How to effectively make up the binding version in the imposition process
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In the process of printing books and periodicals, after the folding of the text, there is often a phenomenon of irregular front and wrong heart, that is, the inside pages of the signature are gradually pushed out, and the inner page is offset from the front. In order to ensure that the whole book version and the page number are consistent, in addition to minimizing the error and ensuring that the folding is accurate, the intention should be to intentionally shift the inner page of the signature and the inner core of the saddle stitching product to the direction of the ordering position by 1~2mm. This kind of adjustment of the position of some pages in a post or a certain post in the imposition to ensure the consistency of the finished book and the page number can also avoid the phenomenon of uneven front and wrong heart.
Whether the version of the finished book and the page number are aligned is one of the standards for measuring the quality of books and periodicals. The National Press and Publication Administration publishes the requirements for the detection of high-quality products for book printing: the page number error of the excellent book is ≤ 4mm, and the associated page number error is ≤ 2mm. The version of the heart is skewed ≤ 0.5mm, and the image registration error is ≤ 0.5mm. The style of books and periodicals is becoming more and more lively. Designs such as cross-page, bleeding, and eyebrows are often used in design. Although these methods can improve the grades of books and magazines and maintain their own characteristics, they also put forward higher requirements for binding and cutting. . For example, the cross-page map design not only requires the color of the puzzle area to be consistent during printing, but also the process of imposition, folding, etc. must be accurate: the front eyebrow of the front mouth, the product with the line code of the page code, to ensure the uniformity and width of the front mouth network cable Same as the content. This kind of product needs more attention when it is imposition. Because it involves uncertain factors such as paper thickness and machine performance, the imposition operation will have certain difficulty, and should be specifically analyzed.
The reason for the book book heart shift
There are many reasons for the offset and skew of the finished book, such as the telescopic deformation of printing paper, improper printing pressure and water consumption, inaccurate folding, and mismatched binding. The offsets that are not related to the core and the heart can be easily summarized into the following points.
1. Offset due to the thickness of the printed paper
Ignoring the thickness of the printing paper when grouping and splicing often leads to the offset of the finished book. If the printing is performed with thin paper (such as 50g/m2 or less), the effect of paper thickness can be neglected. . However, the effect of paper thickness on the offset of the core is revealed by printing on thicker paper or in saddle stitching products. The specific performance is as follows: the inside of the finished book is better than the outer post, and the inner page of the post is closer to the front than the outer page. The thicker the paper, the more the number of posts on the saddle, the more obvious the performance. In the conventional layout, the elements of each page are the same, and the positioning of the core is treated uniformly according to the requirements of the mouth, the incision, the head and the foot. With the existence of the thickness of the paper, after the actual folding, the ordering of each page can not completely coincide with the deviation between the printing cores and the positioning of the positioning. Taking the saddle-stitched product of 70g/m2 paper and 4 sheets as an example, the difference between the center page and the outer page can reach 3-4mm. As shown in Figure 1, the deviation is not only in the direction of the mouth, the front mouth, the sky, The direction of the foot also exists, but in contrast, the folding hand in the direction of the head and the foot is one fold less than the direction of the incision, so the total deviation in this direction is small.
2. Deviation caused by too many folding times
The printing paper is the same. If there are too many folding times, the inner and outer pages of the signature will also have a significant offset. This offset is ultimately caused by the thickness of the paper, but it can be controlled by controlling the number of folds. The folding limit for book printing is clearly defined in the industry standard CY/J28-1999: the paper is below 59g/m2. Fold four hands, fold up to three hands at 60-80g/m2, and fold up to two hands at 81g/m2. The main reason for this limitation is that there are too many folds, and the signatures will produce eight-fold pleats, which will affect the quality of the binding. Strictly in accordance with this standard, the front and bottom of the signatures may be controlled within a certain range. However, in actual production, sometimes based on other considerations, the printing paper of about 70g/mZ is folded into four hands, and the printing paper of 105g/m2 or even 157g/m2 is folded by three hands, and the problem of the eight-fold pleats and the core offset generated at this time is relatively high. Seriously, the problem of the eight-fold pleats can be solved by the method of breaking the venting of the folding machine or interrupting the post-stacking first, and the core offset generated by the folding machine needs to be solved according to the treatment method of the front opening.
3. Folding into a post too loose, causing the inner and outer pages to be inconsistent
In principle, the tighter the page is, the better it is. However, due to the limitation of paper tension, the phenomenon of not being tied is always there. In addition, the folding machine adjustment is not in place, the signature will also appear not compact, inclined, hollow, etc. as shown in Figure 2. When a loosely-formed signature is glued, there will be a phenomenon that the page is not penetrated and the paper is not firmly adhered, and the page may be deviated.
Disordered processing
It is very difficult to completely solve the problem of the heartbeat, but it is still possible to control the deviation within a certain range by appropriate processing during the imposition. The processing method is very simple, that is, the deviation that may be generated by the core is biased in the opposite direction in the imposition, thereby offsetting the error that may occur in the finished book. The correct and appropriate bias needs to solve the following problems.
1. Determination of deviation correction
According to the analysis, the deviation of the core is present between every page of the signature from the outside to the inside. Therefore, in principle, the correction should be performed between each page during the imposition. The thicker the paper, the larger the scale to be biased. The closer you are to the inner page, the more you have to give. The determination of the amount of correction should be based on the thickness of the printing paper, and a paper thickness is added every other page in the signature. In the case where the folding is not tight, an empirical value can be attached to each page for correction. In actual production, there is generally no page-by-page correction, but from the perspective of operability, according to the requirements of product accuracy, each page is graded and biased according to the inner 4 pages and the inner 8 pages. For example: the general version of the second version of the general saddle stitching product is 0.5-lmm in the direction of the book, the third version of the overall version of the heart is oriented to the direction of the 1-2mm and so on; using the WD-B550 book rotary offset press The large set of pages printed by other types of printers (two prints per post) has an overall width of 0.5-1 mm for the 8 pages, especially for special products. For the classic works with high quality requirements, although the printing process is adopted, the errors caused by the front and the back are corrected by page-by-page correction by means of repeated proofing and folding in the upper and lower directions.
2. Correction of page number
Different ordering methods and different folding methods have different relative positions on each page in the large version. It is important to distinguish the relative position of each page on the large version to correct the deviation. Skilled imposition operators can accurately spell different models, different heads and feet rules, but generally in order not to make mistakes, before the imposition, you should fold out the sample, draw the sketch, and mark the page number. It will not be confused when processing.
3. Processing of cross-page maps
The splicing of the cross-page map requires very high and low, small errors on the left and right sides will be obvious in the finished book, so the correct stitching is very important. Before processing, it should be carefully analyzed according to the specific position of the two-page code of the cross-page map on the large version. For the flat-stitched and glued products, the existence of the milling and the registration should be considered when the cross-page map is imposed. When you are working on a large version, the spread plan is considered separately. A layout with a cross-page map cannot simply bias the entire version of the heart toward the direction of the book, but separate the cross-page map from the other versions of the text, and the cross-page map does not move, and the other versions of the heart text are normally biased. In the direction of the head and the foot, the whole version of the heart will be corrected up and down together to ensure that the stitching is right and left and right up and down.
The phenomenon of irregularity in the front of the book and the wrong heart is generally formed in the process of imposition. Neglecting this problem often leads to the failure of the product quality to meet the standard and sometimes even more serious consequences. Therefore, it must be taken seriously in normal work.