Four, book block with paste after milling, drawing slot
Milling back and pulling groove are the key steps for glue binding. Milling back is to cut back the book block of the good book along the setting part and cut it into a single page. The back of the book can't be cut into bevels. The groove is the back of the book block that is milled and cut. The undulating groove is deeply drawn and deepened to increase the permeability and contact area of ​​the hot melt adhesive to the book block, so that the pages can be closely adhered. According to the thickness of the paper, the thickness of the book is determined by the thickness of the paper. The depth of the cutting is defined by the number of folded layers of the book. Take 52 g of 60 g paper as an example. The depth of the three-pass book block is 1.52 mm, and the four-fold book block is 23mm. Groove depth is generally controlled between 0.8-1.5mm. If the paper is thick and the fiber is poor, you can pull it deeper, and vice versa. The deepest shall not exceed 1.5mm, and the shallowest shall not be less than 0.8mm. The shape of the pulling groove shall be a ∧ type, and the angle shall be approximately 60°. The distance between two adjacent grooves is generally 35mm, and the concave may be properly adjusted according to the condition of the paper. The distance between slots, the general situation 64 book core can pull 46 slots, 32 books can pull 68 slots, 16 books can pull 810 slots, 8 book core can pull 1012 slots, if milling back Depth and depth of the groove can not meet the requirements, will affect the penetration of glue, resulting in page breaks, loose sheet quality defects, in the inspection of milling back, the depth of the groove is appropriate, but also to check before entering the glue The quality of semi-finished products in the process of matching, bundling, compaction, etc., must also be checked.