What skills do you need to know about YRT turntable bearings?
In vertical lathe machines, the rotary table is one of the core elements which reflect the overall performance of the machine tool and realize the machining accuracy of the workpiece. We require it to run at high speed and bear a heavy load, at the same time, it has accurate running accuracy and very high anti overturning torque capacity, and the turntable bearing supporting the workbench is the key to complete this important role. Before, most domestic workbenches applied thrust bearing and radial bearing together. This kind of layout has a complex structure and a lot of materials. Especially when placing large box parts, the space volume of the whole machine tool is larger. It is also difficult to install and pre-tighten the YRT turntable bearings, to ensure alignment, and to improve the overall accuracy of the worktable.
Therefore, more and more designs begin to choose the more compact YRT turntable bearing, which not only saves the material cost, but also simplifies the design scheme, has higher limit speed, better operation accuracy, and stability, and has stronger bearing capacity and rigidity.
1、 Runout accuracy
YRT turntable bearing runout can be divided into synchronous runout and asynchronous runout. The impact of synchronous runout on the overall runout of the worktable can be greatly reduced by grinding the worktable, but the impact of asynchronous runout can not be eliminated in this link, which is mainly determined by the tolerance of roller outer diameter and roundness. Therefore, the better the asynchronous run-out control of the bearing, the smaller the final radial and axial run-out of the worktable, that is, the higher the running accuracy. When selecting the bearing brand and accuracy level, it is suggested not only to pay attention to the bearing assembly runout but also to have a deep understanding of the accuracy standards that affect the asynchronous runout of the bearing.
2、 Bearing fit
When selecting the bearing type of YRT turntable, it is recommended that the inner ring and the shaft, the outer ring and the ring gear are a tight fit. As the outer ring is a rotating part, the tightening amount should be slightly larger, and the inner ring will move down under the pressure of the end cover, so the tightening amount should be slightly smaller. However, if the inner ring is considered to be a static part and the inner ring and shaft are designed to have radial clearance between the loose fit inner ring and shaft, it is possible that the inner ring will be deflected when the inner ring is installed, locked or the bearing is loaded, that is to say, eccentricity occurs. This eccentricity will cause stress concentration on the boundary of the contact area between rollers and raceway, which will cause a serious scratch, indentation, and peeling, and shorten the YRT turntable bearing's service life.
3、 Geometrical tolerance
The installation surface of the shaft and ring gear shall have the same flatness, verticality, roundness and cylindricity as that of the precision bearing. Controlling these tolerances can not only obtain better assembly accuracy but also avoid the stress concentration caused by the excessive eccentricity of the inner and outer rings of the bearing and prolong the service life of the bearing. As for the machining standard of form and position tolerance, it is recommended to consult the bearing supplier to match the bearing accuracy.
4、 Axial preload
In the cutting test of the vertical lathe, the roughness of the end face and the outer circle of the workpiece is very concerned, and the rigidity of the system is one of the key factors that determine the quality of the workpiece. The rigidity of the system includes the rigidity of the frame structure, the rigidity of the bearings supporting the YRT turntable, etc. the rigidity of the bearings often depends on their axial preload.
Therefore, it is very important to consider the influence of temperature and load and set the axial preload of the YRT turntable bearing reasonably.
Please check the Product Guide to select suitable bearings for your machinery.
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