FASTENERS

Abstract: Figure 1 shows a band fastener in an open condition. The thin flexible band loop carries a hook 12 spaced from one end, and the opposite end is formed into a generally triangular shape to carry a toggle fastener which can draw the ends together and clamp the band about a pipe or other object.

Description: This invention relates to fasteners of the kind comprising a band which is to loop about an object to be clamped, and with means for contracting the loop and fixing the loop in the contracted position. Various different fasteners of this general kind are known. For example it is known to turn the ends of the loop radially outwardly and aperture them, using a nut and bolt extending generally tangentially of the loop to draw the ends together. Such a fastener is cheap and simple but slow to operate and tends to apply pressure to the article clamp by the band unequally. Another known fastener of the general kind referred to is a worm drive hose clip where the band is provided with a series of parallel slots or recesses in a tail portion which extends through a housing fixed to the other end of the band, and a screw carried in the housing engages in those slots so that rotation of the screw contracts or expands the band. A disadvantage of fasteners of that kind is (again) the slow operation and a further disadvantage is that the band has to be of a certain thickness and stiffness to carry the slots or the like which again makes it likely that pressure is applied unequally to the clamped object. The object of the invention is to provide an improvement. According to the invention a fastener of the kind comprising a looped band and means for contracting the loop, has a two part fastener with one part attached near each end of the band, one end of the band extending past the attached part in the interior of the loop and overlapping the other end of the band, the fastener being a toggle fastener. The term "toggle fastener" as used herein means a fastener having a mounting plate, a lever pivoted to the mounting plate about a first axis, a hasp bail pivoted to the lever about a second axis, and the bail extending past the first axis to a permanent or releasable pivotal engagement with the other of the fastener parts about a third axis. When such a fastener is in the open or released condition the attachment plate hasp and bail form a somewhat Z shape, and as the lever is moved generally parallel to the attachment plate it also moves the hasp bail to a similar relationship and draws the third axis towards the other two axes. Preferably the toggle fastener used in the present invention has an over-centre action. That is to say in contracting the loop and folding the parts of the toggle fastener to the generally parallel condition, the second axis is taken from one side to the other of a plane containing the first and third axes. Such an over-centre action provides a lock against accidental displacement. Preferably the band is made of particularly thin and flexible material so as to conform to the contour of the object to be clamped. Spring steel is preferred, and this may additionally enable the loop to automatically relax and open when the hasp bail is appropriately positioned. As mentioned, the third axis may be a permanent connection between the hasp bail and one end of the band or it may be a releasable connection as by providing that end of the band with a hook. In general there are two alternative possibilities for overlapping the ends of the band. In one possibility the hook or equivalent is provided at the extreme end of the band and the other components of the toggle fastener are mounted near, but not at the opposite end of the band, so that said opposite end can extend and underly the end provided with a hook, or in other words the end provided with a hook overlaps the opposite free end of the band. In the other alternative, the toggle fastener components are mounted on one end of the band and the hook or equivalent is provided near the other of the band but not at it, so that the band portion extending past the hook can overlap or more strictly underly the opposite end of the band which carries the toggle fastener. The attachment plate on which the lever is mounted may be fixed to a platform extending generally tangentially of the loop on which in one of the possibilities is made out of an end portion of the band. This can be done even when the band is of particularly thin and flexible material by forming the end of the band into a somewhat triangular shape, the three sides of the triangle being composed by a portion of the loop, a platform extending under the attachment plate, and a tie consisting of a final portion of the band extending between the outer end of the platform and the loop at a position say 60 degrees of arc around the loop form the end of the latter which is integral with the platform. The platform may be sandwiched between the attachment plate and a reinforcement located internally of the triangle, the reinforcement abutting the loop at one end, and one end of the tie at the other end, and being in compression. The tie itself is in tension when the band is clamped about an object. Alternatively the triangular shape may comprise a portion of the loop as a first side, with a stiffer V shaped part fixed to the loop at the free ends of both limbs of the V so as to form the platform and the tie and in this event a reinforcement may be unnecessary. If the bail is to be permanently attached to the band, the hook may be closed around the bail at the pivotal connection between the two: if releasable the hook could be a generally C shape. Three embodiments of the invention are now more particularly described with reference to the accompanying drawings wherein: Figure 1 is an elevation of a first fastener in an open condition; Figure 2 is a generally similar view of a second fastener in the same open condition: Figure 3 shows the first fastener in a closed position: Figure 4 shows the second fastener in a closed position clamped around an object: Figure 5 is a view similar to figure 4 showing the third fastener in the closed position: Figure 6 is an enlarged sectional view on the line 6.6 of figure 5. Referring first to Figure 1, a length of thin flexible material is formed into a loop having a first inner end 10, extending beyond a fixed attachment hook 12 (and continuing clockwise) to a second attachment point 14 where it may be rivetted or spot welded to the loop. A toggle fastener comprises attachment plate 22, lever 24 and hasp bail 26. The latter is generally U shaped to engage over the hook 12. As seen in Figure 3, when the fastener is in the closed condition, the loop ends 10, 16 are substantially overlapped so as to ensure that an object being clamped is engaged about 360 degrees of periphery. Any inequality of pressure in clamping occurs at the zone 30 where there is step owing to the overlapped layers of the band, and the dimension of that step depends upon the thickness of the strip used for the band. In the figures 1 and 3 illustration, the band is sufficiently thick and rigid to be used as the platform 18 without needing any stiffening on the interior of the triangle formed by the parts 18, 20 and the adjacent band sector. The lever is pivoted on the axis of pin 32 and the hasp bail on the axis of pivot 34. The third axis is that of the connection of the hasp bail to the hook. It will be noted that in moving from the Figure 1 to Figure 3 position, the axis of pin 32 moves from one side of a plane containing the axes of pin 34 and of the engagement with the hook 36 to the other side of that plane to give the over-centre action previously referred to. The fastener of Figures 1 and 3 may be adjustable to give different clamping pressures on the same nominal size by making the spacing between the pins 32, 34 variable by use of a screw connecting the two, and with the pin 34 extending in slots 38 in the sides of the lever 24 for that adjustment purpose. The fastener shown in Figures 2 and 4 is generally similar. It differs particularly in being made from a very much thinner band material so that the platform for the attachment plate of the toggle fastener needs to be stiffened by the component 42 located in the interior of the triangle and in compression between the points 44 and 46 due to the tension applied to the band when it is clamped. In addition the toggle fastener has the refinements of a lug 48 apertured to align with an eye 50 in the side of the lever so that a locking pin or padlock can be inserted to hold the fastener in the locked condition: and a locking catch operated by a member 52 which is slidable in the direction fo the arrows A-A of Figure 4 to engage a hook not shown because it lies between the side walls of the lever in a further locking slot 54 in the lug 48, so as to provide security against accidental operation and release of the fastener. In making a fastener according to the alternative arrangement described herein, the band would at the end 10 terminate in the vicinity of the hook 12, and for example could be formed directly into the hook instead of using a separate part fixed to the band. The opposite end of the band 16 would then continue in the loop so as to underly the hook. In the case of Figure 2 and 4 the band is so thin that there is an imperceptible step in the overlapped position giving particularly uniform clamping pressure around the object, and it will be noted that such uniformity will be maintained even if the object is non-circular. The point 44 may cause a binding or scuffing of the material being clamped as the fastener moves from the Figure 2 position to the Figure 4 position. This may be particularly or even exclusively the case where the band is of particularly thin and flexible material. It is preferred to use particularly thin and flexible material for the band in order to get good clamping even if the object is not truly circular. The binding or scuffing can be reduced by stiffening the thin material of the band by using a thicker shorter stiffening piece 60 as illustrated in Figure2 and 4. Such a piece is however optional and its use, or not, may depend upon the particular application of a fastener. Where it is employed, it will extend over a sufficient length so that it overlaps the point 44 even in the most open position of the fastener possible, i.e. that illustrated in Figure 2. At the opposite end it is conveniently fastened to the hook or like which provides the attachment point which engages with the hasp bail. In the third fastener shown in Figures 5-6 the construction is generally the same as in Figures 2 and 4 except that the optional stiffener 60 is replaced by a channel section (and essential) stiffeners 64 which is fixed to the hook and to the flexible band. This channel serves to receive and locate the outer end of the band between its side walls whilst the inner end of the band 68 lies under the end of the channel. Locating the toggle fastener generally tangentially of the loop ensures that the clamping force provided does not have any distorting effect on the loop causing localised unbalanced pressures.

Claims: 1. A fastener of the kind comprising a looped band and means for contracting the loop, having a two part fastener (12,22-26) with one part (12) attached near one end of the band and the other part (22-26) attached near the opposite end of the band,one end of the band (10) extending past the attached part in the interior of the loop and overlapping the other end of the band, and characterised in that the fastener (22-26) is a toggle fastener. 2. A fastener as claimed in Claim 1 characterised in that the toggle fastener has an over-centre action (Figure 2) in which the hasp bail 26 travels from one side to the other of a plane containing the pivotal axes (32,34) of the bail on the lever (24) and the lever (24) on a mounting plate (22) of the fastener, during the final stages of closing the fastener. 3. A fastener as claimed in Claim 1 wherein the band is made of particularly thin and flexible spring steel material. 4. A fastener as claimed in Claims 1 to 3 wherein one part of the fastener (22-26) comprising the lever (24) and bail (26) is mounted at one end of the band and the other end of the band (10) extends to the interior of the fastener, with a hook or equivalent (12) for bail engagement fixed to the band away from said end (10) so that the ends of the band overlap. 5. A fastener as claimed in any of Claims 1 to 3 wherein one part of the fastener comprising the lever and bail (24,26) is mounted away from one end of the band and the other end of the band is provided with hook or equivalent to engage with said bail and so that the ends of the band overlap. 6. A fastener as claimed in any preceding claim in which the lever (24) of the toggle fastener is mounted on an attachment plate (22) fixed to a platform (18) extending generally tangentially of the loop. 7. A fastener as claimed in Claim 6 wherein the platform is made out of the band which is formed generally into a triangular shape of which one side is the platform (18), one side is the loop, and the third is a tie strut (20). 8. A fastener as claimed in Claim 7 wherein the platform (18) is sandwiched between said attachment plate (22) and a reinforcement (42) which abuts the other two sides of said triangle so as to be in compression when the tie is in tension. 9. A fastener as claimed in any preceding claim wherein the end of the band carrying the hook or equivalent (12) is fixed to a stiffener (60). 10. A fastener as claimed in Claim 9 wherein the said stiffener is of channel section with sides (64) receiving the opposite end of the band carrying the lever and bail (24,26).

Inventors: COOKE, ROBERT SEYMOUR
Applicants: HOWARD S. COOKE & CO LTD
Application year: 1987
Main classification: F16B2
IPC codes: F16B2, F16L33