Increasing Productivity/Quality through Better Utilization of Dimensional Data John Reed, Accurex Measurement, Inc.

Transcription

1 Increasing Productivity/Quality through Better Utilization of Dimensional Data John Reed, Accurex Measurement, Inc. Dimensional measurement is accepted as standard operating procedure in the aerospace industry. Nearly every step in the manufacturing procedure incorporates some type of dimensional measurement to ensure that the process is done according to specification. The information is evaluated to determine whether the piece meets specific requirements. The information is then discarded if the part is within tolerance, or it can be saved for recordkeeping. In some cases, the data is archived so that it can be recalled if a product problem occurs or the data may be examined statically to determine if the process is under control. However, most information is discarded immediately or saved only to be ignored in the future. Geometric Dimensioning and Tolerancing During this presentation we will show examples of collecting data from White Light Scanners, Photogrammetry, and data from the Gap/Mismatch systems. We will also use these systems to show how to utilize this data again to increase productivity and quality. Breuckmann Stereo Scan GapGun System TubeInspect The goal of this presentation is to discuss examples of additional data uses that will utilize this information for further improvement in quality and/or productivity. We will first discuss several pieces of dimensional measurement equipment, describing what they are, how they work, and the type of dimensional data they produce. We will then give examples of how this dimensional data can be reused to result in additional advantages.

2 Gap & Flush measuring device. A. Primary Applications. This measuring device is used to either measure the gap and mismatch of two surfaces that are assembled together or the shape of a single feature. The gap and mismatch is generally measured to reduce fluid drag or noise from fluids that move over its surface (i.e., water or air), to minimize radar signature, or to give the object a uniform appearance for cosmetic purposes. The single feature measurement would be small radii or chamfer measurement. Gap/Mismatch Aerospace Gap/Flush Automotive Measurement of Radii & Chamfers B. Operating Principle. This hand-held device produces a laser line, which is projected normal to the gap you want to measure. It is brought closer to the surface until it is within operating range (approximately 2 inches from the surface). Although it can be completely non-contact, standoffs may be used to center the device. When the correct position is achieved, the system will automatically take 16 images of the laser line using an embedded digital camera. During this process, the line is digitized, the desired calculations are made, the nonconforming images is discarded, and is the remaining images are used to provide the gap, flush or form measurements. C. System Performance. The accuracy of this system is between.001 to.004. Speed is as high as 10 features per minute. The system can be automated to give graphical instructions to an operator, who positions the system. The system then completes the measurement, compares the output to the nominal/tolerances and displays the results. Operator is shown The measurement is Results displayed Result recorded the correct point done.

3 D. Typical uses. As the operator performs the measurement, the results are shown as being within tolerance (green) or outside tolerance (red) on the color PDA, recorded on an Excel spreadsheet where the number of good vs. out of tolerance features can be immediately viewed. The trend comparison from the last several pieces can be seen and the data archived. GapGun sample output Example of additional uses 1. Nissan Motors uses this type of system on-line, taking between 16 to 32 features of each vehicle that move down the production line. It uses multiple Gap/Flush measurement devices connected to the same computer and program. The operator receives immediate feedback for each feature measured. The results are automatically put into an SPC pack for long-term evaluation. They have also added an additional area of feedback: The results for each vehicle will be displayed in the area assembling components, giving them a running real-time indication (within a few minutes) on the consistency of the work. 2. Lockheed Martin. Every F35 that is manufactured contains a large number of gap/mismatch measurements. Lockheed developed a system to store all data from every airplane. After a number of airplanes are manufactured it is possible to look at all the dimensional data on each plane to include gap/mismatch in an attempt to correlate changes in performance to the dimensional variance. F35 JFS F35 JFS Checkplan

4 Mold Measurement Using a White Light Scanner A. Primary Application. Creation of a point cloud (2 to 200 million surface points) on free-form shaped parts or parts with many small surface features. To be used for inspection, comparison to CAD or reverse engineering on small to mid size parts. Scans (unfinished) part Scans finished B. Operating principle. Structured light is projected (a series of lines) onto the surface. There is a known angle and distance between the projector and the camera(s). This allows triangulation to be used to calculate the surface points allowing several million surface points to be calculated in a few seconds. Topometrical Setup with Miniature Projection-Technique echnique ( MPT ) Topometric Data Acquisition and Evaluation MPT-projector triangulation angle Image recording with combined GrayCode- / Phaseshift-technique ( about 1 s ) MPT-projector digital camera digital camera evaluation of the image sequence calculation of 3D-coordinates optotop-he Matching ( STL-data ) GrayCode Phase image Fringe contrast How a White Light Scanner Works Example of results C. System Performance. The size of each scan can vary from ½ inch square to 8 feet square. The scan time (2 seconds) and the number of points remain the same. The accuracy.0002 to.020 and the resolution will change as the field of view increases. Multiple scans can be merged together to create a point cloud. D. Typical applications: Applications vary widely. It is used in industrial applications such as turbine blades, dashboards, molds and dies. It is also used in measuring skin roughness, artifact preservation, and in a number of other industries.

5 Thursday, 16 October 2008 Thursday, 16 October 2008 Thursday, 16 October 2008 reverse engineering projects Blaser Jagdwaffen - Hunting Weapons Measuring of prototype rifle stock models Reverse engineering Milling out of precious root wood engineering projects and feasability studies Snecma/IBS/Clever Engineering Aircraft and Space Engines Development of an Adaptive Grinding Process Until now the airfoil area is measured on a multi tactile measuring machine. Cultural Heritage Smithsonian Institution / Accurex Largest Museum Complex Worldwide Deer Stones Project in Mongolia Reverse Engineering Inspection of complex parts Cultural preservation Example of additional uses Scanning a die that is used for a large forging is an example of an industrial measurement for a White Light Scanner. Both halves of the die are scanned and the results can be compared to the individual CAD models to indicate if they are within acceptable tolerance. The output can be given to the operator as XYZ data or as a color deviation diagram. This information can also be given to an individual who is either wielding more material on the die or using a hand sander to remove it. A better utilization of this data is to download the model and data into an analysis package, such as Polyworks. This allows for more options to best fit the data. For example, the error can be shifted around to permit a decrease of the hand sanding or the wielding. Another option is to optimize the work to allow for longer life of the die before it needs be reworked. PolyWorks/Inspector Process Overview: Left Die vs Draw CAD 1 Alignment 3 2 Initial Stage: Data & CAD in two different coordinate systems Comparison Report the results Scanning of large accurate complex parts Color deviation diagrams PolyWorks/Inspector Feature-Based Alignment vs Best-Fit Alignment Data CAD Aligned 1 st : 4-Way Locator 3 rd : Reference Points (3) in 2 nd : 2-Way Locator the y axis Hemmer Die Right versus Inner Panel CAD Door after left Die 2-34 versus and Upper Frame CAD Inner Panel CAD Optimization thru best fit 2. Another possibility is to output the data to a laser projection system where it will projects different colors on the sections of the die needing work, thereby showing the hand grinding operator exactly where and how much

6 material needs to be removed. This will increase the productivity of the machinist working on the repair. Color deviation diagram projected on part. I. Bent Tube Inspection by a Photogrammetry System A. Primary application. Dimensional Inspection of bent tubes, hose and attachments made with a CNC bender. Theoretical tolerance zones of a typical bent tube. B. The operating principles. The system starts with an enclosure that houses 8 to 16 CCD cameras mounted on the ceiling. On the bottom and two of the sides is a light table with embedded photogrammetry target. The exact XYZ coordinates of the targets are known to the system. The tube is placed on the table in a free (unrestrained) state. Each camera then takes an image showing all or part of the tube as well as the targets in approximately 30 milliseconds. The system digitizes the profile of the tube it sees from the cameras. Using the photogrammetry targets, the system merges all the images together to create a 3D model. The model is put into a simulated restrained condition to take out the effects of gravity and creates an inspection report. Basic Principle Images from 16 digital cameras Basic Principle Creating 3D model and bending points Work Flow Optical Gauge Printout of deviation report The Parts are place in the Images are merged to Inspection Results made Tubeinspect system construct a model

7 C. System Performance. Bent tubes or hoses from 1/8 to 8 Diameter -- length is unlimited -- can be measured. Accuracy is.001 to.004. The system can measure an 8 foot tube with 20 bends in 15 seconds. With a sampling rate of thousands of points, increasing the reproducibility. D. Typical application. Application in aerospace or automotive tube or tube assemblies (with hoses) coming from a CNC tube bender are typical applications. Theoretical tolerance zones of a typical bent tube. Example of additional uses 1. An increase in utilization of the data is to take the measurement data, compare it to the nominal measurement and automatically calculate the changes needed to change the bender PBR (Push- Bend-Rotate) to bring a part to nominal. At that point the changes can be sent either automatically or on-command to the bender. (Can be automatically done in the software) Work Flow Bending Program Set Up Work Flow Bending Program Set-up Generate correction data Send set-up data to machine (RS232, TCP/IP) tube info SERVER SERVER Bender 1 deviation values control panel for datatransfer Bender 2 Bender 3 Bender 4 2. Another example involves aerospace tube bending. Most aerospace tube bending applications have very short runs (2 to 7 pieces). Typically after the tube is bent, it is measured and the excess length is hand marked on the tube. It is then hand trimmed on a saw with the operator positioning each end as close a possible to the hand marked location. However, with the TubeInspect, it can use the existing measurement date and automatically calculate the amount of tube to be removed. It then automatically positions a motorized stop behind the saw in order to put the tube in the correct location.

8 The operator then takes the tube out of the tubeinspect, puts the first end of the tube against the backstop, cuts off the end, and rotates the tube before repeating on the opposite end. II. Basic Single Camera Photogrammetry. A. Primary application. Typically Industrial photogrammetry has been used to create small point clouds to be used for large or difficult to reach part measurements, or to measure deformation on parts due to temperature, weight or position changes. B. Operating principle. Reflective photogrammetry targets are placed on the desired measurement object at each location where a recorded point is needed. A reference bar is placed in the measurement field with two targets of known distance. A special digital camera is used to collect the images, which are digitized and downloaded to a computer. A point cloud of these points is created, which can be used for feature measurement or compared with an earlier survey to establish deformation Z 5 4 Y X The theory of Photogrammetry Photogrammetry example output of camera positions equipment Photogrammetry C. System Performance: The system can be used to measure parts from 1 to several hundred feet. Accuracy is from.0002 to.010. D. Typical application. In the past it has been used to measure primarily free-form surfaces or forms on large parts. This was due to the target being primarily paper or vinyl reflective targets that were difficult to use to measure prismatic parts like aerospace fixtures. Now with the use of Cubic targets edges and bores can be measured more easily. Antenna prepared for survey Color deviation diagram of antenna

9 Large Fabricated Part Large round free standing case Example of additional uses Increase utilization of measurement data. Now that prismatic features can be easily measured, there is no need to bother with paper targets or features to create point clouds. These points can be automatically downloaded to a software design for easy comparison between the measure data (features) and the nominal through the use of CAD, which also generates an inspection report. Standard flat or paper reflective targets New style cubic feature target Closing Summary These descriptions of additional usage for dimension measurement are examples of benefits that can be achieved with the extra step of utilizing the dimensional measurement data already collected. The goal of this paper is to give pertinent examples of how to better utilize your data. Since applications and requirements vary widely you may not be able to use these exact examples. However, it can serve to enable various problem-solving approaches for uncovering how this data can improve your production/quality with various applications and data collection systems.