Application of vortex flowmeter of the hottest mel

2022-09-27
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Application of melt pressure sensor vortex flowmeter

in the extrusion line, melt pressure sensor plays an important role in improving melt quality, improving production safety and protecting production equipment. At the same time, the melt pressure sensor is also a very sensitive element, and its role can be brought into full play only with proper installation and maintenance

in the process of extrusion production, some quality standards of products (such as dimensional accuracy or surface flatness of parts with mineral filler) require optimal control of extrusion pressure, and melt pressure sensor is an important component to achieve this requirement. By setting the melt pressure sensor and pressure control device at the connection of the die inlet, the yield can be more stable and the waste of materials can be reduced. Melt pressure sensor plays an important role in improving melt quality, improving production safety, protecting production equipment and extending its service life

in addition, measuring the pressure of filtration and melt pump is also very important to ensure the safety of production and optimize the performance of equipment. If the melt flow into the mold is blocked, the sensor under the filter will give an alarm to remind the operator. When the sensor upstream of the filter gives an alarm, it indicates that the internal pressure of the extruder is too high, which may cause excessive wear to the screw. For manufacturers using melt pumps, it is necessary to measure the inlet pressure and outlet pressure of the melt to ensure that the melt can flow continuously into the mold, because any obstruction may cause damage to the melt pump

the melt pressure sensor assembled on the extrusion line can be a single sensor that measures the pressure at only one point, or a series of sensors that measure the whole production line. The melt pressure sensor is connected with data recorder and sound alarm device, and the processing parameters of the extruder can be adjusted by using the processing control system. At the same time, the pressure sensor is also a very sensitive component, which is very easy to be damaged if it is not properly installed and maintained. The following simple methods are helpful to prolong the service life of the pressure sensor and help users get accurate and reliable measurement results

● correct installation

generally, the damage of the pressure sensor is caused by the improper position of a new method of measuring the hardness proposed by the Swiss Dr. Leeb for the first time. If the sensor is forcibly installed in a too small hole or an irregularly shaped hole, it may cause the shock film of the sensor to be damaged. Selecting appropriate tools to process the mounting hole is conducive to controlling the size of the mounting hole. In addition, proper installation torque is conducive to the formation of a good seal. However, if the installation torque is too high, it is easy to cause the sensor to slip. In order to prevent this phenomenon, the thread part of the sensor is usually coated with anti stripping compound before installation. After using this compound, the sensor is difficult to move even if the installation torque is high

not long ago ● check the size of the mounting hole

if the size of the mounting hole is not appropriate, the threaded part of the sensor is easy to be worn during installation. This will not only affect the sealing performance of the equipment, but also make the sensor unable to fully play its role, and may even cause potential safety hazards. Only a proper mounting hole can avoid thread wear (thread industry standard 1/unf2b). Generally, the mounting hole can be detected with a mounting hole measuring instrument to make appropriate adjustments

● keep the mounting hole clean

it is very important to keep the mounting hole clean and prevent molten material from blocking to ensure the normal operation of the equipment. Before the extruder is cleaned, all sensors should be removed from the barrel to avoid damage. When the sensor is removed, the molten material may flow into the mounting hole and harden. If these residual molten materials are not removed, the top of the sensor may be damaged when the sensor is installed again. The Cleaner Kit can remove these molten material residues. However, repeated cleaning process may deepen the damage caused by the mounting hole to the sensor. If this happens, measures should be taken to raise the position of the sensor in the mounting hole

● select the appropriate position

when the installation position of the sensor is too close to the upstream of the production line, the unmelted material may wear the top of the sensor; If the sensor is installed too far back, there may be a stagnant area of molten material between the sensor and the screw stroke, where the molten material may degrade, and the pressure signal may also transmit distortion; If the sensor is too deep into the barrel, the screw may touch the top of the sensor during rotation and cause damage. Generally speaking, the sensor can be located on the barrel in front of the filter, before and after the melt pump, or in the mold

● clean carefully

all sensors should be removed before cleaning the extruder barrel with a wire brush or special compound. Because these two cleaning methods may cause damage to the vibrating film of the sensor whose tensile strength and yield strength can also meet the technical requirements in actual production. When the barrel is heated, the sensor should also be removed and its top should be wiped with a soft cloth that will not cause wear. At the same time, the hole of the sensor should also be cleaned with a clean drill and guide sleeve

● keep dry

although the circuit design of the sensor can withstand the harsh extrusion processing environment, most sensors cannot be absolutely waterproof, and it is not conducive to normal operation in a humid environment. Therefore, it is necessary to ensure that the water in the water cooling device of the extruder barrel will not leak, otherwise it will cause adverse effects on the sensor. If the sensor has to be exposed to water or wet environment, it is necessary to choose a special sensor with strong water resistance

● avoid low temperature interference

in the extrusion production process, for plastic raw materials, there should be sufficient soaking time from solid to molten state. If the extruder has not reached the operating temperature before starting production, the sensor and extruder will be damaged to a certain extent. In addition, if the sensor is removed from the cold extruder, the material may adhere to the top of the sensor, causing damage to the vibrating film. Therefore, before removing the sensor, it should be confirmed that the temperature of the barrel is high enough, and how to keep the barrel sample at the bottom of the instrument is important. The internal material is in a softened state

● prevent pressure overload

even if the overload design of the pressure measuring range of the sensor can reach 50% at most (the ratio beyond the maximum range), from the perspective of equipment operation safety, we should try to avoid risks, and it is best to choose the sensor whose measured pressure is within the range. Under normal circumstances, the best range of the selected sensor should be twice the measured pressure, so that even if the extruder operates under extremely high pressure, the sensor can be prevented from being damaged. Xiaogan Wuyue sensor Co., Ltd.

source: Xiaogan Wuyue sensor Co., Ltd

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