Adjustment and maintenance of offset wetting system
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Ink balance is the key to ensuring print quality, and maintaining the normal operation of the wetting system is an important condition for achieving ink and water balance. Here, the author takes the Heidelberg printing machine as an example, and summarizes the maintenance and maintenance methods of the wetting system to share with you.
Wetting system adjustment
1. Adjustment of water delivery components
The water delivery components of the Heidelberg press consist of a water fountain roller, a metering roller, a water roller, a plate water roller, an intermediate roller and a water bucket.
(1) Preparation before adjustment
Before adjusting the water delivery parts, pay attention to the following points: 1 Select the corresponding standard plate according to the thickness standard of the lining provided by the Heidelberg printing machine manual; 2 when the upper version, the diagonal line is reset to zero to ensure the printing The plate is in a horizontal state; 3 select “Use intermediate roller” on the main console; 4 When adjusting the water roller and the plate roller, the plate upshift should be aligned with the delivery direction to ensure the plate roller and the plate ink. When the roller is falling, it can be in contact with the printing plate; 5Adjust the ink roller and then adjust the intermediate roller to make it contact with the plate roller and the plate water roller, and evenly on the plate water roller and the plate roller. Apply white ink; 6 adjust the pressure between the water rollers, preferably by looking at the width of the indentation bar between the water rollers to adjust the pressure, with little or no feeler gauge.
(2) Adjustment criteria
When adjusting the water delivery parts, the adjustment methods and adjustment order provided in the instruction manual of the model to be operated should be performed. Taking the Heidelberg printing machine as an example, depending on the printing material, the adjustment standard can be floated within a certain range: 1 the width of the indentation bar between the plate water roller and the water roller is 6 to 7 mm; The width of the indentation bar between the plate and the printing plate is 4 to 5 mm; the width of the indentation bar between the plate water roller and the metering roller is 5 to 6 mm; 4 the indentation between the first plate roller and the intermediate roller The width of the bar is 3 to 4 mm, and the width of the indentation bar between the intermediate roller and the water-repellent roller is 2.5 to 3.5 mm.
The order of adjustment of the pressure of the water delivery component is as follows: 1 the pressure of the plate water roller and the water roller; 2 the pressure of the plate water roller and the printing plate; 3 the pressure of the metering roller and the plate water roller; 4 the metering roller and the water bucket The pressure of the roller.
(3) Adjusted inspection method
First, at the main console, the plate will be pressed against the plate roller and the plate water roller. Then, the speed of the water fountain roller is set at the main control station to uniformly inject the ink in the axial direction of the printing plate. After the printing machine runs at a constant speed, gradually increase the speed of the water fountain roller to make the blank portion of the printing plate clean. If the printing plate is clean when the blank portion of the axial direction is different, the pressure of the metering roller and the water fountain roller can be adjusted by adjusting the adjusting bolt of the metering roller, so that the blank portions on both sides are simultaneously cleaned.
2. Control of dampening solution
Practice has shown that the fountain solution is suitable for printing when it satisfies the following conditions: 1 surface tension is 35-42 mN/m; 2 pH is 4.5-5.5; 3 water hardness is 5-7.5. Through experiments, it can be better to achieve the above conditions by controlling the following indicators: 1 to make the dampening solution alcohol concentration 8% to 12%; 2 the winter dampening solution temperature should be controlled at 10 ° C, and the summer should be controlled at 8 ° C; Make the conductivity of the dampening solution 1600±200μS/cm; 4 ensure the concentration of the dampening solution is 2%.
Maintenance of the wetting system
The equipment is three-point maintenance using seven points. In daily production, the maintenance of the wetting system cannot be ignored. Specifically, the operator should do the following:
1 Timing, quantitative filling lubricant in the lubrication part of the water delivery parts;
2 cleaning the water bucket roller with water from the water roller every day;
3 cleaning the filter screen according to water quality;
4 Wash the water and ink roller with calcium remover every week to prevent crystallization;
5Measure the pH value and conductivity value of the dampening solution every day, and record it, and change the dampening solution according to the measured data;
6 according to the water quality and For workload, clean the wetting system with a dampening solution circulating cleaning agent.
Operators should develop good habits, standardize operations, and speak with data. Only when the equipment is in the best condition can the printing preparation time be shortened, the production efficiency can be improved, and the product quality can be guaranteed.