Video: Dual-Wheel, Vertical Grinding of a Camshaft
In this video, one of EMAG's VTC machines grinds a camshaft using two opposing grinding wheels. Opposing the wheels in such a way cancels axial forces on the camshaft.
Emag (Farmington Hills, Michigan) is applying the vertical grinding concept in a new way for long workpieces such as automotive camshafts. The concept uses dual, opposing grinding wheels that cut simultaneously. The prime advantage is that the axial forces created by the wheels are directed toward each other, so they are canceled.
Video of the company’s VTC machine grinding a camshaft shows the two grinding spindles moving in X and Z axes on independent, compound slides as they complete camshaft lobes. Located vertically between the two spindles, the camshaft is secured from below by a fixed tailstock center and from above by a moveable work-head center. This provides the wheels with ample access to the workpiece to allow simultaneous grinding from both the left and the right sides.
Optimizing a camshaft lobe grinding cycle has traditionally been based less on science and more on educated guesswork and numerous test grinds. Now, computer thermal modeling software can predict areas where lobe burning is likely to occur, in order to determine the fastest possible work speed that won't thermally damage lobes and greatly reduce the number of requisite test grinds.
It sounds like a contradiction in terms-between centers and centerless grinding on one machine. But for some categories of workpieces, it's a viable production process that can yield machining time reductions of 45 percent over separate grinding operations.
Understanding grinding wheel fundamentals will help you find the right wheel for the job.