MAIN SHAFT DEVICE FOR MACHINE TOOL

摘要

The inside of a hollow portion (7) of a main shaft (5) through which a draw bar (9) and a disc spring assembly (11) are inserted is of a closed chamber structure and serves as an oil-containing chamber where a lubricating oil is filled. Inner diameter dimensions of bearing portions (21, 39) on both sides for supporting the draw bar (9) of the oil-containing chamber are made equal and it is arranged such that the volume of the oil-containing chamber does not change when the draw bar (9) is moved in the forward/backward direction. As a result, the lubricating oil is not pushed out from the oil-containing chamber. In a main shaft device with the above structure, clamping means, constituted of the draw bar (9) and the disc spring assembly (11), for clamping a tool or work pallet on the head portion of the main shaft is reliably lubricated. Further, the device has reduced friction and breakage in the clamping means, and has long life.