Online induction heating and shallow hardening process after outer thread processing of pipe end

Abstract

The invention relates to an online induction heating superficial-layer hardening process and device after the outer thread processing of a pipe end, belonging to the technical field of geological drilling pipe machining. The invention has the technical scheme that the process comprises the following steps of: machining the end thread of a pipe on a lathe, retreating a cutting tool under the condition of motionless pipe, sheathing an induction coil at the threaded end of the pipe, and moving an induction mechanism to heat and shallowly harden the end thread of the pipe. The invention has the advantages that the hardening depth is 0.4-0.8 mm and does not 20% of the thickness of a thin-wall working piece, the hardening effect of the working piece is ensured, and the working piece is also ensured to have certain toughness; the induction mechanism is directly installed on the lathe and is simple and feasible, and the hardening effect can be effectively ensured; the problem of non-concentricity brought by secondary card mounting is avoided, and the evenness of the hardening layer can be ensured; and the device has reliable action and sensitive response, and the shallow hardening quality is ensured.

Description

technical field [0001] The invention relates to an on-line induction heating shallow layer hardening process after external thread processing of a pipe end, belonging to the technical field of geological drilling pipe processing. Background technique [0002] At present, induction heating surface hardening technology has become a mature process technology and is widely used in the production of parts that require surface hardening. Due to the three major effects of high-frequency current (skin effect, sharp corner effect, and proximity effect), the current penetration depth of the pipe is deeper than that of the solid workpiece during induction heating, so the heating depth is larger. The thickness of conventional induction heating surface hardening is greater than 0.8mm (according to needs, it can reach a thickness of several millimeters), plus the heat-affected zone, the thickness of the tissue changed by heating is usually more than 1mm. It may be deeper in the case of t...

AI Technical Summary

Problems solved by technology

However, for the drill pipe with a small wall thickness (the wall thickness of the drill pipe at the threaded part is about 3mm), the hardened layer is too thick, which will make the ratio of the hardened layer and the non-hardened layer out of balance, affecting the performance of the non-hardened layer material inside the thread, and then Affect the life of drill pipe

At present, in the production of drilling pipes, the thread at the end of the pipe is the same as that of the matrix structure (the same processing conditions). Although the end thread is strengthened, there are many problems: such as different degrees of hardening and inappropriate hardening thickness (the above-mentioned hardened layer out of proportion with the non-hardened layer), high hardening cost, complicated processing technology, etc.

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