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Super calender is a kind of finishing equipment for papermaking, which belongs to a kind of soft calender. The paper web passes through a number of pressure zones of the paper roll and metal roll on the super calender, and becomes smoother, shiny, tight, flat or transparent under the action of mechanical and thermal forces, preventing and reducing the loss of powder and lint, improving the appearance of the paper web and some of its physical quality indicators.

Although soft roll calender and super soft roll calender have been developed in recent years, their appearance has partially replaced the function of super calender.

However, with the technological progress and structural improvement of the super calender, it is still an irreplaceable and important finishing equipment for the production of high-grade paper.

Technical progress performance:

1) The new paper meal roller and MC nylon roller with long life and meeting the requirements of the use process are adopted.

2) Use floating controllable medium-high rollers or zoned controllable medium-high rollers that can compensate or control medium-high.

3) The chilled cast iron roller adopts the hot roller structure and temperature control technology with through holes or jackets around the roller body.

4) Using quick-release roller and soft landing mechanism, the rollers in the roller group can quickly disengage from each other when the paper is broken, so that the paper meal roller is protected from damage.

5) Equipped with web tension, smoothness, gloss, thickness of the online detector and computer control system.

6) It can smoothly adjust the working speed, and the speed is stable when increasing, decreasing or decelerating. When pressurized, the main drive has small dynamic speed drop, good dynamic response and high static speed stabilization accuracy. The performance of the paper return mechanism and the paper reel follow the main drive is good. When the paper is broken, it can quickly brake the electric drive system of the paper roller and the roller.

7) Using shaft roll paper, the roll diameter of the roll paper can be detected, and the linear speed of the roll paper can be adjusted by calculating the current to make it synchronized with the main drive tracking system.

In order to prevent the paper roll from getting uneven tightness, arching and folding paper diseases and making the diameter of the paper roll larger, a new type of paper rolling technology is used to maintain a constant distance between the riding roller and the paper roll by using a hydraulic level adjustable riding roller and a photoelectric tracking detection device of a sensitive layer detector.

When the riding roller and the paper roll to maintain a constant gap, the paper roll is a "soft roll", when the riding roller and the paper roll to maintain a stable pressure, the paper roll is a "hard roll", that is, to maintain a constant surface coiling pressure.

8) The use of automatic replacement paper roll and automatic replacement of roll paper roll paper and roll paper device, improve operating conditions and greatly improve the efficiency of the operation.

9) There is a roller weight balancing device in the middle roller depth, so that there is the same or different line pressure between each pressing area, so as to improve the finishing effect on both sides of the paper web.

Super calender can usually be divided into two categories:

1. For writing paper, printing paper, coated paper and other cultural paper and coated paper, it is characterized by high requirements for gloss and smoothness, wide door width, high speed, relatively low line pressure and low temperature of hot roller.

2. For industrial paper such as capacitor paper, cigarette paper, imitation parchment paper, etc., it is characterized by narrow door, low speed and high line pressure.

The metal rollers and paper meal rollers of the super calender are arranged on both sides and one side according to the paper requirements. The smoothness and gloss of the side of the paper web in contact with the metal roll are higher than the side in contact with the paper meal roll.

In the super calender for pressing two-sided glossy paper webs, the number of paper meal rollers should make both sides of the paper have the opportunity to contact with metal rollers. The top and bottom rollers of the roller group are usually metal rollers. Except for two paper meal rollers contacting each other, the rest are alternately arranged by paper meal rollers and metal rollers.

Therefore, the rolls of such supercalenders are all even-numbered rolls. The supercalender for single-sided coated paper and single-sided glossy paper has an odd number of rollers.

Except for the top and bottom rolls of metal, the rest are paper rolls and metal rolls alternately arranged.

The smoothness difference between the two sides of the paper can be adjusted by adjusting the line pressure of the intermediate roller pressure relief device.

The main mechanism of the super calender is composed of a paper return frame, a paper reel and a main frame with a roller group.

Roller set: paper meal roller, controllable middle and high roller as top roller and bottom roller and metal roller that can be heated or cooled. The rolling surface width of metal roller must be larger than that of paper meal roller.

The temperature of the paper web is an important factor in plasticizing the paper web and achieving a better calendering effect.

Generally, the roller in the metal is used as a hot roller, and hot water, steam or other heating media are introduced into the roller barrel to increase the paper temperature. Sometimes cold water is also introduced into the roller in the metal to prevent excessive heat accumulation of the paper meal roller from damaging the roller surface due to long-term operation.

The smoothness of the paper has a great relationship with the moisture of the paper. Due to the large amount of heat generated by the friction of the calender during operation, the moisture of the paper will be reduced, and the smoothness and gloss of the paper will be reduced.

In order to eliminate these heat, some intermediate rollers are drilled with a diameter of 40 to 60mm hollow rollers, through the cooling water, in order to maintain a certain degree of moisture in the paper, to increase its smoothness and tightness.

If the moisture of the paper web entering the calender is too high, it is easy to stick to the roller and break the paper, which also affects the gloss of the paper. Therefore, the hollow roller is heated by steam, which plays a role in ironing the paper to improve the gloss of the paper.

The paper meal roller is made of one or more fibers made of paper or fabric and then stacked on the shaft after being compacted. The paper meal roller body must have a certain hardness and elasticity. The hardness of the paper roll depends on the nature of the paper or fabric from which the roll is made and the process conditions under which the roll is made.

Factors affecting paper super calendering:

1) The line pressure of the pressure roller is high:

Because the roller group of super calender is composed of metal roller and paper meal roller. During pressurization, the elastic deformation caused by the contact between the paper meal roller and the paper is large, and a narrow surface contact is formed between the two rollers. When the online pressure is constant, the paper sheet is not easy to be crushed under the specific pressure of the pressing area, so it can withstand a much larger line pressure than that of the ordinary calender, which increases the tightness of the paper and also improves the smoothness of the paper.

The radial deformation of the paper meal roller during calendering results in different circumferential speeds in the deformation area, resulting in tiny sliding between the rollers, which plays a role in rolling and friction on the surface of the paper, and improves the smoothness and gloss of the paper.

If the pressure is too large, the impression of the paper meal roller will be pressed onto the paper, which will affect the smoothness of the paper.

2) Moisture content of paper sheets: Some paper types, such as capacitor paper and translucent paper, require paper with high tightness and transparency. If the water content is large, the calendering effect is good. Therefore, such paper should be wetted back before calendering to humidify the water to 15% ~ 28%.

3) calendering speed: the calendering speed increases, the time of the paper by the calendering effect decreases, but the roller friction heat increases, but there is a better effect, the smoothness and gloss of the paper sheet will be slightly improved;

4) The number of calender rollers and their surface temperature: within a certain range, increasing the temperature of the roller can improve the smoothness, tightness and transparency of the calendered paper, and can also play the role of drying and dehumidification, which is beneficial to calendering. However, the temperature is too high, especially when the moisture content of the paper is too low, it will have an adverse effect on the calendering effect.

At this time, saturated steam must be sprayed onto the paper to increase the water content of the paper. Or pass cold water into the metal roller to cool down, adjust the temperature of the roller, and control the calendering moisture in a reasonable process range.

5) The composition of paper and the nature of fiber raw materials: generally thin and strong swelling ability of fiber and pulp with high beating degree of paper, after matte smoothness and tightness are easy to improve; for pulp, wood pulp is higher than straw pulp, chemical pulp is higher than ground wood pulp. The filler has small particle size, high dispersion, soft texture, good calendering effect, and good smoothness, gloss and tightness of the paper.