Markus Hubert

Continuous rotational cutting of laminations for electric drives: Cutting process and tool setups for rotational cutting of laminations

Rotational cutting of stator and rotor laminations has the potential to bridge the gap between laser cutting in the production of prototypes and high-speed punching in mass production. Furthermore with this process, a technological answer to the production of ever thinner stator and rotor laminations can be found in which high-speed punching is reaching its technical limits. In this paper the process for rotational cutting of thin electric sheets is described in general and various concepts for tooling setups are presented. In addition it is described how the deviating process chain in the manufacture of cutting cylinders leads to a change in the product geometry.

Process and Energy Data Acquisition on Machining Center and Individual Machine Components

This paper describes possibilities of process and condition data acquisition on universal milling centers with Sinumerik 840D-sl control. The measurement and process data is gathered mostly with the present control system architecture of the machine tool. This internal data collection has been extended by additional sensors and an external measurement system to enable further and partially deeper analysis. This setup is also explained in this publication. The demonstrator together with the measuring system allows an investigation of the introduced components close to reality and the observation of the overall system at once. The latter is considered energetically on a comparative measurement to ascertain discrepancies in energy consumption between two different milling strategies for a pocket cycle.

Rotary cutting as an alternative method in the processing of electrical steel strip: Geometric and kinematic determination of the process setup

Improving the efficiency in production is always the aim. In many applications, where progressive stamping approaches the technological limits, rotary cutting is successful. Relevant applications to name are the processing of paper, card boxes, packaging and simple perforated steel profiles. The main limiting factors of the stamping technology are the accelerations and decelerations in sheet feed and stamping motion. In contrast rotary cutting is a continuous process which leads to greater speeds and higher output. While performing the electrical steel strip between two cylindrical tools in stamp and die arrangement, the laminations are being cut out. Rotary cutting in the manufacture of laminations is a great challenge and a research topic at the Bavarian Technology Center for Electric Drives at the FAU. This paper provides the main technological differences between progressive stamping and rotary cutting regarding the process structure. Furthermore the geometric and technical parameters of the rotary cutting process are described mathematically. Finally the correlation of process parameters are identified.

Laserschneiden in der Elektroblechfertigung

Kurzfassung Die Fertigung elektrischer Antriebe steht auf dem Prüfstand. Bekannte Prozessketten werden auf Grund des Einstiegs der Automobilindustrie grundsätzlich hinterfragt, optimiert, und teils völlig neue Werkstoffe im Stator und Rotor fordern traditionelle Prozesse, wie z. B. das Stanzpaketieren, zunehmend heraus. Obwohl das Laserschneiden von Elektroblechen in vielen flexiblen Produktionen bereits seit Jahren zum Einsatz kommt, liegt die Produktivität im direkten Vergleich noch um einige Größenordnung unter den verfügbaren Stanzverfahren. In der Forschungsgruppe des Bayerischen Technologiezentrums für elektrische Antriebstechnik (E|Drive-Center) am Lehrstuhl für Fertigungsautomatisierung und Produktionssystematik der Friedrich-Alexander-Universität Erlangen-Nürnberg werden daher Rationalisierungseffekte beim Laserschneiden durch neuartige Ansätze erforscht und der Automatisierungsgrad gezielt erhöht.

Explicit finite element analysis for rotary cutting of electrical steel sheet

Rotary cutting of rotor and stator laminations complements the available methods in the processing of electrical steel sheet. Furthermore, with this process, a technological answer to the production of ever-thinner laminations can be found in which high-speed stamping is reaching its technical limits. This paper explicates a finite element analysis for the rotary cutting process of electrical steel. First an overview of the cutting process and its peculiarities is given. Then the setup for the FEM simulation and its material model are explained. Finally followed by a discussion of simulation results with different parameters.

Energetic Simulation of Complex Mechatronic Drive Systems over Complete Drive Cycles

This paper presents a simulation model, which enables the energetic simulation of complex mechatronic powertrains over complete drive cycles. One focus of this work is on reducing the simulation duration to enable the simulation of extended drive cycles on the one hand, and the possibility to optimize drive cycles on the other hand. Furthermore, the program allows the user to assemble an energetically optimized selection of propulsion components.

A System Embracing Observation of Different PTFE-Compounds in the Sealing Application of Rotary Manifolds

Due to the increase of product complexity, 5 axes machining centers are becoming more and more important. Rotary tables are usually chosen for the 4th and 5th axis. Additional hydraulic or pneumatic mounting clamps are often needed on these tables. The feeding of the required media is realized by a so-called rotary manifold. For this application, commonly several rotary seals are used to seal the transmitted media. Different sealing materials, based on the carrier polymer PTFE, have been examined during this research. In tribological model tests, friction and wear characteristics have been investigated during an oscillating movement under dry run conditions and equal load spectrums (surface pressure). The counter running surfaces were specific textured as a result of various machining processes to research the effects of possible micro-and macroscopic patterning on the sealing system. The tribological behavior of the analyzed combinations and the topography of the counter surfaces have been evaluated.

Coupled Thermal and Fluid Mechanical Modeling of a High Speed Motor Spindle

The objective of this survey is to evolve a better understanding of the complex thermal interactions inside a motor spindle. Therefore, the thermal behavior is investigated based on a simulation model and experiments. In contrast to existing simulation models, which either performed a complex thermal examination or an elaborate flow-mechanical analysis, a thermal (Finite Element Method) and fluid mechanical (Computational Fluid Dynamics) coupled simulation model was developed. Based on a comparative analysis, the usability of the currently available boundary conditions is scrutinized.

Rotary Cutting of Electrical Steel Laminations – A Contrast to Traditional Stamping

A R T I C L E I N F O A B S T R A C T Article history: Received: 30 April, 2017 Accepted: 12 June, 2017 Online: 16 July, 2017 Rotary cutting of electrical steel laminations is a novel, promising alternative in the processing of electrical steel strip with enormous economical and technical potentials. This paper is an extension of work originally presented on the 6th International Electric Drives Production Conference (E|DPC) in Nuremberg, Germany 2016. The scope of this paper includes a theoretical description of the rotary cutting process, an explanation of the machine and tooling setup, the basics of the Toroidal Core Tests and a discussion of the theoretical and experimental results. The methodology applied is basing on the Toroidal Core Test per DIN 60404-6, which is elementary described in section 3. Toroidal core tests allow a characterization in regards of technical, process and functional aspects, what is also mainly extended in this work. Finally, a classification of the rotary cutting process into existing processing technologies of electrical steel strip is feasible with respect to its limits and possibilities.

Influence of cutting edge on core loss induced through various manufacturing parameters

Various manufacturing processes in the production - from laminated magnetic steel sheets to an assembled stator - affect the electromagnetic characteristics. Often the manufacturing processes of the process step cutting are compared to highlight differences. Many publications have already dealt with this issue over several decades. Flux distribution, loss and the B-H characteristics are not the same, whether an electrical sheet with defined geometry is cut with a laser, water jet, electrical discharge machining, rotational cutting or with a punching machine. It is adequately researched that differences in loss behavior occur. Within the various technologies, a comparison of varied production parameters is scarcer. Here, interesting studies result when considering the specific hysteresis and eddy current losses in the variation of the process parameters on the relative position of the rolling direction, average speed, distance energy and the comparison between fiber and CO2-Laser with different focus diameters. This paper deals with the comparison of cut sheets made from electrical steel with grade M270 35A. The metal strips investigated were prepared on dimensions of 150×150 mm and 37,5×150 mm using the above parameter variation and analyzed in a single sheet tester from Brockhaus regarding their loss behavior.