KBA Rapida 104 has been used for a period of time, and different degrees of ghosting appear when printing four colors, especially when printing on coated paper under 105g / m2.
Ghosting phenomenon 1: The trailing corners of the trailing edge of the printed sheet cause overprint ghosting. This phenomenon occurs when the device is used for about one and a half years.
Reason analysis: After inspection, it was found that the gripping force of the entire row of impression cylinder gripping teeth was insufficient, and a single gripper was stiff up and down or had become a dead tooth. Upon further inspection, it was found that the contact surface between the gripper copper hoop and the long axis of the open tooth was rusty. The reason for the rust is that when the operator cleans the ink and paper powder on the surface of the impression cylinder, the water in the gasoline enters the dental brace, and it rusts for a long time. Due to insufficient gripping force, paper ejection occurred during the printing process, resulting in flicking and overprinting.
Solution: (1) First loosen the eccentricity of the opening ball, then loosen each brace, remove the rust, apply engine oil, restore each gripper to its original position, and finally adjust the gripping force to be consistent to restore the eccentricity of the opening ball Position to ensure the grip of the entire row of grippers. (2) When cleaning the surface of the impression cylinder, the oil-water mixture should be avoided as much as possible to reduce the possibility of rust.
Treatment result: After finishing the work of cleaning and adjusting the gripper, restart the printing and the ghost phenomenon disappears.
Ghosting phenomenon 2: When facing large-scale printed copies, the two sides of the printed sheet appear from the grip to the trailing edge. This phenomenon occurs 2 to 3 years after the equipment is put into production.
Analysis of the reason: when printing the facing sheet, the gripping teeth of the impression cylinder other than 780mm are temporarily not used. The gripping teeth and the rubber pad of the dental pad are in direct contact for a long time, and the rubber pad will be bitten by the gripper. At this time, the contact ability between these grippers and the dental pad is basically lost. When the printing is far from each other, the gripping force of these grippers on both sides of the printed sheet is almost lost. Coupled with the printing pressure and the effect of viscous ink, the paper backing phenomenon occurs on both sides of the printed sheet, resulting in ghosting.
Solution: Replace the new dental pad. However, each original dental pad is about 400 yuan, the price is more expensive, and sometimes there is no domestic inventory, it needs to be imported from Germany, so it takes less than two weeks, the production loss caused by downtime and other parts is too large, and the domestic parts are wear-resistant Not enough. Later, after research and experiment, we used ordinary 502 glue and domestic suction nozzle apron to make a dental pad that is comparable in function to the original dental pad. Clean the basic surface of the dental pad, cut the apron, polish the contact surface of the apron, use 502 glue to firmly adhere the apron made of the apron to the dental pad, and then polish the pad to level the surface of the impression cylinder, and finally adjust the The gripping force is consistent. It takes only 5 minutes before and after making such a dental pad.
Processing result: restart the printing and the ghost phenomenon disappears.
Ghosting caused by overprinting errors. This phenomenon occurs 3 to 4 years after the equipment is put into production.
Cause analysis: The rubber pad of the middle part of the gripper of the impression cylinder or part of the dental pad is seriously worn, causing a large amount of gripping force to be obviously insufficient, almost losing the gripping force due to it, and a large area of ​​paper removal occurs in the printed sheet, which causes serious overprinting error.
Solution: Same as the solution to the second ghost phenomenon, use 502 glue and apron to repair the dental pad rubber pad. The difference is that this repair has a larger number of dental pads. Finally, the entire row of gripping teeth is adjusted to be consistent .
Processing result: restart the printing and the ghost phenomenon disappears.
Estimation of economic benefits: Workers made for these adjustments and repairs can obtain direct and indirect economic benefits.
Direct economic benefits: If you buy a new dental pad, it is about 400 yuan each, 21 rows in a row, a total of 8 rows, it costs about 70,000 yuan, while a bottle of 502 glue and a dozen aprons only cost a few yuan. Savings of more than 70,000 yuan. Indirect economic benefits: such as 10 days of downtime and other parts, the output of a single shift is 40,000 prints per day, and the output of double shifts is 80,000 prints. Based on 30 yuan per color order, the output value of one day is about 10,000 yuan, and the output value of 10 days is about 100,000. yuan.
The above direct and indirect savings are about 170,000 yuan. This shows that as long as we actively use our brains and dare to innovate and work hard, the economic benefits are considerable, and at the same time we have been tempered and improved.
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