For various reasons, the use of metal top end stops is being abandoned in favour of plastic top end stops that can be fused into the tapes of the slide fastener. The stops are located in anvils and the edges of the tape introduced into the stops in the anvils, which are then subject to heat and pressure from ultrasonic horn means to fuse the plastic and cause it to flow into the fabric of the tapes for good bonding.

EP 0 396 373 discloses a method, itself an improvement on an earlier-proposed method, for applying plastic top end stops in which the stops are held between an anvil and a horn, the anvil and horn being moved together into the path of travel of the fastener tapes, which are threaded through the stops. The anvil and horn are vertically movable together toward and away from the horizontal path of travel of the fastener tapes. After the anvil has been separated from the horn, to remove the tapes from the anvil, both anvil and horn are moved out of the path of travel of the tapes. In this way, a prepared, continuous length of fastener, complete except for the top end stops, and having bottom stops, sliders, and sections (where the top end stops are to be inserted) without the interlocking fastener teeth, can be processed continuously, by pulling through a section to which top end stops have been applied and cutting off the length of completed fastener, the next section of the continuous length to have top end stops fitted being thereby pulled through to the location of the anvil and horn.

One problem which is likely to arise with this procedure is that the ultrasonic fusing can be difficult to arrange to apply equally to both tapes of the fastener, with the result that one of the top end stops may be imperfectly bonded so that it can work loose with use of the fastener. Another problem is that the operation has to be carried out in the confined space between the laterally separated tapes of the fastener, which means that special measures (referred to in EP 0 396 373 aforementioned) have to be taken to ensure that the tapes are perfectly guided to be threaded through the stops so that their edges are snugly inside, and remain so, as the horn is brought down on to the anvil.

The present invention provides a way of attaching plastic top end stops that does not suffer from these problems.

The invention comprises a method for applying fusible top end stops to the two tapes of a slide fastener, comprising holding two top end stops in adjacent anvils inserting the edge of each tape into one of the top end stops clamping and fusing the top end stops to the edges of the tape by applying to each one a separate ultrasonic horn and thereby applying heat energy to each of the top end stops to clamp and fuse it to its respective tape edge.

By using two separate ultrasonic horns, each is independently adjustable to take account of differences between the plastic filaments from which the top end stops are produced.

The filaments are produced by cutting lengths (about 4mm) from spools, and it is found that there often substantial differences, arising in production or from different times or conditions of storage, between the two spools of filament used to make the end stops for one or the other of the tapes. Using a single horn at best means that there has to be a compromise in the setting of the ultrasonic frequency or power so that neither end stop is optimally applied..

The tapes may, during the clamping and fusing operation, be orientated in spaced apart, parallel planes, having been twisted out of their original coplanar configuration in the fastener. The top end stops may be cut from filaments and bent into U-shapes around arbors in anvils, the U-shaped top end stops being held in place in the anvils while the arbors are removed prior to introduction of the edges of the tapes into the stops in the anvils. The anvils may be on a common member and the ultrasonic horns approach the stops from either side of the common member to heat and compress them around the edges of the tapes against the common member. The tapes may be twisted and guided around an arrowhead formation on the common member.

The invention also comprises apparatus for applying fusible top end stops to the two tapes of a slide fastener, comprising: adjacent anvils for holding U-shaped top end stops side-by-side with their open ends commonly orientated fastener transport means adapted to transport a continuous, prepared fastener length comprising consecutive fastener units each having a length of interengaging fastener teeth on tapes, bottom stops and sliders but no end stops, with a part of the teeth being omitted near the bottom stop, past the anvils, unit-by-unit, and to locate the inner edges of the tapes each into its appropriate end stop in the anvils ultrasonic horn means, one for each anvil, adapted to be deployed against top end stops on the edges in the anvils to apply heat and pressure thereto to clamp and fuse the stops to the tape edges.

The anvils may be on a common member against which the horns are deployed from either side thereof. The common member may have an arrowhead formation guiding and twisting the tapes out their original coplanar configuration in the fastener into spaced apart, parallel planes.

The apparatus may comprise top end stop forming means comprising: supports for spools of filament feed means to feed filament lengths sufficient to make top end stops anvil and deployable arbor means and co-operating punch means severing the filament lengths and bending them around the arbor means deployed in the anvil means, the arbor means being then removable leaving U-shaped top end stops in the anvil means.

The apparatus may comprise independent controls for the power and/or energy of the ultrasonic horn means.

The apparatus may further comprise cutting means for cutting finished lengths of fastener off the continuous length in between the bottom stops and the newly applied top end stops.

One embodiment of apparatus and a method for applying fusible top end stops to the two tapes of a slide fastener according to the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a face-on view of a prepared slide fastener to which the top end stops are to be applied; Figure 2 is a view like Figure 1 of the fastener, deployed for application of the top end stops; Figure 3 is a view on Arrow 3 of Figure 2; Figure 4 is a plan view of part of one embodiment of apparatus for forming and applying the top end stops, at one stage of the operation; Figure 5 is a plan view like Figure 4 of the apparatus at another stage of the operation; Figure 6 is a plan view like Figure 4 of the apparatus at a third stage in the operation; and Figure 7 is a plan view like Figure 4 of the apparatus during a final stage of the top end stop applying operation.

The Figures illustrate a method and apparatus for applying fusible top end stops 11 to the two tapes 12,13 of a slide fastener 14.

The fastener 14 is provided as a continuous, prepared fastener length comprising consecutive fastener units 14a each having a length L of interengaging fastener teeth 15 on the tapes 12,13, bottom stops 16 and sliders 17, but no top end stops. A part of the interengaging teeth rows 15 is omitted (either not having been knitted or woven in, or removed after incorporation) near the bottom stop 16 where the top end stops are to be applied. Arrows A indicate the locations where the top end stops are to be applied, arrow B indicating where, subsequently, the fastener units 14 will be separated.

Figures 2 and 3 illustrate the fastener 14 with its tapes 12,13 orientated, for the clamping and fusing operation, in spaced apart, parallel planes, having been twisted out of their original coplanar configuration in the fastener as shown in Figure 1, arrows A and B again showing the point of application and the point of separation respectively.

Figures 4 to 7 illustrate various stages in the operation of applying the top end stops 11.

Figure 4 illustrates a first stage in the forming of the top end stops from filament 41, which is supplied from two spools, not shown, mounted on supports of the apparatus.

The filaments 41 are fed through channels 42 in a member 43 to protrude therefrom by an amount, say 4mm, sufficient to form, when doubled over, 2mm deep top end stops.

The protruding lengths are severed by punches 44 which slide along the member 43 and push the severed lengths over arbors 45 deployed on an anvil 46 (Figure 5), then the arbors 45 are withdrawn leaving the top end stops 11 in place. The member 43 has an arrowhead formation 47 which constrains the tapes 12,13 to twist out of the plane of the fastener (broken line P) so that their inner edges are now aligned with the open directions of the U-shaped top end stops, into which they are inserted by the fastener transport arrangements (Figure 6).

Ultrasonic horns 61,62 now approach from each side of the member 43 and are applied against the exposed faces of the top end stops 11 to heat and press them against the member 43 so that they fuse and melt into the fabric of the fastener tapes 12,13-Figure 7.

The horns 61,62 are then withdrawn and the member 43 moved out of the way for a fresh unit of fastener to be drawn through and positioned ready for the next pair of top end stops to be applied.

The operations can be controlled automatically and adjusted for processing different lengths of fastener by the use of sensors, for example, for the bottom stops to locate the fastener appropriately for the application of the top end stops.

While specific reference has been made to the use of ultrasonic horns for the fusing and clamping operation, other methods of applying heat and pressure may be found convenient instead.