GB2445156A

GB2445156A - Concealed slide fastener

Info

Publication number: GB2445156A
Application number: GB0604599A
Authority: GB
Inventors: Mark Davis
Original assignee: YKK Europe Ltd; YKK Corp
Current assignee: YKK Europe Ltd; YKK Corp
Priority date: 2006-03-07
Filing date: 2006-03-07
Publication date: 2008-07-02
Anticipated expiration: 2026-03-07
Also published as: GB2445156B; US20070209170A1; CN101057721A; JP4822187B2; JP2007236958A; GB0604599D0; CN100508816C

Abstract

A slide fastener has coupling elements 11, 13, 15 which comprise a head 43 and a shelf (47, Fig 3). The heads engage with the heads of their counterparts, and also bear on the shelves of their counterparts through the tape of the fastener to resist forces transverse to the fastener. The tape (17, 19, Fig 3) extends from the front of the coupling element and then bends round over it so that the coupling elements are hidden. Because the shelf is on the other side of the tape from the head it can be made thicker than if it were on the same side, see figure 10. The coupling elements may be injection moulded onto the tape using a two part mould.

Description

Concealed Slide Fastener The present invention relates to a concealed

slide fastener and in particular to a concealed slide fastener having moulded elements.

Examples of concealed slide fasteners having moulded elements are described in US-A-4 078 278, JP-A-2000-201708, JP-A-2598345 and US-A- 3 124 871. Figure 10 shows a coupling element illustrated in US-A-4 078 278.

A stringer of a concealed slide fastener having moulded elements 101 is provided by moulding the fastener elements 101 on to an edge of a tape (not shown) so that the tape exits the element from a slot 103 formed in a front surface 105 of the element body 107. The coupling part 109 of the coupling element 101 is formed on the front surface 105 of the body, to one side of the tape. The tape is then folded around the upper body portion 107a, away from the coupling part 109 to cover the upper surface 111 of the body. When the stringer is coupled with a like stringer, the tapes abut, between the facing front surfaces 105 of the coupling elements 101, thus concealing the elements 101 when viewed from above. A similar technique can be used for providing waterproof fasteners and the present invention includes such fasteners.

A drawback of the prior art arrangement is that the coupling part 109 is formed completely to one side of the tape. Because the element body 107 must be of sufficient thickness in the region 107a above the tape, to prevent it fracturing, the body portion 107b below the tape must be kept relatively thin to avoid the element body 107 being too thick overall. Thus, the coupling part 109 formed is on only about one half the overall depth of the body. The coupling part 109 serves two main functions. Firstly, heads 117 of the coupling parts on opposed elements engage behind each other to prevent separation in the plane of the fastener. Secondly, shelves 113 are formed on the heads 117 to bear on shelves 115 provided on the opposed elements to limit out of plane bending of the fastener and prevent separation of the coupling elements by out of plane movement. This shelf 113 forms an undercut on the head 117 facing the tape and so it is necessary to use a sliding core mould for moulding the coupling elements 101 on the tape. If the coupling part 109 is too thin, particularly at the region of a shelf, it is likely to break when the fastener is flexed roughly or even in normal use. Also, the thin coupling element head 117 itself contributes less resistance to out of plane bending of the fastener.

However, the overall thickness or depth of the element 101 must be kept small for aesthetic reasons, and also to reduce the amount and cost of materials.

In one aspect of our invention we provide a concealed slide fastener in which moulded coupling elements are provided on the edge of a tape, with a head of the coupling element on one side of the tape and a shelf of the coupling element on the other side. A body of the element straddles the tape edge. The tape exits the body at a front surface. The coupling head extends from the front surface, on one side of the slot where the tape exits the body. The shelf is formed by a projection on the front surface, at the other side of the tape. The tape is wrapped over the projections and the upper surface of the body. When the coupling heads of opposed stringers are engaged, the heads of one stringer engage behind the heads of the opposed elements on the other stringer and bear on the shelves of the opposed elements through the thickness of the respective tape. By forming the shelves on the other side of the tape, the coupling head can be the full depth of the body portion on the one side of the tape. Preferably there is no undercut facing the tape, and so the coupling elements can be moulded without a sliding core: a two part mould can be used.

Preferably the slot mouth formed where the tape exits the body is about half way up the front face of the body.

Preferably the tape portion within the body is positioned substantially at a mid plane of the body.

The coupling element head is formed on a neck which extends from the front face of the element body. A coupling element head engages behind the heads of two opposed coupling elements on the other stringer and lays between their respective necks. A shoulder is provided each side of the neck, to provide an abutment surface for the head of an opposed element.

The shelf may extend the full width of the body, in the elongate direction of the tape. Preferably two shelves are provided, at opposite ends of the body surface, and respective protrusions forming the shelves form a recess between the protrusions. The recess may partially accommodate the shelves of opposed elements.

The protrusions of opposed coupling element are spaced from each other by the thickness of the intervening tapes. Depending on the desired appearance, a greater spacing may be provided. Particularly for a waterproof fastener, the protrusions may be arranged to pinch the tapes together.

As well known, as the fastener is flexed, a coupling element head bears on the adjacent necks and heads of the opposed coupling elements and the opposed shoulders. By maximising the height of the element heads, to the depth of the body portion on one side of the tape, the coupling elements are better able to resist flexing of the fastener. Preferably the element heads and the necks are shaped so that a coupling head abuts the shoulders on the opposed elements and also abuts the side surface of the adjacent coupling heads at a region which transitions from the head to the neck. Preferably the side surfaces abut one another at a region midway between the opposed tapes. The heads also bear on the shelves of the opposed elements through the respective tape to prevent separation by out of plane movement.

Other features and advantages of the invention will be apparent from the

accompanying description and claims.

The invention will be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view from above of three coupling elements of a slide fastener which forms an embodiment of the invention, with the respective tapes removed for clarity; Figure 2 is an underneath perspective view of the elements of Figure 1 Figure 3 is a cross-section along line Ill-Ill of Figure 1, and showing the slide fastener tapes; Figure 4 is a plan view of a slide fastener coupling element of Figure 1; Figure 5 is an underneath view of the element of Figure 4; Figure 6 is a side view of the element of Figure 4; Figure 7 is a plan view of a modification of the slide fastener, with one tape removed; Figure 8 is a cross-section through the slide fastener, showing a part of a slider; Figure 9 is an underneath plan view of the coupling elements of Figure 1 showing the contact surfaces of the elements, and

Figure 10 shows a prior art coupling element.

Referring to Figure 1, this shows three coupling elements 11, 13, 15 of thermoplastic material which are moulded directly onto respective tapes 17, 19 (shown in Figure 3) by injection moulding. The tapes have cords 21, 23 at their edges 25, 27. As seen in Figure 3, the element body portions 29 straddle the respective tape edge. The tape exits the body portion at a slot in the front face 31, approximately mid way of the face. The tape edge portion is shown in the mid plane of the element body portion 29, but it could be angled to the mid plane. The tape edge portion 25, 27 is positioned to ensure that there is sufficient thickness of material of the body portion 29 around the tape edge to avoid any weakness in the body portion 29.

Projections 33 project from the front face 31 of the body portion 29 at each outer end 35 thereof and form a recess 37 between them. The projections 33 extend down to the tape 17, 19 to form shelves 47 facing the tape.. As seen in Figure 3, the tapes 17, 19 are folded around the projections 33, passing over the recess 37 and covering the upper surface 41 of the respective elements 11, 13, 15.

A coupling portion 53 extends out from the front surface 31 and is formed by a coupling element head 43 on a neck 45. Shoulders 46 are formed on the front face 31 to each side of the neck 45. From Figure 2 it can be seen that in the coupled fastener, the head 43 of coupling element 11 engages behind the heads 43 of the opposed elements 11, 13 to prevent separation of the coupling elements in the plane of the fastener, as well known in the art.

The head 43 also presses against the necks 45, heads 43 and shoulders 46 of the adjacent elements 11, 13 to limit out of plane movement or twisting of the elements relative to one another. The head 43 also bears on the shelf 47 (Figure 5) formed by the underside of the projections 33, to limit relative out of plane movement of the adjacent coupling elements. It will be appreciated that the respective tape (in this case tape 17) is interposed between the head 43 of element 15 and the shelves 47 of elements 11, 13.

Thus it can be seen that the upper faces 49 of the coupling element heads 43 are adjacent the underneath surface of the tape 17, 19 where it exits the coupling element body 29 and the shelves 47 are adjacent the upper surface of the tape 17, 19, generally in line with the upper and lower walls of the slots 30.

Referring to Figure 3, the tapes 17, 19 are nipped between the projections 33 of the opposed elements 11, 13, 15. The degree of compression of the tapes will depend on the distance between projections. Some compression is desirable for a waterproof fastener. For a fabric, relatively less compression is desirable to avoid puckering of the fabric. Referring to Figure 6, it can be seen that the elements 11, 13, 15 can be injection moulded on to the respective tape which is captured in a mould which splits approximately along the line X-X, because there are no undercuts facing the tape 17, 19. As known in the art, several coupling elements can be moulded at a time on to the tape 17, 19. Metal elements could be stamped or crimped onto the tape edge.

Figure 7 is a plan view of a slide fastener of the invention. This has coupling elements 11' similar to those of Figure 1. One of the tapes has been removed and it can be seen that the projections 33' are positioned to each side of the neck 45 so as to bear on the adjacent heads 43 of the opposed elements, with the tape sandwiched in between. The projections help to limit out of plane bending of the fastener by abutting the opposed projections if the fastener is twisted. The positioning and width of the projections will depend on the desired effect and in particular how important it is to avoid any puckering of the material of the tapes on the upper surface of the fastener.

Figure 8 shows a cross section through a fastener with a part of a slider 51 which embraces the coupling elements and is slid along the fastener to close or open the fastener as known in the art.

Figure 9 shows the contact between coupling elements 11, 13, 15. The coupling element head 43 of element 15 abuts the shoulders 46 on the opposed pair of elements 11, 13. Additionally the coupling portion 53 touches the adjacent coupling portions 53 in the widthways direction at a transition region 55 where the coupling head 43 transitions into the neck 45. There is a gap 57 in the region between where the head 43 abuts the shoulder 46 and the transition region, bridging the centreline A-A of the fastener. Contact at the transition region 55 and the shoulders 46 provides for greater stability of the fastener. However, if adjacent teeth contact completely along their facing surfaces, the fastener will be difficult to operate.

Claims

CLAIMS: 1. A concealed slide fastener comprising a pair of stringers in

which moulded coupling elements are provided on the edge of a respective tape, a body of the coupling element straddles the tape edge and the tape exits the body at a front surface thereof, a coupling portion of the coupling element extends from the front surface adjacent one surface of the tape and a shelf is formed on the front surface, adjacent other side of the tape, whereby when the coupling elements of opposed stringers are engaged, the coupling portions of one stringer engage behind the coupling portions of the opposed elements on the other stringer and bear on the shelves of the opposed elements through the thickness of the respective tape.
2. A concealed slide fastener as claimed in claim 1, wherein there is no undercut facing the tape, and the coupling elements can be moulded with a two part mould.
3. A concealed slide fastener as claimed in claim 1 or 2, wherein the tape is positioned at a mid plane of the body.
4. A concealed fastener as claimed in claim 1, 2 or 3, wherein two shelves are provided on a coupling element and are formed by projections at opposite ends of the body front surface to form a recess between the shelves.
5. A concealed slide fastener as claimed in any one of claims 1 to 4, wherein the shelves of opposed coupling element are spaced from each other by approximately the thickness of the intervening tapes.
6. A slide fastener as claimed in any one of claims 1 to 5, wherein a coupling portion comprises a neck extending from the front surface of the body and a head formed on the neck, and shoulders are formed on the body adjacent the neck, wherein a coupling portion abuts the adjacent opposed coupling portions at the shoulders and at the transition regions between the head and the neck.
7. A concealed slide fastener in which moulded coupling elements are provided moulded on the edge of a tape, wherein a head of the coupling element is provided on one side of the tape and a shelf of the coupling element on the other side.
8. A concealed slide fastener in which coupling elements are moulded on an edge of the fastener tape using a two part mould.