Focus on extrusion, granulation screw barrels design and manufacturing
What is the screw barrel of an injection molding machine？
2021.11.12
The screw is an important part of the injection molding machine. Its function is to transport, compact, melt, stir and apply pressure to plastics. These procedures are completed by the rotation of the screw in the barrel. When the screw rotates, the plastic will generate friction and mutual movement on the inner wall of the barrel, the bottom surface of the screw groove, the screw edge advancement surface, and the plastic and the plastic. The forward advancement of the plastic is the result of this combination of movements, and the heat generated by the friction It is also absorbed to increase the temperature of the plastic to melt the plastic. The structure of the screw will directly affect the extent of these effects. In order to improve the quality of plasticization, the screw can be designed as a separation type screw, a barrier type screw or a split type screw.
Type of screw barrel for injection molding machine:
1. Features of gradual gradual change screw: The compression section is longer, the energy conversion is gentle during plasticization, and it is mostly used for PVC and other plastics with poor thermal stability.
2. Features of mutant mutant screw: The compression section is short, and the energy conversion is more intense during plasticization. It is mostly used for polyolefin, PA and other crystalline plastics.
3. Features of general-purpose general-purpose screw: The general-purpose screw with strong adaptability can be adapted to the processing of a variety of plastics and avoid frequent screw replacement.
Material of manufacturing barrel:
At present, the commonly used materials in China are 45, 40Cr and 38CrMoAIA. The material for the barrel of the imported extruder is commonly used alloy steel 34CrAINi and CrMoV9. The yield strength of this material is about 900 MPa. After nitriding, the hardness is above 1000HV, which is abrasion-resistant and has good corrosion resistance. Tungsten carbide alloy barrel, tungsten carbide alloy + chromium alloy barrel, tungsten carbide alloy + chromium alloy + nickel alloy barrel, using Material alloy steel as the base material, and casting the above alloy in the inner hole to improve the wear resistance and resistance of the barrel Corrosion performance.
Daily maintenance of the barrel:
1. Do not start the machine when the barrel screw has not reached the preset temperature. Prevent metal fragments and debris from falling into the hopper. If processing recycled materials, a magnetic hopper should be added to prevent iron filings from entering the hopper.
2. Make sure that the plastic in the barrel is completely melted when using anti-salvation to avoid damage to the transmission system parts when the screw retreats. When using new plastic, the remaining material in the barrel should be cleaned. When the temperature of the molten plastic is normal but black spots or discoloration of the injection product are constantly found, check whether the screw head, rubber ring, and rubber meson are worn. When the product is injection molded, try to make the material evenly plasticized to reduce the transmission torque of the screw and increase its service life.
Type of screw barrel for injection molding machine:
1. Features of gradual gradual change screw: The compression section is longer, the energy conversion is gentle during plasticization, and it is mostly used for PVC and other plastics with poor thermal stability.
2. Features of mutant mutant screw: The compression section is short, and the energy conversion is more intense during plasticization. It is mostly used for polyolefin, PA and other crystalline plastics.
3. Features of general-purpose general-purpose screw: The general-purpose screw with strong adaptability can be adapted to the processing of a variety of plastics and avoid frequent screw replacement.
Material of manufacturing barrel:
At present, the commonly used materials in China are 45, 40Cr and 38CrMoAIA. The material for the barrel of the imported extruder is commonly used alloy steel 34CrAINi and CrMoV9. The yield strength of this material is about 900 MPa. After nitriding, the hardness is above 1000HV, which is abrasion-resistant and has good corrosion resistance. Tungsten carbide alloy barrel, tungsten carbide alloy + chromium alloy barrel, tungsten carbide alloy + chromium alloy + nickel alloy barrel, using Material alloy steel as the base material, and casting the above alloy in the inner hole to improve the wear resistance and resistance of the barrel Corrosion performance.
Daily maintenance of the barrel:
1. Do not start the machine when the barrel screw has not reached the preset temperature. Prevent metal fragments and debris from falling into the hopper. If processing recycled materials, a magnetic hopper should be added to prevent iron filings from entering the hopper.
2. Make sure that the plastic in the barrel is completely melted when using anti-salvation to avoid damage to the transmission system parts when the screw retreats. When using new plastic, the remaining material in the barrel should be cleaned. When the temperature of the molten plastic is normal but black spots or discoloration of the injection product are constantly found, check whether the screw head, rubber ring, and rubber meson are worn. When the product is injection molded, try to make the material evenly plasticized to reduce the transmission torque of the screw and increase its service life.
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