Positioning device

The utility model discloses a positioning device which comprises a base, annular supporting legs are fixed to the bottom of the base, a cavity is formed in the base, a channel is formed above the cavity, a threaded rod is fixed to the inner wall of the cavity, a motor is fixed to the bottom of the base, and an output shaft of the motor is in transmission connection with a driving shaft. A limiting assembly; a sealing assembly; and an extension assembly. The motor is started to drive the driving shaft to rotate, the threaded rod provided with two sections of symmetrical threads is driven to rotate through transmission of the bevel gear set, at the moment, the sliding block in threaded connection with the outer ring of the threaded rod is separated to move until the sliding block makes contact with the inner ring of the bearing placed on the base, and meanwhile the limiting body block is shifted upwards; and the 7-shaped part at the upper end part of the limiting body block is in contact with the top of the bea