XL CATALOG

Also, for taking the most of the features, in Loading ball screws it is essential to take into account the deformations of the shaft and the nut, since, being the forces high, these deformations are not negligible. The following diagram shows how the nut and the shaft axis are deformed according to the position of the flange with respect to the support and according to the direction of application of the load. Load distribution in Loading ball screws Flange opposite to support: · When the flange of the nut is positioned at the opposite end to the support where the bearing package is, the shaft and nut are subjected to the SAME type of load: - Shaft is in compression and Nut is in compression, if the external load is directed towards the support. - Shaft is in traction and nut is in traction, if the external load is directed towards the free end. As both nut and shaft deform in the same direction, the load distribution between the balls is quite uniform, although if there are many circuits, it is advisable to take into account the magnitude of these deformations to calculate as accurately as possible the actual load that the different balls bear. Flange next to support: · When the flange of the nut is positioned in the nut side next to the support where the bearing package is, the shaft and nut are subjected to DIFFERENT type of load: - Shaft is in compression and Nut is in traction, if the external load is directed towards the support. - Shaft is in traction and nut is in compression, if the external load is directed towards the free end. The deformation of both elements is in the opposite direction, so the distribution of the external load between the balls is not uniform. In extreme cases with many circuits and very long nuts, the balls in the first circuit can support a much higher load than the balls in the last circuit. The ideal would be to change the position of the flange where the nut is tied to the machine, and put it towards the free end. If it is not possible to change the position of the flange, it is necessary to oversize the nut or take into account the actual load of the balls that bear the greatest load. Another option is to act on the geometry of the nut to improve the load distribution. Therefore, the recommendation for the position of the flange in Loading ball screws to guarantee uniform load distribution, is always to try to ensure that the clamping flange of the nut to the table is facing the free end, on the opposite side to the support where the bearings that support the load are located. Flange opposite to support - Recommended Flange next to support - Not recommended Compression Traction F F F F F F F F 14