Abstract:
A collapsible mechanism for molding the bead of a tire includes a series of sectors configured for radial and diagonal movement to selectively apply a continuous, uniform surface for molding and shaping the bead. The sectors collapse into a retracted, release position to allow for placement of the tire within and removal of the tire from the mold.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to molds for tires. More particularly, the invention relates to a mold for shaping the beads of tires.  
           [0002]    In tubeless, pneumatic tires the beads provide two functions: to anchor the tire to the wheel and to form a seal with the rim to close the air cavity. Conventional pneumatic tires rely on the exterior (relative to the tire cavity) portion of the tire bead to seat on the wheel rim for these functions. In certain types of tires, for example, vertically anchored tires such as the PAX brand tire available from Michelin North America, Inc., the interior portion of tire bead contacts the wheel rim to form the air seal.  
           [0003]    To mold the interior portion of the tire bead, it is necessary to introduce a mold element in the interior of the tire. The tire molding art contains examples of bead molding parts that allow the uncured tire to be introduced into the mold without deforming the bead, and then expand to clamp on the bead for molding. For example, U.S. Pat. No. 6,238,193 to Bosseaux, which is commonly owned with the present invention, discloses a bead molding ring that includes radially moving parts and pivoting parts that mate in an expanded, molding position, and retract to allow the tire to be loaded and removed from the mold.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned from practice of the invention.  
           [0005]    In one exemplary embodiment, the present invention provides a mold for a tire that includes a loading plate defining a cavity and having a central axis. A base is received within the cavity. The base has an engagement surface and is movable along the central axis. An actuator is also movable along the central axis between a spaced position and an engaged position relative to the base. The mold includes at least one sliding section movably attached to the engagement surface. The sliding section is movable in a direction perpendicular to the central axis between an engaged position and a retracted position, and has a molding surface for a tire bead. The mold also includes at least one floating section movably attached to the engagement surface and movable on a diagonal axis relative to the central axis between an engaged position and a retracted position. The floating section has a molding surface for a tire bead. Movement of the actuator from the spaced position to the engaged position moves the at least one sliding section and the at least one floating section to the respective engaged positions so that the respective molding surfaces join to form a continuous molding surface for the tire bead.  
           [0006]    For the exemplary embodiment being discussed, the actuator may have a frustoconical shaped driving surface for mating contact with at least one sliding section and at least one floating section. Such sections in turn have frustoconical shaped follower surfaces for being driven by the actuator. Additionally, each of the floating sections and sliding sections may be configured with joining surfaces, which mutually bear on one another when the respective sections are in the engaged position. Such exemplary features allow the application of a uniform pressure by a continuous, sealed surface against the tire bead. Accordingly, the tire bead may be molded into the desired shape and left with a smooth surface for forming an air tight seal.  
           [0007]    In addition, this exemplary embodiment may be configured such that at least one floating section is biased to the retracted position spaced along the central axis from said base and radially inward toward the central axis. Furthermore, at least one sliding section may be configured such that it is biased to the retracted position radially inward toward the central axis.  
           [0008]    In another exemplary embodiment of the present invention, a mold element for shaping a tire bead is provided and includes a platform having a support surface. A base resides over the platform and has a first surface and a second surface. The base is supported by a plurality of springs in mechanical communication with the first surface and the support surface. A plurality of floating sectors are connected to the second surface and are configured for simultaneous radial and axial movement. Each of floating sectors has a tire bead molding surface located along the outer radius and has a drive surface located along the inner radius. A plurality of radial sectors are connected to the second surface and are configured for radial movement. The radial sectors each have a tire bead molding surface positioned along the outer radius and each have a drive surface located along the inner radius. An actuator having a contacting surface is positioned over the base. Upon causing the actuator to move towards the platform, the contacting surface of the actuator contacts the drive surfaces to move the plurality of floating sectors and the plurality of radial sectors so as to cause the tire bead surfaces to form a uniform, sealed surface for application to the tire bead.  
           [0009]    In another exemplary embodiment of the present invention, a mold element for a tire is provided that includes an annular disk comprised of a plurality of movable sectors. The annular disk has an axis about which the sectors are radially located. Each movable sector has a molding surface located along its outer radius that is configured for contact with a bead of the tire. At least one of the plurality of movable sectors is configured for radial movement between a release position and an engaged position. At least one of the plurality of movable sectors is configured for simultaneous radial and axial movement between a release position and an engaged position. An actuator is positioned above the annular disk and is configured for selectively acting upon the annular disk so as to move the plurality of movable sectors between the release position and the engaged position. Upon being placed into the engaged position, the mold surfaces of the plurality of movable sectors collectively form a continuous surface for molding the tire bead.  
           [0010]    Another exemplary embodiment of the present invention provides a tire mold that includes a circular member having a series of alternately positioned radial sectors and diagonal sectors. The radial sectors are configured for movement in a radial direction between a release position, in which the tire may be placed upon or removed from the mold, and a secure position, in which a bead of the tire is in contact with the series of alternating radial sectors and diagonal sectors. The diagonal sectors are configured for movement simultaneously in both an axial direction and a radial direction between the release position and the secure position. An actuating member is positioned axially above the circular member and is configured for contacting the radial and diagonal sectors so as to selectively, reciprocally position the radial and diagonal sectors between the release position and the secure position. Upon being placed into the secure position, the series of radial and diagonal sectors collectively create a uniform surface for contacting and molding the bead of the tire.  
           [0011]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the principles of the invention. As will be understood by one of ordinary skill in the art using the teachings disclosed herein, the present invention as set forth in the claims herein exists in a variety of different embodiments that may be used to secure the position of a tire as needed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an exploded assembly view of an exemplary embodiment of a run-flat tire assembly.  
         [0013]    [0013]FIG. 2 is a perspective view of the tire assembly shown in FIG. 1.  
         [0014]    [0014]FIG. 3 a partial cross-sectional view of another exemplary embodiment of a run-flat tire assembly.  
         [0015]    [0015]FIG. 4 is a partially exploded perspective view of an exemplary embodiment of the present invention.  
         [0016]    [0016]FIG. 5 is a cross-sectional view of an exemplary embodiment of the present invention in the collapsed or open position.  
         [0017]    [0017]FIG. 6 is a cross-sectional view of an exemplary embodiment of the present invention in the expanded or closed position.  
         [0018]    [0018]FIG. 7 is a cross-sectional view of an exemplary embodiment of the present invention in the collapsed or open position, and such embodiment is shown as it might be used with a curing press.  
         [0019]    [0019]FIG. 8 is a cross-sectional view of an exemplary embodiment of the present invention in the expanded or closed position, and such embodiment is shown as it might be used with a curing press.  
     
    
     DETAILED DESCRIPTION  
       [0020]    Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.  
         [0021]    Applicant&#39;s assignee is the owner of U.S. Pat. No. 5,891,279, entitled “Safety Support Made of a Flexible Elastomeric Material for Tires”, which is incorporated herein by reference in its entirety for all purposes. Such patent illustrates exemplary embodiments of a run-flat tire having an insert in the shape of a ring disposed on a rim. The tire surrounds the insert and is vertically anchored onto the rim as is described in U.S. Pat. No. 5,634,993, entitled “Rim And Assembly Of Tire And Ring-Shaped Tread Support On Same” which is also owned by the assignee of the present invention and is incorporated by reference herein in its entirety for all purposes. Exemplary embodiments of the present invention will be described with reference to such run-flat tires. However, particular tire types are not a limiting feature of the disclosure and teachings herein as such may be used with a variety of tire designs as will be understood by one of ordinary skill in the art using such disclosure and teachings.  
         [0022]    Referring now to the drawings, an example of a run-flat tire assembly  10  is shown in FIG. 1. The tire assembly  10  is shown as being made of three basic components. First, an alloy or steel integral wheel rim  12  is provided onto which a support member  14  is placed. The support member  14  shown in FIG. 1 is a ring. Next, a rubber tire  16  is placed onto the rim  12  and completely surrounds the support member  14 . The tire assembly  10  is shown in an assembled state in FIG. 2. The tire  16  is vertically anchored to the rim  12  as described in U.S. Pat. No. 5,634,993.  
         [0023]    [0023]FIG. 3 shows a partial cross sectional view of a tire assembly  10  in accordance with one exemplary embodiment of a run-flat tire assembly. As shown, the support member  14  is similar to that disclosed in the &#39;279 patent mentioned above, and is located on a cylindrical section  18  of the rim  12 .  
         [0024]    As shown for the exemplary run-flat tire assembly of FIG. 3, tire  16  is provided with tire tread  26  on its outer surface. Two side walls  28  extend from the tire tread  26  portion of tire  16 . For this exemplary embodiment for a run-flat tire assembly, the side walls  28  are substantially vertical in orientation once seated onto the rim  12 . A first bead  30  is present at the end of one of the side walls  28 , and a second bead  32  is present at the end of the other side wall  28 . The beads  30 ,  32  keep the tire  16  attached to the rim  12  and also create an air seal to maintain air pressure in the space  34  formed between the tire  16  and rim  12 .  
         [0025]    Rim  12  has a first bead seat  36  and a second bead seat  38  formed therein for seating the first and second beads  30  and  32  respectively. The first bead seat  36  is formed by a pair of humps  40  and  42 . The second bead seat  38  is formed by a pair of humps  44  and  46 . An air seal is formed between the first bead  30  and the first bead seat  36 . Similarly, an air seal is also formed between the second bead  32  and the second bead seat  38 . These air seals prevent air from escaping around the beads  30  and  32  respectively.  
         [0026]    During manufacturing, a mold element  110  must be introduced into the interior of the tire to mold the shape of tire bead  30  or  32 . FIGS. 4 through 8 illustrate an exemplary embodiment of a mold element  110  for molding bead  32  of a tire  16 . Mold element  110  is depicted in the open or collapsed position in FIG. 5 and FIG. 7. In such position, tire  16  may be removed from mold element  110 . Conversely, mold element  110  is depicted in the closed or expanded position in FIG. 6 and FIG. 8. In this position, mold element  110  is contact with tire  17  and operates to form bead  32  into the desired shape.  
         [0027]    [0027]FIG. 7 and FIG. 8 depict mold element  110  being used in conjunction with a curing press  166 . Curing is a step in the manufacturing process during which tread detail, lettering, and other features may be added while the tire  16  is subjected to heat and pressure. The shape of bead  30  or bead  32  is also formed during this step. Press  166  includes two halves  168  and  170  that are used to press or sandwich tire  16  during the curing step. As depicted, the press  166  is open in FIG. 7 and in FIG. 8. The internal walls of halves  168  and  170  include, for example, tread detail  172  for impression upon tire  16 .  
         [0028]    Referring generally now to FIGS. 4 through 8, mold element  110  includes a loading plate  112  that may be attached to the bottom of a curing press  166  or other tire manufacturing apparatus as desired. The internal surface  114  of loading plate  112  defines a cavity  116 . Loading plate  112  also has a central axis AA, designated with dashed lines in FIGS. 5 and 6. Bolts or pins may be inserted through apertures  118  and  120  for orienting and attaching loading plate  112  to the curing press  166  or other equipment.  
         [0029]    Base  122  is received within cavity  116  of loading plate  112  and has a first surface  126  and a second surface  124 . Base  122  is movable in both directions along central axis AA. As shown, a plurality of springs  128  provide mechanical communication between first surface  126  of base  122  and loading plate  112 . More specifically, loading plate  112  supports base  122  through the plurality of springs  128 . Pins  130  operate to orient and guide the plurality of springs  128 . As will be described below, the plurality of springs  128  are compressed when base  122  is moved towards loading plate  112  along axis AA and are therefore released as base  122  is moved away from loading plate  112 .  
         [0030]    Attached to the second surface  124  of base  122  in alternating positions are radial sectors  132  and floating sectors  134 . For the exemplary embodiment of FIGS. 4 through 8, there are three such radial sectors  132  and three such floating sectors  134 . As used here, “sector” describes the geometrical shape of two radii and the arc of at least one circle. The center of such circle defines an axial direction congruent or parallel with axis AA, and a radial direction that is perpendicular to the axial direction. For the exemplary embodiment illustrated, radial sectors  132  and floating sectors  134  are depicted as sections that together form a circular or annular disk having an aperture  136  (FIG. 4) positioned at its center. It should be understood, however, that the present invention may contain any number of sectors  132  and  134 , and is not limited to only the use of six radial sectors  132  and floating sectors  134  nor to the use of sectors having the same shape as illustrated in FIGS.  1 - 6 . Furthermore, sections having shapes other than as depicted for radial sectors  132  and floating sectors  134  may be used to form the overall circular or annular shape.  
         [0031]    Referring again to the exemplary embodiment illustrated, each radial sector  132  is configured for reciprocal movement in a radial direction. More specifically, each radial sector  132  is configured for movement within a plane and direction that is perpendicular to central axis AA (shown in FIGS.  5 - 6 ). Pin  138  connects radial sector  132  to base  122  through link  140 . Base  122  defines a chamber  142  housing a compressive spring  144  that is in mechanical communication with compressive link  140  through pin  146 . As radial sector  132  moves in a radial direction away from axis AA, pin  146  and a portion of link  140  are constrained to move within chamber  142  and compressive spring  144  is compressed. As radial sector  132  moves in a radial direction towards axis AA, spring  144  is released.  
         [0032]    Each floating sector  134  is configured for reciprocal simultaneous radial and axial movement. More specifically, each floating sector  134  moves in a direction that is diagonal to axis AA. This direction is indicated by axis BB (FIGS.  5 - 6 ). Guide pin  152  connects floating sector  134  to base  122 . When mold element  110  is in the expanded position shown in FIG. 6, guide pin  152  is contained within recesses  154  and  156  located in floating sector  134  and base  122  respectively. Guide pin  152  also operates in conjunction with compressive spring  158 . Accordingly, as floating sector  134  is moved along axis BB, compressive spring  158  is compressed when floating sector  134  is moved towards base  122  and released when floating sector  134  moves away from base  122 . In the preferred embodiment, axis BB forms an angle of 30 degrees as measured in a counter-clockwise direction from central axis AA. It should be understood, however, that the present invention is not limited to an angle of 30 degrees for axis BB, and other angles may be used as will be understood by one of ordinary skill in the art using the teachings disclosed herein.  
         [0033]    Radial sectors  132  each have a drive surface  147  located along an inner radius, while floating sectors  134  each have a drive surface  149  located along an inner radius. These drive surfaces  147  and  149  are beveled and oriented for mating contact with a contacting surface  160  (FIG. 5) on actuator  162 . More specifically, actuator  162  has a frustoconical-shaped contacting surface  160  for contacting and driving frustoconical-shaped surfaces  147  and  149 . Preferably, contacting surface  160  is at an angle of 30 degrees as measured in a direction clockwise from central axis AA. However, it should be appreciated that other angles may be used for contacting surface  160  as will be understood by one of skill in the art using the teachings disclosed herein.  
         [0034]    A top plate  164  is attached to actuator  162 . Accordingly, as top plate  164  and actuator  162  are moved along axis AA towards base  122 , contacting surface  160  contacts drive surfaces  147  and  149 . Consequently, radial sectors  132  are driven in a radial direction outward from axis AA while floating sectors  134  are driven towards base  122  in a direction along axis BB. For the exemplary embodiment of molding element  110  depicted, floating sectors  134  and radial sectors  132  also engage and bear upon each other along angled surfaces  135  and  137 . Surfaces  135  and  137  are preferably angled at 45 degrees; however, other angles may be used as will be understood by one of skill in the art using the teachings disclosed herein. In addition, the base  122  moves downward into the cavity  116  in the loading plate  112 , which allows the continuous surface formed by the engaged sectors to come into contact with the tire bead with an axial movement.  
         [0035]    Actuator  162  and top plate  164  may be powered by operation of a hydraulic piston or shaft  174  extending through aperture  136 . However, one of ordinary skill in the art will understand that other means of powering actuator  162  and top plate  164  may be envisioned using the teachings disclosed herein.  
         [0036]    Radial sectors  132  each have a tire bead molding surface  148  located along an outer radius. Similarly, floating sectors  134  each have a tire bead molding surface  150  located along an outer radius. When the exemplary embodiment being discussed is in the expanded position as shown in FIGS. 6 and 8 for example, the tire bead molding surface  148  of each radial sector  132  and the tire bead molding surface  150  of each floating sector  134  collectively form a continuous surface that presses against second bead  32 . More specifically, the series of mating surfaces provided by surfaces  148 ,  150 ,  135 , and  137  allow for the application of a uniform, continuous surface to second bead  32 . Accordingly, mold element  110  is used to assist in shaping second bead  32  as desired while also molding a smooth surface along second bead  32  for creating a tight air seal. Mold element  110  also performs the secondary function of helping to secure the position of tire  16  during the curing step.  
         [0037]    The present invention may be configured for use with first bead 30 and is not limited to using second bead  32  as will be understood by one of skill in the art using the teachings disclosed herein. More specifically, the orientation of tire  16  as shown in FIG. 5 and FIG. 6 is by way of example only.  
         [0038]    An example of the operation of the exemplary embodiment  110  of the present invention will now be described. A tire  16  is placed into, for example, a curing press  166  and second bead  32  is placed over mold element  110 . Top plate  164  and actuator  162  are then moved along axis AA towards loading plate  112  by operation of shaft  174 . Contacting surface  160  then urges radial sectors  132  and floating sectors  134  from a collapsed or open position shown in FIGS. 5 and 7 to a closed or expanded position as shown in FIGS. 6 and 8.  
         [0039]    More specifically, contacting surface  160  contacts and drives surfaces  147  so as to cause radial sectors  132  to move radially outward and floating sectors  134  to move along diagonal axis BB. Compressive springs  144  and  158  are compressed. The plurality of springs  128  are also compressed as base  122  is urged towards loading plate  112 . As a result, tire seating surfaces  148  and  150  contact and apply pressure to second bead  32  and thereby provide a uniform pressure and a continuous, sealed molding surface against second bead  32 . Radial sectors  132  and floating sectors  134  are now in a secure or clamped position as tire  16  is now fixed in place by mold element  110 . Accordingly, mold element  110  can be used to mold second bead  32  into the shape desired and to provide a smooth surface for sealing air within the tire during operation.  
         [0040]    Upon releasing or removing tire  16  from mold element  110 , top plate  164  and actuator  162  are moved along axis AA away from loading plate  112 . In turn, compressive springs  144  cause radial sectors  132  to move radially inward towards axis AA. Compressive springs  158  cause floating sectors  134  to move diagonally upwards along axis BB. Base  122  is also driven away from loading plate  112  by operation of the plurality of springs  128 . As a result, tire seating surfaces  148  and  150  release pressure from second bead  32  allowing tire  16  to be removed. Radial sectors  132  and floating sectors  134  are now in a release position as tire  16  can now be removed from mold element  110 .  
         [0041]    It should be understood that the present invention includes various modifications that can be made to the embodiments as described herein as come within the scope of the appended claims and their equivalents. The aforementioned description of embodiments of the present invention is by way of example only and not intended as a limitation on the spirit and scope of the claims that follow.