4 - Low-force elastic beam surface profiler

Abstract

This chapter presents two types of elastic beam surface profilers with a low measuring force for measurement of the micro-edge of a cutting tool. The first profiler is composed of a triangulation-based laser displacement sensor and a cantilever beam. A stylus probe is mounted at the free end of the beam. The surface of the cutting edge is scanned by the stylus. The vertical displacement of the free end of the cantilever beam is measured by the laser displacement sensor. The cantilever beam is designed to make the measuring force to be less than 0.1mN over a measurement range of 100μm. The output of the cantilever probe surface profiler is confirmed from the measurement of roughness standard specimen before it is applied to measure the edge of a cutting tool specimen. The repeatability of the calculated edge angle from the measuring result is evaluated to be 0.33 degrees at an upward slope and 0.79 degrees at a downward slope. From measuring result, the measurement repeatability of cutting edge width is 0.2μm. A both ends supported beam is then employed to replace the cantilever beam in an improved surface profiler so that the tilt error of the stylus probe can be reduced. An intermittent scanning mode is employed in the improved profiler to expand the measurement range while keeping the measuring force to be a constant value of less than 0.1mN through controlling the deformation of the beam to be constant. The cutting edge of a rotary die cutter with a sharp slope of 80 degrees is measured by the improved profiler.