Logo of the Physikalisch-Technische Bundesanstalt

Novel procedures for the inspection of 3D hole patterns in coordinate metrology


PTB together with an industrial manufacturer of coordinate measurement machines is  investigating reliable methods for the computational simulation of product assemblies by 3D hole pattern fitting procedures. An example of an application is the inspection of flange rings for wind turbines.

Figure 1 shows the assembly of two flange rings. To mount both parts, several bolts must fit in all drill holes at once. The drill holes are crooked due to the inevitable manufacturing deviations. To see if all drill holes are within an acceptable tolerance of deviations, 3D hole-pattern fitting compares the flange with a geometrically ideal counterpart.

Figure 1: Requirements for the assembly of a flange ring with bolt

The research starts with dimensioning and tolerancing principles within the standards ISO 1101 and ISO 2692 which lead to inspections with assembly simulations. PTB offers guidelines for the application of these methods to coordinate measuring machines according to the requirements from the above mentioned standards.

At present, flange rings for wind turbines have diameters up to 5 metres with more than 50 drill holes. Thus, software for 3D hole-pattern fitting has to work highly efficiently, as measurement data sets for all holes can comprise many millions of measurement points. PTB has developed a novel reference algorithm which is capable of the accurate calculation of the fitting with considerably better performance than previously used software.

In future, software tests will be implemented for different applications of 3D hole pattern fitting. These comprise test data sets with an a priori known fitting solution and evaluation procedures for the comparison of different calculations results. The tests will be offered to industry as a new service via an online test system. 

The research is funded by the Federal Ministry for Economic Affairs and Energy. It started in April 2015 and has a duration of 30 months. It will help to improve the quality of products in different industrial sectors such as automotive engineering , microelectronics and medical engineering in the long term.


Contact person:

Daniel Hutzschenreuter, FB 1. 1, AG 1. 14, E-Mail: Opens window for sending emailDaniel.Hutzschenreuter(at)ptb.de