| 摘要 |
The invention relates to a rotary cutting instrument (10, 110) that comprises a barrel (12, 112) having a longitudinal axis (14, 114), and at least one flute (16, 116) and an active part (18, 118). Each active part has a peripheral surface that comprises: a radial cutting edge (20, 120) located at a cutting distance (Rc) from said longitudinal axis, a relieving face (30, 130) located at a relieving terminal distance (Rd) from said longitudinal axis, and a control face (40, 140) located at a penetration control distance (Rp) from said longitudinal axis. These distances meet the following relation: 0 < ?p < ?d, with ?p = | Rc - Rp | and ?d = | Rc - Rd |. The invention can be used in the fields of endodontics and jewellery. |
