PURPOSE: To prevent abnormal wear of alloy part of a tip or decrease in bit service life caused by early wear of the tip by making large the degree of freedom in design of arragement or sizes of blade body or water holes, while making the hole tip out of cemented carbide.
CONSTITUTION: The whole of tip 2 is made of cemented carbide and a button- like blade body 5 is integrated with the plane of te tip 6 so as to project therefrom. At a core of the tip 2 a water hole base paret 9 is arranged, and a narrow water hole opening in the bit tip is branched from the tip. A threaded hole 12 is formed at the rear part of a base 3 of a steel cylinder, and a fitted recess 13 formed at the tip of the alloy 3 and the threaded hole 12 are communicated with each other through the water hole 15. The tip 2 and the alloy 3 are communicated with each other. The two 2, 3 are fixed under a state that afitting projection part 7 is fited into the recess 13 of the alloy 3. Striking force or thrust conveyed to the alloy 3 is tranmitted to a rear end face 7a of fitting projection paret of the tip 2 form a bottom face of fitting recess 13, and thus transmission of force is made efficiently so that overload is not applied to the alloy 3 and the tip 2.
| JPH10227190 | EXCAVATOR |
| JPH05125886 | DRILLING TOOL |
| WO/2014/136727 | DIGGING BIT |
AKIYOSHI NAOYOSHI
OKADA KENJI
MIKAMI YOSHIICHI