4.1.2.1 Centerless Grinding Wheels
Centerless grinding is commonly applied for large batch and mass production. In this circumferential grinding variant, the workpiece is not fixed along its axis between centers, but is supported on its circumference. Centerless grinding can be external or internal. In external grinding, the workpiece lies between grinding wheel, workrest plate and control wheel. In internal centerless grinding, the workpiece lies between rolls or shoes and is driven by a control wheel or a faceplate. [LINK14b]
In centerless grinding wheels, the structural density along the wheel width has to be monitored carefully. During manufacturing and pressing of large width wheels, the pressure needs to be higher and applied longer than for thinner wheels [TYRO03]. For centerless grinding wheels, wear is highest in the transition zone from grinding to spark-out zone. This is however not connected to the wheel density, but to the profile wear in transverse grinding operations as explained in Sect. 6.3.1 “Macro Effect—Tool Profile Loss”.
The contact properties between workpiece, grinding wheel, control wheel, and workrest plate define process stability [SCHR71]. The grinding wheel elasticity affects the grinding forces and depth of cut [SCHR71, p. 28 f.].
The control wheel, also known as regulating wheel, regulates the speed of the workpiece. It is a conventional grinding wheel, often rubber bonded corundum, or a steel body with a cemented carbide coating. The control wheel regulates the workpiece speed by accelerating or decelerating through friction. Control wheels have complex shapes to realize a linear support of the workpiece. Control wheel profile is influenced by control wheel inclination angle, workpiece center height, and workpiece diameter [MEIS81]. New calculation models for control wheel profile enable shorter dressing times and lower wheel wear [MEYR12].