Tool changer

A tool changer disposed at a tool change position in a machine tool and changing a tool attached to a spindle with a next tool positioned at a standby position, the tool changer comprising:

• a holding member disposed to have a center axis parallel to an axis of the spindle, and provided to be rotatable about the center axis and movable in a direction along the axis of the spindle;
• a rotation mechanism including a rotation servo motor and rotating the holding member at a first rotation speed in normal and reverse directions about the center axis, the rotation servo motor having an encoder;
• a forward/backward movement mechanism including a forward/backward movement servo motor and moving the holding member forward and backward at a first forward/backward movement speed in the direction along the axis of the spindle, the forward/backward movement servo motor having an encoder;
• at least one tool change arm disposed on the holding member to extend in a radial direction of the holding member and holding the tools such that axes of the tools are parallel to the center axis of the holding member;
• a storage having a first threshold previously stored therein;
• and
• a controller calculating a first difference as a difference between a command value for the rotation servo motor and an output value of the encoder of the rotation servo motor and comparing the first difference with the first threshold, in a case where the first difference is equal to or greater than the first threshold, changing a rotational speed of the holding member rotated by the rotation mechanism to a second rotation speed slower than the first rotation speed, and in a case where the first difference is less than the first threshold, maintaining the rotational speed of the holding member rotated by the rotation mechanism at the first rotation speed.