MXPA99000744A - Pneumatic rolling surface with hides through which a flu passes - Google Patents

Abstract

A method of molding a rolling surface for a tire and a rolling surface 6 is described. The mold 2 has at least one mold rib having a plurality of notches cut in the rib forming the flow paths 30 through the rib. mold rib that allow rubber from the tread surface to flow uniformly to adjacent elements of the tread forming recesses 22 within the mold. The resulting rolling surface 6 has at least one slit 40 that has flow paths 30 filled with rubber

Description

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B60C 1112, 11/04, B29D 30/06 Al PNEUMATIC ROLLING SURFACE WITH HIDES THROUGH WHICH A FLUID PASSES Technical Field This invention relates to a method and article of manufacture known as a tire or rim, more specifically, a tire tread surface.

BACKGROUND OF THE INVENTION Tires are generally manufactured using a process invented by Charles Goodyear called vulcanization. This tire vulcanization cures green rubber components before or after assembly. The most common method includes placing the tire lining and its tread rubber in a mold, applying heat and pressure thereby forming the pattern of the tread surface while at the same time healing the tire unit. A second method includes the pre-casting of the rolling surface by compression or injection molding and then the application of the running surface to a prepared precured casing, in a process commonly known as retreading or applying the rolling surface to a new coating. cured or not cured to make a nine tire. A common feature in tire treads is the use of slits, both circumferentially continuous or extending laterally. The mold that forms slit patterns in the tread usually has metal ridges or ribs that exit the outer surface of the tread surface to form a portion of the mold. These metallic ribs form the slits. When the running surface has deep grooves, these metallic ribs project outwards at a considerable distance. This is particularly true for heavy-lift truck tires _ some snow tires that are used in passenger-type vehicles. These ribs that form the slits in the mold can act as flow restrictors of the rubber. For example, a circumferentially continuous groove has a metal rib extending 360 °, thus limiting the lateral flow of rubber from the running surface during the vulcanization process. Tires having a pattern of block elements on the running surface have a series of laterally extending slits formed by metal ribs that can create a circumferential limitation on the flow of the rubber.

For the untrained eye, tires that have deep running surfaces can, for all intents and purposes, look uniform. Occasionally tire manufacturing may have to grind some of the running surfaces due to the large points formed during molding. These big points are only a symptom of a much deeper problem that has occurred during the molding process. When the green tires are inserted into the curing molds it is almost impossible to perfectly align the tire in the mold. As a result, undesirable, undesirable mass imbalance of the tread surface rubber occurs which gives rise to irregularities in the cured tread surface. The rubber on the tread must flow through and around the rib to balance the mass of the rubber through the tread surface. The ribs of the mold forming the groove create dams that prevent the rubber from the running surface from flowing uniformly through the pattern of the running surface during the molding process. This is particularly troublesome during the compression molding process because the uncured green rubber may have brownish portions which, if limited between the grooved ribs of metal grooves and the pawl of the underlying shell of the shell, result in a rolling surface having a rubber with high density at one point and rubber with lower density at another point. These changes in density affect the physical properties of the tread surface so that its operation can be irregular producing a propensity to the appearance of irregular wear problems, variation in hysteretic performance and problems generated by heat, and poor rolling resistance properties. In addition, this problem causes the belt reinforcement to deform or deviate as a result, the depth of the pattern on the running surface has been limited to a sufficiently low depth, and the lower part of the running surface between the mold rib and Belts are made thick enough to avoid this restrictive flow problem. However, this tends to limit the amount of mileage one can expect from a tread surface. The compounds of the material can be developed to prolong the molding, however, if these compounds can be used on surfaces of non-slip, deeper grooves, an operation of the mile can be obtained and even better if the physical properties of the running surface they can be kept uniform during the molding process. Another object of the invention is to describe a rolling surface with deeper crevices for a tire that has uniform physical properties. ription of the invention Compendium of the invention. A method of molding a running surface for a tire has the step of: providing a mold 2 for forming a tread surface pattern on a rubber tire tread G. The mold 2 has at least one rib 20 for forming a slit 40 in a tire rolling surface 6. The at least one rib 20 has a plurality of elongated flow paths in length 10. The elongated flow paths 10 are notches cut in the rib 20 and spaced apart 42 where the area of the flow path 10 when observed in the cross section along the length of the slit 44 is larger than the area between the adjacent flow paths 10 at the same depth t measured from a tip of the mold rib 20 that forms the base of the slit at the minimum height (H) at the top of the notch that forms the flow path. The method further has the steps of: inserting uncured rubber to the running surface in the mold 2, applying heat and pressure to cure and form the running surface 6 > remove the cured and formed tread surface t from the mold 2.

Preferably, the flow paths 10 each have an elongated length PL with a width PW measured perpendicular to the length PL. The width PW extends through the rib of the mold by intersecting the respective walls of the slit formed by the rib of the mold 20. In the preferred method, the step of providing a mold 2 incluthe step of providing at least one forming mold rib of the circumferential groove 20 having a plurality of flow paths 10. The rib 20 has sito form the walls of the groove inclined from the radial direction and a maximum space length of the groove G between the adjacent flow paths where the plurality of flow paths? umple the relation 6 x G = P = 2 x G? . More preferably, the method incluthe steps of: inserting a tire / liner into the mold 2? Together with the uncured rubber from the running surface thereby forming a tire unit 8 and removing the pneumatic unit & after curing and forming the unit 8 running surface 6 and coating the tire 7.

The resulting tread surface > formed by the previous method is also claimed. The running surface t has a depth D measured from the base or bottom of the groove to the surface of the running surface / the flow paths filled with rubber that have a height of approximately 3 mm. It is considered preferable that the rubber-filled tracks should have the respective ends 34, 3 € inclined at an angle? of about 20 ° relative to the radial direction and spaced at location 42 a distance G of about 5-mm (0.2 inches). This prevents the stones from being caught between the flow paths 30.

Definitions, "relationship between dimensions" of the tire means the ratio of its height section (SH) to its width section (SW) multiplied by 100- for the expression ~ co or a percentage. "Asymmetric running surface" means a running surface having a non-symmetrical rolling surface pattern with respect to the center plane or the equatorial plane (PE) of the tire. "Coating" means the carcass, belt structure, heels, side walls and all other components of the tire except the running surface and the inner part of the running surface. The coating may be unvulcanized, new rubber or pre-vulcanized rubber to be adjusted with a new tread surface. "Circumferential" means lines or directions that extend along the perimeter of the surface of the surface of annular rolling perpendicular to the direction of the axis. "Equatorial plane (PE)" means the plane perpendicular to the e e of rotation of the tire and passing through the center of its running surface. "Footprint" means the contact patch or contact area of the tread surface of the tire with a flat surface at zero speed and under normal load and pressure. "Slit" means an elongated empty area on a running surface that may extend on the circumference or laterally around the running surface in a straight manner, curved or zigzag. "Lateral" means a direction of e e. "Net contact area" means the total area of elements that make contact with the ground between the defined contour lines divided by the gross area between the contour lines measured around the entire circumference of the running surface. "Net to gross ratio" means the total area of elements of the tread surface that make contact with the ground between the contour lines around the entire circumference of the tread surface divided by the gross area of the entire tread surface between the contour lines.

"Non-directional tread surface" means a tread surface that has no preferred forward travel direction and does not require to be placed on a vehicle in a specific position or positions of the wheel to ensure that the tread surface design is aligned with the preferred route direction. In contrast, a directional tread surface design has a preferred direction of travel that requires specific placement of the wheel. "Axial" and "axially" means lines or directions that are parallel to the axis of rotation of the tire. "Pneumatic tire" means a mechanical rolling device of generally toroidal shape (usually an open toroid) having heels and a running surface and made of rubber, chemicals, cloth and steel or other materials. When mounted on the wheel of a motor vehicle, the tire contains the fluid that holds the vehicle's load and provides traction through its running surface. Pre-cured component means a component that is at least partially vulcanized before being assembled with other non-vulcanized components. "Radial" and "radialmerite" means directions radially toward or away from the axis of rotation of the tire. "Replacement running surface" as used herein refers to a "cured in the mold" or pre-molded and precured running surface. "Recauchuta e" means the process of renewing a worn tire on the running surface by removing the worn running surface and replacing it with a precured running surface or a "cured in the mold" running surface. "Rolling surface" means a molded rubber component that, when attached to a tire liner, includes this portion of the tire that comes in contact with the road when the tire is normally inflated and under normal load. "Ribs or ribs" means a rubber strip extending circumferentially over the running surface that is defined by at least one circumferential groove and a second groove or contour line, the strip being laterally subdivided by full depth grooves. "Filter" means small grooves molded into the elements of the tread surface of the tire that subdivide the tread surface and improve traction.

"Rolling element" or "traction element" means a rib or a block element.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view developed in fragments of a tire mold showing the protruding ribs to form circumferential grooves according to the invention. Figure 2 is a cross-sectional view of a rib taken along line 2-2 of Figure 1.

Figure 3 is a fragmentary view of a tread surface of the first embodiment formed according to the inventive method using the mold of Figure 1. Figure 4 is a cross-sectional view of the tread surface taken along the length of the tread. the length of the slit along lines 4-4 of Figure 3. Figure 5 is a cross-sectional view of the tread surface taken along a groove width along the lines bb of the Figure 3. Figure C is a fragmentary plan view of a tire mold showing the protruding ribs to form the lateral and circumferential grooves according to the invention. Figure 7 is a cross-sectional view of a rib taken along line 1-1 of Figure 6. Figure 8 is a fragmentary view of a second embodiment of the tornadoed running surface according to the inventive method using the mold of the Figure 5. Figure 9 is a cross-sectional view of the running surface taken along a length of slit along lines 9-9 of Figure 8. Figure 10 is a cross-sectional view of the running surface taken along a slit width along lines 10-10 of Figure 8.

Detailed description of the invention. With reference to Figure 1 a portion of a mold 2 is shown, the portion illustrated represents a design for forming a tread surface for a tire, the tread surface having a rib-like surface. The blades 5 are placed in the mold 2 to form filters. The ribs 20 are used to form the slits 40. The recesses 22 between the ribs 20 are used to form the elements of the running surface such as the ribs 50 blocks or studs 52. With particular attention drawn to the ribs 20 A plurality of holes known herein are shown as "flow paths" 10. These flow paths Id extend through the ribs of the mold 20 creating open flow channels between adjacent blocks on the running surface 52 or ribs 50. forming recesses 22 in the mold 2. These flow paths 10 are elongated in length P, along the direction of the route of the slit forming the rib 20. In Figure 2 a cross-sectional view of the rib 20 is shown with the vias of flow 10. The rib 20 projects outwardly from the recess forming the tread surface element 22. The benefits of the invention are also seen throughout the range of depths of slits currently used in tires and can, in fact, , making these grooves even deeper to allow rolling surfaces as deep as 32 mm (40/32 inches of an inch) sic]. The rib 20 that forms the slit creates a flow restriction of the rubber during molding. Traditionally, in tires for heavy-duty trucks the tire has a minimum caliper amount of the lower part of the running surface 54 between the outermost surface of the reinforcing belt structure 60 and the base or lower part 44 of the grooves 40. For purposes of the rubber flow in the tread surface in the mold and the protection of the belt rope, this lower part of the running surface 54 has a gauge thickness U generally maintained at approximately C mm (8/32). inches). When green tires 4 are inserted into the molds of cured it is almost impossible to perfectly align the tire 4 in the mold 2. As a result, an undesirable, undesirable mass mass of the rubber occurs on the running surface which gives rise to irregularities in the cured raceway surface 6. The rubber on the surface Rolling must flow through or around the rib 20 to balance the mass of the rubber through the running surface. As the lower part of the running surface 54 becomes thinner, the flow restriction of the rubber increases substantially. The Applicant has found that localized increases of the lower part of the running surface 54 can be achieved by utilizing pluralities of open flow pathways 10 that completely traverse the ribs 20. In theory, the flow paths 10 are notches that are cut into the mold rib 20 at a distance t of 3 mm (4/32 inch) from the tip 11 of the mold rib 20 as shown in Figure 2. This creates a conduit for the green rubber on the surface The flow path from one side of the mold rib 20 to the other side and as shown in FIG. 3, from origin to a flow path filled with rubber 30 in the base 44 of the slit 40, which was formed by the mold rib 20. This 3mm (4/32 inch) depth is considered ideal on a tire tread surface to drive truck because it is required to eliminate the depth of the running surface in many jurisdictions. This flow path filled with rubber acts as an indicator of wear on the tread surface for steering tire applications. In other applications, the wear indicators of the tread are set to 1.5 mm (2/32 of an inch) in such case, the flow paths filled with rubber 30 can project 1.5 mm (2/32 inch) over the actual usable boundary surface. However, due to the fact that the flow paths 30 are also designed to function as stone penetration protectors, this is a common height for such features that are commonly found at the base of the slits 40. What is little common is the size and the spacing of the rubber-filled flow paths. As shown in Figure 4 of the molded tire, the cut of the slit 40 has flow paths 30 that are elongated in length P as measured from the base of and along the length of the slit-in which it is located. . The flow path 30 must have a length P that is greater than the distance 42 between the adjacent flow paths 30. The resulting rubber-filled flow path has a minimum height (H) preferably set at 3 mm or 4/32 inch on the bottom 44 of the henaudure 40. Preferably, these flow paths 30 are placed closely along a slot 40 within a distance G of 50% P, or lesser measure at location 42. As shown, the ends 34, 36 of the tracks of 5 flow are inclined at an angle of 0, being? approximately 20 ° in relation to the radial direction. This large inclination also ends up preventing the retention of stones. The use of these flow paths 30 is more beneficial in circumferentially continuous grooves "40. The grooves 40 have a width Gw. The flow paths 30 have a width P ". As shown in Figures 5-10, when the side slits 40 are used in combination with circumferential slots 40 to form block elements 52, the flow paths 10, 30 can replace the struts connecting adjacent blocks 52, wherein the space G between the flow paths in lateral grooves maintains a full depth gap measurable giving the operator a greater indication of the running surface is still usable. In any case, the beneficial effect of equaling The amount of rubber on the running surface through the design of the same as the running surface 6 is molded can be best achieved by the generous use of these flow paths filled with rubber by the generous use of these vials. flow full of rubber 30. The increase in the area of transverse flow through a The slit of the mold forming the slit of the rib 20 is measured as the number of flow paths 10 (N) by the cross-sectional area A of the flow paths. Without these flow paths the area for the flow of the rubber under the ribs 20 is limited to the cross-sectional area of the lower part of the running surface 54 at this location. Although the flow paths 30 do not produce a complete increase in surface area due to space or location 42, they contribute substantially to the uniform density of the tread surface 6 almost eliminating the presence of low high blocks 52 [sic] and 50 common ribs on the truck tires 4. In addition, the stones penetration protectors 62 can also be used on the running surface. It is considered that no matter what composition or chemical composition of substance is developed in the future to improve and prolong the life of the running surface of a truck tire, the present invention may also extend to the useful life of the running surface. . Another important feature of the inventive method to produce a non-slip, deep running surface < -.- > is the uniformity of pressure and density within a given rib 50 or block element 52. This is to distinguish from the best general uniformity of the rolling surface of the inventive 6. Directly under the ribs 20 of the mold 2, the rubber of the running surface must be displaced to either side as the mold 2 is closed. This rubber of the displaced running surface increases the density of the rubber elements 50, 52 directly below and along the ribs 20 resulting in greater density or maximizing the edges of the running surface 55 adjacent the slit 40 formed by the rib of the mold 20. This This phenomenon is manifested by an undulating belt reinforcement 60 of the molded tire 4. It is considered that when the tires are inflated and the running surface is worn, the belts tend to straighten making observable the high and low points that can also accelerate the irregular wear . At least these undulating belts are an irregularity that can be eliminated or greatly reduced by the use of the inventive flow paths 10 in the ribs of the mold 20. This means that the running surface element 52 or the rib 50 when the tire 4 is inflated and loaded normally, it will present upper contact pressure along the edges of the running surface 55. On the contrary, the central portions 56 of the rolling elements 50, 52 present lower pressure. It is considered that it is more beneficial to have the elements block 52 or 50 ribs evenly loaded to improve uniform wear. It is considered probable that these non-uniformities within the ribs 50 or the blocks 52 is one of the root causes of irregular wear, such as the wear of the heel and flange, the wear of the couplings and rivers. Once these conditions begin they progress rapidly. Needless to say, the physical design of a tread pattern also does not play an important role in the wear of the tread, but it is considered that despite the pattern of the chosen tread surface, the designer engineer should try to achieve a distribution of uniform pressure through the patch or contact patch of the tire. A large amount of work has been directed to these objectives by selecting the shell and the structure of cmturon and the shape of the mold. On some occasions, engineers must mold tires with smooth running surfaces and then engrave a rolling design on the running surface or a quick resource to test the rolling concept. These naturally recorded tires would have very uniform tread surface density. The resulting engraved tires would be promising. An experimental mold would be ordered and the molded tread surface would show deficient wear characteristics unexpected The only difference being that the engraved tires were made with a homogeneous rolling surface of material with adequate uniformity and the molded tread had deformities of the material added as a result of the molding process. Those skilled in the art will readily recognize that the method of molding the inventive tread surface as described herein can achieve uniform properties of the engraved tread surface of the experimental tires making it possible to use a molded tread surface design suitable for mass production. If no other benefit was considered, the fact that casual tire production now will more closely reproduce the performance of the experimentally engraved tire of great value to the tire engineer. The above description has referred to the uniformity and the best performance to the resulting wear and tear the flow paths 10 and a mold 2. Additionally, various other benefits are possible when the flow paths 10 are used in a mold 2. A conventional truck tire 4 has approximately 8/32 in the lower part of the eupcrficic of rolling measured from the base 4 of a circumferential groove 40. On the base 44 ae the slit 40 is a wear indicator of the running surface determined at 1.5 mm (2/32 inch). The steering wheels are removed when there is 4/32 of tread surface measured from the base of the slit 40. This means that 12/32 of the tread rubber is discarded without contributing to any beneficial use or mileage. The reduction of the caliper of the lower surface of the tread 54 simply results in the exacerbation of the restrictive flow of the rubber on the running surface by increasing the deformities described above. However, by employing the flow paths 10 in a mold 2 positioned as shown, the lower part of the running surface 54 can be reduced by at least 1.5 mm (2/32 inch) when using 4 mm in the height of the flow paths 10. "To better appreciate this concept of the reduction of the caliber of the lower part of the running surface, the running surface must be observed over a determined length L of a groove 40 as shown in the Figure 4. The sum of the "areas of flow path 30 is equal to SA,, dividing SA, between L equal to the amount of reduction of the lower part of the running surface? U .. It should be understood that the Areas A, of each flow path need not be the same. This means that for a global reduction in the lower part of the rolling surface than the tracks of flow are employed in all full depth 40 slits. It is possible to reduce the lower part of the running surface as much as 3/32, the minimum legally permitted. The effective flow will be approximately the same as the prior art tire having 8/32 of bottom of the running surface. In this way, with no increase in the tread surface rubber, the useful amount of the tread surface that can be worn will increase by at least 2/32 of an inch. This is true because the wear indicator of the running surface will still be 1.5 mm (2/32 inch) above the lower portion 54 of the slit 40 which is measured at the location of the space 42 between the flow paths 30. of the tire. No increase in the weight of the tread surface will occur because, as mentioned above, the overall thickness of the rubber on the tread surface was not modified, a slight decrease actually occurs due to the reduction in the lower part of the tread. the rolling surface. Otherwise, to improve the rolling resistance and thus provide better fuel efficiency, the same reduction of the lower surface of the tread could result in a corresponding reduction in the thickness of the rubber on the running surface in no less of the caliber usable in the rolling surface. If the bottom of the tread is reduced by 1.5 mm (2/32 of an inch) to 5/32 of an inch, the total thickness of the tread could be reduced proportionally in a ratio of 1 to 1. The result would be the same or better wear speed as is conventionally achieved with a substantially lighter tread surface. Assuming a non-slip tire depth of 26/32 inch is maintained, the prior art tire would employ 34/32 of non-slip depth and the bottom of the running surface while the same running surface of 26/32 of inch could be made with the flow paths 30 having a non-slip gauge and in the lower part of the running surface of 29/32. The material savings resulting from 5/32 inch gauge in the tread result in approximately 4 to 6 pounds of rubber per tire. A very substantial saving that improves the uniformity and usefulness of the tire. Furthermore, as can be seen, the use of numerous flow paths 30 provide superior protection against penetration of stones compared to those currently in use because there is greater protection provided by the base of the slit when compared to the protectors of button type. The cost of making the gypsum model is also reduced eliminating the expensive ventilation system necessary to allow the rubber to flow into the cavity used to form the protector. The flow paths 30 allow easier measurement of the gauge of the running surface due to the elimination of the air hole which interferes with the gauge probe of the running surface. The flow paths 30 contribute to increase the stability of the ribs and blocks that improve the stability and handling of the vehicle.

Claims (11)

1. A method of molding a tread surface for a tire comprising the steps of: providing a mold for forming a tread surface design on a tread surface of a rubber tire, the tread member having at least one rib to form a groove in a tire tread surface, the at least one rib having a plurality of elongated flow paths along, the elongated flow paths being notches cut in the rib and spaced apart where the flow path area when viewed in the cross section along the lengths of the flow path is greater than the area between the adjacent flow paths at the same depth measured from a tip of the rib that forms the base of the slit at the minimum height (H, ) at the top of the notch that forms the flow path; insert uncured rubber for the running surface in the mold; apply heat and pressure to cure and form the running surfaces; and removing the cured and formed jelly surface from the mold.
2. 2. The method of molding a running surface for a tire, wherein the flow path in the mold rib is defined by a length P having a minimum notch depth measured from the base of the slit formed by the mold rib t and a width P extending through the mold rib by inserting the respective walls of the slit formed by the mold rib, the distance between the flow paths being less than 50% of the length Pi.
3. 3. The method of molding a running surface for a tire of claim 1, wherein the step of providing a mold includes the step of establishing the depth t of the flow path in the mold rib by at least 3 mm. (4/32 of an inch). The method of molding a running surface for a tire of claim 3, wherein the step of providing a mold includes the step of providing at least one circumferential groove forming mold rib having the plurality of flow paths , where the flow path, has ends inclined at 20 ° and a length of space G? between the adjacent flow paths, where the plurality of flow paths meet the relation 6? G > P = 2 x G. 5. The method of molding a running surface for a tire of claim 1 further comprises the steps of: inserting a tire liner into the mold together with uncured rubber from the running surface, thereby forming a tire unit; and removing the pneumatic unit after curing and forming the tire surface and tire unit. 6. A running surface for a tire having a plurality of grooves at least one groove having a base and a plurality of elongated flow paths in length filled with rubber, the length being defined as the direction along the route of the tire. the slit, the flow paths extending widthwise from one wall of the slit to the opposite wall of the slit and being spaced along the length of the slit, wherein the area of the flow path when viewed at its cross-sectional cuts along the length of the flow path are greater than the hollow area between the adjacent flow paths at the same depth measured from the base of the slit to the minimum height (H) at the top of the flow path. 7. The running surface for a tire of claim 6, wherein the rubber-filled flow paths have an elongated length P, a width P measured perpendicular to the length F, the width P extending to through the slit by intersecting the walls of the slit, the distance between the flow paths G being less than 50% of the length Pi. 8. The running surface for a tire of claim 7, wherein the slit having the flow paths has a thickness in the lower part of the running surface measured from the base or bottom of the slit inwards in the range of 2 mm to 6 mm. The tread surface of a tire of claim 6, wherein the flow path has the minimum height (H) being 3 mm (4/32 of an inch) or greater. The tread surface for a tire of claim 7, wherein the at least one slit having flow paths has a maximum length in the gap space of the gap between the adjacent flow paths and the flow paths complying with the relation: 6 x G, = P >; 2 x Gt. The running surface for a tire of claim 10, wherein G is approximately 5 mm.