Analysis of common problems of coating machine

Process flow of the coating machine: the polar substrate placed on the unwinding device is pulled out by the roller, enters the floating roller tension system after automatic correction, and enters the coating head after adjusting the unwinding tension. The polar slurry is coated according to the setting procedure of the coating system. The coated wet pole piece enters the oven and is dried by hot air. The dried pole piece is adjusted by the tension system, and the winding speed is controlled to synchronize it with the coating speed. The pole piece is automatically corrected by the deviation correction system to keep the base material in the center position, and the winding device is used for orderly winding.
The general process flow of electrode coating is as follows:
Unwinding → splicing → traction → tension control → automatic deviation correction → coating → drying → automatic deviation correction → tension control → automatic deviation correction → rewinding
The coated substrate (metal foil) is released by the unwinding device and fed into the coating machine. The head and tail of the substrate are connected into a continuous belt at the splicing table, and then sent to the tension adjustment device and the automatic deviation correction device by the traction device. After adjusting the tension and position of the sheet path, they enter the coating device. The polar paste shall be coated in sections according to the predetermined coating amount and blank length in the coating device. During double-sided coating, the first side coating and blank length are automatically tracked for coating. The coated wet electrode is sent to the drying system for drying, and the drying temperature is set according to the coating speed and coating thickness. After tension adjustment and automatic deviation correction, the dried pole piece is rolled up for processing in the next process.
The key of the coating machine is to be stable. After a parameter is adjusted, it may last for a whole day. If there are any variables in the coating process, it will have a great impact on the battery performance. Although the stability of the coater is very important, the proficiency of the operator is also particularly critical. An excellent operator can not only operate the equipment and know how to maintain the equipment, but also know what causes the problem when there is a problem in the coating process, what is the main reason for this problem, and how to solve it. Be a qualified operator and a good equipment maintainer.
In the process of coating, the bad coating gap and the wrinkling of the pole are analyzed:
one
Phenomenon and causes of poor coating clearance
one
Trailing
(1) Material: slurry material, viscosity, solid content, slurry (surface) tension
(2) Equipment: distance between coating and back roll, speed of coating roll when the back roll bounces off, diameter of back roll, surface material of back roll. The back roll is deformed. The parallelism between the back roll and the coating roll, the back roll and the front roll of the oven are not parallel. The tension in operation.
(3) Operation: parameters for head and tail adjustment
two
The head and tail are not parallel
(1) Material: the gravity on both sides of the substrate is uneven.
(2) Equipment: the horizontal plane of back roll and coating roll is not parallel; The left and right side of the back roll are not aligned when it bounces off; The surface coaxiality of the back roll, the back roll and the traction roll are not parallel, and the level changes.
(3) Adjustment state of tension adjusting roller
three
The front and back sides are not aligned
(1) Operation: the first side gap is consistent. The operation parameters are not adjusted properly. The light eye is blocked. The unwinding pinch roll forgets to clamp
(2) In terms of equipment: the rear tension of the second side is large, and the front tension is small
four
The white space becomes smaller when starting in the middle, and the back 3-4 pieces are inaccurate
In terms of equipment: the tension is not correct at the initial stage of starting, the first side has no memory function, the foil belt slides forward 2-3 mm when starting, the tension is opened first, the back roll is not turned, and the coating head has no pinch roll or is not clamped.
five
The last piece is parallel and trailing
Operation: spacing of back roller (trailing on the first side, not trailing on the second side); The back roll is pulled slowly when the machine is stopped
six
Thick head and thin tail or thin head and thick tail
Operation: head and tail parameters are not adjusted properly.
seven
There is action but no effect
(1) Material: the two sides of the foil are different in tightness
(2) Equipment: foil leaves the back roll at a small tension moment, and the distance between the coated back rolls
eight
Double-sided large blank phenomenon
The photoeye is not sensitive, the gap on the first side is abnormal, and the photoeye is covered
two
The length of coating section changes and the spacing is unstable
one
Large change in segment length (* shorter) * small change in spacing (narrower)
Fault cause
1) The surface of back roll and rear rubber roll is not clean;
2) The gap between back roll and rubber roll is too small and tight;
3) The front and rear tension do not match, and the unwinding is greater than the winding.
Solution
1) Cleaning roller
2) Adjust the ramp to the fixed position
3) Adjust with reference to setting parameters
two
Large change in segment length (* shorter) Large change in spacing (larger)
Fault cause
If the length of the head of the pole piece and the head of the next piece changes greatly (decreases), the tail between the two segments of the pole piece changes slightly, so that it can be judged that the solenoid valve (control rubber roll movement) is not flexible.
three
Large change in segment length (* longer) * large change in spacing (wider)
Fault cause
1) The surface of back roll and rear rubber roll is not clean,
2) There is no pinch roll, which may not be clamped or out of control
3) The front and rear tension do not match, and the winding is larger than the unwinding
Solution
1) Cleaning roller
2) Add pinch roll
3) Adjust with reference to setting parameters
three
Causes and countermeasures of the wrinkling phenomenon of the pole sheet during the operation of the coater
1. The overall installation accuracy is low. The installation center of each component deviates from the design center line of the whole machine, or has an angle with the design center. The foil belt will be seriously wrinkled, and the installation center must be adjusted.
2. If the parallelism between the rollers is out of tolerance, the foil strip will wrinkle. It is necessary to carefully check whether the vertical projection plane is not parallel or the horizontal plane is not parallel, and then adjust it.
3. The roughness of the over-roll roll surface is out of tolerance, the roll surface is not smooth enough, and there is obvious processing texture, which will also cause the foil belt to wrinkle, so the manufacturer needs to replace it.
4. The back roll and each passing roll are stuck with foreign matters or scrubbed with too much water and isopropanol, which need to be checked frequently, found and cleaned in time, and pay attention not to damage the roll surface.
5. The foil strip joint is poor. When the tension on both sides of the foil strip is unbalanced, the pole piece is wrinkled. First adjust the tension adjusting roller under the cloth coating head, and then adjust the adjusting roller to the original state after the foil strip is gradually stable.
6. When the gap between the back roll and the coating roll is inconsistent when they are close to contact, the pole piece will wrinkle. The coating line believes that the gap should be carefully adjusted whether the first side or the second side is coated. First, the gap should be properly expanded, and then slowly reduced. At the same time, observe the dial indicator scale at the moment when the coating roller just contacts the foil strip, and then reduce the gap by 0.03 mm.
7. When the deviation correction system is abnormal, the pole will also wrinkle. Check whether the front and rear three deviation correction systems are in automatic state. According to the coating line, the length of both sides of the foil strip is inconsistent, that is, when the sickle is bent too large, the pole piece will wrinkle, which exceeds the ability to correct the deviation, so the foil has to be replaced.
8. When the tension of the pole piece is too large, the pole piece will wrinkle. Check whether the tension setting value is reasonable. Then check whether the rotation of each drive roll and winding roll is flexible, and deal with the inflexible roll in time.
9. When the back roll pulling stroke is inconsistent, the pole piece is wrinkled. The machine repair personnel are required to check, confirm and adjust. After the back roll and the coating roll are pulled apart, the gap on both sides is 1mm (see the dial indicator). The trial coating is started. When the tail is qualified, lock the nut.
10. The rubber roll surface of the back roll will undergo periodic elastic deformation during reuse. When there is a certain degree of residual deformation, it will also wrinkle. At this time, it must be replaced with a new one.
11. According to the coating online understanding, the parallel state of each roll is damaged due to the loosening of the fastening screw of a roller, and wrinkling will occur at this time. As long as it is found in time, it can be adjusted and fastened.
four
The pole piece breaks when the coater is running
1. The tape is not connected properly and the additional tension is increased, which causes the foil tape to break at the weak point;
2. Damage caused by sampling results in a significant decrease in the tensile strength of the foil;
3. The tension is too large, unstable and abrupt;
4. Sudden change of air volume and serious uneven distribution;
5. The sudden change of temperature has a great impact on the strength of aluminum foil;
6. The quality of the foil strip is poor, and there is a gap at the edge;
7. The foil strip deviated seriously and was cut off by the edge of the roller end face.
five
Other faults
one
There are obvious bumps and scratches on the electrode plate, which are distributed longitudinally
1) The blade of the scraper roller is chipped or stuck with foreign matters
2) The coating roller is not easy to use. During the coating gap, if the gap material coming out from the coating roller is not scraped clean and reapplied to the substrate, it will leave obvious marks on the substrate;
3) The parallelism between the axis of the scraper device and the axis of the coating roller is out of tolerance, resulting in inconsistent pressure of the blade on the coating roller, improper shape of the blade edge, low elasticity of the blade, etc.
two
There are obvious cracks on the pole piece
The drying speed is too fast, the oven temperature is too high, and the baking time is too long.