The description of PVC pipes extrusion
In external silos providing constant conditions for the storage, raw PVC in the loose form are present. That is why, powders of raw materials are taken and transported with pipelines using pressure method to the mixer, weighted in proper proportion, mixed in hot mixer (to the temperature of 120°C) and cooled in cold mixer (40°C) . Furthermore, the mixture in the solid form is transported with pneumatic pipeline to the silos.
Extruding press is connected to the system of mechanic and pressure transport to each of silo with solid mixture suitable for the pipe type of expected quality and colour. The amount of inflammable dust releasing in the system of extruding press supply is slender (no risk of explosion).
The collar connecting the extruding press and supply pipe is airtight and this prevent from penetrating dust into the hall.
Dry residue is heated in the extruding press (electrical heating + internal friction) and mixed with screws and as a result homogeneous and plastic mass of 170 - 190 °C temperature is formed.
The PVC material is rolled over with electrically heated ring shaped mouthpiece nozzle under the pressure of 200 - 300 Bar in the cylinders and extrusion head, thus forming the pipe shape.
The material, that still remains soft, continually passes through the calibrator of chilled bathtub operating in the negative pressure (-0, 7 Bar), where it is supersaturated to the calibrator that is shaping final form and dimension, sprinkled with cooling water of 13-20 °C temperature and due to it the rigidity and strength is obtained.
Depending on the wall and diameter thickness, the pipe has to pass suitable amount of cooling containers to be chilled.
Some production lines consist of two extruding press. It allows the pipes production made of external coat of solid PVC and middle layer with regranular or expanded PVC.
The speed of broaching behind the extruding press section and cooling bathtubs is synchronized with the extruding press efficiency in such a way to control the thickness of pipes walls. Automatic circulation saw controls the length of cut sections of the pipe, whereby manufactured pipe is delivered to the belling and afterwards the seal and plug is provided, finally the pipe is packed.
Ink-jet printer prints on the pipe the company's name, hour, day, year and other data required by the regulations every meter.
The quality control department gathers the pipes samples on which various laboratory tests are conducted.
Upon verification of the quality, dimensions and pipes looks they are transported to the warehouse located outside of the building.
All products of improper quality are disintegrated with grinding mills and transported to the mixer, whereas they are used again to the production in the clean form or as the addition to main raw materials.
PVC mixture is blended in the portions approx. +/- 300 or 500 kg. Raw PVC which constitutes 60%-80% composition of dry mixture (depending on the recipe) is transported with the use of negative pressure according to the weight system. The scales are also weighting suitable amount of additives that is chalk, stabilizer and modifier. The microadditives are weighted on the scale. colours and waxes. Scales content is dropped to hot mixer, where as a result of friction, the mixture is heating up gradually to the temperature of 120°C, and melting of waxes and stabilizing agents and the mixture homogenization takes place. Reaching the temperature, the valve of hot mixer is opened automatically and the material is dropped to cold mixer. Upon the completion of the process and reaching the temperature of approx 50°C, the mixture is dosed to the transport system and transferred pneumatically to one of silos with dry mixture. Meanwhile, hot mixture is activated again. Dry mixtures are transported to various production lines with a system of supply pipes. Each pipeline is designed to dry mixture of the type (with regard to the hazard of contamination for three types of the mixture).
The description of PE pipes extruding
PE Pipes extruding is conducted almost in the same manner as PVC pipes. The distinction resides in the fact that the material is delivered in the form of granulated product ready for the application and without dust, therefore no mixing devices are required. PE production lines can include up to three extruding presses - one as basic material, one for extruding detection strips and one for applying sliding layer inside of the pipe. Delivered granulated products shall be initially dried in the dryer that blow the material with dry and warm air to remove the moisture. Diameters up to 63 mm are always produced in a reel or on the drum, pipes of 75-110 mm diameter can be delivered as the straight pipes or in a reel. For the purpose, at the end of production lines reeling machines are installed. Instead of Ink-jet printer use the stamping with hot film is applied.
The description of PP pipes pressing
PP (polypropylene) pipes are used for the sewage system inside of the building. Extrusion process is similar to PVC and PE pipes system. They are manufactured in two technologies. Pipes of 110 mm diameter are three-layers with middle layer foamed, however, all other diameters (from 32 to 75 mm) in the solid pipe technology - that is one-layer. The length of manufactured pipes is regulated by construction standards, that is from 150 to 6 m.