Posted to News on 10th Feb 2007, 17:35
LBS cylindrical ball spline eliminates angular backlash
THK is introducing its latest LBS cylindrical ball spline that is designed to eliminate angular backlash while providing high levels of rigidity and accuracy from a compact, rugged device. In addition, the latest LBS ball splines can transmit torque at high linear and rotational speeds, making them suitable for use in a wide range of applications including robotics, machine tool, palletising and materials handling systems, and they can also save money by replacing traditional parallel twin-shaft ball bushing mechanisms with a single, lower-cost unit.
The LBS ball splines are manufactured from cold-drawn and precision-ground steel, with three longitudinal ridges positioned equidistantly at 120-degree intervals around the circumference of the spline shaft. The spline nut locates onto these ridges and incorporates THK's proven circular arc ball-race technology, with two rolls of recirculating balls mounted in precision machined raceways between each spline ridge. The ball-race mechanism is designed so that the steel balls provide smooth, almost frictionless motion with minimal heat, noise or wear.
In operation, one row in each of the three raceway units carries the torque loading in one direction of linear movement, with the second row of each being used in the reverse direction to provide uniform displacement of load. Perhaps as importantly, this configuration helps to minimise angular backlash in the direction of rotation, while backlash can be eliminated entirely by simply pre-loading the spline nut. Due to the innovative construction of the raceways, pre-loading can be achieved without the need to twist the spline nut.
A further advantage of this configuration is a high degree of rigidity and positional accuracy. This is achieved through the close-conformity circular arc contact within the raceway units, and the ability to preload the spline without initial deflection. Additionally, the LBS ball splines can operate at speeds in excess of 150m/minute for sustained periods
LBS ball splines are also available with hollow shafts for running piping, cabling or even laser beams in alignment systems, and in heavy-duty versions for use in applications where high levels of torque of up to 13,900Nm need to be transmitted or where overhung loads are carried.
