Digitalisierung eines Rotationsschmiedetribometers und Durchführung von tribometrischen Untersuchungen zur Bestimmung von umformtechnisch relevanten Reibgrößen

Tribology is of great importance in forming technology as it influences many process parameters as well as the quality of the workpiece and the tool wear. To examine friction conditions in the contact zone between workpiece and tool under forging conditions more precisely, a specially designed rotational forging tribometer is present at the Chair of Metalforming at Montanuniversität Leoben. In experiments, an upper and lower tool are pressed against each other with a defined normal force and the lower tool is simultaneously rotated. The friction conditions can be determined by measuring the normal and resulting tangential force. In this thesis, the rotational forging tribometer was updated to current state of the art soft- and hardware, followed by pin-on-disc experiments and the setup of a digital model of the testing process. First of all, a new control program was developed and implemented using B&R Automation Studio 4.12. Subsequently, a new concept for data acquisition was devised and applied to the machine. For this purpose, an embedded PC from Beckhoff with suitable measurement terminals was used. The experiments simulated a knife forging process with the material pairing 1.4301 and W300. A total of 20 experiments were conducted at workpiece temperatures of 850, 900, 950 and 1000°C and a die temperature of 250°C, with friction velocities of 38 and 75mm/s. In parallel, a digital model of the experiment was set up as a FEM-simulation using Simufact. The results from the experiments and simulations were analyzed and compared. It was found that the contact surface between the specimens and the degree of deformation of the pins could be reproduced well by the simulation. However, the friction conditions in the effective joint could not be represented realistically, which is reflected in a clear underestimation of the torque required to rotate the lower tool.