A new solution for sharpening helical flute hobs

Abstract

• A complete model of a hob sharpener to sharpen helical flute hobs is established. • The model of circular arc wheel profile to sharpen helical flute hobs is established. • The model of machine settings for form grinding machine to sharpen helical flute hobs is established. • Using a circular arc profile CBN wheel and a form grinding machine, the result exceeds DIN AA. Sharpening helical hobs with a hob sharpener is relatively easy and efficient, but the hob sharpener has poor versatility due to its tilted spindle for sharpening helical flutes. In this paper, we propose a new solution for sharpening helical flute hobs. Geometrically, we simplified the wheel profile to a circular arc, which made it easy to obtain the wheel profile through the circular arc NC (numerical control) function G02 or G03. With the simplified wheel profile, it is much easier to obtain the profile of the wheel made with CBN (cubic boron nitride), even with the use of an ordinary CNC (computer-aided numerical control) contour dressing machine. We also calculated the machine settings for a 5-axis form grinding machine, in which the machine settings of a hob sharpener were transformed into through coordinate transformation. With such new machine settings, the helical flute hob can be sharpened by the form grinding machine. Finally, our numerical examples evaluate the variations between the proposed simplified circular arc wheel profile and the theoretical one. Moreover, the results of our experiment using the form grinding machine with the simplified circular arc profile wheel are illustrated in the plots of the measuring machine.