| 摘要 |
In a system that includes a linearly movable carriage or the like, a mechanism to convert rotary motion of a leadscrew to linear motion of a nut and, hence, linear movement of the carriage to which the nut is mechanically secured. The leadscrew has a special threadform and the nut has a special threadform that matches the threadform of the leadscrew with a pressurized fluid interface therebetween, there being both axial clearance and radial clearance sufficient to accommodate angular and lateral misalignment between the leadscrew and the carriage. Shallow independent grooves along each side of the nut's helical threadform act to equalize fluid pressure across each respective side of the threadform and orifices or other fluid flow control devices connect to the grooves or passages to permit introduction of high pressure air or other fluid thereto. Exhausts are provided from the region by radial clearance between the leadscrew threadform and the nut threadform. Both threadforms are ideally in the form of square threads, i.e., threads whose axial thickness of the root of each tooth substantially equals the axial thickness of the peak thereof, i.e., rectangular threads. Also, for best results, the nut should have a single threadform of depth equal to about one-quarter the major diameter of the leadscrew, where the final shape of the nut thread is finish cast with epoxy to the shape of the screw using putty and mold release wax to attain necessary oil flow grooves and radial and axial clearance.
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