Large telescopic arm structure welding optimization process based on numerical simulation technology

Abstract

The invention discloses a large telescopic arm structure welding optimization process based on a numerical simulation technology, and aims to solve the problems that after a large telescopic arm is welded, residual stress is large, deformation is obvious, so that size parameters exceed design limitation requirements, the bearing capacity is reduced, the service life is shortened, and the like. The welding process of the telescopic arm is subjected to numerical simulation based on a finite element method, stress fields and deformation distribution under different optimization schemes are compared and analyzed, and the optimal welding optimization process is determined, specifically, backing welding adopts five-section type back welding, and cosmetic welding adopts two-section type centering symmetric welding. According to the optimization process, the welding residual stress and deformation are effectively reduced in a mode of finely regulating and controlling the welding sequence, so that the damage risk of the telescopic arm in the service period is reduced, the product quality is improved, and the expected life is prolonged. Powerful technical support and reference are provided for optimization of the welding process of the large telescopic arm structure, and a new thought is provided for upgrading and development of welding manufacturing of the large telescopic arm structure of related enterprises.

Description

Technical Field

[0001] The present invention relates to the technical field of large telescopic arm welding, and in particular to a welding optimization process based on numerical simulation technology suitable for reducing welding residual stress and deformation of a large telescopic arm structure. Background Art

[0002] Large telescopic booms (hereinafter referred to as telescopic booms) are important components of large equipment such as cranes, excavators, wind power equipment, and building tower cranes due to their good flexibility and adaptability. They are widely used in various engineering sites such as construction sites, port terminals, and road construction. In terms of the design and manufacturing of telescopic booms, there is still a certain gap between domestic products and foreign products. In order to improve independent design and production capabilities, reduce import dependence, and gain a certain market share and competitive advantage in global competition, domestic heavy machinery and equipment manufacturers need to continuously improve product quality and technical level, consolidate and enhance product competitiveness.

[0003] Welding is the most critical link in the manufacturing process of telescopic arms, and has the greatest impact on the performance and quality of the structure. Due to the characteristics of non-uniform rapid heating and cooling during the welding process and the structural characteristics of the telescopic arm's longitudinal seam length of more than ten meters, it is inevitable that large residual stress and post-weld deformation will be generated. Excessive welding deformation will result in poor appearance quality of the component, and dimensional parameters such as flatness and parallelism will exceed the design limit requirements, reducing the bearing capacity and service life. At the same time, deformation correction or repair will increase manufacturing costs and cycles. Therefore, reducing the welding residual stress and deformation of the telescopic arm is of great significance to improving the welding quality of the telescopic arm, reducing the probability of damage in the weld area, and increasing the service life of the telescopic arm.

[0004] If the traditional method of accumulating data through process tests is used to solve the problem of residual stress and deformation after welding, it will not only be difficult, costly and time-consuming. Therefore, the existing production and manufacturing of telescopic arms requires a technical means that can quickly and accurately realize the welding process design to achieve the quantitative calculation and visual analysis of the residual stress and deformation of the telescopic arm welding. Based on this technical means, the welding process optimization can be completed quickly and reliably, the residual stress and deformation of the telescopic arm welding can be reduced, thereby reducing the probability of damage to the telescopic arm during service. Ultimately, the quality and service life of the telescopic arm can be improved, and the digitalization level of the company's welding manufacturing, as well as the economic benefits and market competitiveness can be improved. Summary of the invention

[0005] In view of this, the present invention proposes a large telescopic arm structure welding optimization process based on numerical simulation technology. The process is designed based on the finite element method, and its purpose is to predict the post-welding residual stress and deformation of the components under different welding sequences to improve their welding quality and service life, and reduce the probability of damage in the weld area. It provides technical references for relevant practitioners to design and optimize the welding process of large telescopic arm structures, and provides new ideas for the upgrading and development of large telescopic arm structure welding manufacturing in related enterprises.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A large telescopic arm structure welding optimization process based on numerical simulation technology. It is characterized by the following steps:

[0008] S1: Design and carry out orthogonal test of double-layer double-pass MAG butt welding process for Q960E high-strength steel to obtain actual welding process parameters;

[0009] S2: Conduct finite element simulation of flat plate welding, establish a telescopic arm welding heat source model, and perform calibration and verification;

[0010] S3: According to the actual structure of the telescopic arm, a simplified geometric model is established and the finite element mesh is divided;

[0011] S4: The thermoelastic-plastic method is used to calculate the residual stress and deformation of the telescopic arm after welding under different base layer and cover layer welding processes, and the best process solution is obtained by comparison.

[0012] Preferably, the orthogonal test of the double-layer double-pass MAG butt welding process of Q960E high-strength steel is designed and carried out to obtain the actual welding process parameters. Specifically: the use of reasonable welding process parameters is a prerequisite for the weldment to obtain good weld formation and welding joint performance. For the telescopic arm structure, welding is the most critical link in the manufacturing process and has the greatest impact on the performance and quality of the structure. For the telescopic arm weld welded by metal active gas shielded welding (MAG), there are many main parameters that affect its welding process, including welding current, welding voltage, welding speed and welding process. The present invention first adopts the orthogonal experimental method to design different welding parameter factors and different parameter value levels, optimize the welding process parameters of the telescopic arm weld, and obtain a welding process parameter combination with better weld formation and joint performance, which is used for subsequent heat source model calibration and numerical simulation of the telescopic arm welding process.

[0013] Preferably, the flat plate welding finite element simulation is performed, the telescopic arm welding heat source model is established, and the calibration and verification are performed, specifically: first, based on the cross-sectional molten pool morphology of the weld joint under the optimal welding process parameter combination of the weld obtained from the welding process parameter optimization test of the telescopic arm weld, a welding heat source model with corresponding feature matching is selected. Further, according to the welding process parameter optimization test working conditions, the flat plate welding process finite element model of the weld is established respectively and the heat source model is applied to perform numerical simulation of the welding process. By comparing the cross-sectional molten pool morphology of the joint obtained by numerical simulation and experiment, the parameters of the heat source model are corrected. Then, the flat plate welding simulation temperature calculation results are verified by thermocouple temperature measurement test; the flat plate post-welding stress test is carried out by blind hole residual stress test method, and the accuracy of the flat plate welding simulation stress calculation results is verified; the modeling of the post-welding flat plate and reference plane is completed by laser scanning equipment, and its post-welding deformation is measured and the accuracy of the flat plate welding simulation deformation results is verified.

[0014] Preferably, according to the actual structure of the telescopic arm, a simplified telescopic arm model is established and a finite element mesh is divided, specifically: first, according to the actual structure of the telescopic arm, a scaled geometric model of the telescopic arm is established, and the geometric model is simplified and cleaned accordingly. On this basis, the simplified geometric model is meshed to establish a high-quality telescopic arm mesh model. Finally, according to the welding and constraint working conditions of the actual welding process of the telescopic arm, the initial conditions and boundary conditions of the finite element model of the telescopic arm welding process are set.

[0015] Preferably, the thermoelastic-plastic method is used to calculate the residual stress and deformation of the telescopic arm after welding under different base layer and cover layer welding processes, and the best process scheme is obtained by comparison, which is specifically as follows: first, the long straight longitudinal seam is divided into two to six sections, and the welding process planning of the telescopic arm base layer is carried out. There are a total of 7 welding process schemes: process 1 is a two-stage center-symmetrical welding process, process 2 is a two-stage back-welding process, process 3 is a three-stage back-welding process, process 4 is a four-stage center-back welding process, process 5 is a four-stage back-welding process, process 6 is a five-stage back-welding process, and process 7 is a six-stage center-back welding process. At the same time, the cover layer uniformly adopts a straight-through welding process. Furthermore, according to the results of different welding process schemes, the corresponding stress value and deformation value in the plate thickness direction are extracted along the center path of the weld, the peak stress value and deformation value in the plate thickness direction are extracted in the area with relatively uniform stress distribution, the deformation mean, standard deviation and peak value along the center of the weld are calculated, and the best base layer welding process is obtained by comprehensive comparison. Furthermore, based on the optimal base layer welding process, the cover layer welding process is optimized. There are two welding process schemes: process 1 is a two-stage center-symmetrical welding process, and process 2 is a five-stage back-welding process. The optimal cover layer welding process is obtained by comparison using the same method as above. Specifically: the optimal process is to use five-stage back-welding for base welding and two-stage center-symmetrical welding for cover welding.

[0016] Compared with the prior art, the present invention has the following positive effects: the large telescopic arm structure welding optimization process based on numerical simulation technology applied by the present invention can effectively reduce the welding residual stress and deformation of the telescopic arm, reduce the probability of damage to the telescopic arm at the weld, and thus improve the product quality and service life of the telescopic arm. At the same time, the present invention is designed based on the finite element method, which can not only reduce the process optimization cost and improve the welding quality, but also help the relevant staff to understand the physical essence of the welding process at a deeper level, and intuitively realize the control of the stress and deformation of the component welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Flow chart of a welding optimization process for large telescopic arm structure based on numerical simulation technology

[0018] Figure 2 MAG double-layer double-pass weld front and back morphology

[0019] Figure 3 Finite element model of plate and tooling

[0020] Figure 4 Schematic diagram of MAG welding heat source model calibration

[0021] Figure 5 Comparison of experimental and simulated thermal cycle curves: (a) base layer; (b) cover layer

[0022] Figure 6 Blind hole residual stress test sampling position

[0023] Figure 7 Comparison of experimental and simulated residual stress: (a) Path 1; (b) Path 2

[0024] Figure 8 Schematic diagram of deformation extraction: (a) scanning model; (b) simulation calculation model

[0025] Fig. 9 Comparison of calculated and measured deformation values ​​of flat plate after welding

[0026] Fig.10 Thermo-elastoplastic mesh model of telescopic arm: (a) overall view; (b) local view

[0027] Fig.11 Partial view of mesh model: (a) minimum mesh 1mm; (b) minimum mesh 2mm

[0028] Fig.12 Mechanical boundary conditions: (a) Support fixture, symmetry surface and support rib model; (b) Fixed node position

[0029] Fig.13 Optimization scheme for base layer welding process

[0030] Fig.14 Extraction path of weld front center stress and residual stress

[0031] Fig.15 Residual stress curves of each process of base layer: (a) stress at the center of weld; (b) peak stress at the back

[0032] Fig.16 Post-weld deformation extraction path

[0033] Fig.17 X-axis deformation curves after welding for different base layer processes (1-4): (a) deformation at the center of the weld; (b) mean value of peak deformation

[0034] Fig.18 X-axis deformation curves after welding for different base layer processes (5-7): (a) center deformation of weld; (b) mean value of peak deformation

[0035] Fig.19 Deformation of the weld center in each process of base layer

[0036] Fig. 20 Optimization scheme for cover layer welding process

[0037] Fig.21 X-axis deformation curves of the cover layer after welding in each process: (a) deformation at the center of the weld; (b) mean value of peak deformation

[0038] Fig. 22 Residual stress curves of each process of the cover layer: (a) stress at the center of the weld; (b) peak stress at the back

[0039] Fig.23 Center deformation of weld seams in each process of cover layer DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments.

[0041] The present invention is described below based on embodiments. Those skilled in the art should understand that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0042] Figure 1 The figure is a flow chart of a large telescopic arm structure welding optimization process based on numerical simulation technology according to the present invention.

[0043] Step S1: Design and carry out orthogonal test of Q960E high-strength steel double-layer double-pass MAG butt welding process to obtain actual welding process parameters. Specifically, the welding test uses Q960E high-strength steel with parent material specifications of (length × width × height) 200mm × 100mm × 5mm and 200mm × 100mm × 6mm, MAG welding is used for welding, and TRANS-30MAG welding power source is used. The nickel-based alloy welding wire with the grade of SNi6082 and the diameter of 1.2mm is selected, and its American standard grade is ERNiCr-3. The shielding gas is 80% Ar + 20% CO2 mixed gas. The gas flow rate of each group of tests is kept at 20L / min, and the dry extension of the welding wire is kept in the range of 10 to 12mm. The welding gun stays at the arc end of each weld for 0.5s. A gap of about 1.5mm is reserved at the arc starting end of welding, and a gap of about 2mm is reserved at the arc end to ensure the back of the base layer is formed. A T2 copper plate with the size of 220mm×220mm×4mm (length×width×height) is used as a pad to stabilize the arc and improve the welding quality. The test plate is fixed with a circular base fixture at the four corners of the test plate in a symmetrical form. The orthogonal welding experiment plan is shown in Table 1:

[0044] Table 1 Orthogonal test welding plan for flat plate welding

[0045]

[0046]

[0047] Further, after welding is completed, the following Figure 2 The weld shown in the figure was prepared with a metallographic sample of 25mm×15mm using a DK77 type electric spark wire cutting machine, and then the sample was ground and polished, and corroded with a 4% nitric acid alcohol solution. The macroscopic morphology of the joint section was observed and photographed using an industrial camera, and the weld excess height, upper and lower weld width and other dimensions were measured. The distribution of the organization in each area of ​​the joint and its fine morphology were observed under an optical microscope at different magnifications, and the influence of different organizations on the joint performance was analyzed. Finally, the optimal MAG double-layer double-pass welding process parameter window was obtained: the base layer welding current was 110~120A, the welding voltage was 17.5V, and the welding speed was 3.3~4.2mm / s; the cover layer welding current was 180~190A, the welding voltage was 22.5V, and the welding speed was 5.8~6.7mm / s.

[0048] Step S2: Perform finite element simulation of flat plate welding, establish a telescopic arm welding heat source model, and perform verification and validation. Figure 3As shown in the figure, according to the actual size of the welded test plate, the geometric model of the welded test plate is established at a ratio of 1:1. The mesh size of the welded joint area is the smallest. In the width direction, three transition mesh divisions are performed in sequence from the heat affected zone to the edge of the parent material at a ratio of 2:1; in the thickness direction, two transition mesh divisions are performed in a ratio of 2:1 and 3:1. The minimum mesh size is in the range of 0.8-1.2 mm, and the maximum mesh size is in the range of 7.9-8.2 mm. Both are eight-node hexahedral meshes. The entire plate finite element model contains a total of 22,850 meshes. Further, a rigid body model of the fixture base with a radius of 20 mm is established, and according to its actual clamping position, it is symmetrically arranged at 8 mm from the edge of the four corners of the plate. Further, a rigid body model of the liner plate of 220 mm × 220 mm × 4 mm is established, and a groove with a depth of 1 mm and a width of 5 mm is left in the middle according to the actual shape. The boundary conditions set are as follows: the convection heat transfer coefficient h is set to 20 W / (m 2 ℃); all contact heat transfer coefficients α are set to 1000W / (m 2 ℃); the radiation heat transfer coefficient ε is coupled to the convection heat transfer, and the coefficient is 0.6.

[0049] Furthermore, the initial values ​​of the double ellipsoid heat source model size are set, where the heat source half-width is set to 0.45 times the actual melt width, the heat source depth is set to 0.9 times the actual melt depth, the heat source front semi-axis length is 0.9 to 1.2 times the heat source half-width b, and the heat source rear semi-axis length is 2 times the heat source front semi-axis length. By adjusting the above parameters, the weld temperature field cloud map obtained by simulation calculation is consistent with the contour of the melting zone in the metallographic photograph, and then the telescopic arm welding finite element calculation is carried out. Figure 4 As shown in the figure, the metallographic specimen of the flat butt welding test and the contour of the melting zone of the finite element simulation temperature field are compared. The left side is the metallographic macroscopic morphology, and the right side is the corresponding cross-sectional peak temperature cloud map of the finite element simulation calculation result. Among them, the welding parameters are the base layer welding current of 110A, welding voltage of 17.5V, and welding speed of 3.3mm / s; the cover layer welding current of 180A, welding voltage of 22.5V, and welding speed of 5.8mm / s.

[0050] Furthermore, the simulation temperature calculation results of the flat plate welding were verified by thermocouple temperature measurement test. The thermal cycle curves of the near weld area during the welding process of the base layer and the cover layer were collected respectively, and the corresponding thermal cycle curves of the simulation calculation results were extracted, such as Figure 5 The average peak temperatures of the base weld obtained by measurement and simulation are 490.1 and 470.8°C, respectively, with an error of about 3.9%. The average peak temperatures of the cap weld obtained by measurement and simulation are 532.8 and 504.0°C, respectively, with an error of about 5.4%. The thermal cycle curves obtained by measurement and simulation have good consistency in trend.

[0051] Furthermore, the blind hole residual stress test method was used to test the post-weld stress of the flat plate, and the accuracy of the simulated stress calculation results of the flat plate welding was verified. The surface residual stress was measured at certain nodes along the weld and in the direction perpendicular to the weld of the test plate after welding, such as Figure 6 Then the residual stress curve on the corresponding path was extracted from the simulation results, as shown in Figure 7 The differences between the calculated and measured equivalent residual stresses at each node are 29.55MPa, 35.43MPa, 27.76MPa, 19.70MPa and 35.43MPa, respectively. Within the inherent error range, the stress calculation results of the constructed model can better reflect the distribution law and numerical level of residual stress after welding.

[0052] Furthermore, laser scanning equipment was used to complete the modeling of the plate and reference plane after welding, measure its deformation after welding, and verify the accuracy of the plate welding simulation deformation results. After adjusting the spatial coordinates of the scanning model and the calculation model to be consistent, six nodes N1 to N6 were selected at the corresponding positions, such as Figure 8 The X-axis deformation value of each node was extracted and calculated, as shown in Fig. 9 As shown, the deformation difference is between 0.12 and 0.24 mm, and the relative error is in the range of 8.39% to 16.1%, which proves that the deformation calculation results of the constructed model have a good confidence level of more than 80%.

[0053] Step S3: According to the actual structure of the telescopic arm, a simplified telescopic arm model is established and the finite element mesh is divided. Specifically, in order to facilitate the subsequent mesh division, necessary geometric cleaning is performed on the structures such as the bolt holes and mounting holes on the cover plate. The telescopic arm studied in this embodiment has a total length of 10515mm, a width of 640mm, and a height of 786mm. The upper and lower cover plates are welded together by two long straight longitudinal seams of the same length as the components. According to the performance requirements of the cover plates, the upper cover plate is designed to be 5mm thick and the lower cover plate is designed to be 6mm thick. Furthermore, in order to ensure the mesh accuracy of the weld and the heat-affected zone as much as possible and to control the overall number of meshes, the telescopic arm model is appropriately proportionally reduced. The scaled mesh model of the telescopic arm is 2080mm in length, 320mm in width, and 393mm in height. The mesh in the joint area is consistent with the flat plate finite element model. In order to simulate the fixed spot welding between the upper and lower cover plates in actual welding, the spot welding mesh length is proportionally set to 5mm and the spacing is 85mm according to the actual spot welding length and spacing. Fig.10 shown.

[0054] In order to further reduce the number of grids, the joint area grid is used as the basis, such as Fig.11As shown in the figure, a grid transition coarsening was performed in the parent material area far from the weld at a ratio of 2:1. The maximum grid size was in the range of 15.8mm to 16.4mm, and the number of grids was 489,580. Furthermore, the scaled rigid body models of the supporting ribs were established and set at the corresponding supporting positions. In order to ensure that the component model does not undergo overall displacement during the simulation calculation process, ten nodes with equal spacing were selected at the upper and lower edges of the component model to constrain its displacement in the X, Y, and Z directions, as shown in the figure. Fig.12 shown.

[0055] Step S4: Apply the thermoelastic-plastic method to calculate the residual stress and deformation of the telescopic arm after welding under different base layer and cover layer welding processes, and compare to obtain the best process solution. Fig.13 As shown in the figure, based on practical feasibility, the long straight longitudinal seam is divided into two to six sections to plan the welding process of the telescopic arm base layer. There are 7 welding process schemes in total: process 1 is a two-stage center-symmetrical welding process, process 2 is a two-stage back-welding process, process 3 is a three-stage back-welding process, process 4 is a four-stage center-symmetrical back-welding process, process 5 is a four-stage back-welding process, process 6 is a five-stage back-welding process, and process 7 is a six-stage center-symmetrical back-welding process; at the same time, the cover layer uniformly adopts a straight-through welding process from end A to end B.

[0056] Furthermore, according to the results of different welding process schemes, the corresponding stress values ​​and deformation values ​​in the plate thickness direction are extracted along the center path of the weld, the peak stress value and deformation value in the plate thickness direction are extracted in the area with relatively uniform stress distribution, and the deformation mean, standard deviation and peak value along the center of the weld are calculated, and the optimal process scheme is obtained by comprehensive comparison. Fig.14 A is the starting point. On the front of the component, the stress results are extracted along the center of the weld to the rightmost end of the weld. Fig.14 End at B. In the area with relatively uniform stress distribution, the residual stress results on the back of the weld are extracted according to the method path shown in the figure. The length between end a and end b of each path is 96mm, and the interval between them is 32mm. After extracting the residual stress from each path, the mean of the three data with the same Z coordinate is calculated to improve the uniformity and reliability of the extracted results. The results are plotted into corresponding curves, such as Fig.15 Specifically, the X-axis deformation component of the deformation peak area is extracted along the relevant paths. The specific extraction path is as follows: Fig.16 As shown in the figure, the length between the a end and the b end of each path is 96mm, and the intervals between them are 32mm and 8mm respectively. After extracting the post-weld deformation from each path, the average of the three data with the same Z coordinate is obtained to improve the uniformity and reliability of the extracted results. The relevant X-axis deformation values ​​are plotted into corresponding curves, as shown in Fig.17 , 18Furthermore, in order to more intuitively and comprehensively compare the overall level and uniformity of the post-welding deformation of each process of the base layer, the deformation mean, standard deviation and peak value of each process along the center of the weld are plotted into a bar graph, as shown in Fig.19 shown.

[0057] Furthermore, based on the optimal base layer welding process, the cover layer welding process is optimized. There are two welding process schemes: process 1 is a two-stage symmetrical welding process, and process 2 is a five-stage back-welding process. Fig. 20 The same method as above is used to obtain the residual stress curve of each process of the cover layer, the X-axial post-weld deformation curve of each process of the cover layer, and the central deformation bar graph of the weld of each process of the cover layer, which are respectively Fig.21 , Fig. 22 , Fig.23 shown.

[0058] Furthermore, the optimal process solution obtained by integrating the welding procedures of the base layer and the cover layer is to use five-stage back-welding for the base layer welding and two-stage center-symmetrical welding for the cover layer welding.

[0059] The results of the embodiment show that the present invention simulates and calculates the residual stress and deformation of the telescopic arm after welding by planning different welding sequence schemes, and obtains that the minimum welding deformation among the multiple welding process schemes is the five-stage back-welding of the base welding and the two-stage symmetrical welding of the cover welding, which can guide the actual production and has potential economic and social benefits. The present invention can also provide certain reference and reference for the welding production and manufacturing of similar welding structures.

[0060] The above description is only a part of the actual implementation cases of the present invention, and does not limit the present invention in any form. Any person familiar with the professional field, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiments still falls within the protection scope of the claims of the present invention.

Claims

1. A large telescopic arm structure welding optimization process based on numerical simulation technology, characterized in that: The steps are: S1: Design and carry out orthogonal test of double-layer double-pass MAG butt welding process for Q960E high-strength steel to obtain actual welding process parameters; S2: Conduct finite element simulation of flat plate welding, establish a telescopic arm welding heat source model, and perform calibration and verification; S3: According to the actual structure of the telescopic arm, a simplified geometric model is established and the finite element mesh is divided; S4: The thermoelastic-plastic method is used to calculate the residual stress and deformation of the telescopic arm after welding under different base layer and cover layer welding processes, and the best process solution is obtained by comparison.

2. According to claim 1, a large telescopic arm structure welding optimization process based on numerical simulation technology is characterized in that: Step S1 designs and carries out an orthogonal test of the double-layer double-pass MAG butt welding process of Q960E high-strength steel, and obtains the actual welding process parameters. The optimal MAG double-layer double-pass welding process parameter window is: the base layer welding current is 110-120A, the welding voltage is 17.5V, and the welding speed is 3.3-4.2mm / s; the cover layer welding current is 180-190A, the welding voltage is 22.5V, and the welding speed is 5.8-6.7mm / s; Step S2 performs a finite element simulation of flat plate welding, establishes a telescopic arm welding heat source model, and performs verification and validation; Step S3 establishes a simple structure according to the actual structure of the telescopic arm. The telescopic arm model is optimized and divided into finite element meshes, the finite element model and heat source model of the telescopic arm welding process are established, and the quantitative calculation of the telescopic arm welding process and the model reliability verification are completed. Based on the above model and method, the telescopic arm welding process optimization can be realized intuitively, quickly and accurately; Step S4 uses the thermoelastic-plastic method to calculate the residual stress and deformation of the telescopic arm after welding under different base layer and cover layer welding processes, and the best process scheme is obtained by comparison. The optimal process obtained by simulation is that the base welding adopts five-stage back-welding and the cover welding adopts two-stage center-symmetrical welding. This process is also suitable for the welding residual stress and deformation control of the same type of welded components.

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