The data measured on the rotogravure machine is mainly taken from the roll holder. The printing effect was also studied in the experiment: the tension curve of 10 rolls was measured simultaneously on a roll holder and after passing through 4 printing devices. As a result, it was found that the tension curve measured on the roll holder was still visible after passing through the four printing devices. This is a noteworthy result because most web breaks on gravure printers occur after the web passes through the printing unit. Figure 3 shows the tension curve measured at the time of web change. It can be seen that the tension curve changes greatly because the paper roll is cut from different machine roll positions. It is not difficult to understand that this change will have an adverse effect on the paper-drawing situation. In this case, a paper break occurred in the tape. It must be noted that the printing press can also have an effect on the tension curve, and it can sometimes have a particularly large effect.
Due to the different position of the reels, the output tape tension is not the same, so some printers only output tape from one reel position at a time.
The actual significance of the tension curve The number of breaks and the percentage of waste paper calculated using different methods directly affect the quality of the print job. In the course of this study, the on-line measurement of the rotogravure machine was performed using an IQTension tension measuring device mounted on a roll holder. The roll width is between 98 and 245 centimeters, and the weight of paper is 49 to 90 grams per square meter. The number of web breaks and the amount of waste paper per roll are collected directly from the print production control system. The web break data and tension data were measured cumulatively from 120,000 rolls in 2 years. The waste paper rate data is the measurement result of 3,000 paper rolls.
The main operational problems encountered on printing presses are web breaks and registration errors, which increase the amount of waste paper and reduce the productivity. Most web breaks occur after passing through the printing device when the web is cut into narrow strips. At that time, the statistical analysis was conducted on the relationship between the actual operation status and the tension curve. Different parameters were calculated based on the tension curve of each roll. The most important data is the maximum, minimum, average, and tilt of the tension curve.
Figure 4 (slightly) Chinese paper rolls are divided into groups according to key data. Each column of data shows the break rate for each group of rolls. The rate of web break in the lowest portion of the tension is caused by the wrinkling and instability of the web, especially when the slack portion of the web becomes a narrow, loose web before the folder. If the tension is too high, paper breaks may occur (this may be due to the limited roll paper strength). If there are some defects in the web itself, paper breaks tend to occur. The inclination of the tension curve has a certain influence on the web break rate. The reason may be that the state of the web passing through the printing press is unstable. The optimal average tension value can be found; in this case the optimal average tension value is 300 Newtons per meter (N/m).
Figure 5 shows the effect of different parameters on the waste paper rate. Paper rolls that have experienced breaks in the production process are not included in the statistics because most of the waste paper was produced at the beginning of the run. The number of counted paper rolls is about 3,000. It can be seen that the loose part of the web, or the part where the force curve of the web greatly changes, tends to further increase the waste paper rate. This is caused by the unstable state of the web.
In the course of this study, different paper manufacturers were compared and analyzed. As a result, it was found that the advanced calendered paper with a large change in the tension curve has a higher rate of paper breakage and paper waste. The magnitude of change in the tension curve is measured at the upper layer of the paper roll and near the middle layer.
The tension and slack of the web, as well as the tilt of the force curve of the web, will affect the operation of the press. Therefore, the optimal tension curve has a slight inclination.
The results of the measurements on the rotogravure machine and related experience The results presented in this paper were obtained on a rotogravure machine by measuring over 20,000 rolls of paper roll. The operator can empirically predict the web break and possible alignment problems based on the roll force curve. This means that they can reject web rolls with poor tension profiles and web breaks. Previously, in the absence of a chance to obtain tension curve data, they rejected paper rolls with two or three broken sheets. The tension curve data also helps the operator to identify other causes that affect the job. If the tension curve is good, but there are still many problems, operators can focus on the press to find the cause of the problem.
The tension curve cannot be controlled on the press and can only be adjusted with a certain amount of tension. Sometimes tension changes have a positive effect on the accuracy of registration, but adjusting the tension does not completely eliminate the registration error.
One of the most important effects of tension measurement is that the print operator starts to print jobs from only one reel position at a time; the reason is that the reel spool position is different, and the reel power curve is also inconsistent. This avoids sudden changes in the tension curve.
Thanks to the sober understanding of the tension curve, the operating method was improved and the paper rolls were grouped more effectively. The web break rate at the final replacement of the paper roll was reduced by 50%.
Conclusions and Future Measures It is generally believed that the phenomenon of web breaks in printing plants is often caused by factors such as poor roll paper strength, poor quality of its own, damage during transportation, malfunction of printing presses, and improper human handling. We believe that the tension curve also has a certain influence on web breaks. Studies have found that excessively tight or too loose parts of the paper roll cause both the number of breaks and waste paper problems to increase. The larger local slope of the tension curve is also the cause of the problem. The slackening of the slack and the tension curve tends to cause wrinkles in the web and the state is unstable, eventually leading to the occurrence of web breaks.
Roll paper force characteristics are generally brought to the press by the paper mill. That is to say that paper rolls cut from different parts often have different tension curves. In order to not change the tension of the reel when the paper roll is changed, different parts should be printed in order. One of the roving gravure printers in the research team began grouping the paper rolls into groups according to the location of the cut paper. As a result, the web break rate decreased by 50%.
A research project called "The interaction of paper and printing presses" was subsequently launched. The participants in this research project included printer manufacturers, paper machine manufacturers, paper manufacturers, and printers. The goal was to finalize important printer variables and roll paper parameters related to improving the quality of press operations. (Finish)
Due to the different position of the reels, the output tape tension is not the same, so some printers only output tape from one reel position at a time.
The actual significance of the tension curve The number of breaks and the percentage of waste paper calculated using different methods directly affect the quality of the print job. In the course of this study, the on-line measurement of the rotogravure machine was performed using an IQTension tension measuring device mounted on a roll holder. The roll width is between 98 and 245 centimeters, and the weight of paper is 49 to 90 grams per square meter. The number of web breaks and the amount of waste paper per roll are collected directly from the print production control system. The web break data and tension data were measured cumulatively from 120,000 rolls in 2 years. The waste paper rate data is the measurement result of 3,000 paper rolls.
The main operational problems encountered on printing presses are web breaks and registration errors, which increase the amount of waste paper and reduce the productivity. Most web breaks occur after passing through the printing device when the web is cut into narrow strips. At that time, the statistical analysis was conducted on the relationship between the actual operation status and the tension curve. Different parameters were calculated based on the tension curve of each roll. The most important data is the maximum, minimum, average, and tilt of the tension curve.
Figure 4 (slightly) Chinese paper rolls are divided into groups according to key data. Each column of data shows the break rate for each group of rolls. The rate of web break in the lowest portion of the tension is caused by the wrinkling and instability of the web, especially when the slack portion of the web becomes a narrow, loose web before the folder. If the tension is too high, paper breaks may occur (this may be due to the limited roll paper strength). If there are some defects in the web itself, paper breaks tend to occur. The inclination of the tension curve has a certain influence on the web break rate. The reason may be that the state of the web passing through the printing press is unstable. The optimal average tension value can be found; in this case the optimal average tension value is 300 Newtons per meter (N/m).
Figure 5 shows the effect of different parameters on the waste paper rate. Paper rolls that have experienced breaks in the production process are not included in the statistics because most of the waste paper was produced at the beginning of the run. The number of counted paper rolls is about 3,000. It can be seen that the loose part of the web, or the part where the force curve of the web greatly changes, tends to further increase the waste paper rate. This is caused by the unstable state of the web.
In the course of this study, different paper manufacturers were compared and analyzed. As a result, it was found that the advanced calendered paper with a large change in the tension curve has a higher rate of paper breakage and paper waste. The magnitude of change in the tension curve is measured at the upper layer of the paper roll and near the middle layer.
The tension and slack of the web, as well as the tilt of the force curve of the web, will affect the operation of the press. Therefore, the optimal tension curve has a slight inclination.
The results of the measurements on the rotogravure machine and related experience The results presented in this paper were obtained on a rotogravure machine by measuring over 20,000 rolls of paper roll. The operator can empirically predict the web break and possible alignment problems based on the roll force curve. This means that they can reject web rolls with poor tension profiles and web breaks. Previously, in the absence of a chance to obtain tension curve data, they rejected paper rolls with two or three broken sheets. The tension curve data also helps the operator to identify other causes that affect the job. If the tension curve is good, but there are still many problems, operators can focus on the press to find the cause of the problem.
The tension curve cannot be controlled on the press and can only be adjusted with a certain amount of tension. Sometimes tension changes have a positive effect on the accuracy of registration, but adjusting the tension does not completely eliminate the registration error.
One of the most important effects of tension measurement is that the print operator starts to print jobs from only one reel position at a time; the reason is that the reel spool position is different, and the reel power curve is also inconsistent. This avoids sudden changes in the tension curve.
Thanks to the sober understanding of the tension curve, the operating method was improved and the paper rolls were grouped more effectively. The web break rate at the final replacement of the paper roll was reduced by 50%.
Conclusions and Future Measures It is generally believed that the phenomenon of web breaks in printing plants is often caused by factors such as poor roll paper strength, poor quality of its own, damage during transportation, malfunction of printing presses, and improper human handling. We believe that the tension curve also has a certain influence on web breaks. Studies have found that excessively tight or too loose parts of the paper roll cause both the number of breaks and waste paper problems to increase. The larger local slope of the tension curve is also the cause of the problem. The slackening of the slack and the tension curve tends to cause wrinkles in the web and the state is unstable, eventually leading to the occurrence of web breaks.
Roll paper force characteristics are generally brought to the press by the paper mill. That is to say that paper rolls cut from different parts often have different tension curves. In order to not change the tension of the reel when the paper roll is changed, different parts should be printed in order. One of the roving gravure printers in the research team began grouping the paper rolls into groups according to the location of the cut paper. As a result, the web break rate decreased by 50%.
A research project called "The interaction of paper and printing presses" was subsequently launched. The participants in this research project included printer manufacturers, paper machine manufacturers, paper manufacturers, and printers. The goal was to finalize important printer variables and roll paper parameters related to improving the quality of press operations. (Finish)
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