Metal sheet punching device

A metal sheet punching device comprising:

• a die including a circular opening and configured to support a metal sheet;
• and
• a punch configured to form a circular punched hole in the metal sheet supported by the die, wherein
• the punch moves toward the die, wherein the punch includes:
• a main body part;
• a cylindrical punching part provided at a distal end;
• a rotating part disposed between the main body part and the punching part so as to be rotatable about a central axis of the punching part as a rotation axis;
• a coated abrasive provided on an outer circumferential surface of the rotating part and configured to polish a sheared edge of the punched hole;
• a spring disposed between the main body part and the punching part such that the spring is capable of contracting and extending in a punching direction, the spring being configured to contract and accumulate a part of a punching load as elastic energy until the punching part comes into contact with and punches the metal sheet, release the elastic energy, and extend after the punching part punches the metal sheet;
• and
• a rotational motion conversion device configured to convert a linear motion in the punching direction of the punching part due to extension of the spring into a rotary motion of the rotating part.