Capped rivet

A capped rivet has a cap 10 with an exposed topside 14 and an inside 18 and further has a rivet part 20 with a rivet shank 22 and a rivet flange 24. The rivet shank 22 extends away from the inside 18 of the cap 10 and the rivet flange 24 extends transverse to the axis 23 of the rivet shank 22. The rivet flange 24 is firmly attached to the cap 10, and a reinforcing element 26 is arranged at the underside 25 of the rivet flange 24.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a capped rivet with two parts: a cap part
 (cap, for short) and a rivet part. The cap has an exposed topside and an
 inside, and the rivet part has a rivet shank and a rivet flange. The rivet
 shank extends away from the inside of the cap, and the rivet flange
 extends transverse to the axis of the rivet shank and is firmly attached
 to the cap. The invention also relates to an attachable element comprising
 a capped rivet of this kind and to a carrier material to which the
 attachable element is connected.
 Capped rivets as introduced above may have the form of decorative elements
 that are attachable to a sheet-like carrier material, for example to
 clothing garments and carrying bags. Furthermore, capped rivets of this
 kind may also be used for attaching snap-button closure elements to a
 sheet-like carrier material. In this case, the rivet shank is passed
 through the carrier material and then shaped to form the attachment of the
 capped rivet. To protect the carrier material or to attach a snap-button
 closure part, it is possible to first slide a counterpart such as a lug or
 a ball forming the snap-button closure part onto the rivet shank after it
 has been passed through the carrier material and then clamp the
 counterpart against the carrier material by deforming the rivet shank.
 The deformation of the rivet shank required for fastening the capped rivet
 is usually performed by a rivet-installation machine comprising a riveting
 tool that presses against the exposed topside of the cap and pushes the
 rivet shank through the carrier material against a tool that holds the
 counterpart.
 2. Description of the Related Art
 A known capped rivet used for the installation of snap-button closure parts
 is shown in FIG. 5. This capped rivet has a cap 100 and a rivet part 110
 consisting of a rivet shank 112 and a rivet flange 114. To attach the
 rivet part to the cap, the outer rim 106 of the cap 100 is bent downward
 and inward to reach around and below the outer rim of the rivet flange
 114. To install the snap-button closure part, a riveting tool pushes
 against the exposed topside 102 of the cap 100 and forces the capped rivet
 through the carrier material and against a counteracting tool that bends
 the free end 112 of the rivet shank outwards and upwards so that the
 carrier material is clamped against a clamping surface 116 at the
 underside of the rivet flange 114. In this process, the pressure force of
 the installation tool may have the effect of deforming the cap 100,
 thereby damaging the appearance of the capped rivet.
 To solve the aforementioned problem, the capped rivet of FIG. 6 has been
 proposed. In addition to the rivet shank 112 and the rivet flange 114, the
 rivet part 110 of this capped rivet has two supporting portions 120 that
 are arranged between the rivet shank 112 and the cap 100 and extend
 approximately parallel to the inside of the cap. The supporting portions
 120 are formed by cutting out and folding back two sections of the rivet
 flange along fold lines running between the rivet shank 112 and two
 windows 118 in the rivet flange that are formed as a result of this
 process. The supporting portions 120 form a thrust-bearing surface to
 counteract the effect of the insertion tool of deflecting the cap 100
 towards the rivet shank 112 and thus to prevent the undesirable
 deformation of the cap 100.
 To further stabilize the cap, a capped rivet of the kind shown in FIG. 5 is
 proposed in DE 196 38 450 where one of the supporting portions is folded
 over the other in such a manner that the topside of one supporting part is
 in at least partially overlapping contact with the bottom side of the
 other.
 This arrangement provides a reliable means of preventing the undesirable
 deformation of the cap during the rivet-installation process. However, the
 known capped rivet has proven to be unsuitable for the attachment of
 watertight snap buttons because the windows that the supporting portions
 leave in the rivet flange form a leakage spot. In addition, the process of
 forming the supporting portions by folding back sections of the rivet
 flange and thereby opening up corresponding windows in the rivet flange
 has proven to be a problem, particularly in the case of capped rivets with
 flanges that have a stepped profile rather than a plane surface, e.g., in
 spring pin rivets. Finally, the known way of stabilizing the cap cannot be
 used if the diameter of the rivet flange is only insignificantly larger
 than the diameter of the rivet shank.
 SUMMARY OF THE INVENTION
 In view of the problems with the existing state of the art as explained
 above, the object of the present invention is to provide a capped rivet in
 which the deformation of the cap during the installation process is
 reliably prevented, in essence with no restrictions on the shape of the
 rivet flange.
 This problem is solved through a design advancement of the known capped
 rivet with the essential characteristic feature that the rivet part has a
 reinforcing element arranged at the underside of the rivet flange, i.e.,
 on the side that faces away from the inside of the cap.
 This solution is based on the observation that the only reason for the
 deformation of the cap in the installation process of conventional capped
 rivets is that the rivet flange, which serves for attaching the cap to the
 rivet part, yields to the pressure force that the riveting tool exerts on
 the topside of the cap. In the capped rivet according to the invention,
 the rivet flange is strengthened by a reinforcing element. In this manner,
 the deflection of the rivet flange, which is the actual reason for the
 deformation of the cap, is reliably prevented. By arranging the
 reinforcing element at the underside of the rivet flange (i.e., the side
 that faces away from the inside of the cap), it is also assured that the
 reinforcing element itself will not cause an undesirable deformation of
 the cap due to the effect of the pressure force applied to the cap by the
 riveting tool. The design of the reinforcing element may be independent of
 the shape of the rivet flange. Overall, this solution allows an unwanted
 deformation of the cap to be prevented no matter what shape the rivet
 flange has.
 In view of the tact that deformations of the rivet flange occur with
 particular frequency in the transition area between the rivet shank and
 the rivet flange and can cause appearance-degrading impressions of the
 upper rim of the rivet shank in the cap, it has been proven to be
 particularly practical if the reinforcing element is arranged in the area
 where the inner border of the rivet flange meets the rivet shank. With
 this arrangement, the occurrence of unwanted deformations can reliably be
 prevented even in capped rivets of the smallest rivet flange diameters
 because the reinforcing element can be formed independently of the rivet
 flange with a diameter corresponding to or smaller than the rivet flange
 diameter.
 An arrangement where the reinforcing element backs immediately against the
 underside of the rivet flange is particularly reliable in preventing
 unwanted deformations. In this, it has proven to be especially practical
 if the reinforcing element is shaped like a ring that coaxially surrounds
 the rivet shank.
 A capped rivet in accordance with the invention is particularly simple to
 produce if the reinforcing element is formed in one piece together with
 the rivet shank. This can be achieved by giving the reinforcing element
 the form of a protuberance of the rivet shank. In the last described
 embodiment of the invention, a particularly strong support of the rivet
 flange is assured if the protuberance has the shape of a reinforcing
 convex bead that is concentric to the axis of the rivet shank and has a
 first flank lying flat against the underside of the rivet flange and a
 second flank lying flat against the side of the first flank that faces
 away from the underside of the rivet flange. This arrangement provides
 between the cap and the rivet shank a supporting portion for the cap that
 is three times the material thickness of the rivet part, which is reliable
 in preventing the upper rim of the rivet shank from impressing its shape
 into the cap during the riveting process. In this manner, the reinforcing
 bead can be formed on the rivet part even with rivet flanges of the
 smallest diameters without the need for adding more stamping material to
 the rivet part. Furthermore, this particularly strong supportive backing
 of the cap allows unwanted deformations to be reliably prevented even when
 caps of a relatively thin material are used.

DETAILED DESCRIPTION OF THE INVENTION
 The cap shown in FIG. 1a comprises a dome-shaped central portion 12 with an
 exposed topside 14 and an outer rim 16 that is bent downward from the
 central portion 12 and has the approximate shape of a circular cylinder
 wall. In the embodiment of the invention according to FIG. 1, the rivet
 part 20 that is in addition required for producing the inventive capped
 rivet consists in essence of a rivet shank 22, a plane rivet flange 24,
 and a reinforcing element 26 arranged between the rivet shank 22 and the
 rivet flange 24. The reinforcing element 26 is formed integrally out of
 the same piece with the rivet shank 22 and the rivet flange 24 in the
 shape of a protruding ridge on the rivet shank 22 that extends in a circle
 around the rivet shank axis 23 and is produced as a press-formed
 reinforcing bead. The reinforcing bead has a first flank 28 that is folded
 radially outwards from the inner border of the rivet flange 24 and a
 second flank 30 that is folded radially inwards from the first flank 28
 and then continues into the rivet shank 22 that is approximately shaped
 like a circular cylinder. The upside 28a of the first flank 28 lies flat
 against the underside 25 of the rivet flange 24 (which faces away from the
 cap 10), and the upside 30a of the second flank lies flat against the
 downside 28b of the first flank. The result of this arrangement is a
 supportive backing area for the cap 10, which has three times the material
 thickness of the rivet part 20 in the area where the inner border of the
 rivet flange 24 meets the rivet shank 22.
 To manufacture a capped rivet according to the invention, the cap 10 is set
 on the rivet flange 24 of the rivet part 20, and the outer rim 16 of the
 cap 10 is folded inwards and then upwards, so that the outer rim of the
 rivet flange 24 is engaged from below by the outer rim 16 of the cap 10,
 as illustrated in FIG. 1b.
 As visualized in FIG. 2, a capped rivet according to FIG. 1 can be used,
 e.g., for attaching a snap-button closure part in the form of a snap
 eyelet 50 to a sheet-like carrier material 40. This is accomplished by
 first positioning the capped rivet on one side of the carrier material 40
 and the snap eyelet 50 on the other side. Next, by means of a riveting
 tool pressing against the topside 14 of the cap 10, the rivet shank 22 of
 the rivet part 20 is pushed through the carrier material 40 and inserted
 into a central opening 52 of the snap eyelet 50 that is bordered by a rim
 54 shaped approximately like a circular cylinder wall running parallel to
 the axis 23 of the rivet shank. As a last step, the rivet shank 22 is
 folded outwards and upwards by means of the riveting tool and a
 counteracting tool holding the eyelet 50, so that the rivet shank reaches
 around the rim 54 of the central opening 52 as illustrated in FIG. 2b.
 During the installation process, the inside 18 of the cap 10 is pushed
 against the rivet flange 24 due to the pressure force of the riveting tool
 against the topside 14 of the cap 10. However, the reinforcing element 26
 prevents the deformation of the rivet flange 24, which alone would
 otherwise cause an unwanted deformation of the cap. The reinforcing
 element 26 particularly prevents the rivet flange 24 from being bent
 downward in the area where the rivet shank 22 meets the rivet flange 24,
 which would cause an impression of the upper rim of the rivet shank to be
 stamped into the cap 10.
 As illustrated in FIG. 3, a capped rivet according to the invention can
 also be used to attach a spring pin cap in which the flange is not
 normally flat but has a shape which from the upper rim of the rivet shank
 starts out through an inner zone 24a running approximately parallel to the
 cap 10, then curves downward and continues through a transitional segment
 24b followed by an intermediate segment 24c that is again approximately
 parallel to the cap 10, and terminates in an upward-bent outer rim 24 of
 the rivet flange.
 As can further be seen in FIG. 4, the inventive improvement of the known
 capped rivet can also be realized in a case where the diameter of the
 rivet flange 24 is only insignificantly larger in comparison to the
 diameter of the rivet shank 22.
 The invention is not limited to the embodiments discussed above with
 reference to the drawing. Rather, the scope of possible design concepts
 also includes using the inventive capped rivets to attach ball-shaped,
 snap-button elements or using the capped rivets ornamental elements.
 Furthermore, the rivet flange of the inventive capped rivet may also have
 a differently shaped profile.