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.

Description

CROSS REFERENCE [0001] This application is a continuation of previously filed PCT application “Tire Manufacturing Method for Improving the Uniformity of a Tire”, assigned PCT / US2004 / 039021, filed Nov. 19, 2004, which is a continuation-in-part of PCT application “Tire Manufacturing Method for Improving the Uniformity of a Tire”, assigned PCT / IB2003 / 006462, filed Nov. 21, 2003.BACKGROUND OF THE INVENTION [0002] The present invention relates to a manufacturing method for tires, more specifically a method for improving the uniformity of a tire by reducing the after cure radial force variation. In a tire, and more precisely, a radial tire, the after cure radial force variation (RFV) can be affected by many variables introduced from the process of assembly of the green (uncured) tire and during curing of the tire. When the radial force variation in a cured tire exceeds acceptable limits, the result may be unwanted vibrations affecting the ride and handling of the vehicle. For these reason...

AI Technical Summary

Benefits of technology

[0008] In view of the above background, the present invention provides a tire manufacturing method that can effectively reduce the after cure radial force variation (RFV) of each tire produced. The method of the present invention operates to optimize each harmonic of RFV. A composite RFV signal, such as those described above, is a scalar quantity that is the variation of the tire's radial force at each angular position around the tire from the average radial force corresponding to the vertical load applied to the tire. When this composite is decomposed into its respective harmonic components, each harmonic of RFV can be expressed in polar coordinates as an after cure RFV vector. This vector has a magnitude equal to the peak-to-peak magnitude of the force variation of the respective harmonic and an azimuth equal to the angular difference between the measuring reference point and the point of maximum RFV.

Problems solved by technology

When the radial force variation in a cured tire exceeds acceptable limits, the result may be unwanted vibrations affecting the ride and handling of the vehicle.

This method is effective, but has the drawback of creating an undesirable surface appearance and of removing wearable tread rubber from the product.

In addition, this method requires an extra manufacturing step and uses expensive equipment.

This method eliminates the undesirable removal of tread rubber, but still requires an extra manufacturing step and high-cost equipment.

A major drawback to this method is its assumption that the formation and vulcanization contributions to after cure RFV are equivalent for each tire.

In fact, these methods contain contradictory assumptions.

Since, the above methods use composite waveforms including all harmonics, these methods fail to optimize the RFV harmonics to which the vehicle is most sensitive.

In this instance, the tire can cause more vehicle vibration problems than if the process were not optimized at all.

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