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Cold forging of toothed components by extrusion is associated with high punching forces and tool loads, which requires the use of expensive and high-strength tool steels. High process forces result into a substantial tool deflection, which significantly reduces the precision of the toothed components. Thus, the development of alternative processes in order to reduce acting process forces in cold forging is of high interest. A potential process enhancement approach is to use a preform operation where the resulting preform can be formed partwise either in the same or in a subsequent die. Preforms allow to systematically control the material flow in subsequent forming operations. For this reason, the Institute for Metal Forming Technology in Stuttgart has developed a new cold extrusion process for manufacturing toothed components based on the conventional Samanta process. The newly developed die design of the Guided Material Flow-Samanta (GMF-Samanta) process enables efficient cold forging of gears. By means of numerical simulations and forging experiments it was successfully demonstrated that the new Guided Material Flow-Samanta process results into a significant reduction of punch force and normal pressure while simultaneously improving the die filling. Kaltfließpressen verzahnter Komponenten in einem modifizierten Samanta-Verfahren Konferenzbericht Zusammenfassung Das Kaltfließpressen verzahnter Komponenten ist mit hohen Stempelkräften und Werkzeugbelastungen verbunden, wodurch der Einsatz kostenintensiver und hochfester Werkzeugstähle erforderlich ist. Hohe Prozesskräfte führen zudem zu einer erheblichen elastischen Werkzeugdeformationen, welche die Form-und Maßgenauiugkeit der verzahnten Komponenten signifikant vermindert. Daher ist die Entwicklung alternativer Verfahren zur Reduktion der wirkenden Prozesskräfte in der Kaltmassivumformung von hohem Interesse. Ein möglicher Ansatz zur Prozessverbesserung ist die Anwendung einer Vorformoperation, bei der die resultierende Vorform am Werkstück entweder im gleichen oder in einem nachfolgenden Werkzeug weiter umgeformt werden kann. Vorformen ermöglichen es, den Materialfluss in der nachfolgenden Umformoperationen systematisch zu steuern und damit eine gezielte Reduktion der Reibfläche zwischen Werkstück und Werkzeug herbeizuführen. Aus diesem Grund hat das Institut für Umformtechnik in Stuttgart ein neues Kaltfließpressverfahren zur Herstellung von verzahnten Bauteilen entwickelt, das auf dem konventionellen Samanta-Prozess basiert. Die neuartige Fließpressmatrize des Guided Material Flow-Samanta (GMF-Samanta)-Verfahrens ermöglicht ein effizientes Kaltfließpressen von Verzahnungen. Mittels numerischer Simulationen und experimentellen Umformversuchen konnte erfolgreich nachgewiesen werden, dass das neue Guided Material Flow-Samanta-Verfahren zu einer signifikanten Reduktion der Stempelkraft und der Kontaktspannungen im Werkzeug bei gleichzeitiger Verbesserung der Formfüllung führt.

Cold forging tools become increasingly complex and require enhanced functionality, especially in the context of digitisation. Conventional subtractive manufacturing processes often reach their limits when the geometric complexity of the workpiece increases, hence additive manufacturing processes have become increasingly important in the last decades. Additive manufacturing processes have already been used in many fields of manufacturing technology to produce tool components with promising results, but the potentials of additive manufacturing processes have not yet been applied to cold forging tools. Therefore, the Institute for Metal Forming Technology (IFU) of the University of Stuttgart has developed an additive manufactured cold extrusion tool with integrated functional features. As functional features in the additive manufactured extrusion tool, a close contour glass fiber sensor for temperature measurement, a cooling system and a lubrication system for the controlled injection of minimal lubricant amounts during the forming process were integrated. Due to the integrated functional features, structural degradation appears in the tool, therefore the structural-mechanical tool properties were analyzed numerically with the FE-Software DEFORM 3D™ in this report as well. Furthermore, the additive manufactured cold extrusion tool was experimentally evaluated in sequentially executed extrusion operations. Thereby the integrated functional features were used and gathered data were recorded. As a result of the experimental forming tests, near-contour temperature measurements in the extrusion tool with and without the use of the integrated cooling system as well as the modification of the maximum punch forces by an inline lubricant application were obtained. In addition, the experimentally determined temperature fields in the extrusion die are validated with numerically calculated results.

Die Presskraft ist in Umformprozessen eine zentrale Messgröße für die Prozessüberwachung und wird meist durch Federkörper im Krafthauptschluss oberhalb des Stempels oder unterhalb der Matrize erfasst. Als Alternative dazu wird in diesem Beitrag der Einsatz von Kraftmessschrauben (PiezoBolts) zur Dehnungsmessung im Armierungsring bei einem beispielhaften Kaltmassivumformverfahren untersucht. Es werden zwei Einbausituationen der Kraftmessschraube experimentell und simulativ betrachtet sowie die ermittelten zeitlichen Dehnungsverläufe gegenübergestellt.   Forming load is one of the most decisive parameters in metal forming and is usually measured by using strain gauges, applied on pressure plates located in the main load path above the punch or beneath the die. An alternative investigated here is to apply load measuring bolts (PiezoBolts) for strain measurement in the die compression ring of an exemplary cold forging process. This paper investigates two different mounting positions fpr the PiezoBolt and compares strain profiles gained from experiment and simulation.

This paper describes the tribological investigation of the cold forming and ejection process during ironing of hollow components with helical internal geometry. The experimental tests on a test tool are intended to evaluate the tribological system by varying the surface pretreatment of the blanks and the lubricant. For the evaluation of the tribological effects the ironing and ejection force are measured. In addition, the die filling as well as the surface quality of the pressed parts are determined, allowing the correlation of the test results with the tribological conditions. Furthermore, a numerical investigation of the process was performed. The numerical results are presented and compared with the experimental results.