| 摘要 |
PROBLEM TO BE SOLVED: To provide a spiral tap with an end mill blade, capable of improving efficiency of formation work of a hole by prolonging its service life. SOLUTION: Bottom blades 11 are arranged at the tip surface 2 of the tool body 7 of the spiral tap 1 with the end mill blade. An outer circumferential blade for forming a preliminary hole in a material to be processed cooperating with the bottom blades 11 is formed at the outer circumferential surface 18 of the tool body 7. Gashes 13 are formed on the tip surface 2. Grooves 19 continued to the gashes 13 are formed on the outer circumferential surface 18 of the tool body 7. When the diameter of the tool body 7 at the tip surface 2 is D, the depth L of the gash 13 is set to 0.16D or more. COPYRIGHT: (C)2011,JPO&INPIT |
