Toyoda FH630 make it less expensive to rebuild in the future



CHALLENGE

Toyoda FH630, 6000 RPM, oil mist lubrication, stator driven

This horizontal machining spindle was seized when it arrived at NTE. The OD of the shaft nose had rubbed out on the ID of the front cover, and the ID of the taper insert had poor tool contact with excessive runout. The tool retention force was very low incoming and we observed that the gripper fingers were damaged and had significant wear. We also noted that the rear actuator bolts and the sensor covers were loose, and that the spindle-side ceramic seal surface of the rotary union was chipped. We suspected that the front bearings had lost preload in a crash, which may have resulted in much of the previously-mentioned damage.

SOLUTION

The 100mm front bearing journal of the spindle shaft was manufactured to be oversized +32/+35µ to accommodate the special preload of the front quad set of proprietary OEM angular contact bearings. Normal ISO tolerance for that journal when using non-proprietary bearings would be ±9µ. The decision was made to reduce the OD of the journal to make possible the use of non-proprietary high-precision bearings in this, and any subsequent rebuilds. We performed a kiss grind of the OD of the shaft nose, the ID of the taper insert and the 100mm front bearing journal. After a thorough cleaning of all the other spindle components, we reassembled the spindle with all new bearings, Bellevilles, grippers, rotary union, seals, o-rings and assembly screws. Tool retention force was checked and found to be improved to within the correct range. During our five hour break-in test run of the rebuilt spindle we confirmed that the vibration & temperature readings were within specification. Hopefully our customer will not need to have this spindle rebuilt any time soon, but if they eventually do, the bearings needed will be more readily available at a lower cost.

DETAILED CAUSE OF FAILURE

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