Abstract:
In accordance with one aspect of the present invention there is provided improved means for centering of a green vehicle tire carcass on a shaping drum. “Centering” as used herein and unless otherwise stated or obvious from the context of its use, includes positioning of the bead ring-containing. opposite ends of a carcass substantially equidistantly from the centerplane of the drum and substantially radially equidistant from, and substantially concentric about, the rotational axis of the drum. In one embodiment, the shaping drum includes first and second pluralities of lateral positioning shoes disposed about the outer circumference of thedrum, these pluralities of shoes being disposed on opposite sides of the lateral centerplane of the drum, and first and second pluralities of bidirectional (radial and lateral) positioning wheels, the pluralities of wheels also being disposed about the outer circumference of the drum, on opposite sides of the lateral centerplane of the drum, and between respective ones of the pluralities of shoes and the lateral centerplane of the drum. These shoes and wheels are selectively positionable laterally and radially of the drum to effect centering of the carcass. A method is disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates generally to methods and apparatus for use in the manufacture of vehicle tires. In particular, this invention relates to methods and apparatus for the positioning of a green tire carcass on a shaping drum. More particularly, this invention pertains to 
     2. Description of the Related Art 
     In the manufacture of vehicle tires, one process operation includes positioning of a green tire carcass on a shaping drum whereupon the carcass is inflated to a generally desired toroidal shape. The green tire carcass normally is of a generally hollow cylindrical geometry having a non-extensible bead ring secured internally of each of the opposite ends of the carcass. The shaping drum of the prior art includes first and second generally cylindrical mandrels which are disposed on opposite sides of a centerplane oriented perpendicular to the longitudinal centerline of the drum. This longitudinal centerline also defines the rotational axis of the drum. The mandrels of a shaping drum are designed to engage the bead ring-containing opposite ends of the carcass and thereby hold the carcass centered on the drum relative to the centerplane and concentric with respect to the rotational axis of the drum. 
     In the present embodiment, each of the mandrels is of the radially expansible type, that is, each mandrel comprises a plurality of segments which are disposed radially about the rotational axis of the drum and which collectively define generally the outer circumference of an annular receiver for one of the bead rings of the carcass. The segments of each mandrel are radially moveable relative to the rotational axis of the drum for locking the bead rings of the carcass to the drum and are laterally movable to permit initial selection of the spacing between the bead rings as the carcass. and adjustment of their lateral spacing as the carcass is radially expanded to define a green tire. 
     For proper functioning of the shaping drum and true rotational dimensioning of the carcass into a vehicle tire, it is important that the carcass initially be positioned precisely centrally of the shaping drum both radially of the drum and laterally of the centerplane of the drum so that upon inflation of the carcass toward a toroidal geometry, all parts of the carcass move or expand uniformly with respect to one another, thereby ensuring uniformity of symmetry of the expanded carcass, as well as uniformity of distribution of the material of construction of the carcass, and ultimately, uniformity of the radial and lateral dimensions and material distribution of the finished tire. 
     A typical green tire carcass for an automobile will weigh 35-50 pounds or more and is relatively flimsy. Obviously, a green carcass for a truck tire, or an off-the-road (OTR) tire, will be considerably heavier and more difficult to manipulate. Accordingly, loading of the carcass onto a shaping drum is difficult in several aspects. For example, manually placing the carcass onto the drum from one end of the drum, that is “threading” of the carcass initially onto one end of the drum and further moving the carcass toward the lateral centerplane of the drum is difficult in that the carcass tends to bend, twist, collapse and/or sag due to gravity, from its open cylindrical geometry when lifted by an operator or a mechanical transfer device. After the carcass has been initially threaded onto the drum, there remains the problem of completing the centering the carcass relative to the lateral centerplane of the drum so that the bead rings are disposed on opposite sides of, and equidistantly from the centerplane of the drum and equidistant radially about the rotational axis of the drum. These and other positioning efforts are frustrated by the tendency of the carcass to “sag” under the effects of gravity thereby impeding the radial centering of the carcass relative to the longitudinal centerline of the drum before, or as, the bead rings become locked to the mandrels of the drum. Failure to center the carcass both radially and longitudinally of the shaping drum can result in non-uniform distribution of the material of the carcass, hence of the finished tire, with the result that the finished tire is unacceptably “out of round” and must be scrapped. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is provided improved means for centering of a green tire carcass on a shaping drum. “Centering” as used herein and unless otherwise stated or obvious from the context of its use, includes positioning of the bead ring-containing opposite ends of a carcass substantially equidistantly from the centerplane of the drum and substantially radially equidistant from, and substantially concentric about, the rotational axis of the drum. In one embodiment, the shaping drum includes first and second pluralities of lateral positioning shoes disposed about the outer circumference of the drum, these pluralities of shoes being disposed on opposite sides of the lateral centerplane of the drum, and first and second pluralities of bidirectional (radial and lateral) positioning wheels, the pluralities of wheels also being disposed about the outer circumference of the drum, on opposite sides of the lateral centerplane of the drum, and between respective ones of the pluralities of shoes and the lateral centerplane of the drum. These shoes and wheels are selectively positionable laterally and radially of the drum. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a representation of a shaping drum embodying various of the features of the present invention; 
     FIG. 2 is an end view of the drum depicted in FIG. 1; 
     FIG. 3 is a side elevation view, in section, of the drum depicted in FIG. 1; 
     FIG. 4 is a representation of a drum in accordance with the present invention and depicting the opposite sections of the drum in their spaced apart relationship and with the carcass positioning shoes and wheels disposed in their radially retracted positions; 
     FIG. 5 is a representation of the drum depicted in FIG. 4 with the positioning shoes and wheels disposed in their radially extended positions; 
     FIG. 6 is a representation of a portion of the right-hand section of the drum depicted in FIG.  4  and depicting spatial and functional relationships of the carcass positioning shoes and wheels employed in one embodiment of the present invention; 
     FIG. 7 is a further representation of a further portion of the right-hand section of the drum depicted in FIG.  4  and depicting further details of drum; 
     FIG. 8 is a side elevation view of a drum embodying various of the features of the present invention and depicting a green tire carcass encircling the drum; 
     FIG. 9 is a detail view of a portion of the drum depicted in FIG.  8  and taken generally along the line  8 — 8  of FIG. 7; 
     FIG. 10 is a side elevation view of the inboard section of a drum of the type depicted in FIG.  4  and showing the multidirectional wheels in their retracted positions; 
     FIG. 11 is an end view of the drum section depicted in FIG. 10; 
     FIG. 12 is a side elevation view of the inboard section of a drum of the type depicted in FIG.  4  and showing the multidirectional wheels in their extended positions; 
     FIG. 13 is an end view of the drum section depicted in FIG. 12; 
     FIG. 14 is a representation of a mounting arm for a positioning wheel of the present invention; 
     FIG. 15 is a representation of a mounting lug for the base end of the cylinder of a piston/cylinder actuating device for effecting radial movement of the shoes/wheels of the present invention; 
     FIG. 16 is a representation of a lever arm for interconnecting the outboard end of a piston rod of a piston/cylinder actuation device with a driven gear ring employed in one embodiment of the present invention. 
     FIG. 17 is a representation of an alternative embodiment of a positioning shoe as employed in the present invention; and 
     FIG. 18 is a further representation of the positioning shoe depicted in FIG.  17 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIGS. 1-3, in the depicted embodiment of the drum  10  of the present invention, there is provided a central (rotational) shaft  12  having a radial shoulder  14  suitable for attachment of the depicted drum to a conventional drive system for a shaping drum. The depicted drum includes a rotational axis  16  and a centerplane  18  (see FIG.  4 ). The drum is divided into substantially a first (inboard) section  20  and a second (outboard) section  22 , each section being mounted on the shaft  12  for simultaneous rotation of the sections upon rotation of the shaft  12 . Further, each section is translatable laterally of the centerplane of the drum, the two sections moving substantially simultaneously toward the centerline or substantially simultaneously away from the centerline. Common or equivalent components of the two sections of the drum are designated using primed numerals. 
     Referring specifically to FIG. 3, in the depicted drum, internally of the shaft  12  there is provided a lead screw  23  having one of its opposite ends  24  rotatably mounted in the inboard end of the shaft  12  and its opposite (outboard) end  25  rotatably mounted internally of the outboard section  22  of the drum. The inboard end  24  of the lead screw projects laterally outwardly of the drum to define a lug  26  by means of which the lead screw may be rotated relative to the shaft  12 . 
     Adjacent the inboard end of the lead screw, there is provided a lead nut  30  which threadably encircles the lead screw and whose outer circumference is secured to the inboard end  32  of a first hollow cylindrical tube  34  so that upon rotation of the lead screw, the lead nut and its attached tube  34  move inwardly or outwardly relative to the shaft  12 , depending upon the direction of rotation of the lead screw. Adjacent the outboard end  36  of the tube  34 , there is provided a second lead nut  38  which threadably encircles the outboard end  25  of the lead screw and which has its outer circumference attached to mounting lugs  40 ,  41  which, in turn, are attached to the inboard section  20  of the drum at diametrically opposite locations about the shaft  12 . Further, the outboard end  36  of the tube  34  is attached by a mounting ring  42  to the outboard section  22  of the drum. Thus, it will be seen that rotation of the lead screw effects lateral movement of the two halves  20 , 22  of the drum relative to each other. By design, rotation of the lead screw effects about twice as much lateral movement of the inboard drum section  20  as the lateral movement of the outboard section  22  of the drum. To accommodate this relative movement between the drum halves, the tube  34  is provided with a slot  44  which extends substantially from end to end of the tube  34  and the shaft  12  within which the tube is slidably mounted, is provided with a slot  46  which extends from proximate the outboard end of the shaft  12  to a point about midway along the length of the shaft  12 . These slots are in register and the mounting lugs  40 , 41  reside in and slide along these registered slots. This construction provides for lateral movement of the drum halves relative to one another, without rotational movement of either section relative to the shaft  12  or the tube  34 . By this means, all of the components of each of the two sections  20 , 22  are translatable laterally relative to the centerplane  18  of the drum. 
     As depicted in the several Figures, in the depicted embodiment, each of the inboard and outboard drum sections  20 , 22 , includes a carcass alignment subassembly  50 , 52 , these assemblies being substantially mirror images of one another. 
     Referring specifically to the inboard section  20  of the drum depicted in FIGS. 4,  5  and  9 , the carcass alignment subassembly  50  includes a first plurality of positioning wheels  52  disposed about the outer circumference of the inboard section of the drum, and adjacent to the transverse centerplane  18  of the drum. Each positioning wheel  52  is provided with a plurality of barrel-type rollers  54  disposed at spaced apart locations about the outer circumference of the wheel. In one embodiment (see FIGS.  6  and  9 ), each of these rollers  54  is mounted within a depression  56  in the outer circumference  58  of its respective wheel for rotation about a rotational axis  60  that is aligned substantially parallel to a chord of the outer circumference of the wheel. As depicted, (see also FIGS. 5 and 14) each wheel is mounted between the legs  62  and  64  of a rocker arm  66  whose opposite end  68  is pivotally mounted, by a pin  69 , to a cylindrical hub  71  which is mounted nonrotatably, but laterally slidably relative to the shaft  12 . The axis of rotation  57  of the wheel  52  is disposed perpendicular to the axes of rotation of its respective rollers  54 . 
     Referring also to FIG. 9, the carcass alignment subassembly  50  further includes a first plurality of lateral alignment shoes  72  also disposed about the outer circumference of the drum and immediately inboard of the first plurality of positioning wheels  52 . Each lateral positioning shoe  60  comprises a generally arcuate, i.e., curved, body portion  74  including an outer surface  75  which defines a portion of an outer circumference of the drum. That edge  76  of the shoe disposed nearest the centerplane of the drum is provided with a bifurcated projection  78  which extends radially inwardly of the drum, terminating as legs  83 , 84 , and receives therein a shaft  80  which is oriented substantially parallel to the rotational axis of the drum, and about which the shoe is pivotable. The opposite end  82  of the shoe projects in cantilevered fashion laterally outwardly of the drum from the bifurcated projection, and terminates in the form of a radially inwardly curved distal surface  84 . As depicted in FIG. 9, each shoe is provided with a channel  85  which extends between opposite sides of the shoe and which opens outwardly of the surface  75  of the shoe. As depicted in FIGS. 7 and 13, for example, the shoes of each section of the drum are encircled by an elastic band  87  which resides in the channels of the several shoes of each section of the drum. By this means, the rotational movement of the shoes is restricted to a few degrees of rotation, thereby maintaining the orientation of the outer surface of each shoe generally concentric with respect to the outer circumference of the drum, but allowing a relatively small degree of freedom of rotation to provide for alignment of each shoe such that its distal edge properly engages the inner circumference of the carcass adjacent a respective bead ring. This elastic band is not shown in most of the drawings for purposes of clarity. 
     In one embodiment of the present invention (see FIG.  9 ), the positioning wheels  52  of the first plurality of positioning wheels and the lateral positioning shoes of the first plurality of positioning shoes are disposed in pairs, a pair comprising one wheel  52  and one shoe  72 . In this embodiment, the wheel and shoe of each pair are rotatably/pivotally mounted on a common axis, which may comprise the common shaft  80  that is mounted between the bifurcated outboard legs  86 , 88  of a rocker arm  90  and which also extends to be received between the arms  82 , 84  of the bifurcated projection  76  of the shoe  72 . The axis of this shaft  80  which mounts the wheel and shoe of each pair is disposed substantially parallel to the rotational axis  16  of the drum. In this embodiment, this common mounting of the positioning wheels and shoes is repeated in mirror image fashion on the opposite side of the centerplane of the drum with a second plurality of positioning wheels  52 ′ and a second plurality of positioning shoes  60 ′ associated with the outboard section of the drum. 
     As may been seen in FIGS. 4,  7  and  9 , in the depicted embodiment of the present invention, the physical mounting of each shoe relative to its associated wheel, when employing a combination of wheels and shoes, provides for the arcuate radially outer surface  75  of each shoe to be disposed more radially inwardly of the drum relative to the outer circumference  58  of each wheel. This mounting relationship of the shoes and wheels provides for the inner circumference  108  or a carcass  110  which is initially threaded onto the drum to engage, and be supported by, the rollers in the outer circumference of each wheel with the inner circumference of the carcass spaced apart from the outer surface  75  of each shoe. This spacing of the carcass away from the outer surface of the shoes permits the carcass to be moved readily laterally of the drum and/or rotated about the rotational axis of the drum without impedance from the outer surfaces of the several shoes. 
     Referring to FIGS. 5,  6 ,  7  and  9 , on a given side of the centerplane  18  of the drum, that end of each rocker arm  90  opposite its bifurcated end is provided with gear teeth  100  which mesh with like gear teeth  102  provided in the radially outward circumferential surface  104  of a driven gear ring  106  which is free-floating rotatably mounted on the outer circumference of the cylindrical hub  71  and adjacent the annular mounting ring  70 . By this means, each of the rocker arms for each of the pairs of shoes and wheels is mechanically interconnected to every other of the rocker arms on a given side the centerplane of the drum so that upon rotation of the driven gear ring  106 , all of the rocker arms pivot simultaneously in the same direction and by the same amount. 
     Referring to FIGS. 9-13, as so operably disposed, each of the positioning shoes  72  and each wheel  52  may be pivoted between a first (extended) position in which the outer surface of each shoe and the outer circumference of each wheel of each pair of shoes and wheels projects radially beyond the general outer overall circumference of the drum, and a second (retracted) position in which each pair of shoes and wheels is disposed radially inwardly of the general outer overall circumference of the drum. As noted, in their first positions (during carcass loading), the outer surface of the shoe is more radially inward of the drum than are the rollers of its respective wheel by a distance, e.g. about 2 inch, sufficient to create a space  77  between the outer surface  75  of each shoe and the internal cylindrical circumference  108  of a carcass  110  disposed on the drum  10 , while at the same time positioning the radially inwardly extending edge  82  of each shoe to engage the carcass at a location adjacent a bead ring  112  disposed within an end  114  of the carcass. 
     Rotation of the driven gear ring is provided for by means of at least one, and in one embodiment, a plurality of piston/cylinder devices  116  operably interconnected between the fixed annular mounting ring  70  to which the rocker arms  90  are pivotally mounted, and one or more of the lever arms  118  (see FIGS.  6 - 9 ). In the depicted embodiment, each of the lever arms  118  includes a bifurcated end  120  between the legs of which the end  122  of a piston/cylinder rod  121  is pivotally pinned  123 , and a distal end  124  which is provided with a plurality of gear teeth  126  which mesh with like gear teeth  1102  on the driven gear ring  106 . Each lever arm is pivotally mounted, intermediate its opposite ends to the inner surface  67  of the annular mounting ring  70  as by a pin  128 . The base end  130  of the cylinder of each piston/cylinder device is pivotally anchored to the outer circumference of the annular mounting ring  70  as by a mounting bracket  132  which is pinned  133  at one end  134  thereof to the inner surface  108  of the annular mounting ring  70  and whose opposite end includes a yoke  136  to which the base end of the cylinder is pinned. 
     Upon rotation of the driven gear ring  106  relative to the mounting ring  70  by means of actuation of the piston/cylinder devices(s)  116 , each of the pairs of shoes and wheels on a given side of the centerline of the drum are caused to pivot either radially outwardly or radially inwardly relative to the rotational axis of the drum and thereby present the shoes and wheels for engagement therewith by the inner circumferential surface  108  of a carcass  110  being loaded onto the shaping drum, or to withdraw the shoes and wheels from engagement with the inner surface of such carcass. 
     Rotation of the driven gear ring  106 ′ on the opposite side of the centerline of the drum is effected substantially identically as described. In one embodiment, the piston/cylinder devices  116 ,  116 ′ disposed on the opposite sides of the centerplane are connected to a common source of hydraulic or pneumatic fluid and are controlled to function simultaneously and in like manner so that the wheels and shoes on both sides of the centerline of the drum move simultaneously and in like radial direction and extent of movement as do the wheels and shoes disposed on the opposite side of the centerline of the drum. 
     In accordance with one embodiment of the method of the present invention, in preparation of the shaping drum for the threading of a carcass thereon, the piston/cylinder devices are actuated to rotate the driven gear rings, causing each pair of the shoes and wheels to simultaneously pivot about their respective pivot axes in a direction toward their retracted positions radially inwardly of the drum. This position of the shoes and wheels is depicted in FIGS. 10 and 11 and provides for the passage of the bead ring-containing ends  114 , 114 ′ past the wheels and shoes on respective outboard and inboard sections of the drum. Thereupon, the green tire carcass (see FIG. 8) is initially threaded onto the outboard end of the drum and into a position where each of its opposite ends is disposed generally in encircling relationship to a respective plurality of pairs of wheels and shoes. 
     Once the carcass has been manually threaded onto the drum to the extent that the bead rings  112 ,  112 ′ at the opposite ends  114 ,  114 ′ of the carcass (see FIGS.  7  and  8 ), are disposed laterally beyond the distal ends  84 ,  84 ′ of the shoes of each of the first and second sections of the drum, radial movement of the wheels and shoes outwardly of the drum is commenced. As the outer surface of the rollers in the outer circumference of each wheel engage the inner circumference of the carcass, a radially directed pressure is exerted against the inner circumference of the carcass causing the carcass to be formed into a substantially uniform cylinder intermediate the bead rings in the opposite ends of the carcass. 
     Substantially simultaneously with the action of “rounding up” of the carcass and the slight laterally inward movements of the bead rings, the distal curved ends of the shoes on opposite sides of the centerplane engage the inner circumference of the carcass at locations laterally inwardly of their respective bead rings in the opposite ends of the carcass. The radially outward movement of these curved ends of the shoes against the inner circumference of the carcass develops a resultant vectorial force acting against each end of the carcass adjacent each bead ring, but in opposite directions laterally from the centerplane of the drum. Because the uniformly cylindrical carcass is supported on the rollers of the wheels, and each wheel is freely rotatable about an axis parallel to the shaft of the drum, the carcass is in position to be readily moved laterally of the drum in either direction so that the vectorial forces exerted against the inner circumference of the carcass move the carcass to a position wherein the bead rings are disposed substantially equidistantly from the centerplane of the drum. This action occurs very rapidly (on the order of 2-3 seconds) and once completed, the bead rings of the carcass are in position to be locked into engagement with the drum and the carcass expanded to define a tire, and/or for other operational processes to be performed thereon. When the formed tire is ready to be removed from the shaping drum, the driven gear rings are rotated to cause the wheels and shoes to retract to their retracted position radially inwardly of the drum so that the formed tire may be readily removed from the shaping drum. 
     The construction and actuation of the bead ring clamps indicated generally by the numerals  150  and  150 ′ (FIGS. 3,  8  and  9 ), may be of a design known in the art. The present bead ring clamping mechanism associated with each section of the drum includes a plurality of arms  160 , each of which is individually pivotably mounted at one end  162  thereof, and each of which carries a bead ring clamp  164  on its opposite end  166 . Actuation of the arms is by means of pressurized fluid introduced into a cylindrical chamber  168  to cause a cylinder  170  to move laterally of the drum and urge rollers  172  associated with the arms  160  toward engagement with a ramping surface  174  on each arm  160  and thereby urge the ends  166  of the arms  160 , and their respective bead clamps radially of the drum to engage the bead rings. This mechanism is duplicated for the other section of the drum, and preferably, their respective actuations are coordinated to produce substantially simultaneous movement of the bead clamps. In FIGS. 5 and 6 there is depicted an elastomeric cylindrical covering  175  for the proximal ends of the bead locks. This covering is useful for protecting the proximal ends of the bead locks against contaminants, etc. and is omitted from others of the drawings for purposes of clarity. 
     As is true with known shaping drums, once the bead rings of the carcass have been locked to the drum, the carcass is inflated to expand the carcass into the desired toroidal shape. This action requires that the locked bead rings move simultaneously and equally inward of the drum toward the centerline of the drum. This action is accomplished through the means of the lead screw  23 , its lead nuts  30  and their interconnection with the sections  20 , 22  of the drum. This structure, and its operation, are well known in the art. 
     In one embodiment, the gear teeth provided on the outer circumference of the driven gear ring are present only adjacent each of the inboard ends of the rocker arms, as opposed to gear teeth about the entire circumference of the driven ring. Other modifications and/or equivalents of the disclosed embodiments of the present invention will be recognized by one skilled in the art and it is intended that the invention be limited only as set forth in the claims appended hereto.