DBF-900 type multi-functional plastic film continuous sealing machine is favored by small and medium-sized food processing companies because of its characteristics such as continuous sealing, stable performance, and good sealing effect. This machine has also been widely used in the production of bags for flexible packaging. When the plastic film is bagged with side seals, medium seals, and bottom seals, the machine can be re-sealed to achieve the heat seal quality requirements.
The machine has been used for a long time, especially under continuous operation and overload conditions, it is prone to some electrical failures and mechanical failures, such as: the seal is not strong, the machine stops, the fuse is blown at the start, and the operation sounds "The temperature is uncontrollable, the finished bag is deformed and bent at the sealing, and air bubbles or irregular marks appear at the seal of the knife. In this paper, based on actual experience, several kinds of failures are analyzed, the causes are analyzed, and the corresponding solutions are proposed. The maintenance of the continuous sealing machine is also explained. It is hoped that the company and individual who use the continuous sealing machine will be helpful.
1. The seal is not strong
Sealing is not one of the common faults of the continuous sealing machine. The sealing does not have three meanings: 1 The sealing position of the bag cannot be closed; 2 The bag mouth is sealed under the pressure of the sealing knife, but it is squeezed slightly or Tear-peeling and sealing cracked again; 3 When the peeling test was performed at the sealing area, half of the seals were firmly sealed and half separated. The sealing quality of the bag was still unacceptable because the contents were squeezed during storage and transportation. Easy to miss. This situation often occurs when the composite lining is OPP and blow molded PE.
The main causes of the first type of failure are the following.
(1) The heat seal temperature is not enough
Under normal circumstances, the composite bag with OPP as the material, when the total thickness of the bag is 80 ~ 90μm, the heat sealing temperature should reach 170 ~ 180 °C; the total thickness of the bag made of PE with the compound bag is 85 ~ 100μm When the temperature should be controlled at 180 ~ 200 °C. As long as the total bag thickness increases, the heat seal temperature must be increased accordingly.
(2) The heat seal is too fast
The lack of sealing is also related to the speed of the sealing machine. If the speed is too fast, the seal is still heated in the future and it is transported to the cold pressure place by the pulling roller for cooling. Naturally, the heat sealing quality is not achieved.
(3) The cold pressure rubber wheel is not suitable
There is one on each side of the cold-compression rubber wheel, and the pressure between them must be moderate. When adjusting the pressure, only the spring needs to be clamped.
(4) There is a problem with the quality of the heat seal film
Sealing seals are also not related to the quality of the heat-seal film. If the corona treatment of the composite lining is not uniform, the effect is not good, and it happens to occur at the seal, and it cannot be sealed. This situation is rare, but once it appears, the product must be scrapped. Therefore, in the color printing and packaging industry, it is the next process to supervise the previous process. Once quality problems are discovered, the causes must be analyzed and resolved in a timely manner. If there is moisture and dirt in the seal, the seal will be loose. In short, to solve the first problem of poor sealing, the heat sealing temperature can be generally increased appropriately, and then the heat sealing speed can be reduced, and the pressure of the cold rubber roller can be increased at the same time.
The main reasons for the failure of the second seal are as follows.
(1) The heat seal temperature is not enough
Just increase the heat seal temperature to solve the problem.
(2) The surface of the heat-sealing knife is not sufficiently smooth
The heat-sealing knife is divided into upper and lower pieces, and usually the thermocouple is installed therein to sense the temperature transmission condition. There are three screws on the heat-sealing knife. The middle screw plays the role of supporting and strengthening the blade. The other two screws are equipped with pressure springs and gaskets, which are mainly used to adjust the pressure of the heat-sealing knife. Each of the upper and lower blades has two springs. . The main reason for the unevenness of the surface of the heat-sealing knife is that the middle screw is inclined, not horizontal; or the pressure of the upper heat-sealing knife is not uniform.
The solution is to re-adjust the position of the middle screw so that it is level. If the upper and lower heat-sealing blades are unbalanced, they must be adjusted by adjusting the pressure springs. When the spring is retracted outwards, the heat-sealing knife will fall downward; when the spring of the lower blade is applied upwards, the heat-sealing knife will move upwards.
(3) Uneven pressure on the cold rubber roller
The uneven pressure of the cold pressing rubber wheel can also cause the failure of such sealing. The solution is similar to the first one.
There are two main reasons for the failure of the third seal.
(1) Uneven pressure in the heat-sealing knife or uneven pressure in the cold knife
The adjustment on the heat seal knife and the cold knife is exactly the same.
(2) The surface of the heat-sealing knife is not sufficiently smooth
Refer to the corresponding solution to the failure of the second seal.
2. Blown fuse
The main motor of DBF-900 multi-function plastic film continuous sealing machine is produced by Shanghai Hulong Motor Co., Ltd. The main function of this motor is to drive the transmission and gear transmission of various components. Sometimes when the sealer is started, it will make a "click" sound, it will not work properly, and even a fuse may blow on the fire.
Exclude this fault should first check whether the power is normal, and then cut off the power, use the resistance file to measure whether the switch is damaged, in addition should also carefully check the line and the motor is short circuit. Usually, when the motor is short-circuited or the winding is damaged or disconnected, the fuser is blown as soon as the sealing machine is started. Another reason for this failure is that the size of the fuse is too small. If the size of the fuse is increased, the problem can be solved.
3. There is a "click" in the operation
The fault occurs during the operation of the sealing machine. The "click" sound often occurs suddenly. The next step is the uneven speed of the sealing, which causes the texture of the bag sealing area to be poor, which affects the appearance of the product. Occasionally, it can work normally but it is fickle.
This phenomenon is mostly due to mechanical damage or serious wear and poor lubrication. The DBF-900 multi-purpose plastic film continuous sealing machine used by our factory appeared some time ago during sealing. We first follow the sound emitted to find the fault site. Open the back protection board and found that the sound of "click" was transmitted from the gearbox. Remove the screws one by one and found that the gear inside the transmission gear has dried and the gears are bright. This shows that the cause of the failure is Lack of oil. Mix the same model oil and grease into the gearbox, and tighten the screws to restore it. After the power is turned on, the “click” sound disappears and the seal is normal.
In addition, if the joints in the high temperature zone are loose and seriously damaged, and they are not clean and have dirt on the surface, they will not be synchronized with the traction wheel during operation, and sometimes they will make a "click" sound. The solution is to replace the same high temperature zone. Replacing high temperatures with certain skills. First, the pressure wheel spring is compressed by hand, and then one end of the high temperature belt is placed on the rubber wheel, and the other end is held against the other rubber wheel with the hand, and the speed governor is set to low speed, and the start is activated. The inertia of the movement, the high temperature belt is automatically installed.
Sometimes the "click" sound is also emitted by a DC parallel motor. It may be due to lack of oil in motor bearings. If this is the case, it should be removed and lubricated, and the sound can be eliminated.
4. Sealing temperature out of control
The fault manifests itself as failure of the temperature meter, inability to control the temperature, non-constant heat sealing temperature, and the fact that the seal is not scorched or the seal is not firm and the seal is deformed. It is difficult to see.
The main cause of the malfunction is that the thermometer is bad and must be repaired; in addition, the thermocouple may also be broken, and the sensing temperature cannot be normally transmitted to the thermometer. Replace thermocouples of the same type and specifications.
The mechanical reason is that the heat sealing pressure is uneven, so long as the pressure spring of the heat sealing knife is adjusted so that the pressure can be uniform. At the same time, the pressure contact surface of the heat-sealing knife should be kept clean and free of dirt.
Another reason is that the heat sealing quality of the composite material itself is not good and the heat sealing coefficient changes, resulting in inconsistent temperatures.
5. The sealer walks and stops
In the production, we encountered the failure of the sealer to stop and go, and the speed was inconsistent. The panel on the back of the sealer was disassembled and it was found that the connection between the motor shaft and the gearbox had come off and loosened. Retighten the screws so that they all fit together and the problem is solved. In addition, the main motor is operated by the carbon brush contact. If the carbon brush is seriously worn out, it is not completely in contact with the slip ring, or the friction is not good, it will also cause the sealer to stop and go, and put on the same type of new carbon. Brush to solve the problem.
6. Air bubbles and irregular marks appear on the sealing area
This type of failure is also common. Although it does not cause leakage of the packaging, it affects the beauty of the packaging and destroys the image of the product.
The main causes of this failure are the following two points.
(1) The equipment has been used for a long time. Dust and plastic debris have been attached to the high-temperature belt, causing the high-temperature belt to be not smooth and uneven, making the seal unevenly heated, and bubbles appearing after being pressed by the cold-rolling wheel. Clean or replace the hot strip to remove the fault. The high-temperature zone is generally 1.5 cm wide and about 22 μm thick. If the dirt is stuck on the surface, it must be scrapped.
(2) Irregular irregular marks on the cold-press rubber wheel are directly reflected on the package, so that more noticeable traces appear at the seal. In order to ensure that the packaging bag is beautiful, it is best to replace the cold rubber roller.
7. Issues needing attention in equipment maintenance
(1) The sealer should be placed in a ventilated, dry place. Generally, the sealer can be maintained at about 25°C.
(2) For every 48 hours of operation, 6# oil should be added to each moving part, mainly gears, bearings and gearboxes.
(3) Dust should be regularly cleaned to keep the whole machine clean. When not in use, it is best to unplug the power supply and cover it with a cover cloth.
(4) If the running time is too long, the cooling fan should be turned off before shutting down, and then turned off when the temperature drops. Because it is turned off without cooling, the high temperature belt is easily damaged.
(5) Dirt should be regularly removed at high temperature to ensure the quality of the seal.
(6) Severely worn parts should be replaced in time to prolong the life of the whole machine.
