A method for forming a threaded steel pipe

Abstract

The invention discloses a method for forming a threaded steel pipe. First, a section of threaded steel pipe that has been rolled and is ready to be cut is selected. The cutting point of a bite line at a cutting port on the front end of the threaded steel pipe is used as a reference. The length is selected as required and the threaded steel pipe is cut at the rear end. At the newly formed cutting port, the cutting point of the bite line and the cutting point of the bite line at the front end are in the same horizontal plane and are symmetrical front to back. Subsequently, a forming device is arranged in the cut threaded steel pipe. During forming, the cutting point of the bite line at the cutting port of the pipe is used as a positioning point. In this scheme, the front and rear elliptical threaded pipes can be well butted in the original threaded state. At the same time, a hydraulic forming device is used to form the pipe in the pipe, which is beneficial to the control of the circumferential shape after forming.

Description

Technical Field

[0001] The invention relates to the field of production and installation of threaded steel pipes, and in particular to a method for forming a threaded steel pipe. Background Art

[0002] After the threaded steel pipe is buried, it often deforms, its height decreases, and its width increases, which makes it impossible for vehicles on the top road to pass normally, affecting normal use. Therefore, it is necessary to pre-deform the pipe vertically into an elliptical shape.

[0003] If the tooling is used to press the outside of the pipe, the tooling itself is large and bulky, and will cause irregular deformation of the pipe, which is difficult to control. In addition, since the cross-section of the pipe mouth of the threaded steel pipe is corrugated, the shape of the pipe mouth cross-section will change when the position of the threaded steel pipe is cut off. When the pipes are butt-jointed and installed, if it is a circular pipe, the angle of the next pipe section can be rotated to adjust it to ensure that the threads of the previous pipe section and the next pipe section are aligned and form a consistent thread line at the joint. However, in the case of an elliptical pipe, if the next pipe section is rotated, it cannot be connected to the previous pipe section in the original thread state. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a method for expanding a threaded steel pipe that enables elliptical front and rear threaded pipes to be butt-jointed in their original threaded state.

[0005] Technical solution: The method for forming a threaded steel pipe according to the present invention comprises the following steps:

[0006] (1) Select a section of threaded steel pipe that has been rolled and is ready to be cut, and take the cutting point of the bite line at the front end of the cut-off of the threaded steel pipe as the reference, select the length as needed and cut the threaded steel pipe at the rear end. At the new cut-off, the cutting point of the bite line is in the same horizontal plane as the cutting point of the bite line at the front end and is symmetrical from front to back;

[0007] (2) An expansion device is arranged in the cut threaded steel pipe. During the expansion, the cutting point of the bite line at the cut end of the pipe is used as the positioning point.

[0008] By adopting the above technical solution, the front and rear elliptical threaded pipes can be well connected in the original threaded state. At the same time, a hydraulic expansion device is used to expand the pipe, which is beneficial to the control of the circumferential shape after expansion.

[0009] Preferably, in step (2), the shape of the expansion plate in the expansion device is consistent with the required shape of the pipe after deformation, which can improve work efficiency and ensure that the shape after expansion meets the requirements.

[0010] Preferably, the cut-off points of the bite lines of all pipe sections of the same batch and the same specification are expanded at the same position, so that the consistency of the front and rear pipe sections after connection can be ensured.

[0011] Preferably, the swollen shape of the threaded steel pipe is an ellipse.

[0012] Preferably, the expanded shape of the threaded steel pipe is a box arch or a polygonal arch.

[0013] Beneficial effect: Compared with the prior art, the present invention has the significant advantage that it can enable the front and rear elliptical threaded pipes to be butt-jointed in the original threaded state, and is also beneficial to the control of the circumferential shape after expansion. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side structural diagram of the threaded steel pipe in the processing method of the present invention;

[0015] Figure 2 It is a cross-sectional view of a threaded steel pipe in the processing method of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0017] like Figure 1 and 2 As shown, the expansion processing method of the threaded steel pipe comprises the following steps:

[0018] (1) Select a section of threaded steel pipe that has been rolled and is ready to be cut, and take the cutting point of the bite line at the front end of the cut-off of the threaded steel pipe as the reference, select the length as needed and cut the threaded steel pipe at the rear end. At the new cut-off, the cutting point of the bite line is symmetrical with the cutting point of the bite line at the front end in the same horizontal plane;

[0019] (2) An expansion device is arranged in the cut threaded steel pipe, and the cutting point of the bite line at the cut end of the pipe is used as the positioning point. The shape of the expansion plate in the expansion device is consistent with the required shape of the pipe after deformation, and it is ensured that the cutting points of the bite line of all pipe sections of the same batch and the same specification are expanded at the same position.

[0020] Finally, the shape of the expanded threaded steel pipe can be oval, box arch or polygonal arch.

Claims

1. A method for forming a threaded steel pipe, characterized in that: The following steps are involved: (1) Select a section of threaded steel pipe that has been rolled and is ready to be cut, and take the cutting point of the bite line at the front end of the cut-off of the threaded steel pipe as the reference, select the length as needed and cut the threaded steel pipe at the rear end. At the new cut-off, the cutting point of the bite line is in the same horizontal plane as the cutting point of the bite line at the front end and is symmetrical from front to back; (2) An expansion device is arranged in the cut threaded steel pipe. During the expansion, the cutting point of the bite line at the cut end of the pipe is used as the positioning point.

2. The method for forming a threaded steel pipe according to claim 1, characterized in that: In step (2), the shape of the expansion plate in the expansion device is consistent with the required shape of the pipe after deformation.

3. The method for forming a threaded steel pipe according to claim 1, characterized in that: The bite line cutting points of all pipe sections of the same batch and the same specification are expanded at the same position.

4. The method for forming a threaded steel pipe according to claim 1, characterized in that: The swollen shape of the threaded steel pipe is an ellipse.

5. The method for forming a threaded steel pipe according to claim 1, characterized in that: The bulged shape of the threaded steel pipe is a box arch or a polygonal arch.

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