Mechanism for controlling opening sizes of clamp

The invention discloses a mechanism for controlling the opening sizes of a clamp. The mechanism comprises an enclasping air cylinder and a control plate for controlling car body welding framework sizes and is characterized in that the control plate includes a movable control plate and a fixed control plate which are oppositely arranged, the fixed control plate is arranged on the body of the enclasping air cylinder, the enclasping air cylinder is provided with a rotary support, and the movable control plate is arranged on the rotary support. The mechanism has the advantages that the mechanism is reasonable in structural design, the locking stabilization principle of the enclasping air cylinder is utilized, the car body welding framework sizes are controlled through the control plate, car body framework welding deformation is small, and the car body welding framework sizes are controlled to be in a theoretical state. 本发明公开了种夹具开口尺寸控制机构，包括抱紧气缸和用于控制车身焊接骨架尺寸的控制板，所述控制板包括相对设置活动控制板和固定控制板，所述固定控制板设在抱紧气缸的缸体上，抱紧气缸上设有转动支架，