Ball screw drive

Abstract

A ball screw having a spindle nut (21), a threaded spindle, and a retaining element (23) is provided. The retaining element (23) is connected in a form-fitting, play-free manner to the threaded nut (21) by a projection (24) which fits around the outside of the threaded nut (21) in an end region. The threaded nut (21) and the retaining element (23) functioning as a force transmission member are first positioned precisely during manufacture and then connected by a form-fitting, in particular play-free connection, in particular by caulking, crimping, clinching or other deformation processes.

Claims

1. A method for producing a ball screw which has a threaded spindle, a threaded nut, and a retaining element, the method comprising: first positioning the threaded nut and the retaining element which functions as a force transmission member together precisely during manufacture without deformation of the threaded nut or the retaining element by axially pushing the retaining element into a defined fit position on the spindle nut body against a stop region in which an axial end of the threaded nut contacts a surface of the retaining element and a projecting region of the retaining element that fits over the end of the threaded nut extends axially beyond the stop region, and then connecting said retaining element by a form-fitting connection via a radial application of force at least in some sections of the projecting region axially spaced from the stop region to at least one of caulk, crimp, clinch, or deform material of the projecting region onto the threaded nut without affecting a position of the stop region.

2. The method according to claim 1, wherein, during production of the form-fitting connection between the threaded nut and the retaining element, material of the retaining element is pressed into a filling region on the threaded nut.

3. The method according to claim 1, wherein the form-fitting connection of the retaining element to the spindle nut is supported by at least one of a roughening, knurling or other surface treatment or a surface coating in the filling region.

4. The method for producing a ball screw according to claim 1, wherein the spindle nut includes a peripheral groove on an outside thereof axially spaced from the stop region, and the method further comprises connecting said retaining element by the at least one of caulking, crimping, clinching, or deforming the material of the retaining element into the peripheral groove.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a ball screw according to the prior art;

(2) FIG. 2 shows a section through a spindle nut according to the prior art;

(3) FIG. 3 shows a flange detail from FIG. 2;

(4) FIG. 4 shows an embodiment of the invention;

(5) FIG. 5 shows a detail X from FIG. 4; and

(6) FIG. 6 shows an axial plan view of a flange according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) The invention is explained in more detail by the attached drawings. FIG. 1 shows, as the prior art, a ball screw 7 with a threaded spindle 2 and a spindle nut (ball circulation nut) 1 fitting around said spindle. The nut body has incorporated ball races 5, which are designed to match the geometry of the threaded spindle 2. The nut body has a plurality of load-bearing ball races 5, that is, inner threads which together with the outer thread of the spindle form the space for accommodating the load-bearing balls 3, 4. With the ball return (often also referred to as ball recirculation), the balls are lifted completely off the spindle at the end of the thread by inserts in the nut and directed back through a return tube, for example. A flange 6 acts as a torque transmission means.

(8) FIG. 2 shows a sleeve-like threaded nut 10 in an alternative design (still) without torque support. The sectional drawing shows a sleeve-like formation at one end of the spindle nut with a stop region 12 and a radially peripheral groove 14 forming an undercut. Feature 13 is a ball channel.

(9) FIG. 3 shows the spindle nut 10 of FIG. 2 with a crimped flange 6. During the joining process, the material of the flange in the stop region 12 is deformed and fills the peripheral groove 14 at least partially on the circumference. The flange 6 and the threaded nut 10 thus form a joined unit; this crimping process has a negative effect on the dimensional stability of the overall connection. If knurling 11 is provided in the stop region 14, the torque transmission in the final state is also improved.

(10) FIG. 4 and FIG. 5 in detail show a joined connection of a flange element or retaining element 23 with a spindle nut 21 according to the invention. During production, the retaining element 23 is pushed onto the spindle nut 21. As soon as a precise fit has been achieved in the stop region 22 or the positioning plane 25, the projection 24 is crimped onto the spindle nut 21. In this case, only material from the projection 24 or in the edge region of the nut body is affected; there is no reshaping in the region of the stop region 22 responsible for the fit accuracy. The joining region 20 faces away from the fit 22, therefore the reshaping has no effect.

(11) FIG. 6 shows a retaining element 23/flange in plan view in the assembled state with recesses 27, in this case press marks.

LIST OF REFERENCE SYMBOLS

(12) 1 Spindle nut 2 Threaded spindle 3 Ball 4 Ball 5 Ball races 6 Flange 7 Ball screw 10 Spindle nut, alternative design 11 Knurling 12 Stop region 13 Channel 14 Inner, radially peripheral groove 20 Joining region 21 Spindle nut 22 Stop region 23 Retaining element, flange 24 Projection 25 Positioning plane 26 Filling region 27 Recess