Diameter-expanding tool head and diameter-expanding method thereof

A diameter-expanding tool head, the diameter-expanding tool head defining an axis, the diameter-expanding tool head defining a front end and a rear end relative to the axis, the diameter-expanding tool head comprising:

• an expanding section, the expanding section being formed from the front end toward the rear end relative to the axis, the expanding section being cylindrical, the expanding section being formed with an outer peripheral surface relative to the axis, the outer peripheral surface being a cylindrical surface, the outer peripheral surface being formed with a plurality of convex portions and a plurality of concave portions disposed at intervals, any one of the concave portions being formed between any two of the convex portions, each of the convex portions being an arcuate shape protruding outward relative to the axis, each of the convex portions having a convex peak, the convex peak of each of the convex portions being a part farthest from the axis, each distance being equal, a maximum outer diameter of the expanding section being located at any one of the convex peaks, the convex peak of each of the convex portions being axially connected relative to the axis to form a diameter-expanding surface, the diameter-expanding surface spanning each of the concave portions;
• and
• a blocking section connected to the expanding section, the blocking section being formed on the rear end relative to the axis, an outer diameter of the blocking section being larger than the maximum outer diameter of the expanding section, and a connection between one side surface of the blocking section and the expanding section radially forming a blocking surface relative to the axis.