The quality of offset products in the printing process is inseparable from whether the ink and water maintain a certain balance. How should the water supply device be adjusted during the offset printing process?
In order to adapt the water supply of the water delivery mechanism to the requirements of printing production, the water delivery mechanism is provided with a device for controlling moisture and adjusting the amount of water. This can be divided into three parts according to their working nature: one is the water supply device; the other is the water leveling device; the third is the water supply device.
The water supply device is mainly composed of a water tank, a water bucket roller and a water transfer roller. The water tank is used to store water, and there is a water bucket roller (also called water outlet roller) on the upper part. The lower half of the hopper roller is immersed in the hopper solution, and they do not contact or support each other. In addition to adding water by an automatic water dispenser during operation (many manufacturers have not used it), water can also be added manually. Manual water addition requires the operator to constantly add the previously prepared solution to the water tank.
Since the water supply in the bucket roller is related to the height of the bucket solution, to make the water supply even, the bucket solution in the sink must maintain a certain water level. The operator should not be anxious when adding the water bucket solution, and slowly add the water bucket solution to the water tank, and cannot stir the water tank solution. Like swinging,
First, it causes the local moisture to suddenly increase during normal printing, which affects the quality of the product;
Second, the water bucket solution will sprinkle and drip onto the front gauge part under the sink, causing abnormal paper feeding and clutch pressure (this is because the solution drops onto the electric tooth part of the front gauge, forming conductivity)
Third, it is dropped on the printed product, causing water droplets on the paper, and it is easy to appear double sheets when printing the next color.
The water transfer roller, also known as the draft roller, is a rubber roller that is installed between the water bucket roller and the string water roller and swings back and forth to transfer moisture. Its surface is covered with water roller fleece. The adjustment requirement of the water transfer roller is that it should be parallel to the water bucket roller and have appropriate pressure when draught. It is adjusted by the tension springs on both sides. When adjusting, the tension of the tension spring must be consistent to ensure that the water transfer roller works parallel to the water bucket roller when draught. The water supply depends on the cam, and the adjustment must put the water transfer roller against the string water roller with proper pressure. There are an adjusting screw and a positioning backing on each side below the water roller. The adjustment also requires the water transfer roller and the water string roller to remain parallel.
The water transfer roller also has a draught clutch device. When opening and closing the press, the normal draught feed water swings back and forth through the 0.7V iron suction of 220V. Stop swinging back and forth when the pressure is off, that is, no longer lean on the water outlet roller. The buttons for water supply opening and water supply stop on the operation table are used to control this iron suction, and they work according to the production situation. Sometimes when we print normally, we will find that the moisture on the press surface becomes larger after the pressure is removed. why? This is because after the iron suction stops working, the pulling force of the top claw tension spring beside the iron suction is not enough, which causes the drum to still be draught from the pressure water transfer roller. The strength of the tension spring is not enough, causing the suction iron to retract one or two beats, which is why the moisture on the layout becomes larger. Solving this problem is very easy to do, just change a new tension spring or shorten the old tension spring by one or two knots.
The water leveling device is mainly a string of water rollers. Generally made of corrosion-resistant metal materials. In order to make the water on the water roller even, the water roller not only has rotary motion, but also axial motion. The surface speed of the water roller is equal to the surface speed of the printing plate, so as to keep the plate water roller moving at the same speed. The axial tandem motion of the water string roller is adjusted by an eccentric connecting rod, which is relatively simple and generally does not need to be adjusted during the printing process.
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