Anti-cracking heat exchange pipe end groove structure and machining method thereof

Abstract

The invention discloses an anti-cracking heat exchange pipe end groove structure and a machining method thereof. The machining method comprises the steps of building a heat exchange pipe end groove structure calculation model and machining the heat exchange pipe end groove structure based on the heat exchange pipe end groove structure calculation model. The heat exchange tube end groove structure comprises a heat exchange tube and a tube plate, a plurality of tube holes are formed in the tube plate, and first grooves are formed in the edges of the tube holes; the heat exchange tube is coaxially inserted into the tube hole, a second groove which is an inner V-shaped groove or an inner arc-shaped groove is formed in the inner wall of the tube end of the heat exchange tube, and the root of the second groove exceeds the end face of the tube plate; and the heat exchange tube and the tube plate are welded into a whole. The method has the beneficial effects that a heat exchange tube end groove structure calculation model is established, grooves are machined in the tube plate and the tube end of the heat exchange tube in combination with the model, the grooves of the tube ends are in an inner V shape or an inner arc shape, the tube end morphology of the heat exchange tube is changed, welding stress distribution of the heat exchange tube is changed, tube end cracking and tube opening pollution are effectively prevented, and the heat exchange effect is improved. The service life of the heat exchanger is prolonged.

Description

Technical Field

[0001] The present application relates to the field of welding, and in particular to a crack-proof heat exchange tube end groove structure and a processing method thereof. Background Art

[0002] The heat exchange tubes in the heat exchanger are the main medium for heat exchange and play a key role in the condenser. Because they are often in complex working conditions such as corrosion, oxidation and high pressure, and are affected by factors such as equipment vibration, heat exchange tubes often face the risk of partial or overall failure. These problems may eventually affect the normal operation of the heat exchanger. Austenitic stainless steel has good toughness and strong weldability. It also has good corrosion resistance, wear resistance, mechanical properties and toughness, as well as excellent machinability and weldability, making it a widely selected heat exchanger tube material for heat exchangers in the industry. It is widely used in industrial fields such as petroleum, chemical industry and medical equipment. However, austenitic stainless steel is very sensitive to contamination by low-melting-point substances such as copper. There are many studies and cases of welding cracks and hot working cracks caused by copper contamination in actual production applications. The traditional method of welding heat exchange tubes and tube sheets is generally to pass the heat exchange tubes through the tube sheet, open a groove on the tube sheet, and then weld the two together. Under the action of welding stress concentration, the cracking caused by copper contamination is more sensitive and serious. The cracking failure of the tube end is as follows: Fig.12 , Fig.13 As shown in the figure, the cracks all start from the inside of the pipe end and extend longitudinally along the thickness of the pipe end and the inner wall.

[0003] like Figure 3~Figure 6 As shown, the tube end of the conventional heat exchange tube 1' of the current tubular heat exchanger equipment is an I-type groove 11'. When welding the conventional tube sheet 2', cracks often occur at the tube end. This is mainly due to stress concentration. The maximum Mises stress caused by welding is concentrated on the inner wall of the tube end. In addition, the I-type groove easily causes the inner wall of the tube end to be contaminated by the positioning core rod of the welding equipment. The combination of the two makes the possibility of cracking even greater.

[0004] Therefore, there is an urgent need for a heat exchange tube and a processing method thereof that can effectively change the welding stress distribution, prevent tube end cracks, and reduce or avoid tube orifice contamination. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide an anti-cracking heat exchange tube end groove structure and a processing method thereof, so as to solve the current problems that the heat exchange tube ends are prone to cracks and the tube ends are prone to contamination.

[0006] To solve the above problems, the technical solution adopted in this application is: The present application provides a method for processing a heat exchange tube end groove structure to prevent cracking, which is characterized by comprising the steps of establishing a heat exchange tube end groove structure calculation model and processing the heat exchange tube end groove structure based on the heat exchange tube end groove structure calculation model; The steps for establishing the calculation model of the groove structure of the heat exchange tube end include: A geometric model of the groove structure of the tube end of the heat exchange tube is established in the modeling software based on the material properties, size parameters and installation position parameters of the tube sheet and the heat exchange tube, wherein the first groove is designed on the edge of the tube hole of the tube sheet and the second groove is designed on the inner wall of the tube end of the heat exchange tube; Dividing the geometric model and determining the number of weld passes and layers required for simulating the assembly of tube sheets and heat exchange tubes; The surfacing process of the weld is simulated by using the birth and death unit technology, and the birth and death unit subroutine is used to control the coordination of the birth and death unit and the heat source movement to simulate the material addition process of the weld; the heat source subroutine is compiled and imported into the finite element software to establish a double ellipsoid heat source model; the double ellipsoid heat source model includes a front half ellipsoid heat source model and a rear half ellipsoid heat source model; The double ellipsoid heat source model is loaded onto the geometric model for processing, and solved based on finite element software to obtain heat source simulation results; the heat source simulation results include the cross-sectional morphology of the weld and the temperature field and stress field data stress deformation field of the model that change with time; Based on the heat source simulation result, the processing parameters of the groove structure of the heat exchange tube end are corrected to ensure that the Mises maximum stress concentration point of the heat exchange tube is moved back to the inside of the heat exchange tube, and the processing parameters of the groove structure of the heat exchange tube end are generated; the processing parameters at least include the morphological parameters of the first groove, the morphological parameters of the second groove, and the relative welding position of the first groove and the second groove; The steps of processing the groove structure of the heat exchange tube end based on the heat exchange tube end groove structure calculation model include: Based on the processing parameters of the corrected groove structure of the heat exchange tube end, a first groove is processed on the edge of the tube hole of the tube sheet, and a second groove is processed on the inner wall of the tube end of the heat exchange tube; Insert the heat exchange tube coaxially into the tube hole of the tube sheet, and keep the root of the second groove of the heat exchange tube beyond the front end face of the tube sheet, weld the tube sheet and the heat exchange tube at the first groove, connect the front end face of the tube sheet and the tube end of the heat exchange tube through the weld, and complete the assembly processing of the groove structure of the tube end of the heat exchange tube.

[0007] As a preferred embodiment of the present application, the heat flow expression of any point in the front semi-ellipsoid heat source model is: When 0≤ z ≤ h hour: (1); when h≤ z ≤ H hour: (2); The heat flow expression of any point in the rear semi-ellipsoid heat source model is: When 0≤ z ≤ h hour: (3); when h ≤ z ≤ H hour: (4); Where: q (x ,y ,z) The heat flux distribution of the double ellipsoid heat source model [J / (m 2 ﹒ s); Q f Get the heat (W) for the first half of the heat source model; h is the depth of the inflection point (m); H is the depth of heat source (m); l is the proportionality coefficient; z is the z-axis coordinate of the double ellipsoid heat source model (m); a 1 is the shape parameter of the front half ellipsoid; a 2 is the shape parameter of the rear half ellipsoid; b is the shape parameter of the ellipsoid.

[0008] As a preferred embodiment of the present application, the second groove is an outward-inclined inner V-shaped groove, the height of the second groove is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube, and the inclination angle θ of the second groove is 30° to 60°.

[0009] As a preference of the present application, the height of the second groove is 1 mm, and the inclination angle θ of the second groove is 45°.

[0010] As a preferred embodiment of the present application, the second groove is an inner arc groove, and the inner arc groove is concave toward the first groove.

[0011] As a preferred embodiment of the present application, the groove radius of the second groove is 1 / 2 to 1 of the wall thickness of the heat exchange tube.

[0012] As a preferred embodiment of the present application, the groove radius of the second groove is 2 mm.

[0013] As a preferred embodiment of the present application, the number of welding layers is 2, the first layer has a welding current of 120 A, a welding voltage of 12 V and a welding speed of 160 mm / min; the second layer has a welding current of 122 A, a welding voltage of 12 V and a welding speed of 120 mm / min.

[0014] As a preferred embodiment of the present application, when the first groove and the second groove are outward-inclined inner V-shaped grooves, the groove parameters include the outer diameter of the heat exchange tube, the wall thickness of the heat exchange tube, the length of the tube end of the heat exchange tube extending out of the tube sheet, the inner diameter of the tube sheet, the height of the first groove, the inclination angle of the first groove, the height of the second groove and the inclination angle of the second groove.

[0015] As a preferred embodiment of the present application, when the first groove is an outward-inclined inner V-shaped groove and the second groove is an inner arc-shaped groove, the groove parameters include the outer diameter of the heat exchange tube, the wall thickness of the heat exchange tube, the length of the tube end of the heat exchange tube extending out of the tube sheet, the inner diameter of the tube sheet, the height of the first groove, the inclination angle of the first groove, and the groove radius of the second groove.

[0016] The present application also provides a heat exchange tube end groove structure, comprising a heat exchange tube and a tube sheet, characterized in that: a plurality of tube holes are provided on the tube sheet, and a first groove is provided at the edge of the tube hole; the heat exchange tube is coaxially inserted into the tube hole of the tube sheet, and the tube end of the heat exchange tube protrudes outward from the front end surface of the tube sheet, and the inner wall of the tube end of the heat exchange tube is processed with a second groove, the second groove is an inner V-shaped groove or an inner arc-shaped groove, and the root of the second groove exceeds the front end surface of the tube sheet; the heat exchange tube and the tube sheet are welded as a whole.

[0017] As a preferred embodiment of the present application, the first groove is an outward-inclined inner V-shaped groove.

[0018] As a preferred embodiment of the present application, the height of the first groove is 1-5 mm.

[0019] As a preferred embodiment of the present application, the height of the first groove is 2 mm.

[0020] As a preferred embodiment of the present application, the inclination angle of the first groove is 30°~60°.

[0021] As a preferred embodiment of the present application, the inclination angle of the first groove is 45°.

[0022] As a preferred embodiment of the present application, the second groove is an outward-inclined inner V-shaped groove.

[0023] As a preferred embodiment of the present application, the height of the second groove is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube.

[0024] As a preferred embodiment of the present application, the wall thickness of the heat exchange tube is 2 mm.

[0025] As a preferred embodiment of the present application, the height of the second groove is 0.5~6mm.

[0026] As a preferred embodiment of the present application, the height of the second groove is 1 mm.

[0027] As a preferred embodiment of the present application, the inclination angle θ of the second groove is 30°~60°.

[0028] As a preferred embodiment of the present application, the inclination angle θ of the second groove is 45°.

[0029] As a preferred embodiment of the present application, the second groove is an inner arc groove, and the inner arc groove is concave toward the first groove.

[0030] As a preferred embodiment of the present application, the groove radius of the second groove is 1 / 2 to 1 of the wall thickness of the heat exchange tube.

[0031] As a preferred embodiment of the present application, the groove radius of the second groove is 2 mm.

[0032] As a preferred embodiment of the present application, the tube end of the heat exchange tube extends out of the front end surface of the tube sheet close to the tube end by 3 to 7 mm.

[0033] As a preferred embodiment of the present application, the tube end of the heat exchange tube extends out of the front end surface of the tube sheet close to the tube end by 5 mm.

[0034] The present application also provides a heat exchanger, characterized in that it comprises a heat exchange tube end bevel structure manufactured by the heat exchange tube end bevel structure processing method or the heat exchange tube end bevel structure described in the present application.

[0035] Compared with the prior art, the beneficial effects of the present application are: establishing a calculation model for the groove structure of the tube end of the heat exchange tube, and processing grooves on the tube sheet and the tube end of the heat exchange tube according to the model, forming front-to-back staggered welding positions by changing the tube end morphology of the heat exchange tube and the front-to-back staggering of the groove, thereby changing the welding stress distribution of the heat exchange tube, so that the welding stress of the heat exchange tube is moved from the tube end to the inside of the heat exchange tube, effectively preventing tube end cracking and tube end contamination, and improving the service life of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flowchart of a method for processing the groove structure of a heat exchange tube end of the present application.

[0037] Figure 2 Schematic diagram of the structure of the groove structure of the heat exchange tube end of Example 1.

[0038] Figure 3 Schematic diagram of parameter marking of the groove structure at the end of the heat exchange tube in Example 1.

[0039] Figure 4 This is a schematic structural diagram of the groove structure at the end of the heat exchange tube in Example 2.

[0040] Figure 5 Schematic diagram of parameter marking of the groove structure at the end of the heat exchange tube in Example 2.

[0041] Figure 6 Schematic diagram of the simulation calculation model of the groove structure of the heat exchange tube end of Example 1 of the present application (number of units: 20840 number of nodes: 24600).

[0042] Figure 7 and Figure 8 They are schematic diagrams of simulation calculation results of the groove structure of the heat exchange tube end of Example 1 of the present application.

[0043] Fig. 9 This is a schematic diagram of a simulation calculation model for the groove structure of the heat exchange tube end of Example 2 of the present application (number of units: 20840 number of nodes: 24600).

[0044] Fig.10 and Fig.11 Schematic diagram of simulation calculation results of the groove structure at the end of the heat exchange tube in Example 2 of the present application.

[0045] Fig.12 and Fig.13 The heat exchange tube ends of the traditional tubular heat exchanger equipment with I-type grooves crack and fail.

[0046] Fig.14 It is a schematic diagram of the structure of the traditional I-type groove heat exchange tube end.

[0047] Fig.15 This is a partial enlarged view of the end of a heat exchange tube with a traditional I-type groove.

[0048] Fig.16 and Fig.17 The welding position and enlarged view of the welding position of the traditional I-groove heat exchange tube end, where B is the weld and C is the heat affected zone.

[0049] Fig.18 Schematic diagram of the simulation calculation model for the end of a heat exchange tube with an I-type groove (number of elements: 21160, number of nodes: 24256).

[0050] Fig.19 Schematic diagram of the heat source model for the end of the heat exchange tube with an I-type groove.

[0051] Fig. 20 and Fig.21 It is a schematic diagram of the simulation calculation results of the tube end of the heat exchange tube with an I-type groove, where D is the observation section.

[0052] In the accompanying drawings: 1-heat exchange tube; 11-second groove; 2-tube sheet; 21-first groove; 22-front end face; 1'-traditional heat exchange tube; 11'-I-type groove; 2'-traditional tube sheet. DETAILED DESCRIPTION

[0053] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application.

[0054] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0055] In addition, it should be understood that one or more method steps mentioned in this application do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in this application does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these two explicitly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of implementation of this application. Changes or adjustments in their relative relationships shall also be regarded as the scope of implementation of this application without substantial changes in the technical content.

[0056] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0057] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "inner", "outer", "axial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, "multiple" means two or more.

[0058] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0060] The present application is further described below in conjunction with specific embodiments, but the protection scope of the present application is not limited thereto.

[0061] like Figure 1 As shown, the present application also provides a method for processing the bevel structure of the tube end of a heat exchange tube to prevent cracking, including the steps of establishing a calculation model for the bevel structure of the tube end of the heat exchange tube and processing the bevel structure of the tube end of the heat exchange tube based on the calculation model for the bevel structure of the tube end of the heat exchange tube; S1 establishes a geometric model of the groove structure of the heat exchange tube end in the modeling software based on the material properties, size parameters and position parameters of the heat exchange tube and the tube sheet, wherein the first groove is designed at the edge of the tube hole of the tube sheet and the second groove is designed on the inner wall of the tube end of the heat exchange tube; S2 divides the geometric model and determines the number of welds and the number of layers required for simulating the assembly of the tube sheet and the heat exchange tube; S3 uses birth and death unit technology to simulate the surfacing process of the weld bead, uses birth and death unit subroutine to control the coordination of birth and death unit and heat source movement, and simulates the material addition process of the weld bead; compiles the heat source subroutine and imports it into the finite element software to establish a double ellipsoid heat source model; the double ellipsoid heat source model includes a front half ellipsoid heat source model and a rear half ellipsoid heat source model, wherein: The heat flow expression at any point in the front semi-ellipsoid heat source model is: When 0≤ z ≤ h hour: (1); when h ≤z ≤ H hour: (2); The heat flow expression of any point in the rear semi-ellipsoid heat source model is: When 0≤ z ≤ h hour: (3); when h ≤ z ≤ H hour: (4); Where: q (x ,y ,z) The heat flux distribution of the double ellipsoid heat source model [J / (m 2 ﹒ s); Q f Get the heat (W) for the first half of the heat source model; h is the depth of the inflection point (m); H is the depth of heat source (m); l is the proportionality coefficient; z is the z-axis coordinate of the double ellipsoid heat source model (m); a 1 is the shape parameter of the front half ellipsoid; a 2 is the shape parameter of the rear half ellipsoid; b is the shape parameter of the ellipsoid; S4 loads the double ellipsoid heat source model onto the geometric model for processing, compiles the heat source subroutine in the Visual Studio compilation platform using the Fortran language and imports it into the Abaqus finite element software, performs a solution based on the Abaqus finite element software, and obtains heat source simulation results; the heat source simulation results include the cross-sectional morphology of the weld and the temperature field and stress field data of the model that change with time, stress deformation field; S5: based on the heat source simulation result, modifying the processing parameters of the groove structure of the heat exchange tube end to ensure that the Mises maximum stress concentration point of the heat exchange tube is moved back to the heat exchange tube; the processing parameters at least include the morphology, relative position and groove parameters of the first groove of the tube sheet and the second groove on the heat exchange tube; S6: Based on the modified processing parameters of the groove structure of the tube end of the heat exchange tube, a first groove is processed on the edge of the tube hole of the tube sheet, and a second groove is processed on the inner wall of the tube end of the heat exchange tube; S7 inserts the heat exchange tube coaxially into the tube hole of the tube sheet, and keeps the root of the second groove of the heat exchange tube beyond the front end face of the tube sheet, welds the tube sheet and the heat exchange tube at the first groove, connects the front end face of the tube sheet and the tube end of the heat exchange tube through the weld, and completes the assembly processing of the groove structure of the tube end of the heat exchange tube.

[0062] Steps S1 to S5 are steps for establishing a calculation model for the groove structure of the heat exchange tube end; and steps S6 to S7 are steps for processing the groove structure of the heat exchange tube end based on the calculation model for the groove structure of the heat exchange tube end.

[0063] In some embodiments of the present application, the number of welding layers is 2, the first layer has a welding current of 120 A, a welding voltage of 12 V and a welding speed of 160 mm / min; the second layer has a welding current of 122 A, a welding voltage of 12 V and a welding speed of 120 mm / min.

[0064] like Figure 2~Figure 5 As shown, the present application provides a crack-proof heat exchange tube end groove structure, wherein the tube sheet 2 is provided with a plurality of tube holes, and a first groove 21 is provided at the edge of the tube hole; the heat exchange tube 1 is coaxially inserted into the tube hole of the tube sheet 2, and the tube end of the heat exchange tube 1 protrudes outward from the front end surface of the tube sheet 2, and the inner wall of the tube end of the heat exchange tube 1 is processed with a second groove 11, and the second groove 11 is an inner V-shaped groove or an inner arc-shaped groove, and the root of the second groove 11 exceeds the front end surface 22 of the tube sheet 2; the heat exchange tube 1 and the tube sheet 2 are welded as a whole.

[0065] like Figure 2~Figure 5 As shown, the first groove 21 is an outward-inclined inner V-shaped groove.

[0066] like Figure 2~Figure 5 As shown, the height of the first groove is 1-5 mm, preferably 2 mm.

[0067] like Figure 2~Figure 5 As shown, the inclination angle of the first groove is 30° to 60°, preferably 45°.

[0068] like Figure 2~Figure 5 As shown, the tube end of the heat exchange tube 1 extends 3 to 7 mm from the front end surface of the tube sheet 2 close to the tube end, preferably 5 mm.

[0069] The inner V-shaped groove of the groove structure of the heat exchange tube end of the present application is as follows Figure 2 and Figure 3 As shown in the figure, the meanings of the parameters are as follows: OD-outer diameter of heat exchange tube, T-wall thickness of heat exchange tube, L-length of heat exchange tube to tube sheet, ID-inner diameter of tube sheet, h-height of V-groove of inner hole of tube sheet, ψ-angle of V-groove of inner hole of tube sheet, t-height of V-groove inside heat exchange tube, θ-angle of V-groove inside heat exchange tube.

[0070] like Figure 2 and Figure 3 As shown, the second groove 11 is an outward-inclined inner V-shaped groove.

[0071] like Figure 2 and Figure 3As shown, the height of the second groove 11 is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube 1 .

[0072] like Figure 2 and Figure 3 As shown, the inclination angle θ of the second groove 11 is 30° to 60°.

[0073] like Figure 2 and Figure 3 As shown, the second groove 11 is an inner arc groove, and the concave surface of the inner arc groove faces the first groove.

[0074] like Figure 2 and Figure 3 As shown, the groove radius of the second groove 11 is 1 / 2 to 1 of the wall thickness of the heat exchange tube 1.

[0075] like Figure 2 and Figure 3 As shown, the groove radius of the second groove is 2 mm.

[0076] The present application also provides a heat exchanger, including a heat exchange tube end bevel structure processed according to the heat exchange tube end inner bevel calculation model establishment method or a heat exchange tube end bevel structure as described in the present application.

[0077] Example 1 Taking the inner V-groove of the tube end of the heat exchange tube as an example, the heat source subroutine was compiled by Fortran language in the Visual Studio compilation platform and imported into Abaqus finite element software to simulate the stress distribution of the welded joint.

[0078] Specifically, the parameters of the tube sheet and heat exchange tube of the heat exchange tube end groove structure of this embodiment are as follows: the heat exchange tube material brand GB / T 13296 S31603, specification φ25*2mm. The tube sheet material brand is S31603Ⅲ, thickness 85mm, inner hole diameter φ25.3mm, and the length of the tube extending from the outer surface of the tube sheet is 5mm. The parameters of the heat exchange tube end groove structure of this embodiment are as follows: OD=25mm, T=2mm, L=5mm, ID=25.3mm, h=2mm, ψ=45°, t=1mm, θ=45°. The V-shaped groove inside the tube end is calculated, and the second groove diagram of the heat exchange tube end is shown in the figure. Figure 2 and Figure 3 , settlement results see Figure 7 and Figure 8 .

[0079] The wire-filling welding is realized by adopting the life-death unit technology. Specifically, the first layer of the mobile heat source is loaded with a welding current of 120A, a welding voltage of 12V, and a welding speed of 160mm / min; the second layer of the welding current is 122A, a welding voltage of 12V, and a welding speed of 120mm / min. The simulation parameters are shown in Table 1, and the simulation calculation model is shown in Figure 6 The simulation results are shown in Figure 7 and Figure 8 .

[0080] Table 1 Simulation parameters of wire-filling welding using the birth-death unit technology Temperature (℃) Elastic modulus (GPa) Poisson's ratio <![CDATA[Coefficient of thermal expansion 10 -6 / °C]]> Yield strength MPa Specific heat J / (kg﹒℃) Thermal conductivity W / (m﹒K) <![CDATA[Density (g / cm 3 )]]> 20 205 0.3 16.0 250 502 16.3 7.98 100 198 0.3 16.0 220 515 18.0 7.93 200 191 0.3 16.1 180 530 19.5 7. 89 300 183 0.3 16.2 170 538 20.2 7.83 400 176 0.3 16.8 155 550 21.8 7.78 500 168 0.3 17.5 150 569 23.2 7.73 600 159 0.3 18.1 143 580 25.0 7.68 700 150 0.3 18.6 138 595 27.2 7.62 800 140 0.3 19.0 60 620 28.2 7.57 1000 125 0.3 19.7 30 659 29.0 7.45 1200 100 0.3 20.2 10 795 30.2 7.34 1400 0.1 0.3 21.1 1 886 31.1 7.22 Through the above calculation, the maximum Mises stress of the V-groove inside the pipe end is 331MPa, and is distributed inside the pipe.

[0081] Example 2 For the inner arc groove of the groove structure of the heat exchange tube end, the heat source subroutine is compiled by Fortran language in the Visual Studio compilation platform and imported into Abaqus finite element software to simulate the stress distribution of the welded joint.

[0082] like Figure 4 and Figure 5 As shown, taking the inner circular groove of the tube end as an example, the meanings of the parameters in the figure are as follows: OD-outer diameter of the heat exchange tube, T-wall thickness of the heat exchange tube, L-length of the heat exchange tube to form the tube sheet, ID-inner diameter of the tube sheet, h-height of the V-groove of the inner hole of the tube sheet, ψ-angle of the V-groove of the inner hole of the tube sheet, and R radius of the inner circular groove of the heat exchange tube.

[0083] Specifically, taking the inner circular groove of the tube end as an example, the parameters of the tube sheet and heat exchange tube of the groove structure of the tube end of the heat exchange tube in this embodiment are as follows: the material grade of the heat exchange tube is GB / T 13296 S31603, and the specification is φ25*2mm. The material grade of the tube sheet is S31603Ⅲ, the thickness is 85mm, the inner hole diameter is φ25.3mm, and the length of the tube extending out of the outer surface of the tube sheet is 5mm. The parameters of the groove structure of the tube end of the heat exchange tube in this application are as follows: OD=25mm, T=2mm, L=5mm, ID=25.3mm, h=2mm, ψ=45°, R=2mm. The inner groove of the tube end is calculated, and the second groove diagram of the heat exchange tube end is shown in FIG. Figure 4 and Figure 5 , the simulation calculation model is shown in Fig. 9 , settlement results see Fig.10 and Fig.11 .

[0084] The wire-filling welding is realized by adopting the birth-death unit technology, and the specific parameters are the same as those in Example 1.

[0085] Through the above calculations, the maximum Mises stress of the circular groove at the pipe end is 319MPa, and is distributed inside the pipe.

[0086] Comparative Example 1 This comparative example is described by taking the tube end of a traditional heat exchange tube with an "I" type groove as an example. The heat source subroutine is compiled by Fortran language in the Visual Studio compilation platform and imported into the Abaqus finite element software to simulate the stress distribution of the welded joint.

[0087] Specifically, the parameters of the tube sheet and heat exchange tube of the heat exchange tube end groove structure of this embodiment are as follows: the heat exchange tube material brand GB / T 13296 S31603, specification φ25*2mm. The tube sheet material brand S31603Ⅲ, thickness 85mm, inner hole diameter φ25.3mm, the length of the tube extending from the outer surface of the tube sheet is 5mm. The parameters of the heat exchange tube end groove structure of this application are as follows: OD=25mm, T=2mm, L=5mm, ID=25.3mm, h=2mm, ψ=45°. For calculation, the I-type groove of the traditional heat exchange tube end is shown in the figure. Figure 14~Figure 17 , the simulation calculation model is shown in Fig.18 , settlement results see Figure 20~Figure 21 The actual tube heat exchanger equipment has an I-type groove at the end of the heat exchange tube, and the crack failure diagram is as follows: Fig.12 and Fig.13 shown.

[0088] The wire-filling welding is realized by adopting the birth-death unit technology, and the specific parameters are the same as those in Example 1.

[0089] According to the above calculation, the maximum Mises stress of the I-type groove is 392MPa, and it is distributed on the inner wall at the end of the pipe, which makes the pipe end very easy to crack. In addition, since the I-type groove is easy to scratch the positioning core rod of the welding gun, it will cause the pipe mouth to be contaminated.

[0090] It can be seen from the test results of Example 1, Example 2 and Comparative Example 1 that the improved heat exchange tube end groove structure changes the welding stress distribution by changing the tube end morphology; and prevents tube end contamination and cracking problems by changing the tube end morphology.

[0091] The above examples are for the purpose of illustrating the embodiments disclosed in the present application and should not be construed as limiting the present application. In addition, the various modifications listed herein and the variations of methods and compositions in the invention are obvious to those skilled in the art without departing from the scope and spirit of the present application. Although the present application has been specifically described in conjunction with various specific preferred embodiments of the present application, it should be understood that the present application should not be limited to these specific embodiments. In fact, various modifications obvious to those skilled in the art as described above to obtain inventions should be included within the scope of the present application.

Claims

1. A method for processing a crack-proof heat exchange tube end groove structure, characterized in that: The method comprises the steps of establishing a heat exchange tube end groove structure calculation model and processing the heat exchange tube end groove structure based on the heat exchange tube end groove structure calculation model; The steps of establishing the calculation model of the groove structure of the heat exchange tube end include: A geometric model of the groove structure of the tube end of the heat exchange tube is established based on the material properties, size parameters and installation position parameters of the tube sheet and the heat exchange tube, in which a first groove is designed at the edge of the tube hole of the tube sheet and a second groove is designed on the inner wall of the tube end of the heat exchange tube; Dividing the geometric model and determining the number of weld passes and layers required for simulating the assembly of tube sheets and heat exchange tubes; Simulating the surfacing process of the weld bead and establishing a double ellipsoid heat source model; the double ellipsoid heat source model includes a front half ellipsoid heat source model and a rear half ellipsoid heat source model; The double ellipsoid heat source model is loaded onto the geometric model, and the solution is performed based on the finite element software to obtain the heat source simulation result; the heat source simulation result includes the cross-sectional morphology of the weld, the temperature field and stress field data stress deformation field of the model changing with time; Based on the heat source simulation results, the groove structure of the heat exchange tube end in the geometric model is corrected, and the processing parameters of the groove structure of the heat exchange tube end are generated to ensure that the Mises maximum stress concentration point of the heat exchange tube is moved back to the heat exchange tube; the processing parameters at least include the morphological parameters of the first groove, the morphological parameters of the second groove, and the relative welding position of the first groove and the second groove.

2. The method for processing the anti-cracking heat exchange tube end groove structure according to claim 1, characterized in that: The heat flow expression at any point in the front semi-ellipsoid heat source model is: When 0≤ z ≤ h hour: （1）； when h ≤ z ≤ H hour: （2）； The heat flow expression of any point in the rear semi-ellipsoid heat source model is: When 0≤ z ≤ h hour: （3）； when h ≤ z ≤ H hour: （4）； Where: q (x ,y ,z) Heat flux distribution of the double ellipsoid heat source model ; Q f Get the heat (W) for the first half of the heat source model; h is the depth of the inflection point (m); H is the depth of heat source (m); l is the proportionality coefficient; z is the z-axis coordinate of the double ellipsoid heat source model (m); a 1 is the shape parameter of the front half ellipsoid; a 2 is the shape parameter of the rear half ellipsoid; b is the shape parameter of the ellipsoid.

3. The method for processing the anti-cracking heat exchange tube end groove structure according to claim 1, characterized in that: The number of welding layers is 2. The first layer has a welding current of 120A, a welding voltage of 12V and a welding speed of 160mm / min. The second layer has a welding current of 122A, a welding voltage of 12V and a welding speed of 120mm / min.

4. The method for processing the anti-cracking heat exchange tube end groove structure according to claim 1, characterized in that: The second groove (11) is an inner V-shaped groove or an inner arc-shaped groove.

5. A heat exchange tube end groove structure manufactured according to the method for processing the anti-cracking heat exchange tube end groove structure according to any one of claims 1 to 4, comprising a heat exchange tube (1) and a tube sheet (2), characterized in that: The tube sheet (2) is provided with a plurality of tube holes for inserting the heat exchange tubes (1), and the front end surfaces of the tube holes are provided with first grooves (21); the heat exchange tubes (1) are coaxially inserted into the tube holes of the tube sheet (2), and the tube ends of the heat exchange tubes (1) extend outward from the front end surface of the tube sheet (2); the inner wall of the tube ends of the heat exchange tubes (1) is processed with second grooves (11), and the second grooves (11) are inner V-shaped grooves or inner arc-shaped grooves, and the root of the second grooves (11) exceeds the front end surface (22) of the tube sheet (2); the heat exchange tubes (1) and the tube sheet (2) are welded as a whole.

6. The heat exchange tube end groove structure according to claim 5, characterized in that: The first groove (21) is an outwardly inclined inner V-shaped groove.

7. The heat exchange tube end groove structure according to claim 5, characterized in that: The second groove (11) is an outward-inclined V-shaped groove.

8. The heat exchange tube end groove structure according to claim 7, characterized in that: The height of the second groove (11) is 1 / 4 to 3 / 4 of the wall thickness of the heat exchange tube (1), and the inclination angle θ of the second groove (11) is 30° to 60°.

9. The heat exchange tube end groove structure according to claim 5, characterized in that: The second groove (11) is an inner arc groove, and the inner arc groove is concave toward the first groove.

10. The heat exchange tube end groove structure according to claim 9, characterized in that: The groove radius of the second groove (11) is 1 / 2 to 1 of the wall thickness of the heat exchange tube (1).

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