The use of light refraction, inverse principle, the center positioning method, can be convenient to see clearly the position of the spine, spine positioning operation to meet user needs, so as to better pull paper positioning speed accuracy of xiamen. Equipped with auxiliary equipment of negative pressure adsorption and double roller hemming, to cover more smooth, do not move, to avoid the bubble. The cover, the board, the middle diameter plate and so on all can accurately adjust the positioning to adapt to the paper thickness 0.5-6mm.