AGMA 11FTM01-2011 pdf free.AGMA Technical Paper A New Way of Face Gear Manufacturing By H.J. Stadtfeld, The Gleason Works.
Figure 3 shows a modified cylindrical gear hobbing machine which employs a special hob for face gears (shown enlarged in Figure 2 on the right side). One hob start winds about two times around the disk shaped cutter body, where the cutter body is curved in width-wise direction (in the axial plane). The individual hob blades which have an involute profile, are grouped like the teeth of the corresponding cylindrical pinion around the pinion’s root cylinder. The disk cutter for face gears attempts to represent the corresponding cylindrical pinion, similar to the way a regular bob represents a generating rack. There are process related distortions some of which can be corrected. The cutter disk moves during the cutting process in the “Feed Direction” across the face width. Such a cutter disk can only be used for one particular face gear design, which makes standardization of the cutting tools impossible [2].
A very e’egant and geometrically sound cutting method for face gears uses a shaper cutter as shown in Figure 4. The blade profile of the shaper cutter is equal to the corresponding pinion profile, where backlash and root clearance have been considered in the design of the tool. Also here, the tool is a custom design, but is calculated and manufactured like a regular shaper cutter.Hard finishing by continuous grinding with a threaded grinding wheel as shown in Figure 5 is very fast yet it requires the same corrections as already mentioned for the hobbing disk cutter. Dressing of the threaded grinding wheel is complicated because it requires a spatially inclined involute path and it presents undercut conditions on the two sides of the threaded grinding disk.
The single indexing generating grinding as shown in Figure 6 delivers very precise flank forms. The profile of the peripheral grinding wheel resembles the normal tooth profile of the corresponding cylindrical pinion, where backlash and root clearance has been considered. It is required that the grinding wheel traverses in each generating roll position along the entire face width. The discrete generating positions have to be chosen in increments fine enough since there is no automatic process to support rounding of the generating flats. Both flanks of one slot can be ground simultaneously which is advantageous regarding grinding time and grinding quality. The generating motion is a swing rotation of the grinding wheel around the virtual axis of the corresponding cylindrical pinion, as indicated in Figure 5. In spite of the simultaneous machining of both flanks of one slot, single index grinding is the slowest of the methods discussed so far [4].
The new CONIFACE method
One question raised from the discussions in the last paragraphs is: “Is there a universal tool which can be applied on an existing gear cutting or grinding machine design in order to simulate the involute shaped tooth of the corresponding cylindrical pinion during the machining process?” A simulation of the pinion tooth along the entire face within any roll position would be of great advantage because this could eliminate the time consuming traversing motion and at the same time would provide a rounding between the generating flats.
All the above mentioned criteria are fulfilled from CONIFLEX cutters and from CONIFLEX grinding wheels [5], however, the blade profile of the CONIFLEX cutter is required to have an involute profile. Figure 7 shows to the right such a modification on a CONIFLEX grinding wheel. In order to come to a standard tool it is also possible to modify the cutter disk swing rotation during the roll motions such that also a blade with a straight cutting edge will generate a correct face gear flank. This can be achieved with the Gleason standard feature “Modified Roll”.
The contact lines between the cutter disk and the flank of the corresponding cylindrical pinion are drawn in the left part of Figure 7. These contact lines extend along the entire face width but they are different to the actual generating lines, which are identical to the contact lines between cylindrical pinion and face gear. An important aspect is the face width orientation of the contact lines between face gear flanks and enveloped tool surface, because it presents the possibility to eliminate any traversing feed motion.AGMA 11FTM01 pdf free download.