BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bit for a multi-air hammer drill. In particular, a multi-air for excavating the ground while engaging and rotating and conveying a plurality of air hammer drills that actuate the piston by a pressure air from the ground and strike the bit is applied. It relates to a bit for a hammer drill.;According to the present invention, a predetermined portion of the circular outer surface of the multi-air hammer drill bit 14 is formed by vacancy, and the vacancy is made as the multi-bit outer diameter of the multi-air hammer drill. Therefore, the outer diameter areas of the multi-bits 14 and 14 can be largely occupied by the vacancies 34A, 34B, and 34C, and a plurality of metal tips 36, 36... Can be installed in the vacancies 34A, 34B, and 34C. Therefore, digging efficiency is improved. In addition, the bit 14 can be manufactured only by processing a bit into predetermined | prescribed circumferential material by lathe processing, and then cutting a vacancy part by machine tools, such as a milling machine, or by hand. In addition, when the bit 14 is detachably fixed to the bit fixing part of the air hammer drill 11 by a spline coupling mechanism, the plurality of vacant portions 34A, 34B, 34C of the bit 14 can be rotated and used. 14) can extend the service life.
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