A method for processing a score of an explosion-proof valve of a power battery shell

Abstract

The application belongs to the technical field of power batteries, and provides a processing method for a power battery shell explosion-proof valve notch, comprising the following steps: pretreating the power battery shell to obtain an explosion-proof valve notch sketch; 3D scanning the explosion-proof valve notch sketch to obtain the depth of the explosion-proof valve notch sketch; calculating the thickness of the remaining part of the shell at the explosion-proof valve notch sketch; determining the gradient group to which the thickness of the remaining part of the shell at the explosion-proof valve notch sketch belongs and the corresponding depth compensation amount according to the set gradient group; and laser cleaning compensation for the explosion-proof valve notch sketch. Through pretreatment, 3D scanning detection and laser cleaning compensation, the risk of damaging the notch integrity caused by traditional processing and the influence caused by uncontrollable factors such as tool wear and clamping tolerance can be avoided, so that a higher-precision explosion-proof valve notch can be processed on the power battery shell, and the sensitivity when the explosion-proof valve is opened and the consistency of the valve opening pressure relief are ensured, and the safety performance of the power battery is improved.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and specifically to a method for machining the explosion-proof valve of a power battery casing. Background Technology

[0002] The power batteries used in new energy vehicles often feature high-energy cells to meet their increasing demands for longer driving range. These batteries have high energy density, and in the event of a collision or other accident, the damaged battery can generate a large amount of gas, causing the internal pressure to rise rapidly and even exceed safe limits. If this pressure is not released in time, it can lead to serious consequences such as battery casing deformation, leakage, or even explosion. Therefore, to prevent these situations and ensure the safety of power battery use, the battery casing is generally equipped with a pressure relief structure known in the industry as an explosion-proof valve. When the internal pressure of the power battery exceeds the safe limit, the internal gas can be released by rupturing the pressure relief structure to prevent an explosion.

[0003] Currently, the explosion-proof valves of power batteries are grooves machined into the battery casing. In some applications requiring high precision in pressure relief valve opening, such as extreme certifications for combustion injection or high standards for module safety, the grooves on the explosion-proof valves of power batteries must meet the requirements of small depth fluctuations and high valve opening consistency. However, traditional stamping or CNC machining processes, due to the combined effects of clamping tolerances, friction between the tool and the groove, and tool wear, have two limitations: firstly, they cannot directly machine very deep grooves (friction would destroy the integrity of the grooves); secondly, they cannot guarantee the consistency of the explosion-proof valve groove machining. Especially when the battery casing is made of hard and thick steel, tool wear exacerbates uncontrollable factors, ultimately leading to large fluctuations in the depth of the explosion-proof valve grooves and poor consistency, which affects the safety performance of the power battery. This has become a technical bottleneck that the industry needs to overcome. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for machining the explosion-proof valve markings on a power battery casing, thereby solving the problem that the integrity of the markings on the explosion-proof valves of existing power batteries is easily compromised and consistency cannot be guaranteed during machining.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for machining the explosion-proof valve of a power battery casing includes the following steps:

[0007] S1. Pre-process the power battery casing to obtain a prototype of the explosion-proof valve with a preset shape and size;

[0008] S2. Perform 3D scanning on the explosion-proof valve groove prototype obtained in S1 to obtain the depth of the explosion-proof valve groove prototype;

[0009] S3. Based on the thickness of the power battery casing and the depth of the explosion-proof valve etched profile obtained in S2, calculate the thickness of the remaining part of the casing at the explosion-proof valve etched profile.

[0010] S4. According to the set gradient group, determine the gradient group to which the thickness of the remaining part of the shell at the explosion-proof valve indentation calculated in S3 belongs and the corresponding depth compensation amount.

[0011] S5. Based on the thickness gradient group and corresponding depth compensation amount of the remaining part of the shell at the explosion-proof valve scoring prototype determined in S4, perform laser cleaning compensation on the explosion-proof valve scoring prototype obtained in S1 to process the explosion-proof valve scoring that meets the design requirements.

[0012] In one embodiment disclosed in this application, in S1, the pretreatment is one of stamping, CNC machining, and cold extrusion.

[0013] In one embodiment disclosed in this application, in S1, the preset shape of the explosion-proof valve scoring prototype is generally C-shaped and the cross-section is U-shaped.

[0014] In one embodiment disclosed in this application, the C-shaped explosion-proof valve groove prototype is connected end to end by a circular arc to form a complete circle, and the central angle corresponding to the circular arc is 10 to 35°.

[0015] In one embodiment disclosed in this application, in S1, the preset dimensions of the explosion-proof valve groove prototype include a preset diameter, a preset width, and a preset depth, wherein the preset width is 0.5 to 1.0 mm.

[0016] In one embodiment disclosed in this application, the power battery casing is made of steel or aluminum.

[0017] In one embodiment disclosed in this application, in S4, the set gradient groups include three groups: a lower limit group, a middle limit group, and an upper limit group. The lower limit group does not compensate for depth, the middle limit group corresponds to a light compensation amount for depth, and the upper limit group corresponds to a heavy compensation amount for depth.

[0018] In one embodiment disclosed in this application, when the thickness of the remaining portion of the housing at the initial groove of the explosion-proof valve is 0.07±0.02mm, it belongs to the lower limit group, and the depth compensation amount is 0mm;

[0019] When the thickness of the remaining part of the shell at the initial groove of the explosion-proof valve is 0.11±0.02mm, it belongs to the middle limit group, and the slight compensation amount is 0.04±0.02mm;

[0020] When the thickness of the remaining part of the shell at the initial groove of the explosion-proof valve is 0.15±0.02mm, it belongs to the upper limit group, and the heavy compensation amount is 0.08±0.02mm.

[0021] In one embodiment disclosed in this application, in S5, the laser cleaning compensation path is an O-ring whose diameter matches the preset diameter of the explosion-proof valve scoring prototype.

[0022] The start / end point of the laser cleaning compensation is set on the arc connecting the beginning and end of the explosion-proof valve's etched outline, so as to achieve continuous cleaning while overcoming the defect of unstable energy when the laser is turned on and off.

[0023] In one embodiment disclosed in this application, the relevant parameters for laser cleaning compensation include scanning speed, frequency, pulse width, line spacing, number of cleaning cycles, and cleaning time;

[0024] When the power battery casing is made of steel, based on the parameters of scanning speed of 800mm / s, frequency of 50kHz, pulse width of 350ns, line spacing of 0.01mm, number of cleaning cycles of 100, and cleaning time of 13s, the depth compensation that can be processed by the laser cleaning compensation is 0.04mm.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] By preprocessing, 3D scanning detection, and laser cleaning compensation, the risk of damaging the integrity of the markings caused by traditional stamping or CNC machining can be avoided. It can also reduce the impact of uncontrollable factors such as tool wear and clamping tolerances. This allows for the machining of high-precision explosion-proof valve markings on the power battery casing, thereby ensuring the sensitivity of the explosion-proof valve when it is opened and the consistency of valve opening and pressure relief, and improving the safety performance of the power battery. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the steps of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the explosion-proof valve groove on the power battery casing obtained by the present invention;

[0030] Figure 3This is a schematic diagram of the initial shape of the explosion-proof valve groove obtained after pretreatment of the power battery casing;

[0031] Figure 4 A schematic diagram of the cross-sectional structure of the initial grooved shape of the explosion-proof valve;

[0032] Figure 5 This is a schematic diagram of the structure of the explosion-proof valve markings obtained after laser cleaning of the initial markings.

[0033] Figure 6 This is a schematic diagram of the cross-sectional structure of the grooves on the explosion-proof valve. Detailed Implementation

[0034] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention.

[0040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] See Figures 1-6 As shown, the present invention provides a method for machining the explosion-proof valve of a power battery casing, comprising the following steps:

[0042] S1. Pre-process the power battery casing to obtain a prototype of the explosion-proof valve with a preset shape and size.

[0043] Specifically, a power battery casing made of steel or aluminum is selected. Pre-processing techniques such as stamping, CNC machining, and cold extrusion are used to rough-machine the end cap 10 of the power battery casing, obtaining a preliminary explosion-proof valve marking 11' with a pre-defined C-shaped overall structure and a U-shaped cross-section. The C-shaped explosion-proof valve marking preliminary is connected end-to-end by an arc to form a complete circle, with the central angle α corresponding to this arc preferably being 10–35°. The pre-defined dimensions of the explosion-proof valve marking preliminary include a pre-defined diameter D, a pre-defined width W, and a pre-defined depth h1, wherein the pre-defined width W is preferably 0.5–1.0 mm. Through the pre-processing, the depth of the explosion-proof valve marking preliminary is relatively shallow, making the remaining part of the corresponding casing slightly thicker, which can effectively avoid the risk of frictional damage to the marking.

[0044] S2. Perform 3D scanning on the prototype of the explosion-proof valve groove obtained in S1 to obtain the depth of the prototype of the explosion-proof valve groove.

[0045] Specifically, based on a high-precision 3D vision system, the pre-processed explosion-proof valve scoring prototype is scanned and detected in 3D to obtain the depth of the explosion-proof valve scoring prototype (i.e., the amount of pre-processing).

[0046] S3. Based on the thickness of the power battery casing and the depth of the explosion-proof valve etched profile obtained in S2, calculate the thickness of the remaining part of the casing at the explosion-proof valve etched profile.

[0047] Specifically, the end cap 10 of the power battery casing has a thickness of T, the preset depth of the explosion-proof valve etched outline is h1, and the thickness of the remaining portion of the casing at the explosion-proof valve etched outline is t1. Figure 4 It can be known that:

[0048] t1=T-h1

[0049] The thickness of the remaining part of the shell at the initial groove of the explosion-proof valve can be calculated using the above formula.

[0050] S4. According to the set gradient group, determine the gradient group to which the thickness of the remaining part of the shell at the explosion-proof valve indentation calculated in S3 belongs and the corresponding depth compensation amount.

[0051] Specifically, the defined gradient groups include three groups: a lower limit group, a middle limit group, and an upper limit group. The lower limit group does not compensate for depth; the middle limit group corresponds to a slight depth compensation; and the upper limit group corresponds to a heavy depth compensation. In this embodiment, when the thickness t1 of the remaining portion of the shell at the initial scoring of the explosion-proof valve is 0.07±0.02mm (i.e., 0.05≤t1<0.09), it belongs to the lower limit group, and the depth compensation is 0mm; when the thickness t1 of the remaining portion of the shell at the initial scoring of the explosion-proof valve is 0.11±0.02mm (i.e., 0.09≤t1<0.13), it belongs to the middle limit group, and the slight compensation is preferably 0.04±0.02mm; when the thickness t1 of the remaining portion of the shell at the initial scoring of the explosion-proof valve is 0.15±0.02mm (i.e., 0.13≤t1<0.17), it belongs to the upper limit group, and the heavy compensation is preferably 0.08±0.02mm.

[0052] S5. Based on the thickness gradient group and corresponding depth compensation amount of the remaining part of the shell at the explosion-proof valve scoring prototype determined in S4, perform laser cleaning compensation on the explosion-proof valve scoring prototype obtained in S1 to process the explosion-proof valve scoring that meets the design requirements.

[0053] Specifically, laser equipment such as ultraviolet nanosecond lasers are used to perform light or heavy laser cleaning compensation on the explosion-proof valve marking prototypes of different gradient groups according to the corresponding depth compensation amount, so as to achieve fine machining of the explosion-proof valve markings, thereby obtaining explosion-proof valve markings 11 whose shape and size meet the design requirements. The laser cleaning compensation path is an O-ring, the diameter of which matches the preset diameter D of the explosion-proof valve marking prototype; the start / end point 12 of the laser cleaning compensation is set on the arc connecting the beginning and end of the explosion-proof valve marking prototype, so as to achieve continuous cleaning while overcoming the defect of unstable energy when the laser is turned on and off.

[0054] Based on the prototype of explosion-proof valve grooves of different materials and lengths, as well as the different gradient groups and corresponding depth compensation amounts determined in S4, the scanning speed, frequency, pulse width, line spacing, number of cleaning cycles (i.e., number of engraving cycles), and cleaning time (i.e., engraving time) of laser cleaning compensation are optimized by DOE method.

[0055] For example, when the power battery casing is made of steel, the O-ring of the laser cleaning path is a φ21mm circle with a cleaning width of 0.5mm. Using optimized parameters of a scanning speed of 800mm / s, a frequency of 50kHz, a pulse width of 350ns, and a line spacing of 0.01mm, the laser cleaning of the initial grooves on the explosion-proof valve yields the following number of cleaning cycles and cleaning time required to achieve the corresponding depth compensation:

[0056] ① After 100 washes, the washing time is 13 seconds, and the depth compensation is approximately 0.04 mm.

[0057] ② The machine was cleaned 150 times, with a cleaning time of 19 seconds and a depth compensation of approximately 0.08 mm.

[0058] ③ The machine is cleaned 200 times, with a cleaning time of 26 seconds and a depth compensation of approximately 0.12 mm.

[0059] After laser cleaning and compensation, the depth of the scoring on the explosion-proof valve is h2, and the corresponding thickness of the remaining portion of the housing is t2. Figure 6 It can be known that:

[0060] h2 = h1 + depth compensation amount

[0061] t2 = t1 - depth compensation amount

[0062] In summary, by using preprocessing, 3D scanning detection, and laser cleaning compensation, we can avoid the risk of damaging the integrity of the markings caused by traditional stamping or CNC machining, and reduce the impact of uncontrollable factors such as tool wear and clamping tolerances. This allows us to process high-precision explosion-proof valve markings on the power battery casing, thereby ensuring the sensitivity of the explosion-proof valve when it is opened and the consistency of the valve opening and pressure relief, and improving the safety performance of the power battery.

[0063] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of the patent of the present invention.

Claims

1. A method for machining the explosion-proof valve of a power battery casing, characterized in that, Includes the following steps: S1. Pre-process the power battery casing to obtain a prototype of the explosion-proof valve with a preset shape and size; S2. Perform 3D scanning on the explosion-proof valve groove prototype obtained in S1 to obtain the depth of the explosion-proof valve groove prototype; S3. Based on the thickness of the power battery casing and the depth of the explosion-proof valve etched profile obtained in S2, calculate the thickness of the remaining part of the casing at the explosion-proof valve etched profile. S4. According to the set gradient group, determine the gradient group to which the thickness of the remaining part of the shell at the explosion-proof valve etched prototype calculated in S3 belongs and the corresponding depth compensation amount. The set gradient group includes the lower limit group, the middle limit group and the upper limit group. The lower limit group does not compensate for depth. The depth compensation amount corresponding to the middle limit group is a light compensation amount. The depth compensation amount corresponding to the upper limit group is a heavy compensation amount. S5. Based on the thickness gradient group and corresponding depth compensation amount of the remaining part of the shell at the explosion-proof valve scoring prototype determined in S4, perform laser cleaning compensation on the explosion-proof valve scoring prototype obtained in S1 to process the explosion-proof valve scoring that meets the design requirements.

2. The method for machining the explosion-proof valve of the power battery casing according to claim 1, characterized in that, In S1, the pretreatment is one of stamping, CNC machining, and cold extrusion.

3. The method for machining the explosion-proof valve of the power battery casing according to claim 1, characterized in that, In S1, the preset shape of the explosion-proof valve scoring prototype is C-shaped and the cross-section is U-shaped.

4. The method for machining the explosion-proof valve of the power battery casing according to claim 3, characterized in that, The C-shaped explosion-proof valve's serrated outline is connected end to end by a circular arc to form a complete circle, with the central angle corresponding to the arc being 10 to 35°.

5. The method for machining the explosion-proof valve of the power battery casing according to claim 1, characterized in that, In S1, the preset dimensions of the explosion-proof valve groove prototype include a preset diameter, a preset width, and a preset depth, wherein the preset width is 0.5 to 1.0 mm.

6. The method for machining the explosion-proof valve of the power battery casing according to any one of claims 1 to 5, characterized in that, The battery casing is made of steel or aluminum.

7. The method for machining the explosion-proof valve of the power battery casing according to claim 1, characterized in that: When the thickness of the remaining part of the shell at the initial groove of the explosion-proof valve is 0.07±0.02mm, it belongs to the lower limit group, and the depth compensation amount is 0mm; When the thickness of the remaining part of the shell at the initial groove of the explosion-proof valve is 0.11±0.02mm, it belongs to the middle limit group, and the slight compensation amount is 0.04±0.02mm; When the thickness of the remaining part of the shell at the initial groove of the explosion-proof valve is 0.15±0.02mm, it belongs to the upper limit group, and the heavy compensation amount is 0.08±0.02mm.

8. The method for machining the explosion-proof valve of the power battery casing according to claim 1, characterized in that: In S5, the laser cleaning compensation path is an O-ring, the diameter of which matches the preset diameter of the explosion-proof valve scoring prototype. The start / end point of the laser cleaning compensation is set on the arc connecting the beginning and end of the explosion-proof valve's etched outline, so as to achieve continuous cleaning while overcoming the defect of unstable energy when the laser is turned on and off.

9. The method for machining the explosion-proof valve of the power battery casing according to claim 8, characterized in that: The relevant parameters for laser cleaning compensation include scanning speed, frequency, pulse width, line spacing, number of cleaning cycles, and cleaning time. When the power battery casing is made of steel, based on the parameters of scanning speed of 800mm / s, frequency of 50kHz, pulse width of 350ns, line spacing of 0.01mm, number of cleaning cycles of 100, and cleaning time of 13s, the depth compensation that can be processed by the laser cleaning compensation is 0.04mm.

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