Flexo Printing 1000 Questions (121-130)

121 Why does the ink roller and anilox roller have special transmission methods?

With its own independent motor-driven fountain roller and anilox roller flexo unit, the ink supply system drive should meet the two special requirements of water-based ink: First, when the printing unit is in normal working condition, ink fountain glue The roller and the anilox roller are driven by the main drive system of the machine to rotate synchronously with the machine. At this moment, the anilox roller motor stops rotating. Second, when the machine stops temporarily, even if it is "emergency stop", as long as the power is not cut off, the net Roller motor also drives the anilox roller and ink fountain roller separately at low speed to ensure that the ink on the anilox roller surface and the doctor blade will not dry.

122 Ink roller used to pay attention to what?

The ink fountain roller is driven by the gears of the anilox roller. It shoulders two tasks: it is necessary to bring the ink in the ink fountain to the anilox roller, and under the effect of the ink transfer pressure, the excess ink is squeezed out. ". As mentioned before, no matter if the flexo printer is in the printing working state, as long as the ink fountain is filled with a certain amount of ink, the ink fountain roller and the anilox roller should be constantly rotating. It is worth noting that if there is no ink between the ink fountain roller and the anilox roller, they should absolutely prevent them from rotating in surface contact. This is because the surface line speed of the ink fountain rubber roller is lower than that of the anilox roller. "Dry grinding" will damage the surface of the ink fountain roller in a very short time.

What is the role of 123 squeegee?

In general, as long as the use of laser engraving ceramic anilox roller, it should be used in conjunction with the squeegee, when the transfer pressure is smaller to ensure that there is enough ink is evenly brought to the surface of the anilox roller, and then in the scraping ink Under the action of the knife, excess ink is scraped off, leaving a uniform layer of ink on the surface of the anilox roller. The squeegee is therefore an integral part of the anilox roller quantitative ink delivery system.

124 Squeegee structure is divided into several categories?

The structure of the squeegee can be divided into two types: positive and reverse squeegees. If it is in accordance with the assembly, it can be divided into two kinds of insert scraper and closed scraper.

125 What is a positive scraper type scraping mechanism?

Along the direction of rotation of the anilox roller, a scraper is added to the surface of the anilox roller, and the structure of scraping off excess ink on the surface of the anilox roller is called forward scraper type. According to the relevant information, the positive scraper will be affected by the speed of the machine to change the amount of ink transferred.

126 what is the reverse scraper type scraping mechanism?

Against the rotation direction of the anilox roller, a scraper is added to the surface of the anilox roller, and the structure of scraping the excess ink on the surface of the anilox roller is called a reverse scraper type. With a reverse squeegee, the amount of ink transferred will not change as the speed of the machine changes. Therefore, scraping ink with a reverse doctor blade is an ideal way of scraping ink in flexographic printing. The installation angle of the reverse scraper is generally: 30° to 40° with the tangent of the anilox roll.

127 What are the characteristics of plug-in blade scraping mechanism?

The insertion type squeegee is easy to assemble and disassemble, and the pressure adjustment is simpler than the closed type. However, when the machine is increased to a certain speed, the water-based ink foaming will cause the ink to overflow from the ink fountain and restrict the improvement of printing speed.

128 what is the closed blade scraping mechanism?

The closed squeegee system consists of a forward squeegee and a reverse squeegee. The positive squeegee mainly acts as a seal, and the reverse squeegee acts as a squeegee. The ink transferred to the anilox roller forms a certain pressure in the double blade chamber and is recycled. It eliminates the “flickering” phenomenon during high-speed operation. The solvent in the aqueous ink is also not easily volatilized, and the ink can be kept clean, such as Can be equipped with circulation ink pump, but also greatly improve the printing speed of the flexo press. This type of squeegee eliminates the need to adjust the angle and position of the squeegee. It only needs to be positioned once and the squeegee can be quickly installed later. Almost all modern flexo presses can install this closed squeegee.

129 flexographic unit how to achieve left and right registration?

The structure of the left and right register mechanism is relatively simple, and its basic requirement is to move the plate cylinder in the axial direction of the drum, which is generally realized by using the threads in the mandrel of the plate cylinder. Rotating the handle of the mandrel by hand can drive the mandrel to rotate, but since the mandrel cannot move axially during use, it drives the plate cylinder to move axially through the connection with the roller bearing.

130 flexographic unit how to achieve world registration?

The simplest method for registering heaven and earth is to swing the paper guide roller mounted on the swing arm by turning the hand wheel, thereby changing the length of the paper path between two adjacent printing units so as to achieve the purpose of registration. Using this method for register adjustment, the accuracy is low, and the reject rate is high, which is not suitable for printing screen printing parts and has gradually been eliminated.

Another method is to use a gear box consisting of three shafts and two pairs of helical gears mounted on the shaft. A manual adjustment shaft is installed between the two wall plates of the flexographic printing machine, one end of which passes through the operation side wall plate, the outside is equipped with a hand wheel, and the other end passes through the transmission side wall plate through the toothed belt and the gear box. A shaft is connected. Turn the hand wheel to drive a pair of helical gears in the gear box and simultaneously drive the coaxial helical gears of the driven gear in the pair of helical gears to rotate the other pair of helical gears in the gear box, thereby driving the impression drum to rotate. With this adjustment method, the registration accuracy is higher than that of the former method. As long as the gear ratio of the gear is appropriate, it can be used for printing net print parts. However, its adjustment range is limited by the width of the gears and cannot achieve a print register adjustment within 360°.

The mechanism that can be used for printing register adjustment in the 360° range consists of a small motor and a compound gearbox. The gear box is a composite of the power transmission section and the registration section. On the one hand, this gearbox transmits power to the individual printing units via the main drive shaft. On the other hand, the other part of the gearbox can be driven by a small motor to execute the "registration" command. When the main drive shaft rotates, the register part does not turn, the gear box only transmits power; the main drive shaft does not turn, and the small motor drives the register part, the impression cylinder rotates slowly, so that the adjacent printing unit does not change the phase When the main drive shaft of the flexo press rotates, pressing the button can also enable the small motor to drive the register portion and superimpose the two motions so that the print register can be executed when it is turned on. Therefore, it can achieve print register adjustment within 360°. The German-imported gearboxes are installed on flexographic printing machines imported from the United States, Britain, Switzerland, and other countries, as well as on flexographic equipment produced by Shanghai Ziguang Machinery Co., Ltd.

Shanghai Ziguang Machinery Co., Ltd. Shi Jianping