Applied Mechanics and Materials Vol. 882

Abstract: Energy efficiency becomes a critical production factor due to legal regulations, sustainable customer-side production requirements and the increasingly volatile supply situation. Energy transparency is of crucial importance for the definition of strategic measures to increase energy efficiency. However, the transparent collection and processing of energy data in production not only forms the basis of industrial energy management, but also facilitates the additional optimization of subareas in the production environment. Especially in the context of production-related data, such as process and product quality data and production planning and control information, as well as combined with expert knowledge, energy data provides a wide range of application fields. This paper analyzes the requirements for a holistic, transparent collection and processing of energy data and identifies possible applications for the optimization of production and production-related areas.

Abstract: The paper presents an intralogistics routing-service for autonomous and versatile transport vehicles. An infrastructural sensor digitize the workspace of the vehicle and is the basis for the vehicle-specific routing plan. Nowadays, a central computing unit allocates transportation task to a known number of automated guided vehicles, which are usually of the same type. Furthermore, this device generates a routing appropriate to the dimensions and the kinematic gauge of the vehicle fleet. The pathing for each specific vehicle is calculated and the result is send to the different entities. The approach of this paper bases on the digitization of the workspace with a ceiling camera, which divides the scenery into moving obstacles and an adaptive background picture. A central computing unit receives the background picture of several cameras and stitch them together to an overview of the entire workspace, e.g. a production hall. Furthermore, the approach includes the development of automated guided vehicles to versatile autonomous vehicles, were each entity is able to calculate the pathing on a given routing plan. A fleet of versatile autonomous vehicles consists of vehicles with task-specific dimensions and kinematic gauges. Therefore, each vehicle needs its own routing-plan. The solution is that each vehicles uses a vehicle parameter-server and register itself with these parameters at the routing unit. This unit is calculating a routing-plan for each specific vehicle dimension and gauge and providing it. When getting a new task, the vehicles uses this routing-plan to do the pathing. The routing-algorithm is implemented inside the service-layer of the versatile autonomous vehicle system. This approach lowers the amount of data, which is send between the service layer and the transportation entities by reducing the information of the workspace to the possible routes of each specific vehicle. Furthermore, the calculation time for routing and pathing is lowered, because each vehicle is calculating its task-specific path, but the route-map is calculated once for each vehicle-type by the routing-service.

Abstract: This paper addresses the problem of efficiently operating a flexible manufacturing machine in an electricity micro-grid featuring a high volatility of electricity prices. The problem of finding the optimal control policy is formulated as a sequential decision making problem under uncertainty where, at every time step the uncertainty comes from the lack of knowledge about fu-ture electricity consumption and future weather dependent energy prices. We propose to address this problem using deep reinforcement learning. To this purpose, we designed a deep learning architecture to forecast the load profile of future manufacturing schedule from past production time series. Combined with the forecast of future energy prices, the reinforcement-learning algorithm is trained to perform an online optimization of the production ma-chine in order to reduce the long-term energy costs. The concept is empirical-ly validated on a flexible production machine, where the machine speed can be optimized during the production.

Abstract: When installing magnets on synchronous rotors, the target values of energy efficiency, vibration, noise emissions, power density and synchronism are decisively influenced by the quality of the rotor magnetic field. This depends on the real position of the magnets after mounting, on the polarization of the magnet and on the direction of magnetisation. However, large component tolerances in the magnet bodies also require tolerances in the rotor magnetic field. The quality assurance in the field of rotor production, which is largely lacking in the current state of the art, is compensated for by robust motor designs in order to keep the rejects low. Unconventional machine designs, such as the Halbach arrangement of the magnets, exploit optimization potential in terms of power density by eliminating the ferromagnetic component in the rotor and reduce harmonics due to the almost sinusoidal field shape, so that more efficient winding processes, such as linear winding in the stator with a constant low torque ripple compared to distributed winding, are used. At the same time, however, the requirement for homogeneity of the magnetic field increases due to the matching pairing of the magnets and the correct magnetic position when using sintered, isotropic rare earth magnets. By 100 % testing of magnets and rotors, it is possible on the one hand to exploit these design potentials and on the other hand to estimate the performance data of the motor before the final assembly test by means of data mining. In the framework of the E|MagTol project, the process feasibility of a logistics solution for storing magnetized goods has already been successfully investigated. In order to extend the potential uncovered in the previous project, it is necessary to record all process data of the rotor assembly process such as magnet geometry, magnet position, polarization and magnetization direction. The aim of E|S2MART is on the one hand to increase machine efficiency by compensating for component deviations by adapting or matching the magnetic position and magnetic parameters in a closed-loop control loop in the assembly process and on the other hand to significantly increase the energy efficiency of the assembly process. This is done by optimizing the magnetization process and coupling with inductive heating to replace the furnace process during the bonding process and to reduce the energy consumption during magnetization. On the basis of the existing process experience, the savings potential in the assembly process is estimated to be at least 70 % compared to conventional processes.

Abstract: One of the major and at the same time most critical process step in the production of electric drives is the contacting process. The purpose of this contacting process is to join the stator windings mechanically and electrically with a contact element. An innovative and energy-efficient process is the ultrasonic crimping process, which combines the two process steps of stripping and contacting in one single process. This process is characterized by the transformation of oscillation energy into thermal energy caused by damping. Due to the direct heat generation within the cable lug and the oscillation coupled in, it shows major potentials relating to process stability, the contacting of high-frequency litz wires and anodized conductors. However, some disadvantages like the occasional occurrence of fatigue fractures in the tubular cable lugs and unclear dependencies reducing process reliability have to be investigated. The following paper presents possibilities to further optimize the ultrasonic crimping process and increase the process reliability. In this context, the mounting conditions of the tubular cable lugs are considered. In order to evaluate the obtained results, the electrical and mechanical connection quality of the samples is determined.

Abstract: Laser beam welding has become an established joining technique in automotive manufacturing. Common solid-state lasers generate high-quality joints, but they provide low energy efficiency. By contrast, direct diode lasers (DDL) have superior energy efficiency, are cheaper to purchase and additionally require less utility space. To examine the overall performance of direct diode lasers in comparison to disk lasers, welding quality and energy consumption of the two lasers have to be evaluated. Additionally, for this contribution the stability of the DDL’s beam, like temporal variation of focus position and beam shape, is examined. It is found that a focus shift takes place for longer periods of emission, but the variation of the focus diameter in the initial focal plane is negligible. As expected, the direct diode laser consumes less energy than the disk laser for the same output power. Welding experiments are conducted using four different steel alloys that are exemplary for engineering materials used in automotive manufacturing. Metallographic analysis shows that weld seam depths and widths are on average larger using the disk laser. However even with the need for higher output powers to achieve equal seam geometries the DDL consumes less energy and thereby causes less costs.

Abstract: Powerful permanent magnets are of essential meaning for electric drives as well as for environmental friendly energy conversion in general. The main requirements for these applications are high energy products, coercivity and remanent polarization, thermal stability as well as affordable price. As state of the art, rare earth permanent magnets, frequently consisting of NdFeB based alloys, meet these requirements. When complex geometric shapes like arcs, shells or freeform surfaces are required by the application, a trade-off has to be taken into account between magnetic performance and post magnet-fabrication processing steps. Either bonded magnets can be produced with great variety of geometries while accepting low magnetic performance due to a significant amount of nonmagnetic plastic binder matrix, or sintered blocks with great magnetic performance have to be machined out to the specified shape accepting great effort for grinding or wire cutting as well as a significant loss of valuable material. To overcome the drawback of both conventional established magnet manufacturing processes, Laser Beam Melting (LBM) is investigated to provide an alternative process route for magnet production. This innovative Additive Manufacturing (AM) process offers tool less production of nearly any thinkable geometry by use of a metal powder bed fusing process. Due to the challenging material behavior, a detailed parameter study is presented including a systematic design of experiment (DoE) approach. The connection between process parameters, density and key performance indicators on the B/H-curve is broken down.

Abstract: This paper aims to expand the use of CO₂ blasting by investigating a cryogenic deburring method for machined metallic materials. In advance to the actual deburring experiments, a streaming analysis based on high-speed video records was conducted for different blasting technologies, in order to gain deeper knowledge about their underlying active principles. For the titanium alloy Ti-6Al-4V and the stainless steel X6CrNiMoTi17-12-2, deburring experiments with three different blasting techniques were conducted and evaluated. It has been shown that cryogenic deburring has the potential to represent an alternative deburring solution for metals.

Abstract: Fiber-reinforced plastics are known as outstanding lightweight composite material, which are used in various areas. Especially the demand for components made of carbon fiber reinforced plastics (CFRP) has steadily increased within the last years due to their high strength and stiffness combined with light weight. The manufacturing of CFRP components is a cost-intensive and time-consuming process due to frequently required and challenging manual operations for several working steps. In order to remain competitive and meet the small-batch production because of increasing desire for individuality and diversity, the manufacturing process of CFRP components needs further development. In order to face these challenges, this paper focuses on the resource efficiency of curing processes with the autoclave technology. The measurement analysis of the different energy consumers of the autoclave at changing the curing parameters (temperature, pressure, time) shows how the settings affect the resource efficiency of curing processes. Finally, the authors present their recommendation for action in order to increase resource efficiency.

Abstract: The partitioned stator flux reversal machine (PS-FRPM) is a novel stator PM machine topology, which exhibits a higher torque capability than its single stator counterpart and the conventional permanent magnet synchronous machine (PMSM). The PS-FRPM consists of two stators, one which carries the armature winding, and one which is equipped with surface mounted permanent magnets. The rotor is sandwiched between the two stators. The separation of the stator allows a better utilization of the machine volume which results in a higher torque density. Furthermore, because the magnets are placed on a stationary component, they can be cooled effectively. Consequently, critical rare-earth materials can be saved.The structure of the PS-FRPM is very similar to that of magnetic gears. In this paper the torque production of a PS-FRPM is described by means of the magnetic gearing effect. First the magnetic gearing effect is introduced and then the corresponding analytics is transferred to the PS-FRPM. Based on Maxwell's stress tensor, the torque contributions of the individual space harmonics are determined. In contrast to conventional machines, the torque in PS-FRPM is produced by several space harmonics in both air gaps.