Impact-type composite threaded-connection drilling tool

Abstract

The invention discloses an impact-type composite threaded-connection drilling tool which belongs to an impact-type drilling drill. The invention aims to provide the impact-type drilling tool of which a trouser body and a drilling rod have long service lives. The tool comprises the trouser body and the drilling rod which is in a fitting connection with a taper blind hole via outer threads, wherein when an outer thread section (2-1) and a threaded blind hole (1-2) are screwed down, the front end face (2-5) of a transition section (2-4) can touch the hole bottom (1-1) of the threaded blind hole (1-2); and a thread tooth shape of the threaded blind hole (1-2) is composed of a straight-line inner thread tooth top (3), a curve-shaped inner thread tooth bottom (5) and two sections of straight-line inner thread tooth sides (4), and a thread tooth shape of the outer thread section (2-1) is composed of a straight-line outer thread tooth bottom (6), a curve-shaped outer thread tooth top (8) and two sections of straight-line outer thread tooth sides (7). The drilling tool disclosed by the invention is characterized in that the trouser body and the drilling rod are not broken easily; processing is easy; and the service lives are long. The drilling tool is an improved structure of the impact-type drilling tool.

Description

technical field [0001] The invention relates to an impact type rock drilling tool, in particular to an impact type composite thread connection rock drilling tool. Background technique [0002] At present, the percussive rock drilling tool is usually formed by connecting the drill rod with the trouser body of the drill bit through threads. During the rock drilling process, the stress on the drill rod and the trouser body is relatively complicated and harsh, which may easily cause the drill tool to fail and affect the life of the drill tool. Observation found that there are two main forms of drilling tool failure: 1) fracture occurs near the end of the external thread section of the drill rod; 2) the area between the end of the internal thread of the blind threaded hole of the trouser body and the bottom of the screw hole is prone to fracture. After analysis, the main reasons for the fracture of the drill rod or trousers are as follows: [0003] 1) Since the stress is mostly...

AI Technical Summary

Problems solved by technology

In actual use, even if the fit relationship between the two inner tapered surfaces and the shaft shoulder is handled well (the interference degree of over-positioning is small), but when the drilling tool is deformed under load (especially near the end surface of the inner thread) It is very likely that the bending moment will be borne by the right-angled end face of the drill rod shaft shoulder (or the corresponding internal thread end face) and the cone surface at the front end of the external thread section of the drill rod, resulting in a sudden reduction in the bearing force arm and an increase in the local stress of the bending moment

At the same time, when the right-angled end face of the shaft shoulder (or the end face of the internal thread) is not uniformly stressed, the impact force transmitted (the main load transmitted by the combined component) will further increase the degree of local stress concentration, resulting in failure of the part in a short time

[0006] In addition, "CN10289110B" discloses a "drill bit for percussive rock drilling". This patent uses a section of internal thread to replace the relief groove in the threaded blind hole, although it can overcome the thinner trouser wall at the relief groove. defects, but the internal thread processing is more difficult

Not only that, due to the cancellation of the undercut, the internal thread extends all the way to the bottom of the threaded blind hole; therefore, a stress concentration will be formed between the end of the internal thread and the bottom of the threaded blind hole, resulting in the intersection of the internal thread and the bottom of the hole prone to cracks

In addition, since the drill rod of this patent is not equipped with a shaft shoulder, the end face of the trouser body and the thread occlusal line are similar to a simply supported beam structure, and the external thread will inevitably break at the thread occlusal line under the action of the bending moment, which is also the current traditional external thread. The main failure mode of thread

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