US3508408A - Supporting cushions - Google Patents

Description

Apu-i128, 1970 11u-:JEUNE l 3,508,403

SUPPORTING CUSHIONS FIiled July 18. 1968 2 Sheets-Sheet 1 F/G. /B

DANIEL LEJEUNE 5 F G. 5 l INVENTOR.

his TTORNEYS April 28,` 1970 D. LEJEUNE 3,508,408

' SUPPORTING cusHIoNsv Filed July 18, 1968 2 sheets-sheet a INVENTOR. DANIEL LEJEUNE BY MM,W4W*

his ATTORNEYS United States Patent O Inf. c1. E21d15/44, 19/00 U.S. Cl. 61-45 9 Claims ABSTRACT OF THE DISCLOSURE A pneumatic cushion for shoring up the roof of a coal mine or the like has two plies of oblique reinforcingl textile cords extending helically therearound, the cords being wound in opposite senses. The cords form an angle with the longitudinal axis of the cushion greater than 54 and preferably about 70. An additional ply of longitudinal metallic cords is provided at the lower surface of the cushion.

BACKGROUND OF THE INVENTION The present invention relates to improvements in pneumatic supporting cushions intended to support, in cooperation with a wooden or metallic framework, the roof of underground galleries.

It has been proposed that the support of mine galleries could be assured with the help of pneumatic cushions resting on metal or wooden frames spaced apart regularly. The cushions are arranged in the manner of roof tiles, covering one another in part and each resting on two successive frames. Support by pneumatic cushions offers the advantage of supplying a protective cover which hugs the necessarily irregular for-m of the gallery ceiling and which supports such ceiling over almost its entire surface.

However, it may happen that a block becomes detached from the gallery ceiling and exerts on the cushion with which it is in contact a pressure such that such cushion becomes considerably depressed, especially if the stressis exerted between two successive frames. Under these circumstances, the cushion loses a considerable part of its capacity to resist the load, a capacity which is substantially higher if the load is more evenly distributed over all of its surface.

In order to prevent or reduce the deflection or sagging of a pneumatic cushion, it has been proposed to combine it with one or more straps or webbings. However, this solution is inconvenient, inasmuch as it requires that the strap be tautly stretched in advance in order to be effective.

SUMMARY OF THE INVENTION An object of the present invention is to remedy the disadvantages outlined above and to give supporting cushions such a structure that their resistance against bending increases in the desired direction under the effect of pressure.

As used herein, the longitudinal direction of a pneumatic supporting cushion is that direction which is intended to run perpendicularly to the frames serving as supports of the cushions in the gallery; i.e., the direction parallel to the gallery. Ordinarily, the cushions have an oblong shape and the longitudinal direction is the direction of the largest dimension. Of course, the upper surface of a cushion is understood to be the surface intended to be in contact with the roof of the gallery, while the lower surface, consequently, is the opposite surface, resting on the frames.

Fice

A pneumatic supporting cushion in accordance with the invention is characterized by a reinforcement cornprising plies of cords or wires which are continuous from one side of the cushion to the other. The cords of one ply are crossed with respect to those of the following one, and the cords of both plies form with the longitudinal direction of the cushion an acute angle greater than 54; for example, ranging from 60 to 85, and preferably close to 70. The cushion is further characterized, on its lower surface, by a ply of wires or cords which run parallel to the longitudinal direction or form a small angle with it.

If pressure is exerted on the upper surface of a cushion in accordance With the invention, the lower surface of the cushion has a tendency to elongate, whereby the ply of longitudinal wires or cords is put under tension. The greater the pressure exerted, the greater becomes the tension of the longitudinal wires. Further, the difference in rigidity between the upper and lower surfaces results in that the cushion, when it is inflated, assumes a curved shape, the upper surface having a greater elongation than the lower in a longitudinal direction.

In a preferred embodiment of cushions in accordance with the invention, the reinforcement comprises an even number of plies of wires or cords wound helically around the longitudinal axis of the cushion, one of the pairs in one direction, the other one of the pairs in the other direction, in addition to the ply or plies of longitudinal wires. Preferably, the cushion in that case has the shape of an elongated hexagon two sides of which form the longitudinal edges of the cushion and the other four sides of which, two at each longitudinal end, are parallel to the oblique wires of the reinforcing plies. In this arrangement it is sufficient to reinforce the longitudinal edges of the cushion. Furthermore, on inflation, the two triangles forming the longitudinal ends of the cushion have a tendency to assume an almost perpendicular position with respect to the lower surface.

Preferably, the cords of the reinforcing plies arranged obliquely consist of some comparatively elastic material, or are rendered elastic by cabling so that they can extend considerably and bacilitate the longitudinal elongation of the upper surface of the cushion. Onevmay use rayon,

polyamide or polyester cords, or also elastic metal cords. or glass cords. On the other hand, the longitudinal cords of the reinforcement consist preferably of some material that is rigid and has high tensile strength, and they have only a limited ability to extend. One may use, for example, metalcords of the kind used currently in the reinforcement of crown plies of tires. The combined use of textile and metal wires, i.e., extensible together with practically inextensible wires or cords, enables one to obtain an upper cushion surface which is remarkably pliable while the lower surface is rigid.

The various plies are relatively widely spaced apart from one another in the lower surface, and in contrast thereto, are relatively close to one another in the upper surface of the cushion so that an increased rigidity differential is obtained in the two surfaces. v

The use of flexible textile wires in combination withv BRIEF DESCRIPTION OF THE DRAWING Additional aspects of the invention will be fully understood by reference to the following detailed description of a representative embodiment thereof, in conjunction with the attached drawings, wherein:

and elevational vie'ws of a cushion in accordance with v the invention;

FIGURE 2 is a cross section on a larger scale and in greater detail through line 2n-2, looking in the direction of the arrows, of the cushion in accordance with FIGURE 1A;

FIGURE 3 is a plan view of one of the plies of oblique wires of the cushion in FIGURES 1A, 1B, and 2, the other plies and the elastomer being omitted for clarity;

FIGURE 4 is a plan view of the ply in FIGURE 3 before folding;

FIGURE 5 is a plan view of the ply of longitudinal cords of the cushion in accordance with the invention, the other plies and the elastomer being omitted for clarity;

FIGURE 6 is a plan view of -one of the reinforcing plies of a cushion end in accordance with the invention;

FIGURE 7 is a plan view of the ply in FIGURE 6 prior to folding;

FIGURE 8 is an elevation of a cushion according to the invention, inated and bearing a load in the middle; and

FIGURE 9 is a view analogous to FIGURE 8 showing the cushion inated but without load.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGURE 1A shows a cushion 10 made of rubber, of elongated hexagonal shape as seen from a position above the upper surface. FIGURE 1B shows the same cushion not inflated, with its upper surface 11 and an inflating valve 13 and a safety valve 14 on its lower surface 12. The length of the cushion ranges from 1800 mm. to 2500 mm., its width from 800 mm. to 900 mm.

FIGURE 2 is a cross section of the structure of the cushion 10. There are two layers or plies 20 and 21 of textile threads which are relatively close to each other along the upper surface 11 and which, in contrast thereto, are relatively widely spaced apart along the lower surface 12. 'I'he wires consist, for example, of high'tenacity rayon cords of 3 strands, 1650 deniers. The reinforcement of the cushion comprises, furthermore, a ply of longitudinal metal wires 25 about at mid-distance from the textile reinforcement and the lower surface 12. The plies 20, 21 and 25 are imbedded in the rubber forming the cushion.

FIGURE 3 shows one of the plies 20 or 21 in the form it assumes in the cushion 10. The angle alpha of the textile cords 30 ranges from 56 to 85 and is close to 75 in the figure. The pitch P, i.e., the distance between the connecting lines 32 in the upper or the lower surface,

is from 400 mm. to 600 mm. FIGURE 4 shows the,

same ply before folding and helicoidal winding. The cords 30, the edges 32 which will form the connecting lines, and folding lines 33, which form the sides of the completed cushion, are all visible. The winding pitch P is thel 20 and 21. They are arranged in a manner whereby the same angle alpha is formed with the longitudinal direction, at least in the part 72 which is not folded back.

FIGURES 8 and 9 respectively show the cushion 10 loaded and unloaded. Application of a load, for example the rock 15, on the upper surface 11 changes the form of the lower surface 12. The latter, curved concavely when the upper surface is not loaded, becomes plane and stretched due to the load 15.

I claim:

1. A pneumatic supporting cushion for mounting on spaced-apart support members and shoring up the roof of a mine or the like, said cushion having an upper surface, a lower surface, and a longitudinal axis extending between said support members and comprising at least two plies of oblique reinforcing cords extending continuously from one of said surfaces to the other, the cords of one ply being crossed with respect to the cords of the other ply and t-he cords of each ply forming with the longitudinal direction of the cushion an angle greater than 54, and an additional ply of cords on said lower surface, the cords of said additional ply extending in a substantially longitudinal direction, so that said upper surface is better adapted to conform to an irregular surface than is said lower surface and said lower surface is more resistant to elongation than is said upper surface.

2. A cushion according to claim 1 wherein said angle ranges from 60 to 85.

3. A cushion according to claim 1 wherein said angle is about 4. A cushion according to claim 1 wherein said plies of oblique cords are |wound helically around said axis and extend without interruption from one end of said cushion to the other.

5. A cushion according to claim 1 wherein said cushion has the shape of an elongated hexagon having two elongated longitudinal edges, the other four sides being two by two respectively parallel to said oblique cords.

6. A cushion according to claim 5 further comprising supplementary plies reinforcing said other four sides.

7. A cushion according to claim 1 wherein said oblique cords are relatively extensible and said longitudinal cords are relatively inextensible.

l8. A cushion according to claim 7 wherein said oblique cords are formed of textiles and said longitudinal cords are formed of metal.

9. ,A cushion according to claim 1 wherein said oblique cords are relatively widely spaced apart from each other at said lower surface and relatively close to each other at said upper surface.

References Cited UNITED STATES PATENTS 705,176 7/1902 Wheeler et al 152-354 X 2,985,214 5/1961 Lugli 152-361 X 2,990,166 6/1961 Walsh 299-33 X FOREIGN PATENTS 876,872 9/ 1961 Great Britain. 1,448,299 6/ 1966 France. 1,094,216 12/ 1960 Germany. 1,118,120 11/1961 Germany.

DENNIS L. TAYLOR, Primary Examiner

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