Reinforced Opening

The provision of reinforcing rings around openings in sheet material and, in particular, to sail cloth is old in the art as shown in U.S. Pat. Nos. 3,653,353; 3,683,844; 3,812,809; 3,979,798; and 3,890,695. It is the purpose of this invention to improve upon the structure shown in the aforesaid patents by providing a structure which will distribute the load as efficiently as any structure shown in the aforesaid patents, but which will be less prone to cracking and stripping under strain, which will be much lighter in weight, which can be made of a material which will not corrode and which will be less expensive to manufacture.

As herein illustrated, the cringle structure is designed especially for sails; however, it is equally useful for tarpaulins, awnings, tent material and like sheet material and comprises a ring positioned about the opening at one side of the material with a width of the material bounding the opening folded from said one side through the opening and outwardly about the ring, said ring enfolded by said width of material at the edge of the opening constituting a bead bounding the opening and a liner positioned within the opening bounded by the bead with portions folded symmetrically outwardly over the surfaces of the bead at opposite sides into clinching engagement with the opposite surfaces of the sheet outwardly of the bead. The ring is substantially incompressible, is desirably of a cross section such as to provide edges running peripherally thereof, may be comprised of high-impact plastic or metal and is of larger diameter than the opening. The tubular insert is of such smaller outside diameter that when placed within the ring, there is a clearance between the ring and the liner corresponding substantially to the thickness of the material bounding the opening. The sheet material in the area of the opening may optionally be of multi-ply construction.

In another aspect, invention resides in the method of inserting a cringle in sheet material such as sail cloth comprising forming an opening in the material, positioning a rigid ring at one side of the material about the opening, folding the material bounding the opening from the one side through the ring and about the ring at the opposite side, positioning a tubular liner element within the opening and folding the protruding ends of the tubular liner element outwardly about the enfolded ring into frictional engagement with the opposite sides of the material bounding the opening. In accordance with the method, the opening is of smaller diameter than the inside diameter of the ring and the material bounding the opening is radially slitted so that the locus of the extremities of the slits define a circle of a diameter corresponding substantially to the inside diameter of the ring.

The invention will now be described in greater detail with reference to the accompanying drawings, wherein:

FIG. 1 is a plan view of a portion of the sail provided with a cringle attachment according to this invention;

FIG. 2 is a sectional view taken on the line 2--2 of FIG. 1;

FIG. 3 is a plan view of a ring member;

FIG. 4 is a diametral section of the ring member shown in FIG. 3;

FIG. 5 is a plan view of a liner sleeve;

FIG. 6 is a diametral section taken on the line 6--6 of FIG. 5;

FIG. 7 is a plan view of a portion of sheet material showing the initial step in preparing for applying the cringle;

FIG. 8 is a section taken on the line 8--8 of FIG. 7;

FIG. 8A is a section showing a multi-ply construction in the area of the cringle;

FIG. 9 is a plan view simular to FIG. 7 showing a second step in installing the cringle;

FIG. 10 is a section taken on the line 10--10 of FIG. 9;

FIG. 11 is a section similar to FIG. 10 showing the initial step in folding the lining outwardly; and

FIG. 12 is an elevation showing the final step of folding the liner into engagement with the opposite surfaces of the material.

Referring to the drawings, FIG. 1, there is shown in plan a portion of a sail 10 or other sheet material to which a cringle 12 is applied according to this invention. The cringle may be applied at any appropriate point and, desirably, in the area where the cringle is applied, the material is of multi-ply thickness.

As illustrated in FIG. 2, the cringle comprises a core ring 14, a bite 16 of the material of the sail folded from one side of the core ring through the ring and about the other side and a liner 18 positioned within the opening with portions 20 and 22 folded over the ring 14 into clinching engagement with the opposite sides of the sail material.

The core ring 14, FIGS. 3 and 4, is comprised of a rigid, high-impact plastic of rectangular cross section; however, it is to be understood that it can be made of metal. Desirably, the core ring 14 is sufficiently rigid so that it does not become deformed substantially under compression and so that the edges 24 remain sharp.

The liner 18, FIGS. 5 and 6, is a tubular sleeve comprised of stainless steel or its equivalent.

The cringle is assembled as follows. First, as shown in FIG. 7, an opening 26 is formed in the sail cloth through the several plies together with a plurality of circumferentially-arranged, radially-extending slits 28. The core ring 14 is now placed on the sail cloth in concentric relation to the opening 26 as shown in FIG. 9 and the portions 30 defined by the slits 28 are folded through the core ring as shown in FIGS. 9 and 10. The liner sleeve 18 is now placed in the opening 26 defined by the upwardly-folded portion 30. The outside diameter of the liner sleeve 18 is smaller than the inside diameter of the ring 14 by an amount corresponding to the thickness of the material of the sail. The protruding ends 32--32 of the liner sleeve are now folded outwardly and downwardly as shown in FIG. 12 by dies 34--34 to bring the end edges of the sleeve into clinching frictional engagement with opposite sides of the sail cloth.

By making the core ring 14 of a rigid, substantially incompressible material so that the edges 24--24 remain unblunted when the liner is folded about the enfolded ring and applying sufficient pressure, the edges 24--24 become embedded in the material of the sail folded about the core ring so as to produce a high degree of frictional resistance to slippage.

Desirably, the area or areas which are to be reinforced with the cringle structure thus described may be provided with one or more plies 36 at one or both sides, FIG. 8A, as by stitching 38.

An advantage of the structure herein described resides in the fact that the parts need not be precast as are the parts which comprise the makeup of some of the cringles shown in the prior art, which parts are apt to crack under pressure and may be made up of stainless steel which is particularly resistant to corrosion. Furthermore, since the core ring itself is comprised of plastic and the liner of stainless steel and, therefore, need not be of such heavy gauge as is required in the making of castings, the entire cringle is relatively light in weight, which becomes an advantage where the rings are large and a number of rings are used.

It is to be understood that while the cringle is designed specifically for sails, it is equally useful for reinforcing holes in other sheet material such as tarpaulins, awnings, tent material and the like.