JPH05269622A - Method for cutting thread on outer circumferential surface of pipe end - Google Patents

Abstract

PURPOSE:To prevent a burr from being produced, when threads are cut on the outer circumferential surface of a pipe end, after taper threads have been cut on the outer circumferential surface of the pipe end, by chamfering the final terminal outer circumferential surface of the pipe end toward the pipe end. CONSTITUTION:First, taper threads 3 are formed on the outer circumferential surface of the pipe end of a steel pipe 1 at a taper angle theta1. Then, a chamfer 2 is formed at a chamfer angle theta2. In this case, chamfering is carried out toward the direction of A. If the chamfering is carried out in the direction of B reverse to the direction of A, since the relationship between the angle alpha and the angle betabecomes alpha<beta, a burr 24 is produced at the part of the angle alpha. Thus, there is no factor to produce a burr during thread cutting, so that no burr 24 is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting method for threading a taper screw on the outer peripheral surface of a pipe end of a steel pipe such as an oil well pipe which requires high airtightness of a joint.

[0002]

2. Description of the Related Art Joints for connecting steel pipes are formed at both ends of the outer peripheral surface of a seamless steel pipe mainly used for excavating oil wells for pumping oil and for pumping oil from oil wells. It FIG. 2 is a cross-sectional view showing an example of a joint portion formed on such a steel pipe. The screw 22 of the joint portion 21 has a diameter (D) connecting the outer peripheral surfaces with the pipe end final end 21a.
Is formed as a taper screw (taper is about 1/16) that increases from the center to the center in the longitudinal direction. Then, the steel pipes are connected to each other by a joint member 31 having a female screw having a taper opposite to this taper screw.

When the taper screw is threaded on the outer peripheral surface of the above-mentioned steel pipe end, a chamfer process for forming a chamfer having an angle larger than the taper angle of the taper screw is applied to the outer surface of the final end of the pipe end in advance. This is because unless the chamfer is formed, the final end face of the pipe end and the outer peripheral face of the screw are substantially orthogonal to each other, so that workability is significantly impaired when connecting the pipes. Then, after chamfering, the steel pipe is fixed so as not to move with a chuck, and a cutting die called a checker is provided in a die having a hollow portion at the center, and the cutting edges are arranged so as to face the hollow portion of the die. , The die is rotated by a rotating mechanism to approach the steel pipe end, and the checker is cut into the outer surface of the pipe end.

[0004]

However, the conventional thread cutting method for the outer peripheral surface of the pipe has the following problems. That is, as shown in the explanatory view of FIG. 3, in the conventional thread cutting method for the outer peripheral surface of the pipe end, first, a chamfer 23 is formed with a chamfer angle of θ ₂ using a cutting tool, and then a taper angle of θ ₁ is formed. Although the taper screw 22 is formed by, the thread shape of the chamfered portion is an incomplete thread in which the portion 22a indicated by the dotted line is missing. When this imperfect thread is formed, a space is created between the thread cutting blade checker and the thread cutting tube, and the burr 24 is inevitably generated in this space. Since it is a general quality requirement level of customers that the burr 24 should not be present, it must be removed using a flap wheel or the like, and this work is a general work of thread cutting work. There was a problem that it reduced the efficiency.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for threading the outer peripheral surface of a pipe end without causing burrs.

[0006]

A pipe end outer peripheral surface threading method according to the present invention is a pipe end outer peripheral surface for chamfering a final end outer surface of a pipe end while threading a taper screw on the outer peripheral surface of the pipe end. In the thread cutting method, a taper screw is threaded on the outer peripheral surface of the pipe end, and then the outer surface of the final end portion of the pipe end is chamfered in the pipe end direction.

[0007]

In the method of threading the outer peripheral surface of the pipe according to the present invention, after the taper screw is threaded on the outer peripheral surface of the pipe end, the outer surface of the final end of the pipe end is chamfered. Is not formed, and burr does not occur.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pipe end outer peripheral surface threading method according to one embodiment of the present invention will be described with reference to FIGS. 1 (a) and (b). In the pipe end outer peripheral surface thread cutting method of one embodiment of the present invention,
First, the taper screw 3 is formed on the outer peripheral surface of the steel pipe 1 at a taper angle of θ ₁ . Then, after that, the chamfer 2 is formed at a chamfer angle of θ ₂ . In this case, the chamfering process is performed in the direction A shown in the drawing. if,
As shown in FIG. 1B, when machining is performed in the direction B as opposed to the direction A, the angle α and the angle β have a relationship of α <β, so that the burr 24 is generated in the portion of the angle α. . 1 of the present invention
Since the pipe end outer peripheral surface threading method of the embodiment is performed as described above, there is no element for generating burrs during threading unlike the prior art, and burrs do not occur.

[0009]

EFFECTS OF THE INVENTION According to the present invention, burrs do not occur when threads are cut on the outer peripheral surface of the pipe end.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a method of threading a pipe end outer peripheral surface according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example of a joint portion formed on a steel pipe.

FIG. 3 is an explanatory view showing a conventional method for threading the outer peripheral surface of a pipe end.

[Explanation of symbols]

 1 Steel pipe 2 Chamfer 3 Tapered screw

Claims (1)

[Claims] 1. A method of threading a taper screw on the outer peripheral surface of a pipe end and chamfering the outer surface of the final end of the pipe end, wherein a taper screw is threaded on the outer peripheral surface of the pipe end. After that, the outer peripheral surface of the final end of the pipe end is chamfered in the pipe end direction.