Machining toolholder

A machining toolholder, adapted to be engaged with a tool, wherein the machining toolholder is provided on a spindle and is driven by the spindle to rotate, the machining toolholder comprising:

• a body, comprising a center through hole extended along an axial direction therein;
• a horn, comprising a first section and a second section, wherein the first section and the second section are disposed coaxially and connected with each other;
• the first section is partially inserted into the center through hole;
• the second section is connected to the body and engaged with the tool and the first section is slidably engaged with the body;
• and
• a piezoelectric actuator, adapted to be fit around the horn and controllable to drive the tool to vibrate;
• wherein an outer peripheral surface of the first section is directly and slidably coupled to an inner surface of the center through hole, and an outer peripheral surface of the second section is fixed to the inner surface of the center through hole;
• wherein the second section comprises a first vibration amplitude-amplifying part and a flange;
• the first vibration amplitude-amplifying part is engaged with the tool;
• the flange is extended outwardly from the outer surface of the first vibration amplitude-amplifying part in a radial direction;
• the center through hole comprises a first hole section and a second hole section;
• part of the first section is inserted into the first hole section and is directly and slidably coupled to the first hole section, and the flange of the second section abuts against a wall surface of the second hole section;
• a first resonance node of the horn is formed at a joint between the first section and the body when the piezoelectric actuator vibrates, wherein the first resonance node has a minimum displacement;
• a second resonance node of the horn is formed at a joint between the second section and the body when the piezoelectric actuator vibrates, wherein the second resonance node has a minimum displacement.