Abstract:
A method and apparatus ( 10 ) for shaping a tire wherein an outboard pocket assembly ( 26 ) and an inboard pocket assembly ( 24 ) are radially movable outwardly into engagement with preshaped bead/apex assemblies ( 60, 76 ) of a tire band ( 74 ) and are movable axially to a cured tire width of the bead/apex assemblies for shaping other tire components to a cured tire shape and for positioning the ply edges at predetermined cured tire positions.

Description:
TECHNICAL FIELD 
     This invention relates to a method and apparatus for building and shaping a tire with preshaped components positioned in the tire at the same spacing as in the cured tire so that the other components will substantially conform to the shape of the preshaped components in the shaped tire. Also by substantially preshaping the tire to the cured shape the edges of the plies are turned up around the bead and set in predetermined turned up positions that will not be appreciably changed in the tire press. 
     BACKGROUND ART 
     In U.S. Pat. No. 5,262,115 a method of producing a tire bead filler assembly is described wherein the bead filler is preshaped and cured about the bead before building in the tire. The advantage of this method is that the bead filler assembly keeps its shape during building of the tire and also the time required for curing the tire in a tire press may be reduced. One of the problems of using precured tire componets is that the other tire components are not shaped to the cured tire shape until the tire is finally shaped in a tire press. This results in repositioning of the tire components in the tire press which is difficult to control with precision and may affect tire quality. 
     Tire shaping drums, such as the drum shown in U.S. Pat. No. 5,405,484 have been utilized for shaping tire components, however, no provision has been made for shaping the uncured components to the cured tire shape. One of the reasons for not fully shaping the tire has been the limited force available for pushing the beads toward the cured tire positions. Also, no provision has been made for retaining the beads in the pocket assemblies of the drum if the tire were to be shaped to the cured shape. Also the bladder hinge points are not secured to prevent pulling the plies under the tire bead. 
     DISCLOSURE OF INVENTION 
     In accordance with the present invention, a new and improved shaping drum and method of building a tire with preshaped components is provided. The shaping drum has segmented pocket assemblies for gripping preshaped bead apexes and moving them to the spacing of the cured tire during shaping of the tire into a belt-tread assembly. The tread may also be precured so that when the tire is cured, the only time required for vulcanization in the tire press is the curing time required for the remaining uncured components. 
     In accordance with the present invention, there is provided a method of building a tire with a shaping drum having an expandable inboard pocket assembly, an expandable outboard pocket assembly, an inflatable inboard turnup bladder, an inflatable outboard turnup bladder, an inboard sealing flap and an outboard sealing flap connected to said outboard pocket assembly and said inboard pocket assembly comprising: 
     a. transferring a tire band to a position over the drum, 
     b. positioning an outboard tire bead over the outboard pocket assembly and an inboard tire bead over the inboard pocket assembly, 
     c. expanding the outboard pocket assembly and the inboard pocket assembly into sealing engagement with the inboard tire bead and the outboard tire bead, 
     d. transferring a tread belt assembly to a position over the tire band, 
     e. inflating the inboard turnup bladder, the outboard turnup bladder and the tire band to expand the tire band into the tread belt assembly, characterized by: 
     f. simultaneously moving the inboard pocket assembly and the outboard pocket assembly toward a center line of a drum to positions spaced apart a distance which is substantially the same as the distance between the beads of the tire in the cured condition, 
     g. applying a preshaped component of the tire to the tire band in the cured shape of the tire, 
     h. stitching the tire tread belt assembly to the expanded tire band with a roller, 
     i. deflating the inboard turnup bladder, the outboard turnup bladder and the tire band, 
     j. retracting the inboard pocket assembly and the outboard pocket assembly; and 
     k. removing the tire from the drum 
     In accordance with another aspect of the invention, there is provided a tire shaping drum comprising a shaft rotatably mounted on a support member at an inboard end of the shaft, an outboard drum section and an inboard section slidably mounted on the shaft at spaced apart positions, screw means mounted in the shaft and operatively connected to the inboard drum section and the outboard section for moving the inboard drum section and the outboard drum section together and apart upon rotation of the screw, each inboard drum section and outboard drum section having a cylindrical frame, a plurality of bead pocket segments mounted on each frame and spaced circumferentially around the shaft, radially extending spoke members attached to each of the bead pocket segments and slidably mounted in radially extending slots in the frame, piston cylinder assemblies mounted on the drum sections having pistons connected to sliding cams engagable with the spoke members to radially expand the pocket segments for retaining a shaping bladder and providing a bead seat characterized by each of the segments having a circumferentially extending channel for mounting a first edge and a second edge of the bladder, a flange on a first side of the channel and a removable nose piece on a second side of the channel for removal during mounting of the first edge and the second edge of the bladder in the channel with a minimum stretching of the first edge and the second edge of the bladder. 
     In accordance with a still further aspect of the current invention, there is provided a pocket assembly for a tire building drum of the type having a plurality of circumferentially spaced expandable segments for retaining a shaping bladder and providing a bead seat characterized by each of the segments having a circumferentially extending channel for mounting a first edge and a second edge of the bladder, a flange on a first side of the channel, and a removable nose piece on a second side of the channel for removal during mounting of the first edge and the second edge of the bladder in the channel with a minimum stretching of the first edge and the second edge of the bladder. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a cross section of the shaping drum embodying the invention showing the tire band on the drum and the bead apexes in position for seating in the pockets. 
     FIG. 2 is a view like FIG. 1 of one half of the shaping drum in the expanded condition with the tread belt applied, the sidewall turned up and the bead pocket assembly moved to a position where the distance between the beads is the same as the bead spacing in the cured tire. The position of the ply edges after shaping is also shown in detail. 
     FIG. 3 is a schematic sectional view taken along line  3 — 3  in FIG. 1 showing the expanded positions of the pocket segments with parts being broken away at the outside edge of the pocket segments. 
     FIG. 4 is a schematic view taken along line  4 — 4  in FIG. 2 showing the expanded position of the pocket segments with parts being broken away. 
     FIG. 5 is a detailed fragmentary view in perspective of a pocket segment showing the cam for expanding the pocket segment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and especially to FIG. 1 a tire shaping drum  10  is shown in the retracted condition having a drum shaft  12  with a mounting flange  14  for attachment to a rotatable drum support assembly in a supporting housing (not shown). Slidably mounted on the drum shaft  12  are an outboard drum section  16  and an inboard drum section  18 . Radially outward of the inboard drum section  18  is a cylindrical support assembly  20 , slidably mounted on the drum section  18 . Radially outward of the outboard drum section  16  and inboard drum section  18  are cylindrical support assemblies  20  and  22  mounted on the drum sections  16  and  18 . 
     The drum sections  16  and  18  are connected to a screw drive (not shown) extending through the drum shaft  12  and rotatable to adjust the spacing of the inboard drum section  18  and the outboard drum section  16  and thereby provide the desired spacing of an inboard bead pocket assembly  24  and an outboard pocket assembly  26  mounted on the drum sections  18  and  16  respectively. 
     The following description of the inboard bead pocket assembly  24  will also apply to the outboard bead pocket assembly  26  where similar parts are indicated by the same number with a prime mark. As shown in FIGS. 3 and 4, the inboard bead pocket assembly  24  has a plurality of circumferentially spaced expandable cylindrical segments  28 . In this embodiment there are eight segments  28  and each of the segments is mounted on a radially extending spoke  30  supported in a slot  32  in a cylindrical frame  34  mounted on the inboard drum section  18 . The spoke  30  may have a cam roller  36  for rolling engagement with a cam surface  38  on an axially extending sliding cam  40 . Each sliding cam  40  may be connected to a piston cylinder assembly  42  mounted on the inboard drum section  18 . A piston  44  of the piston cylinder assembly  42  is connected to the cam  40  and is movable upon communication of air pressure to a cylinder  46 . The air pressure may be factory air pressure of 100 p.s.i. (7.03 kg sq cm) and with the enlarged diameter of the piston  44  provides a substantially high pressure for extending the spoke  30  radially outward and moving the cylindrical segment  28  radially outward. 
     Each cylinder segment  28  has circumferentially extending fingers  48  in meshing engagement with fingers of an adjacent segment to provide a continuous cylindrical surface  50  around the drum for supporting a shaping bladder  52 . 
     As shown in FIGS. 1,  2 , and  5 , each of the cylindrical segments  28  has a pocket  54  in the form of a circumferentially extending channel for receiving an inboard edge  56  and an outboard edge  58  of the bladder  52 . The outboard edge  58  of the bladder  52  may be enlarged with a thickness “t” of about 0.9 inches (2.28 cm) for seating in the pocket  54 . The thickness “t” of the outboard edge  58  is less than the depth “d” of the pocket  54  so that a tire bead  60  will not be pulled out of the respective pocket when the outboard drum section  16  and inboard drum section  18  are moved together to the spacing of the cured tire as shown in FIG.  2 . The outboard edge  58  of the bladder  52  is folded over to provide a hinge point  59  under the preshaped bead apex  76 . 
     A sealing flap  62  has an outer edge  64  which is clamped between a nose piece  66  and corresponding cylinder segment  28  of each pocket  54 . The nose pieces  66  may be removed to install the outboard edge  58  of the bladder. Screws  68  may be used to fasten the nose piece  66  to the segment  28 . The sealing flap  62  also has an inner edge  70  which may be attached to a flange  72  connected to the inboard drum section  18 . 
     Referring to FIG. 2, the drum  10  is shown in more detail supporting a tire  74  with bead apexes  76 , 76  positioned at the same spacing or distance D/2 from the centerline X—X of the tire as the spacing of the beads for a cured tire. 
     Referring to FIG. 1, the drum  10  is shown in the retracted condition with a tire band  74  supported on the drum. An outboard bead apex  76  and an inboard bead apex  76 ′ are shown positioned over the bead pocket assemblies  24  and  26 . The bead apex  76  and bead apex  76 ′ are preshaped to the same shape they have in a cured tire and may be precured. A carriage (not shown) with magnets may be used to carry the bead apexes  76  and  76 ′ to the positions shown in FIG. 1 where they are held until the tire band  74  is shaped. The tire band  74  may also be assembled on a band drum (not shown) after which the band is transferred by means well known in the art to a position over the shaping drum  10  as shown in FIG.  1 . 
     The tire band  74  shown in FIG. 1 includes an inner liner  80 , a barrier  82 , a ply  84 , a sidewall  86  and other components such as chafers, fabric chafers, apex members and gum chafers. A tread belt assembly  88 , shown in FIG. 2 may also be preassembled and transferred to a position over the drum  10  prior to expansion of the drum. Inflation means is provided in communication with the space. “A” enclosed by the tire  74  and sealing flaps  62 . 
     In operation, the inboard bead pocket assembly  24  and the outboard bead pocket assembly  26  are expanded by communicating air under pressure to the cylinder  46  of each inboard pocket assembly  24  and to cylinder  46 ′ of each outboard pocket assembly  26 , causing the cams  40  or  40 ′ to engage the rollers  36  and  36 ′ on the spokes  30  and  30 ′ and move the spokes radially outward and expanding the cylindrical segments  28  and  28 ′. The outboard bead apex assembly  76  and the inboard bead apex assembly  76 ′ are then seated in the pockets  54  and  54 ′ providing a sealed space “A” within the tire band  54 , 54 ′. 
     The outboard drum section  16  and the inboard drum section  18  are then moved together while the tire band  74  is inflated and expanded to the shape shown in FIG.  2 . Also the shaping bladders  52 , 52 ′ are inflated, wrapping ply  84  and sidewalls  86  around the sides of the shaped tire band as shown in FIG. 2. A radially inner edge  90 , 90 ′ of the bladder  52 , 52 ′ is positioned under the pocket  54 , 54 ′ so that a ply edge  92 , 92 ′ of the tire band  74  is turned up and positioned at a predetermined location on the shaped tire band. The tread-belt assembly  88  is positioned over the tire band  74  during the shaping and receives the expanded crown portion of the tire band as shown in FIG.  2 . The outboard drum section  16  and inboard drum section  18  are moved together by air pressure communicated to the piston cylinder assemblies  42  for each of the cylindrical segments  28 . This movement continues until the inboard bead pocket assembly  24  and outboard bead pocket assembly  26  are spaced apart a distance D, which is in this embodiment is about 6 inches (15.18 cm). This distance is substantially the same as the distance between the beads  60 , 60 ′ of the tire band  74  in the cured condition. The shaping bladders  52 , 52 ′ are then deflated and the tread belt assembly  88  is stitched to the tire band. In this manner the preshaped bead/apex assemblies  76  and  78  are positioned in the tire band with the other components which have now been shaped to the cured tire shape. 
     The tire band  54 , 54 ′ may then be deflated and the spokes  30  may be retracted radially for removal of the assembled tire band  74 , which is now ready for curing in a tire vulcanizer (not shown). It is evident that the tire band  74  in the fully cured shape may be cured in the tire vulcanizer with substantially little additional shaping and therefore avoid the possibility of altering the positions of the tire components. This is especially true with respect to the ply edges  92  and  92 ′ where it is important that they not be pulled down during the vulcanization process.