API Helps CRRC Ensure Accuracy, Improve Efficiency

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Radian Laser Tracker Helps Align High Speed Train Manufacturing Processes

China Railway Rolling Stock Corporation (CRRC), headquartered in Beijing China, is the world’s leading supplier of rail transit equipment. CRRC is engaged in the R & D, design, manufacture, repair, sales, leasing and technical services of railway rolling stock, urban rail transit vehicles, and construction machinery products. To meet increasing demand, CRRC needed more advanced processing methods to improve efficiency while ensuring the quality of their high-speed rail products. They invested in a precision machine tool with a 60-meter-long x axis. To verify this tool, CRRC turned to API and the RADIAN 6 Degrees of Freedom (6DoF) Laser Tracker. API was able to:

  • Measure the entire length of the machine axis
  • Determine straightness and vertical errors in X, Y, and Z axes
  • Reduce downtime by more than 30% with a single measurement setup

CRRC was formed in 2014 when CNR and CSR Groups decided to re-merge into one corporation. They were formerly known as China National Railway Locomotive & Rolling Stock Industry Corporation, which split in 2002. With over 180,000 employees, CRRC is the world’s largest supplier of rail transit equipment with the most complete product lines and leading technologies. In order to ensure the safety and comfort of their high-speed trains, CRRC must meet tight requirements for high-speed train cars, such as tightness, mute effect, aerodynamic factors and body strength. At the same time, the increasing demand for orders also requires more efficient manufacturing of high-speed trains. When they made an investment in a precision machine tool, they needed a way to verify the machine tool and the high-volume parts it was producing.

Traditionally, laser interferometry (IFM) is the benchmark of length measurement. The usual method is to use an IFM to measure the error parameters of the machine tool. In this case however, the 60-meter length prohibited the use of an IFM (with a maximum measuring distance of 45m) for a single-setup measurement. Additionally, the installation and debugging of the IFM and the twofold verticality of the three axes on the machine tool would add dramatic downtime to IFM-only measurements.

Fortunately for CRRC, API’s Radian Pro Laser Tracker is a dual-laser instrument, which integrates IFM (the benchmark of length measurement) and ADM laser (absolute laser, used for fast light break continuation, to ensure continuous and smooth measurement operation), and can widely meet the needs of various measurement operations. CRRC contracted API China’s Services team to use a Radian Pro to verify their precision machine tool.

Radian Pro was able to measure the straightness and vertical errors of all axes in a single setup. The Services team set the Tracker at one end of the X-axis, fixed and SMR to the spindle, and sent the machine through it’s movement patterns to run measurements for the straightness of the X-axis both vertical/horizontal and left/right. Then, they ran the machine through trips along the X, Y, and Z-axes to measure vertical errors between all three. The tracker’s software was able to automatically create error reports on these measurements that can be uploaded into the machine controller.

Radian Pro’s ability to measure down to the micron from up to 80m allowed CRRC to verify all error parameters of their precision machine tool in a single measurement setup, ensuring quality and dramatically reducing downtime. For more information on Radian, visit apimetrology.com.

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