Liquid Injection Barrel

Core Function

The liquid injection barrel is used to inject liquid material into the interior of the extruder during the mixing, such as oil filling in the TPV process, entrainer (water/alcohol/acetone) in the maleic anhydride low-VOC process, and so on.

Types

1. Integral barrels:
   • The integral barrel has no seams and has good corrosion resistance. The materials can be nitrided steel, 304/316L stainless steel, Hastelloy C, etc.
2. Combined barrels:
   • The combined barrel is composed of two parts: the outer shell and the liner. The material of outer shell is usually 45# steel, but it can also be customized to nitrided steel or stainless steel according to customer requirements. Liners are further classified into C liner and integral liner. C liner offers high cost performance and is suitable for simple blending, such as high-filling, engineering plastics, etc. The material of integral liner is available in two types: α101 and HIP. The former is wear-resistant and has a high cost performance; the latter is both wear-resistant and corrosion-resistant, but the imported materials are expensive.
   • For example, when processing peek/pps, the temperature is very high. To prevent the outer shells and liners from cracking due to inconsistent expansion coefficients, it is recommended to use a nitrided steel shell and an integral liner.

Components

As shown in the above figure, this liquid injection barrel is a combined barrel, consisting of an outer shell and an integral liner. There are many enamel holes on the protruding surfaces on both the left and right sides of the barrel shell, which are used for connection and reinforcement with other barrels. The upper side of the shell is reserved with a liquid injection port for injecting liquid raw materials. The lower side of the shell is reserved with a placement opening for thermocouples and the inlet and outlet of the water channel. The interior of the liner is a screw chamber. The entire screw is suspended in this hollow position, leaving a bit of a gap between them without touching each other. Generally, the liquid injection barrel needs to be equipped with an external liquid injection device or a liquid injection gravimetric feeder for normal use.