The vacancy of the back layer of the book is mainly manifested by the obvious honeycomb pores and bubbles at both ends of the book's sky and feet. Pressing the back of the book hard will have a bumpy feeling. The main reasons for these quality problems are:
â‘ The back milling cutter is not sharp, and the gap between the back milling cutter and the inner wheels of the two squeeze wheels is too large, so that the book's end post appears convex edges during the milling process, resulting in uneven book back.
â‘¡The height of the glue wheel is not adjusted properly, making the glue layer uneven. Too high glue roller makes the back of the book squeezed into a trumpet shape, too low glue roller makes the rubber wheel lack a certain pressure on the back of the book, and it is difficult to apply glue evenly.
â‘¢ Improper adjustment of the supporting and forming mechanism. Too high of the supporting and forming mechanism will squeeze the adhesive layer of the book back, and if it is too low, the cover and the back of the book will not stick together, and the adhesive layer of the book will become empty.
The method of elimination is:
â‘ Check whether the back milling cutter is sharp, and adjust the gap between the inner wheel of the squeeze wheel and the back milling cutter, which should be between 0.1-0.1 5mm.
â‘¡Adjust the thickness of rubber wheel and rubber layer.
â‘¢ Adjust the height of the pallet forming mechanism, which should be adjusted according to the thickness, softness and hardness of the book cover paper.
2. The back cover of the book is wrinkled, the bar lines, the round back, or the back of the book is too high
These problems are factors that directly affect the firmness and appearance of the book. The main reasons for these problems are that the positioning height of the back milling cutter and the positioning height of the supporting and forming mechanism are inconsistent, the supporting and the clamping time of the supporting and forming mechanism are inconsistent, the parts of the supporting mechanism are worn, and the rubber brush is too high. The method to solve these problems is to check whether the positioning height of the back milling cutter and the supporting forming mechanism are consistent. The inspection method is that the distance between the back milling cutter and the bottom clip of the book clip should be kept at 12mm (when the thickness of the supporting side clamping plate is 10mm), and when the supporting mechanism rises to the highest point, the bottom support plate and the bottom of the book clip The jaw should also be kept at 12mm. If the adjustment is not correct, it will directly affect the forming quality of the back of the book. If the support is too high, the back of the book will be wrinkled and the bars are raised. If the back of the book is too high, the back of the book will be round and empty.
During the production process of the Martini offset binding line, it often encounters a variety of different papers, such as newsprint, offset paper, and coated paper. The pages of the book are compacted and uncompacted, the cover of the book is laminated or not, there is thick paper and thin paper, and there are hard and soft. Therefore, in the production process, it is necessary to adjust the support and clamping time of the support forming mechanism according to different paper properties. Use 52g /? Of paper in the book. The thickness of the book is 20mm, and the cover paper is 157g /? Coated paper as an example. When adjusting the machine, pay attention to the following requirements:
â‘ After the book is milled and roughened (brushing should be 1.5mm), the gap between the first rubber wheel and the back of the book should be kept at 0.8mm when glued, because the paper of the book block is thinner and the book is thicker. If the rubber wheel is too high, it is easy to squeeze the back of the book into a trumpet shape. After the book is formed, the quality of the back of the book is not beautiful, the back is high, and the bar line is raised. The gap between the second rubber wheel and the back of the book should be 1.5-2mm. If the height is too high, the glue layer of the book will not reach a certain thickness, and the book will not be firm.
â‘¡In the moment when the book and the cover are glued together, the time of the support should be adjusted to clamp slightly faster than the support. Because the book is thicker, it will cause bars, wrinkles, or concave hearts on the back of the book This adjustment method is limited to Martini NBS-type perfect binding machines, excluding other models and disc machines, and other models and disc machines have other adjustment methods).
â‘¢Severe wear of the supporting mechanism will also cause the appearance of the back of the book to be unsightly. The pallet forming mechanism of the perfect binding machine is the most critical mechanism for book forming, and is an important link that directly affects the quality of the book. If the wear is serious, it will cause inconsistent molding on the back of the book, round and square. When the parts of the supporting mechanism match the upper, lower, left and right margins of more than 3mm, it should be considered to replace new parts, so that the supporting mechanism maintains a good running accuracy and ensures the quality of the book molding.
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