| 摘要 |
FIELD: working materials by cutting, drilling holes in metals, resinous and polymeric materials, in stone, concrete and wood. ^ SUBSTANCE: drill includes large number of cutting portions on working end of its base and cuttings removing grooves. Each groove is formed between adjacent cutting portions and it is designed for removing cuttings to basic end of base. In order to enhance manufacturability each cutting portion has at least three cutting blades arranged one near another in radial direction in such a way that first blade is arranged radially inside relative to second and third blades while second blade is arranged between first and third blades in radial direction. Circumferential positions of first, second and third cutting blades are arranged with deviation backwards according to given order in direction of drill rotation. Wall of back edge of cuttings removing groove corresponding to third cutting blade is arranged in the same position or downstream in rotation direction relative to its cutting surface. In order to provide removal of cuttings cut off by each cutting portion, just near said portion recess is formed. Said recess is arranged upstream in rotation direction; its one surface is made by cutting off outer peripheral surface of portion of working end of base. Inner edge of recess is arranged radially inside relative to outer edge of first cutting portion and it passes to position lower than outer edge of said recess. ^ EFFECT: improved manufacturing process for making annular drill. ^ 22 cl, 16 dwg |
