Gear grinding is distinguished into generating grinding and profile grinding as well as continuous and discontinuous grinding [KARP08]. Generating gear grinding generates the gear shape mainly by the complex process kinematics, profile gear grinding mainly through the grinding wheel profile (Fig. 4.2).
The grinding tools have to withstand long contact lengths. The contact length in tooth flank profile grinding can be as long as in creep feed grinding [SCHL04]. Karpuschewski et al. [KARP08] describe recent developments in gear grinding applications.
Profile grinding
Fig. 4.2 Gear grinding tools, with permission from the Gear department, WZL of RWTH Aachen University
4.1.2.2 Cylindrical Peel Grinding Wheels
External cylindrical form grinding processes or so called peel grinding procedures are defined by a transverse feed and an inclined wheel. As consequence, the machining zone is small and approaches a punctiform contact in theory. This procedure is very flexible regarding workpiece shape and the grinding forces are comparatively small. Due to the punctiform contact zone, however, the grinding forces result in high pressure and high load on the single abrasive grit. Often superabrasive grits are used and they have to be fixed well within the binding matrix. In general, the abrasive layer exhibits a high hardness [BLAN07]. Today, mostly vitrified bonded CBN grinding wheels are used with wheel circumferential speeds of up to 160 m/s for peel grinding applications [BLAN07]. Specific material removal rates of several hundred mm3/mms are possible [BLAN07].
The variant Quick-Point grinding was patented by Sir Erwin Junker in 1994 and integrates high wheel speeds, CBN grits, and CNC controlled paths [WANG12]. Consequently, tool layout has to be adapted [BLAN07]. Wang et al. [WANG12] suggest that future research focusses on new matrix materials with low density, thermal expansion coefficient, and high specific strength.