Straightening die and straightening device for hot-expanded seamless steel pipe
By designing the thermal expansion seamless steel pipe straightening mold with arc grooves, the problems of steel pipe surface indentation and high equipment costs are solved, and high-quality straightening and low-cost production are achieved.
Patent Information
- Application Number
- CN202422052309.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-23
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-08-23
AI Technical Summary
When the prior art straightens the thermal expansion seamless steel pipe, it is easy to cause indentation damage on the surface of the steel pipe and protrudes on the inner surface, which cannot meet the product straightness requirements, and the equipment investment is high.
Thermal expansion seamless steel pipe straightening mold is adopted, including connecting plates and press blocks. Arc grooves are set up in the center of the press blocks. The grooves are composed of straight sections and transition sections to increase the contact area and reduce the concentration of contact stress between the steel pipe and the mold.
It reduces the indentation of the steel pipe surface, improves product quality, reduces equipment investment costs, and meets the product straightness requirements.
Smart Images
Figure CN223171656U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a straightening die and a straightening device, in particular to a straightening and aligning device for hot-expanded seamless steel pipes. Background Art
[0002] With the rapid development of China's industry, the demand for high-grade steel, large-diameter and thick-wall seamless steel pipes is increasing day by day. Domestic hot-expanded seamless steel pipes are gradually replacing imported products, and the export volume of domestic hot-expanded products is also increasing. When the seamless steel pipe is hot-expanded, it is heated by a heating coil to about 800 °C. After expansion, the steel pipe needs to be cooled in a static state on the blanking bench. Since the steel pipe itself has no self-rotation function during static placement, the radial heat dissipation and cooling are uneven, resulting in uneven shrinkage of the entire length of the steel pipe in the up, down, left, and right directions. Therefore, the cooled steel pipe will have a side bending phenomenon. In severe cases, the overall straightness exceeds 1%L, which cannot meet the requirement of the product straightness ≤ 0.1%L specified by the standard.
[0003] At present, domestic steel pipe production workshops mainly use multi-angled roll straightening machines to straighten rolled seamless steel pipes, which have good straightening effect and high speed. However, for the straightening of large-diameter and extra-thick-wall steel pipes after hot expansion, if a multi-angled roll straightening machine is used, it will be larger in size, heavier in equipment, and high in cost, even requiring an investment of tens of millions. Therefore, most domestic hot-expanded pipe workshops are equipped with three-point four-column hydraulic straightening machines. This kind of hydraulic straightening machine is lighter in weight and simpler in structure than the multi-angled roll straightening machine, and the equipment investment is much less than that of the angled roll straightening machine. The die of such a four-column hydraulic straightening machine consists of one upper die and two lower dies as a set. After straightening the hot-expanded seamless steel pipe with the existing straightening die, indentation damage often occurs on the outer surface of the steel pipe, and there will be protruding bumps on the inner surface. For steel pipes with such serious problems, users often return the goods. After analysis, when the three-point straightening die straightens, the concave surface of the semi-cylindrical die contacts the cylindrical outer surface of the steel pipe. Before straightening, the bottom plate of the upper die is fixed to the upper and lower movable seats of the hydraulic cylinder with bolts, and the bottom plate of the lower die is fixed to the ground track trolley with bolts. Align the highest point of the maximum deflection of the steel pipe with the upper die, place the two lower dies symmetrically, and according to the analysis of the bending of a small-curvature curved beam in material mechanics theory, for a bent steel pipe, if it is to be made straight, it needs to be overcorrected, that is, adjust the pressing stroke of the upper die to control the reverse bending of the steel pipe. After springback, the steel pipe is straightened. During the reverse bending process, the middle part of the die is separated from the surface of the steel pipe, and only the edges at both ends of the upper die and the inner edges of the lower die contact and exert force on the surface of the steel pipe in a small area, causing the surface of the steel pipe at this place to reach yield and produce irreversible permanent deformation, forming indentation defects. Summary of the Utility Model
[0004] In order to overcome the above deficiencies, the utility model provides a straightening die and a straightening device for hot-expanded seamless steel pipes, which can reduce the indentation generated on the surface of the steel pipe during the straightening process and improve the product quality.
[0005] To achieve this purpose, the structure adopted by the utility model is: a straightening die for hot-expanded seamless steel pipes, including a connecting plate, a pressing block is connected to the bottom of the connecting plate, a groove is arranged in the center of the pressing block, the longitudinal section of the groove is arc-shaped, both ends of the groove are rounded edges, and the groove is composed of one or more of a straight section and a transition section. The straight section is a groove section with a flat contact surface with the steel pipe, and the transition section is a groove section with an arc-shaped contact surface with the steel pipe.
[0006] The groove is a three-section surface, including one straight section and two transition sections. The straight section is located in the center, and the two transition sections are symmetrically connected to both ends of the straight section. The radius of the transition section gradually increases from the straight section to the rounded edge.
[0007] The groove is a two-section surface, including one transition section and one straight section, and the straight section and the transition section are connected to each other.
[0008] A straightening device, including an upper die and two lower dies. The upper die is located above the center of the two lower dies. The top of the upper die is connected to a downward pressing oil cylinder. The lower die is connected to a track trolley. The upper die and the lower die are the above-mentioned straightening dies for hot-expanded seamless steel pipes.
[0009] The groove of the upper die is a three-section surface.
[0010] The groove of the lower die is a two-section surface.
[0011] The two-section surface of the lower die is one transition section and one straight section, and the straight section is close to the center of the two lower dies.
[0012] The beneficial effects are as follows: The structure of the utility model is designed reasonably and ingeniously. When the hot-expanded seamless steel pipe passes through the straightening device, the downward pressing oil cylinder presses down to make the steel pipe bend between the two lower dies, thereby realizing the straightening of the steel pipe. Since the upper die and the lower die adopt straightening dies, during the downward pressing process, the contact surface between the steel pipe and the straightening die is an arc surface, increasing the force-bearing area, thus reducing the indentation formed during the straightening process of the steel pipe and improving the product quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The utility model will be described by way of examples and with reference to the accompanying drawings, wherein:
[0014] Figure 1 is the front view of the straightening die of the utility model;
[0015] Figure 2 is the sectional structure diagram of the three-section surface straightening die
[0016] Figure 3 is the sectional structure diagram of the two-section surface straightening die;
[0017] Figure 4 is the schematic structural diagram of the straightening device. Detailed implementation manners
[0018] The present utility model will be further described in detail below with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only schematically showing the basic structure of the present utility model, so they only show the components related to the present utility model.
[0019] In the description of the utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0020] In the description of the utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements; the fixed connection can be welding or bonding. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.
[0021] As Figures 1-3 shown in the hot-expanded seamless steel pipe straightening die, it includes a connecting plate 11. Connecting holes are provided on the connecting plate 11 for connecting a loading device. A pressing block 12 is connected to the bottom of the connecting plate 11. A groove 13 is provided in the center of the pressing block 12. The groove 13 contacts the steel pipe. The longitudinal section of the groove 13 is arc-shaped. The two ends of the groove 13 are rounded edges 14, with smooth transitions and not easily causing stress concentration to form indentations. The groove 13 is composed of one or more of a straight section 15 and a transition section 16. The straight section 15 is a groove section with a flat contact surface with the steel pipe, and the transition section 16 is a groove section with an arc-shaped contact surface with the steel pipe.
[0022] As Figure 2 shown, the groove 13 has a three-section surface, including one straight section 15 and two transition sections 16. The straight section 15 is located in the center, and the two transition sections 16 are symmetrically connected to both ends of the straight section 15. The radius of the transition section 16 gradually increases from the straight section 15 to the rounded edge 14.
[0023] As Figure 3As shown, the groove 13 has two sections, including a transition section 16 and a straight section 15, and the straight section 15 is connected to the transition section 16.
[0024] As Figure 4 As shown, a straightening device includes an upper die 1 and two lower dies 4. The upper die 1 is located above the center of the two lower dies 4. The top of the upper die 1 is connected to a downward pressure oil cylinder 3, and the groove opens downward. The lower die 4 is connected to a rail trolley 5, and the groove opens upward. The upper die 1 and the lower die 4 are the above-mentioned straightening dies for hot-expanded seamless steel pipes, and the steel pipe 2 passes through between the upper die 1 and the lower die 4.
[0025] The groove of the upper die 1 has three sections.
[0026] The groove of the lower die 4 has two sections, which are a straight section and a transition section connected to each other, and the straight section is close to the center of the two lower dies 4.
[0027] The structure design of the present utility model is reasonable and ingenious. The straightening device using the straightening die for hot-expanded seamless steel pipes can straighten the steel pipe by the method of three-point straightening. Since the contact surface with the steel pipe is arc-shaped, the contact area can be increased, and the indentation caused by excessive bending of the steel pipe and extrusion of the straightening die during the straightening process can be eliminated or reduced. At the same time, the steel pipe rotates forward during the straightening process, so the ovality of the steel pipe can also be corrected, improving the product quality.
[0028] Based on the inspiration of the present utility model, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this utility model. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. The straightening die for hot-expanded seamless steel pipes is characterized in that It includes a connecting plate (11). A pressing block (12) is connected to the bottom of the connecting plate (11). A groove (13) is provided in the center of the pressing block (12). The longitudinal section of the groove (13) is arc-shaped. The two ends of the groove (13) are rounded edges (14). The groove (13) is composed of one or more of a straight section (15) and a transition section (16). The straight section (15) is a groove section with a flat contact surface with the steel pipe, and the transition section (16) is a groove section with an arc-shaped contact surface with the steel pipe.
2. The straightening die for hot-expanded seamless steel pipes according to claim 1, characterized in that The groove (13) is a three-section surface, including one straight section (15) and two transition sections (16). The straight section (15) is located in the center, and the two transition sections (16) are symmetrically connected to both ends of the straight section (15). The radius of the transition section (16) gradually increases from the straight section (15) to the rounded edge (14).
3. The straightening die for hot-expanded seamless steel pipes according to claim 1, characterized in that, The groove (13) is a two-section surface, including one transition section (16) and one straight section (15). The straight section (15) and the transition section (16) are connected to each other.
4. Straightening device, characterized in that, It includes an upper die (1) and two lower dies (4). The upper die (1) is located above the center of the two lower dies (4). A downward pressing oil cylinder (3) is connected to the top of the upper die (1). The lower die (4) is connected to a rail trolley (5). The upper die (1) and the lower die (4) are the straightening dies for hot-expanded seamless steel pipes described in any one of claims 1-3.
5. The straightening device according to claim 4, characterized in that, The groove of the upper die (1) is a three-section surface.
6. The straightening device according to claim 4, characterized in that The groove of the lower die (4) is a two-section surface.
7. The straightening device according to claim 6, characterized in that The two-section surface of the lower die (4) is one transition section and one straight section, and the straight section is close to the center of the two lower dies.