Customer Solutions

Using DAQ and ComponentWorks to Create the Accuscan Runout Inspection System

Author(s):

Doug Valente, Paris Mountain Consulting

Industry:

Machines/Mechanics

Product:

Data Acquisition, Measurement Studio

The Challenge:

Creating a flexible, high-accuracy inspection system for measuring circular geometry characteristics such as mechanical and electrical runout.

The Solution:

Using National Instruments Measurement Studio, Microsoft Visual Basic 6.0, and an E Series multifunction DAQ board to build a PC-based system called AccuScan, which can collect and analyze circular geometry data; produce polar profiles, strip charts, and inspection reports; and simulate manual data collection techniques.

Introduction
Circular geometry is an important class of measurement, particularly in the aircraft engine, turbine manufacturing, and automotive, industries, where circular geometry plays a critical role in producing a quality product. Roundness, a common circular geometry measurement, is familiar to most people and easy to visualize. However, there are other measurements, such as runout, circular flatness, eccentricity, and circular parallelism, that are critical in these types of products.

When building aircraft engines and industrial gas turbines, for instance, circular geometry data is required for computerized rotor stacking. In this process, the designer constructs a virtual assembly of the rotor with specialized software before the parts are actually assembled. This software, sometimes called a "stacking program," uses the circular geometry data of each part to construct a mathematical model of the rotor assembly process. The position of each part is then optimized to produce a straight rotor with low vibration characteristics. The results are a shorter assembly time, a higher quality rotor, and longer engine life.
Paris Mountain Consulting LLC, located in Greenville, SC, specializes in the design and development of data acquisition and inspection systems and develops software for the aircraft engine, industrial gas turbine, and steam turbine industries. In 1999, we embarked on a project to develop our own circular geometry inspection system called "AccuScan." AccuScan, now in its third major revision, is an inspection system that can quickly adapt to a machine tool for in-process inspection, or it can easily integrate with a precision rotary table. Inspection time with AccuScan is dramatically reduced over manual data collection methods. Because of its extreme versatility, we have even used AccuScan to measure turbine blade-tip runout.

Data Acquisition Hardware
Circular geometry data is typically collected using contact LVDTs, such as those made by TESA/Brown & Sharpe, Federal Instruments, and Mitutoyo. You can use AccuScan with these contact probes as well as with noncontact probes (eddy current, capacitance, fiber optics, and laser triangulation).

When millionths of an inch count, high-resolution sampling is critical. For this reason, we chose a 16-bit data acquisition board for AccuScan, the National Instruments 16-channel E Series PCI-MIO-16XE-50. We selected it, not just because it offers 16-bit sampling, but because it also has two 24-bit counter/timers and eight digital I/O lines. We needed these features for proximity switches, LEDs, a quadrature encoder, and control of a rotary table. Because one normally collects circular geometry data very slowly to minimize mechanical noise in the measurement system (the part is typically rotated at 1 to 2 rpm), the 20 kS/s sampling rate of the PCI-MIO-16XE-50 was more than adequate. The standard AccuScan inspection system uses a rack-mounted industrial PC, but we also offer AccuScan in a laptop configuration. This ultracompact version of AccuScan uses an NI DAQCard AI-16XE-50, which offers the same capabilities as the PCI-MIO-16XE-50.

System Software
We developed AccuScan using Microsoft Visual Basic 6.0 and National Instruments Measurement Studio, which we selected because of the following features:

• Seamless integration into our own software
• All necessary functionality
• Familiar programming paradigm via ActiveX components for Visual Basic and Visual C++.
  

Because Measurement Studio offers such a full array of features, we avoided purchasing third-party user interface and analysis components. This fact helped reduce production costs, decrease development time, and simplify installation and revision control issues. NI-DAQ upgrades have gone very smoothly as well, with only minor changes to our code. With Measurement Studio, we achieved all of our design goals and delivered a robust professional product that is very easy to use.There are actually three parts to the AccuScan software; AccuScan IFE, the inspection file editor, is used to create "inspection templates," or part programs.

AccuScan IFE is a stand-alone program that we include with every AccuScan inspection system, and you can use it offline, on a PC separate from the inspection system. AccuScan itself is the data acquisition application. It can read inspection templates, perform the necessary data acquisition, read and write inspection data files, and generate inspection reports. The third part of the system, the AccuScan Viewer, is a free program for viewing, printing, and exporting inspection reports and data. It was also created using Measurement Studio.
The transition of AccuScan from a desktop to a laptop platform was as simple as loading the software and plugging in the DAQCard. It has all the capabilities and features of the PCI board used in the desktop system - a testimony to the quality, flexibility, and scalability of the National Instruments product line.

Summary
With AccuScan, you can collect and analyze high-accuracy circular geometry data, with dramatic reductions in inspection time. You can export, print, save reports (as PDF files), and view data using the free AccuScan Viewer program that you can download from our Web site. Thanks to National Instruments superior products, AccuScan is a best-of-breed inspection system.

For more information, contact:

Greg Valente

Paris Mountain Consulting

833 Altamont Road

Greenville, SC 29609

Tel: (864) 232-6011

Fax: (864) 232-8899

E-mail: sales@parismountain.com

Web: www.parismountain.com

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