Using a flea’s hind limb teeth as a slant rack cutter profile to create a helical gear pair tooth surface modification

Most people think gears are a man-made invention; however, the shape of gears also exists in the flea hind leg kinematic mechanism [1]. This research utilized the flea hind tooth profile leg as a basis to fit the tooth profile of a virtual skewed rack cutter. The tooth profile of a virtual skewed rack cutter are created and applied to create helical gear pairs. The tooth surface for the rack cutter is adjusted so that the tooth thickness is maximal at the tooth center. The tooth thickness decreases progressively along the tooth surface longitudinal direction, resulting in a barrel-shaped tooth surface for the rack cutter. The modification method of the gear tooth surface can effectively avoid the problem of edge contact. Installation errors for the gear pair are simulated. The tooth contact analysis (TCA) method is utilized, and the kinematic error of the gear pair is then calculated. It is observed that the vertical component of the installation error in the shaft lead to larger kinematic errors. The values of the vertical component of the installation error at large and small angles were compared. The results show that the kinematic error curve remains unchanged, but as the axis assembly error angle becomes larger, the kinematic error value becomes larger. The finite element analysis method is conducted to explore the gear pair behavior after modification. All tooth contacts occur at the center of the curved surface, effectively avoiding edge contacts.