Switching tracks

Changing workholding systems accelerates railway switch production

Railway switches for moving trains from one set of tracks to another are formed from very hard alloy steel. Cuts range from 5/8-in to 7/8-in deep and range from 16 to 40 feet in length. The extensive cutting requires precise clamping throughout a process that can take two or more hours per switch. Various hydraulic clamps from Enerpac, Milwaukee, WI, have aided Progress Rail, Covington, KY, in retooling their plant for increased efficiency and production.

Operators begin the clamping process by loading rail components on the fixture and clamping them in place. Initial cuts are made to the top and sides of the rail, then the machine rotates the fixture 90 degrees for additional cuts to the base of the rail. After cutting, the fixture rotates to its original position for unloading of the finished part and insertion of the next one.

Previous electromagnetic clamps proved unreliable, sometimes scrapping entire lengths of track. In the new system, a combination of 400 block cylinders, threaded body cylinders and swing cylinders work in tandem at 5000 psi each, positioning the rails and holding them intact throughout the milling process. Block cylinders lock the fixture in the upright position and clamp the "tee-rail" assemblies used to clamp the rail. Double acting threaded cylinders operate the rocker arm clamps that hold the rail in place. These cylinders also operate shot pins that lock the tilting fixture in the lock position. The swing clamps pull the rail tight to the machine base during cutting operations and rotate 90 degrees when unclamped. A customized system guides the operator through the clamping sequence.

Once the swing cylinders pull the rail into place and the threaded body cylinders are applied, bolts run through holes in the rail into threaded holes in the tee rail assembly to complete the clamping process.

According to manufacturing manager, Lee Knox, "We're cutting faster on this machine than we were previously. That's because we're checking less and cutting more. With the consistency we're getting now with hydraulic clamps, we no longer have to cut two or three times on a single part...I estimate we're at least 50 percent faster now."

--SG

For more information:

Circle 700 - Enerpac, or connect directly to their website via the Online Reader Service Program at http://www.OneRS.net/105df-700

Circle 701 - Progress Rail Services, or connect directly at http://www.OneRS.net/105df-701