Corrugator
A corrugator (engl .: corrugated , dt .: corrugated) is a machine, mainly for the production of corrugated plastic pipe is applied. Other similar continuous products can also be produced on corrugators, e.g. B. Fasteners for pipes. The process is assigned to blow molding .
Main ingredients
Spray head
The injection head, also known as the nozzle, transforms the melt flow from the extruder into a hose and is mainly responsible for the accuracy of the wall thicknesses. The wall thickness can be adjusted via the nozzle gap. The power supply (water, vacuum, air) for the cooling mandrel and the supply line for the molding air run through the spray head.
Cooling mandrel
A cooling mandrel is required to produce a double-walled corrugated pipe with a smooth inner skin. Since the cooling mandrel is supposed to dissipate the heat from the inner skin and to calibrate it at the same time, it is usually made of aluminum and cooled by water. In the case of corrugated pipes larger than 200 mm, an additional vacuum is applied to the inner skin. With correspondingly smaller nominal widths, the contact pressure is only provided by the molding air.
Mold jaws
The mold jaws represent the negative shape of the corrugated pipe. A large part of the thermal energy is extracted from the plastic via the mold jaws. The mold jaws must be able to dissipate the heat well and should not be too heavy. Depending on the manufacturer, these are either liquid-cooled or air-cooled. That is why aluminum is mostly used here. The mold jaws are only made of steel on smaller and older models.
Vacuum suction
In modern systems, the plastic hose is sucked into the mold jaws or the cooling mandrel using a vacuum. The use of a vacuum prevents the outer skin from “blowing”. Larger pipe diameters can only be produced with the aid of vacuum suction.
Shaping air
With a simple corrugated pipe, the molding air flows out of the nozzle behind the plastic hose and creates an overpressure there that pushes the melt into the molding jaws. To prevent the molding air from escaping through the pipe, a sealing mandrel is used here, which is connected to the nozzle via a rod and is located in the outlet of the corrugator.
In the case of double-walled corrugated pipes, the shaping air flows out between the outer nozzle and the inner nozzle. The outer skin is thus pressed into the mold jaws while the inner skin is pressed against the cooling mandrel.