External detection magnetoscale protection device for plate and strip hot rolling unit finishing mill roll gap

The invention relates to an external detection magnetoscale protection device for a plate and strip hot rolling unit finishing mill roll gap, and belongs to the technical field of plate and strip hotrolling unit equipment. The external detection magnetoscale protection device for the plate and strip hot rolling unit finishing mill roll gap comprises an HGC cylinder (1), a breathing hole (3), a magnetic ring (4), an attachment cylinder (5), a magnetoscale rod (6), a flexible pipe (7), a drying box (8), desiccants (9) and a filter (10), wherein the magnetoscale rod (6) and the magnetic ring (4)are installed in the attachment cylinder (5) outside the HGC cylinder (1), the breathing hole (3) is formed in the lower end of the attachment cylinder (5), the breathing hole (3) is connected to oneend of the flexible pipe (7), the drying box (8) is connected to the other end of the flexible pipe (7), and the desiccants (9) and the filter (10) are arranged in the drying box (8). The external detection magnetoscale protec