Double-layer steel pipe with connecting plate and manufacturing method of double-layer steel pipe

Abstract

The invention relates to a double-layer steel pipe with a connecting plate and a manufacturing method of the double-layer steel pipe, and the steel pipe comprises an inner pipe and an outer pipe, the outer pipe is arranged outside the inner pipe in a sleeving manner and is formed by spirally rolling a second steel belt; the spiral web plate is arranged in the containing cavity, the inner circumference of the spiral web plate is connected with the outer surface of the inner pipe, the outer circumference of the spiral web plate is connected with the inner surface of the outer pipe, and the containing cavity is divided into a spiral cavity body by the spiral web plate; and the connecting plate is formed by spirally rolling a straight third steel belt, and the connecting plate is arranged to cover the spiral seam of the rolled inner pipe. The forming quality of the inner pipe blank can be guaranteed, edge rolling deformation at the spiral butt joint of the first steel belt is avoided, the connecting plate made of the third steel belt can serve as the benchmark of inner pipe edge rolling butt joint, it is guaranteed that the first edge and the second edge on the two sides of the spiral butt joint of the inner pipe blank are in butt joint flush, and the butt joint quality is improved. Smooth spiral edge rolling forming of the inner pipe blank can be guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel pipes and steel pipe manufacturing technology, in particular to a double-layer steel pipe with connecting plates and a manufacturing method thereof. BACKGROUND

[0002] The steel pipe structure with a pipe wall sandwich cavity filled with concrete is a special pipe structure, that is, concrete is poured into a steel pipe and tamped to increase the strength and stiffness of the steel pipe. It has unique mechanical properties and application advantages. The compressive strength of concrete is high, but the bending resistance is very weak. Steel, especially shaped steel, has strong bending resistance and good elastic-plasticity, but it is easy to lose stability and axial compressive capacity under compression. Steel pipe concrete can combine the advantages of both in structure, which can greatly improve the mechanical properties. Steel and concrete composite structure has been applied in practical engineering projects and has shown good performance.

[0003] The applicant previously invented a combined structure steel pipe made of two layers of spiral welded steel pipes. A vertical steel plate is welded between the inner and outer layers of the pipe wall to connect the inner and outer layers of the pipe wall. During product manufacturing, a plurality of vertical narrow steel strips are welded on the second steel strip, and then enter a special spiral coiling mechanism to coil. After one circle is coiled, the vertical steel strip becomes a spiral reinforcing ring. The first steel strip is attached to the outside of the coiled vertical steel strip and welded during the implementation process. Due to the coiling of the vertical steel strip, the outer edge is stretched, the inner edge is compressed and shrunk, which easily leads to the inner convex deformation of the second steel strip after the coiled pipe wall. SUMMARY

[0004] Therefore, it is necessary to provide a double-layer steel pipe with connecting plates and a manufacturing method thereof, which has stable welding and excellent structural strength, aiming at the above technical problems.

[0005] A double-layer steel pipe with connecting plates, the steel pipe comprising:

[0006] an inner pipe made of a first steel strip coiled in a spiral shape, the inner pipe being in a cylindrical shape as a whole;

[0007] an outer pipe sleeved outside the inner pipe and made of a second steel strip coiled in a spiral shape, the outer pipe being in a cylindrical shape as a whole, the outer pipe being connectable with the inner pipe, and a containing cavity being formed between the inner pipe and the outer pipe;

[0008] a spiral web provided in the containing cavity, an inner periphery of the spiral web being connected to an outer surface of the inner pipe, an outer periphery of the spiral web being connected to an inner surface of the outer pipe, and the spiral web dividing the containing cavity into a spiral cavity; and

[0009] The first connecting plate is made of a third steel strip in a flat shape, and is arranged on the spiral joint of the inner pipe after the spiral winding.

[0010] In one embodiment, the steel pipe further comprises a second connecting plate made of a fourth steel strip in a flat shape, and arranged on the spiral joint of the outer pipe after the spiral winding and inside the spiral cavity.

[0011] In one embodiment, the first steel strip comprises a first edge and a second edge, and the third and fourth steel strips are arranged on the first edge and at least a part of the third and fourth steel strips extends out of the first edge for connecting the second edge.

[0012] In one embodiment, the third and fourth steel strips extend out of the first edge by a distance not less than the thickness of the spiral web.

[0013] In one embodiment, the connecting plate is arranged apart from the spiral web.

[0014] In one embodiment, the spiral web is arranged on the spiral joint of the outer pipe at one end of the outer pipe.

[0015] In one embodiment, the steel pipe further comprises a concrete layer casted in the spiral cavity between the outer pipe and the inner pipe.

[0016] A manufacturing method of a double-layer steel pipe with a connecting plate, the manufacturing method comprising the steps of:

[0017] welding a vertical steel strip on the first steel strip and welding a third steel strip on a first edge of the first steel strip so that the third steel strip overlaps the first edge of the first steel strip on one side and extends out of the first edge on the other side to form a composite steel strip with a spiral web and a connecting plate;

[0018] turning over the composite steel strip so that the web faces downward and performing spiral winding;

[0019] after the spiral winding, abutting the adjacent edges of the composite steel strip to each other to form a spiral joint of an inner pipe so that a second edge of the first steel strip is pressed against the extended end of the connecting plate, welding the spiral joint of the first steel strip and the connecting plate to form a pipe blank, then welding a fourth steel strip on a second steel strip according to the method of the first steel strip, winding the second steel strip on the pipe blank, inserting a welding torch into a gap between the pipe blank and an outer pipe, and welding the spiral web and the second steel strip to form a steel pipe.

[0020] In one embodiment, the step of forming the pipe blank comprises:

[0021] After the composite steel strip is rolled, the first edge is aligned with the second edge, and the second edge is pressed against the third steel strip that protrudes from the first edge at the intersection of the first edge and the second edge;

[0022] The intersection of the first edge, the second edge and the connecting plate is welded to form a pipe blank with the connecting plate and the first spiral weld.

[0023] In one embodiment, the steps of rolling the composite steel strip and rolling the second steel strip are performed synchronously.

[0024] In one embodiment, the step of rolling the composite steel strip further comprises a step of pre-deforming the area where the first steel strip is connected to the web plate, and the pre-deformation is in a direction in which the web plate is away from the first steel strip.

[0025] In one embodiment, the step of attaching the outer pipe to the pipe blank further comprises arranging the spiral joint of the outer pipe at one end of the web plate, arranging the spiral joint of the inner pipe between adjacent web plates, and staggering the spiral joint of the outer pipe and the spiral joint of the inner pipe.

[0026] The present application realizes the following technical advantages in the welding of double-layer pipe walls by introducing the combination of the connecting plate and the spiral web plate:

[0027] 1) By arranging the third steel strip and the fourth steel strip, the forming quality of the inner pipe blank and the outer pipe can be ensured, and the deformation of the inner pipe during rolling can be avoided. The connecting plate made of the third steel strip can serve as a reference for the butt joint of the inner pipe, ensuring the butt joint of the first edge and the second edge on both sides of the spiral butt joint of the inner pipe blank, and ensuring the smooth spiral rolling of the inner pipe blank.

[0028] 2) The connecting plate increases the mechanical properties of the butt joint in various directions, and improves the local strength of the first and second steel strips. As such, the pipe wall can be designed to be thinner than conventional pipe walls. Due to the presence of the connecting plate, the thin inner pipe wall is less likely to deform and be burned through. As such, the structure of the inner pipe can be designed more flexibly, and the overall weight of the double-layer steel pipe is smaller.

[0029] 3) The connecting plate has the function of a welding backing, which can improve the quality of the joint welding. The connecting plate forms a thermal conduction gradient buffer layer, which preferentially absorbs arc energy during welding, delays the transfer of heat to the inner layer, and fills the interface gap through metal melting flow, ensuring that the welding penetration penetrates the spiral ring plate, and avoiding the burning of the thin wall of the first steel strip due to instantaneous high temperature overload. The thickness of the connecting plate matches the welding power with the heat capacity characteristics, forming a dynamic thermal equilibrium mechanism.

[0030] 4) The manufacturing process is automated and highly efficient. The flat and straight characteristics of the connecting plate allow it to be integrated into the existing pipe production line, and to be synchronously spirally wound with the inner and outer pipes by a special guiding device. The high matching of its geometric characteristics and the welding path allows the use of a fixed welding gun to complete continuous welding by cooperating with the rotation of the pipe body, which fundamentally eliminates the complexity of welding gun trajectory tracking in the traditional process. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 Structure diagram of the composite steel strip with the spiral web located at the edge.

[0032] Figure 2 Structure diagram of the composite steel strip with the spiral web located at the edge. Figure 1 Process diagram of the welding of the composite steel strip.

[0033] Figure 3 Structure diagram of the composite steel strip with the spiral web located at the edge.

[0034] Figure 4 Structure diagram of the composite steel strip with the spiral web located at the edge.

[0035] Figure 5 Process diagram of the welding of the composite steel strip.

[0036] Figure 6 Structure diagram of the steel pipe.

[0037] Figure 7 Structure diagram of the second steel strip with the fourth steel strip during the manufacturing of the pipe blank. DETAILED DESCRIPTION

[0038] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many different ways other than those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0039] In the description of the application, it should be understood that, if there are these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0040] In addition, if there are these terms "first", "second", these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, if the term "multiple" appears, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0041] In this application, unless otherwise explicitly specified and limited, if there are terms such as "mounting", "connecting", "connecting", "fixing" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0042] In this application, unless otherwise explicitly specified and limited, if there are similar descriptions such as "first feature on or under second feature", the meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" of the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" of the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0043] It is to be noted that when an element such as a layer, region or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements can also be present. In addition, it is to be noted that when a layer is referred to as being "formed on" the surface of a substrate, the layer can be formed directly on the substrate surface or intervening layers can also be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the term "about" when used in reference to a particular recited numerical value, means that the value can vary from the recited value by no more than 1%, 2%, 5%, or 10%. As used herein, the terms "horizontal" and "vertical" are intended to refer to the orientation of the device as it is typically oriented for use, and are not intended to refer to an absolute orientation of the device.

[0044] The applicant invented a combined structure steel pipe made of two layers of spiral welded steel pipes, and a vertical steel plate is arranged in the interlayer between the two layers of pipe walls to weld and connect the inner and outer layers of pipe walls. The applicant found through research that during production, a plurality of vertical narrow steel strips are welded on the second steel strip, then the vertical narrow steel strips are turned over by 180 degrees so as to face downward and enter a special spiral roll forming mechanism to be rolled, and after one circle of rolling is completed, the vertical steel strips become spiral reinforcing rings. Then, the first steel strip 201 is attached to the outside of the circle of the rolled vertical steel strips, and the two are welded in the implementation process. Since the vertical steel strips are rolled, the outer edge is stretched, the inner edge is compressed and shrunk, which easily causes the second steel strip welded with the inner edge to be rolled into a circular pipe, and the pipe wall is deformed inwardly and protrudes outwardly with rib marks. Especially when the vertical steel strips are higher and thicker, or the second steel strip is thinner, the situation is more serious.

[0045] Referring to Figures 4-6 , Figures 4-6 A structure diagram of a double-layer steel pipe with a first connecting plate 400 in an embodiment of the present application is shown, and the double-layer steel pipe with the first connecting plate 400 includes an inner pipe 200, an outer pipe 100, a spiral web 300, and a first connecting plate 400. The inner pipe 200 is made of a flat first steel strip 201 and is spirally rolled, and the inner pipe 200 is in a cylindrical shape as a whole. The outer pipe 100 is sleeved on the outer pipe 200 and is made of a second steel strip and is spirally rolled, and the outer pipe 100 is in a cylindrical shape as a whole. The outer pipe 100 can be connected with the inner pipe 200, and a containing cavity is formed between the inner pipe 200 and the outer pipe 100. The spiral web 300 is arranged in the containing cavity, the inner periphery of the spiral web 300 is connected with the outer surface of the inner pipe 200, the outer periphery of the spiral web 300 is connected with the inner surface of the outer pipe 100, and the spiral web 300 divides the containing cavity into a spiral cavity. The first connecting plate 400 is made of a flat third steel strip and is spirally rolled, and the first connecting plate 400 is arranged on the spiral joint of the inner pipe 200 after rolling.

[0046] The present application realizes the following significant technical advantages in the welding of double-layer pipe walls by introducing the combined structure of the gasket and the spiral web 300:

[0047] 1) By setting the third steel belt, the forming quality of the inner tube 200 can be ensured, and the edge deformation at the spiral butt joint of the first steel belt 201 can be avoided. The first connecting plate 400 made of the third steel belt can serve as the reference for the butt joint of the inner tube 200, ensuring the butt joint of the first edge 210 and the second edge on both sides of the spiral butt joint of the inner tube 200, and ensuring the smooth spiral forming of the inner tube 200.

[0048] 2) The first connecting plate 400 increases the mechanical properties of the butt joint in various directions, and improves the local strength of the first steel belt 201. Thus, the pipe wall of the inner tube 200 can be designed to be thinner than the conventional pipe wall. Due to the presence of the first connecting plate 400, the thinner inner tube 200 pipe wall is not easy to deform and be burned through, so the structure of the inner tube 200 can be designed more flexibly, and the overall weight of the double-layer steel pipe 10 is smaller.

[0049] 3) The first connecting plate 400 has the effect of welding gasket, which can improve the welding quality. The first connecting plate 400 forms a thermal conduction gradient buffer layer, which preferentially absorbs arc energy during welding, delays heat transfer to the inner layer, and at the same time fills the interface gap through metal melting flow, which not only ensures the penetration of the welding depth of the spiral ring plate, but also avoids the burning of the thin wall of the first steel belt 201 due to instantaneous high temperature overload. The thickness of the first connecting plate 400 matches the welding power of the heat capacity characteristics, forming a dynamic thermal equilibrium mechanism.

[0050] 4) The manufacturing method is automated and has high production efficiency. The equal width and straightness of the first connecting plate 400 allows it to be integrated into the existing pipe winding production line, and through a special guide device, it can be spirally wound synchronously with the inner and outer pipes 100. The high matching of its geometric characteristics and welding path allows the use of a fixed welding gun to complete continuous welding by rotating the pipe body, which fundamentally eliminates the complexity of welding gun trajectory tracking in traditional processes.

[0051] In one embodiment, the first steel belt 201 includes a first edge 210 and a second edge 220, the third steel belt is arranged on the first edge 210, and at least part of the third steel belt extends out of the first edge 210 for connecting the second edge 220.

[0052] Specifically, the first edge 210 and the second edge 220 are two parallel outer edges of the first steel belt 201, the extension direction of the first edge 210 and the second edge 220 is the longitudinal direction of the first steel belt 201, and when the first steel belt 201 is coiled, the first edge 210 and the second edge 220 form a spiral structure, and all the first edges 210 and all the second edges 220 form spiral joints with each other.

[0053] The third steel strip is connected to the first edge 210 by 40%-60% of its total width, and the remaining 40%-60% of the total width of the third steel strip extends beyond the first steel strip 201. The third steel strip is coiled with the first steel strip 201 to form a spiral structure to connect to the second edge 220 of the spiral. The coiling direction is away from one side of the third steel strip 201, i.e. after coiling, the first connecting plate 400 is located on the outer wall of the cylindrical inner tube 200.

[0054] In one embodiment, the third steel strip extends beyond the first edge 210 by a distance not less than the thickness of the spiral web 300. The width of the third steel strip can be 2-5 times the thickness of the spiral web 300, for example, the width of the third steel strip can be 20-200 mm. The third steel strip extends beyond the first edge 210 by a distance of 1-2.5 times the thickness of the spiral web 300, for example, the third steel strip extends beyond the first edge 210 by a distance of 10-100 mm, so as to ensure that the first connecting plate 400 can provide sufficient connection strength support.

[0055] In one embodiment, the first connecting plate 400 is arranged spaced apart from the spiral web 300.

[0056] Specifically, it is found through research that in a structure in which the spiral web 300 is generally arranged, as shown in Figure 1 , the spiral web 300 is located at the edge of the first steel strip 201, and the spiral web 300 is wider than half the thickness. After the first steel strip 201 is coiled once to form a steel pipe 10, the lower direction of the steel pipe 10 is shown in the longitudinal section as Figure 2 . The web located at the side of the first steel strip 201 is deformed inconsistently with the bending deformation of the web at other positions when it is coiled into the spiral web 300, and at the same time, it causes the deformation of the first steel strip 201 welded thereto at the connection to be inconsistent with other positions. Specifically, the web located at the side is prone to inward bulging when coiling, which affects the bonding quality at this position with the previous circle of the first steel strip 201. Further, it affects the welding quality at the bonding position, and after the pipe is formed, there are obvious spiral bulges in the pipe.

[0057] If only the spiral web 300 is shifted, the two sides of the first steel strip 201 are free edges, as shown in Figure 3As shown, the free edge after the rounding is often deformed, and after one round, it is not easy to align up and down at the spiral joint with the previous round, which is particularly evident when the first steel strip 201 is relatively thin. Moreover, when the weld here is a single-welded double-formed weld, the welding and forming quality is affected. By setting the first connecting plate 400 and shifting the spiral web 300 to the middle of the first steel strip 201, the problem of the inner bulge during rounding can be solved, and the problem of not easy to weld can also be solved, so that the first steel strip 201 after rounding has no obvious bulge, the flatness of the inner tube 200 is ensured, the first edge 210 and the second edge 220 are more easily aligned, and welding is more easily performed, ensuring the welding quality and the strength of the steel pipe 10.

[0058] Further, the distance between the spiral web 300 and the first edge 210 or the second edge 220 is 10%-80% of the width of the first steel strip 201, or the distance between the spiral web 300 and the first connecting plate 400 is 10%-80% of the width of the first steel strip 201. Preferably, the distance between the spiral web 300 and the first edge 210 or the second edge 220 is 20%, 30%, or 40% of the width of the first steel strip 201, or the distance between the spiral web 300 and the first connecting plate 400 is 20%, 30%, or 40% of the width of the first steel strip 201. At least two spiral webs 300 can be provided on each first steel strip 201.

[0059] In one embodiment, the spiral web 300 is arranged on the spiral joint of the outer tube 100 towards one end of the outer tube 100. That is, the spiral web 300 at least partially locates on the edge of the second steel strip and at least partially extends out of the edge of the second steel strip towards one end of the outer tube 100. Specifically, both ends of at least one spiral web 300 are located at the middle of the first steel strip 201 and the end of the second steel strip, respectively.

[0060] In one embodiment, the steel pipe 10 further comprises a concrete layer poured into the spiral cavity formed between the outer tube 100 and the inner tube 200. The concrete layer and the first connecting plate 400 form a spatial grid interlocking: the solidified concrete in the spiral cavity forms a radial anchoring column penetrating through the steel pipe 10, the outer tube 100 and the inner tube 200 establish an axial force transmission channel through the first connecting plate 400, and the pre-compressive stress generated by the concrete solidification and shrinkage forms a self-balancing system with the elasticity of the steel pipe 10. This structure enables the concrete to mainly bear the circumferential tensile stress when the pipeline is subjected to internal pressure, the steel pipe 10 to resist local buckling, and the first connecting plate 400 to coordinate the deformation of the two, thereby maximizing the utilization rate of material strength.

[0061] In one embodiment, the steel pipe further comprises a second connecting plate 500 formed by spirally rounding a flat fourth steel strip, the second connecting plate 500 covering the spiral weld of the outer tube after rounding and being located inside the spiral cavity.

[0062] In one embodiment, the third and fourth steel strips, namely the first connecting plate 400 and the second connecting plate 500, extend beyond the first edge 210 by a distance not less than the thickness of the spiral web.

[0063] A method for manufacturing a double-layer steel pipe 10 having a first connecting plate 400, the method comprising the steps of:

[0064] S100, weld a vertical steel strip onto the first steel strip 201, and weld a third steel strip onto the first edge 210 of the first steel strip 201, such that one side of the third steel strip overlaps the first edge 210 of the first steel strip 201 and the other side extends out of the first edge 210, thus forming a composite steel strip with a spiral web 300 and a first connecting plate 400.

[0065] S200. Turn the composite steel strip over so that the web faces down, and roll it into a circle;

[0066] S300. After rolling, the adjacent edges of the composite steel strip are joined together to form a spiral joint of the inner tube 200, so that the second edge 220 of the first steel strip 201 is pressed against the protruding end of the first connecting plate 400. The spiral joint of the first steel strip 201 and the first connecting plate 400 are welded to form a tube blank.

[0067] S400. The second steel strip is rolled into a circle and attached to the tube blank. The welding torch is inserted into the interlayer between the tube blank and the outer tube 100 to weld the spiral web 300 and the second steel strip to form the steel pipe 10.

[0068] In one embodiment, the step of forming the tube blank in step S300 includes:

[0069] S310. After the composite steel strip is rolled into a circle, the first edge 210 is aligned with the second edge 220, and the second edge 220 is pressed onto the third steel strip that extends out of the first edge 210. The third steel strip is located at the junction of the first edge 210 and the second edge 220.

[0070] S320, the junction of the first edge 210, the second edge 220, and the first connecting plate 400 is welded to form a tube blank having the first connecting plate 400 and the first spiral weld. Specifically, preferably, the first edge 210 and the first connecting plate 400 can be welded together before rolling, or they can be welded separately after rolling.

[0071] In one embodiment, the step of coiling the composite steel strip in step S200 is synchronized with the step of coiling the second steel strip in step S400. Specifically, the composite steel strip is coiled and the web is directed outward. The coiled composite steel strip is attached to the inner wall of the second steel strip from the inside of the outer pipe 100 being coiled, i.e., the first steel strip 201 is attached to the surface on the side in the direction of the bending of the composite steel strip, and then the two are input into a coiling mechanism of a specific structure for synchronized coiling.

[0072] In one embodiment, the step of coiling the composite steel strip in step S200 further includes a step of pre-deforming the region where the first steel strip 201 is connected to the web, the pre-deformation being in a direction in which the web is directed away from the first steel strip 201. Specifically, the pre-deformation is to set a certain width of the region of the first steel strip 201 to protrude upward (toward the top in the drawing). Figure 4 When the inner pipe 200 is coiled, the region of the inner pipe 200 deforms inward due to the shrinkage of the inner circle of the web after coiling, which offsets the pre-deformation and makes the inner pipe 200 smooth and flat.

[0073] In one embodiment, the third steel strip protrudes from the edge by a distance not less than the thickness of the web. In one embodiment, the width of the lap of the third steel strip on the edge is not less than the thickness of the web. That is, the width of the third steel strip arranged on the first edge 210 and / or the second edge 220 is not less than the thickness of the web, to ensure the support of the first connecting plate 400 to the inner pipe 200.

[0074] In one embodiment, the step of attaching the outer pipe 100 to the pipe blank further includes arranging the spiral joint of the coiled outer pipe 100 at one end of the web, the spiral joint of the inner pipe 200 between adjacent webs, and the spiral joint of the outer pipe 100 and the spiral joint of the inner pipe 200 being staggered.

[0075] Specifically, after S300, the inner pipe 200 pipe blank is formed, and then the un-welded outer pipe 100 is attached to the inner pipe 200 pipe blank below the inner pipe 200 pipe blank. The two sides of the outer pipe 100, i.e., the first edge 210 and the second edge 220, are to be lapped on the top end of the web. The welding torch is inserted into the interlayer between the inner pipe 200 pipe blank and the outer pipe 100, and the joint between the web and the outer pipe 100 is welded, and then the spiral joint between the outer pipe 100 after coiling is welded, which is on the end surface of the top of the web.

[0076] Any combination of the technical features described above can be made, and for the sake of brevity, not all possible combinations of the technical features described above are described, but it is understood that any combination of the technical features is within the scope of the present disclosure as long as the combination does not result in a contradiction.

[0077] The above-described embodiments are merely illustrative of several embodiments of the present application, and the description is relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these are all within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. A double-layered steel pipe having a connecting plate, characterized by, The steel pipe comprises: an inner pipe made of a first steel strip spirally rolled into a flat shape, the inner pipe being in a cylindrical shape as a whole; an outer pipe sleeved outside the inner pipe and made of a second steel strip spirally rolled into a flat shape, the outer pipe being in a cylindrical shape as a whole, the outer pipe being connectable with the inner pipe, and a containing cavity being formed between the inner pipe and the outer pipe; a spiral web provided in the containing cavity, an inner periphery of the spiral web being connected with an outer surface of the inner pipe, an outer periphery of the spiral web being connected with an inner surface of the outer pipe, and the spiral web dividing the containing cavity into spiral cavities; and a first connecting plate made of a third steel strip spirally rolled into a flat shape, the connecting plate being arranged on a spiral joint of the inner pipe after rolling and being arranged inside the spiral cavities.

2. The double-layered steel pipe with a connecting plate according to claim 1, characterized by The steel pipe comprises a second connecting plate made of a fourth steel strip spirally rolled into a flat shape, the second connecting plate being arranged on a spiral joint of the outer pipe after rolling and being arranged inside the spiral cavities.

3. The double-layered steel pipe with a connecting plate according to claim 1, characterized by The first steel strip comprises a first edge and a second edge, the third steel strip being arranged at the first edge and at least a part of the third steel strip extending out of the first edge for connecting the second edge.

4. The double-layered steel pipe with a connecting plate according to claim 2, characterized by The fourth steel strip is arranged at a left edge of the second steel strip and extends out of the left edge for connecting a right edge of a next round of the second steel strip.

5. The double-layered steel pipe with a connecting plate according to claim 4, characterized by The third steel strip and the fourth steel strip extend out of the edge by a distance not less than a thickness of the spiral web.

6. The double-layered steel pipe with a connecting plate according to claim 1, characterized by The connecting plate is arranged in a spaced manner with the spiral web.

7. The double-layered steel pipe with a connecting plate according to claim 1, characterized by An end of the spiral web towards the outer pipe is arranged on a spiral joint of the outer pipe.

8. The double-layered steel pipe with a connecting plate according to claim 1, characterized by The steel pipe further comprises a concrete layer casted in the spiral cavities formed between the outer pipe and the inner pipe.

9. A method of manufacturing a double-layered steel pipe having a connecting plate, characterized by, The manufacturing method comprises the steps of: welding a vertical steel strip on the first steel strip and welding the third steel strip on a first edge of the first steel strip, so that one side of the third steel strip is overlapped on the first edge of the first steel strip and the other side of the third steel strip extends out of the first edge, to form a composite steel strip with the spiral web and the connecting plate; turning over the composite steel strip so that the spiral web faces downwards and rolling the composite steel strip; after rolling, abutting edges of the composite steel strip are abutted on each other to form a spiral joint of the inner pipe, so that a second edge of the first steel strip is pressed on an extending end of the connecting plate, and the spiral joint of the first steel strip and the connecting plate are welded, to form a pipe blank; rolling the second steel strip and attaching the second steel strip on the pipe blank, a welding gun being inserted into a layer between the pipe blank and the outer pipe to weld the spiral web and the second steel strip, to form the steel pipe.

10. The method of manufacturing a double-layered steel pipe with a connecting plate according to claim 9, characterized by, The step of forming the pipe blank comprises: after rolling the composite steel strip, a first edge is aligned with a second edge, and the second edge is pressed on the third steel strip extending out of the first edge, the third steel strip being located at an intersection of the first edge and the second edge; welding the intersection of the first edge, the second edge and the connecting plate to form the pipe blank with the connecting plate and a first spiral weld joint.

11. The method of manufacturing a double-layered steel pipe with a connecting plate according to claim 10, characterized by, after welding the fourth steel strip on a left edge of the second steel strip, the fourth steel strip is attached on the pipe blank from below the pipe blank, a weld joint between the second steel strip and the pipe blank is welded, and the left edge of the second steel strip after rolling is welded.

12. The method of manufacturing a double-layered steel pipe with a connecting plate according to claim 9, characterized by, The step of rolling the composite steel strip further comprises a step of pre-deforming the area where the first steel strip is connected to the web, the pre-deformation being in a direction in which the web is caused to move away from the first steel strip.

13. The method of manufacturing a double-layered steel pipe with a connecting plate according to claim 9, characterized by, The step of attaching the second steel strip to the pipe blank further comprises arranging the spiral seam of the outer pipe to be located at one end of the web and the spiral seam of the inner pipe to be located between adjacent webs, the spiral seam of the outer pipe being staggered with respect to the spiral seam of the inner pipe.

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