TIRE UNIFORMITY GRINDER AND METHOD

摘要

The apparatus for improving tire uniformity includes contrarotating grinding wheels for removing tire material from the upper and lower shoulder portions of the tire. The grinders are moved into grinding engagement with the tire along a path that is defined by a radius of the tire to ensure that both grinding wheels at each shoulder of the tire make simultaneous contact with the tire. The amount and extent of grinding accomplished by the contra-rotating grinders is controlled by a grind control circuit. The grind control circuit measures the no-load current level of the grinder motor and compares the no-load current level with the current level when the grinder motors are under load. When the grinder current under load is above a predetermined maximum load current, the control circuit will signal the grinders to retract from engagement with the tire until the load current drops below the predetermined maximum level. When the motor load current is below the minimum operating range level, the grinders are signalled to advance into engagement with the tire until the load current reaches the predetermined minimum level. This operation is repeated in cyclic fashion until the tire has been ground a sufficient amount to bring it within an acceptable correction range. An alarm circuit which cooperates with the grind control circuit assures that once a grinding operation is begun it will have a predetermined minimum time duration. The alarm circuit also detects whether one of the shoulder grinders takes too long to engage the tire after the other shoulder grinder has made such engagement. The alarm circuit will stop the grinding operation if too long a period of time has elapsed and if there are other malfunctions of the grinders.