Automatic Defect Recognition in Cutting Tools

Automated metal-cutting manufacturing facilities are strongly dependent on the availability, on demand, of properly configured cutting tools. Tools must not only have the correct geometry but must also be in a suitable state for producing workpieces to the required standards of dimensional accuracy and surface finish. In earlier, manually-operated systems, this was readily achieved through operator skill and vigilance but, in automatic systems, other means must be employed. To this end, work has been undertaken at the University of Hull to develop automatic tool inspection systems based on the use of lasers to scan the cutting edges of tools for the presence of defects. Physical defects such as progressive wear or chipping of an edge can be detected and characterised by such means. Such systems can be implemented in several ways but the most useful are those which allow inspection of tools whilst held either in a local storage system, accessed by an automatic tool changer (ATC), or in the machine tool itself. The paper describes both arrangements and refers specifically to recent work concerned with data capture and signal processing techniques necessary to implement fully automatic inspection systems.