A method for manufacturing nails

Abstract: Nails (14) suitable for outdoor use, such as roofing nails, are formed from carbon steel wire (10) pre-coated with a metallic layer (12), which has corrosion-resistant properties, such as a zinc layer applied by pre-galvanizing the wire. Each nail (14) is formed with a shank (18) and with a head (16). The metallic layer is discontinuous in a region (22) on the head (16) of each nail (14). The nails are collated by means of collating wires (24) welded to the shanks of the nails (14). The collated nails are coiled. The coiled nails are cleaned in a cleaning bath, such as 1,1,1,trichloroethane. The cleaned nails are coated with a polymeric layer, which covers the region (22) on the head (16) of each nail (14) where the metallic layer is discontinuous, thus restoring the corrosion-resistant properties of the nails (14).

Description: This invention pertains to the manufacture of nails suitable for outdoor use, such as roofing nails, from pregalvanized or pre-chromated, carbon steel wire, wherein the nails are treated after forming to restore or enhance their corrosion resistance. Commonly, roofing nails and other nails intended for outdoor use are formed from carbon steel wire. It is necessary to protect such nails against corrosion. It is conventional to galvanize such nails, in a batch process, after such nails have been formed. It is known, moreover, to coat the galvanized nails with a polymeric material, which provides further protection against corrosion. Such a system is disclosed in EP-B-0016784. Because galvanizing in a batch process is expensive and difficult to implement, it would be highly desirable to eliminate any need to galvanize such nails after such nails have been formed, while still achieving the desired corrosion resistance for the nails. This invention provides a method for manufacturing nails suitable for outdoor use, such as roofing nails, without any need for galvanizing the nails after the nails have been formed from carbon steel wire. The desired corrosion resistance is achieved by forming the nails from carbon steel wire pre-coated with a protective, metallic layer, such as pre-galvanized, carbon steel wire, and thereafter treating the nails so as to restore the corrosion resistance of the portions of the nail no longer covered by the protective, metallic layer. Carbon steel wire coated with a metallic layer, such as pre-galvanized, carbon steel wire or pre-chromated, carbon steel wire, is provided. Pre-galvanized, carbon steel wire is preferred. Nails are formed from such wire, as by means of a known nail-forming machine. Each nail is formed with a shank and a head. While conventional forming processes are desirably economical, the nails are formed thereby in such manner that the head of each nail has a region where the protective, metallic layer is discontinuous. The region where the protective, metallic layer is discontinuous may be conveniently described as a window in the protective, metallic layer. For outdoor use, it is desirable to restore the corrosion resistant properties of the nails, particularly where the protective, metallic layer is discontinuous. To this end, at least the head of each nail is coated with a protective, polymeric layer, which covers the window in the protective, metallic layer on the head of each nail. Preferably, substantially all of each nail is coated with the protective, polymeric layer. It is preferred, moreover, to clean each nail at least where such nail is to be coated with the protective, polymeric layer, thereby to assure proper bonding and integrity of the protective, polymeric layer. In a preferred mode for carrying out the method provided by this invention, the nails are formed from pre-galvanized, carbon steel wire and are collated by means of collating wires welded to the shanks of the nails. After the collated nails are coiled, substantially all of each nail is cleaned, as mentioned above. Thereupon, substantially all of each nail is coated with a protective, polymeric layer, as mentioned above, thus fully restoring and indeed enhancing the corrosion-resistant properties of the steel wire from which the nails are formed. A particular example of a method in accordance with this invention will now be described with reference to the accompanying drawings; in which:- Figure 1 is a fragmentary, perspective view of an indeterminate length of pre-galvanized, carbon steel wire; Figure 2 is a perspective view of a roofing nail formed from such wire; Figure 3, on a reduced scale, is a fragmentary, perspective view of three such nails collated by means of two collating wires welded to their shanks; Figure 4, on a further reduced scale, is a perspective view of a coil of such collated nails; and, Figure 5 is a flow chart indicating successive steps in a preferred mode for carrying out this invention. As shown in Figure 1, an indeterminate length of pre-galvanized, carbon steel wire 10 is provided. Such wire is coated with a zinc layer 12. An indeterminate quantity of roofing nails are formed, as exemplified by the roofing nails 14 shown in Figures 2, 3, and 4. The roofing nails 14 may be advantageously formed in a nail-forming machine of a type exemplified by a Wafios™ nail-forming machine, Model No. N5 or N6. Each roofing nail 12 is formed with a head 16 and a shank 18 with a pointed tip 20. As shown in Figure 2, roofing nails typically have a head which is large in relation to the shank diameter. As the head is formed, a significant amount of material is laterally displaced to expose the underlying steel in a region shown at 22. A "window" is thus created which is at least partially devoid of corrosion protection. As shown in Figure 3, the roofing nails 14 are collated, in a known manner, by means of two collating wires 24 welded to the shanks 18 of such nails 14. The collated nails 14 are coiled, in a known manner, to form coils exemplified by the coil 26 of Figure 4. A rubber band 28 or a wire tie (not shown) is used to secure such nails 12 in such coils 26 for handling, shipping, and storage. Prior to further treatment of the nails 14 for corrosion resistance, the individual coils 26 are cleaned in a cleaning bath of a suitable composition, such as 1,1,1 trichloroethane, which is preferred. Thus, the coiled nails 14 are cleaned, along with the collating wires 24. Such cleaning step assures the effectiveness of the subsequent corrosion-resistance treatment. Since this treatment includes the application of a protective, polymeric layer, cleaning of the coils 26 assures that the protective, polymeric layer will be effectively bonded to the metallic surfaces of the nails 14. Thus, the present invention contemplates restoration and augmentation of the corrosion-resistant properties of the metal from which the nails 14 are formed. This restoration can be efficiently and economically achieved when the nails 14 are collated and coiled for use in automatic, pneumatically powered or combustion-powered nailing tools, since collated coils of nails can be readily handled and treated in accordance with the present invention. After the coiled nails 14 and the collating wires 24 have been cleaned, the individual coils 26 are coated with a polymeric layer. Thus, the coiled nails 14 are coated with the polymeric layer, which covers the region or window 22 where the zinc layer 12 is discontinuous. The individual coils 26 are coated in a coating bath of a suitable composition. A preferred composition for the coating bath is acrylic ketone base coating, as available commercially from Finnaren & Haley, Conshohocken, Pennsylvania, under #12-598. In this manner, the protective, polymeric layer acts to restore the corrosion resistance of each nail 14 at the region 22 on its head 16, and at any other portion of such nail 14 where the zinc layer 12 may have been adversely affected in the process of nail formation. At the same time, the protective, polymeric layer enhances and augments the corrosion resistance of the remaining portions of each nail 14, i.e., those portions where the zinc layer 12 remains intact. The resultant nails 14 are particularly suited for the rigors of outdoor use. Preferably, the individual coils 26 are moved into and from the cleaning bath, and into and from the coating bath.

Claims: A method for manufacturing nails suitable for outdoor use, such as roofing nails, comprising steps of (a) providing carbon steel wire coated with a protective, metallic layer, which has corrosion-resistant properties, (b) forming nails from said wire in such manner that each nail is formed with a shank and with a head having a region on the head where the protective, metallic layer is discontinuous, and (c) restoring the corrosion-resistant properties of the nails by coating at least the head of each nail with a protective, polymeric layer, which covers the region on the head of such nail where the metallic layer is discontinuous. The method of claim 1, wherein the coating step includes coating substantially all of each nail with the polymeric layer. The method of claim 1 or 2, comprising a step, which follows the forming step and precedes the coating step, of cleaning each nail at least where such nail is to be coated in the coating step. The method of claim 3, wherein the cleaning step includes cleaning substantially all of each nail and wherein the coating step includes coating substantially all of each nail with the polymeric layer. The method of any preceding claim, comprising a step, which follows the forming step and precedes the coating step, of collating the nails by means of collating wires welded to the shanks of the nails. The method of claim 5 when dependent upon claim 4, wherein the cleaning step includes cleaning the collating wires as well as the collated nails and wherein the coating step includes coating the collating wires as well as the collated nails. The method of claim 5 or 6, comprising a step, which follows the forming step and precedes the cleaning step, of coiling the collated nails.

Inventors: GABRIEL WILLIAM LEON, HEMINGER DAVID, LAT GERONIMO E, SHELTON LAWRENCE S, GABRIEL, WILLIAM LEON, HEMINGER, DAVID, LAT, GERONIMO E., SHELTON, LAWRENCE S.
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 1991
Main classification: B21G5
IPC codes: F16B15, B21G3, B21G5