The dbf-900 multi-function plastic film continuous sealing machine is favored by small and medium-sized food processing enterprises because of its continuous sealing, stable performance and good sealing effect. This machine has also been widely used in flexible packaging bag making. When the fastness of the side seal, middle seal and bottom seal appears in the plastic film bag, the machine can be used for re-sealing to meet the heat sealing quality requirements.
The machine has been used for a long time, especially under continuous operation and overload conditions, it is prone to some electrical and mechanical failures, such as: inadequate sealing, stop and go of the machine, fuse blown at the start, and a squeak in operation ", Temperature can not be controlled, the finished bag is deformed and bent at the seal, bubbles or irregular marks appear at the seal stamping. This article combines actual use experience, analyzes the causes of several of these failures, proposes corresponding solutions, and explains the maintenance problems of the continuous sealing machine, hoping to help companies and individuals using the continuous sealing machine.
1. The seal is not strong
Unsealable sealing is one of the common faults of continuous sealing machine. There are three meanings of unsealable sealing: ① The sealing position of the packaging bag cannot be sealed; After tearing, the seal will crack again; ③ When the peeling test is performed on the seal, half of the seal is firm and half separated, and the quality of the seal of such a bag is still unqualified because the contents are squeezed during storage Easy to miss. This situation often occurs when the composite lining is opp or blown pe.
The main causes of the first failure are the following.
(1) The heat sealing temperature is not enough
Normally, for compound bags with opp as lining, when the total thickness of the bag is 80 ～ 90μm, the heat sealing temperature should reach 170 ～ 180 ℃; the total thickness of the bag with pe as the lining is 85 ～ 100μm At this time, the temperature should be controlled at 180 ~ 200 ℃. As long as the total thickness of the bag is increased, the heat sealing temperature must be increased accordingly.
(2) The heat sealing speed is too fast
The lack of sealing is also related to the speed of the sealing machine. If the speed is too fast, the sealing part will be transported to the cold pressing part for cooling by the traction roller before it can be heated in the future, and naturally the quality requirements of the heat sealing cannot be reached.
(3) Cold pressure rubber wheel pressure is not suitable
There is one cold rubber roller on top and one on the bottom, the pressure between them should be moderate, and only need to clamp the spring when adjusting the pressure.
(4) There is a problem with the quality of the heat sealing film
The failure to seal the seal is also related to the quality of the heat seal film. If the corona treatment of the composite lining is uneven, the effect is not good, and it just happens to appear at the seal. This situation is rare, but once it occurs, the product is bound to be scrapped. Therefore, in the color printing and packaging industry, the next process supervises the previous process. Once a quality problem is discovered, the cause must be analyzed and resolved in a timely manner. If there is moisture or dirt at the seal, it will also cause the seal to not be secure. In short, to solve the problem of the first type of sealing failure, generally the heat sealing temperature can be appropriately increased, then the heat sealing speed is reduced, and the pressure of the cold-pressed rubber wheel is increased.
The main causes of the failure of the second type of sealing failure are the following.
(1) The heat sealing temperature is not enough
The problem can be solved only by appropriately increasing the heat sealing temperature.
(2) The blade surface of the heat sealing knife is not flat enough
The heat sealing knife is divided into upper and lower pieces. Usually thermocouples are installed in it to sense the temperature transfer. 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. The upper and lower blades have two springs. . The main reason for the uneven surface of the heat sealing knife is that the middle screw is inclined, not horizontal; or the pressure spring of the upper heat sealing knife is uneven.
The solution is to recalibrate the position of the middle screw to make it horizontal. If the upper and lower heat sealing knives are unbalanced, it should be achieved by adjusting the pressure spring, which can be adjusted to a moderate level. When the spring is retracted outward, the heat sealing knife will fall down; when the spring of the lower blade is tightened upward, the heat sealing knife will move upward.
(3) Uneven pressure of cold-press rubber wheel
The uneven pressure of the cold-pressed rubber wheel will also cause the failure of such a tight seal, and the solution is similar to the first case.
There are two main reasons for the failure of the third type of sealing failure.
(1) Uneven pressure of hot sealing knife or uneven pressure of cold pressing knife
The adjustment on the hot sealing knife and the cold pressing knife is exactly the same.
(2) The blade surface of the heat sealing knife is not flat enough
Refer to the second corresponding solution to the failure of loose sealing.
2. Blown fuse
The main motor of dbf-900 multifunctional plastic film continuous sealing machine is produced by Shanghai Hulong Motor Co., Ltd. The main function of this motor is to drive the gearbox and gear transmission of various components. Sometimes as soon as the sealing machine is started, it will make a "squeak" sound, which can't operate normally, and even the fuse on the fire wire is blown.
To eliminate the fault, first check whether the power supply is normal, and then cut off the power supply, use a resistance file to check whether the switch is damaged, and also carefully check whether the circuit and the motor are short-circuited. Usually when the motor is short-circuited, the winding is burned or disconnected, the fuse will blow as soon as the sealing machine is started. Another reason for this failure is that the fuse specifications are too small, and correspondingly increase the specifications to solve the problem. [next]
3. A "squeak" sound appears during operation
This fault occurs during the operation of the sealing machine. The "squeak" sound often occurs suddenly. The next step is the uneven sealing speed, which causes bad texture at the sealing and sealing area of the packaging bag and affects the appearance quality of the product. In the meantime, it can work normally, but it is erratic.
This phenomenon is mostly due to mechanical damage or severe wear and poor lubrication. Some time ago, this phenomenon appeared in the dbf-900 type multi-function plastic film continuous sealing machine used by our factory. We first follow the sound emitted to find the fault location. Remove the back protection plate and find that the "squeak" sound is coming from the gearbox. Remove the fixing screws one by one and find that the grease in the gearbox has dried and the gears are bright, which means that the cause of the failure is Lack of oil. Mix the same type of engine oil and grease into the gearbox, and tighten the screws to recover, the "squeak" sound disappears after booting, and the seal is normal.
In addition, if the joints of the high-temperature belt are loose, severely worn, and are not clean, there is dirt on the surface, they are not synchronized with the traction wheel during operation, and sometimes a "squeak" sound is made. The solution is to replace the high temperature belt with the same specifications. Replacing high temperature comes with certain skills. First compress the pressure wheel spring by hand, and then place one end of the high-temperature belt on the rubber wheel, and the other end is held against the other rubber wheel by hand, set the governor to a low speed, once started, lean on Movement inertia, the high temperature zone is automatically installed.
Sometimes the "squeak" sound is also emitted by the DC shunt motor. It may be caused by lack of oil in the motor bearings. If this is the case, it should be removed and lubricated, the sound can be eliminated.
4. Sealing temperature is out of control
The fault manifests as a thermometer display failure, unable to control the temperature, the heat sealing temperature is not constant, the seal is either scorched, or the seal is not tight, the seal is deformed, and it is ugly.
The main reason for this failure is that the thermometer is broken and must be repaired; in addition, the thermocouple may also be broken, and the induction temperature cannot be transmitted to the thermometer normally. Replace the thermocouple with the same model and specification.
The mechanical reason is that the pressure of the heat seal is uneven, as long as the pressure spring of the heat seal knife is adjusted to make the pressure consistent. 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. Sealing machine stop and go
We have encountered the failure of the sealing machine running around and the speed is inconsistent in the production. The panel on the back of the sealing machine was disassembled and it was found that the connection between the shaft connection of the motor and the gearbox connection has fallen off and slack. Re-tighten the screws to make them all fit, and the problem is solved. In addition, the main motor is operated by carbon brush contact. If the carbon brush is seriously worn, incomplete contact with the slip ring, or the friction is not good, it will also cause the sealing machine to stop and go, and replace it with new carbon of the same model Swipe to solve the problem.
6. Bubbles and irregular marks appear at the seal
This kind of failure is also relatively common. Although it will not cause the leakage of the packaging, it will affect the beauty of the packaging and destroy the image of the product.
There are two main reasons for this failure.
(1) The equipment has been used for a long time, and dirt and plastic debris are attached to the high-temperature belt, which causes the high-temperature belt to be unsmooth and uneven, resulting in uneven heating of the seal, and bubbles appear after being pressed by the cold pressing wheel. The fault can be eliminated by cleaning or replacing the high temperature belt. The high temperature zone is generally 1.5cm wide and about 22μm thick. If the dirt is stuck and cannot be washed off, it has to be scrapped.
(2) Irregularly arranged uneven marks on the cold-pressed rubber wheel are directly reflected on the packaging, causing more obvious marks on the seal. In order to ensure the beautiful appearance of the packaging bag, it is best to replace the cold-pressed rubber wheel.
7. Problems that should be paid attention to in 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 each moving part, mainly in gears, bearings and gearboxes.
(3) Dust should be removed regularly to keep the whole machine clean. It is best to unplug the power supply when not in use and cover it with a cloth.
(4) If the running time is too long, the cooling fan should be turned on before shutting down, and then shutting down after the temperature drops, because shutting down without cooling, the high temperature zone is easily damaged.
(5) The high-temperature belt should be degreased regularly to ensure the sealing quality.
(6) Seriously worn parts should be replaced in time to extend the life of the whole machine.
