Tire manufacturing method for improving the uniformity of a tire

Abstract

A tire manufacturing method includes a method for optimizing the uniformity of a tire by reducing the after cure radial force variation. The after cure radial force variation vector is modeled as a vector sum of each of the vectors representing contributions arising from the tire building steps—the “tire room effect vector” and a vector representing contributions arising from the vulcanization and uniformity measurement steps—the “curing room effect vector.” In further detail, both the tire room and curing room effect vectors can be further decomposed into sub-vectors representing each radial force variation contribution for which a measurable indicator is available. For a series of tires, the method obtains such measurements as the before cure radial runout (RRO) at one or more stages of the building sequence, measurements of loading angles on the tire building equipment, and measurements made during vulcanization process.

1 . A method for improving the after cure uniformity of a tire comprising: 
 (a) Determining a set of vector coefficients for estimating the after cure radial force variation of a tire;    (b) Estimating the after cure uniformity of an individual tire comprising the sub-steps of: 
 (i) Measuring a before cure radial runout characteristic of said individual tire;  
 (ii) Choosing a harmonic of radial force variation to be optimized;  
   (c) Optimizing the after cure uniformity of said individual tire from said vector coefficients, comprising the sub-steps of: 
 (i) Estimating a loading angle of one or more tire components according to an optimization criterion;  
 (ii) Loading said components on the corresponding manufacturing tooling at said loading angle.  
   
     
     
         2 . The method for improving the uniformity of a tire according to  claim 1 , further comprising the steps of aligning said individual tire at a predetermined curing room azimuth angle, loading said individual tire in said curing mold, and curing said tire.  
     
     
         3 . The method for improving the uniformity of a tire according to  claim 1 , wherein said component comprises a tire carcass and said tooling comprises a second stage building drum  
     
     
         4 . The method for improving the uniformity of a tire according to  claim 1 , wherein the said tire component comprises a tread and belt assembly and said tooling comprises a building form.  
     
     
         5 . The method for improving the uniformity of a tire according to  claim 1 , wherein said optimization criterion is the magnitude of a tire room effect vector and is substantially equal to the magnitude of a curing room effect vector.  
     
     
         6 . The method for improving the uniformity of a tire according to  claim 1 , wherein said optimization criterion is the magnitude of a tire room effect vector and is substantially equal to zero.  
     
     
         7 . The method for improving the uniformity of a tire according to  claim 1 , wherein a pair of said vector coefficients comprises a first stage building drum vector.  
     
     
         8 . The method for improving the uniformity of a tire according to  claim 1  wherein a pair of said vector coefficients comprises a second stage building drum vector.  
     
     
         9 . The method for improving the uniformity of a tire according to  claim 1  wherein a pair of said vector coefficients comprises a tread and belt building form vector.  
     
     
         10 . The method for improving the uniformity of a tire according to  claim 1  wherein a pair of said vector coefficients comprises a transfer ring vector.  
     
     
         11 . The method for improving the uniformity of a tire according to  claim 1  wherein said vector coefficients comprises a carcass radial runout vector and a gain vector.  
     
     
         12 . The method for improving the uniformity of a tire according to  claim 1 , wherein said vector coefficients comprises a tread and belt assembly radial runout vector and a tread and belt assembly radial runout vector gain vector.  
     
     
         13 . The method for improving the uniformity of a tire according to  claim 1 , wherein said vector coefficients comprises a green tire radial runout vector and a green tire radial runout vector gain vector.  
     
     
         14 . The method for improving the uniformity of a tire according to  claim 1 , wherein said vector coefficients comprises a curing room effect vector.  
     
     
         15 . The method for improving the uniformity of a tire according to  claim 1 , wherein said vector coefficients comprises an intercept vector.  
     
     
         16 . The method for improving the uniformity of a tire according to  claim 1 , wherein a tire room effect vector comprises the vector sum of a before cure tire effect vector, a building drum vector, and an intercept vector.  
     
     
         17 . The method for improving the uniformity of a tire according to  claim 16 , wherein said before cure tire effect vector comprises the vector sum of a carcass vector, a first stage building drum tooling vector, a tread and belt assembly vector, and a tread and belt assembly tooling vector.  
     
     
         18 . The method for improving the uniformity of a tire according to  claim 16 , wherein said vector sum of said tire room effect vector further comprises a transfer ring tooling vector.  
     
     
         19 . The method for improving the uniformity of a tire according to  claim 1 , wherein a before cure tire effect vector comprises a vector product of a tire gain vector and a green tire radial runout vector of said harmonic.  
     
     
         20 . The method for improving the uniformity of a tire according to  claim 1 , wherein the step of determining said vector coefficients is performed in a simultaneous action.  
     
     
         21 . The method for improving the uniformity of a tire according to  claim 20 , wherein said simultaneous step comprises a multivariate least-squares regression.  
     
     
         22 . The method for improving the uniformity of a tire according to  claim 1 , wherein said radial runout characteristic is measured on a tire carcass.  
     
     
         23 . The method for improving the uniformity of a tire according to  claim 1 , wherein said radial runout characteristic is measured on a tire tread and belt assembly.  
     
     
         24 . The method for improving the uniformity of a tire according to  claim 1 , wherein said radial runout characteristic is measured on a finished tire.  
     
     
         25 . A method for improving the uniformity of a tire comprising the steps of: 
 (a) Determining a set of vector coefficients for estimating the after cure radial force variation of a tire;    (b) Estimating the after cure uniformity of an individual tire comprising the sub-steps of: 
 (i) Measuring a before cure radial runout characteristic of said individual tire;  
 (ii) Choosing a harmonic of radial force variation to be optimized;  
 (iii) Estimating said after cure uniformity from said vector coefficients.  
   (c) Aligning said individual tire at a predetermined curing room azimuth angle, loading said individual tire in said curing mold, and curing said tire.    
     
     
         26 . The method for improving the uniformity of a tire according to  claim 25 , wherein the step of determining a set of vector coefficients further comprises the sub-steps of: 
 (i) Measuring a before cure radial runout characteristic of a plurality of tires at least one predetermined step during the manufacture of said tires;    (i) Recording a loading angle of said finished tires in a curing mold and curing said tires,    (iii) Measuring the after cure radial force variation for each of said tires;    (iv) Extracting at least one harmonic of the radial runout and of the radial force variation of said tires;    (v) Determining a set of vector coefficients relating the before cure radial runout to the after cure radial force variation of said tires cured in said mold;    (vi) Storing said vector coefficients.    
     
     
         27 . The method for improving the uniformity of a tire according to  claim 25 , wherein the step of determining a set of vector coefficients further comprises the sub-step of recording a loading angle of a tire carcass on a measurement fixture, and the step of estimating the after cure uniformity of an individual tire further comprises the sub-step of recording a loading angle of a carcass of said individual tire on said measurement fixture.  
     
     
         28 . The method for improving the uniformity of a tire according to  claim 27 , wherein said measurement fixture is a tire building drum.  
     
     
         29 . The method for improving the uniformity of a tire according to  claim 27 , wherein the sub-step of measuring the before cure radial runout is carried out with a measurement fixture comprising a tangential imaging means.  
     
     
         30 . The method for improving the uniformity of a tire according to  claim 25 , wherein the sub-step of measuring the before cure radial runout is carried out on a tire building drum at the completion of assembly of said tire.  
     
     
         31 . The method for improving the uniformity of a tire according to  claim 1 , wherein said steps of determining a set of vector coefficients and estimating the after cure uniformity comprises a multivariate least-squares regression of a set of matrix equations corresponding to multiple building drums and multiple curing cavities.  
     
     
         32 . The method for improving the uniformity of a tire according to  claim 1 , further comprising the steps of recording an identifier for a specific building drum and for a specific curing category.  
     
     
         33 . The method for improving the uniformity of a tire according to  claim 1 , wherein the step of determining a set of vector coefficients further comprises the sub-step of recording a loading angle of a cured tire on a uniformity measurement machine.  
     
     
         34 . The method for improving the uniformity of a tire according to  claim 1 , wherein a pair of said vector coefficients corresponds to a uniformity machine vector.  
     
     
         35 . The method for improving the uniformity of a tire according to  claim 1 , wherein the step of determining a set of vector coefficients is repeatedly updated using data from said individual tire.  
     
     
         36 . The method for improving the uniformity of a tire according to  claim 1 , wherein said step of determining a set of vector coefficients and said step of optimizing the after cure uniformity are carried out using the first through fifth harmonics of the radial force variation of said tire.