The screw support seat (also called the screw support seat or bearing seat) plays a vital role in CNC lathes. It is one of the core supporting components of the ball screw transmission system. Its main functions can be summarized as follows:
1.Precisely support and position the ball screw:
Precision bearings (usually angular contact ball bearings or tapered roller bearings) are installed inside the support seat, which accurately support both ends of the ball screw (fixed end and support end).
It ensures the parallelism of the screw’s rotation axis with the machine tool guide rail and its own straightness, which is the basis for achieving high-precision positioning.
2.Bearing axial load:
During the processing of CNC lathes, the screw needs to withstand the huge axial thrust (cutting force, acceleration/deceleration inertia force) generated when the worktable (tool holder or tailstock) moves.
The bearing group in the fixed end support seat (usually angular contact ball bearings installed in pairs) is specially designed to withstand these bidirectional axial loads and transmit them to the machine bed structure to prevent the screw from axial movement.
3.Bear radial loads and bending moments:
In addition to axial forces, the screw may also be subjected to certain radial loads (such as force caused by component gravity and assembly errors) and bending moments.
The bearings in the support seat (especially the support end usually uses deep groove ball bearings or cylindrical roller bearings) can withstand these radial forces and bending moments to maintain the stable rotation of the screw.
4.Constrain the thermal expansion of the screw:
The screw will generate heat during high-speed rotation and friction, causing the screw to expand and elongate due to thermal expansion.
The fixed-end support seat (usually with a pre-stretched structure) will rigidly constrain the axial movement of the screw at this end. The support end (free end) is designed to allow the screw to expand freely in the axial direction (usually using deep groove ball bearings or cylindrical roller bearings, which allow the inner ring to move axially relative to the outer ring). This design avoids bending deformation or internal stress of the screw due to thermal expansion, ensuring accuracy and screw life.
5.Improve system rigidity:
The combination of a sturdy support seat structure and high-rigidity precision bearings significantly improves the axial rigidity of the entire ball screw transmission system. High rigidity means less deformation when under load, which is important for:
Resisting deformation caused by cutting force: Ensuring machining accuracy, especially during heavy cutting.
Improving dynamic response: Allowing the worktable to accelerate, decelerate and accurately position faster, reducing following errors.
Suppressing vibration: Reducing system vibration and improving machining surface quality.
6.Ensuring smoothness and precision of movement:
By accurately supporting the lead screw, bearing loads, constraining thermal deformation and improving system rigidity, the support seat fundamentally ensures the smoothness of the lead screw rotation and reduces unnecessary vibration and jumping.
This is one of the key factors in achieving high repeatability positioning accuracy, high contour following accuracy and good surface machining quality of CNC lathes.
7.Protecting lead screws and bearings:
The support seat usually has a sealing structure (such as oil seals, labyrinth seals) to prevent contaminants such as cutting fluid, chips and dust from entering the bearing, extending the service life of precision bearings and lead screws.
8.In summary, the significance of the lead screw support seat for CNC lathes is:
It is the physical basis for the stable and precise operation of the ball screw.
It directly determines the axial stiffness, load-bearing capacity and thermal deformation control ability of the screw system.
It ultimately affects the core performance indicators of the CNC lathe: positioning accuracy, repeated positioning accuracy, dynamic response speed, processing stability and surface quality.
It can be said that without a reasonably designed, well-made and accurately installed screw support seat, the CNC lathe cannot achieve its high-precision and high-efficiency processing capabilities. It is an indispensable core component in the precision transmission system.