Spindle nut, threaded drive, and method for manufacturing a spindle nut

Abstract

Methods for producing a spindle nut, and spindle nuts produced by such methods are disclosed. The method for producing a spindle nut may include producing a blank which has a sleeve portion and a cylindrical outer surface by non-cutting shaping from sheet metal; and forming a thread provided for cooperation with a threaded spindle in the blank by non-cutting shaping, while maintaining the cylindrical outer surface of the sleeve portion.

Claims

1. A method for producing a spindle nut, the method comprising: producing a blank which has a sleeve portion and a cylindrical outer surface by non-cutting shaping from sheet metal wherein, a radially outwardly pointing flange is integrally formed on one end face of the blank and a radially inwardly directed rim is integrally formed on the opposite end face; forming a thread provided for cooperation with a threaded spindle in the blank by non-cutting shaping, while maintaining the cylindrical outer surface of the sleeve portion.

2. The method as claimed in claim 1, wherein the sleeve portion is formed by deep drawing or extrusion and the thread is formed by thread grooving.

3. The method as claimed in claim 1, wherein a wall thickness of the flange and a wall thickness of the rim deviates from a mean wall thickness (W) of the sleeve portion by no more than 15%.

4. A spindle nut, comprising a sleeve portion with a cylindrical outer surface and a threaded inner surface, a radially outwardly pointing flange integrally formed on a first end face of the sleeve portion, and a radially inwardly directed rim integrally formed on a second end face of the sleeve portion opposite the first end face, wherein a depth of threads of the threaded inner surface is at least 20% and at most 50% of a mean wall thickness of the sleeve portion.

5. The spindle nut as claimed in claim 4, wherein the mean wall thickness is less than a quarter of a radius of the sleeve portion.

6. A screw drive comprising a spindle nut as claimed in claim 4 and a threaded spindle cooperating with this spindle nut.

7. The screw drive as claimed in claim 6, wherein it is a non-returning ball screw drive.

8. The screw drive as claimed in claim 6, wherein it is a ball screw drive with a single or external recirculation system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of the disclosure is explained in more detail below with reference to a drawing, which shows:

(2) FIG. 1 a screw drive in a sectional perspective view;

(3) FIG. 2 a spindle nut of the screw drive according to FIG. 1 during the production process;

(4) FIG. 3 a detail of the spindle nut in a schematic sectional illustration.

DETAILED DESCRIPTION

(5) FIG. 1 shows a screw drive 1, namely a ball screw drive, which comprises a spindle nut 2 and a threaded spindle 3. The spindle nut 2 is a single-piece sheet metal part made from sheet steel; the threaded spindle 3 is a steel tube. Balls serving as rolling bodies 4 roll between the threaded spindle 3 and the spindle nut 2. An annular intermediate piece 5, whereof the cross-section is adapted to the contours of the spindle nut 2 and the threaded spindle 3, is furthermore located between the threaded spindle 3 and the spindle nut 2. The intermediate piece 5, which also serves to support a spring, strikes a radially inwardly directed rim 7, which delimits a cylindrical sleeve portion (denoted by 6) of the spindle nut 2 at an end face.

(6) At the opposite end face of the sleeve portion 6, this merges into a radially outwardly directed flange 8. The flange 8 can be provided with fastening bores in a manner which is not shown.

(7) The production of the spindle nut 2 is explained below with reference to FIG. 2: a blank, which is produced by deep drawing from sheet metal and whereof the outer contour already corresponds to the outer contour of the spindle nut 2 but is still smooth on the inner face, is inserted into a die 10 so that the cylindrical outer wall of the sleeve portion 6 lies with its entire surface against the inner wall of the die 10. The flange 8 and the rim 7 likewise lie against the die 10. With the aid of a tool (not illustrated), the thread denoted by 9 is generated in the sleeve portion 6 of the spindle nut 2.

(8) The spindle nut 2 as a whole is then subjected to a heat treatment, in particular to improve the suitability of the thread 9 as a rolling-body track. In this hardened state, the spindle nut 2 can be used without further machining steps for assembly of the screw drive 1. Alternatively, in a manner not shown, the cylindrical outer surface of the sleeve portion 6 can be overmolded with a plastics sheathing, whereof the outer surface is designed as a toothed contour to enable the spindle nut 2 to be driven by a toothed wheel or a toothed belt.

(9) Like the spindle nut 2, the threaded spindle 3 can also be produced by a shaping method. To this end, the threaded spindle 3 is placed on a mandrel (not illustrated) and then machined by a tool which acts on the outer surface of the threaded spindle 3.

(10) The screw drive 1 is a ball screw drive without a ball return. To prevent rolling bodies 4 from falling out of the screw drive 1, an annular end piece (not illustrated) can be arranged on that side of the spindle nut 2 on which the flange 8 is located, analogously to the intermediate piece 5. Instead of a rotation of the spindle nut 2, a rotation of the threaded spindle 3 can also be provided during operation of the screw drive 1, wherein, in this case, the displaceable spindle nut 2 is secured against rotation in a manner which is not illustrated.

(11) FIG. 3 serves to illustrate dimension ratios of the spindle nut 2. The radius of the sleeve portion 6 is denoted by r. R denotes the axis of symmetry of the spindle nut 2, which is identical to the axis of rotation of the screw drive 1. The sleeve portion 6 has a mean wall thickness W which is less than 25% of the radius r. The depth (denoted by T) of the thread 9 corresponds to more than 20% but less than 50% of the mean wall thickness W of the sleeve portion 6 of the spindle nut 2.

LIST OF REFERENCE SIGNS

(12) 1 Screw drive, ball screw drive 2 Spindle nut 3 Threaded spindle 4 Rolling body, ball 5 Intermediate piece 6 Sleeve portion 7 Rim 8 Flange 9 Thread 10 Die r Radius of the spindle nut R Axis of rotation T Depth of the thread W Mean wall thickness