The Machines of a Pipe Extrusion Line

The machines of extrusion systems are using for a lot of area which agriculture, infrastructure, construction, industry and such as medical.  So the extrusion machines are without doubt indispensable for this world. In this article, we will descibe pipe extrusion machines.

A pipe extrusion line consist of different machines :

Extruder

The extruder selection is made according to plastic raw material to it will process. For example, twin screw extruder is used for rigid PVC powder raw material. Single screw extruder is used for LDPE, LLDPE, MDPE, PP, PA raw material. 

Extruder converts raw plastic material into a continuous tube shape melt by extrusion through die head. Screw desing is very important for this process.

Screw design is very important for this process. Because the plastic raw material should reach the most suitable dough consistency without any degradation. An extruder that does not have a correct screw barrel design may lead to deterioration of the chemical and physical properties of the plastic material. 

The other most important effect of the screw barrel design (for example L/D ratio) is that it directly affects the hourly production capacity. Kg/h capacity is an important parameter for cost analysis of manufacturers.

The other most important equipment of the extruder is the motor and reducer. They provide the speed and torque required for the processing of plastic raw materials. Ztech brand gearboxes provide high torque and long service life for counter-rotating twin screw extruders.

Die-Head

In the die head design there is much of the important of a material properties. It can be a type porta mandril, with spiral, or lateral feed. Each of these designs provides a different melt flow. According to pipe properties, the die heads can be one and three layer.

Calibration Sleeves

The calibraton sleeves are used to for give tube shape and determine to pipe outside diameter by vacuum of pipes. The calibration desing  is made according to pipe properties. For example the shrinkage ratio is changing raw material and pipe thickness.

Vacuum and Cooling Tanks

The plastic melt is entering through a calibrator while its surface is cooled enough to maintain the dimension and a circular form of the pipe by the vacuum and cooling tanks. After pipe exits from the calibration sleeve inside the cooling process will continue by spraying water to the pipe so that it maintains its circularity before it exits the vacuum tank. By spray or immersion baths you can cool it down. The spray tanks is used for pipes with large diameter, where production speeds are low and the spray can achieve effective cooling. In the immersion the tube passes through a water-filled tanks in constant cooling.

Other a importance of cooling, lies in the stability that acquires the plastic pipe to not deform when passing through the haul off unit, where the pipe is subject to pressures that could produce alterations in the circular shape required.

Depending on the thickness and size of the pipe, the length of the vacuum tanks types.

Haul-Offs

Once cooled , it pass to the haul off unit, which generates all the strength which, to put it in some way, pulls the pipe in order to extract it from the extrusion line.

Important parameter for the haul-offs, it maintains the thickness of the pipe by constant pulling speed. The haul-off works in a fully synchronize mode with the extruder’s capacity to maintain the thickness of the pipe.

Depending on the type and size of the pipe, different models of the Haul-off machines are used, for example,for sizes  from  to 22 mm pipes band type, for sizes 16mm to 63mm, two pallets (double caterpillar) are used. For larger pipes, we use haul-offs that have three caterpillars, four caterpillars, six caterpillars.

Cutter

When choosing the cutting machine must be taken into account the diameter and wall thickness, the raw material used, the shape, quality and the length of the cut.

ZPT Planetary Cutters generally use for rigid PVC pipes, the blade is inside a moving wagon which moves fully synchronize to pipe line’s speed. During a cycle, the wagon starts to move from zero position (home position) and simultaneously the blade inside the wagon rotates in circumferences of pipe and cutting will occur in this cycle.

ZTT fixed blade cutters ideal for PE pipes; It cuts without removing any shavings and therefore produces neither dust, shavings nor noise. To avoid the formation of residues, it is used a mechanisms where the blades are inserted in the wall of the tube and spin at high speed, producing only a strip of shavings but preventing deformations.

Coiler

The coiler machines are used for polyethylene pipes which are sold coiled form. Used for up to 63 mm size pipes two station coiler, 63 to 110 mm pipe single station coiler.

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