| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a conventional boring air hammer: that, in order to increase the impact force of the air hammer, there are no other means than to elongate a cylinder and install a long and heavy air hammer or to increase the diameter of the cylinder and install a heavy air hammer, which means that a plurality of types of air hammers with different weights must be prepared at all times and changed for use. SOLUTION: An air hammer 12 is vertically slidably fitted and installed around the outer periphery of a center shaft 1 having an auger and a rotary rod 10 or the like mounted at its upper end and a boring member 11 mounted at its lower end. A center hole 2 in the center shaft 1 is formed with a valve chamber 3, a valve seat 4, an air feed port 5, an exhaust port 6 and an exhaust hole 7. An air valve having a piston valve 8 mounted in the valve chamber 3 and the valve seat 4 is provided. High-pressure air valving operation done with the air valve causes the air hammer 12 to slide up and down at high speeds and continuously collide against the boring member 11 to achieve boring. Also, an adjusting weight 16 in the form of a cylinder or the like is detachably and replaceably provided on the outer periphery of the air hammer 12. COPYRIGHT: (C)2003,JPO
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