Rolling compounding equipment for core rod and seamless metal composite pipe
By designing a mandrel and protrusion combination equipment for seamless metal composite pipe rolling, the deformation problem caused by performance differences in seamless metal composite pipes during the rolling process is solved, which improves the yield of the pipe and reduces production costs.
Patent Information
- Application Number
- CN202421764675.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-24
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2034-07-24
AI Technical Summary
When the prior art produces seamless metal composite pipes with internal corrugation, due to the large differences in performance of the inner and outer seamless metal pipes, it is easy to cause wrinkles, bending, instability, tearing and other problems caused by incoordination of deformation, which reduces the yield of the pipe and increases production costs.
A mandrel is designed to support the seamless metal composite tube blank when rolling a seamless metal composite tube, and to provide protrusions on the outer wall of the mandrel. During the rolling process, the protrusions can form internal corrugations on the inner wall of the seamless metal composite tube, avoiding the use of additional equipment or processes and simplifying the process flow.
By using a combination device of the mandrel and the protrusion, the deformation problem caused by the differences in performance of the inner and outer seamless metal pipes can be effectively overcome, and the yield of the seamless metal composite pipe with inner corrugation can be improved, and the production cost is reduced.
Smart Images
Figure CN222790161U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of seamless metal composite pipe preparation equipment, in particular to a rolling composite equipment of a mandrel and a seamless metal composite pipe. Background Art
[0002] Seamless metal pipe is a hollow cross-section metal pipe without welds along the axial direction, which is widely used to transport various fluids such as oil, natural gas, coal gas, water, etc. However, with the continuous application of seamless metal pipes in extreme service environments in various fields, conventional seamless metal pipes can no longer meet the use requirements, and the demand for special-shaped seamless metal pipes, especially seamless metal pipes with internal corrugations, is increasing.
[0003] Seamless metal tubes with inner corrugations are generally made of ordinary seamless metal tubes and are processed and manufactured by cold rolling, spinning or cold extrusion. The inner wall has spiral ribs or grooves, which can effectively overcome the laminar flow phenomenon caused by slow liquid flow rate, and at the same time make the internal fluid rotate and flow, using centrifugal force to increase the turbulence of the fluid in the tube. When seamless metal tubes with inner corrugations are used as high-pressure boiler tubes, a steam film can be formed between the inner wall of the tube and the liquid to avoid film boiling and damage to the tube, improve the safety factor of equipment operation and extend the life of the tube. In addition, compared with seamless metal tubes without inner wall corrugations, seamless metal tubes with inner corrugations have a larger inner surface area per unit length, which greatly increases their heat transfer coefficient and is widely used in heat exchangers and high-heat pipes.
[0004] In recent years, the seamless metal composite tube prepared by using the outer seamless metal tube as the base tube and the inner seamless metal tube as the covering tube can have the advantages of both metal materials. With its excellent corrosion resistance, weight reduction, and oxidation resistance, it has become the best choice to replace the existing seamless metal tubes. This also provides a new development direction for the optimization of seamless metal tubes with internal corrugations. In the prior art, cold rolling, spinning or cold extrusion methods are generally used to produce seamless metal composite tubes with internal corrugations. However, due to the large performance difference between the inner and outer seamless metal tubes of the seamless metal composite tube, wrinkling, bending, instability, tearing and other problems caused by uncoordinated deformation will occur, which reduces the yield of seamless metal composite tubes with internal corrugations and increases production costs. Utility Model Content
[0005] The utility model aims to provide a rolling composite device for a mandrel and a seamless metal composite pipe, which is used to improve the yield of the seamless metal composite pipe with inner corrugations and reduce the production cost.
[0006] In order to achieve the above-mentioned objectives, in a first aspect, the utility model provides a mandrel rod, which is used to support a seamless metal composite tube blank when rolling a seamless metal composite tube. The seamless metal composite tube blank is sleeved outside the mandrel rod, and the mandrel rod includes a mandrel rod body and a protrusion arranged on the outer wall of the mandrel rod body.
[0007] When the above technical solution is adopted, when rolling the seamless metal composite pipe, the seamless metal composite pipe blank is sleeved outside the mandrel. During the rolling process, under the action of the rolling force, not only can the interface composite of the two seamless metal pipes be achieved, but also the setting of the protrusion can form inner corrugations on the inner wall of the seamless metal composite pipe during the rolling process. There is no need to use additional equipment or process to process the inner corrugations on the inner wall of the seamless metal composite pipe. Not only is the process simple, but it also overcomes the problems of wrinkling, bending, instability, tearing, etc. caused by the uncoordinated deformation due to the large performance difference between the inner and outer seamless metal pipes of the seamless metal composite pipe, and can improve the yield of the formed seamless metal composite pipe with inner corrugations and reduce production costs.
[0008] In the second aspect, the utility model provides a rolling composite equipment for seamless metal composite pipes, comprising a three-roller cross-rolling mill, a mandrel trolley and the mandrel described in the first aspect, wherein the three-roller cross-rolling mill is used to roll the seamless metal composite pipe blank into a seamless metal composite pipe. One end of the mandrel is arranged on the mandrel trolley, and the mandrel trolley is used to drive the mandrel to move back and forth along the rolling axis of the three-roller cross-rolling mill, and drive the mandrel to rotate around the axis of the mandrel. When the three-roller cross-rolling mill rolls the seamless metal composite pipe blank, the seamless metal composite pipe blank is sleeved outside the mandrel.
[0009] The beneficial effects of the rolling composite equipment of the seamless metal composite pipe described in the second aspect can refer to the beneficial effects of the mandrel described in the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:
[0011] Figure 1 A schematic diagram of the structure of a rolling composite device for a seamless metal composite pipe provided in an embodiment of the utility model;
[0012] Figure 2 A schematic diagram of the positional relationship between the oblique rolling rollers, the seamless metal composite tube blank and the mandrel provided in an embodiment of the utility model;
[0013] Figure 3 A schematic diagram of a mandrel provided in an embodiment of the utility model;
[0014] Figure 4 A schematic diagram of a support section of a mandrel provided in an embodiment of the utility model;
[0015] Figure 5 A schematic diagram of a corrugated section of a core rod provided in an embodiment of the utility model;
[0016] Figure 6 A schematic diagram of a tip section of a mandrel provided in an embodiment of the utility model;
[0017] Figure 7 A schematic diagram of a mandrel with a protruding ring as a protruding portion provided in an embodiment of the utility model;
[0018] Figure 8 A schematic diagram of a mandrel with a protruding portion as a protruding helical line provided in an embodiment of the utility model;
[0019] Fig. 9 A schematic diagram of a mandrel provided by an embodiment of the utility model, wherein the protrusion includes a plurality of first protrusion lines uniformly distributed along the circumference of the mandrel body;
[0020] Fig.10 A schematic diagram of a mandrel provided by an embodiment of the utility model, wherein the protrusion includes a plurality of second protrusion lines uniformly distributed along the circumference of the mandrel body;
[0021] Fig.11 A schematic diagram of an oblique rolling roller provided in an embodiment of the utility model;
[0022] Fig.12 A schematic diagram of the positional relationship between the mandrel and the oblique rolling roller when the protruding portion is located at the biting section during rolling provided by an embodiment of the utility model;
[0023] Fig.13 for Figure 7 The position relationship between the mandrel and the oblique roller is shown in Fig.12 In the middle, a schematic diagram of a rolled seamless metal composite tube;
[0024] Fig.14 A schematic diagram of the positional relationship between the mandrel and the oblique rolling roller when the protruding portion is located in the pressing section during rolling provided by an embodiment of the utility model;
[0025] Fig.15 for Figure 7 The position relationship between the mandrel and the oblique roller is shown in Fig.14 In the middle, a schematic diagram of a rolled seamless metal composite tube;
[0026] Fig.16 A schematic diagram of the positional relationship between the mandrel and the oblique rolling roller when the protruding portion is located in the flattening section during rolling provided by an embodiment of the utility model;
[0027] Fig.17 for Figure 7 The position relationship between the mandrel and the oblique roller is shown in Fig.16 In the middle, a schematic diagram of a rolled seamless metal composite tube;
[0028] Fig.18 for Fig.10The position relationship between the mandrel and the oblique roller is shown in Fig.12 In the middle, a schematic diagram of a rolled seamless metal composite tube;
[0029] Fig.19 for Fig.10 The position relationship between the mandrel and the oblique roller is shown in Fig.14 In the middle, a schematic diagram of a rolled seamless metal composite tube;
[0030] Fig. 20 for Fig.10 The position relationship between the mandrel and the oblique roller is shown in Fig.16 Schematic diagram of a rolled seamless metal composite tube.
[0031] Reference numerals:
[0032] 1- core rod, 11- core rod body, 111- support section, 1111- first annular water groove, 112- corrugated section,
[0033] 1121- second annular water groove, 113- tip section, 1131- third annular water groove, 12- protrusion,
[0034] 13-cooling channel, 131-entry channel, 132-outflow channel, 133-uniform distribution channel, 2-three-roller oblique rolling mill, 21-oblique rolling roller, 211-biting section, 212-pressing section, 213-flattening section, 3-mandrel trolley,
[0035] 4-Seamless metal composite pipe. DETAILED DESCRIPTION
[0036] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0037] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.
[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.
[0039] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.
[0040] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it 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 a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.
[0041] See also Figure 3 As shown, an embodiment of the utility model provides a mandrel rod, which is used to support a seamless metal composite tube blank when rolling a seamless metal composite tube. The seamless metal composite tube blank is sleeved outside the mandrel rod 1, and the mandrel 1 includes a mandrel rod body 11 and a protrusion 12 arranged on the outer wall of the mandrel rod body 11.
[0042] When the above technical solution is adopted, when rolling the seamless metal composite tube, the seamless metal composite tube blank is sleeved outside the mandrel 1, such as Figure 2As shown, under the action of rolling force, not only can the interface of the two seamless metal pipes be composited, but also the setting of the protrusion 12 can form corrugations on the inner wall of the seamless metal composite pipe during the rolling process, without the need to use additional equipment or processes to process inner corrugations on the inner wall of the seamless metal composite pipe. Not only is the process simple, but it also overcomes the problems of wrinkling, bending, instability, tearing, etc. caused by the uneven deformation due to the large performance difference between the inner and outer seamless metal pipes of the seamless metal composite pipe, which can improve the yield of the seamless metal composite pipe with inner corrugations and reduce production costs. In actual situations, the protrusion 12 can be welded to the outer wall of the mandrel body 11. Of course, the protrusion 12 can also be formed integrally with the mandrel body 11, which is not specifically limited here.
[0043] In one possible implementation, see Figure 3 The core rod body 11 includes a supporting section 111, a corrugated section 112 and a tip section 113 which are connected in sequence, and the protrusion 12 is arranged on the corrugated section 112. In this way, when the supporting section 111, the corrugated section 112 or the tip section 113 needs to be replaced, there is no need to replace the core rod body 11 as a whole, which can save equipment costs.
[0044] In a specific implementation, the protrusion 12 can be a protruding ring, such as Figure 7 As shown, a circle of rings is arranged on the outer surface of the mandrel 1 body. Of course, a plurality of protruding rings can also be arranged on the mandrel body 11, and the plurality of protruding rings are arranged along the axis direction of the mandrel body 11. The protruding portion 12 can also be a protruding spiral line, refer to Figure 8 The specific size of the spiral line is set according to the actual situation and is not specifically limited here. Fig. 9 As shown, the protrusion 12 may also include a plurality of first protrusion lines uniformly distributed along the circumference of the mandrel body 11, and an acute angle is formed between the first protrusion lines and the axis of the mandrel body 11. Fig.10 As shown, the protrusion 12 may also include a plurality of second protrusion lines uniformly distributed along the circumference of the mandrel body 11, and the second protrusion lines are parallel to the axis of the mandrel body 11. The arrangement mode and specific dimensions of the protrusion 12, such as the height, width, number, angle, etc. of the protrusion 12, can be set according to actual conditions and are not specifically limited here. By controlling the type and specific dimensions of the protrusion 12, the shape, pitch and corrugation depth of the corrugation inside the seamless metal composite tube can be controlled, and seamless metal composite tubes with internal corrugations of different specifications can be produced.
[0045] In the embodiment provided by the utility model, the core rod 1 includes a tip section 113, a corrugated section 112 and a support section 111. The corrugated section 112 is the main stress-bearing section and the section prone to wear during the rolling process. The support section 111 can be connected to the corrugated section 112 by welding, clamping, etc. Similarly, the corrugated section 112 can be connected to the tip section 113 by welding, clamping, etc. In one example, the support section 111 can be threadedly connected to the corrugated section 112, and the corrugated section 112 can be threadedly connected to the tip section 113. The threaded connection of the tip section 113, the corrugated section 112 and the support section 111 can be quickly disassembled and replaced, thereby avoiding the increase in cost caused by the overall replacement of the core rod 1. Specifically, refer to Figures 4 to 6 As shown, on the end faces of two different connected segments, a threaded hole can be provided on one segment, and a stud matching the threaded hole can be provided on the other segment. Figure 4 and Figure 5 , a threaded hole can be provided on one end face of the support section 111 close to the corrugated section 112, and a stud matched with the threaded hole on the support section 111 can be provided on one end face of the corrugated section 112 close to the support section 111. Of course, in actual situations, a stud can also be provided on one end face of the support section 111 close to the corrugated section 112, and a threaded hole matched with the stud on the support section 111 can be provided on one end face of the corrugated section 112 close to the support section 111.
[0046] As an alternative, refer to Figures 3 to 6 A cooling channel 13 is provided inside the core rod body 11 for circulating a coolant, and the coolant may be water or a refrigerant. Thus, by providing a cooling channel 13 inside the core rod body 11 for circulating a coolant to cool the core rod 1, the service life of the core rod 1 is extended.
[0047] In one example, referring to Figures 3 to 6 The cooling channel 13 includes an inlet channel 131, a uniformly distributed channel 133 and a plurality of outflow channels 132, wherein the inlet channel 131 extends from one end of the support section 111 away from the corrugated section 112 along the axial direction of the core rod body 11. The outflow channel 132 extends from one end of the support section 111 away from the corrugated section 112 along the axial direction of the core rod body 11, and the plurality of outflow channels 132 are arranged along the circumference of the core rod body 11. The uniformly distributed channel 133 is arranged at the tip section 113, referring to Figure 6 The evenly distributed channel 133 is arranged at one end of the tip section 113 away from the corrugated section 112, and the evenly distributed channel 133 is connected with the inlet channel 131 and multiple outflow channels 132 to form a closed loop to ensure the circulation of the coolant.
[0048] In this way, the coolant can flow into the mandrel body 11 through the inlet channel 131, and then disperse the coolant to the multiple outflow channels 132 through the uniformly distributed channels 133, and the coolant finally flows out from the outflow channels 132. The inlet channel 131 can be colinear with the axis of the mandrel body 11, and the number of outflow channels 132 can be multiple. For example, the number of outflow channels 132 can be 4-8, and the multiple outflow channels 132 are arranged in the same circumferential direction close to the surface of the mandrel body 11 to reduce the surface temperature of the mandrel body 11 and the protruding portion 12 during rolling, thereby extending the service life.
[0049] In some embodiments, please refer to Figure 4 A first annular water groove 1111 is provided on one end surface of the support section 111 close to the corrugated section 112, and the first annular water groove 1111 is connected to the plurality of outflow channels 132. Figure 5 The second annular water grooves 1121 are disposed on both end surfaces of the corrugated section 112, and the second annular water grooves 1121 are connected to the plurality of outflow channels 132. Figure 5 , a third annular water groove 1131 is provided on one end surface of the tip section 113 close to the corrugated section 112, and the third annular water groove 1131 is connected to the multiple outflow channels 132. At this time, when the tip section 113, the corrugated section 112 and the support section 111 are connected by threads, an annular water groove is provided at the connection along the circumferential direction of the mandrel body 11 to ensure that the two sections of the outflow channels 132 are connected and the coolant can be discharged smoothly.
[0050] As an optional manner, the outer diameter of the protrusion 12 is 1 mm-5 mm smaller than the inner diameter of the seamless metal composite tube blank, so that the core rod 1 can smoothly penetrate into the seamless metal composite tube blank.
[0051] In addition, see Figure 1 The present invention also provides a rolling composite equipment for seamless metal composite pipes, including a three-roller cross-rolling mill 2, a mandrel trolley 3 and the mandrel 1. The three-roller cross-rolling mill 2 is used to roll the seamless metal composite pipe blank into a seamless metal composite pipe. The cross-rolling roll 21 of the three-roller cross-rolling mill 2 includes a bite section 211, a press section 212 and a flattening section 213 connected in sequence. Fig.11 , Fig.12 , Fig.14 and Fig.16 One end of the mandrel 1 is arranged on the mandrel trolley 3, and the mandrel trolley 3 is used to drive the mandrel 1 to move back and forth along the rolling axis of the three-roller cross-rolling mill 2, and drive the mandrel 1 to rotate around the axis of the mandrel 1. When the three-roller cross-rolling mill 2 rolls the seamless metal composite tube blank, the seamless metal composite tube blank is sleeved outside the mandrel 1.
[0052] In the specific implementation, the seamless metal composite tube billet heated to a certain temperature is sleeved outside the mandrel 1, and the mandrel trolley 3 drives the mandrel 1 to move forward to a predetermined position. During the rolling process, the mandrel 1 remains stationary along the axial position and can make free circumferential rotation when subjected to force. Subsequently, the seamless metal composite tube billet is pushed into the main machine of the three-roller oblique rolling mill 2 and contacts with the oblique roller 21. The seamless metal composite tube billet spirally advances under the action of the feed angle and friction force of the oblique roller 21 and passes through the bite section 211, the press section 212, and the flattening section 213 of the oblique roller 21 in turn, thereby realizing the smooth separation of the seamless metal composite tube billet and the mandrel 1, and rolling out corrugations on the inner surface of the seamless metal composite tube billet to obtain a seamless metal composite tube with inner corrugations.
[0053] It can be seen from this that the rolling composite equipment for the seamless metal composite pipe provided in the embodiment of the utility model can realize the simultaneous interface bonding and internal corrugation processing of the seamless metal composite pipe. The prepared seamless metal composite pipe has a spiral space composite interface, high bonding strength, excellent comprehensive performance and economic benefits, and can replace the existing internal corrugated metal pipe without the need for subsequent separate demolding. The method has a simple process flow and high production efficiency, and can realize industrial mass production.
[0054] In a possible implementation, when the seamless metal composite tube is sleeved outside the mandrel, the protruding portion 12 of the mandrel 1 is located at the biting section 211, the pressing section 212 or the flattening section 213. The mandrel trolley 3 drives the mandrel 1 to move along the rolling axis of the three-roller inclined rolling mill 2. During rolling, the protruding portion 12 of the mandrel 1 can be located at the biting section 211 relative to the inclined rolling roller 21, such as Fig.12 As shown, in this case, when the protrusion 12 is Figure 7 When the protruding ring is shown, the seamless metal composite pipe 4 formed by rolling is referred to Fig.13 As shown; when the protrusion is Fig.10 When the plurality of second protruding lines uniformly distributed along the circumferential direction of the mandrel body are shown, the seamless metal composite tube 4 formed by rolling is referred to Fig.18 During rolling, the protruding portion 12 of the mandrel 1 may be located at the pressing section 212 relative to the oblique rolling roller 21, as shown in FIG. Fig.14 As shown, in this case, when the protrusion 12 is Figure 7 When the protruding ring is shown, the seamless metal composite pipe 4 formed by rolling is referred to Fig.15 As shown; when the protrusion is Fig.10 When the plurality of second protruding lines uniformly distributed along the circumferential direction of the mandrel body are shown, the seamless metal composite tube 4 formed by rolling is referred to Fig.19 During rolling, the protruding portion 12 of the mandrel 1 can also be located at the flattening section 213 relative to the oblique rolling roller 21, as shown in FIG. Fig.16 As shown, in this case, when the protrusion 12 is Figure 7When the protruding ring is shown, the seamless metal composite pipe 4 formed by rolling is referred to Fig.17 As shown; when the protrusion is Fig.10 When the plurality of second protruding lines uniformly distributed along the circumferential direction of the mandrel body are shown, the seamless metal composite tube 4 formed by rolling is referred to Fig. 20 In specific implementation, the position of the protrusion 12 relative to the oblique roller 21 and the type and size of the protrusion 12 can be controlled to produce seamless metal composite tubes with different interfaces and internal corrugation morphologies, such as seamless metal composite tubes with or without corrugations on the inner wall, corrugation spacing, corrugation width and depth.
[0055] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.
[0056] The above are only specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A mandrel, characterized in that: It is used to support a seamless metal composite tube blank when rolling a seamless metal composite tube, and the seamless metal composite tube blank is sleeved outside the mandrel; the mandrel includes a mandrel body and a protrusion arranged on the outer wall of the mandrel body.
2. The mandrel according to claim 1, characterized in that The core rod body comprises a supporting section, a corrugated section and a tip section which are connected in sequence, and the protrusion is arranged on the corrugated section.
3. The mandrel according to claim 2, characterized in that The support section is threadedly connected to the corrugated section; and / or the corrugated section is threadedly connected to the tip section.
4. The mandrel according to claim 2, characterized in that A cooling channel is arranged in the core rod body for circulating cooling liquid.
5. The mandrel according to claim 4, characterized in that The cooling channel comprises: An entry channel extending from an end of the support section away from the corrugated section along the axial direction of the mandrel body; A plurality of outflow channels, wherein the outflow channels extend from one end of the support section away from the corrugated section along the axial direction of the mandrel body; the plurality of outflow channels are arranged along the circumference of the mandrel body; The evenly distributed channel is arranged at the tip section, and the evenly distributed channel is connected with the inlet channel and the plurality of outflow channels.
6. The mandrel according to claim 5, characterized in that A first annular water groove is provided on one end face of the support section close to the corrugated section, and the first annular water groove is connected to the multiple outflow channels; and / or, second annular water grooves are provided on both end faces of the corrugated section, and the second annular water grooves are connected to the multiple outflow channels; and / or, a third annular water groove is provided on one end face of the tip section close to the corrugated section, and the third annular water groove is connected to the multiple outflow channels.
7. The mandrel according to claim 1, characterized in that The protrusion is a protruding circular ring; or, the protrusion is a protruding spiral line; or, the protrusion includes a plurality of first protruding lines uniformly distributed along the circumference of the mandrel body, and an acute angle is formed between the first protruding lines and the axis of the mandrel body; or, the protrusion includes a plurality of second protruding lines uniformly distributed along the circumference of the mandrel body, and the second protruding lines are parallel to the axis of the mandrel body.
8. The mandrel according to claim 1, characterized in that The outer diameter of the protrusion is 1 mm to 5 mm smaller than the inner diameter of the seamless metal composite tube.
9. A rolling composite equipment for seamless metal composite pipes, characterized in that: include: A three-roller cross-rolling mill is used to roll a seamless metal composite tube billet into a seamless metal composite tube; The mandrel according to any one of claims 1 to 8; A mandrel trolley, one end of the mandrel is arranged on the mandrel trolley; the mandrel trolley is used to drive the mandrel to move back and forth along the rolling axis of the three-roller inclined rolling mill, and drive the mandrel to rotate around the axis of the mandrel; when the three-roller inclined rolling mill rolls the seamless metal composite tube blank, the seamless metal composite tube blank is sleeved outside the mandrel.
10. The rolling composite equipment for seamless metal composite pipe according to claim 9, characterized in that: The inclined rolling rolls of the three-roll inclined rolling mill include a biting section, a pressing section and a flattening section connected in sequence. When the seamless metal composite tube is sleeved outside the mandrel, the protruding portion of the mandrel corresponds to the biting section, the pressing section or the flattening section.