Enhanced extrusion courtesy Control Techniques
October 2011, Motion Control & Drives
A switch from DC to AC drives at European recycling company Govaerts Recycling of Belgium has resulted in major maintenance savings with the bonus of a dramatic cut in production noise. The new high-tech extrusion lines have at their heart modular Unidrive SPMA drives from Control Techniques.
With five production lines, Govaerts Recycling has an annual output of around 8000 tons of high quality plastic and rubber products for street and park furniture, decking and flooring. When the company’s five DC driven production lines were facing the need of refurbishment, owner Eddy Govaerts could not find suitable replacements, so set out to build his own.
Granules of polyofines are blown into the weigh and mixing section, mixed with colouring pigments and other additives to give the mechanical qualities required. This is extruded at 200°C and injected into special moulds. The moulds are cooled, the profiles ejected and then cut to length to produce a wide range of recyclable products.
“Our first extruder lines had DC motors and drives,” says Govaerts. “We bought an off-the-shelf extruder in 1996 to make our first planks and boards for horse stables, but it was not very successful, required many modifications and proved very unreliable. With our wealth of in-house experience in mechanical engineering and automation, we decided to make our own, and with huge success.”
Govaerts Recycling opted for an original concept, four 37 kW water cooled AC motors are all directly connected to the shaft of the gearbox giving total power of 148 kW, but with a saving in size of 70% that eliminates the drive belts and improves overall efficiency by 10%. This new assembly is almost maintenance free with no belts or couplings to fail, no air filters, no lubrication and no protection covers required. “Perhaps most surprising,” adds Govaerts, “is how quiet it is. At full power, the noise is only 40 dbA, about the same as a domestic dishwasher.”
The line’s PLC monitors the motor and water temperature as well as vibration levels. In order to provide a facility for the high level of overload generally required on extruders, each line has two Control Techniques modular, heavy duty 110 kW Unidrive SPMA AC drives – every drive feeds two motors.
The units that make up the SPM range can be used to implement most types of system. The separation of the power circuit into rectifier and drive stages enables elegant and compact active input configurations to be implemented, while the modular nature of the power circuit allows drive systems to be constructed in non-standard enclosures. Configurable in five operating modes – open and closed loop, vector, servo and regenerating – the range is complemented by plug-in module options that extend the on-board PLC with specialist feedback and communication modules.
Govaerts likes the Unidrive SPMA solution because it only requires the user to keep one small module in stock as spare and not a costly drive. The drive has an LCD keypad for text information and incorporates a plug-in Profibus network card for communication with the Beckhoff PLC. The Safe Torque Off function is used to give absolute security for maintenance personnel with a large braking resistor mounted on the top of the cabinet for emergency braking. All of the drives are mounted in air conditioned containers. “Each component in the machine is selected for round the clock service,” says Govaerts. “You cannot buy a machine like this from an OEM because they build to cost. We designed our machine to give the lowest total life cycle cost – long life, low downtime, low maintenance and low energy.
“That is why we select the very best components with the very best value/price ratio. At Govaerts Recycling our philosophy is high quality, quick response, fast deliveries and excellent service. We select only suppliers who have those same qualities, that is why we partnered with Control Techniques. We like that they have the power and resources of a large global group with the spirit and service of a small family company.”
Govaerts Recycling products are used in applications including street furniture, park benches, stable flooring and decking for terraces around pools and spas.
For more information contact Bill Tedd, Control Techniques, +27 (0)11 462 1740, email@example.com, www.controltechniques.co.za