Hydraulic screen changer
Product Name:Pressure screen changer (also known as: high-pressure screen changer, dual-station/four-station hydraulic screen changer)
Product positioning:In plastic granulation production lineThe core execution unit of the melt filtration systemInstalledBetween the extruder head and the dieUsed inUnder the premise of full automation, no downtime, and ensuring continuous productionFiltering impurities in the melt and replacing clogged filters are key equipment for ensuring product quality, improving production efficiency, and achieving automated operation.
I. Core Functions and Working Principles
Core functions:
Continuous filtration under high pressure:In the high-pressure (usually 10-50MPa) melt flow at the extruder outlet, the melt is forced to pass through a high-precision filter (such as 20-120 mesh) to effectively intercept solid impurities such as carbides, gel particles, metal shavings, and unmelted materials, ensuring the purity of the output.
Network replacement without shutdown:When filter clogging causes the pressure at the machine head to rise to a set value, the hydraulic system drives the screen changing slide or sleeve.In an instant (0.1-2 seconds), the clogged, dirty screen workpiece is removed from the melt flow channel, while a new workpiece pre-loaded with a clean filter screen is simultaneously moved in.The melt flow is uninterrupted throughout the entire process, ensuring uninterrupted production.
Stable extrusion pressure and quality:By performing rapid and smooth screen changing operations, fluctuations in melt pressure and temperature are minimized, avoiding quality problems such as broken strips, uneven thickness, and reduced output caused by screen changing.
Increase automation level:It can be linked with a PLC to achieve fully automatic operations such as pressure triggering, automatic screen changing, automatic venting, and fault alarm.
Working principle (taking mainstream two-column/four-column type as an example):
There is a sliding part inside the main body of the device.Swapping skateboardThe skateboard has 2 or 4Filtration stationDuring operation, one of the stations performs filtration within the melt flow channel. When the filter at this station becomes clogged, a hydraulic cylinder pushes a sliding plate to move rapidly laterally, removing the clogged station and simultaneously aligning and moving a clean, ready-to-use station into the center of the flow channel. The removed dirty filter station can then be cooled, cleaned, and reinstalled, preparing for the next filter change. The entire process is precisely controlled by the hydraulic system, with the melt flow channel experiencing only a very brief disturbance during the filter change.
II. Main Structural Components
Ultra-high pressure heavy-duty machine body:useHigh-quality alloy steel (such as 34CrNiMo6)Made from a single forging or multiple forgings stacked together, and after precision machining and heat treatment (quenching and tempering, nitriding), it possesses extremely high...Fatigue strength, creep resistance and corrosion resistanceIt can withstand high temperature and high pressure for a long time.
Hydraulic drive system:
Hydraulic power unit:Provides a stable high-pressure oil source, usually equipped withPiston pump, accumulator (used to provide a large flow rate instantly for rapid screen replacement), cooler, precision oil filter。
Hydraulic cylinder:Heavy-duty double-acting hydraulic cylinders drive the screen-changing slide plate to perform high-precision linear motion.
Swapping net skateboard (core moving parts):
Materials and processes:useSpecial high temperature alloy steel, surfaceSuper-hardening treatments (such as boronizing and hard chrome plating)andHigh-precision grindingThis ensures smooth sliding, wear resistance, and reliable sealing under high temperature and high pressure.
Heating and temperature measurement:built-inheating rods and thermocouplesThis allows for precise control of the temperature, consistent with the machine body, preventing the melt from cooling and solidifying at the gaps in the slide plate.
High-efficiency sealing system:
Multi-layer composite seal:use"Metal seal + flexible graphite seal + spring energy storage seal"Multiple sealing combinations ensure absolutely no leakage under long-term high temperature of 370°C and high pressure of 50MPa.
Intelligent control system:
PLC control cabinet:Core control unit, realizingAutomatic/manual control, screen changing pressure/time setting, action sequence control, temperature PID control, fault diagnosis and alarm (such as abnormal pressure, excessive temperature, displacement timeout).。
Human-Machine Interface (HMI):The touchscreen is used for parameter setting, status monitoring, and historical data query.
III. Core Features and Advantages of the Product
Extremely high reliability and security:Designed specifically for extreme operating conditions, eliminating the risk of problems caused by material fatigue or seal failure.Melt leakage (material runaway)In the event of a major safety accident, ensure the safety of personnel and equipment.
Excellent filtration performance and stability:The optimized flow channel design, large filter area, and strong dirt-holding capacity minimize the impact of screen replacement on melt pressure, temperature, and output, resulting in highly consistent product quality.
Fully automated, unmanned operation:Automatic screen changing is triggered based on preset pressure or time, reducing labor intensity and human error, making it suitable for continuous and intelligent production lines.
Ultra-long service life and low maintenance costs:Key components utilize top-tier materials and processes, ensuring a long design life. Modular design simplifies maintenance, and major seals can be replaced online.
Wide range of process adaptability:
Applicable to almost all plastic granulation processes:Production of new and recycled materials such as PP/PE/ABS/PET/PA/PC, including granulation, filler modification, cable materials, and color masterbatch.
Suitable for high viscosity materials:Such as UHMW-PE, TPU, and high-filler materials (calcium carbonate, glass fiber).
Energy saving and efficiency improvement:Non-stop screen replacement avoids the huge energy and time waste caused by traditional shutdown screen replacement, such as heating, cleaning, and feeding, significantly improving equipment utilization and overall production capacity.
IV. Key Application Scenarios and Technical Parameters
Typical application scenarios:
Plastic recycling pelletizing line:Impurities such as sand, metal, and coke in the filtered recycled material are essential for producing high-quality recycled pellets.Essential equipment。
Modified plastics production line:Filter glass fibers, filler aggregates, and gels produced during the manufacturing process.
Color masterbatch and functional masterbatch production line:Ensure that pigments or additives are evenly dispersed and filter out coarse particles.
High-end specialty material granulation:Materials requiring extremely high purity, such as those used in medical devices and automotive parts.
Technical parameters (example):
model:HPH-250 (named after the extruder screw diameter of approximately 250mm that it is compatible with)
Design workload pressure:40-50 MPa (up to 70 MPa or more)
Design operating temperature: ≤ 400°C
Network switching methods:Two-column/four-column hydraulic continuous screen changer
Filter diameter/area:For example, Φ120mm / approximately 100cm² (customizable).
Hydraulic system pressure: 16-21 MPa
Network switching time:0.3 - 1.5 seconds (fast mode)
Control method:PLC fully automatic control with touch screen
V. Selection and Usage Guidelines
Core selection criteria:
Extruder specifications:Screw diameter, maximum output, and maximum working pressure.
Material properties:Melt viscosity, impurity content, and processing temperature.
Filtration requirements:Required filter mesh size and filter replacement frequency.
Spatial layout:The length of the screen changer affects the distance between the die head and the pelletizer.
Usage and maintenance:
Proper preheating:Before starting the machine, the screen changer must be heated to the set process temperature and maintained for a sufficient time to ensure uniform temperature.
Filter preparation:The spare filter screen must be placed correctly (e.g., with a support screen) and installed flat.
Parameter monitoring:Closely monitor the pressure change curves before and after the grid replacement, and optimize the grid replacement trigger pressure setting.
Regular maintenance:Regularly check the quality of the hydraulic oil and the condition of the seals, and clean the slide rails.
