Reverse Engineering a Guide Vane with Photogrammetry

Hydropower plants around the world have been equipped with components from Voith Hydro for over 140 years. As a full-service provider of hydroelectric power plant equipment, Voith is one of the world’s leading manufacturers.

The Voith Hydro GmbH & Co. KG, with its headquarters in Heidenheim, Germany is a leading full-service provider of machine technology equipment for hydroelectric power plants. In order to digitize components for which there is no available CAD data, the company employs the HandySCAN 3D Scanner and the photogrammetry camera MaxSHOT 3D from Creaform.

The Reverse Engineering Project

The aim was to reconstruct a missing filling piece for a guide vane and to assign an existing filling piece to the correct guide vane. The guide vanes are components of the distributor. They control the volume of water and direct it onto a turbine runner in the desired flow direction.

As a first step, a photogrammetry measurement was carried out on the two guide vanes using the MaxSHOT 3D optical coordinate measuring system in order to increase the scanning accuracy as well as to be able to carry out the scanning process with flexibility. The MaxSHOT 3D offers a measurement accuracy of more than 0.015 mm/m and is ideally suited for large projects and parts ranging from 2 to 10 m in length, making highly precise measurements possible.

In addition, a scan was made in which the existing filling piece was digitized. The scan file should depict as accurate an image as possible (in the range of 0.1 mm) of the wing contour, so that exact assignment and reconstruction of the filler pieces are possible. The scanning and processing of the scan files are done with VXscan. By deleting redundant or accidentally captured areas and then saving them as .stl files, the software also cleaned up the model.

In order to obtain a complete CAD model, it is necessary to perform a surface reconstruction. This was implemented in Polyworks Modeler. The polygon models generated from the scan files serve as a foundation here. During processing, CAD’s images of the filler piece and its counterpart were generated on the guide vane.

The scan files of the guide vanes and the filler piece were also used for the “digital test fit”. Here, the scan files were merged in Polyworks Inspector to find out to which vane the existing filler belongs to. The same was done with the newly designed filler piece to make sure it matched the guide vane.

Guide vane with filler piece in VXelements and as CAD in Polyworks, copyright: Voith Group


Scan of filler piece in VXelements and color comparison in Polyworks, copyright: Voith Group

Advantages of Portable Measurement Devices

“In the hydropower sector, a great many free-form surfaces used are difficult to measure with conventional measuring instruments. In order to be faster, more effective, and more flexible, as well as to obtain the benefits of reverse engineering, we decided to use Creaform’s scanning technology,” explains Daniel Roessler, Quality Engineer at the Voith Hydro Group Division.

In the past, the company used various handheld measuring devices as well as 3D measuring arms. The Creaform HandySCAN 3D is much more flexible and unbound than a measuring arm. The dimensional range of components in the hydropower sector extends from 500 mm to 7000 mm. It is essential to use a system that is portable and can capture the desired areas without constant repositioning. In addition, the previous system could only capture small areas. In comparison, the Creaform system works quickly and effectively and can therefore also capture large areas.

Mr. Roessler continues: “In our field, we need mobile devices that can be used flexibly and are ready for use without much effort. With the HandySCAN 3D as well as the MaxSHOT 3D, we have two products which allows us to react quickly and with flexibility at the customer’s site in the power plant, at suppliers, as well as in workshops.”

The advantage here is that after a scan, all profiles and measurement data are complete in one file, and time-consuming rechecks on the component are no longer necessary. Furthermore, the risk potential of manual faulty measurements and misinterpretations is reduced to almost zero. The location of the component is not relevant when using laser scanning. With the portable Creaform devices, Voith Hydro is able to capture the details everywhere and in almost any position.

Return on Investment

Creaform HandySCAN3D, copyright: Voith Group

It would certainly have been possible to carry out some of the measurements using manual measuring equipment, from which the filling piece could have been assigned and a new one constructed. However, it is highly probable that the newly manufactured filling piece would have had to be reground manually afterwards, because the free-form contour cannot be recorded with conventional methods. This would require the components to be transported from the power plant to the Voith plant, which would involve additional costs and effort. With the help of scanning technology, only one person was needed to perform the scan on site at the power plant. Using the digital images of the components, the remaining steps could be carried out digitally on a PC.

In principle, a time and cost saving potential of 40% to 50% can be achieved by using reverse engineering for components with a medium level of detail compared to standard engineering.

The advantage here is that after a scan, all profiles and measurement data are complete in one file, and time-consuming rechecks on the component are no longer necessary. Furthermore, the risk potential of manual faulty measurements and misinterpretations is reduced to almost zero. The location of the component is not relevant when using laser scanning. With the portable Creaform devices, Voith Hydro is able to capture the details everywhere and in almost any position.

A Positive Result All Around

“Practices and processes have improved, especially in terms of what’s possible. Using the HandySCAN 3D and the MaxSHOT 3D, Voith Hydro is able to react flexibly and quickly to tasks or problems. Components can be digitized and examined or reconstructed on a PC in no time. Responsiveness is an important feature that the Creaform systems make possible. In production, in the service area, or on construction sites, situations often arise in which immediate reaction is required and long waiting times are often accompanied with high costs. With our Creaform Systems, we are immediately able to offer the customer a solution and an analysis,” summarizes Mr. Roessler.

“Creaform has sophisticated systems for digitizing components. With Creaform’s products, we are able to accurately measure and digitize our customers’ components quickly and cost-effectively for the future, especially those from past years of manufacture when digitization did not yet play a role. In addition, we can manufacture the components individually according to the requirements.”

About Voith

Voith is a globally active technology group. With its broad portfolio of equipment, products, services, and digital applications, Voith sets standards in the energy, oil & gas, paper, raw materials, and transport & automotive markets. Founded in 1867, Voith is currently one of Europe’s major family-owned companies with more than 19,000 employees, 4.3 billion euros in sales, and locations in over 60 countries around the world.

The Group Division Voith Hydro, headquartered in Heidenheim, Germany, is a leading full-range supplier of equipment for hydropower plants and a reliable partner. Voith develops individual, long-term solutions and services for large and small hydropower plants all over the world. With its product and service portfolio, the company covers the entire life cycle and all components from hydropower plants both large and small: from generators, turbines, pumps, and automation systems to spare parts services, maintenance, training services, and digital solutions for smart hydropower.

For more information: www.creaform3d.com

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