One research topic of the Institut für Integrierte Produktion Hannover (IPH) is the avoidance of worker overload in production during job shop scheduling to eliminate production errors, improve product quality and reduce cost.
job shop scheduling, human performance curve, error costs
Ross, J.; Nothdurft, S.; Langner, J.; Springer, A.; Kaierle, S.; Behrens, B.-A.: Innenhochdruckumgeformte laserstrahlgelötete Tailored Hybrid Tubes aus Stahl-Aluminium-Mischverbindungen für den automobilen Leichtbau. In: Energie / Effiziente Verarbeitung zukunftsweisender LeichtbauWerkstoffe; Tagungsband T 44 des 37. EFB-Kolloquiums Blechverarbeitung 2017, 28./29. März Fellbach, EFB Hannover 2017; S. 125 – 133. ISBN 978-3-86776-503-9
A main target in automotive engineering research and development is currently to reduce fuel consumption and CO2 emissions. Therefore in this project lightweight design was combined with material design in order to produce more efficient structural components. The joining process for tubes of steel and aluminum by laser brazing was investigated to create a joint area that is highly formable. These steel-aluminum joints were afterwards hydroformed, at which steel and aluminum parts were formed in a single step. This process is called "IHU-THT" and can provide lightweight components with excellent mechanical properties.
FEA, hydro forming, tailored forming
Most of today’s technical parts and components are made of monolithic materials. These mono-material components produced in established production processes reach their limits due to their respective material characteristics. Thus, a significant increase in production quality and efficiency can only be achieved by combining different materials in one part. Bulk forming of previously joined semi-finished products to net shape hybrid components that consist of two different materials is a promising method to produce parts with locally optimized characteristics. This new production process chain offers a number of advantages compared to conventional manufacturing technologies. Examples are the production of specific load-adapted forged parts with a high level of material utilization, an improvement of the joining zone caused by the following forming process and an easy to implement joining process due to the simple geometries of the semi-finished products.
This paper describes the production process of hybrid steel parts, produced by combining a plasma-transferred arc deposition welding process with a subsequent cross wedge rolling process. This innovative process chain enables the production of hybrid parts. To evaluate the developed process chain, coating thickness of the billet is analysed before and after cross wedge rolling. It could be shown, that the forming process leads to an improvement of the coating, meaning a more homogeneous distribution along the main axis.
process chain, plasma-transferred arc deposition welding, hybrid parts, cross wedge rolling
In recent years, the requirements for technical components have steadily been increasing. This development is intensified by the desire for products with lower weight, smaller size and extended functionality, but also higher resistance against specific stresses.
The superior aim of the Collaborative Research Centre 1153 "Tailored Forming" is to develop potentials for hybrid solid components on the basis of a new process chain by using joined semi-finished workpieces.
This paper presents the approach and first results of selected subprojects for semi-finished workpiece production by composite extrusion presses, for forming the hybrid semi-finished products by means of cross wedge rolling, die forging and extrusion, and numerical failure prediction of the joining zones. This provides an overview of possible lightweight strategies in the area of bulk forming by the use of pre-joined semi-finished workpieces.
tailored forming, semi-finished workpiece production, forming, cross wedge rolling
Different challenges arise in cross wedge rolling hybrid parts depending of the material arrangement (serial or coaxial) which need to be investigated fundamentally first.
In cross wedge rolling of serial components, the controlled forming of the joining zone is the greatest challenge. The forming behaviour of the component halves is different, depending on the flow stress of the materials used. In order to allow the forming process to be carried out in a controlled manner, the forming behaviour was first analysed with regard to the displacement and quality of the joining zone, and then possibilities were determined with which the forming can be effected in a targeted manner. For this purpose, the influencing parameters (workpiece temperature, forming speed, cross-section reduction, shoulder and wedge angle) were determined systematically using the Finite Element method, and the investigations were then verified experimentally. In order to influence the forming behaviour the investigations include structural measures (e.g. unequal tool halves) as well as process-related parameters (e.g. unequal temperature distribution).
Cross wedge rolling of coaxial components has other challenges due to the component construction. The aim is to be able to specifically influence the course of the thickness of the applied coating during the forming. Therefore finite element simulations were carried out to determine the influencing parameters. By a systematic investigation of the test parameters according to the DoE method, the layer thickness before the deformation as well as the cross-section reduction are parameters with the greatest influences on the course of the layer thickness after the deformation gave. The results obtained were subsequently verified in experimental tests.
cross wedge rolling, steel, aluminum, joining zone, coating thickness
This paper proposes a method for the automated generation of roadmaps for AGVs. So far the roadmaps are mostly generated manually, which leads to long and laborious planning phases. The presented method incorporates both mathematical roadmap algorithms as well as human knowledge in the form of a fuzzy inference system. The results of the expert system are evaluated in comparisons to the A* algorithm and to manually generated roadmaps on a real production layout. In both cases the expert system performs better.
fuzzy logic, expert system, AGV, roadmap
Automated guided vehicle systems (AGVS) have become indispensable in advanced production facilities. Due to significant progress in the field of automated guided vehicles (AGVs) and the increased automation within production plants, the potential applications for AGVs increase. The design of the roadmap for automated guided vehicle systems is a time-consuming process which is currently performed manually for the most part. Because of the AGVs increasing degree of complexity a manual design of the roadmap becomes more and more difficult and challenging. In the course of the research project “Automatic design of the roadmap for automated guided vehicle systems” (IG 18007) a software demonstrator was developed which allows the automated generation of the roadmaps for AGVS. The software demonstrator was applied to real reference scenarios and it was proven that the automatically generated roadmaps are as reliable as the manually generated ones and in some cases even more efficient.
fuzzy logic, expert system, AGV, roadmap
The volatility of electricity prices is steadily increasing due to the growing expansion of renewable energies. This is particularly observable at the electricity exchange. Small and medium-sized enterprises (SMEs) in the manufacturing sector can save energy costs due to these fluctuations through targeted load management methods. To increase this potential, SMEs need to use smart meters and obtain their electricity at pricest as close to those at the electricity exchange as possible.
power procurement, electricity exchange, load management, electricity costs
Mach, F.; Hund, E.; Stonis, M.: A Control Model for the Dismantling of Industrial Plants. In: World Academy of Science, Engineering and Technology, International Science Index 122, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering, 11. Jg. (2017) H.2, pp. 167 - 176.
The dismantling of disused industrial facilities such as nuclear power plants or refineries is an enormous challenge for the planning and control of the logistic processes. Existing control models do not meet the requirements for a proper dismantling of industrial plants. Therefore, this paper presents an approach for the control of dismantling and post-processing processes (e.g. decontamination) in plant decommissioning. In contrast to existing approaches, the dismantling sequence and depth are selected depending on the capacity utilization of required post-processing processes by also considering individual characteristics of respective dismantling tasks (e.g. decontamination success rate, uncertainties regarding the process times). The results can be used in the dismantling of industrial plants (e.g. nuclear power plants) to reduce dismantling time and costs by avoiding bottlenecks such as capacity constraints.
dismantling management, logistics planning and control models, nuclear power plant dismantling
Researchers at the Institut für Integrierte Produktion Hannover (IPH) have developed a software programme for an objective evaluation of factory layouts. With this tool, you can select your optimum layout numerically instead of following your gut instincts.
factory planning, layout evaluation, optimization procedures
Large-scale products are often assembled according to the job-site principle, meaning the product is not moved through the factory while assembly but located at a fixed position. Though, during the assembly, the area requirements of such a product are constantly changing. On one hand, the product itself is growing with each assembly step, while on the other hand varying areas for storage, machines or working areas are temporarily required. This is an important factor when arranging products to be assembled within the factory. Currently, it is common to reserve a fixed area for each product to avoid overlaps or collisions with other assemblies. Intending to be large enough to include the product and all adjacent areas, this reserved area corresponds to the superposition of the maximum extents of all required areas of the product. In this procedure, the reserved area is usually poorly utilized over the course of the entire assembly process; instead a large part of it remains unused. If the available area is a limited resource, a systematic arrangement of the products, which complies with the dynamic area requirements, will lead to an increased area utilization and productivity. This paper presents the results of a study on the arrangement of assembly objects assuming dynamic, competing area requirements. First, the problem situation is extensively explained and existing research on associated topics is described and evaluated on the possibility of an adaptation. Then, a newly developed mathematical optimization model is introduced. This model allows an optimal arrangement of dynamic areas, considering logical and practical constraints. Finally, in order to quantify the potential of the developed method, some test series results are presented, showing the possible increase in area utilization.
XXL products, dynamic area arrangement, layout planning
A three step process chain with cross wedge rolling multi-directional forging and final forging would save time and money but leads to high wear at the dies. The cross wedged rolled perform can be described by forming angle and cross section area reduction. Depending on the preform geometry and the offset of the middle axis at the multi-directional forging a different amount of wear at the dies is generated. This paper shows the results of the investigation of the abrasive Archard-wear at the dies at the multi-directional forging. A short contact time, a low forming angle, ahigh cross section area reduction and a low offset of the middle axis all lead to a small depth of abrasive wear at the dies
die wear, multi-directional forging, cross wedge rolling
In production, product-based failure costs can be reduced by focusing the production factor „human“. Therefore, human performance fluctuations during the course of day have to be considered in the production planning and control. This paper presents an approach for quality-orientated flexible job shop scheduling, taking into account human performance fluctuations during the day.
production planning and control, performance curve, quality
Uttendorf, S.; Eilert, B.; Overmeyer, L.: A fuzzy logic expert system for the automated generation of roadmaps for automated guided vehicle systems. In: 2016 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM), (2016), p.977-981. DOI: 10.1109/IEEM.2016.77980232016.
So far the generation of roadmaps for automated guided vehicles (AGVs) is mostly performed manually. Mathematical path finding algorithms often return results that are mathematically optimal but not applicable to a real production layout. This paper proposes an expert system as a solution that combines traditional path finding algorithms (in the form of a modified version of the A* and the Bellman-Ford algorithm) with a fuzzy inference system that incorporates the human knowledge of AGV system planners. Results that prove the efficiency of the proposed solution are shown in the end.
roadmaps, automated guided vehicles, path planning, fuzzy logic
Whether aircraft, ships or construction machines: The assembly of so-called XXL products requires a lot of space. Researchers at IPH are currently developing a method which enables companies to find an ideal layout. By this means, they can save space and increase their productivity.
XXL products, area arrangement
Data glasses or data gloves as a novel human-machine interface allow intelligent networking within the Smart Factory. Due to lack of implementation strategies small and medium-sized enterprises hesitate to integrate these technologies in production and logistics. In this context, the following article describes a maturity-based approach for a systematic and holistic planning and controlling of the implementation of these interactive assistance systems (IAS).
industry 4.0, maturity model, interactive assistance system, data glasses
A low energy demand and a fast processing time are required in each industrial process for the production of crankshafts. Crankshafts have a very complex geometry and are forged with a high percentage of flash compared to other forging parts. Recent research showed the feasibility of a flashless forging of crankshafts. One way to forge a flashless crankshaft within three steps is to use cross wedge rolling, multi-directional forging and final forging.
This paper presents the investigation results of the influence of the forming angle in cross wedge rolling on different parameters at multi-directional forging. First the state of research, the process development and tool design of cross wedge rolling and multidirectional forging are described. Then the parameter study will be presented and the influence of the forming angle ? on flash generation, billet temperatures, forming degree, forming forces and effective strain are shown. Generally, flash generates because a rotation-symmetric billet is forced into an asymmetric movement. The influence of a rising forming angle leads to a higher amount of flash at the bottom of the crankwebs.
multi-directional forging, cross wedge rolling, crankshaft, parameter study, forming angle
In complaint management, 8D reports are used to document the analysis and elimination of errors. However, the quality of these reports is often insufficient and leads to longer processing times and the repetition of errors. The newly developed evaluation system QuSys enables an automated check of 8D reports.
complaints, quality, evaluation system, errors, 8D reports
Assembling large-scale products involves frequent process interruptions why in order to reduce the impact of interruptions, a short-term response is necessary to reduce delivery delays and idle times of resources. An approach to challenge this represents the flexibility of a production system. Regarding the environment of large-scale product assembly, it has to be shown which potentials of flexibility are able to be used in a short-term manner.
assembly, production management, disruption management
To reduce production costs of forged parts, different approaches are possible. Especially for valuable materials like titanium, material costs represent a large part of the production costs. Therefore, reducing the initial material can decrease the total costs significantly. In order to identify the potential for improvements, an existing forging sequence was investigated.
For a titanium hip implant, a new forging sequence was developed. To reduce the initially needed material, cross wedge rolling as a preforming operation and die forging with flash brakes was investigated. The influence of the different stages on the final result was analysed and presented in detail. To increase the prediction accuracy of the newly developed flash-reduced forging sequence and to decrease iteration loops of die designs, feasible simulation parameters considering the boundary conditions of the forging environment were investigated. This is done using Finite Element Analysis (FEA), considering form filling, process stability, die stress and press forces. Using cross wedge rolling and die forging with flash brakes, the newly developed forging sequence reduces the flash rate significantly from 69 % to 32 %.
cross wedge rolling,forging, flash-reduced, finite element simulations, flash brakes