Stress Analysis and Shape Study of Keyways in Journals of Large Sized Backup Rolls

Abstract

Though a keyway in the journal of a large sized backup roll is an area where stress is usually concentrated, there are a few studies on strength of keyways.
In this paper the stress analysis in the corner of keyway bottom and the improvement of keyway shape for stress reduction were studied by the two-dimensional photoelastic method.
The main results obtained are as follows:
1) A repeated tensile and compressive stress work in the corner of keyway bottom. However, no stress enough to break the keyway occurs under the usual rolling load. When the high circumferential impact load is inflicted repeatedly, there is a probability of keyway breakage.
2) To improve the strength of the corner of keyway bottom, it is effective to apply a larger curvature radius to the corner. And from scope of this study it became clear that the corner radius of 15 mm min brought a satisfactory result.