Corrosion-resistant, headed fastener, such as nail for exterior applications, and manufacturing method

Abstract: A corrosion-resistant, headed fastener, such as a nail (10) for exterior applications, is made from a carbon steel wire (W) pre-coated with a protective, metallic layer (L) having corrosion-resistant properties, the protective, metallic layer (L) being discontinuous at a region (18) on a leading end of the pre-coated wire (W). After at least part of a protective, metallic cap (C) having corrosion-resistant properties is disposed near the leading end of the pre-coated wire (W), at least part of the protective, metallic cap (C) is welded to the leading end of the pre-coated wire (W) so as to cover the region (18) where the protective, metallic layer (L) is discontinuous, by impact welding, as a fastener (10) is formed from the pre-coated wire (W) in such manner that the fastener (10) is formed with a shank (12) and with a head (16), which is formed by deformation of the leading end. The welded part of the protective, metallic cap (C) provides the fastener (10) with corrosion resistance at the region (18) where the protective, metallic layer (L) is discontinuous, and the protective, metallic layer (L) provides the fastener (10) with corrosion resistance elsewhere. The protective, metallic layer (L) is made from chromium, nickel, zinc, aluminum, or an alloy comprising zinc and aluminum, preferably from zinc or such an alloy. The protective, metallic cap (C) is made from chromium, nickel, zinc, aluminum, or an alloy comprising zinc and aluminum, preferably aluminum, which can be visually differentiated from zinc or such an alloy.

Description: Technical Field of the Invention This invention pertains to manufacture of a fastener having a head and a shank, such as a siding, decking, fencing, or roofing nail, from a carbon steel wire pre-coated with a protective, metallic layer having corrosion-resistant properties, such as pre-galvanized, carbon steel wire. This invention employs a protective, metallic cap, which provides the fastener with corrosion resistance at an area where the protective, metallic layer is discontinuous on the head of the fastener. Background of the Invention Commonly, siding, decking, fencing, or roofing nails and other fasteners intended for outdoor use or other exterior applications are made from carbon steel wire. It is necessary to protect such fasteners against corrosion. It is conventional to galvanize such fasteners, in a batch process, after such fasteners have been formed. It is known, moreover, to coat the galvanized nails with a polymeric material, which provides further protection against corrosion. As disclosed in Lat et al . U.S. Patent No. 5,033,181, it is known to make such fasteners from carbon steel wire coated with a protective, metallic layer having corrosion-resistant properties, such as pre-galvanized, carbon steel wire or pre-chromated, carbon steel wire. As disclosed therein, the protective, metallic layer is discontinuous and the carbon steel of the wire is exposed at a region on a leading end of the wire, on which end a head of such a fastener is formed. As disclosed in the Lat et al. patent, the head of each fastener is coated with a protective, polymeric layer covering the region where the protective, metallic layer is discontinuous, so as to restore the corrosion-resistant properties of such fastener. It is known from the US-A-1 867 353 a method for making wheatherproof nails which consists in providing a headed nail having a plurality of lugs on the underside of the head and enclosing all of the head and all surfaces of said lugs except the buttom thereof with a cap of softer metal. The cap is made by placing a mass of cap material upon the top of the nail head in a recess and applying pressure to the said mass of metal to force it about the nail head and to enclose the nail head. It is an object of the present invention to provide an improved method for manufacturing a corrosion-resistant headed fastener. The object is achieved by the method according to claim 1, comprising the steps of providing a carbon steel wire pre-coated with a protective metallic layer having corrosion resistant properties wherein said protective metallic layer is discontinuous at the region defined upon a leading end portion of the pre-coated wire and disposing a protective metallic cap having corrosion-resistant properties near the leading end portion of the wire. The protective metallic cap is secured upon the leading end portion of the pre-coated wire so as to cover the region of the leading end portion of the pre-coated wire at which the protective metallic layer is discontinuous while deforming the leading end portion of the pre-coated wire. For purposes of this invention, carbon steel wire pre-chromated (e.g. after having been pre-galvanized) is regarded as being pre-coated with a protective, metallic layer having corrosion-resistant properties. Moreover, sacrificial properties are regarded as corrosion-resistant properties. Desirably, the protective, metallic layer and the protective, metallic cap respectively are made from chromium, nickel, zinc, aluminum, or an alloy comprising zinc and aluminum. Preferably, the protective, metallic layer is made from zinc or an alloy comprising zinc and aluminum, and the protective, metallic cap is made from aluminum. Thus, the protective, metallic cap provides the fastener with corrosion resistance at the region of the head where the protective, metallic layer is discontinuous. Also, the protective, metallic layer provides the fastener with corrosion resistance elsewhere. Moreover, this invention provides an improved fastener, which can be advantageously manufactured by the improved method summarized above. These and other objects, features, and advantages of this invention are evident from the following description of a preferred mode for carrying out this invention, with reference to the accompanying drawings. Brief Description of the Drawings Figure 1 is a perspective view of a nail for exterior applications, as manufactured by the improved method summarized above. Figure 2, on a greatly enlarged scale, is an elevational view of the head of the nail shown in Figure 1. Figure 3 is a schematic view illustrating the preferred mode for carrying out the improved method summarized above. Figure 4 is an elevational view taken along line 4―4 of Figure 3, in a direction indicated by arrows. Figure 5 is a sectional view taken along line 5―5 of Figure 3, in a direction indicated by arrows. In Figures 4 and 5, thickness of a coating layer is exaggerated for illustrative purposes. Detailed Description of Preferred Mode As shown in Figures 1 and 2, and as manufactured by the improved method, a nail 10 for exterior applications has a shank 12 formed with a pointed end 14 and a head 16 formed on the opposite end of the shank 12. As shown in Figures 3, 4, and 5, the nail 10 is made from carbon steel wire W pre-coated with a protective, metallic layer L having corrosion-resistant properties. As manufactured, the nail 10 remains coated with the protective, metallic layer L along the shank 12, except possibly at the pointed end 14 where the protective, metallic layer L is discontinuous, and on all surfaces of the head 16, except at a region 18 on the head 16 where the protective, metallic layer L is discontinuous. However, at least part of a protective, metallic cap C having corrosion-resistant properties is welded to the head 16 so as to cover the region 18 on the head 16 where the protective, metallic layer L is discontinuous. The protective, metallic layer L provides the nail 10 with corrosion resistance along the shank 12, except possibly at the pointed end 14 where the protective, metallic layer L is discontinuous, and on the head 16, except at the region 18 on the head 16 where the protective, metallic layer L is discontinuous. The protective, metallic cap C, which has corrosion-resistant properties, provides the nail 10 with corrosion resistance at the region 18 on the head 16 where the protective, metallic layer L is discontinuous. Desirably, the protective, metallic layer L is made from chromium, nickel, zinc, aluminum, or an alloy comprising zinc and aluminum. Preferably, the protective, metallic layer L is made from zinc or an alloy comprising zinc and aluminum. Galfan™ alloy comprised of approximately 95% zinc by weight, approximately 5% aluminum by weight, and trace amounts of rare earths, manufactured by or pursuant to specifications of International Lead Zinc Research Organization of New York, New York, and available commercially from Indiana Steel and Wire Corporation of Muncie, Indiana, is a most preferred alloy for the protective, metallic layer L. Desirably, the protective, metallic cap C is made from chromium, nickel, zinc, aluminum, or an alloy comprising zinc and aluminum. Preferably, the protective, metallic cap C is made from aluminum. As shown, the protective, metallic cap C is severed from an auxiliary wire A, although an auxiliary foil (not shown) may be instead used. As shown schematically in Figure 3, the nail 10 can be advantageously manufactured in a conventional nail-forming machine, such as a Wafios™ nail-forming machine, Model No. N5 or Model No. N6, which has been adapted suitably. The machine includes a mechanism M for gripping the pre-coated wire W, which was fed incrementally by another mechanism (not shown) of the machine, and a header H for forming the head 16 of the nail 10 on a leading end 20 of the wire W. Also, the machine has been adapted to feed the auxiliary wire A. In the nail-forming machine, the pre-coated wire W is fed incrementally by the mechanism until the leading end 20 of the wire W is extended for a suitable distance. As shown in Figure 4, the carbon steel S of the wire W is exposed at the leading end 20 of the wire. Also, the auxiliary wire A is fed incrementally until a leading end 20 of the auxiliary wire A is disposed near the leading end 20 of the pre-coated wire W, between the header H and the leading end 20 of the pre-coated wire W. Next, the header H is moved toward the leading end 20 of the pre-coated wire W in such manner that an end part of the auxiliary wire A is welded to the leading end 20 of the pre-coated wire W by impact welding, which deforms the welded part and which severs the welded part from the auxiliary wire A remaining in the nail-forming machine, whereby the welded part provides the protective, metallic cap C, which covers at least the region 18 where the protective, metallic layer L is discontinuous. Furthermore, the leading end 20 of the pre-coated wire W is deformed simultaneously and in a known manner to form the head 16 of the nail 10. The protective, metallic cap C may cover more of the head 16, beyond the region 18 where the protective, metallic layer L is discontinuous. In further steps outside the scope of this invention, the nail-forming machine forms the pointed end 14 on the nail 10 and severs the nail 10 from the pre-coated wire W remaining in the nail-forming machine. If the protective, metallic layer L is made from zinc or an alloy comprising zinc and aluminum, such as Galfan™ alloy discussed above, and if the protective, metallic cap C is made from aluminum, the protective, metallic cap C can be visually differentiated from the protective, metallic layer L for purposes of quality inspection.

Claims: A method for manufacturing a corrosion-resistant headed fastener, comprising the steps of: providing a carbon steel wire (W) pre-coated with a protective, metallic layer (L) having corrosion-resistant properties wherein said protective, metallic layer (L) is not present and is therefore discontinuous at a region (18) defined upon a leading end portion (20) of said pre-coated wire (W), characterized in disposing a protective, metallic cap (C) having corrosion-resistant properties near said leading end portion (20) of said pre-coated wire (W); and securing said protective, metallic cap (C) upon said leading end portion (20) of said pre-coated wire (W), so as to cover said region (18) of said leading end portion (20) of said pre-coated wire (20) at which said protective, metallic layer (L) is discontinuous, while deforming said leading end portion (20) of said pre-coated wire (W), so as to form a fastener from said pre-coated wire (W) which has a shank portion (12) and a head portion (16) comprising said region (18) at which said protective, metallic layer (L) is not present. The method of claim 1, characterized in that the securing step comprises welding said protective, metallic cap (C) to said leading end portion (20) of said pre-coated wire (W). The method of claim 2, characterized in that said welding step is performed by impact welding simultaneously with said deformation of said leading end portion (20) of said pre-coated wire (W) so as to form said head portion (16). The method of one of claims 1 to 3, characterized in that said protective, metallic layer (L) comprises a material selected from the group of chromium, nickel, zinc, aluminium, or an alloy comprising zinc and aluminium. The method of claim 4, characterized in that said alloy comprises approxymately 95% zinc by weight and approximately 5% aluminium by weight. The method of one of claims 1 to 5, characterized in that said protective, metallic cap (C) is fabricated from a material which is selected from the group of chromium, nickel, zinc, aluminium, or an alloy comprising zinc and aluminium. A corrosion-resistant, headed fastener, comprising: a shank portion (12); a head portion (16) at one end of said shank portion (12); a carbon steel wire (W) pre-coated with a protective, metallic layer (L) having corrosion-resistant properties wherein said protective, metallic layer (L) is discontinuous at a substantially central region (18) of said head portion (16) which substantially corresponds to said carbon steel wire (W), characterized in that protective, metallic cap (C) means are provided having corrosion-resistant properties, for being fixedly secured to said head portion (16) during formation of said head portion (16) by deformation of one end of said pre-coated carbon steel wire (W) so as to cover said substantially central region (18) of said head portion (16) where said protective metallic layer (L) is discontinuous. The fastener of claim 7, characterized in that said protective, metallic cap (C) is welded to said head portion (16) so as to cover said substantially central region (18) of said head portion (16) where said protective, metallic layer (L) is discontinuous. The fastener of claims 7 or 8, characterized in that said protective, metallic layer (L) is fabricated from a material selected from the group of chromium, nickel, zinc, aluminium, or an alloy comprising zinc and aluminium. The fastener of on of claim 9, characterized in that said alloy comprises approximately 95% zinc by weight and approximately 5% aluminium by weight. The fastener of one of claims 7 to 10, characterized in that said protective, metallic cap (C) is fabricated from a material selected from the group of chromium, nickel, zinc, aluminium or an alloy comprising zinc and aluminium.

Inventors: LAT GERONIMO E, LAT, GERONIMO E.
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 1996
Main classification: B21G5
IPC codes: F16B15, B21G3, B21G5