Importance

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Abstract

Sonic energy in a cycloidal or quadrature action pattern is generated in a drill stem by means of a sonic oscillator employing an eccentrically weighted rotor. The stem is coupled to the drill bit by means of a rocker-type joint thereby forming a pivot fulcrum for limited motion of the bit both vertically and laterally in a nutating path. The rocker action develops a powerful longitudinal vibratory force at the cutter teeth for more effective drilling action. The rocker joint in one embodiment is formed by horizontal and vertical shoulders formed in the top end of the bit assembly by virtue of an undercut portion formed in such assembly in which the lower edge of the drilling jacket is received with the bottom edge of such jacket opposite the horizontal shoulder and the inner surfaces of the jacket opposite the vertical shoulder. In another embodiment, suitable for use where precise control of drilling direction is required, limited rocking motion is provided by means of a special fulcrum guidance structure. In still a third embodiment adapted for use as a rock splitter, incorporated into a rock stripping wheeled loader, the rocking motion is constrained by means of a centering spring which may be of an elastomeric material.

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First Claim