Abstract

The present invention relates to a hammer coupled to the bottom end of a connecting rod assembled to an excavator, and particularly, to a variably expandable hammer comprising: a hammer main body (100) including a rod connecting adapter (110) for coupling a connecting rod to the top end thereof; a hydraulic cylinder (300) installed within the upper portion of the hammer main body (100) to vertically expand and contract; an elevating block (400) coupled to the bottom of the hydraulic cylinder (300) to raise and lower the inside of the hammer main body (100) according to the expansion/contraction of the hydraulic cylinder (300); a plurality of air hammers (200) installed with a certain distance therebetween on the elevating block (400), the top ends of which are pivotably pin-coupled to the elevating block (400) and the bottom ends of which have hammer bits (210) mounted thereon; a ball mount (510) coupled to the air hammers (200), respectively, and formed having a convexly curved outer periphery and a cavity (511) defined through the center thereof, such that the body of the air hammer (200) passes through the cavity (511) and is slidably coupled to the ball mount; and a ball mount support block (520) coupled at the bottom of the hammer main body (100), including a curved surface corresponding to the outer periphery of the ball mount (510), and having a plurality of ball mount receptacles (521) defined vertically therethrough for receiving the respective ball mounts (510), wherein the hammer bit (210) projects downward from the ball mount (510).

IPC Classes  ?

• E21B 7/28 - Enlarging drilled holes, e.g. by counterboring
• E21B 1/30 - Percussion drilling with a reciprocating impulse member the impulse member being a piston driven directly by fluid pressure by air, steam or gas pressure