WO2010126507A1

WO2010126507A1 - Apparatus and method for forming tire belts having cords posed at variable angles

Info

Publication number: WO2010126507A1
Application number: PCT/US2009/042199
Authority: WO
Inventors: Raymond J. Balzer; Patrick M. Rawlinson
Original assignee: Societe De Technologie Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2009-04-30
Filing date: 2009-04-30
Publication date: 2010-11-04

Abstract

An apparatus for making tires with belts that have cords posed at variable angles is disclosed that includes an expandable and contractible drum that has a surface having a low coefficient of friction that can be created, for example, by applying a nonstick coating. The drum may have movable body segments with magnets that can be used to keep the belts centered as they slide on the surface having a low coefficient of friction during mechanical conformation. In some applications, this apparatus can be used in conjunction with a method for manufacturing a tire. The method includes adhering a portion of a first belt with a second belt and then expanding the drum so that the cords of the adhered portions of the belts pantograph, decreasing the angle they form with the centerline of the drum, and later, with the equatorial plane of the tire once the belts have been incorporated into a tire. At the same time, the cords of the portions of the belts that are not adhered to each other have moved slightly, forming an angle with the equatorial plane of the tire that is greater than the angle formed by the cords that have been adhered to each other.

Description

APPARATUS AND METHOD FOR FORMING TIRE BELTS HAVING CORDS

POSED AT VARIABLE ANGLES

BACKGROUND OF THE INVENTION Field of the Invention

[0001] This invention relates generally to an apparatus and method for forming tire belts that have cords at different angles, and more specifically, to such an apparatus and method that can form tire belts that have cords which form a smaller angle with the equatorial plane of a tire near the center of its tread and that transition to make a larger angle with the equatorial plane near the outside edges of the belts which corresponds to the shoulders of the tire once the belts are incorporated into a tire.

Description of the Related Art

[0002] Belts are routinely used to reinforce and strengthen tires. In particular, they are often used to help prevent the puncture of the tread of the tire by nails and other sharp objects which might cross the path of the tire in use which can lead to a loss of inflation pressure and to help maintain the proper shape of the tire. These belts have cords made of a desirable material, such as steel or some other durable substance, which help prevent the puncture of the tread of the tire and help maintain the shape of the tire due to their strength. The cords of these belts are usually arranged at some angle relative to the equatorial plane of the tire, or centerline of the belt, for a number of reasons such as handling and comfort performance. For reference, the equatorial plane is a plane that cuts the tire in half laterally and that is perpendicular to the axis of rotation of the tire. In many cases, the centerline of the belts is coincident and parallel to the equatorial plane of the tire but in certain situations the centerline of the belts is offset from equatorial plane or maybe slightly angled relative to the equatorial plane. In addition, governmental regulations regarding the breaking energy for passenger and light truck tire designs is often the determining factor for the angle and the density, of the cords of these belts. Accordingly, it is desirable to maintain the angle and density of the cords with respect to the equatorial plane of the tire at predetermined values. Typically, the angle is 20° to 30° but could be anything else that is desired by the tire designer.

[0003] On the other hand, it is also known that the angle of the cords of the belts is one of the factors that affect the shear forces at the free edge of the belt. Based on the theory of biased composites, the shear, which at higher levels is detrimental to endurance, can theoretically be reduced to zero at an angle of 54.7°. However, as stated above, in order to achieve the desired handling and comfort performance, most passenger car and light truck tires are designed with cured belts that have cords that form angles of 20° to 30° with the equatorial plane of a tire. As can be seen, it is desirable from a design perspective to use belts in tires where their cords are pitched at a smaller angle with respect to the equatorial plane, providing a higher density of cables in the center region of the tire tread. Likewise, it is desirable that the cords then change the angle they form with respect to the equatorial plane to a higher angle such as 50° to 60° to reduce the shear at the edge of the belts.

[0004] Looking at Figure 1 , an example of such a belt 40 with cords that form variable angles with the equatorial plane once installed in a tire is shown. The cords 50 form a lesser angle θ_c with respect to the centerline C_L of the belt 40 in the center portion 52 of the belt and a greater angle θ_s with respect to the centerline C_L of the belt in the shoulder portions 54. This type of belt allows the tire designer to adjust the center and shoulder properties of the belt separately, which allows several performances, as described previously, to be optimized in a manner not possible with belts that have cords posed at substantially a constant angle.

[0005] Another problem that has arisen over the years is that a great number of tires with different dimensions are required to be manufactured with different belt components and properties such as the type of cable, skim thickness, angle of the cords, width of the belt, etc. Consequently, the cost and complexity of manufacturing these belts and the tires that use them has risen substantially and it is desirable to standardize on belt components and dimensions as much as possible.

[0006] The use and construction of belts that have cords that form variable angles with the centerline of the belt or equatorial plane of the tire is known in the tire industry. For example, see Japanese Patent Application Publication No. 6-115311 and World Patent Application Publication No. WO 2004062897. These publications disclose machinery that is needed in addition to the machinery typically used in the manufacturing of tires in order to make belts with cords having variable angles. This requires a capital expenditure which may not be desirable. Furthermore, the processes described in these publications sometimes include the laying down of individual strips or cords and/or the varying of the angular rate of rotation and/or axial position of a drum upon which the strips or cords are laid. This is time consuming and therefore more expensive than needed in order to make the use of belts with cords having variable angles practical.

[0007] In contrast, standard tire construction may be performed in the following manner.

First, the carcass, which often acts as the spine that supports the load of the tire, is created by laying a series of components including the bead wires and carcass plies onto a building drum or confection tambour. Second, the summit package which includes the tread stock/rubber that contacts the road and any belts found in the tread stock are laid down sequentially on another drum called a finishing forme. In this operation, the first belt, which is a semi-finished good fabricated using calendaring and extrusion processes, is typically laid down on the center of a drum and held in place by magnets and/or suction cups that are found periodically in the circumferential direction of the forme in some of the movable sections thereof, called movable body segments or shoes. The number of shoes varies based on the maximum diameter of the forme and the design of the manufacturer but a typical number is 24. As can be imagined, it can be difficult to keep a tire component such as a belt to stay on the forme as it can tend to slip off the forme as the forme rotates. For this reason, means to hold the belt onto the forme are provided including magnets and/or suction cups that are found on the surface of the shoes which itself has enough friction to help keep the belt on the forme. After the belt has been laid around the forme as it rotates, the belt is then cut and a joint is created. In the case of steel belts, the joint is created by a diagonal cut found between two steel cords such that the free ends of the belt are butt to butt or overlapped. Next, gum layers or belt edge cushions that are only a fraction of the width of the first belt are applied on top of the first belt adjacent the free side edges of the belt and are adhered thereto by applying force using a roller.

[0008] Then the second belt, which is another semi-finished good, is appropriately positioned on top of the first belt and cushion layers. The second belt is then cut diagonally and another joint is created, similar to the first joint that was made for the first belt. The belts are then adhered to each other by rotating the drum and pressing on the second belt which causes it to stick to the gum layers and first belt. Next, the finishing forme is inflated or moved such that the body segments or shoes expand, causing the outer surface of the forme and all the materials laid on it to expand and simulate the desired shape the summit package will have when the tire is inflated. This is called mechanical conformation. Then, if so desired, a cap layer made of an organic material such as nylon or some other material such as metallic wire, which is intended to limit the radial growth of the tire when rotating at high speeds, is applied on top of the belts. Finally, the tread rubber is then laid down and adhered to the other items already on the finishing forme, completing the summit package which is a subassembly that can be placed onto the carcass as will be discussed in more detail later.

[0009] Of course, the creation of the summit package can be altered depending on the exact architecture that is desired for the tire. For example, the number and placement of the belts and any other component can be changed. Also, other components not specifically mentioned herein can be added by placing them at the appropriate place and time to create the desired tire architecture.

[0010] Once the carcass and summit package have been fabricated, the tire is finished in the following way. First, the carcass is placed onto a finishing drum or tambour. Second, the summit package is transferred to the finishing tambour and placed onto the carcass at the appropriate lateral position. Finally, the summit package is adhered to the carcass by rotating the drum and applying the necessary pressure to make the carcass and summit package stick to each other. The green tire, so called because the rubber components that make up the tire have not been vulcanized, is then sent to a mold or other device where the tire is heated so that vulcanization of the rubber can occur, fixing the geometry and architecture of the tire permanently. While a two step finishing process has been described herein, a one step process where the confection and finishing steps are performed on a single tambour is also commonly used. Of course, there is already a considerable capital investment in the standard machinery and processes used to make tires so it would be advantageous to create variable angled belts by using existing machinery and processes as much as possible.

[0011] Accordingly, there exists a need for an apparatus and method for creating tire belts that have cords posed at variable angles in a time efficient manner using existing machinery that is used in the standard production of tires. Furthermore, it is also desirable if such an apparatus and method allow for the standardization of belt components so that as few variations in the type and dimensions of belts in the green state as possible are needed to further reduce the cost of manufacturing belts and tires. SUMMARY OF THE INVENTION

[0012] An apparatus for building a tire that includes a drum is provided. The drum may have a plurality of movable body segments that each has a surface with a low coefficient of friction.

[0013] In certain embodiments, the surface having a low coefficient of friction may be found in the center portion of the movable body segments and the side portions of the movable body segments may have surfaces with higher coefficients of friction than the center portion. The low friction surface may include a nonstick coating such as that sold under the trademark TEFLON. In certain embodiments, each movable body segment may have a magnet. Alternatively, suction cups may be used.

[0014] A method for manufacturing a tire with belts is provided comprising the following steps. An expandable and contractible drum with a surface having a low coefficient of friction is provided. A first belt with cords arranged at a predetermined configuration and a second belt with cords arranged at a predetermined configuration are provided. The drum is contracted to an initial building configuration. The first belt is laid down at least partially onto said surface of the drum that has a low coefficient of friction. A separation layer is applied onto the first belt. The second belt is laid onto the first belt and separation layer. The second belt is pressed onto the first belt so that a first portion of the first belt adheres to the second belt while a second portion of the first belt does not adhere to the second belt. Finally, the drum is expanded so that the cords of the portions of the first belt and second belt that are adhered to each other pantograph, decreasing their angle with respect to the centerline of the drum while at the same time the cords of the other portions of the first and second belts that are not adhered to each other move so that the angle they form with respect to the centerline of the drum is greater than the angle of the cords of the adhered portions of the belts.

[0015] The separation layer may comprise a plastic film that is laid on top of the first belt.

This method may further include marking a line between a side edge of the belt and the centerline of the drum as a guide for where the separation layer may be placed. Also, the step for providing a drum with a surface having a low coefficient of friction may further comprise applying a nonstick coating, such as that sold under the Trademark TEFLON.

[0016] The foregoing and other objects, features and advantages of the invention will be apparent from the following more detailed descriptions of particular embodiments of the invention, as illustrated in the accompanying drawings wherein like reference numbers represent like parts of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG. 1 is a top view of a belt that has cords posed at variable angles with respect to the centerline of the belt; [0018] FIG. 2A is a perspective view of a building drum according to an embodiment of the present invention in an expanded state with its direction of rotation for building tires shown with no tire components on the drum being shown; [0019] FIG. 2B is a top view of the building drum of FIG. 2A in a contracted state showing the centerline of the drum, magnets and surfaces having a low coefficient of friction of the shoes with no tire components on the drum being shown; [0020] FIG. 3 is a top view of the drum of FIG. 2B that shows a first tire belt with steel cords (only some cords are shown for enhanced clarity) that has been laid down on the circumference of the drum and that has been cut diagonally and joined to itself via a butt to butt joint; [0021] FIG. 4 shows gum layers that have been applied adjacent to the side edges of the first tire belt of FIG. 3; [0022] FIG. 5 shows lines that mark on either side of the center portion of the tire belt of

FIG. 4 the position where separation layers are to be placed; [0023] FIG. 6 depicts the separation layers in the forms of pieces of plastic film that have been wound around the belt of FIG. 5 adjacent the marked lines thereof; [0024] FIG. 7 shows the second belt with steel cords (only some cords are shown for enhanced clarity) that has been placed on top of the first belt and separation layers of FIG.

6 and that has been cut diagonally and joined to itself via a butt to butt joint in similar fashion as the first belt; [0025] FIG. 8 shows the center portions of the first belt and second belt of FIG. 7 being adhered to each other via a roller; [0026] FIG. 9 illustrates the removal of the separation layers from between the first and second belts of FIG. 8; [0027] FIG. 10 shows the belts and drum of FIG. 9 in an expanded state after mechanical conformation where the center portions of the belts where the cords of the belts are adhered to each other have pantographed so that the angle the cords form with the centerline of the belts has decreased while the cords of the shoulder portions of the belts that are not adhered to each other have moved slightly, forming an angle with centerline of the belts that is greater than the angle formed by the cords in the center portion of the belts;

[0028] FIG. HA is a simplified representation of the cords found in the center portion and shoulder portions of the first and second tire belts of FIG. 9 before mechanical conformation, and therefore pantographing, has not occurred;

[0029] FIG. HB shows the pantographing of the cords found in the center portion of the first and second belts and the movement of the cords of the shoulder portions of the first and second belts of FIG. HA after mechanical conformation has occurred; and

[0030] FIG. 12 is a right side view of the belts and drum of FIG. 10 showing their relative movement during mechanical conformation.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0031] Looking at FIGS. 2A and 2B, there is shown a finishing drum or tambour 100 according to one embodiment of the present invention. It comprises, in part, a series of movable body segments or shoes 102 that allow the drum to expand and contract and rotate by means commonly known in the art to establish various tire building stages. Each movable body segment 102 has a strong magnet 104 along its centerline C_L which helps keep tire belts having steel cords centered on the drum 100 as will be described in further detail later. Preferably, there are thee magnets 104 in each shoe 102 with an additional magnet found on either side of the center magnet, all of which are arranged symmetrically about the centerline C_L of the drum 100. However, it is contemplated that fewer or more magnets could be used in each shoe and that some or all the shoes may have no magnets at all. In addition, the center portion 106 of each shoe 102 has a nonstick coating, such as that sold under the trademark TEFLON, which provides a surface having a low coefficient of friction which allows a belt that is posed against this surface to slide relative to this surface easily which is useful to practice the present invention as will be discussed more thoroughly later. In an exemplary embodiment, 24 shoes are used that each have a width of the region having a nonstick coating applied to it of 100 mm (approximately 3.94 inches), which is centered about the centerline C_L of the drum. In order to satisfy this need of reduced friction, magnets 104 are used instead of suction cups because magnets can be placed in a flush to recessed manner on the surface of the shoe to avoid creating friction. In an exemplary embodiment, magnets sold by Bunting Magnetics Co. under catalog # NEP305NP are used. In addition to these added features, the tambour 100 is modified so that it has a fully collapsed state that is smaller than typical.

[0032] However, it is contemplated that suction cups could be used provided that air is blown out of them to create a layer of air as a buffer between a belt and the surface of the shoe to remove friction at the appropriate time before sliding is needed. Likewise, the surface of the shoe having a low coefficient of friction may be made from a material such as a plastic that has an inherently low coefficient of friction. Also as shown by FIG. 2B, the surface of the shoes in the lateral direction is flat but it is contemplated that it could be curved to better conform to the crown of the tire that is manufactured on the tambour. In addition, mechanical means could be incorporated into the tambour to allow independent movement of the center or nonstick portion of the tambour with respect to the outer or higher frictional surfaces to ease the sliding movement of the first tire belt or tire component laid onto the tambour.

[0033] As can be seen, the finishing tambour of this embodiment of the present invention is essentially the same as those already known except for the addition of the nonstick coating, added magnets on each shoe, and modification of the drum so that it can achieve a decreased radius in the fully collapsed state, allowing a finishing tambour according to the present invention to be made quickly and inexpensively from existing equipment already used to produce tires. While a drum using discrete shoes made of aluminum has been disclosed, it is contemplated that this drum could be substituted for one that has a single bladder that can be inflated and deflated and that has a suitable surface having an acceptable coefficient of friction that allows the first tire belt to rotate relative to the drum.

[0034] Turning to FIGS. 3 - 12, the process for creating tires that have belts that have cords posed at various angles with respect to the equatorial plane of a tire is clearly illustrated. This process includes posing several different tire components on the drum 100 and contracting and expanding the drum 100 at different stages. Although the steps will be referred to in numerical order, it is to be understood that some of the steps may be performed in a chronological order that is different than that in which they have been presented and that certain steps may be added or omitted as necessary to create the desired tire architecture.

[0035] First, as best shown in FIG. 3, a first tire belt 108 having steel cords 110 posed at a predetermined configuration is laid onto the finishing tambour 100 in a circumferential direction when the tambour 100 is in its fully collapsed state. The first belt 108 is located such that it is centered on the tambour 100 with its centerline coincident with the centerline C_L of the tambour so that it contacts the surface 106 of the tambour with the nonstick coating on it. For this particular embodiment, the cords 110 are originally posed at a constant angle α with respect to the centerline of the belt and have a consistent initial pace Pi, which is defined as the distance between the centerlines of the cords as measured in a direction that is perpendicular to the cords. However, it is contemplated that the cords could have any desired configuration including those configurations where the angle varies and/or where the pace or distance between the cords changes. Likewise, the cords could be made of a different material than steel such as nylon, glass or any other suitably durable material. Also, it is necessary that the width of first tire belt 108 be greater than the width of previously known first tire belt to accommodate the greater contraction of the width of the belt during mechanical conformation. Once the tambour 100 has rotated 360° so that the first belt 108 has been laid around the entire circumference of the tambour 100, the belt 108 is cut diagonally and joined to itself by way of a butt to butt joint 111 or overlapped joint as is commonly done in the art. It is contemplated that another tire component could be laid on top of the drum prior to the laying of the first tire belt as long as it can slide relative to the drum as discussed previously.

[0036] Second, as best shown by FIG. 4, gum or cushion layers 112 are laid on top of the first tire belt 108 adjacent to the free side edges 114 of the belt 108. These gum layers 112 are used to provide a cushion between the first tire belt 108 and the free edges of the second tire belt to prevent shearing between the two belts once installed and used in a tire. For this particular embodiment, the gum layers 112 are thicker than previously used to help ensure enough of a cushion is provided given the greater amount of movement that occurs during mechanical conformation when using the modified tambour 100 of this embodiment of the present invention which tends to thin out the gum layers more than usual. After being applied onto the first tire belt, the gum or cushion layers are pressed thereon by a roller to ensure that they are fully adhered to the first tire belt (not shown).

[0037] Third, as shown by FIG. 5, lines 116 are marked on top of the first tire belt 108 predetermined distances away from the side edges 114 of the belt 108 toward the center of the belt. This could be done manually by measuring with a ruler and then scribing a line on the tire belt while rotating the tambour 100 or it could be done automatically by using a laser that shines onto the tire belt giving guidance to a tire builder on where to place a separation layer. Of course, the number of lines 116 and their relative position depends on the design of the tire and the number of separation layers that will be used. Typically, a line 116 will be found somewhere in between where the gum layer 112 stops and the centerline C_L of the tire belt or tambour.

[0038] Once the lines 116 have been marked, the next step is to lay down a separation layer 118 covering the area of the first tire belt 108 that lies between each side edge 114 of the belt 108 and a marked line 116 (see FIG. 6). As shown, it is advantageous to allow the separation layer 118 to extend past the free side edge 114 of the belt 108 to ensure proper coverage. This usually includes covering an entire cushion layer 112 found in that region. For this embodiment, that means that there are two separation layers 118 with one posed on either side portion of the first tire belt 108. The separation layer 118 for this embodiment comprises a plastic film that is placed onto one side portion of the first tire belt 108 while the tambour 100 is rotated 360° so that it covers only the portion of the first tire belt 108 found between one side edge 114 and the first marked line 116. This process is then repeated for the other side of the tire belt. It is possible that both plastic films could be laid down simultaneously, if for example, the process was fully automated. It is also possible that the separation layer could take different forms such as wax or stearate or anything else that is capable of keeping the first and second tire belts from adhering to each other in these regions and is compatible with cured tire performance.

[0039] Fifth, after the separation layers 118 have been laid down, the second tire belt 120 having steel cords 122 posed at a predetermined configuration is ready to be posed onto the tambour 100 by placing it on top of the first tire belt 108 and separation layers 118 (see FIG. 7). For this embodiment, the second tire belt 120 is centered with the first tire belt 108 and has less width so that its free side edges 124 will rest on top of the gum layers 112 suitable distances away from the free side edges 114 of the first tire belt 108 and the interior edges 126 of the gum layers 112 once the separation layers 118 have been removed. Typically, the second tire belt 120 has the same initial pace Pi and constant angle α at which its cords are posed as the first belt 108 except that the cords 122 are angled in an opposite fashion with respect to the centerline C_L of the belt. However, its configuration could be different and could include any desired configuration including those where the angle varies and/or where the pace or distance between the cords changes. The second tire belt 120 is wound around the tambour 100 and cut diagonally and joined to itself via a butt to butt joint 128 or overlapped joint in the same way the first tire belt 108 was applied to the drum 100. At this point, the center portions 129 of the first and second tire belts 108, 120 are in contact with each other while their side portions 131 do not touch as the separation layers 118 keep them apart. As shown in FIG. 8, the center portions 129 of the tire belts are then adhered to each other by rotating the tambour 100 and pressing onto the center portions using a roller 130. This could be done either manually or by machine.

[0040] Seventh, the separation layers 118 are removed from in between the first and second tire belts 108, 120 (see FIG. 9). In this embodiment, each of the plastic films are pulled by an operator or robot at one end until it is no longer between the first and second tire belts and is held in place while the tambour 100 is rotated which effectively removes the rest of the plastic films from in between the tire belts. In some cases where the separation layer can be left between the belts and cured into the tire without adversely affecting the properties thereof, as may be the case with wax or stearate, this step may be omitted.

[0041] Eighth as shown by FIG. 10, the tambour 100 is expanded or mechanically conformed to a state where the tread package can be attached. The center portions 129 of the tire belts 108, 120 which have been adhered to each other have steel cords 110, 122 that form a diamond pattern, due to the equal and opposite angles the cords of the belts form with the centerline C_L of the tambour as described above, where the intersections of the cords in the direction of rotation of the tambour 100 act like pin connections 132. As a result, the cords in the center portion 129 of the belts triangulate or pantograph, similar to how a lattice or baby gate looks as it slides open and close (see FIGS. HA and HB to see the original configuration of the cords and their configuration after conformation), as the diameter of the drum 100 increases, which results in the angle the cords of the center portions 129 of the belts form with the centerline C_L of the drum to decrease to β_c. At the same time, the cords 110, 122 found in the side or shoulder portions 131 of the belts move slightly because they are not adhered to each other and form an angle with the centerline of the drum, β_s, which is larger than β_c . These movements are caused by the stretching of the cords in the circumferential direction of the drum, which in turn, causes an inward movement of the cords in the center portions of the belts as they translate toward the centerline C_L of the belts 108, 120 which results in a slight pivoting of the cords in the side portions of the belts because the length of the cords remains fixed. This also results in the reduction of the width of the center portions and overall widths of the belts. Hence, belts with cords posed at variable angles are created that enhance the performance of any tire they are incorporated into for the reasons explained previously in this application.

[0042] It should be noted that other geometrical properties of the tire belts are also altered by this process including the final pace P_fC of the cords in the center region of the belts, which often decreases as compared to the initial pace of the cords Pi, and the final pace Pf_S of the cords in the shoulders of the belts which often increases as compared to the initial pace of the cords Pi. Furthermore, the thickness of the shoulders or side portions 131 of the belts decreases while the thickness of the center portion 129 of the belts increases as compared to previous belts. Accordingly, the thickness of the tread rubber is adjusted to compensate for these changes.

[0043] As best seen in FIG. 12, the importance of the nonstick coating and separation layers 118 can be clearly seen. As the tambour 100 mechanically conforms, the first tire belt 108 rotates in one direction with respect to the tambour 100 while the side portions 131 of the second belt 120 rotate in the opposite direction with respect to the first belt 108. These relative movements allow the cords of the first and second belt to pantograph and move as needed in the appropriate amounts and directions to achieve the desired geometry. Without the ability of the first tire belt 108 to slide freely with respect to the tambour 100 and the side portions of the second belt 120 to slide relative to the side portions of the first belt 108, the desired geometry in the center and side portions of the belts could not be achieved. Often, the portions of first and second tire belt that were originally separated are adhered to each other using a roller after mechanical conformation has occurred so that they are properly adhered to each other before other components are added onto them.

[0044] The following is an exemplary case for the present invention. First, the radius of the tambour in its fully collapsed state is 290 mm (approximately 11.4 inches), which is 30 mm (approximately 1.2 inches) less than what has been done previously. Also, the width of first tire belt 108 is greater than what has been previously done and is in the range of 245 - 250 mm (approximately 9.6 - 9.8 inches) to accommodate the greater contraction of the width of the belt during mechanical conformation. The width of the second tire belt 120 is 32 mm (approximately 1.26 inches) less than that of the first tire belt 108, which means that its free edges 124 are 16mm away from the free edges 114 of the first tire belt 108 initially. On rare occasions, the second tire belt could be wider than the first tire belt. Both belts 108, 120 have cords 110, 122 that are originally posed at a constant angle α of 41° and an initial pace Pi of 2.25 mm (approximately .09 inches). After being laid on the tambour 100 per the process outlined above, the belts are mechanically conformed as the radius of the drum increases by 20%. As a result of the pantographing and movement of the cords due to the expansion of the drum 100, the angle the cords 110, 122 of the center portions of the belts form with the centerline C_L of the drum decreases to an angle β_c of approximately 22° while the angle the cords 110, 122 of the shoulder portions of the belts form with the centerline C_L of the drum decreases only slightly to an angle β_s of approximately 36°. At the same time, the pace of the cords in the center portions of the belts after conformation changes to a final pace Pf_C of 1.62 mm (approximately .06 inches) while the pace of the cords in the shoulder portions of the belts after conformation changes to a final pace Pf_S of 2.51 mm (approximately .1 inches). Also, the original thickness of the first and second tire belts taken together is 3.42 mm (approximately .13 inches). This shape changes to 5.86 mm (approximately .23 inches) in the center of the belts and 2.87 mm (approximately .11 inches) in the shoulder regions of the belts after conformation. Again, this can be compensated for by adjusting the thickness of the rubber of the tread in the appropriate places.

[0045] While one exemplary case has been shown, it is to be understood that other belt configurations can be used such as those that have an initial angle α that ranges from 23.5° to 41° and an initial pace Pi of 2.25 mm (approximately .09 inches), which are mechanically conformed by increasing the radius of the tambour by 2.5 - 20%, which results in changed angles of β_c, ranging from 22 - 24°, and of β_s, ranging from 24 - 36°. This also results in a change in the final paces of the cords to Pf_C, ranging from 1.62 - 2.04 mm (approximately .06 - .08 inches), and to Pf_S, ranging from 1.95 - 2.51 mm (approximately .076 - .1 inches). Accordingly, it is contemplated that by choosing suitable original configurations of the belts and the correct conformation processes that a wide array of final configurations of the belts can be achieved. Thus, this apparatus and method allows for the standardization of the belts to include fewer initial or green configurations, so called because the rubber of the tire components has not yet been vulcanized, since this process allows for a variety of final or cured configurations, so called because the rubber of the tire components has been vulcanized, by simply changing the amount of conformation.

[0046] In addition, other components for a tire can be added on top of the tire belts as discussed above. These components include a cap ply that may be of nylon or some other type of summit reinforcement. Also, additional belts may be added. Finally, after all the desired components have been placed at the appropriate time and location, the tread rubber can be added, completing the summit package which can then be applied to the carcass of the tire by means commonly known in the art. Of course, the present invention can be used in the construction of pneumatic and non-pneumatic tires alike.

[0047] As can be seen, the apparatus and method of the current invention provides a way to economically manufacture tires that have belts with cords posed at variable angles to improve tire performance simply by making inexpensive modifications to existing equipment used for the manufacture of tires. Furthermore, this method allows multiple final belt configurations to be created by using fewer initial configurations, facilitating the standardization and reduction of the number of the types of belts needed to be made and kept in inventory for manufacturing tires of various sizes and shapes. Thus, this method and apparatus satisfy the aforementioned needs.

[0048] The terms "comprising," "including," and "having," as used in the claims and specification herein, shall be considered as indicating an open group that may include other elements not specified. The term "consisting essentially of," as used in the claims and specification herein, shall be considered as indicating a partially open group that may include other elements not specified, so long as those other elements do not materially alter the basic and novel characteristics of the claimed invention. The terms "a," "an," and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The terms "at least one" and "one or more" are used interchangeably. The terms "preferably," "preferred," "prefer," "optionally," "may," and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention. Ranges that are described as being "between a and b" are inclusive of the values for "a" and "b."

[0049] It should be understood from the foregoing description that various modifications and changes may be made to the embodiments of the present invention without departing from its true spirit. The foregoing description is provided for the purpose of illustration only and should not be construed in a limiting sense. Only the language of the following claims should limit the scope of this invention.

Claims

CLAIMSWhat is claimed is:

1. An apparatus for building a tire including a drum comprising: a plurality of movable body segments, each with a portion that has a low friction surface.

2. The apparatus of claim 1 wherein said low friction surface is found in the center portion of each movable body segment and wherein the side portions of the movable body segments have surfaces with higher coefficients of friction than said center portion.

3. The apparatus of claim 2 wherein said low friction surface comprises a nonstick coating.

4. The apparatus of claim 1 wherein each movable body segment has at least one magnet.

5. The apparatus of claim 1 wherein each movable body segment has at least one suction cup.

6. The apparatus of claim 1 wherein the apparatus is expandable and contractible through various stages, thereby changing the radius of said drum, said stages including a collapsed state where belts are applied and an expanded state where the tread rubber is applied.

7. A method for manufacturing a tire with belts comprising the following steps: providing an expandable and contractible drum with a surface having a low coefficient of friction; providing a first belt with cords arranged at a predetermined configuration and a second belt with cords arranged at a predetermined configuration; contracting the drum to an intial building configuration; laying down the first belt at least partially onto said surface of the drum having a low coefficient of friction; applying a separation layer onto the first belt; laying a second belt onto the first belt and separation layer; pressing the second belt onto the first belt so that that a first portion of the first belt adheres to the second belt while a second portion of the first belt does not adhere to the second belt; and expanding the drum so that the cords of the portions of the first belt and second belt that are adhered to each other pantograph, decreasing their angle with respect to the centerline of the drum while at the same time the cords of the other portions of the first and second belts that are not adhered to each other move so that the angle they form with respect to the centerline of the drum is greater than the angle of the cords of the adhered portions of the belts.

8. The method of claim 7 wherein the separation layer comprises a plastic film that is laid on top of the first belt.

9. The method of claim 7 which further comprises marking a line between a side edge of the belt and the centerline of the drum.

10. The method of claim 9 which further comprises marking a second line between the other side edge of the belt and the centerline of the drum.

11. The method of claim 10 wherein said separation layer is laid onto the first belt from the first marked line up to its first side edge and wherein a second separation layer is laid onto the first belt from the second marked line up to the second side edge of the first belt.

12. The method of claim 7 which further comprises removing the separation layer before the drum has expanded and the desired configuration of the cords of both belts has been achieved.

13. The method of claim 7 which further comprises placing a cushion layer onto the first belt and adhering it thereto.

14. The method of claim 7 which further comprises placing a cap ply on top of the second belt and adhering it thereto.

15. The method of claim 14 which further comprises placing the tread rubber on top of the cap ply and adhering it thereto, completing the formation of a summit package.

16. The method of claim 15 which further comprises providing a carcass and placing it on a finishing drum.

17. The method of claim 16 which further comprises placing the summit package on top of the carcass and adhering it thereto, completing the fabrication of a green tire.

18. The method of claim 17 which further comprises vulcanizing the rubber components of the green tire.

19. The method of claim 7 wherein said step for providing a drum with a surface having a low coefficient of friction further comprises applying a nonstick coating.

20. A tire made according to the method of claim 7.