Screw without compression ratio

Abstract

A screw without a compression ratio is installed in a machine barrel and comprises a feed section, a compression section, a homogenization section and a pin head. The volume of a single screw groove of the compression section is larger than that of a single screw groove of the feed section. . The volume of a single screw groove of the homogenization section is equal to that of a single screw groove of the compression section. The screw pitch of the compression section is larger than that of the feed section. The screw pitch of the homogenization section is larger than that of the compression section. The depth of the single screw groove of the homogenization section is smaller than that of the single screw groove of the compression section. The screw groove of the homogenization section isa double-side groove, wherein the partial groove depth in the screw groove is in a shallow-thin change. The screw groove of the homogenization section is wavy. The overall compression ratio of the screw changes within the range of 1.7 to 2.5. The equal-volume screw grooves are adopted for the compression section and the homogenization section of the screw, after fibers are added in, spiral pushing in the isochoric process can be achieved, high shear brought by sudden volume change is avoided, loss of fiber length is reduced greatly, the compression ratio of the screw is low, a strong shear effect is avoided, and breakage of the long glass fibers is reduced greatly.

Description

technical field [0001] The invention relates to the technical field of equipment for forming and processing fiber-reinforced polymer-based composite materials, in particular to a screw with no compression ratio. Background technique [0002] Compared with the traditional short glass fiber reinforced thermoplastic (SFT), the length of glass fiber in the long glass fiber reinforced thermoplastic (LFT) product is longer, and forms a reinforced skeleton network, which greatly improves the reinforcement effect and gives the product more excellent Mechanical properties, dimensional stability and temperature resistance make LFT widely used in the automotive industry, household appliances, industrial equipment, communication facilities, outdoor products and other fields. [0003] At present, the injection molding methods for producing long glass fiber plastic (LFT) products can be divided into two types: online compounding method and direct injection molding method of LFT pellets; o...

AI Technical Summary

Problems solved by technology

[0007] 1. Melt pressure seriously affects glass fiber breakage. The higher the melt pressure, the greater the shear strength, and the more severe the glass fiber breakage;

[0008] 2. From the feeding section to the homogenizing section, the volume of the traditional screw channel changes greatly, high compression, and the melt pressure changes drastically, which seriously damages the glass fiber;

[0009] 3. The glass fiber is conveyed in the screw in the form of laminar flow. Even the pin mixing head cannot realize the glass fiber "trough top-trough bottom" flip, and the glass fiber clusters cannot be rubbed apart, which is not conducive to the dispersion of glass fiber

[0010] Therefore, the traditional plasticizing system has caused severe damage to the glass fiber, and the residual length is even less than 1mm, which cannot meet the requirements of long glass fiber

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