This phase is generally characterized with severe wear on the worm wheel, leading to an adjustment of the micro and macro geometry of the tooth flank. As a result, the tribological system of the tooth contact in worm gears is subjected to changes, in particularly within the first phase of the gear’s lifetime (running-in). In case of the commonly used combination of a bronze wheel with a steel worm, friction is accompanied by wear on the worm wheel when an insufficient lubricant film leads to solid body contact. Due to substantial sliding in tooth contact, friction losses are an issue in worm gears. They offer a high load capacity, smooth operation, as well as high-gear ratios in a single stage. Worm gears are transmission elements used in various applications for power transmission or precision gears. Both aspects are considered for a verification of the wear calculation. Wear is on one hand a directly measured value, and on the other hand, it changes the geometry of the tooth flank and influences and thereby the unloaded kinematics of the gears. The tooth friction is reflected by the measured efficiency of the gearbox on the test bench. However, for measurement reasons, a comparison takes place on the macro scale. Since various values are determined in the simulation model, the comparison covers different aspects to verify the model. The simulative results are compared with experimental wear studies on the running-in of worm gears. The included wear model associates abrasive wear with solid friction energy occurring in the tooth contact and allows a time-dependent simulation by considering the wear-modified tooth flank in the tribological calculation. With a simplified model of the EHL-tooth contact, boundary as well as fluid friction are calculated locally, and the tooth efficiency is evaluated. For the investigation of the continuous change of friction in the tooth contact during that process, a tribological simulation program is used. Wear on the worm wheel with a softer material during the running-in process increases the contact pattern and thereby the load capacity. Worm wheels are often manufactured by using an oversized hob, which results in a relatively small initial contact pattern. T he load capacity of worm gears strongly depends on the size of the contact pattern.
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