In the vertical lathe equipment, the rotary table is one of the core structures that reflect the overall functions of the machine tool and realize the machining accuracy of the workpiece. We require it to work at high speed and accept heavier workpieces, have precise running accuracy and very high anti-overturning moment ability, and the slewing bearing supporting the table is important to complete this important task. In the past, most of the domestic workbenches used thrust bearings and radial bearings in cooperation. This arrangement has a messy structure and uses more materials. Especially when large box parts are placed, the entire machine tool has a larger space. It is also difficult to install and adjust the pre-tightening of the slewing bearing, and it is increasingly difficult to ensure the alignment, and it is difficult to improve the overall accuracy of the workbench.
Therefore, more designs are beginning to choose interspersed roller bearings with a more compact structure, which not only saves data costs, but also simplifies the design scheme, higher limit speed, better running accuracy and stability, and stronger load-bearing ability and rigidity. This article introduces how to use interspersed roller bearings on a vertical lathe to achieve its perfect engineering function.
1. Runout accuracy
Bearing run-out can be divided into synchronous run-out and asynchronous run-out, during which the influence of synchronous run-out on the overall run-out of the worktable can be reduced to the greatest extent by grinding the work surface, but the impact of asynchronous run-out cannot be eliminated in this link. Mainly determined by the roller outer diameter tolerance and roundness. Therefore, the better the asynchronous runout control of the bearing, the smaller the final radial and axial runout of the worktable, that is, the higher the working accuracy. When selecting bearing brands and accuracy grades, it is recommended not only to pay attention to the bearing installation runout, but to deepen the understanding of the accuracy standards that affect the asynchronous runout of the bearing.
2. Bearing cooperation
When selecting bearings, it is recommended that the inner ring and the shaft, and the outer ring and the gear ring be in close cooperation. The outer ring is made of rolling parts, and the tight fitting amount should be slightly larger. The inner ring will be pressed down by the end cap and adjusted to a certain pre-tightening amount, so the tight fitting amount should be slightly smaller. However, if the inner ring is considered to be a stationary part, and the inner ring and the shaft are designed to be loose, there is a radial gap between the inner ring and the shaft, it is possible that the inner ring may deviate when the inner ring is installed, the inner ring is locked, or the shaft is loaded. Oblique, that is, migraine occurs. This kind of misalignment will cause stress concentration in the gap between the contact area of the roller and the raceway, causing serious scratches, cratering and peeling, and ending the life of the bearing earlier.
