Patent Publication Number: US-2007122582-A1

Title: Method and apparatus for producing a monocomposite for a tire component

Description:
This application claims the benefit of U.S. Provisional Application No. 60/740,920, filed Nov. 30, 2005. 
    
    
     FIELD OF THE INVENTION  
      The present invention is directed towards tires and the manufacturing of tire components.  
     BACKGROUND OF THE INVENTION  
      Historically the pneumatic tire has been fabricated as a laminate structure of generally toroidal shape having beads, a tread belt reinforcement and a carcass. The tire is made of rubber, fabric and steel. Tire manufacturing generally involves manufacturing the individual tire components such as the innerliner, sidewalls, ply, and then layering each component on a tire building drum. Each component is cut to length and spliced together prior to the application of another component.  
      One disadvantage to the prior art process is that the tire carcass formed of the individual tire components has multiple splices. These splices may contribute to tire nonuniformity resulting in a higher rate of scrap tires. Eliminating the splices is one way to reduce tire nonuniformities. Another disadvantage to the prior art process is due to the fact that each tire component is separately manufactured to a given tire specification and then stored on wind-up trucks until application to the tire building drum. As a result, for a given tire configuration, there are multiple tire components which are stored in inventory. Thus to change tire configurations requires the changing out of all the premanufactured tire components.  
      Thus it is desired to provide a new and improved way of building tires where the number of tire splices is reduced resulting in more uniform tires and a more efficient, less costly way of building tires.  
     SUMMARY OF THE INVENTION  
      The invention provides in a first aspect an apparatus for forming an elastomeric monocomposite of tire components, the apparatus comprising a first and second calender roll, each calender roll being rotatably mounted about its longitudinal axis, one or more elastomeric processors in fluid communication with a nip of said calender rolls, wherein one of said calender rolls has an outer projection.  
      The invention provides in a second aspect a monocomposite elastomeric laminate comprised of a single layer of two or more elastomer composition strips, wherein each elastomer composition strip has a longitudinal axis and a side edge, wherein each elastomeric strip is joined at said side edges without overlapping.  
      The invention provides in a third aspect a method of forming an elastomeric monocomposite of two or more tire components, the method comprising the steps of: providing two or more elastomeric compositions to a nip of two calender rolls, calendering said elastomeric compositions to form a single layer of elastomeric material.  
     Definitions  
      For ease of understanding this disclosure, the following terms are disclosed:  
      “Axial” and “axially” mean lines or directions that are parallel to the axis of rotation of the tire;  
      “Bead” means that part of the tire comprising an annular tensile member wrapped by the carcass ply and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim;  
      “Belt or breaker reinforcing structure” means at least two layers of plies of parallel strands, woven or unwoven, underlying the tread, unanchored to the bead;  
      “Cable” means at least two strands bunched or stranded together to form a reinforcing structure;  
      “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction;  
      “Equatorial plane (EP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of its tread;  
      “Filament” means a generic term for a continuous strand;  
      “Nominal rim diameter” means the diameter of the rim base at the location where the bead of the tire seals;  
      “Normal inflation pressure” refers to the specific design inflation pressure at a specific load assigned by the appropriate standards organization for the service condition for the tire;  
      “Normal load” refers to the specific load at a specific design inflation pressure assigned by the appropriate standards organization for the service condition for the tire;  
      “Ply” means a continuous layer of rubber-coated parallel strands;  
      “Radial” and “radially” mean directions extending radially toward or away from the axis of rotation of the tire; and  
      “Strand” means a reinforcing structure formed of at least one filament. A strand may be used alone for reinforcing or multiple strands may be grouped together to form a cable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will be described by way of example and with reference to the accompanying drawings in which:  
       FIG. 1  is a perspective view of calendering system of the present invention;  
       FIG. 2  is a side view of only the calender rolls of the invention shown in  FIG. 1 ;  
       FIG. 3  is a perspective view of a one piece sheet of a tire component laminate produced by the calendering system of  FIG. 1 ;  
       FIG. 4  is a close up perspective view of the tire component laminate showing the beveled area;  
       FIG. 5  is a perspective view of the tire component laminate just prior to assembly of the ends together;  
       FIG. 6  is an alternate embodiment of the calender rolls of the present invention;  
       FIG. 7  is a first embodiment of the laminate composite of the present invention; and  
       FIG. 8  is a second embodiment of the laminate composite of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The following language is of the best presently contemplated mode or modes of carrying out the invention. This description is made for the purpose of illustrating the general principals of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.  
       FIG. 1  illustrates a first embodiment of a calendering apparatus  10  of the present invention is shown. The calendering apparatus  10  includes a first calender roll  20  having a long cylindrical shape and having an outer surface  22 . The calendering apparatus further includes a second calender roll  30  located adjacent and in parallel alignment for mating engagement with said first calender roll  20 . Each calender roll  20 ,  30  is rotatably mounted to rotate about its longitudinal axis.  
      Interposed between the two calender rolls  20 ,  30  are one or more plows  40 . Located near the calender rolls  20 ,  30  are two or more extruders, gear pumps, injectors or other means  70 ,  72 ,  74  for providing processed elastomeric material to the nip of the calender rolls  20 ,  30 . The plows  40  separate two or more compound feed strips for each tire component. In one example, there is an innerliner feed strip  45  for forming an innerliner, two chafer feed strips  46 , and two sidewall feed strips  47 . Each strip  45 ,  47  may have a different compound composition depending upon the desired component characteristics. During calendering, the different compounds flow together to form a smooth monocomposite continuous sheet  50  of tire components. The interface or adjoining edges between the tire components may be about parallel to the longitudinal axis of the sheet  50 . Alternatively, the interface may be formed at an angle by angling the tips of the plows (not shown).  
      Preferably, the calender roll  30  is divided into sections which corresponds to a different tire component. Each calender section is contoured to a predetermined profile for the selected tire component. For example, the inner section of the calender roll  30  corresponds to the innerliner  52 . The outer sections correspond to formation of the tire sidewalls  56 , and have an outer contour to form the desired shape of the sidewalls. The contoured calender roll  30  further has two sections located between the inner liner section and the sidewall sections, which correspond to formation of the tire chafers  54 , located between the inner liner  52  and the sidewalls  56  on the monocomposite  50 .  
       FIG. 3  illustrates the monocomposite sheet  50  of tire components produced by the calendering apparatus  10  of the invention. The monocomposite sheet  50  as shown, has an innerliner  52 , on either end of the innerliner are optional chafers  54 , and sidewalls  56 . The tire components may have a flat cross-sectional profile as shown in  FIG. 7 . Alternatively, each tire component may have its unique cross-sectional profile.  FIG. 8  illustrates an embodiment of the monocomposite sheet wherein the sidewalls are contoured.  
      As shown in  FIG. 3 , the monocomposite sheet  50  further includes beveled ends  60 ,  62 . A conventional cutter such as a hot knife may be used to cut the monocomposite sheet along web cut line  63  to form strips of a desired length. The cut line between the beveled ends is about 0.005 to about 0.007 inches thick, to maintain the continuous process. The strips have beveled ends  60 ,  62  which may be lap spliced together on the tire building drum as shown in  FIG. 5 .  
      The beveled ends  60 ,  62  are formed on the calender rolls  30 ,  32 . As shown in  FIG. 2 , the second calender roll  30  has a contoured outer surface  32 , with an outer projection  34 . Outer projection  34  has outer inclined sidewalls  36 ,  38  to produce a beveled splice area  60 ,  62  on the monocomposite as shown in  FIG. 4 .  FIG. 6  is an alternate embodiment of the calender roll system showing an outer projection  74  having steeper angled sidewalls  76 ,  78 . The angle of the bevel splice i.e., length of the sidewalls  60 ,  62  and consequently the angle of the bevel  60 , 62  of the sheet  50  can vary depending on different bead diameters or tire size. For example, a 20-inch diameter bead may have a 12.5 inch long splice, while a 16-inch diameter bead may have a 25 inch long splice. The angle of the splice may typically be in the range of about 1 to about 15 degrees, more typically in the range of about 3 to about 8 degrees.  
      While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be appreciated there are still in the art various changes and modifications may be made therein without departing from the spirit or scope of the invention.