| 摘要 |
<p>The present invention relates to raise-type earth boring drills and more particularly, to rais drills having shock elements for absorbing bending loads passing through the drill. During a raise drilling operation, a tremendous amount of wear and stress is imposed upon the raise bit and upon the drive stem thereof. Removable drive stems are used to extend the useful life of the bit, but a certain amount of down time is still required to remove and replace the stem. This non-operating time is costly and it is preferable to obtain as long a running time as possible for each bit-stem combination. One area that has not been sufficiently explored in raise drilling is the area relating to improving the operating life of a raise drill drive stem. The present invention accomplished this by providing a shock element in the drill for absorbing the uneven bending and impact type loads on the bit in order to prevent them from being transferred to the drive stem. The raise-type drill according to the present invention includes a drive stem attached to a thrust bearing support plate which, in turn, is interconnected to a main bit body. The interconnection is accomplished on an elastomeric shock element which functions to transfer the thrust and torsional loads from the drive stem to the bit body while absorbing the bending loads passing therethrough.</p> |
