Combined drill bit

Abstract

The invention discloses a combined drill bit. The combined drill bit comprises a drill shank, a hollow drill bit body and a twist drill bit body. The hollow drill bit body and the twist drill bit body are made of metal. The hollow drill bit body comprises a tubular base body, cutting teeth arranged at the bottom end of the tubular base body, and a linkage part located in the tubular base body. The twist drill bit body comprises a fixing part connected with the drill shank and a cutting part away from the drill shank. The drill shank is made of plastic and comprises an injection-molded connection part connected with the hollow drill bit body and an installation part away from one end of the hollow drill bit body. A gear-shaped linkage hole is formed in the center of the linkage part of the hollow drill bit body. Concave areas are formed in the portions, at the upper end and the lower end of the linkage part, of the tubular base body. The injection-molded part of the drill shank is provided with a linkage gear matched with the linkage hole. The fixing part of the twist drill bit body is provided with a plurality of reinforcement holes which are transversely through in the direction perpendicular to the direction of the center axis. When the drill shank is manufactured through injection molding, the reinforcement holes are also filled with plastic. The strength of the combined drill bit can be guaranteed, and the manufacturing cost of the combined drill bit can be effectively reduced.

Description

[0001] This case is a divisional application of an invention patent application with an application date of "November 26, 2012", an application number of "201210487843X", and a title of "composite drill bit". technical field [0002] The present invention relates to the technical field of drill bit structure design, and in particular relates to a composite drill bit. Background technique [0003] attached figure 1 It is a cross-sectional view of a traditional drill bit, which includes a drill shank (91), a hollow drill bit (92), a twist drill (93) and a fastening screw (94); a blind hole is provided at the center of one end of the drill shank ( 911), the outer peripheral wall of this end is provided with an external thread connection part (912), and a fastening hole (913) communicating with the blind hole is provided on the drill shank body; the hollow drill bit is screwed and fixed on the outer surface of the drill shank. On the threaded connection part, one end of the twi...

AI Technical Summary

Problems solved by technology

[0004] The disadvantages of this traditional drill bit are: its structure is relatively complicated, and the manufacturing process is relatively cumbersome; in addition, its drill shank, drill bit and twist drill are all made of metal, which is heavy in weight and high in cost.

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