Fastener having an inner undercut region

Abstract

A fastening means, in particular for a bellows, comprises a male end segment and a female end segment complementary to the male end segment. The fastening means can be used to fasten bellows to joint housings and/or shafts. The fastening means has an inner undercut region in order to provide an improved closing behavior of the fastening means.

Claims

1. A fastening means, comprising: a male end segment and a female end segment complementary to the male end segment, wherein the female end segment comprises a base on which there is arranged approximately centrally a foot segment and two outer segments, a head part being arranged on the foot segment, and the two outer segments project beyond the head part in a longitudinal direction of the fastening means, the longitudinal direction being approximately perpendicular to the base, the head part projecting laterally over an outer contour of the foot segment and having lower lateral surfaces transverse to a longitudinal direction of the fastening means for fitting at least one inner undercut region in a recess of the male end segment.

2. The fastening means according to claim 1, wherein the foot segment proceeds from the base tapering to a minimum width b.sub.3.

3. The fastening means according to claim 1, wherein a transition angle between the base and the foot segment is in a range from 91 to approximately 110.

4. The fastening means according to claim 1, wherein arranged between lateral longitudinal surfaces of the foot segment and the lower lateral surfaces of the head part are radial regions having notch radii of at least approximately 0.3 millimeters.

5. The fastening means according to claim 1, wherein at least parts of the lateral surfaces of the head part are curved with notch radii of at least approximately 0.3 millimeters.

6. The fastening means according to claim 1, further comprising a lateral head surface of the head part in at least one sub-region approximately parallel to the base.

7. The fastening means according to claim 1, wherein the outer segments have recesses in which extension parts of the male end segment may be arranged.

8. The fastening means according to claim 1, wherein, in addition to the inner undercut region, the male end segment includes at least one outer undercut region.

9. The fastening means according to claim 1, wherein the male end segment has a second foot segment that proceeds from a base tapering to a minimum width b.sub.1.

10. The fastening means according to claim 9, wherein a transition angle between the base and the second foot segment of the male end segment is in a range from approximately 90.5 to approximately 110.

11. The fastening means according to claim 9, wherein, arranged on the male segment at an end of the second foot segment that faces away from the base, is a second head part with extension parts that form the inner undercut region.

12. The fastening means according to claim 11, wherein the extension parts comprise lateral transverse surfaces to form at least one outer undercut region.

13. The fastening means according to claim 12, further comprising at least one of: an acute angle W, formed by the lateral transverse surfaces, with lateral longitudinal surfaces of the foot segment, in a range from approximately 45 to approximately 88 ; and notch radii of at least 0.3 millimeters arranged in a region between the lateral longitudinal surfaces of the foot segment and lateral transverse surfaces of the extension parts.

14. The fastening means according to claim 11, wherein longitudinal surfaces of the extension parts are approximately parallel to the outer wall of the fastening means.

15. The fastening means according to claim 11, wherein between the extension parts of the second head part of the male segment is a recess that is complementary to the head part of the foot segment arranged on the base of the female end segment.

16. The fastening means according to claim 1, wherein a length of the second foot segment and of the second head part including the extension parts is shorter than a width of the fastening means.

17. The fastening means according to claim 1, wherein minimum widths b.sub.21 and b.sub.22 of both of the two outer segments of the female end segments of the female end segment, and a minimum width b.sub.3 of the foot segment of the female end segment, are all selected based on one of the following: (a) for a minimum width b.sub.1 of a second foot segment of the male end segment a ratio b.sub.1:(b.sub.21+b.sub.22+b.sub.3) is approximately 0.79 to approximately 1.27; or (b) there is a recess that is arranged so as to be displaced beyond a base of the male end segment in a length direction of the fastening means, and longitudinal segments in a region of the recess have minimum widths b.sub.11 and b.sub.12, so that a ratio of (b.sub.11+b.sub.12):(b.sub.21+b.sub.22+b.sub.3) is approximately 0.79 to approximately 1.27.

18. The fastening means according to claim 1, wherein the fastening means is at least one of ribbon-like and closable to create a ring in which the male and the female end segments are connected to one another.

19. A system, comprising a bellows and a fastening means, the fastening means comprising: a male end segment and a female end segment complementary to the male end segment, wherein the female end segment comprises a base on which there is arranged approximately centrally a foot segment and two outer segments, a head part being arranged on the foot segment, and the two outer segments project beyond the head part in a longitudinal direction of the fastening means, the longitudinal direction being approximately perpendicular to the base, the head part projecting laterally over an outer contour of the foot segment and having lower lateral surfaces transverse to a longitudinal direction of the fastening means for fitting at least one inner undercut region in a recess of the male end segment.

Description

SUMMARY OF THE DRAWINGS

(1) The foregoing and other advantages of the present disclosure are explained in greater detail using the following figures.

(2) FIG. 1 is a top view of a ribbon-like fastening means in a first example;

(3) FIG. 2A is a male end segment of the fastening means according to FIG. 1;

(4) FIG. 2B is a female end segment of the fastening means according to FIG. 1;

(5) FIG. 3 is a perspective elevation of the fastening means according to FIGS. 1 through 3 in the closed ring condition.

(6) FIG. 4 is a top view of a second example of a closed ring-shaped fastening means;

(7) FIG. 5 is a third example of the fastening means;

(8) FIG. 6 is a detail Y from the second example according to FIG. 4; and,

(9) FIG. 7 is a fourth example of the fastening means.

DETAILED DESCRIPTION

(10) It should first be noted that the examples of the fastening means depicted in the figures should not be interpreted as limiting; for instance, two or more foot segments with head part and extension parts may also be arranged at the base of the female and male end segments in the case of the male end segment. The features described in the figures may be combined to create another example with the features provided in the description above. Moreover, it should be noted that the reference numbers indicated in the description of the figures do not limit the scope of protection for the present disclosure, but instead merely refer to the examples illustrated in the figures. Provided no information to the contrary is explicitly provided, identical parts or part with the same function have the same reference numbers in the following.

(11) FIG. 1 is a top view of a first example of the fastening means 10, which is shown in a ribbon-like shape, i.e., in the non-closed condition. The fastening means 10 has a male end segment 14 and a female end segment 12 between which a strip segment 12 is arranged. The fastening means 10 has an outer wall 11 on both sides.

(12) FIG. 2A depicts a first example of the male end segment 14 of the fastening means 10 according to FIG. 1. A width b, determined between the outer walls 11, of the fastening means 10 or strip segment 12, is greater than a length 1 of the male end segment, measured between a base 22 and lateral head surfaces 33.1 and 33.2. The length 1 is approximately 80% of the width b.

(13) The male end segment 14 has a foot segment 20 and a head part 21. The head part 21 has two extension parts 32.1 and 32.2 that project laterally beyond an outer contour of the foot part 20. The foot part 20 has lateral longitudinal surfaces 30.1, 30.2, an obtuse angle (gamma), approximately 93, being formed between the base 22 and the lateral longitudinal surfaces 30.1 and 30.2. A notch radius r.sub.5 of approximately 0.3 mm is provided in the region of the transition from the base 22 to the lateral longitudinal surfaces 30.1 and 30.2. The foot part 20 is embodied tapering to a minimum width b.sub.1. Provided following this minimum width b.sub.1 is a first notch radius r.sub.1, having a value of 0.8 mm, which transitions continuously tangentially into a notch radius r.sub.2 of 0.3 mm. These notch radii r.sub.1 and r.sub.2 represent the transition from the lateral longitudinal surfaces 30.1 and 30.2 of the foot segment 20 to lateral transverse surfaces 34.1 and 34.2 of the extension parts 32.1 and 32.2, which lateral transverse surfaces 34.1 and 34.2 are arranged in a first and only outer undercut region 26. These then transition into lateral surfaces 35.1 and 35.2 of the extension parts 32.1 and 32.2 with a minimum notch radius r.sub.3 of 0.3 mm and connecting thereto continuously tangentially with a notch radius r.sub.4 of 0.8 mm. The lateral surfaces 35.1 and 35.2 are not embodied running parallel to the outer wall 11 of the fastening means 10, but instead at an angle of approximately 3 thereto, so that the extension parts 32.1 and 32.2 are embodied somewhat tapering toward the lateral head surfaces 33.1 and 33.2 thereof that can be associated with the female end segment 16. This provides a region, following the notch radius r.sub.4, having a minimum width b.sub.2 in the complementary female segment 16, as may be seen below in FIG. 2b. In the male end segment 14, the foot segment 20 has a greater width b.sub.4 on the base 22 than in the region of the minimum width b.sub.1.

(14) The transition between the lateral longitudinal surfaces 35.1 and 35.2 of the extension parts 32.1 and 32.2 into the lateral head surfaces 33.1 and 33.2 runs essentially at a right angle.

(15) Due to production tolerances, however, notch radii may be up to 0.3 mm.

(16) The lateral transverse surfaces 34.1 and 34.2 of the extension parts 32.1 and 32.2 are embodied at an acute angle W of 85 with the lateral longitudinal surfaces 30.1 and 30.2 of the foot segment 20.

(17) The head part 21 of the male end segment 16 has a mushroom head-shaped recess 38 that is for forming an inner undercut region 36 and that is embodied proceeding from the lateral head surfaces 33.1 and 33.2 of the extension parts 32.1 and 32.2. The lateral head surfaces 33.1 and 33.2 transition to inner lateral longitudinal surfaces 40.1 and 40.2 for forming a sort of mushroom stem for the mushroom head-shaped recess 38. The mushroom head of the mushroom head-shaped recess 38 has a lateral base surface 41, some of which is linear and parallel to the base 22 and transitions into curved inner lateral surfaces 42.1 and 42.2 without any linear segments so that ultimately a mushroom head is formed. Minimum widths b.sub.61 and b.sub.62 of the extension parts 32.1 and 32.2 may be found in the region of the mushroom head-shaped recess 38.

(18) FIG. 2B depicts the female end segment 16 of the fastening means 10, in which are shown the only outer undercut region 27, also cited with respect to the complementary example to the male end segment 14, and the inner undercut region 36. The outer undercut regions 26 and 27 extend from the minimum width b.sub.1 of the foot segment 20 of the male end segment 14 to the minimum width b.sub.21 or b.sub.22 of longitudinal segments 50.1 and 50.2 of the female end segment 16. The inner undercut region 36 extends from a minimum width b.sub.3 of a foot segment 56 of the female end segment 16 to the minimum width b.sub.61 and b.sub.62 of the extension parts 32.1 and 32.2 of the male end segment 14. Proceeding from a base 54 of the end segment 16, a foot segment 56 with a head segment 57 is arranged approximately in the center. The foot segment 56 has a minimum width b.sub.3.

(19) Lateral longitudinal surfaces 58.1 and 58.2 of the length segment 56 transition from an obtuse angle of approximately 95 into the base 54. The foot segment 56 is thus embodied tapering towards the head part 57. Connecting to the lateral longitudinal surfaces 58.1 and 58.2 of the length segment are lower lateral transverse surfaces 63.1 and 63.2 that are embodied at least in part parallel to the base 54 and transition to curved lateral surfaces 62.1 and 62.2, which themselves transition to a lateral head surface 60 that is embodied with a center sub-region approximately parallel to the base 54. In the transition between the lateral longitudinal surfaces 58.1 and 58.2 of the foot segment 56 and the lower lateral transverse surfaces 63.1 and 63.2, radial regions 59.1 and 59.2 immediately following the minimum width b.sub.3 have a notch radius of 0.8 mm and then tangentially continuously a notch radius of 0.3 mm.

(20) Length segments 50.1 and 50.2, whose outer walls 51.1 and 51.2 transition flush into the outer wall 11 of the fastening means 10, are embodied on both sides of the mushroom head-shaped center formed by the foot segment 56 and the head part 57. At its end that may be associated with the male end segment, the length segments 50.1 and 50.2 have recesses 53.1 and 53.2 in which extension segments 24.1 and 24.2 (see FIG. 2A) of the male end segment 14 may engage. This provides a longitudinal undercut 28 (see FIG. 2A). Projections 52.1 and 52.2 of the length segments 50.1 and 50.2, associated with the male end segment 14, come to be positioned therein in recesses 25.1 and 25.2 (see FIG. 2a).

(21) The length segments 50.1 and 50.2 have minimum widths b.sub.21 and b.sub.22. These minimum widths b.sub.21 and b.sub.22 follow second inner lateral transverse surfaces 65.1 and 65.2 within the outer undercut region 27 and are in the transition to the second inner lateral longitudinal surfaces 64.1 and 64.2, wherein immediately connected to the minimum widths b.sub.21 and b.sub.22 is a notch radius of 0.8 mm and provided connected therein is a notch radius of 0.3 mm. The second inner lateral transverse surfaces 65.1 and 65.2 then transition into the first inner lateral transverse surfaces 66.1 and 66.2.

(22) The ratio of the widths b.sub.1:(b.sub.21+b.sub.22+b.sub.3) is approximately 0.87. With such a ratio, the minimum cross-sectional width of the male end segment 14 and the minimum cross-sectional widths of the female end segment 16 optimize the values for tensile stresses in the fastening means once it has been closed to create a ring.

(23) The outer undercut region 26 of the male end segment 14 comprises the lateral transverse surfaces 34.1 and 34.2 with connecting radial regions as seen above and below in the length direction of the fastening means 10. According to FIG. 2B, the inner undercut region 36 is formed by the lower lateral transverse surfaces 63.1 and 63.2 and the radial regions connected thereto.

(24) FIG. 3 is a perspective elevation of the first example of the fastening means 10, shaped as a closed ring. In contrast, FIG. 4 is a top view onto a closed ring in a second example of the fastening means 10, the detail Y being shown in FIG. 6. This second example is essentially embodied similar to the first example according to FIGS. 1 through 3, but the lateral longitudinal surfaces 35.1 and 35.2 of the extension parts 32.1 and 32.2 of the head part 21 are oriented exactly parallel to an outer wall 11 of the fastening means 10. In addition, an angle , which is determined by the lateral transverse surfaces 34.1 and 34.2 and their linear segments on the one hand and, on the other hand, by a straight line running through the base 22 of the male end segment 14 or a parallel thereto, is 10 and not 5, as in the example according to FIG. 2a. Consequently, in this example the value for the acute angle W, which is not shown in FIG. 6, is approximately 80, since the angle , which is also not shown in FIG. 6, is 93, just as in the first example according to FIG. 2a. However, the acute angle W may also be, for instance, 70 in an alternative to the example according to FIG. 6. FIG. 6 provides an idealized view of the union of the male end segment 14 and the female end segment 16 on the fastening means 10 that has been closed to create a ring. In fact, due to the use of bending tools there may be minor material deformations, however, so that the precise geometrical values, that is, the precise shape of the male and female end segments 14, 16 in the closed ring, deviate somewhat from those of the open ribbon segment as shown in FIGS. 1 and 2a/b.

(25) FIG. 5 depicts a third example of the fastening means 10 when closed, i.e. with male and female end segments, this third example differing from the first and second examples largely in that the foot segment 56 of the female end segment 16 has been lengthened significantly, specifically beyond the base 22 of the male end segment 14 in the length direction of the fastening means 10. Because of this, the head part 57 is disposed on the far side of the base 22 so that then, ultimately, embodied in the male end segment 14 is a recess 38 that is displaced beyond the base 22 in the length direction of the fastening means. In the example according to FIG. 5, the minimum width b.sub.1 is formed by the two sub-widths b.sub.11 and b.sub.12, so that there is a ratio (b.sub.11+b.sub.12):(b.sub.21+b.sub.22+b.sub.3) of 0.8. The widths b.sub.11 and b.sub.12 of the male end segment 16 then relate to the longitudinal segments 18.1 and 18.2 thereof, which were created due to the displacement of the recess 38 beyond the first base 22 in the length direction of the fastening means.

(26) Finally, FIG. 7 depicts a fourth example of the fastening means 10 in the closed, ring-shaped condition. In this example, a first and a second outer undercut region 26.1 and 26.2 are provided in the male end segment 14 and a first and a second outer undercut region 27.1 and 27.2 of the female end segment 16 are provided. The male end segment 14 may therefore be considered to be shaped like a tree. The minimum width b.sub.2 of a second male foot segment 20.2 in the second undercut region 26.2 is therefore used to determine the ratio for the second stage: b.sub.2:(b.sub.21+b.sub.22), b.sub.21 and b.sub.22 being minimum widths of longitudinal segments 50.1 and 50.2 of the female end segment 16 in the latter's second outer undercut region 27.2, so that the ratio is approximately 0.8, while for determining the cross-sectional width ratio, a minimum width b.sub.1 of the male foot segment 20.1 in the latter's first undercut region 26.1 and widths b.sub.11 and b.sub.12 of the outer lateral longitudinal segments 50.1 and 50.2 of the female end segment in the latter's first undercut region 27.1 and also a minimum width b.sub.3 of the inner undercut region 36 are used on the first stage, and the ratio there b.sub.1:(b.sub.11+b.sub.12+b.sub.3) is approximately 0.8. Because two outer undercut regions 26.1 and 26.2/27.1 and 27.2 are provided, the fourth example according to FIG. 7 has excellent values for static tensile elongation. Following the first undercut region 26.1, then, a longitudinal undercut region is again provided due to the trough-like formation 44, as is provided by the projections 24.1 and 24.2 in the first example according to FIG. 2a, for instance. In addition, however, corresponding projections 24.1 and 24. 2 are also provided on the base 22. Otherwise the upper part with the recess 38 is embodied identical to the second example according to FIGS. 4 and 6. If there was a desire to provide two inner undercut regions, in a tree-like manner a recess 38 would be provided in the adjacent segment or a foot 20.1 would also be provided.

(27) With the fastening means, a fastening means is provided that supplies better values in terms of tensile and bending load, so that ultimately crack openings are prevented during operation and the service life of the fastening means is thereby significantly extended.