Common faults and troubleshooting of sealing machine

(1) The sealing is not firm, which is one of the common faults of the continuous sealing machine. The sealing is not firm, which has three meanings: ① The sealing part of the packaging bag cannot be sealed;
② Under the pressure of the sealing knife, although the bag mouth is sealed, it will crack again if it is rubbed or torn slightly; ③ When the peeling test was carried out on the sealing part, the appearance of half sealing and half separation was presented. The sealing quality of such packaging bags was still unqualified, because the contents were easily missed after being kneaded during storage and transportation. This situation often occurs when the composite lining is OPP or blown PE.
The main reasons for forming a problem are as follows.
The heat seal temperature is not good
Generally, when the total thickness of the bag is 80~90 μ M, the heat sealing temperature should reach 170~180 ℃; The total thickness of composite bag with PE as lining is 85~100 μ M, the temperature should be controlled at 180~200 ℃. As long as the total thickness of the bag is increased, it is necessary to improve the heat sealing temperature accordingly.
2. The heat sealing speed is too fast
Failure to seal is also related to the speed of the sealing machine. If the speed is too fast, the sealing area will be transported to the cold pressing area for cooling treatment by the traction roller before it can be heated, which will naturally fail to meet the quality requirements of heat sealing.
3. Improper pressure of cold pressed rubber wheel
There is one cold pressing rubber wheel at the top and one at the bottom, and the pressure between them should be moderate. When adjusting the pressure, just clamp the tension spring.
4. The quality of heat sealing film is questionable
The sealing failure is also related to the quality of the heat sealing film. If the composite lining corona treatment is uneven, the effect is not good, and it just appears at the sealing place, it must not be sealed. This kind of situation is rare, but once it appears, the goods will be invalid. Therefore, in the color printing and packaging profession, the next process is to supervise the previous process. Once a quality problem is found, it is necessary to analyze the reason and deal with it in time.
If there is water and dirt at the sealing place, the sealing will not be firm.
In conclusion, to deal with the problem of poor sealing, it is usually necessary to properly increase the heat sealing temperature, then reduce the heat sealing speed, and increase the pressure of the cold-pressed rubber wheel together.
The main reasons for the second kind of seal failure are as follows.
The heat seal temperature is not good
It is only necessary to properly improve the heat seal temperature to solve the problem.
2. The cutting surface of the heat sealing knife is not flat
The heat sealing knife is divided into two parts, the upper and the lower. Usually, the thermoelectric coupling is installed between them to sense the transmission of temperature. There are three screws on the hot sealing knife. The central screw has the effect of supporting and reinforcing the blade. The other two screws are equipped with pressure springs and gaskets, which are mainly used to regulate the pressure of the hot sealing knife. The upper and lower blades have two tension springs respectively.
The main reason for the uneven surface of the heat sealing tool is that the central screw is inclined, not horizontal; Or the pressure of the tension spring of the upper heat sealing knife is uneven.
The treatment method is to check the orientation of the central screw from the beginning to make it horizontal. If the upper and lower heat sealing knives are not balanced, they should be completed by adjusting the pressure tension spring to moderate. When the tension spring moves outward, the heat sealing knife will fall downward; When the tension spring of the lower blade is tightened upwards, the heat sealing blade will move upwards.
3. Uneven pressure of cold-pressed rubber wheel
The uneven pressure of the cold-pressed rubber wheel will also cause this kind of sealing problem, and the treatment method is similar to the same condition.
There are two main reasons for the third kind of seal failure.
Uneven pressure of hot sealing knife or uneven pressure of cold pressing knife
The conditioning on the hot sealing knife and the cold pressing knife are completely the same.
2. The cutting surface of the heat sealing knife is not flat
Refer to the corresponding treatment method for the second type of seal failure.
(2) The fuse is blown
To eliminate this problem, first check whether the power supply is normal, then cut off the power supply, measure whether the switch is damaged with a resistance gear, and then carefully check whether the circuit and motor are short-circuited. Normally, when the motor is short-circuited, the winding is burnt or disconnected, the fuse will blow as soon as the sealing machine is started. Another reason for this problem is that the fuse standard is too small, so we can handle the problem by increasing its standard accordingly.
⑶. "Squeak" sound in work
This problem appears in the working process of the sealing machine. The "squeak" often occurs suddenly, followed by the uneven sealing speed, resulting in poor texture at the sealing imprint of the packaging bag, which affects the appearance quality of the goods. Occasionally, they can also work normally, but it's a storm.
This appearance is mostly due to mechanical damage or severe wear, as well as poor smoothness.
In addition, if the joint of the high-temperature belt is loose, severely worn, and unclean, with dirt on the surface, and the working process is not synchronized with the traction wheel, sometimes a "squeak" sound will be announced. The treatment method is to replace the high-temperature zone with the same standard.
There are certain tricks to replace high temperature. First, tighten the tension spring of the pressure wheel by hand, and then place one end of the high temperature belt on the rubber wheel, and the other end is supported by the hand against the other rubber wheel. Set the governor to low speed. Once it is started, the high temperature belt will be automatically installed by the motion inertia.
Sometimes the "squeak" is also announced by the DC shunt motor. It can be caused by a lack of oil in the motor bearings. If this is the case, it should be removed and oiled smoothly, so that the noise can be eliminated.
(4) The sealing temperature is out of control
The problem is that the thermometer appears to be out of order, the temperature cannot be controlled, the heat seal temperature is unstable, the seal is not scorched, that is, the seal is not tight, the seal is deformed, and it is very ugly.
The main reason for this problem is that the thermometer is broken and needs to be repaired; In addition, the thermocouples can also be broken and can not normally transmit the sensing temperature to the thermometer. Replace with the same type and standard thermocouple.
The mechanical reason is that the heat sealing pressure is uneven. Simply adjust the pressure tension spring of the heat sealing knife to make its pressure common. Together, the press contact surface of the heat sealing knife should be clean and free of dust.
Another reason is that the heat sealing quality of the composite material itself is poor, and the heat sealing coefficient changes, resulting in different temperatures.
(5) The sealing machine stops
In production, we have encountered the problem that the sealing machine is running and stopping, and the speed is not the same. We removed the panel on the back of the sealing machine, and found that the connection between the shaft rod of the motor and the gearbox has appeared to be falling and loose. Tighten the screws from the beginning to make sure they are all consistent, and the problem will be solved. In addition, the main motor is connected by carbon brush
If the carbon brush is severely worn, does not fully contact with the slip ring, or has poor conflict, it will also form a sealing machine
Stop and go, and replace with a new carbon brush of the same type to solve the problem.
(6) Bubbles and irregular marks appear at the seal
This type of defect is also relatively common. Although it does not cause leakage of the packaging, it affects the aesthetic feeling of the packaging and damages the image of the product.
There are two main reasons for this problem.
The equipment has been used for a long time, and dirt such as dust and plastic scraps are attached to the high-temperature zone, which forms a non-smooth and uneven high-temperature zone, which makes the sealing uneven, and presents bubbles after being pressed by the cold pressing wheel. The problem can be eliminated by cleaning or replacing the high-temperature belt from the beginning. The high-temperature zone is generally ⑴. 5cm wide and about 22 thick μ m. If the dirt can't be washed out after being stuck, it has to be discarded.
2. There are irregular high and low marks on the cold-pressed rubber wheel, which are directly reflected on the packaging, so that there are more obvious marks at the seal. In order to ensure that the packaging bag is formed beautifully, * Jia is to replace the cold-pressed rubber wheel.
(7) Problems to be noticed during equipment maintenance
1. The sealing machine should be placed in a ventilated and dry place. Generally, the room temperature should be maintained at about 25 ℃.
2. Every 48 hours of operation, 6 # oil should be added to all moving parts, mainly at gears, bearings and gearboxes.
3. Dust removal shall be conducted regularly and the whole machine shall be cleaned. When not in use, it is advisable to unplug the power supply and conceal it with a cloth.
4. If the working time is too long, the cooling fan should be turned on before shutting down, and then shut down after the temperature is reduced. The high temperature zone is easily damaged because it is shut down without cooling.
5. The high-temperature zone shall be regularly cleaned to ensure the sealing quality.
6. Severely worn parts shall be replaced in time to extend the service life of the whole machine.