Gear grinding machine process, elimination of the physical shifting axis

Another significant part of the new concept of gear grinding machine is the elimination of the physical shifting axis. Threaded grinding wheels, for being fully utilized, need to be shifted (i.e. displaced) along their axis between workpieces to bring in “fresh” grids. They also need to be shifted during grinding to create a diagonal instead of a pure axial motion. To accomplish this, all current gear grinding machines use a physical Y-axis underneath the grinding spindle. Unfortunately, there are serious space-constraints in this area so that this Y-axis typically builds small with low stiff ness. On the other hand, it is just this axis carrying in its own direction the highest dynamic load which is initiated by the generating process.

The new Samputensili concept of the G 160 gear grinding machine also perfectly addresses this constraint. Rather than stiffening the axis, the G 160 grinding machine completely eliminates it. By doing so, not only is this “weak spot” gone, but also – instead of stacking 4 axes (radial (X), axial (Z), swivel (A) and shifting (Y) – only 3 axes are stacked onto each other (Y, Z, A) before it comes to the grinding spindle. This architecture with 3 stacked axes instead of 4 is a real breakthrough. When compared to all existing gear grinding machine, this architecture significantly increases the overall system rigidity, thus enhancing productivity and grinding quality. With the shifting axis not physically available, its motion is simulated by an interpolation of the Z and the Y axes, the so-called virtual shifting axis. Both of these axes are not restricted by space constraint and are therefore large, strong and very rigid. This unique, patented machine concept ensures the best production times currently on the market. But the machine delivers even more.

No additional axis is needed to perform the dressing cycle. The dresser is mounted on the X1 axis slide next to the workpiece spindle. So, the precise and highly dynamic motion of the linear motor may also be used to fine-tune the geometry of the grinding wheel and the corresponding gear. It enables topological modifications of the gear flank at an unprecedented quality. Having the dresser located on the same slide as the workpiece-spindle, it finally makes it totally insensitive to thermal or other types of deviations.

Automatic Transmission Planetary Pinion

Number of teeth z 23
Normal module m 1.356 mm
Normal pressure angle α 17°30’00”
Helix angle β 18°51’43”
Face width b 20.6 mm
Nominal stock per flank q 0.08 mm

 

Roughing Pass Finishing Pass
No. of Starts 5 5
Axial Feed Rate 0.67 0.25 mm/rev
Grinding speed 80 80 m/s
Idle Time 1.0 5.1 sec
Part Change 1.0 1.0 sec
Dressing Part 0.7 0.7 sec
Total Cycle Time 10.7 10.7 sec