Product features of hydraulic screen changer

The characteristics of the screen changer are that it does not need to stop the machine, reduces the labor intensity of workers, improves production efficiency, and also reduces the generation of waste. However, many people do not know much about the single-plate screen changer. Today, I will share with you the characteristics of the hydraulic screen changer.

Improve the cleaning effect of the screen changer
The cleaning of the screen changer is divided into three steps: TEG cleaning, high-pressure water gun cleaning and ultrasonic cleaning.
To extend the cooking time of triethylene glycol, triethylene glycol is a colorless, transparent, neutral oily liquid with a boiling point of 276°C. After heating, it has an alcoholysis and dissolution effect on polyester. Triethylene glycol cleaning is to dissolve the polyester melt on the screen changer by heating and cooking under the action of triethylene glycol solvent. The melt filter element just removed, wrapped with polyester melt, must be cooked in the TEG cooker and taken out at 285°C for 4H; when the filter element is removed, it is found that some melts cannot be completely dissolved. Therefore, the constant temperature time is increased from 4H to more than 6h to dissolve all the melts adhering to the filter element; at the same time, the secondary TEG cooking method is adopted, that is, the removed filter element is loaded into the hanging basket for secondary cooking, so as to further improve the cooking cleaning effect.
Strengthen the cleaning of the TEG cooking filter element with a high-pressure water gun. Because it is dirty, it must be cleaned with a high-pressure water gun. However, an external filter changer is used, and impurities still remain in the outer layer of the filter. Therefore, a special high-pressure water gun is needed to flush the impurities from the inside to the outside. At the same time, the outer protective cover of the filter element is removed to enhance the cleaning effect. In order to clean the filter element to a large extent, 10 filter elements are randomly taken out from a group of filter elements, and 5 outer iron covers are removed randomly, and the filter element is cleaned with a high-pressure water gun, and then the filter element is cleaned with ultrasonic waves for 2 hours, and the bubble point test is performed. The comparison results are shown in Table 2. It can be seen that in the high-pressure water gun flushing and ultrasonic cleaning stages, it is easier to clean the filter element by removing the outer iron cover of the filter element.
In order to strengthen ultrasonic cleaning, small molecular impurities are easy to squeeze into the filter element under high pressure, and it is difficult to flush them out with a high-pressure water gun, so it is necessary to perform ultrasonic cleaning. In order to find a better cleaning time, a set of experiments was conducted, and the results are shown in Table 3. Increasing the ultrasonic cleaning time alone is not a better method. Therefore, the ultrasonic cleaning time can be set at 2 to 3 hours.

After ultrasonic cleaning, some impurities are removed, but some remain in the filter. In order to remove this part of the impurities, a 1.6Mpa steam backwashing production line was established to remove internal impurities to a large extent. Practice has proved that the effect is remarkable.

Daily maintenance of the screen changer:
1. Under no circumstances is it allowed to install, remove the filter and adjust the structural parts when the oil pump motor is rotating.
2. When the equipment is not used for many days and restarted, first check whether the screen changer is sensitive and reliable.
3. It is strictly forbidden to push and pull the filter repeatedly under high temperature and without lubrication to avoid damaging the matching surface.

4. During normal production, a small amount of molten material should overflow on both sides of the slide plate of the granulator automatic screen changer. For the convenience of lubrication, if there is no overflow or when it is newly installed, silicone oil should be used to lubricate both sides of the slide plate when replacing the screen.

The operating tip for a screen changer is to optimize the number of heating sections, which is necessary to balance the temperature on the screen changer. More specifically:
1. Three sections are best with one integrated section at each end of the slide, and two separate sections with two sections. Many processors connect these converters to separate control sections, causing the slide to heat too much or too little. This will make the temperature distribution of the melt unstable and cause the material to burn in the offline circuit breaker.
2. For continuous bolt-on screen changers, it is usually best to use a single control end, but when the size of these machines increases, additional body sections are needed to help balance the heating. Bolted continuous screen heat exchangers heat the bolts by heat conduction from the body. If the heat is not balanced, the body can shrink to the bolts to produce a high enough clamping force to prevent the bolts from moving.

3. For the die sleeve of the machine, it is usually best to use a separate heating controller. However, this will vary with size.

As screen changers age, leakage is a problem faced by almost all screen changer designs, especially slide-type screen changers. This type of screen changer relies on manual adjustment or pressure to activate the seal and is subject to factors such as wear caused by the movement of the slide plate, degradation of the seal pressure ring, and damage to the filter screen. Maintenance of these mechanical seals can range from once a week to once a year. Maintenance requires disassembly and assembly, which is a time-consuming and expensive process. It is important to keep the slide plate clean before servicing to prevent polymer leakage into the circuit and other equipment.

Increasing the head pressure is one way to reduce leakage in such systems to a large extent. Your instinct will tell you that it is better to reduce the pressure because it will put less stress on the system. However, since the seals are designed to respond to extrusion pressure, they only work at the peak when the pressure is high. At lower pressures, the seals will loosen slightly. When the extruder is idling or running at a declining speed, less pressure is applied to the seal and low-viscosity materials tend to leak out. The updated slide plate seal uses an all-steel segmented pressure ring design to solve this problem and provides a lifetime leak-free guarantee regardless of temperature and low viscosity. This is the first time that the seal operates leak-free in high-temperature coating applications.

In bolt-on or other close-tolerance rotary screen changers without mechanical seals, biological materials can leak over time. Leaks in these precision machined wire changers are almost always caused by mechanical damage, so they are usually designed for a fairly narrow range of material viscosities. Therefore, you should not use a screen changer with gaps designed for high pressure and high viscosity on a low viscosity process without approval or modification from the supplier.