Injection molding machine barrel screw design principles

Update:29-06-2018
Summary:

Injection molding machine barrel screw design principle […]

Injection molding machine barrel screw design principles:

The main part of the pin screw is an ordinary screw, and the pin can be set in the melting section of the screw or the groove of the metering section or the smooth cylindrical surface without the groove at the end of the metering section. Pins are arranged in a certain arrangement, which can vary in density and quantity. The cylindrical pins are formed by fitting the pins into the holes of the screw; the square or diamond pins are formed by milling directly on the screw.

If these pins are located in the melting zone, the pins can break down the solid bed, destroy the two-phase flow, and stir the solid and liquid phases to increase the contact area between the fragments of the final dissolved solid phase and the contained materials. Melting. If the pin is set in the melt delivery zone, its main role is to divide the stream, increase the interface, change the direction of the stream, and rearrange the streams. Multiple splits, confluences, change the direction of flow, and homogenize the melt composition and temperature.

The mixing section is an inward grooved structure provided at the end of the normal screw homogenizing section, and its outer diameter is equal to the outer diameter of the screw. Grooves are divided into several groups, each of which is a confluence area of ​​materials. The material is divided by grooves, meets in the confluence zone, and then is divided and merged. The principle is similar to that of the pin type.

The characteristics of the separate screw is that in addition to the original one screw pattern (called the main screw) on the melting section, a thread (called additional thread) is attached, and its outer diameter is slightly smaller than the outer diameter of the main thread. The lead is different. The secondary thread starts from the end of the charging section (and is connected with the feeding section). After several threads, it gradually intersects with the main thread of the homogenization section.

The screw groove depth and the thread lead of the screw are gradually changed from the feed section to the homogenization end. Both the thread lead gradually narrows from the width and the depth of the screw groove gradually decreases from the depth, so that the material can be maximally compressed.