GB2304149A

GB2304149A - Zip fastener

Info

Publication number: GB2304149A
Application number: GB9516170A
Authority: GB
Inventors: David Johnson; Nigel Berry; Masaharu Sato
Original assignee: YKK Europe Ltd
Current assignee: YKK Europe Ltd
Priority date: 1995-08-07
Filing date: 1995-08-07
Publication date: 1997-03-12
Anticipated expiration: 2015-08-07
Also published as: GB2304149B; GB9516170D0

Abstract

The coupling elements 2 mounted on a stringer tape 12 of a zip fastener are deburred by a deburring wheel 36 which rotates transverse to the elongate direction of the fastener to deburr the edge 18 of the foot portion 14 of the coupling elements 2 and the outer face 20.

Description

ZIP FASTENER The present invention relates to a zip fastener and a method of manufacturing zip fasteners. In particular it relates to the manufacture of metal zip fasteners in which the coupling elements are deburred to remove sharp edges.

It is known to tumble the coupling elements of a zip fastener to remove rough edges before the elements are mounted on the fastener tape. This suffers the drawback that the projections on the heads of the elements, which engage with corresponding cavities in other elements when the fastener is closed, are worn by the tumbling process, and so it is difficult to maintain the tolerance required for high quality fasteners.

Several machines have been proposed for grinding or polishing the fastener elements when they are mounted on the fastener tapes. In this way the orientation of the element relative to the grinding or polishing wheel can be controlled so that only selected parts are ground.

In JP 30-13189 a single stringer is fed past a grinding wheel. The fastener tape is held in a groove to orient the coupling elements relative to the grinding wheel. A three stage process is used to grind, in turn, three faces at the head of the coupling elements.

JP-31-7349 shows a system in which the sides of the elements are polished. The elements of two stringers are meshed together, forming a chain, and the chain is then passed around a pulley wheel, with a contrarotating polishing wheel bearing on the element sides.

These systems aim to improve the fastener, by polishing the coupling elements to make them shiny and to smooth the head portion over which the slider travels.

In these prior art systems, the grinding or polishing wheel rotates in the plane of movement of the stringer.

This limits the portions of the coupling elements which can be ground or polished.

We have now realised that by rotating a wheel in a plane transverse to the direction of movement of the stringer we can deburr the foot portion of the coupling element, and in particular the exposed edge of the coupling element foot, which runs parallel to the stringer, and also polish the outer faces of the coupling element.

This helps reduce the friction between the slider and the coupling elements.

A first aspect of the present invention provides apparatus for deburring coupling elements of a zip fastener, the apparatus comprising guide means having a channel for receiving a tape of a stringer carrying a plurality of coupling elements, means for moving the stringer in a first, lengthwise direction through the channel, and a deburring wheel mounted to rotate in a plane transverse to the direction of movement of the stringer to deburr an edge of the foot portion of the coupling elements distal of the head portion.

Preferably the channel guides the tape in a substantially straight line past the deburring wheel.

Preferably, two guide channels are provided to receive respective tapes of two stringers, the coupling elements of which are coupled together forming a chain.

Preferably two deburring wheels are provided, spaced apart along the direction of movement of the chain, and rotating in opposite directions to deburr the coupling elements of a respective stringer. The wheels are rotated in the direction from the foot towards the head of the respective coupling element.

Preferably, the guide channels are angled to each other and away from the wheel, so that the foot portions of the coupling elements are made proud to the deburring wheel.

Preferably the coupling elements are supported on their face opposite the deburring wheel and preferably suction in applied to draw dust away from the coupling elements during deburring.

Another aspect of the invention provides a method of manufacturing a zip fastener, comprising mounting coupling elements on a fastener tape, moving the fastener tape in a first direction, rotating a deburring wheel in a plane transverse to the first direction, and bringing the foot portion of the coupling elements into contact with the deburring wheel.

The invention also provides a zip fastener comprising U-shaped metal coupling elements each having a head portion which engages with a head portion of a like coupling element, side portions which embrace an edge of a fastener tape and foot portions at the ends of the side portions distal of the head portion, wherein the edge of the foot portion extending in the elongate direction of the stringer is deburred.

The invention will be further described by way of example with reference to the accompanying drawings in which: Figure 1 shows a coupling element of a zip fastener, Figure 2 shows schematically a deburring apparatus according to the invention, Figures 3a and 3b shows details of a deburring station of the machine of Figure 2; Figures 4a and 4b show a detail of Figures 3a and 3b; and Figure 5 shows the contact between a deburring wheel and a coupling element.

Figures 1 and 5 illustrate a metal coupling element 2 of a zip fastener. The basic shape of such elements is well known in the art and may be varied in its details according to the size and performance requirements of the zip fastener. Typically, the elements 2 are cut or stamped from a flat wire strip or from a shaped strip.

Both processes tend to leave burrs at the cut edges, which can increase friction between the elements and the slider, and also feel quite rough or sharp to the touch. The coupling element 2 has a head portion 4 having a projection 6 which, in use, engages with a cavity 8 formed in the underside of the head portion of a like coupling element (see figure 4). Extending away from the head portion 4 are two side portions 10 which straddle the reinforced edge of a fastener tape 12 A foot portion 14 is formed at the end of each side 10, distal of the head portion 4. The foot portions are pinched together to pinch the fastener tape 12 between their opposed faces 16 to secure the coupling element 2 on the reinforced edge of the fastener tape 12.

When metal coupling elements are manufactured, they will have sharp edges which can feel rough to the touch, and can also increase resistance to movement of the slider along the zip fastener. The present invention aims to remove the burr or sharp edge found at the edges and corners of the foot portion. In paraticular, it is desired to deburr the edge 18 which extends in the direction of the fastener tape 12 and, at the same time, to polish the visible or facing surface 20 of the side portions 10.

Referring to Figure 2, two stringers 22 (the elongate fastener tapes 12 having coupling elements 2 mounted on them, as in figure 4) are fastened together forming a chain 24. Gaps are formed along the tapes 12, between groups of coupling elements 2, to define the beginning and end of the finished zip fastener, as is well known in the art. The chain 24 is fed through a detector and counter 26 which detects and counts the spaces for control of the production line.

The chain 24 is then fed past four deburring stations 28 which will be described in more detail with reference to figures 3 and 4.

Two stations 28a, 28b deburr one side of the elements on chain 24, and the chain is then twisted through 180 degrees at 30 for deburring the other side of the elements at stations 28c, 28d. The stations 28 are identical in construction save that the position of the deburring wheel is different for the stations of a pair 28a, 28b; 28c, 28d, as will be described with reference to Figures 4a and 4b.

The chain 24 is drawn through the apparatus by a feeder unit 32 to a roller guide 34, from where it passes to a storage reel or directly on to the next stage of the production process.

Referring to Figure 3a, which shows a cross-section on the line III-III of station 28a in Figure 2, a deburring wheel 36 is mounted to rotate in a plane perpendicular to the direction of movement of the chain 24 (ie. to rotate in the plane of the paper).

A support 38 has two guide channels 40, 42 which receive and guide respective tapes 12 of the chain 24.

The coupling elements 2 are received in a support channel 44 between the guide channels 40, 42. The support channel 44 has a rear wall 46 and side walls 48 which support the coupling elements 2 to limit movement when engaged by the deburring wheel 36. As shown in Figure 3b, the rear wall 46 of the channel 44 has air holes 50 which connect with a conduit 52. A vacuum device sucks air through the air holes 50 via the conduit 52. This in turn draws air through the coupling elements as they are drawn across the rear wall 46. The air flow serves several functions; it cools the coupling elements during the deburring operation, it draws off waste material formed during deburring, and it also draws the coupling elements against the rear wall.

As shown in Figure 2, each pair of adjacent supports 38a and 38b, 38c and 38d is mounted on a carriage 54 having a first threaded adjuster 56 allowing coarse adjustment towards the wheel 36. Individual second threaded adjusters 58 adjust the position of the support 38 on the carriage 54 for fine movement of the support 38 towards and away from the respective deburring wheel 36.

Figures 4a and 4b show on a larger scale the guide channel and the position of the deburring wheel 36 relative to the coupling elements 2 of the chain 24.

The centre of rotation C of a wheel 36 is offset from the centre line C' of the chain 24, and is aligned approximately with the centre line of the side wall 10 of the elements 2 which are being deburred. Thus, in Figure 4a the wheel 36a at one station 28a engages the edge 18 of the coupling elements of one stringer (from "below"), and in Figure 4b the wheel 36b at the adjacent station 28b engages the coupling elements of the other stringer (from "above").

Figure 5 shows an enlarged view of the contact of the deburring wheel 36 with the coupling element 4. It can be seen that the wheel abrades the edge 18 of the head portion 14 to deburr it, and also polishes the surface 20 of the side portion 10.

Thus the apparatus of the invention deburrs the outer edge of the coupling elements, at the foot portion, and also polishes the outer faces of the elements, without affecting the head portions.

Claims

1. Apparatus for deburring coupling elements of a zip fastener, the apparatus comprising guide means having a channel for receiving a tape of a stringer carrying a plurality of coupling elements, means for moving the stringer in a first, lengthwise direction through the channel, and a deburring wheel mounted to rotate in a plane transverse to the direction of movement of the stringer to deburr an edge of the foot portion of the coupling elements distal of the head portion.

2. Apparatus as claimed in claim 1, in which the channel is arranged to guide the tape in a substantially straight line past the deburring wheel.

3. Apparatus as claimed in claim 1 or 2, in which two guide channels are provided to receive respective tapes of two stringers, the coupling elements of which are coupled together forming a chain.

4. Apparatus as claimed in claim 3, in which the guide channels are angled to each other and away from the wheel, so that the foot portions of the coupling elements are made proud to the deburring wheel.

5. Apparatus as claimed in any one of claims 1 to 4, in which two deburring wheels are provided, spaced apart along the direction of movement of the chain, and rotating in opposite directions to the coupling elements of a respective stringer.

6. Apparatus as claimed in any one of claims 1 to 5, in which the coupling elements are supported on their face opposite the deburring wheel.

7. Apparatus as claimed in any one of claims 1 to 6, in which suction is applied to draw dust away from the coupling elements during deburring.

8. A method of manufacturing a zip fastener, comprising mounting coupling elements on a fastener tape, moving the fastener tape in a first direction, rotating a deburring wheel in a plane transverse to the first direction, and bringing the foot portion of the coupling elements into contact with the deburring wheel.

9. A zip fastener comprising U-shaped metal coupling elements each having a head portion which engages with a head portion of a like coupling element, side portions which embrace an edge of a fastener tape and foot portions at the ends of the side portions distal of the head portion, wherein the edge of the foot portion in the elongate direction of the stringer is deburred.