Light core rod for hot expanding of steel pipe

Abstract

The utility model relates to the technical field of steel pipe plastic deformation, and discloses a light core rod for steel pipe hot expanding, which comprises a leading-in section, a deformation section, a sizing section and a straightening section which are sequentially connected, and the deformation section, the sizing section and the straightening section are hollow and form communicated hollow cavities. A water inlet communicated with the hollow cavity is formed in the inner wall of the end, close to the guide-in section, of the deformation section, a water outlet communicated with the hollow cavity is formed in the inner wall of the end, away from the sizing section, of the straightening section, and the water inlet and the water outlet are connected with a cooling water pipeline. The light core rod for hot expanding of the steel pipe is provided with the hollow cavity, the weight of the core rod can be reduced, materials are saved, the core rod can be cooled through cooling water, the linear expansion amount of the deformation section and the sizing section at the operation temperature is reduced, and the size precision of the hot expanding steel pipe is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to steel pipe plastic deformation technical field especially relates to a light core rod for steel pipe hot expanding. BACKGROUND

[0002] The core rod is an important die in the production of the medium-frequency hot expanding steel pipe and is an important part for ensuring the size precision of the hot expanding steel pipe. The deformation section of the hot expanding core rod works at the hot expanding temperature (750 DEG C~900 DEG C) for a long time and is usually made of heat-resistant stainless steel. For the large-diameter seamless steel pipe, the required core rod is large in size and heavy in weight, which not only has high material cost but also easily causes the uneven wall thickness of the steel pipe in the expanding process. In addition, the linear expansion coefficient of the heat-resistant stainless steel is large at the hot expanding operation temperature, the diameters of the deformation section and the sizing section of the core rod change greatly, and the inner diameter size of the hot expanding steel pipe is greatly affected. SUMMARY

[0003] In view of the above problems, the utility model discloses a light core rod for steel pipe hot expanding, which meets the hot expanding requirement of the large-diameter steel pipe and ensures the accurate and stable size of the steel pipe.

[0004] To achieve the above purpose, the utility model adopts the following technical scheme:

[0005] A light core rod for steel pipe hot expanding, comprising a guide-in section, a deformation section, a sizing section and a straightening section which are sequentially connected, the deformation section, the sizing section and the straightening section are all hollow and form a hollow cavity which is communicated, a water inlet is arranged on the inner wall of one end of the deformation section close to the guide-in section and communicated with the hollow cavity, a water outlet is arranged on the inner wall of one end of the straightening section away from the sizing section and communicated with the hollow cavity, and the water inlet and the water outlet are respectively connected with a cooling water pipeline.

[0006] As an optional scheme, the deformation section is conical, a first bevel is arranged at the small end of the cone, a second bevel is arranged at the large end of the cone, the deformation section is welded with the guide-in section through the first bevel, and the deformation section is welded with the sizing section through the second bevel.

[0007] As an optional scheme, the sizing section and the straightening section are integrally cast, an end of the sizing section close to the deformation section is provided with a third bevel which has the same angle as the second bevel, the root of the third bevel is welded with the root of the second bevel, the weld is flush with the inner ring of the hollow cavity, a cylindrical plate which is flush with the outer ring of the hollow cavity is arranged in the gap between the third bevel and the second bevel, the outer side of the cylindrical plate is welded, and the weld is flush with the outer surface of the deformation section and the outer surface of the sizing section.

[0008] As an optional scheme, an end of the guide-in section close to the deformation section is provided with a fourth bevel which has the same angle as the first bevel.

[0009] As an alternative, the angle of the first bevel is 10° to 15°, and the angle of the second bevel is 12° to 18°.

[0010] The beneficial effects of this utility model are:

[0011] The lightweight mandrel for hot expansion of steel pipe has a hollow cavity, which not only reduces the weight of the mandrel and saves materials, but also allows the mandrel to be cooled by cooling water, reducing the linear expansion of the deformation section and sizing section at the operating temperature and improving the dimensional accuracy of the hot expanded steel pipe. Attached Figure Description

[0012] Fig. 1 This is a schematic diagram of the structure of the lightweight mandrel for hot expansion of steel pipe provided in this embodiment of the utility model;

[0013] Fig. 2 This is a schematic diagram of the modified segment involved in an embodiment of the present utility model;

[0014] Fig. 3 This is a schematic diagram of the sizing section and straightening section involved in the embodiment of this utility model.

[0015] In the attached image:

[0016] 1. Inlet section; 2. Deformation section; 3. Sizing section; 4. Straightening section; 5. Hollow cavity; 6. Inlet; 7. Outlet; 8. First bevel; 9. Second bevel; 10. Third bevel; 11. Cylindrical plate. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.

[0018] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0019] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0020] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0021] Furthermore, the terms "first" and "second" are merely used to distinguish between different terms in description and do not have any special meaning.

[0022] Please see Figs. 1 to 3 As shown, this embodiment provides a lightweight mandrel for hot expansion of steel pipes, including an inlet section 1, a deformation section 2, a sizing section 3, and a straightening section 4 connected in sequence. The deformation section 2, the sizing section 3, and the straightening section 4 are all hollow and form a connected hollow cavity 5. An inlet 6 communicating with the hollow cavity 5 is provided on the inner wall of the end of the deformation section 2 near the inlet section 1. An outlet 7 communicating with the hollow cavity 5 is provided on the inner wall of the end of the straightening section 4 away from the sizing section 3. The inlet 6 and the outlet 7 are respectively connected to cooling water pipes.

[0023] Therefore, the lightweight mandrel for hot expansion of steel pipe has a hollow cavity 5, which can not only reduce the weight of the mandrel and save materials, but also cool the mandrel with cooling water, reduce the linear expansion of the deformation section 2 and the sizing section 3 at the operating temperature, and improve the dimensional accuracy of the hot expanded steel pipe.

[0024] Optionally, the deformed section 2 is conical, with a first bevel 8 at the small end of the cone and a second bevel 9 at the large end of the cone. The deformed section 2 is welded to the inlet section 1 through the first bevel 8 and to the sizing section 3 through the second bevel 9.

[0025] Therefore, by using segmented welding, the forming difficulty of the mandrel is reduced, especially the forming of the deformed section 2. The design of the first bevel 8 and the second bevel 9 is more conducive to improving the welding effect and appearance, making the connection between the deformed section 2 and the inlet section 1 and the sizing section 3 more solid, ensuring the stability of the mandrel under high temperature and high pressure, and ensuring the efficiency and quality of the hot expansion process.

[0026] Optionally, the sizing section 3 and the straightening section 4 are integrally cast. The end of the sizing section 3 near the deformation section 2 is provided with a third bevel 10 at the same angle as the second bevel 9. The root of the third bevel 10 is welded to the root of the second bevel 9, and the weld is flush with the inner edge of the hollow cavity 5. A cylindrical plate 11 flush with the outer edge of the hollow cavity 5 is provided in the bevel gap between the third bevel 10 and the second bevel 9. The outer side of the cylindrical plate 11 is welded, and the weld is flush with the outer surface of the deformation section 2 and the outer surface of the sizing section 3.

[0027] Thus, the structure of two layers of welding and cylindrical plate 11 ensures the sealing of the hollow cavity 5, further enhances the overall strength and high temperature resistance of the mandrel, effectively prevents cooling water leakage, and achieves a reliable connection between the deformation section 2 and the sizing section 3.

[0028] Optionally, the end of the guide segment 1 near the deformed segment 2 is provided with a fourth bevel at the same angle as the first bevel 8. Similarly, the welding of the fourth bevel with the first bevel 8 enhances the connection stability and appearance quality between the guide segment 1 and the deformed segment 2.

[0029] Optionally, the angle of the first bevel 8 is 10° to 15°, and the angle of the second bevel 9 is 12° to 18°. Within this angle range, the welding stress distribution is uniform, reducing the risk of hot cracking and improving the overall durability and operational safety of the mandrel.

[0030] In addition, inlet 6 and outlet 7 are connected to external water pipes. The external water pipes are equipped with shut-off valves and quick-connect fittings. After the quick-connect fittings are connected to the soft water pipes, the shut-off valves and quick-connect fittings are located outside the hot-expanded steel pipes. After the hot expansion of the steel pipes is completed, the shut-off valves are closed, the connection with the soft water pipes is disconnected from the quick-connect fittings, and the hot-expanded steel pipes are lifted off the workbench.

[0031] In summary, the lightweight mandrels used for hot expansion of steel pipes described above have the following advantages:

[0032] 1) Cooling water is introduced through the hollow cavity 5 to reduce the operating temperature of the deformation section 2, thereby reducing the linear expansion of the deformation section 2 at the operating temperature, which is beneficial to improving the dimensional accuracy of the hot-expanded steel pipe.

[0033] 2) The hollow cavity structure can save on the amount of heat-resistant stainless steel used, thus reducing material costs;

[0034] 3) The hollow cavity structure 5 can reduce the weight of the mandrel, reduce the problem of uneven steel pipe wall thickness caused by excessive mandrel weight, and improve the forming quality of the steel pipe.

[0035] 4) Segmented welding and beveling design improve welding quality and appearance, and make it easier to manufacture mandrels.

[0036] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A light weight mandrel for hot expansion of steel pipes, characterized in that, The device comprises a leading-in section (1), a deformation section (2), a sizing section (3) and a straightening section (4) connected in sequence, the deformation section (2), the sizing section (3) and the straightening section (4) are hollow and form a hollow cavity (5) in communication, a water inlet (6) is arranged on the inner wall of the end of the deformation section (2) close to the leading-in section (1) and communicates with the hollow cavity (5), a water outlet (7) is arranged on the inner wall of the end of the straightening section (4) away from the sizing section (3) and communicates with the hollow cavity (5), and the water inlet (6) and the water outlet (7) are respectively connected with a cooling water pipeline.

2. The light weight core rod for a steel pipe hot expander according to claim 1, characterized by The deformation section (2) is conical, a first bevel (8) is arranged at the small end of the cone, a second bevel (9) is arranged at the large end of the cone, the deformation section (2) is welded with the leading-in section (1) through the first bevel (8), and the deformation section (2) is welded with the sizing section (3) through the second bevel (9).

3. The light weight mandrel for a steel pipe hot expander according to claim 2, characterized by The sizing section (3) and the straightening section (4) are integrally formed by casting, a third bevel (10) with the same angle as the second bevel (9) is arranged on the end of the sizing section (3) close to the deformation section (2), the root of the third bevel (10) is welded with the root of the second bevel (9), the weld is flush with the inner ring of the hollow cavity (5), a cylindrical plate (11) flush with the outer ring of the hollow cavity (5) is arranged in the gap between the third bevel (10) and the second bevel (9), the outer side of the cylindrical plate (11) is welded, and the weld is flush with the outer surface of the deformation section (2) and the outer surface of the sizing section (3).

4. The light weight mandrel for hot expansion of steel pipes according to claim 2, characterized by A fourth bevel with the same angle as the first bevel (8) is arranged on the end of the leading-in section (1) close to the deformation section (2).

5. The light weight mandrel for hot expansion of steel pipes according to claim 2, characterized by The angle of the first bevel (8) is 10°-15°, and the angle of the second bevel (9) is 12°-18°.

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