WO1998041769A1

WO1998041769A1 - Hook for webbing

Info

Publication number: WO1998041769A1
Application number: PCT/SE1998/000470
Authority: WO
Inventors: Henry Norrby
Original assignee: Henry Norrby
Priority date: 1997-03-17
Filing date: 1998-03-16
Publication date: 1998-09-24
Also published as: SE9700954L; AU6529698A; SE9700954D0; SE506857C2

Abstract

A hook for webbing includes a metal rod bent in a single piece having an upper cross piece (1) intended for receiving a webbing, said cross piece transforming into two legs (2, 2') which converge from opposite ends thereof so as to form a loop part together with the cross piece and which legs in turn transform into two curved portions (4, 4') which together form a lower hook part (5). One curved rod portion (4) is located on top of the other one (4') and fixedly joined thereto while forming a hook part (5) having a moment of inertia which is larger than the sum of the individual moments of inertia of the two portions (4, 4').

Description

HOOK FOR WEBBING

This invention relates to a hook for webbing comprising a metal rod bent in a single piece having an upper cross piece intended for receiving a webbing, said cross piece transforming into two legs which converge from opposite ends thereof so as to form a loop part together with the cross piece and which legs in turn transform into two curved portions which together form a lower hook part .

Prior Art

Hooks of the above-mentioned kind constitute a mass-produced article which is used in combination with different kinds of webbing, for instance ties and straps (see e.g. SE 9602524-2), more precisely with the purpose of enabling fastening of the webbing in holders, e. g. rings, hooks or the like, on trail cars, platform bodies, etc. Out of competition, it has always been an ambition to manufacture these hooks at such a cost being as low as possible. An important factor for keeping the manufacturing cost down as much as possible is that the hook is made in one single piece of a rod blank, more precisely by bending the blank in a machine and then harden it (in some embodiments it also occurs that two curved portions of the proper hook part are welded together by spot welding) . Previ- ously known hooks for webbing made of one single rod piece has usually been designed with two identical, although mirror- inverted side halves, more precisely of a genuine round rod, i.e. a rod having circular cross-sectional shape along the entire length thereof, the two curved rod portions forming the hook part being put side by side next to each other. Crucial for the dimensioning of each individual standard type of hook is primarily the flexural rigidity of the hook part. Namely, if the two curved rod portions which together form said hook part would be under-dimensioned relative to a predetermined loading capacity (= rated load) , there is a risk that the hook part is straightened when the webbing together with the hook are loaded maximally. Another important factor for the dimensioning is constituted by the flexural rigidity of the cross piece connected to the webbing. If said cross piece becomes too weak relative to the length thereof it may sag at maximum load and thereby deform the hook in its entirety. Previous attempts made in order to reduce the manufacturing cost for such hooks for webbing have generally been focused on reducing the rod diameter to an absolute minimum value considering current security regulations as well as maximising the structural strength of the material by suitable choices of material and refining the hardening and finishing methods. However, these attempts have not in practice led to any radical cost reductions.

Objects and Features of the Invention

The present invention aims at reducing the material consumption in connection with the manufacture of hooks for webbing of the above-mentioned type, and thereby lowering the total cost of the production of the same significantly. Thus, a primary object of the invention is to provide a hook for webbing, which, by the geometrical shape thereof, allows the use of minimal quantities of rod material for a given load capacity. Thus, for a hook for webbing with a predetermined load capacity, a rod blank having considerably smaller cross-section than a corresponding round rod blank in conventional hooks should be possible to use, without the proper hook part tending to straighten out at maximum load. A further object is to provide a hook for webbing the cross piece of which does not run the risk of sagging or deforming when the webbing together with the hook are subjected to maximum load.

According to the invention, at least the primary object is attained by the features defined in the characterizing clause of claim 1. Preferred embodiments of the invention are furthermore defined in the dependent claims.

Further Elucidation of Prior Art

By FR 2 526 502 a hook is previously known which includes two partially curved lower parts which are interconnected and one of which is situated on top of the other one. However, said hook is intended to be fastened on walls and is composed of two separate components in the form of wide flat bars which in upper portions thereof are interconnected via a third component in the form of a sleeve. Therefore, this hook construction is not at all suitable for ^"application on webbing and, what is more, it is expensive to manufacture due to the mere fact that it has to be composed of several different components .

Brief Description of the Appended Drawings In the drawings : Fig 1 is a perspective view showing a hook according to the invention viewed obliquely from the front, Fig 2 is a front view of the hook according to figure 1, Fig 3 is a side view of said hook,

Fig 4 is a perspective view of the hook viewed obliquely from the back, Fig 5 is a perspective view corresponding to figure 1 showing an alternative embodiment of the hook, Fig 6 is a front view of the hook according to figure 5,

Fig 7 is a partly cut side view of the hook according to figures 5 and 6 , Fig 8 is a planar view from above of the hook according to figures 5 to 7, Fig 9 is a cross-section A-A in figure 7,

Fig 10 is a perspective view showing another alternative embodiment of the hook according to the invention, Fig 11 is a side view of the hook according to figure 10, Fig 12 is a cross-section A-A in figure 11, and Fig 13 is a cross-section corresponding to figure 12 showing yet another alternative embodiment of the hook according to the invention.

Detailed Description of Preferred Embodiments of the Invention The hook illustrated in figures 1 to 4 is made in one single piece from an elongated blank, viz . in the form of a metal rod, which has been bent to the shape shown. In the present embodiment, the rod blank consists of a genuine round rod, i.e. a rod that initially has a circular cross-sectional shape along the entire length thereof. After bending, the hook includes an upper cross piece 1 for receipt of a webbing (not shown) . At opposite ends the cross piece transforms into two legs or side pieces 2, 2' converging therefrom. Together with the cross piece these legs form a substantially triangular loop part, generally designated 3. The lower ends of the legs 2, 2¹ in turn transform into two curved rod portions 4, 4', which together form a lower hook part, generally designated 5.

The expressions "upper" cross piece and "lower" hook part, respectively, are in this description and the following claims solely used for the purpose of achieving a simple terminology without any connection to the use of the hook in practice. Accordingly, it is obvious that the hook in practical use can take any possible position in space, e.g. with the hook part turned upwards and the cross piece turned downwards.

Characteristic of the present invention is that one of the two curved rod portions 4, 4', viz . the portion 4 is located on top of the other rod portion (4') and fixedly joined thereto while forming an integral hook part having a moment of inertia which is larger than the sum of the individual moment of inertia of the two portions 4, 4' . In a preferred embodiment, the two arc rod portions 4, 4¹ are mutually joined by welding. Thus, in the example given it is shown how the rod portions in question are interconnected by three spot welds 6, 6', 6" of which two may be placed on one side of the hook part and a third one on the opposite side of the hook part, preferably in an area approximately in the middle between the two opposite welds 6, 6¹. In practice, the rod blank of which the hook is made may consist of steel of a suitable quality, and therefore welding may be effected by means of conventional, simple methods.

In the embodiment shown in figures 1 to 4 , the hook part 5 extends substantially perpendicularly out from the plane of the loop part 3, although other angles than exactly 90° are possible. The two curved rod portions 4, 4' may advantageously be mainly equally long. However, by the fact that the lower portion 4 ' has a larger bending radius than the upper portion 4, the last-mentioned rod portion will protrude a distance with its outer end 7 from the corresponding outer end 7' of the lower rod portion 4 ' .

Concerning the embodiment shown in figures 1 to 4 it should in conclusion be pointed out that this hook is primarily intended for comparatively narrow webbing, e.g. with a width of 30 mm. The cross piece 1 will then have a corresponding, rela- tively limited length counted between the inner edges 8, 8' of the V-shapedly bent rod portion of the loop part.

The advantage of the hook according to the invention is that the dimensions, and thus the weight of the rod blank, may be radically reduced as a consequence of the fact that the moment of inertia or flexural rigidity of the hook part in a critical section in the area of the bottom of the hook part will be many times larger than the corresponding moments of inertia for two individual arc rod portions which are placed next to each other side by side. Calculations show that a certain rod diameter which is required for a given loading capacity of a conventional hook for webbing having two collateral arc rod portions in the hook part, may be reduced by around 26 % in the hook according to the invention while maintaining one and the same loading capacity. Therefore, in case one and the same material is used in the two cases, the weight of the rod work piece may be reduced by around 46 %. This in turn leads to considerable cost savings in connection with the production. It will also be gained that the low dead weight of the hook facilitates the handling thereof as well as storing and transportation. In addition, by reducing the rod diameter, the production capacity may be increased by the fact that the times for heating the hook to a hardening temperature will be reduced on a level with the material reduction. Reference is now made to figures 5 to 9 which illustrate an embodiment intended for wider webbing, e.g. webbing having the widths of 50 and 70 mm, respectively. In order to avoid that the reduced rod diameter enabled by the increase of the moment of inertia in section A-A, obtained according to the invention, should lead to the effect that the comparatively long cross piece 1 becomes too weak, special measures have been taken. Thus, at least a central portion of the cross piece has been given a flattened shape, more precisely along opposite, plane outer areas designated 9. Therefore, the central portion of the cross piece has got a cross-section height, which is larger than the width, as may be clearly seen in figure 7. Advantageously, the flattening is effected in such a way that the geometrical normal or major axis of the flattened portion is obliquely inclined relative to the legs 2, 2' , more pre- ω ω IO to — o o o

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Claims

1. Hook for webbing, comprising a metal rod bent in a single piece having an upper cross piece (1) intended for receiving a webbing, said cross piece transforming into two legs (2, 2') which converge from opposite ends thereof so as to form a loop part (3) together with the cross piece and which in turn transforms into two curved portions (4, 4¹) which together form a lower hook part (5) c h a r a c t e r i z e d in that one curved rod portion (4) is located on top of the other one (4') and fixedly joined thereto while forming a hook part (5) having a moment of inertia which is larger than the sum of the individual moments of inertia of the two curved rod portions.

2. Hook according to claim 1, c h a r a c t e r i z e d in that a central portion (9) of the cross piece (1) has a cross-section-wise larger height than width and is, with the geometrical normal or major axis thereof, obliquely inclined relative to the legs, more precisely into a plane of forces extending towards the hook part (5) .

3. Hook according to claim 2, c h a r a c t e r i z e d in that the cross piece (1) has a straight lower edge (11) .

4. Hook according to any one of claims 1 to 3 , c h a r a- c t e r i z e d in that the hook part (5) is situated in a plane extending perpendicularly to the plane of the loop part (3) .

5. Hook according to any one of claims 1 to 3 , c h a r a- c t e r i z e d in that the hook part (5) and the loop part (3) are situated in a common plane.

6. Hook according to any one of the preceding claims, c h a- r a c t e r i z e d in that the two curved rod portions (4, 4') are interconnected by welding (6) .

7. Hook according to any one of the preceding claims, c h a- r a c t e r i z e d in that the two curved rod portions (4, 4') are mainly equally long, whereby an outer end (7) of the upper rod portion protrudes a distance from the corresponding outer - end (7') of the lower rod portion.

8. Hook according to any one of the preceding claims, c h a- r a c t e r i z e d in that said hook is made of a round rod as a blank and that the cross piece (1) is flattened by machining in order to give the rod material said larger height than width .

9. Hook according to any one of claims 1 to 7, c h a r a ct e r i z e d in that said hook is made of a blank in the form of a rod having an elongated round cross-sectional shape.

10. Hook according to claim 9, c h a r a c t e r i z e d in that the cross piece is, by machining, at least partially turned relative to the legs in order to locate the geometrical major axis of the rod cross-section in said plane of forces.