Publications

Multi-stage process chains are often used for the efficient production of complex geometries. These consist of a homogeneous heating, one or more preform stages and the final forging step. Via inhomogeneously heated blanks, the process chains are to be simplified or shortened. This is to be achieved by setting several, clearly defined temperature fields in which different yield stresses are present. These can influence the material flow, leading to an easier production of complex parts.

inhomogeneous heating, bulk forming, preforming processes

To this day, the design of preforms for hot forging processes is still a manual trial and error process and therefore time consuming. Furthermore, its quality vastly depends on the engineer’s experience. At the same time, the preform is the most influencing stage for the final forging result. To overcome the dependency on the engineer’s experience and time-consuming optimization processes this paper presents and evaluates a preform optimization by an algorithm for cross wedge rolled preforms. This algorithm takes the mass distribution of the final part, the preform volume, the shape complexity, the appearance of folds in the final part and the occurring amount of flash into account. This forms a multi-criteria optimization problem resulting in large search spaces. Therefore, an evolutionary algorithm is introduced. The developed algorithm is tested with the help of a connecting rod to estimate the influence of the algorithm parameters. It is found that the developed algorithm is capable of creating a suitable preform for the given criteria in less than a minute. Furthermore, two of the five given algorithm parameters, the selection pressure und the population size, have significant influence on the optimization duration and quality.

preform optimization, genetic algorithm, cross wedge rolled, adaptive flash

Bulk-formed components are used in many applications in automotive and plant engineering. The conditions under which the components are manufactured, often at more than 800°C and thousands of tons of forming force, lead to high die wear. One way to reduce wear is to use suitable protective coatings. Initial basic investigations showed that the use of hard Diamond-like Carbon (DLC) wear-resistant coatings can significantly reduce the tribological effects on the die surface. With new methods such as the use of multilayer layer coatings and temperature measurement on the die surface by use of thin layer sensors, the potential of wear protection for semi-hot massive forming is to be investigated and expanded.

DLC, hot forging, wear

The melt level and oxide layer quantity in an aluminum melting furnace cannot be monitored by contact sensors, since the melting bath is not accessible due to the high holding temperature (above 600°C). Therefore, the method of monitoring the melting bath by means of optical sensors is investigated for the first time. For this purpose, suitable optical measuring systems can be applied which will be able to record the melting bath. The height change of the melt is to be elaborated by means of image analysis and any oxide layer on the bath surface is to be detected.

aluminum melting furnace, metling bath monitoring, oxide layer

Abstract: For factory planning projects the layout capturing and layout processing process need a huge amount of effort, because they are typically done by hand. These processes could be accelerated and optimized by using a drone and automated analysis algorithms. Furthermore, this article shows a way to raise the digitization level for industrial processes. The key aspect lies on the usage of a drone in indoor environment and the processing of three-dimensional point cloud models for factory planning processes.

drone, factory planning, 3D-factory layout, object recognition

For the establishment of innovative manufacturing processes, consistent results and increased tool life is very important. When using slider tools in multidirectional forging processes, tool life identification has not been occurred yet. For the industrial implementation of slider tools, the influence of different process parameters on the resulting tool life is to be determined and a construction guideline for tool life increasement is created.

multi-directional forging, tool life optimization, design guidelines, toolmaking

The CO2 emissions of the logistics sector and the resulting environmental impact are continuously increasing. Rising costs for energy and resources, increased sensitivity of customers, changed legal bases and the impending climatic change force producing enterprises to ecologically-oriented rethink. The lack of knowledge about interdependencies, quantitative effects of actions and parameter characteristics prevents SMEs from the implementation. A holistic ecological-logistical impact model with software implementation can support SMEs reaching their potential. Requirements for the model and fundamental relationships between logistic parameters and ecological target values are presented in this publication.

SME, logistic, ecology

Since 2015 the Mittelstand 4.0 Centre of Excellence "Mit uns digital!" informs SMEs in Lower Saxony and Bremen about the opportunities and challenges of digitalisation. Now the funding from the Federal Ministry of Economic Affairs was renewed.

digitalization, industry 4.0, SMEs

Material efficiency and the development time of a forging sequence are decisive criteria for increasing the economic efficiency in the production of complex forgings. SMEs can often only interpret forging sequences in a shortened form due to insufficient capacities and high competitive pressure. Therefore, a generally valid method is to be developed that automatically generates multi-stage, efficient forging sequences based on the mass distribution of any forged part.

automated process design, die forging, resource efficiency

More and more players in the German wind energy sector are concerned with the question of how to deal with the aging German wind fleet, as around 5,200 turbines will simultaneously reach the end of the feed-in tariff funding period of the Renewable Energy Sources Act (EEG) for the first time at the end of 2020. Around 8,000 wind turbines will follow by the end of 2025, as shown in Figure 1. Operators of affected wind turbines will then have the choice between (I) continuing to operate the old turbine within the framework of direct marketing on the European Power Exchange, (II) repowering the old turbine by a new and more efficient wind turbine at plant-specific feed-in premium levels tendered in the German renewable energy auctions or (III) decommissioning the respective plant finally.

However, the question of choosing the right option arises not only for the operators themselves, but also for various other players in the wind energy sector:

Project developers, turbine manufacturers, and investors are interested in evaluations of plant-specific repowering potentials in the existing wind turbine fleet in order to provide operators with targeted support in implementing new projects; dismantling contractors and disposal companies particularly search for derivatives of plant-specific dismantling potentials and the associated disposal and recycling flows in order to enable optimal handling of the comprehensive dismantling processes; and regional as well as supra-regional public and political institutions are interested in estimates of changes to the installed wind energy capacity in order to enable optimal control of future capacity expansion under consideration of societal, economic and political aspects.

dismantling, wind turbine

Belt conveyor systems are an excellent way to handle bulk material. As loads and distances increase, those systems become bigger and energy efficiency becomes an important factor. The energy consumption of belt conveyor systems is primary determined by the drive power. The drive power is the sum of the main drive power and the power of all intermediate drives, if present. The implementation of driven support rollers allows to reduce the load on the conventional drive based at the head of a conveyor system, by splitting it to multiple driven rollers. The main drive can be build smaller, which leads to a lower energy consumption and therewith to cost savings during the production. Furthermore, driven rollers enable the concept of modular belt conveyor systems, what would be impossible with the conventional head drives. This gives planners more flexibility for engineering new or modifying existing conveyor systems.

Despite the great opportunities and promising characteristics of driven rollers, they yet have not been used in daily operation. Without having sufficient knowledge about the behavior of driven rollers under certain conditions, as heat or cold, and the economic efficiency of them, the benefit is questioned. To bridge the lack of knowledge, investigations and research need to be done. A test rig for driven rollers is indispensable to develop this technology into a marketable commodity. At the same time a test process needs to be implemented.

This paper gives an overview about driven rollers and an accurate insight in the development of a test rig for investigating driven rollers. With this test rig, the use of driven rollers can be simulated under certain climatic conditions. Moreover, different loads and speeds can also be simulated by using state-of-the-art technology.

Driven roller, belt conveyor system, energy efficiency, test rig, cost savings

In this paper, the validation of an inductive sensor for an energy self-sufficient sensor for condition monitoring of wet-running steel disc clutches in marine gearboxes is presented. For a reliable operation of these a permanent monitoring of their state is advisable. As part of condition-based maintenance, more and more sensors are being installed in machines. Reliability becomes even more important when people are endangered by possible failure of the machines. In shipping, it is essential that, for example, the powertrain and thus the transmission are in perfect condition. In case of long distance traveling, wear or even damage of important components has to be known so that maintenance can be carried out proactively. To address this need an energy self-sufficient and wireless sensor network is developed. Miniaturized sensor nodes monitor torque, rotational speeds, temperatures as well as the wear condition of the torque transmitting components. The energy needed to operate these sensors is obtained from the surrounding environment. Thus, the system operates wirelessly and without an external energy supply, whereby the installation and maintenance costs decrease significantly. In addition to the concept of sensor integration in the transmission, the energy harvesting concept is also described in more detail. Finally, measurements are taken in a gear-like environment and the behavior of a magnetoinductive sensor in a not constantly supplied situation has been examined.

ship, gearbox, wear, sensor, torque

At the end of 2020, around 6,000 wind turbines will simultaneously fall out of the 20-year subsidy under the Renewable Energy Sources Act (EEG) for the first time. Around 8,000 further wind turbines will follow by the end of 2025. Operators of affected wind turbines will then have the choice between continuing to operate the old turbine at the significantly lower spot market prices of the European Power Exchange (EPEX), operating a new and more efficient wind turbine at the site of the old turbine (repowering) at auctioned conditions or finally decommissioning it. Quo vadis 20 years old Wind trubines? Scientists from the Institut für Integrierte Produktion Hannover (IPH) have therefore been working on the "DemoNetXXL" project, funded by the German Research Foundation (DFG), in cooperation with the Institute for Information Systems at Leibniz University Hanover on the selection and design of optimal post-utilisation strategies for wind power plants.

wind turbines, plants repowering, post-use strategies, dismantling

In lightweight automotive construction, hybrid structures made of various materials as well as solid and sheet metal elements are used. By hybrid compound forging, a sheet steel and a solid aluminium part can already be joined in a material-locking manner during the forming process. The Institut für Integrierte Produktion Hannover (IPH) gGmbH and the Institut für Schweißtechnik und Trennende Fertigungsverfahren (ISAF) of TU Clausthal are investigating how solid aluminium bolts and steel sheets can be joined in a material-locking manner. This article explains the decisive forming parameters. Furthermore, the tool design for the joining tests is presented.

lightweight construction, aluminum, compound forging

The joint is the weak point at a hybrid metal semifinished product in tube hydroforming. In real forming processes, a deformation at the joint would be prevented in order to avoid failure. A better knowledge of the forming behavior enables to reduce the effort in process design. Thus, this study investigates in hybrid material combinations and the forming behavior of the joint area regarding their suitability for tube hydroforming.

hydroforming, tube, steel-aluminum, FEA

This paper describes the development and prototypical implementation of an energy self-sufficient sensor for condition monitoring of wet-running steel disc clutches in marine gearboxes. For the precise control of an automated system and the monitoring of its performance, the knowledge about the possible wear is an essential prerequisite. In addition, the storage of sensor data over the life of the system offers the possibility of long-term condition monitoring. The combination with various other technological components creates a solution that enables cost-effective condition monitoring of marine gearboxes. Compared to existing systems, for example, the costs for installation and maintenance are significantly reduced. Both the methodology from the morphological box to the fine concept as well as the first measurements of the sensors are presented.

automated system, condition monitoring, metrology, clutch, gearbox

Lightweight automotive construction increasingly relies on hybrid structures made of steel and aluminium. These materials are currently joined mainly by form locking, for example by riveting. Welding and bonding are also used for joining the two materials. Hybrid composite forging allows to join the two components during the forming process. This shortens the process chain. With the help of zinc as a brazing material, the components are joined to form a material bond. This publication explains the results of the simulative parameter study. It shows how temperature, geometry and speed influence the joining result. Furthermore, first results of practical joining tests are presented.

lightweight construction, aluminum, simulative parameter study

Resource depletion and climate change are the main drivers for the rapid change of power generation structures. The energy transformation is causing an increase in energy prices for manufacturing small and medium-sized enterprises (SMEs). Within the last decade energy prices in Germany have doubled and are expected to grow even further . Metal processing SMEs are already attributing 4.5 percent of their gross production value to electricity costs. The paper shows the possible savings potential of the use of inventory levels as energy storage and provides approaches to an efficient solution of the associated optimization problems.

production program planning, energy costs, inventory level, energy storage

So far, the design of automated guided vehicle systems (AGVS) as well as the disturbance management in AGVS is in need of human experts. In order to design an AGVS or clear an occurring disturbance a system expert has to work through defined process steps manually. This work?ow does not only demand expert knowledge but causes high costs and the proposed solutions are often limited to the experiences of the expert. The following paper introduces the development of a case-based reasoning expert system for an automated proposition of solutions for disturbances in AGVS and discuss related work in the feld of expert systems for the design support of AGVS.

expert system, automated guided vehicle systems, disturbance management

In average, more than 1,275 wind turbines were installed annually since 1997 in Germany and more than 27,000 wind turbines are in operation today. The technical and economic life time of wind turbines is around 20 to 25 years. Consequently, dismantling of aging wind turbines will increase significantly in upcoming years due to repowering or decommissioning of wind farms and lead to millions of costs for operators. An option to supersede the costly and time-consuming dismantling of wind turbines entirely on-site is to establish a dismantling network in which partly dismantled wind turbines are transported to specialized dismantling sites for further handling. This network requires an optimization model to determine optimal locations and an appropriate distribution of disassembly steps to dismantling sites. The challenge is to consider the networks dependency on the trade-off between transportation and dismantling costs which, in turn, depends on the selection of dismantling depths and sites. Building on the Koopmans-Beckmann problem, we present a mathematical optimization model to address the described location planning and allocation problem. To permit a proof-of-concept, we apply our model to a case-study of an exemplary wind farm in Northern Germany. Our results show that the model can assist dismantling companies to arrange efficient dismantling networks for wind turbines and to benefit from emerging economic advantages.

dismantling, wind turbine, optimization model

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