![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
Paper, cellophane, plastic film, and aluminum foil used in the packaging of foods, medicines, clothing, clothes, cigarettes, etc., are often printed on a gravure web printer due to their own characteristics. In recent years, due to the diversification of printing and the high speed of printing, particularly the requirements for the dimensional accuracy of the next process equipment, as well as the saving of materials and the improvement of the yield. Tension control methods are widely used. At present, the use of tension control in foreign countries has become mature and its use is very common.
Now try to analyze the tension control principle and characteristics.
First, the characteristics of gravure printing At present, the printing main application of the layout are relief, lithography and gravure three, gravure is characterized by graphics and some concave, the layout of all immersed in the ink plate, and then use the scraper to scrape excess ink, will residue The method of transferring the ink in the concave portion to the printed object is gravure printing.
The main features of gravure printing are:
The ink accumulated in the concave portion of the layout can transfer sufficient ink to obtain a layered print. The shade of the print is expressed by the depth of the print, so the print has a three-dimensional effect, and the fine lines can be printed clearly and freely and widely. Select and use various media.
Second, on the tension control of gravure Before describing this issue, we should understand what tension control is.
At present, the gravure printing machine used needs two main parts that apply the tension control principle:
The first part is from the feed to the feed roll. Overprinting error, that is, overprinting accuracy between colors of multi-color printing. If the position relationship of the printing press mechanism is correct and the error is caused by the elongation or shortening of the material, a certain amount of elongation is controlled within the allowable range, and the tension control is the most effective.
The second part is from the receiving traction roller to the receiving part, should pay attention to the receiving material tension, neat, reliable and other factors tension control.
The tension control method from the feed shaft to the feed pull roller will be described in detail below.
Due to the action of the pulling roller, the printing material is pulled out of the feeding shaft at a certain speed and tension and sent to the printing section. The tension of this part is greater than the tension of the printing section. The tension is usually controlled by a brake attached to the feeding shaft. . As we all know, the winding diameter of the work gradually becomes smaller. In recent years, due to the increase in speed and the use of diversified materials, the coil diameter has changed greatly. Therefore, manual mechanical brakes used in the past have not been able to obtain high-quality prints. Therefore, the use of automatic control methods, especially the use of tension measurement data management becomes a necessary practice. Its detection methods are spring-rolled roller type and micro-displacement type detection. Mechanical brakes have been used since very early and are cheap, but the torque value is inaccurate. So gradually there are other forms. Magnetic powder brakes use magnetic powder as a friction medium to generate braking force by current, because of its good linearity in torque-current characteristics. So it is widely used. Pneumatic brakes, although some printing machines are used in large quantities, are due to the non-linear torque characteristics and the large wear factor. Also gradually replaced by large-capacity magnetic powder brakes.
In addition to the tension control of the feed, the tension of the feed is determined by the following factors:
Tensile change due to uneven thickness;
The slippage and even slippage of the material slow down;
Roll is not installed, material and shaft eccentric;
The change in the peripheral speed of the turning device during rotation;
The reaction force of the pressure roller and cutter when the paper is connected;
The roundness of each roller is not enough.
Most of these changes took place within a short period of time and were transmitted to the printing department as tension changes. From the mechanical structure point of view, it must be noted that the inertia of the guide roller and the manufacturing error between the feed shaft and the traction roller are the causes of the increase in tension, and in particular, the low tension of several kilograms or less must not be ignored.
Speak about the change and control of the tension between the traction roller and the plate roller (traction part).
In the gravure printing machine, the traction roller is usually provided with a peripheral speed synchronization mechanism adjacent to the first roller. This is different from the feed situation, the diameter does not change, so use other principles to control the tension.
The printed material has the same elasticity and plasticity as a general object, and the printing process is performed within the elastic limit. Therefore, the tension must be controlled according to the law of elasticity. This is to understand the characteristics of different materials.
In order to obtain the same elongation in use, the tension can be determined by various ratios of the width and thickness of the material.
There are two ways to get the proper tension:
1 Make the diameter of the pressure roller slightly change;
2 Correct the number of rotations of the pressure roller. (To be continued)
Now try to analyze the tension control principle and characteristics.
First, the characteristics of gravure printing At present, the printing main application of the layout are relief, lithography and gravure three, gravure is characterized by graphics and some concave, the layout of all immersed in the ink plate, and then use the scraper to scrape excess ink, will residue The method of transferring the ink in the concave portion to the printed object is gravure printing.
The main features of gravure printing are:
The ink accumulated in the concave portion of the layout can transfer sufficient ink to obtain a layered print. The shade of the print is expressed by the depth of the print, so the print has a three-dimensional effect, and the fine lines can be printed clearly and freely and widely. Select and use various media.
Second, on the tension control of gravure Before describing this issue, we should understand what tension control is.
At present, the gravure printing machine used needs two main parts that apply the tension control principle:
The first part is from the feed to the feed roll. Overprinting error, that is, overprinting accuracy between colors of multi-color printing. If the position relationship of the printing press mechanism is correct and the error is caused by the elongation or shortening of the material, a certain amount of elongation is controlled within the allowable range, and the tension control is the most effective.
The second part is from the receiving traction roller to the receiving part, should pay attention to the receiving material tension, neat, reliable and other factors tension control.
The tension control method from the feed shaft to the feed pull roller will be described in detail below.
Due to the action of the pulling roller, the printing material is pulled out of the feeding shaft at a certain speed and tension and sent to the printing section. The tension of this part is greater than the tension of the printing section. The tension is usually controlled by a brake attached to the feeding shaft. . As we all know, the winding diameter of the work gradually becomes smaller. In recent years, due to the increase in speed and the use of diversified materials, the coil diameter has changed greatly. Therefore, manual mechanical brakes used in the past have not been able to obtain high-quality prints. Therefore, the use of automatic control methods, especially the use of tension measurement data management becomes a necessary practice. Its detection methods are spring-rolled roller type and micro-displacement type detection. Mechanical brakes have been used since very early and are cheap, but the torque value is inaccurate. So gradually there are other forms. Magnetic powder brakes use magnetic powder as a friction medium to generate braking force by current, because of its good linearity in torque-current characteristics. So it is widely used. Pneumatic brakes, although some printing machines are used in large quantities, are due to the non-linear torque characteristics and the large wear factor. Also gradually replaced by large-capacity magnetic powder brakes.
In addition to the tension control of the feed, the tension of the feed is determined by the following factors:
Tensile change due to uneven thickness;
The slippage and even slippage of the material slow down;
Roll is not installed, material and shaft eccentric;
The change in the peripheral speed of the turning device during rotation;
The reaction force of the pressure roller and cutter when the paper is connected;
The roundness of each roller is not enough.
Most of these changes took place within a short period of time and were transmitted to the printing department as tension changes. From the mechanical structure point of view, it must be noted that the inertia of the guide roller and the manufacturing error between the feed shaft and the traction roller are the causes of the increase in tension, and in particular, the low tension of several kilograms or less must not be ignored.
Speak about the change and control of the tension between the traction roller and the plate roller (traction part).
In the gravure printing machine, the traction roller is usually provided with a peripheral speed synchronization mechanism adjacent to the first roller. This is different from the feed situation, the diameter does not change, so use other principles to control the tension.
The printed material has the same elasticity and plasticity as a general object, and the printing process is performed within the elastic limit. Therefore, the tension must be controlled according to the law of elasticity. This is to understand the characteristics of different materials.
In order to obtain the same elongation in use, the tension can be determined by various ratios of the width and thickness of the material.
There are two ways to get the proper tension:
1 Make the diameter of the pressure roller slightly change;
2 Correct the number of rotations of the pressure roller. (To be continued)