Green tire evolution for high speed uniformity

Abstract

A method for controlling uniformity in tire manufacturing includes the steps of measuring the radial runout of an uncured tire carcass, modeling the radial force variation contribution of the carcass from the radial runout measurement, measuring the thickness of the tire tread, modeling the mass imbalance of the tread from the tread thickness measurement, forming a green tire by loading the tread onto the carcass at an angle whereby the radial force variation contribution of the carcass is opposed to the tread mass imbalance determined from the tread mass imbalance model, and placing the green tire in a curing press at an angle which minimizes the radial force variation or mass imbalance of the green tire.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a tire showing a frame of reference.

FIG. 2 is a vector polar plot showing the various contributors to green tire radial runout and the resulting radial runout.

FIG. 3 is a mass variation curve with the X axis representing the angular position of the tire and the Y axis representing average tread runout across the width of the tread.

FIG. 4 is an optimization routine for improving the uniformity of a tire.

Claims

1. A method for controlling the uniformity of tires in tire manufacture, comprising the steps of: measuring a radial runout of an uncured tire carcass, wherein the measured radial runout is separated into separate components comprising confection effects, tire building drum effects, and effects from loading the carcass onto the tire building drum and conforming the carcass with a tire tread;modeling a radial force variation contribution of the carcass from the above radial runout measurement;measuring a thickness of the tire tread;modeling mass imbalance of the tread from the thickness measurement;forming a green tire by loading the said tread onto the said carcass at an angle whereby the radial force variation vector contribution of the carcass and the tread mass imbalance vector determined from the tread mass imbalance model minimizes any harmonic, or combination of harmonics, of green tire uniformity.

2. The method according to claim 1, wherein a first harmonic of the green tire uniformity is optimized.

3. The method according to claim 1, wherein the tread is loaded onto the carcass at an angle which minimizes a high speed uniformity of the cured tire.

4. The method according to claim 3, wherein the green tire is placed in a curing press at an angle which minimizes the high speed uniformity of the cured tire.

5. The method according to claim 4, wherein the radial runout measurement is made while the tire carcass is loaded onto the tire building drum.

6. The method according to claim 5, wherein the tread thickness is measured while the tread is on a tire building drum.

7. The method according to claim 3, wherein the tread thickness is measured before the tread is loaded on a tire building drum.

8. The method according to claim 6, wherein the tire carcass is partially inflated.

9. The method according to claim 6, wherein radial runout from confection effects is calculated by vectorial subtraction of an average loading radial runout and an average tire building drum radial runout, from the measured radial runout of the uncured tire carcass.

10. The method according to claim 9, wherein the step of modeling radial force variation of the carcass further comprises: calculating a proportionality coefficient relating the radial runout of the carcass due to loading effects to radial force variation due to loading effects;multiplying the loading proportionality constant by the average loading radial runout to calculate a loading radial force variation;calculating a proportionality coefficient relating the radial runout of the uncured carcass due to confection effects to radial force variation due to confection effects;multiplying the confection proportionality constant by the confection radial runout to calculate a confection radial force variation; anda vector summation of the confection radial force variation and the loading radial force variation.

11. The method according to claim 10, wherein the tread thickness is calculated as the average value of measured thickness values across a portion of the width of the tread.

12. The method according to claim 10, wherein the tread thickness is calculated as the average value of measured thickness values across the entire width of the tread.

13. The method according to claim 10, wherein the proportionality coefficients are calculated using a regression analysis.

14. The method according to claim 10, wherein the proportionality coefficients are calculated at the same time.

15. The method according to claim 11, wherein the tread thickness measurement comprises measuring the tread band.

16. The method according to claim 11, wherein runout of a drum to build the tread is measured.

17. The method according to claim 3, wherein the radial force variation vector contribution of the carcass and the tread mass imbalance vector determined from the tread mass imbalance model are placed out-of-phase.

18. The method according to claim 3, wherein the radial force variation vector contribution of the carcass, the tread mass imbalance vector determined from the tread mass imbalance model, and at least one other uniformity attribute are combined to minimize the high speed uniformity of the tire.

19. The method according to claim 11, wherein the model of tread mass imbalance comprises: calculating a proportionality coefficient relating the tread thickness to the tread mass imbalance;multiplying the tread proportionality constant by the tread thickness to calculate the tread mass imbalance.

20. A tire built by the process comprising: measuring a radial runout of an uncured tire carcass, wherein the measured radial runout is separated into separate components comprising confection effects, tire building drum effects, and effects from loading the carcass onto the tire building drum and conforming the carcass with a tire tread;modeling a radial force variation contribution of the carcass from the above radial runout measurement;measuring a thickness of the tire tread;modeling mass imbalance of the tread from the thickness measurement;forming a green tire by loading the said tread onto the said carcass at an angle whereby the radial force variation vector contribution of the carcass and the tread mass imbalance vector determined from the tread mass imbalance model minimizes any harmonic, or combination of harmonics, of green tire uniformity.