Application Report. Propeller Blade Inspection Station

Transcription

1 34935 SE Douglas Street, Suite, Snoqualmie, WA 9874 Ph: Fax: Application Report Propeller Blade Inspection Station Prepared By Kyle Johnston, Ph. D. Metron Systems Inc

2 34935 SE Douglas Street, Suite, Snoqualmie, WA 9874 Ph: Fax: Introduction: In this application report, we present a turnkey Blade Inspection Station that uses Metron Systems MSG2 Laser Scanning System to conduct a completely automatic geometric inspection of a propeller blade. Some features and abilities of the Blade Inspection Station are: Comprehensive scanning to characterize the complete surface geometry of the blade is conducted in a completely automatic fashion in the time span of only a few minutes. We are able to collect dense, accurate, noise free data from blades with surface finishes ranging from brushed aluminum to painted. Please see Section for more details on the scanning process. Once a complete data set has been acquired, we are able to utilize a 3D data analysis software package to automatically produce a comprehensive 3D comparison between a blade being tested and the ideal CAD geometry. Such information allows quick feedback to the manufacturing process as well as the new ability to select sets of blades with matched geometric shapes. Please see Section 2 for comparison examples. A completed Blade Inspection Report can be automatically generated using the scan data set and a proprietary analysis package. Please see section 3 for more information about this analysis solution. A fully automated turnkey Blade Inspection Station will automatically scan a blade, conduct 3D analysis and produce a completed blade report, all in less than minutes. This is a hands free system; the only user actions required are to load the blade and initiate inspection using a bar code system. Please see section 4 for more details. Section.Scanning the Blade The Blade Inspection Station based on the MSG2 Laser Scanner consists of a high precision non-contact laser scan head, two high-precision motion stages and a rigid, stable platform. The laser scan head is mounted on a precision linear motion stage that is in turn mounted on a robust vertical riser. The part to be scanned is mounted on a precision rotary table located on the base plate. A sophisticated automatic calibration algorithm allows the system to precisely locate the center of rotation of the rotary table. A 3D point cloud is generated when the scan head is translated past the test part. Multiple views of the part can be characterized by rotating the part and scanning from different angles. The system automatically combines the 3D data from multiple rotary views, allowing a complete surface characterization of a part to be generated with no user intervention and no post processing of the data. Linear Axis Laser Scan Head Rotary Table Figure. A test blade on the MSG2 Laser Scanning System There is no need for the blade to be centered, but a clamp to keep the blade from moving is recommend. The clamp should leave a portion of the Shank exposed to allow determination of the center of rotation. Metron Systems Proprietary 2

3 34935 SE Douglas Street, Suite, Snoqualmie, WA 9874 Ph: Fax: Section 2.3D Comparison Figure 2. A comprehensive 3D data cloud acquired from a test blade. A completed data set can be imported it into a 3D data analysis software package that allows a best-fit alignment with the CAD model to be performed. Once a data set is aligned with a CAD surface file, it is then possible to calculate a 3D deviation comparison. The color plot shows the local deviations of the real blade from the CAD model. Figure 3. Color deviation plot showing deviations between the Blade geometry and the CAD. We are also able to conduct 2D deviation analysis of cross sections. The whisker plot shows an example of the deviations at station 33 of the blade shown in Figure 2 and Figure 3. Figure 4. Whisker Plot of deviation of Station 33 from the CAD. The 3D data analysis software package allows for extensive automatic analysis capabilities. For example, at the end of the scanning process, we can automatically load the data and the CAD and then initiate the alignment and analysis process. As a result, we can scan the blade and automatically produce a 3D comparison report without any user interaction. In addition to comparing a test blade with the CAD specification, it is also possible to compare a test blade with a previously scanned blade, producing results similar to those shown in Figure 3 and Figure 4. This ability allows blades to be compared together and sorted into sets of matched blades. Metron Systems Proprietary 3

4 34935 SE Douglas Street, Suite, Snoqualmie, WA 9874 Ph: Fax: Section 3.Blade Inspection Reports A typical Blade Inspection Report requires many aspects of the blade geometry to be characterized at a variety of locations along the length of a blade. Geometric features such as blade angle and alignment with the rotation axis of the blade can be difficult and time consuming to determine using conventional metrology techniques. Metron Systems has developed a proprietary Blade Analysis Application that drastically simplifies the process of creating of a Blade Inspection Report. This application is tightly integrated with the scanning process so that after the scanning is complete, the critical blade geometry characteristics are automatically evaluated and a report is generated without the need for user intervention. To prepare for the analysis of a blade, an engineer first programs the analysis by filling out a table similar to that shown below. In addition to the specific locations of the cross sections (shown as letters in this example), the data table also contains the nominal values and tolerances (shown as X s) to be included in the Blade Inspection Report as well as a few analysis directives such as if the blade is to be treated as having a flat or curved face at the desired location Tol -Tol Tol Tol Tol Tol Tol Tol Tol A.X.X.X B.X.X.X C.X.X Proprietary customer data has been removed D.X.X.X E.X.X.X.X F.X.X.X G.X.X.X H.X.X.X Figure 5. Example of the tables used to specify the inspection parameters. Once the data set is acquired, the analysis application automatically determines the center of rotation datum by analyzing the geometry of the Shank of the blade. Figure 6. Shank Geometry and Center of Rotation. Metron Systems Proprietary 4

5 34935 SE Douglas Street, Suite, Snoqualmie, WA 9874 Ph: Fax: A blade angle datum can be defined at any specified reference station. The analysis application automatically determines the datum by analyzing the point cloud data. The plot shows the cross section before and after alignment. For each station specified in the table, the analysis application automatic analyzes the point cloud data to find features such as the leading and trailing Radius Datum. If the cross section is specified as having a flat face, the blade angle can be determined using the flat side of the blade. Otherwise, the analysis application can use the chord line determined by the leading and trailing Radius Datum. The following plot shows some of the automatically generated datum that are found during analysis at a typical station location Initial Alignment Aligned with Y Axis Center of Rotation Figure 7. Reference Station E aligned with the Y-axis Figure 8. Typical station shown with Leading / Following Radius Datum, Chord Line, Face Angle and Center of Rotation. The analysis application can determine all the required geometric values and produce a Blade Inspection Report in a completely automatic fashion. The following table of inspection results for the sample blade shown in Figure 2 was automatically generated by the analysis application as directed by the setup table in Figure 5. Once these geometric values have been determined, this information can be formatted in a variety of ways. Details such as visual formatting, reporting of nominal values, tolerances, deviations and even Pass/Fail can easily be produced in a fashion that meets a customers requirements. Table BuildData (, Station ) Station A B C = D E F G H Blade Angle Thickness Width Face Alignment Edge Alignment Proprietary customer data has been removed Figure 9. Automatically generated results table with the parameters required for a Blade Inspection Report. Metron Systems Proprietary 5

6 34935 SE Douglas Street, Suite, Snoqualmie, WA 9874 Ph: Fax: Section 4. Turnkey Inspection System The turnkey, completely automatic Blade Inspection Station has many advantages over traditional inspection techniques and can generate a strong ROI model based on characteristics such as: The total inspection time for blades similar to the sample blade are less than minutes total elapsed time from mounting on the platform to generation of the final report. The operator loading is anticipated at % to 5% with the majority of required interaction limited to loading parts and initiation of inspection via a barcode. There are no special templates or tooling required. The system can be used interchangeably to inspect a range of different blade styles without special tooling or down time for setup. The ability to quickly generate comprehensive geometric comparison data and deviation analysis will allow enhanced feedback to the manufacturing process, improving both quality and yield. The same technique which allows a blade to be compared to CAD will also allow a one blade to be compared to a second blade, providing the new ability to provide premium matched propeller assembly sets by selecting from stock using similar characteristics. The Blade Inspection Station is available configured as one of the two configurations shown below, depending on the required length of travel. In addition the scanning platform, a system also includes: An integrated PC platform to accept barcode initiation drives the scanning system, acquire the data, perform the analysis and provide the finished reports. The Blade Inspection software package that allows automatic analysis of a propeller blade and automatic generation of an Inspection Report. (a) Figure. (a) Example of Metron Laser Scanner Inspection Station for travel lengths up to 6 and (b) example of Inspection Station compatible with travel up to 8 (b) Metron Systems Proprietary 6