Tool changing mechanism having function of controlling loosening and pulling tool

A tool changing mechanism having a function of controlling loosening and pulling a tool, the tool changing mechanism comprising:

• a tool base housing provided therein with an accommodating space;
• a mandrel disposed in the tool base housing and located in the accommodating space, the mandrel being formed therein with a chamber communicating with two ends of the mandrel, the chamber of the mandrel being axially provided in a middle section thereof with a keyway, the chamber being formed with a first shoulder portion located at an end of the keyway, and a predetermined number of pulling jaws being pivotably disposed at another end of the keyway;
• a first linked unit located in the chamber, the first linked unit having a first pulling rod, an end of the first pulling rod having an external thread, and another end of the first pulling rod having a connecting portion for connecting a pneumatic cylinder;
• and
• a second linked unit located in the chamber, the second linked unit having a second pulling rod and a pressing head, the second pulling rod being arranged along an axis of the mandrel, an end of the second pulling rod having an internal thread, the pressing head being disposed at another end of the second pulling rod, the second pulling rod being provided with a sliding key, the sliding key corresponding to the keyway of the mandrel, the internal thread of the second pulling rod being screwed onto the external thread of the first pulling rod, and relative screwing rotation therebetween enabling the second pulling rod and the first pulling rod to approach or leave each other, the pressing head approaching the pulling jaws to bring a pressing state when the second pulling rod approaches the first pulling rod, and the pressing head leaving the pulling jaws to bring a relieved pressing state when the second pulling rod leaves the first pulling rod;
• wherein the first linked unit further has a spacer ring, an anti-thrust space ring, and a bearing, the spacer ring is located between the first shoulder portion and a disc spring;
• the anti-thrust spacer ring is located between the disc spring and the bearing;
• and the disc spring is abutted against the first shoulder portion and a second should portion indirectly.