Patent Application
20200398512
The invention relates in general to tire manufacturing, and more particularly to a method for forming an improved method for making an improved apex for a pneumatic tire.
A conventional radial-ply automobile tire includes radial plies that are wrapped around two annular inextensible beads. The portions of the plies that extend beyond the beads are turned up around the beads, forming “turn-ups.” An annular rubber filler bounded by the turned up ply and the bead is called an “apex.” The choice of dimensions and material properties of the apex affects the performance of the tire, such as tire weight, sidewall stiffness, handling, ride comfort, flexural heat, material fatigue, and tire life. It is desired to form the apex such that is does not have a splice in order to improve tire uniformity and consistency. It is also desirable to form an apex that has a tip that does not curl. It is also desired to have an improved method and apparatus for making an improved apex that can be made of multiple compounds in desired ratios in order to improve the tire's performance attributes previously mentioned. It is further desired to have an improved method and apparatus for making an improved apex that has a continuously variable ratio of two different compounds, which avoids a discrete change from one compound to another.
“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.
“Tangent delta”, or “tan delta,” is a ratio of the shear loss modulus, also known as G″, to the shear storage modulus (G′). These properties, namely the G′, G″ and tan delta, characterize the viscoelastic response of a rubber test sample to a tensile deformation at a fixed frequency and temperature, measured at 100° C.
“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 first layer 212 is formed from a first rubber compound which is typically used to form an apex. The second compound is preferably a rubber compound preferably having high stiffness properties. The first and second rubber compounds of the strip are formed in discrete layers 212, 214, and thus are not mixed together.
The first layer thickness of the first compound 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 layer thickness of the second compound preferably 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 coextruded strip 210 shown in
As shown in
The stiffness may be characterized by the dynamic modulus G′, which are sometimes referred to as the “shear storage modulus” or “dynamic modulus,” reference may be made to Science and Technology of Rubber, second edition, 1994, Academic Press, San Diego, Calif., edited by James E. Mark et al, pages 249-254. The shear storage modulus (G′) values are indicative of rubber compound stiffness which can relate to tire performance. The tan delta value at 100° C. is considered as being indicative of hysteresis, or heat loss.
In a first embodiment, the second rubber compound comprises a stiff rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranging from 18 to 32 MPa, and the first rubber compound comprises a rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranging from 1.2 to 10 MPa. In a more preferred embodiment, the second rubber compound comprises a rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranging from 23 to 31 MPa, and the first rubber compound comprises a rubber composition having a shear storage modulus G′ measured at 1% strain and 100° C. according to ASTM D5289 ranging from 1.4 to 2.3 MPa.
The coextrusion nozzle 100 is preferably mounted upon a rotatable head 70, which allows the rotatable head 70 and nozzle to rotate about the z axis. The nozzle has a small tapered tip. As best shown in
The volume ratio of the first compound to the second compound may be changed by varying the ratio of the speed of the first gear pump of the first compound to the speed of the second gear pump of the second compound. The dual coextruded strip forming 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 residence time. The composite apex forming apparatus 102 further includes an annular flat platen 110 that is rotatably mounted and is preferably oriented in the vertical direction (Z). The annular flat platen 110 preferably has an outer surface having a nonstick coating. The annular flat platen 110 is mounted on a backing plate so that it is retractable in the axial (X) direction, in a direction away from a bead chuck assembly 115.
The bead chuck assembly 115 is located at the radially inner portion of the annular flat platen 110 for receiving and securing a bead therein. The bead chuck is formed of three or more members 118 that are arranged in a circle for radial expansion in order to secure the bead. While the bead chuck holds the bead in place, the annular flat platen provides a rotatable and removable support for applying a continuous co-extruded or dual strip of rubber that is formed into an apex or a combination bead and apex subassembly. In order to remove the bead and apex subassembly, the annular flat platen 110 is retracted in the axial (X) direction away from the bead chuck to facilitate removal of the formed apex A or apex and bead assembly.
The outer receiving surface of the annular platen 110 further comprises one or more bars 122 that are preferably oriented in the radial direction. The one or more bars 122 are preferably coated with the nonstick coating. The annular flat platen 110 further includes at least one or more standoff bars 130 that are preferably oriented in the radial direction. When the annular flat platen is mounted in a first position for applying the apex, the one or more standoff bars 130 are flush with the outer surface of the annular platen such as shown in
Variations in the present inventions 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.
| Number | Date | Country | |
|---|---|---|---|
| 62781781 | Dec 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16659859 | Oct 2019 | US |
| Child | 17008073 | US |
