Resistance welding device and resistance welding method of current collector assembly

Abstract

The present invention discloses a resistance welding device, including a first electrode and a second electrode arranged relatively to each other; and a puncture ejector pin, wherein the puncture ejector pin is used to puncture at least part of the laminated weldment of the current collector assembly before welding, so that a puncture area is formed on the laminated weldment, the first electrode and the second electrode can move relatively and clamp the current collector assembly, and weld the current collector assembly in a power-on state. At the same time, a resistance welding method for the current collector assembly is also disclosed, including: using the puncture ejector pin to puncture at least part of the laminated weldment of the current collector assembly, so that the welding area of ​​the laminated weldment is formed with a puncture area; clamping the current collector assembly between the first electrode and the second electrode, and adjusting the orthographic projection area of ​​the first electrode to completely cover the puncture area of ​​the laminated weldment; turning on the power supply, and performing resistance welding on the puncture area of ​​the current collector assembly, which solves the problem that the existing pole ear and pole are prone to cold welding during the resistance welding process.

Description

Technical Field

[0001] The invention relates to the field of batteries, and in particular to a resistance welding device and a resistance welding method for a current collector assembly. Background Art

[0002] Resistance welding refers to a welding method that uses the resistance heat effect generated by the current flowing through the contact surface of the weldment and the adjacent area as a heat source to heat the local metal of the weldment to a molten or plastic nugget, and then pressurizes the nugget to solidify and crystallize under pressure to form a metal bond. Resistance welding has the advantages of concentrated welding heat, short heating time, high welding efficiency, small welding deformation, and no need to fill welding materials during the welding process. Resistance welding has become one of the welding technologies selected in the battery manufacturing industry, such as the connection process of the current collector assembly (between the pole and the lug).

[0003] Usually, during resistance welding, the area under great pressure will fit most closely with the pole ear, and the resistance in the area under great pressure is low, and the large current mainly flows through this area. Since the contact surface area of ​​the existing pole weldment is large, when the contact surface of the pole weldment is subjected to uniform force during resistance welding, the pressure area is large, and the difference between the resistance in the pressure area and the resistance in the adjacent area is not obvious. At the same time, in the actual production process, no matter how much pressure is increased, the problem of welding shunt will easily occur, resulting in the phenomenon of cold welding, which cannot meet the welding requirements. Summary of the invention

[0004] In order to overcome at least one of the defects of the above-mentioned prior art, the present invention provides a resistance welding device and a resistance welding method for a current collector assembly, which solves the problem that cold welding is easy to occur between the existing pole lugs and poles during resistance welding.

[0005] The technical solution adopted by the present invention to solve the problem is:

[0006] A resistance welding device, comprising:

[0007] A first electrode and a second electrode disposed opposite to each other; and

[0008] A puncture ejector pin, which is used to puncture at least a portion of the laminated weldment of the current collector assembly before welding, so that a puncture area is formed on the laminated weldment;

[0009] The first electrode and the second electrode can move relative to each other and clamp the current collector assembly, and in a power-on state, the current is distributed in the surrounding area of ​​the puncture area to weld the puncture area of ​​the current collector assembly.

[0010] At the same time, a resistance welding method of a current collector assembly is also disclosed, comprising:

[0011] Using a puncture ejector needle to puncture at least a portion of the laminated weldment of the current collector assembly, so that a puncture area is formed in the welding area of ​​the laminated weldment;

[0012] The current collector assembly is sandwiched between the first electrode and the second electrode, and the orthographic projection area of ​​the first electrode is adjusted to completely cover the welding area of ​​the laminated weldment;

[0013] The power supply is turned on to perform resistance welding on the puncture area of ​​the current collector assembly.

[0014] In summary, the resistance welding device and the resistance welding method of the current collector assembly provided by the present invention have the following technical effects:

[0015] The current collector assembly can complete the puncture area forming process and the resistance welding process on the same device. In this way, not only does it not need to be clamped and positioned between different devices, it greatly improves the accuracy and quality of resistance welding, and also avoids the problem of welding spatter or cold welding caused by misalignment during the secondary clamping process.

[0016] More importantly, by utilizing the forming process of the puncture area, a small amount of deformation generated during the puncture process of the laminated weldment of the current collector assembly can be preliminarily connected and positioned, thereby achieving a pre-fixing effect before the resistance welding process.

[0017] At the same time, the use of the piercing area can effectively reduce the pressure area of ​​the welding area during resistance welding and reduce the contact resistance in the pressure area. At this time, along the axial cross section of the piercing area, when the current flows through the stacked weldment of the current collector assembly, the current is distributed on both sides of the piercing area, and the unit area of ​​the current flowing through a single side is much smaller than the unit area of ​​the formed piercing area, that is, the current density per unit area on a single side is more concentrated, which is conducive to the formation and growth of the molten core, and eliminates the problem of cold welding of the current collector assembly during resistance welding.

[0018] The above and other objects, features and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings which show preferred embodiments of the present invention as illustrative examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a first exploded structural diagram of a resistance welding device of the present invention;

[0020] Figure 2 A second exploded structural diagram of a resistance welding device according to the present invention;

[0021] Figure 3 It is a first top view schematic diagram of a resistance welding device of the present invention;

[0022] Figure 4 for Figure 3 A cross-sectional view of the middle AA position;

[0023] Figure 5 for Figure 4 A partial enlarged schematic diagram of point B in the middle;

[0024] Figure 6 A second top view schematic diagram of a resistance welding device of the present invention;

[0025] Figure 7 for Figure 6 Schematic cross-sectional view of the CC position;

[0026] Figure 8 for Figure 7 A partial enlarged schematic diagram of point D in the middle;

[0027] Fig. 9 The figure is a schematic diagram of current flow in a resistance welding device of the present invention.

[0028] Icons: 1-first electrode, 11-ejector guide, 2-second electrode, 3-puncture ejector, 4-current collector assembly, 41-laminated weldment, 42-pole weldment, 43-puncture area, 5-solder pad. DETAILED DESCRIPTION

[0029] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] First embodiment

[0033] Figure 1 A first exploded structural diagram of a resistance welding device of the present invention is shown. Figure 2 The second exploded structure diagram of a resistance welding device of the present invention is shown. Figure 1 and Figure 2 As shown, the present invention discloses a resistance welding device, including a resistance welding body, a first electrode 1, a second electrode 2 and a puncture ejector 3, wherein the first electrode 1 and the second electrode 2 are both installed on the execution end of the driving component of the resistance welding body, and the connection and assembly of the first electrode 1 and the second electrode 2 on the resistance welding body belong to the mature prior art known in the field of resistance welding. Therefore, the resistance welding body is not shown in the figure and will not be described in detail here.

[0034] However, it should be noted that under the driving action of the driving component of the resistance welding body, the first electrode 1 and the second electrode 2 can generate relative movement, so that the first electrode 1 and the second electrode 2 jointly exert a force on the weldment or make the first electrode 1 and the second electrode 2 leave the weldment. The weldment in this embodiment is a current collector assembly 4, and the current collector is a part or component used to collect current in a battery, such as a pole ear, a pole column, a foil, a adapter, etc., wherein a laminated weldment 41 of the current collector assembly 4 can be formed by stacking multiple layers of pole ears, and a laminated weldment 41 of the current collector assembly 4 can also be formed by stacking multiple layers of foil, or the laminated weldment 41 of the current collector assembly 4 can also be formed by stacking multiple layers of adapters, then the current collector assembly 4 can be only a laminated weldment 41, or a laminated weldment 41 with a pole column weldment 42, and this embodiment is described with a laminated weldment 41 with a pole column weldment 42 as the current collector assembly 4.

[0035] Furthermore, the puncture pin 3 is used to pierce at least a portion of the laminated weldment 41 of the current collector assembly 4 before welding, so that a puncture area 43 is formed on the laminated weldment 41, that is, Fig. 9 The schematic diagram of current flow of a resistance welding device of the present invention is shown, in which the piercing ejector pin 3 can pierce a part of the pole ear of the laminated weldment 41, while the other part of the laminated weldment 41 is not pierced. In this case, the piercing area 43 formed on the laminated weldment 41 is a countersunk hole, or the piercing ejector pin 3 can completely penetrate each layer of the pole ear of the laminated weldment 41, in this case, the piercing area 43 formed on the laminated weldment 41 is a through hole.

[0036] As one of the preferred implementations, specifically combined with Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown, the first electrode 1 is provided with an ejector guide 11 inside, and the puncture ejector 3 is provided inside the ejector guide 11 . The puncture ejector 3 can pierce the laminated weldment 41 along the extension direction of the ejector guide 11 and reset into the ejector guide 11 .

[0037] Specifically, the aperture size of the ejector guide channel 11 can be adapted to the diameter size of the puncture ejector 3. Of course, the aperture size of the ejector guide channel 11 can be larger than the diameter size of the puncture ejector 3. The ejector guide channel 11 is preferably arranged at the center position of the first electrode 1, and the extension direction of the ejector guide channel 11 coincides with the central axis of the second electrode 2. In this way, when the puncture ejector 3 slides along the extension direction of the ejector guide channel 11 and acts on the current collector assembly 4, the puncture ejector 3 will puncture the laminated weldment 41 of the current collector perpendicular to the current collector assembly 4.

[0038] In addition to the above-mentioned manner in which the extension direction of the ejector guide path 11 coincides with the central axis of the second electrode 2, the ejector guide path 11 can also form a certain angle with the central axis of the second electrode 2. In this way, when the puncture ejector pin 3 slides along the extension direction of the ejector guide path 11 and acts on the current collector assembly 4, the puncture ejector pin 3 is inclined to the current collector assembly 4 for puncturing. The central axis of the formed puncture area 43 is inclined to the contact surface between the laminated weldment 41 and the pole weldment 42, and the inclination angle between the central axis of the puncture area 43 and the contact surface is preferably between 88° and 92°.

[0039] It should be noted that, in the above, the second electrode 2 may be provided with an ejector guide 11, so that both the first electrode 1 and the second electrode 2 are provided with an ejector guide 11, and the puncture ejector 3 may penetrate and partially extend into the ejector guide 11 of the second electrode 2, thereby ensuring that the laminated weldment 41 can be completely penetrated. Of course, the ejector guide 11 of the second electrode 2 is also provided with a puncture ejector 3, and at this time, the laminated weldment 41 is punctured by two puncture ejector needles 3.

[0040] The state of the puncture ejector 3 inside the ejector guide 11 can be that the puncture ejector 3 is completely placed inside the ejector guide 11, or that the puncture ejector 3 is at least partially exposed outside the ejector guide 11, so as to puncture the laminated weldment 41.

[0041] In this embodiment, the resistance welding process of the resistance welding device on the current collector assembly 4 is as follows:

[0042] The first electrode 1 and the second electrode 2 clamp the current collector assembly 4, so that the stacked weldment 41 of the current collector assembly 4 and the pole weldment 42 are pressed tightly together;

[0043] The resistance welding machine then drives the puncture ejector 3 to puncture the stacked weldment 41 of the current collector assembly 4 to form a puncture area 43;

[0044] After completing the forming process of the puncture area 43, the resistance welding body drives the puncture pin 3 to reset and turns on the power. When the power is on, the current flows through the first electrode 1, the current collector assembly 4 and the second electrode 2 in sequence. At this time, the current is distributed in the surrounding area of ​​the puncture area 43 to complete the resistance welding process of the current collector assembly 4.

[0045] It should be noted that the above-mentioned peripheral area should be understood as the area formed between the boundary of the pressure area and the boundary of the puncture area 43 during the resistance welding process, that is, the pole weldment 42 and the stacked weldment 41 are in abutment contact during the resistance welding process, and the contact surface between the pole weldment 42 and the stacked weldment 41 is the pressure area. The puncture area 43 is located inside the pressure area, and the peripheral area is the pressure area excluding the puncture area 43.

[0046] At this time, when the current flows through the current collector assembly 4, it cannot enter the puncture area 43, and can only flow in a concentrated manner from the peripheral area, and the puncture area 43 is used to guide the current flowing through the current collector assembly 4. At the same time, since the contact surface between the pole welding piece 42 and the stacked welding piece 41 is reduced, the pressure area is reduced, and the force of the current collector assembly 4 during the pressure process is concentrated in the peripheral area, and the resistance of the peripheral area will be greatly reduced, thereby effectively avoiding the problem of welding shunting caused by uniform force during resistance welding.

[0047] Therefore, according to Fig. 9 As shown, on the axial cross section along the puncture area 43, when the current flows through the stacked weldment 41 of the current collector assembly 4, the current flowing through the axial cross section is concentrated on both sides of the puncture area 43. In this way, the unit area of ​​the current flowing through a single side is much smaller than the unit area of ​​the unformed puncture area 43, that is, the current density within the unit area of ​​a single side is more concentrated, so that the heat of resistance welding is more concentrated, which is conducive to the formation and growth of the molten core, thereby effectively avoiding the problem of cold welding of the current collector assembly 4 during the resistance welding process.

[0048] In addition, when the puncture pin 3 pierces the laminated weld 41 of the current collector assembly 4, it will pierce the oxide layer on the surface of the pole ear, which will reduce the impedance of the laminated weld 41 and its current collector assembly 4, and is also conducive to the formation and growth of the molten core, thereby further avoiding the problem of cold welding of the current collector assembly 4 during the resistance welding process.

[0049] It should be noted that the above process method is only used as an example and is not limited to the process method. It can be adjusted according to the operation setting of the resistance welding device or the actual operation experience of the operator. For example, while the first electrode 1 and the second electrode 2 clamp the current collector assembly 4, the tip of the puncture ejector 3 abuts against the stacked weldment 41, and then the puncture ejector 3 is driven to perform the puncture action. Alternatively, the forming process of the puncture area 43 is completed before the first electrode 1 and the second electrode 2 clamp the current collector assembly 4.

[0050] It should also be noted that the puncture ejector 3 can be fixed to the driving component of the resistance welding machine body through an adjusting member, and the adjusting member adjusts the length of the puncture ejector 3 extending out of the ejector guide 11, that is, adjusts the depth of the puncture area 43 formed on the laminated weldment 41. Preferably, a punching component is separately configured on the driving component, and the puncture ejector 3 is installed at the execution end of the punching component, so that under the action of the punching component, the puncture ejector 3 is driven to puncture the current collector assembly 4. The punching component can be a cylinder, a hydraulic cylinder, or an electric cylinder.

[0051] Second embodiment

[0052] Based on the resistance welding device provided in the first embodiment, the inventor also provides another preferred implementation, which is different from the first embodiment only in that:

[0053] Please combine the specific Figure 2 , Figure 6 , Figure 7 and Figure 8 As shown, the puncture needle 3 is arranged on one side of the first electrode 1 , and the puncture needle 3 and the first electrode 1 can act on the current collector assembly 4 in sequence in a first direction, and the first direction is the extension direction along the central axis of the second electrode 2 .

[0054] In this embodiment, the puncture ejector 3 moves on the outside of the first electrode 1. In this way, a manipulator can be configured on the resistance welding body, and the puncture ejector 3 is installed at the execution end of the manipulator to adjust or change the relative position between the puncture ejector 3 and the second electrode 2. Alternatively, the resistance welding body has a transmission mechanism that can rotate and / or translate, and the driving component and the punching component are both installed on the transmission mechanism. The driving component and the punching component are independently arranged. Here, the punching component can be a cylinder, or a hydraulic cylinder, or an electric cylinder. The punching component is used to drive the puncture ejector 3 to puncture the current collector assembly 4. In this way, when the resistance welding device performs the forming process of the puncture area 43, under the action of the rotation of the mechanism, the puncture ejector 3 rotates or translates to the position of the current collector assembly 4. When the resistance welding device performs the resistance welding process, under the action of the rotation of the mechanism, the first electrode 1 rotates or translates to the position of the current collector assembly 4, and the puncture ejector 3 is reset synchronously.

[0055] Of course, other devices or mechanisms that can enable the puncture needle 3 and the first electrode 1 to act on the current collector assembly 4 in sequence in the first direction can be used as alternatives to this embodiment.

[0056] Thus, the resistance welding process of the resistance welding device of this embodiment on the current collector assembly 4 is as follows:

[0057] The resistance welding machine drives the puncture ejector 3 to move to the orthographic projection area of ​​the second electrode 2 along the first direction, that is, in the first direction of the current collector assembly 4, and punctures the laminated weldment 41 of the current collector assembly 4 to form a puncture area 43;

[0058] After the forming process of the puncture area 43 is completed, the resistance welding machine body drives the puncture ejector 3 to reset;

[0059] The resistance welding machine drives the puncture ejector pin 3 to reset, and drives the first electrode 1 to move to the orthographic projection area of ​​the second electrode 2 along the first direction, that is, in the first direction of the current collector assembly 4, and then drives the first electrode 1 and the second electrode 2 to move relative to each other until the first electrode 1 and the second electrode 2 clamp the current collector assembly 4. Finally, the power is turned on. In the power-on state, the current flows through the first electrode 1, the current collector assembly 4 and the second electrode 2 in sequence. At this time, the current is distributed around the peripheral area of ​​the puncture area 43 to complete the resistance welding process of the current collector assembly 4.

[0060] Third embodiment

[0061] Based on the resistance welding device disclosed in the first embodiment and the second embodiment, the inventors also provide a resistance welding method for a current collector assembly 4 using the resistance welding device, including:

[0062] Step 1, using the puncture ejector needle 3 to puncture at least part of the laminated weldment 41 of the current collector assembly 4, so that the welding area of ​​the laminated weldment 41 is formed with a puncture area 43, that is, using the tip of the puncture ejector needle 3 to puncture and penetrate the laminated weldment 41 to form the puncture area 43 in the form of a through hole, or using the tip of the puncture ejector needle 3 to puncture part of the laminated weldment 41 to form the puncture area 43 in the form of a countersunk hole;

[0063] It should be noted that the stacked weldment 41 includes a plurality of layers of tabs. The forming puncture area 43 of the stacked weldment 41 also includes punching the tabs of the stacked weldment 41 and stacking the tabs. In addition, when implementing the process of forming the puncture area 43 of the welding area of ​​the stacked weldment 41 in step 1, the following steps may be optionally included:

[0064] Step 11-a, at least part of the tab is punched by the puncture ejector 3;

[0065] Step 12-a, stacking several layers of tabs, and adjusting the through holes of two adjacent tabs to at least partially overlap.

[0066] Alternatively, the following steps may be optionally included to replace Step 11-a and Step 12-a:

[0067] Step 11-b, stacking several layers of tabs;

[0068] Step 12-b, using the puncture ejector needle 3 to perform sequential punching processing on at least part of the tabs.

[0069] Step 2, sandwiching the current collector assembly 4 between the first electrode 1 and the second electrode 2, and adjusting the orthographic projection area of ​​the first electrode 1 along the second direction to completely cover the welding area of ​​the laminated weldment 41, the second direction being the extending direction along the central axis of the first electrode 1;

[0070] Step 3, turn on the power supply and perform resistance welding on the puncture area 43 of the current collector assembly 4.

[0071] In this embodiment, the resistance welding device of the first embodiment or the second embodiment is cleverly used to perform a process of first forming the puncture area 43 on the laminated weldment 41 of the current collector assembly 4 and then performing resistance welding.

[0072] For example, in step 11-a and combined with step 12-a, several layers of pole ears are first punched layer by layer on the resistance welding device, and then stacked. The through holes of several layers of pole ears are coaxial and connected in sequence, forming a puncture area 43 in the form of a through hole. Alternatively, several layers of pole ears are first separated into two parts, one part is the pole ears that need to be punched, and the other part is the pole ears that do not need to be punched. After the pole ears that need to be punched are punched layer by layer on the resistance welding device, the pole ears that have been punched and the pole ears that do not need to be punched are stacked, and the through holes of several layers of pole ears are coaxial and connected in sequence, forming a puncture area 43 in the form of a countersunk hole. In the implementation of the above-mentioned punching process, the first electrode 1 and the second electrode 2 do not need to perform any action. The resistance welding device only needs to control the puncture ejector 3 to perform the puncture action until the punching of the pole ears is completed, and then several layers of pole ears are stacked, and then the subsequent resistance welding process is performed.

[0073] For another example, step 11-b and combined step 12-b are different from step 11-a and combined step 12-a in that a plurality of layers of tabs are stacked first, and then placed on a resistance welding device to perform hole punching on the multiple layers of tabs. At this time, the resistance welding device is used to adjust the penetration force and penetration depth of the puncture ejector 3 so that the puncture area 43 formed by the stacked weldment 41 is a through hole or a countersunk hole. In this way, resistance welding can be performed after the process of forming the puncture area 43 is completed, which is faster and more efficient.

[0074] It should be noted that step Step 1 and step Step 2 can be swapped, that is, the current collector assembly 4 is first clamped between the first electrode 1 and the second electrode 2, and the orthographic projection area of ​​the first electrode 1 is adjusted along the second direction to completely cover the welding area of ​​the laminated weld 41, and then the puncture pin 3 is used to pierce at least part of the laminated weld 41 of the current collector assembly 4, so that the welding area of ​​the laminated weld 41 is formed with a puncture area 43, that is, the current collector assembly 4 is first clamped and fixed by the cooperation between the first electrode 1 and the second electrode 2, and then the puncture pin 3 is used to form the puncture area 43 on the laminated weld 41 of the current collector assembly 4.

[0075] In the above-mentioned punching process, the puncture portion of the electrode ear, that is, the edge of the through hole will be deformed toward one side of the puncture direction, so that several layers of electrode ears are not easily displaced when they are stacked and during the resistance welding process. The puncture area 43 formed by the stacked weldment 41 also provides an unexpected effect of welding positioning for the subsequent resistance welding process, that is, in the subsequent resistance welding process, the puncture area 43 of the stacked weldment 41 is positioned within the orthographic projection area of ​​the second electrode 2 along the first direction and the orthographic projection area of ​​the first electrode 1 along the second direction, where the second direction is the extension direction along the central axis of the first electrode 1.

[0076] In addition, the puncture area 43 formed by the laminated weldment 41 also achieves the purpose of reducing the material of the laminated weldment 41. On the one hand, the contact surface between the pole weldment 42 and the laminated weldment 41 is reduced, the pressure area is reduced, and the force of the current collector assembly 4 during the pressure process is concentrated on the surrounding area of ​​the puncture area 43, then the resistance of the surrounding area will be greatly reduced, thereby effectively avoiding the problem of welding shunt caused by uniform force during resistance welding. On the other hand, the current cannot pass through the puncture area 43, that is, the current path is limited and can only surround the surrounding area of ​​the puncture area 43. In this way, the puncture area 43 plays a better role in guiding the current and makes the current density more concentrated, which is conducive to more concentrated heat during resistance welding.

[0077] What is even more unexpected is that, since the material of the pole ear is usually aluminum metal, an oxide film will be generated on the outer surface of the pole ear during the production process, and the impedance of the oxide film is relatively high, which increases the contact resistance generated by the laminated weldment 41 and the pole weldment 42 during the resistance welding process. In particular, when the number of layers of the pole ear increases, the difference between the resistance in the pressure area and the resistance in the adjacent non-welding area will be closer, so that the large current will be diverted to the adjacent non-welding area, which will cause a cold weld during the resistance welding process. When the puncture area 43 formed by the laminated weldment 41 punctures the oxide layer on the pole ear, it is also conducive to the increase of current density, further increasing the heat of resistance welding, and facilitating the formation and growth of the molten nugget.

[0078] Based on the above analysis, it can be seen that the puncture ejector pin 3 is used to form the puncture area 43 of the stacked weldment 41, and the first electrode 1 and the second electrode 2 are resistively welded, which can effectively solve the problem of spatter or cold welding during resistance welding, thereby improving the welding quality and production efficiency of the current collector assembly 4.

[0079] As a preferred method of this embodiment, please refer to Figure 2 , Figure 3 and Figure 8 As shown, a soldering sheet 5 is sandwiched between the second electrode 2 and the laminated welding member 41 of the current collector assembly 4. The soldering sheet 5 can prevent the second electrode 2 and the laminated welding member 41 from being adhered after resistance welding.

[0080] It must be noted that, when pre-punching is performed using the puncture pin 3 , the soldering sheet 5 can be disposed between the first electrode 1 and the laminated weld 41 of the current collector assembly 4 , and / or between the second electrode 2 and the laminated weld 41 of the current collector assembly 4 .

[0081] As can be seen from the above, due to the presence of an oxide layer on the surface of the pole ear, when the oxide layer on the surface of the pole ear is not broken by punching, the overall impedance of the laminated weldment 41 is relatively high, resulting in an increase in the contact resistance generated by the laminated weldment 41 and the pole weldment 42 during resistance welding, thereby causing the current collector assembly 4 to easily shunt during welding. With regard to this problem, the inventor also provides a further preferred method:

[0082] The number of layers of the electrode tabs that have been punched is defined as the number of processed layers, and the ratio of the number of processed layers to the total number of layers of the laminated weldment 41 is in the range of 10% to 100%.

[0083] When the ratio of the number of processed layers to the total number of layers of the laminated weldment 41 reaches 100%, that is, each layer of the tabs of the laminated weldment 41 will be perforated, which avoids the shunting phenomenon of the current collector assembly 4 during the welding process to the greatest extent, and effectively avoids the problem of cold welding of the current collector assembly 4 during the welding process. When the ratio of the number of processed layers to the total number of layers of the laminated weldment 41 is less than 10%, the number of tabs that have been perforated is too small, which not only makes the overall impedance of the laminated weldment 41 still high, but also because the depth of the puncture area 43 is small, that is, the current path is less constrained, resulting in a significant decrease in the welding effect, and the problem of cold welding of the current collector assembly 4 during the welding process cannot be effectively solved.

[0084] Fourth embodiment

[0085] In the third embodiment, in order to solve the problem that the current collector assembly 4 is prone to shunting during welding due to the presence of an oxide layer on the surface of the tab, the inventor proposes a solution for controlling the ratio between the number of processed layers and the total number of layers of the laminated weldment 41. In addition, the inventor discloses another preferred method:

[0086] The only difference from the third embodiment is that the current collector assembly 4 also includes a pole weldment 42, and the area of ​​the contact surface of the laminated weldment 41 for abutting the pole weldment 42 is defined as the contact area S, and the area of ​​the through hole of the pole ear is the puncture area s. The puncture area S and the contact area s satisfy the following relationship: puncture area s / contact area S=0.1~0.7.

[0087] Among them, when the ratio of the puncture area s to the contact area S is less than 0.1, the puncture area s is too small, while the contact area S and the contact surface between adjacent pole ears in the stacked weldment 41 are both large, which will cause the contact resistance generated during the resistance welding process to be still large, and the current collector assembly 4 is still prone to shunt problems during the welding process, thereby affecting the welding effect.

[0088] When the ratio of the puncture area s to the contact area S is greater than 0.7, the puncture area s is too large, and the single-side width of the cross-section of the peripheral area of ​​the puncture area 43 perpendicular to the central axis direction of the puncture area 43 will become smaller, resulting in too little solder in the peripheral area (i.e., the welding area), which causes welding abnormalities such as bubbles after resistance welding, thereby affecting the welding strength.

[0089] Maintaining the puncture area s / contact area S within the range of 0.1 to 0.7 can not only effectively solve the problem of shunt of the current collector assembly 4 during welding, but also effectively ensure the welding strength of the current collector assembly 4, thereby effectively ensuring the welding quality of the current collector assembly 4.

[0090] It should be noted that when the current collector assembly 4 is only a stacked weldment 41, the contact area S should be understood as the area of ​​the welding area, that is, the welding area formed between the first electrode 1, the second electrode 2 and the stacked weldment 41 should also satisfy the relationship between the puncture area S and the contact area s as above.

[0091] It should also be noted that the solution disclosed in this embodiment can be used in combination with the solution disclosed in the third embodiment for controlling the ratio between the number of processed layers and the total number of layers of the laminated weldment 41 .

[0092] Fifth embodiment

[0093] In view of the problem that the current collector assembly 4 is prone to shunting during welding due to the presence of an oxide layer on the surface of the tab, the inventors have also disclosed another preferred method:

[0094] Different from the third and fourth embodiments, the contact surface of the stacked weldment 41 for abutting against the pole weldment 42 is defined as the reference plane, the center points of the through holes of several pole ears are sequentially connected to form a stacking line, and the angle between the stacking line and the reference plane ranges from 88° to 92°.

[0095] Specifically, the above-mentioned stacking line is the central axis of the puncture area 43. When the angle between the stacking line and the reference plane is in the range of 88° to 92° for resistance welding, the local internal resistance of the peripheral area (i.e., the welding area) can be reduced, thereby improving welding efficiency and welding strength. When the angle between the stacking line and the reference plane is less than 88° or greater than 92°, the local pole ear in the stacked weldment 41 increases the internal resistance of the stacked weldment 41 at this position due to the presence of the oxide layer, which leads to the problem of cold welding at this position of the stacked weldment 41 during resistance welding, thereby affecting the welding effect.

[0096] As a further preferred embodiment of the present invention, the stacking line coincides with the center line of the pole weld 42. That is, the stacking line is perpendicular to the reference plane to avoid the problem of partial cold welding of the stacking weld 41 during resistance welding. At the same time, the puncture area 43 is located at the center of the pole weld 42. In this way, when the first electrode 1 and the second electrode 2 apply pressure to the pole weld 42 and the stacking weld 41, the center of the weld mark can be evenly distributed inside the pressure area, thereby effectively avoiding the problem of weld mark deviation.

[0097] It should be noted that the scheme disclosed in this embodiment can be used in combination with the scheme for controlling the ratio between the number of processed layers and the total number of layers of the stacked weldment 41 disclosed in the third embodiment, and can also be used in combination with the scheme for controlling the ratio between the puncture area s and the contact area S disclosed in the fourth embodiment, or the scheme of this embodiment can be combined with the schemes of the third embodiment and the fourth embodiment.

[0098] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A resistance welding device, characterized in that: include: A first electrode (1) and a second electrode (2) arranged opposite to each other; as well as A puncture ejector pin (3), the puncture ejector pin (3) being used to puncture at least a portion of the laminated weldment (41) of the current collector assembly (4) before welding, so that a puncture area (43) is formed on the laminated weldment (41); The first electrode (1) and the second electrode (2) can move relative to each other and clamp the current collector assembly (4), and in a power-on state, weld the puncture area (43) of the current collector assembly (4); An ejector guide path (11) is provided inside the first electrode (1), the puncture ejector (3) is provided inside the ejector guide path (11), and the puncture ejector (3) is capable of piercing the laminated weldment (41) along the extension direction of the ejector guide path (11) and resetting into the ejector guide path (11).

2. A resistance welding method for a current collector assembly, applied to the resistance welding device as claimed in claim 1, characterized in that: include: Using a puncture pin (3) to pierce at least a portion of the laminated weldment (41) of the current collector assembly (4), so that a puncture area (43) is formed in the welding area of ​​the laminated weldment (41); The current collector assembly (4) is sandwiched between the first electrode (1) and the second electrode (2), and the orthographic projection area of ​​the first electrode (1) along a second direction is adjusted to completely cover the welding area of ​​the laminated weldment (41), wherein the second direction is a direction extending along the central axis of the first electrode (1); The power supply is turned on, and the puncture area (43) of the current collector assembly (4) is subjected to resistance welding.

3. The resistance welding method of the current collector assembly (4) according to claim 2, characterized in that: The stacked weldment (41) comprises a plurality of layers of pole tabs, at least some of which are punched by the puncture pin (3), and then the plurality of layers of the pole tabs are stacked and the through holes of two adjacent pole tabs are adjusted to at least partially overlap.

4. The resistance welding method of the current collector assembly (4) according to claim 2, characterized in that: The stacked weldment (41) comprises a plurality of layers of pole tabs, wherein the plurality of layers of pole tabs are stacked, and the puncture ejector needle (3) is used to perform a sequential punching process on at least a portion of the pole tabs.

5. The resistance welding method of the current collector assembly (4) according to claim 3 or 4, characterized in that: The number of layers of the electrode tabs that have been punched is defined as the number of processed layers, and the ratio of the number of processed layers to the total number of layers of the laminated weldment (41) is in the range of 10% to 100%.

6. The resistance welding method of the current collector assembly according to claim 3 or 4, characterized in that: The current collector assembly (4) further comprises a pole welding piece (42), wherein the contact surface area of ​​the laminated welding piece (41) for abutting against the pole welding piece (42) is defined as a contact area S, and the area of ​​the through hole of the pole ear is defined as a puncture area s. The puncture area S and the contact area s satisfy the following relationship: puncture area s / contact area S=0.1-0.

7.

7. The resistance welding method of the current collector assembly according to claim 6, characterized in that: A side surface of the stacked weldment (41) close to the first electrode (1) or the second electrode (2) is defined as a reference plane, and the center points of the through holes of the plurality of tabs are sequentially connected to form a stacking line, and the angle between the stacking line and the reference plane is in the range of 88° to 92°.

8. The resistance welding method of the current collector assembly (4) according to claim 7, characterized in that: The stacking line coincides with the center line of the pole weldment (42).

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