Automation keeps ‘manhandling’ to a minimum

Whether a railway carriage carries freight or passengers over the 225,308 km (140,000 miles) of track in the U.S. railway network, wheel sets wear out and must be re-profiled or scrapped when outside the tolerances set by the Association of American Railroads. Since 1910, Simmons Machine Tool Corp., Albany, New York, has built machine tools and measuring machines for producing and maintaining railway wheel sets. The company also manufactures automation systems.

When worn wheel sets arrive at an AAR-certified railway wheel maintenance facility, the end caps and bearings first are removed and manually inspected. The serial numbers for each wheel set component then are entered into a supervisory control and data acquisition system. A measurement machine qualifies the parameters of a worn wheel set. Based on that data, a wheel set is either re-profiled on a machining center or scrapped.

Simmons Machine Tool chose the ZP-6 overhead gantry with a two-axis robot to provide most of the material-handling capability for the Wheel Turning Center, a vertical CNC lathe for machining railway wheels. Image courtesy of Güdel

Each wheel traditionally is placed on a machining center using a forklift, a crane or another manual handling method — a slow, inconsistent process in which worker safety is a concern. When workers place hooks around a wheel to lift it, there are potential pinch points, so personnel risk suffering from repetitive motion injuries or even having hands crushed under the wheel, said Scott Mitchell, manager of turnkey projects at Simmons Machine Tool.

“All those things are there because the operator has to manually move the wheel,” he said.

When the machine builder designed its new Wheel Turning Center, a vertical CNC lathe for machining railway wheels, its goals were to maximize worker safety and boost productivity to avoid repair delays. For the WTC-60 model, Simmons automated most of the process to avoid making operators manually handle wheels. For the automation system, the company turned to Coventry, U.K.-based Güdel Lineartec U.K. Ltd., which Simmons Machine Tool has worked with for about 30 years. (Güdel Inc. is in Ann Arbor, Michigan.)

Although Simmons Machine Tool historically has had success with Güdel, Mitchell said Simmons Machine Tool explores the market every five or six years to “see if Güdel is still all that we need.”

Those searches include Simmons Machine Tool’s sister company that manufactures components for automation systems.

For the WTC-60, Simmons Machine Tool selected Güdel’s ZP-6 double-axis gantry robot.

“Simmons chose Güdel’s ZP-6 gantry system for this application primarily for its reliability and capability and because equipment availability is critical for our customers,” said Jason Steven Murphy, marketing specialist at Simmons.

Mitchell said the ZP-6 gantry is probably the lowest-cost option that still provides the throughput that customers need. The complete machine cell, however, stands about 4.5 m (14.8′) high. If a customer’s facility cannot accommodate that height, Simmons Machine Tool offers other automation options, such as a six-axis robot.

When designing the WTC-60, the company modified a “widely available, generic” vertical turning center by adding a special table and tooling, reinforcing the column and enhancing the guarding, he said.

Wheel sets that require machining are placed onto a conveyor and transported into a machine cell. To accomplish this task, each wheel is picked up by a vertical lift system from Güdel. Image courtesy of Güdel

Nonetheless, Mitchell said, Simmons didn’t build the base machine, and the cell didn’t supply the rigidity required for the freight side of the industry, which moves heavier loads than the transit side.