In-depth solution to the problem of opening the loose leaf
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In order to implement the “re-improvement” requirements of the “3·15” quality inspection activities in 2017, and to solve the problem of long-term impact on the quality of book printing, the General Administration of Quality Supervision and Inspection Center organized relevant experts to analyze and revise the solution. Please refer to the relevant departments, publishing units and printing companies for reference.
First, the effect and problem of "one improvement" in 2016
In 2016, the “3·15” quality inspection activities first proposed the “one improvement” requirement for solving the problem of open-laid loose-leaf pages, and formulated a solution, which comprehensively analyzed the causes of the problem of open-laid loose-leaf pages and proposed them in a targeted manner. Related requirements. During the event, local management departments, publishing units, and printing companies attached great importance to the issue of promoting the opening of plastic sheets. The results of the spot check showed that the problem of “opening the glue spread” in the non-conforming product dropped sharply, which was about 48 percentage points lower than that of the previous year. The problem of “opening the rubber spread” was effectively controlled. However, the phenomenon of side glue opening, gum breakage, gelatin root, falling pages, empty back, adhesive backing and so on are still outstanding, and it is necessary to raise awareness, attract attention, and focus on solving.
Second, the four problems solved in 2017
(1) Side glue opening problem
The glue-bonding side glue opening glue refers to the phenomenon that the cover and the book core sticking to the adhesive mouth are not firmly adhered. The performance is as follows: the front side or the back side side glues open the glue, and the front side front side glues open the glue or partially opens the glue (see Fig. 1). In severe cases, the cover is separated from the book block and affects the reader's use (see Figure 2).
Reason 1: a small number of books have a side glue opening phenomenon. First, there are too many downtimes during the operation of the equipment. The cover is not bonded and shaped during the opening time of the glue. Second, the thickness of the batch book is inconsistent, and the thin side glue is in poor contact.
Solution:
(1) Minimize the number of downtimes during normal operation of the equipment;
(2) When the shutdown exceeds the opening time of the glue, 6-8 copies (3-5 pieces of stand-alone machine) should be eliminated;
(3) The rejected book can be reheated and flattened into a good product by hot pressing, without throwing off the cover and throwing it away;
(4) After the folding, the paper should be bundled to reduce the air in the signature to ensure that the thickness of the batch book is basically the same.
Reason 2: There is a phenomenon of side glue opening in the batch book. First, the gap between the rubber wheels on both sides is improperly adjusted, and the contact with the book block is bad; the second is that the side rubber type is improperly selected; the third is that the side rubber temperature is not set according to the technical parameters. The fourth is that the clamping distance is too large when the clamp is clamped.
Solution:
(1) According to the different paper quality, the type and type of adhesive should be selected correctly;
(2) Correctly adjust the spacing of the side rubber wheels according to the actual thickness of the book block to ensure uniform, stable and proper amount of glue;
(3) The temperature of the glue must be determined according to the technical parameters specified by the type and type used. The tolerance is ±5 °C, and the special case is ±10 °C. The data cannot be changed arbitrarily;
(4) Correctly adjust the distance of the clamping block, which is subject to the actual thickness of the book, and should not be too large or too small.
(2) Wireless Adhesive Staples Back Glue Breaking or Dew Root Problem
Some books have broken gums when they are flipped, and the pages of the breaks are not firmly bonded, which affects the reader's reading (see Figure 3); some books are opened on the first or last page of the book cover when the cover is opened. The glue is exposed at the beginning (see Figure 4).
Reason 1: the book folder is not parallel or skewed, the milling back groove is not uniform, and the glue cannot be filled.
Solution:
(1) Correctly adjust the verticality and clamping degree of the book to ensure that the back of the book is in parallel contact with the rubberizing wheel;
(2) Correctly adjust the height of the three sets of rubber wheels of the rubberizing wheel, the rubberizing wheel and the rubberizing wheel.
Cause 2: The milling cutters are not parallel.
Solution:
Check the parallelism of the rotation of the milling cutter and the stability of the cutter in time, and find problems in time to repair or replace.
Reason 3: The type and type of adhesive used are not good or the quality of the adhesive is not good.
Solution:
(1) According to different paper quality, select the appropriate standard and type of adhesive;
(2) Check the technical parameters of the adhesive according to the standard;
(3) Do not misuse and mix adhesive materials.
Reason 4: Adhesive aging deterioration or improper adjustment of glue temperature.
Solution:
(1) Clean the rubber pot on time, the amount of glue should be reasonable, and the glue should not be repeatedly melted for a long time;
(2) The temperature of the glue is based on the technical parameters of the adhesive used, the tolerance is ±5 °C, the special case is ±10 °C, and it is not allowed to increase or decrease at will;
(3) Different types of adhesives should not be mixed.
Reason 5: The paper is different and the glue is improper.
Solution:
(1) When different types of paper and paper are used in the same book, the type and type of the glue to be used shall be the best of the paper;
(2) Different types of adhesives should not be mixed.
Reason 6: The book is exposed before and after the book.
Solution:
(1) When the cover and book core paper, thickness and weight are disparity, the process design should increase
Line the paper to make the tension between the two transition;
(2) When the cover paper is thick and hard, the cover indentation (side rubber peeling marks) should be as deep as possible to prevent the marks or paper from being fractured.
(3) Droppage problem
The wireless glued book has a phenomenon that the page inside the book core is out of the page when it is flipped, which affects the reader's reading (see Figure 5).
Reason 1: the paper of the signature is thick and hard, and the number of folds is too large. The depth of the milling back groove is not enough or the spacing of the groove is too large, and the glue does not fully penetrate into the slot.
Solution:
(1) Increase the depth of the milling back and the groove so that the glue can seep into the innermost sheet.
(2) According to the paper quality, thickness and number of signatures, the groove depth is adjusted to 2mm (standard 1.5±0.5mm) according to the standard requirements.
Reason 2: When folding, the crease is empty, and the innermost sheet is not milled, and there is no glue.
Solution:
Adjust the pressure of the folding paper feed roller, the parallelism and the verticality of the gauge, so that the sheet is correctly conveyed into position, and the crease is tight and seamless.
Reason 3: When the single machine is stored, the book is not flushed, there is a shrinking phenomenon, and the indented signature is not milled, and there is no glue.
Solution:
(1) The single-machine processing shall be equipped with a booklet first, and then processed by the glue-binding machine;
(2) The linkage line should increase the vibration amount of the vibrator, so that the scattered book is shocked and neat;
Cause 4: The paper dust and paper hair are not removed, the slot is blocked, and the glue cannot penetrate.
Solution:
(1) Properly install and use the paper suction device;
(2) Clean the equipment used on time to ensure that the milling and backing device is clean and tidy, so that the production goes smoothly.
Reason 5: The type of adhesive used is not correct, the quality of the adhesive is not up to standard or the temperature is not correct.
Solution:
(1) According to the standard requirements of EVA hot melt adhesive and the paper used, select the correct type and type of adhesive.
(2) The use of glue temperature is based on the technical parameters of the adhesive, the tolerance is ±5 °C, and the special case is ±10 °C;
(3) According to the standard requirements, the softening point of the adhesive should be >82 °C. If the product does not meet the standard, it is a non-conforming product. Do not use it;
(4) Different types of adhesives are strictly prohibited to be mixed.
Reason 6: There is residual adhesive at the bottom of the book board, and the front and back pages are pulled off.
Solution:
(1) Correctly adjust the retention of the book folder, not too high or too low, generally 10mm is suitable for sticking;
(2) Frequently clean the residual adhesive on the edge of the bookboard or apply some silicone oil beforehand to prevent the adhesive residue from sticking to the front and back pages of the book block.
4 Empty back or back glue hole problem
There are holes of different sizes at one or both ends of the backing area or the back of the book, which affects the bond fastness and appearance quality (see Figures 6 and 7).
Reason 1: the air in the book block is not excluded, resulting in the inconsistency between the width of the book back and the thickness of the book block, which results in the clamping degree of the book board being different, which causes the rubberizing wheel to work normally.
Solution:
(1) From the beginning of the folding process, correctly adjust and use the ripper, the air in the signature should be excluded as much as possible;
(2) The folded post must be tied and bundled so that the excluded air is no longer reflowed; the thickness of the batch book is basically the same after the match;
(3) After the folding, the stacked platen method can also be used to stack the stacks of the plaques, and each of the two plates is laminated, and the uppermost layer is also pressed with a plate to achieve the binding effect;
(4) The spacing of the book holder (clamping degree) is adjusted according to the actual thickness in the middle of the book block;
(5) Trapezoidal paper can also be attached to the book holder to solve the parallelism of the clamping.
Reason 2: The height of the rubberizing wheel is not properly adjusted, and the effect of the three wheels is not understood.
Solution:
(1) Correctly understand the respective uses of the three sets of rubber wheels, such as rubberizing wheel, rubberizing wheel and rubberizing wheel, and correctly adjust the height of each wheel;
(2) The tolerance of each rubber wheel before and after the double rubber pot should not be too large.
Publishing units and printing enterprises should further improve their understanding of product quality, strictly implement standards and norms, strengthen personnel technical training, establish and improve a long-term mechanism for quality management, and effectively improve the ability and level of quality control. All management departments and quality inspection agencies should vigorously promote the implementation of the supervision and promotion solutions, find out the quality problems and communicate with relevant units in a timely manner, and help the analysis, rectification and improvement.