The Firestone Tire & Rubber Company

Christopher D Erickson

John Strand

David P Krause

A grinder for removing a predetermined amount of rubber at a predetermined angle from a raised or recessed area on the sidewall of an inflated tire as the tire rotates. A pair of spaced sensors engage the sidewall area of the tire at predetermined radial spaced locations on opposite sides of the area to be worked. The sensors generate a pair of electrical signals in relationship to the profiles of the sidewall areas engaged thereby. The signals are fed to a microprocessor which calculates the average angle of the raised or recessed area by the difference between the outputs from the two sensors along with the known spacing therebetween and generates a third signal. This third signal is supplied to a servo mechanism which automatically adjusts the grind angle of the grinding wheel to match the average angle of the area to be ground. A fourth signal is supplied by the microprocessor to another servo mechanism which dynamically controls the depth of grind of the grinding wheel in relationship to the profile of the sidewall represented by the signal generated by one of the sensors. In an alternate embodiment the signal generated by the microprocessor representing the average angle of the area to be worked controls the spacing between the tire beads by adjusting the tire mounting chuck to place the sidewall area in a relatively flat plane for perpendicular contact by the grinding wheel eliminating angle adjustment of the grinding wheel.

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Saline, MI, United States of America

Christopher D Erickson