Rectilinear motion rolling guide unit

Abstract

There is provided a rectilinear motion rolling guide unit comprising: a long track rail having an almost I-shaped cross section; a casing having an almost inverse U-shaped cross section; and rolling elements interposed between the track rail and the casing. The casing is arranged so as to ride over the track rail by a concave portion formed in the central lower portion of the casing. Upper and lower corner portions of both upper projecting portions of the track rail are chamfered to form inclined surfaces, thereby forming two upper and lower rail side track surfaces, respectively. Two upper and lower casing side track surfaces are formed on the inner peripheral surfaces of the concave portion of the casing at positions corresponding to the two upper and lower rail side track surfaces. A number of rolling elements are interposed between the corresponding track surfaces on the rail and casing sides, respectively, thereby allowing a relative slidable motion between the track rail and the casing. Rolling elements return passageways are formed in the casing in correspondence to the two upper and lower casing side track surfaces. Two upper and lower direction turning passageways for the rolling elements which roll and run on the two upper and lower casing side track surfaces are formed in each of side plates. The side plates are attached to both end portions in the longitudinal direction of the casing, thereby coupling the two upper and lower casing side track surfaces with the corresponding return passages. Thus, two upper and lower endless rolling elements circulating passageways are formed.