Positioning assembly applied to clamping mechanism in vacuum cavity

The utility model relates to a positioning assembly applied to a clamping mechanism in a vacuum cavity, which comprises a limiting block which is arranged between two mechanical arms and comprises a mechanical arm fixing part and a mechanical arm abutting part, the mechanical arm fixing part is fixedly connected with a motor control end in one mechanical arm, and the mechanical arm abutting part abuts against the mechanical arm fixing part. The mechanical arm abutting part abuts against the motor control end of the other mechanical arm when the motor control ends of the two mechanical arms are close to each other, and limiting fit is formed. The photoelectric sensor is arranged below the clamping mechanism and can detect the position of the tray; and the control module is respectively connected with the photoelectric sensor and a motor for controlling the rotating positions of the two mechanical arms. By arranging the limiting block and the photoelectric sensor, the positioning assembly applied to the clampin