What is the auxiliary equipment of the masterbatch twin-screw extruder?

The twin-screw extruder has good feeding performance, mixing and plasticizing performance, exhaust performance, extrusion stability, etc., which has been widely used in the molding and processing of extruded products. Among them, the masterbatch extruder is suitable for the extrusion and manufacture of filled masterbatch, flame retardant masterbatch, antistatic masterbatch, white color masterbatch, whitening masterbatch, black color masterbatch, textile masterbatch, etc. In this article, we will briefly introduce the auxiliary equipment of the color masterbatch twin-screw extruder.

The following is the list of contents

Straightening device

Preheating device

Cooling device

Straightening device

One of the most common types of plastic extrusion scrap is eccentricity. Bending of the wire core in various patterns is an important cause of insulation eccentricity. In sheath extrusion, scratches on the sheath surface are also often caused by the bending of the cable core. Therefore, various extrusion units in straightening devices are essential. The main types of straightening units are drum type (divided into horizontal and vertical); pulley type (divided into single pulley and pulley set); winch-type, which plays various roles such as dragging, straightening, and stabilizing tension; press wheel type (divided into horizontal and vertical), etc.

Preheating device

Preheating of the cable core is necessary for both insulation layer extrusion and sheath extrusion. For the insulation layer, especially the thin insulation layer, which does not allow the existence of pores, the water, oil, and dirt on the surface of the core can be completely removed by high temperature preheating before extrusion. For the sheath extrusion, the main role is to dry the cable core and prevent the possibility of pores in the sheath due to the action of moisture (or moisture around the encapsulated layer). Preheating also prevents the plastic from being extruded due to sudden cooling and residual internal pressure. In the process of extruding plastic, preheating can eliminate the high-temperature heat entering from the cold line and create a temperature overhang at the die opening in contact with plastic to avoid the fluctuation of plastic temperature which leads to the fluctuation of extrusion pressure, thus stabilizing the extrusion volume and ensuring the quality of extrusion. The extrusion unit adopts an electric cable core preheating device, which requires sufficient capacity and ensures rapid temperature rise to make the cable core preheating and cable core drying more efficient. The preheating temperature is limited by the discharge speed and is generally similar to the head temperature.

Cooling device

The formed plastic extruded layer should be cooled and shaped immediately after leaving the head, otherwise, it will be deformed under the action of gravity. The way of cooling usually adopts water cooling and is divided into fast cooling and slow cooling according to the water temperature. Fast cooling is direct cooling with cold water, fast cooling is beneficial to plastic extrusion layer sizing, but for crystalline polymers, due to the sudden heat cooling, it is easy to produce residual stress organization inside the extrusion layer, causing cracking during use, generally, PVC plastic layer using fast cooling. Slow cooling is to reduce the internal stress of the product by placing water of different temperatures in the cooling water tank in sections so that the product can be gradually cooled and shaped. PE and PP extrusion use slow cooling, that is, after three times of hot water, warm water, and cold water cooling.

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