Holding apparatus for cutting tool

An apparatus for holding a cutting tool,

• the cutting tool comprising:
• a blade-side cylindrical portion;
• a cylindrical shank having a larger diameter than that of the blade-side cylindrical portion;
• and a wall forming a step between the shank and the blade-side cylindrical portion,
• the apparatus comprising a cylindrical tool inserting hole for receiving the cutting tool shank and a configuration to determine a position of the cutting tool at which the cutting tool is prevented from being detached in an axial direction from the apparatus,
• the apparatus further comprising:
• a retaining ring with a larger inner diameter than the diameter of the shank when no external force is applied to the retaining ring;
• a holding body comprising:
• the tool inserting hole;
• a cavity on a side of an opening of the tool inserting hole, in which cavity the retaining ring is seated whose inner diameter is smaller than the diameter of the shank;
• and a slope which gradually increases a diameter of the tool inserting hole from the cavity towards the opening;
• and
• a pressing member which is disposed onto the blade-side cylindrical portion and includes a pressing portion for pushing the retaining ring from the opening into the cavity,
• wherein when the pressing member moves in a direction from an opening side to a cavity side, the pressing portion pushes the retaining ring along the slope into the cavity from a larger diameter side to a smaller diameter side so that an outer periphery of the retaining ring shrinks and an inner diameter of the retaining ring becomes smaller than the diameter of the shank.