The milling back is even and the milling back volume is accurate and stable, which is an important item for quality control of the bound book. However, in the daily binding production process, due to operational techniques, process equipment performance and uneven thickness of the book block, etc., there are some quality defects in the milling back process. Therefore, only by correctly understanding the cause of the milling back failure and strictly regulating and controlling the process and technical measures can we better guarantee the quality of book binding.
Milling back deflection caused by mechanical defects
1. The milling back deflection caused by the loose shaft hole and shaft rod at the bottom of the pallet
When the shaft hole and shaft at the bottom of the pallet are worn out due to the use, the working surface of the pallet and the slide rail of the book holder will inevitably lose the stable and accurate working parallel state requirements. Then, due to the positioning of the book block The instability of the inevitably leads to the bad situation of more milling and less milling. For example, our factory has encountered such failures recently, and the clearance in the up and down direction of the pallet has been loosened up to two or three millimeters, so that the amount of back milling at both ends is different. After the repair process, the abnormal clearance is eliminated, ensuring an even and stable milling back.
2. Milling back deflection caused by poor pallet adjustment
The amount of back milling is mainly achieved by adjusting the height of the pallet. From the perspective of milling back technology, the thinner the book block thickness, the less the milling amount of the book back is, the more beneficial it is to improve the accuracy of milling back. However, when the thickness of the book block is large and the amount of milling back is large, the unfavorable situation of deformation or deflection of the milling back is likely to occur due to the increased working resistance of the milling back. Therefore, under the condition that the innermost page of the signature can be cut, the amount of back milling does not need to be multi-milling as a guiding ideology for adjusting the working height of the supporting plate. In addition, if the pallet is not adjusted properly and the height is uneven, it will inevitably cause deflection of the milling back, so that the back of the book against the high pallet will be less milled on one side and less on the other side. To this end, the screw at the bottom of the pallet should be adjusted so that the pallet and the guide rail are parallel to ensure uniform milling back.
3. The working height of the milling cutter head and the gap between the clamping plates are too large, causing the milling back to deflect
The working height of the milling cutter head and the distance between the clamping plate have a direct relationship with the quality of the milling back. When the distance between the milling cutter head and the clamping plate is too large, the working resistance of the milling blade on the book back is at this time. If the back of the book is not properly held, the back of the book is easily deformed during the milling process, resulting in uneven and skewed back milling. Therefore, in order to ensure the quality of the milling back, the milling cutter disk should be adjusted to the best working state, so that the milling cutter tip is as close as possible to the bottom surface of the splint. In the case of the blade tip not touching the splint, the smaller the gap, the better the improvement. Precision of back milling.
4. The cutting edge of the milling cutter head becomes blunt, causing the milling back to deflect
The sharpness of the back milling blade is also an important condition for determining the accuracy of the milling back. When the cutting edge wears out and becomes blunt, it will inevitably be deformed or skewed due to the increased working resistance of the back. Especially when milling books with thick book blocks, it is easiest to make the back of the book that just entered the edge of the book, because the resistance is light and more milling, the back of the book back is less milled due to the large working resistance, and the milling amount deviation of the front and back sections can reach 23 mm many. We encountered this kind of situation in the process of operation, and the machine could not solve the problem by turning around. Later, after replacing the new lion sharp cutter head, the deviation of the milling back size deviation was immediately eliminated.
5. Milling back deflection caused by the unsuitable gap size of the book holder or the two ends are not parallel
When milling the back, the blade edge exerts a certain degree of impact on the back of the book. In this case, if the gap between the two book clip clamping plates is too large or there is a bad situation with one big end and one small end, the book holder cannot clamp the book block Function, then the book block is very easy to move upward during the milling process, resulting in a milling back deflection failure. Therefore, the thickness of the washer should be adjusted to control the distance between the two plywood, so that the entire book block can be evenly clamped when the plywood is in working state, so as to ensure the accuracy of milling back.
6. The milling back deflection caused by the loosening of the book holder in the up and down direction
We know that the milling back is completed when the book holder slides along the guide rail. This work characteristic clearly shows that the precision of the cooperation between the book holder and the rail must be maintained in a reliable and stable state to avoid the book holder from running. Bounce phenomenon occurs. When the ball bearing on the book holder and the copper plate of the guide rail have wear gaps, the milling back will be skewed or inaccurate due to the unstable operation of the book holder. For this, only the worn parts should be replaced with new accessories. Ensure the quality of milling back. [next]
Milling back deflection caused by improper process control
1. Milling back deflection caused by uneven binding of book stickers
Bundling is an important part of the quality control of perfect binding, and it is necessary to align the book stickers so that they are not skewed, so as to ensure an even and consistent milling back. If the book sticker is rushed to be glued on the back without rushing, then the machined back of the book block that is uneven or has an inclination will be uneven due to the uneven working resistance of the cutter head, which will inevitably lead to inconsistencies Happening. If the working resistance is larger when the back of the book is trimmed, the less the milling back is, the less the end of the book back is. Therefore, we should pay attention to the operation technology of book binding and strapping. When bundling, you can place a stack of books on the machine one by one, loosen the pressure plate after pressing and compacting, and then put a stack of books and compacting. After accumulating to a certain thickness in sequence, it can be bundled and glued. By operating in this way, the book can be tightly and neatly pressed, and the binding is not easy to bow, and a reliable foundation is laid to prevent the back deflection of the milling.
2. Milling back deflection caused by excessive thickness on the adhesive or uneven thickness at both ends
The role of the adhesive back is to stick the book stickers to the cost, which is convenient for placing and milling the back. In this sense, the adhesive should be suitable for bonding the stickers. It is not necessary to make the adhesive too thick, otherwise it is easy to cause the back Too thick glue increases the working resistance of the milling back, resulting in deflection of the milling back. In addition, the thickness of the glue on both sides of the back of the book is different, which will inevitably lead to the deviation of the milling back. Therefore, in order to prevent the occurrence of the above-mentioned disadvantages, the concentration of the adhesive glue should be appropriate, and excessive concentration is not conducive to achieving uniform glue application. Maintaining good fluidity of the glue is the basic condition for the most uniform and consistent glue, and is also a better guarantee for improving the quality of the milling back.
3. The book block is not tightly pressed, and the back deflection caused by the uneven thickness of the two ends
When milling the back, the book holder can only ensure the accuracy of the milling back by clamping the book block. This reason is obvious. Then, if the thickness of the book's head and feet is not the same, the book holder can only clamp the thicker end. Because the thinner end is not clamped, it is easy to move upward during the back milling process, so that the milling amount becomes smaller. This situation is mainly due to the fact that the book blocks are not evenly compacted, and the foot parts are often significantly thicker than the sky parts. In order to prevent this bad situation from happening, every small stack of book blocks, the head and the feet should be staggered for reverse stacking, so that the whole stack of book blocks is relatively balanced, so that the book blocks after compaction are thin It is also relatively uniform, which can avoid the milling back deflection caused by the difference in the thickness of the book block.
In summary, the milling back deflection failure in the perfect binding process may be caused by one cause, or it may be caused by a chain reaction caused by the coexistence of multiple undesirable conditions. It is only good at carefully analyzing and summing up experience and accurately understanding The above conditions can better improve the quality of the binding process.
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