MXPA99008838A - Ply path controlled by precured apex - Google Patents

Abstract

A tire (10) having a contoured precured bead filler or apex (40) with a contoured surface (42) for directing the ply path (24A) of the cord reinforced carcass plies (24) is taught. The contour of the precured bead filler or apex (40) has a convex surface (42A) and concave surface (42B) that transition at an inflection location (T) at or below the rim flange (52) to which the tire (10) is to be mounted.

Description

TECHNICAL FIELD This invention relates to a radial layer tire having a predetermined rope layer trajectory, Prior Technique Tire manufacturing engineers have historically established the contours of tires when constructing a mold having a predetermined contour, placing raw or uncured tires with predetermined amounts of rubber or rubber on both sides of the reinforcing layers in the mold, expanding the tire against the mold, using an inflatable bladder and then applying heat and pressure to cure the tire. The mold is constructed with an annular strip forming rings constituting the contour of the bead portion 200 of the tire 100. These bead rings have a molding surface that generally approximates the contour of the edge on which the tire 100 will adjust. The layer 210 is anchored in the bead cores 200 and conventionally in tires of the prior art 100, has a working layer path between the core of heel 200 and the bundles of bands 140. In the lower portion of the tire, the bead core and the lip flange limit the amount of movement that the layer cords 210 can take. In the upper portion of the tire circumferentially extending the bundle of bands limits the radial growth of the layer. At a site just below the side edges of band 150, the layer cords when tensioned take an outline that approximates a single radius of curvature RUP. This simple radius of curvature RUP is usually referred to as the "neutral layer line". This simple radial contour can only be maintained at a point as illustrated in Figure 1. If the contour defined by RUP is maintained further, a very steep curve extending axially at a location well above the flange of the lip is achieved. a tire lip for conventional truck. Ideally, we would like to optimize the string layer path. A recent description entitled "Tire With Reduce Bead Mass" (Tire with Reduced Heel Mass), is described in US Pat. No. 5,526,863. It is suggested that a reduced heel mass can be achieved as much as 15% using a small vertex with an outer component with elongated constant thickness and an axially large outer filling component. The patent of the U.S.A. No. 5,526,863 shows the addition of a massive amount of rubber axially outward from the surrounding layer portion. This in combination with the placement of the surrounding portion of the axially inward layer adjacent to the radially outer location of the lip flange / effectively allows the surrounding layer portion to move toward the lower layer curvature on the lip flange, such that the space between the surrounding layer portion and the layer path is a constant T from a distance Fl a below a site F2. This prior art tire has a slight improvement or reduction in tire mass with a corresponding reduction in rolling resistance. The performance of the route was better or worse, depending on the total physical modality tested. The corner and radial rigidity is degraded with the lower dynamic spring ratio. The capacity for high speed also worsened. This inventor seems to believe that the lighter weight benefits outweigh the reductions in durability or performance.

An inherent problem in the aforementioned prior art tires is that the uncured rubber circulates during vulcanization, making the control of the layer path, rather unpredictable. A second and equally important problem is that the lower layer path must be altered to effectively anchor the bead core. This is particularly true of conventional flange-type lips. Those skilled in the art conventionally construct a groove fit between the upper wall neutral outline l and the lower side wall. The resulting slot occupies the region between the maximum section width and the location radially close to the bead flange. The slot adjustment has a very large radius of curvature that often approximates an almost linear segment. In this portion of the layer, the layer path deviates from the neutral layer path, shear stresses develop that can generate heat and degrade the rolling resistance and durability of the tire. The tire of the present invention has a layer path consisting of the lower side wall having very low stresses. This lower layer path contour is controlled by a Unique precured contoured vertex, which can minimize or even eliminate the use of a slotted fit. Description of the invention Compendium of the invention. A tire 10 is described for mounting on a rim of a vehicle. The tire 10 has a portion of the contact part with the floor 12, a bundle of strips 14, radially inward of the contact part with the floor 12, a pair of side wall portions 16, each extending radially towards in from a side edge 15 of the bundle of strips 14, a pair of beads 22 each having an annular bead core 20, and positioned radially inwardly of a respective sidewall portion 16, at least one housing layer 24 located radially inward of the bundle of strips and extending from bead 22 to bead 22. The carcass ply at least 24 has radially projecting parallel strings 24A and a pair of surrounding portion ends 26, an end of surrounding portion is wrapped around each bead core 20 and extending radially outward to an end point radially outwardly of a flange 52 of rim 50. Tire 10 has a pair of reel portions. heel ene 40 precuradas, a portion of filling of precured heel 40 is adjacent a radially outer surface of a bead core 20. Tire 10 is characterized by each pre-shaped bead filler 40 having an axial interior curvature 42. The axial interior curvature 42 is defined by a convex surface 42A and a concave surface 42B. The convex surface 42A projects radially outwardly from axially inwardly of the bead core 20 to an inflection location T, the location T being substantially in or radially inward from a radially outer surface of the rim flange 52. The concave curvature 42B extends from the inflection location T to a radially outer end 41 located at or below the radial location of a maximum section width of the tire 10. The axially inner surface curvatures 42A, 42B establish a string layer path 24A of the carcass ply 24 when the tire 10 is inflated and discharged normally. The layer path 24A extends from radially on the rim flange 52 to the side ends of the bundle of bands. The layer path 24A has a radius of curvature (RUP) between the lateral band ends at the radial location H of the maximum section width and one second RLP radius of curvature in the range equal to or greater than UPL, preferably 100% to 200% RUPI > , between location H and location T. The inflection location T may be at a point or may include a short slot having a mid point below the rim flange. Def nitions. "Ratio of dimensions" of the tire means the ratio of its section height (SH = Section Height) to its section width (SW - Section Width) / "Axial" and "axially" means lines or directions that are parallel to the axis of tire rotation; "Heel" means that part of the tire comprising an annular tension member wrapped by layered and shaped cords, with or without other reinforcement elements such as fins, reinforcing portions (chippers), vertices, eyelash protectors and plates (chafers) ), to fit the design rim. "Strip reinforcement structure" means at least two substrates of parallel string layers, woven or non-woven, underlying the floor contact portion, without anchoring the bead, and having both angles of left rope as right in the range of 17 degrees to 27 degrees, with respect to the equatorial plane of the tire; "Housing" means the structure of the tire apart from the band structure, part of contact with the floor, under the contact part with the floor and sidewall rubber on the layers, but including the heels; "Circumferential" means lines or directions extending over the perimeter of the contact part surface with the annular floor perpendicular to the axial direction; "plates" refers to narrow strips of material placed around the outside of the bead to protect the layers of rim strings, distributing flexure on the rim and to seal the tire; "reinforcing portions" means a reinforcing structure located in the bead portion of the tire; "Rope" means one of the reinforcing filaments of which the layers in the tire are constituted; "Design rim" means a rim that has a specified configuration and width. For the purposes of this specification, the design rim and the design rim width are as specified by the industrial standards in force at the location where the tire is produced. For example, in the U.S., the design tires are as specified by the Tire and Rim Association (Association of Tires and Rims). In Europe, rims are as specified by the European Tire and Rim Technical Organization - Standards Manual and the term design rim means the same as standard measurement rims. In Japan, the standard organization is The Japan Automobile Tire Manufacturerf s Association (The Association of Automotive Tire Manufacturers of Japan). "Equatorial plane (EP = Equatorial plane)" means the plane perpendicular to the axis of rotation of the tire and passing through the center of its part of contact with the ground; "Footprint" means the patch or contact area of the tire bead with a flat surface at zero speed and under normal pressure and load; "Inner lining" means the layer or layers of elastomer or other material that forms the inner surface of a tubeless tire and that contains the inflation fluid within the tire; "Net-to-gross ratio" means the proportion of rubber of contact part with the tire floor that makes contact with the road surface, while it is in the footprint, divided by the area of contact part with the floor in the footprint, including non-contact portions such as grooves; "Normal rim diameter" means the average diameter of the rim flange at the location where the bead portion of the tire rests; "Normal inflation pressure" refers to the specific design inflation load and pressure assigned by the organization of appropriate standards for the service condition for the tire; "Normal load" refers to the specific designed inflation load and pressure assigned by the organization of appropriate standards for the service condition for the tire; "Layer" means a continuous layer of parallel strings covered with rubber; "Radially" and "radial" means directions radially toward or away from the axis of rotation of the tire; "Radial ply tire" means a tire circumferentially constrained or with bands wherein the cords of layers extending from bead to bead are placed at rope angles between 65 degrees and 90 degrees with respect to the equatorial plane of the tire; "Section height (SH = Section Heigth) means the radial distance from the nominal rim diameter to the outer diameter of the tire in its equatorial plane, and" Section width (SW = Section Width) means the maximum linear distance parallel to the axis of the tire. pneumatic and between the outside of its side walls when and after it has been inflated at normal pressure for 24 hours, but without unloading, excluding elevations of the side walls due to labeling bands, decoration or protectors. BRIEF DESCRIPTION OF THE DRAWINGS The invention can be taken physically in certain parts and arrangement of parts in a preferred and alternate embodiment of which will be described in detail in this specification and illustrated in accompanying drawing that is part of it and where: Figure 1 is a schematic view of the half of a cross section of a tire and its resultant geometry as discussed herein. Figure 2 is an enlarged schematic view of the lower bead portion of the tire of Figure 1 and its resultant geometry. Figure 3 is a cross-sectional view of one half of a prior art tire. Figure 4 is a cross-sectional view of a line of neutral contour layers in a theoretical tire as described by Purdy. Figure 5 is a cross section of a bead portion of a theoretical tire as described by Purdy. Figure 6 is a cross-sectional view of the half of a tire made according to the invention. Figure 7 is a cross-sectional view of the half of a second embodiment of a tire produced according to the invention. Figures 8A and 8B are enlarged views of the cross sections of the heel core structures with precured vertex according to the invention.

Detailed description of the invention. In order to ensure a complete and complete understanding of the invention and an exemplary method of practicing this invention, a detailed description of how a person with ordinary skill can determine or develop a line of layers for a radial layer tire is discussed. For ease of understanding, Figures 1 and 2 describe abbreviations or initials that facilitate understanding, the initials are similarly referred to in the text that follows. For a given tire 10 of a particular size, it is initially considered that the mold (OD), section diameter (SD) and molded base width (MBW) are known. It is also considered that for the application of given tire, the calipers of floor contact part against skating (NSK), sub-part of contact with the floor (UT) and band gauges (BGA) and coating liner gauges Superior (TPC) have been determined, and critical specifications are known for mold ring diameter and bead profile, as well as bead diameter. The following dimensions and gauges are also known from a successful practice in the prior art, namely: side wall gauge (SWGA), gauge of rubber reinforcement portions, plate gauge, gauge of fin, layer termination height (PEH), layer-to-mold wire end gauge (T2) and layer-to-layer (TI) wire end gauge. It is considered that the width of the part of contact with the floor, radio of part of contact with the floor and bandwidth have been determined from standard practice methods. There are several methods to determine TAW. One such method is to use the molded base width +/- 5%. Once TAW is determined, the radius of the floor contact part can be determined from the following construction. An angled line is drawn at -5 degrees through the OD mold point. The intersection of this line and a vertical line in TAW forms a point that can be reflected with respect to the vertical axis. The radius of the contact part with the floor is a circle through these three points. The bands are then placed concentric with respect to the radius of the contact part with the floor. A mnemonic rule for maximum bandwidth is such that the caliber-to-mold in the widest band is .55 (direction, stroke), .60 (pulse). It is also considered that stepped belt displacements are known and that an extruded wedge is placed between the working bands.

It is considered that engineering calculations will be performed to verify required bead size, layer wire diameter and band wire diameter.

The calculations are normally made before determination of the neutral contour line. NEUTRAL CONTROL LINE CAN BE ESTABLISHED AS FOLLOWS: Five power parameters are required to specify a neutral contour layer line. These parameters are RC, YM, RB, YB and PR (shown in Figure 1). The parameters are sufficient to define a well-known mathematical curve from the point YS to the point (RB, YB). Purdy, JF "Mathematics Underlying the Design of Pneumatic Tires, Hiney Printing 1963, illustrates a theory or string tension that defines the neutral contour line for any tire.This neutral contour is as illustrated in Figure 4. Purdy establishes Chapter VI of his book "Bead Tension" (Heel Tension), that "In Chapters I and II, the string tension is defined for any tire such as t = -pp < ? m 2 -? 2) 1) N sin OE sin F and several terms of the equation were also defined. In the present case let N be the total number of strings in the v layers of a tire and p the inflation pressure. The component of the rope tension tangent to the contour of the tire and in a radial plane, is t sin and its component in the plane of any large circle of radius p is t sen OÍ eos p 2) This component of tension exerted by each rope of tire results in a force distributed evenly around a ring of radio P, such as the steel ring to which the layers of a tire are anchored and which serves as a means to hold a tire on a wheel or rim. If n equals the number of tire strings per 2.54 cm (1 inch) normally counted to the rope path, then in 2.54 cm (1 inch) of circumference of the radius ring p there are n sin to strings in each layer, so such that for v layers tnvp sin2 to eos F = Tb 3) where Tb is the tension in the heel or steel anchor ring as it is called. From 1) we can substitute the value of t and have Tb - P Í a > 2) eos F 4) sen reco rdan In this case, N = 2 F p n v sin OÍ. Expanding the terms eos F and sin F by the equations of Chapter II we have as the heel ring tension in any tire of any rope trajectory under the restrictive condition that we will now describe. It will be recalled that the equations of the curvature and shape of tire contour were derived for an equilibrium surface between the tension in their cords and the inflation pressure. It is quite apparent that when in the construction of a tire the edges of the various layers are anchored to an inextensible steel ring when bending them around a ring and extending the crease at a diameter larger than that of the ring itself, a comparatively rigid structure is formed by the combination of steel anchor ring and layers of rubberized cloth. If this inflexible structure were placed with its neutral contour coinciding with the neutral contour of the flexible ring 300 as in Figure 4, equations 4) or 5) would exactly define the tension in the steel anchor ring. In most tires 320, however, the rigid structure of the steel ring and the surrounding rubbery rope material are shaped as in Figure 5, and the neutral contour of the flexible tire 320 does not come close to the steel ring or the Neutral contour of the surrounding rigid structure. In this case, if the rope pull is to be defined by equations 2) or 3), it will have to be defined in A where the flexible contour meets the rigid structure known in the rubber workshops as the "heel" of tire. The force on AD t n v sin2 eos F in the type of heel tends to flip the structure about an axis through some point near B. A twist Current occurs in many cases, but if it does or there are no tensions in the heel structure that have presented persistent problems to the designer. As for the tension in the steel anchor ring, equations 3) or 4) when calculated at point A were not very reliable voltages in the steel ring in B. Instead of the component of rope pulls tnv sin2 eos F consider the component t sen OÍ transmitted on the arc AB that exerts the force BC on the steel ring in its own plane. Then we will rewrite 4) as 2 sin Fb as the tension in the B ring, and where k is a factor that will correct the way in which the forces t sin OÍ are transmitted from A to B. "The generation of this real neutral layer line curve is performs numerically within a Computer Aided Drawing program (CAD = Computer Aided Drawing). At point YS, the curve is tangent to a circular arc that extends from point RC to YS. SPECIFYING THE NEUTRAL CONTOUR LINE, it is achieved using the following stages: 1. Determine the RC point by RC = OD / 2 - TO where TO = 1.04 * NSK + UT + BGA + TPC 2, Determine YM by subtracting the required lateral stop gauge (SWGA) from SD / 2. 3. In order to determine the point RB, YB the heel position must be established. The lateral position of the bead bundle is determined by first displacing the upper portion of the mold ring inward and parallel to an amount of BMG (equal to the sum of the sizes of gum reinforcement portions, fabric reinforcement portions, plates, coat and fin). The lower right hand vertex of the bead wire bundle is then placed axially in this line. 4. For determination of RB, YB, the upper portion of the mold ring moves outward in parallel 1.27 cm (0.5 inch). From the intersection of the critical mold diameter line and this offset exit, a line is drawn at 135 degrees to the horizontal. A vertical line is passed through the center of the heel beam. The intersection of the vertical line and the 135 degree line is the point RB, YB, . A neutral contour line can now be constructed with an estimate of PR such that the point YS (constant radius edge PR) falls between 80-85% of the WBA dimension, where WBA is the width of the band that covers the "wedge" " Additional PR estimates can be used in an iterative way until the YS objective is reached. REVISION OF THE UPPER LAYER CONTOUR LINE The neutral contour of C / L to the shoulder is checked in order to provide a uniform rubber gauge between the divided bands # 1. This normalizes the insert for plant efficiency. REVISION OF THE LOWER LAYER CONTOUR LINE While it is convenient to make the layer line follow the neutral contour line in practice, the steep approach angle (from the vertical) prevents the curing bladder from providing enough pressure to form contour. In this way, the lower layer line is checked in the following way: A point X (see Figure 2) on the mold surface is located at the intersection of the bead radius and the mold ring flange. The layer 26 termination is in a circular arc of radius PEH (centered in X) and it is located at a distance T2 from the mold surface (which is obtained by the intersection of the displaced mold surface and the circle arc PEH). The point E is then established on the inner side of the layer termination 26 and a circle of radius Ti is then plotted to establish the distance to layer 24 (see note 3). It should be noted that at this point, the layer gauge and the appropriate fin gauges have been placed on the inner side of the heel as concentric circular arcs. A groove 70 is then drawn through the YM point (point A), tangent to the circle centered at E (point B) and tangent to the layer circle (point D) at the inner side of the heel (dotted line). With reference to Figures 6, 7 and 8, the use of a precured contour vertex 40, provides a surface 42 that maintains its profile during the vulcanization process. By profiling the contour 42 of a precured vertex 40 with a convex surface 42A axially inward of the bead core 20 and extending to a radial location T, the location T is at or below the radial height Z of the rim flange 52 of the design rim 50, where the tire 10 will be mounted, the contour 42 has a tipping point or short T-slot line, wherein the axially lower surface becomes concave 42B, the concave surface 42B extends from the inflection point T to the radially outer end 41 of the vertex 40, the radially outer end 41 is at or preferably slightly below the radial location H of the maximum section width SW of the tire 10. When T is constructed as a short slot, a preferred approach of the slot T is established as a line tangent to the circular arc which is established by the radius RLPJj and tangent to the circular arc adjacent to the bead core 20. The average length of the groove T must be at or below the radial location Z of the rim flange Z. This ensures that although a slot, it must be very short in length and in this way limits the amount of deviation from the optimal neutral contour line. From a geometric fit relationship as the ratio LK / UPL greater than 1.0 increases, then the length of the slot T decreases to a point where the tangency of the circular arcs is a point T. Importantly, the location T either a point or the midpoint of the groove must be located between the rim flange 52.

As can be seen in Figures 6, 7 and 8, the lower path of the layer cord 24 below the maximum section width is dictated by the total contour of the precured vertex 40. The layer line 24A in the upper shoulder region has a single radius of curvature RUPL, RUPL extends from below the band 14 near the edges of band 15 to the width of maximum section SW in the diameter of section width SD. Near this location, the curvature of the layer line transits to a second lower radius of curvature RLPL, RLPL is greater than or equal to RUPI preferably approximately 100% to 250% at the radius RUPll, more preferably approximately 125% to 200% RUPL * As it is illustrated in Figures 8A and 8B, considering that a line S tangent to the convex surface 42A of the precured vertex 42 is drawn at an angle of 45 ° with respect to the radial direction and then that line extends to the intersection point S1 in the lower axially concave surface 42B, the extension of the line S will cover or extend between 50% and 100% of the precured vertex length 40 which lies below the intersection point S1. The maximum distance X1 between T and S1 between line S and layer line path 24A will be at least 1.0, preferably at least 2 times the thickness of the layer gauge (t). The resulting tire 10 exhibits an approximately neutral contour to a radial location at or below the rim flange 52. This greatly reduces the shear stress of the cords and gives the tire 10 superior performance improvements. The fact that the deviation of the optimal layer path 24 occurs at a point where the rigid rim flange 52 and the bead core 20 can cooperatively constrain the cords 21, means that the total durability adjacent the bead cores 20 it is not decreased, while the internal shear stresses on the layer 24 line have been dramatically reduced. This means the generation of hysteresis heat and the associated reduced bead durability, can reliably and uniformly reduce the problems of high rolling resistance common in radial tires 10. The precured vertex 40 is considered to be manufactured more efficiently using injection molding without However, vertex compression molding can also achieve similar benefits as described above.

As used herein, the term "precured vertex" means that the rubber flow associated with the vulcanization process can not occur appreciably. In this manner, the term "pre-cured" may also encompass a partially cured rubber apex, provided that the contour profile 42 can be maintained to provide the shape of the layer line 24A. By using the contoured precured vertex 40 which maintains its shape during molding of the tire 10 as the adjacent uncured or raw components initiate the state of flow curing and as the tire is cured and "set" the layer path is fixed by vertex in combination with the mold. It is considered to be better that the bead core 20 should be inserted into the mold for vertex formation to produce a precured vertex and heel structure 43. This is of course a method that further ensures uniformity of these parts during tire assembly.

Claims (3)

1. CLAIMS 1. A tire for mounting on a rim of a vehicle, the tire has a portion of floor contact part, a bundle of radially inward bands of floor contact part, a pair of side wall portions each one extending radially inwardly from a side edge of the bundle of webs, a pair of beads each having an annular bead core and radially disposed within a respective sidewall portion, at least one radially located carcass ply. Inwardly of the bundle of strips and extending from bead to heel, the carcass layer at least has radially extending parallel strings and a pair of surrounding portion ends, each end of surrounding portion is wrapped around each bead core. and extending radially outwardly to an end point located radially outwardly of a rim flange, and a pair of heel fill portions p recirculated, a portion of precured heel filler is adjacent a radially outer surface of a bead core; The tire is characterized because: each precured heel pad has an inner curvature, the curvature
2. Inner is defined by a convex surface and a concave surface, the convex surface extends radially outward from axially inwardly of the bead core to an inflection location T substantially radially inwardly and a radially outer surface of the rim flange , the concave curvature extends from the inflection location T to a radially outer end located below the radial location of a maximum section width of the tire, the inner surface curvatures establish a layered rope path of the carcass layer when the tire is normally inflated and discharged, the layer path extends from radially on the rim flange to the side ends of the bundle of webs, the layer path has a radius of curvature (RUMl) between the web side ends on the radial location H of the maximum section width and a second radius of curvature RLP L in the range of 150% to 200% RUPL between the location H and the location T. 2. The tire according to claim 1, characterized in that the location T is defined by a line that has its midpoint below the radially outer surface of the rim flange, the line is a tangent line, tangent to the radius of trajectory of lower layer of curvature RLPL and the convex curvature.
3. 3. The tire according to claim 1, characterized in that the location T is a point.