Ball screws convert rotational movements into an axial movement. Ball screws, which are designed as a recirculating ball screw, have a very high level of effi ciency in comparison with planetary screw drives (such as trapezoidal screws or metric screws) due to the lower rolling friction that occurs. In addition, the superior manufacturing precision enables a very low axial play, accompanied by a very high positioning accuracy.
In addition to the ball screw, the BS product series also includes both the bearing and the coupling to the motor.
The duplex bearing used in this case – a pair of angular ball bearings with backlash-free mounting – enables the absorption of axial tensile and compressive forces. The highprecision pin coupling transmits the motor torque to the screw virtually backlash-free.
A number of threaded holes are provided on the front of the housing for the purpose of attaching the motor-screw combination. Because of the high-precision raceways and the lowbacklash or backlash-free adjustment, the ball screw nut
cannot compensate for radial deviations between screw axis and any additional guides of an attachment to the nut. A radial decoupling element must be provided here if necessary. This relates to deviations of the radial distance (misalignment) and angular deviations (tipping) of the guides. In order to reduce radial forces on the bearing, it is recommended that the screw is supported by an additional bearing.
The ball raceways on the ball screws are exposed. For this reason, the screw drives have to be protected against dirt and contamination. The ball screw nut must never, either in operation or during mounting, be moved out beyond the raceway area of the ball screw.