TPT January 2010

H eat and S urface T reatments

New heating and cooling technologies in pipe thermoforming processes

The socket thermoforming processes of plastic pipes use several different heating, forming and cooling techniques. Heating with short-wave infrared heating elements, IR-SW ovens, combined with new and efficient cooling systems with internal refrigerating cycle (Sica patent), are a new technical concept for socketing machines. The systems are used in socketing machines for both PVC-U and PP or HDPE pipes, and are adapted and optimised according to the specific processing technologies necessary for the different materials. Their combination has been installed recently in Sica machines. The new systems can also be applied on BA/ CA socketing machines already installed in existing extrusion lines. Advantages include the reduction of the number of heating stations while maintaining the same production capacity, resulting in a smaller socketing machine, simplified operating management, and better operator accessibility. It is claimed that, in this way, a single-oven socketing machine can attain output equal to or higher than those of traditional double-oven socketing machines. IR-SW ovens introduce constructive solutions, a particular layout of the heating elements and logic to control and optimally distribute the radiated heat on the pipe. The advantage of heating time reduction with IR-SW ovens is especially apparent with medium and thick walled pipes. The IR-SW ovens offer low energy consumption, versatility and high adaptability to pipes with different diameter and wall- thickness, and low and simple maintenance. Operation is not influenced by initial pipe temperature. The ovens allow reliable control of pipe heating quality, resulting in lower product waste. The installation of IR-SW ovens on belling machines can bring important advantages, reducing not only heating time but also socket forming and cooling times. In order to attain these operating conditions, Sica developed and patented a fluid treatment system for socket forming and cooling inside the forming mould. The new Sica process enhances the reutilisation of compressed air for forming with an additional thermodynamic treatment performed directly on the forming compressed air with a special refrigerating cycle integrated in the socket forming system. In order to further increase the system’s refrigerating capacity, it can

be equipped with controlled water spray. New Sica socketing machine models are also available to process compact, smooth wall or multi-layer PVC-U pipes. These models are available in different sizes, up to maximum diameters of 250, 400, and 500mm. The Unibell 1 model is configured with one IR-SW oven, and Unibell 2

Sica’s Unibell socketing machine

is equipped with two IR-SW ovens. The machines form sockets with internally calibrated ring seat, by means of mechanical mandrel or Rieber cycle, and are equipped with a quick-change belling tools system. The new systems can also be used in socketing machines for smooth polyolefin pipes, in particular for multilayer pipes for outdoor sewer or indoor soundproofing sewer. The Everbell H range is available in different models, according to the pipe maxi- mum diameter: 200, 315, 500 and 630mm. The machines are equipped with two heating stations: the first has an IR-SWoven, the second a standard contact oven. In this

way, the IR-SW oven reduces heating times, while the contact oven renders uniform the thermal condition and stabilises the material temperature with little variability (±1°C). The machines are equipped with a single socket forming-cooling unit. The forming cycle is PSP, a Sica patented system that allows internal socket calibration. The forming process is enhanced during cooling thanks to an internal refrigerating cycle system. Sica SpA – Italy Fax: +39 0544 81340

Email: info@sica-italy.com Website: www.sica-italy.com

The Everbell 200H

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J anuary 2010

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