Hinge joint for pin roll with smoothed upper and lower single surfaces

The invention discloses a hinge joint for a pin roll with smoothed upper and lower single surfaces. The hinge joint comprises a single lug seat, the pin roll, double lug seats and screws. When the hinge joint is used for installing and connecting the existing product, a common pin roll connecting manner is improved, and the pin roll only needs to pass through a pin roll hole of the single lug seat and then is fixedly connected with the double lug seats through the screws; as unthreaded holes, screw holes in the pin roll can be large so that the screws can conveniently pass; in addition, only one surfaces, in contact with the screw heads, of two ends of the pin roll are smoothed, while the other surfaces of the two ends of the pin roll are kept cylindrical; the corresponding contact surface of the double lug seats is machined to form a cylindrical concave surface, so that the pin roll and the double lug seats can be automatically centered when being compacted, that is, the connecting central points of the pin roll and the single and double lug seats are positioned on the axis of the pin roll; the single lug seat and the double lug seats can be rotatably connected completely as required after the screws are tightened; therefore, the problem that as the pin roll needs to simultaneously pass through three pin holes of the double lug seats and the single lug seat in the prior art, and particularly when high precision movable fit exists between the pin roll and the pin holes and the sizes and the weights of connected workpieces and the pin roll are large, the installing difficulty is increased obviously can be solved.