Welding machine capable of avoiding insufficient welding of negative electrode of cylindrical lithium ion battery

Abstract

The utility model relates to the technical field of lithium ion batteries, and discloses a welding machine for avoiding insufficient welding of a cathode of a cylindrical lithium ion battery, which comprises a frame body and a welding needle, a rotating structure for driving the welding needle to rotate horizontally is mounted on the frame body, the rotating structure is movably connected with the welding needle, and a pressure follower for controlling the welding pressure of the welding needle is connected onto the welding needle. The pressure follower is connected with the frame body; the influence of the pressure follower on the welding pressure of the welding needle and the contact internal resistance of the battery shell is verified, and the conclusion that the larger the welding pressure is, the smaller the contact internal resistance is is is obtained, so that the welding pressure is controlled to control welding energy output, and the welding energy consistency is ensured; the welding machine is optimized, and after welding is completed, adhesion between the welding needle and the negative electrode lug and between the welding needle and the battery shell is effectively controlled through the rotary needle pulling function of the rotary structure, and the problem that a welding point between the negative electrode lug and the battery shell is loosened due to direct needle pulling is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium-ion batteries, and more specifically, to a welding machine for avoiding virtual welding in the negative electrode welding of lithium-ion cylindrical batteries. Background Art

[0002] In the late 1970s, the oil crisis prompted the world to search for alternative energy sources to reduce dependence on fossil fuels. During the application research and exploration process, it was found that lithium-ion batteries have high energy density and can be charged and discharged multiple times. Therefore, the application of lithium-ion batteries is not limited to the consumer electronics field, but also widely used in many fields such as electric vehicles, energy storage systems, and aerospace.

[0003] With the global emphasis on environmental protection and sustainable development, the application of lithium-ion batteries has completely changed our daily lives. Various electronic devices carried or used, such as mobile power supplies, laptops, and electric bicycles for driving, all use lithium-ion batteries as their power sources. During the use, charging, or discharging process of these lithium-ion batteries, extremely high requirements are placed on the welding effect and consistency of the negative electrode inside the battery. Only when the molten state at the joint of the two metal parts to be welded is stable and the welding effect is good, can the current conduction effect during the charging and discharging process be better. When virtual welding occurs in the negative electrode welding, the joint between the negative electrode tab and the battery case is in a detached and virtual connection state, which significantly increases the internal resistance of the battery. There may be a risk of open circuit during high-rate discharge, resulting in the failure of the battery to be used and ultimately causing the equipment in use to be paralyzed, seriously affecting our daily lives.

[0004] Currently, in the manufacturing process of lithium-ion cylindrical batteries in the industry, especially during the welding process of the negative electrode tab and the battery case, industry-leading resistance welding equipment and fixtures are often purchased to enhance the welding effect. However, the problem of virtual welding cannot be systematically solved. Only by enhancing the welding strength and subsequent screening methods can the use reliability of the product be improved. When the welding strength increases, the appearance problems at the bottom of the battery case become particularly prominent, and in severe cases, the product is directly scrapped. In addition, subsequent screening is often carried out through methods such as vibration, high-rate charging and discharging, etc. However, this solution cannot completely pick out the virtual-welded batteries, and the cost is relatively high. There is a small probability that some batteries will flow to the end-users. In mild cases, the battery life is reduced due to excessive internal resistance, and in severe cases, the product fails to be used due to battery open circuit. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a welding machine for avoiding virtual welding in the negative electrode welding of lithium-ion cylindrical batteries, aiming to solve the problem of virtual welding existing in the welding process of the negative electrode tab and the battery case in the prior art.

[0006] The utility model is realized as follows. A welding machine for avoiding the virtual welding of the negative electrode of a lithium-ion cylindrical battery includes a frame body and a welding needle. A rotating structure for driving the horizontal rotation of the welding needle is installed on the frame body. The rotating structure is movably connected to the welding needle. A pressure follower for controlling the welding pressure of the welding needle is connected to the welding needle, and the pressure follower is connected to the frame body.

[0007] Further, a moving frame for longitudinal movement is provided on the frame body. A clamping head for clamping the welding needle is provided on the moving frame. The pressure follower is arranged above the clamping head, and the clamping head is in transmission connection with the rotating structure.

[0008] Further, the rotating structure includes a driven gear arranged on the moving frame and rotatingly arranged, and a driving gear in gear engagement with the driven gear. The clamping head is fixed on the driven gear and is eccentrically arranged with the driven gear. A driver for driving the rotation of the driving gear is connected to the driving gear.

[0009] Further, the welding needle is inserted into the clamping head. The upper end of the welding needle passes through the clamping head to form an upper section exposed above the clamping head, and the lower end of the welding needle extends downward to form a lower section.

[0010] Further, a horizontally arranged cantilever and a moving rod for driving the up and down movement of the cantilever are provided at the bottom of the pressure follower. The upper part of the moving rod is connected to the pressure follower, and the lower part of the moving rod is connected to the inner end of the cantilever. The outer end of the cantilever extends horizontally away from the moving rod, and a longitudinally arranged pressing head is connected to the outer end of the cantilever. The pressing head is movably abutted against the upper section.

[0011] Further, a clamping seat is provided on the moving frame. The moving rod is inserted into the clamping seat, and the clamping seat is located between the pressure follower and the cantilever.

[0012] Further, the moving frame includes a longitudinal plate movably connected to the frame body and longitudinally moving along the frame body. The pressure follower is installed on the longitudinal plate. A transverse plate is connected to the longitudinal plate, and the clamping head is installed on the transverse plate. The longitudinal plate is connected with a driving structure, and the driving structure drives the moving frame to longitudinally move relative to the frame body.

[0013] Further, the driving structure includes a connecting rod. The upper end of the connecting rod is hinged with an upper connecting plate, and the upper connecting plate is fixedly connected with the moving frame. The lower end of the connecting rod is hinged with a lower connecting plate, and the lower connecting plate is connected with a longitudinally moving moving block.

[0014] A screw that rotates in place is inserted into the moving block. The screw is threadedly connected to the moving block. The screw is connected to a motor. During the process that the motor drives the screw to rotate in place, the moving block moves longitudinally along the screw, and drives the moving frame to move longitudinally along the frame body through the connecting rod.

[0015] Further, a disconnection seam is provided in the clamping head. The disconnection seam penetrates through the clamping head vertically. The outer side of the disconnection seam penetrates through the circumferential side of the clamping head, and the inner side of the disconnection seam is placed inside the clamping head and is arranged in a closed manner. The middle part of the disconnection seam is recessed outward respectively to form a clamping channel. The clamping channel penetrates through the clamping head vertically. The welding needle is inserted into the clamping channel, and the upper section penetrates out of the clamping channel and extends above the clamping head.

[0016] Further, the disconnection seam divides the clamping head into two power supply parts that are connected as a whole. The two power supply parts are respectively connected to the positive electrode and the negative electrode of the power supply, so that the welding needle is energized to weld the negative electrode tab and the battery case.

[0017] Compared with the prior art, the welding machine provided by the present utility model for avoiding virtual welding of the negative electrode of a lithium-ion cylindrical battery verifies the influence of the welding pressure of the welding needle and the contact internal resistance of the battery case through a pressure follower, and obtains the conclusion that the greater the welding pressure, the smaller the contact internal resistance. Thus, the size of the welding pressure is controlled to achieve the control of the welding energy output, ensuring the energy consistency of the welding. The welding machine is optimized. When the welding is completed, the function of rotating and pulling out the needle is realized through the rotating structure, effectively controlling the adhesion between the welding needle, the negative electrode tab and the battery case, avoiding the looseness of the solder joint between the negative electrode tab and the battery case caused by directly pulling out the needle, which affects the welding effect, and improving the service life of the welding needle, reducing problems such as explosion due to deformation at the end of the welding needle or metal attachments, and further solving the energy loss in the welding process. By controlling the welding energy output and the energy loss in the welding process, the problem of virtual welding in the welding process is systematically solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a three-dimensional schematic diagram of the welding machine provided by the present utility model for avoiding virtual welding of the negative electrode of a lithium-ion cylindrical battery;

[0019] Figure 2 is a three-dimensional schematic diagram of the pressure follower, the rotating structure and the driving structure provided by the present utility model;

[0020] Figure 3 is a three-dimensional schematic diagram of the driving structure and the frame body provided by the present utility model;

[0021] Figure 4 is a three-dimensional schematic diagram of the clamping head provided by the present utility model;

[0022] Figure 5It is a schematic diagram of the welding pressure fitting line provided by the present utility model;

[0023] Figure 6 It is a schematic diagram of the contact internal resistance at the welding position under different welding pressures provided by the present utility model.

[0024] In the figure: frame body 10, welding needle 20, pressure follower 30, rotating structure 40, moving frame 11, clamping head 12, driving structure 13, clamping seat 14, upper section 21, lower section 22, longitudinal plate 111, transverse plate 112, disconnection seam 121, clamping channel 122, power supply part 123, connecting rod 131, upper connecting plate 132, lower connecting plate 133, moving block 134, screw rod 135, motor 136, moving rod 31, cantilever 32, pressing head 33, driven gear 41, driving gear 42, driver 43. Specific embodiments

[0025] In order to make the purpose, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0026] The implementation of the present utility model will be described in detail below with reference to specific embodiments.

[0027] In the attached drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the attached drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the attached drawings are only for illustrative purposes and cannot be understood as a limitation of the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0028] Refer to Figure 1-6 As shown, it is a preferred embodiment provided by the present utility model.

[0029] A welding machine for avoiding virtual welding at the negative electrode welding of lithium-ion cylindrical batteries includes a frame body 10 and a welding needle 20. A rotating structure 40 for driving the horizontal rotation of the welding needle 20 is installed on the frame body 10. The rotating structure 40 is movably connected to the welding needle 20. A pressure follower 30 for controlling the welding pressure of the welding needle 20 is connected to the welding needle 20, and the pressure follower 30 is connected to the frame body 10.

[0030] The welding machine provided above for avoiding the false welding of the negative electrode of the lithium-ion cylindrical battery verifies the influence of the welding pressure of the welding needle 20 on the contact internal resistance of the battery case through the pressure follower 30, and draws the conclusion that the greater the welding pressure, the smaller the contact internal resistance. Thus, the size of the welding pressure is controlled to control the output of the welding energy and ensure the energy consistency of the welding. The welding machine is optimized. When the welding is completed, the function of rotating and pulling out the needle is realized through the rotating structure 40, which effectively controls the adhesion between the welding needle 20, the negative electrode tab and the battery case, avoids the loosening of the solder joint between the negative electrode tab and the battery case caused by directly pulling out the needle, which in turn affects the welding effect, and improves the service life of the welding needle 20, reduces problems such as explosion due to deformation at the end of the welding needle 20 or the presence of attached metal, and thus solves the energy loss during the welding process. By controlling the output of the welding energy and the energy loss during the welding process, the problem of false welding in the welding process is systematically solved.

[0031] A digital display calibrator is set on the pressure follower 30, so as to ensure the output of the welding energy, the key parameters of the process control are practical, and the operation feasibility is high; to ensure the accurate output of the welding pressure, by verifying the influence of the welding pressure on the contact internal resistance, it is concluded that the greater the welding pressure, the smaller the contact internal resistance.

[0032] It avoids the problems of high internal resistance and open circuit caused by false welding of the battery during the transportation and use of the product, and improves the consistency of the product; it completely solves the negative impact caused by false welding of the battery, such as complaints about high internal resistance and open circuit failure of the battery, and unqualified terminal use performance, etc.; it improves the product quality of the company, reduces the risk of customer complaints, consolidates the market position of the product, improves the market competitiveness of the product, increases the order volume of the product, and maintains the profit of the company.

[0033] Through the verification of the influence of different welding pressures F and contact internal resistances R (Q = I 2 RT, where I is the current and T is the welding time. When I and T are constant, the internal resistance R affects the output of the welding energy), the reasonable welding pressure F interval parameters are obtained.

[0034] Through the regression analysis of the data of the welding pressure F and the contact internal resistance R, the P value < 0.05, indicating that there is a certain linear relationship between the welding pressure and the contact internal resistance, that is, the smaller the welding pressure, the greater the contact internal resistance, and the better the welding effect.

[0035] By referring to Figure 5-6 As can be seen from the figure, the contact internal resistance R is relatively stable within the range of the welding pressure F of 30 - 45N. Theoretically, the smaller the welding pressure, the greater the contact internal resistance, and the better the welding effect. However, if the contact internal resistance is too large, the contact parts such as the welding needle 20 and the welding seat are easily damaged. Therefore, the welding pressure control range is comprehensively evaluated: 30 - 45N. Within the calibrated welding pressure range, the fluctuation of the contact internal resistance is small, so that the consistency of the welding energy output Q can be effectively controlled.

[0036] In this embodiment, a longitudinally movable frame 11 is provided on the frame body 10 , a clamping head 12 for clamping the welding needle 20 is provided on the movable frame 11 , a pressure follower 30 is provided above the clamping head 12 , and the clamping head 12 is transmission-connected to the rotating structure 40 .

[0037] The frame 10 drives the welding needle 20 to move up and down through the movable frame 11. The clamping head 12 is used to clamp the welding needle 20 and move. The controller is used to control the pressure follower 30 to press against the upper section 21 of the welding needle 20, thereby stably controlling the pressure follower 30 to control the welding pressure of the welding needle 20.

[0038] In this embodiment, the rotating structure 40 includes a driven gear 41 that is arranged on the mobile frame 11 and is rotatably arranged, and a driving gear 42 that is gear-engaged with the driven gear 41. The clamping head 12 is fixed on the driven gear 41 and is eccentrically arranged with the driven gear 41; the driving gear 42 is connected to a driver 43 that drives the driving gear 42 to rotate.

[0039] The negative electrode tab and the battery shell are welded to form a connection position. When the welding needle 20 completes the welding of the negative electrode tab and the battery shell, the driver 43 is used to drive the driving gear 42 to rotate, and the driven gear 41 is driven to drive the clamping head 12 to rotate horizontally eccentrically, so that the welding needle 20 deviates horizontally from the connection position and disengages from the connection position.

[0040] In this embodiment, the welding needle 20 is inserted into the clamping head 12 , and the upper end of the welding needle 20 passes through the clamping head 12 to form an upper section 21 exposed above the clamping head 12 , and the lower end of the welding needle 20 extends downward to form a lower section 22 .

[0041] The bottom of the pressure follower 30 is provided with a horizontally arranged cantilever 32 and a movable rod 31 that drives the cantilever 32 to move up and down. The upper part of the movable rod 31 is connected to the pressure follower 30, and the lower part of the movable rod 31 is connected to the inner end of the cantilever 32. The outer end of the cantilever 32 extends horizontally away from the movable rod 31. The outer end of the cantilever 32 is connected to a longitudinally arranged pressure head 33, and the pressure head 33 is movably abutted on the upper section 21.

[0042] When the lower section 22 is inserted into the battery shell and the negative electrode tab is welded to the battery shell, the controller controls the pressure follower 30 to move so that the pressing head 33 presses the upper section 21 from top to bottom, applying pressure to the welding needle 20 so that the welding pressure of the welding needle 20 is within the set pressure range.

[0043] The pressure follower 30 can be connected to the welding needle 20 through the pressure head 33 on the cantilever 32, so as to feedback the size of the welding pressure of the welding needle 20 through the pressure head 33, so that the pressure follower 30 can transmit the information to the controller.

[0044] In this embodiment, a clamping seat 14 is provided on the moving frame 11. The moving rod 31 is inserted through the clamping seat 14, and the clamping seat 14 is located between the pressure follower 30 and the cantilever 32. In this way, the moving rod 31 can be clamped by the clamping seat 14 to prevent the moving rod 31 from deviating during the up and down movement, resulting in the pressure head 33 detaching from the upper section 21.

[0045] In this embodiment, the moving frame 11 includes a longitudinal plate 111 that is movably connected to the frame body 10 and moves longitudinally along the frame body 10. The pressure follower 30 is installed on the longitudinal plate 111. A transverse plate 112 is connected to the longitudinal plate 111, and the clamping head 12 is installed on the transverse plate 112; the longitudinal plate 111 is connected with a driving structure 13, and the driving structure 13 drives the moving frame 11 to move longitudinally relative to the frame body 10.

[0046] The moving frame 11 provides an installation position for the pressure follower 30 through the longitudinal plate 111, and provides an installation position for the rotating structure 40 through the transverse plate 112. The rotating structure 40 is used to clamp the welding needle 20 and control the rotation of the welding needle 20, so that the welding needle 20 horizontally deviates from the connection position and disengages from the connection position, effectively controlling the adhesion between the welding needle 20 and the negative electrode tab and the battery case, and avoiding the loosening of the solder joint between the negative electrode tab and the battery case caused by directly pulling out the needle; the driving structure 13 is used to drive the transverse plate 112 to drive the welding needle 20 on the clamping head 12 to move up and down.

[0047] The driving structure 13 includes a connecting rod 131. The upper end of the connecting rod 131 is hinged with an upper connecting plate 132, and the upper connecting plate 132 is fixedly connected to the moving frame 11. The lower end of the connecting rod 131 is hinged with a lower connecting plate 133, and the lower connecting plate 133 is connected to the longitudinally moving moving block 134;

[0048] A screw rod 135 that rotates in place is inserted through the moving block 134. The screw rod 135 is threadedly connected to the moving block 134. The screw rod 135 is connected with a motor 136. During the process that the motor 136 drives the screw rod 135 to rotate in place, the moving block 134 moves longitudinally along the screw rod 135, and drives the moving frame 11 to move longitudinally along the frame body 10 through the connecting rod 131.

[0049] In this embodiment, a disconnection seam 121 is provided in the clamping head 12. The disconnection seam 121 penetrates through the clamping head 12 up and down. The outer side of the disconnection seam 121 penetrates through the circumferential side of the clamping head 12, and the inner side of the disconnection seam 121 is placed inside the clamping head 12 and is arranged in a closed manner; the middle part of the disconnection seam 121 is recessed outward respectively to form a clamping channel 122. The clamping channel 122 penetrates through the clamping head 12 up and down. The welding needle 20 is inserted through the clamping channel 122, and the upper section 21 penetrates out of the clamping channel 122 and extends above the clamping head 12.

[0050] The clamping head 12 clamps the welding needle 20 through the clamping channel 122, and the disconnection seam 121 is used to adjust the clamping head 12 to adapt to the clamping of welding needles 20 of various sizes.

[0051] The disconnection seam 121 divides the clamping head 12 into two integrally connected power supply parts 123, and the two power supply parts 123 are respectively connected to the positive and negative electrodes of the power supply to make the welding needle 20 conduct electricity to weld the negative electrode tab and the battery case.

[0052] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries, characterized in that: It includes a frame and a welding needle. The frame is equipped with a rotating structure for driving the welding needle to rotate horizontally. The rotating structure is movably connected to the welding needle. The welding needle is connected to a pressure follower for controlling the welding pressure of the welding needle. The pressure follower is connected to the frame.

2. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries according to claim 1, characterized in that: The frame body is provided with a movable frame which moves longitudinally, the movable frame is provided with a clamping head for clamping the welding needle, the pressure follower is arranged above the clamping head, and the clamping head is transmission-connected with the rotating structure.

3. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries as claimed in claim 2, characterized in that: The rotating structure includes a driven gear that is arranged on a mobile frame and is rotatably arranged, and a driving gear that is gear-engaged with the driven gear. The clamping head is fixed on the driven gear and is eccentrically arranged with the driven gear. The driving gear is connected to a driver that drives the driving gear to rotate.

4. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries as claimed in claim 3, characterized in that: The welding needle is inserted into the clamping head, the upper end of the welding needle passes through the clamping head to form an upper section exposed above the clamping head, and the lower end of the welding needle extends downward to form a lower section.

5. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries as claimed in claim 4, characterized in that: The bottom of the pressure follower is provided with a horizontally arranged cantilever and a moving rod that drives the cantilever to move up and down. The upper part of the moving rod is connected to the pressure follower, and the lower part of the moving rod is connected to the inner end of the cantilever. The outer end of the cantilever extends horizontally away from the moving rod. The outer end of the cantilever is connected to a longitudinally arranged pressure head, and the pressure head is movably abutted on the upper section.

6. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries as claimed in claim 5, characterized in that: The movable frame is provided with a clamping seat, the movable rod is passed through the clamping seat, and the clamping seat is located between the pressure follower and the cantilever.

7. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries according to claim 6, characterized in that: The movable frame includes a longitudinal plate movably connected to the frame body and movable longitudinally along the frame body, the pressure follower is mounted on the longitudinal plate, the longitudinal plate is connected to a transverse plate, and the clamping head is mounted on the transverse plate; the longitudinal plate is connected to a driving structure, and the driving structure drives the movable frame to move longitudinally relative to the frame body.

8. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries as claimed in claim 7, characterized in that: The driving structure includes a connecting rod, the upper end of the connecting rod is hinged to an upper connecting plate, the upper connecting plate is fixedly connected to the moving frame, and the lower end of the connecting rod is hinged to a lower connecting plate, the lower connecting plate is connected to the moving block that moves longitudinally; A screw that rotates in situ is passed through the moving block, the screw is threadedly connected to the moving block, and the screw is connected to a motor. When the motor drives the screw to rotate in situ, the moving block moves longitudinally along the screw, and the connecting rod drives the moving frame to move longitudinally along the frame body.

9. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries according to any one of claims 4 to 8, characterized in that: A disconnecting seam is provided in the clamping head, and the disconnecting seam passes through the clamping head up and down, the outer side of the disconnecting seam passes through the peripheral side of the clamping head, and the inner side of the disconnecting seam is placed inside the clamping head, forming a closed arrangement; the middle part of the disconnecting seam is respectively recessed outward to form a clamping channel, and the clamping channel passes through the clamping head up and down, the welding needle is inserted into the clamping channel, and the upper section passes through the clamping channel and extends to the top of the clamping head.

10. The welding machine for avoiding cold welding of negative electrodes of lithium-ion cylindrical batteries according to claim 9, characterized in that: The disconnection seam divides the clamping head into two power supply parts connected as one body, and the two power supply parts are respectively connected to the positive pole and the negative pole of the power supply, so that the welding needle is energized to weld the negative electrode tab and the battery shell.

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