GB2065218A - Buckle for fastening a bundling strap - Google Patents

Abstract

A buckle, for fastening a bundling strap having stop projections (12), comprises a main body having an insertion hole extending therethrough for permitting the ends of the bundling strap to be inserted therein. Tongue-shaped engaging pieces (6) are possessed of thin-wall connecting edges (5) and are formed in opposed walls of the main body, free ends of the tongue-shaped engaging pieces being formed in an increased wall thickness and incorporating inner edge parts in the form of stop claws (8), as well as outer edge parts in the form of catch portions for engagement with catch portions (10) presented by the opposed walls of the main body. The bundling strap is fastened with the buckle by pressing the tongue- shaped engaging pieces (6) into the insertion hole, with the thin-wall connecting portions (5) serving as fulcrums, until the catch portions of the engaging pieces (6) and the catch portions (10) engage, allowing the stop claws (8) to be thrust into the insertion hole and brought into engagement with the stop projections (12) of the bundling strap. <IMAGE>

Description

SPECIFICATION Buckle for fastening a bundling strap This invention relates to a buckle for fastening the loose ends of a bundling strap which is used for bundling cords and tubes distributed within electric appliances and automobile engine rooms.

A wide variety of buckles designed to fasten the loose ends of bundling straps have been proposed and have found utility in practical applications.

These conventional buckles are in inseparable relation with bundling straps and they are, in most cases, constructed in conformity to the shape of bundling straps with which they are used. The buckles of the commonest type are cylindrically formed and the bundling straps are admitted through insertion holes which are formed by the inner walls of the cylinders. Generally, these insertion holes are provided with claws, which are adapted to be hooked on matching projections formed on the straps inserted therethrough so as to prevent the received straps from being accidentally pulled out of the buckles, whereby the bundling straps are retained in their securely fastened condition.Further, in the buckles of the class incorporating such claws, the claws are provided more often than not on the inner wall surfaces of these insertion holes or near the entrances or exits of such insertion holes. At the same time, these claws are resiliently joined at one side to their respective buckles and are adapted to come into contact with the surface of the straps passed through the insertion holes in such a manner that the claws permit advance of the straps in the direction from the entrances to the exits and, when the direction of their advance is reversed, the claws are brought into engagement, by the resilient force exerted thereto, with the projections formed on the bundling straps to prevent the straps from being pulled out of the insertion holes.It may be safely said that the claws having conferred thereupon the resiliency of the nature of a non-return claw are most popular and are used widely.

The conventional buckles provided with claws of the nature of a non-return claw, however, have these claws exposed at all times to contact with straps thrust into the insertion holes. The claws, therefore, interfere with the smooth passage of such straps and do not prove quite desirable from a viewpoint of the operation of buckles. Further since the engagement of these claws with the projections on the straps is secured by the resilient force of the claws, there is a possibility of the engagement being broken by a pull given with a force surpassing the resilient force.

Further, among the bundling straps of the type designed to bundle given cords or pipes with the aid of an automatic bundling machine, those which have found popular acceptance are so constructed that bundling straps are formed integrally with buckles containing insertion holes adapted for insertion of bundling straps and the insertion holes of the buckles are provided with claws. With the conventional bundling straps of the type just mentioned, when the straps are used with the aid of an automatic bundling machine, the claws formed within the insertion holes of the buckles interfere with smooth passage of the straps through the insertion holes after the straps have been wrapped round given cords or pipes, rendering it troublesome to have the loose ends of straps passed into the insertion holes of the buckles.In an extreme case, this interference could be such as to deprive bundling straps of their self-retaining force.

This invention has issued from a research carried out to cope with the various problems entailed by the conventional buckles.

A major object of this invention is to provide a buckle for a bundling strap, so constructed that a pair of claws offer absolutely no obstacle to the bundling strap while the strap is being inserted into the insertion hole, but facilitate the passage of the strap and enhance the operational efficiency of buckle and, when the inserted strap is brought to a stop within the insertion hole, the claws are engaged with an adjacent pair of projections on the strap to ensure the engagement and, consequently, the buckle is allowed to manifest an extremely powerful fastening force on the bundling strap.

Another object of this invention is to provide a buckle for a bundling strap which proves particularly effective when it is used for fastening bundling straps round given cords or pipes by use of an automatic bundling machine.

According to the present invention a buckle, for use in fastening a bundling strap of the kind provided on a front face thereof with a series of stop projections in the longitudinal direction of the strap, comprises: a main body having an insertion hole extending therethrough of a size sufficient for permitting a bundling strap of the stated kind to be inserted therein when its ends are placed back to back and one on top of the other; opposed walls of the main body carrying a pair of tongue-shaped engaging pieces, each of which has a relatively thin edge on an entrance side of the insertion hole, two side edges and a relatively thick edge on an exit side of the insertion hole, the relatively thin edges being hingedly connected to the opposed walls and the three remaining edges of each of the engaging pieces being either separated from or frangibly connected to the opposed walls, with the result that the relatively thick edges can be regarded as free ends of the engaging pieces; and the free ends including inner edge parts for engagement with adjacent stop projections on a bundling strap, and also including outer edge parts in the form of catch portions for engagement with adjacent catch portions presented by the opposed walls; the arrangement being such that, in use, the engaging pieces are pressed into the insertion hole, with the relatively thin edges serving as fulcrums, until the catch portions on the engaging pieces and the catch portions on the opposed walls are brought into engagement, so that the inner edge parts of the free ends of the engaging pieces are thrust into the insertion hole and brought into engagement with the stop projections formed on the bundling strap.

The buckle of this invention permits perfectly smooth passage of a bundling strap, because it avoids forming any engaging means which projects toward the axis of the insertion hole of the buckle.

The accompanying drawings show a preferred embodiment of the invention, which represents one typical buckle. In these drawings Figure 1 is a partially cutaway perspective view of the buckle and a fragmentary perspective view of a bundling strap; Figure 2 is a plan view of just the buckle of Figure 1; Figure 3 is a centrally cross-sectioned view of the buckle and the strap of Figure 1; and Figure 4 is a centrally cross-sectioned view of the buckle having a bundling strap caught fast in position.

In the drawings, the main body 1 of this buckle is formed in the shape of a generally angular barrel and is provided at the central portion thereof with an insertion hole 3 large enough for the loose ends of a bundling strap 2 to be placed back to back one on top of the other and inserted therethrough.

The upper and lower walls 4,4 of the aforementioned main body, opposed vertically to each other, are provided with tongue-like engaging pieces 6, 6 formed by inserting a perforation of the shape of three sides of a square each in the walls, with thin-wall connecting portions 5 formed on the entrance 3a side of the aforementioned insertion hole 3 falling on the remaining side of the square of perforation.

The engaging piece 6, 6 mentioned above, as a whole, are formed in a thickness roughly equal to the wall thickness of the main body of buckle, with the exception of the aforementioned connecting portions 5 which are formed in a smaller thickness in order that the engaging pieces may be readily bent down into the insertion hole at the time that the bundling strap is to be caught fast in position as described more fully afterward. The free ends of the engaging pieces are formed conversely in an increased wall thickness, with a catch portion 7 formed each at the outer edge parts and a stop claw 8 formed each at the inner edge parts respectively of the engaging pieces. On the outer surface parts of the engaging pieces, push projections 9 protruding above the outer surfaces of the main body of buckle are integrally formed.

The engaging pieces 6, 6 are formed by inserting a perforation in the shape of three sides of a square each in the opposed walls 4, 4 of the main body as described above. In this embodiment, notched edges in the walls 4 opposed to the free ends of the engaging pieces are formed in the shape of claws to give rise to catch portions 10. The leading ends of the catch portions 10 and the aforementioned free ends are connected each with a readily breakable thin-wall piece 11. Owing to the connection through these pieces 11, the engaging pieces are prevented from otherwise possible oscillation and the inner surfaces of the engaging pieces are kept flush with the entrance 3a side of the inner wall surfaces of the insertion hole of the main body of buckle while the buckle is being molded.Further in this embodiment, the exit 3b side of the insertion hole 3 in the main body of buckle is given a large opening to increase the distance between the inner wall surfaces of the upper and lower walls of the buckle at the opening, so that the aforementioned catch portions 10 meet the free ends of the engaging pieces 6 at points falling halfway in the entire depth of the free ends, with the stop claws 8 thrust inwardly therefrom.

On the other hand, the bundling strap 2 in this embodiment is a flexible strap which is provided on one side (surface) thereof with stop projections 12 formed in an undulated series in the longitudinal direction, and along the opposite lateral edges thereof with integrally formed reinforcing strips 13, 13 of a height equalling the height of the aforementioned stop projections. In bundling given cords or pipes, this strap is wrapped round the cords or pipes, with the side containing the aforementioned stop projections facing outwardly. The loose ends of the strap which are inserted into the buckle are joined back to back and are drawn into the insertion hole 3 (Figure 3).The inner depth of the insertion hole 3 in particular must be selected in advance so that during the insertion into the buckle, the loose ends of the bundling strap placed, back to back, one on top of the other are smoothly advanced inside the buckle and the loose ends slide one over the other inside the insertion hole and are not allowed to produce any play during their advance.

After the loose ends of the strap have been inserted through the insertion hole 3 as described above, they are drawn off each other to an extent required to tighten the strap's grip of the cords or pipes and then the engaging pieces 6, 6 provided in the buckle are depressed from outside to force the free ends thereof down into the interior of the insertion hole 3 with the connecting portions 5 serving as their fulcrums. Consequently, the bundling strap is caught fast inside the buckle.

This forced insertion of the engaging pieces 6, 6, in the present embodiment, is accomplished by applying pressure to the push projections 9. Under the pressure, the engaging pieces are bent inwardly about the connecting portions 5 as the fulcrums and, at the same time, the thin-wall pieces 11 are broken. As a result, the free ends are thrust into the interior of the insertion hole 3 and the stop claws 8 formed at the inner edges of the free ends are brought into engagement with the stop projections 12 formed on the strap, whereby the motion of the bundling strap within the buckle is frozen and, at the same time, the engaging pieces 6 cause the catch portions 7 provided on the outer edges of the free ends thereof to be brought into engagement with the catch portions 10 which are thrust out by being cut off at the thin-wall portions 1 1. Despite the resilient force exerted by the connecting portions 5, the free ends are retained securely in their inwardly bent state and the aforementioned stop claws 8 are kept in fast engagement with the stop projections.

Since this invention is constructed as described above, the engaging pieces remain flush with the inner wall surfaces of the entrance to the main body of buckle during the insertion of the loose ends of the strap and, therefore, offer no hindrance to the passage of the loose ends and ensure smooth progress of the bundling work. At the time the strap is to be caught fast inside the buckle, the engagement established between the catch portions 10 and the catch portions 7 prevents the engaging pieces from resuming their original state owing to the resilient force and allows the stop claws 8 to remain securely in engagement with the stop projections formed on the surface of the strap. Thus, the buckle of this invention can be expected to provide perfect fastening of the loose ends of the bundling strap.Of course, the buckle of this invention requires the connecting portions of the engaging pieces to possess resiliency. This resiliency serves the purpose of facilitating the deformation of the engaging pieces at the time they are pushed down into the interior of the buckle and, therefore, differs essentially from the springiness which is imparted for retaining the non-return claws as involved in the conventional buckles of this type. Unlike the conventional buckles, therefore, the buckle of this invention ensures smooth insertion of the loose ends of the strap and provides a fixed, powerful bundling force without entailing the possibility of the magnitude of this resiliency affecting the bundling force or increasing the springiness excessively to interfere with the insertion of the loose ends of the strap.

Owing to the construction described above, the buckle of this invention can be integrally molded of a thermoplastic synthetic resin and, therefore, can be mass produced inexpensively.

The embodiment so far described represents a case wherein the stop claws 8 are formed protrudingly specifically on the inner edge portions of the free ends of the engaging pieces 6. These stop claws 8 are formed with a view to ensuring safe engagement between the edge parts and the stop projections on the strap. Optionally, they may be formed by simply forming angular corners along the edge parts. In the illustrated embodiment, the bundling strap is of a particular type provided on one side thereof with stop projections formed in an undulated series and along the opposite lateral ends thereof with reinforcing strips. The bundling strap is not required to be limited to this particular design. It may be of a type provided only with stop projections.

Claims (6)

1. A buckle, for use in fastening a bundling strap of the kind provided on a front face thereof with a series of stop projections in the longitudinal direction of the strap, comprising: a main body having an insertion hole extending therethrough of a size sufficient for permitting a bundling strap of the stated kind to be inserted therein when its ends are placed back to back and one on top of the other; opposed walls of the main body carrying a pair of tongue-shaped engaging pieces, each of which has a relatively thin edge on an entrance side of the insertion hole, two side edges and a relatively thick edge on an exit side of the insertion hole, the relatively thin edges being hingedly connected to the opposed walls and the three remaining edges of each of the engaging pieces being either separated from or frangibly connected to the opposed walls, with the result that the relatively thick edges can be regarded as free ends of the engaging pieces; and the free ends including inner edge parts for engagement with adjacent stop projections on a bundling strap, and also including outer edge parts in the form of catch portions for engagement with adjacent catch portions presented by the opposed walls; the arrangement being such that, in use, the engaging pieces are pressed into the insertion hole, with the relatively thin edges serving as fulcrums, until the catch portions on the engaging pieces and the catch portions on the opposed walls are brought into engagement, so that the inner edge parts of the free ends of the engaging pieces are thrust into the insertion hole and brought into engagement with the stop projections formed on the bundling strap.

2. A buckle according to claim 1, in which outer surfaces of the engaging pieces carry push projections which extend outwardly beyond outer surfaces of the opposed walls.

3. A buckle according to claim 1 or claim 2, in which the side edges of the engaging pieces are separated from the opposed walls, whereas the relatively thick edges of the engaging pieces are frangibly connected to the catch portions on the opposed walls.

4. A buckle according to any preceding claim, in which the exit side of the insertion hole is of greater depth than the entrance side of the insertion hole, and the inner edge parts of the engaging pieces are formed as stop claws which, before use, lie internally of the catch portions on the opposed walls whilst still enabling inner surfaces of the engaging pieces to be substantially flush with inner surfaces of the opposed walls on the entrance side of the insertion hole.

5. A buckle according to any preceding claim which is integrally moulded of a thermoplastics material.

6. A buckle according to claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.