Paper calender structure and principle of words you know

Construction of ordinary calender Ordinary calender generally consists of 3 to 8 rollers), each roller is in a vertical line and installed on the same frame. The lower roller is the active roller, and the remaining rollers are driven by friction. The number of rolls of the calender is generally determined by the speed of the car and the variety of the paper. The low and medium speed paper machine is generally six rollers, the tissue paper can be three rollers, and the newsprint can reach 8 to 10 rollers. The lower roller bears all the applied pressure and the weight of each roller, so its diameter is the largest. The second roller from the lower number is directly close to the active roller, and its diameter is slightly larger due to the large tangential force during friction transmission. The diameter of each roller in the middle is the smallest, so that the rollers tend to be in line contact, thereby increasing the pressure on the paper surface to improve the calendering effect. The uppermost roller is subjected to external pressure, so the diameter is also slightly larger. In order to facilitate the introduction of paper, the top of the ordinary odd-numbered roller calender is equipped with a pressure roller, which can be made of felt. The even-numbered roller calender has no pressure roller and is suitable for compressed air to lead paper. The working part of the roller body of the ordinary calender roller is cast in the metal mold, because the heat of molten iron during casting is absorbed sharply by the metal mold, so that the working surface forms a layer of about 10~20mm, with high wear resistance. The surface of the calender roller is required to be very smooth, the conicity is not more than 0.005mm, the ovality is not more than 0.01mm, the tensile and compressive strength is large, the resistance to friction and the scratch is high, the expansion coefficient is small, not easy to rust, and can resist the corrosion of acid, alkali and salt. The contact surface between the roller and the roller must be close without slight gaps. In order to overcome the deflection deformation after compression, the upper roller and the lower roller have "medium and high" (sometimes 10-15% of the medium and high of the lower roller is allocated to the penultimate roller), so that the paper surface is flat and tightly compressed to meet the calendering requirements. General calender roll is made of nickel-chromium steel or cold cast iron, hardness of not less than 80~85 (Shore). As for the size of the roll, in addition to its position on the calender, it mainly depends on the width of the paper machine, I .e. the larger the width, the larger the diameter. After the paper sheet is introduced between the pressing roller and the upper roller, it passes through each roller in sequence, and is peeled off from the previous roller and transferred to the lower roller by means of a scraper. As the number of rolls increases from top to bottom, the line pressure increases. Generally, the two rollers at the bottom of the calender are provided with ventilation, cooling and cooling devices to eliminate the heat converted by mechanical energy during the calender process. Such ventilation and cooling devices can also be provided at the second and third rollers to adjust the calender effect in the transverse direction of the paper web. The calender has a special cooling fan. The cold air is directly blown through the center of the roller through the nozzle. Each nozzle is equipped with a valve to adjust the air volume and can move horizontally. mechanism of paper calender In the past, the mechanism of calendering was understood to be caused by the friction caused by mechanical compression and speed difference between rolls. When it was found that the speed difference between the rollers was extremely small, and the friction effect was questioned, it was also proposed that calendering was caused by the deformation of the paper sheet when the paper surface was deformed by the shearing effect between the rollers. Recently, with the help of an electron microscope, it has been clearly seen that the surface of the calender roll has a clear impression on the surface of the calender roll, thus clarifying the calender of the paper sheet, mainly in the form of transfer printing, the smoothness of the roll surface is transferred to the paper surface. Obviously, the more flexible and plastic the surface of the paper sheet, the higher the roller pressure and the longer the pressure time of the paper sheet, which is more conducive to obtaining a higher calender effect. The friction and the shear deformation of the paper surface do not play a major role.

2023-12-20

Paper calender, the reader is so summarized

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.

2023-10-10

Introduction to the calendering mechanism of papermaking

In the past, the mechanism of calendering was understood to be caused by the friction caused by mechanical compression and speed difference between rolls. When it was found that the speed difference between the rollers was extremely small, and the friction effect was questioned, it was also proposed that calendering was caused by the deformation of the paper sheet when the paper surface was deformed by the shearing effect between the rollers. Recently, with the help of an electron microscope, it has been clearly seen that the surface of the calender roll has a clear impression on the surface of the calender roll, thus clarifying the calender of the paper sheet, mainly in the form of transfer printing, the smoothness of the roll surface is transferred to the paper surface. Obviously, the more flexible and plastic the surface of the paper sheet, the higher the roller pressure and the longer the pressure time of the paper sheet, which is more conducive to obtaining a higher calender effect. The friction and the shear deformation of the paper surface do not play a major role.

2023-09-20

The calendering effect of paper, what to do

When the paper passes through the calender, under the action of the line pressure, the polyurethane roller and the paper are deformed to form a deformed area. The pressure is distributed over this area.

2023-06-04

Hot roll

The hot roller is madeAluminum alloyComposition, the surface is coated with a layer of special substances, it can not only resist high temperature, the most important thing is that it will not adhere to carbon powder and other dirt, whether solid or molten liquid, therefore, it can carry the load (such as paper,sulfuric acid paperetc.)

2023-05-28

Super calender

Super calender is a kind of calendering equipment in papermaking. The shape is similar to the mechanical calender, but the number of rollers is more. Suitable for coated paper, coated paper, writing paper, offset printing paper and other cultural paper and capacitor paper and other insulating paper.

2023-04-28

Soft calendering technology

Soft roller calender is a calender group consisting of a combination of hard and soft rollers. Hard roller: hot roller, cold casting roller, the surface hardness is high, smooth like a mirror surface, with oil or water outside the machine heating to the roller, also useful induction electric heating, roller surface temperature from 120 degrees to 200 degrees, up to 230 degrees. Soft roller: controllable middle and high roller, the surface is made of special polymer, which requires high temperature and high pressure resistance, good elasticity, and can withstand frequent changes in load. The main materials used are epoxy resin, nylon,synthetic rubber, polyester urethane, etc.

2023-04-12

Warmly celebrate the success of the construction of Dalian Pearl Machinery website!

With 61 years of history, Pearl Machinery is an excellent supplier of papermaking machinery finishing equipment. It can provide chilled cast iron papermaking calender rolls to customers around the world: steam-heated hot rolls, heat transfer oil-heated hot rolls, swimming rolls and zoned controllable mid-high rolls, roll shells; fixed mid-high hard calender, soft calender, controllable Mid-high hard calender, soft calender. At present, we have provided more than 700 soft and hard calender of various specifications and suitable for various paper needs, and more than 18000 calender rolls to all parts of the world.

2021-06-24

Warmly celebrate the success of the construction of Dalian Pearl Machinery website!

With 61 years of history, Pearl Machinery is an excellent supplier of papermaking machinery finishing equipment. It can provide chilled cast iron papermaking calender rolls to customers around the world: steam-heated hot rolls, heat transfer oil-heated hot rolls, swimming rolls and zoned controllable mid-high rolls, roll shells; fixed mid-high hard calender, soft calender, controllable Mid-high hard calender, soft calender. At present, we have provided more than 700 soft and hard calender of various specifications and suitable for various paper needs, and more than 18000 calender rolls to all parts of the world.

2021-06-24