Improving machined surface texture in avoiding five-axis singularity with the acceptable-texture orientation region concept

• The machined surface textures in avoiding five-axis singular problem are concerned.
• The ATOR concept together with the non-singular ATOR is proposed.
• The surface texture of the tool axis picked inside ATOR is acceptable.
• The orientation curve is re-generated with a B-spline curve interpolation schema.

The singular phenomenon is common in five-axis machining process. Most of the existing methods try to solve the problem by deforming the tool orientations or inserting extra cutter locations after the tool path is generated, with the drawbacks that (1) the machining geometry errors are not respected and (2) irregular machined surface textures might be caused. This paper dedicates to improve the machined surface textures in the scenario of avoiding the five-axis singularities. In this paper, the acceptable-texture orientation region (ATOR) concept is proposed. If the tool orientation is picked inside the ATOR, the resulted surface texture is considered to be acceptable. Based on this concept, the tool orientations are optimized locally. For a given tool path, if the orientation curve crosses the singular circle, it is locally modified out of the circle with a bridge point locating schema and a cubic B-spline interpolation technique. Eventually, the obtained new orientation curve goes around the singular circle like a rubber band to avoid the singular problem and remains unmodified to achieve the best machined surface qualities for the rest pieces. As the process is implemented at the tool path planning stage, the machining geometry errors can also be respected.