Analysis of the causes of the back-field glue and dirty glue of the wireless adhesive book
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The binding process is a paperback book processing method that uses adhesive as a connecting material to join the signatures and make them into a book. The adhesive used is hot melt adhesive, which is a 100% meltable polymer solid. When heating and melting to a certain temperature (generally 160 ° C ~ 180 ° C), to achieve the required fluidity and adhesion, the glue is applied by a glue wheel to a certain thickness of the glue layer, the length of the glue, the correct starting position On the back of the book that has been milled back, it is bonded to the cover, and the binding process is completed after the molding.
Since the wireless binding is “sticky” and “scheduled”, the materials to be ordered are different types of adhesives, and the various parts of the book are in operation and hand-over in the production, especially in the forming mechanism, the book conveying belt, and the turning conveyor chain. In some places, adhesives will inevitably stick. When the books are run and transported to these parts, the adhesive adhered to them will be transferred to the back or cover of the book to form wild rubber and dirty glue, which will affect the appearance of the book. This causes the cover to be stuck and the back of the book to be uneven. This phenomenon has become a problem that affects the quality of the frame. Investigating its causes, we believe that there are mainly the following aspects.
1. Improper operation adjustment
1 The amount of glue is too much, the length of the glue is not suitable for the starting position of the glue, and the excess glue is squeezed to the ends of the book during the clamping. Some of them stick to the forming mechanism, and some are transferred to the output with the book. On the conveyor belt, a cycle of wild rubber and dirty glue is formed.
2 The temperature control inside the rubber pot is too high, causing the viscosity of the glue to decrease, the fluidity to increase, and delaying the cooling film deposition time of the hot melt adhesive.
3 The glue remaining on the tray forming mechanism, the book delivery belt, and the reverse conveying chain plate was not removed in time.
4 machine speed control (too fast) is not compatible with the hot melt adhesive solidification drying time.
2. Causes of process management
1 The size of the book paper is not compatible with the size of the cover paper. It is generally characterized by a long book block and a short cover. The short end of the cover is glued to the forming mechanism, and the book is attached after the book is opened. Attached to the surface of the conveyor belt and to the book guide.
2 The selection of hot melt adhesive models and technical indicators (mainly time parameters and viscosity indicators) are not compatible with the type and product structure of the binding equipment used.
3 equipment maintenance, adjustment is not in place, the movement position and accuracy of each component does not meet the requirements.
3, hot melt adhesive itself has problems
1 The hot melt adhesives with the same model and different batch numbers have inconsistent technical performance, and sometimes even have large differences.
2 The viscosity index is too high, resulting in poor fluidity and permeability. It is drawn and dragged when applied to the back of the book.
3 The curing and drying time is too slow, and the adhesive cannot be solidified in time after clamping and setting.
The main reason for the book back wild glue and dirty glue is nothing more than the above. How to overcome and reduce this phenomenon in the whole process of product production, let's talk about some experiences.
1 Firstly, according to the production efficiency of different binding equipment (normal operation speed and the time required for the hot melt adhesive to be applied to the back of the book to run on the backing forming mechanism, the general medium speed machine is 4 to 6 seconds; the low speed machine is 3 to 5 seconds). Product structure, ambient temperature, correct purchase of hot melt adhesives with various technical indicators meeting the requirements, especially when selecting suppliers, priority should be given to manufacturers with strong strength, stable product quality, and reputable, and control the incoming inspection. If there should be product certification, technical parameters, instructions for use and other information.
2 In the operation, the technical performance of different types of hot melt adhesives should be strictly controlled. All kinds of adhesives should be sorted and stacked and marked. When using, it is necessary to select suitable hot melt adhesives according to different binding equipments and different products. Glue is used in combination.
3 In the production, attention should be paid to controlling the temperature of the glue. According to the product paper condition, book thickness and ambient temperature, the coating temperature or the machine speed can be appropriately reduced within the allowable range. Because most of the current glue binding machine temperature display values and the actual glue temperature in the plastic pot have errors (less 20 ° C, more 70 ~ 80 ° C), so can not be based on the meter display value, can only be used as a reference, should Re-purchase the temperature measurement meter with a range of up to 300 °C into the plastic pot to monitor the actual temperature of the glue to keep the temperature stable.
4 Control the coating amount of the glue layer, the length of the glue, and the starting position of the glue (can be achieved by adjusting the scraper plate, the rubber wheel on the back of the book, the rubber wheel, and the rubber working face of the rubber). The distance between the rubber wheel and the back of the book is generally Between 2mm ± 0.5, the length of the glue is about 5mm shorter than the cover).
5 promptly remove the molding mechanism, the book delivery belt and the excess glue on the reverse conveying plate. For easy removal, apply a little silicone oil to these areas. Do diligent, clean, and diligent adjustment.
6 In the process planning, try to make the length of the cover larger than the length of the book block or book block and the length of the cover. This is a difficult and important part. It involves paper size, publishing house, customers, and various departments of the factory. Negotiate and resolve.
7 Install an air-cooling device (in the form of a wind pump, air compressor, blowing pipe, fan, etc.) from the supporting forming mechanism to the opening and closing part of the book, so that the excess glue extruded on the back of the book quickly cools the conjunctiva.
8 Strengthen the maintenance work of the binding machine. Because the book holder, the brushing mechanism, the cover conveying positioning, and the supporting forming mechanism are mostly chain-driven, the chain and the sprocket will wear after running for a period of time, thus affecting the transmission accuracy. These parts should be regularly inspected, maintained, adjusted, and compensated to maintain their transmission accuracy.
Finally, there is a point that after the actual production of hot melt adhesives meets the requirements, it is best not to change them frequently. In short, there are many factors that produce wild rubber and dirty glue in production. Some problems are not easy to solve. When this happens, it may be necessary to analyze and find out the above reasons and take active measures to solve them.