GB2070676A - Strap belt and buckle - Google Patents

Abstract

A buckle, particularly for use with a strap of woven synthetic material, comprises a flat base with three apertures, 2, 3 and 4 and upstanding sides 1. A cross-piece 10 links the sides at points above the base. In the form shown in Fig. 1, a pivoted member 15 is provided and has an edge-piece 16 to clamp, under spring tension, the strap aggainst the base, thus preventing movement of the strap when it is unloaded and the frictional retaining forces caused by looping the band the apertures 2, 3 and 4 are inoperative. <IMAGE>

Description

SPECIFICATION Strap belt This invention concerns a strap belt, which comprises a woven, flat band, preferably of textile material, with at least one buckle, from which the band extends as a closed loop with adjustable length which can be fixed by the frictional action with the buckle. The strap belt is designed to achieve the greatest possible strength, rapid and convenient handling, and is created for use as a luggage strap, towing line or lifting strap for example.

Strap belts, or bands of the type indicated in the introduction, are previously known in many different variations. Among all these variations can be distinguished a large group in which the buckle is more or less permanently fixed to the band by stiff or sharp objects which interact with or penetrate the band. To this group can also be referred such designs in which the band is sewn or riveted to the buckle. Designs belonging to this group can probably function well as long as no high demands are made upon the tensile strength and furthermore that the band used is manufactured from a material which does not undergo any marked elongation before rupture takes place. Typical examples of bands which satisfy these requirements are leather belts, or woven bands of cotton material or other natural fibre.Latterly however bands of synthetic materials have appeared where both the material itself has a relatively high extensibility and the manner in which the band is woven also contributes to the band having a very high elongation before rupture occurs. Characteristic for bands of this type is then that they are cheap to manufacture, withstand very high tensile forces before rupture occurs, and that their permanent or elastic elongation immediately before rupture can often be very high, in certain cases up to 40%. If it is to be possible to make use of the superior physical properties of such a band in practice, it is essential that the band when loaded does not suffer any local elongation which would bring in its train local, more or less permanent deformations or failures which would have a seriously impairing effect upon the total strength of the band.It is clear that a band with these properties is broadly speaking quite useless in such connections where the band is fixed to a buckle by rivets for example, or where the band is sewn to the buckle, since both the riveted connection and the sewn area have completely different tensile properties than those otherwise demonstrated by the band. In a similar manner, such designs in which a stiff object projects through the band, or where a sharp object lies in contact with the band, are also unsuitable for the same reason. This means that the category of strap belts given above are not capable of utilizing the superior values of tensile strength that bands of this type exhibit on the assumption that they are loaded in a correct manner.

The high strength values for woven synthetic band discussed above implies also that special care must be taken in the design of the buckle so that this will not be the weak link. For this reason such buckles that are bent in such a way that they can be more or less straightened out, deform or deflect so that their original shape is affected or obliterated are unsuitable for use together with modern woven synthetic bands if optimal strangth is the objective.

An object of the present invention is therefore to achieve a strap belt of the type indicated above, designed in such a way that it has optimal strength in relation to the quantity of material included both in the band and in the buckle, and furthermore designed in such a way that it can be used quickly and conveniently.

With this object in view the present invention provides a strap belt for securing, towing or the like and comprising a band preferably a flat textile band and at least one buckle which has frictional interaction with the band and from which the band extends as a closed loop with adjustable length arranged for fastening around a load or a load holder characterised by the buckle having the form of a rigid unit with an essentially flat bottom with side elements projecting upwards therefrom, with a cross-member connecting the side elements at a distance from the bottom, and the bottom section having three openings arranged consecutively, when the band sections forming the loop possess self-locking frictional action with the bottom, at the edges of the openings situated furthest from each other when loaded.

The invention will be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view of a buckle which is part of a preferred embodiment of the strap belt of the invention; Figure 2 is a sectional elevation of the buckle of Fig. 1, its buckling with a woven synthetic band being shown in outline; Figure 3 corresponds substantially with Fig.

2 but shows in outline the woven synthetic band encircling an article; Figure 4 corresponds with Figs. 2 and 3 but shows an alternative manner of buckling the buckle and the woven synthetic band; and Figure 5 is a sectional elevation of an alternative buckle for use with the preferred embodiment of the strap belt of the invention.

It will be seen from Figs. 1 and 2 that the preferred strap belt of the invention comprises a buckle consisting of a bottom section, which is essentially flat, and which is manufactured in one piece with two side elements 1 projecting therefrom at right angles. The bottom section is equipped with three openings, 2, 3 and 4, which extend over its entire width, and where the opening 2 has preferably a dimension in the longitudinal direction of the buckle which is considerably greater than is the case with the two other openings. The remaining parts of the bottom section of the buckle form bridges which connect the side elements 1 with each other and which are designated 5, 6, 7 and 8. Bridge 8, at the one end of the buckle, is extended by a bent transitional section to form a grip 9, which is arranged at an angle to the essentially flat bottom section of the buckle.In addition the buckle has a transverse or cross-member 10, which is placed at a distance above the bottom section of the buckle and which, in the longitudinal section of the buckle, can be suitably situated directly above that edge of opening 2 that is nearest to the grip 9 of the buckle. The crossmember 10 can suitably be of cylindrical cross-section. for manufacturing reasons, even if this is not absolutely necessary for functional reasons. The cross-member 10 can thus be a rivet with heads 11 and 12, which connects the two side elements with each other, permanent and unrotatable.

In the form shown in Fig. 2 the object of the invention is intended with band section A to extend over a load which can be placed on the roof rack of a car. The other end of the band, i.e. the extension of band section A can be fixed to the roof rack by means of a buckle idemtical with that shown in Fig. 2. As will be seen from Fig. 2 the band passes under the bridge 5, up through the opening 4, and then over the bridges 6 and 7, to proceed down through the opening 3, over the bridge 6 and down through the opening 4. The passage of the band as described means that through friction effect, principally with the bridges 6 and 7, the band is held fixed relative to the buckle, in which connection however it must be noted that the buckle can easily be moved along the band if only the band is unloaded.

The band moreover passes around the various bridges in such a way that no bending moment of significance for strength is exercised on the buckle as a whole or on the bridges.

Furthermore the pure tensile force on the bridges will be in the direction of their greatest material cross-section. This means in other words that the buckle will be subjected to the most favourable case of loading that is on the whole possible.

Emerging from opening 4 the band then forms with sections B and C a closed loop, which for example can be threaded around a tube 1 3 forming part of a roof rack, or some other fixed anchorage. From the tube 1 3 band section C then proceeds to the edge of the bridge 8, then up around the cross-member 10 and again down around the edge of the bridge 8, where the band section D emerges.

When the band is under tension the two band sections C and D will be pressed against each other and against the edge of the bridge 8, but in addition a corresponding pressing of the band will take place around the crossmember 10, which thereby together achieves a very effective locking of the band in relation to the buckle due to friction. The length of the closed loop B C can be simply reduced by a, tension in the band section D, whereby this tension achieves a certain rotation of the buckle clockwise, so that the friction effect between the band and the buckle in the region of cross-member 10 and the edge of bridge 8 is reduced. As soon as the band section D is released however, the buckle will return to its original position due to the elasticity of the band, thereby reestablishing the friction effect at full strength.This means in other words that the buckle and the band in the region of the cross-member 10 and the edge of bridge 8 have a slef-locking friction effect that comes into effect as soon as the band is in tension.

In a corresponding manner this self-locking effect between the band and the buckle can be terminated simply by lifting the grip 9 away from the tube 13, i.e. so that the buckle is rotated clockwise.

The laws of geometry and friction which govern the friction effect of the band on the buckle are completely analogous with the state of affairs in connection with the effect of a rope laid around a bollard or a belt around a pulley, for example. Practical tests have demonstrated that the friction effect is so large that slipping between the band and the buckle can hardly occur, not even if the strap belt is loaded to failure. Such tensile tests have also indicated that in contrast to many previously known buckles the buckle described in the invention is not deformed to such an extend that the effect of friction is affected or that the buckle is overloaded to failure. This means in practice that a relatively slenderly designed buckle is capable of withstanding the same heavy loading as the textile band which is threaded through the buckle.

It can also be noted in this connection that a condition for the good strength properties mentioned is that the edges of all the parts of the buckle with which the band comes into contact are well rounded so that stress concentrations in the band are avoided at these places. It can further be noted that the most highly loaded parts of the buckle are arranged with their greatest material cross-sections in, or essentially in, the direction of the ruling loadings.

Fig. 3 shows an alternative use of the strap belt in accordance with the invention. In this figure the belt is shown being used as a collective organ around for example, a crate or some other kind of package. It will also be seen that the band sections A and B of Fig. 2 have in principle changed places and purposes in the form shown in Fig. 3. It is thus band section A which together with band section C form a closed band loop which embraces the crate 14. As far as the rest is concerned, the same friction relationship applies in this form both for opening and tightening of the band loop. This means for example that the band loop A C can be tightened very hard simply by applying a tensile force to band section D, when the above-mentioned self-locking effect is also achieved as soon as the tensile force in band section D is discontinued.Furthermore, in spite of the fact that there is a very large tensile force in the loop A C, it is possible to simply terminate the friction effect between the band and the buckle by lifting the grip 9 from the crate 14.

Even if the method shown in Fig. 3 of passing the band through the buckle gives excellent results in a normal case, practical tests show that the band will begin to slip round bridges 6 and 7 when the tensile force has reached a certain value. Since this slipping occurs before the band ruptures or the buckle deforms. the total strength of the device has not been completely optimally utilised. The method of passing the band through the buckle shown in Fig. 4 gives so much greater frictional effect between the band and the buckle that the design is completely optimised, i.e. failure of the band occurs at about the same time as the buckle has been so far deformed that its function has begun to be affected.

The textile band used in accordance with the invention can at least in its loaded condition be considered as having no stiffness of its o'/n. Despite that, this inherent negligible stiffness however can give rise to certain problems when the strap belt is completely unloaded or only loaded to a very slight extent. Thus in such situations slipping can occur around cross-member 1 0 and against the edge of bridge 8.If for example the strap belt is to be used as a lifting strap, where for example a lifting device is expected to engage with some part of the band loop A C in the application shown in Fig. 3, or if for example band section A is connected with a lifting device, while the band loop B C is fastened to a load which in Fig. 2 is represented by the tube 13, such a poor friction effect before any loading takes place can cause problems. In order to eliminate probierns of this kind, the buckle can be naodiwiew and amplified in the way shown in Fig. 5. A pivoting locking member 1 5 is arranged thus between the side elements 1 of the buckle.This member has an edge section 36 which can be brought to a spring engagen1ent with the section of the band that passes around cross-member 10.

The locking member 1 5 has two curved sections 1 7 which extend n bow form to surround partly cross-member 1 0 and which can suitably be somewhat springy. The free ends of the bow-iormti sections are pivoted at 1 8 to the inside of the side elements 1 of the buckle, and thus the locking mernber 1 5 can be rotated through approximately 1 80' frnm the position shown in Fig. 4.In order to achieve a good spring effect at the edge 1 6, which is necessary if the locking member 1 5 is not to rotate inadvertently from the position shown in Fig. 4, it is best if the edge 1 6 is placed somewhat nearer the bottom of the buckle than the centre of the cross-member 1 0. Furthermore, the distance between the edge 1 6 and the nearest point of cross-mem- ber 10 should be somewhat less than the thickness of the band when this is in an unloaded state. The distance between the edge 1 6 and the cross-member 10 should not however be so small, or the edge 1 6 so sharp, that there can be a risk that the band will be lacerated.Even if the interaction between the edge 16, the band and the cross mernber 10 can give rise to consideraDole forces, it is not these frictional forces that primarily keep the band fixed relative to the buckle; this takes place in the manner described above. On the other hand, the extra friction brought about by edge 1 6 is of the greatest importance in those situations when the band is essentially unloaded, i.e. before a proper tightening of the loop has taken place by pulling on band section D.

Even if the friction between the band, tha edge 1 6 and the cross-member 10 cannot replace the other friction effect for the 30cking of the length of band loop, the extra friction force at the edge 1 6 helps to achieve a friction which is sufficiently large to prevsm'J the band loop increasing in size even if the grip 9 is lifted. This means that broadly speaking it is impossible to remove the buckle from the band even if the grip is lifted, so long as the locking member 1 5 is in the position shown in Fig. 5.This situation can be made use of through the locking member having a projecting lug 1 9 with an opening, at the opposite end to the pivot 1 8, and that this iug on the locking member is matched bIv a corresponding lug 20 on one of the side elements 1 of the buckle. The lug 20 situated on the side element is also provided with an opening, through which for example a seal or a locle can be threaded, making it posible to break open a crate 14 as in Fig. 3 without being discovered. It is naturally also possible, if space permits, to arrange these holes in tithe side elements of the buckle and the locking member. In these forms the buckle can 6133 be used for sealed securing of woads, car covers and the like on vehicles such as cars or trailers.

Claims (4)

1. A strap belt for securing, towirl9 or t;se like and comprising a band preferably a flat textile band and at least one buckle which bas frictional interaction with the band ini from which the band extends as a closed loop with adjustable length arranged for fastening around a load or a load holder characterised by the buckle having the form of a rigid unit with an essentially flat bottom with side elements projecting upwards therefrom, with a cross-member connecting the side elements at a distance from the botton, and the bottom section having three openings arranged consecutively, when the band sections forming the loop possess self-locking frictional action with the bottom, at the edges of the openings situated furthest from each other when loaded.

2. A strap belt as claimed in claim 1 characterised by the cross-member being arranged essentially directly opposite the edge of the opening situated nearest one end of the buckle, this one end of the buckle having a grip, and one end section of the band acting against the edge of that opening nearest the grip and being passed around the cross-member and back to the afore-mentioned edge of the opening, to be fixed relative to this by friction when the grip is not effected.

3. A strap belt as claimed in claim 2 characterised by the buckle having a pivoted locking device which with a section can be brought to a locking position pressing the band against the cross-member when the locking device and the buckle have in the locking position openings adjacent to each other which can receive a seal or the like.

4. A strap belt substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.