Patent ID: 8100612
Filing Date: 2012-01-24
Classification: B23B,B28D,Y10S,Y10T

Abstract:
1. A core drill comprising: a base body including a shank; and a drill core body including a drill cutting blade, a connection opening portion of the drill core body being attached to the base body, wherein the connection opening portion of the drill core body is provided with a concave portion forming member including a large-diameter hole cutting blade, the large-diameter hole cutting blade is provided outside the drill cutting blade in a radial direction of the connection opening portion, and the base body, the drill core body and the concave portion forming member are connected to each other by causing an engagement projection formed so as to project in the connection opening portion of the drill core body to engage with an engagement concave portion provided on the base body, and wherein the concave portion forming member includes a concave portion core body which is radially larger than the drill core body, the large-diameter hole cutting blade is provided at a lower end opening edge portion of the concave portion core body, an upper end opening portion of the concave portion core body is reduced in diameter so as to form a connection opening portion, and the connection opening portion externally fits the connection opening portion of the drill core body so as to be connected thereto.