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Laser projectors benefit turbine blade manufacture


Axel Rieckmann, LAP

Using the experience it has gained from the aviation industry, LAP GmbH Laser Applikationen is now helping wind turbine blade manufacturers to improve accuracy and reduce costs. Axel Rieckmann, sales manager industry at LAP, explains the use of the company’s laser projection equipment, which Germanischer Lloyd has certified for use in the production of turbine blades.

Laser projection systems display points, lines, crosses or any other shape on virtually any surface true to scale based on CAD data, replacing physical templates and measurement equipment. LAP provides projectors and software for 2D applications (projection on flat surfaces) and 3D applications (projection on curved surfaces).

Using laser projection equipment, manual alignment is easier and faster, and errors during part placement are reduced. In addition, changes in design can be easily implemented, as it is not necessary to produce a new physical template or rewrite a complicated measurement description – changing the projection data is sufficient.

The benefits of laser projection systems include improved quality, reduced set-up time, increased throughout, and reduced costs.

Laser projection equipment can be used in several processes, including:

  • joining parts;
  • placing layers of material;
  • positioning and aligning parts;
  • to display work steps; or
  • support other work by giving visual aids.

An important field of application is the manufacture of high performance carbon fibre composite components for the aviation and automotive industries. However, laser projection systems are also commonly applied in other sectors, such as wood processing, the textiles and tyre industries, as well as in the manufacture of rotor blades for wind power plants.

The operating principle

Using laser projection equipment, a laser beam is deflected in the x- and y-direction by two oscillating mirrors, continuously tracing the shape (template) required. The mirror drives (galvanometers) are optimised for the highest speed and accuracy. Their movement is controlled by a digital trajectory processor. If the outline is traced more than approximately 20 times per second, it appears solid to the eye. From a 4 m distance to the surface the line reaches an accuracy of ±0.5 mm.

The shape to be projected is transmitted to the system as CAD data. From these data a digital signal processor generates the control signals to be used by the galvanometers.

LAP is the only manufacturer using digital algorithms for galvanometer control. In this way, there is virtually no drift caused by analogue control elements, resulting in superior repeatability and stability of the projection.

To avoid user errors and offer highest precision and repeatability, the system includes automated safety processes. One of these is ‘TargetCheck’, an automated function that checks the position of reference points in selectable time intervals to ensure exact calibration of the system.

LAP’s PRO-SOFT 3D software controls the complete workflow, from reading the CAD data files, to transmission of control data for the projectors in the order of the working steps. The user is guided step by step through the lay-up process.

Most of the time laser projectors will be mounted on the ceiling or on a support. The projector housings are hermetically sealed to prevent lasers and galvanometers from being polluted. Active thermoelectric temperature control compensates for varying ambient temperature, supporting longevity of the laser modules. The light and compact design makes integration in existing systems easy.

Adding colour

LAP is the only manufacturer of laser projectors which display three colours (red/green/yellow) simultaneously.

This feature can be used in many ways. For example, areas that need special care can be emphasised. By switching colours from red to green or yellow, the system can also show which layers are to be placed next, which layers are already placed, or where special work is needed. Depending on surface, colour and structure of the material surface, the laser with the best reflected wavelength can be selected for better visibility.

LAP’s CAD-PRO laser projection systems display several templates for multiple teams in up to three colours.

Composites

Composites are used in a growing number of industries, including motorsport and Formula 1 racing, the automotive industry, boat building, sports and leisure goods, and industrial products. In all of these areas, laser projectors can increase quality and simplify workflows.

Composite parts are made up of several layers that are placed on top of each other in a tool. The number of layers can vary depending on the strength needed at that particular area of the part. As a result, different areas of the part require a different number of layers to be stacked. Traditionally, mechanical templates (paper, metal, or plastics) or measurement instructions have been used for positioning of the layers. This work is time-consuming and changes in the part’s design require new templates or instructions.

With laser projection systems, the CAD data available from the product design stage are used for the projection of the templates. If the design changes, only the projection files have to be adjusted. During the lay-up of composite parts, the laser system displays the position and outline of the layers using laser beams.

This technique saves time and money, as alignment with mechanical templates or complicated manual measuring instructions are no longer needed. In addition, the position of parts or layers in the tool during lay-up can be checked using laser projection. In this way wrong placement can be prevented at an early stage in the production process, eliminating reject parts.

Aviation industry

Laser projection systems are widely used in the aviation industry, where composite parts are increasingly used in modern aircraft. As every customer has different tasks and specifications, LAP customises its laser systems accordingly.

Airbus recently commissioned LAP to provide 220 laser projection systems which will be used in the manufacture of carbon fibre composite components for wings, fuselage and tail of the new Airbus A350 XWB.

During the build-up of the carbon fibre components, the LAP systems will indicate by laser beams where each individual carbon fibre layer has to go, eliminating the use of difficult-to-handle templates and complicated measurements. The laser projectors are also used to check the position of the layers during the assembly process. This ensures that any errors in the manufacturing process are avoided at an early stage.

The projectors guide the operators step by step through the process of component build-up. Like an ‘electronic plybook’, the software displays working steps such as positioning of carbon fibre plies, but also the exact marking of other part locations in the correct order. All the elements are placed in the right position at the right time, and verification and documentation are included.

Benefits of laser projection systems

The benefits of laser projection systems include:

  • project outlines, place elements – fast and easy;
  • no mechanical templates – no more template fabrication, storage, administration and no more cumbersome application;
  • very high precision;
  • efficient team working using multiple lasers and multi-tasking software.

For more than 25 years, LAP has developed and manufactured laser-based systems for high-precision contour projection in industrial and medical applications as well as non-contact measurements of geometric dimensions, such as position, width, thickness, length and diameter, in industrial production. LAP offers standard products and customised solutions. Both can be designed to customer specifications. LAP offers the full range of services from design, development, engineering, programming and production, through to commissioning and after-sales activities.

During the next three years, Airbus will install the laser equipment at its production facilities in Germany, Spain and France. The first projectors were shipped in the middle of 2010 to the Aerolia works in Meaulte, France.

Turbine blades

Similar to the aviation industry, composites play an important role in wind turbine rotor blade manufacturing.

For blades with lengths of up to (and more than) 65 m, LAP offers a ‘Multi-Head’ system, where several projectors with overlapping projection areas cover the complete surface of the blade. With millimetre precision and even higher repeatability, they ensure that all parts and layers are placed exactly where they should be.

The LAP multi-tasking software with OptoGroup feature supports virtually all combinations of installed projectors, tasks and working areas. Every working team has a display of the outline they are working with, no matter what the other teams are doing. The teams can work independently of each other and in this way, processes are accelerated and production is optimised.

Fast return on investment

More and more companies are starting using laser projectors, recognising the advantages they offer. LAP laser template projectors are small, versatile and easy-to-use. They increase the through-put of production by up to 100%. Return on investment (ROI) is reached after a short time, often within the first year of use.

In the lay-up of composite parts laser projector systems can increase throughout, improve quality and enhance team working. Already widely used in the aviation industry, manufacturers of wind turbine blades and other composite components are now discovering the benefits of employing laser projection systems in their production processes.


This article was published in the January/February 2011 issue of Reinforced Plastics magazine.

 

 


 

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