Self-attaching female fastener elements and method of forming same |
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申请号 | US10546412 | 申请日 | 2003-11-24 | 公开(公告)号 | US20060252560A1 | 公开(公告)日 | 2006-11-09 |
申请人 | Harold Ladouceur; John Parker; | 发明人 | Harold Ladouceur; John Parker; | ||||
摘要 | The method of forming self-attaching female fasteners by rolling a continuous metal strip including a central pilot portion having parallel sides and flange portions on opposed sides, severing at least the pilot portion and cold forming the rectangular pilot portion into a cylindrical end portion. Wing-shaped radial portions are formed in the pilot portion which may be severed or remain for anti-rotation features. The strip may remain continuous, wherein the severed pilot portions are spread and the flange portions are thinned or the strip may be severed into discreet fasteners. The female fasteners thus include generally cylindrical pilot portions and rectangular flange portions which may include rolled grooves. | ||||||
权利要求 | |||||||
说明书全文 | The present invention relates to self-attaching female fasteners and a method of forming female fastener elements utilizing a combination of rolling and cold header techniques to form an improved fastener element having a rectangular body portion and an integral central projecting pilot portion having a generally cylindrical end portion. Self-attaching fasteners, including pierce and clinch nuts as disclosed in U.S. Pat. Nos. 2,707,322 and 3,648,747, assigned to the predecessor in interest of the assignee of this application, have been commercially successful in mass production applications, such as utilized by the automotive and appliance industries. The self-attaching female fastener elements disclosed in these patents are formed by rolling techniques including rolling a continuous strip of metal having the desired cross-section of the female fastener element including a rectangular central pilot portion and flange portions on opposed sides of the pilot portion. The pilot portion is then pierced through the end face, forming a bore of the fastener element, and the strip is then cut or chopped to length and the bore may then be internally threaded, as required. Reference is also made to U.S. Pat. Nos. 3,775,795 and 3,999,659, which disclose a method of forming a continuous strip of female fastener elements of the type disclosed in the above-referenced U.S. Pat. No. 2,707,322, wherein the rolled strip is only partially severed by transverse slots punched through the continuous pilot portion and a portion of the flanges, such that the strip may be severed in the installation head during installation of the female fastener elements in a panel. As will be understood by those skilled in this art, the pilot portion formed by rolling a continuous strip must include a rectangular pilot portion having a rectangular end face. The rectangular end face of the self-attaching fastener is then utilized to pierce a rectangular opening in a panel and the pilot portion is then received through the pierced panel opening and attached to the panel by a die member or die button, as described below. Alternatively, the rectangular pilot portion is received through a preformed rectangular opening in the panel where the self- attaching fastener element is utilized as a clinch nut. Self-attaching fastener elements of the type disclosed in the above-referenced patents are typically attached in a panel in a die press, wherein the upper die shoe or die platen includes an installation head, which receives the self- attaching fasteners and having a reciprocating plunger, and the lower die shoe or die platen includes a die member or die button which supports the panel during installation and installs the nut in the panel with each stroke of the die press. Because the panel may be simultaneously formed during installation of the self-attaching female fastener element, this method of installation is preferred in mass production applications. However, there are certain applications where a generally round or cylindrical pilot portion is preferred to avoid stress risers at the sharp corners of the rectangular panel opening. However, pierce or clinch nuts having a generally cylindrical or circular pilot portion are presently manufactured only by conventional cold forming or cold heading techniques. It would, however, be desirable to form self-attaching female fastener elements by continuously rolling a metal wire, thereby utilizing the advantages of this technology, but resulting in a self-attaching female fastener having a generally circular or cylindrical pilot portion, thereby achieving one of the advantages of a female fastener element formed by conventional cold heading techniques, including the elimination of stress risers. Further, self-attaching fasteners formed by cold forming are more expensive. The method of forming self-attaching female fastener elements of this invention achieves these advantages and the resultant female fastener element has advantages over the prior art as now described. The method of forming self-attaching female fasteners of this invention begins with rolling a continuous metal strip from a wire having a cross- section of the self-attaching fasteners to be formed including a continuous projecting pilot portion having an end face and continuous flange portions on opposed sides of the pilot portion. The method of this invention then includes severing at least the continuous pilot portion thereby forming spaced generally rectangular pilot portions. In one method of forming self-attaching female fastener elements of this invention, the method includes severing the strip through the pilot and flange portions, thereby forming discreet fastener segments each having rectangular pilot portions and flange portions on opposed sides of the pilot portions. In an alternative embodiment of the method of this invention, the continuous pilot portion of the strip is pierced or lanced through the pilot portion only, forming spaced generally rectangular pilot portions, and a continuous portion on opposed sides of the pilot portion, thereby forming integral carrier portions. The method of this invention then includes deforming the corners of the end portion of the rectangular pilot portions outwardly and simultaneously deforming a top end portion of the pilot portion into a generally cylindrical form. In a preferred embodiment, the generally cylindrical end portion is rolled by a die wheel having generally cylindrical recesses in a continuous operation. In the disclosed embodiment of the method of forming self-attaching female fastener elements of this invention, the corners of the pilot portion are deformed generally radially, forming four integral wing-shaped portions which are deformed against the flange portions. The wing-shaped portions may then be either trimmed or removed, leaving a generally cylindrical pilot portion, or the wing-shaped portions may remain with the pilot portion forming additional anti-rotation means following installation of the fastener element in a panel. The method of this invention further includes piercing an opening through the pilot portions, which forms the bore of the female fastener elements. The opening may be piercing through the pilot portions of the female fastener elements either while the fastener elements remain in a strip or following severing of the strip into discreet fastener elements. The final step is tapping the bore, forming a threaded bore, if desired for the application. In the embodiment of the method of forming self-attaching female fastener elements of this invention, wherein only the pilot portion is lanced and the fastener elements remain in a strip, as described above, one preferred method includes spreading the fastener elements in the strip. In this disclosed embodiment, the female fastener elements are spread in the strip by rolling and thinning the flange portions, forming integral carrier portions and eliminating a straightening operation as disclosed in the above-referenced U.S. Pat. Nos. 3,775,791 and 3,999,659. Where the female fastener elements are chopped from the strip, forming discreet fastener elements as described above, the fastener elements may be reconnected by frangible connector elements, such as wires, as disclosed in U.S. Pat. No. 3,845,860, also assigned to the predecessor in interest of the assignee of this application. One embodiment of the female fastener elements formed by the method of this invention includes a rectangular body portion including a central projecting pilot portion having an end face and flange portions on opposed sides of the pilot portion, which may be formed by the rolling method described above, wherein the pilot portions include a generally cylindrical end portion and integral wing-shaped portions as described above. The wing-shaped portions provide additional support for the panel, following installation, and further anti-rotation means. As will now be understood, the method of forming self-attaching female fastener elements of this invention thus combines the advantages of the rolling process of forming female fastener elements known in the prior art, but includes a generally cylindrical pilot portion formed by cold forming or cold heading techniques. Other advantages and meritorious features of the method of forming self- attaching female fastener elements and the improved female fastener elements of this invention will be more fully understood from the following description of the preferred embodiments, the appended claims and the drawings, a brief description of which follows. The nut section may then be chopped or severed from the nut strip 26 as shown at 26a in The first cold forming step is to deform the end portion or end face 30 of the rectangular pilot portion radially outwardly to form a cylindrical end portion 38 as shown in FIGS. 3 to 15 illustrate an alternative embodiment of the method of this invention, wherein the self-attaching female fastener elements are retained in an integral strip for installation as described below. The first cold forming step in forming the female fastener elements from the strip 46 is to pierce or lance openings 58 through the pilot portion 48 of the strip. As best shown in The next step in the method disclosed in FIGS. 3 to 15 is spacing the cylindrical pilot portions 68 and reducing the thickness of the carrier portion as best disclosed in The next step in this alternative disclosed method of this invention includes rolling grooves 78 into the opposed sides of the pilot portion as shown in The self-attaching female fastener elements may then be installed in a panel by conventional means as shown, for example in As will be understood by those skilled in this art, various modifications may be made to the self-attaching female fastener elements and method of forming such elements of this invention within the purview of the appended claims. For example, the integral wing-shaped portions 40 of the female fastener element illustrated in |