MXPA97006697A - Tired rims and method to prepare the same without the cement of rociad - Google Patents

Abstract

The present invention relates to a retread tire assembly (66) and the method for making the same. The method and assembly provide the means for applying a new running surface (60) to a polished tire cover (12) with only one layer of cushion rubber (50) placed therebetween. The cushion rubber (50) is applied directly to the polished surface (44) of a tire cover (12) without the use of conventional spray cement normally applied to the polished surface (44) of the entire tire.

Description

"ROLLED TIRE AND METHOD TO PREPARE THEM WITHOUT SPRAYING CEMENT" TECHNICAL FIELD This invention relates generally to a method for making retreaded tires and particularly to a method for making retreaded tires that eliminates the need for the spray cement normally applied to the tire cover.

BACKGROUND OF THE INVENTION Retreaded tires have been available for many years and provide an inexpensive way to obtain additional use of a tire cover after the original running surface has been worn. In accordance with a conventional method of retreading, sometimes referred to as cold-process retreading, the remaining running surface on the used rim is removed by a special grinding machine that grinds the old raceway and leaves a surface polished to which a new surface layer can be bonded.

Removal of the old tread surface from the tire cover provides a surface free of generally smooth tread surface around the circumference of the tire cover. The tire cover can then be examined for damage, often called scratches, that are filled with a repair rubber. After completing the scraping process, the polished surface is sprayed with a tire cement that provides a sticky surface for the application of the bonding material and a new spraying surface. Then, a layer of cushion rubber is applied to the back, that is, the inner surface of a new layer of rolling surface. The cushion rubber and the running surface are applied in combination around the circumference from the tire cover to create a retread tire assembly ready for healing. The cushion rubber forms the bonds between the running surfaces and the tire cover during healing. After screwing the tire cover, cement, cushion rubber and running surface, the total retread tire assembly is placed inside a flexible rubber shell. An air tight seal is created between the shell and the heel of the rim. The entire rim assembly within the shell is placed inside a healing chamber, and is subjected to pressure and a high temperature for a specific period of time. The combination of pressure, temperature and time chemically bonds the layer of the rubber buffer to both the tire cover and the new tire tread surface. The above-described method of retreading the cold process works well and provides retreaded tires of superior quality. However, in certain applications it would be advantageous to eliminate the spraying cement. This is particularly the case in geographical areas where there is an increased regulation of the use of chemical substances within the spraying cement. In general, the available spray cements include either a heptane solvent or methyl chloroform. The ethane solvent has been found to contribute to the formation of es og and the methyl chloroform even when it does not cause smog, has a tendency to be considerably more expensive than the heptane solvent. The use of spraying cement can also add to the cost of producing retreaded tires due to the cost of the product and the cost of the equipment. For example, because cementing the tire cover should only be carried out in a well-ventilated spray booth, retread shops should purchase the appropriate ventilation equipment. The elimination of spraying cement therefore eliminates the need to buy ventilated spray booths. A potential solution to the problems of smog associated with the use of heptane solvent is the installation of a solvent capture equipment in this retreading workshop. However, this solution is disadvantageous due to the cost of the equipment and the costs of operation and maintenance. The present invention addresses the inconveniences associated with using spray cement during tire retreading.

COMPENDIUM OF THE INVENTION The present invention includes a method for retreading a rim comprising the steps of removing the tread surface of the rim from a rim tire to present a polished surface. Then, a layer of rubber buffer is applied directly to the polished surface, without spraying cement over the polished surface. A tread surface layer is wrapped around the cushion rubber layer and finally, the rim is treated to form bonds between the tire and the cushion rubber layer and between the tread surface layer and the cushion rubber layer . Another unique aspect of the invention is a retread tire assembly prepared to be inserted into a pressurized heating chamber. The rim assembly includes a rim cover that has a pair of sides and a radially outer wall that spans the pair of sides. The radially outer wall has a polished surface positioned around the outer circumference of the tire cover. A layer of cushion rubber is placed directly against the polished surface and a layer of tread surface is placed against the cushion rubber around the outer circumference of the cushion rubber. After proper treatment with heat and pressure, the tire cover, cushion rubber, and tread surface are bonded together in an integral retreaded tire that can be used on an appropriate vehicle running on the road.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings in which the like reference numerals represent like elements and: Figure 1 is a cross-sectional view of an exemplary original rim; Figure 2 is a cross-sectional view of the rim of Figure 1 after the tread surface layer has been removed from the tire cover; Figure 3 is a schematic representation of the cushion rubber layer of the new tread surface layer that is applied to a rim cover; Figure 4 is a cross-sectional view of the rim cover illustrated in Figure 2, with the addition of the cushion rubber layer and the new tread surface layer; and Figure 5 is a perspective cross-sectional view of an alternative embodiment of the retreaded rim in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY Referring generally to Figure 1, an original rim 10 is shown as having a rim cover 12 from which a rim rolling surface 14 extends. The rim 10 illustrated is a radial rim; however, the invention applies equally to other types of rims, such as slanted tire rims. More particularly, the rim 10 includes a pair of sides 16 linked by a radially outwardly facing wall 18 generally encompassing the sides 16. Each side 16 extends radially inwardly from the outer wall 18 and terminates in a bead area 20 designed to be mounted on the rim ring (not shown). The heel area 20 can. be designed in a variety of configurations depending, for example, on the type of rim, the tire size or the rim configuration. In the illustrated embodiment each bead area 20 includes a lower heel portion 22, a heel tip 24 and a heel sole 26. Each bead area 20 may also include a bead beam 28 and a grating layer 30. Both the bead beam 28 and the galling layer 30 include, for example, metal wires or wires to improve the strength of the bead area 20. . The sides 16 may also include multiple layers, such as a rubber layer 32, a radial layer 34 and an inner liner 36 which cooperate to provide a sturdy but flexible side. The sides 16 are joined to the wall 18 radially outwardly and to the running surface 14 through a pair of shoulder areas 38. The shoulder areas 38 extend towards the running surface 14 of the rim that, in turn, is positioned radially outward from the wall 18 of the rim cover 12. The surface of the tread 14 of the rim may include a plurality of grooves 40 designed to channel the water and provide additional traction during certain road conditions, furthermore, the outer wall 18 may be reinforced by a plurality of belts or cords 42 that are extend circumferentially around the rim 10 within the wall 18 (see Figures 2 and 5). After the rolling surface 14 of the rim wears beyond a certain limit, the rim 10 must either be discarded or retreaded before being used in the vehicle for which it was designed. In cold process retreading, the tread surface 14 of the remaining rim is removed from the tire cover 12 by a polishing machine such as the Model 8110 polishing machine manufactured by Bandag, Incorporated, of Muscatine, Iowa. polishing operation, the running surface 14 of the original rim is ground away from the tire cover 12, leaving a surface 44 polished, as illustrated in Figure 2. The polished surface 44 extends circumferentially around the tire 12 of the rim and also extends transversely through the outside of the outer radial wall 18 until it terminates in the polished shoulder areas 46. After removal of the used tread surface layer, a scraping and filling process is carried out on the cover 12 of the rim. Scraping is the removal of damaged material from a tire before making a repair. Frequently, tire cover 12 accumulates holes, notches or breaks due to stones or other sharp objects with which the tire is brought into contact during use. Damaged or injured areas are first rectified to be smooth by an appropriate grinding tool and then filled with the repair gum, such as a repair gum or repair cord from the Bandag extrusion apparatus or some other appropriate material. It is necessary to fill the damaged areas to the level of the polished surface 44 to avoid air cavities between the polished surface 44 and the subsequently applied surface of the rolling surface. Trapped air can have negative effects on the longevity of a typical retreaded tire. After the scraping and filling operation, a patching step occurs where a layer of the cushion rubber and the new tread surface layer are wrapped around the circumference of the tire cover 12, along the surface 44 polished. As best illustrated in Figure 3, a sewing machine 48 (shown schematically), such as Bandag 5110, the semiautomatic sewing machine manufactured by Bandag, Incorporated, can be used to apply a cushion rubber layer 50 such as the HD30 cushion rubber manufactured by Bandag, Incorporated. Although the cushion rubber layer 50 can be applied to the tire cover 12 in a variety of ways, the schematic representation of Figure 3 shows a roll of the cushion rubber 52 mounted rotatably on the make machine 48. The cushion rubber layer 50 moves around a tension roll 54 before being wrapped circumferentially around the polished surface 44. Preferably, the cushion rubber layer 50 is covered by a sheet 56 of lower plastic, eg, a sheet of poly, and a sheet 58 of similar plastic upper. As illustrated, the lower sheet 56 is detached from the layer 50 of the cushion rubber shortly thereafter before the cushion rubber is wound around the tire cover 12 along the polished surface 44. The lower plastic sheet 56 is then wound around the tension roll 54 as shown in Figure 3. The layer 50 of the cushion rubber is preferably applied to the polished surface 44 within 8 hours of the polishing operation. further, the application has been found to work best when the cushion rubber layer 50 is applied under tension in the circumferential direction. Depending on the application, it may be desirable to slightly lengthen the cushion rubber layer 50 to achieve better adhesion to the polished surface 44. The cushion rubber layer 50 is cut crosswise and the cut edge is joined to the front edge so that there is no gap between the start and end of the cushion rubber layer 50. Any overlap between the front edge and the cut back edge preferably is limited to 3.18 millimeters or less. After the cushion rubber layer 50 is applied to the cover 12 of the rim, the layer 50 is sewn or in other words stretched against the polished surface 44 to expel any air trapped between the cushion rubber layer and the surface 44 polished After sewing, the pla top layer 58 is removed from the cushion rubber layer 50 to allow a new surface layer 60 to be applied over the cushion rubber. The step of sewing also helps to prevent the cushion rubber from rising up by separating from the polished surface 44 when the pla layer 58 is removed and the surface layer 60 is applied. Preferably, the tread surface layer 60 is also applied with the aid of the make machine 48 even when there are a variety of ways to wrap the tread surface layer 60 around the circumference of the tire cover 12. When the making machine 48 is used, a rolling surface roll 62 is rotatably mounted therein and the running surface surface 60 is guided towards the tire cover 12 against the cushion or cushion rubber layer 60 by the guide rollers 64. The cover 12 of the rim is rotated in the make machine 48 until a sufficient length of the running surface layer 60 is unwound from the roll 62 to extend around the circumference of the tire cover 12. The tread surface layer 60 is then cut generally transversely to the circumferential direction, and the cut end is bumped against the leading edge of the tread surface layer 60 to form a splice. The emplame of the tread surface layer is often held together by a plurality of staples (not shown). It is also preferred that the embossed area of the cushion rubber layer 50 and the spliced area of the tread surface layer 60 be placed at different points along the polished surface 44. Even though the application of the cushion rubber layer 50 and the tread surface layer 60 to a rim cover 12 by the make machine 48 have been generally known in the industry for many years, the unique aspects of this The method of the invention of retreading, allows the omission of a previous step to know the application of the spraying cement to the surface 44 polished. Previously, the spraying cement would initially be applied to the polished surface 44. Then, the cushion rubber layer 50 would be applied to the inner or lower surface of the tread surface layer 60. The combination of the cushion rubber layer 50 and the tread surface layer 60 would be wound around the polished surface covered with cement and emplaced together. The present method allows the elimination of the spraying cement which overcomes certain disadvantages which are described in the background of the section of the previous invention. By first extending the layer of the cushion rubber around the circumference of the rim cover 12, the operation of sewing the cushion rubber and then applying the tread layer 60 above the rim cover 12 and the layer 50. cushion rubber combined, has eliminated the need to eliminate spraying cement. It has been found that retreaded tires made in accordance with the new method have very desirable characteristics without requiring an extra cementing step. After application of the cushion rubber layer 50 and the tread surface layer 60, a retreaded rim assembly 66 is created ready to be cured under appropriate conditions of heat and pressure. A cross section of retreaded rim assembly 66 is best illustrated in Figure 4. After assembly, the total rim assembly is inserted into a rubber healing shell such as an appropriate Bandag, Incorporated healing shell that is designed for the specific type of rim and size that is being retreaded. The retreaded rim assembly 66 is sealed within the healing shell and placed within a healing chamber such as the Model 4130 or 4120 healing chamber sold by Bandag, Incorporated. Pressure and heat are applied to the assembly 66 of the retreaded rim inside the healing chamber. The amount of time needed to cure a certain retreaded tire can vary depending on the size of the tire and the materials used. However, the period of time must be long enough to create a sufficient bond between the cover 12 of the rim and the cushion rubber layer 50 and between the layer 60 of the running surface and the cushion rubber layer 50. In general, the bond results from the vulcanization between the rim cover, the cushion rubber layer and the surface layer. The times, pressures and temperatures within the healing chamber would be known by a person skilled in the art. However, the exemplary parameters during cure within the healing chamber are the temperature: of about 99 ° C; the pressure: of approximately 5.94 kilograms per square centimeter; and the time: of approximately three and a half hours. The pressure temperature and aforementioned time parameters are only given as examples, and are not intended to limit the scope of the invention. As stated above, the time inside the healing chamber may vary depending on the size of the rim and the materials of the rim. In addition, other combinations of temperature and pressure can potentially provide satisfactory results. After curing, the retreaded tire may undergo certain small trimming operations or is otherwise ready for use in a vehicle. Another embodiment of the retreaded tire assembly 66 is illustrated in Figure 5. The process used in this type of retreaded tire is the same as that described above, with the exception of the addition of a pair of bump strip 68 of rubber cushion that they are added to accommodate the arcuate outer flanges 70 which curve in the transverse direction generally around the shoulder areas 46 in the tire 12 of the rim. Accordingly, additional shock absorber in the form of shoulder strips running generally along each shoulder area 46 of the rim cover 12 and below the rims 70 should be added. In this way, after the polished surface 44 is applied to the cushion layer 50 and sewn thereon, the plastic top layer 58 is removed and the shoulder strips 68 are applied along the shoulder areas 46. The running surface layer 72 including its arcuate outer flanges 70 is applied over the cushion layer 50 and the shoulder strips 68, cut and spliced in a manner similar to that described above. The different parameters involved in retreading cement-free tires can vary according to the total design of the tire being retreaded and the composition of the retread materials. However, it is generally preferred that the temperature of both the rim cover 12 and the cushion rubber layer 50 be at least 18 ° C when the cushion rubber layer is applied to the polished surface 44. Likewise, the cushion rubber should be applied to the non-cemented cover within 8 hours of being polished or if the polished cover is covered with poly, the application of the cushion layer should be within 72 hours of being polished. Furthermore, to ensure a premium quality retread tire it is preferred that the center line of the cushion rubber layer 40 be aligned with the center line of the polished tire, within plus or minus 3.18 millimeters. When the flat style tread surface illustrated in Figure 4 is applied, there must be at least 3.16 millimeters of cushion rubber layer 50 extending transversely beyond the base of the tread surface on each side of layer 60 of rolling surface. Similarly, the cushion rubber layer 50 must be applied with sufficient tension to facilitate shaping to the polished surface 44, but the tension must not cause the width of the cushion layer 50 to be reduced by more than 3.18 millimeters. Generally, the length of the layer 50 of the cushion rubber is approximately 5.08 to 20.32 millimeters shorter than the circumference of the surface 44 polished. It will be understood that the foregoing description is of the preferred exemplary embodiment of this invention and that the invention is not limited to the specific form shown. For example, the invention is directed to a tire assembly and a method for retreading tires that do not require the use of spraying cement and therefore a wide variety of equipment can be used to apply the layers of the cushion rubber and the surface of the tire. rolling to the tire cover. further, the invention encompasses a wide variety of designs of tires, materials and running surfaces that can be assembled according to the invention. The methods for preparing the tire cover and curing the retreaded tire assembly can vary considerably due to differences in materials, equipment and techniques to create the retreaded tires. These and other modifications can be made in the design and arrangement of the elements without departing from the scope of the invention as expressed in the appended claims.

Claims (20)

R E I V I N D I C A C I O N E S:

1. A method for retreading a tire, comprising the steps of removing the tread surface of the tire from the rim tire to present a polished surface; apply a cushion layer directly to the polished surface; wrapping a layer of rolling surface around the layer of the buffer rubber; and treating the rim to form bonds or bonds between the cover and the layer of the buffer layer, and between the surface layer of rolling and the layer of rubber buffer.

The method for retreading a rim according to claim 1, wherein the step of applying the cushion rubber layer includes the step of pressing the cushion rubber layer against the polished surface, with a pressure sufficient to force any air from the cushion. between the cover and the rubber buffer layer.

3. The method for retreading a tire according to claim 2, wherein the step of applying the cushion rubber layer includes elongating the cushion rubber layer circumferentially around the tire.

The method for retreading a rim according to claim 1, wherein the step of applying the cushion rubber layer includes the step of applying a pair of shoulder strips to the polished surface.

The method for retreading a rim according to claim 3, wherein the step of applying the cushion rubber layer includes the steps of cutting the layer generally transverse to the circumferential direction and splicing the layer in the cut region. .

The method for retreading a rim according to claim 5, wherein the step of wrapping the tread surface layer includes the steps of cutting the tread surface layer, generally transverse to the circumferential direction and splicing the tread. layer of rolling surface to the cut region.

The method for retreading a rim according to claim 6, further comprising the steps of enclosing the rim in a shell, heating the rim; apply a vacuum inside the envelope and apply the pressure to the outside of the envelope.

8. A method for retreading a tire, comprising the steps of: removing the tread surface of the old rim from a rim tire to present a polished surface; cutting a layer of rolling surface to a length sufficient to surround the polished surface along the circumference of the tire; keep the polished surface free of cement to retread tires; placing a layer of rubber buffer between the polished surface and the surface layer of the raceway; tightening the cushion rubber layer between the polished surface and the tread surface layer; and heating the tire of the combination rim, the tread surface layer and the cushion rubber layer to form a vulcanized ligature therebetween.

The method for retreading a rim according to claim 8, wherein the step of removing the tread surface of the old rim includes grinding the tread surface of the rim tire rim.

The method for retreading a tire according to claim 9, wherein the step of maintaining the polished surface includes removing contaminants from the polished surface.

The method for retreading a rim according to claim 8, wherein the step of placing the cushion rubber layer includes applying tension thereto in a circumferential direction as the layer of the cushion rubber is wrapped around the rim. circumference of the tire cover.

The method for retreading a tire according to claim 11, wherein the step of attaching the cushion rubber layer includes sewing the cushion rubber layer to the polished surface to expel air therefrom.

13. The method for retreading a tire in accordance with claim 8, wherein the tightening step includes the steps of placing the tire cover, the tread layer and the cushion rubber layer combined into a pressure chamber.

The method for retreading a rim according to claim 13, wherein the tightening step includes the steps of placing the rim cover, the tread surface layer and the cushion rubber layer combined into a shell and creating a empty inside the envelope.

15. The method for retreading a tire according to claim 14, wherein the step of heating occurs while the tire cover, the tread surface layer and the combined cushion rubber layer are in the pressure chamber.

16. A retreaded rim assembly ready to be inserted into a pressurized heating chamber comprising: a rim cover having a pair of sides and a radially outer wall that spans the side pair, the radially outer wall has a polished surface placed around the circumference of the tire cover; a layer of cushion rubber placed directly against the polished surface; and a layer of rolling surface placed against the cushion rubber.

17. The retread tire assembly according to claim 16, wherein the cushion rubber layer is tensioned around the circumference of the tire cover.

18. The retread tire assembly according to claim 17, wherein the cushion rubber layer includes a center strip and a pair of shoulder strips.

19. The retread tire assembly according to claim 17, wherein the tread surface layer is arcuate in both the circumferential and transverse directions.

20. The retread tire assembly according to claim 17, wherein the tread surface layer is arched only in the circumferential direction.