| 摘要 |
<p>A twist drill for making deep holes consists of a cutting section, guiding edges (2) and spiral grooves (23) intended for chip removal. The front wall (4) of the spiral groove (3) consists of two conjugating sections (7, 8). The first section (7) intersecting with the guiding edge (2) constitutes with the generatrix (9) of the external cylindrical surface of the twist drill an angle (α) smaller than 90°. The angle (β) of inclination of a tangent passing through the conjugating point of the first and the second sections (7, 8) of the front wall (4) in relation to the generatrix (9) of the external cylindrical surface of the twist drill is chosen on the basis of the following relationship: 125° > δ > (57° - φ) . K + 90°, where φ is the angle of inclination of the spiral groove (3) in relation to the axis of the twist drill at a given point, K = 1.4-2.1.</p> |
