Ball Screw Do Not Know How To Install
As a high-precision functional component, the ball screw has certain requirements for its installation accuracy, otherwise it will affect its working performance and reduce its service life. Today, Bian Xiao brings you three basic installation methods.
One end is fixed and one end is free.
One end is fixed, the other end is free to install. The bearing at the fixed end can bear both axial force and radial force, while the ball screw bearing is mainly used for the short screw bearing with small stroke or the fully enclosed machine tool, because the mechanical positioning of this structure is the most unreliable precision. , Especially the screw bearing with a relatively large length and diameter (the ball screw is relatively thin), the thermal deformation is very obvious. But if it is a 1.5-meter-long lead screw, it is normal to change 0.05~0.1mm in different hot and cold environments. However, due to its simple structure and easy installation and debugging, most high-precision machine tools still use this structure. But there is one thing that needs special attention. When adopting this structure, the grating must be installed, and the feedback of the fully closed loop must be used to fully improve the performance of the lead screw.
Second, one end is fixed and the other end is supported.
One end is fixed and the other end is supported. The fixed end bears both axial force and radial force, while the support end only bears radial force, which can do a small amount of axial floating to reduce or avoid the bending caused by the weight of the lead screw. In addition, the thermal deformation of the lead screw can freely extend to one end. Therefore, this is the most widely used structure. For example, this structure is used in small and medium CNC lathes and vertical machining centers in China.
Third, the two ends are fixed.
Both ends of the screw are fixed. In this way, the fixed end bearing can bear the axial force at the same time, apply an appropriate pre-tightening force to the screw rod, improve the support rigidity of the screw rod, and partially compensate the thermal deformation of the screw rod. Therefore, large-scale machine tools, heavy-duty machine tools, and high-precision boring and milling machines mostly use this structure. Of course, there is also a disadvantage, that is, the use of this structure will make the adjustment work more cumbersome; in addition, if the preload at both ends is too large during installation and adjustment, the final stroke of the screw will be longer than the design stroke, and the pitch will be larger than the design pitch; if Insufficient pre-tightening force of the nuts at both ends will lead to the opposite result, which will easily cause the machine tool to vibrate and reduce the accuracy. Therefore, if the fixed structure at both ends is used, it must be adjusted in strict accordance with the instructions during disassembly and assembly, or adjusted with the aid of an instrument (dual-frequency laser interferometer) to avoid unnecessary losses.