Core rod with temperature measurement function for steel pipe thermal expanding

Abstract

The utility model is suitable for the technical field of steel pipe plastic deformation devices, and provides a steel pipe thermal expanding core rod with a temperature measurement function, which comprises a deformation rod, the guide rod is arranged at one end of the deformation rod, the sizing rod is arranged at the other end of the deformation rod, the variable diameter sizes of the guide rod, the deformation rod and the sizing rod are arranged according to a sequence from small to large, and the outer diameter of the deformation rod is gradually increased in the thermal diameter expansion direction to form a gradually-transitioned variable diameter structure. Stable guiding and supporting are provided for the steel pipe, stress concentration and steel pipe damage are effectively avoided through a gradual transition reducing structure of the deformation rod, and therefore the diameter precision and the surface quality of the steel pipe are guaranteed. And secondly, due to the installation design of a reinforcing structure in the core rod and a detection piece on the outer surface, the strength and the stability of the core rod are remarkably enhanced, the core rod can reliably work in a high-temperature and high-pressure environment, and the temperature and the pressure in the working process of the core rod are monitored in real time.

Description

Technical Field

[0001] This utility model belongs to the technical field of steel pipe plastic deformation device, and in particular relates to a mandrel for hot expansion of steel pipe with temperature measurement function. Background Technology

[0002] Hot expansion is a crucial step in steel pipe production, and its stability and accuracy directly affect the final quality of the steel pipe. During hot expansion, the steel pipe needs to undergo a high-temperature and high-pressure environment to achieve precise diameter expansion and shape optimization. However, this process is often accompanied by complex thermal and mechanical stresses, which can easily lead to deformation, damage, or even structural failure of the steel pipe. Therefore, how to improve the stability and accuracy of the hot expansion process has become an urgent problem to be solved in the steel pipe production field.

[0003] Traditional mandrel designs often focus on structural integrity and strength to ensure smooth guidance and support for the steel pipe during hot expansion. However, with the increasing demands on steel pipe production, traditional mandrel designs are no longer sufficient to meet the requirements of modern hot expansion processes.

[0004] Temperature is a crucial parameter in the hot expansion process; it not only directly affects the deformation and shaping effect of the steel pipe, but also relates to the thermal stability and service life of the mandrel. Traditional hot expansion processes often lack real-time temperature monitoring methods, making it impossible to accurately assess the thermal stability of the mandrel, predict potential thermal failure risks, and optimize hot expansion process parameters. Utility Model Content

[0005] This utility model provides a mandrel for hot expansion of steel pipes with temperature measurement function, which aims to solve the problem that the stability and accuracy of the hot expansion process are easily affected by the complex stress under high temperature and high pressure, which can easily lead to deformation and damage of steel pipes. Traditional mandrel designs are difficult to meet the requirements of modern processes and lack real-time temperature monitoring, making it impossible to accurately assess thermal stability, predict thermal failure risks, and optimize process parameters.

[0006] This utility model is implemented as follows: a mandrel for hot expansion of steel pipe with temperature measurement function, comprising a deformation rod; a guide rod disposed at one end of the deformation rod, the guide rod and the deformation rod being integrally formed; a sizing rod disposed at the other end of the deformation rod, the sizing rod and the deformation rod being provided with an active connection structure; the diameters of the guide rod, deformation rod and sizing rod are arranged in ascending order, wherein the outer diameter of the deformation rod gradually increases along the hot expansion direction, forming a gradually transitioning diameter structure; the guide rod and sizing rod are cylindrical structures with constant diameters; the guide rod, deformation rod and sizing rod are all hollow structures, each with a reinforcing chamber inside; the reinforcing chamber includes: a reinforcing ring disposed on the inner sidewall of the guide rod, deformation rod and sizing rod; a shock-absorbing pad is disposed on the contact surface between the reinforcing ring and the guide rod, deformation rod and sizing rod; an assembly ring is disposed at the middle position of the reinforcing ring; a plurality of equidistantly distributed reinforcing ribs are fixedly connected between the assembly ring and the reinforcing ring.

[0007] Preferably, the active connection structure includes: a connecting post disposed on the end side of the deformation rod, the outer surface of the connecting post being provided with an external spiral groove; an installation groove is provided on the side of the sizing rod opposite to the deformation rod, the installation groove being provided with an internal thread groove, and the deformation rod and the sizing rod forming a threaded engagement through the installation groove and the connecting post.

[0008] Preferably, the outer surfaces of the guide rod, deformation rod, and sizing rod are provided with a plurality of mounting grooves, and a detection element is provided in the mounting groove.

[0009] Preferably, the detection element includes a temperature sensor and a pressure sensor disposed within the mounting groove.

[0010] Preferably, the temperature sensor and pressure sensor are provided with heat-conducting sheets that conform to the outer walls of the guide rod, deformation rod and sizing rod.

[0011] Preferably, a reserved through hole is provided on the side of the sizing bar away from the deformation bar, and a cold water pipe is provided in the reserved through hole, with one end of the cold water pipe extending to the inner cavity of the sizing bar.

[0012] Preferably, the cold water pipe extends to the outside of the sizing bar and is connected to a connector.

[0013] Compared with the prior art, the embodiments of this application have the following main advantages:

[0014] Firstly, this device greatly improves the stability of the hot expansion process and the forming quality of the steel pipe. The guide rod and deformation rod adopt an integrated molding structure, ensuring the integrity and strength of the structure and providing stable guidance and support for the steel pipe. The gradual transition diameter-changing structure of the deformation rod allows the steel pipe to gradually and smoothly expand its diameter during the expansion process, effectively avoiding stress concentration and steel pipe damage, thereby ensuring the diameter accuracy and surface quality of the steel pipe. At the same time, the reinforced chamber, reinforcing ring, shock-absorbing pad, and reinforcing ribs inside the mandrel significantly enhance the strength and stability of the mandrel, enabling it to work reliably under high temperature and high pressure environments, further improving the stability of the hot expansion process.

[0015] Secondly, this device also boasts excellent thermal management and ease of maintenance. By creating mounting grooves on the outer surfaces of the guide rod, deformation rod, and sizing rod and installing detection components, the temperature and pressure changes of the mandrel during operation can be monitored in real time. This provides crucial data support for assessing the thermal stability of the mandrel, predicting potential thermal failure risks, optimizing hot expansion process parameters, and precisely controlling the deformation degree and shaping effect of the steel pipe. Furthermore, to improve the accuracy and reliability of temperature measurement, a heat-conducting plate that conforms to the outer wall of the mandrel is installed on the sensor, effectively dispersing and mitigating thermal stress and protecting the sensor from damage.

[0016] Thirdly, this device effectively removes the heat generated during operation by installing a cooling water pipe inside the sizing bar and circulating cooling water, maintaining a stable temperature for the sizing bar and preventing structural failure and performance degradation caused by excessive temperature. It also reduces the generation of thermal stress and further protects the overall structure of the mandrel. These designs not only improve the thermal management efficiency of the mandrel but also make the mandrel more convenient to manufacture and maintain, reducing maintenance costs and improving work efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the three-dimensional structure of the reinforced chamber of this utility model;

[0018] Figure 2 This is a schematic diagram of the three-dimensional structure of the reinforced chamber of this utility model;

[0019] Figure 3 This is a three-dimensional structural schematic diagram of the present invention;

[0020] Figure 4 This is a schematic diagram of the connection structure between the deformation rod and the sizing rod of this utility model;

[0021] Figure 5 This is a front sectional view of the structure of this utility model;

[0022] In the diagram: 1. Deformation rod; 2. Guide rod; 3. Sizing rod; 4. Reinforcing ring; 5. Vibration damping pad; 6. Assembly ring; 7. Reinforcing rib; 8. Connecting column; 9. Mounting groove; 10. Inspection piece; 11. Mounting groove; 12. Heat-conducting plate; 13. Reserved through hole; 14. Cold water pipe; 15. Connector. Detailed Implementation

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] This utility model embodiment provides a mandrel for hot expansion of steel pipes with temperature measurement function, such as... Figure 1-5 As shown, the device includes a deformation rod 1; a guide rod 2 disposed at one end of the deformation rod 1, the guide rod 2 and the deformation rod 1 being integrally formed; and a sizing rod 3 disposed at the other end of the deformation rod 1, the sizing rod 3 and the deformation rod 1 being provided with an active connection structure; the diameters of the guide rod 2, the deformation rod 1 and the sizing rod 3 are arranged in ascending order, wherein the outer diameter of the deformation rod 1 gradually increases along the thermal expansion direction, forming a gradually transitioning diameter structure, and the guide rod 2 and the sizing rod 3... It is a cylindrical structure with a constant diameter; the guide rod 2, deformation rod 1 and sizing rod 3 are all hollow structures with reinforcing chambers inside; the reinforcing chambers include: reinforcing rings 4 disposed on the inner sidewalls of the guide rod 2, deformation rod 1 and sizing rod 3; shock-absorbing pads 5 are provided on the contact surfaces of the reinforcing rings 4 with the guide rods 2, deformation rod 1 and sizing rod 3; an assembly ring 6 is provided at the middle position of the reinforcing rings 4; and several equidistant reinforcing ribs 7 are fixedly connected between the assembly rings 6 and the reinforcing rings 4.

[0026] It should be noted that the stability and accuracy of the expansion process are easily affected by complex stresses under high temperature and pressure, leading to deformation and damage of the steel pipe. Traditional mandrel designs are difficult to meet the requirements of modern processes and lack real-time temperature monitoring, making it impossible to accurately assess thermal stability, predict thermal failure risks, and optimize process parameters. This solution greatly improves the overall efficiency of the hot expansion process. First, the integrated molding structure of the guide rod 2 and the deformation rod 1, as well as the gradual transition diameter design of the deformation rod 1, ensures that the steel pipe can smoothly and accurately expand its diameter during the expansion process, effectively avoiding stress concentration and damage. This guarantees the diameter accuracy and surface quality of the steel pipe, significantly improving the efficiency of hot expansion. The design ensures the stability of the process and the forming quality of the steel pipe. Secondly, by opening an installation groove 11 on the outer surface of the mandrel and installing a detection component 10, real-time monitoring of the temperature and pressure during the mandrel's operation is achieved, providing key data support for process optimization and steel pipe deformation control. At the same time, the setting of the heat-conducting plate 12 also improves the accuracy of temperature measurement and the protection performance of the sensor. Finally, the design of the cooling water pipe 14 inside the sizing bar 3 effectively reduces heat accumulation during the operation process, maintains the stable temperature of the sizing bar 3 and the overall structure of the mandrel, avoids structural failure and performance degradation caused by high temperature, and reduces the generation of thermal stress, further extending the service life of the mandrel.

[0027] Specifically, in this embodiment, the solution mainly includes a deformation rod 1; a guide rod 2 is located at one end of the deformation rod 1 and is integrally formed with the deformation rod 1 to ensure the integrity and strength of the structure; the guide rod 2 has a constant diameter and is a cylindrical structure, and its design purpose is to provide initial guidance and support for the steel pipe during the hot expansion process to ensure that the steel pipe can smoothly enter the deformation area.

[0028] The deformation rod 1 is the core part of the mandrel, and its outer diameter gradually increases along the thermal expansion direction, forming a gradually transitioning diameter structure. This design allows the steel pipe to gradually and smoothly expand its diameter when passing through the deformation rod 1, avoiding stress concentration and steel pipe damage caused by abrupt diameter changes. At the same time, a reinforcing chamber is set inside the hollow structure of the deformation rod 1. The strength and stability of the deformation rod 1 are enhanced by structures such as the reinforcing ring 4, the shock-absorbing pad 5, and the reinforcing rib 7, ensuring its reliable operation under high temperature and high pressure environments. The sizing rod 3 also has a constant diameter and is a cylindrical structure. Its design purpose is to perform final shaping of the steel pipe, ensuring the diameter accuracy and surface quality of the steel pipe.

[0029] In addition, the reinforcing chambers inside the mandrel not only enhance the overall structural strength, but also improve the mandrel's seismic resistance and fatigue resistance through the design of structures such as reinforcing ring 4, shock-absorbing pad 5, and reinforcing rib 7; these structures can effectively absorb and disperse stress during the thermal expansion process, protecting the mandrel from damage.

[0030] In a further preferred embodiment of this utility model, such as Figure 4 As shown, the active connection structure includes: a connecting post 8 disposed on the end side of the deformation rod 1, the outer surface of the connecting post 8 being provided with an external spiral groove; an installation groove 9 is provided on the side of the sizing rod 3 opposite to the deformation rod 1, the installation groove 9 being provided with an internal thread groove, and the deformation rod 1 and the sizing rod 3 forming a threaded engagement through the installation groove 9 and the connecting post 8.

[0031] In this embodiment, a stable and adjustable connection can be formed between the deformation rod 1 and the sizing rod 3 through the rotational engagement of the threads. During the thermal expansion process, the deformation rod 1 and the sizing rod 3 can be easily disassembled by simply rotating the threaded engagement between the connecting column 8 and the mounting groove 9. This design improves the adaptability and flexibility of the mandrel. In addition, the adoption of the active connection structure makes the mandrel more convenient to manufacture and maintain. When it is necessary to replace or repair a part of the mandrel, the relevant parts can be easily disassembled and assembled by simply loosening the threaded engagement, which greatly improves work efficiency and reduces maintenance costs.

[0032] In a further preferred embodiment of this utility model, such as Figure 5 As shown, the outer surfaces of the guide rod 2, deformation rod 1 and sizing rod 3 are all provided with a plurality of mounting grooves 11, and a detection element 10 is provided in the mounting groove 11.

[0033] In this embodiment, these detection elements 10 can monitor the temperature change and stress distribution of the deformed rod 1 in real time during the thermal expansion process, ensuring that the deformation process can proceed smoothly and orderly, and through the analysis of these data.

[0034] In a further preferred embodiment of this utility model, such as Figure 5 As shown, the detection element 10 includes a temperature sensor and a pressure sensor disposed in the mounting groove 11.

[0035] In this embodiment, the temperature sensor (PT100) is responsible for real-time monitoring of the temperature change of the mandrel during the working process. By placing these temperature sensors in the mounting groove 11, the temperature data of the guide rod 2, deformation rod 1 and sizing rod 3 at different working stages can be accurately captured. These data are of great significance for evaluating the thermal stability of the mandrel, predicting potential thermal failure risks and optimizing the thermal expansion process parameters.

[0036] At the same time, the pressure sensor (516MD) monitors the pressure changes of the mandrel during the working process; by monitoring the pressure distribution of the deformation rod 1 in real time during the hot expansion process, the deformation degree and shaping effect of the steel pipe can be controlled more accurately; at the same time, these pressure data also provide important reference for subsequent steel pipe quality inspection and product evaluation.

[0037] In a further preferred embodiment of this utility model, such as Figure 5 As shown, the temperature sensor and pressure sensor are provided with heat-conducting plates 12 that conform to the outer walls of the guide rod 2, deformation rod 1 and sizing rod 3.

[0038] In this embodiment, the heat-conducting sheet 12 is tightly attached to the surface of the steel pipe, and through its excellent thermal conductivity, it rapidly transfers the temperature of the outer wall of the mandrel to the detection element 10. In this way, the detection element 10 can capture the temperature change of the mandrel in real time and accurately, providing important data support for subsequent process control and product evaluation. At the same time, the design of the heat-conducting sheet 12 also takes into account the thermal stress that the mandrel may generate during operation. Through its tight attachment to the outer wall of the mandrel, the heat-conducting sheet 12 can effectively disperse and alleviate thermal stress, protecting the sensor from damage caused by excessive thermal stress.

[0039] In a further preferred embodiment of this utility model, such as Figure 5 As shown, a reserved through hole 13 is provided on the side of the sizing rod 3 away from the deformation rod 1. A cold water pipe 14 is provided in the reserved through hole 13, and one end of the cold water pipe 14 extends to the inner cavity of the sizing rod 3.

[0040] In this embodiment, the cold water pipe 14 is equipped with circulating cold water, which effectively removes the heat generated by the sizing bar 3 during operation; in this way, the sizing bar 3 can be kept within a relatively stable temperature range, avoiding structural failure and performance degradation caused by excessive temperature.

[0041] Meanwhile, the design of the cooling water pipe 14 also takes into account the thermal stress that the mandrel may generate during operation. By reducing the temperature of the sizing bar 3, the cooling water pipe 14 can effectively reduce the generation of thermal stress, thereby protecting the mandrel from damage caused by excessive thermal stress. This design not only improves the reliability and durability of the mandrel, but also ensures that the steel pipe can achieve the best shaping effect during the hot expansion process.

[0042] In a further preferred embodiment of this utility model, such as Figure 5 As shown, the cold water pipe 14 extends to the outside of the sizing bar 3 and is connected to a connector 15.

[0043] In this embodiment, the connection and disconnection between the cold water pipe 14 and the external cooling system can be completed quickly by setting the connector 15.

[0044] Working principle: The mandrel consists of three parts: guide rod 2, deformation rod 1, and sizing rod 3. The guide rod 2 is located at one end of the deformation rod 1 and adopts an integral molding structure with the deformation rod 1 to ensure the integrity and strength of the structure. The guide rod 2 is designed as a cylindrical structure with a constant diameter. Its main function is to provide initial guidance and support for the steel pipe during the hot expansion process, ensuring that the steel pipe can smoothly enter the deformation area.

[0045] The deformation rod 1 is the core part of the mandrel. Its outer diameter gradually increases along the thermal expansion direction, forming a gradually transitioning variable diameter structure. This design allows the steel pipe to gradually and smoothly expand its diameter when passing through the deformation rod 1, avoiding stress concentration and steel pipe damage caused by abrupt diameter changes.

[0046] The sizing bar 3 is also designed as a cylindrical structure with a constant diameter. It is located at the other end of the deformation bar 1. Its main function is to perform the final shaping of the steel pipe to ensure the diameter accuracy and surface quality of the steel pipe.

[0047] Inside the mandrel, a reinforcing chamber is also provided, which not only enhances the overall structural strength, but also improves the mandrel's seismic resistance and fatigue resistance through the design of structures such as reinforcing ring 4, shock-absorbing pad 5, and reinforcing rib 7; these structures can effectively absorb and disperse stress during the thermal expansion process, protecting the mandrel from damage.

[0048] To achieve a stable and adjustable connection between the deformation rod 1 and the sizing rod 3, a threaded rotary fit is adopted. During the hot expansion process, the deformation rod 1 and the sizing rod 3 can be easily disassembled by simply rotating the threaded fit between the connecting column 8 and the mounting groove 9. This design improves the adaptability and flexibility of the mandrel, and also makes the mandrel more convenient to manufacture and maintain.

[0049] To monitor the temperature and pressure changes of the mandrel in real time during operation, several mounting grooves 11 are made on the outer surfaces of the guide rod 2, deformation rod 1, and sizing rod 3, and temperature and pressure sensors are installed in the mounting grooves 11. The temperature sensors are responsible for monitoring the temperature changes of the mandrel in real time, while the pressure sensors jointly monitor the pressure distribution of the mandrel during operation. These data are of great significance for evaluating the thermal stability of the mandrel, predicting potential thermal failure risks, optimizing hot expansion process parameters, and accurately controlling the deformation degree and shaping effect of the steel pipe.

[0050] To improve the accuracy and reliability of temperature measurement, a heat-conducting plate 12 that conforms to the outer wall of the mandrel is provided on the detection element 10. The heat-conducting plate 12 is closely attached to the surface of the detection element 10 and, through its excellent thermal conductivity, rapidly transfers the temperature of the outer wall of the mandrel to the temperature sensor. At the same time, the setting of the heat-conducting plate 12 also effectively disperses and alleviates thermal stress, protecting the sensor from damage caused by excessive thermal stress.

[0051] In addition, in order to control the temperature of the sizing bar 3 during operation, a reserved through hole 13 is opened on the side of the sizing bar 3 away from the deformation bar 1, and a cooling water pipe 14 is installed in the reserved through hole 13. The cooling water pipe 14 is filled with circulating cooling water, which effectively removes the heat generated by the sizing bar 3 during operation. In this way, the sizing bar 3 can be kept within a relatively stable temperature range, avoiding structural failure and performance degradation caused by excessive temperature. At the same time, the installation of the cooling water pipe 14 also reduces the generation of thermal stress, further protecting the mandrel from damage.

[0052] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0053] It should be understood that the disclosed apparatus can be implemented in other ways, given the several embodiments provided in this application. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units described above may be implemented in other ways in practice. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or communication connections shown or discussed may be through some interfaces; indirect coupling or communication connections between devices or units may be telecommunications or other forms.

[0054] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0055] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Although this utility model has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of this utility model according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of this utility model. These technical solutions are also within the scope of protection of this utility model.

Claims

1. A mandrel for hot expansion of a steel pipe with temperature measurement function, characterized by, The utility model relates to a kind of variable diameter rods, comprising: Deformation rod (1); Guide rod (2) is arranged at one end of the deformation rod (1), and the guide rod (2) is integrally formed with the deformation rod (1); The sizing rod (3) is arranged at the other end of the deformation rod (1), and the active connection structure is arranged between the sizing rod (3) and the deformation rod (1); The variable diameter sizes of the guide rod (2), the deformation rod (1) and the sizing rod (3) are arranged in order from small to large, wherein the outer diameter of the deformation rod (1) gradually increases along the hot expanding direction, forming a gradually transition variable diameter structure, and the guide rod (2) and the sizing rod (3) are cylindrical structures with constant diameter; The guide rod (2), the deformation rod (1) and the sizing rod (3) are all hollow structures, and each has a reinforcing chamber inside; The reinforcing chamber comprises: A reinforcing ring (4) is arranged on the inner side wall of the guide rod (2), the deformation rod (1) and the sizing rod (3); The contact surface of the reinforcing ring (4) with the guide rod (2), the deformation rod (1) and the sizing rod (3) is provided with a shock pad (5); A fitting ring (6) is arranged at the middle position of the reinforcing ring (4); A plurality of equally spaced reinforcing ribs (7) are fixedly connected between the fitting ring (6) and the reinforcing ring (4).

2. The mandrel for use in hot expanding of a steel pipe with temperature measurement function according to claim 1, characterized by The active connection structure comprises: A connecting column (8) is arranged on the end side of the deformation rod (1), and the outer surface of the connecting column (8) is provided with an outer spiral groove; An installation groove (9) is formed on the side opposite to the deformation rod (1) of the sizing rod (3), and an inner thread groove is arranged in the installation groove (9), and the deformation rod (1) and the sizing rod (3) are threadedly connected through the installation groove (9) and the connecting column (8).

3. The mandrel for use in hot expanding of a steel pipe with temperature measurement function according to claim 2, characterized in that A plurality of installation grooves (11) are formed on the outer surfaces of the guide rod (2), the deformation rod (1) and the sizing rod (3), and a detection piece (10) is arranged in each installation groove (11).

4. The mandrel for use in hot expanding of a steel pipe with temperature measurement function as set forth in claim 3, characterized by The detection piece (10) comprises a temperature sensor and a pressure sensor arranged in the installation groove (11).

5. The mandrel for use in hot expanding of a steel pipe with temperature measurement function as defined in claim 4, characterized by The temperature sensor and the pressure sensor are provided with a heat-conducting sheet (12) that matches the outer wall of the guide rod (2), the deformation rod (1) and the sizing rod (3).

6. The mandrel for use in hot expanding of a steel pipe with temperature measurement function as set forth in claim 5, characterized by A reserved through hole (13) is formed on the side of the sizing rod (3) away from the deformation rod (1), and a cold water pipe (14) is arranged in the reserved through hole (13), and one end of the cold water pipe (14) extends to the inner cavity position of the sizing rod (3).

7. The mandrel for use in hot expanding of a steel pipe with temperature measurement function as defined in claim 6, characterized by The cold water pipe (14) is connected to a connecting head (15) at the outer position of the sizing rod (3).

Images