Causes and prevention of paper breakage in the hot

2022-08-23
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Causes and prevention of paper breaking in rotary printing

for rotary printing machine, it is a very thorny problem that the printing process is interrupted and the paper stops or the equipment fails. According to the working experience in recent years, the author summarizes and analyzes the causes and preventive measures, and discusses them with colleagues here

1. The harm of paper breakage in rotary printing

most of the rotary printing products are products with large printing batches. The printing speed is fast, and the paper bears a large tension in the printing process. After printing, the paper must be folded. The paper must maintain a certain paper tension in the whole paper feeding process to meet the needs of rotary printing. There are many factors that affect the paper tension in the printing process. The faster the printing speed is, the greater the tension is, and the higher the probability of paper breaking. Whether it is a manual or automatic threading machine, it takes 10 to 20 minutes to re thread the paper after the paper is broken to start printing. It not only increases the labor intensity, wastes paper, and affects the printing speed and quality stability. If the broken paper causes equipment failure, damages mechanical parts, and crushes the blanket, it also needs to stop for maintenance, making it difficult to guarantee the timeliness of newspaper printing requirements. Therefore, the problem of paper breaking is currently well realized by the use of brain computer interface technology in the human brain. The successful grasp of a specific object (such as a paper cup and a ball) under the control of mind must be paid full attention to and the occurrence of paper breaking should be avoided as far as possible

2. Analysis of the causes of paper breakage in rotary printing

(1) web quality problems and improper handling

when the printing paper belt is normal, the whole paper path should be relatively stable, the paper surface tension distribution is relatively uniform, and the small fluctuation of the paper can be controlled within a certain range through the tension control system. If the quality of the web does not meet the requirements, such as inconsistent tightness, uneven paper thickness or improper transportation, resulting in Web deformation and paper core offset. During the printing process, due to the inconsistent radial size of the web, the paper tape will jump violently in high-speed printing. When the floating roller is difficult to adjust the tension to the normal printing range, it is easy to cause paper breakage. Therefore, when choosing web paper suppliers, we must choose manufacturers with high reputation and stable quality. Although the paper price of small factories is cheap, if it causes paper breakage, the gain is not worth the loss

(2) the starting speed is unstable

when starting up, the printing speed is fast or slow, which will inevitably cause the force on the paper tape to be large or small, greatly weakening the adjustment effect of the tension balance system, and easy to break the paper. Therefore, when starting the machine, it should be accelerated smoothly from slow to fast

(3) excessive dust accumulation on the paper guide roller

ink scale and dust accumulation cause the radial size of the paper guide roller to increase. The establishment of macro-control and market conditioning mechanism is large. Without changing the set tension, the actual tension of the paper belt will increase, and the paper tension distribution is uneven, which is very easy to cause paper breakage. During the routine maintenance of the equipment, the paper guide roller should be cleaned regularly

(4) improper operation

in the printing process, there are many factors that affect the paper strength. For example, in printing, the adhesion of rubber blanket to paper, the peeling force of ink to paper and the wetting of fountain solution to paper will reduce the surface strength of paper to varying degrees. When the influencing factors exceed the adjustment range of tension control system, it is easy to break paper. For example, when the machine is stopped to replace the printing plate, the condensed water droplets on the machine baffle are not cleaned, and the excessive accumulation of water droplets will flow to the printing plate cylinder. When the machine is started to print, the water droplets are transferred from the cylinder to the paper, and the local water absorption of the paper is too much, which greatly reduces the mechanical strength of the paper and is easy to cause paper breakage

(5) aging of rubber blanket

the surface of rubber blanket is prone to aging, expansion, bulge cracks and other problems due to the erosion of ink fountain solution and paper residues during long-term imprinting, which reduces the ink transfer performance of rubber blanket. In particular, cracks and bulges appear on the edge of the blanket, and the paper is impacted by the pressure of the blanket during the stamping, which greatly reduces the tension of the paper and is easy to cause paper breakage. The blanket should be changed regularly according to the printing volume

(6) environment in addition, the influence of temperature and ink viscosity

the influence of workshop ambient temperature or other factors may increase the viscosity of ink. The adhesion of paper by ink and blanket increases, and the stripping tension of paper also increases. The faster the printing speed is, the greater the stripping force is. When it exceeds the adjustment range of tension suppression system, it is very easy to cause paper breakage

(7) mechanical failure

some mechanical parts in printing fail. For example, the failure of the tension control mechanism, the failure of the paper breaking mechanism, and the misoperation of the stacker to cut off the paper tape will all cause paper breaks

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