MXPA99010619A - An elastomeric composite structure - Google Patents

Abstract

An elastomeric composite structure (45) having two arrays of parallel cords (41, 43), each array of cords (41, 43) being of different modulus or percent elongation. The array of cords (41,43) are spaced and provide different bending stiffness dependent on the direction of the applied load.

Description

COMPOSITE ELASTOMERIC STRUCTURE TECHNICAL FIELD This invention relates to rubber articles reinforced with ropes.

BACKGROUND OF THE INVENTION Reinforced elastomeric materials with parallel layer arrays juxtaposed to obtain increased tensile strength are well known in the art. Power transmission belts, as described in U.S. Patent No. 5,244,436 to Kurokow, are an example. This patent describes a belt v consisting of a plurality of longitudinally extending load carriers or load carriers, embedded in a rubber adhesive layer; a compression section "having a plurality of laterally extended cords, embedded in a second rubber layer; and a rubber reinforcing layer interposed between these layers to maintain a space between and thereby prevent inadvertent contact between the laterally extended cords and the supporting cords. Other products such as conveyor belts, tires and hoses are in the same way reinforced with ropes. U.S. Patent No. 3,607,592 discloses a portable rubber platform having a layer of 3 and 6 rubber-coated steel cords separated by a layer of transverse textile elements to obtain longitudinal stiffness in one direction. This invention relates to portable platforms suitable for use, for example, as temporary bridges, service walkways and other corridors, and temporary roads on non-firm terrain or swamps. According to this invention, a portable platform consists of a flexible composition that has a composite reinforcement embedded therein comprising a textile reinforcement together with at least two layers of virtually inextensible, transverse, individually flexible metal cords, the metal cords in each case. layer remaining substantially parallel to each other and substantially at right angles to the length of the platform, the separation of the metallic, transverse cord layers being sufficient to confer a substantial degree of transverse stiffness to the platform as a whole, and a textile constituent interposed of the composite reinforcement being placed between each layer of transverse metal cords and the layer of adjacent transverse metal cords. According to one aspect of this invention, a portable platform as described above had a composite reinforcement including a layer of substantially longitudinal, substantially inextensible metal cords, substantially parallel to each other and to the length of the platform, this layer of metal cords longitudinals being placed between an interposed textile constituent of the composite reinforcement and the layer of transverse metal cords that is closer to the load carrying surface of the platform. The longitudinal metal cords were continuous or discontinuous. When they were discontinuous, they could be in parallel relation, superimposed on each other. The discontinuous metal cords may be of any convenient length. Normally the metal strings are steel strings. The steel cords preferably had a percent extensibility of less than 5%. Suitable ropes are composed of interwoven strands of steel wire; for example, the cords can be composed of 6 to 24 steel wire strands of approximately 0.001 to 0.010 inch diameter. The strings were usually arranged in side by side relationship and could be properly arranged at a density of 8 to 24 strings per inch. Preferably, the composite reinforcement consisted of two layers of transverse steel cords with a single layer of textile reinforcement between them, and a layer of longitudinal steel cords placed between the textile layer and one layer of the transverse steel cords that are finds closest to the cargo carrying surface of the platform. This invention of the prior art provides a portable platform that can be constructed simply by applying moderate tension, for example, approximately 50-80 pounds per inch from the supports at the ends. The platform has a remarkable transverse rigidity, so that edge flexing does not occur to any undesirable degree when a person or vehicle remains on or moves along the platform with the weight acting on the edges of the platform, and so that the torsion of the platform is limited. The platform can be rolled and transported in convenient rolls. In addition, the layer of longitudinal metal cords on textile reinforcement gives longitudinal stiffness with respect to the loads that act down on the load-bearing surface of the platform. The longitudinal, continuous metal cords also add tensile strength to the platform, whereas, when longitudinal, discontinuous metal cords were used, although these provide longitudinal stiffness to the platform, the tensile strength is then provided only by the textile reinforcement. Due to the virtually inextensible nature of the metal cords, longitudinal bending can not occur even when the metal cords are discontinuous, unless the textile reinforcement below the longitudinal, discontinuous metal cords is appreciably stretched, which requires considerable force. However, the platform can be easily rolled up with the load bearing surface on the outside in the roll, because the bending of the platform in this direction simply requires circumferential compression of the textile reinforcement - down the non-stretchable metal cords. The present invention described herein has discovered a novel and useful way to create a composite structure that has a difference in flexural stiffness created by a change in the modulus between two different arrangements, separated from parallel cords or by a c " I adjust the percentage of elongation of the strings.

SUMMARY OF THE INVENTION A composite, elastomeric reinforced rope structure 45 has a first external surface 42 and a second external surface 44. The first and second surfaces 42, 44 are spaced apart. Within the elastomeric structure 45 are two different arrays of parallel strings 41, 43. The first array of parallel strings 41 has a first module E of X. The second array of parallel strings 43 has a second modulus E greater than X, preferably approximately 10 GP1. The cords 41, 43 of the first and second array are encapsulated in the elastomeric material. The strings 41, 43 of both arrays are practically parallel and separated from the other array. The first string arrangement 41 is located near the first surface 42, while the second string arrangement 43 is located near the second surface 44. The composite structure 45 has a bending stiffness transverse to the arrangement of the strings 41, 43 and generally normal to the first and second surfaces 42, 44 in one direction greater than in the other. The number of strings 41 of the first array may be greater than, the same or less than the number of strings 43 of the second array. The strings 43 of the second array of preference are practically non-extensible and have a percentage of elongation under load less than the strings 41 of the first array.

BRIEF DESCRIPTION OF THE DRAWINGS Figures IA and IB show the composite structure being transversely loaded in each of the first and second surfaces, respectively.

Figures 2A, 2B show cuts of a tire, using the composite structure of the inventive. Figures 3A, 3B and 3C show the structures of the composite side walls in a schematic view of the tires of Figure 2A, 2B and a prior art tire.

Detailed description of the invention. For a better understanding of the concept of inventiveness, a composite structure of the test sample 45 was constructed, as shown in Figures IA and IB. For simplicity, the rubber layers were all of the same type with the same properties. The parallel reinforcing cords 41 were placed at a depth of DI of 3.1 mm and were rayon strings with a modulus of 13 GPa and had an end-per-inch count (epi) of 30. The parallel reinforcement cords 43 were steel cords of a construction 1 + 5x .18 mm at 18 epi and were oriented parallel to the strings of rayon 41 and were embedded in the rubber separated at a distance D2 of 6.34 mm from the strings of rayon 41, the steel strings 43 also being at a distance D3 of 8.32 mm from the bottom of the sample 45. The test sample 45 had a test length or length at load points of 152.4 mm and a width of 38 mm. The thickness was the sum of DI, D2, D3. The rectangular test sample 45 was first loaded as shown in Figure 1A and a 10 mm bending was recorded with a load of 64N (newtons). Sample 45 was then loaded as in Figure IB, the inversion of the upper and lower loads in the resulting bending at 10 mm required a load of 136N (newtons). A second test sample identical to the first sample, but with only two layers of rayon strings 41 was loaded as in Figure IA, with the resulting charge only 20N (newtons). The sample with all rayon layers 45 is similar to prior art structures. This test showed that a composite with two layers of very different module cords can give rise to a large difference in flexural rigidity depending on the direction of the load. The loading in Figures 1A and IB created tension or compression of the cords 41, 43 depending on the direction in which the load was applied. The application of this principle was then treated for a test tire of one size P235 / 55R17. tire 100 of Figure 3A with the prior art tire similar to tire 10 of Figure 2A, but having only rayon strings in layers 380, 400 was used as a control tire. The tire of the same construction and size was tested in the construction of Figure 3B, where the strings 43 of the layer 40 were the 1 + 5x.l8 mm strings with an epi of 18 were radially outward from the rayon strings 41 of layer 38 which was the same as layer 380 of the prior art tire. All other construction materials were the same for the control tire 100 and the first test tire 10. The control tire with rayon layers 100 had an effective elastic rate at 26 psi of 1516 pounds / inch, at 35 psi an elastic rate of 1787 pounds / inch. The first test tire had an elastic, inflated rate with 26 psi of 1541 lb / in and at 35 psi a rate of 1816 lb / inch. At 0 psi of inflation the elastic rate of the first test tire was 773 pounds / inch. A second test tire was constructed, where the rayon strings 41 were placed in the layer 40, and were radially outward from the steel strings 43 of the layer 38, as shown in Figure 3C. This second test tire had elasticity rates at 26 psi 35 and psi of 1557 and 1847, respectively. At inflation 0, the elasticity rate of the second test tire was 789 pounds / inch. As can be seen from the application of the concept, the string arrangement 41 does not need to be uniformly placed from the string arrangement 43 to obtain the flexural rigidity differential, however, the location of the maximum spacing will achieve or it will be the location of the maximum rigidity. As will also be appreciated, the axis of flexion A of the structures is located closer to the strings of higher module. Although certain representative embodiments and details have been shown for the purpose of illustrating the invention it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

Claims (3)

1. A composite structure consisting of: an elastomeric structure, the structure having a first external surface and a second external surface, the second external surface being separated from the first external surface; a first arrangement of parallel strings with a first module E of X, and a second arrangement of parallel strings with a second module E greater than X, the strings of the first array and the second array being encapsulated in the elastomeric material. The strings of both arrays being practically parallel and separated from the other arrangement, the first string arrangement being closer to the first surface, and the second arrangement being closer to the second surface; and wherein the composite structure has a flexural stiffness transverse to the string arrangement and in relation to the first and second surfaces is greater in one direction than in the other.

2. The composite structure of claim 1, wherein the number of strings of the first array is greater than the number of strings of the second array.

3. The composite structure of claim 1, wherein the strings of the first array have a percent elongation greater than the strings of the second array.