Reasons and Treatments of Milling Back Deviation in the Process of Bookbinding

The smooth and even milling back and the accurate and stable milling back are an important item in the book quality control. However, due to the reasons such as the operation technology, the performance of the process equipment and the unequal thickness of the book block during the daily glue production process, there are some quality defects in the milling and backing process. Therefore, only the correct understanding of the cause of milling back failure, from the technical and technical measures to strict standards and checks, in order to better guarantee the book binding quality.

Milling back deflection caused by poor machinery

1. Milling back deflection caused by looseness of shaft hole and shaft wear at the bottom of pallet
When the shaft hole and the shaft at the bottom of the pallet are worn out due to the use, the guide 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 core The instability will inevitably lead to an unfavorable situation in which more milling and less milling occur. For example, if the plant has encountered such failures in the near future, the looseness of the clearance in the lower direction of the pallet is up to 23 millimeters, resulting in a situation in which the amount of back-and-forth milling at both ends varies. The post-repair process eliminates abnormal gaps and ensures uniform and stable milling back.

2. Milling back deflection caused by poor pallet adjustment
The amount of milling back depends mainly on the adjustment of the height of the tray. From the perspective of the milling back process, the thinner the book block thickness and the smaller the milling amount of the book back, the better the accuracy of the milling back. When the book block thickness is large and the milling back amount is also large, it is inevitable that the work resistance of the milling back works to increase, so that the unfavorable conditions of the milling back deformation or deflection tend to occur. Therefore, under the condition that the innermost pages of the signatures can be milled, the milling back amount does not need to be multi-milled as the guideline for adjusting the working height of the booklet. In addition, if the tray is misaligned and misaligned, it will inevitably cause the back of the milling cutter to be skewed, so that the backrest of the book will be less milled while the backing board is high, and the other side will be less. This should be done by adjusting the screw on the bottom of the pallet, so that the pallet board and the guide rails are parallel to ensure the evenness of the milling back.

3, the working height of the milling cutter head and the splint gap is too large to cause milling back deflection
The distance between the working high end of the milling cutter head and the clamping plate has a direct relationship with the quality of the milling back. When the distance between the milling cutter blade and the clamping plate is too large, the milling back blade will work against the back of the book. At this time, the clamping plate is If the backing of the book is not well done, the back of the book is easily deformed in the milling and backing process, resulting in uneven milling and backlash. Therefore, in order to ensure the quality of milling and milling, the milling cutter disk should be adjusted to the best working state so that the milling tool tip is as close as possible to the bottom surface of the clamping plate. The smaller the clearance between the cutter tips is, the better the clearance is. Milling back accuracy.

4, the milling cutter blade edge blunt caused milling back deflection
It is also an important condition for the accuracy of milling and backing to maintain the sharpness of the cutting edge of the milling cutter. When the wear of the cutting edge is dulled, the milling back deformation or deflection will inevitably occur due to the increased resistance of the milling back. In particular, before the books with thick book blocks are booked, the books that have just entered the knife edge are most likely to be back-positioned. The resistance is light because of the multiple milling. The rear part of the book back is less because of the large working resistance. The deviation of the back and forth section of the book can be up to 23mm. many. We encountered such a situation during the operation process. The adjustment of the machine did not solve the problem. After the replacement of the new lion-sharp head, the deviation of the mill's back-to-back error was immediately eliminated.

5, the size of the clip gap is not suitable or the two sides are not parallel to the milled back deflection
When milling and backing, the edge of the knife has a certain degree of impact on the back of the book. In this case, if the gap between the two clips is too large or if there is a big one and a small bad condition, the book clip cannot play the pinched book block. The function, then, the book block in the process of milling and backing is very easy to move upwards, causing milling back deflection fault conditions. Therefore, the thickness of the gasket that controls the spacing between the two plates should be adjusted so that the entire book block can be evenly clamped during the working state of the plate to ensure the milling back accuracy.

6, book folder up and down direction caused by milling back deflection
We know that the milling back is done during the process of the book slide along the guide rail. This work characteristic clearly shows that the accuracy of the book-to-rail matching must be maintained in a more reliable stable state to avoid the operation of the book holder. Beat occurs. When there is a wear gap between the ball bearing and the guide rail copper plate on the book clamp, it will inevitably result in the skewing of the milling back due to unstable operation of the book folder or the occurrence of fault conditions. In this regard, only the worn parts can be replaced with new accessories. Make sure the mill back quality.

Milling back deflection caused by improper control of the process

1, book binding uneven adhesive caused by milling back deflection
Bundling is an important part of the quality control of glue-binding, and it is not skewed to ensure uniform and consistent milling back-to-back. If the book is not glued on the rush to glue on the adhesive, then, uneven or tilting the book block on the machine back and forth, due to uneven working resistance of the cutter plate, will inevitably produce some inconsistent milling back volume Happening. The back end of the book with a relatively neat end has a large resistance to milling and back work, and the end of the back of the book is not milled due to the light resistance of the milling back. Therefore, it is necessary to pay attention to the operation of the book binding technique. When tying, you can place a stack of books on the machine one by one, loosen the plate after compaction, and then place it in a stack of books. After being added to a certain thickness, they can be bundled and glued back. According to this method, the book can be tightly and neatly booked, and it is not easy to press the tightly bound and to prevent the milling and back deflection from laying a reliable foundation.

2. Back milling deflection caused by over-thickness or uneven thickness at both ends
The function of the back is to stick the cost of the book sticking, so that it is easy to put the milling back operation. In this sense, the back glue should be able to adhere to the book paste is appropriate, without the back glue is too thick, otherwise it is easy to back The glue is too thick to increase the work resistance of the milling back, causing the milling back deflection. In addition, the thickness of the adhesive on both sides of the back of the book is not the same, and it will inevitably lead to the deviation of the milling back. Therefore, in order to prevent the occurrence of the above-mentioned ills, the concentration of adhesive glue should be appropriate, and over-concentration is not conducive to uniform brushing. The glue liquid maintains good fluidity, which is the most basic condition for uniform adhesive backing, and it is also a good guarantee for improving the quality of milling and backing.

3, book core pressure is not tight, both ends of the thickness of the milling back deflection
When milling and backing, it is obvious that the book holder can only ensure the accuracy of the milling back-to-back accuracy by clamping the book block. Then, if the thickness of the book block is not the same as the width of the foot, the book holder can only clamp the end with a large thickness. Since the thin end is not clamped, it is easy to move upward during the milling and backing process, so that the amount of milling becomes smaller. This situation is mainly caused by the fact that the book block has not been evenly compacted, and the feet are often thicker than the head of the sky. In order to prevent this unfavorable situation from happening, each small stack of book blocks should be staggered in reverse stacking between the head and the feet so that the stacking of book blocks is relatively balanced and the thickness of the book blocks after compaction is increased. Also relatively uniform, it can avoid the milling back deviation caused by the difference between the thickness of the book block thickness and the loose clamp.

In summary, the mill-back skew failure in the process of glue-binding may be caused by one kind of reason, or it may consist of a series of chain reactions caused by the coexistence of many kinds of unfavorable conditions. Only good at conscientiously analyzing and summing up experience and accurately recognizing All the above conditions can improve the quality of glue-binding process better.