A system comprising a recirculating ball spindle and an associated open nut, of use for supported screwthreaded spindles

Claim 1

A system comprising a recirculating ball spindle and an associated open nut, of use for supported screwthreaded spindles, characterised in that it comprises: a screwthreaded spindle (1) threaded with a hemispherical-section helical groove or channel in its external cylindrical surface; a longitudinal slit hollow cylindrical nut (2) which engages around the spindle (1) except as regards the longitudinal slit (5) and which is formed with a helical groove or channel (2.2) in its inner periphery to match the spindle (1), the external periphery of the nut (2) being formed with a helical channel (2.3) of the same pitch as the internal channel and throughout parallel to the channel in the internal periphery; a cylindrical sleeve or bush (2.4) whose inner periphery has a plain surface and extends around the outer periphery (2.1) of the nut and whose ends are parallel to the ends of the slit (5) in the nut (2); the slit (5) in the nut (2.1) and sleeve (2.4) being bounded by the intersection of the nut sleeve and cylinder with two longitudinal planes containing the radius and rotational axis of the nut, resulting in a front cross-section in the form of a circular crown sector and the longitudinal ends of the slit being two rectangles of plane and equal area, the sides of the rectangles having the hemispherical cross-sections arising from cutting the grooves of the helical channels in the outer and inner peripheries of the nut, the length of the chord of the slit at the ends of the inner circumference of the circular crown sector being less than the diameter of the spindle (1); a number of balls engaged in the groove of the screwthreading of the spindle (1) and in complementary contact with the groove in the nut inner periphery and between the groove in the nut outer periphery and the plain inner surface of the sleeve, the arrangement being such that in response to relative movement between the spindle (1) and the nut (2) there occurs a relative axial movement therebetween through the agency of contact and pressure on the balls rolling along the groove; a ball recirculating mechanism being provided so that the balls roll continuously with the movement mentioned which converts their flow into a closed ball circuit, a flow of balls rolling in each groove in the nut inner periphery to issue at a sectioned end of the groove, move through the parallel groove in the outer periphery and re-enter the opposite end of the same groove in the inner periphery.

Claim 2

A system comprising a recirculating ball spindle and an associated open nut, of use for supported screwthreaded spindles, characterised in that it comprises: a screwthreaded spindle (1) threaded with a hemispherical-section helical groove or channel in its external cylindrical surface; a longitudinal slit hollow cylindrical nut (2) which engages around the spindle (1) except as regards the longitudinal slit (5) and which is formed with a helical groove or channel (2.2) in its inner periphery to match the spindle (1), the external periphery of the nut (2) being formed with a helical channel (2.3) of the same pitch as the internal channel and throughout parallel to the channel in the internal periphery; a cylindrical sleeve or bush (2.4) whose inner periphery has a plain surface and extends around the outer periphery (2.1) of the nut and whose ends are parallel to the ends of the slit (5) in the nut (2); the slit (5) in the nut (2.1) and sleeve (2.4) being bounded by the intersection of the nut sleeve and cylinder with two longitudinal planes containing the radius and rotational axis of the nut, resulting in a front cross-section in the form of a circular crown sector and the longitudinal ends of the slit being two rectangles of plane and equal area, the sides of the rectangles having the hemispherical cross-sections arising from cutting the grooves of the helical channels in the outer and inner peripheries of the nut, the length of the chord of the slit at the ends of the inner circumference of the circular crown sector being less than the diameter of the spindle (1); a number of balls engaged in the groove of the screwthreading of the spindle (1) and in complementary contact with the groove in the nut inner periphery and between the groove in the nut outer periphery and the plain inner surface of the sleeve, the arrangement being such that in response to relative movement between the spindle (1) and the nut (2) there occurs a relative axial movement therebetween through the agency of contact and pressure on the balls rolling along the groove; a ball recirculating mechanism being provided so that the balls roll continuously with the movement mentioned which converts their flow into a closed ball circuit, a flow of balls rolling in each groove in the nut inner periphery to issue at a sectioned end of the groove, move through the parallel groove in the outer periphery and re-enter the opposite end of the same groove in the inner periphery.

Claim 4

A system according to claims 1 and 2, characterised in that when there is relative rotation between the spindle (1) and the nut (2) the spindle (1) rotates and the nut moves axially, to which end any kind of means, such as a key or cotter or the like (4), is provided to secure the nut against rotation.

Claim 5

A system according to claims 1 - 3, characterised in that the spindle (1) is supported on stationary supports in the form of columns (3) along its whole length in the most appropriate form, and when the spindle (1) is rotated the slit nut (2) moves axially, the spindle support columns (3) passing between the ends of the nut slit (5).