Method and apparatus for decorating articles of non-circular

Abstract

A method and apparatus for decorating or finishing the external surface of an article having a non-circular cross-sectional configuration, the apparatus including a roller for applying a decorating medium to the article surface, wherein during a teaching mode a constant force is applied by the roller to the article while the latter is rotated and during a subsequent decorating or finishing mode the force applied by the roller and the speed of rotation of the article are controlled according to a trajectory generated from information derived during the teaching mode to provide constant pressure and constant linear speed between the article and the decorating medium. In particular, the article is rotated about a first axis and the roller is mounted for free rotation about a second axis and is moved linearly along a path joining the two axes and into contact with the article surface. In the teaching mode, the article is rotated at a constant speed and the roller is urged along the path to apply a constant force substantially perpendicular to the surface of the article. Changes in a parameter at angular increments or intervals of the rotation of the article thereof are detected and utilized to obtain indications of the radius of the article at each of the circumferential increments or intervals. The indications of the radius are utilized to develop the above-mentioned trajectory for controlling the applied force and speed of rotation of the article during the decorating or finishing mode.