Patent ID: 8726708

Claim:
An apparatus, comprising: a roller hemming device including: a robot manipulator and a roller attached to a front end of the robot manipulator for carrying out at least one of a pre-hemming or hemming process for a workpiece having an outer sheet mounted on a mold and an inner sheet stacked on the outer sheet, the robot manipulator configured to move the roller while the roller is pressed against the peripheral edge of the outer sheet so that the peripheral edge of the outer sheet nipped between the roller and the mold is bent; a position detector for detecting a current position of the roller; a force measurer arranged between a wrist section of the robot manipulator and the roller; and a controller for controlling the position of the roller by using an output of the position detector and an output of the force measurer, so that pressing force applied to the mold by the roller is a predetermined value, wherein the controller controls the position of the roller by using an output of the position detector and an output of the force measurer, so that pressing force applied to the mold by the roller is a predetermined value and moment applied to the roller is a predetermined value, and wherein the roller hemming device further comprises a movement controller for controlling the movement of the roller so that a predetermined force is applied to the roller in a direction perpendicular to both the pressing direction of the roller against the mold and a traveling direction of the roller, by using the output of the force measurer, during the pre-hemming or hemming process, wherein the apparatus further comprises: a calculator for calculating positional error of the robot manipulator relative to the peripheral edge of the outer sheet, based on the position of the roller obtained from the position detector, the force and moment obtained from the force measurer and information regarding the shape of the roller, wherein the apparatus is configured for correcting a start point for the pre-hemming or hemming process based on the positional error.