GB2184779A - Automatic lock slider for slide fastener - Google Patents

Abstract

An automatic lock slider (10) for a slide fastener provided with discrete coupling elements (19) includes a locking prong (20b) being movable into and out of a guide passage (17) of the slider and having a canted cam surface (20d) at the end portion. The slider further includes an upwardly sloped cam surface (27') in an inner wall thereof in confrontation to the prong. The canted cam surface (20d) and the sloped cam surface (27') cooperate to allow the fastener chain to pass underneath the prong (20b) in a locking position without marring the coupling elements when an external force is applied directly to the fastener chain to spread apart the same. <IMAGE>

Description

SPECIFICATION Automatic lock slider for slide fastener This invention relates to sliders for slide fasteners provided with discrete coupling elements and in particularto such a slider which means of automatically locking the same against movement.

A conventional slider of the automatic lock type is typically provided with pull tab and a springactuated locking prong operatively associated therewith such that upward tilting of the pull tab lifts and releases the locking prong from engagement with the coupling elements of the slide fastener, and bringing the pull tab back in a position parallel with the slider body urges the locking prong down into the path of the coupling elements to lock the slider against any movement. This operation is usually manipulated by fingers on the pull tab. However, with garments of rigid fabric such as jeans to which slide fasteners equipped with the above-mentioned lock sliders are applied, it is often a lazy practice to grab the garment fabric and spread the fastener stringers forcibly apart to open the fastener instead of the usual manipulation of the pull tab on the slider.A similar scene of this practise is also witnessed at the site of sewing slide fasteners to jeans trousers or other garments made of rigid fabric materials. It would be however desirable from a view point of productivity and facility to be able to open the slide fastener without manipulating the slider pull tab.

Japanese Utility Model Laid-Open Publication No.

51-126703 proposes a means of opening the slide fastener, while the slider is locked, without having such adverse effects as malaligned or dislocated coupling elements which would otherwise take place due to the elements being trapped and jammed between the locking prong and the inner walls of the slider body. The proposed means consists of a cavity formed in the bottom wall of the slider body, the cavity being deep enough to allow the coupling elements to move underneath and clearthe locking prong.

It has been found however that the above prior art is not quite satisfactory in that the coupling elements are often prevented from moving past the locking prong partly on account of dimensional irregularities of finished parts and more fatally because of structural problems. More specifically, these problems are associated with the shape of the locking prong which is square and straight throughout its tip end and further with the contour of the cavity having its forward end wall being upright and substantially perpendicular to the plane of the bottom wall. Accordingly the coupling elements whose allowable angle of tilt is normally 20"--30" are prone to get jammed against the end wall of the cavity and fail to move out of the latter, resulting in displaced, separated or otherwise damaged coupling elements.

According to the present invention, there is provided an automatic lock slider for a slide fastener having a slide fastener chain provided with coupling elements comprising: a slider body including upper and lower wings spaced in parallel to each other and joined together at a front end portion to define a guide channel therebetween; a pull tab pivotally mounted on the slider body; a locking member supported on the slider body and including a locking prong movable into and out of the guide channel; said locking prong having a rearwardly canted cam surface adapted to allow the coupling elements to tilt therealong when the slide fastener chain is forced to spread apart the same while said prong is in a locking engagement with the fastener chain; and said lower wing having a cavity disposed in an inner surface thereof to open to said guide channel in registry with said prong, said cavity being progressively reduced in depth toward said front end portion to thereby provide an upwardly sloped cam surface.

It is believed possible by means of the present invention to provide an automatic lock slider for a slide fastener which incorporates structural features such that the coupling elements on the fastener are allowed to move, while being tilted within their allowable range of angles, smoothly past, underneath, the locking prong of the slider without encountering difficulties experienced in the prior art devices.

The invention will be described by way of example with reference to the accompanying drawings, wherein like references refer to like parts unless the contex requires otherwise and wherein:- Figure 1 is a longitudinal cross-sectional view of a slider embodying the invention mounted on a slide fastener chain; Figure 2 is an enlarged fragmentary side elevational view of a locking prong constituting an operative part of the slider; Figure 3 is a longitudinal cross-sectional view of a modified part of the slider of Figure 1; Figure 4 is a perspective view of a fragmentary bottom portion of the slider of Figure 1; Figure 5 is a schematic side elevational view on enlarged scale of a portion of the slider of Figure 1, illustrating the operative relationship between the locking prong and the fastener coupling elements;; Figures 6--9 inclusive are longitudinal crosssectional views of a rear portion of the slider of Figure 1, illustrating the behavior of the coupling element in progression; Figure 1S13 inclusive are longitudinal crosssectional views of modified portions of the slider of Figure 1; and Figure 14 is a longitudinal cross-sectional view of the slider incorporating a modified locking arrangement.

Referring now to the drawings and Figure 1 in particular, there is shown in longitudinal crosssection an automatic lock slider generally designated at 10 for use in a slide fastener. The slider 10 has a slider body generally indicated with 11 which includes upper and lower spaced parallel wings 12 and 13 which are joined attheirfront ends by a connecting neck 14 commonly known as a diamond head. The upper and lower wings 12, 13 are generally similar in shape and inwardly flanged along their lateral side edges as at 15 as better shown in Figure 4. Formed in and extending vertically through the connecting neck 14 is a retention groove 16 for receiving one end of a spring locking member 20 later described.

The upper and lower wings 12 and 13 of the slider 10 define therebetween a generallyY-shaped guide channel 17 for the passage therethrough of a pair of stringers each including a support tape 18 and a row of discrete coupling elements 19 of a discrete formation.

Formed on the upper surface of the upper wing 12 adjacent to the neck 14 is a first retaining lug 21 which holds the locking member 20 in place against lateral movement. A second retaining lug 22 is formed likewise on the upper wing 12 adjacent to an aperture 23 communicating with the guide channel 17 and is adapted to restrict ascending movement of the free end of the locking member 20 which functions as a locking prong hereafter described.

The locking member 20 is made of a resilient material as a whole, and it has a downwardly curved end 20a received and anchored in the retention groove 16 and a straight vertically depending free end which serves as a locking prong 20b resiliently movable through the aperture23 into and out of the guide channel 17. The locking prong 20b is brought into and out of engagement with the coupling elements 19 in the guide groove normally by manipulation of a pull tab 24 in a well known manner. As shown in Figure 4, the locking prong 20b is adapted to project in a space between an adjacent pair of the discrete coupling elements 19, and more specifically between an adjacent pair of leg portions (only one shown) of the coupling elements.The locking prong 20 includes a bulged support portion 20c adjoining the prong 20b, the bulged portion 20c defining with the upper surface of the upper wing 12 a lateral bore 25 for pivotally receiving a spindle 26 of the pull tab 24. The spindle 26 has a peripheral cam surface for operatively engaging the bulged portion 20c.

The general construction and operation of the automatic lock slider 10 as above described is conventional, and hence no further explanation will be required.

Now, according to an important aspect of the present invention, the locking prong 20b is provided at its outer rear portion with a cam surface 20d extending at a canted angle from a vertical lock surface 20e to a horizontal end surface 20f, as better shown in Figure 2.

According to another important aspect of the invention, there is provided a cavity 27 in an inner or upper surface of the lower wing 13 in confronting relation to the aperture 23, the cavity 27 opening to the guide channel 17 and being progressively reduced in depth toward the forward end or the connecting neck 14 of the slider body 11 to provide a cam suface 27'.

Forces directly exerted on the fastener chain to spread apart the same urge the coupling element 19 to tilt in abutting engagement with the locking prong 20b and sink into the cavity 27. This dual movement if the coupling element 19 is effected by the presence of forces or stresses barely reaching or immediately premature of the critical point of a slider lock strength at which the coupling element 19 would be shifted out of position or separated from the support tape 18. The critical angle at which the coupling element 19 can tilt at once and sink or descend is normally 20 30 .

The behavior or the above dual movement of the coupling element 19 in contact with the locking prong 20b is illustrated in Figures 5 and 69 inclusive, in which the coupling element 19 initially in a locked position begins to tilt and sink under the influence of spreading forces upon the fastener chain as the upper front corner 19a of the element 19 slides down along the canted cam surface 20d of the locking prong 20b.The cam surface 20d serves not only to permit the coupling element 19 to tilt as shown in Figures 6 and 7 but also to lift the locking prong 20b in contact with the coupling element 19 against spring tension in the locking member 20 as shown in Figure 8, for which purpose the angle of the cam surface 20d is ideally at about 45 . The coupling element 19 continues to advance in siiding contact with the locking prong 20b until the upper rear corner 1 9b of the element 19 reaches the right angle corner 20b' of the locking prong 20b, at which time the coupling element 19 is in effect released from the locking prong 20b and thereafter guided up along the upgrade cam surface 27' of the cavity 27 back onto a regulartrack in the guide channel 17 as shown in Figures 5 and 9.If were not for the upgrade cam surface 27', the coupling element 19 would stand upright during forward travei and end up in getting jammed against the frontal cavity wall.

Figure 3 shows a part modification of the slider of Figure 1 in which the rear end portion of the inner surface of the lower wing defining the guide channel 17 has a length L greater than an element-toelement pitch P such that during normal manipulation of the slider 10 to close the fastener, the coupling elements 19 are prevented from falling into the cavity 27 by the gravity of the fastener chain that has already moved out of the guide channel 17.

Figure 10 shows a modified form of the cavity 27 in which its contour is cross-sectionally arcuate.

Figure 11 shows a cavity 27 being bottomless to provide access to the guide channel 27 to clean the same.

Figure 12 shows a cavity 27 whose bottom surface is extended straight out through an extreme end of the lower wing 13, the arangement being advantageous for molding the slider body 11 and also for keeping the coupling elements free from being captured in the cavity 27.

Figure 13 shows a modification of the locking prong 20b in which its cam surface 20d is arcuately contoured.

Figure 14 shows a modified locking arrangement including a locking member 30 angularly movable held in a recess in the upper wing 12 and having a prong 30b projecting through the aperture 23 in the upper wing 12. A cover 31 is disposed over the upper wing 12 and the locking member 30. A leaf spring 32 is supported on an inner wall of the cover 31 to normally urge the locking member 30 downwardly to project the prong 30b into the guide channel 27 through the aperture. The prong has a canted cam surface 20d and the cavity arrangement 27, 27' is formed in the lower wing 13.

In each of the above-described and illustrated embodiments, the rearwardly canted cam surface of the locking prong is adapted to allow the coupling elements to tilt therealong when the slide fastener chain is forced to spread apart the same while the prong is in a locking engagement with the fastener chain. Also, in each embodiment the cavity in the inner surface of the lower wing is progressively reduced in depth toward the front end portion (i.e.

toward the connecting neck) to thereby provide an upwardly sloped cam surface.

Claims (7)

1. An automatic locksliderfora slide fastener having a slide fastener chain provided with coupling elements comprising: (a) a slider body including upper and lower wings spaced in parallel to each other and joined together at a front end portion to define a guide channel therebetween; (b) a pull tab pivotally mounted on the slider body; (c) a locking member supported on the slider body and including a locking prong movable into and out ofthe guide channel; (d) said locking prong having a rearwardly canted cam surface adapted to allow the coupling elements to tilt therealong when the slide fastener chain is forced to spread apart the same while said prong is in a locking engagement with the fastener chain; and (e) said lower wing having a cavity disposed in an inner surface thereof to open to said guide channle in registry with said prong, said cavity being progressively reduced in depth toward said front end portion to thereby provide an upwardly sloped cam surface.

2. An automatic lock slider according to claim 1, said canted cam surface having a flat surface rearwardly upwardly slanted at such an angle as one coupling element is allowed to slide therealong when the slider fastener chain is forcibly spread apart with the prong in the locking engagement therewith.

3. An automatic lock slider according to claim 2, said angle being 45 degrees.

4. An automatic lock slider according to claim 1, said canted cam surface being in the form of an arcuate surface.

5. An automatic lock slider according to claim 1, said cavity including an arcuate bottom surface.

6. An automatic lock slider according to claim 1, said cavity extending rearwardly to a rear end of said lower wing.

7. An automatic lock slider according to claim 1, said lower wing including a rear end portion defining a guide channel portion extending between a rear edge of the cavity and the rear end of the lower wing, said rear end portion having a length greater than an element-to-element pitch of the coupling elements.