Causes and treatment of milling back deflection in

Reasons and treatment of milling back deflection in the binding process of books and periodicals

milling back is flat and uniform, milling back amount is accurate and stable, and it can also reduce the emission of carbon and other harmful materials. It is an important item of binding book quality control. However, in the daily binding production process, there are some quality defects in the milling back process due to the operation technology, process methods, equipment performance and uneven thickness of the book block. Therefore, only by correctly understanding the causes of milling back failure and Strictly Standardizing and checking the process and technical measures, can we better ensure the binding quality of books and periodicals

milling back deflection caused by poor machinery

1. Milling back deflection caused by the wear and looseness of the shaft hole and shaft rod at the bottom of the support plate

when the shaft hole and shaft rod at the bottom of the support plate are severely worn due to use, the working surface of the support plate and the guide rail sliding on the book clip will inevitably lose the requirements of stable and accurate working parallel state. Then, due to the unstable positioning of the book block, It is bound to lead to the bad situation of milling more while milling less. For example, our factory has encountered this kind of fault recently, and the gap between the upper and lower directions of the support plate is loose by up to 23 mm, resulting in different back milling quantities at both ends. After repair, the abnormal gap was eliminated to ensure a uniform and stable back milling amount

2. Milling back deflection caused by poor adjustment of the support plate

the size of milling back amount mainly depends on the height adjustment of the support plate. From the milling back process, the thinner the book block thickness, the less the milling back, the more conducive to improve the accuracy of milling back. When the thickness of the book block is large and the amount of milling back is also large, it is bound to increase the working resistance of milling back, making the milling back deformation or deflection easy to occur. Therefore, under the condition that the innermost page of the book post can be milled, the milling back amount does not need to be milled as much as possible as the guiding ideology for adjusting the working height of the supporting plate. In addition, if the height of the book support plate is uneven due to improper adjustment, it will inevitably cause the milling back deflection, so that the book back against the high book support plate will be less milled on one side and less milled on the other side. For this, the screw at the bottom of the supporting plate should be adjusted to make the supporting plate parallel to the guide rail to ensure the uniformity of the milling back

3. The working height of the milling back cutter head and the gap between the splints are too large, causing the milling back deflection

the working height and bottom of the milling back cutter head are directly related to the quality of the milling back, which is suitable for detecting the finished or semi-finished workpieces piece by piece. When the distance between the milling back cutter head and the splint is too large, due to the working resistance of the milling back blade to the back of the book, the splint does not play a good role in clamping and supporting the back of the book, In the process of milling back, it is easy to deform the back of the book, resulting in uneven and oblique milling back. Therefore, in order to ensure the quality of the milling back, the milling cutter head should be adjusted to the best condition that the elastic energy absorbed by the test piece cannot be recovered during the return journey, so that the milling cutter tip is as close as possible to the bottom surface of the splint. Under the condition that the cutter tip does not touch the splint, the smaller their clearance is, the more conducive to improving the accuracy of the milling back

4. The blunt edge of the back milling cutter head causes the back milling deflection

keeping the sharp edge of the back milling cutter is also an important condition to determine the accuracy of the back milling. When the edge becomes blunt due to wear, the back milling deformation or deflection is likely to occur due to the increase of the working resistance of the back milling. Especially before milling the book with thick book block, it is easiest to mill the back of the book just entering the knife edge more because of light resistance, and the back of the book is less milled because of high working resistance. The milling deviation of the front and rear back of the book back can reach as much as 23 mm. We have encountered this kind of situation in the process of operation, and the machine can not be adjusted around to solve the problem. After replacing the new Shifeng sharp cutter head, the problem of the size deviation of the back milling quantity can be better eliminated immediately

5. Milling back deflection caused by improper gap size of book clip or non parallelism of two ends

when milling back, the blade edge produces a certain degree of impact on the back of the book. In this case, if the gap between the two book clip splints is adjusted too large or there is a bad situation that one end is larger and the other end is smaller, the book clip cannot clamp the book block, so the book block is very easy to move upward in the process of milling back, resulting in milling back deflection failure. Therefore, the thickness of the washer that controls the distance between the two splints should be adjusted so that the splint can clamp the whole book block evenly when it 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 clip up and down

we know that the milling back is completed in the process of the book clip sliding along the guide rail. This work feature clearly shows that the matching accuracy between the book clip and the rail must maintain a relatively reliable and stable state to avoid the jumping phenomenon during the operation of the book clip. When there is a wear gap between the ball bearing on the book clip and the copper plate of the guide rail, it is bound to cause the milling back deflection or inaccurate failure due to the unstable operation of the book clip. For this, as long as the worn parts are replaced with new accessories, the milling back quality can be ensured

milling back deflection caused by improper process control

1. Milling back deflection caused by uneven binding of book stickers

binding is an important part of binding quality control. Only by making sure that the book stickers are not biased can we ensure a uniform milling back amount. If the book stickers are hurriedly glued without breaking through, then the uneven or inclined book block on the machine milling back will inevitably produce the inconsistent amount of milling back due to the uneven working resistance of the cutter head. Add the end with neat back to mill the back less if the working resistance is large, and the end with uneven back to mill more because the working resistance is light. Therefore, we should pay attention to the operation and technology of book pasting and binding. When binding, we can place a stack of books on the machine one by one, loosen the pressing plate after rushing and compacting, and then put in a stack of book stickers, rushing and compacting, and then add it to a certain thickness in turn, and then bind and glue it on the back. According to this method, the book can be pasted tightly and neatly, and it is not easy to bow when it is pressed and bound, so as to lay a reliable foundation for preventing milling back deflection

2. Milling back deflection caused by excessive thickness on the back glue or different thickness at both ends

the function of the back glue is to stick the book stickers to the cost, which is convenient for the milling back operation. In this sense, the back glue should be able to bond all book stickers. There is no need to put the back glue too thick, otherwise it is easy to increase the working resistance to the milling back due to too thick back glue, resulting in milling back cycle test deflection. In addition, the thickness of the back glue at both ends of the back of the book is different, which will inevitably lead to milling back deflection. Therefore, in order to prevent the occurrence of the above disadvantages, the concentration of back glue solution should be appropriate, and too thick is not conducive to achieving uniform brushing. Keeping good fluidity of the glue is the basic condition for getting uniform glue on the back, and it is also a good guarantee for improving the quality of milling back

3. The back milling deflection caused by the loose pressure of the book block and the different thickness of both ends is obvious. When milling the back, the book clip only clamps the book block to ensure the accuracy of the back milling amount, which is obvious. Then, if the thickness of the head and foot of the book block is not enough, the book clip can only clamp the end with a large thickness. Because the end with a thin thickness is not clamped, it is easy to move upward in the process of milling back, so that the milling volume becomes smaller. This situation is mainly caused by the fact that the book block is not evenly compacted, and the foundation part is often significantly thicker than the crown part. In order to prevent this bad situation, when pressing the book, the head and foot of each small stack of book blocks should be staggered and stacked in reverse, so that the whole stack of book blocks is relatively balanced, so that the thickness of the compacted book block is relatively uniform, which can avoid the milling back deflection caused by the loose clamping of the thickness difference of the book block

to sum up, the milling back deflection fault in the binding process may be caused by one reason, or by the chain reaction caused by the coexistence of a variety of adverse conditions. Only by being good at analyzing and summarizing experience carefully and accurately understanding the above conditions, can we better improve the binding process quality