Metody predikce životnosti v konstrukci tvářecích nástrojů

Abstract

The dissertation thesis addresses the prediction possibilities of tool life. The beginning of the thesis surveys the current situation of the issues; there are various approaches to investigate the tool life. In this document, the author focuses on the comparison of the numerical model with the real forming operation. Since the issue of the durability in forming operations is very wide, the author focused only on the basic forming technology, i.e. cold forming. The experiment, which was compared to the real operation, was upsetting. While drawing the experiment up, was used experimental press the ZD 40 with numerical driving and collecting dates. The press allows the performance of both tensile and compression tests. The experiment in the actual operations would be very expensive due to the fact that it is time-consuming. The experiment was performed for two types of tool materials and two types of formed materials. Through the appropriate combination of all materials, two sets of tools and formed materials were made; they were subject to testing. One test set comprised two plates (tools) and several blocks (samples). The blocks were cold pressed, using the press connected to a PC. After pressing of 10 samples, the tools changes were measured in exposed place. The measurement was carried out using a MAHR length gauge. The obtained data needed to be corrected (two approach options are presented). Decreases in the surface - wear and tear - arose from the corrected data. The following premise of the wear and tear was adopted based on the intersection of the measured data and the data from the numerical model. As a by-product of the thesis, the temperatures reached during the forming operation were compared and confronted with the numerical model. The temperatures were measured, using a contactless method with a thermal camera. The differences between the numerical models (various versions of the computing software) and the actual processes were explained. In the experiment, the tools were also measured, using the instrument for magnetic field intensity measurement. This, however, is not the actual goal of the thesis. The device, however, is able to detect defects under the surface; thus there is no need for the technologies, such as x-ray or ultrasound, to detect various anomalies. The conditions of the tools can be deduced from the results of this measurement.