WO2004060642A2

WO2004060642A2 - Tire building apparatus and assembly process

Info

Publication number: WO2004060642A2
Application number: PCT/US2003/041595
Authority: WO
Inventors: David William Bailey; Daniel Andre Dupuis; William George Steiner; John Foster Collins
Original assignee: Societe De Technologie Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2002-12-30
Filing date: 2003-12-29
Publication date: 2004-07-22
Also published as: AU2003300087A1; AU2003300087A8; WO2004060642A3

Abstract

The present Invention relates to an apparatus (10) that is used in the building of a tire and an assembly process for building a tire. The apparatus comprises a building drum (100) that is provided with a plurality of drum segments (120) disposed concentrically about the axial Center of the drum and which are movable in both the axial and radial directions and is fixed to the main shaft (15) in rotation. The drum segments (120) further comprise right (130a) and left (130b) shoulders located axially at the lateral edges, and the base of each of the shoulder extends axially to form a lateral projection (135a, 135b). The apparatus further comprises at least a right (150) and a left (160) side assembly coaxially attached to the main shaft (15) and located proximately to the lateral projection (135a,135b) of the drum segments.

Description

TITLE OF THE INVENTION

Tire Building Apparatus and Assembly Process

TECHNICAL FIELD

[0001] The present invention relates generally to a tire building apparatus and assembly process for building pneumatic tires.

BACKGROUND

[0002] Certain tires may have a bead architecture that is different from conventional pneumatic tires. The bead architecture may be designed in such a way that upon a loss of air pressure to the tire, the beads maintain an improved grip on the rim to better retain the tire on the rim than in conventional pneumatic tires. One design of this type of tire is illustrated in United States Patent Numbers 5,785,781 and 5,971,047 that are owned by the assignee of the present invention and are incorporated by reference herein in their entirety for all purposes. Figure 1 depicts an example of a tire having this bead architecture. See, for example, Fig. 2 of United States Patent Number 5,971,047 for a detailed view of the bead construction.

[0003] The construction of a pneumatic tire often involves a two-stage process. The first stage comprises the building of the beads and carcass of a tire on a drum. The tire is then moved to another drum in which the second stage of the tire building process occurs. Here, belts, an unfinished tire tread, and/or possibly sidewalls are added to the tire. However, it is also known in the art to provide a single drum that allows the combining of these two stages. Such a process is typically known as a unistage building process because the steps occur on a single drum. [0004] Previously known methods of building the bead architecture shown in Fig. 1 employ at least the steps of first placing an uncured rubber section on the casing carcass followed by folding of the extremity of the carcass around the rubber section. These methods may suffer from variations in the precision and placement of an uncured rubber section in the bead during the manufacturing of tires. In addition, precision in the finished tire is impacted further if the uncured rubber section does not remain substantially stationary, but is allowed to rotate or otherwise distort, during the carcass folding step. [0005] The present invention improves upon previous building methods and drums used in building a tire by providing a tire building apparatus and assembly process that is capable of producing a tire having a consistent tire bead architecture.

SUMMARY OF THE INVENTION

[0006] The present invention relates to an apparatus that is used in the building of a tire and an assembly process for building a tire. The apparatus comprises an apparatus frame and a main shaft that is rotatable in at least one axis about the apparatus frame. The apparatus further comprises a building drum that is provided with a plurality of drum segments disposed concentrically about the axial center of the drum. The plurality of drum segments is movable in both the axial and radial directions and is fixed to the main shaft in rotation. Each of the plurality of drum segments forms a section of an outer surface of the drum that comprises a substantially cylindrical main receiving surface to receive the products to be assembled. The drum segments further comprise right and left shoulders located axially at the lateral edges of the main receiving surface. The base of each of the shoulder extends axially to form a lateral projection or nose section, thereby forming a secondary support surface whose outside diameter is smaller than the diameter of the main receiving surface. At least one version of the apparatus has right and left shoulders of unequal heights to facilitate fabrication of tires having unequal bead seat diameters. Each shoulder has a transition radius that is proportionate to the height of the respective shoulder. [0007] The apparatus further comprises at least a right and a left side assembly coaxially attached to the main shaft and located proximately to the respective lateral projection of the drum segments. The side assemblies form substantially cylindrical auxiliary receiving surfaces, also capable of receiving the tire products to be assembled. At least one side assembly is capable of sliding axially at least partly under the lateral projection. Furthermore, at least one side assembly is capable of radial expansion and retraction. [0008] The side assemblies may further comprise a plurality of radially expandable nose tab segments similar to the drum segments. A set of expandable turn-up bladders is located proximately and axially outward of the nose tab segments of the right and left side assemblies. Expansion of the turn-up bladders aids in the production of the tire. The turn-up bladders may be expanded and maintained in either partial or fully inflated positions. In the partially inflated positions, the turn-up bladder aids in maintaining a precise positioning of the bead products.

[0009] The present invention also includes an apparatus for building a tire where the drum segments and nose tab segments further comprise a means for positioning the respective segments a plurality of radial positions.

[0010] The present invention also includes an assembly process for building a tire comprising the steps of: providing an apparatus comprising a drum having a substantially cylindrical main receiving surface to receive the products to be assembled, said main receiving surface being radially movable, said drum comprising a right and a left shoulder located axially at the lateral edges of said main receiving surface, and said shoulders being axially extended in the form of a lateral projection; and said apparatus further comprising at least a right and a left side assembly, wherein each of said side assemblies has a nose tab and a substantially cylindrical auxiliary receiving surface; positioning radially said main receiving surface and said right and left auxiliary receiving surfaces at substantially equal radial positions; applying an inner layer complex on said main receiving surface and on said right and left auxiliary receiving surfaces and overhanging said shoulders of said drum; applying a carcass reinforcement on said inner layer complex; expanding radially said main receiving surface a radial distance at least equal to the height of said right shoulder; expanding radially at least said left side assembly a radial distance at least equal to the height difference between said right and left shoulders; placing an uncured rubber section on said carcass reinforcement at an axial location radially outward of said nose tab; folding said inner layer complex and said carcass reinforcement around said uncured rubber section such that the orientation of said uncured rubber section remains substantially stationary; placing a bead reinforcement on the fold thus made, axially to the interior of the location where the uncured rubber section is laid; placing an bead filler section on said bead reinforcement; dilating said uncured rubber section. [0011] The present invention also includes an assembly process for building a tire as discussed previously where the bead filler and bead reinforcement are formed from a unitary bead complex. The steps of placing the bead reinforcement and placing the bead filler section are thereby combined in a single step to simplify assembly of the bead.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 - Cross section view of a tire having a bead architecture exemplary of the type to be fabricated by the apparatus of the invention.

[0013] Figure 2 - Detailed view of the first embodiment of the invention showing an axial cross- section of the apparatus in the initial set position to receive tire products and with the drum segments at minimum axial expansion.

[0014] Figure 3 - Detailed view of the first embodiment of the invention showing an axial cross- section of the apparatus in the conformation position with the drum and left-hand side assembly at maximum radial expansion.

[0015] Figure 4 - Detailed view of the first embodiment of the invention showing both side assemblies fully under the drum shoulders. [0016] Figure 5 - Detailed view of the first embodiment of the invention showing an axial cross- section of the apparatus in the initial set position to receive tire products and with the drum segments at maximum axial expansion. [0017] Figure 6 - Simplified view of the first embodiment of the invention showing an axial cross- section of the apparatus in the conformation position and with the drum segments at minimum axial expansion. [0018] Figure 7-a through Fig. 7-n are schematic representations in axial cross-section of the several steps in the assembly process of a tire according to the first embodiment of the invention.

Detailed Description

[0019] Reference will now be made in detail to exemplary versions of the invention, one or more versions of which are illustrated in the drawings. Each described example is provided as an explanation of the invention, and not meant as a limitation of the invention. Throughout the description, features illustrated or described as part of one version may be usable with another version. Features that are common to all or some versions are described using similar reference numerals as further depicted in the figures.

[0020] Figure 2 depicts an apparatus 10 for building a tire corresponding to a first embodiment of the invention comprising an apparatus frame 11 and a main shaft 15, and a tire building drum 100. The tire building drum 100 is configured for building tires having unequal bead diameters such as the tire shown in Fig. 1. The main shaft 15 of the apparatus is attached to the apparatus frame 11 so that the shaft can rotate at least about its longitudinal axis X-X to allow the laying of tire components during the building process. The main shaft 15 can be attached to the frame 11 to also allow rotation about a vertical axis Z-Z passing through the apparatus frame. This second axis of rotational freedom allows the entire apparatus to rotate from at least a first to a second tire building stage. The multiple stages may be configured to complete the carcass-building steps, or a combination of stages to build both the carcass and to build the belt package and tread band. In the detailed description that follows, reference is made to the right and left sides of the apparatus 10. Note that "right" and "left" are only descriptive terms that apply to a particular figure. It is within the scope of the invention to include an apparatus configured as a mirror image of the apparatus shown in the figures.

[0021] Figure 6 shows a simplified axial cross section of the apparatus 10 that permits a better explanation of the invention. The building drum 100 includes a plurality of drum segments 120 located radially about the axial centerline of the drum 10. The drum segments 120 are movable in both the axial and radial direction of the apparatus. Each of the drum segments forms a section of an outer surface of the drum 100 that comprises a substantially cylindrical main receiving surface 101 to receive the products to be assembled. As shown in Fig. 6, the drum segments 120 may comprise an assembly of right half- segments 125a and left half-segments 125b joined in the center by segmented slats 127. The right and left half-segments are capable of independent axial movement and are fixed in rotation to the main shaft 15. Thus, the drum 100 can be configured to build several different tire sizes by positioning the assembly of drum segments 120 to various axial widths to accommodate tires having different carcass layer lengths. Figure 2 shows the drum set to its minimum axial width, and Fig. 5 shows the drum set to its maximum axial width. Alternatively, the drum segments 120 may each be comprised of a single article with a predetermined, fixed axial width to accommodate tires having a single carcass layer length. [0022] The plurality of drum segments 120 can be expanded to various radial locations to establish a series of nearly cylindrical receiving surfaces 101 to support the tire products. If the number of drum segments is large, the tire products are well supported since the receiving surface 101 is nearly cylindrical and the gaps between the segments are small. When there are few drum segments, the gaps can become large and the receiving surface will have a more polygonal shape. It is desirable to build the tire on a surface that is most nearly cylindrical. Therefore, the required number of drum segments is a compromise between the mechanical complexity of a large number of segments weighed against fewer segments that provide less uniform support to the tire products and provide a less cylindrical receiving surface 101. For the instant invention, twenty-four drum segments provides adequate support of the tire products. [0023] The drum segments 120 further comprise a right-hand lateral shoulder 130a and a left-hand lateral shoulder 130b located at the lateral edges of the main receiving surface 101. The base of each of the shoulders 130a and 130b further extends axially to form a set of lateral projections or nose sections, 135a and 135b, respectively. The exterior surface of each lateral projection forms a set of secondary support surfaces 136a and 136b whose outside diameters are smaller than the diameter of the main receiving surface 101. The secondary support surfaces of the nose sections are defined by a radius of about 6 mm to about 10 mm tangent to the shoulders and whose centers C are noted by a "+" in Fig. 6. The secondary support surfaces help to position the bead products during the final steps of bead formation.

[0024] The drum segments 120 have a shoulder height measured between the outer surface 101 and a horizontal line passing through the centers C of the radius forming the secondary support surfaces. The shoulder height is identified in Fig. 6 as Ha for the right shoulder 130a and Hb for the left shoulder 130b. In addition, the right and left shoulders have respective transition radii Ra and Rb to allow the carcass products to smoothly conform to the outer surfaces of the shoulders. It is advantageous for the transition radii to be proportionate and of a substantially similar magnitude to the shoulder heights. That is, a drum segment with a high shoulder will necessitate a larger expansion of the carcass layer during the conformation step. Expansion of a cord reinforced carcass layer takes place by a plastic deformation of the uncured rubber between the cords. If the expansion is too great, the rubber may undergo non-uniform expansion or even rupture. This deformation is most tortuous in the transition area near the shoulder. In this case, a larger shoulder radius facilitates the expansion of the carcass layer and avoids adverse effects that could affect tire quality.

[0025] As shown in Fig. 6, the completed tire would have a larger bead seat diameter on the left side. During the tire design process, the tire designer's choice of bead seat diameter for the right and left bead seats of the finished tire determines the diameter of the bead reinforcement BRW. Typically, tires having the bead architecture shown in Fig. 1 have bead seat diameters Da and Db differing by about 8 mm to about 12 mm. In turn, the diameter of the bead reinforcement BRW determines the radial position of the secondary support surfaces 136a and 136b. Since the main receiving surface 101 remains substantially cylindrical, the shoulders 130a and 130b of drum 100 must now have different heights. The shoulder height Ha is greater than the shoulder height Hb by an amount substantially equal to the difference in bead seat diameters of the finished tire. For the embodiment of the invention shown in Figure 6, the bead seat diameters are different by 10 mm. The right shoulder 130a has a height Ha between about 20 mm to about 24 mm, and preferably about 22 mm. Likewise, the left shoulder 130b has a height Hb between about 10 mm to about 14 mm, and preferably about 12 mm.

[0026] The shoulder height difference presents additional challenges for the design of a tire building apparatus. During the process of building the tire carcass, the drum 100 expands from the initial set diameter a shown in Fig. 7-a to the conformation diameter as shown in Fig. 7-d. The carcass ply is forced to conform to the exterior profile of the drum segments in a step called "ply-down." To facilitate ply- down without adverse affects on the carcass layer fabric, the transition radius Ra on the right (higher) shoulder is larger than the transition radius Rb on the left (lower) shoulder. The drum 100 employs a right-hand transition radius Ra of about 17 mm and a left-hand transition radius Rb of about 12 mm. [0027] The drum 100 includes a means for radially positioning the drum segments during the conformation steps. Suitable examples of such means are mechanical linkages, electrodynamic actuators, hydraulic actuators, or pneumatic assemblies. For the drum 100 shown in Fig. 2, pneumatic assemblies position the segments. These assemblies comprise an inner base 170, a plurality of outer base segments 175 and an expansion bladder 177. The inner annular base 170 is coaxial with and fixed in rotation with the main shaft 15 and is adjustable in axial position relative to the shaft. The plurality of outer base segments 175 is fixed in rotation with the main shaft 15, but may move freely in radial motion relative to the inner base 170. Each of the outer base segments 175 is attached to an adjacent drum segment 120. An expandable pneumatic bladder 177 is interposed between the inner base 170 and the outer base segments 175. When air pressure expands the bladder 177, the outer base segments move radially outward to position the drum segments 120 at the required position. A key may be present and be connected to the inner base 170. The key may communicate with a keyway that is an extension of the outer base segment 175. The key may provide for radial stability during movement of the drum segment 120. The radial positions may be controlled by a variety of means such as fixed or adjustable stop blocks. The present embodiment obtains a guidance of the drum sectors both axially and radially by a guide rod attached to the inner base 170 that slides in a guide tube in the outer base 175.

[0028] The apparatus 10 further comprises right and left side assemblies 150 and 160 mounted coaxially with the drum and located proximately to the lateral projections 135a and 135b of the drum segments 120. The axially outermost surfaces of the right and left side assemblies 150 and 160 form substantially cylindrical auxiliary receiving surfaces 15 ϊ and 161, respectively, also capable of receiving the tire products to be assembled. The apparatus 10 further comprises a means for axially positioning the side assemblies. For the drum 100 depicted in Fig. 6, both side assemblies 150 and 160 are capable of sliding axially at least partly under its respective lateral projection 135a or 135b. Suitable examples of such means are mechanical linkages, electrodynamic actuators, hydraulic actuators, or pneumatic assemblies. This version of the apparatus 10 utilizes a plurality of air piston actuators 190 to retract or extend the side assemblies. The actuators 190 have an axial excursion sufficient to retract the side assemblies 150 and 160 axially outside of the lateral projections 135a and 135b and to extend the side assemblies at least party or fully under the lateral projections.

[0029] The right and left side assemblies 150 and 160 each further comprise set of expandable turnup bladders 180 located proximately and axially outward of the auxiliary receiving surfaces 151 and 161. Control of the expansion of the turn-up bladders 180 aids in the formation of the tire bead. When the turn-up bladders 180 are fully deflated, their radially outer surfaces form substantially cylindrical extensions of the auxiliary support surfaces 151 and 161 and provide additional support for the tire products. The turn-up bladders 180 are expandable either to a partially inflated position as depicted in Fig. 7-i or to a fully inflated position as shown in Fig. 7-1. When the bladder 180 maintains a partially inflated position as depicted in Fig. 7-i, the surface of the turn-up bladder 180 forms a bearing surface that aids in maintaining a precise positioning of the bead products.

[0030] When the drum 100 is set to the initial diameter for receiving the inner layer complex and carcass layer, the drum segments 120 and side assemblies 150 and 160 are set to substantially equal radial positions forming a wide, substantially cylindrical, support surface for the entire width of the carcass products. However, during the conformation step proceeding the placing of the uncured rubber section PRS, the drum segments 120 expand radially by an amount at least equal to Ha. One observes that the left side assembly 160 must expand radially by an amount equal to the height difference Ha-Hb so as to place the left auxiliary receiving surface 161 at its correct radial position proximate to the left secondary support surface 136b. Therefore, at least one the side assembly assemblies must be capable of radial movement in addition to axial movement. The left side assembly 160 of the drum 100 comprises a plurality of side assembly segments 165 that are capable of both radial and axial movement. A radial positioning means permits the radial movement of the side assembly segments 165. Suitable examples of such means are mechanical linkages, electrodynamic actuators, hydraulic actuators, or pneumatic assemblies. Figure 6 shows the side assembly segments 165 positioned by pneumatic assemblies that are substantially similar to those used to position the drum segments 120. Furthermore, if the process used to build the tire requires a radial expansion of the drum segments 120 by an amount greater than Ha, then the right side assembly 150 may likewise be capable of both radial and axial movement by the types of positioning means just described. In this manner, the apparatus 10 is capable of manufacturing a variety of tire bead architectures.

[0031] In a second embodiment of the invention, an apparatus 20 is intended to manufacture tires having bead seats of equal diameter. In this case, a drum 200 has shoulders 230a and 230b having equal heights and having equal transition radii. That is to say, the height Ha is equal to the height Hb and the radius Ra is equal to the radius Rb. Since the shoulders of drum 200 now have equal heights, it is no longer required to radially expand the left side assembly 260. Thus, the apparatus 20 comprises a simplified design having side assemblies 250 and 260 that are fixed radially, but are capable of sliding axially at least partly under the respective lateral projection 235a or 235b. The side assembly 150 of the first embodiment provides an example of a suitable design for both the right side assembly 250 and left side assembly 260 of the apparatus 20.

[0032] The assembly process for the manufacture of a tire carcass using an apparatus such as the embodiment of the invention typified by apparatus 10 will now be described in detail. The tire carcass comprises an inner layer complex, a cord reinforced radial carcass layer, a pair of beads for engaging the tire with a mounting rim wherein the beads have different bead seat diameters, and at least one bead reinforcement in each of the beads. More specifically the tire carcass has a bead architecture where the lateral extremity of the carcass layer forms a fold such that the folded extremity passes between the carcass layer and the bead reinforcement. One skilled in the art recognizes that the apparatus 10, the apparatus 20, and the process of manufacture described herein may be adapted to a variety of tire architectures having additional tire products or fewer tire products and is not limited to radial carcass tires. Moreover, the process and apparatus may be practiced either as a two-stage or single-stage process, the latter yielding a completed tire including sidewall products, tread reinforcements, and tread bands. [0033] Figure 7-a through Fig. 7-n are schematic representations in axial cross-section of the several steps in the manufacture of a tire according to the first embodiment of the invention where the apparatus 10 is configured to build tires having unequal bead seat diameters. The operation of the process to manufacture a tire according to the second embodiment is easily deduced from the former. The physical articles comprising the apparatus are noted by the same reference numerals as used for the apparatus 10 and as shown in Fig. 6. The tire products required to build the tire carcass are noted by uppercase alphabetic characters. A given tire design may use more or fewer tire products without departure from the scope of the invention.

[0034] According to Fig. 7-a the drum 100 is set to its first working configuration by positioning radially the main receiving surface 101, the right auxiliary receiving surface 151 and left auxiliary receiving surface 161 at substantially equal radial positions. The side assembly 150 and 160 are positioned in their fully retracted axial positions. A sheet of rubber for the inner layer complex IL is first laid on the receiving surfaces a shown in Fig. 7-b. The inner layer complex IL comprises a pre- complexed assembly of an inner layer and a rim protector rubber that is laid as single product for manufacturing efficiency. However, the reference to "inner layer complex" as used herein can apply equally to a single rubber sheet or a complex of a plurality of products. Next, Fig. 7-c shows the laying of a carcass layer CL. The lateral extremities CL' of the carcass layer overlap the extremity of the inner layer complex and protector and are supported by the axially outer surface of the side assemblies 150 and 160 and the turn-up bladders 180. Uncured rubber products are easily stretched or distorted from their desired shapes. Thus, an advantage of the invention is that these first tire product layers receive substantially uniform support across the entire width. This configuration facilitates more accurate positioning of the products and reduces unwanted stretching or distortion.

[0035] Then, in Fig. 7-d, air pressure is applied to the pneumatic bladders 177 to expand the assembly of drum segments 125a and 125b and slats 127 radially outward a distance equal to the height HA of the right shoulder 130a. In cooperation with the expansion of the drum segments, the left side assembly 160 also expands radially outward a distance at least equal to the height difference Ha-Hb between the right and left shoulders. Elasticity of the uncured carcass layer products should be sufficient to conform these products to the exterior contour of the drum as depicted in Fig. 7-d. However, in some cases, it may be advantageous for the operator to apply external pressure to the carcass products to more closely conform them to the contours of the shoulders 135a and 135b and particularly to the contours of the lateral projections 136a and 136b. The carcass layer CL is now ready to accept the profiled rubber section PRS.

[0036] Now, the operator performs the critical step of placement of the profiled rubber section PRS on the carcass layers. The rubber section PRS is generally prepared by extrusion to a predetermined cross section or profile and is posed on the carcass in its uncured state. In Fig. 7-e the rubber sections PRS are posed on carcass layer CL radially outward of the auxiliary receiving surfaces 151 and 161, and axially abutting the lateral projections 136a and 136b. Here, another advantage of the invention is apparent. The precision of the position of the rubber section PRS is critical to the accurate formation of the fold of the carcass layer. As is readily appreciated form Fig. 7-e, the location of the rubber section PRS gains precision in the radial direction by virtue of the rigid auxiliary receiving surfaces 151 and 161, and in the axial direction by the outer extremities of the lateral projections 136a and 136b.

[0037] According to Fig, 7-f, the turnup bladders 180 are now partially inflated and their exterior surfaces lift the carcass extremity CL' and rotates the extremity CL' about the rubber section PRS so that the latter remains substantially stationary and the carcass extremity CL' is left in a substantially vertical position. The bladders 180 are then deflated as shown in Fig. 7-g and the bead reinforcement BRW translates axially until it contacts the lifted extremity of the carcass layer CL'. Now, the bead reinforcement BRW continues its axial translation and passes over and axially inward of the rubber section PRS until the fold of the carcass layer is completed. In its final position, as shown in Fig. 7-h, the bead reinforcement establishes contact with the carcass layer over a substantial surface area thereby ensuring good green adhesion of the products and a tight fold of the carcass layer extremity CL' around the rubber section PRS.

[0038] Next, the turnup bladders 180 are again partially inflated prior to the placement of the bead filler section BF as shown in Fig. 7-i. Partial inflation of the turnup bladders causes a partial inward rotation of the rubber section PRS in the direction of the bead reinforcement BRW and applies pressure to maintain the position of the bead reinforcement against the shoulders 135a and 135b. The turnup bladders remain inflated during the application of the bead filler section BF as shown in fig. 7-j, thereby inhibiting movement of the bead reinforcement BRW. Thus, the bead components are laid with an improved level of accuracy and repeatability.

[0039] Figure 7-k and Fig. 7-1 show the steps to dilate the rubber section PRS and to complete the formation of the bead. First, the turnup bladders 180 are fully deflated, then the actuators 190 translate the side assemblies 150 and 160 axially inward to a position fully under the lateral projections 135a and 135b of the respective shoulders 130a and 130b. Finally, the turnup bladders 180 fully reinflate causing the folded carcass and the rubber section BRS to further radially expand and to rotate to a position where these products contact the bead reinforcement BRW and bead filler BF. The rubber-to-rubber contact between the carcass layer, the rubber section BRS, and the filler BRW forms an adhesive bond between the products so that the products will remain adhered to each other during subsequent process steps. [0040] To complete the carcass building cycle, the turnup bladders 180 fully deflate and the side assemblies 150 and 160 axially retract as shown in Fig. 7-m. Finally the drum segments 120 and the left side assembly 160 both radially retract as shown in Fig. 7-n, thereby placing the drum 100 in the set position to start a new cycle. In this position, the completed carcass is easily removed from the drum. [0041] It should be understood that the present invention includes various modifications that can be made to the embodiments of the tire apparatus described herein as come within the scope of the appended claims and their equivalents.

Claims

CLAIMSWe claim:

1. An apparatus for building a tire comprising: an apparatus frame and a main shaft rotatable in at least one axis about said frame; a building drum fixed coaxially to said main shaft and fixed in rotation with said main shaft, said building drum comprising a plurality of drum segments and a means for radially positioning the outer surface of said drum segments at a plurality of specified radial positions, whereby the outer surface of said segments forms a sector of a substantially cylindrical main receiving surface for receiving the tire products to be assembled; at least a right and a left side assembly attached coaxially to said main shaft and fixed in rotation with said main shaft, and each of said side assemblies positioned proximately to the respective lateral sides of said drum, each of said side assemblies comprising a nose tab, a means for manipulating tire products, and a means for axially positioning said side assembly relative to said drum, wherein the radially outer surface of said side assembly forms a substantially cylindrical auxiliary receiving surface for the tire products to be assembled, and at least one of said side assemblies further comprising a means for radially positioning said nose tab and said auxiliary receiving surface at a plurality of radial positions.

2. The apparatus for building a tire according to claim 1, wherein each of said drum segments further comprises: a right and a left shoulder located at the respective lateral edges of said segment and each shoulder having a vertical height and a transition radius joining said main receiving surface to the outer surface of said shoulders, , a radially innermost portion of said shoulders extended laterally to form a right and a left lateral projection, wherein the outer surface of said projection forms at least a sector of a secondary support surface for receiving the tire products to be assembled, and said main receiving surface having an outside diameter greater than the outside diameter of said secondary support surface.

3. The apparatus for building a tire according to claim 2, wherein the height of said right shoulder is greater than the height of said left shoulder.

4. The apparatus for building a tire according to claim 3, wherein said right shoulder height is between about 20 mm to about 24 mm and said left shoulder height is between about 10 mm to about 14 mm.

5. The apparatus for building a tire according to claim 2, wherein said transition radius on each of said shoulders is proportionate to the height of said shoulder.

6. The apparatus for building a tire according to claim 5, wherein said transition radius of said right shoulder is about 17 mm and said transition radius of said left shoulder is about 12 mm.

7. The apparatus for building a tire according to claim 1, wherein said means for positioning said drum segment comprises: an inner annular base coaxial with and fixed in rotation with said main shaft, said base being adjustable in axial position relative to said main shaft; a plurality of outer base segments fixed in rotation with said shaft and free in radial motion relative to said inner base, and each of said outer base segments is attached to one of said drum segments; a radially expandable pneumatic bladder interposed between said inner base and said outer base segments.

8. The apparatus for building a tire according to claim 1, wherein each of said drum segments further comprises a right half-segment, a left half-segment, and a slat contacting and overlapping the central portions of said half segments, each of said half-segments having a shoulder and said shoulder axially extends to form a lateral projection, whereby the outer surfaces of said half- segments and of said slat form a sector of said main receiving surface.

9. The apparatus for building a tire according to claim 1, wherein said means for positioning said side assemblies has an axial excursion sufficient to position said nose tabs at least partly under said lateral projections and to position said nose tabs axially outside of said lateral projections.

10. The apparatus for building a tire according to claim 9, wherein said means for axially positioning said side assemblies is a plurality of pneumatic actuators fixed to said main shaft.

11. The apparatus for building a tire according to claim 1, wherein said means for radially positioning at least one of said auxiliary receiving surfaces comprises: an inner annular base coaxial with and fixed in rotation with said main shaft, said base being movable in axial position relative to said main shaft; a plurality of outer segments forming a sector portion of said nose tab, fixed in rotation with said shaft and free in radial motion relative to said inner base, and each of said outer base segments is attached to one of said drum segments; a radially expandable pneumatic bladder interposed between said inner base and said outer segments.

12. An assembly process for building a tire comprising the steps of: providing an apparatus comprising a drum having a substantially cylindrical main receiving surface to receive the products to be assembled, said main receiving surface being radially movable, said drum comprising a right and a left shoulder located axially at the lateral edges of said main receiving surface, and said shoulders being axially extended in the form of a lateral projection; and said apparatus further comprising at least a right and a left side assembly, wherein each of said side assemblies has a nose tab and a substantially cylindrical auxiliary receiving surface; positioning radially said main receiving surface and said right and left auxiliary receiving surfaces at substantially equal radial positions; applying an inner layer complex on said main receiving surface and on said right and left auxiliary receiving surfaces and overhanging said shoulders of said drum; applying a carcass reinforcement on said inner layer complex; expanding radially said main receiving surface a radial distance at least equal to the height of said right shoulder; expanding radially at least said left side assembly a radial distance at least equal to the height difference between said right and left shoulders; placing an uncured rubber section on said carcass reinforcement at an axial location radially outward of said nose tab; folding said inner layer complex and said carcass reinforcement around said uncured rubber section such that the orientation of said uncured rubber section remains substantially stationary; placing a bead reinforcement on the fold thus made, axially to the interior of the location where the uncured rubber section is laid; placing an bead filler section on said bead reinforcement; dilating said uncured rubber section.

13. The assembly process for building a tire according to claim 12, wherein the step of placing said uncured rubber section is preceded by a step of conforming said inner layer and said carcass layer to the exterior profiles of said shoulder and of said lateral projection.

14. The assembly process for building a tire according to claim 12, wherein the step of placing said uncured rubber section further comprises placing said rubber section proximate to the axial extremity of said lateral projection.

15. The assembly process for building a tire according to claim 12, wherein the step of folding said inner layer complex and said carcass reinforcement around said uncured rubber section is further comprises the sub-steps of: radially lifting an extremity of said carcass so that it is substantially oriented radially, translating said bead reinforcement complex axially closer to the center of said drum until said bead reinforcement contacts said substantially radially oriented extremity of said carcass, and continuing the axial translation of said bead reinforcement, passing over said rubber composition section to complete the folding of said carcass layer.

16. The assembly process for building a tire according to claim 12, wherein the step of placing said bead filler section is preceded by inflating partially a turn-up bladder in said right and left side assemblies and maintaining said bladders in the partially inflated position during the placing of said bead filler.

17. The assembly process for building a tire according to claim 12, wherein the steps of placing said bead reinforcement and said bead filler section are combined in a single step.

18. The assembly process for building a tire according to claim 12, wherein the step of dilating said rubber section further comprises the sub-steps of: translating said side assemblies axially inward such that said auxiliary receiving surfaces are at least partially under said shoulders, actuating a folding device arranged under said rubber section whereby said rubber section radially expands and said fold of said carcass layer forms an adhesive contact with said bead reinforcement and said bead filler.