Automatic welding method, equipment and system for fixed tube plate type heat exchanger

Abstract

The invention relates to the technical field of automatic welding of heat exchangers, in particular to an automatic welding method, device and system for a fixed tube plate type heat exchanger, and the method comprises the steps that current and voltage data in all welding processes are obtained; dividing the current data of each welding process into a plurality of peak value and base value current data segments, and obtaining a distortion abnormal value of each current data segment; acquiring a current pulse abnormal value in a single welding process; the current fluctuation degree of the current rising stage and the current falling stage of the single welding process is obtained; obtaining an abnormal factor of a single welding process; acquiring a current abnormal coefficient in the current welding process; and the welding influence coefficient of the current welding process is obtained and used for regulating and controlling the proportional parameters during PID control in the next welding process. Therefore, the welding quality of the fixed tube plate type heat exchanger is improved, and the welding effect in different welding processes is more stable.

Description

Technical Field

[0001] The present application relates to the technical field of automatic welding of heat exchangers, and in particular to an automatic welding method, equipment and system for a fixed tube plate heat exchanger. Background Art

[0002] Fixed tube sheet heat exchanger is a heat exchange equipment widely used in the industrial field. Its main structure includes shell, tube sheet, tube bundle, top cover and other parts. The two ends of the tube bundle are fixed to the tube sheet by welding or expansion, and the tube sheet is welded to the shell to form an integral structure. It has the advantages of simple structure, low cost, high heat transfer efficiency, etc., and is suitable for a variety of heat exchange process scenarios. For the welding of fixed tube sheet heat exchangers, due to the large number of tube sheet joints, small tube diameter and narrow arrangement spacing of the heat exchanger, an efficient and stable automatic welding method is urgently needed.

[0003] Publication No. CN113369730A is an automatic welding process for heat exchanger tube sheets. The tube sheets and limit blocks are made of the same material. A tube sheet welder is used to test weld the joints between the heat exchange tubes and the limit blocks. After the test welding is completed, the parameters of the tube sheet welder are adjusted for final welding. This patent fails to take into account that the instability of the internal components of the welding machine power supply during the welding process will lead to unstable output current, thereby affecting the welding quality. In addition, the asynchronous change between the output voltage and output current of the welding machine will further reduce the welding quality. In the automatic welding process, the output current is usually regulated by preset fixed PID control parameters based on the welding material and the required welding effect. The influence of the above factors on the welding quality is not considered, resulting in unstable welding effects and poor welding quality in different welding processes. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide an automatic welding method, equipment and system for a fixed tube-sheet heat exchanger. The technical solutions adopted are as follows: In a first aspect, an embodiment of the present application provides an automatic welding method for a fixed tube sheet heat exchanger, the method comprising the following steps: Obtain current and voltage data during each welding process; The current data of each welding process is divided into peak value and base value current data segments according to the peak value state and base value state of the pulse. The distortion abnormal value of each current data segment is obtained according to the minimum distance between the current data of each current data segment and the corresponding fitting curve, and the difference between each abnormal point and the left and right adjacent data in each current data segment; the current pulse abnormal value of a single welding process is obtained according to the average level and discrete degree of all the distortion abnormal values ​​in a single welding process; According to the degree of dispersion of the current mean value of each peak current data segment in the current rising stage and the current falling stage of a single welding process, the current fluctuation degree in the current rising stage and the current falling stage of a single welding process is obtained respectively; and combined with the difference in the current change speed in the current rising and falling stages of a single welding process, the abnormal factor of a single welding process is obtained; According to the abnormal current pulse value and abnormal factor of the current welding process, the abnormal current coefficient of the current welding process is obtained; the welding influence coefficient of the current welding process is obtained, and the calculation formula is: ; In the formula, is the welding influence coefficient of the i-th welding process, is the current abnormal coefficient of the i-th welding process, is the consistency coefficient of the i-th welding process, exp( ) represents an exponential function with the natural constant e as the base; wherein, the consistency coefficient of the current welding process is the Spearman correlation coefficient between all current values ​​and all voltage values ​​in the current welding process; the proportional term parameters of the PID algorithm in the next welding process are adjusted, and then the output current of the next welding process is adjusted.

[0005] Preferably, the process of obtaining the abnormal distortion value of each current data segment is as follows: Obtaining a fitting curve for each current data segment; calculating the minimum distance between each data point and the corresponding fitting curve, and taking the average of all the distances for each current data segment as the waveform deviation coefficient of each current data segment; Obtain the abnormal points of each current data segment, calculate the absolute value of the difference between each abnormal point and its two adjacent data on the left and right, and take the average of all the absolute values ​​in each current data segment as the mutation significance coefficient of each current data segment; The product of the waveform deviation coefficient and the mutation significance coefficient of each current data segment is taken as the distortion abnormal value of each current data segment.

[0006] Preferably, the current pulse abnormal value of the single welding process is the product of the mean and standard deviation of the distortion abnormal values ​​of all current data segments in the single welding process.

[0007] Preferably, the process of obtaining the current fluctuation degree in the current rising stage and the current falling stage of the single welding process is: Calculate the current mean value of each peak current data segment in the current rising stage and the current falling stage respectively; Obtaining fitted straight lines of all mean values ​​in the current rising phase and all mean values ​​in the current falling phase respectively, and calculating the shortest distance between each current mean value and the corresponding fitted straight line respectively; The cumulative sum of all the shortest distances in the current rising stage of a single welding process is used as the current fluctuation degree of the current rising stage of the corresponding single welding process, and the cumulative sum of all the shortest distances in the current falling stage of the single welding process is used as the current fluctuation degree of the current falling stage of the corresponding single welding process.

[0008] Preferably, the calculation process of the abnormal factor of the single welding process is: ; In the formula, represents the abnormal factor of the ith welding process, represents the mean value of the current fluctuation during the current rising stage and the current falling stage in the i-th welding process, It represents the sum of the corresponding slopes of the fitting straight lines of the current mean values ​​in the current rising stage and the current falling stage during the i-th welding process.

[0009] Preferably, the current anomaly coefficient of the current welding process is the product of the current pulse anomaly value and the anomaly factor of the current welding process.

[0010] Preferably, the specific process of regulating the proportional term parameter of the PID algorithm in the next welding process and then adjusting the output current of the next welding process is: The adjustment range of the proportional term parameter of the PID algorithm is set to [a, b]. According to the adjustment range of the proportional term and the welding influence coefficient of the current welding process, the proportional term parameter of the PID algorithm in the next welding process is obtained. The specific expression is: ; In the formula, is the proportional parameter of the i+1th welding process, a is the first preset parameter, b is the second preset parameter, is the normalized result of the welding influence coefficient of the i-th welding process; the obtained proportional term parameter is used as the proportional term parameter of the PID algorithm in the next welding process to adjust the output current of the next welding process.

[0011] In a second aspect, an embodiment of the present application provides an automatic welding device for a fixed tube sheet heat exchanger, the automatic welding device comprising: Data acquisition module, used to obtain current and voltage data during welding; The current characteristic analysis module is used to obtain the current abnormality coefficient based on the abnormality of the current data, the current fluctuation characteristics and the degree of difference in the change speed during the current rise and fall stages; and obtain the welding influence coefficient of the current welding process based on the current abnormality coefficient of the current welding process and the correlation between the current data and the voltage data; The PID parameter control module is used to control the proportional term of the PID algorithm in the next welding process according to the welding influence coefficient of the current welding process.

[0012] In a third aspect, an embodiment of the present application further provides an automatic welding system for a fixed tube plate heat exchanger, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein when the processor executes the computer program, the steps of any one of the above-mentioned automatic welding methods for a fixed tube plate heat exchanger are implemented.

[0013] This application has at least the following beneficial effects: This application aims at the problem that the welding quality will be affected by the output current and output voltage of the welding machine power supply during the welding process, deeply analyzes the abnormal characteristics of the output current at different stages, and combines the consistency relationship between the changes in welding current and voltage to obtain the welding influence coefficient of the current welding process, and optimizes the proportional term parameters of the PID algorithm in the next welding process based on the welding influence coefficient. Its beneficial effect is that it can timely optimize and adjust the proportional term parameters of the PID algorithm of the next welding process according to the fluctuation of the output current during the welding process and the asynchronous characteristics between the output current and the output voltage, so that the output current of the welding machine is adjusted in time, the welding quality of the fixed tube plate heat exchanger is improved, and the welding effect in different welding processes is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 A flowchart of a method for automatic welding of a fixed tube sheet heat exchanger provided in one embodiment of the present application; Figure 2 A step of obtaining a welding influence coefficient of a current welding process provided by an embodiment of the present application; Figure 3 A schematic structural diagram of an automatic welding device for a fixed tube sheet heat exchanger provided in accordance with an embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to further explain the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following is a detailed description of the fixed tube sheet heat exchanger automatic welding method, equipment and system proposed in the present application, its specific implementation method, structure, features and effects in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0017] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0018] The following is a detailed description of a specific solution of an automatic welding method, equipment and system for a fixed tube-sheet heat exchanger provided by the present application in conjunction with the accompanying drawings.

[0019] See also Figure 1 , which shows a flowchart of a method for automatic welding of a fixed tube sheet heat exchanger provided by an embodiment of the present application, the method comprising the following steps: Step 1: Obtain the current and voltage data during each welding process.

[0020] This embodiment uses a tube sheet automatic welder to weld the alloy tube sheet and heat exchange tube in the heat exchanger. The current sensor and voltage sensor are built into the tube sheet automatic welder to obtain the output current and output voltage of the automatic welder power supply in real time. This embodiment sets the acquisition frequency of the output current and output voltage to 1000Hz. In addition, the pulse welding method can reduce the heat input by controlling the current size and output time, which is conducive to the formation of welds and reduces the occurrence of defects. In order to improve the welding quality, this embodiment sets the pulse frequency and pulse duty cycle to 10Hz and 50% respectively.

[0021] Step 2: Divide the current data of each welding process into peak and base current data segments according to the peak state and base state of the pulse. Obtain the distortion abnormality value of each current data segment based on the minimum distance between the current data of each current data segment and the corresponding fitting curve, and the difference between each abnormal point in each current data segment and the left and right adjacent data; obtain the current pulse abnormality value of a single welding process based on the average level and discreteness of all distortion abnormality values ​​in a single welding process.

[0022] Before welding the alloy tube sheet and the heat exchange tube in the heat exchanger, in order to ensure the welding quality and improve the welding efficiency, the weldment needs to be pretreated first. During the pretreatment process, this embodiment first performs mechanical cleaning, using a wire brush and sandpaper to mechanically polish to remove oil, rust, and impurities in the oxide scale on the surface of the weldment, as well as burrs on the edge until the metallic luster is exposed. Then chemical cleaning is performed. This embodiment uses pickling liquid as a chemical cleaning agent to clean the surface of the weldment. This embodiment uses scrubbing to remove the stubborn oxide film and oil on the surface. Finally, rinse the weldment with clean water to ensure that there is no residual cleaning agent on the surface, and perform neutralization treatment to prevent corrosion.

[0023] After the pretreatment is completed, the tube sheet automatic welding machine is used for welding. In this embodiment, argon is used as a shielding gas during the welding process to achieve the effect of isolating the air. The quality of the annular weld of the corner joint between the alloy tube sheet and the heat exchange tube in the heat exchanger is the key to the manufacturing quality of the entire heat exchanger, and the number of joints of a single tube sheet heat exchanger is large, and a full-position automated welding process is required for welding. The molten pool metal may be affected by the combined effects of gravity, arc blowing force and surface tension and change continuously with the change of welding position, thereby affecting the weld formation. Therefore, it is necessary to keep the metal melt stable during welding. However, affected by the internal components of the welding power supply, the output current of the welding machine may be abnormal, showing certain irregular change characteristics, thereby reducing the welding quality. The current and voltage in the welding process are two core parameters, which will have a significant impact on the quality of the weld. During the welding process, the current and voltage need to be adjusted accordingly according to the welding position and welding angle, and as the wire is continuously fed, the output current and voltage may change to varying degrees. The consistency of the welding current and voltage changes is crucial to the welding effect. In view of the above-mentioned characteristics of the impact on welding quality, the following analysis is performed.

[0024] The current change of each welding process can be divided into three stages: current rise, pulse welding, and current drop. In the current rise stage, the current gradually increases to a given value in a pulsed manner at a certain tilt angle to prevent the current shock from affecting the welding effect; after the current reaches the given value, it enters the pulse welding stage, and after the welding is completed, it enters the current drop stage; in the current drop stage, the current gradually decreases in a pulsed manner at a certain tilt angle. The above three stages correspond to a complete welding process of the heat exchange tube and the tube sheet.

[0025] In each welding process, no matter at which stage, the current is pulsed, and each pulse cycle contains a peak current state and a base current state. The current data in the entire welding process shows that the peak current state and the base current state alternate with each other. When in the peak current state, the metal is melted, and when in the base current state, the arc is kept burning stably. The peak current mainly affects the melting degree of the weld. Too small a peak current will make the weld difficult to form, and too large a peak current will cause excessive melting of the metal, affecting the adjacent welds. The base current only needs to ensure that the arc can be kept burning stably. Too large a base current can easily lead to too large a weld, and too small a base current affects arc burning. When affected by the internal components or control system of the welding machine power supply, the output current of the welding machine is abnormal, and the pulse current waveform is distorted and has more significant mutation values, resulting in instability in the rising and falling stages, which in turn affects the formation of the weld. Based on this feature, the following processing is performed.

[0026] The current data of the i-th welding process is taken as an example for the following analysis. Under normal circumstances, there will be an obvious jump between the peak current stage and the base current stage. In order not to mistake this normal jump for an abnormal data mutation, it is necessary to analyze the peak current stage and the base current stage separately. In this embodiment, the Bernaola Galvan algorithm is used to obtain the segmentation point of the current data. According to the obtained segmentation point, the current data of the i-th welding process can be divided into multiple current data segments, wherein the current data segment is divided into a peak current data segment and a base current data segment. Whether it is a peak current data segment or a base current data segment, the current data segment has a sinusoidal waveform feature under normal circumstances, and the greater the deviation of the distorted current waveform from the sine wave, the more there will be some mutation points. Therefore, in this embodiment, the trigonometric function fitting technology is used to obtain the fitting curves of each current data segment respectively, and then the minimum distance between each data point and the corresponding fitting curve is calculated respectively, and the mean of all the distances of each current data segment is used as the waveform deviation coefficient of each current data segment. The larger the obtained waveform deviation coefficient, the greater the current distortion degree of the corresponding current data segment. In order to obtain the mutation characteristics of current data, this embodiment uses the SOS (Stochastic Outlier Selection) algorithm to detect abnormal points in each current data segment, sets the significance level of the algorithm to 0.9, and outputs all abnormal points in each current data segment. The SOS algorithm is a well-known technology, and the specific process is not repeated. The absolute value of the difference between each abnormal point and its two adjacent data on the left and right is calculated respectively, and the average of all the absolute values ​​in each current data segment is used as the mutation significance coefficient of each current data segment. The larger the obtained mutation significance coefficient, the more obvious the current mutation abnormality of the corresponding current data segment. It should be noted that when the abnormal point is located at the head or tail of the current data segment, resulting in the absence of data on its left or right, the calculation is performed according to the actual existing data. Further, the product of the waveform deviation coefficient of each current data segment and the mutation significance coefficient is used as the distortion abnormality value of each current data segment, which is used to characterize the abnormal characteristics of current distortion under each current data segment.

[0027] In addition to the above-mentioned current abnormality characteristics, the unstable welding current characteristics are also manifested in that the distortion abnormality values ​​of each current data segment are quite different. When the welding current is stable, the more stable the data of each current data segment is, the smaller the difference in the distortion abnormality values ​​between the corresponding current data segments is. Therefore, the product of the mean and standard deviation of the distortion abnormality values ​​of all current data segments in a single welding process is taken as the current pulse abnormality value of a single welding process, which is used to characterize the abnormal degree of the current in a single welding process.

[0028] Step 3: According to the degree of discreteness of the current mean value of each peak current data segment in the current rising stage and the current falling stage of a single welding process, the current fluctuation degree in the current rising stage and the current falling stage of a single welding process is obtained respectively; and combined with the difference in the current change speed in the current rising and falling stages of a single welding process, the abnormal factor of the single welding process is obtained.

[0029] Furthermore, during the automatic welding process, the change process of the welding current cooperates with the movement of the machine head. After the arc is successfully struck, the current enters the rising stage. At the same time, the machine head rotates around the connection position between the heat exchange tube and the tube sheet, and then enters the normal welding stage. At this time, the machine head has turned a certain angle. After one rotation, the weld is completed. Since the first section of the weld is completed in the current rising stage, the welding effect is not ideal. It is necessary to use the current falling stage to repair the weld in the current rising stage. Therefore, the stability of the current rising and falling process in the rising and falling stages is crucial. The current in each base current stage remains relatively stable, and mainly relies on the current in the peak stage to rise and fall. The current mean of each peak current data segment in the current rising stage and the current falling stage is calculated respectively, and the fitting straight lines of all the mean values ​​in the current rising stage and all the mean values ​​in the current falling stage are obtained respectively by using the straight line fitting technology, and the shortest distance between each mean value and the corresponding fitting straight line is calculated respectively, and the cumulative sum of all the distances in the current rising stage of the i-th welding process is used as the current fluctuation degree in the current rising stage of the i-th welding process, and the cumulative sum of all the distances in the current falling stage of the i-th welding process is used as the current fluctuation degree in the current falling stage of the i-th welding process. In addition, the weld seam in the current rising stage needs to be repaired in the current falling stage. Under normal circumstances, the current change speed between the two stages should be close. When an abnormality occurs, the current change speed of the two stages will be greatly different.

[0030] As a preferred implementation, according to the current fluctuation degree in the current rising stage and the current falling stage of a single welding process, and the difference in the current change speed in the current rising and falling stages of a single welding process, the abnormal factor of a single welding process is obtained to characterize the current fluctuation characteristics and difference characteristics in the current rising and falling stages of a single welding process. In this embodiment, the abnormal factor of the i-th welding process is recorded as , its specific expression is: ; In the formula, represents the abnormal factor of the ith welding process, represents the mean value of the current fluctuation during the current rising stage and the current falling stage in the i-th welding process, It represents the sum of the slopes of the fitted straight lines corresponding to the current mean values ​​in the current rising stage and the current falling stage during the i-th welding process. The larger the value, the greater the difference in the speed of the current rise and fall. It reflects the current fluctuation characteristics and difference characteristics in the current rising and falling stages during the i-th welding process.

[0031] Step 4: Obtain the current abnormality coefficient of the current welding process according to the current pulse abnormal value and abnormal factor of the current welding process; and obtain the welding influence coefficient of the current welding process in combination with the correlation between the current data and the voltage data in the current welding process, which is used to adjust the proportional term parameters of the PID algorithm in the next welding process, and then adjust the output current of the next welding process.

[0032] Furthermore, the product of the abnormal value of the current pulse in the ith welding process and the abnormal factor is taken as the current abnormal coefficient of the ith welding process, which is recorded as . The larger the value of is, the more unstable the current provided in the ith welding process is, and the greater the impact on the welding quality is. The current abnormality coefficient can comprehensively characterize the current abnormal state in the automatic welding process.

[0033] Furthermore, welding current and voltage will affect the quality of the weld, and during welding, the current and voltage will respond to changes in the welding position and welding angle, and as the conductive nozzle continues to feed the wire, the output current and voltage may change to varying degrees. The consistency of the welding current and voltage changes is crucial to the welding effect. To this end, this embodiment analyzes the change characteristics between the average current and voltage data during the welding process. For each welding process, the Spearman correlation coefficient between all current values ​​and all voltage values ​​in the current welding process is calculated and used as the consistency coefficient of the current welding process. The consistency coefficient of the i-th welding process is recorded as . The larger the value of , the stronger the correlation between the current data and the voltage data of the i-th welding process.

[0034] Furthermore, as a preferred embodiment, the welding influence coefficient of the current welding process is constructed according to the current abnormal coefficient and consistency coefficient of the current welding process, which is used to characterize the degree to which the output current of the welding machine is affected by the internal components of the power supply and other factors in the current welding process. The steps for obtaining the welding influence coefficient of the current welding process are as follows: Figure 2 In this embodiment, the welding influence coefficient of the i-th welding process is recorded as , its specific expression is: ; In the formula, is the welding influence coefficient of the i-th welding process, is the current abnormal coefficient of the i-th welding process, is the consistency coefficient of the ith welding process, and exp( ) represents an exponential function with the natural constant e as the base. The larger it is, the more unstable the i-th welding process is, and the greater the degree of influence of the internal components of the power supply and other multiple factors.

[0035] Furthermore, a PID algorithm is used to regulate the output current of the welding machine, and combined with the above analysis results, the proportional term of the PID algorithm in the next welding process is optimized. Specifically, when the welding influence coefficient of the current welding process is larger, it means that the output current of the welding machine power supply is more affected in the current welding process, and rapid adjustment is required. In this case, the proportional term parameter in the PID algorithm is appropriately increased in the next welding process. In this embodiment, the preset values ​​of the integral term and differential term parameters in the PID algorithm are set to 0.005 and 1.5, respectively, and the adjustment range of the proportional term parameter is set to [a, b]. In this embodiment, a=0.8 and b=1.6. The proportional term parameters for the next welding process are calculated based on the adjustment range of the proportional term and the welding influence coefficient of the current welding process: ; In the formula, is the proportional parameter of the i+1th welding process, a is the first preset parameter, b is the second preset parameter, is the normalized result of the welding influence coefficient of the i-th welding process. In this embodiment, the Sigmoid function is used for normalization. The obtained proportional term parameter is used as the proportional term of the PID algorithm in the next welding process to adjust the output current of the welding machine power supply in the next welding process, which helps to improve the stability and quality of automatic welding.

[0036] See also Figure 3 , Figure 3 Schematic diagram of the structure of a fixed tube plate heat exchanger automatic welding device provided in an embodiment of the present application. In this embodiment, each unit included in the terminal is used to execute each step in an embodiment corresponding to a fixed tube plate heat exchanger automatic welding method. Figure 3 ,The automatic welding equipment includes: data acquisition module, current characteristic analysis module, and PID parameter control module.

[0037] Data acquisition module, used to obtain current and voltage data during welding; The current characteristic analysis module is used to obtain the current abnormality coefficient based on the abnormality of the current data, the current fluctuation characteristics and the degree of difference in the change speed during the current rise and fall stages; and obtain the welding influence coefficient of the current welding process based on the current abnormality coefficient of the current welding process and the correlation between the current data and the voltage data; The PID parameter control module is used to control the proportional term of the PID algorithm in the next welding process according to the welding influence coefficient of the current welding process.

[0038] Based on the same inventive concept as the above method, an embodiment of the present application also provides an automatic welding system for a fixed tube plate heat exchanger, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above-mentioned automatic welding methods for a fixed tube plate heat exchanger when executing the computer program.

[0039] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0040] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0041] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present application should be included in the protection scope of the present application.

Claims

1. An automatic welding method for a fixed tube-sheet heat exchanger, characterized in that: The method comprises the following steps: Obtain current and voltage data during each welding process; The current data of each welding process is divided into peak value and base value current data segments according to the peak value state and base value state of the pulse. The distortion abnormal value of each current data segment is obtained according to the minimum distance between the current data of each current data segment and the corresponding fitting curve, and the difference between each abnormal point and the left and right adjacent data in each current data segment; the current pulse abnormal value of a single welding process is obtained according to the average level and discrete degree of all the distortion abnormal values ​​in a single welding process; According to the degree of dispersion of the current mean value of each peak current data segment in the current rising stage and the current falling stage of a single welding process, the current fluctuation degree in the current rising stage and the current falling stage of a single welding process is obtained respectively; and combined with the difference in the current change speed in the current rising and falling stages of a single welding process, the abnormal factor of a single welding process is obtained; According to the abnormal current pulse value and abnormal factor of the current welding process, the abnormal current coefficient of the current welding process is obtained; the welding influence coefficient of the current welding process is obtained, and the calculation formula is: ; In the formula, is the welding influence coefficient of the i-th welding process, is the current abnormal coefficient of the i-th welding process, is the consistency coefficient of the i-th welding process, exp( ) represents an exponential function with the natural constant e as the base; wherein, the consistency coefficient of the current welding process is the Spearman correlation coefficient between all current values ​​and all voltage values ​​in the current welding process; the proportional term parameters of the PID algorithm in the next welding process are adjusted, and then the output current of the next welding process is adjusted.

2. The automatic welding method for a fixed tube sheet heat exchanger according to claim 1, characterized in that: The process of obtaining the abnormal distortion value of each current data segment is as follows: Obtaining a fitting curve for each current data segment; calculating the minimum distance between each data point and the corresponding fitting curve, and taking the average of all the distances for each current data segment as the waveform deviation coefficient of each current data segment; Obtain the abnormal points of each current data segment, calculate the absolute value of the difference between each abnormal point and its two adjacent data on the left and right, and take the average of all the absolute values ​​in each current data segment as the mutation significance coefficient of each current data segment; The product of the waveform deviation coefficient and the mutation significance coefficient of each current data segment is taken as the distortion abnormal value of each current data segment.

3. The automatic welding method for a fixed tube sheet heat exchanger according to claim 1, characterized in that: The current pulse abnormal value of the single welding process is the product of the mean value and the standard deviation of the distortion abnormal values ​​of all current data segments in the single welding process.

4. The automatic welding method for a fixed tube sheet heat exchanger according to claim 1, characterized in that: The process of obtaining the current fluctuation degree in the current rising stage and the current falling stage of the single welding process is as follows: Calculate the current mean value of each peak current data segment in the current rising stage and the current falling stage respectively; Obtaining fitted straight lines of all mean values ​​in the current rising phase and all mean values ​​in the current falling phase respectively, and calculating the shortest distance between each current mean value and the corresponding fitted straight line respectively; The cumulative sum of all the shortest distances in the current rising stage of a single welding process is used as the current fluctuation degree of the current rising stage of the corresponding single welding process, and the cumulative sum of all the shortest distances in the current falling stage of the single welding process is used as the current fluctuation degree of the current falling stage of the corresponding single welding process.

5. The automatic welding method for a fixed tube sheet heat exchanger according to claim 4, characterized in that: The calculation process of the abnormal factor of the single welding process is: ; In the formula, represents the abnormal factor of the ith welding process, represents the mean value of the current fluctuation during the current rising stage and the current falling stage in the i-th welding process, It represents the sum of the corresponding slopes of the fitting straight lines of the current mean values ​​in the current rising stage and the current falling stage during the i-th welding process.

6. The automatic welding method for a fixed tube sheet heat exchanger according to claim 1, characterized in that: The current anomaly coefficient of the current welding process is the product of the current pulse anomaly value and the anomaly factor of the current welding process.

7. The automatic welding method for a fixed tube sheet heat exchanger according to claim 1, characterized in that: The specific process of regulating the proportional term parameter of the PID algorithm in the next welding process and then adjusting the output current of the next welding process is: The adjustment range of the proportional term parameter of the PID algorithm is set to [a, b]. According to the adjustment range of the proportional term and the welding influence coefficient of the current welding process, the proportional term parameter of the PID algorithm in the next welding process is obtained. The specific expression is: ; In the formula, is the proportional parameter of the i+1th welding process, a is the first preset parameter, b is the second preset parameter, is the normalized result of the welding influence coefficient of the i-th welding process; the obtained proportional term parameter is used as the proportional term parameter of the PID algorithm in the next welding process to adjust the output current of the next welding process.

8. An automatic welding device for a fixed tube-sheet heat exchanger, characterized in that: To implement an automatic welding method for a fixed tube sheet heat exchanger as described in any one of claims 1 to 7, the automatic welding equipment comprises: Data acquisition module, used to obtain current and voltage data during welding; The current characteristic analysis module is used to obtain the current abnormality coefficient based on the abnormality of the current data, the current fluctuation characteristics and the degree of difference in the change speed during the current rise and fall stages; and obtain the welding influence coefficient of the current welding process based on the current abnormality coefficient of the current welding process and the correlation between the current data and the voltage data; The PID parameter control module is used to control the proportional term of the PID algorithm in the next welding process according to the welding influence coefficient of the current welding process.

9. An automatic welding system for a fixed tube-sheet heat exchanger, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the automatic welding method for a fixed tube plate heat exchanger as described in any one of claims 1 to 7 are implemented.

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