| 摘要 |
An auxiliary bearing apparatus for selective attachment to milling machines of the Bridgeport type, said machines having a head which supports a quill that is longitudinally movable with respect to a fixed housing. A tool-holding spindle is rotatable within the vertically movable quill at all times, both when the auxiliary bearing apparatus is installed and when it has been removed. The auxiliary bearing apparatus includes a support bearing which is adapted to be selectively attached to the housing near the bottom of the head, when the quill is fully retracted into the housing. Installation of the auxiliary bearing support is facilitated by providing a threaded retainer which engages a special extension of the housing, the special extension having threads for the express and singular purpose of accomodating the threaded retainer. When the quill is to be extended for some operation in accordance with the orginial design of the milling machine, the auxiliary bearing is easily removed by the machinist and temporarily set aside. When a new operation is to be done in which it is desired to support a spindle and its tool more rigidly (so that tool chatter or vibration is to be minimized), the quill is fully retracted into the housing and the auxiliary bearing apparatus is again installed. By providing precision bearings as a part of the auxiliary bearing apparatus, and providing a hardened surface against which the auxiliary bearing is tightened, the auxiliary bearing apparatus may essentially be installed and removed almost an infinite number of times without introducing any change in the degree of support made possible by the auxiliary bearing apparatus.
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