Pierre, what kind of in feed depth of cut does that Landis machine increment the grinding wheel?
Is that particular shaft/operation done without any kind of support to prevent bowing of the part under wheel pressure?
The Landis in auto feed can infeed down to 0.000 something and up to 0.0015” per pass. The traversing speed can be varied in both directions as well. Even if these shafts are 1.125” diameter at the end, one has to be careful to not overload the wheel. Deflection will occur.
On shorter shafts I have taken 0.005” on a roughing pass (hand fed and slow traverse) such as the shorter version (only 8” vs 14” as shown here) of the work rolls, but that is only when they have only been newly made, and I do all of the sets at the same setting so that all are near the same size prior to going to finish size. Obviously the wheel needs to be redressed after this. Usually I am only doing a clean up of the surface, which calls for a 0.001-2” grind to remove the surface coating and any defects caused by foreign debris that dimpled the surface.
It really helps if the wheel can move completely off the part at both ends, when not there is a size change where the wheel does not come off and compensation for this can be troublesome. On the short rolls, I will move across and then back without moving the wheel. Flip the roll and again without changing the wheel, move across and back to the start position. This removes the slight taper that occurs at the drive end where the dog is. It measures only 0.0005” oversized on the last inch but this still causes issues when rolling material down to 0.0005” across 3” strip.
I start up the Landis an hour before I need it so that everything is warm and the bushings are tightened up due to thermal expansion. Circulate the coolant through the filters at the same time to reduce surface defects.
In the arbors case, I turned on the lathe about 0.020” over size. Cut the RH and LH threads, did a heat treatment and then ground to size. The over size allows for the distortion that occurs during the heat treat. Ground between centers and since I had to stop at that center shoulder, I fed 0.001” per pass until I was 0.001“ away from final size. The last few passes were only 0.000X per pass. Flood coolant and final passes with no infeed to sparkout. No supports were used.
In the hot rolls case, machined 0.010” oversized, heat treat to R62-67. Grind to sizes as required per print. Flood coolant and extra filtration of coolant as a mirror finish is desired.
When grinding the large back up rolls, which are 5x larger in diameter, no support is required over the 22” length. Just need to be careful handling them due to weight.
Pierre
