Shell detection method, device and tool and process parameter optimization method

Abstract

The invention relates to the technical field of batteries, in particular to a shell detection method, device and tool and a process parameter optimization method, and the shell detection method comprises the steps: carrying out the gas leakage detection of shells with the same process parameters, and obtaining the critical pressure when the shells start to leak gas; according to the critical pressure, the weld strength qualification rate and the critical pressure concentrated distribution value of the shell welded under the corresponding process parameters are determined; and determining the weld strength grade of the shell welded under the corresponding process parameters according to the weld strength qualification rate and the critical pressure concentrated distribution value. The detection method is used for detecting the air leakage condition of the shell under the condition of the same process parameter, namely the structural strength of the shell weld joint, and further analyzing the risk after the shell welded under the condition of the process parameter is made into a battery cell, so that the process parameter is conveniently adjusted in the shell processing stage to improve the weld joint strength of the high-frequency welding shell.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a shell detection method, device, tooling and process parameter optimization method. Background Art

[0002] The battery shell is welded by high-frequency welding or bending laser welding. After welding, there will be a weld on the side of the shell. There may be microscopic cracks that penetrate the shell wall thickness at the weld. The cracks will cause the shell to leak, and different process parameters will cause the above characteristics of the shell weld to be different. At present, helium detection is mainly used to detect cracks in the shell weld with the same process parameters. The helium leak rate is used to judge whether the weld strength of the shell produced under the process parameter conditions can meet the standard.

[0003] However, the pressure state of the shell during the helium inspection does not match the actual pressure state of the battery during the entire production and use process. Specifically, the pressure inside the shell during the entire production and use of the battery can reach nearly 0.4MPa, while the internal pressure of the existing shell during the helium inspection is -1pa to -90kPa. Since the pressure inside the shell is relatively high during the entire production and use of the battery, this will cause some shells that have passed the helium inspection to expand again due to high pressure during subsequent battery processing, causing some potential cracks at the welds (cracks that do not leak during the helium inspection) to expand. After these shells are processed into batteries, the battery cells will leak, resulting in a high probability that the batteries made from shells that have passed the helium inspection will become defective products.

[0004] Therefore, it is obviously unreasonable to use the helium leak rate to judge whether the weld strength of the shell produced under the corresponding process parameter conditions can meet the standard. Summary of the invention

[0005] The present application provides a shell detection method, device, tooling and process parameter optimization method to solve the problem that the method in the prior art of judging whether the weld strength of the shell produced under the process parameter conditions can meet the standard by the helium leak rate is unreasonable.

[0006] In one aspect, the present application provides a shell detection method, comprising: Perform gas leakage detection on shells with the same process parameters respectively, and obtain the critical pressure when the shell starts to leak; Determine the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under corresponding process parameters according to the critical pressure; The weld strength grade of the shell welded under corresponding process parameters is determined according to the weld strength qualification rate and the critical pressure concentration distribution value.

[0007] In a possible design, gas leakage detection is performed on shells with the same process parameters respectively, and the critical pressure when the shell starts to leak is obtained respectively, including: Inflate the inner cavities of the shells with the same process parameters respectively, and control the pressure in the inner cavities of the shells to increase in a gradient; During the process of the pressure rising in the inner cavity of the shell, it is determined whether the shell is leaking, and the pressure corresponding to when the shell starts to leak is determined as the critical pressure.

[0008] In a possible design, respectively inflating the inner cavity of the shell to control the pressure rise in the inner cavity of the shell includes: The pressure of the inner cavity of the shell with the same process parameters is controlled to increase in a gradient from the first preset pressure until the shell leaks or the pressure of the inner cavity of the shell rises to the second preset pressure, and the inflation is stopped. The pressures of two adjacent gradients differ by a preset difference, and the pressure of each gradient is maintained for a preset time.

[0009] In a possible design, determining whether the housing is leaking includes: The shell is placed below the liquid level of the liquid medium. During the process of inflating the inner cavity of the shell, if bubbles appear on the liquid surface, it is determined that the shell is leaking; if no bubbles appear on the liquid surface, it is determined that the shell is not leaking.

[0010] In a possible design, the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under corresponding process parameters are determined according to the critical pressure, including: If the critical pressure is less than or equal to the standard pressure, the weld strength of the shell is unqualified; if the critical pressure is greater than the standard pressure, the weld strength of the shell is qualified; The critical pressure concentration distribution value is the pressure value corresponding to the gradient where the number of shells with air leakage is the largest.

[0011] In a possible design, determining the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under corresponding process parameters according to the critical pressure also includes: The two ends of the shell whose critical pressure is greater than the standard pressure are pulled apart, and metallographic inspection is performed on the broken shell; Determine whether the fracture of the shell overlaps with the weld. If so, the weld strength of the shell is unqualified; if not, the weld strength of the shell is qualified.

[0012] In a possible design, the weld strength grade of the shell welded under the process parameters is determined according to the weld strength qualification rate and the critical pressure concentration distribution value, including: If the qualified rate is greater than or equal to the standard qualified rate, and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is level one; If the qualified rate is less than the standard qualified rate and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is Level 2; If the qualified rate is less than the standard qualified rate and the critical pressure concentration distribution value is less than or equal to the standard pressure, the weld strength grade is grade three.

[0013] On the other hand, the present application also provides a housing detection device, comprising: The gas leakage detection module is used to perform gas leakage detection on the shells with the same process parameters respectively, and obtain the critical pressure when the shells start to leak; A first determination module is used to determine the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under corresponding process parameters according to the critical pressure; The second determination module is used to determine the weld strength grade of the shell welded under corresponding process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value.

[0014] On the other hand, the present application further provides a detection tool, which is used to perform gas leakage detection on housings with the same process parameters, respectively, the housing having a first port and a second port arranged oppositely, and the detection tool comprises: Water tank; A limit seat, arranged in the water tank, having a U-shaped groove for placing the shell; A first sealing plate, used for sealing the first port, having an air filling port; The second sealing plate is used to seal the second port.

[0015] In one possible design, the stopper includes: A bottom plate, arranged on the bottom wall of the water tank; A first side plate, vertically arranged on one side edge of the bottom plate; A second side plate is vertically arranged on the other side edge of the bottom plate and is arranged opposite to the first side plate; The limiting member can be connected with the first side plate and the second side plate so that the first side plate and the second side plate are respectively pressed against the opposite sides of the shell.

[0016] On the other hand, the present application also provides a process parameter optimization method, including the shell detection method as described above, and also including: adjusting the process parameters according to the weld strength level, the process parameters including at least one of the heat affected zone ratio, circular beam power, center beam power, welding speed, defocus amount, weld trajectory, nitrogen flow, nitrogen dryness, and dust removal wind speed.

[0017] The beneficial effects of this application are as follows: The shell detection method of the present application performs gas leakage detection on the shells with the same process parameters respectively, and obtains the critical pressure when the shell starts to leak respectively; determines the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under the process parameters according to the critical pressure; determines the weld strength grade of the shell welded under the process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value. The detection method is used to detect the leakage condition of the shell under the same process parameter conditions, so as to determine the weld structural strength of the shell produced under the process parameter conditions based on the leakage condition of the shell under the process parameter conditions, and analyzes the risk of the shell welded under the process parameter conditions after being made into a battery cell through the weld structural strength, and promptly feeds back the detection results to the shell processing stage, so as to facilitate the adjustment of the process parameters in the shell processing stage to improve the weld strength of the high-frequency welded shell, improve the shell qualification rate, and reduce the defective rate of the shell produced as a battery.

[0018] The shell detection tooling provided in the present application is used to execute the shell detection method in the present application to perform air leakage detection on shells with the same process parameters respectively, and therefore has all the above-mentioned advantages of the shell detection method.

[0019] The shell process parameter optimization method provided in the present application includes the shell detection method in the present application, and therefore also includes all the above advantages of the shell detection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of a process flow of a shell detection method provided in one embodiment of the present application; Figure 2 A schematic flow chart of a method for optimizing shell manufacturing process parameters provided in one embodiment of the present application; Figure 3 A schematic diagram of a housing detection device provided in accordance with an embodiment of the present application; Figure 4 A schematic diagram of the structure of a detection tool provided for one embodiment of the present application; Figure 5 for Figure 4 Sectional view along AA; Figure 6 It is a schematic diagram of the structure of the shell.

[0022] Reference numerals: 1. Limit seat; 11. Bottom plate; 12. First side plate; 13. Second side plate; 2. First sealing plate; 3. Second sealing plate; 4. Limit member; 5. Welding seam position. DETAILED DESCRIPTION

[0023] The technical solution of the present application will be described clearly and completely below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0024] Figure 1 A schematic diagram of a process flow of a shell detection method provided in one embodiment of the present application.

[0025] Reference Figure 1 As shown, the shell detection method provided in the embodiment of the present application is described, which mainly includes the following steps: Step S101, performing gas leakage detection on shells with the same process parameters respectively, and obtaining the critical pressure when the shells start to leak respectively; It should be noted that, since the detection method of this embodiment is used to determine the weld strength grade of the shell under the same process parameters, the shell to be tested should be selected from the same batch of shells welded under the same process parameter conditions. Among them, the process parameters include heat affected zone ratio, annular beam power, center beam power, welding speed, defocus, weld trajectory, nitrogen flow, nitrogen dryness and dust removal wind speed, so the same process parameters refer to the values ​​of all the above parameters of the shell to be tested are equal.

[0026] In some specific embodiments of the present application, step S101 is specifically as follows: The shell is placed underwater, and the first port and the second port at opposite ends of the shell are blocked to form a closed inner cavity of the shell, and then the inner cavity of the shell is inflated to increase the pressure of the inner cavity of the shell in a gradient manner. Specifically, the pressure of the inner cavity of the shell is increased in a gradient manner from a first preset pressure, and the pressures of two adjacent gradients differ by a preset difference, and the pressure of each gradient is maintained for a preset time until the shell leaks or the pressure of the inner cavity of the shell rises to a second preset pressure, and then the inflation is stopped. For example, the pressure in the shell cavity is gradually increased from 0.2 MPa, and the difference between two adjacent gradients is 0.05 MPa. That is, the pressure in the shell cavity is increased in the order of 0.2 MPa, 0.25 MPa, 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa, 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.65 MPa, 0.7 MPa, 0.75 MPa and 0.8 MPa. Based on the pressure on the shell during the battery processing, the general detection pressure rises to 0.8 MPa. During the pressure increase process, the pressure of each gradient is maintained for 20 seconds to observe whether the shell leaks. When the shell leaks, stop inflating the shell immediately. The pressure of the current gradient is the critical pressure of the shell. For example, when the pressure is pressurized to 0.5MPa, the shell leaks, and 0.5MPa is the critical pressure of the shell. If the pressure is increased to 0.8MPa and the shell still does not leak, stop inflating the shell, and 0.8MPa is the critical pressure of the shell.

[0027] During the process of the pressure in the inner cavity of the shell continuously rising, if bubbles appear on the water surface, the shell is leaking; if no bubbles appear on the water surface, the shell is not leaking. When the potential cracks at the weld of the shell are expanded by air pressure due to pressure, the gas inside the shell leaks from the expanded cracks, and bubbles appear on the water surface. When bubbles are detected on the water surface, the inflation into the inner cavity of the shell is stopped immediately, and the inner cavity pressure corresponding to the appearance of bubbles on the water surface is determined as the critical pressure, that is, the maximum pressure that the shell can withstand. In this way, by making the pressure in the inner cavity of the shell rise in a gradient, it is helpful to determine a more accurate critical pressure. By underwater detection of leaks, leaks can be discovered more promptly, which is helpful to determine a more accurate critical pressure. If you want to improve the accuracy, the preset difference between two adjacent gradient pressures can be further reduced.

[0028] After the critical pressure of the shell is determined, step S102 is performed.

[0029] Step S102, determining the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under corresponding process parameters according to the critical pressure; In some specific embodiments of the present application, the method for determining the weld strength qualification rate in step S102 is specifically as follows: after obtaining the critical pressure of the shell in step S101, compare the critical pressure with the standard pressure, wherein the standard pressure is the maximum pressure to which the shell is subjected during the battery production process; if the critical pressure is less than or equal to the standard pressure, it means that the shell may have a high-pressure expansion joint in the high-pressure environment of the battery production process, and therefore the weld strength of the shell is unqualified; if the critical pressure is greater than the standard pressure, it means that the shell will not have a high-pressure expansion joint in the high-pressure environment of the battery production process, and therefore the weld strength of the shell is qualified. Specifically, the standard pressure is 0.4MPa, and if the critical pressure is less than or equal to 0.4MPa, the weld strength of the shell is unqualified; if the critical pressure is greater than 0.4MPa, the weld strength of the shell is qualified. Based on the total number of shells involved in the test and the number of shells with qualified weld strength, the weld strength qualification rate of the shell is calculated.

[0030] The method for determining the critical pressure concentration distribution value in step S102 is specifically as follows: the critical pressure concentration distribution value is the pressure value corresponding to the gradient with the largest number of shells having air leakage. For example, among the gradients of 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, 0.5MPa, 0.55MPa, 0.6MPa, 0.65MPa, 0.7MPa, 0.75MPa, and 0.8MPa, the pressure value corresponding to the gradient with the largest number of shells having air leakage is 0.5MPa, and the critical pressure concentration distribution value is 0.5MPa.

[0031] In some embodiments of the present application, step S102 further includes: The two ends of the shell whose critical pressure is greater than the standard pressure are pulled apart, and the metallographic inspection is performed on the broken shell; it is determined whether the fracture of the shell overlaps with the weld. If so, the weld strength of the shell is unqualified; if not, the weld strength of the shell is qualified.

[0032] It should be noted that although the critical pressure of some shells is greater than the standard pressure, the weld strength of the shell is not necessarily qualified, and there is still a risk of leakage after the battery is made. Therefore, the shell with a critical pressure greater than the standard pressure needs to be further metallographically tested. When both the metallographic test and the gas leakage test are passed, the weld strength of the shell is qualified. If the metallographic test fails, the weld strength of the shell is unqualified. Specifically, the two ends of the shell with a critical pressure greater than the standard pressure are pulled apart, and the metallographic test is performed on the broken shell. The color of the weld is different from the color of other parts of the shell. In this way, by identifying the color, it can be judged whether the shell fracture and the weld overlap. If the shell fracture overlaps with the weld, such as complete overlap or partial overlap or end overlap, the shell weld strength is unqualified; if the shell fracture has no overlap with the weld, the shell weld strength is qualified. In this way, the weld characteristics of the shell under the corresponding process parameters can be further detected.

[0033] After the weld strength qualification rate and the critical pressure concentration distribution value are determined, step S103 is performed.

[0034] Step S103, determining the weld strength grade of the shell welded under corresponding process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value.

[0035] In some embodiments of the present application, step S103 includes: If the qualified rate is greater than or equal to the standard qualified rate, and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is level one; if the qualified rate is less than the standard qualified rate, and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is level two; if the qualified rate is less than the standard qualified rate, and the critical pressure concentration distribution value is less than or equal to the standard pressure, the weld strength grade is level three. It should be noted that the weld strength grade is for batch shells under process parameter conditions, not for a single shell, so judging the quality of the corresponding process parameters by the weld strength grade has a greater reference value.

[0036] After testing, if the weld strength grade of the shell under the corresponding process parameters is determined to be level one, then the process parameters are listed as preferred parameters and can be put into shell production; if after testing, the weld strength grade of the shell under the corresponding process parameters is determined to be level two, then the process parameters are listed as parameters to be improved, and further adjustment and verification are required before they can be put into shell production after passing the test again; if after testing, the weld strength grade of the shell under the corresponding process parameters is determined to be level three, then the process parameters are listed as parameters to be improved. Of course, the shell weld strength grade can be subdivided into more levels to make the process parameters more specific, such as level one improvement, level two improvement, level three improvement, etc. For each level of improvement parameters, they can be modified by setting a specific adjustment parameter model, thereby improving the shell weld strength grade under the modified process parameters.

[0037] By utilizing the technical solution of the above-mentioned embodiment, air leakage detection is performed on shells with the same process parameters respectively, and the critical pressure when the shell starts to leak is obtained respectively; the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under the process parameters are determined according to the critical pressure; the weld strength grade of the shell welded under the process parameters is determined according to the weld strength qualification rate and the critical pressure concentration distribution value. The detection method is used to detect the weld strength of the shell welded under the same process parameter conditions. By applying the detection method to the detection of the shell welded under different process parameter conditions, the weld characteristics of the shell welded under different process parameters can be distinguished by the weld strength level, so that corresponding parameter optimization measures can be taken for each weld strength level, which is used to convert product test data into process improvement data related to the process parameters, so as to provide accurate data feedback to the front end, and provide detection data support for the welding parameters of the high-frequency welding or bending laser welding shell, so that the front-end production stage and the detection stage form a complete closed loop, so that in the high-frequency welding or bending laser welding stage of the shell, the welding process parameters can be adjusted in time to improve the weld strength of the high-frequency welding or bending laser welding shell, thereby improving the yield rate after the shell is processed into a battery.

[0038] Figure 2 A schematic flow chart of a method for optimizing shell process parameters provided in accordance with an embodiment of the present application.

[0039] Reference Figure 2 As shown, in an embodiment of the present application, a process parameter optimization method is also provided. After determining the weld strength grade of the shell welded under the corresponding process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value, it also includes step S104: adjusting the process parameters according to the weld strength grade, and the process parameters include at least one of the heat affected zone ratio, the annular beam power, the central beam power, the welding speed, the defocus amount, the weld trajectory, the nitrogen flow, the nitrogen dryness, and the dust removal wind speed. It should be noted that the process parameter optimization method makes the process parameters corresponding to the shell with a weld strength grade of level two or level three increase to level one of the weld strength grade of the shell under the modified process parameters by adjusting at least one of the heat affected zone ratio, the annular beam power, the central beam power, the welding speed, the defocus amount, the weld trajectory, the nitrogen flow, the nitrogen dryness, and the dust removal wind speed.

[0040] Figure 3 A schematic diagram of a shell detection device provided in one embodiment of the present application.

[0041] Reference Figure 3 As shown, the embodiment of the present application also provides a housing detection device, including: The air leakage detection module 201 is used to perform air leakage detection on the shells with the same process parameters respectively, and obtain the critical pressure when the shells start to leak respectively; The first determination module 202 is used to determine the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under corresponding process parameters according to the critical pressure; The second determination module 203 is used to determine the weld strength grade of the shell welded under corresponding process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value.

[0042] Furthermore, the air leakage detection module 201 is specifically used for: Inflate the inner cavity of the shell so that the pressure in the inner cavity of the shell increases in a gradient manner; To determine whether the shell is leaking, the pressure corresponding to when the shell starts to leak is the critical pressure.

[0043] Furthermore, the air leakage detection module 201 is also specifically used for: The pressure in the inner cavity of the shell starts to increase from the first preset pressure, and the pressures of two adjacent gradients differ by a preset difference. The pressure of each gradient is maintained for a preset time until the shell leaks or the pressure in the inner cavity of the shell rises to a second preset pressure, and inflation is stopped.

[0044] Furthermore, the air leakage detection module 201 is also specifically used for: The shell is placed underwater. During the process of inflating the inner cavity of the shell, if bubbles appear on the water surface, the shell is leaking; if no bubbles appear on the water surface, the shell is not leaking.

[0045] Furthermore, the first determining module 202 is specifically configured to: If the critical pressure is less than or equal to the standard pressure, the weld strength of the shell is unqualified; if the critical pressure is greater than the standard pressure, the weld strength of the shell is qualified; The critical pressure concentration distribution value is the pressure value corresponding to the gradient where the number of shells with air leakage is the largest.

[0046] Furthermore, the first determining module 202 is further configured to: The two ends of the shell whose critical pressure is greater than the standard pressure are pulled apart, and metallographic inspection is performed on the broken shell; Determine whether the fracture of the shell overlaps with the weld. If so, the weld strength of the shell is unqualified; if not, the weld strength of the shell is qualified.

[0047] Furthermore, the second determining module 203 is specifically configured to: If the qualified rate is greater than or equal to the standard qualified rate, and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is level one; If the qualified rate is less than the standard qualified rate and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is Level 2; If the qualified rate is less than the standard qualified rate and the critical pressure concentration distribution value is less than or equal to the standard pressure, the weld strength grade is grade three.

[0048] Figure 4 A schematic diagram of the structure of a detection tool provided for one embodiment of the present application; Figure 5 for Figure 4 The cross-section along AA, Figure 6 It is a schematic diagram of the structure of the shell.

[0049] Reference Figure 4 , Figure 5 , Figure 6 As shown, the embodiment of the present application also provides a detection tool, through which the shells with the same process parameters are respectively tested for air leakage. Specifically, the shell is a rectangular shell, and the shell has a first port and a second port arranged oppositely, and the side of the shell is a weld position 5. The detection tool includes a water tank, a limit seat 1, a first sealing plate 2 and a second sealing plate 3. The limit seat 1 is arranged in the water tank, and the limit seat 1 has a U-shaped groove for placing the shell; the first sealing plate 2 is used to seal the first port, and the first sealing plate 2 has an air filling port; the second sealing plate 3 is used to seal the second port. Specifically, water is filled in the water tank, the limit seat 1 is a U-shaped seat, and a U-shaped groove is formed on the U-shaped seat, and the notch of the U-shaped groove is upward. By setting the rectangular shell in the U-shaped groove, the first port and the second port of the rectangular shell are leaked from the left and right sides of the U-shaped groove respectively, wherein the first port of the rectangular shell is sealed by the first sealing plate 2, and the second port of the rectangular shell is sealed by the second sealing plate 3. Optionally, a sealing belt is provided on one side of the first sealing plate 2 and the second sealing plate 3, and the shape of the sealing belt is consistent with the shape of the first port and the second port. After the first sealing plate 2 and the second sealing plate 3 are connected to the limit seat 1, the sealing belt can seal the first port and the second port to prevent gas leakage from the first port and the second port. Among them, the first sealing plate 2 and the second sealing plate 3 are U-shaped plates, and the two opposite side plates of the U-shaped plate are respectively connected to the limit seat 1 by a bolt structure or a slot structure. Using the detection tooling of the above embodiment, the shell can be sealed, so that the shell can be tested for gas leakage when the shell is a semi-finished product, effectively reducing the defective rate of the battery after the shell is processed into a battery.

[0050] In some embodiments of the present application, the limit seat 1 includes a bottom plate 11, a first side plate 12, a second side plate 13 and a limit member 4. The bottom plate 11 is arranged on the bottom wall of the water tank; the first side plate 12 is vertically arranged on one side edge of the bottom plate 11; the second side plate 13 is vertically arranged on the other side edge of the bottom plate 11, and the second side plate 13 is arranged opposite to the first side plate 12; the limit member 4 can be connected with the first side plate 12 and the second side plate 13 so that the first side plate 12 and the second side plate 13 are respectively against the opposite sides of the shell. Specifically, the limit member 4 is U-shaped and is clamped above the first side plate 12 and the second side plate 13. After the shell is inserted into the limit seat 1, the limit member 4 is connected with the first side plate 12 and the second side plate 13 through a bolt structure or a slot structure, so that the first side plate 12 and the second side plate 13 are against each other with the shell. By providing the first side plate 12 and the second side plate 13, when the shell is tested, the first side plate 12 and the second side plate 13 are respectively pressed against opposite sides of the shell, which can not only fix the position of the shell, but also reduce the deformation of the shell during the airtightness test.

[0051] Before testing the shell, place the shell to be tested on the limit seat 1, between the first side plate 12 and the second side plate 13; install the first sealing plate 2 on the left side of the limit seat, so that the first sealing plate 2 blocks the first port of the shell, and install the second sealing plate 3 on the right side of the limit seat, so that the second sealing plate 3 blocks the second port of the shell; then buckle the limit member 4 on the top of the limit seat 1, and after tightening the bolts, under the extrusion of the limit member 4, the opposite sides of the shell to be tested are respectively abutted against the first side plate 12 and the second side plate 13; after the water tank is filled with water, test the shell, and use the exhaust air compressor to pump air into the shell through the inflation port of the first sealing plate 2. The cavity is inflated, and pressurization is started from the pressure of the first gradient, for example, from 0.2MPa. The pressures of two adjacent gradients differ by a preset difference, for example, a difference of 0.05MPa, and the pressure of each gradient is maintained for a preset time, for example, the pressure of each gradient is maintained for 20 seconds; observe whether bubbles appear on the water surface, if so, it is determined that there is leakage in the shell, and the pressure of the current gradient is determined as the critical pressure of the shell; if not, the pressurization is continued until the pressure rises to the highest gradient, and inflation is stopped, for example, the pressure rises to 0.8MPa, and the shell still does not leak, and the critical pressure of the shell is determined to be the pressure of the highest gradient; after the detection is completed, the shell is removed from the tooling.

[0052] Table 1 Comparison of shell weld strength after helium inspection and water inspection

[0053] At present, the helium leak rate is used to determine whether the weld strength of the shell produced under the corresponding process parameters can meet the standard. The qualified helium leak rate value is 9.9*10-7Pa·m 3 / s, that is, when the helium leak rate of the shell is less than or equal to 9.9*10-7Pa·m 3 / s, the shell is determined to be qualified; when the helium leak rate of the shell is greater than 9.9*10-7Pa·m 3 / s, it is determined that the shell inspection fails.

[0054] From Table 1, it can be seen that the helium leak detection rates of the shells of Comparative Examples 1-6 are all less than 9.9*10-7Pa·m 3 / s, that is, the helium leak rate can be used to determine that the weld strengths of the shells of Comparative Examples 1-6 are all qualified. However, during the water test, the shells of Comparative Examples 1-6 still leak under different water pressures. Therefore, it is obviously unreasonable to determine whether the weld strength of the shell produced under the corresponding process parameter conditions can meet the standard by the helium leak rate, and it is more accurate to determine whether the weld strength of the shell produced under the corresponding process parameter conditions can meet the standard by water test.

[0055] Table 2 Comparison of shell weld strength after helium inspection

[0056] From Table 2, it can be seen that the helium leak detection rates of the shells of Comparative Examples 1, 4 and 6 are all less than 9.9*10-7Pa·m 3 / s, that is, the helium leak rate can be used to determine that the weld strengths of the shells of Comparative Examples 1, 4, and 6 are all qualified. However, during the metallographic detection process of the shells of Comparative Examples 1, 4, and 6 after being pulled apart, the fracture position will still be at the weld. Therefore, the method of judging whether the weld strength of the shell produced under the corresponding process parameter conditions can meet the standard by the helium leak rate is obviously unreasonable. It can be seen that by performing metallographic detection on the broken shells, a batch of shells with unqualified strength can be further screened out, improving the accuracy of shell detection, and facilitating more accurately determining the weld strength level corresponding to the shells with different process parameters, so as to more accurately adjust the process parameters.

[0057] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0058] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0059] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0060] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0061] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A shell detection method, characterized in that: include: Performing gas leakage detection on shells with the same process parameters respectively, and obtaining the critical pressure when the shells start to leak respectively; Determine, according to the critical pressure, the weld strength qualification rate of the shell welded under the process parameters and the critical pressure concentration distribution value; The weld strength grade of the shell welded under the process parameters is determined according to the weld strength qualification rate and the critical pressure concentration distribution value.

2. The shell detection method according to claim 1, characterized in that: The step of performing gas leakage detection on the shells with the same process parameters respectively and obtaining the critical pressure when the shells start to leak respectively includes: Inflate the inner cavities of the shells with the same process parameters respectively to control the pressure increase of the inner cavities of the shells; During the process of the pressure rising in the inner cavity of the shell, it is determined whether the shell is leaking, and the pressure corresponding to when the shell starts to leak is determined as the critical pressure.

3. The shell detection method according to claim 2, characterized in that: The step of respectively charging the inner cavities of the shells with the same process parameters to control the pressure rise in the inner cavities of the shells comprises: The pressure of the inner cavity of the shell with the same process parameters is controlled to increase in a gradient from a first preset pressure until the shell leaks or the pressure of the inner cavity of the shell rises to a second preset pressure, and the inflation is stopped. The pressures of two adjacent gradients differ by a preset difference, and the pressure of each gradient is maintained for a preset time.

4. The shell detection method according to claim 2, characterized in that: The determining whether the housing is leaking includes: The shell is placed below the liquid surface of the liquid medium. During the process of inflating the inner cavity of the shell, if bubbles appear on the liquid surface, it is determined that the shell is leaking; if no bubbles appear on the liquid surface, it is determined that the shell is not leaking.

5. The shell detection method according to any one of claims 1 to 4, characterized in that: The method of determining the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under the process parameters according to the critical pressure includes: If the critical pressure is less than or equal to the standard pressure, it is determined that the weld strength of the shell is unqualified; if the critical pressure is greater than the standard pressure, it is determined that the weld strength of the shell is qualified; The critical pressure concentration distribution value is the pressure value corresponding to the gradient where the number of shells with air leakage is the largest.

6. The shell detection method according to claim 5, characterized in that: The method of determining the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under the process parameters according to the critical pressure also includes: Breaking off the two ends of the shell where the critical pressure is greater than the standard pressure, and performing metallographic testing on the broken shell; It is determined whether the fracture of the shell overlaps with the weld. If so, it is determined that the strength of the weld of the shell is unqualified; if not, it is determined that the strength of the weld of the shell is qualified.

7. The shell detection method according to any one of claims 1 to 4, characterized in that: The step of determining the weld strength grade of the shell welded under the process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value comprises: If the qualified rate is greater than or equal to the standard qualified rate, and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is determined to be level one; If the qualified rate is less than the standard qualified rate and the critical pressure concentration distribution value is greater than the standard pressure, the weld strength grade is determined to be level 2; If the qualified rate is less than the standard qualified rate and the critical pressure concentration distribution value is less than or equal to the standard pressure, the weld strength grade is determined to be grade three.

8. A shell detection device, characterized in that: The shell detection method according to any one of claims 1 to 7 is used to perform gas leakage detection on shells with the same process parameters respectively, and the detection device comprises: An air leakage detection module is used to perform air leakage detection on shells with the same process parameters respectively, and obtain the critical pressure when the shells start to leak; A first determination module is used to determine the weld strength qualification rate and the critical pressure concentration distribution value of the shell welded under the process parameters according to the critical pressure; The second determination module is used to determine the weld strength grade of the shell welded under the process parameters according to the weld strength qualification rate and the critical pressure concentration distribution value.

9. A shell detection tool, characterized in that: The detection tool is used to perform air leakage detection on shells with the same process parameters by executing the shell detection method according to any one of claims 1 to 7, wherein the shell has a first port and a second port arranged opposite to each other, and the detection tool comprises: Water tank; A limiting seat, arranged in the water tank, having a U-shaped groove for placing the shell; A first sealing plate, used for sealing the first port, having an inflation port; The second sealing plate is used to seal the second port.

10. A method for optimizing shell process parameters, characterized in that: The shell detection method comprising any one of claims 1 to 7, further comprising: adjusting the process parameters according to the weld strength grade, the process parameters comprising at least one of heat affected zone ratio, annular beam power, center beam power, welding speed, defocus amount, weld trajectory, nitrogen flow, nitrogen dryness and dust removal wind speed.

Images