Publications

Within the Collaborative Research Centre (CRC) 1153 “Tailored Forming “the manufacturing of hybrid bulk components is investigated. Therefore, a process chain consisting of joining, forming, milling and quality control has been established by multiple subprojects.Within subproject B1 of the CRC forming of hybrid parts by the incrementally forming cross-wedge rolling (CWR) process is investigated. The superior aim is to determine process limits and capabilities, when forming parts consisting of different materials joined by varying technologies.

In this paper, the investigation of cross-wedge rolling of serially arranged hybrid parts made of steel and aluminum is described. The focus of the research presented in this publication is the displacement of the joining zone of hybrid parts due to the cross-wedge rolling process. Therefore, finite element simulations have been developed, that allow the investigations of hybrid solid components. After simulation of various variations of the cross-wedge rolling process, i.e.  differently shaped tools and forming velocities, experimental trials were carried out with identical parameter sets. A comparison of simulation and experiment, showed that the simulation model is capable of describing the cross-wedge rolling process of hybrid parts. The standard deviation of the displacement of the joining zone between simulation and experimental trials is 8.8% with regard to all investigated cases.

tailored forming, cross-wedge rolling, material forming, aluminum, steel

Within the Collaborative Research Centre (CRC) 1153 Tailored Forming a process chain for the manufacturing of hybrid high performance components is developed. Exemplary process steps consist of deposit welding of high-performance steel onto low cost steel and pre-shaping the component by cross-wedge rolling (CWR), supported by an optical quality control system. A combination of a fringe projection profilometry setup with a thermal imaging camera is used to monitor the components before and after the CWR process. Both geometry and thermal imaging data are combined, assigning temperature values to 3D data points.
In this paper, the acquisition of combined temperature-geometry data is described. The data before and after the CWR is compared to the input and the result data of the forming simulation that was used to design the CWR process. The comparison shows the quality and sustainability of the heating process as well as the influence of the transportation of the hot component prior to forming. Additionally, the accuracy of the used simulation model and software are evaluated by data examination. The examination shows the limits of idealised and simplified assumptions for the simulation, e.g., a homogeneous temperature distribution before forming or the modelling of the heat transfer on contact surfaces.

tailored forming, cross-wedge rolling, material forming, aluminum, steel, optical measurement

Within the Collaborative Research Centre 1153 “Tailored Forming“ a process chain for the manufacturing of hybrid high performance components is developed. Exemplary process steps consist of deposit welding of high performance steel on low-cost steel, pre-shaping by cross-wedge rolling and finishing by milling.
Hard material coatings such as Stellite 6 or Delcrome 253 are used as wear or corrosion protection coatings in industrial applications. Scientists of the Institute of Material Science welded these hard material alloys onto a base material, in this case C22.8, to create a hybrid workpiece. Scientists of the Institut für Integrierte Produktion Hannover have shown that these hybrid workpieces can be formed without defects (e.g. detachment of the coating) by cross-wedge rolling. After forming, the properties of the coatings are retained or in some cases even improved (e.g. the transition zone between base material and coating). By adjustments in the welding process, it was possible to apply the 100Cr6 rolling bearing steel, as of now declared as non-weldable, on the low-cost steel C22.8. 100Cr6 was formed afterwards in its hybrid bonding state with C22.8 by cross-wedge rolling, thus a component-integrated bearing seat was produced. Even after welding and forming, the rolling bearing steel coating could still be quench-hardened to a hardness of over 60 HRC. This paper shows the potential of forming hybrid billets to tailored parts. Since industrially available standard materials can be used for hard material coatings by this approach, even though they are not weldable by conventional methods, it is not necessary to use expensive, for welding designed materials to implement a hybrid component concept.

tailored forming, cross-wedge rolling, hard material coatings, PTA

By using digital tools in the factory planning process, the planning quality can be improved and the duration of the project can be shortened. In order to exploit these potentials, data consistency must be guaranteed throughout the planning process. In this article, digital factory planning tools, used at the Institut für Integrierte Produktion Hannover (IPH), will be presented and their applications and requirements will be discussed.

digital factory planning, factory planning process, data consistency, digital tools

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

By automating process steps, additive manufacturing can be integrated into industrial value chains. The Institut für Integrierte Produktion Hannover (IPH) gGmbH has been designing a process chain linking 3d printers and mounting stations automatically.

additive manufacturing, 3D printing

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

Drones are often used in outdoor areas. Though drone are able to do more, e.g. to measure and digitalize the indoor layout structure of production environments. Further more it is possible to plan the production structure directly in the digital model with image processing algorithms. The combination of both step allows a faster and more efficient production planning process. 

drone, layoutscan, production planning, digitalization

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

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