Patent Publication Number: US-2019184657-A1

Title: Method and apparatus for forming rubber reinforced component

Description:
FIELD OF THE INVENTION 
     The invention relates generally to rubber processing, and more particularly to a method and apparatus for forming a rubber component such as a tread, shear band or other rubber component with reinforcements. 
     BACKGROUND OF THE INVENTION 
     The invention describes a method and apparatus capable of making a rubber component that is reinforced with metal or nonmetal reinforcements. The rubber component may be for example a belt and tread ring assembly or a shear band and tread assembly for a nonpneumatic tire. Typical prior art methods generally utilize expensive equipment such as gear pumps and extruders in order to form a strip of rubber for strip lamination of components. Extruders are typically very high pressure and require large amounts of horsepower in order to form a small strip. Extruders are expensive, and if not used properly, may overheat or overwork the rubber. Thus, an apparatus and method of efficiently producing reinforced rubber component is desired. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, an apparatus for forming a reinforced rubber component is described. The apparatus includes a support frame; a rotatable drum mounted upon the support frame; a rubber strip forming apparatus mounted in close proximity to the rotatable drum for applying a rubber strip onto the rotatable drum; and a reinforcement applier apparatus for applying a reinforcement onto the rotatable drum. 
     According to a second aspect of the invention, a method of forming a reinforced rubber component is described. The method comprises the steps of: providing a rotatable drum; applying a rubber strip onto the rotatable drum to form a first rubber layer in a first direction; applying a reinforcement over the first rubber layer in a second direction opposite the first direction to form a first reinforcement layer; applying a rubber strip over the first reinforcement layer. 
     According to a third aspect of the invention, a method of forming a spliceless tread ring is described. The method comprising the steps of: providing a rotatable drum; applying a rubber strip onto the rotatable drum to form at least three rubber layers, wherein the strip is spirally wound on the rotatable drum to form a green tread ring; and then inserting the green tread ring in a mold and curing the tread ring. 
     According to a fourth aspect of the invention, a method of forming a tire is described. The method comprises the steps of: providing a tire carcass and mounting it on a rotatable drum; applying a rubber strip onto the tire carcass to form at least three rubber layers, wherein the strip is spirally wound to form a green tread ring; and then curing the green tread ring and the tire carcass in a mold. 
     Definitions 
     “Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100 percent for expression as a percentage. 
     “Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire. 
     “Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire. 
     “Chafer” is a narrow strip of material placed around the outside of a tire bead to protect the cord plies from wearing and cutting against the rim and distribute the flexing above the rim. 
     “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
     “Equatorial Centerplane (CP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of the tread. 
     “Footprint” means the contact patch or area of contact created by the tire tread with a flat surface as the tire rotates or rolls. 
     “Inboard side” means the side of the tire nearest the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle. 
     “Lateral” means an axial direction. 
     “Lateral edges” means a line tangent to the axially outermost tread contact patch or footprint as measured under normal load and tire inflation, the lines being parallel to the equatorial centerplane. 
     “Net contact area” means the total area of ground contacting tread elements between the lateral edges around the entire circumference of the tread divided by the gross area of the entire tread between the lateral edges. 
     “Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire. 
    
    
     
       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 front perspective view of a strip forming apparatus of the present invention; 
         FIG. 2  is a closeup view of the strip forming apparatus of  FIG. 1  shown with only half of the application roller for clarity; 
         FIG. 3  is a front view of the applicator wheel of  FIG. 2 ; 
         FIG. 4  is a front perspective view of the strip forming apparatus illustrating the path of the rubber. 
         FIGS. 5 and 6  are a side views of a second embodiment of a milltruder head and the application roller from different angles; 
         FIG. 7  is a bottom view of the milltruder head of  FIG. 5 . 
         FIG. 8  is a front view of a reinforced rubber component making apparatus of the present invention; 
         FIG. 9  is a front view of a wire applicator apparatus of the present invention; 
         FIG. 10  is a front close up view of the wire applicator apparatus of  FIG. 9 ; 
         FIG. 11  is a front view of a mold; 
         FIGS. 12 a  through 12 e    are schematics illustrating the steps for forming a reinforced rubber component. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention as described herein provides a method and apparatus for forming reinforced rubber components. The reinforced rubber components may include for example, a belt and tread structure, and in another example, a shear band useful for a nonpneumatic tire. The invention includes a strip forming apparatus  100  as shown in  FIGS. 1-7  and described in more detail, below. The invention may further include a wire applicator apparatus  500  as shown in  FIGS. 8-10  and described in more detail, below. The strip forming apparatus  100  and wire applicator  500  may be used in conjunction with drum system  600 , shown in  FIG. 8 . The drum system  600  includes a first and second drum  610 ,  620 . The first and second drum  610 , 620  are mounted on a support frame  630  which is rotatably mounted on column  640 . The support frame  630  preferably can rotate at least 180 degrees on column  640 . The column  640  is mounted to lower support frame  650  which can slide on rails  660 . The first and second drums  610 , 620  can slide on rails  660  to a mold ring apparatus  700 . Preferably, there are two mold ring apparati  700 . 
     Strip Forming Apparatus 
     Referring to  FIG. 1 , a strip forming apparatus  100  is shown. The strip forming apparatus  100  includes a mounting frame  110  that is rectangular in shape, with a significantly longer vertical length than width. The mounting frame  110  has an upper end  112  that is pivotally mounted to a servomechanism  120 . The servomechanism  120  functions to traverse the mounting frame forward and aft. The mounting frame  110  hangs vertically on the servomechanism allowing the stitching pressure to be adjusted by the traverse position. The angle α that the strip forming apparatus makes with the vertical direction may be adjusted by a servo mechanism  118 . In order to adjust the stitching pressure, the angle α of the strip forming apparatus is varied. Variation of the angle changes the stitching pressure. Very low stitching pressure can be achieved which is required for small rubber strips. The stitching pressure can be adjusted by the traverse position of the strip forming apparatus in relation to a tire building drum, as described in more detail below. 
     As shown in  FIG. 1 , the mounting frame  110  has a length L and a width W, wherein the length L is aligned with the vertical direction. The length/width ratio is greater than 10. The mounting frame  110  has a plurality (at least two) of spaced apart preheat rollers  130 ,  140 ,  150 ,  160 ,  170  that are positionally fixed and rotatably mounted on the frame. The preheat rollers  130 - 170  are preferably aligned in the vertical direction so that the centers of each roller are preferably in a straight line. Each roller is spaced apart from an adjacent roller in the range of 1-5 inches. The rollers are not calendaring the rubber, as they are spaced apart. Calendering involves forming a shape between two rollers. 
     Each preheat roller has internal heaters (not shown). Preferably, each preheat roller is heated to a different temperature than the other preheat rollers. Preferably, the preheat rollers are progressively heated to a higher temperature so that the first preheat roller  130  is the coolest roller, while the second preheat roller  140  is heated to a higher temperature than the first preheat roller  130 . The third preheat roller  150  is heated to a higher temperature than the second preheat roller  140 , and the fourth preheat roller  160  is heated to a higher temperature than the third preheat roller  150 . Likewise, the fifth preheat roller  170  is heated to a higher temperature than the fourth preheat roller  160 . In summary, the preheat rollers are preferably maintained at progressively higher temperatures, increasing in temperature in the incremental range of about 5-20 degrees per roller with decreasing height of the mounting frame, so that the first or highest roller  130  is the coolest and the lowest roller is the hottest. 
     It is also preferred that the preheat rollers progressively increase in rotational speed from the highest vertical roller  130  to the lowest vertical roller  170 , so that the lowest vertical roller  170  is the fastest. 
     The rubber strip path is wound around the preheat rollers as shown in  FIG. 4 . As the rubber strip is wound around the preheat rollers, the increase in roller speed and temperature results in the strip being stretched and thinned to a strip having the desired width and thickness. In a first example, the series of vertically oriented preheat rollers process rubber stock having a 4-inch width, ¼ inch thickness into a 3-inch wide, ⅛-inch strip of rubber. However, the rubber stock could be any size. The strip formed from the strip forming apparatus may be as narrow as ⅛ inch and wider, and is not limited in size. 
       FIG. 2  illustrates the path of the rubber strip after exiting the series of vertically oriented preheat rollers  130 - 170 . The rubber strip is fed into the opening  210  of a milltruder  200 . The milltruder includes a milltruder head  220  and an application forming roller  230 . A channel  240  is formed between the milltruder head  220  and the forming roller  230 .  FIG. 2  only illustrates half of the forming roller  230  for clarity, while  FIG. 3  illustrates the entire forming roller  230 . The channel  240  preferably decreases in area from the inlet to the outlet adjacent a die  250 . The rubber is fed into the opening of the channel into engagement with the rotating forming roller and the lower end  222  of the head  220 . Preferably, the milltruder head  220  is heated. 
       FIG. 3  illustrates the application forming roller  230 . The application forming roller  230  is comprised of a first conical half  232  and a second conical half  234  separated by a central band  236 . The conical halves  232 , 234  are arranged so that the largest diameter is adjacent the band  236 , while the smallest diameter is axially outward of the band  236 . The application roller  230  may additionally optionally comprise a plurality of grooves or serrations  238 . The grooves or serrations  238  will increase pressure in die area which will increase output. The application roller  230  may optionally comprise a radial groove  260 . The radial groove  260  is used to increase the quality of the edge of the strip. Once rubber fills the groove  260 , it will flow the full 360 degrees back to the head. This action will pull any flash away from the rubber strip being applied to a tire building drum leading to a higher quality product. 
     As the application roller  230  rotates, it pulls rubber between the roller  230  and the milltruder head  220 . As the rubber moves toward a die  250 , the rubber is compressed and mixed both circumferentially and axially in the channel  240  between the milltruder head  220  and application forming roller  230 . The axial mixing/movement is also increased due to the conical shape of the application roller. Since the outer diameter of the roller has a higher surface speed than the smaller diameter of the cone, rubber will tend to migrate to the surfaces with higher surface velocities, ie towards the band  236 , generating additional mixing and pressure at the die opening. If more work or heat is required to process the rubber, the die  250  can be moved out to allow rubber to form a band around the application roller similar to a mill. This will allow multiple “passes” of rubber between milltruder head and roller, thus increasing work input. 
     The strip forming apparatus  100  may apply a strip of rubber onto a drum  300  or onto a carcass under construction. The application pressure may be adjusted by adjusting the angle α that the apparatus forms with the vertical direction. 
     An alternate embodiment of a milltruder head  400  is shown in  FIGS. 5-7 . As shown in  FIG. 7 , the milltruder head  400  has a lower surface  410  having a curved surface. The lower surface  410  has a hole  424  for receiving a pin  426  therein. The pin  426  preferably has a beveled upper surface that protrudes from the lower surface  410  of the head. The curved lower surface has a V shaped groove  420  with the narrow portion of the V terminating in a die outlet  430 . The die outlet  430  is positioned adjacent the band  236 . 
     Reinforcement Applicator Apparatus 
     The reinforcement applicator apparatus  500  is shown in  FIGS. 8-10 . The reinforcement applicator apparatus  500  is useful to apply reinforcements such as metal wire, nylon or aramid reinforcements. Reinforcement is fed from a spool  510  through opposed rollers  520 , 522  to applicator head  530 . Located adjacent the applicator head  530  is stitcher roller  540  for pressing the reinforcement into the rubber surface upon which the reinforcements are applied. The applicator head  530  is mounted on housing  550 . The angle of the housing with the vertical axis may be adjusted to vary the application pressure of the reinforcement onto the drum. 
     Mold Apparatus 
     The mold apparatus  700  is shown in  FIG. 11 . The mold apparatus  700  includes a plurality of segments  710  which can be arranged to form a ring about a drum  610 , 620 . The segments have an inner face  712  with desired tread pattern. The segments are capable of being heated to desired temperature in order to cure the rubber component. 
     Method of Forming a Shearband 
     A method of forming a shearband onto a drum  610  is illustrated in  FIGS. 12 a  through 12 e   . As shown in  FIG. 12 b   , a first step to form a shearband is to use the strip forming apparatus  100  to apply a continuous strip  800  of rubber onto the drum  610  to form a first rubber layer  810 . Preferably, the layer is formed by spirally winding the continuous strip  800  about the drum  610 . The direction of traverse in this example is from left to right. Next in a second step, the reinforcement applicator  500  is used to apply a first reinforcement layer  820  over the first rubber layer  810  by traversing the reinforcement applicator  500  from right to left as the drum rotates, so that the reinforcement is applied over the first rubber layer  810 . Preferably, the reinforcement is spirally wound over the first rubber layer  810 . The reinforcement is pressed into the first rubber layer  810  by the stitcher roller  540 . The strip forming apparatus  100  is able to be in close proximity to the reinforcement applicator in a side by side manner. Thus, in a third step, the strip forming apparatus  100  may continuously wind a strip of rubber over the first reinforcement layer  820  while the reinforcement applicator is applying the first reinforcement layer. 
     These steps one through three may be repeated in order to build a shear band having the desired number of rubber and reinforcement layers. In a second embodiment of a shearband, there are at least two layers of rubber between the reinforcement layer. The shearband may include 3 layers of spirally wound reinforcements separated from each other by two layers of rubber, for a total of 6 layers of rubber. An additional 3 layers of rubber is added for the tread layer. After the shearband is formed on the drum, the drum may be slid on rails and inserted into mold. The mold segments are moved radially inwards about the shearband, and the mold segments are heated to the desired temperature to cure the shearband. 
     Method of Forming a Tread Structure 
     The reinforcement applicator  500  and the strip applicator  100  may be used in conjunction with conventional tire building drums. In one embodiment, the reinforcement applicator  500  may be used to form belts directly onto a shaped toroidal carcass that is mounted on a tire building drum. The reinforcement applicator may form one or more zigzag belts. The strip applicator may be used to spirally wind a strip of rubber directly onto the carcass to form a tread. 
     Retread 
     In this embodiment, a spliceless tread is built onto the drum  610 , and is useful in retreading operations. The strip forming apparatus  100  is used to apply a continuous strip  800  of rubber onto the carcass to form one or more rubber layers. Typically, at least three layers of rubber is needed to form a tread ring. The tread ring is then inserted into mold  700  and then cured. The cured tread ring may then be mounted and then glued onto a buffed carcass as known to those skilled in the art of retreading of tires. 
     The advantages of the system are: Significant reductions in capital costs of a system vs extrusion. Significantly lower horsepower required (lower energy costs). Since the size of the system is small, multiple strips can be applied to the building drum simultaneously. This reduces capital cost and increases output because fewer drums and less conveying of building drums is required. Since the entire assembly is hanging vertically, stitching application pressures can be more easily achieved vs present extrusion technology. This leads to reduced trapped air and a higher quality product. Being able to control this stitching pressure also allows for reinforcement to be applied directly to the building drum without pre-calendering, further reducing complexity and costs. 
     Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.