Laser welding assembly, laser welding defect detection method and system

Abstract

The embodiment of the present application discloses a laser welding assembly, a laser welding defect detection method and a system. The laser welding assembly includes a welding kit and a temperature sensor, the welding kit is provided with a laser incident through hole that penetrates the corresponding first end and second end of the welding kit, the temperature sensor is arranged between the first end of the welding kit and the bus, one end of the temperature sensor is connected to the first end of the welding kit, the other end of the temperature sensor is abutted against the bus, and a surface of the bus away from the temperature sensor is abutted against a battery cell pole, and then in the process of laser welding between the bus and the battery cell pole, the firmness of the weld between the bus and the battery cell pole can be timely determined according to the temperature information detected by the temperature sensor, and corresponding processing is performed, which greatly improves the yield rate of laser welding between the bus and the battery cell pole and reduces the cost of laser welding between the bus and the battery cell pole.

Description

Technical Field

[0001] The present application relates to the field of laser welding technology, and in particular to a laser welding assembly, a laser welding defect detection method and a system. Background Art

[0002] Laser welding between the aluminum busbar and the battery cell pole can not only achieve a deeper level of fusion, but also ensure stable welding quality and firm welds, and can effectively avoid damage to surrounding sensitive components, thereby improving the overall stability and safety of the battery.

[0003] In the related art, in order to ensure the quality of laser welding between the aluminum bar and the battery cell pole, it is usually necessary to perform destructive testing on the welded samples to ensure that the weld between the aluminum bar and the battery cell pole is firm. Although this method can determine the firmness of the weld between the aluminum bar and the battery cell pole, it cannot ensure that all welds between the aluminum bar and the battery cell pole are firm. Summary of the invention

[0004] In response to the deficiencies in the prior art, the present application provides a laser welding assembly, a laser welding defect detection method and a system, which can test the weld firmness between the aluminum busbar and the battery cell pole during the welding process, thereby avoiding the technical problem of poor weld firmness between the aluminum busbar and the battery cell pole after welding.

[0005] To solve the above problems, in a first aspect, the present application provides a laser welding assembly, which includes:

[0006] A welding kit is provided with a laser incident through hole penetrating a first end and a second end of the welding kit, wherein the first end and the second end are two corresponding ends of the welding kit;

[0007] The temperature sensor is arranged between the first end of the welding kit and the bus bar, one end of the temperature sensor is connected to the first end of the welding kit, the other end of the temperature sensor abuts against the bus bar, and a surface of the bus bar away from the temperature sensor abuts against the battery cell pole.

[0008] Further, in the laser welding assembly provided in the present application, the first end is provided with an abutment portion, and the abutment portion is connected to one end of the temperature sensor;

[0009] The second end is provided with a connecting portion, and the connecting portion is fixedly connected to the welding machine.

[0010] Furthermore, in the laser welding assembly provided in the present application, the distance between the temperature sensor and the welding point in the laser incident through hole is 2 to 10 mm.

[0011] Furthermore, in the laser welding assembly provided in the present application, the temperature sensor is an annular temperature sensor, and the annular temperature sensor and the laser incident through hole are co-centered.

[0012] Furthermore, in the laser welding assembly provided in the present application, a heat insulating member is provided between the welding kit and the temperature sensor, one end of the heat insulating member is connected to the temperature sensor, and the other end of the heat insulating member is connected to the welding kit.

[0013] Furthermore, in the laser welding assembly provided in the present application, a first annular groove is provided at one end of the heat insulating member, and the first annular groove is configured to embed a temperature sensor;

[0014] The other end of the heat insulating member is provided with a second annular groove, and the second annular groove is configured to be embedded with the first end.

[0015] Further, in the laser welding assembly provided in the present application, the temperature sensor includes a PN junction temperature sensor or a platinum resistance temperature sensor; or / and,

[0016] The welding kit includes the welding copper sleeve.

[0017] In a second aspect, the present application further provides a laser welding defect detection method, which is applied to the laser welding assembly of the first aspect, and the laser welding defect detection method comprises:

[0018] Obtaining a first temperature for laser welding between the busbar and the cell pole;

[0019] If the first temperature is not within the preset temperature range, it is determined that there is a welding defect between the bus bar and the battery cell pole.

[0020] Furthermore, in the laser welding defect detection method, after obtaining the first temperature of laser welding between the busbar and the cell pole, it also includes:

[0021] Determine a welding time corresponding to the first temperature;

[0022] Determine the temperature range based on the welding time.

[0023] Furthermore, in the laser welding defect detection method, the temperature range is determined according to the welding time, including:

[0024] When laser welding the busbar and the battery cell pole using multiple welding powers, a temperature curve of the laser welding temperature changing with time under each welding power is obtained;

[0025] The second temperature and the third temperature of the temperature range are determined according to the plurality of temperature curves and the welding time.

[0026] Furthermore, in the laser welding defect detection method, determining the second temperature and the third temperature of the temperature range according to the plurality of temperature curves and the welding time includes:

[0027] Determine a fourth temperature corresponding to each temperature curve according to the welding time;

[0028] The second temperature and the third temperature are determined from a plurality of fourth temperatures.

[0029] In a third aspect, the present application also provides a laser welding detection system, which is applied to the laser welding defect detection method provided in the second aspect.

[0030] The laser welding assembly provided in the present application includes a welding kit and a temperature sensor. The welding kit is provided with a laser incident through hole which passes through the corresponding first end and second end of the welding kit. The temperature sensor is arranged between the first end of the welding kit and the bus. One end of the temperature sensor is connected to the first end of the welding kit, and the other end of the temperature sensor is abutted against the bus. A surface of the bus away from the temperature sensor is abutted against a battery cell pole. Therefore, during the process of laser welding between the bus and the battery cell pole, the firmness of the weld between the bus and the battery cell pole can be timely determined according to the temperature information detected by the temperature sensor, and corresponding processing can be performed, which greatly improves the yield rate of laser welding between the bus and the battery cell pole and reduces the cost of laser welding between the bus and the battery cell pole. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A structural diagram of a laser welding assembly provided in an embodiment of the present application at a first viewing angle;

[0033] Figure 2 A structural diagram of a laser welding assembly provided in an embodiment of the present application at a second viewing angle;

[0034] Figure 3 A structural diagram of a laser welding assembly provided in an embodiment of the present application at a third viewing angle;

[0035] Figure 4 A cross-sectional view of a laser welding assembly provided in an embodiment of the present application;

[0036] Figure 5 A top view of a laser welding assembly provided in an embodiment of the present application;

[0037] Figure 6 An exploded view of a laser welding assembly provided in an embodiment of the present application;

[0038] Figure 7A schematic diagram of the structure of a temperature sensor provided in an embodiment of the present application;

[0039] Figure 8 A schematic diagram of the structure of the heat insulation member provided in the embodiment of the present application;

[0040] Fig. 9 Another schematic diagram of the thermal insulation provided by the embodiment of the present application;

[0041] Fig.10 A schematic diagram of the structure of a welding kit provided in an embodiment of the present application;

[0042] Fig.11 A top view of a laser welding assembly provided in an embodiment of the present application on a battery cell;

[0043] Fig.12 A schematic diagram of a bus bar and a battery cell pole after welding provided in an embodiment of the present application;

[0044] Fig.13 A connection diagram of a laser welding assembly provided in an embodiment of the present application;

[0045] Fig.14 A schematic diagram of a process for detecting laser welding defects provided in an embodiment of the present application;

[0046] Fig.15 A temperature curve at a welding position between a busbar and a battery cell pole provided in an embodiment of the present application;

[0047] Fig.16 A schematic block diagram of a laser welding defect detection system provided in an embodiment of the present application.

[0048] Among them, 101 is a welding kit, 1011 is a laser incident through hole, 1012 is a connecting part, 1013 is abutting part, 102 is a temperature sensor, 103 is a heat insulating member, 1031 is a first annular groove, 1032 is a second annular groove, 104 is a controller, 105 is a laser, 106 is a galvanometer, 107 is a laser beam, 108 is a human-machine interface, 109 is a warning light, 201 is a bus, 2011 is a pole area, 300 is a battery cell, 301 is a battery cell pole, 302 is a battery cell cover, and 400 is a welding point. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. 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 this field without creative work are within the scope of protection of this application.

[0050] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0051] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0052] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0053] In addition, in this application, unless otherwise clearly specified or limited in the embodiments, the terms "installed", "connected", "connected" and "fixed" etc. appearing in the embodiments should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integrated connection. It can be understood that it can also be a mechanical connection, an electrical connection, etc.; of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements, or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific implementation situation.

[0054] In the related art, when detecting the laser welding defects between the busbar 201 and the battery pole 301, the welding position between the aluminum busbar and the battery pole 301 after welding is usually detected by two-dimensional detection to determine the fusion depth and fusion width of the welding position, or the appearance defect detection is performed by taking pictures. For the weld firmness test between the aluminum busbar and the battery pole 301 after welding, only a small amount of samples are taken from the welded product to test the weld firmness between the aluminum busbar and the battery pole 301 after welding, and the samples need to be destroyed during the test process. Not only can the weld firmness of each welded product not be determined, but the test cost is also high.

[0055] In order to solve the above-mentioned technical problems, the present application provides a laser welding assembly, a laser welding defect detection method and a system, which can test the weld firmness between the aluminum busbar and the battery cell pole 301 during the welding process, thereby avoiding the technical problem of poor weld firmness between the aluminum busbar and the battery cell pole 301 after welding.

[0056] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the present application provides a laser welding assembly, which includes:

[0057] The welding kit 101 is provided with a laser incident through hole 1011 penetrating through the first end and the second end of the welding kit 101, and the first end and the second end are two corresponding ends of the welding kit 101;

[0058] The temperature sensor 102 is arranged between the first end of the welding kit 101 and the bus 201. One end of the temperature sensor 102 is connected to the first end of the welding kit 101, and the other end of the temperature sensor 102 abuts against the bus 201. A surface of the bus 201 away from the temperature sensor 102 abuts against the battery cell pole 301.

[0059] Specifically, when laser welding is performed between the busbar 201 and the battery pole 301, the laser light generated by the laser 105 can be emitted into the laser incident through hole 1011 on the welding kit 101 through the galvanometer 106, and reach the welding position between the busbar 201 and the battery pole 301 through the laser incident through hole 1011, so as to realize laser welding of the busbar 201 and the battery pole 301. The battery cell where the battery pole 301 is located can be a lithium battery cell 300. Fig.13 As shown, a cell cover 302 is disposed above the lithium cell 300 , and a cell pole 301 is disposed on the cell cover 302 .

[0060] At the same time, the reason why the present application chooses the temperature sensor 102 instead of using non-contact infrared temperature to collect the temperature at the welding position between the bus 201 and the battery cell pole 301 is mainly because the non-contact infrared temperature recognition has large temperature fluctuations during laser welding, resulting in large temperature collection deviations, low reliability and accuracy. The temperature sensor 102 will not have the problem of large temperature fluctuations during laser welding.

[0061] In addition, the busbar 201 mentioned in the present application may be an aluminum busbar, but is not limited thereto. The type of the busbar 201 may be selected according to actual applications.

[0062] In this embodiment, during the laser welding process at the welding position between the busbar 201 and the battery cell pole 301, the temperature sensor 102 can monitor the temperature at the welding position at any time. When the temperature at the welding position is low, it can be determined that there is a defect in the laser welding between the busbar 201 and the battery cell pole 301; when the temperature at the welding position is high, it can also be determined that there is a defect in the laser welding between the busbar 201 and the battery cell pole 301. When it is determined that there is a defect in the laser welding between the busbar 201 and the battery cell pole 301, it is necessary to immediately stop the operation of the laser 105 so as to timely confirm the welding status between the busbar 201 and the battery cell pole 301 and repair it, which can not only ensure the firmness of the welding position between each busbar 201 and the battery cell pole 301 after welding, but also improve the yield rate of the laser welding between the busbar 201 and the battery cell pole 301.

[0063] The laser welding assembly provided in the present application includes a welding kit 101 and a temperature sensor 102. The welding kit 101 is provided with a laser incident through hole 1011 which passes through the corresponding first and second ends of the welding kit 101. The temperature sensor 102 is arranged between the first end of the welding kit 101 and the bus 201. One end of the temperature sensor 102 is connected to the first end of the welding kit 101, and the other end of the temperature sensor 102 is abutted against the bus 201. A surface of the bus 201 away from the temperature sensor 102 is abutted against the battery cell pole 301. Therefore, during the process of laser welding between the bus 201 and the battery cell pole 301, the firmness of the weld between the bus 201 and the battery cell pole 301 can be timely determined according to the temperature information detected by the temperature sensor 102, and corresponding processing can be performed, which greatly improves the yield rate of laser welding between the bus 201 and the battery cell pole 301 and reduces the cost of laser welding between the bus 201 and the battery cell pole 301.

[0064] In some embodiments, Fig.10 As shown, a first end is provided with an abutting portion 1013, which is connected to one end of the temperature sensor 102; a second end is provided with a connecting portion 1012, which is fixedly connected to the welding machine.

[0065] In this embodiment, the laser welding assembly can be fixed on the welding machine, and the welding machine can be provided with a laser 105 and a galvanometer 106. When the welding machine uses the laser welding assembly to weld the bus 201 and the battery cell pole 301, the abutment portion 1013 at the second end of the welding kit abuts the bus 201 through the temperature sensor 102, and the laser emitted by the laser passes through the galvanometer 106 and the laser incident through-hole 1011 in sequence to achieve laser welding of the bus 201 and the battery cell pole 301. Among them, the abutment portion can be set in a funnel shape, the connecting portion can be set in a rectangular block shape, a plurality of through holes can be set on the connecting portion, and screws can pass through the through holes to fix the laser welding assembly on the welding machine.

[0066] In some embodiments, the distance between the inner ring of the annular temperature sensor 102 and the welding point 400 in the laser incident through hole 1011 is 2-10 mm.

[0067] Specifically, Fig.11 As shown, the busbar 201 provided in the present application is rectangular in shape, and the battery pole 301 is cylindrical. The busbar 201 covers the battery pole 301. Therefore, when laser welding is performed between the busbar 201 and the battery pole 301, it is necessary to contact the busbar 201 with the battery pole 301 at the contact position, that is, Fig.11 At the pole area 2011 in the middle, laser welding is performed around the cell pole 301, so that the bus 201 and the cell pole 301 are laser welded to form a Fig.12 The weld points 400 of the circular ring are shown.

[0068] In some embodiments, Figures 1 to 7 As shown, the temperature sensor 102 is an annular temperature sensor 102 , and the annular temperature sensor and the laser incident through hole 1011 are co-centered.

[0069] Since the laser beam 107 enters the laser incident hole from the second end of the welding kit 101 and reaches the welding point 400 between the bus 201 and the battery cell pole 301 through the laser incident hole, and the welding point 400 is a circular ring, the temperature sensor 102 cannot be placed inside the circular ring. Therefore, the present application needs to set the temperature sensor 102 as a ring-shaped temperature sensor 102 to ensure that during the laser welding process at the welding position between the bus 201 and the battery cell pole 301, the temperature sensor 102 can monitor the temperature at the welding position at any time.

[0070] In addition, when the wake-up temperature sensor 102 is set at the first end of the welding kit 101, it is necessary to ensure that the distance between the annular temperature sensor 102 and the welding point 400 in the laser incident hole 1011 is between 2 and 10 mm to avoid being too close to the laser beam 107, which may cause the temperature sensor 102 to be damaged due to excessive temperature.

[0071] In some embodiments, Figures 1 to 6 As shown, a heat insulating member 103 is further provided between the welding kit 101 and the temperature sensor 102 , one end of the heat insulating member 103 is connected to the temperature sensor 102 , and the other end of the heat insulating member 103 is connected to the welding kit 101 .

[0072] In this embodiment, the welding kit 101 is a kit made of metal material, which has good thermal conductivity. In order to prevent the welding kit 101 from directly contacting the temperature sensor 102 and affecting the temperature sensor 102 collecting the temperature of the welding point 400 between the bus 201 and the battery cell pole 301, the present application also needs to set a heat insulation member 103 between the temperature sensor 102 and the welding kit 101, thereby ensuring the accuracy of the temperature sensor 102 collecting the temperature at the welding position.

[0073] The heat insulating member 103 may include at least one of zirconium oxide and silicon oxide. Preferably, the heat insulating member 103 may be a composite oxide composed of zirconium oxide and silicon oxide, which can ensure that the temperature sensor 102 collects the temperature at the welding position without being affected by the welding kit 101.

[0074] In some embodiments, Figure 8 and Fig. 9 As shown, a first annular groove 1031 is provided at one end of the thermal insulation member 103, and the first annular groove 1031 is configured to embed the temperature sensor 102; a second annular groove 1032 is provided at the other end of the thermal insulation member 103, and the second annular groove 1032 is configured to embed the abutment portion 1013 of the first end.

[0075] Specifically, by setting a first annular groove 1031 at one end of the thermal insulation member 103 and a second annular groove 1032 at the other end of the thermal insulation member 103, when assembling the laser welding assembly, the temperature sensor 102 can be directly embedded in the first annular groove 1031, and the abutment portion 1013 of the welding kit can be directly embedded in the second annular groove 1032, so that when the laser welding assembly is used for assembly line operation, the laser welding assembly can be quickly moved from one welding area to another welding area through a welding machine.

[0076] In addition, after the temperature sensor 102 is embedded in the first annular groove 1031, the other end of the temperature sensor 102 away from the first annular groove 1031 needs to abut against the bus 201 to avoid inaccurate temperature detection due to obstruction of the thermal insulation component 103 during welding.

[0077] In some embodiments, the welding kit 101 and the temperature sensor 102 are bonded with an adhesive.

[0078] Specifically, the adhesive can be used to bond the temperature sensor 102 to the first end of the welding kit 101. At the same time, the adhesive must have good bonding effect and good high temperature resistance, thereby avoiding the separation of the temperature sensor 102 and the welding kit 101 due to high temperature during the laser welding process between the bus 201 and the battery cell pole 301.

[0079] Furthermore, when a heat insulating member 103 is provided between the welding kit 101 and the temperature sensor 102 , the heat insulating member 103 and the abutting portion 1013 of the welding kit 101 are bonded with an adhesive, and the heat insulating member 103 and the temperature sensor 102 can also be bonded with an adhesive.

[0080] In some embodiments, the temperature sensor 102 includes a PN junction temperature sensor or a platinum resistance temperature sensor.

[0081] In this embodiment, the temperature sensor 102 preferably selects a PN junction temperature sensor and a platinum resistance temperature sensor. Among them, the PN junction temperature sensor is a device that uses the temperature characteristics of semiconductor materials to measure temperature changes. Its working principle is based on the fact that when the PN junction is forward biased, as the temperature increases, the equivalent resistance will decrease, thereby causing the voltage across the PN junction to change, thereby making the PN junction temperature sensor have the characteristics of high sensitivity and fast response, and usually completes temperature measurement within microseconds.

[0082] Specifically, when a forward voltage is applied to the PN junction, it presents a low resistance state with a large forward diffusion current; when a reverse voltage is applied, it presents a high resistance state with a small reverse drift current. Therefore, by measuring the change in the forward voltage drop or reverse current of the PN junction at different temperatures, accurate temperature measurement can be achieved. In addition, the PN junction temperature sensor also has the advantages of good linearity, small time constant and fast response speed.

[0083] Among them, the temperature measurement range of the PN junction temperature sensor is between -50℃ and 150℃. Therefore, when using the PN junction temperature sensor to collect the temperature of the welding point 400 between the bus 201 and the battery cell pole 301, it is necessary to ensure that the distance between the PN junction temperature sensor and the welding point 400 in the laser incident through hole 1011 is between 2 and 10 mm to avoid being too close to the laser beam 107, which may cause the PN junction temperature sensor to be damaged due to excessive temperature.

[0084] The platinum resistance temperature sensor is a sensor that measures temperature based on the property that the resistance value of metal platinum changes with temperature. Its working principle is to measure the resistance value of the platinum resistor at different ambient temperatures and calculate the corresponding temperature value based on the preset resistance-temperature relationship curve. Among them, the core part of the platinum resistance temperature sensor is a slender filament resistor made of pure platinum. When the ambient temperature changes, the resistance value of the platinum wire will also change, which can be detected and converted by the circuit system and finally displayed as a temperature value.

[0085] In some embodiments, the welding kit 101 includes a welding copper sleeve. In this embodiment, the shape of the welding copper sleeve is similar to a funnel, and a temperature sensor 102 is set at the bottom of the welding copper sleeve, and the bus 201 can be abutted against the battery cell pole 301 through the temperature sensor 102, and the laser beam 107 can be shot from the through hole of the welding copper sleeve to the welding position between the bus 201 and the battery cell pole 301. It should be noted that the welding kit 101 can also be a metal kit of other materials, which can be selected according to actual applications, and this application does not make specific limitations.

[0086] In some embodiments, Fig.13 As shown, the laser welding assembly further includes a control module 104 and a display module; wherein the control module 104 is electrically connected to the display module, the laser 105 and the temperature sensor 102 respectively.

[0087] In this embodiment, the control module 104 can control the opening and closing of the laser 105, and the temperature sensor 102 can be electrically connected to the control module 104, so that the temperature of the welding point 400 between the bus 201 and the battery cell pole 301 collected by the temperature sensor 102 can be transmitted to the control module 104 for calculation and comparison to determine whether there is a welding defect at the welding position, and it can be displayed by the display module. Among them, the display module includes a human-machine interface 108 and a warning light 109. If there is a welding defect at the welding position, the warning light 109 can be used to prompt.

[0088] It can be understood that the laser welding assembly provided in the above embodiment is only an example. The laser welding assembly described in the embodiment of the present application is to more clearly illustrate the technical solution of the embodiment of the present application, and does not constitute a limitation on the technical solution provided in the embodiment of the present application. A person of ordinary skill in the art can know that with the evolution of laser welding assemblies and the emergence of new business scenarios, the technical solution provided in the embodiment of the present application is also applicable to similar technical problems. The following is a detailed description.

[0089] It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments. The thermal runaway management method is described in detail below. At the same time, the laser welding defect detection method provided in this application can be executed by the control module 104 in the laser welding assembly.

[0090] See also Fig.14 , Fig.14 The following is a flow chart of the laser welding defect detection method provided in the embodiment of the present application. Fig.14 As shown, the present application also provides a laser welding defect detection method, which includes steps S110 and S120.

[0091] S110, obtaining a first temperature for laser welding between the busbar and the cell pole.

[0092] Specifically, the first temperature is the temperature information collected by the temperature sensor 102 at the welding position between the busbar 201 and the cell pole 301 during the laser welding process between the busbar 201 and the cell pole 301. After collecting the first temperature at the welding position between the busbar 201 and the cell pole 301, the temperature sensor 102 can transmit it to the control module 104, and then the control module 104 can determine whether there is a problem such as loose welding at the welding position based on the first temperature, so that the laser 105 can be stopped quickly, and the welding state between the busbar 201 and the cell pole 301 can be confirmed, and repair can be carried out in time, which can not only ensure the firmness of the welding position between each busbar 201 and the cell pole 301 after welding, but also improve the yield rate of the laser welding between the busbar 201 and the cell pole 301.

[0093] In some embodiments, after step S110, the method further includes: determining a welding time corresponding to the first temperature; and determining a temperature range according to the welding time.

[0094] Specifically, when the present application uses the first temperature to determine whether there is a welding defect between the busbar 201 and the battery cell pole 301, it is determined by judging whether the first temperature is within a preset temperature range. The temperature range can be determined according to the welding time corresponding to the first temperature.

[0095] In this embodiment, the welding time of laser welding between the busbar 201 and each battery cell pole 301 can be preset, and the welding time can be divided into multiple time periods, each time period corresponds to a temperature range of laser welding, and then after obtaining the first temperature, the welding time of the first temperature can be determined, and the corresponding time period can be determined according to the welding time, and then the corresponding temperature range can be determined according to the corresponding time period, so that by judging whether the first temperature is within the preset temperature range, it can be determined whether there is a welding defect between the busbar 201 and the battery cell pole 301. Among them, the welding time can be 3s, and the temperature acquisition time interval at the welding position can be between 10 and 30ms.

[0096] In some embodiments, the temperature range is determined according to the welding time, including: when laser welding the bus and the battery cell poles using multiple welding powers, obtaining a temperature curve of the laser welding temperature changing with time at each welding power; and determining the second temperature and the third temperature of the temperature range according to the multiple temperature curves and the welding time.

[0097] Specifically, the present application can pre-use different laser powers, that is, multiple welding powers, to perform laser welding on the busbar 201 and the battery pole 301. The temperature sensor 102 can be used to collect the temperature of the busbar 201 and the battery pole 301 that are laser welded at each welding power. After obtaining the temperature collected at each welding power, the collected temperature at each welding power can be fitted to obtain a temperature curve of the temperature changing over time at each welding power. After that, the firmness of the welding position at each welding power can be tested to determine the temperature curve that can be adopted, and then the temperature curve can be obtained. Fig.15 Multiple temperature curves are shown, such as a first temperature curve a and a second temperature curve b.

[0098] After determining multiple temperature curves at the welding position between the busbar 201 and the battery cell pole 301, the maximum temperature and the minimum temperature, i.e., the second temperature and the third temperature, can be found from the multiple temperature curves at different times, and then the temperature between the minimum temperature and the maximum temperature can be used as the temperature within the temperature range mentioned in this application. Among them, the temperature curve corresponding to the maximum temperature can be the first temperature curve a, and the temperature curve corresponding to the minimum temperature can be the second temperature curve b.

[0099] It should be noted that when the present application uses multiple welding powers for laser welding, the busbar 201 and battery cell pole 301 used can be used as samples, which are not the busbar 201 and battery cell pole 301 in step S110.

[0100] In some embodiments, determining the second temperature and the third temperature of the temperature range according to multiple temperature curves and welding time includes: determining the fourth temperature corresponding to each temperature curve according to the welding time; and determining the second temperature and the third temperature from the multiple fourth temperatures.

[0101] Specifically, after obtaining multiple temperature curves, the present application can find a temperature value, i.e., the fourth temperature, from each temperature curve according to the welding time, and each temperature value is within the temperature range mentioned in the present application. Then, the multiple temperature values ​​found are statistically analyzed to obtain the maximum temperature and the minimum temperature within the temperature range, i.e., the second temperature and the third temperature.

[0102] S120: If the first temperature is not within a preset temperature range, determine that there is a welding defect between the busbar and the battery cell pole.

[0103] Specifically, when the first temperature is within the preset temperature range, it can be determined that the laser welding between the bus 201 and the battery cell pole 301 is in a normal state; when the first temperature is lower than the minimum temperature within the temperature range, it can be determined that the laser welding between the bus 201 and the battery cell pole 301 is in an abnormal state, and it is necessary to stop the laser 105 to stop welding at the welding position between the bus 201 and the battery cell pole 301, and give an alarm, and at the same time detect whether the laser welding between the bus 201 and the battery cell pole 301 is normal. If an abnormality is detected, maintenance and adjustment are required; when the first temperature is greater than the minimum temperature within the temperature range, it can be determined that the laser welding between the bus 201 and the battery cell pole 301 is in an abnormal state, and it is necessary to stop the laser 105 to stop welding at the welding position between the bus 201 and the battery cell pole 301, and give an alarm, and at the same time detect whether the laser welding between the bus 201 and the battery cell pole 301 is normal. If an abnormality is detected, maintenance and adjustment are required.

[0104] For example, Fig.15 As shown, after obtaining the first temperature of laser welding between the busbar 201 and the battery cell pole 301, the welding time corresponding to the first temperature is determined, such as time t1, and then the Fig.15 By comparing whether the first temperature is between T2 and T1, it can be determined whether there is a welding defect between the busbar 201 and the cell pole 301. If the first temperature is between T2 and T1, it can be determined that there is no welding defect between the busbar 201 and the cell pole 301; if the first temperature is not between T2 and T1, it can be determined that there is a welding defect between the busbar 201 and the cell pole 301.

[0105] The laser welding defect detection method provided in the present application obtains the first temperature for laser welding between the bus 201 and the battery cell pole 301; if the first temperature is not within the preset temperature range, it is determined that there is a welding defect between the bus 201 and the battery cell pole 301, and then during the laser welding between the bus 201 and the battery cell pole 301, the firmness of the weld between the bus 201 and the battery cell pole 301 can be timely determined according to the temperature information detected by the temperature sensor 102, and corresponding processing can be performed, which greatly improves the yield rate of laser welding between the bus 201 and the battery cell pole 301 and reduces the cost of laser welding between the bus 201 and the battery cell pole 301.

[0106] An embodiment of the present application also provides a laser welding detection system, which is used to execute any embodiment of the aforementioned laser welding detection method.

[0107] Specifically, see Fig.16 , Fig.16 A schematic block diagram of a laser welding defect detection system provided in an embodiment of the present application.

[0108] like Fig.16 As shown, the laser welding detection system includes: an acquisition unit 210 and a determination unit 220 .

[0109] The acquisition unit 210 is used to acquire the first temperature of laser welding between the busbar 201 and the battery cell pole 301; the determination unit 220 is used to determine that there is a welding defect between the busbar 201 and the battery cell pole 301 if the first temperature is not within a preset temperature range.

[0110] The laser welding defect detection system provided in the embodiment of the present application is used to execute the above-mentioned acquisition of the first temperature for laser welding between the bus 201 and the battery cell pole 301; if the first temperature is not within the preset temperature range, it is determined that there is a welding defect between the bus 201 and the battery cell pole 301, and then during the laser welding between the bus 201 and the battery cell pole 301, the firmness of the weld between the bus 201 and the battery cell pole 301 can be timely determined according to the temperature information detected by the temperature sensor 102, and corresponding processing can be performed, which greatly improves the yield rate of laser welding between the bus 201 and the battery cell pole 301 and reduces the cost of laser welding between the bus 201 and the battery cell pole 301.

[0111] It should be noted that technicians in the relevant field can clearly understand that the specific implementation process of the above-mentioned laser welding detection system and each unit can refer to the corresponding description in the aforementioned method embodiment, and for the convenience and brevity of description, it will not be repeated here.

[0112] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A laser welding assembly, characterized in that: include: A welding kit, provided with a laser incident through hole penetrating a first end and a second end of the welding kit, wherein the first end and the second end are two corresponding ends of the welding kit; A temperature sensor is disposed between the first end of the welding kit and the bus bar, one end of the temperature sensor is connected to the first end of the welding kit, the other end of the temperature sensor abuts against the bus bar, and a surface of the bus bar away from the temperature sensor abuts against a battery cell pole; Wherein, a heat insulating member is further provided between the welding kit and the temperature sensor, one end of the heat insulating member is connected to the temperature sensor, and the other end of the heat insulating member is connected to the welding kit.

2. The laser welding assembly according to claim 1, characterized in that: The first end is provided with an abutment portion, and the abutment portion is connected to one end of the temperature sensor; The second end is provided with a connecting portion, and the connecting portion is fixedly connected to the welding machine.

3. The laser welding assembly according to claim 1, characterized in that: The distance between the temperature sensor and the welding point in the laser incident through hole is 2-10 mm.

4. The laser welding assembly according to claim 3, characterized in that: The temperature sensor is an annular temperature sensor, and the annular temperature sensor and the laser incident through hole are co-centered.

5. The laser welding assembly according to claim 1, characterized in that: A first annular groove is provided at one end of the thermal insulation member, and the first annular groove is configured to embed the temperature sensor; The other end of the heat insulating member is provided with a second annular groove, and the second annular groove is configured to be embedded in the first end.

6. The laser welding assembly according to claim 1, characterized in that: The temperature sensor includes a PN junction temperature sensor or a platinum resistance temperature sensor; or / and, The welding set comprises a welding copper sleeve.

7. A laser welding defect detection method, characterized in that: The laser welding assembly according to any one of claims 1 to 6, wherein the method comprises: Acquiring a first temperature for laser welding between the busbar and the battery cell pole; If the first temperature is not within a preset temperature range, it is determined that there is a welding defect between the bus bar and the battery cell pole.

8. The laser welding defect detection method according to claim 7, characterized in that: After obtaining the first temperature for laser welding between the busbar and the cell pole, the method further includes: Determining a welding time corresponding to the first temperature; The temperature range is determined according to the welding time.

9. The laser welding defect detection method according to claim 8, characterized in that: Determining the temperature range according to the welding time includes: When laser welding the busbar and the battery cell pole is performed using multiple welding powers, a temperature curve of the laser welding temperature changing with time under each welding power is obtained; The second temperature and the third temperature in the temperature range are determined according to the plurality of temperature curves and the welding time.

10. The laser welding defect detection method according to claim 9, characterized in that: The step of determining the second temperature and the third temperature within the temperature range according to the plurality of temperature curves and the welding time comprises: Determining a fourth temperature corresponding to each of the temperature curves according to the welding time; The second temperature and the third temperature are determined from among the plurality of fourth temperatures.

11. A laser welding detection system, characterized in that: A laser welding defect detection method as described in any one of claims 7 to 10.

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