| 摘要 |
PROBLEM TO BE SOLVED: To provide a hole drilling method which can suppress chips generated when drilling a hole from being stuck into a narrow part.SOLUTION: The hole drilling method forms an Fr-side water hole 4 in a cylinder head 1 in which a water jacket 3 with the narrow part 8 is formed. In the hole drilling method, the Fr-side water hole 4 is formed to make the water jacket 3 communicate to the outside of the cylinder head 1 while the water jacket 3 is filled with a coolant in which the cylinder head 1 is formed with a feeding hole and a discharging hole, and the coolant is discharged to the outside of the cylinder head 1 from the discharging hole while feeding the coolant into the water jacket 3 from the feeding hole to maintain a state that the water jacket 3 is filled with the coolant. |
