Tool holder for delivering coolant with enhanced stiffness

A tool holder for delivering coolant comprising:

• a mounting flange having
• a first end;
• a second end opposite to the first end;
• a first diameter;
• and
• a first length defined as a distance between the first end and the second end;
• a connecting portion extending from the first end of the mounting flange and having
• a second diameter being smaller than the first diameter;
• a holding portion extending from the second end of the mounting flange and having
• a generatrix being a curved line;
• a length being larger than or equal to 4 times of the first length;
• a third diameter defined at an edge between the holding portion and the mounting flange, being smaller than the first diameter and larger than or equal to the second diameter, and ranging from 0.8 times to 0.9 times of the first diameter;
• a fourth diameter defined at a front end of the holding portion away from the mounting flange, being smaller than the third diameter, and being smaller than 0.4 times of the first diameter;
• and
• a fifth diameter defined at a position on the holding portion separating from the second end of the mounting flange by a first distance, wherein the first distance is 0.5 times of the first length, and the fifth diameter ranges from 0.65 times to 0.75 times of the first diameter.