„New inline measurement process“
Inline monitoring of stamping and bending processes
Within the framework of the “Efficient Production Technology” network (EffPro), the Kempten University of Applied Science and Otto Bihler Maschinenfabrik are developing a new optical measurement system for the inline monitoring of stamping and bending processes. This measures both the cut edges and the tool wear – without contact, online and in real time.
The aim of the “Efficient Production Technology” technology transfer center is to improve manufacturing processes, optimize production technologies and adapt relevant products to the demands of the marketplace. “Particular focus is being placed on competitive advantages, cost reductions, energy efficiency during production and minimizing resource consumption,” explains Project Manager Professor Dr.-Ing. Christian Donhauser from the Faculty of Mechanical Engineering at the Kempten University of Applied Science. One of the partner companies in the EffPro project is Otto Bihler Maschinenfabrik, which last year made a GRM-NC servo-controlled stamping and bending machine available to the University. “We greatly value our cooperation with the Kempten University of Applied Science and, as an experienced technology partner, are happy to support it,” stresses Bernd Haussmann, Member of the Managing Board at Otto Bihler Maschinenfabrik. “The University develops innovative, forward-looking solutions that can be put to practical use by industry.”
20 percent reduction in wear-related costs
Currently, as part of the EffPro project, the GRM-NC is being used to develop a new optical procedure for the inline measurement of the cut edges. The new solution permits the continuous online recording of the characteristic values of the cut edges of each part in real time. This is achieved by means of the so-called light-section method and involves a camera system, an illumination unit and a laser unit. The images are subjected to computer-assisted analysis in accordance with defined criteria and warning messages can be issued or the machine halted if, for example, the burr height tolerance is exceeded. This check ensures high parts quality, reduces the risk of faults and cuts down on unplanned machine stoppages. At the same time, it makes it possible to draw valuable conclusions about wear to the punches and dies. “In this way, the corresponding maintenance activities can be planned much more precisely and can also be postponed for much longer because the precise level of wear is known at all times,” says Haussmann. “Overall, a reduction in tool wear-related costs of 20 percent is perfectly realistic.”
Adaptation for series use
In cooperation with Bihler, the inline measurement procedure is currently being extended to develop a variant that can be used in industry. The development process will conclude with a standardized box that will be marketed as part of the Bihler portfolio. Bihler expects to present the inline measurement system, which is designed for use with punched and bended parts of all dimensions, for the first time at the 2020 sheet metal working trade fair. At the same time, the inline measurement procedure can also be extended to include other quality criteria. According to Professor Donhauser: “It is perfectly possible to conceive of sensors that continuously measure material properties such as tensile strength, monitor the results of the stamping process and also inspect the bending angle online. In combination with the GRM-NC, at which it is already possible to undertake corrective actions, this would open up a completely new dimension in manufacturing.” And this ultimate objective will also form part of the future cooperation between the Kempten University of Applied Science and Otto Bihler Maschinenfabrik.
It is possible to see with millimeter accuracy that the bended edge of a part appears differently depending on the position and the process parameters.