Automatic clamping device and small-field-angle clamping mechanism

The utility model discloses a clamping mechanism with a small field angle. The clamping mechanism comprises a clamping unit and a clamping driving mechanism, the clamping unit comprises a clamping arm, a clamping arm support and a connecting rod mechanism. A chuck is arranged at the front end of the clamping arm, and a guide groove is formed in the rear end; a guide pin corresponding to the guidegroove is arranged on the clamping arm support, and the guide pin is inserted into the guide groove, so that the clamping arm can slide along the guide groove and can rotate around the guide pin; theconnecting rod mechanism comprises a first connecting rod and a second connecting rod, the first end of the first connecting rod is hinged to the clamping arm, the second end of the first connecting rod is hinged to the first end of the second connecting rod, a lug is arranged on the clamping arm support, and the middle of the first connecting rod is hinged to the lug; the clamping driving mechanism comprises a transmissio