ON THE UTILISATION OF THE WORKSPACE OF AN INDUSTRIAL ROBOT FOR MILLING STRUCTURAL TIMBER COMPONENTS - EXPERIMENTAL TRIALS WITH DIFFERENT ARM POSITIONS AND EVALUATION OF MACHINING QUALITY

摘要

Within subtractive manufacturing of timber construction components, industrial robots equipped with a milling spindle hold great potential for efficiency increases and new production methods. A key difference to modern joinery machines is the larger workspace, especially in the horizontal and vertical direction. This pushes the limits for the dimensions of workpiece cross sections and allows for newly thought-out workpiece placement and possibilities for batch processing. However, a basis must be created to assess the quality and to evaluate the effects of different robot positions on the machining quality. The subject of this paper is therefore the machining of pockets in glued laminated timber using the same parameters yet in two test series: A) four different robot positions and tool orientations B) the reach is set to four different values with each two workpiece orientations. The processing quality is then assessed based on four different scales of magnitude: 1) nominal/actual geometry comparison; 2) optical and haptic surface quality assessment; 3) stylus method surface roughness measurements; 4) 3D scans. The results show effects of the position especially in machining directions influenced by longer static levers and mass inertia. Nevertheless, compared to reference workpieces the machining quality is competitive.