Kinetic Behavior of Linear Motion Bearings Applied Linear Motor.

Abstract

This paper deals with the kinetic behavior of linear motion bearings applied a permanent magnet type linear synchronous motor (LSM). It is neccessary to make clear normal force characteristics of the LSM, because the normal force acts on the bearings and influences the life time of the bearings. Static thrust and normal force characteristics of the LSM were investigated from both sides of theory and experiment, and the nominal life of the bearings was investigated through the experimental transit The results are as follows:(1) The static thrust is 450 N, and the normal force is 2.9 kN at exciting current 8.8A. The normal force increases in proportion to exciting current, and shows constant value for displacement. The error of calculated value through finite element method is found within 20% of measured value of normal force.(2) The acceleration arising from the bearings themselves is over 50m/S2. The maximum variable load generated by the acceleration reaches to 1.1 kN, and namely the ratio of the variable load is equal to 38% of the normal force.(3) The nominal life of the bearings is calculated in 4, 100km with empirical load factor. In the test for durability, the LSM is driven in reciprocating motion at maximum speed 2m/s, stroke length of 800mm. The distance of the test with periodic lubrication has been found over 16, 000km. It will be necessary to reconsider the load factor of the linear motion bearings.