Precision ground recirculating ball screws are mechanical elements used to convert rotary motion into translational or linear motion and vice versa. Their operating principle is based on a series of balls that roll between the grooves formed by the threaded shaft and the nut, thus converting motion using rolling friction. Rolling friction is considerably lower than the friction generated by conventional trapezoidal screws, where motion is inverted by the action of the screw and nut thread sliding against each other, consequently determining higher operating costs. Ground recirculating ball screws are extremely high efficiency components that are widely used in industrial and precision machinery requiring motion reversibility but also superior performance.
Ground recirculating ball screws are obtained from extremely precise grinding techniques. However, the distinguishing feature of B.B. brand products is their “Gothic Arch” profile, a particular rolling track profile designed to optimise contact pressure occurring between ball and screw tracks as well as axial load capacity.
This profile is made up of two symmetrical arches which have a bend radius that is larger than that of the balls themselves. These arches meet on the axis of symmetry, forming a point; the two arches are related to the ball radius in such a way as to produce an optimum contact angle. This solution definitively prevents ball slippage or wedging.
Another distinctive characteristic is the type of nut used for ground screws, which B.B. supplies in two versions: double preloaded nut and single preloaded nut.
THE ADVANTAGES OF GROUND RECIRCULATING BALL SCREWS
- Extremely high efficiency (generally higher than 90%), making them approximately three times more efficient than conventional screws. Consequently, much less power is dissipated as heat, with evident advantages as far as applied motor and energy savings are concerned.
- A long working life due to excellent resistance to wear.
- High-speed performance capabilities.
- High positioning precision as a result of being able to eliminate play.