Actuators achieve cutting edge precision
02 August 2012
Linear actuators are playing a vital role in helping a manufacturer of roof panels to eliminate virtually all sources of defects in its machining processes, which in turn has enabled the plant to double its annual production output of ready-to-fit roof components.
Kluth, a private, family-owned company based in Barsinghausen, Germany, specialises in producing sloping roofs made from lightweight materials. Planning, production and customisation to specific sizes are all provided from a single source, giving this manufacturer a unique selling point in this particular corner of the building materials sector.
The roof and its related components such as insulating panels (strips), solid and acoustic fillers, counter slope strips, roof edge strips, vessel segments, joint profile fillers, expansion joint strips and other similar accessories, are manufactured from high quality, DIN-compliant materials such as expanded polystyrene (EPS), polyurethane and mineral wool in compliance with the relevant standards.
In order to ensure the quality of the different construction materials used, Kluth produces the EPS in block form using its own large foam moulding machines. This enables roof panels to be machined to specific customer requirements – a process that runs 12 hours per day, seven days a week. With approximately 830,000 individual roof elements manufactured each year, this involves hundreds of thousands of cutting operations.
The production process for converting large format EPS blocks into customised, high precision Styrofoam parts does, however, place very demanding requirements on the machine builders supplying companies like Kluth.
Indeed, Kluth’s operations require high performance machines with a high level of automation, such as its new EPS cutting machines, which feature computer controlled cutting wire adjustment. Manual adjustment of the cutting wires is out of the question, as this would certainly compromise dimensional accuracy and quality. As Kluth managing director, Marcus Kluth explains, his company is under enormous time and cost pressures and so his machines must be accurate, highly flexible and provide absolute reliability.
The 3,000 x 1,200 x 1,000mm (3.6m3) blocks are trimmed and then divided up according to customer orders. To do this quickly and economically – and with minimum waste – the workforce relies on special machinery and equipment supplied by Dingeldein & Herbert Maschinen-und Apparatebau, a specialist machine supplier to the EPS industry, currently headed up by brothers Markus and Christoph Dingeldein.
The range encompasses not only EPS foam moulding machines but also EPS hot wire cutting machines. The latter are either of conventional design or with oscillating wires, block tilting devices and block conveying equipment, compact hot wire cutting devices, profile cutting machines and pre-crushers, as well as fine grinding mills for processing of cutting waste. The machines are normally built to customer specifications and provided for standardised processes using a certain proportion of standard components and sub-assemblies.
Christoph Dingeldein is well aware that his machines must operate continuously across multiple shifts and thus provide maximum availability. “The machines must also provide high performance and quality, which is why we only fit high quality machine elements and work in close partnership with our customers and suppliers,” he adds.
The EPS blocks are separated systematically into specific customer orders into ready-to-fit roof elements and the cutting operation is mostly automated. In order to adjust the cutting wires automatically at high speed and with repeatable accuracy, as well as with minimal set-up time, two Schaeffler MKUVE20-B-ZR linear actuators are used. These adjust the individual cutting wires under software control, either in parallel or, where necessary, obliquely (when specially formed panels/strips are required).
The MKUVE20-B-ZR comprises an inherently rigid aluminium support rail and fully integrated linear guidance system, in a combination that provides a high load carrying capacity. The compact linear actuator includes linear recirculating ball bearings and guideway assemblies plus two carriages. This enables moderate loads, combined with high static loads about all three axes, to be moved with high positional accuracy at speeds of up to 5m/s, thanks to a drive system comprising toothed belt and brushless servomotor.
The actuators are built from profiled sections and guidance shafts cut-to-length from standard components and sub-assemblies and are supplied as ready-to-mount, factory-fitted units, complete with couplings, gearboxes, motors, sensors, cables and controllers. They have a total length of 2,616mm and provide an effective stroke of 2,150mm. Christoph Dingeldein is enthusiastic about his company’s partnership with Schaeffler and the performance of the MKUVE20-B-ZR units:
“We mount grippers on the carriage that allow the individual wires to be adjusted and set up quickly with repeatable accuracy. The result is that the cutting machines can separate the EPS blocks into customer-specific roof elements without any interruptions. By using standard linear actuators, we were able to simplify the design of the adjacent machine, which means we need to produce fewer mechanical components, which also reduces assembly work.”
Meanwhile, back at Kluth’s factory, the cutting and customising machines have helped to increase the production capacity for sloping roof panels from 300m3 to approximately 600m3 per day.
The wire adjustment system has now been adopted as a standard configuration in Dingeldein & Herbert machines and, as a result, several more EPS cutting machines are equipped with Schaeffler linear actuators. Moreover, similar linear actuators are now also fitted to other roof material cutting machines, as well as those used for the stacking and unloading of machined roof elements.
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