NEW TILTING TABLES: A giant step in innovation to dominate the offshore wind generation market

The number of offshore wind farms has increased considerably around the world in the last decade. It is one of the most profitable ways of generating energy, does not have limitations in terms of land use and does not have an impact on the landscape. Furthermore, because they are far from population centers and do not have as many limitations insofar as noise generation, large offshore turbines can work at higher rotation speeds (90 m/s in contrast to 65 m/s in land applications).

The production of offshore wind turbines has been growing in parallel with the increase in demand for this kind of energy. Nevertheless, machining their components is complex, highly demanding and hard to do productively.

The JUARISTI model introduces two major new features onto the market: capacity up to 100 tons of weight and automatic positioning with hydrostatic support on the tilting axis.

With that in mind, at JUARISTI work has been done for the last five years on a specific solution that reduces manufacturing time for these kind of pieces by 30 %. Tolerances have been achieved that are not common for these sizes (volumes up to 100 m³ and weights above 70 t). It is a high-capacity tilting rotary table.

A Perfect Solution for Large Hubs

For decades, JUARISTI has been a leader in manufacturing roto-traversing tables, which is a very suitable component for machining complex pieces and increasing job productivity. Through active listening to the market and working collaboratively with customers, the technical managers found a difficulty that manufacturers of large wind turbine hubs needed to overcome.

Currently, the manufacturers of those components work with milling and boring centers and machine the pieces directly with them supported on a flat rotating table. Nevertheless, some machining operations require the piece to be inclined over one of its faces. To do that operation, operators use wedges and fixtures that can lift or incline the piece and prepare it with adjustments and measurements made manually by the operator.

The tilting table made by JUARISTI can make that task slightly easier, because in addition to the cross movement and rotation on a horizontal plane, it can make a tilting movement. Consequently, the end users can automate their operations and do them in a single clamping without operator involvement.

In addition, the JUARISTI model introduces two major new features onto the market. On one hand, the tilting movement is done with hydrostatic guiding and support (unique in the world), which makes it possible to reach loads up to 100 tons with complete reliability. On the other hand, in addition to doing automatic positioning and working with the tilting axis locked, the configuration of the table makes it possible to continuously machine along its two CNC axes, which makes it easier to machine large pieces in five axes.

The outcome is a table highly suitable for high performance machining of large pieces that achieves a degree of precision similar to what other manufacturers achieve with small pieces.

Precise Production and Zero Defects

This component lets JUARISTI customers do efficient manufacturing with zero defects, because by eliminating the use of wedges and fixtures all the errors associated with manually handling pieces and doing different clampings can be avoided. On the other hand, reducing the number of defective machining processes eliminates scrapping pieces, thus optimising material resources use and giving greater profitability.

To facilitate manufacturing complex parts, the tables provide two different tilting configurations. They have a standard tilting angle of -5°/+5° and an additional configuration of -2°/+8°, which is a more flexible range that satisfies the needs of the most complex pieces.

For developing this component, JUARISTI had to overcome a great challenge of manufacturability. To obtain the required geometric positioning of the table, very high precision machining must be done, in terms of roughness, concentricity and circularity. It should be noted that the machining was done on surfaces with a radius of approximately 3 metres, which drastically increased the difficulty.

The prototype project was made within the framework of Hazitek, which is an R&D support programme under the auspices of the Basque Government. After successfully finishing the prototype, JUARISTI made two new tables for critical industry customers. One of them was delivered to Sakana S. Coop, which is contractor that machines large hubs. This year a second hydrostatic table was delivered to an aerospace multinational that will use it for machining landing gear.