Experimental study of a specially designed diamond micro discontinuous grinding tool

In this paper, a novel designed discontinuous micro grinding tool, which is composed of three active units and three passive units, is fabricated based on the calculation of tool unbalance amount and the theory of chatter reduction of unequal pitch milling cutter, and the best difference central angle of active unit is determined based on the theoretical calculation. In order to validate the effectiveness of the proposed discontinuous grinding tool, a grain size contrast experiment, including four kinds of grain sizes W10, W20, W28, and W40 respectively, was firstly designed and conducted to strip out the impact of grain size on the following grinding tool shape contrast experiment. The most suitable grain size W28 is determined based on the comparisons of grinding tool wear, machined workpiece, and grinding forces among these four kinds of grain sizes. In the second tool shape contrast experiment, grinding force during experiment is measured and compared between regular shape and discontinuous shape. A three time relationship of force circle in tool one rotation period is found between discontinuous tool and regular tool, and a great grinding forces reduction of 39.6% and 34.5% for F-x and F-y, respectively are found when axial cutting depth is 10m, 38.9% and 41.2% respectively when axial cutting depth is 20m. Besides, a big improvement of chip removal and therefore the caused much less severe tool wear is found, an initial machining stage lightly worse but middle and late machining stages much better machined surfaces also are observed, then the superiority of new designed discontinuous grinding tool is proved, which is considered to be caused by the greatly improved chip removal ability. Finally, based on the comparison between experiment values and model values, the effectiveness and accuracy of the grinding force model built in this paper are proved. The new proposed discontinuous grinding tool in this study not only can extend the tool life and allow the use of more aggressive machining parameters but also can provide a new design idea for grinding tool.