CN115055784A - Electric water heater liner girth welding optimization process based on finite element method design - Google Patents
Electric water heater liner girth welding optimization process based on finite element method design Download PDFInfo
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Abstract
The invention discloses an electric water heater liner girth welding optimization process based on finite element method design. The process aims at the problems that the current inner container of the electric water heater is in leakage failure caused by welding residual stress and too high deformation of a welding seam area in the pulse pressure test and use processes, the optimization cost of the welding process is high, the efficiency is low, the reliability is poor, and the like. Numerical simulation and verification are carried out on the welding process of the liner based on a finite element method, quantitative calculation and comparative analysis are carried out on the welding stress field and deformation of the liner under different circular seam welding optimization process schemes, and finally the liner circular welding seam arc starting position welding optimization process for controlling liner welding residual stress and deformation to be optimal is obtained, namely circular welding seams on two sides of the liner arc at a position which is 270 degrees (left end) clockwise from a longitudinal welding seam on a welding path of the liner, and clockwise synchronous welding is carried out. The process can effectively reduce the welding residual stress and deformation of the inner container, thereby reducing the probability of leakage and damage of the inner container at the welding seam, improving the product quality of the inner container and prolonging the service life of the inner container. The invention can provide a new idea for improving the quality and service life of the inner container of the electric water heater in the industry and optimizing the design of the welding process.
Description
Technical Field
The invention relates to the field of manufacturing of inner containers of electric water heaters, in particular to a girth welding optimization process which is designed based on a finite element method and is suitable for reducing the welding residual stress and deformation of the inner containers of the electric water heaters.
Background
The improvement of living standard and the acceleration of living rhythm promote the rapid increase of the demand of people for electric water heaters. In recent years, the sales and occupancy of electric water heaters in China are increasing, and the water storage type electric water heaters occupy the main market. The inner container is a core part of the water storage type electric water heater, and welding is a key manufacturing process of the inner container. In the production and manufacturing process of the inner container, the welding quality directly determines the service life, so that the economic benefit and the market competitiveness of an enterprise are greatly influenced.
At present, the liner of the water storage type electric water heater still has certain problems in the manufacturing and service processes. On one hand, in the welding manufacturing process of the inner container, welding defects such as welding through, hump welding bead and discontinuous welding bead still occur at certain probability in a longitudinal welding seam and circumferential welding seams at two sides of the cylinder body. In general, this is caused by unreasonable welding parameter settings, which can be improved by repeatedly adjusting parameters, and finally a welding parameter combination with good weld formation can be obtained. On the other hand, after the welding of the inner container is finished, in the pulse pressure testing process, the longitudinal welding seam and the circumferential welding seam of the inner container are easy to leak and finally damaged, and the pulse pressure testing result cannot meet the welding quality requirements of enterprises. In the actual use process of the liner, leakage failure often occurs at the longitudinal welding line and the circumferential welding line, and the service life is not reached. One of the main causes of leakage or failure is the residual stress and deformation of the solder.
Because the longitudinal welding seam and the circumferential welding seam of the inner container are longer, the heat input in the whole welding process is higher, the welding residual stress of the welding seam area is higher, and the welding deformation is larger. The superposition of the working stress and the welding residual stress generates higher tensile stress in a welding seam area, which is easy to induce the phenomena of damage accumulation such as microcrack, accelerated fatigue, stress corrosion cracking and the like, thereby leading the liner to leak and fail in advance. Meanwhile, the discontinuity of the geometric structure is brought by the overlarge deformation amount, so that the stress concentration is more easily caused, and the bearing capacity of the structure is reduced. Therefore, the reduction of the welding residual stress and the deformation of the inner container has important significance for improving the welding quality of the inner container and reducing the probability of leakage in a welding seam area so as to prolong the service life of the inner container.
In fact, the welding residual stress and deformation are usually difficult to measure due to the high technical difficulty and the high test cost, so that the optimization work of the welding residual stress and the deformation of the liner is difficult to carry out. Therefore, the existing liner production needs a technical means which can quickly and accurately realize the welding process design to realize the quantitative calculation and the visual analysis of the liner welding residual stress and deformation. Based on the technical means, the welding process can be quickly and reliably optimized, and the welding residual stress and deformation of the liner are reduced, so that the probability of leakage and damage of the liner in the service process is reduced. Finally, the quality and the service life of the inner container are improved, and the welding and manufacturing digitization level, the economic benefit and the market competitiveness of enterprises are improved.
Disclosure of Invention
In view of this, the invention provides a welding optimization process suitable for reducing the welding residual stress and deformation of an inner container of an electric water heater, which is designed based on a finite element method and aims to reduce the welding residual stress and deformation of the inner container of the electric water heater, improve the welding quality and service life of the inner container, and reduce the probability of leakage or damage of a welding seam area in the service process of the inner container. The welding process provides technical reference for designing and optimizing the structure welding process for related practitioners, and provides a new idea for the welding, manufacturing, upgrading and developing of the inner container of the electric water heater of related enterprises.
The specific technical scheme of the invention is as follows:
an electric water heater liner girth welding optimization process based on finite element method design. The method is characterized by comprising the following steps:
s1: the electric water heater liner longitudinal weld and circumferential weld welding process parameter optimization test design and test data acquisition.
S2: establishing and checking a heat source model in the welding process of longitudinal welding seams and circumferential welding seams of the inner container of the electric water heater.
S3: finite element modeling is carried out on the welding process of longitudinal welding seams and circumferential welding seams of the inner container of the electric water heater.
S4: numerical simulation and circumferential weld joint welding optimization process acquisition in the welding process of the inner container of the electric water heater.
S5: the actual production line of the optimization scheme of the circumferential weld joint welding process of the inner container of the electric water heater is verified.
Preferentially, the parameters of the welding process of the longitudinal welding line and the circumferential welding line of the inner container of the electric water heater optimize the test design and the test data acquisition. The method specifically comprises the following steps: the reasonable welding technological parameters are adopted on the premise that the weldment obtains good weld forming and welding joint performance. For the inner container structure of the electric water heater, a longitudinal welding seam on the cylinder body and a circumferential welding seam formed by two ends of the cylinder body and the end cover are key welding seams for connecting the inner container into a complete structure. For a longitudinal welding seam of Plasma Arc Welding (PAW) and a circumferential welding seam of consumable electrode active gas shielded welding (MAG), the main parameters influencing the welding process are more, including welding current, welding voltage, welding speed and the like. The invention firstly adopts an orthogonal test method, designs different welding parameter factors and different parameter value levels, respectively optimizes the welding process parameters of the longitudinal welding line and the circumferential welding line of the liner, obtains the welding process parameter combination with better welding line forming and joint performance, and is used for subsequent heat source model checking, liner welding process numerical simulation and actual production line verification.
Preferentially, the heat source model of the welding process of the longitudinal welding line and the circumferential welding line of the inner container of the electric water heater is established and checked. The method specifically comprises the following steps: firstly, based on the weld joint cross section molten pool appearance under the better welding process parameter combination of the longitudinal weld and the circumferential weld obtained by the liner longitudinal weld and circumferential weld welding process parameter optimization test, a welding heat source model with corresponding characteristic matching is selected. Further, test working condition conditions are optimized according to welding process parameters, a finite element model of a test piece part-level welding process of a longitudinal welding line and a circumferential welding line is respectively established, and a heat source model is applied to carry out numerical simulation of the welding process. And correcting the heat source model parameters by comparing the appearance of the joint section molten pool obtained by numerical simulation and experiments. And finally, verifying the accuracy of the heat source model parameters and the reliability of the finite element modeling process by comparing the corresponding position welding thermal cycle temperature curves obtained by numerical simulation and test.
Preferentially, finite element modeling is carried out on the welding process of the longitudinal welding seam and the circumferential welding seam of the inner container of the electric water heater. The method specifically comprises the following steps: firstly, according to the actual structure of the welded inner container, a 1: 1 complete geometric model of the inner container is established, and the geometric model is simplified and cleaned correspondingly. On the basis, the simplified geometric model is subjected to grid division, and a high-quality liner grid model is established. Further, an enamel steel material model for the liner is established, and nonlinear parameter changes of parameters such as density, specific heat capacity, thermal conductivity, thermal expansion coefficient, Young modulus, yield strength and Poisson ratio in a certain temperature range are mainly included. And finally, setting initial conditions and boundary conditions of the finite element model in the liner welding process according to the actual welding and constraint working conditions of the liner.
Preferentially, the numerical simulation and the circumferential weld joint welding optimization process of the liner of the electric water heater are obtained. The method specifically comprises the following steps: based on the structural characteristics of the inner container and the operability of actual production, circumferential weld seam welding process schemes of different inner containers are designed. And (4) performing quantitative calculation and analysis on the liner welding temperature field, the stress field and the deformation under different schemes by adopting the better longitudinal welding seam and circumferential welding seam welding process parameter sets obtained in the welding process parameter optimization test in the S1 and applying the checked heat source model. The liner circumferential weld joint welding process for controlling liner welding residual stress and deformation to be optimal is obtained by comparing liner welding residual stress and deformation under different schemes, and specifically comprises the following steps: the circumferential welding seams at the two sides are arc-started at a position which is 270 degrees (left end) clockwise from the longitudinal welding seam on the welding path, and the welding is synchronously performed clockwise.
Preferentially, the actual production line of the circular weld joint welding process optimization scheme of the inner container of the electric water heater is verified. The method specifically comprises the following steps: in an actual liner production line, firstly, the superior longitudinal weld seam welding process parameters obtained by the welding process test in S1 are adopted to complete the longitudinal weld seam welding of the cylinder body. Further, the liner circumferential weld seam welding optimization process obtained in the step S4 is adopted to perform circumferential weld seam welding on two sides, namely the circumferential weld seams on the two sides arc at a position which is 270 degrees (left end) clockwise from the longitudinal weld seam on the welding path of the circumferential weld seams on the two sides, and clockwise synchronous welding is performed. And selecting the welding parameters from the better circumferential weld welding process parameters obtained by the welding process test in the S1. And finishing the residual manufacturing process of the inner container on the basis. And finally, carrying out air tightness test and pulse pressure test on the inner container, and verifying the reliability of the circumferential weld seam welding optimization process scheme of the inner container of the electric water heater provided by the invention.
Compared with the prior art, the invention has the following positive effects: the electric water heater liner girth welding optimization process based on the finite element method can effectively reduce the welding residual stress and deformation of the electric water heater liner, reduce the probability of leakage and damage of the liner at the welding seam, and further improve the product quality and the service life of the liner. Meanwhile, the invention is designed based on the finite element method, thereby not only reducing the process optimization cost and improving the welding quality, but also being helpful for related workers to understand the physical essence of the welding process more deeply and intuitively realize the control of the stress and the deformation of the member in the welding process.
Drawings
FIG. 1 is a schematic view of an optimized process for circumferential weld arc striking position of an inner container of an electric water heater;
FIG. 2 is a macroscopic view of a weld joint in an optimization test of parameters of a longitudinal weld joint welding process of an inner container of an electric water heater;
FIG. 3 is a macroscopic view of weld joint in an optimization test of circumferential weld joint welding process parameters of an inner container of an electric water heater;
FIG. 4 is a cross-sectional profile comparison diagram of a weld joint obtained from simulation and test of a longitudinal weld joint welding process of an inner container of an electric water heater;
FIG. 5 is a cross-sectional profile comparison diagram of a weld joint obtained from simulation and test of the circumferential weld joint welding process of the liner of the electric water heater;
FIG. 6 is a comparison graph of welding heat cycle curves of sampling points obtained by simulation and test of the welding process of longitudinal and circumferential weld seams of an inner container of an electric water heater: (a) longitudinal weld seam (b) circumferential weld seam;
FIG. 7 is a three-dimensional geometric model structure diagram of an inner container of an electric water heater: (a) simplifying the geometric model of the inner container by the complete geometric model of the inner container;
FIG. 8 is a diagram of a grid model of an inner container of an electric water heater;
FIG. 9 is a schematic diagram of an optimized circumferential weld seam welding process for an inner container of an electric water heater: (a) scheme 1 (b) scheme 2 (c) scheme 3 (d) scheme 4;
FIG. 10 is a cloud diagram of welding residual stress of an inner container of an electric water heater under four kinds of circumferential weld seam welding optimization process schemes;
FIG. 11 is a comparison graph of welding residual stress on the center line of the outer surface of the longitudinal weld of the liner of the electric water heater under four optimized circumferential weld welding processes;
FIG. 12 is a comparison graph of welding residual stress on the center line of the circumferential weld outer surface of the liner of the electric water heater under four kinds of circumferential weld welding optimization process schemes;
FIG. 13 is a cloud view of the welding deformation of the lower liner in the four circumferential weld joint welding optimization process schemes;
FIG. 14 is a schematic diagram of a straight deformation analysis path of a welded cylinder of an inner container of an electric water heater;
FIG. 15 is a comparison graph of the deformation results of the welded cylinder body of the inner container of the electric water heater;
FIG. 16 is a schematic diagram of a roundness deformation analysis path of a welded cylinder body of an inner container of an electric water heater;
FIG. 17 is a comparison graph of roundness deformation results of welded cylinder bodies of inner containers of electric water heaters;
FIG. 18 is a schematic view of an actual production line circumferential weld arc striking position of an electric water heater liner;
FIG. 19 is a schematic view of an actual production line circumferential weld arc starting position welding optimization process of an electric water heater inner container;
FIG. 20 is a schematic view of liner welding in an optimized circumferential weld seam arcing position welding process;
FIG. 21 is a schematic view of a liner pulse pressure test in an optimized circumferential weld seam arcing position welding process;
Detailed Description
The present invention is further illustrated by the following specific examples.
The present invention is described below based on embodiments, and it will be understood by those of ordinary skill in the art that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.
Step 1: an electric water heater liner girth welding optimization process based on finite element method design is shown in figure 1. Firstly, selecting an enamel steel inner container of the water storage type 601 electric water heater as an object, developing a welding process parameter optimization test and acquiring test data. The method is characterized in that plasma air flow, welding current and welding speed are selected as main factors aiming at the longitudinal welding line of the liner, and an orthogonal process test scheme is designed based on a process parameter window of an actual welding production line of the longitudinal welding line of the liner, and is shown in table 1. Argon with the purity of 99.9% is selected as the protective gas and the ion gas, wherein the flow of the protective gas is 15L/min, and the flow of the plasma gas is a variable of a test factor. Aiming at the circumferential weld joint of the liner, the welding current, the welding voltage and the welding speed are selected as main factors, and an orthogonal process test scheme is designed based on a process parameter window of an actual welding production line of the circumferential weld joint of the liner, as shown in table 2. The protective gas is selected from Ar 80% + CO 220%, and the gas flow is 15L/min.
TABLE 1 orthogonal test protocol for longitudinal weld PAW butt welding
TABLE 2 MAG Lap weld orthogonal test scheme for circumferential weld
Further, the macro-topography of the longitudinal weld seam and the circumferential weld seam obtained by the welding process parameter optimization test are respectively shown in fig. 2 and fig. 3. Tensile strength and microhardness values are shown in table 3 and table 4, respectively.
TABLE 3 test results of mechanical properties of longitudinal weld PAW butt welding
TABLE 4 test results of MAG lap welding mechanical properties of circumferential weld
Through comprehensive comparative analysis of the weld forming and joint performance of the longitudinal weld and the circumferential weld obtained by the welding process test, the superior welding process parameter combination of the longitudinal weld and the circumferential weld is obtained, as shown in tables 5 and 6. The parameter combination is used for numerical simulation and welding process test in the subsequent welding process.
TABLE 5 longitudinal weld PAW Butt welding preferred welding process parameter combinations
TABLE 6 preferred welding process parameter combinations for circumferential MAG lap welding
And 2, step: and selecting a double-ellipsoid heat source model to carry out numerical simulation on the inner container welding process according to the appearance of a joint cross section molten pool under the combination of longitudinal welding seams and circumferential welding process parameters obtained by the welding process test. Establishing a finite element model of the welding process of the test piece, and correcting the parameters of the heat source model by comparing the cross-section molten pool profile obtained by test and simulation, as shown in figures 4 and 5. Further, a K-type thermocouple is adopted to measure a thermal cycle curve of the welding process of the test piece, corresponding point welding thermal cycle temperature curves in the numerical simulation result are extracted for comparison, and as shown in fig. 6, heat source model parameters are verified. Therefore, the consistency of the weld section molten pool profile calculated by the heat source model after checking and the appearance of the joint molten pool obtained by the test is better. The temperature curve of the warm-heat circulation of the test measuring point is consistent with the change trend of the calculation result of the finite element temperature field of the corresponding node. The reliability of the finite element modeling process and the accuracy of the selection and check of the welding heat source model are verified.
And step 3: according to the actual inner container structure, an inner container 1: 1 geometric model is established, and the geometric model is cleaned and simplified, as shown in fig. 7. Further, the simplified geometric model is subjected to mesh division, and an inner container mesh model is established, as shown in fig. 8. For the material DC01EK for the enamel steel liner of the water storage type 601 electric water heater, a material model parameter model of the material DC in a certain temperature interval is established by adopting the modes of reasonable extrapolation, software calculation and the like based on the material components and properties, as shown in Table 7.
TABLE 7 model of parameters of DC01EK steel material for enamel
Further, setting initial conditions and boundary conditions of the finite element model according to working conditions of the actual welding process of the liner, setting the initial temperature to be 25 ℃ at room temperature, and loading the welding heat input load through the heat source model. In the longitudinal welding seam welding process, the degree of freedom of the cylinder body corresponding to the tool constraint area is set to be 0, and in the circumferential welding seam welding process, the degree of freedom of the end covers on the two sides corresponding to the tool constraint area is set to be 0.
And 4, step 4: based on the structural characteristics of the liner and the operability of actual production, four different liner circumferential weld seam welding process schemes are designed, as shown in fig. 9. After the longitudinal welding seam of the cylinder body is welded, the cylinder body is assembled with the end covers on the two sides, and the circumferential welding seams on the two sides are synchronously welded. Setting longitudinal welding seams to be positioned at the top of the liner, wherein in the scheme 1, the circumferential welding seams at two sides arc at a position which is 0 degrees (top end) clockwise away from the longitudinal welding seams on the welding path of the circumferential welding seams, and welding clockwise; in the scheme 2, the circumferential welding seams at two sides arc at the position 90 degrees (right end) clockwise from the longitudinal seam on the welding path, and are welded clockwise; in the scheme 3, the circumferential welding seams at two sides arc at the position 180 degrees (bottom end) clockwise away from the longitudinal seam on the welding path, and are welded clockwise; scheme 4 is that the circumferential welding seams at two sides are arc-started at a position which is 270 degrees (left end) clockwise from the longitudinal seam on the welding path, and the welding is carried out clockwise.
Further, in the finite element model of the inner container welding process, four process schemes are set, and the temperature field, the stress field and the deformation of the inner container welding process under different processes are quantitatively calculated and analyzed. Firstly, a cloud chart of welding residual stress of the liner under four schemes is extracted, as shown in fig. 10. It can be seen that when the circular seam clamp is released and cooled to the room temperature state, the distribution law of the welding residual stress of the inner liner under the four schemes is similar. Further, residual stress values on the centers of the outer surfaces of the longitudinal welding seams of the lower liner in the four schemes are extracted, as shown in fig. 11. It can be clearly seen that the residual stress values under the four schemes are different on the center line of the outer surface of the longitudinal weld joint. The peak stress of the case 3 was the highest and was 197.7MPa, and the peak stress of the case 4 was the lowest and was 170.3MPa, which was 13.85% lower than the former. The residual stress mean values under the four schemes are 129.81MPa, 114.20MPa, 130.05MPa and 104.08MPa respectively, and the mean residual stress of the scheme 4 is reduced by 19.82 percent, 8.86 percent and 19.96 percent respectively compared with the former three. Therefore, compared with other schemes, the scheme 4 can effectively reduce the welding residual stress of the longitudinal welding line of the liner. Further, residual stress values on the centers of the circumferential weld joint outer surfaces of the inner liners under the four schemes are extracted, as shown in fig. 12. Obviously, on the center line of the outer surface of the circumferential weld joint, the residual stress values under the four schemes also have difference. The peak stress of the case 3 was 184.63MPa, and the peak stress of the case 4 was 151.94MPa, which was a 17.71% decrease. The residual stress averages of the four schemes are 151.44MPa, 135.73MPa, 151.03MPa and 135.30MPa respectively, and the average residual stress of the scheme 4 is reduced by 10.66 percent, 8.86 percent and 10.42 percent respectively compared with the scheme 1 and the scheme 3. Therefore, compared with other schemes, the scheme 4 can effectively reduce the welding residual stress of the circumferential welding line of the liner.
Further, a cloud picture of welding deformation of the inner container under the four schemes is extracted, and is shown in figure 13. Under the four schemes, the maximum deformation of the inner container is positioned in the middle area of the longitudinal seam, and the peak deformation amounts are respectively 1.001mm, 0.900mm, 1.025mm and 0.897 mm. The peak deformation amount of case 4 was reduced by 10.38% and 12.49% compared to cases 1 and 3, respectively. Further, by extracting displacement data of nodes on different paths, the overall roundness deformation and the overall straightness deformation of the cylinder under the four schemes are analyzed, and the advantages and disadvantages of the four schemes in the aspect of controlling the welding deformation of the liner are comprehensively compared. The straight path of the outer surface of the cylinder is taken at intervals of 30 degrees along the circumferential direction of the cylinder body, and the total number of the straight paths is 12, as shown in figure 14. The predetermined linearity deviation is an absolute value of a difference between a maximum value (max) and a minimum value (min) of deformation displacement of a node along the direction of the radius R of the cylinder on the same path, and the comparison result is shown in fig. 15. It can be seen that there is a significant difference between the mean value of straightness errors of all paths in the four schemes, and the mean value of straightness errors in the schemes 4 and 2 is equivalent and significantly smaller than those in the schemes 1 and 3, which shows that the schemes 4 and 2 are better in controlling barrel straightness deformation. Further, 12 circumferential paths were taken along the longitudinal seam welding direction on the outer surface of the cylinder, as shown in fig. 16. And respectively extracting node displacement data on the paths, wherein the roundness error is the average value of the deformed nodes along the radial displacement on the same circumferential path. The comparative results are shown in FIG. 17. The error level of the integral roundness of the cylinder body in the scheme 4 is the lowest in the four schemes, and the average value is the smallest, which shows that the error level is the best in the aspect of controlling the roundness deformation of the cylinder body. The cylinder body straightness deformation result is combined, and in the aspect of controlling the cylinder body straightness and roundness welding deformation, the scheme 4 is the optimal scheme of the four schemes.
Further, the liner welding residual stress and deformation simulation results under the four schemes are comprehensively compared, the overall welding residual stress and deformation of the scheme 4 are the lowest of the four schemes, the scheme is an optimal circular seam arc starting welding process for controlling the liner welding residual stress and deformation, namely after the longitudinal welding seam of the cylinder body is welded, the cylinder body is assembled with the end covers at the two sides, the circular welding seams at the two sides arc at a position which is 270 degrees (left end) clockwise from the longitudinal welding seam on the welding path of the circular welding seams, and the circular welding seams are synchronously welded clockwise, as shown in fig. 1.
And 5: in the actual production line of the liner of the electric water heater, the optimal circumferential weld seam arcing position welding process provided by the invention is verified, and circumferential weld seams on two sides arc at a position (left end) which is 270 degrees clockwise away from a longitudinal seam on a welding path, and are synchronously welded clockwise. The actual production line is tracked, so that the circumferential welding seam welding procedure of the liner of the electric water heater in the current enterprise does not make a welding process specification, and the arcing position of the circumferential welding seam is disordered, as shown in fig. 18. Further, according to the optimum circumferential weld arc striking position proposed by the present patent, as shown in fig. 1 and 19, the arc striking position of the circumferential weld is set. And welding process parameters of superior longitudinal welding seams and circumferential welding seams obtained by a welding process test are adopted to weld a certain number of inner containers for air tightness test and pulse pressure test, as shown in figure 20. The welded liners were all subjected to the airtightness test, and then four liners were randomly selected among all the liners to be subjected to the pulse pressure test, as shown in fig. 21. Test results show that the test results of the four inner containers all reach more than 10 ten thousand pulse times, the sampling inspection qualified rate reaches 100%, the welding quality requirements of enterprises are met, and the effectiveness and the reliability of the welding optimization process of the inner container of the electric water heater designed based on the finite element method are verified.
The result analysis of the embodiment shows that the electric water heater liner girth welding optimization process designed based on the finite element method can realize quantitative calculation and analysis of a temperature field, a stress field and deformation of the electric water heater liner in the welding process based on the finite element method. Compared with the traditional welding process optimization method based on the welding test, the method has the advantages of low cost, good visualization, high reliability, high efficiency and the like. On the basis, the welding process for the optimal arc striking position of the circumferential weld joint can effectively reduce the weld joint area and the integral welding residual stress of the liner, simultaneously reduce the straightness and roundness deformation of the welded liner, and is favorable for reducing the risk of leakage and damage of the weld joint area of the liner in the service process. The invention provides an important technical application reference for promoting the wide application of the finite element method and the numerical simulation technology in the fields of water heater inner containers and even household appliance manufacturing. For related manufacturing enterprises, the optimization process for welding the circumferential welding seam arcing position of the inner container of the electric water heater, provided by the invention, can effectively reduce the welding residual stress and deformation of the inner container, improve the welding quality of the inner container and prolong the service life of the inner container, and has certain guiding significance and economic value. The invention can also provide certain reference and reference for welding production and manufacture of similar welding structures.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. An electric water heater liner girth welding optimization process based on finite element method design is characterized by comprising the following steps:
s1: the electric water heater liner longitudinal weld and circumferential weld welding process parameter optimization test design and test data acquisition.
S2: establishing and checking a heat source model in the welding process of longitudinal welding seams and circumferential welding seams of the inner container of the electric water heater.
S3: finite element modeling is carried out on the welding process of longitudinal welding seams and circumferential welding seams of the inner container of the electric water heater.
S4: numerical simulation and circumferential weld joint welding optimization process acquisition in the welding process of the inner container of the electric water heater.
S5: the actual production line of the optimization scheme of the circumferential weld joint welding process of the inner container of the electric water heater is verified.
2. The electric water heater liner girth welding optimization process designed based on the finite element method as claimed in claim 1, is characterized in that: in the step S1 electric water heater liner longitudinal weld joint and circumferential weld joint welding process parameter optimization test design and test data acquisition, the obtained excellent welding process parameter composition of the PAW longitudinal weld joint is as follows: the plasma flow is 1.5L/min, the welding current is 205A, and the welding speed is 10 mm/s; the optimal welding process parameters of the MAG circumferential weld are as follows: welding current 190A, welding voltage 31V and welding speed 23 mm/s.
3. The electric water heater liner girth welding optimization process designed based on the finite element method as claimed in claim 1, is characterized in that: the method comprises the steps of S2 building and checking a heat source model in the welding process of the longitudinal weld and the circumferential weld of the inner container of the electric water heater, S3 building a finite element model in the welding process of the longitudinal weld and the circumferential weld of the inner container of the electric water heater, and S4 obtaining a numerical simulation and a circumferential weld welding optimization process in the welding process of the inner container of the electric water heater, wherein the finite element model and the heat source model in the welding process of the inner container of the electric water heater are built, quantitative calculation and model reliability verification in the welding process of the inner container of the electric water heater are completed, and the optimization of the welding process of the inner container of the electric water heater can be intuitively, quickly and accurately realized based on the model and the method.
4. The electric water heater liner girth welding optimization process based on finite element method design as claimed in claim 1, characterized in that: in the steps of S4 electric water heater liner welding process numerical simulation and circumferential weld seam welding optimization process acquisition and S5 electric water heater liner circumferential weld seam welding process optimization scheme actual production line verification, the optimal circumferential weld seam welding process for reducing electric water heater liner welding residual stress and deformation obtained by simulation and actual verification is as follows: the circumferential welding seams at two sides are arc-started at a position which is 270 degrees clockwise (left end) away from the longitudinal welding seam on the welding path, and the welding is clockwise and synchronously performed, and the process is also suitable for controlling the welding residual stress and deformation of welding members of the same type (longitudinal welding seam-circumferential welding seams at two sides).
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