Richter, J.; Stonis, M.; Langner, J.; Blohm, T.; Behrens, B.-A.: Development of a predictive simulation method for thin flash generation in flashless precision forging processes of aluminum parts using FEA and experiments. In: Production Engineering, Springer Berlin Heidelberg, 12. Jg. (2018), H. 3-4, S. 419-429, DOI: 10.1007/s11740-018-0803-6.
In this paper, the investigation of thin flash generation in precision forging process of an aluminum long flat part is described. The aim was to derive a predictive simulation method for thin flash generation in order to increase both process and part quality in the future. The forging processes were varied by use of different preforms with equal volumes but different mass distributions while using the same final part geometry. The experimentally forged parts were analyzed concerning the amount and part area of the generated thin flash. The conducted FE simulations were analyzed concerning the hydrostatic pressure values p in the part areas near to the tool gap between upper and lower die immediately before form-filling. For a more detailed comparison, single p values were included to hydrostatic pressure functions P. The comparison between the P functions and the experimentally determined thin flash height shows, that high pressure values as well as high gradients of the P functions indicate less thin flash generation. The method therefore allows a qualitative prediction of thin flash generation. It can provide two kind of information. First: The prediction of the specific locations where thin flash is likely to occur in one final part by use of one single preform. Second: The qualitative prediction of the specific final part areas were thin flash is likely to occur depending on different preform geometries. This method will decreases the necessity of time-consuming forging trials and can shorten the preform designing process in the future.
forging flashless precision forging FEA aluminum predictive simulation method
Rising and increasingly volatile energy prices resulting from increased power feeds from renewable sources such as solar and wind energy are confronting manufacturers with new challenges. If these companies procure their power supplies at ?uctuating short-term prices from electricity exchanges or through energy purchasing pools, they can in?uence the result-ing energy costs through production control via its actuating variables while energy consumption remains constant. A form of sequencing that decides at short notice which order will be processed next shows particularly high potential. The energy price-oriented sequencing rule that is introduced in this article prioritises orders with a high energy requirement at times when energy prices are low and gives precedence to orders that require less energy at times when energy prices are high, without neglecting the scheduled completion deadline. However, this sequencing rule can only be applied e?ectively under certain preconditions. These are elaborated in this article by means of a simulation study that will con?rm the way the rule functions.
production planning and control, manufacturing control, sequencing, energy costs
In the forging industry, like in many other economic sectors, it is common to simulate forming processes before executing experimental trials. An iterative simulation process is more economic than trials only but still takes a lot of time. A simulation with realistic parameters takes many hours. For an economical production the idea of predicting some main results of the simulation by Data mining was developed. Within this paper, the use of four different Data mining methods for the prediction of certain characteristics of a simulated flange forging process are presented. The methods artificial neural network, support vector machine, linear regression and polynomial regression are used to predict forming forces and the lack of volume. Both are important parameters for a successful simulation of a forging process. Regarding both, forging forming forces and lack of volume after the simulation, it is revealed that an artificial neural network is the most suitable.
data mining, artificial neural network, linear and polynomial regression, support vector machine
Interactive assistance systems such as data glasses or headsets as a new human-machine interface enable an increase in process quality and speed through networking within the factory. However, small and medium-sized enterprises (SMEs) are critical to the implementation of these systems. Therefore, this article describes the development of a maturity model for a systematic ability analysis and increase to the implementation of interactive assistance.
industry 4.0, interactive assistance systems, maturity models, implementation support
Blohm, T. ; Nothdurft, S.; Mildebrath, M.; Ohrdes, H.; Richter, J.; Stonis, M.; Langner, J.; Springer, A.; Kaierle, S.; Hassel, T.; Wallaschek, J.; Overmeyer, L.; Behrens, B.-A.: Investigation of the joining zone of laser welded and cross wedge rolled hybrid parts. In: International Journal of Material Forming, Springer-Verlag France (2017), DOI: 10.1007/s12289-017-1393-0
This paper describes the production process of serially arranged hybrid steel parts, produced by combining a laser welding process with a subsequent cross wedge rolling process. The presented results are only a first approach in order to get first insights in the forming behaviour of laser welded and cross wedge rolled parts. The investigated material combination is C22 (1.0402) and 20MnCr5 (1.7147). This innovative process chain enables the production of hybrid parts. To evaluate the developed process chain, the weld and the joining zone is analysed before and after cross wedge rolling. Main results are that the joining process using laser welding enables a strong bonding between the two materials with a higher hardness in the joining zone than for the individual materials. After the forming process, the bonding of the joining zone is still present, while the hardness decreased but remains higher than of the materials themselves.
tailored forming, laser welding, hybrid parts, cross wedge rolling
The storage planning is an important component of the factory planning and describes an improvement potential in the times of an increasing global competition. The selection of a suitable storage, commissioning and transport system is a big challenge especially for small and medium-sized enterprises. In a research project of IPH – Institut für Integrierte Produktion Hannover a method for companies will be created to determine the necessary level of versatility and automation to choose an optimal system. This article introduces the research project and explains the approach and first results.
storage planning, sct systems, versatility, automation, software demonstrator
Energy requirements of belt conveyor systems are essentially determined by the necessary drive power, which is composed of the main drive and intermediate drives. The use of driven support rollers reduces the load on the conventional drive at the head of conveyor systems. Thus, the drive can be build smaller, which can lead to energy and cost savings. In contrast to conventional head drives, driven rollers enable the implementation of modular conveyor systems. The theoretical possibilities and consequences of driven rollers are promising. Due to a lack of knowledge regarding the economic efficiency and behavior under certain conditions, driven rollers have not yet been integrated into real operation. In order to investigate the behavior of driven rollers and to ensure the introduction into practice, test stands are indispensable. This paper presents the concept of driven rollers and, on this basis, the development of a test stand for investigating these rollers.
driven roller, test rig, belt conveyor, energy efficiency
To forge a flashless crankshaft within few steps and with low energy consumption innovative forging processes are necessary, such as cross wedge rolling and multi-directional forging. The direct combination of the two forming processes normally leads to flash at the bottom of the crankweb preform after the multi-directional forging. The reason for the flash generation is the rotation-symmetric cross wedge rolled billet, which is formed laterally to the main axis during multi-directional forging. In this paper, a parameter field in which flashless crankshaft preforms can be forged is presented. The parameters varied within the experimental research are the forming angle and the cross section area reduction at cross wedge rolling as well as the axis offset, the billet temperature and the forming velocity at the multi-directional forging. The limits of this flashless parameter field are shown in several diagrams. For a flashless combination of two forming process low values for all parameters such as a forming angle of 30°, a cross section area reduction of 30 %, and a billet temperature of 1050 °C are recommended. Furthermore, the intensity of the influence of the significant parameters are shown. The cross section area reduction thereby caused the highest range at flash generation with 0.4 mm.
multi-directional forging, cross wedge rolling, crankshaft, parameter study, flashless
Mohammadifard, S.; Langner, J.; Stonis, M.; Semrau, H.; Sauke, S.-O.; Larki Harchegani, H.; Behrens, B.-A.: Monitoring of an Aluminum Melting Furnace by Means of a 3D Light-Field Camera. In: 2017 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM), (2017), p. P-0104.
The melting process in an aluminum melting furnace cannot be monitored by contact sensors, since the furnace is not accessible due to the high temperatures (more than 700 °C). Therefore, monitoring the melting process by means of optical sensors is investigated for the first time in this research project. This article deals with an innovative optical measuring system that is able to monitor the melting bridge despite the red-hot furnace walls. For this purpose, a light-field camera is installed on top an aluminum melting furnace in order to monitor the process and to control a targeted heat input into the melting furnace using a rotatable burner. The light-field camera used can capture a 3D point cloud with only one image. To achieve this, a separate field of lenses is placed between the image sensor and the main lens, projecting a virtual intermediate image onto the actual image sensor for further data processing. In addition, a self-developed image analysis program serves to monitor the height variation of the aluminum block and any melting rest on the melting bridge of the furnace.
Thus, the energy efficiency of the aluminum melting process could be increased by 15 % and the melting time reduced by almost 20 minutes by means of online monitoring.
light-field camera, process monitoring, image processing, melting process, energy efficiency
One aim of the research project "Networked cognitive production Systems (netkoPs)" was the development of the formal language Production Modeling Language (PML). The PML is to be understood as a digital twin of the product and the production system. At the beginning, useful potentials for PML from the current state of research as well as the aims of the research project netkoPs were derived. Afterwards, based on a requirement analysis, the required data fields for the PML were classified. In a next step, the PML, based on the AutomationML, was implemented. The potential benefits formulated in the context of netkoPs could finally be demonstrated in connection with the further research results. For example, a preliminary ProductPML can equipping the machine before the product arrives.
digital twin, ProductionML, decentralized control, material flow
Lot sizing is an important task of production planning and control: basis of lot sizes are order change costs and costs for storage. Models for lot sizing do not consider lot size dependent maintenance costs. However, for a forging company the tool wear is very important, because the tooling costs represent a major part in the production cost. In this article, the deter-ministic lot size model of Andler is extended with lot size dependent maintenance costs. For this purpose, the correlation between lot size and the tool wear is ?rst derived in order to develop a lot size dependent wear function. The linking of a lot size dependent wear function with maintenance costs results in a lot size dependent maintenance cost function, which can be integrated into existing lot size models with a customized total cost function. The validation of the extended lot size model consists of two parts. In the ?rst part, the functionality of the extended lot size model is validated. In the second part, a sensitivity analysis of the lot size is carried out with regard to lot size dependent costs and unit costs.
lot sizing, tool wear, forging industry, sensitivity analysis
Awkward bending, lifting heavy items, working overhead: Such movements may cause permanent health problems. As a preventive measure, researchers of IPH and IFA developed an ergonomics assessment tool for assembly workplaces: 3D cameras capture unhealthy movements automatically.
3D camera system, ergonomics assessment, assembly
In this paper, investigations about the displacement of the joining-zone of serially arranged semi-finished hybrid parts durig cross-wedge rolling are presented. The investigated material combinations are steel-steel (C22 and 41Cr4) and steel-aluminum (20MnCr5 and AlSi1MgMn). The rolling process is designed using FEM-simulations and the cross-wedge rolling process was experimentally investigated afterwards. Research priorities are investigations of the displacement of the joining-zone depending on the main parameters of cross wedge rolling. It could be shown that the forming behaviour of serially arranged hybrid parts made of steel-steel and steel-aluminum can be described using FEM. The deviation of the simulated displacement of the joining-zone compared to the trials is only about 3 %, which is a good approximation.
cross-wedge rolling, steel, aluminum, joining-zone
The investigation of thin flash generation in a precision forging process of an aluminum long part using finite elements analysis (FEA) and corresponding forging trials is described in the presentation. Thin flash generation leads to bad handling and positioning in subsequent process steps and therefore tolerance defects. For investigation purpose, the forging processes were varied by use of different preforms with equal volumes but different mass distributions, while the geometrical parameters of the final part were not varied.
The forging processes were analyzed by FEA with focus on the value of the form-filling simultaneity depending on the preform geometry. Afterwards, corresponding forging trials were carried out for validation.The results of the experiments and the FEA showed good agreement concerning the part areas were thin flash generation was predicted by FEA and actually occurred in experiments.Preforms with higher values of form-filling simultaneity showed less thin flash generation while preforms with lower values of form-filling simultaneity showed significantly increased thin flash generation.
forging, aluminum, FEA, thin flash generation, prediction
Manufacturing individual products at almost the prices of mass products – using 3D printers. The Lower Saxony Center for Additive Manufacturing offers small and medium-sized enterprises (SMEs) free-of-charge support for the introduction of the new technology.
3D printing, additive manufacturing, individual products
As a result of the increasing feed-in of renewable energies, the volatility of the electricity price rises. Considering this, manufacturers can save energy costs by applying an energy price-oriented sequencing rule. Since the application of this sequencing rule does not only have an impact on the energy costs, a potential analysis is presented in this article which, in addition to the energy costs, also considers the schedule compliance cost of production orders.
cost accounting, manufacturing control, production planning and control
In production, product-related error costs can be reduced by focusing on human production factors, such as considering human performance fluctuations during the day, when production planning with respect to job-shop scheduling. In this article, the flexible job-shop scheduling problem is extended by considering product-related error costs and logistic costs. Product-related error costs are increased by over stressing the operative workers. Logistic costs are based on work in process and throughput time. This cost-based definition enables a production plan to be simultaneously optimized in respect of both error and logistic costs. The product-related error costs and flexible job-shop scheduling problem are described mathematically and a memetic algorithm is also presented as an approach. Within the memetic algorithm, the evolutionary process is supplemented with a local search procedure to improve the ability of solutions and repair procedures to rectify infeasible solutions. The influence of product-related error costs on the total costs of a production plan within job-shop scheduling is presented.
flexible job shop scheduling, memetic algorithm, human perfor-mance fluctuation, error costs
An essential component of belt conveyor systems are the support idlers. Particularly in bulk material handling systems, which are used in demanding terrain with numerous gradients as well as under extreme environmental conditions in tropical and arctic regions, they are exposed to considerable stress. The steadily growing flow rates mean higher loads and speeds for the support idlers. This trend is countered by new drive concepts. For example, belt-driven conveyor systems with internally installed motors are used.
Within a research project, the IPH is developing a dual measuring system that can be used to test both conventional bearing rollers and driven bearing rollers.
driven idlers, test rig, efficiency of conveying systems
In respect to the expansion of renewable energies, temporary oversupplies of electrical energy cause a resulting price decline on the German electricity exchange. The electricity traded on the electricity exchange already shows high price volatility. For this reason, energy storage systems are needed that can balance energy supply and demand to ensure grid stability. The production industry can make a contribution by adjusting its consumption by shifting energy-intensive production steps to times of negative residual load.
energy cost, production planning, requirements, power
The measurement of torque via sensors as well as the generation of torque form the basis of many industrial sectors. Within a research project an optical and non-contact measurement method to detect the absolute rotation angle and torque was developed. For comparison with the current state of the art torque sensors a test stand was built and compared to a reference torque sensor. The results of this validation are presented in the present paper.
torque, rotation angle, optical, validation