Cutting-tools of “black diamond”

Abstract

An ASEA robot has been modified for the purpose of grinding cast iron. There was the problem that the paths of the robot, which have to be programmed by the time consuming teach-in method, are not adequate for a continuously decreasing grindstone size. It is fairly simple to correct the paths in one direction by an additive correction of all robot coordinates, and this is just the way in which axial adjustments for a flat grindstone are implemented. But for grindstones of a rather small diameter, which are used radially and which show up a rapidly decreasing radius, a twodimensional correction is necessary. The plane of correction is to be defined by the operator teaching in four points for a search process, which has to determine the grindstone diameter automatically. The vector of path correction is to be defined by the operator teaching in suitable points and marks. For circular and partly circular paths only four, respectively three points must be teached in, thereby defining the whole circle and the radial direction of the correction vector.Correct computations would require coordinate transformations between the robot joint and cartesian coordinates, but this would exceed the capabilities of the Intel 8008 microprocessor used in the ASEA robot system. Therefore all path computations are based on the approximation that the cartesian coordinates at the circular path to be programmed are a linear function of the robot joint coordinates and, with less accuracy, the correction vectors may be transferred as robot joint correction vectors from the place of the search process to the place of the grinding process. The limitations resulting from these approximations are to be accounted for by the operator during the teach-in process. This method has been realized using a three-dimensional force-torque-sensor for determining the grindstone diameter in the automatic search process. The improved robot system was tested in a cast iron manufactory.