Patent Grant
6907647
The invention pertains first to an eyelet of the type indicated in the introductory clause of claim 1. There are two-part eyelets, the first part of which consists of an eyelet, the second consisting of a disk. These two parts are located on opposite sides of the carrier web and clamp the carrier web between them in sandwich-like fashion.
One-part eyelets are also known, however, which do not have a disk part and which thus consist only of an eyelet part (U.S. Pat. No. 2,107,375 A). Pleats are formed in the end of the neck of the eyelet part, as a result of which radial expansions are created between axial projections. When the eyelet part is flanged over, a C-shaped profile is formed between the neck and the plate, the radial expansions being supported against the rear surface of the carrier web. The carrier web thus extends radially into the interior of the C-shaped profile. This known eyelet has limited resistance to pull-out.
In connection with a single-part eyelet comprising of an eyelet collar with a semi-circular profile and an eyelet neck with uniformly circumferentially extending V-shaped cross-section on the end face of the neck, it is known (EP 0 673611 A1) to close the resulting C-shaped profile to such an extent that the carrier web is clamped in the remaining gap between the outer edge of the eyelet collar and the end face of the eyelet neck. The semi-circular interior of the eyelet collar is divided by a peripheral annular rib into an inner and an outer groove wherein the annular rib over portions thereof carries pointed tips. The transition area between the eyelet neck and the eyelet collar is provided with conical stabilizing ribs which prevent flanging of these areas. After flanging of the residual length of the neck, the end face of the eyelet neck is aligned only with the outer groove of the eyelet collar. In the interior of the C-shaped profile, a labyrinth for the carrier web is provided. The tips of the annular rib appear to effect a holding action securing the carrier web against rotation but the tearing-out stability of the carrier web is insufficient because the topside of the carrier web is contacted only by the outer edge of the eyelet collar and the bottom side of the carrier web is only contacted by the end face of the eyelet neck.
Moreover, for a single-part eyelet it is also known (DE 299 03 124 U1) to cut the free end of the neck in the flanging tool into individual tab-shaped securing elements and to bend them radially outwardly. For this purpose, the bottom part of the flanging tool is provided with a circular arrangement of widening depressions which are separated from one another by cutting edges that point toward the top part of the tool. After attachment to the carrier web, the securing elements form, viewed in cross-section, together with the eyelet disk a V-shaped folded product. The carrier web which is clamped between the legs of the V is secured only insufficiently in this folded product.
The invention is based, first, on the task of developing an inexpensive, quickly installable eyelet of the type indicated in the introductory clause of claim 1, which, after it has been attached to the carrier web, is characterized by high resistance to tear-out. This is achieved according to the invention by the measures cited in claim 1, to which the following meaning attaches:
In the invention, a ring-shaped profile is formed which extends across more that a complete circle because practically the entire length of the neck is rolled spirally into the interior of the ring-shaped profile when the neck is flanged over; the projections provided at the end of the neck are included in the formation of the spiral. As a result, special compression points, which provide very high resistance to the tensile stresses exerted on the carrier web, are produced on the gripped carrier web inside the spirally rolled-in ring-shaped profile. These compression points are formed because the projections on the spirally rolled-in ring-shaped, flanged-over neck press an area of the carrier web surrounding the hole against opposite support surfaces, which, in the case of the present ring-shaped profile, are formed by the plate or by the transition between the plate and the neck of the eyelet part. The carrier web adapts with a ring-segment shape to the ring-shaped profile and the rolled-in projections on the neck and is compressed in a sandwich-like fashion between the ring surfaces and the spiral surfaces. The carrier web extends beyond the compression points to the edge of the hole in the interior of the ring-shaped profile. The projections on the spirally shaped rolled-in end pieces of the neck point toward the interior of the ring-shaped profile and are oriented counter to the tensile loads occurring during use of the carrier web. In front of these real compression points a step-like increase of the web material takes place which upon stresses acting on the carrier web actually improve the grip at the compression points. The spiral rolling of the end piece of the neck provides a very clean riveting action without having to fear injuries being inflicted on the user. The eyelet according to the invention is much more resistant to pull-out than the state of the art indicated above.
In comparison with the much more complicated, two-part eyelets, the eyelet according to the invention provides a surprisingly high resistance to tear-out; it is, in fact, 30-75% stronger. This strength is obtained precisely in the case of the previously so difficult to handle flexible or stretchable carrier webs, which could not be processed at all with one-part eyelets in the past. Because of the one-piece design of the invention, the disk part is eliminated, which saves material, warehouse costs, freight costs, and handling during the installation process. Because the one-part eyelet part according to the invention can be installed rapidly, the cost of installing the eyelet is reduced. The neck of the eyelet part according to the invention must be long enough to make it possible for the desired ring-shaped profile to be obtained during the flanging operation. The thickness of the carrier web, of course, must also be taken into account. The only other step to be taken is to produce the axial or radial projections at the free end of the neck, which can be done in various ways.
One possibility is to form the projections by making radial holes in the tubular wall of the neck. When the neck is flanged over, these radial projections penetrate into the edge area of the material around the hole in the carrier web being gripped, where they dig themselves in and produce the compression points against the opposing support surface on the plate. The other possibility, namely, forming projections which proceed in the axial direction, is easier to manufacture, however. The pronged or wave-like terminal edge of the neck mentioned for this purpose in claim 2 is suitable. In this case, the entire edge of the neck has a continuous profile and does not, as in the state of the art mentioned above, show individual projections spaced a certain distance apart. When the ring-shaped profile is formed, both the neck and its projections are deformed jointly according to the invention. When the ring-shaped profile is produced during the flanging-over operation, the prong digs into the web material, and there is therefore not just a clamping effect between the prong and the opposing support surface of the plate but also a positive connection, which is established between the prong and the carrier web. The greater the tensile force exerted on the carrier web, the greater the strength with which the prongs dig into the web. This explains the surprisingly high resistance of the eyelet according to the invention to tear-out.
The invention also pertains to a device for installing the eyelet according to the invention. In the case of the known device (U.S. Pat. No. 1,838,973 A), which is intended for two-part eyelets, the thrust ring in the lower tool projects beyond the cutting edge provided here. The upper tool has an axially movable, central insert with a bore; this insert projects out axially beyond the adjacent surfaces of the upper tool. During the working stroke of the two tools, the carrier web is pushed by the central insert of the upper tool into the thrust ring before the central insert meets the cutting edge of the lower tool to cut the hole in the carrier web. The attachment of the carrier web to this two-part eyelet, which consists of both an eyelet part and the previously mentioned disk part, is therefore unattractive, because folds are formed in the carrier web.
The invention is therefore also based on the task of developing a device which can be used to attach the one-part eyelet cited in claim 1 more attractively to the carrier web and with greater resistance to tear-out. This is accomplished according to the invention by the features cited in the characterizing clause of claim 9, to which the following special meaning attaches:
In the invention, the upper tool is provided with a counter-thrust ring to work together with the thrust ring in the lower tool, the counter-thrust ring being subjected to a force acting toward the lower tool. It is recommended here, in accordance with claim 10, that these two rings be provided with opposing beveled surfaces. When the two tools perform their stroke, the carrier web is tensioned between the two rings, and the beveled surfaces exert an additional stretching and smoothing-out effect on the carrier web. During the following flanging operation of the one-part eyelet, the carrier web is kept flat and smooth, which ensures that the eyelet is attached ideally to the carrier web. The tensioning of the web minimizes the amount of material which is pulled into the eyelet. This has the result that spacing of the eyelets can be maintained with precision, and positional deviations can be limited even in the case of large tarps.
Additional measures and advantages of the invention can be derived from the subclaims, from the following description, and from the drawings. The drawings illustrate the invention on the basis of an exemplary embodiment:
As
As
The eyelet part 10 can be divided into a plate 11 with a curved cross section, extending essentially in the radial direction, and a tubular neck 12, extending in the axial direction. To increase the dimensional stability of the eyelet and to make it easier to flange over the neck 12 into a ring, as will be described in greater detail below, the plate 11 is provided with a curved profile 13. As a result, an especially conspicuous arc-shaped transition 14 is obtained between the plate 11 and the neck 12. The neck is provided at its free end 15 with axial projections 16, which, therefore, extend in the direction of the neck 12. These projections consist in the present case of a curved, pronged terminal edge 17, as can be seen in FIG. 5. This edge has the following appearance.
The tips 17 of the prongs are provided with convexly rounded areas 27, whereas the gaps 18 between the prongs have concavely rounded areas 28. As a result, the pronged profile 19 acquires a wave-like form. The course of the waves is asymmetric. That is, the radius of curvature of the rounded areas 27 of the prong tips 17 is smaller than that of the rounded areas 28 of the gaps between the prongs.
This eyelet part 17 is attached to the carrier web 20 by the device 30, shown in FIG. 6. The device 30 consists of essentially five parts, which are able to move in the axial direction with respect to each other in a chronological sequence. These parts include, first, the bottom tool 32, which, in the present case, remains at rest and which carries a thrust ring 34, which is able to move passively in the axial direction with respect to the lower tool. In addition, the device 30 also includes an upper tool 31, which is able to move actively with respect to the lower tool 32 and which has a central, coaxial insert 33. This insert is also able to move passively in the axial direction with respect to the upper tool 31. Finally, the upper tool 31 is enclosed circumferentially by a counter-thrust ring 54, which is also able to move passively in the axial direction. The central insert 33 and the counter-thrust ring 54 are subjected to load in the direction of the force arrows 35 and 55 toward the lower tool 32, whereas the thrust ring 34 in the lower tool 32, in mirror-image fashion, is acted upon by a group of springs 56 acting in the direction of the force arrow 36 toward the upper tool 31, these springs being installed in axial holes in the bottom tool 32. The springs 56 are designed as helical springs, and pins 57 seated on the thrust ring 34 fit into the interior of the helical turns. The tool assembly 31, 33, 54 on the one side and the tool assembly 32, 34 on the other are able to move up and down with respect to each other, as indicated by the motion arrow 37 of the upper tool assembly 31, 33, 54.
The counter-thrust ring 54 is guided on the circumferential surface 63 of the upper tool 31. The force 55 exerted by the counter-thrust ring 54 is produced by a compression spring 64, which is supported between a flank of a circumferential flange 65 on the upper tool 31 and the contact surface of a cutaway portion 66 of the counter-thrust ring 54. The extent to which the counter-thrust ring 54 extends outward is determined by end stops. These consist in the present case of the heads 67 of a group of guide rods 68, the length of which can be adjusted by the use of a threaded section 69 and a lock nut 71. When in the resting state, the head 67 of the rod is supported on the top surface of the flange 65. As a result, the desired extension 70 of the counter-thrust ring 54 relative to the upper tool 31 is determined.
After the eyelet part 10 has been inserted, the end of the neck 20 is supported on the circumferential surface of the central insert 33. The central insert 33 is provided with a flat end surface 43. To secure the eyelet part in position in the tools 31, 33, a retaining element 44, which, in the present case, consists of a radially spring-loaded pin, is used, which is located in the circumferential area of the central insert 33.
The carrier web 20 is laid between the two tool parts 31, 32; at this point, the web is still unperforated. The previously mentioned springs 56 hold the thrust ring 34 in a defined starting position, shown in FIG. 6. At maximum stroke of the tool, the defining-upper surface 45 of the thrust ring 34 is located above or preferably at the same level as a cutting edge 42 provided on the cutting tool 32. As a result, a horizontal support plane 60 for the carrier web 20, illustrated in broken line in
During the downstroke 37 of the upper tool assembly 31, 33, 54, the leading counter-thrust ring 54 makes contact first with the carrier web 20 lying on top of the thrust ring 34. The two rings 34, 54 are provided with bevels 58, 59, which are essentially parallel to each other and which grip the carrier web 20 between them, as a result of which the carrier web 20 is initially put under a certain amount of tension. The bevel 58 of the thrust ring 34 forms an acute angle 61 to the support plane 60, shown in dash-dot line in
Then the central insert 33, under the force being exerted by the press plunger, makes contact with the upward-facing, visible side 23 of the carrier web 20, thus pressing it against the cutting edge 42 of the lower tool 32, which is resting against the bottom surface 24 of the carrier web. As a result, a circular hole is punched out of the carrier web 20. The radius 46 of the hole determined by the cutting edge 42 is smaller than the radius 26 of the neck 12 of the eyelet indicated at 26 in FIG. 6.
When the upper tool 31 is lowered further in the direction of the stroke arrow 37, the carrier web 20 is pulled even tighter between two bevels 58, 59 of the two rings 34, 54. The neck 12 of the eyelet part 10 continues to pass through the hole thus formed and into the lower tool until the plate 11 of the eyelet part 10 arrives at the thrust ring 34, the carrier web 20 ending up between the plate and the ring. During this downward movement 37, the upper tool 31 overcomes the elastic force 36 being exerted from underneath by the thrust ring 34, and the neck 12 of the eyelet and its axial projections 16 are flanged over against the flanging profile 47 of the lower tool 32. The elastic force 54 of the thrust ring 34 acting from above is weaker than the ejection force 36 acting from below on the thrust ring 34. As in the case of the upper tool 31, the lower tool 32 also has an insert 32′, positioned in the axial area, which carries the defining flanging-over profile 47. This flanging-over profile 47 wears out after prolonged use. At that point, it necessary merely to replace this insert 32′.
During the flanging operation, the special riveting relationships shown in
When the eyelet part installed on the carrier web 20 is properly used, the tensile forces indicated by the force arrows 52 in
| Number | Date | Country | Kind |
|---|---|---|---|
| 100 39 462 | Aug 2000 | DE | national |
| 201 04 102 U | Mar 2001 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP01/06316 | 6/2/2001 | WO | 00 | 1/24/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO02/13646 | 2/21/2002 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1565523 | Stuart | Dec 1925 | A |
| 1838973 | Wilder | Dec 1931 | A |
| 2101060 | Gookin | Dec 1937 | A |
| 2107375 | Gookin | Feb 1938 | A |
| 2143087 | Rau | Jan 1939 | A |
| 2901800 | Koehl | Sep 1959 | A |
| 3328854 | Tombari | Jul 1967 | A |
| 4479287 | Asaka | Oct 1984 | A |
| 4890362 | Odajima et al. | Jan 1990 | A |
| 5588191 | Slbeck | Dec 1996 | A |
| Number | Date | Country |
|---|---|---|
| 299 03 124 | Jun 1999 | DE |
| 0673611 | Sep 1995 | EP |
| 1577474 | Jun 1969 | FR |
| Number | Date | Country | |
|---|---|---|---|
| 20030167610 A1 | Sep 2003 | US |
