Rolling die

Abstract

A rolling die for forming a screw thread on a screw blank is disclosed. The rolling die has a plurality of grooves, where the grooves each have two flanks as seen in cross-section. At least a portion of each of the grooves has a forming area in which the size of a profile angle enclosed by the flanks decreases continuously along the grooves.

Claims

1. A rolling die for forming a screw thread on a screw blank, comprising: a planar working face, wherein the planar working face has a plurality of grooves, wherein the grooves are each defined by two flanks in cross-section, and wherein at least a portion of each of the grooves has a forming area wherein the two flanks define a profile angle and wherein a size of the profile angle defined by the two flanks decreases continuously along the groove.

2. The rolling die according to claim 1, wherein a width of at least a portion of the groove in the forming area decreases continuously along the groove.

3. The rolling die according to claim 1, wherein at least a portion of each of the grooves has a foot area with a foot area profile angle in at least a portion of the forming area in cross-section, and a portion of each of the grooves has a head area with a head area profile angle, wherein the foot area profile angle is smaller than the head area profile angle, wherein at least a size of the foot area profile angle in the forming area decreases continuously along the groove, and wherein the foot area profile angle and the profile angle are a same angle.

4. The rolling die according to claim 1, wherein a pitch angle between the grooves and a longitudinal axis of the rolling die varies along the grooves at least in the forming area.

5. A method for forming a screw thread on a screw blank comprising forming the screw thread on the screw blank by the rolling die according to claim 1.

6. A rolling die for forming a screw thread on a screw blank, comprising: a planar working face, wherein the planar working face has a groove, wherein the groove is defined by two flanks in cross-section, wherein the two flanks define a profile angle and wherein a size of the profile angle defined by the two flanks decreases continuously along a length of the groove.

7. The rolling die according to claim 6, wherein a width of the groove decreases continuously along the length of the groove.

8. The rolling die according to claim 6, wherein the groove has a foot area with a foot area profile angle and a head area with a head area profile angle, wherein the foot area profile angle is smaller than the head area profile angle, wherein the foot area profile angle decreases continuously along the length of the groove, and wherein the foot area profile angle and the profile angle are a same angle.

9. The rolling die according to claim 6, wherein a pitch angle between the groove and a longitudinal axis of the rolling die varies along the length of the groove.

10. The rolling die according to claim 8, wherein a depth of the groove increases continuously along the length of the groove.

11. The rolling die according to claim 6, wherein a width of the groove decreases continuously along the length of the groove and wherein a depth of the groove increases continuously along the length of the groove.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a top view of an exemplary embodiment of rolling dies according to the invention with grooves;

(2) FIG. 2 illustrates the cross-sectional shape of a groove from FIG. 1;

(3) FIG. 3 illustrates the cross-sectional shape of a groove of a rolling die according to another exemplary embodiment; and

(4) FIG. 4 illustrates the cross-section of a groove of a rolling die according to another exemplary embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 1 shows a first exemplary embodiment of a rolling die according to the invention. The rolling die 1 shown here is embodied as a flat rolling die and, as such, it has a planar working face 3. To perform other rolling methods, the working face 3 may fundamentally also be designed with a curvature. A plurality of at least approximately parallel thread forming grooves 10 is created in the working face 3, running at an angle to the longitudinal axis 5 of the rolling die.

(6) In a refinement (not shown), the pitch angle may be variable in the longitudinal direction 15 of the grooves 10, so that a change in the rolling circle can be taken into account.

(7) FIG. 2 shows the progression in the cross-section of a groove 10 from FIG. 1 in the longitudinal direction 15 of the groove 10, wherein the view at the lower left in FIG. 2 shows the groove 10 at the section A-A from FIG. 1, and the view at the upper right in FIG. 2 shows the groove 10 at the section B-B from FIG. 1. Accordingly, the variables assigned to the section A-A in FIG. 1 are labeled with the index A and the variables assigned to the section B-B are labeled with the index B. The cross section of the groove 10 is shown with hatching in FIG. 2, and the progression in the groove between sections A-A and B-B is obtained from the dotted lines connecting the sections in FIG. 2.

(8) As FIG. 2 shows, the groove depth Z, the groove width a on the groove opening side and the groove width b on the groove bottom side undergo changes along the longitudinal direction 15 of the groove 10 of the profile angle between two flanks 11 and 12; namely Z increases, while , a and b decrease continuously from the inlet area, which is situated near the section A-A, to the calibration area, which is situated near the section B-B.

(9) FIG. 3 shows other possible cross-sectional progressions in the groove 10 in a diagram like that in FIG. 2, showing a first alternative with dotted lines and a second alternative with dash-dot lines. According to the exemplary embodiments of FIG. 3, the profile angle follows a hyperbolic function.

(10) FIG. 4 shows another exemplary embodiment of a groove cross-section. According to the exemplary embodiment in FIG. 4, it is possible to differentiate a foot area 22 on the groove bottom and a head area 21 at the groove opening, in which different profile angles 0 and/or are provided between the flanks 11 and 12. An auxiliary angle , which permits even gentler forming, is thus implemented.

(11) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.