What are the Classifications of Screws?
Screws are mostly used in plastic molding equipment, such as plastic profile extruders, blow molding machines, etc. Screws and barrels are the core components of plastic molding equipment. It is the part of heating and extrusion plasticizing, which is the core of plastic machinery.
The ordinary screw can be divided into three sections in the structure, a feeding section, a gradual section, and a metering section. The three sections are independent of each other and do not overlap. The characteristics are that the aspect ratio (L/D) is (20~30)/1; the length of the feeding section is (4~8)D, and the length of the measuring section is (6~10) D. Its role is to carry out solid transport, melting, melt transport, venting, and mixing of raw materials.
What about the big blow molding machine?
Large containers require large parisons and many melts. Therefore, a new type of screw with strong plasticizing ability, high mixing effect, and uniform temperature should be used.
The new screw can meet the minimum energy consumption, stable pressure, and uniform melt at low-temperature and uniform mixing of various material components to achieve the desired viscosity and dispersion requirements.
The structural characteristics of the new type of screw are relatively large and long, usually 28:1, 30:1 for individual, and 1.0-1.2 for compression ratio. The screw core is provided with a cooling tunnel and is cooled by water. The depth of the groove is deeper, the rotation speed is faster, and the output is greatly increased. In addition, when the screw speed and temperature control are certain, the depth of the screw groove is deep, the shear heat is low, and the temperature of the extrusion material is relatively low, which avoids shearing and overheating of some of the melt, which is beneficial to the quality of the container.
What are the screw types for large blow molding machines?
The split type screw is provided with two main and two threads in the melting section of the screw and constitutes two screw grooves. One groove holds the solid and the other groove holds the liquid. The melt film formed on the inner surface of the solid screw barrel is fed into the liquid screw groove by the rotation of the screw. The homogenization section of the liquid straight-through screw, the length of the homogenization section is correspondingly increased, and the melt-extruded into the inside of the machine head is relatively stable, and the screw has excellent performance.
The barrier screw is a barrier section added at a certain position of the screw to improve the mixing ability. The longitudinal grooves formed in the barrier section are divided into two groups. One group is the feed trough, the outlet is closed; one is the discharge trough, and the inlet is closed. All melt or unplasticized small particles are forced through the barrier ribs. The gap between the ribs is small and the shearing effect is strong. The very fine granules pass through the high shear zone in a short time, the shear rate is large, the fine granules are rapidly plasticized and the melt is further kneaded to obtain a uniform dispersion.
The split type screw is to add a pin or a split block at a certain position of the screw to increase the mixing ability. Pins or diverters play different roles in different locations. The mixing can be improved in the screw homogenization section; the shear rate is increased in the melting section. Although the pin or shunt does not significantly increase the shear stress, it causes disturbances in the velocity distribution, improves material orientation, and facilitates mixing.
Yankang is the biggest blow molding machine manufacturers in China. Focus on the 200L-20000L large water tank blow molding machines. Using a more energy-efficient IKV screw, the blow molding machine has a plasticizing capacity 1.5 times faster than similar products.
The above is the knowledge that Yankang shared with you about the classification of large blow molding machine screws.
More information about the screw of large plastic blow molding machine.
Learn more about blow molding machines, you can click to enter the relevant blog: blow molding machine blog.