External detection device for stroke of expanding and contracting cylinder of uncoiling machine

The invention discloses an external detection device for the stroke of an expanding and contracting cylinder of an uncoiling machine. The device comprises an external connection support. A plurality of bolt holes connected with bolts are formed in a vertical plate of the external connection support, and a linear track is installed on a transverse plate of the external connection support and fixedly connected with the external connection support. A moving trolley is arranged in the linear track. A sensor supporting plate is arranged close to the front end of the linear track, and a displacement sensor is horizontally and fixedly installed on the sensor supporting plate. A sensor side flange is installed on the front end face of the moving trolley, a sensing magnet ring is fixedly installed on the outer end face of the sensor side flange, and an ejector rod of the displacement sensor penetrates through the sensor supporting plate and the sensing magnet ring and then stretches into an inner cavity of the moving