Roller screw bidirectional and alternated preloading structure with built-in metal springs

Abstract

A bidirectional staggered preload structure for a roller screw with a built-in spring includes a screw, a nut, a roller assembly, two retaining preload units, and a fastener assembly. The screw has a threaded structure on its outer circumferential surface, the nut is fitted onto the screw, and its inner circumferential surface has an annular groove section and two limiting grooves. The roller assembly is disposed between the screw and the nut, comprising staggered first and second rollers. Each roller has annular teeth on its outer circumference, which mesh with the threaded structure and the annular groove section. The two retaining preload units are respectively disposed at two opposite ends of the roller assembly. Each retaining preload unit includes a retainer and a spring. The two retainers each have a plurality of retaining holes for accommodating the positioning ends of each roller. The spring forms a plurality of elastically tilted feet that are inclined and raised towards the roller assembly along the circumferential direction, and is radially offset relative to the retaining holes. A gap is formed between the positioning end of each roller and the bottom of the corresponding retaining hole, and the tip abuts against the elastic foot on the opposite side and causes it to elastically deform. Through this gap and abutting relationship, axial preload in opposite directions can be applied to the first roller and the second roller respectively, forming a bidirectional staggered preload effect, thereby compensating for the gap, improving transmission accuracy and motion stability.

Claims

1. A bidirectional staggered preload structure for a roller screw with a built-in spring sheet, comprising: A screw with a threaded structure on its outer circumference; a nut fitted onto the screw, with at least one annular groove section and two limiting grooves on its inner circumference; a roller assembly disposed between the screw and the nut, having a plurality of staggered first rollers and a plurality of second rollers, each first roller having a first positioning end and a first tip at both ends, and each second roller having a second positioning end and a second tip opposite to the ends of the first roller, each roller having an annular tooth on its outer circumference that meshes with the threaded structure and the annular groove section; two retaining preload units disposed within the nut and located at both ends of the roller assembly, each including a retainer and a spring plate, the retainer having a plurality of retaining holes, each retaining hole accommodating the first positioning end and the second positioning end, the spring plate being disposed between the inner side of the retainer and the roller assembly, and having a plurality of elastically tilted and tilted towards the roller assembly along the circumferential direction. The elastic feet are radially offset relative to the retaining holes, and the elastic feet of the two spring pieces elastically abut against the first tip and the second tip respectively; a fastener assembly has two fasteners respectively disposed on the outside of the two retaining preload units and embedded in the limiting groove, for axially limiting the two retaining preload units within the nut; by means of the radial offset of the elastic feet and the retaining holes, the first tip and the second tip abut against the elastic feet of the two spring pieces respectively, thereby causing the elastic feet to elastically deform, and the first positioning end and the second positioning end to form a first gap and a second gap with the bottom of their corresponding retaining holes respectively, so that the preload is transmitted from the first tip and the second tip to the opposite direction, applying axial preload in opposite directions to the first roller and the second roller, thereby forming bidirectional staggered preload at both ends of the roller assembly, reducing the back clearance between the screw and the nut, and maintaining pure rolling contact of the rollers.

2. The roller screw bidirectional staggered preload structure with built-in spring sheet as described in claim 1, wherein the retainer is provided with a plurality of fitting grooves, the spring sheet is an annular spring sheet, and its outer edge is provided with a plurality of fitting feet, which are correspondingly embedded in the fitting grooves to achieve detachable positioning.

3. The bidirectional staggered preload structure of the built-in spring sheet with roller screw as described in claim 1, wherein each of the plurality of elastic feet of the spring sheet is provided with a groove, and the first tip and the second tip respectively correspond to the groove.

4. The bidirectional staggered preload structure of the built-in spring sheet roller screw as described in claim 3, wherein the groove is an arc-shaped groove, a conical groove, or a geometric groove; the first tip and the second tip are conical and form point contact with the groove.

5. The bidirectional staggered preload structure of the roller screw with built-in spring as described in claim 1, wherein the elastic springs are arranged radially at intervals and are in a raised state when not under force.

6. The bidirectional staggered preload structure of the built-in spring sheet roller screw as described in claim 1, wherein a bearing is provided between the preload holding unit and the fastener.

7. The bidirectional staggered preload structure of the built-in spring sheet with roller screw as described in claim 1, wherein the retainer and the spring sheet are integrally formed.

8. A bidirectional staggered preload structure for a roller screw with a built-in spring sheet, comprising: A screw with a threaded structure on its outer circumference; a nut fitted onto the screw, with at least one annular groove section and two limiting grooves on its inner circumference; a roller assembly disposed between the screw and the nut, having a plurality of staggered first rollers and a plurality of second rollers, each first roller having a first positioning end and a first tip at opposite ends, and each second roller having a second positioning end and a second tip opposite to the ends of the first roller, each roller having an annular tooth on its outer circumference that meshes with the threaded structure and the annular groove section; two retaining preload units disposed at opposite ends of the roller assembly, each including a spring plate, each spring plate having a plurality of positioning holes and a plurality of elastic rests tilted and raised towards the roller assembly, and each of the two spring plate positioning holes respectively accommodating the first positioning end and the second positioning end, the elastic rests of the two spring plate being positioned relative to the positioning holes. The components are radially misaligned and elastically abut against the corresponding first and second tips respectively; a fastener assembly has two fasteners, which are respectively disposed on the outside of the two retaining preload units and embedded in the limiting groove, for fixing the two retaining preload units and axially limiting them within the nut; by means of the radial misalignment of the elastic flaps and the positioning holes, the first tip and the second tip abut against the elastic flaps of the two spring pieces respectively, and the elastic flaps undergo elastic deformation, thereby causing the first positioning end and the second positioning end to form a first gap and a second gap with their corresponding positioning holes respectively, so that the first tip and the second tip respectively transmit preload in opposite directions, applying axial preload in opposite directions to the first roller and the second roller, thereby forming bidirectional staggered preload at both ends of the roller assembly, so as to reduce the back clearance between the screw and the nut and maintain pure rolling contact of the rollers.

9. The bidirectional staggered preload structure of the built-in spring sheet roller screw as described in claim 8, wherein the elastic spring has a groove at a free end, and the groove forms point contact with the corresponding first tip or second tip.

10. The bidirectional staggered preload structure of the built-in spring sheet roller screw as described in claim 9, wherein the groove is an arc-shaped groove, a conical groove, or a geometric groove; the first tip and the second tip are conical and form point contact with the groove.

11. The bidirectional staggered preload structure of the built-in spring sheet with roller screw as described in claim 8, wherein a bearing or a washer is provided between each spring sheet and the fastener.

Images