Common ball screw installation methods are divided into the following parts
1, one end fixed and one end free
One end of the ball screw is fixed and the other end is free to be installed. The fixed end bearing needs to bear axial force and radial force at the same time. This support mode is suitable for short screw with small stroke or fully closed loop machine tools. Because the mechanical positioning accuracy of this structure is not reliable, especially compared with the lead screw with large length and diameter, its thermal deformation is very obvious. It is normal for the lead screw with length of 1.5m to change 0.05-0.10mm in different cold and hot environments. But because this structure is simple, for installation and debugging, more convenient, so there are still many high-precision machine tools to use this structure, it is necessary to pay attention to the need to install grating, the use of full closed-loop feedback.
2. One end is fixed and one end is supported
One end of the ball screw is fixed and the other end is supported. The fixed end is subjected to both axial and radial forces. The supporting end only bears radial force, and can make a small amount of axial float, which can reduce or avoid the bending caused by the weight of the lead screw to a certain extent. At the same time, the thermal deformation of the lead screw can extend freely to one end. This way should be the most widely used, the current domestic small and medium-sized CNC machine tools, vertical machining centers and other basic use of this structure.
3, fixed at both ends
Both ends of the lead screw are fixed. The fixed end bearings can bear axial force at the same time. This kind of support can exert appropriate preload on the lead screw to a certain extent, improve the stiffness of the lead screw support, and partially compensate the thermal deformation of the lead screw.
For large machine tools, heavy machine tools and high precision boring and milling machines are usually also used in this way. However, this adjustment of the lead screw is relatively frequent. If the preload on both ends is too large, the lead screw will end up with a longer travel than the design and a larger pitch than the preset. If the pretightening force of the locking bar at both ends of the lead screw is insufficient, the use effect may be relatively strong and unsatisfactory, which is easy to cause vibration of the machine tool and reduce the accuracy. Therefore, this kind of screw must be adjusted in accordance with the original manufacturer's instructions when loading and unloading, or with the help of instruments and equipment, do not handle without authorization.