Method for prediction and control of tire uniformity parameters from crown thickness variation
View Patent ↗Improved and more easily implemented methods for predicting uniformity parameters such as uneven mass distribution, radial run out and high speed radial force variation utilize other measurements such as the tire crown thickness variation. When high speed radial force variation is calculated, low speed radial force variation is also measured. Tire crown thickness variation can be measured in different fashions depending on the particular tire manufacturing process employed. By electronically determining resultant uniformity parameters, tires can be improved by rectification to address the uniformity levels. In addition, tire manufacturing can be improved by altering the resultant location of tire crown thickness variation relative to other aspects of the tire and/or tire manufacturing process.
1. A method of electronically determining a uniformity parameter for a tire based on measured crown thickness variation, said method comprising:
measuring on a tire measurement apparatus the crown thickness variation for the tire, the crown thickness variation represented as a vector quantity comprising for each data point a thickness magnitude and corresponding angle representative of angular location around the tire circumference;
identifying tire parameters associated with the tire, wherein said tire parameters associated with the tire comprise tire density, width and radius; and
electronically calculating one or more uniformity parameters for the tire from the measured crown thickness variation and the tire density, width, and radius, wherein said one or more uniformity parameters comprise one or more of uneven mass distribution of the tire and radial run out of the tire;
wherein said step of measuring on a tire measurement apparatus the crown thickness variation for the tire comprises obtaining a surface measurement for the tire carcass and obtaining a surface measurement for the carcass plus crown and determining the crown thickness variation by subtracting the obtained measurements.
2. The method of claim 1 , wherein said step of measuring on a tire measurement apparatus the crown thickness variation for the tire comprises measuring a profile surface of a tread portion of the tire.
3. The method of claim 1 , wherein said step of measuring on a tire measurement apparatus the crown thickness variation for the tire comprises obtaining a surface measurement for the crown portion after the crown portion is provided on an intermediate formation drum.
4. The method of claim 1 , wherein said step of measuring on a tire measurement apparatus the crown thickness variation for the tire comprises subtracting a waveform obtained when circumferentially measuring surface location of an interior surface of the tire from a corresponding waveform obtained when circumferentially measuring surface location of an exterior surface of the tire.
5. The method of claim 1 , wherein said step of electronically calculating one or more uniformity parameters comprises calculating uneven mass distribution (UMD h ) for one or more harmonics (h) using the following model:
UMD
h
_
=
π
2
ρ
wR
0
2
t
n
_
,
where t h represents the crown thickness variation for one or more harmonics (h).
6. The method of claim 1 wherein said tire parameters further
includes a stiffness coefficient (K h e ), and wherein said step of electronically calculating one or more uniformity parameters comprises calculating radial run out (.DELTA.RRO.sub.h) for one or more harmonics (h) using the following model:
Δ
RRO
h
_
=
ω
2
π
ρ
wR
0
2
t
h
_
2
K
h
e
.
7. The method of claim 1 , further comprising a step of electronically identifying a quality characteristic associated with the tire based on a level of electronically calculated uneven mass distribution or radial run out.
8. The method of claim 1 , further comprising a rectification step comprising one or more of grinding or adding extra mass to the tire to reduce levels of uneven mass distribution or radial run out identified in the tire, or building a new tire to improve uneven mass distribution or radial run out based on knowledge of the electronically calculated uneven mass distribution or radial run out due to crown thickness variation.
9. A method of electronically determining a uniformity parameter for a tire based on measured crown thickness variation, said method comprising:
measuring on a tire measurement apparatus the crown thickness variation for the tire, the crown thickness variation represented as a vector quantity comprising for each data point a thickness magnitude and corresponding angle representative of angular location around the tire circumference;
identifying tire parameters associated with the tire, wherein said tire parameters associated with the tire comprise tire density, width and radius; and
electronically calculating one or more uniformity parameters for the tire from the measured crown thickness variation and the tire density, width, and radius, wherein said one or more uniformity parameters comprise one or more of uneven mass distribution of the tire and radial run out of the tire;
wherein said step of measuring on a tire measurement apparatus the crown thickness variation for the tire comprises subtracting a waveform obtained when circumferentially measuring surface location of an interior surface of the tire from a corresponding waveform obtained when circumferentially measuring surface location of an exterior surface of the tire.