| 摘要 |
PURPOSE: A hammer bit structure of a ground boring device is provided to improve ground boring efficiency by increasing the contact area of a bit and the ground. CONSTITUTION: A hammer bit structure of a ground boring device comprises a bit shaft(210) and an expansion portion(280). The expansion portion is extended from the bit shaft and comprises a bit lower body(220), a center bit(230), multiple auxiliary bits(250), and bit coupling members. The bit lower body is integrally connected to the bit shaft. The center bit is rotatably coupled to the bottom of the bit lower body. The auxiliary bits are formed along the circumference of the center bit and are rotatably coupled to the bottom of the bit lower body. The bit coupling members rotatably couple the center and auxiliary bits to the bit lower body. |
