How to deal with common problems in calendering and reeling section?
March 24, 2023
During the operation of the paper machine, you may want to know what faults may occur in the calendering and reeling section and the reasons for the faults. Today, we will analyze and explore the causes and solutions of the failures.
What Kinds of Calendars are This?
Divided into three types according to the number of working rolls:
- two rolls
- three rolls
- four rolls
Divided into five types according to use :
- Sheet calendar: Used for sheet pressing or textile gluing, usually with three or four rolls, and each roll rotates at the same speed.
- Glue rubbing calendar: Used for rubbing glue on textiles, usually three rolls, with a certain speed ratio between each roll.
- Universal calendar: This calendar has both the functions of the above two calenders, usually three or four rolls, and the speed ratio of each roll can be adjusted by auxiliary gears.
- Calendering machine: It is used to manufacture films with patterns or certain shapes on the surface, and one of the rollers is engraved with patterns.
- Steel wire calendar: Used for gluing steel cord fabric, consisting of four rollers.
Divided into five types according to the arrangement of the rollers
- there are I-type, T-type, L-type, Z-type, S-type
When it comes to the advantages and disadvantages of calendering, what do you know about them?
Advantages of Calendering
- The calender is very good at handling polymer that are heat sensitive as it causes very little thermal degradation.
- It is good at mixing polymers that contain high amount of solid additives that don’t get blended or fluxed in very well.
- Due to this calender is produce a large amount of melt than extrusion
Disadvantages of Calendering
- It is a very expensive process to perform
- If the thickness is below 0.006 inches then there is tendency for pinholes and voids to appear in the sheets.
- If the thickness is greater than about 0.06 inches then there is risk of air entrapment in the sheet.
- So to achieve the desired thickness is also a very difficult process.
Since you have followed me to learn about of advantages and disadvantages of calendering, let's know have you encountered any problems with the calendering and reeling ？
What are the cause of the failure of the calendering and reeling section?
Broken ends of calendered take-up sheet
- Improper paper tension
- The wetness of the paper is inappropriate, and the moisture distribution is uniform
- The weight of the paper and the thickness of the whole width are uneven
- Take small pieces of paper or paper wool onto the paper
- Poor paper strength or paper defects caused by other parts of the paper machine
Difficulty in calendering and guiding
- Improper control of paper tension
- Less quantitative
- Moisture too dry or too low
- The blade of the paper scribing knife becomes blunt and the paper cannot be cut
- The calendering scraper is not tight
The paper roll appears in a trumpet shape
- When changing the paper roller, the bottom of the roller becomes loose
- One side of the paper is thinner
- The paper roll has been bent
- The flared shape of the paper roll refers to the phenomenon that the paper roll is gradually reached in one end of the paper roll in the process of roll paper, and the other end is protruding. Such paper rolls will cause difficulties when cutting paper and re -rolling, increasing paper loss. The paper rolls that are rolled into a horn are not rolled on one side due to the paper layer on the surface of the paper roll, but because the paper of the paper core is out of the paper.
End face star appears at the paper roll section
- The paper roller rolls tightly inside, and the paper inside is strangled into polygon
- The paper page becomes thicker from thin. If it is just on the side of the paper, the thin place is soft and the thick place is tight, and the star shape can be seen on the end surface.
Roll paper pleat
- The position of the paper roll is not correct, and the weight of the full width of the paper roll against the surface of the paper roll cylinder is too different between the front and rear ends. This results in inconsistent web tension between the calender and the paper roll machine, causing the skewed web to be rolled into oblique folds on the end where the paper roll and the cylinder surface contact more heavily
- When the wet paper section breaks, uneven soft and hard paper rollers rotate over the paper roll cylinder. When the time is slightly longer, it is easy to press a certain thickness of paper on the surface of the paper roller into many dead folds
- When the paper roll is not straight, the tension on both sides of the paper web is inconsistent with the tension in the center, and the paper roll jumps during operation, which can also cause live wrinkles
The above are common causes of failures in the calendering and reeling section, what do you know the solutions to common faults in the calendering and reeling section？Let’s have a look.
Five solutions for the problem of calendering and reeling section
Solution of broken ends of calendered take-up sheet
- check whether the speed difference between drying and calendering, calendering and coiling cylinders is appropriate, whether the radian of calendering arc roller is appropriate, and whether the spring roller is horizontal.
Solution of difficulty in calendering and guiding
- Adjust the position and air volume of the paper guide air plate
Solution of the paper roll appears in a trumpet shape
- Pour some water on the roll core on the outward side to soak the paper edge at the roll core
- Roll in some waste paper on the loose side of the paper roller until the paper roller is flat and does not move
- After rolling into a trumpet shaped paper series, you can use a heavier object to aim at the shaft head of the rolled paper series and forcefully hit it to the normal position
Solution of end face star
- if the paper machine operator finds a star phenomenon, he/she should use a method of appropriately relaxing the tension of the paper sheet in front of the roll machine to control it.
- The key points for the operation of the paper reeling section of a paper machine are: the axial center line of the paper roller and the paper reeling cylinder should be parallel; the paper roller pressed on the paper reeling cylinder and dragged by the paper reeling cylinder during operation should be in full and uniform contact with the surface of the paper reeling cylinder; the full width paper reeling speed and tension should be consistent
Solution of Roll paper pleat
- When rolling an oblique pleat, immediately use the adjusting handwheel on the paper holder of the paper reeling machine to lower the slightly higher end, so that the paper roller and the cylinder surface are in uniform contact throughout the entire width until the paper sheet smoothly enters the paper reeling machine and the pleat disappears
- When the wet paper is broken, lift the paper stack up, and when the paper is introduced to the calendering section, put down the paper roller for operation
- When winding paper that is not straight, leave a 50-100mm thick paper layer on the roll to solve the problem of wrinkles
- Thanks for your reading today, we took you to analyze the problems in the calendering and reeling section and the methods to solve them. we hope this article can better help you understand it，if you find this article useful, please feel free to share it with others.