Patent ID: 8662134

Claim:
A buffing machine for removing rubber from a tire casing to produce a predetermined target circumference on the casing, the buffing machine adapted to rotatably mount the tire casing onto a rim, the rim associated with a rim motor arranged to rotate the rim about a central axis, the buffing machine comprising: a cutting device including an electric motor and disposed on a moveable arm such that the cutting device is adapted to selectively engage the tire casing at several iterative cutting depths; a position sensor associated with the moveable arm and disposed to provide a position signal indicative of the position of the cutting device in a radial direction from the central axis about which the tire casing is rotatable, the buffing machine being configured to use said position signal to provide a circumference signal also being disposed to provide a circumference signal indicative of a circumference of the tire casing that is indicative of a radial distance between the central axis and an outer surface of the tire casing; and, an electronic controller connected to the position sensor and the cutting device, the electronic controller being programmed to: receive and process the position signal and the circumference signal, move the cutting device into contact with the tire casing at a respective cutting depth for each of several iterative cuts while receiving an electrical signal corresponding to an amount of electrical work that has been expended by the cutting device through each of the iterative cuts, estimate an amount of material removed from the tire casing through the iterative cuts based on the amount of electrical work, between each iterative cut, use the electrical signal corresponding to the amount of work expended by the cutting device during the previous cut to estimate an amount of material stored by the previous cut, the material stored resulting from a difference between a total amount of material made available for removal by moving to a cutting depth of the previous cut and an amount of material actually removed by the previous cut, determine a target outer dimension of the tire casing after buffing, such target outer dimension indicative of a desired distance from the central axis to the outer surface of the tire casing, determine an offset, based on the amount of material removed through the iterative cuts, for a final cut made on the tire casing to be retreaded, such offset being indicative of an amount of rubber not being removed by prior iterative cuts because of elastic recovery of a rubber material of the tire casing after the cutting device has passed over the rubber material; and perform the final cut on the tire casing where the offset is applied to adjust a radial position of the final cut so that it is nearer to the central axis than the target outer dimension, such offset yielding an achieved outer dimension of the tire casing that substantially corresponds to the target outer dimension.