Apparatus for manufacturing slide fastener filament

#The present invention relates to methods and apparatus for manufacturing for slide fasteners coiled filaments which have the interlocking teeth of the slide fastener.

#Thus, the present invention relates to a method for manufacturing elongated coiled slide fastener filaments which are continuous and preferably made of a plastic material. The invention relates to that type of method wherein the coiled filament is formed on a setting gear wheel the teeth of which are utilized, as well as the gaps between these teeth, in the formation of the coil which may have the configuration of a flattened spiral or another configuration which will have an equivalent effect. The flattened spiral which forms the coiled filament has sharp kinks or bends where the interlocking teeth of the slide member are situated. Of course, the invention also relates to an apparatus for performing the method of the invention.

#At the present time there are a number of different known methods and apparatus for manufacturing slide fasteners of the above general type. In general, the known methods and apparatus utilize a principle according to which the filament is wound in a number of different ways and by various different structures around consecutive teeth of a setting gear wheel, although it is also known to utilize a filament which is preliminarily bent into a spiral or zig-zag configuration separately from the gear wheel. In this latter event, the preliminarily shaped blank filament is fed onto the setting gear wheel to be heat treated so as to relieve the stresses in the row of convolutions of the coiled filament. There are also known methods and apparatus according to which initially depressions are impressed, as by hacking, into the filament, these depressions being provided periodically at equal intervals along the filament, and the filament blank which is obtained in this way is then fed in an enforced manner onto the setting gear wheel so that as the filament is bent the initially formed depressions provide the consecutive locking teeth situated along the respective coils of the filament.

#The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

#FIG. 1 is a schematic illustration of a slide fastener having filament coils manufactured according to the method and apparatus of the invention, the slide fastener being shown in FIG. 1 closed at the lower part of FIG. 1 and open at the upper part of FIG. 1;

#FIG. 2 is a schematic fragmentary top plan view of apparatus of the invention for performing the method of the invention;

#FIG. 1 illustrates part of a slide fastener manufactured with the method and apparatus of the present invention, the slide fastener itself being known. The slide fastener shown in FIG. 1 includes a pair of coiled plastic filaments 10 having flattened convolutions. These coiled filaments 10 are sewn, for example by the lines of stitches 13, to a pair of tapes 11. At their inner portions which project inwardly beyond the tapes 11, the filament coils 10 have at the several convolutions the slide fastener teeth 12 which according to the movement of a conventional slider up and down the slide fastener can be moved between the locked position shown in the lower portion of FIG. 1 and the unlocked position shown in the upper portion of FIG. 1. As is indicated in FIG. 1, each tooth has a breadth a.

#The apparatus and method of the invention illustrated in FIGS. 2-8 are capable of manufacturing a pair of coiled filaments 10, although as will be apparent from the description below, it is also possible to utilize the method and apparatus of the invention in the manufacture of only one filament at a time. The filament F from which the coiled elements 10 are made is preferably a plastic filament, consisting, for example, of a suitable thermoplastic material. The filament F appropriately has a circular cross section. As is indicated in FIG. 3, in the particular method and apparatus shown there are a pair of coaxial setting gear wheels 14a and 14b which have a common axis D--D shown in FIG. 6. Each of the gear setting wheels has at its periphery teeth 15 separated by tooth gaps 15a, as shown most clearly in FIG. 2. These teeth 15 as well as the tooth gaps 15a are of a substantially rectangular configuration. While the axis D--D is shown in FIG. 6 as being vertical, this axis can also be horizontal or it may have an intermediate inclined attitude.

#As is best shown in FIG. 3, a stationary or fixed stop member 16 is provided, having an elongated edge portion extending with clearance into the space between the gear setting wheels 14a and 14b so that the edge portion of the stop member 16, shown at the left in FIG. 3, defines with the peripheral portions of the setting gear wheels, where the teeth thereof are located, a pair of gaps 17.