Method for drawing wire for staples

There is a method for the production of stapling wire for use in the graphic industry for stapling periodicals, brochures and the like. A drawable wire is drawn from an initial material (A) having a low carbon content which is drawn in a first drawing step from a starting diameter (D 1 ) to a temporary diameter (D 2 ). This wire is drawn in a second drawing step from the temporary diameter (D 2 ) to a final diameter (D 3 ), so that a stapling wire results. This process provides a simple and economical method for producing stapling wire, wherein stapling wire is produced to fulfill the requirements of the graphic industry. In addition, this second drawing step is performed without previously subjecting the wire to a heat treatment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings, FIG. 1 shows the prior art process for the production of stapling wire which is intended for use in the graphic industry for stapling of periodicals and the like. A drawable wire serves as the starting material A, which possibly has been previously mechanically and/or chemically descaled. Subsequently, the starting material A is drawn in a first drawing stage B with multiple drawing dies to a smaller intermediate diameter. The drawn wire is then coiled up in stage C. Following this step, the wire is then annealed in stage D, i.e. subjected to a heat treatment. Immediately following this step, the wire is galvanized in stage E. In another known method, not shown, steps D and E can also be separate steps, between which the wire is again coiled up. Following step E the wire is coiled up again in step F and then supplied to the second drawing step G, where the wire is redrawn to the desired final dimensions, so that in step H, a coiled-up stapling wire h results with the desired final diameter. The method according to the invention is schematically illustrated in FIG. 2 . A wire with good drawing properties having a low carbon content serves as the starting material 1 , which, is first cleaned for descaling in a cleaning device. This wire is supplied to a first drawing step 2 . The wire of the starting material 1 has a starting diameter D 1 . In the first drawing step 2 , the wire of the starting material 1 is drawn to a wire with an intermediate diameter D 2 . For this purpose, there is a first drawing device with multiple drawing dies having smaller and smaller diameters. While the starting diameter D 1 of the present wire is approximately 5.5 mm, after the first drawing step 2 , the wire has an intermediate diameter which typically varies between 1.4 mm and 3.2 mm. The wire is then coiled up in step 3 via an appropriate coiling device. In step 4 , the wire is coated with an appropriate coating device. In the present case, the wire is galvanized for surface finish. In principle, it is also possible to perform steps 2 and 4 in one line, without coiling in step 3 . In the embodiment illustrated, the previously coiled wire is uncoiled via an appropriate coiling device and fed through an appropriate bath of the coating device. This wire is then electrolytically galvanized. In principle, hot galvanizing would also be possible. Following this step, the galvanized wire is then coiled up again in the step 5 . The galvanized wire with the intermediate diameter D 2 is then supplied to a second drawing step 6 , whose final product is the stapling wire 7 with the desired final diameter D 3 . There is also a second drawing device with multiple drawing dies having diameters which become smaller and smaller. The stapling wire 7 is then coiled up again via an appropriate coiling device, which occurs in step 8 . The method schematically illustrated in FIG. 2 for the production of stapling wire 7 is completely without heat treatment. However, a stapling wire 7 is nonetheless produced which has excellent properties for the intended purpose of stapling periodicals. As already mentioned, steel with a low carbon content, particularly less than 0.06 weight-percent, is used as the starting material 1 to ensure good drawing properties of the starting material 1 . Thus, it is possible to draw the wire from a starting diameter D 1 of 5.5 mm down to 0.7 mm or 0.2 mm without any heat treatment. In the schematic illustration according to FIG. 2 , step 4 involves a galvanization bath. In principle, it is also possible to provide other coating devices, or, in specific applications, to dispense with the coating completely. In the embodiment illustrated, the first drawing step 2 is performed with the dry drawing process, while the second drawing step 6 , due to the preceding surface finish, is performed with the wet drawing process. Dry drawing typically requires the use of an appropriate dry lubricant. In this context, it is particularly favorable to provide, following the first drawing step 2 , a step 9 ( FIG. 3 ) for surface cleaning of the wire for preferably complete removal of the dry lubricant. An appropriate surface-cleaning device is provided for this purpose. This step ensures that no dry lubricant residue remains on the wire when the coating is performed in step 4 , so that the coating adheres well on the staples produced from the wire. Otherwise, the method illustrated in FIG. 3 corresponds to that in FIG. 2 . In FIG. 4, a stress-strain diagram is illustrated which, shows the stress-strain properties of the stapling wire 7 formed by the process according to the invention and compares this curve to a stapling wire h produced according to the method of the prior art. It can be seen that stapling wire 7 is harder, but definitely keeps its shape after bending. Furthermore, stapling wire 7 can also be cut very well, so that problems in the stapling of periodicals or similar items are not a concern. The values of the diagram indicated on the abscissa are only applicable for one preferred embodiment of the wire produced according to the method according to the invention, but other value ranges are also possible without any further measures. Accordingly, while at least one embodiment of the present invention has been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined in the appended claims.