As a world-class manufacturer of binding equipment, the German Kolbus Company has advanced production and processing technology and a management system that constantly improves the binding technology. The increasing perfection of machine performance is the result of problems encountered in actual operation and corresponding countermeasures. Therefore, it is very necessary to list and discuss the problems encountered in actual operation. Below are some questions about the actual operation of KM470 perfect binding machine, and we will discuss with you.
Appearance binding quality standard and internal binding quality standard
Generally speaking, the appearance quality includes the forming effect of the back of the book: whether the word of the book is centered, whether the upper and lower positioning is consistent (especially important for the set of books); whether the cover is outsourced; whether the adhesive is empty (especially at the top) Whether the title page and the last page are wrinkled; whether the inside of the book block is infiltrated with glue, whether the side glue is sticky and cannot overflow glue, etc. Therefore, the linear quality of the back of the book is more important in the appearance requirements. There are two types of book spine: one is a square back with a flat back and sharp edges. It is characterized by a strong and beautiful appearance, which can fully display the unique charm of paperback books. However, after using the book for a period of time, there is a problem in that the back is sunken and the book belly is protruding. The other type is an arc-shaped spine with a very small arc on the flat base, the edges and corners are not sharp, and a small R angle transition. This type has a natural and beautiful feeling, and better overcomes the above-mentioned problems. Which one is used depends on the customer's needs. In addition, to minimize the thickness difference between the book spine and book block, in the production of wire binding and binding, sometimes it is necessary to go through the process of flattening to help.
So, what are the requirements for the internal binding quality of paperback books? The author believes that, first of all, the adhesion strength of the book block and the low temperature resistance of the glue itself. Although the latter is a problem in the category of raw materials, it still needs to be raised because it is a common and serious problem and one of the weak links in bookbinding. Of course, with the continuous improvement of the performance of hot-melt adhesives, this situation has significantly improved. It is important to select hot-melt adhesives with excellent performance. Adhesive strength not only means sticking to the first page, but also requires that the inner page have a certain tensile strength.
The tensile strength here refers to two directions. One is the tensile force F1 along the vertical direction of the paper, which requires that the single-page paper is torn, and the root of the paper is not degummed, and the other is the tensile force F2 that is perpendicular to the horizontal direction of the paper. It cannot be lower than a predetermined value. These requirements are largely dependent on the quality of the glue itself, but also have a considerable relationship with the adjustment, such as the adhesion strength of the last page of the book block, has always been one of the problems that troubled the KM470 glue binding machine, so that this A concept: the weakest link of wireless book binding is the final horizontal tensile strength of the book block.
How to improve the tensile strength of book block in adjustment
The author believes that in terms of adjustment, the tensile strength is related to the following factors: paper hardness, back milling effect, adhesive layer thickness and sizing temperature, groove depth, density, and groove shape.
Generally, the greater the hardness of the paper, the lower the tensile strength; otherwise, it increases. The milling back effect refers to the flatness of the milling back, the penetration of the grooves and the cleanliness of paper dust and paper powder. A good milling back effect will greatly improve the tensile strength, thicken the adhesive layer and increase the strength. On the other hand, the glue temperature should maintain the best bonding temperature. The so-called best bonding temperature means that the glue at this temperature has the best permeability and adsorption. Increasing the depth and density of the groove will increase the tensile strength, and why can the shape of the groove also affect the tensile strength? When the angle of the groove edge is from 60 ° → 30 ° → 0 ° → negative angle, the tensile strength is obviously enhanced due to the transfer of the force direction, but it cannot be blindly pursued for a small angle, because it will also involve The fluidity and permeability of the glue, only the latter can achieve the desired effect when it meets the requirements of use.
Because the smaller the weight of the paper, the hardness is relatively soft, so it is much easier to bind the paper with a small weight (but the book block is easy to wrinkle on both sides, the following chapter will talk about it). For coated paper with a grammage of over 125g, you need to be cautious. However, although coated paper with the same basis weight differs in paper composition and processing technology, its hardness and the adsorption of glue are also very different. The most difficult thing is the wireless binding of rigid coated paper. This coated paper feels cool. Hard, the end cut is smooth and bright, indicating that it has poor adsorption to the glue. At this time, it is necessary to increase the thickness of the glue layer to increase the sizing temperature moderately (because the temperature drops faster when the glue is in contact with the paper) to increase the groove. Measures such as depth, density, and reducing the angle of the groove edge can improve its tensile strength. Even so, if the grammage exceeds 150g, and the thickness of the book block exceeds 15mm, it is recommended to use the wire binding process.
How to improve the quality of milling back
As mentioned in the previous chapter, the quality of the milling back includes: the flatness of the milling back, the penetration of the groove, and the cleanliness of paper dust and paper powder. The old users of Kolbus know that the back milling system has developed from the first set of cutter heads (including grooving cutters) to the current 3 to 4 groups of rough milling, fine milling, grinding (brushing), and grooving. The cutter head is used to improve the quality of the milling back, because the quality of the milling back not only directly affects the bonding strength of the book block pages, but also affects the forming effect of the back of the book. Therefore, improving the quality of the milling back is the basis for a perfect wireless binding. The first is the flatness of the milling back. The author believes that it is determined by the following factors:
â‘ The book holder and the pressing wheel are suitable for tightness; â‘¡The blade on the cutter head (hereinafter referred to as the moving blade) and the blade fixed above the cutter head (hereinafter referred to as the fixed blade) should maintain a sharp state; â‘¢ Between the fixed blade and the moving blade The clearance should be adjusted; â‘£Whether it is a fixed blade or a moving blade, the quality of the blade material will affect the stability of the milling back quality.
Generally, the blade part of the moving blade is generally made of hard alloy material, and the fixed blade is usually made of ordinary high carbon steel, which is relatively easy to wear. If the fixed blade is worn, if it is not replaced in time, it will directly affect the flatness of the milling back. . If the blade is located at the edge of the blade, a carbide tip is also used. In this way, the blade is sharp and wear-resistant, which can greatly improve the quality and stability of the milling back.
Among the above factors, it is very important to control the gap between the fixed blade and the movable blade.
Due to the influence of thermal expansion and contraction, the cutter must be preheated for about half an hour when it is cold. When the thermal expansion of the cutter head core reaches the limit equilibrium state, stop the cutter head and adjust its gap immediately. Generally, when the running clearance of the milling cutter mandrel is normal, the optimal gap between the inserts is 0.05mm (adjusted with a plug gauge). At this time, the milling state is good, and because the milling resistance of the milling cutter is small, the blade wear is small. It is important that the milling back is flat. Of course, if the machine is used for a long time, the running clearance will increase due to wear. For safety reasons, the clearance between the blades should be adjusted appropriately to 0.1 ~ 0.15mm, or even larger.
The second point, the important thing is the penetrability of the slot on the back of the book. So, what is the role of slotting paperback bound books? It is to increase the contact area with the book block, and at the same time, the depth of the groove formed in the longitudinal direction enhances the structural strength of the adhesive layer, and the angle formed by the groove edge increases the tensile strength of the inner page of the book block. In short, the purpose of the scoring is to enhance the tensile strength of the inner pages of the book block, and the penetrability of the scoring means that the drawn groove should penetrate the entire back of the book, and the drawing groove should be clean and thorough. Conversely, if the penetration of the slot is not good, it means that the slotting knife cuts the side of the back of the book, the slot is not penetrated, and there are still paper scraps on the back of the book that have not been cut, thus covering the root of the virtual The phenomenon of glue, this situation directly affects the tensile strength of the book block, and it is clearly reflected in the problem that the last page is easily pulled apart. So how can the penetration of the groove be improved?
The back milling and grooving of the KM470 glue binding machine produced by Korbus synchronously, and the fixed blade of the grooving knife is fixed by a cantilever type. When the grooving force is applied, the fixed blade will have upward flexibility to make the knife Phenomenon, this is one of the factors that affect the penetration of the groove, so the fixed blade should be fixed at both ends, and the length of the blade beam should be shortened as much as possible to ensure sufficient rigidity. On the other hand, the original KM470 used It is a nylon material with high wear resistance. Although it brings convenience in manufacturing and operation, because nylon material is very easy to wear, after the production of 5000 ~ 10000 books, the fixed blade will have different degrees of wear. In the nylon fixed blade, the curved surface of the blade edge is recessed into it, and the gap between the blades cannot be controlled, causing the last post to be opaque. After the above analysis, the wear of the fixed blade and the gap between the blades become larger, which is the important reason that affects the penetration of the groove. Only when we find the reason, can we determine the improvement plan: first, we will change the fixed blade into a steel piece, and insert a carbide block on the edge of the blade, using a wire cutting process, cut into the desired groove shape, the fixed blade can be fine-tuned left and right for precision Tool setting, gap control and gap adjustment are very important. Be careful and careful, otherwise the cutter head will be easily damaged. The adjustment method is the same as the milling blade. The gap can be set to 0.1mm. In the early models, the density of the grooving is achieved by increasing the number of grooving knives. It is best to install them symmetrically. It is very important to ensure the consistency of the deflection angle of the cutting head. Otherwise, the gap Unable to adjust. The later models all use frequency conversion technology to control the density of the groove, and the effect is very good.
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