequencies in dressing and its effect in surface waviness”.
The PI organized a session with three minisymposia in the ASME IDETC-CIE MSNDC conference (MSNDC-7: Time-varying and time-delay systems, energy harvesting) with 14 participants. The group members of NKFI FK 124361 also gave presentations in the session. The PI was an author in two presentations: “Optimization of Edge Geometry of Cylindrical Milling Tools to Enhance Dynamic Stability” and “Stability of Variable Pitch Milling Tools in Interrupted Cutting Processes”, while David Lehotzky presented his work with the title “Modeling and stability of milling processes with active damping”.
The PI was one of the lecturer in the initial CISM (International Centre for Mechanical Sciences) course in Udine in Italy. The event was supported by CISM and ERC SIREN Adv grant of Prof. Gabor Stepan.
Stiffness calculation was performed by considering spring elements for the rolling parts of bearings and linear guides. This calculation showed 3.62e8 N/m stiffness by not considering the foundation of the force sensor superstructure. By using replaceable elements the stiffness can be lowered with the special design of the force sensor.
Proceeding paper was submitted to the ASME IDETC/CIE 2019 MSNDC conference with the title: "Modeling and Stability of Milling Processes with Active Damping" by David Lehotzky and Zoltan Dombovari. The paper is about the effect of digital control on regenerative time-periodic dynamical system.
Proceeding paper was submitted to the ASME IDETC/CIE 2019 MSNDC conference with the title: "Optimization of Edge Geometry of Cylindrical Milling Tools to Enhance Dynamic Stability" by Zoltan Dombovari, Daniel Bachrathy, Gabor Stepan. The paper is about the theoretical base of the general edge optimization scheme of a cylindrical milling cutter. The research was partially supported by ERC SIREN.
Abstract has been submitted to the XIII Hungarian Mechanical Conference (MAMEK 2019) about attraction zones in milling. This work was partially supported by ERC SIREN
A journal paper was accepted for publication in Materials with the title: “Optimum Selection of Variable Pitch for Face Milling Cutters” by Alex Iglesias, Zoltan Dombovari, German Gonzales, Jokin Munoa and Gabor Stepan. The research was partially supported by ERC SIREN.
Two works were participating in the student competition. One is about the effect of Kalman filters and the other one is a preliminary work on digitally controlled magnetic boring bars.
A journal paper was submitted about variable pitch angle optimization in Materials with the title: “Optimum Selection of Variable Pitch for Face Milling Cutters” by Alex Iglesias, Zoltan Dombovari, German Gonzales, Jokin Munoa and Gabor Stepan. The research was partially supported by ERC SIREN.
A talk was given in UTIS conference in Turkey about axles rolling process with the title Basic Regenerative Modelling of Axles Rolling Process by Zoltan Dombovari , Attila Szlancsik , Kristof Bobor and Ruben Merino.
The first version of the digitally controlled manuscript has been compiled. It is under in-house review.
In order to have an efficient methodology to determine the rolling force and to build-up sufficient semi-analytical mechanical model w.r.t. the technological parameters, a simple parametric FEM model is compiled. This model can run with different indentation, roller-diameter and feed. The animation is about the first successful and valid run.
The connection features for mounting the industrial roller shaft are designed on the force sensor. The connection surfaces with the bores and the perpendicular stiffening parts are ensuring the mechanical integrity of the device.
The concept drawing of the retrofitting is finished. The concept is ready for the next iteration step which will contain the force sensor in it. The workpiece is going to be the top shaft, while the roller is going to be placed underneath. This roller is capable to perform feed motion with the linear guides.
The first concept drawing of the force sensor. The forces measured on the four legs placed to the roller mounting part is enough to determine the complete 3D contact force between the roller and the workpiece shaft. The bore between the legs are the place for the threaded shaft that produces the feed motion.
The proceeding paper handled in the 14th IFAC workshop on Time Delay Systems was published online in IFAC Papers online with the title: “On Basic Modeling of the Dynamics of Axles Rolling Process” by Denes Farago, Ruben Marino and Zoltan Dombovari.
The 3D model of the old rolling mill is completed. We have measured the main geometric properties of the duo rolling mill that takes place in Department of Materials Science and Engineering. This old rolling mill is going to be the base of the high performance axles rolling measurements.
The proceeding paper was submitted and presented in the 14th IFAC workshop on Time Delay Systems.
A seminar was given by Tamás Molnar in IUTAM symposium in Novi Sad (Serbia). A two pages extended abstract was submitted with title: “Semidiscretization Method for Nonlinear Time-Periodic Time-Delay Systems”, by the authors: Tamas G. Molnar, Zoltan Dombovari, Tamas Insperger and Gabor Stepan. The talk was about the nonlinear numerical method, that is capable to predict the behavior of nonlinear periodic delayed dynamical systems.
The mesh convergence test was finished. The resulting indentation-force diagrams showed that under a certain size (4mm) of the mesh does not provide better force evolution in the case of indentation-driven calculation. This is not the case in force-driven case when the results depend greatly from the mesh size.
The problem is specified for the digitally controlled milling process.