|dc.description.abstract||Cross roller bearings are widely used in high-precision and high-load drives. However, due to the cross-arrangement of the rollers of bearings. The load distribution of rollers is complicated because of the interaction of different loads. Therefore, the purpose of this paper is to establish a cross roller bearing analysis model to analyze the distributed load and contact stress of each roller in the bearing. At first, use constant contact stiffness method to solve the load distribution of the bearings under the integrated load with the displacement relationship between the outer ring and the rollers. In order to obtain the contact stress distribution of loaded roller, the loaded contact analysis model is established by the influence coefficient method by using the geometric characteristics of the cross roller bearing, and the constant contact stiffness method is used for predicting contact roller in order to speed up the calculation process. In addition to the roller load distribution, the model can also obtain the contact stress distribution of different roller crowning profiles. And the contact stress distribution of rollers and raceways under different loads.
In this paper, two cases of large-sized slewing gear bearings and small-sized general cross roller bearings are analyzed. To understand the contact characteristics of bearing rollers under load. In the analysis, three crowning profiles such as non-crowning, circular, and logarithmic crowning are considered, as well as the effects of roller contact length, error of roller diameter, and error of roller position.
The result of load distribution analysis of each roller shows when the outer ring of cross roller bearings is subjected to the axial load, only the rollers in the same axial direction are subjected to the load due to the adjacent roller axes are staggered; when subjected to the radial load in the positive x direction, all the rollers between second and third quadrants are subjected to loads; when subjected to the overturning moment, all the rollers of the same axial direction in each side of the torque shaft are subjected to loads. Rollers that do not bear the load have gaps with the raceway due to the displacement of the outer ring. Therefore, under the integrated load, the rollers of the same axis have their respective load distribution curves, and the roller of one axial direction in a partial area may not be overloaded.
The result of stress distribution analysis shows that stress concentration occurs at the contact edge of the non-crowning roller, and under the circular and logarithmic crowning, the stress concentration of the roller can be improved, so that the stress is more evenly distributed on the contact surface. When the ratio of the contact length to the radius of bearing is large, the contact length has a significant influence on the load, and the influence is more significant when the overturning moment is applied. The error of roller diameter is roughly the same for the trend of roller load distribution, but there is irregular runout due to the difference in roller diameter. The error of roller position caused by different thickness holders only result in the load distribution curve to move.
This paper also establishes the limit diagram of the bearing capacity of the slewing gear bearing. Through the relationship between the axial and radial load, the corresponding axial and radial loads meeting the safety factor can be quickly selected.
From the analysis results, the analysis method developed in this paper can quickly and accurately analyze the load distribution trend of the cross roller bearing and the distribution of the contact stress between different geometric shapes of the rollers and the raceway.