Tire Basic Course Tire Basic Course PC Tire Construction Definition Tire Basic Course The tire is the link between the vehicle and the road surface The tire is transmitting forces between the vehicle and the road in • vertical direction spring/ damping function • horizontal direction (lateral) guiding function cornering • horizontal direction (longitudinal) accelerating/ braking Tire Basic Course 10 9 8 7 2 5 1 4 5 3 6 11 12 13 14 15 16 17 18 19 10 Innerliner Carcass Ply Bead Core Apex/ Filler Bead reinforcement Rimstrip Sidewall Belt/ Breaker Capply Tread 1 - Innerliner Tire Basic Course • The innerliner is a (mostly profiled) sheet of rubber with a high percentage of Butyl-rubber • the main purpose of the innerliner is to reduce the air permeation and to ensure the air-tightness of the tire • by the fact that the oxidation of the rubber at the belt edges has direct influence on the durability of a tire, the innerliner also is directly connected with durability issues • the innerliner has also an influence on some NVHrelated problems • in tires with a very small sidewall height the innerliner must also withstand high shear strain stresses 2 – Carcass (Ply) Tire Basic Course • The carcass is made out of layer(s) of textile. This layer(s) are directed in radial direction (90°) • the carcass is connecting the bead (which is attached to the rim) with the crown area and thereby is transmitting forces between these two areas • the carcass cannot transmit bending and pressure forces, only tension forces, the carcass is carrying most of the load caused by the inner pressure of the tire • the material for the carcass is mostly Polyester, Rayon is used for High speed tires (Speed symbol W), • Changing the carcass material/ number of carcass 3 – Bead Tire Basic Course 4 – Apex Tire Basic Course 3/ 4 – Bead/ Apex Tire Basic Course • The apex (bead filler) is an extruded, triangle-shaped profile of rubber with a high shore hardness which is attached directly on the bead bundle in the preparation process • the purpose of the apex is to increased the stiffness in the sidewall and bead area • a higher/ thicker apex increases driving stability/ steering precision • a higher apex adds more masses to the lower sidewall area and therefore can lead to conflicting results in High speed durability • the bead consists of a number of steelcord which (mostly) are arranged in a square shape • the main purpose of the bead is to ensure the connection of the tire with the rim 5 – Bead reinforcements (chipper/ flipper) Tire Basic Course • The bead reinforcements are (mostly) layers of textile attached in the bead area directly to the carcass • the textile layers are cut under a specific angle (30°, 45°) related to the carcass, by this carcass and reinforcement build up a cross-package • due to this package also bending forces can be transmitted in this area • the main purpose of these reinforcements is to stiffen the lower sidewall/ bead area to influence the driving behavior (handling!) and the high speed durability of the tire • for special applications steelcord is used 6 – Sidewall Tire Basic Course • The (combined) sidewall is an extruded rubber profile consisting of two or more different types of rubber • the purpose of the upper part, the sidewall is to protect the carcass against direct mechanical load (e.g. Curbstones) and against Umwelteinflüsse (UV-rays, Ozone etc) • Due to the fact that the carcass cannot transmit bending and pressure forces, but only tension forces a stiff sidewall compound can also influence this force transmission and thereby also influence the driving behavior 7 – Rimstrip Tire Basic Course • the lower part of the sidewall (rimstrip) which is made of rubber with a higher shore hardness is wrapped underneath the bead and overlaps the innerliner • the purpose of this rimstrip is to ensure the correct seating of the tire on the rim • additional purpose esp. with a rim protection rib is to stiffen the lower bead area 8- Belts (breaker) Tire Basic Course • The belts are (at minimum) two layers of calandered steelcord located between the tread/ capply and the carcass • the belts are directed under a specific angle (22°-34°) which is reversed between the belts • thereby the belts together are forming a „package“ of a specific stiffness in axial and circumferential direction • by the width, the angle and the construction of the steelcord the dynamic contour and the footprint and thereby the performance of the tire can be influenced • main task of the belts is to stabilize the „crown“ area of the tire and to transmit forces from the contact patch to the carcass • the (construction of ) the belts have massive influence on the driving stability and the durability of the tire • by every movement through the footprint in a rolling tire but also by radial and circumferential forces the angles between the belts are changing. Therefore the separation/ insulation between the belts and between belt and carcass at the beltedges is necessary. 9 - Capply Tire Basic Course • The capply is made out of layer(s) of textile between the tread and the belt in circumferential direction of the tire • the capply consists of 1 or 2 sheets nylon „full-capply“ or of small strips (1 –15mm) which are wound around the belts (jointless/ spiral capply) • the material for capply is mostly Nylon, for special applications also a hybrid material (Nylon/ Aramid) is used • Nylon has the behavior to shrink under heat. During the curing process the capply therefore builds up circumferential forces around the tire. • The primary function is to reduce the expansion in the crown under service conditions and reduce the movement of the belt package and thereby influence the performance of the tire, i.e. High Speed durability • the material and the construction of the capply have a direct influence on the rolling resistance of a tire 10 - Tread Tire Basic Course • The tread consists of multiple layers of different types of rubber which are made by extrusion • for special application the tread can be wound out of small strips • the tread material is influencing the grip between tire and road and thereby the handling • further purpose of the tread is to influence mileage and rolling resistance • the construction of the rubberlayers has to ensure the electrical conductivity between the road and the vehicle Tire Basic Course # component main FUNCTION MATERIAL DETAIL 1 innerliner air tightness rubber soft 90° 2 carcass radial stiffness textile/cord (rayon/ polyester) 3 bead core rim seating, carcass anchor steel cord 0° 4 apex handling rubber hard 5 bead reinforcement enforcement of bead textile/steel cord 45°/ 60° 6 sidewall abrasion/UV resistance rubber hard 7 belts lat., circ., rad. stiffness steel cords 22°- 36° 8 capply durability nylon/ aramid 0° 9 tread traction/adhesion rubber hard Definition Tire Basic Course A steel belted tire is a inhomogeneous discontinuous Fibre-Cord-Rubber-Compoundconstruction with complex elastic-plastic-viscous characteristics under mechanical and thermal stress
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