A tool changer includes a holding member having a tool change arm, a rotating mechanism for rotating the holding member, a forward/backward moving mechanism for moving the holding member forward and backward, and a controller controlling the mechanisms. A zero return controller determines whether the tool change arm is holding tools. When it is not holding tools, the tool change arm is rotated to a predetermined non-interference angle, the tool change arm is translated to a forward/backward movement zero point, and the tool change arm is rotated to a rotation zero point. When it is holding tools, the tool change arm is translated to a forward end, the tool change arm is rotated to position it on an expected path, and the tool change arm is moved along the expected path, thereby moving the tool change arm to the rotation zero point and the forward/backward movement zero point.

A tool changer includes a holding member having a tool change arm, a rotating mechanism for rotating the holding member, a forward/backward moving mechanism for moving the holding member forward and backward, and a controller controlling the mechanisms. A zero return controller determines whether the tool change arm is holding tools. When it is not holding tools, the tool change arm is rotated to a predetermined non-interference angle, the tool change arm is translated to a forward/backward movement zero point, and the tool change arm is rotated to a rotation zero point. When it is holding tools, the tool change arm is translated to a forward end, the tool change arm is rotated to position it on an expected path, and the tool change arm is moved along the expected path, thereby moving the tool change arm to the rotation zero point and the forward/backward movement zero point.

A tool changer includes a tool magazine, a support shaft disposed to have a center axis parallel to an axis of a tool spindle, a drive mechanism for rotating the support shaft about the center axis and moving the support shaft in the axial direction, three tool change arms fixed to the support shaft and each having a tool holding unit, a tool transfer mechanism for transferring a tool pot from the tool magazine to a standby position, and a provisional placing pot disposed at a provisional placing position. The tool changer starts a tool change operation in a state where a tool to be attached to the tool spindle, a tool to be used next, and a tool to be used after the next tool are held by the tool holding units of the tool change arms.

A tool changing arm of an automatic tool changing device includes an elongated body, wherein two ends of the elongated body respectively form two holding arms, and each holding arm could hold a tool holder with a tool fastening unit. Each tool fastening unit includes a positioning seat, a tool fastening rod, and a pushing member, wherein the positioning seat disposed in a groove of the elongated body has a through hole and a stop surface. The tool fastening rod is disposed in the groove, and a part of the tool fastening rod passes through the through hole. The tool fastening rod keeps moving towards the tool holder due to an action of the pushing member, wherein the tool fastening rod has a positioning surface capable of contacting the stop surface, thereby preventing improper loosening of the tool fastening rod.