Brownbuilt's mobile mill consists of a de-coiler that feeds the material from a large coil to a series of rollers that shape the material to the required profile. The de-coiler motors and the main motor that drives the rollers have to be synchronised, using a variable speed drive (VSD) and programmable logic controllers. The required sheet cut length data is entered via a touch screen into the second PLC.
This mobile facility had a major impact on the architectural form and construction of such buildings, enabling them to be designed to use a roof sheet of any length. The longest produced to date measured 146 metres.
In what is described by Brownbuilt general manager, Johan van der Westhuizen, as a 'symbiotic relationship', CHI Control has provided the automation equipment that controls the operation of the mobile mill, including periodic upgrading to improve its operation.
Of particular value in that relationship has been CHI Control's network of personnel and branches throughout the area, which has facilitated on-site maintenance of the mill. "The mill travels far and wide to different sites across southern Africa and the equipment does not like bouncing over rough roads," Van der Westhuizen explained. "CHI has been able to respond quickly with the necessary expertise to help sort out any problems that may have developed whenever and wherever we have been operating."
Breakdown response
A typical example of that response was to a breakdown call received at CHI in Wadeville at 2 pm on a Friday. A technician got in his car and was on site in Kimberley early the following morning to diagnose a fault in the cable between the variable speed drive and the de-coiler motor. He ran an umbilical cable between the two to get the mill operational until the cable could be replaced at a later stage.
In a second case, this time in Port Elizabeth, the mill was stopped at the end of a shift and would not start on automatic the following day. Local support provided by ALSTOM Automation in Port Elizabeth found that the rough ride to the site had caused a wiring loom to be shaken from its mooring, loosening some of the connections to the motor. After correcting the fault and replacing some starter switches, the mill was running again within four hours.
CHI Control also provides constant technical support with automation design. During annual maintenance last December, it recommended upgrades for the mobile mill, which doubled the mill speed. A new mill is currently under construction, incorporating automation features that have proven successful as well as several new ideas.
"The material design philosophy we employ today is totally different from that which was previously available," Van der Westhuizen said. "We have solved problems of work hardening, stress and metal stretch which, in the original design, resulted from pulling on the decoiler. The method we are using now results in a better product. In addition, we can now handle a wider roll of material, which means fewer stoppages and being able to complete a job that much sooner."
More on Brownbuilt
Brownbuilt's first project was Johannesburg's Fresh Produce Market, erected in the late 1960s. Since then the company has supplied sheeting for a number of industrial buildings across southern Africa, including various buildings such as shopping centres and casinos. In fact, whenever one sees a large, low-pitch roof, the probability that a concealed fix roofing system was used, is high.
Brownbuilt was the first company in South Africa to use a mobile mill to roll continuous lengths of roofing and side cladding for industrial buildings on site. Its product range includes a variety of profiles, including several interlocking, concealed fixing designs, as well as gutters and fascias. A pioneering spirit, reflected in its continuing development and application of leading-edge technology, has enabled a company based in Boksburg North to maintain a commanding lead over its competitors in the field of roofing for large industrial and other buildings.
Since starting out in 1964 as a small factory in Anderbolt, manufacturing a single product, Brownbuilt, a division of Global Roofing Solutions, has expanded its range to cover a wide spectrum of roofing products, as well as a permanent shutter product for decking.
Global Roofing was established by the Dorbyl Group in the mid-'90s, with Brownbuilt and a second division, HH Robertson, operating in competition with each other. Following a management buy-out, Global Roofing Solutions became a (Pty) Ltd company and both divisions began working together, focusing on different markets.
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