While merely solutions for integrated resistance welding have been known until now, a tool technology in a reliable process for the functional integration of initial contact capacitor discharge (CD) arc stud welding was developed in a research project. This technology is particularly well-suited to integration into sheet metal working tools, amongst other reasons, because of its high joining speed, low energy input and high process reliability. In endurance tests, this new technology can be used in order to manufacture high-quality stud welds with a high robustness to disturbing variables at the same time, not least due to the fact that the extraction of welding spatter was tried out for the first time.
sheet metal, capacitor discharge arc stud welding, cd arc stud welding, tip ignition, follow-on tool
To realise integration, a new modular tool concept was developed in a research project. However, negative process effects like weld splatters occur. As a counteraction the control of process parameters, an extraction system and mechanical solutions were developed. Focus of this research project was to demonstrate process stability and reachable numbers of strokes. Welding tests with a developed joining step within a progressive die showed good joining results and high process stability. Welded studs were examined by reverse bending experiments and achieved maximum values pointing to the sheet material were used. Disturbances were introduced reliably detected by process monitoring of the voltage and current curve progression as well as the bolt movement. The analysis of the measurements showed the robustness of the automated welding process. Welding emissions were efficiently removed by suction from the shielded welding area in the tool without compromising on joining qualities.
sheet metal, capacitor discharge arc stud welding, cd arc stud welding, tip ignition, follow-on tool
Warm forged parts have advantages in comparison to conventional hot forged parts: Closer tolerances, reduced surface roughness, no scale and reduced decarburization. However, the geometrical spectrum of warm forged parts is restricted by high flow stress. To overcome this geometrical limitation new rolling and forging processes are developed in the European research project "DeVaPro - Development of a Variable Warm Forging Process Chain". The focus is on the layout of a warm preforming operation by cross wedge rolling followed by an intermediate heating and warm final forming in conventional dies. To get an idea of the effect of lower temperatures on process parameters, e.g. force, die wear and microstructure as opposed to hot forging processes, FE-simulations and experimental tests with a model are performed. In this paper a new warm cross wedge rolling process is introduced and results of experimental tests e. g. mechanical characteristics and microstructure are shown.
warm forging, process chain, cross wedge rolling
Warm forged parts are distinguished by good surface properties and high dimensional accuracy. In comparison to hot forging the maindisadvantage is the high wear of the forging dies because of the higher mechanical load. Diamond-Like Carbon (DLC) coatings are anti-adhesive and extremely hard (up to 3500 HV) and are thus suitable as wear protection coatings. The suitability of these kind of coating is examined by simulation and experiments at the IPH – Institut für Integrierte Produktion Hannover gemeinnützige GmbH. For this purpose, a modular test rig was developed, which enables the detection of relevant process parameters, e.g. as the die temperature. The project aims at a reduction of die wear and a wa to demonstrate the wear process, depending on the process parameters.
DLC, coating, warm forging
The complaint processing in the customer-supplier relationship is costly and time consuming and often incorrect. At the Institute of Metal Forming and Metal Forming Machine Tool (IFUM) will together with the IPH - Institute of Integrated Production Hannover gGmbH developed a measurement and evaluation system to improve the quality and reduce costs in the processing of complaints involving the 8D method.
processing of complaints, method of valuation, cost reduction, 8d report
The processing of complaints involving the 8D method is sometimes very costly and time consuming and often error-prone. Against this background, an automated metric system for measuring and evaluating the quality of processing of an 8D report is presented in the article. On the one hand text mining algorithms are used to determine the metrics. On the other hand manual reviews are used to realize the required bandwidth at reviews efficiently and reliably. The metric system was implemented in software and is designed to enable companies in various industries to reduce the expense of an effective fault management significantly, to shorten response times in the event of a complaint and to benefit from a long-term avoidance of errors.
quality management, complaint management, 8d report, data mining, text mining
In comparison with the conventional forging with flash, precision forging helps to reduce the amount of raw material. Beyond this no additional step for flash removal is needed. In this paper the development of a three step process for a two cylinder crankshaft with flange and pin is described and afterwards compared to a four step process. It shows that the three step process lowers the number of faults saves time and forces. These advantages are due to the innovative tool concept which is shown in this paper.
cross wedge rolling, bi-directional forging, crankshaft forging without flash
Sheet metall parts with small dimensions and high quantities are usually manufactured very economically in a progressive forming process. If these parts require welded joining elements, these elements must be joined on separate welding stations. The handling of the separated components causes high costs. The integration of a thermal joining process simplifies the manufacturing of such components significantly. As part of an EFB research project a welding step including welding head and tool supply of the joining components to the tool integrated stud welding process was developed at the IPH. Emissions are removed from the welding area by means of suction while the tool is closed to protect the tool against contamination. To ensure the quality of welding process parameters current, voltage and distance are permanently monitored. Investigations of welding results from long-term tests with introduced disruptive effects showed a high process reliability and sustainability of compounds as well as a stable and reproducible process. Overall, it was shown that a thermal joining process safely integrate in sheet metal forming by stud welding and that potentially occurring disruptive effects are manageable.
sheet metal, capacitor discharge arc stud welding, cd arc stud welding, tip ignition, follow-on tool
This article presents research results concerning the wear behaviour of precision forging dies within the framework of the Collaborative Research Centre (CRC) 489 "Process chain for the manufacturing of precision forged high performance components". The wear behaviour is described in accordance to the wear curve of DIN 31051. Tests within the scope of this CRC have revealed two different kinds of measurable wear, material abrasion and material adhesion. Based on the wear curve of an examined precision forging tool the threshold level of damage is determined. The threshold level of damage complies with the maximal quantity of good parts which can be produced with the precision forging tool. An approach to identify an economic lot size for forging processes taking into account the maximal tool quantity was developed, in order to enable an integrated production planning and tool maintenance planning.
batch size determination, tool life quantity, abrasion behavior, forging industry
