| 摘要 |
<p>592427 Disclosed is a vibratory drill head assembly to allow for more efficient rock drilling. The drill assembly includes a shaft having a shaft axis, an oscillator assembly operatively associated with the shaft, the oscillator assembly having at least one eccentrically weighted rotor configured to rotate about a pivot point to generate an oscillating vibratory force, wherein an oscillation centerline is defined transverse to the shaft axis and including the pivot point. The drill head assembly also includes a lower bearing coupled to the shaft on a first side of the oscillation centerline and an upper bearing coupled to the shaft on a second side of the oscillation centerline, the second side being opposite the first side. A preload assembly is coupled to the shaft, the preload assembly including a base nut configured to be selectively threaded in position on the externally threaded second end of the shaft; and a plurality of preloaders extending through the base nut. Advancement of at least one preloader of the plurality of preloaders relative to the base nut applies a preload force on at least one bearing.</p> |
