Profiled nut of a screw drive, in particular a ball screw nut of a ball screw drive, and method for the production thereof

Abstract

A profiled nut (1) of a screw drive includes a sleeve (3) produced from sheet steel, has a non-cuttingly formed rolling profile (4) on the inner circumference for rolling contact with rolling bodies and is hardened in a heat treatment method at least in the region of the rolling profile (4). An inner lateral surface of the sleeve (3) having the rolling profile (4) is hardened and has a higher Rockwell hardness. An outer lateral surface of the sleeve (3) is designed such that it can be welded and has a lower Rockwell hardness.

Claims

1. A profiled nut of a screw drive, a sleeve of which, produced from a multi-layer composite sheet steel, has a non-cuttingly formed rolling profile on its inner circumference for rolling contact with rolling bodies and is hardened in a heat treatment method at least in a region of the rolling profile, wherein an inner lateral surface of the sleeve having the rolling profile is hardened and has a first Rockwell hardness, and an outer lateral surface of the sleeve is configured such that it can be welded and has a second Rockwell hardness lower than the first Rockwell hardness, and wherein the multi-layer composite sheet steel includes: i) a first layer comprising an alloyed steel forming the inner lateral surface of the sleeve and having a first carbon content, and ii) a second layer forming the outer lateral surface comprising an alloyed steel having a second carbon content lower than the first carbon content.

2. The profiled nut according to claim 1, wherein the sleeve is carburized on only the inner lateral surface and then hardened in the heat treatment method.

3. The profiled nut according to claim 1, wherein the sleeve is provided at one axial end with a flange, which is weldable and has a lower Rockwell hardness than the first Rockwell hardness.

4. The profiled nut according to claim 3, wherein the sleeve is carburized on only the inner lateral surface and then hardened in the heat treatment method, and the flange is integrally connected to the sleeve and is free of carburization at its end facing away from the sleeve.

5. The profiled nut according to claim 1, wherein the sleeve is provided at one axial end with a flange integrally connected to the second layer of the multi-layer composite sheet steel.

6. The profiled nut according to claim 1, configured as a ball screw nut of a ball screw drive, the ball screw nut having a ball groove helically wound around a nut axis formed by the rolling profile.

7. A method for producing a profiled nut according to claim 1, wherein the multi-layer composite sheet steel is formed into the sleeve in a forming process and then hardened in a heat treatment method.

8. The method according to claim 7 for producing a profiled nut, comprising: forming the multi-layer composite sheet steel into the sleeve with an integrally formed flange; at least in sections, removing the first layer of the multi-layer composite sheet steel on the integrally formed flange on a side provided as a weld surface for a weld-on component; and hardening the profiled nut in the heat treatment method.

9. The method according to claim 7 for producing a profiled nut, comprising: carburizing one side of the multi-layer composite sheet steel; forming the multi-layer composite sheet steel to form the sleeve with an integrally formed flange; and hardening the profiled nut in the heat treatment method.

10. The method according to claim 9 for producing a profiled nut, further comprising: removing the carburization on the integrally formed flange to form a weld surface.

11. The profiled nut according to claim 1, wherein the sleeve has an undulating profile when viewed in longitudinal section.

12. The profiled nut according to claim 1, wherein the multi-layer composite sheet steel includes a copper layer arranged between the first layer and the second layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The method and profiled nut is explained in more detail below with reference to exemplary embodiments shown in 3 out of a total of 6 figures. In the figures:

(2) FIG. 1 shows a profiled nut designed as a ball screw nut of a ball screw drive in longitudinal section,

(3) FIG. 2 shows an enlarged detail from FIG. 1,

(4) FIG. 3 shows another ball screw nut in longitudinal section,

(5) FIG. 4 shows a detail from FIG. 3,

(6) FIG. 5 shows another ball screw nut in longitudinal section,

(7) FIG. 6 shows an enlarged detail from FIG. 5.

DETAILED DESCRIPTION

(8) In all figures, a profiled nut of a screw drive is shown in the form of a ball screw nut of a ball screw drive.

(9) FIG. 1 shows in longitudinal section a profiled nut 1 of a screw drive with weld-on component 7 in longitudinal section. This profiled nut 1 is designed as a ball screw nut 2. The ball screw nut 2 has a sleeve 3 made of sheet steel, on the inner circumference of which a rolling profile 4 formed without cutting is configured for rolling contact with rolling elements, not shown. The rolling profile 4 is designed as a ball groove 5 which is helically wound around a spindle axis and on which rolling elements formed by balls, not shown, can roll.

(10) The sleeve 3 is provided with a flange 6 at one axial end. The weld-on component 7 is welded to the flange 6.

(11) FIG. 2 is an enlargement of the connection between the sleeve 3 and the weld-on component 7 via the flange 6. It can be clearly seen that the flange 6 is welded to the end face of the sleeve 3 with a weld seam 8, wherein the weld seam 8 penetrates the thickness of the flange 6.

(12) In the exemplary embodiment, the weld-on component 7 is welded to the end face 10 of the flange 6 facing away from the sleeve 3 by means of a fillet weld 9.

(13) The exemplary embodiment according to FIGS. 3 and 4 differs from that of FIGS. 1 and 2 only in that a flange 16 is formed which is integrally connected to the sleeve 3, and to whose end face 17 facing the weld-on component 7 the weld-on component 7 is welded.

(14) The embodiment according to FIGS. 5 and 6 differs from that of FIGS. 3 and 4 only in that a flange 18 is integrally formed with the sleeve 3, the free end of which is provided with a flanging 19 so that the outer lateral surface of the sleeve 3 forms an end face 20 which faces the weld-on component 7 and is welded to the weld-on component 7.

(15) In all of the exemplary embodiments, on its inner lateral surface the sleeve 3 is provided with a hardened layer 11, which in the figures is based on two different structures of the sheet steel as an alternative.

(16) Alternative 1: This hardened layer 11 can be formed by carburization 12 of the sheet steel with subsequent heat treatment. The carburization 12 on the inner lateral surface of the sleeve 3 can be clearly seen in all the exemplary embodiments. In this case the sleeve 3 is case hardened. The sleeve 3 made from this sheet metal is non-rolling on its inner lateral surface after hardening.

(17) Alternative 2: This hardened layer 11 can also be provided by a sheet steel that is designed as a two-layer composite material 13. The two-layer composite material 13 can be clearly seen in all exemplary embodiments. A first layer 14 of this composite material 13 is formed from an alloyed steel which has a higher carbon content and forms the inner lateral surface of the sleeve 3. A second layer 15 is formed from an alloyed steel which forms the outer lateral surface of the sleeve 3 and has a comparatively lower carbon content, which is characterized by better weldability. The sleeve 3 made from this composite sheet is non-rolling on its inner lateral surface after hardening.

(18) In all of the exemplary embodiments, the weld-on component 7 is welded to a weldable surface either on the sleeve 3 or on the flange 6, 16, 18 firmly connected to the sleeve 3. 1 Nut 2 Ball screw nut 3 Sleeve 4 Rolling profile 5 Ball groove 6 Flange 7 Weld-on component 8 Weld seam 9 Fillet weld 10 End face 11 Hardened layer 12 Carburization 13 Composite material 14 First layer 15 Second layer 16 Flange 17 End face 18 Flange 19 Flanging 20 End face