Abstract
Selection and maintenance of the preload in the spindle bearings is one of the major challenge for designers of machine tool spindles with rolling element bearings. The balls in a ball bearing assembly deform under the application of a spindle load. Their stiffness is generally less than that of the spindle body, so the balls play the role of springs. In high-speed spindles, preload is imposed when the spindle acts as the rotor of the motor. When the spindle shaft gets hot, it grows, while the spindle housing is not as hot, so it grows less, and this difference increases the preload. Cooling the housing with a water jacket is not enough, and may even make the problem worse. Spindle manufacturers introduce chilled oil down the center of the shaft and collect it as it passes through the bearings so that effective cooling can access the spindle.
Original language | English |
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Pages | 28-29 |
Number of pages | 2 |
Volume | 63 |
No | 6 |
Specialist publication | Cutting Tool Engineering |
State | Published - Jun 2011 |
Externally published | Yes |