The invention relates in general to tire manufacturing, and more particularly to an apparatus for forming tire components and a tire, and more particularly to a method of making a composite innerliner, and a tire with a composite innerliner.
Tire manufacturers have progressed to more complicated designs due to an advance in technology as well as a highly competitive industrial environment. In particular, tire designers seek to use multiple rubber compounds in a tire component such as the tread in order to meet customer demands. In order to improve manufacturing efficiency, strip lamination of a continuous strip of rubber is often used to build a tire or tire component.
One tire component of interest is the tire innerliner, which functions to prevent air loss from the tire. Rubbers such as butyl or halobutyl rubber are often used as a major portion of the innerliners. One problem that occurs when strip laminating the tire innerliner is low adhesion of the strip to the adjacent ply layer. Poor adhesion between the inner liner and ply can result in tire defects, resulting in the need to scrap the tire. Increasing the stitcher pressure to ensure adhesion does not solve the problem. Also, using a lower butyl rubber formulation to enhance adhesion typically results in a heavier liner, increasing the weight of the tire.
Thus, an improved innerliner design and method of making is desired which overcomes the aforementioned disadvantages.
“Aspect Ratio” means the ratio of a tire's section height to its section width.
“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers.
“Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17° to 27° with respect to the equatorial plane of the tire.
“Bias Ply Tire” means that the reinforcing cords in the carcass ply extend diagonally across the tire from bead-to-bead at about 25-65° angle with respect to the equatorial plane of the tire, the ply cords running at opposite angles in alternate layers.
“Breakers” or “Tire Breakers” means the same as belt or belt structure or reinforcement belts.
“Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction; it can also refer to the direction of the sets of adjacent circular curves whose radii define the axial curvature of the tread as viewed in cross section.
“Cord” means one of the reinforcement strands, including fibers, which are used to reinforce the plies.
“Inner Liner” means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire.
“Inserts” means the reinforcement typically used to reinforce the sidewalls of runflat-type tires; it also refers to the elastomeric insert that underlies the tread.
“Ply” means a cord-reinforced layer of elastomer-coated, radially deployed or otherwise parallel cords.
“Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.
“Radial Ply Structure” means the one or more carcass plies or which at least one ply has reinforcing cords oriented at an angle of between 65° and 90° with respect to the equatorial plane of the tire.
“Radial Ply Tire” means a belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from bead to bead are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire.
“Sidewall” means a portion of a tire between the tread and the bead.
“Laminate structure” means an unvulcanized structure made of one or more layers of tire or elastomer components such as the innerliner, sidewalls, and optional ply layer.
The invention will be described by way of example and with reference to the accompanying drawings in which:
The coextruder strip 230 is formed of a first discrete layer 232 of a first compound joined to a discrete second layer 234 of a second compound. The first and second compounds are not mixed together to form the coextruded strip 230, and are only joined together at an interface. The first compound 232 is preferably formed of an impermeable material such as butyl, bromobutyl, and halobutyl rubber as well as any material with the air permeability characteristics of butyl, bromobutyl, or halobutyl rubber. The first layer thickness of the impermeable material is preferably in the range of about 0.3 mm to about 2 mm, and more preferably in the range of about 0.6 to about 1.2 mm. The second compound is preferably ply coat or ply compound, and has a thickness in the range of about 0.01 mm to about 0.2 mm, more preferably about 0.01 mm to about 0.1 mm. The overall width of the strip 230 is in the range of about 10 mm to about 50 mm, more preferably 20-40 mm. The term “about” as used herein means a variation of +/−10%.
The ratio of the first compound to the second compound of the strip may be varied almost instantaneously by the dual extruder apparatus 10 shown in
Dual compound Extruder Apparatus
As shown in
The first extruder inlet 32 receives a first compound A, examples of which are described in more detail, below. The first extruder 30 functions to warm up a first compound A to the temperature in the range of about 80° C. to about 150° C., preferably about 90° C. to about 120° C., and to masticate the rubber composition as needed. The output end 34 of the first extruder 30 is connected to an inlet end 43 of a first gear pump 42. Compound A is thus first extruded by the first extruder 30 and then pumped by the first gear pump 42 into a rotatable housing for facilitating flow into a coextrusion nozzle 100. The first gear pump 42 functions as a metering device and a pump and may have gears such as planetary gears, bevel gears or other gears.
The second extruder inlet 62 receives a second compound B, examples of which are described in more detail, below. The second extruder 60 functions to warm up the second compound B to the temperature in the range of about 80° C. to about 150° C., preferably about 90° C. to about 120° C., and to masticate the rubber composition as needed. The output end 64 of the second extruder 60 is connected to an inlet end 45 of a second gear pump 44. Compound B is thus extruded by the second extruder 60 and then pumped by the second gear pump 44, which functions as a metering device and a pump and may have gears such as planetary gears, bevel gears or other gears.
The first and second gear pumps 42,44 are preferably placed in close proximity to each other so that the outlet channels 46,48 of the first and second gear pumps are also in close proximity, as shown in
The rotatable applicator head 70 is rotatable about the Z axis, allowing the nozzle 100 to pivot or rotate. The compound A and compound B flow streams 67,69 enter the rotatable applicator head 70 in a direction parallel with the Z axis. The A and B flow streams 67,69 are decreased in area and angled downwardly prior to entering coextrusion nozzle 100.
The rotatable applicator head can rotate in the range of about, 360 degrees, or more typically about +/−150 degrees from the center position. Because the rubber material changes direction prior to entering the rotatable applicator head, the flow remains unaffected by the rotation of the applicator head. Since rubber or elastomers have memory, changing direction of the rubber material prior to rotation prevents the material from curling or otherwise having an undesirable non-uniform flow.
The dual compound extruder apparatus 10 with the coextrusion nozzle 100 produces a coextruded strip 230 having a first layer 232 of an impermeable compound such as butyl rubber or halobutyl rubber and a second layer 234 of a second compound B. The first layer 112 and the second layer 114 are not mixed together, and are joined together at an interface in a coextrusion zone of the nozzle. The coextrusion zone is located upstream of the nozzle die, where the compound A flow stream joins with the compound B flow stream under high pressure.
The dual compound extruder apparatus 10 can be used to vary the volume ratio of the first or impermeable compound to the second or ply compound of the coextruded strip, by varying the ratio of the speed of the first gear pump to the speed of the second gear pump. The dual compound extruder apparatus 10 can adjust the speed ratios on the fly, and due to the small residence time of the coextrusion nozzle, the apparatus has a fast response to a change in the compound ratios. This is due to the low volume of the coextrusion zone. The dual compound extruder apparatus 10 with the coextrusion nozzle may be used to coextrude a dual compound strip in a continuous manner onto a tire building drum, as shown in
The width of the rubber strip output from the nozzle orifice is typically about 15 mm in width, but may vary in the range of about 5 mm to about 30 mm. The nozzle may be optionally heated to a temperature in the range of about 0 to about 230 degrees F., preferably in the range of about 0 to about 200 degrees F., using external or internal heaters (not shown).
As shown in
The nozzle is oriented at an angle with respect to a tire building surface or core. The nozzle assembly is capable of translating in three directions in discrete index positions in order to accurately apply the rubber to the building surface. The support surface can be a toroid shaped core or a cylindrical shaped tire building drum, or any other desired shape. The primary advantage of applying the strip to a toroidally shaped surface is the finished part is accurately positioned in a green uncured state at the proper orientation to be molded without requiring any change in orientation from the condition in which the strip was initially formed.
The extrudate exits the nozzle in a strip form, having the desired shape of the exit orifice of the nozzle. If a drum or toroid is used as an applicator surface, as the drum or core rotates, a continuous annular strip may be formed. The nozzle can be indexed axially so to form the desired shape of the component. The nozzle can be controlled by a control system wherein the movement of the nozzle so that the multiple layers of strip dictates the shape of the desired tire component.
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.
Number | Date | Country | |
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62781763 | Dec 2018 | US |