Battery pack upper and lower shell pressing method based on secondary activation

Abstract

The invention relates to the field of battery pack preparation, in particular to a battery pack upper and lower shell pressing method based on secondary activation, which comprises the following steps: acquiring the area proportion of an effective activation region; determining an initial heating mode, wherein the initial heating mode comprises a constant-speed traversal heating mode and an accelerated traversal heating mode; secondary activation of gluing is completed; pressing and pressure maintaining of the upper shell and the lower shell of the battery pack are sequentially completed; increasing the heat input power of the infrared heating device when it is determined that the press fit of the upper shell and the lower shell does not conform to the preset standard according to a constant-speed traversal heating mode, or determining the reason that the press fit does not conform to the preset standard according to the press fit characteristic area; when it is determined that press fit of the upper shell and the lower shell does not conform to the preset standard according to the accelerated traversal heating mode, the reason for determining that the press fit does not conform to the preset standard based on the bonding consistency characteristic value comprises insufficient hot melting or substandard traversal acceleration; and removing the bonding drawn wires of the battery pack of which the upper and lower shells are pressed to meet the preset standard. And the reliability of laminating and bonding the upper and lower shells of the battery pack is improved.

Description

Technical Field

[0001] The present invention relates to the field of battery pack preparation, and particularly to a method for pressing and bonding the upper and lower shells of a battery pack based on secondary activation. Background Art

[0002] With the rapid development of new energy vehicles and energy storage technologies, as the core energy carrier, the structural sealing and durability of lithium-ion battery packs directly affect the safety performance of the system. In the battery pack assembly process, the quality of pressing and bonding the upper and lower shells is a key link to ensure the isolation of the battery cell group from the environment. The traditional adhesive pressing technology has the following problems: in the conventional single pressing process, the curing process of the adhesive is prone to generate a gradient stress distribution, resulting in microcracks in the edge area of the shell; it is difficult for existing vacuum pressing equipment to completely remove the microbubbles in the high-viscosity structural adhesive; due to the CTE difference between the dissimilar material shells, the traditional thermal curing process generates an interfacial displacement of 0.15 - 0.3 mm.

[0003] The secondary activation material forms a closed-cell structure through infrared activation and has high resilience and energy absorption capacity, and has gradually become the mainstream bonding material. During the pressing process, pressure is applied through a precision mold to make the secondary-activated bonding material fully fit with the battery pack shell, eliminating the interfacial gap. During the pressure holding stage, the material deformation is maintained through a constant pressure to ensure that a stable mechanical interlock is formed between the bonding material and the shell, and at the same time, the creep characteristics of the material are used to optimize the interfacial stress distribution.

[0004] Since the liquid colloid during the first application of glue deforms during the curing process, resulting in inconsistent overall shapes before secondary activation, and fluctuations are caused by reasons such as electrical parameters and equipment aging on the production line, the stability of the colloid activation between the upper and lower shells of the battery pack is poor, thus seriously affecting the reliability of the pressing and bonding between the upper and lower shells of the battery pack. Summary of the Invention

[0005] Therefore, the present invention provides a method for pressing and bonding the upper and lower shells of a battery pack based on secondary activation to overcome the problem in the prior art that the poor stability of colloid activation caused by fluctuations in activation parameters affects the reliability of the pressing and bonding between the upper and lower shells of the battery pack.

[0006] To achieve the above object, the present invention provides a method for pressing and bonding the upper and lower shells of a battery pack based on secondary activation, including: Step S1, collecting an image of the glue-applied surface of the lower shell of the battery pack to obtain the proportion of the area of the effective activation region; Step S2, determining the initial heating method based on the comparison between the proportion of the area of the effective activation region and a preset proportion, and the initial heating method includes a uniform traversal heating method and an accelerated traversal heating method; Step S3, leaving a preset distance between the glue-applied surface of the lower shell and the surface to be bonded of the upper shell, and using an infrared heating device to complete the secondary activation of the glue according to the corresponding initial heating method; Step S4, use a press to successively complete the pressing and pressure holding of the upper and lower shells of the battery pack; Step S5, when the average value of the interface bonding strength is obtained by sampling inspection in response to the uniform traversal heating method and it is determined that the pressing of the upper and lower shells does not meet the preset standard based on this average value of the interface bonding strength, increase the heat input power of the infrared heating device, or determine that the reasons for the non-compliance of the pressing with the preset standard include that the pressing speed does not meet the standard and the traversal speed does not meet the standard according to the pressing characteristic area; the pressing characteristic area is the integral area of the pressing time-upper shell displacement curve; Step S6, when the average value of the interface bonding strength is obtained by sampling inspection in response to the accelerated traversal heating method and it is determined that the pressing of the upper and lower shells does not meet the preset standard based on this average value of the interface bonding strength, determine that the reasons for the non-compliance with the preset standard include insufficient hot melting or the traversal acceleration not meeting the standard based on the bonding consistency characteristic value; the bonding consistency characteristic value is the difference in the interface bonding strength between the initial heating area and the termination heating area of the glue-coated surface; Step S7, remove the bonding wire drawing of the battery pack with the pressing of the upper and lower shells meeting the preset standard.

[0007] Further, when it is determined that the effective activation area ratio is less than the preset ratio, determine that the initial heating method is the accelerated traversal heating method, and when the effective activation area ratio is greater than or equal to the preset ratio, determine that the initial heating method is the uniform traversal heating method.

[0008] Further, the uniform traversal heating method is that the infrared heating device covers the glue-coated surface of the lower shell of the battery pack and uniformly heats from the head end to the tail end along the long-range direction of the lower shell; the accelerated traversal heating method is that the infrared heating device covers the glue-coated surface of the lower shell of the battery pack and heats from the head end to the tail end along the long-range direction of the lower shell with a preset acceleration.

[0009] Further, in step S5, when the average value of the interface bonding strength is less than the second preset strength threshold, determine that the pressing of the upper and lower shells does not meet the preset standard; when the average value of the interface bonding strength is greater than or equal to the first preset strength threshold and less than the second preset strength threshold, determine the reasons for the non-compliance of the pressing with the preset standard according to the pressing characteristic area, and when the average value of the interface bonding strength is less than the first preset strength threshold, increase the heat input power of the infrared heating device for the next batch of pressing.

[0010] Further, the increase amplitude of the heat input power of the infrared heating device is positively correlated with the difference between the first preset strength threshold and the average value of the interface bonding strength.

[0011] Further, when the area of the pressing feature is less than the preset feature area, it is determined that the reason for not meeting the preset standard is that the pressing speed does not meet the standard, and when the area of the pressing feature is greater than or equal to the preset feature area, it is determined that the reason for not meeting the preset standard is that the traversing speed does not meet the standard.

[0012] Further, in response to the pressing speed not meeting the standard, the pressing speed of the upper and lower shells of the next batch of battery packs is reduced, and the reduction amplitude of the pressing speed of the upper and lower shells of the next batch of battery packs is positively correlated with the difference between the preset feature area and the pressing feature area; in response to the traversing speed not meeting the standard, the traversing speed of the upper and lower shells of the next batch of battery packs is reduced, and the reduction amplitude of the traversing speed of the upper and lower shells of the next batch of battery packs is positively correlated with the difference between the pressing feature area and the preset feature area.

[0013] Further, in step S6, when the average value of the interface bonding strength is less than the second preset strength threshold, it is determined that the pressing of the upper and lower shells does not meet the preset standard.

[0014] Further, in step S6, when the bonding consistency feature value is less than the preset consistency feature threshold, it is determined that the reason for not meeting the preset standard is insufficient heat melting, and when the bonding consistency feature value is greater than or equal to the preset consistency feature threshold, it is determined that the reason for not meeting the preset standard is that the traversing acceleration does not meet the standard.

[0015] Further, in response to insufficient heat melting, the heat input power for the next batch of pressing is increased, and the increase amplitude of the heat input power is positively correlated with the difference between the preset consistency feature threshold and the bonding consistency feature value; in response to the traversing acceleration not meeting the standard, the preset acceleration for the next batch of pressing is reduced, and the reduction amplitude of the preset acceleration is positively correlated with the difference between the bonding consistency feature value and the preset consistency feature threshold.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: through the real-time acquisition and comparison of the proportion of the effective activation area, the system can accurately identify the defects in the adhesive layer distribution (such as broken glue and bubble-covered areas), and dynamically select a uniform or accelerated heating mode. Compared with the traditional fixed-parameter heating, this solution reduces the ineffective energy loss by more than [X], while ensuring a high activation coverage rate of the adhesive layer and high heating consistency.

[0017] Further, the present invention realizes the phase change control of the melting - flowing - curing of the adhesive through an infrared heating strategy with a preset spacing and combined with high-pressure gradient pressure holding.

[0018] Further, the present invention introduces the integral analysis of the pressing feature area and the comparison of the bonding consistency feature value, constructs a multi-dimensional quality evaluation system, and reduces the process defect rate and shortens the single-process debugging cycle through a feedback mechanism of periodic monitoring, feedback analysis and self-optimization. Description of the Drawings

[0019] Figure 1 This is a flowchart of the method for pressing the upper and lower shells of a battery pack based on secondary activation according to an embodiment of the present invention; Figure 2 This is a schematic structural diagram of the glue - coated surface of the lower shell of the battery pack according to an embodiment of the present invention; Figure 3 This is a flowchart for determining the initial heating method according to an embodiment of the present invention; Figure 4 This is a flowchart for determining whether the pressing of the upper and lower shells meets the preset standard under the uniform traversal heating method according to an embodiment of the present invention; Figure 5 This is a flowchart for determining whether the pressing of the upper and lower shells meets the preset standard under the accelerated traversal heating method according to an embodiment of the present invention. Detailed implementation manners

[0020] In order to make the purpose and advantages of the present invention clearer and more understandable, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0022] Please refer to Figures 1 - 5 , which are respectively the flowchart of the method for pressing the upper and lower shells of a battery pack based on secondary activation according to an embodiment of the present invention; the schematic structural diagram of the glue - coated surface of the lower shell of the battery pack according to an embodiment of the present invention; the flowchart for determining the initial heating method according to an embodiment of the present invention; the flowchart for determining whether the pressing of the upper and lower shells meets the preset standard under the uniform traversal heating method according to an embodiment of the present invention; the flowchart for determining whether the pressing of the upper and lower shells meets the preset standard under the accelerated traversal heating method according to an embodiment of the present invention.

[0023] A method for pressing the upper and lower shells of a battery pack based on secondary activation according to an embodiment of the present invention includes: Step S1, collect an image of the glue - coated surface of the lower shell of the battery pack and obtain the proportion of the area of the effective activation region; Step S2, determine the initial heating method based on the comparison between the proportion of the area of the effective activation region and a preset proportion, and the initial heating method includes a uniform traversal heating method and an accelerated traversal heating method; Step S3, reserve a preset distance of 15 mm between the glue - coated surface of the lower shell and the bonding surface of the upper shell, and use an infrared heating device to complete the secondary activation of the glue according to the corresponding initial heating method; Step S4, use a press to sequentially complete the pressing and pressure - maintaining of the upper and lower shells of the battery pack; Step S5: In response to the interface bonding strength mean value obtained by sampling inspection with the uniform traversal heating method, determine whether the upper and lower shell pressing meets the preset standard according to this interface bonding strength mean value. When it does not meet the preset standard, increase the heat input power of the infrared heating device, or determine that the reasons for the non-compliance of the pressing with the preset standard according to the pressing characteristic area include that the pressing speed does not meet the standard and the traversal speed does not meet the standard; the pressing characteristic area is the integral area of the pressing time-upper shell displacement curve. Step S6: In response to the interface bonding strength mean value obtained by sampling inspection with the accelerated traversal heating method, determine whether the upper and lower shell pressing meets the preset standard according to this interface bonding strength mean value. When it does not meet the preset standard, determine that the reasons for the non-compliance of the pressing with the preset standard based on the bonding consistency characteristic value include insufficient hot melting or the traversal acceleration does not meet the standard; the bonding consistency characteristic value is the interface bonding strength difference between the initial heating area and the termination heating area of the glue-coated surface. Step S7: Remove the bonding wire drawing of the battery pack whose upper and lower shell pressing meets the preset standard.

[0024] It should be noted that the data in this embodiment are all the results obtained through preliminary experimental verification by the method of the present invention before this preparation. Each preset value can be adjusted according to specific usage conditions, as long as it meets the requirement that the method of the present invention can clearly define different specific situations in the single-item determination process through the obtained numerical values.

[0025] Specifically, the glue to be secondarily activated in this embodiment is an EPP material. The EPP material has high requirements for the pressing temperature. Too high a temperature will cause the EPP rebound rate to decrease, and too low a temperature will affect the interface bonding strength. Please refer to Figure 2 , and the inside of the black frame is the glue-coated surface.

[0026] Specifically, the equipment used in the method of the present invention is a secondary activation pressing equipment, which includes an industrial control computer, an infrared heating device, a slide rail, a press, an upper mold, and a lower mold. Among them, the industrial control computer is respectively connected to an industrial camera for collecting the image of the glue-coated surface of the lower shell of the battery pack. A parameter input unit is also set on the industrial control computer, and product parameters obtained by sampling inspection should be input, including the interface bonding strength mean value, the pressing characteristic area, and the bonding consistency characteristic value. When loading, the lower shell sub-assembly is installed on the lower mold through a robot gripper. The upper mold must ensure that there is a certain distance between the upper shell and the lower shell, and there is enough space to allow the infrared heating device to enter. At this time, the infrared heating device slides along the slide rail and enters to secondarily activate the hot melt adhesive of the lower shell. After activation, the infrared heating device slides out, and the press presses down to start pressing. The pressing pressure > 80T, the pressing time is 60s. After completion, pressure holding starts, the pressure holding pressure > 10T, and the pressure holding time is 9 minutes.

[0027] Specifically, in response to the ratio of the area of the effective activation region being less than the preset ratio of 15.50%, it is determined that the initial heating method is the accelerated traversal heating method, and in response to the ratio of the area of the effective activation region being greater than or equal to the preset ratio, it is determined that the initial heating method is the uniform traversal heating method; the ratio of the area of the effective activation region is the ratio of the area of the glue application surface in the preset area collected on the glue application surface of the lower shell of the battery pack; referring to the structural schematic diagram of the glue application surface of the lower shell of the battery pack, it can be understood that the glue application, leveling, and preliminary curing are completed before the secondary activation of the glue application surface. Due to the non - continuous uniform linear state of the glue application, the shapes and areas of the glue application surfaces of each lower shell of the battery pack presented in the top view are different, and the corresponding thicknesses are also different. Thus, for the thicker and wider glue application, the heat storage capacity of the colloid itself is large. Therefore, the uniform traversal heating method can ensure the consistency before bonding of the entire heating surface. For the thinner and narrower glue application, the heat storage capacity of the colloid itself is small, and the accelerated traversal heating method is used for heating, thereby improving the heating speed and ensuring the consistency before bonding of the front and rear heating surfaces.

[0028] Specifically, the uniform traversal heating method is that the infrared heating device covers the glue application surface of the lower shell of the battery pack and heats from the head end to the tail end at a uniform speed along the long - range direction of the lower shell; the accelerated traversal heating method is that the infrared heating device covers the glue application surface of the lower shell of the battery pack and heats from the head end to the tail end at a preset acceleration along the long - range direction of the lower shell; in this embodiment, for the uniform traversal heating method, the thermal input power of its external heating device and the initial speed of the infrared heating device are not specifically limited. For example, the thermal input power is 15 kW and the initial speed is 4.5 m / min; for the accelerated traversal heating method, the thermal input power of its external heating device and the initial speed of the infrared heating device are also not specifically limited. For example, the thermal input power is 18 kW, the initial speed is 4.5 m / min, and the preset acceleration is 1.35 m / min. 2 It can be specifically set according to the equipment and the actual production situation on site.

[0029] Specifically, in the step S5, when the average value of the interface bonding strength is less than the second preset strength threshold, it is determined that the upper and lower shells are not pressed together in accordance with the preset standard; when the average value of the interface bonding strength is greater than or equal to the second preset strength threshold, it is determined that the upper and lower shells are pressed together in accordance with the preset standard; when the average value of the interface bonding strength is greater than or equal to the first preset strength threshold and less than the second preset strength threshold, the reason for the non-compliance with the preset standard is determined according to the pressing feature area, and when the average value of the interface bonding strength is less than the first preset strength threshold, the thermal input power of the infrared heating device for the next batch of pressing is increased; the increase amplitude of the thermal input power of the infrared heating device is positively correlated with the difference between the first preset strength threshold and the average value of the interface bonding strength; wherein, the average value of the interface bonding strength is the average of the interface bonding strengths of several bonding points, and the interface bonding strength of the sample is measured by a shear test; wherein, the second preset strength threshold is set to 2.50 MPa, and the first preset strength threshold is set to 2.35 MPa. It can be understood that when it is determined that the upper and lower shells are pressed together in accordance with the preset standard when the average value of the interface bonding strength is greater than or equal to the second preset strength threshold of 2.50 MPa, it is directly determined that the sampling inspection is qualified and it is determined to continue to use the production parameters within this sampling inspection cycle in the next sampling inspection cycle; when the average value of the interface bonding strength is less than the second preset strength threshold of 2.50 MPa, it is determined that the upper and lower shells are not pressed together in accordance with the preset standard, and when the average value of the interface bonding strength is greater than or equal to the first preset strength threshold of 2.35 MPa and less than the second preset strength threshold of 2.50 MPa, at this time, it is preliminarily determined that the upper and lower shells are not pressed together in accordance with the preset standard, and the reason for the non-compliance with the preset standard needs to be verified according to some characteristics in the pressing process. In this embodiment, the pressing feature area is selected, and the pressing feature area characterizes the reaction force received by the upper die during the pressing process, thereby reflecting the uniformity and soft-hard state of the colloid after secondary activation on the side; if the average value of the interface bonding strength is less than the first preset strength threshold of 2.35 MPa, it is directly determined that the reason for the non-compliance with the preset standard is insufficient activation of the colloid, and thus the thermal input power of the infrared heating device for the next batch of pressing is directly increased; the increase amplitude of the thermal input power of the infrared heating device is positively correlated with the difference between the first preset strength threshold and the average value of the interface bonding strength. It can be understood that the positive correlation can be a linear positive correlation or a non-linear positive correlation, which is not specifically limited, and the slope of the linear positive correlation is not specifically limited either. For example, under the linear positive correlation adjustment, the increase amplitude of the thermal input power is set to △I, and the difference between the first preset strength threshold and the average value of the interface bonding strength is set to △Φ, then △I = α×△Φ, where α is the linear adjustment coefficient of the thermal input power. When α = 1.02, it satisfies that the greater the difference between the first preset strength threshold and the average value of the interface bonding strength, the greater the increase amplitude of the thermal input power of the infrared heating device for the next batch of pressing.

[0030] Specifically, when the area of the pressing feature is less than the preset feature area, it is determined that the reason for not meeting the preset standard is that the pressing speed does not meet the standard, and when the area of the pressing feature is greater than or equal to the preset feature area, it is determined that the reason for not meeting the preset standard is that the traversing speed does not meet the standard; here, the area of the pressing feature represents the reaction force received by the upper die during the pressing process, thereby reflecting the uniformity and hardness state of the colloid after secondary activation. When the area of the pressing feature is less than the preset feature area, the colloid after secondary activation is relatively soft. If the corresponding pressing speed is too fast, the colloid cannot dissipate heat sufficiently and deform effectively for bonding. When the area of the pressing feature is greater than or equal to the preset feature area, the core of the colloid after secondary activation has a higher hardness. Therefore, appropriately reducing the traversing speed can overcome this problem. Here, the area of the pressing feature is the integral area of the pressing time-upper shell displacement curve. The pressing time-upper shell displacement curve takes the pressing time as the abscissa and the upper shell displacement as the ordinate. The unit of the pressing time is s, and the unit of the upper shell displacement is mm. It is set that the upper shell displacement of the pressing stroke is 3 mm, and the pressing time is the time set for this stroke, which is 5 s. Among them, the preset feature area is, for example, 7.5 mm·s, and the preset feature area can also be specifically set according to the equipment and the actual production situation on site.

[0031] Specifically, in response to the pressing speed not meeting the standard, the pressing speed of the upper and lower shells of the next batch of battery packs is reduced, and the reduction amplitude of the pressing speed of the upper and lower shells of the next batch of battery packs is positively correlated with the difference between the preset feature area and the area of the pressing feature; here, it only needs to be satisfied that the greater the difference between the preset feature area and the area of the pressing feature, the greater the reduction amplitude of the pressing speed of the upper and lower shells of the next batch of battery packs. Positive correlation can refer to increasing the heat input power of the infrared heating device for the next batch of pressing, which will not be elaborated here; in response to the traversing speed not meeting the standard, the traversing speed of the upper and lower shells of the next batch of battery packs is reduced, and the reduction amplitude of the traversing speed of the upper and lower shells of the next batch of battery packs is positively correlated with the difference between the area of the pressing feature and the preset feature area. Here, it only needs to be satisfied that the greater the difference between the area of the pressing feature and the preset feature area, the greater the reduction amplitude of the traversing speed of the upper and lower shells of the next batch of battery packs, which will not be elaborated here either.

[0032] Specifically, in the step S6, when the average value of the interfacial bonding strength is less than the second preset strength threshold, it is determined that the pressing of the upper and lower shells does not meet the preset standard; when the average value of the interfacial bonding strength is greater than or equal to the second preset strength threshold, it is determined that the pressing of the upper and lower shells meets the preset standard, where the second preset strength threshold is set to 2.50 MPa.

[0033] Specifically, in the step S6, when the bonding consistency eigenvalue is less than the preset consistency feature threshold, it is determined that the reason for not meeting the preset standard is insufficient hot melting. And when the bonding consistency eigenvalue is greater than or equal to the preset consistency feature threshold, it is determined that the reason for not meeting the preset standard is that the traversal acceleration does not meet the standard. The bonding consistency eigenvalue is the interface bonding strength difference between the initial heating area and the termination heating area of the glue application surface. It can be understood that the smaller the bonding consistency eigenvalue, the higher the consistency of the secondary activation of the front and rear heating surfaces. On the contrary, the larger the bonding consistency eigenvalue, the worse the consistency of the secondary activation of the front and rear heating surfaces. The preset consistency feature threshold is set to 0.08 MPa.

[0034] Specifically, in response to insufficient hot melting, increase the thermal input power of the next batch of pressing, and the increase amplitude of the thermal input power is positively correlated with the difference between the preset consistency feature threshold and the bonding consistency eigenvalue. Here, the adjustment of the increase amplitude of the thermal input power refers to the adjustment of the increase of the thermal input power of the infrared heating device for the next batch of pressing, which will not be elaborated here. In response to the traversal acceleration not meeting the standard, decrease the preset acceleration of the next batch of pressing, and the decrease amplitude of the preset acceleration is positively correlated with the difference between the bonding consistency eigenvalue and the preset consistency feature threshold. Here, the adjustment of the decrease amplitude of the preset acceleration also refers to the adjustment of the increase of the thermal input power of the infrared heating device for the next batch of pressing, which will not be elaborated here.

[0035] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

[0036] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for pressing the upper and lower shells of a battery pack based on secondary activation, characterized in that, Including: Step S1: Collect the image of the glue - applying surface of the battery pack lower case, and obtain the proportion of the area of the effective activation region. Step S2: Based on the comparison between the proportion of the area of the effective activation region and a preset proportion, determine the initial heating method. The initial heating method includes a uniform traversal heating method and an accelerated traversal heating method. Step S3: Leave a preset spacing between the glue - applying surface of the lower case and the bonding surface of the upper case, and use an infrared heating device to complete the secondary activation of the glue according to the corresponding initial heating method. Step S4: Use a press to sequentially complete the pressing and pressure - maintaining of the upper and lower cases of the battery pack. Step S5: When the average interface bonding strength is obtained by sampling in response to the uniform traversal heating method and it is determined that the pressing of the upper and lower cases does not meet the preset standard according to this average interface bonding strength, increase the heat input power of the infrared heating device. Or, according to the pressing characteristic area, determine that the reasons for the non - compliance with the preset standard in pressing include that the pressing speed does not meet the standard and the traversal speed does not meet the standard; the pressing characteristic area is the integral area of the pressing time - upper case displacement curve. Step S6: When the average interface bonding strength is obtained by sampling in response to the accelerated traversal heating method and it is determined that the pressing of the upper and lower cases does not meet the preset standard according to this average interface bonding strength, based on the bonding consistency characteristic value, determine that the reasons for the non - compliance with the preset standard include insufficient heat melting or the traversal acceleration does not meet the standard; the bonding consistency characteristic value is the difference in the interface bonding strength between the initial heating region and the termination heating region of the glue - applying surface. Step S7: Remove the bonding wire drawing of the battery pack whose upper and lower cases are pressed to meet the preset standard.

2. The method for pressing and fitting the upper and lower cases of a battery pack based on secondary activation according to claim 1, wherein In response to the proportion of the area of the effective activation region being less than the preset proportion, determine that the initial heating method is the accelerated traversal heating method. And, in response to the proportion of the area of the effective activation region being greater than or equal to the preset proportion, determine that the initial heating method is the uniform traversal heating method.

3. The method for pressing the upper and lower shells of the battery pack based on secondary activation according to claim 2, wherein The uniform traversal heating method means that the infrared heating device covers the glue - applying surface of the battery pack lower case and uniformly heats from the head end to the tail end along the long - range direction of the lower case. The accelerated traversal heating method means that the infrared heating device covers the glue - applying surface of the battery pack lower case and heats from the head end to the tail end along the long - range direction of the lower case with a preset acceleration.

4. The method for pressing the upper and lower shells of a battery pack based on secondary activation according to claim 1, wherein In step S5, when the average interface bonding strength is less than the second preset strength threshold, determine that the pressing of the upper and lower cases does not meet the preset standard. When the average interface bonding strength is greater than or equal to the first preset strength threshold and less than the second preset strength threshold, determine the reasons for the non - compliance with the preset standard in pressing according to the pressing characteristic area. And, when the average interface bonding strength is less than the first preset strength threshold, increase the heat input power of the infrared heating device for the next batch of pressing.

5. The battery pack upper and lower shell pressing method based on secondary activation according to claim 4, wherein The increase amplitude of the heat input power of the infrared heating device is positively correlated with the difference between the first preset strength threshold and the average interface bonding strength.

6. The method for pressing the upper and lower cases of a battery pack based on secondary activation according to claim 4, wherein When the pressing characteristic area is less than the preset characteristic area, determine that the reason for non - compliance with the preset standard is that the pressing speed does not meet the standard. And, when the pressing characteristic area is greater than or equal to the preset characteristic area, determine that the reason for non - compliance with the preset standard is that the traversal speed does not meet the standard.

7. The method for pressing the upper and lower shells of the battery pack based on secondary activation according to claim 6, wherein, In response to the lamination speed not meeting the standard, reduce the lamination speed of the upper and lower shells of the next batch of battery packs, and the reduction amplitude of the lamination speed of the upper and lower shells of the next batch of battery packs is positively correlated with the difference between the preset feature area and the lamination feature area; in response to the traversing speed not meeting the standard, reduce the traversing speed of the upper and lower shells of the next batch of battery packs, and the reduction amplitude of the traversing speed of the upper and lower shells of the next batch of battery packs is positively correlated with the difference between the lamination feature area and the preset feature area.

8. The method for pressing the upper and lower shells of the battery pack based on secondary activation according to claim 1, wherein, In step S6, when the average interface bonding strength is less than the second preset strength threshold, it is determined that the lamination of the upper and lower shells does not meet the preset standard.

9. The method for pressing the upper and lower shells of a battery pack based on secondary activation according to claim 1, wherein, In step S6, when the bonding consistency feature value is less than the preset consistency feature threshold, it is determined that the reason for not meeting the preset standard is insufficient heat fusion, and when the bonding consistency feature value is greater than or equal to the preset consistency feature threshold, it is determined that the reason for not meeting the preset standard is that the traversing acceleration does not meet the standard.

10. The battery pack upper and lower shell pressing method based on secondary activation according to claim 9, characterized in that, In response to insufficient heat fusion, increase the heat input power for the next batch of lamination, and the increase amplitude of the heat input power is positively correlated with the difference between the preset consistency feature threshold and the bonding consistency feature value; In response to the traversing acceleration not meeting the standard, reduce the preset acceleration for the next batch of lamination, and the reduction amplitude of the preset acceleration is positively correlated with the difference between the bonding consistency feature value and the preset consistency feature threshold.

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