Pressure head assembly and tab welding device

Abstract

The embodiment of the utility model provides a pressure head assembly and a tab welding device, and relates to the technical field of battery production. The pressure head assembly comprises a connecting plate, a pressure head, a connecting piece and a return piece, a mounting hole is formed in the connecting plate and comprises a first section and a second section, and the diameter of the first section is larger than that of the second section; the rod body of the connecting piece is connected with the pressure head; the head part of the connecting piece is movably matched with the first section along the axis direction of the mounting hole; the rod body of the connecting piece is movably matched with the second section along the axis direction of the mounting hole; the connecting piece is sleeved with the return piece, and the two ends of the return piece abut against the pressing head and the connecting plate respectively, so that the connecting piece has the trend of moving from the first section to the second section. The pressure head assembly can avoid deformation of the tabs in the welding process, so that the attaching degree of the two tabs which are overlapped together becomes poor, and the phenomena of insufficient welding and breakdown of the tabs are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of battery production, in particular to a pressure head assembly and a tab welding device. Background Art

[0002] In the current battery module preparation process, the laser welding method of the pole ear is usually to press the equipment head down when the module reaches the welding position, and then start to emit light for welding; in this process, the overlap welding method is usually adopted, that is, the two pole ears are overlapped and welded.

[0003] However, due to the thin thickness of the tabs and the long length of the welding points, the tabs will deform during the welding process and the overlapping area of ​​the two tabs cannot be compacted, resulting in poor fit between the two tabs, and further leading to cold welding and breakdown of the tabs, thereby affecting the product quality of the battery module. Utility Model Content

[0004] The purpose of the utility model is to provide a pressure head assembly and a pole ear welding device, which can apply a certain pressure to the pressure head through a return member to compact the pole ear, and through the cooperation of the connecting member and the mounting hole, limit the moving distance of the connecting member in the axial direction of the mounting hole, thereby avoiding deformation of the pole ear during the welding process, which leads to poor fit of the two overlapping pole ears, and further avoids the phenomenon of cold welding and breakdown of the pole ear, so as to ensure the product quality of the battery module.

[0005] The embodiment of the utility model is achieved as follows:

[0006] In a first aspect, the utility model provides a pressure head assembly, the pressure head assembly includes a connecting plate, a pressure head, a connecting member and a return member;

[0007] The connecting plate is provided with a mounting hole, the mounting hole includes a first segment and a second segment, and the diameter of the first segment is greater than the diameter of the second segment;

[0008] The rod body of the connecting piece is connected to the pressure head; the head of the connecting piece is movably matched with the first segment along the axis direction of the mounting hole; the rod body of the connecting piece is movably matched with the second segment along the axis direction of the mounting hole;

[0009] The return member is sleeved on the connecting member, and two ends of the return member are respectively abutted against the pressure head and the connecting plate, so that the connecting member has a tendency to move from the first segment toward the second segment.

[0010] In an optional embodiment, the pressure head assembly further includes a baffle plate, which is connected to the connecting plate and is located on a side of the connecting plate away from the pressure head;

[0011] One end of the first section facing away from the second section is open; the baffle is used to abut against the head to limit the movement of the head from the second section toward the first section.

[0012] In an optional embodiment, a limiting platform is provided in the first segment, and the limiting platform is spaced apart from the interface between the first segment and the second segment to limit the movement of the head from the second segment toward the first segment.

[0013] In an optional embodiment, two pressure heads are provided, and the two pressure heads are arranged at an interval.

[0014] In an optional embodiment, the pressure head assembly includes a plurality of connecting members, and the connecting plate is provided with a plurality of mounting holes, and each mounting hole is matched with a corresponding connecting member;

[0015] The pressure head comprises a plurality of sub-pressure heads, which are arranged in sequence, and each sub-pressure head is connected to one or more connecting members.

[0016] In an optional embodiment, the sub-pressing head is provided with a boss, which is located on a side of the sub-pressing head away from the connecting member; the area of ​​the contour surface of the boss is smaller than the area of ​​the contour surface of the press head.

[0017] In an optional embodiment, the connecting plate is provided with a first through groove, and the first through groove is directly opposite to the spaced area between the two pressure heads.

[0018] In an optional embodiment, the pressure head assembly further includes a sleeve, which is sleeved on the return member; wherein the length of the sleeve is smaller than the length of the return member in a non-stressed state.

[0019] In an optional embodiment, the return member is a spring, and two ends of the spring are respectively against the connecting plate and the pressure head.

[0020] In a second aspect, the utility model provides a tab welding device, which includes a driving member and a pressure head assembly as described in any one of the aforementioned embodiments, wherein the movable end of the driving member is connected to a connecting plate.

[0021] The beneficial effects of the embodiments of the utility model include:

[0022] The pressure head assembly includes a connecting plate, a pressure head, a connecting piece and a restoring piece; the connecting plate is provided with a mounting hole, the mounting hole includes a first section and a second section, the diameter of the first section is larger than the diameter of the second section; the rod body of the connecting piece is connected to the pressure head; the head of the connecting piece is movably matched with the first section along the axial direction of the mounting hole; the rod body of the connecting piece is movably matched with the second section along the axial direction of the mounting hole; the restoring piece is sleeved on the connecting piece, and the two ends of the restoring piece are respectively abutted against the pressure head and the connecting plate, so that the connecting piece has a tendency to move from the first section toward the second section.

[0023] The pressure head assembly applies a certain pressure to the pressure head through the return member, and limits the moving distance of the connecting member in the axial direction of the mounting hole through the cooperation between the connecting member and the mounting hole, thereby compacting the pole ear and preventing the pole ear from deforming during the welding process, which would lead to a poor fit between the two overlapping pole ears, thereby avoiding cold welding and breakdown of the pole ears and ensuring the product quality of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the structure of a pressure head assembly provided in an embodiment of the utility model;

[0026] Figure 2 A schematic diagram of the structure of the connecting plate provided in an embodiment of the utility model;

[0027] Figure 3 for Figure 2 Sectional view at AA in the middle;

[0028] Figure 4 A schematic diagram of the structure of the connecting plate and the connecting member provided in the embodiment of the utility model;

[0029] Figure 5 for Figure 4 Cross-section at the middle BB;

[0030] Figure 6 for Figure 5 A partial enlarged view of point C in the middle;

[0031] Figure 7 A schematic diagram of the structure of the sub-pressing head and the connecting member provided in an embodiment of the utility model at a first viewing angle;

[0032] Figure 8 A schematic diagram of the structure of the sub-pressing head and the connecting member provided by the embodiment of the utility model at a second viewing angle;

[0033] Fig. 9 A schematic diagram of the structure of the sub-pressing head provided by an embodiment of the utility model at a first viewing angle;

[0034] Fig.10 A schematic diagram of the structure of the sub-pressing head provided by an embodiment of the utility model at a second viewing angle;

[0035] Fig.11A schematic structural diagram of a baffle provided in an embodiment of the utility model.

[0036] Icon: 100-pressure head assembly; 110-connecting plate; 111-mounting hole; 112-first section; 113-second section; 114-first through slot; 120-pressure head; 121-sub-pressure head; 122-boss; 130-connecting member; 131-head; 132-rod body; 140-return member; 150-baffle; 151-second through slot; 160-sleeve. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Due to the thin thickness of the tabs and the long length of the welding points, the tabs will deform during the welding process and the overlapping area of ​​the two tabs cannot be compacted, resulting in poor fit between the two tabs, which in turn leads to cold welding and breakdown of the tabs, thus affecting the product quality of the battery module.

[0044] Based on the above problems, the utility model provides a pole tab welding device, which includes a driving member and a pressure head assembly 100. The movable end of the driving member is connected to the pressure head assembly 100. The driving member is used to drive the pressure head assembly 100 to move in the direction of the pole tab, thereby squeezing the pole tab through the pressure head assembly 100.

[0045] The press head assembly 100 is described in detail below:

[0046] Please refer to Figure 1-Figure 6 , Figure 1 A schematic structural diagram of a pressure head assembly 100 provided in an embodiment of the utility model; Figure 2 A schematic diagram of the structure of the connecting plate 110 provided in an embodiment of the utility model; Figure 3 for Figure 2 Sectional view at AA in the middle; Figure 4 A schematic diagram of the structure of the connecting plate 110 and the connecting member 130 provided in an embodiment of the utility model; Figure 5 for Figure 4 Cross-section at the middle BB; Figure 6 for Figure 5 A partial enlarged view of point C in the middle.

[0047] The pressure head assembly 100 includes a connecting plate 110, a pressure head 120, a connecting member 130 and a restoring member 140; the connecting plate 110 is provided with a mounting hole 111, the mounting hole 111 includes a first segment 112 and a second segment 113, the diameter of the first segment 112 is larger than the diameter of the second segment 113; the rod body 132 of the connecting member 130 is connected to the pressure head 120; the head 131 of the connecting member 130 is movably matched with the first segment 112 along the axial direction of the mounting hole 111; the rod body 132 of the connecting member 130 is movably matched with the second segment 113 along the axial direction of the mounting hole 111; the restoring member 140 is sleeved on the connecting member 130, and the two ends of the restoring member 140 are respectively abutted against the pressure head 120 and the connecting plate 110, so that the connecting member 130 has a tendency to move from the first segment 112 to the second segment 113.

[0048] Specifically, the restoring member 140 is elastic, and by providing the mounting hole 111, the connecting member 130 can move along the axis direction of the mounting hole 111, and the rod body 132 of the connecting member 130 is connected to the pressure head 120, thereby driving the pressure head 120 to move along the axis direction of the mounting hole 111. Since the mounting hole 111 has a first segment 112 and a second segment 113, and the diameter of the first segment 112 is greater than the diameter of the second segment 113, wherein the diameter of the head 131 of the connecting member 130 is smaller than the diameter of the first segment 112 and greater than the diameter of the second segment 113, the head 131 of the connecting member 130 can move in the first segment 112 along the axis direction of the mounting hole 111 and limit the movement of the head 131 from the first segment 112 to the second segment 113.

[0049] It should be noted that the connecting plate 110 extends in a direction perpendicular to the axis of the mounting hole 111, and the extended portion is connected to the driving member. The side of the pressing head 120 away from the connecting member 130 is used to squeeze the pole ear, thereby improving the fit between the two pole ears and avoiding the phenomenon of cold welding and breakdown of the pole ear due to the failure of the pressing head 120 to compact the pole ear during the welding process. In this embodiment, the connecting member 130 is a screw; in other embodiments, a bolt, for example, can be selected as the connecting member 130 according to actual conditions.

[0050] The working principle of the press head assembly 100 is as follows:

[0051] The connecting plate 110 moves toward the direction where the pressure head 120 is located under the action of external force. Since the connecting member 130 and the mounting hole 111 on the connecting plate 110 can be movably matched, the connecting plate 110 and the pressure head 120 can be moved closer to or farther away from each other. In the process of the connecting plate 110 and the pressure head 120 approaching each other, the connecting plate 110 and the pressure head 120 squeeze the restoring member 140, so that the restoring member 140 has elasticity, and a pressure is generated on the pressure head 120. Under the action of pressure, the pressure head 120 can compact the tabs, thereby improving the fit between the two tabs, avoiding the phenomenon of cold welding and breakdown of the tabs, and ensuring the product quality of the battery module.

[0052] Furthermore, the pressing head assembly 100 also includes a baffle 150, which is connected to the connecting plate 110 and is located on the side of the connecting plate 110 away from the pressing head 120; one end of the first segment 112 away from the second segment 113 is open; the baffle 150 is used to abut against the head 131 to limit the movement of the head 131 from the second segment 113 toward the first segment 112.

[0053] Specifically, the baffle 150 is provided to limit the movement of the head 131 in the direction away from the pressure head 120 , that is, to abut against the head 131 and prevent the head 131 from extending out of the first segment 112 .

[0054] The baffle 150 cooperates with the second segment 113 to limit the maximum moving distance of the connecting member 130 in the axial direction of the mounting hole 111. It should be noted that the maximum moving distance of the connecting member 130 in the axial direction of the mounting hole 111 is the difference between the length of the first segment 112 in the axial direction of the mounting hole 111 and the length of the head 131 of the connecting member 130 in the axial direction of the mounting hole 111. In this embodiment, in order to ensure that the connecting member 130 can move in the first segment 112 along the axial direction of the mounting hole 111, the length of the head 131 in the axial direction of the mounting hole 111 should be less than the length of the first segment 112 in the axial direction of the mounting hole 111.

[0055] In this embodiment, the movement distance of the connector 130 is limited to prevent the connector 130 from being separated from the connecting plate 110, and to prevent the pole ear from being deformed during the welding process, which would lead to a poor fit between the two overlapping pole ears, thereby preventing the pole ears from having cold welds and breakdown, thereby ensuring the product quality of the battery module.

[0056] In other embodiments, a limiting platform is provided in the first segment 112, and the limiting platform is spaced apart from the interface between the first segment 112 and the second segment 113 to limit the movement of the head 131 from the second segment 113 toward the first segment 112. The pressure head assembly 100 blocks the head 131 by providing the limiting platform to prevent the head 131 from extending out of the first segment 112.

[0057] It should be noted that, in this embodiment, the restoring member 140 is a spring, and the two ends of the spring are respectively against the connecting plate 110 and the pressing head 120. Thus, the two ends of the spring are respectively against the connecting plate 110 and the pressing head 120, so that the spring can better provide elastic force to the pressing head 120, thereby compacting the tab, and avoiding the occurrence of cold welding and breakdown of the tab. By limiting the moving distance of the connecting member 130, the spring is prevented from plastic deformation and loss of elasticity due to excessive squeezing of the spring by the connecting plate 110 and the pressing head 120.

[0058] Based on the above settings, please refer to Figure 7 and Figure 8 , Figure 7 A schematic diagram of the structure of the sub-pressing head 121 and the connecting member 130 provided in an embodiment of the utility model from a first viewing angle; Figure 8 The schematic diagram of the structure of the sub-pressing head 121 and the connecting member 130 provided by the embodiment of the utility model from a second perspective. The press head assembly 100 further includes a sleeve 160, which is sleeved on the restoring member 140; wherein the length of the sleeve 160 is less than the length of the restoring member 140 in a stress-free state.

[0059] According to the above, in this embodiment, the sleeve 160 is sleeved on the spring, thereby protecting the spring and guiding the spring to shorten or lengthen in the axial direction of the mounting hole 111. It should be noted that the axis of the sleeve 160 coincides with or is parallel to the axis of the mounting hole 111, and the length of the sleeve 160 is less than the length of the spring in a non-stressed state, thereby avoiding obstruction to the movement of the connector 130.

[0060] It should be noted that in this embodiment, when the ram assembly 100 is in the initial state, the difference between the length of the spring and the length of the sleeve 160 is less than or equal to the maximum moving distance of the connector 130. The initial state of the ram assembly 100 is a state where the head 131 abuts against the interface between the first segment 112 and the second segment 113.

[0061] For further information, please refer to Figure 1 There are two pressing heads 120, and the two pressing heads 120 are arranged at intervals. Through the cooperation between the two pressing heads 120, the pressing heads 120 can compact the tabs, avoiding the phenomenon that the two ends of the tabs are lifted up during the pressing process of the pressing heads 120, thereby causing the phenomenon of cold welding and breakdown due to the deformation of the tabs.

[0062] Based on the above settings, please refer to Figure 7-10 , Fig. 9 A schematic diagram of the structure of the sub-pressing head 121 provided in an embodiment of the utility model at a first viewing angle; Fig.10A schematic diagram of the structure of the sub-pressing head 121 provided in the embodiment of the utility model under the second viewing angle. The press head assembly 100 includes a plurality of connectors 130, and the connecting plate 110 is provided with a plurality of mounting holes 111, each mounting hole 111 corresponds to a connector 130; the press head 120 includes a plurality of sub-pressing heads 121, and the plurality of sub-pressing heads 121 are arranged in sequence, and each sub-pressing head 121 is connected to one or more connectors 130. The sub-pressing head 121 is provided with a boss 122, and the boss 122 is located on the side of the sub-pressing head 121 away from the connector 130; the area of ​​the contour surface of the boss 122 is smaller than the area of ​​the contour surface of the press head 120.

[0063] Specifically, by providing the sub-pressing head 121, the number of the sub-pressing heads 121 can be selected according to actual needs during the installation process, thereby changing the length of the pressing head 120. The boss 122 is provided on the sub-pressing head 121 to change the contact area between the sub-pressing head 121 and the tab, thereby increasing the pressure, so that the pressing head 120 can compact the tab, thereby avoiding the phenomenon of cold welding and breakdown of the tab, and ensuring the product quality of the battery module.

[0064] In this embodiment, please refer to Figure 7 and Figure 8 , one sub-pressing head 121 is connected to two connecting members 130, and each connecting member 130 is sleeved with a plurality of springs, thereby increasing the buffering force acting on the pressing head 120. In other embodiments, the number of connecting members 130 and the number of springs sleeved on the connecting members 130 can be selected according to actual conditions.

[0065] For further information, please refer to Figure 2 and Fig.11 , Fig.11 The structural diagram of the baffle 150 provided in the embodiment of the utility model is as follows: The connecting plate 110 is provided with a first through slot 114 , and the baffle 150 is provided with a second through slot 151 , and the first through slot 114 and the second barrel slot are both directly opposite to the interval between the two pressure heads 120 .

[0066] Therefore, during the welding process, the welding machine can pass through the first through slot 114, the second through slot 151 and the gap between the two pressing heads 120 to weld the tab, so that the positioning of the welding point is more accurate.

[0067] It should be noted that, in this embodiment, the width of the first through groove 114 and the second through groove 151 is smaller than the distance between the two pressing heads 120, so as to avoid the laser hitting the pressing head 120 or the welding point deviation and inaccurate positioning when using laser welding.

[0068] In summary, the pressure head assembly 100 in this embodiment applies a certain pressure to the pressure head 120 by setting the return member 140, and cooperates with the connecting member 130 and the mounting hole 111, wherein the diameter of the first segment 112 is greater than the diameter of the second segment 113 and makes the head 131 of the connecting member 130 abut against the second segment 113, thereby limiting the moving distance of the connecting member 130 in the axial direction of the mounting hole 111, thereby compacting the pole ear and preventing the pole ear from deforming during the welding process, which causes the fit of the two overlapping pole ears to deteriorate, thereby avoiding the phenomenon of cold welding and breakdown of the pole ear, and ensuring the product quality of the battery module. In this embodiment, the connecting member 130 is a screw, and the restoring member 140 is a spring, and the baffle 150 is also provided in this embodiment to limit the movement of the connecting member 130 in the direction away from the pressure head 120, thereby connecting the maximum moving distance of the connecting member 130 in the axial direction of the mounting hole 111, and also avoiding the plastic deformation and loss of elasticity of the spring caused by excessive extrusion of the spring by the connecting plate 110 and the pressure head 120. In this embodiment, the sleeve 160 is provided to guide the spring to shorten or elongate in the axial direction of the mounting hole 111 while protecting the spring; and the length of the sleeve 160 is less than the length of the spring in the unstressed state, thereby avoiding obstruction of the movement of the connecting member 130. In this embodiment, the sub-pressure head 121 and the boss 122 are provided to change the length of the pressure head 120 and the pressure when squeezing the pole ear. In this embodiment, two pressure heads 120 are provided to avoid the phenomenon that the pole ear is lifted at both ends during the squeezing process by the pressure head 120, thereby avoiding the phenomenon of cold welding and breakdown of the pole ear. In this embodiment, the first through slot 114 and the second through slot 151 are arranged to be aligned with the gap between the two pressing heads 120 , so that the welding point of the tab can be accurately positioned during the welding process.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pressure head assembly, characterized in that: The pressure head assembly includes a connecting plate, a pressure head, a connecting piece and a return piece; The connecting plate is provided with a mounting hole, the mounting hole includes a first segment and a second segment, and the diameter of the first segment is greater than the diameter of the second segment; The rod body of the connecting member is connected to the pressure head; the head of the connecting member is movably matched with the first segment along the axial direction of the mounting hole; the rod body of the connecting member is movably matched with the second segment along the axial direction of the mounting hole; The return member is sleeved on the connecting member, and two ends of the return member are respectively abutted against the pressure head and the connecting plate, so that the connecting member has a tendency to move from the first segment toward the second segment.

2. The pressure head assembly according to claim 1, characterized in that: The pressure head assembly further includes a baffle, which is connected to the connecting plate and is located on a side of the connecting plate away from the pressure head; One end of the first segment facing away from the second segment is open; the baffle is used to abut against the head to limit the movement of the head from the second segment toward the first segment.

3. The pressure head assembly according to claim 1, characterized in that: A limiting platform is arranged in the first segment, and the limiting platform is spaced apart from the interface between the first segment and the second segment to limit the movement of the head from the second segment toward the first segment.

4. The pressure head assembly according to any one of claims 1 to 3, characterized in that: There are two pressure heads, and the two pressure heads are spaced apart.

5. The pressure head assembly according to claim 4, characterized in that: The pressure head assembly includes a plurality of connecting members, the connecting plate is provided with a plurality of mounting holes, and each mounting hole is matched with a corresponding connecting member; The pressure head includes a plurality of sub-pressure heads, which are arranged in sequence, and each of the sub-pressure heads is connected to one or more of the connecting members.

6. The pressure head assembly according to claim 5, characterized in that: The sub-pressing head is provided with a boss, and the boss is located on a side of the sub-pressing head away from the connecting member; the area of ​​the contour surface of the boss is smaller than the area of ​​the contour surface of the pressing head.

7. The pressure head assembly according to claim 6, characterized in that: The connecting plate is provided with a first through slot, and the first through slot is directly opposite to the spacing area between the two pressure heads.

8. The pressure head assembly according to any one of claims 1 to 3, characterized in that : The pressure head assembly also includes a sleeve, which is sleeved on the return member; wherein the length of the sleeve is smaller than the length of the return member in a state without force.

9. The pressure head assembly according to any one of claims 1 to 3, characterized in that: The return member is a spring, and two ends of the spring are respectively against the connecting plate and the pressure head.

10. A tab welding device, characterized in that: The tab welding device comprises a driving member and a pressure head assembly as described in any one of claims 1 to 9, and the movable end of the driving member is connected to the connecting plate.

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