An automatic welding method, equipment and system for a fixed tube sheet heat exchanger

Abstract

The present application relates to the technical field of automatic welding of heat exchangers, and specifically relates to an automatic welding method, device and system for a fixed tube-sheet heat exchanger. The method includes: obtaining current and voltage data during each welding process; dividing the current data of each welding process into multiple peak and base current data segments, and obtaining the distortion abnormal values of each current data segment; obtaining the current pulse abnormal value of a single welding process; respectively obtaining the current fluctuation degrees in the current rising stage and the current falling stage of a single welding process; obtaining the abnormal factor of a single welding process; obtaining the current abnormal coefficient of the current welding process; obtaining the welding influence coefficient of the current welding process, which is used to adjust the proportional term parameter during PID control in the next welding process. Thereby, the welding quality of the fixed tube-sheet heat exchanger is improved, and the welding effects in different welding processes are made more stable.

Description

Technical Field

[0001] This application relates to the technical field of automatic welding of heat exchangers, and specifically relates to an automatic welding method, equipment and system for a fixed tube-sheet heat exchanger. Background Art

[0002] A fixed tube-sheet heat exchanger is a heat exchange device widely used in the industrial field. Its main structures include components such as a shell, tube sheets, tube bundles, and top covers. Both ends of the tube bundle are fixed to the tube sheets by welding or expansion joints. The tube sheets are then welded to the shell to form an integral structure, which has the advantages of simple structure, low cost, high heat transfer efficiency, etc., and is suitable for various heat exchange process scenarios. For the welding of a fixed tube-sheet heat exchanger, due to the large number of tube sheet joints in the heat exchanger, small tube diameters, and narrow arrangement spacings, there is an urgent need for an efficient and stable automatic welding method.

[0003] The automatic welding process for the tube sheet of the heat exchanger disclosed in Publication No. CN113369730A has the same material for the tube sheet and the limit block. The tube sheet welder is used to perform a trial weld on the connection between the heat exchange tube and the limit block. After the trial weld is completed, the parameters of the tube sheet welder are adjusted for the final welding. This patent fails to consider that the instability of the internal components of the welder power supply during the welding process will lead to unstable output current, which in turn affects the welding quality. In addition, the non-synchronous change between the output voltage and output current of the welder will further reduce the welding quality. During the automatic welding process, the output current is usually regulated by presetting fixed PID regulation parameters according to the welding material and the required welding effect, without considering the influence of the above factors on the welding quality, resulting in unstable welding effects and poor welding quality during 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, and the specific technical solutions adopted are as follows:

[0005] In the first aspect, an embodiment of this application provides an automatic welding method for a fixed tube-sheet heat exchanger, and this method includes the following steps:

[0006] Obtain the current and voltage data during each welding process;

[0007] 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. According to the minimum distance between the current data of each current data segment and the corresponding fitting curve, and the differences between each abnormal point in each current data segment and the adjacent data on the left and right, obtain the distortion abnormal values of each current data segment; according to the average level and dispersion degree of all distortion abnormal values during a single welding process, obtain the current pulse abnormal value of a single welding process;

[0008] According to the degree of dispersion of the current mean values of each peak current data segment in the current rising stage and the current falling stage during a single welding process, the current fluctuation degrees of the current rising stage and the current falling stage of the single welding process are respectively obtained; and in combination with the difference in the current change speed in the current rising and falling stages of the single welding process, the abnormal factor of the single welding process is obtained.

[0009] According to the current pulse abnormal value and the abnormal factor of the current welding process, the current abnormal 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, and exp( ) represents the exponential function with the natural constant e as the base; among them, 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 parameter of the PID algorithm in the next welding process is regulated, and then the output current of the next welding process is adjusted.

[0010] Preferably, the process of obtaining the distortion abnormal value of each current data segment is as follows:

[0011] The fitting curve of each current data segment is obtained; the minimum distance between each data point and the corresponding fitting curve is calculated respectively, and the mean value of all the distances of each current data segment is used as the waveform deviation coefficient of each current data segment.

[0012] The abnormal points of each current data segment are obtained, the absolute values of the differences between each abnormal point and its two adjacent data on the left and right are calculated respectively, and the mean value of all the absolute values in each current data segment is used as the mutation significance coefficient of each current data segment.

[0013] The product of the waveform deviation coefficient and the mutation significance coefficient of each current data segment is used as the distortion abnormal value of each current data segment.

[0014] Preferably, 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 during the single welding process.

[0015] Preferably, the process of obtaining the current fluctuation degrees of the current rising stage and the current falling stage of the single welding process is as follows:

[0016] The current mean values of each peak current data segment in the current rising stage and the current falling stage are calculated respectively.

[0017] Obtain the fitting lines of all the means in the current rising stage and all the means in the current falling stage respectively, and calculate the shortest distance between each of the current means and the corresponding fitting line;

[0018] Take the sum of all the shortest distances in the current rising stage of a single welding process as the current fluctuation degree in the current rising stage of the corresponding single welding process, and take the sum of all the shortest distances in the current falling stage of a single welding process as the current fluctuation degree in the current falling stage of the corresponding single welding process.

[0019] Preferably, the calculation process of the abnormal factor of the single welding process is as follows: ; where represents the abnormal factor of the i-th welding process, represents the average value of the current fluctuation degrees in the current rising stage and the current falling stage of the i-th welding process, represents the sum of the corresponding slopes of the fitting lines of the current means in the current rising stage and the current falling stage of the i-th welding process.

[0020] Preferably, the current abnormal coefficient of the current welding process is the product of the current pulse abnormal value and the abnormal factor of the current welding process.

[0021] Preferably, the specific process of adjusting 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 as follows:

[0022] Set the adjustment range of the proportional term parameter of the PID algorithm as [a, b]; obtain the proportional term parameter of the PID algorithm in the next welding process according to the adjustment range of the proportional term and the welding influence coefficient of the current welding process, and its specific expression is: ; where is the proportional term parameter of the (i + 1)-th 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; use the obtained proportional term parameter as the proportional term parameter of the PID algorithm in the next welding process to adjust the output current of the next welding process.

[0023] In a second aspect, an automatic welding device for a fixed tube sheet heat exchanger provided by an embodiment of the present application includes:

[0024] A data acquisition module for obtaining current and voltage data during the welding process;

[0025] The current feature analysis module is used to obtain the current anomaly coefficient based on the anomaly degree of the current data, as well as the current fluctuation characteristics and the difference degree of the change speed in the current rising and falling stages; and to obtain the welding influence coefficient of the current welding process based on the current anomaly coefficient of the current welding process and the correlation between the current data and the voltage data.

[0026] The PID parameter regulation module is used to regulate the proportional term of the PID algorithm in the next welding process according to the welding influence coefficient of the current welding process.

[0027] In a third aspect, an embodiment of the present application further provides a fixed tube-sheet heat exchanger automatic welding system, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned fixed tube-sheet heat exchanger automatic welding methods are implemented.

[0028] The present application has at least the following beneficial effects:

[0029] Aiming at the problem that the welding quality in the welding process is affected by the output current and output voltage of the welding machine power supply, the present application deeply analyzes the abnormal characteristics of the output current in different stages, and combines the consistent relationship between the changes of the welding current and voltage to obtain the welding influence coefficient of the current welding process, and optimizes the proportional term parameter of the PID algorithm in the next welding process based on the welding influence coefficient. The beneficial effect is that it can timely optimize and adjust the proportional term parameter of the PID algorithm in the next welding process according to the fluctuation of the output current in the welding process and the asynchronous characteristics between the output current and the output voltage, so that the output current of the welding machine can be adjusted in time, improving the welding quality of the fixed tube-sheet heat exchanger and making the welding effect more stable in different welding processes. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a step flow chart of a fixed tube-sheet heat exchanger automatic welding method provided by an embodiment of the present application;

[0032] Figure 2 It is the acquisition step of the welding influence coefficient of the current welding process provided by an embodiment of the present application;

[0033] Figure 3A 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

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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:

[0038] Step 1: Obtain the current and voltage data during each welding process.

[0039] 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.

[0040] 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.

[0041] Before welding the alloy tube sheet and the heat exchange tubes in the heat exchanger, in order to ensure the welding quality and improve the welding efficiency, it is necessary to pre-treat the weldments first. During the pre-treatment process, in this embodiment, mechanical cleaning is first carried out. The oil stains, rust and scale on the surface of the weldments, as well as the burrs on the edge part, are removed by mechanical grinding with a wire brush and sandpaper until the metallic luster is exposed. Then chemical cleaning is carried out. In this embodiment, pickling solution is selected as the chemical cleaning agent to clean the surface of the weldments. In this embodiment, the stubborn oxide film and oil stains on the surface are removed by scrubbing. Finally, the weldments are rinsed with clean water to ensure that there is no residual cleaning agent on the surface, and neutralization treatment is carried out to prevent corrosion.

[0042] After the pre-treatment is completed, an automatic tube sheet welder is used for welding. In this embodiment, argon is used as the shielding gas during the welding process to achieve the effect of isolating the air. The quality of the circumferential weld of the fillet joint between the alloy tube sheet and the heat exchange tubes in the heat exchanger is the key to the manufacturing quality of the entire heat exchanger. And there are a large number of joints in a single tube-type heat exchanger, and a full-position automatic welding process needs to be adopted for welding. The molten pool metal may be affected by the combined action of gravity, arc blow force and surface tension and continuously change with the change of the welding position, thus affecting the weld formation. Therefore, it is necessary to keep the melting of the metal stable during welding. However, affected by the internal components of the welding machine 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 during the welding process are two core parameters, both of which will have a significant impact on the weld quality. 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 changes in the welding current and voltage is crucial for the welding effect. In view of the above influence characteristics on the welding quality, the following analysis is carried out.

[0043] The current change in each welding process can be divided into three stages: current rise, pulsed welding, and current fall. In the current rise stage, the current gradually rises to the given value in a pulsed manner at a certain inclination angle to prevent the impact of the current on the welding effect; after the current reaches the given value, it enters the pulsed welding stage. After the welding is completed, it enters the current fall stage; in the current fall stage, the current gradually decreases in a pulsed manner at a certain inclination angle. The above three stages correspond to a complete welding process of the heat exchange tube and the tube sheet.

[0044] 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.

[0045] Taking the current data of the $i$-th welding process as an example, the following analysis is carried out. 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 mutation of the data, 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, where the current data segments are divided into peak current data segments and base current data segments. Whether it is a peak current data segment or a base current data segment, the current data segment normally has the characteristics of a sine waveform. The greater the deviation of the distorted current waveform from the sine wave, and there will be some mutation points. Therefore, in this embodiment, the trigonometric function fitting technology is used to obtain the fitting curve of each current data segment respectively, and then the minimum distance between each data point and the corresponding fitting curve is calculated respectively. The mean value of all the distances of each current data segment is used as the waveform deviation coefficient of each current data segment. The greater 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 the current data, in this embodiment, the SOS (Stochastic Outlier Selection) algorithm is used to detect the abnormal points of each current data segment, and the significance level of this algorithm is set to 0.9, and the output is all the abnormal points of each current data segment. The SOS algorithm is a well-known technology, and the specific process will not be elaborated. 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 mean value of all the absolute values in each current data segment is used as the mutation significant coefficient of each current data segment. The greater the obtained mutation significant coefficient, the more obvious the abnormal current mutation 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 no data on its left or right, the calculation is carried out according to the actually existing data. Further, the product of the waveform deviation coefficient and the mutation significant coefficient of each current data segment is used as the distortion abnormal value of each current data segment, and this value is used to characterize the current distortion abnormal characteristics under each current data segment.

[0046] In addition, in addition to the above current abnormal characteristics, the unstable characteristic of the welding current is also manifested as a large difference in the distortion abnormal values of each current data segment. When the welding current is stable, the data of each current data segment is more stable, and the difference in the distortion abnormal values between the corresponding current data segments is smaller. Therefore, the product of the mean value and the standard deviation of the distortion abnormal values of all the current data segments in a single welding process is used as the current pulse abnormal value of the single welding process, and this value is used to characterize the abnormal degree of the current in the single welding process.

[0047] Step 3: According to the degree of dispersion of the current mean values of each peak current data segment in the current rising stage and the current falling stage during a single welding process, obtain the current fluctuation degrees of the current rising stage and the current falling stage of the single welding process respectively; and combine the differences in the current change speeds of the current rising and falling stages during the single welding process to obtain the abnormal factor of the single welding process.

[0048] Further, during the automatic welding process, the change process of the welding current cooperates with the movement of the welding head. After the arc is successfully initiated, the current enters the rising stage, and at the same time, the welding head rotates around the connection position between the heat exchange tube and the tube sheet. Then it enters the normal welding stage, and at this time, the welding head has rotated a certain angle. After rotating one circle, the weld is completed. Since the first section of the weld is completed during the current rising stage, its welding effect is not ideal, and it is necessary to use the current falling stage to repair and perfect the weld of the current rising stage. Therefore, the stability of the current rising and falling processes in the rising and falling stages is crucial. The current in each base current stage remains relatively stable, and the rise and fall of the current mainly rely on the current in the peak stage. Calculate the current mean values of each peak current data segment in the current rising stage and the current falling stage respectively, use the linear fitting technique to obtain the fitting lines of all the mean values in the current rising stage and all the mean values in the current falling stage respectively, calculate the shortest distance between each mean value and the corresponding fitting line respectively, and take the sum of all the distances in the current rising stage of the i-th welding process as the current fluctuation degree of the current rising stage of the i-th welding process, and take the sum of all the distances in the current falling stage of the i-th welding process as the current fluctuation degree of the current falling stage of the i-th welding process. In addition, the current falling stage needs to repair and weld the weld of the current rising stage. Normally, the current change speeds between these two stages should be close. When an abnormality occurs, there will be a large difference in the current change speeds of these two stages.

[0049] As a preferred implementation manner, according to the current fluctuation degrees of the current rising stage and the current falling stage of a single welding process, and the differences in the current change speeds of the current rising and falling stages during the single welding process, obtain the abnormal factor of the single welding process, which is used to characterize the current fluctuation characteristics and difference characteristics of the current rising and falling stages during the single welding process. In this embodiment, the abnormal factor of the i-th welding process is denoted as , and its specific expression is: ; in the formula, represents the abnormal factor of the i-th welding process, represents the mean value of the current fluctuation degrees of the current rising stage and the current falling stage during the i-th welding process, represents the sum of the corresponding slopes of the fitting lines of the current mean values of the current rising stage and the current falling stage during the i-th welding process, and the obtained The larger it is, the greater the difference in the speed of current rise and fall. The anomaly factor reflects the current fluctuation characteristics and difference characteristics during the current rise and fall stages of the i-th welding process.

[0050] Step 4: Obtain the current anomaly coefficient of the current welding process based on the current pulse anomaly value and the anomaly factor of the current welding process; and combine the correlation between the current data and voltage data during the current welding process to obtain the welding influence coefficient of the current welding process, which is used to adjust the proportional term parameter of the PID algorithm during the next welding process, and further adjust the output current of the next welding process.

[0051] Furthermore, take the product of the current pulse anomaly value and the anomaly factor of the i-th welding process as the current anomaly coefficient of the i-th welding process, denoted as . The larger the value of is, the more unstable the current provided during the i-th welding process, and the greater the impact on the welding quality. The current anomaly coefficient can comprehensively characterize the current anomaly state during the automatic welding process.

[0052] Furthermore, both the welding current and voltage affect the weld quality, and during welding, the current and voltage will respond and adjust according to the welding position and welding angle changes, and as the wire feeder continuously feeds wire through the contact tip, the output current and voltage may change to varying degrees. The consistency of the changes in welding current and voltage is crucial for the welding effect. Therefore, in this embodiment, the change characteristics between the average current and voltage data during the welding process are analyzed. For each welding process, calculate the Spearman correlation coefficient between all current values and all voltage values during the current welding process, and take it as the consistency coefficient of the current welding process. Denote the consistency coefficient of the i-th welding process as . The larger the value of is, the stronger the correlation between the current data and voltage data of the i-th welding process.

[0053] Furthermore, as a preferred implementation manner, based on the current anomaly coefficient and the consistency coefficient of the current welding process, construct the welding influence coefficient of the current welding process, which is used to characterize the degree to which the output current of the welding machine during the current welding process is affected by internal devices of the power supply and other factors. The steps to obtain the welding influence coefficient of the current welding process are as Figure 2 shown. In this embodiment, denote the welding influence coefficient of the i-th welding process as , and its specific expression is: ; where, is the welding influence coefficient of the i-th welding process, is the current anomaly coefficient of the i-th welding process, is the consistency coefficient of the i-th welding process, and exp( ) represents the exponential function with the natural constant e as the base. The obtained The larger it is, the more unstable the i-th welding process is, and the greater the influence of internal devices of the power supply and other multiple factors.

[0054] Furthermore, the 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 in the current welding process is more affected and needs to be quickly adjusted. Then, 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 the derivative 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 as [a, b]. In this embodiment, a = 0.8 and b = 1.6. The proportional term parameter for the next welding process is calculated according to the adjustment range of the proportional term and the welding influence coefficient of the current welding process: ; where is the proportional term parameter of the (i + 1)-th 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. Using the obtained proportional term parameter 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 helps to improve the stability and quality of automatic welding.

[0055] Please refer to Figure 3 , Figure 3 is a schematic structural diagram of an automatic welding device for a fixed tube-sheet heat exchanger provided by an embodiment of the present application. In this embodiment, each unit included in the terminal is used to execute each step in the corresponding embodiment of a method for automatically welding a fixed tube-sheet heat exchanger. Refer to Figure 3 ,the automatic welding device includes: a data acquisition module, a current characteristic analysis module, and a PID parameter regulation module.

[0056] The data acquisition module is used to obtain current and voltage data during the welding process;

[0057] The current characteristic analysis module is used to obtain the current anomaly coefficient based on the anomaly degree of the current data, as well as the current fluctuation characteristics and the difference in change speed during the current rising and falling stages; and obtain the welding influence coefficient of the current welding process based on the current anomaly coefficient of the current welding process and the correlation between the current data and the voltage data;

[0058] The PID parameter adjustment module is used to adjust the proportional term of the PID algorithm in the next welding process according to the welding influence coefficient of the current welding process.

[0059] Based on the same inventive concept as the above method, an embodiment of the present application further provides an automatic welding system for a fixed tube-sheet heat exchanger, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above methods for an automatic welding method of a fixed tube-sheet heat exchanger are implemented.

[0060] It should be noted that: the above order of the embodiments of the present application is only for description and does not represent the advantages and disadvantages of the embodiments. And the above description of specific embodiments of this specification is provided. In addition, the processes depicted in the 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.

[0061] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

[0062] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present application shall 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 includes the following steps: Obtain the current and voltage data during each welding process; 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. Based on the minimum distance between the current data of each current data segment and the corresponding fitting curve, and the differences between each abnormal point in each current data segment and the adjacent data on the left and right, obtain the distortion abnormal values of each current data segment; According to the average level and dispersion degree of all the distortion abnormal values during a single welding process, obtain the current pulse abnormal value of the single welding process; According to the dispersion degree of the current mean values of each peak current data segment during the current rising stage and the current falling stage of a single welding process, respectively obtain the current fluctuation degrees of the current rising stage and the current falling stage of the single welding process; And combine the differences in the current change speeds during the current rising and falling stages of a single welding process to obtain the abnormal factor of the single welding process; Obtain the current abnormal coefficient of the welding current according to the abnormal value and abnormal factor of the current pulse in the current welding process; obtain the welding influence coefficient of the current welding process, and the calculation formula is: ; In the formula, is the welding influence coefficient of the i-th welding process, is the abnormal coefficient of the welding current of the i-th welding process, is the consistency coefficient of the i-th welding process, and exp( ) represents the exponential function with the natural constant e as the base; among them, 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; adjust the proportional term parameter of the PID algorithm in the next welding process, and then adjust the output current of the next welding process.

2. The automatic welding method of a fixed tube-sheet heat exchanger as claimed in claim 1, wherein The process of obtaining the distortion abnormal value of each current data segment is as follows: Obtain the fitting curve of each current data segment; Calculate the minimum distance between each data point and the corresponding fitting curve respectively, and take the mean value of all the distances of 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 respectively, and take the mean value of all the absolute values in each current data segment as the mutation significance coefficient of each current data segment; Take the product of the waveform deviation coefficient and the mutation significance coefficient of each current data segment 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 during the single welding process.

4. The automatic welding method for a fixed tube-sheet heat exchanger according to claim 1, wherein The process of obtaining the current fluctuation degrees of the current rising stage and the current falling stage of the single welding process is as follows: Calculate the current mean values of each peak current data segment during the current rising stage and the current falling stage respectively; Obtain the fitting straight lines of all the mean values during the current rising stage and all the mean values during the current falling stage respectively, and calculate the shortest distance between each current mean value and the corresponding fitting straight line; Take the sum of all the shortest distances during the current rising stage of the single welding process as the current fluctuation degree during the current rising stage of the corresponding single welding process, and take the sum of all the shortest distances during the current falling stage of the single welding process as the current fluctuation degree during the current falling stage of the corresponding single welding process.

5. The automatic welding method of a fixed tube-sheet heat exchanger according to claim 4, wherein The calculation process of the abnormal factor for the single welding process is as follows: ; where represents the abnormal factor for the i-th welding process, represents the average value of the current fluctuation degrees in the current rising stage and the current falling stage during the i-th welding process, represents the sum of the slopes corresponding to the fitting lines of the current average values in the current rising stage and the current falling stage during the i-th welding process.

6. The automatic welding method of a fixed tube-sheet heat exchanger according to claim 1, characterized in that, The current abnormal coefficient of the current welding process is the product of the current pulse abnormal value and the abnormal 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 during the next welding process and then adjusting the output current of the next welding process is as follows: Set the adjustment range of the proportional term parameter of the PID algorithm to [a, b]; obtain the proportional term parameter of the PID algorithm in the next welding process according to the adjustment range of the proportional term and the welding influence coefficient of the current welding process, and its specific expression is: ; In the formula, is the proportional term parameter of the (i + 1)-th welding process, a is the first preset parameter, b is the second preset parameter, is the normalization result of the welding influence coefficient of the i-th welding process; use the obtained proportional term parameter 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, Implement an automatic welding method for a fixed tube-sheet heat exchanger as described in any one of claims 1-7. The automatic welding equipment includes: A data acquisition module for obtaining the current and voltage data during the welding process; The current feature analysis module is used to obtain the current anomaly coefficient based on the anomaly degree of current data, as well as the current fluctuation characteristics and the difference degree of change speed in the current rising and falling stages; and obtain the welding influence coefficient of the current welding process based on the current anomaly coefficient of the current welding process and the correlation between the current data and the voltage data. The PID parameter regulation module is used to regulate 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, it implements the steps of the automatic welding method for a fixed tube-sheet heat exchanger according to any one of claims 1-7.

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