The role of the three functional areas of the PVC extruder

The melting temperature of PVC is close to the degradation temperature, so it is necessary to prevent the degradation of PVC melt while it is plasticized well. Therefore, generally according to the work function, the extruder can be divided into two functional areas: the feeding section and the compression section are called the heating area, and the melting section and the metering section are called the constant temperature area. The combined core and die after the extruder are called heat preservation zone.

The functions of three functional areas of extruder are different.

Generally, in normal production, materials enter into the feeding section and compression section. Because the temperature difference between the temperature just entering the extruder and the set temperature is too large, and the shear heat effect is not obvious, mainly relying on the heating ring to provide a large amount of external heat, so the heating ring is required to work continuously, so these two sections are called heating areas. It is mainly composed of external heat supply and screw shearing, calendering and friction to provide heat (the so-called shearing heat refers to the friction heat produced by the material between the screw and the barrel when the screw moves relative to the screw; the calendering heat produced by the bottom of one screw rib and another screw groove; the shearing heat produced by the shearing of the material between two screws). The three heat sources account for the largest proportion due to shear heat, which is generally referred to as shear heat).

The melt enters into the melting section and the metering section through the compression section, and has been basically plasticized, and even there is "shear heat" surplus. The purpose of temperature control in this stage is not to further heat supply, but to timely implement "cooling" when the melt is "over temperature", and transfer the excess heat out. Only when the heat loss of the screw is large, the heat lost is occasionally added, so the two sections are called "constant temperature zone".

When the melt enters the core and die, the shear heat effect no longer exists, because the melt has begun to change from the spiral movement to the linear movement. When the melt reaches the die along the specified flow path of the combined core, it will consume part of the heat. In order to ensure that the melt moves evenly along the swallow tail groove flow path of the die, it is necessary to add appropriate heat. For this reason, the die is set at a slightly higher temperature, so it is called "heat preservation zone".

Jiangsu Xinrongplas Machinery Co., Ltd was a China PVC pipe making machine line supplierswhich founded in year 1996. With continuous focusing on plastic extrusion machinery, we have gained a certain awareness as one of professional PVC pipe machine suppliers. Our main products are: plastic pipe extrusion line, plastic profile extrusion line, plastic sheet extrusion line and plastic recycling machine. We have provided turnkey project for more than 80 countries all over the world. Warmly welcome to visit our workshop, and sincerely hope we can have long term cooperation in near future!