Plasticizing screw profile
Solid plastic material from the feed hopper into the screw spiral groove (screw channel), due to the rotation of the screw speed with molten plastic tube (barrel) shearing effect role in making plastic materials mixing spiral groove along the screw conveyor, so that solid plastic materials by melting the heater heating the outer tube and the screw under the action of shear heat generated, so that the melt temperature and melt into the internal tube fuse body.
What is the injection molding machine screw? What are the characteristics of the screw?
Plastic product applications and our lives, injection molding and extrusion molding process is currently the most economical and energy efficient way of processing. Wherein the plasticizing screw the most important key component, for each of the physical properties of different plastics, such plasticizing screw design also will be different. For plasticizing screw design, both previously high cost of using rules of thumb are not necessarily solve the problem, so the plasticizing screw in the design of some of the details are worth us to explore and analyze.
Plasticizing screw in accordance with its function can be divided into four areas:
1, the solid conveying zone (solid conveying zone)
This section is linked with the feed hopper, plastic solid particles are tightly compressed to form a solid bed (solid bed), subject to the shearing effect of molten plastic tube action, in addition to the plastic temperature gradually increased, while the plastic forward delivery.
2, the melting zone delay (delay of melting)
This section is solid conveying zone endpoint to melt pool (melt pool) before the formation region, its main feature in the solid bed and melt tube surface will be formed by a melt composed of thin film layer, the thin film layer melt by melting plastic tube viscous force (drag force) Previous screw spiral groove cumulative, this area formed by the end of a lot of pressure sufficient to deform the solid bed, and stacked to form the front screw screw slot gradually melt pool.
3, the solid melting zone (melting zone)
This section of the end zone for the delay to the plastic melt completely melted ended, this area can be divided into two parts to discuss a plasticized (pastication), while plastics mainly from molten plastic tube shear effect effect, and the other is conveying melt (melt conveying), will be transported to the melt melt pool.
4, melt conveying zone (melt conveying zone)
When all the plastic melt completely into this section begins and ends at the end of the plasticizing screw to maintain a uniform temperature and melt stability of the flow of molten plastic.
Plasticizing screw according to the geometrical shape distinguish three sections:
This section is fixed SCREW ditch is deep, its function is responsible for preheating and plastic solids conveying and compacting. Must ensure that the plastic in the feed end of the block starts to melt (that is to warm up to the melting point).
This segment length is divided into crystalline (POM, PA?? Etc.)> non-crystalline (PS, PU, ABS, etc.)> heat-sensitive (PVC, etc.).
Generally:
Non-crystalline: about 48 ~ 58% L ...... (AS, ABS, PS, etc.)
Crystallinity: about 48 ~ 58% L ...... (PA, POM, PE, PP, CA, etc.)
Singapore sex: about 45 ~ 55% L
2, the metering zone (metering zone)
This section is fixed Goushen SCREW ditch, its main function mixing, melt conveying, metering, but also must provide sufficient pressure to maintain a uniform temperature and melt stability of the flow of molten plastic.
Average length is:
Non-crystalline: about 15 ~ 58% L ...... (AS, ABS, PS, etc.)
Crystallinity: about 48 ~ 58% L ...... (PA, POM, PE, PP, CA, etc.)
Singapore sex: about 45 ~ 55% L
3, the compression zone (compression zone)
This section is tapered screw and tooth deep ditch, and its function as plastic raw material melting, mixing, shear compression and exhaust pressure. This section will be completely dissolved in the plastic, the volume will be reduced, so the design of compression (compression ratio) is important.
Average length is:
Non-crystalline: about 25 ~ 35% L ...... (AS, ABS, PS, etc.)
Crystallinity: about 22 ~ 32% L ...... (PA, POM, PE, PP, CA, etc.)
Singapore sex: about 28 ~ 40% L
PVC: 100% L,
Article Source China Machinery Network: www.fktcc.com