ULTRASONIC WELDING HEAD AND WELDING DEVICE

Provided are an ultrasonic welding head and a welding device. The ultrasonic welding head comprises a welding surface and a side surface. The welding surface is provided with a first welding tooth. The first welding tooth is configured to weld members to be welded. The side surface has an extension direction which intersects an extension direction of the welding surface. The ultrasonic welding head further comprises a connection surface. The connection surface is connected to the welding surface and the side surface, so as to form an avoidance space to avoid the members to be welded.

TECHNICAL FIELD

The present application relates to the technical field of welding, and in particular, to an ultrasonic welding head and a welding device.

BACKGROUND ART

Ultrasonic welding is to transmit high-frequency vibration waves to surfaces of two objects to be welded such that the surfaces of the two objects rub against each other under pressure to form fusion between molecular layers. The ultrasonic welding is an efficient connection method for connecting several members to be welded to each other.

As an example, in which the members to be welded are tabs and an adapter of the battery, the tabs and the adapter of the battery are generally connected to each other in the form of a lap-joint structure, and the tabs are in a stacked structure. During welding, the ultrasonic welding head is pressed against the stacked tabs, a certain amount of pressure is applied by means of the ultrasonic welding head, and an ultrasonic apparatus is used to output ultrasonic waves to achieve atomic resonance of adjacent tabs under high-frequency vibration, such that a plurality of layers of tabs are connected together and the tabs and the adapter are connected together.

Since the tabs of the battery are very thin, during the ultrasonic welding, the tabs often rub against and vibrate with the ultrasonic welding head, resulting in undesirable phenomena such as the first layer or multiple layers of tabs being shattered or cracked, thereby reducing the welding quality.

SUMMARY OF THE DISCLOSURE

In view of the above problems, the present application provides an ultrasonic welding head and a welding device, which can improve undesirable phenomena such as breakage or cracking of members to be welded during ultrasonic welding.

In a first aspect, the present application provides an ultrasonic welding head, comprising:a welding surface provided with a first welding tooth, the first welding tooth being configured to weld members to be welded; anda side surface having an extension direction which intersects an extension direction of the welding surface;wherein the ultrasonic welding head further comprises a connection surface which is connected to the welding surface and the side surface, so as to avoid the members to be welded.

In the technical solution of the embodiment of the present application, by providing the connection surface between the welding surface and the side surface, the contact area between the side surface of the ultrasonic welding head and the members to be welded is reduced, so that during ultrasonic welding, frictional forces in non-welding regions of the members to be welded are reduced, and the thinning effect due to friction during the high-frequency vibration of the ultrasonic welding head becomes smaller, thereby improving undesirable phenomena such as breakage or cracking of the members to be welded, and thus effectively improving the welding quality.

In some embodiments, the connection surface is in smooth transition connection with the welding surface.

In this way, during the ultrasonic welding, no tab will be cut when a transition region between the connection surface and the welding surface comes into contact with tabs, thereby reducing the magnitude of a frictional force between this region and the tabs, making the tabs in this region less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction.

In some embodiments, the connection surface comprises a circular arc surface and an avoidance surface, the circular arc surface is connected to the avoidance surface and the welding surface, and the circular arc surface is tangent to the welding surface.

In this way, the circular arc surface and the avoidance surface are subjected to small frictional forces when in contact with the tabs, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding. In addition, the ultrasonic welding head is also easy to manufacture and form.

In some embodiments, the circular arc surface has a radius ranging from 0.5 mm to 1.5 mm.

In this way, when the radius R of the circular arc surface is in the range of 0.5 mm to 1.5 mm, the contact area between the tabs and the circular arc surface is small during the ultrasonic welding, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, a second welding tooth is provided on the circular arc surface.

In this way, the second welding tooth can pre-press and shape the tabs in advance before the high-frequency vibration of the ultrasonic welding head. Since the tabs are in a stacked structure and are in a fluffy state in the surface region, the second welding tooth can compress the tabs in the fluffy state. Moreover, with the provision of the second welding tooth, it is also possible to change the friction between the tabs and the circular arc surface from the original large-plane friction to a small-plane friction, so that the overall friction area between the tabs and the ultrasonic welding head can be reduced, and the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, a projection of the avoidance surface on a first plane has a height ranging from 0.5 mm to 2 mm, the first plane being perpendicular to the welding surface; and/ora projection of the avoidance surface on a second plane has a width ranging from 0.5 mm to 1.5 mm, the second plane being parallel to the welding surface.

In this way, when the projection of the avoidance surface on the first plane has a height ranging from 0.5 mm to 2 mm, the contact area between the avoidance surface and the tabs is small in a direction in which the avoidance surface and the tabs are parallel to each other, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

When the projection of the avoidance surface on the second plane has a width ranging from 0.5 mm to 1.5 mm, the contact area between the avoidance surface and the tabs is small in a direction in which the avoidance surface and the tabs form an angle with each other, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, the surface form of the connection surface comprises at least one of an inclined surface and an arc-shaped surface, the inclined surface being inclined relative to the welding surface.

In this way, by arranging the inclined surface and the welding surface in an inclined state, it is possible that during the high-frequency vibration of the ultrasonic welding head, the contact area between the side surface of the ultrasonic welding head and the tabs becomes smaller, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, when the surface form of the connection surface comprises an inclined surface, an included angle between the inclined surface and the welding surface is greater than an included angle between the welding surface and the side surface.

In this way, compared to when the included angle between the inclined surface and the welding surface is less than or equal to the included angle between the welding surface and the side surface, the included angle between the inclined surface and the welding surface is set to be greater than the included angle between the welding surface and the side surface to make the contact area between an avoidance space and the ultrasonic welding head is smaller, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, the included angle between the inclined surface and the welding surface is an obtuse angle, and the side surface is perpendicular to the welding surface.

In this way, when the included angle between the inclined surface and the welding surface is an obtuse angle, if the side surface is not perpendicular to the welding surface, it will cause the side surface to cut the tabs, so that the tabs are subjected to undesirable phenomena such as breakage or cracking due to friction with the side surface.

In some embodiments, a second welding tooth is arranged at a connection between the connection surface and the welding surface.

In this way, the second welding tooth can pre-press and shape the tabs in advance before the high-frequency vibration of the ultrasonic welding head. Since the tabs are in a stacked structure and are in a fluffy state in the surface region, the second welding tooth can compress the tabs in the fluffy state. Moreover, with the provision of the second welding tooth, it is also possible to change the friction between the tabs and a connection region between the connection surface and the welding surface from the original large-plane friction to a small-plane friction, so that the overall friction area between the tabs and the ultrasonic welding head can be reduced, and the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, the second welding tooth is arranged at a connection line between the connection surface and the welding surface.

In this way, by arranging the second welding tooth at the connection line between the connection surface and the welding surface, the second welding tooth can fully pre-press and shape the tabs before the ultrasonic welding. When the ultrasonic welding head approaches a pressure-side tab, compared with other positions, the second welding tooth at the connection line may first come into contact with the pressure-side tab, so that the tab can be pre-pressed and shaped faster.

In some embodiments, the first welding tooth has a height greater than that of the second welding tooth.

In this way, the height of the first welding tooth being greater than that of the second welding tooth can prevent the second welding tooth from affecting the contact between the first welding tooth and the tabs, thereby avoiding false welding.

In some embodiments, there are a plurality of first welding teeth and a plurality of second welding teeth, the plurality of first welding teeth are arranged at intervals in a matrix, and at least one of the second welding teeth is located at an extension of a gap between two adjacent first welding teeth.

In this way, the plurality of second welding teeth can pre-press and shape the contact region between the ultrasonic welding head and the tabs in advance to ensure the flatness of the surfaces of the tabs, the plurality of first welding teeth can improve the welding efficiency of the ultrasonic welding head to the tabs, and the positioning of a second welding tooth between two adjacent first welding teeth can optimize the space occupation of the ultrasonic welding head, thereby reducing the overall size of the ultrasonic welding head and reducing the production and manufacturing costs of the ultrasonic welding head.

In some embodiments, the second welding tooth has a spherical shape. When the second welding tooth is spherical, the second welding tooth can change the friction between the tabs and the connection surface from the original large-plane friction to spherical friction. Compared with a non-spherical second welding tooth, this can reduce the overall friction area between the tabs and the ultrasonic welding head, and can also weaken the cutting effect between the ultrasonic welding head and the tabs, so that the tabs are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

In some embodiments, the first welding tooth comprises a first tooth and a second tooth arranged spaced apart from the first tooth, the second tooth is arranged closer to the connection surface than the first tooth, and a contact area between the second tooth and the members to be welded is greater than a contact area between the first tooth and the members to be welded.

In this way, the second tooth is arranged closer to the connection surface and the contact area between the second tooth and the members to be welded is greater than the contact area between the first tooth and the members to be welded, so that the tab in contact with the second tooth can be stretched, in other words the length of the tab participating in the ultrasonic vibration increases. It can be understood that since the area increases and the pressing forces from the first tooth and the second tooth are constant, the pressure on the tab in contact with the second tooth becomes smaller, thereby reducing the friction tearing force from the ultrasonic welding head on the tab during the welding, and thus alleviating the undesirable phenomena such as breakage or cracking of the tab due to friction during the ultrasonic welding.

In some embodiments, the first tooth comprises a first connection surface connected to the welding surface, the second tooth comprises a second connection surface connected to the welding surface, the first welding tooth comprises a first tooth and a second tooth arranged spaced apart from the first tooth, the second tooth is arranged closer to the connection surface than the first tooth, and the second connection surface has an area greater than that of the first connection surface area.

In this way, the welding area of the second tooth is large, the contact between the second tooth and the pressure-side tab is more stable, and the stress in the contact region between the tab and the second tooth is reduced.

In some embodiments, the second tooth comprises a space-keeping surface which is oriented in the same direction as the connection surface.

In this way, compared with the first tooth without a space-keeping surface, during the welding, the contact area between the second tooth and the members to be welded is larger, so that the tab in contact with the second tooth can be stretched, in other words the length of the tab participating in the ultrasonic vibration increases. It can be understood that since the area increases and the pressing forces from the first tooth and the second tooth are constant, the pressure on the tab in contact with the second tooth becomes smaller. In addition, the space-keeping surface can reduce the contact area between the second tooth and the non-welding region of the tab, thereby reducing the friction tearing force from the ultrasonic welding head on the tab during the welding, and thus alleviating the undesirable phenomena such as breakage or cracking of the tab due to friction during the ultrasonic welding.

In some embodiments, an extension direction of an intersection line between the welding surface and the connection surface is a first direction, a second direction is perpendicular to the first direction, and the centers of the first tooth and the second tooth are aligned with each other in the second direction.

In this way, during the ultrasonic welding, the welded parts of the tabs are vibrated uniformly and are less likely to be subjected to undesirable phenomena such as breakage or cracking.

In some embodiments, in the second direction, the first tooth has a dimension less than that of the second tooth; and in the first direction, the first tooth has a dimension equal to that of the second tooth.

In this way, the dimension of the second tooth in the second direction is greater than that of the first tooth, making it easier to perform further machining on the second tooth, so as to create a space-keeping structure on the second tooth. The dimension of the second tooth in the first direction is equal to that of the first tooth, so that the space of the welding surface is effectively utilized.

In a second aspect, the present application provides a welding device, comprising an ultrasonic welding head in the foregoing embodiments.

The above description is only an overview of the technical solutions of the present application. In order to more clearly understand the technical means of the present application to implement same according to the contents of the description, and in order to make the above and other objectives, features and advantages of the present application more obvious and understandable, specific implementations of the present application are exemplarily described below.

REFERENCE SIGNS IN DETAILED DESCRIPTION OF EMBODIMENTS

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are merely intended to more clearly illustrate the technical solutions of the present application, so they merely serve as examples, but are not intended to limit the scope of protection of the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs. The terms used herein are merely for the purpose of describing specific embodiments, but are not intended to limit the present application. The terms “comprising” and “having” and any variations thereof in the description and the claims of the present application as well as the brief description of the accompanying drawings described above are intended to cover non-exclusive inclusion.

In the description of the embodiments of the present application, the technical terms “first”, “second”, etc. are merely used for distinguishing different objects, and are not to be construed as indicating or implying relative importance or implicitly indicating the number, particular order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the phrase “a plurality of” means two or more, unless otherwise explicitly and specifically defined.

The phrase “embodiment” mentioned herein means that the specific features, structures, or characteristics described in conjunction with the embodiment can be encompassed in at least one embodiment of the present application. The phrase at various locations in the description does not necessarily refer to the same embodiment, or an independent or alternative embodiment exclusive of another embodiment. Those skilled in the art understand explicitly or implicitly that the embodiment described herein may be combined with another embodiment.

In the description of the embodiments of the present application, the term “and/or” is merely intended to describe the associated relationship of associated objects, indicating that three relationships can exist, for example, A and/or B can include: only A exists, both A and B exist, and only B exists. In addition, the character “/” herein generally indicates an “or” relationship between the associated objects.

In the description of the embodiments of the present application, the term “a plurality of” means two or more (including two), similarly the term “a plurality of groups” means two or more groups (including two groups), and the term “a plurality of pieces” means two or more pieces (including two pieces).

In the description of the embodiments of the present application, the orientation or position relationship indicated by the technical terms “central”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”; “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc. are based on the orientation or position relationship shown in the accompanying drawings and are merely intended to facilitate and simplify the description of the embodiments of the present application, rather than indicating or implying that the apparatus or element considered must have a particular orientation or be constructed and operated in a particular orientation, and therefore not to be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless otherwise explicitly specified and defined, the technical terms such as “mount”, “couple”, “connect”, and “fix” should be understood in a broad sense, for example, they may be a fixed connection, a detachable connection, or an integrated connection; may be a mechanical connection or an electric connection; and may be a direct connection or an indirect connection by means of an intermediate medium, or may be internal communication between two elements or interaction between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific situations.

At present, from the perspective of the development of the market situation, batteries are used more and more widely. The batteries are not only used in energy storage power systems such as hydroelectric power plants, thermal power plants, wind power plants and solar power plants, but also widely used in electric transportation means such as electric bicycles, electric motorcycles and electric vehicles and in many fields such as military equipment and aerospace. With the continuous expansion of the application field of batteries, the market demand for the batteries is also expanding.

The inventors have noticed that during welding of members to be welded of a battery, especially during connection between tabs and an adapter in the battery, ultrasonic welding technology is generally used. Ultrasonic welding is to transmit high-frequency vibration waves to surfaces of two objects to be welded such that the surfaces of the two objects rub against each other under pressure to form fusion between molecular layers, and thus has high efficiency, high quality, attractive appearance, energy saving, high welding strength and other advantages. The ultrasonic welding is an efficient connection method for connecting the tabs and the adapter to each other. In the battery, the tabs are generally in a structure in which a plurality of tabs are stacked together, and the connection between the tabs and the adapter generally adopts a lap-joint structure. During welding, the ultrasonic welding head is pressed against the stacked tabs, a certain amount of pressure is applied by means of the ultrasonic welding head, and an ultrasonic apparatus then outputs ultrasonic waves to achieve atomic resonance of adjacent tabs under high-frequency vibration, such that the tabs and the adapter are connected together.

However, the tabs of the battery are very thin, generally only 5-20 μm for a single layer of tab. During the welding of the tabs and the adapter, the tabs extend from an electrode assembly. It can be understood that the height of the tab near a main body portion of the electrode assembly will be higher than the tab on the side pressed by the ultrasonic welding head, and there will be a certain angle between the two parts. In this solution, for ease of illustration, the tab on the side close to the main body portion of the electrode assembly is called a cell-side tab, the tab pressed by the ultrasonic welding head is called a pressure-side tab, and a tab in the region between the cell-side tab and the pressure-side tab is called a corner tab. The corner tab is located at an edge of the ultrasonic welding head.

The ultrasonic welding head is divided into a welding region and a non-welding region, the welding region is parallel to the pressure-side tab, and the non-welding region has a certain angle to the pressure-side tab. When welding, it is necessary to press the ultrasonic welding head against the stacked tabs, that is, the welding region is in direct contact with the pressure-side tab, and in a region of the ultrasonic welding head that is close to a battery cell, there is a certain angle between the pressure-side tab and the non-welding region of the ultrasonic welding head. Further, the cell-side tab and the corner tab may be in direct contact with the non-welding region. Since during the ultrasonic welding, the ultrasonic welding head is constantly vibrated and displaced at high frequencies, the corner tab and the cell-side tab constantly rub against the non-welding region of the ultrasonic welding head during the ultrasonic welding, resulting in phenomena such as the first layer or multiple layers of tabs being shattered or cracked, so that metal debris may be generated in the battery region, affecting the quality of the battery.

In order to solve the problem of the tab being shattered or cracked during the ultrasonic welding, the inventors have found that the ultrasonic welding head in the welding device can be improved in design. Specifically, in order to improve the structure of the ultrasonic welding head, an avoidance space is designed in the ultrasonic welding head.

Further, the avoidance space is designed between the welding region and the non-welding region of the ultrasonic welding head to reduce the contact area between the corner tab and the cell-side tab and the non-welding region of the ultrasonic welding head.

In such a welding device, due to the avoidance space designed in the ultrasonic welding head, during the ultrasonic welding, the contact area between the non-welding region of the ultrasonic welding head and the corner tab and the cell-side tab is reduced, so that the degree of friction between the ultrasonic welding head and the corner tab and cell- side tab is reduced, and the corner tab and cell-side tab are thus less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

The ultrasonic welding head disclosed in the embodiments of the present application may be used in a welding device using the ultrasonic welding technology. The welding device may be, but is not limited to, an ultrasonic plastic welding machine, an ultrasonic metal welding machine, etc.

For ease of description of the embodiments below, an example in which a welding device1000according to an embodiment of the present application is an ultrasonic metal welding machine is used for description.

Referring toFIG.1,FIG.1is a schematic structural diagram of a welding device1000according to some embodiments of the present application. The ultrasonic metal welding machine may comprise an ultrasonic welding head100and other functional components. The specific model of the ultrasonic metal welding machine is not limited in the embodiments of the present application, as long as it can meet the requirements for mounting the ultrasonic welding head100according to the embodiments of the present application.

Referring further toFIG.2,FIG.2is a schematic diagram of ultrasonic welding according to some embodiments of the present application. First of all, it should be noted that when describing the embodiments of the present application, members to be welded201are designated as tabs210and an adapter300, but this is only an example for convenience of understanding and cannot be understood as a limitation of the present application. It can be understood that the members to be welded201may be any objects that are processed and manufactured using the ultrasonic welding head100according to some embodiments of the present application. An electrode assembly is an assembly of the battery, and the type of the electrode assembly is not limited in the embodiments of the present application. The electrode assembly comprises a main body portion200and tabs210. The tabs210are connected to the main body portion200. The tabs210may be aluminum tabs, nickel tabs, copper-plated nickel tabs, etc. The material type of the tabs210is not limited in the embodiments of the present application. During ultrasonic welding, the tabs210are generally in a stacked state, that is, a plurality of tabs210are stacked together. Referring further toFIG.3,FIG.3is an enlarged view of part A of the schematic diagram of ultrasonic welding inFIG.2. In this solution, the tabs210may comprise a pressure-side tab211, a corner tab215and a cell-side tab213.

During the ultrasonic welding, the tabs210are placed on the adapter300, and the ultrasonic welding head100is pressed against the tabs210. Further, the ultrasonic welding head100is pressed against the pressure-side tab211. Through the high-frequency vibration and displacement of the ultrasonic welding head100, the tabs210and the adapter300are welded together.

According to some embodiments of the present application, optionally, referring further toFIGS.2to9,FIG.4is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application,FIG.5is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application,FIG.6is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application,FIG.7is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application,FIG.8is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application, andFIG.9is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application. The embodiments of the present application provide an ultrasonic welding head100. The ultrasonic welding head100comprises a welding surface10and a side surface20. The welding surface10is provided with a first welding tooth50. The first welding tooth50is configured to weld members to be welded201. The side surface20has an extension direction which intersects an extension direction of the welding surface10. The ultrasonic welding head100further comprises a connection surface30. The connection surface30is connected to the welding surface10and the side surface20, so as to avoid the members to be welded201.

Specifically, the ultrasonic welding head100is a welding head using the ultrasonic welding technology. In order to adapt to the alternating load generated by high- frequency vibration during the ultrasonic welding, the ultrasonic welding head100should be made of a material with a high fatigue strength, such as an aluminum alloy and a titanium alloy, which will not be limited in the embodiments of the present application. The ultrasonic welding head100may be a cylinder, a cuboid, a truncated cone, etc., which will not be limited in the embodiments of the present application.

The welding surface10is a welding region of the ultrasonic welding head100. During the ultrasonic welding, the welding surface10is parallel to the pressure-side tab211. Further, the welding surface10is in direct contact with the pressure-side tab211and is pressed against the pressure-side tab211. The welding surface10may be a rectangular surface, a square surface, a circular surface, etc., and the specific shape of the welding surface10is not limited in the embodiments of the present application. A first extension plane11is a plane extending from the welding surface10toward the cell-side tab213in a length direction of the ultrasonic welding head100.

The side surface20is a non-welding region of the ultrasonic welding head100. During the ultrasonic welding, the side surface20has an angle to the pressure-side tab211. The side surface20may be a rectangular surface, a square surface, a circular surface, etc., and the specific shape of the welding surface10is not limited in the embodiments of the present application. A second extension plane21is a plane extending from the side surface20toward the pressure-side tab211in a height direction of the ultrasonic welding head100.

The first welding tooth50may be a working welding tooth of the ultrasonic welding head100, or the first welding tooth50may be a structure on the ultrasonic welding head100that is in direct contact with and pressed against the pressure-side tab211during the ultrasonic welding.

As shown inFIGS.5to9, the first welding tooth50may be a pyramid, a sphere, a mixture of the two, etc. The specific shape of the first welding tooth50is not limited in the embodiments of the present application. Optionally, the first welding tooth50is a pyramid. The first welding tooth50may penetrate through the pressure-side tab211. Further, the first welding tooth50may penetrate through the first layer or multiple surface layers of pressure-side tabs210.

By “the side surface20has an extension direction which intersects an extension direction of the welding surface10”, it is meant that the side surface20and the welding surface10have a certain spatial angle. For example, the spatial angle between the side surface20and the welding surface10is 90 degrees. In this case, the side surface20and the welding surface10are perpendicular to each other.

Taking the ultrasonic welding head100defined as a cuboid as an example, the ultrasonic welding head100may comprise a top surface and peripheral surfaces connected to the top surface. The top surface corresponds to the welding surface10. Since the tabs210are in a stacked state, the corner tab215and the cell-side tab213would be partially warped upward. Specifically, the corner tab215and the cell-side tab213move closer to the peripheral surfaces, and the corner tab215and the cell-side tab213constantly rub against the peripheral surfaces during the continuous high-frequency vibration and displacement of the ultrasonic welding head100, thereby causing the breakage or cracking of the tabs210. Here, the side surface20can be understood as any one of the peripheral surfaces, or all the peripheral surfaces.

The connection surface30is a surface between the welding surface10and the side surface20. The connection surface30can be regarded as a transition surface or a chamfer surface between the welding surface10and the side surface20. The connection surface30may be a linear surface or a curved surface.

The welding surface10, the side surface20and the connection surface30may jointly define an avoidance space400. The avoidance space400may be a space surrounded by the connection surface30, the first extension plane11and the second extension plane21, and the avoidance space400is not a closed space. Taking the ultrasonic welding head100defined as a cuboid as an example, along a straight line, which is defined as being parallel to a diagonal line of the cuboid and close to one of the vertices of the cuboid, from the top surface of the cuboid along a linear or curved path to an edge which is close to this vertex and extends from the top surface to the bottom surface, a part of the cuboid that is close to this vertex is removed, and the virtual space left by the removed part is the avoidance space400.

In the technical solution of the embodiment of the present application, by providing the connection surface30between the welding surface10and the side surface20, the contact area between the side surface20of the ultrasonic welding head100and the members to be welded201is reduced, so that during ultrasonic welding, the contact areas of non-welding regions of the members to be welded201are reduced, thereby improving undesirable phenomena such as breakage or cracking of the tabs210, and thus effectively improving the welding quality.

According to some embodiments of the present application, optionally, referring further toFIGS.2and4, the connection surface30is in smooth transition connection with the welding surface10.

Specifically, “smooth transition connection” refers to a circular arc transitional connection between the connection surface30and the welding surface10, that is, in terms of technology, a rounding process is performed between the connection surface30and the welding surface10.

Of course, there may also be other curved transition forms between the connection surface30and the welding surface10, which will not be specifically limited in the embodiments of the present application, as long as there is no local height difference at the transition between the connection surface30and the welding surface10.

In this way, during the ultrasonic welding, no tab210will be cut when a transition region between the connection surface30and the welding surface10comes into contact with the tabs210, thereby reducing the magnitude of a frictional force between this region and the tabs210, making the tabs210in this region less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction.

According to some embodiments of the present application, optionally, referring further toFIGS.2to4, the connection surface30comprises a circular arc surface31and an avoidance surface33. The circular arc surface31is connected to the avoidance surface33and the welding surface10, and the circular arc surface31is tangent to the welding surface10.

Specifically, taking the ultrasonic welding head100defined as a cuboid as an example, the top surface corresponds to the welding surface10. The avoidance surface33may be a transition surface between the corresponding peripheral surface close to the cell-side tab213and the top surface, and the circular arc surface31may be a transition surface between the peripheral surface close to the cell-side tab213and the top surface. Here, the side surface20can be understood as any one of the peripheral surfaces, or all the peripheral surfaces.

By “tangential connection” means that the angle between an end of the circular arc surface31that is away from the avoidance surface33and the welding surface10is 180 degrees.

In this way, the circular arc surface31and the avoidance surface33are subjected to small frictional forces when in contact with the tabs210, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding. In addition, the ultrasonic welding head100is also easy to manufacture and form.

According to some embodiments of the present application, optionally, referring further toFIGS.2,3,4and10,FIG.10is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application. The circular arc surface31has a radius R ranging from 0.5 mm to 1.5 mm.

Specifically, the radius R of the circular arc surface31may be 0.5 mm, 0.6 mm, 1.2 mm, 1.5 mm, etc., which will not be limited in the embodiments of the present application. When the radius R of the circular arc surface31is less than 0.5 mm, the cell-side tab213and the corner tab215still have a large contact area with the circular arc surface31, thereby greatly reducing the improvement effect on the breakage and cracking of the tabs210. When the radius R of the circular arc surface31is greater than 1.5 mm, the outer dimensions of the ultrasonic welding head100will be too large, so that the manufacturing cost of the ultrasonic welding head100is increased and the improvement effect is not significant.

In this way, when the radius R of the circular arc surface31is in the range of 0.5 mm to 1.5 mm, the contact area between the tabs210and the circular arc surface31is small during the ultrasonic welding, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.4and9to13,FIG.11is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application,FIG.12is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application, andFIG.13is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application. A second welding tooth40is provided on the circular arc surface31.

Specifically, as shown inFIGS.9to13, the second welding tooth40may be a pyramid, a sphere, a mixture of the two, etc. The specific shape of the second welding tooth40is not limited in the embodiments of the present application. Optionally, the second welding tooth40is a sphere. There may be a plurality of second welding teeth40, and the plurality of second welding teeth40are arranged at intervals on the circular arc surface31. Taking the second welding tooth40defined as a pyramid as an example, a height direction of the second welding tooth40may be arranged perpendicular to a normal direction of the circular arc surface31.

In this way, the second welding tooth40can pre-press and shape the tabs210in advance before the high-frequency vibration of the ultrasonic welding head100. Since the tabs210are in a stacked structure and are in a fluffy state in the surface region, the second welding tooth40can compress the tabs210in the fluffy state. Moreover, with the provision of the second welding tooth40, it is also possible to change the friction between the tabs210and the circular arc surface31from the original large-plane friction to a small-plane friction, so that the overall friction area between the tabs210and the ultrasonic welding head100can be reduced, and the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2,3,4and10, a projection of the avoidance surface33on a first plane500has a height H4ranging from 0.5 mm to 2 mm. The first plane500is perpendicular to the welding surface10. A projection of the avoidance surface33on a second plane600has a width D6ranging from 0.5 mm to 1.5 mm. The second plane600is parallel to the welding surface10.

Specifically, taking the ultrasonic welding head100defined as a cuboid as an example, the welding surface10corresponds to the top surface. The first plane500may be a plane parallel to the peripheral surface of the short side, that is, perpendicular to the top surface. The height of the projection of the avoidance surface33refers to the dimension of the orthographic projection of the avoidance surface33relative to the first plane500. The height H4of the projection of the avoidance surface33may be 0.5 mm, 0.8 mm, 1.5 mm, 2 mm, etc., which will not be limited in the embodiments of the present application. When the height H4of the projection is less than 0.5 mm, the cell-side tab213and the corner tab215still have a large contact area with the avoidance surface33, thereby greatly reducing the improvement effect on the breakage and cracking of the tabs210. When the height H4of the projection is greater than 2 mm, the outer dimensions of the ultrasonic welding head100will be too large, so that the manufacturing cost of the ultrasonic welding head100is increased and the improvement effect is not significant. Here, the side surface20can be understood as any one of the peripheral surfaces, or all the peripheral surfaces.

Similarly, the second plane600may be a plane parallel to the top surface, and the width D6of the projection of the avoidance surface33refers to the dimension of the orthographic projection of the avoidance surface33relative to the second plane600.

Specifically, the width D6of the projection of the avoidance surface33may be 0.5 mm, 0.8 mm, 1.5 mm, etc., which will not be limited in the embodiments of the present application. When the width D6of the projection is less than 0.5 mm, the cell-side tab213and the corner tab215still have a large contact area with the avoidance surface33, thereby greatly reducing the improvement effect on the breakage and cracking of the tabs210. When the width D6of the projection is greater than 2 mm, the outer dimensions of the ultrasonic welding head100will be too large, so that the manufacturing cost of the ultrasonic welding head100is increased and the improvement effect is not significant.

In this way, when the projection of the avoidance surface33on the first plane500has a height H4ranging from 0.5 mm to 2 mm, the contact area between the avoidance surface33and the tabs210is small in a direction in which the avoidance surface and the tabs are parallel to each other, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding. When the projection of the avoidance surface33on the second plane600has a width D6ranging from 0.5 mm to 1.5 mm, the contact area between the avoidance surface33and the tabs210is small in a direction in which the avoidance surface and the tabs form an angle with each other, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2,4and11to13, the surface form of the connection surface30comprises at least one of an inclined surface35and an arc-shaped surface37. When the surface form of the connection surface30comprises an inclined surface35, the inclined surface35is inclined relative to the welding surface10.

Specifically, as shown inFIG.5, the avoidance surface33may be an inclined surface35, and as shown inFIGS.6and7, the avoidance surface33may alternatively be an arc-shaped surface37. Of course, the avoidance surface33may also be a combination of an inclined surface35and an arc-shaped surface37. For example, the avoidance surface33at the end close to the circular arc surface31may be an inclined surface35, and the avoidance surface33at the end away from the circular arc surface31and close to the side surface20may be an arc-shaped surface37.

By “the inclined surface35is inclined relative to the welding surface10”, it is meant that there is a certain angle between the inclined surface35and the welding surface10, and the angle is not a right angle.

In this way, by arranging the inclined surface35and the welding surface10in an inclined state, it is possible that during the high-frequency vibration of the ultrasonic welding head100, the contact area between the ultrasonic welding head100and the tabs210becomes smaller, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

It can be understood that in some embodiments, the avoidance surface33may also be arc-shaped as a whole.

According to some embodiments of the present application, optionally, referring further toFIGS.2,4and14,FIG.14is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application. When the surface form of the connection surface30comprises an inclined surface35, an included angle a between the inclined surface35and the welding surface10is greater than an included angle b between the welding surface10and the side surface20.

Specifically, the included angle a between the inclined surface35and the welding surface10is an angle between a plane of the extension direction of the inclined surface35toward the welding surface10and a plane of the extension direction of the welding surface10toward the inclined surface35. Similarly, the included angle b between the welding surface10and the side surface20may be an angle between a plane of the extension direction of the welding surface10toward the side surface20and a plane of the extension direction of the side surface20toward the welding surface10. It is worth noting that the angle is selected as an angle less than 180 degrees among the included angles between the planes.

In this way, compared to when the included angle a between the inclined surface35and the welding surface10is less than or equal to the included angle b between the welding surface10and the side surface20, the included angle a between the inclined surface35and the welding surface10is set to be greater than the included angle b between the welding surface10and the side surface20to make the contact area between an avoidance space400and the ultrasonic welding head100is smaller, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.4and14, the included angle a between the inclined surface35and the welding surface10is an obtuse angle, and the side surface20is perpendicular to the welding surface10.

Specifically, when the included angle a between the inclined surface35and the welding surface10is an obtuse angle, the included angle b between the welding surface10and the side surface20is a right angle.

In this way, when the included angle a between the inclined surface35and the welding surface10is an obtuse angle, if the side surface20is not perpendicular to the welding surface10, it will cause the side surface20to cut the tabs, so that the tabs are subjected to undesirable phenomena such as breakage or cracking due to friction with the side surface20.

According to some embodiments of the present application, optionally, referring further toFIGS.2to10and15,FIG.15is a schematic structural diagram of an ultrasonic welding head100according to some embodiments of the present application. A second welding tooth40is arranged at a connection between the connection surface30and the welding surface10.

Specifically, the “connection” refers to a region where the intersection between the connection surface30and the welding surface10is located. Optionally, the second welding tooth40may be distributed in a region of the connection surface30that is close to the welding surface10, and its height may be in the normal direction of the circular arc surface31or the avoidance surface33. The second welding tooth40may also be located in a region of the welding surface10that is close to the connection surface30, and its height may be in the normal direction of the welding surface10. Further, the second welding tooth40is close to the corner tab215and the cell-side tab213.

There may be a plurality of second welding teeth40, and the plurality of second welding teeth40are arranged at intervals at the connection between the connection surface30and the welding surface10. The intervals between the second welding teeth40may be equal. For example, the interval between adjacent second welding teeth40is fixed at 2 mm. The intervals between the second welding teeth40may also be non-equal. Taking the ultrasonic welding head100defined as a cuboid as an example, the top surface corresponds to the welding surface10. In a length direction of the top surface, a distance between two adjacent second welding teeth40may be D1and D2, where D1is the distance between two adjacent second welding teeth40that are not at the vertices in the length direction of the top surface, and D2is the distance between a second welding tooth40that is at a vertex in the length direction of the top surface and a second welding tooth40at the adjacent long side. Optionally, D2=1.5D1.

In this way, the second welding tooth40can pre-press and shape the tabs210in advance before the high-frequency vibration of the ultrasonic welding head100. Since the tabs210are in a stacked structure and are in a fluffy state in the surface region, the second welding tooth40can compress the tabs210in the fluffy state. Moreover, with the provision of the second welding tooth40, it is also possible to change the friction between the tabs210and a connection region between the connection surface30and the welding surface10from the original large-plane friction to a small-plane friction, so that the overall friction area between the tabs210and the ultrasonic welding head100can be reduced, and the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2to9, the second welding tooth40is arranged at a connection line between the connection surface30and the welding surface10.

Specifically, the connection line between the connection surface30and the welding surface10may be a surface intersection line of the welding surface10and the connection surface30. Taking the second welding tooth40defined as a pyramid as an example, the bottom center of the pyramid may be located on the intersection line which may be perpendicular to a connection line between the bottom center and the top center of the pyramid. In this way, by arranging the second welding tooth40at the connection line between the connection surface30and the welding surface10, the second welding tooth40can fully pre-press and shape the tabs210before the ultrasonic welding. When the ultrasonic welding head100approaches the pressure-side tab211, compared with other positions, the second welding tooth40at the connection line may first come into contact with the pressure- side tab211, so that the tab210can be pre-pressed and shaped faster.

According to some embodiments of the present application, optionally, referring further toFIG.2andFIG.10, the height of the first welding tooth50is greater than the height H1of the second welding tooth40.

Specifically, by “the height of the first welding tooth50is greater than the height H1of the second welding tooth40” refers to the heights of the first welding tooth50and the second welding tooth40in the normal direction of the welding surface10. Optionally, in some embodiments, when the first welding tooth50has a plurality of heights, what is meant here is that the lowest height of the first welding tooth50is less than the height H1of the second welding tooth40. The height of the welding tooth specifically refers to the height of the welding tooth protruding from the welding surface10.

In this way, the height of the first welding tooth50being greater than that of the second welding tooth40can prevent the second welding tooth40from affecting the contact between the first welding tooth50and the tabs210, thereby avoiding false welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2and4to9, there are a plurality of first welding teeth50and a plurality of second welding teeth40, the plurality of first welding teeth50are arranged at intervals in a matrix, and at least one of the second welding teeth40is located at an extension of a gap between two adjacent first welding teeth50.

There may be a plurality of second welding teeth40. For example, the number of second welding teeth40is five, six, seven or more. The specific number of second welding teeth40will not limited in the embodiments of the present application. Similarly, there may be a plurality of first welding teeth50. For example, the number of first welding teeth50is five, six, seven or more. The specific number of first welding teeth50will not limited in the embodiments of the present application.

By “arranged at intervals in a matrix” means that the first welding teeth50are arranged in the form of a matrix array. The gap between two adjacent first welding teeth50extends in the direction of the second welding tooth40and passes through the second welding tooth40.

Taking the ultrasonic welding head100defined as a cuboid as an example, the top surface corresponds to the welding surface10, the first welding teeth50are arranged at intervals on the top surface and protrude from the top surface, and the interval between adjacent first welding teeth50in the width direction is D3, and the interval between adjacent first welding teeth50in the length direction is D4. Optionally, D4is greater than D3. Such a configuration facilitates the production and manufacturing, and more first welding teeth50can be arranged on the welding surface10, thereby improving the efficiency of ultrasonic welding.

In this way, the plurality of second welding teeth40can pre-press and shape the contact region between the ultrasonic welding head100and the tabs210in advance to ensure the flatness of the surfaces of the tabs210, the plurality of first welding teeth50can improve the welding efficiency of the ultrasonic welding head100to the tabs210, and the positioning of a second welding tooth40between two adjacent first welding teeth50can optimize the space occupation of the ultrasonic welding head100, thereby reducing the overall size of the ultrasonic welding head100and reducing the production and manufacturing costs of the ultrasonic welding head100.

According to some embodiments of the present application, optionally, referring further toFIGS.2and5, in some embodiments, the second welding tooth40has a spherical shape.

Specifically, the spherical shape may be the cross-sectional shape of the second welding tooth40, and the second welding tooth40may be a hemisphere, a sphere, a spheroid, etc. When the second welding tooth40is spherical, the second welding tooth40can change the friction between the tabs210and the connection surface30from the original large-plane friction to spherical friction. Compared with a non-spherical second welding tooth40, this can reduce the overall friction area between the tabs210and the ultrasonic welding head100, and can also weaken the cutting effect between the ultrasonic welding head100and the tabs210, so that the tabs210are less likely to be subjected to undesirable phenomena such as breakage or cracking due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2to5, the first welding tooth50comprises a first tooth51and a second tooth53arranged spaced apart from the first tooth51, the second tooth53is arranged closer to the connection surface30than the first tooth51, and a contact area between the second tooth53and the members to be welded201is greater than a contact area between the first tooth51and the members to be welded201.

Specifically, the first tooth51may be a welding tooth among the first welding teeth50that is not provided with a space-keeping structure, and the second tooth53may be a welding tooth among the first welding teeth50that is provided with a space-keeping structure. Taking the ultrasonic welding head100defined as a cuboid as an example, the top surface corresponds to the welding surface10. A distance D4between the first tooth51and the second tooth53adjacent to each other may be less than the distance D1between two adjacent second welding teeth40. In the width direction of the top surface, the distance between two adjacent second welding teeth40may be equal to D2.

By “the second tooth53is closer to the connection surface30than the first tooth51”, it is meant that a projection distance of the second tooth53on the connection surface30is less than that of the first tooth51. Taking the first tooth51defined as a pyramid as an example, on the basis of the first tooth51, material is removed along a certain path from the top surface of the pyramid toward the bottom surface. A pyramid-like body obtained after the material is removed is the second tooth53.

Taking the second tooth53defined as a pyramid as an example, the bottom surface of the pyramid is located on the welding surface10, and the top surface protrudes from the welding surface10. The cross-sectional area of the second tooth53may be the cross-sectional area of the side surface20of the pyramid. Optionally, the length L3of the bottom surface of the second tooth53is greater than the length L4of the top surface of the second tooth53. It can be understood that if L3=L4, the second tooth53cannot penetrate through the tabs210, thereby causing false welding. Similarly, taking the first tooth51defined as a pyramid as an example, the bottom surface of the pyramid is located on the welding surface10, and the top surface protrudes from the welding surface10. Optionally, the length L2of the top surface of the first tooth51is equal to the length L4of the top surface of the second tooth53, the width W2of the top surface of the first tooth51is equal to the width W4of the top surface of the second tooth53, the height H2of the first tooth51is equal to the height H3of the second tooth53, the heights H2and H3of the first welding tooth50are greater than the height H1of the second welding tooth40, and H1=0.4H2=0.4H3.

It can be understood that in a direction perpendicular to the welding surface10, the cross-sectional area of the second tooth53gradually decreases, making the transition of the second tooth53in this direction smoother, thereby reducing the friction tearing force from the second tooth53on the tab210during the welding, and thus alleviating the undesirable phenomena such as breakage or cracking of the tab210due to friction during the ultrasonic welding.

In this way, the second tooth53is arranged closer to the connection surface30and the contact area between the second tooth53and the members to be welded201is greater than the contact area between the first tooth51and the members to be welded201, so that the tab210in contact with the second tooth53can be stretched, in other words the length of the tab210participating in the ultrasonic vibration increases. It can be understood that since the area increases and the pressing forces from the first tooth51and the second tooth53are constant, the pressure on the tab210in contact with the second tooth53becomes smaller, thereby reducing the friction tearing force from the ultrasonic welding head100on the tab210during the welding, and thus alleviating the undesirable phenomena such as breakage or cracking of the tab210due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2to4,16and17,FIG.16is a schematic structural diagram of a first tooth51according to some embodiments of the present application, andFIG.17is a schematic structural diagram of a second tooth53according to some embodiments of the present application. The first tooth51comprises a first connection surface510connected to the welding surface10, the second tooth53comprises a second connection surface531connected to the welding surface10, the first welding tooth50comprises a first tooth51and a second tooth53arranged spaced apart from the first tooth51, the second tooth53is arranged closer to the connection surface30than the first tooth51, and the second connection surface531has an area greater than that of the first connection surface area510.

Specifically, reference is made to the first tooth and the second tooth in the above embodiments. The first connection surface510may refer to the bottom surface of the aforementioned pyramid. Similarly, the first connection surface510may refer to the bottom surface of the aforementioned pyramid-like body. The area of the second connection surface531and the area of the first connection surface510may be the areas of the aforementioned two bottom surfaces.

In this way, the welding area of the second tooth53is large, the contact between the second tooth53and the pressure-side tab211is more stable, and the stress in the contact region between the tab210and the second tooth53is reduced.

According to some embodiments of the present application, optionally, referring further toFIGS.2to5, the space-keeping surface530is oriented in the same direction as the connection surface30.

Specifically, taking the first tooth51defined as a pyramid as an example, on the basis of the first tooth51, material is removed along a certain path from the top surface of the pyramid toward the bottom surface. A pyramid-like body obtained after the material is removed is the second tooth53. Further, the space-keeping surface530may be a surface formed after the removal of the material. By “the space-keeping surface530is oriented in the same direction as the connection surface30”, it is meant that the space-keeping surface530is not perpendicular to the connection surface30, or that the normals of the space- keeping surface530and the connection surface30are not perpendicular to each other and the normals of the two surfaces both intersect with the members to be welded201.

In this way, compared with the first tooth51without a space-keeping surface530, during the welding, the contact area between the second tooth53and the members to be welded201is larger, so that the tab210in contact with the second tooth53can be stretched, in other words the length of the tab210participating in the ultrasonic vibration increases. It can be understood that since the area increases and the pressing forces from the first tooth51and the second tooth53are constant, the pressure on the tab210in contact with the second tooth53becomes smaller. In addition, the space-keeping surface530can reduce the contact area between the second tooth53and the non-welding region of the tab210, thereby reducing the friction tearing force from the ultrasonic welding head100on the tab210during the welding, and thus alleviating the undesirable phenomena such as breakage or cracking of the tab210due to friction during the ultrasonic welding.

According to some embodiments of the present application, optionally, referring further toFIGS.2and5to9, an extension direction of an intersection line between the welding surface10and the connection surface30is a first direction e, a second direction f is perpendicular to the first direction e, and the centers of the first tooth51and the second tooth53are aligned with each other in the second direction f.

Specifically, taking the ultrasonic welding head100defined as a cuboid as an example, the top surface corresponds to the welding surface10. The aligned centers of the first tooth51and the second tooth53may be the center of the rectangular top surface. The first direction e may be a linear direction where a long side of the cuboid is located, or the length direction of the cuboid. The second direction f may be a linear direction where a short side of the cuboid is located, or the width direction of the cuboid.

In this way, during the ultrasonic welding, the welded parts of the tabs210are vibrated uniformly and are less likely to be subjected to undesirable phenomena such as breakage or cracking.

According to some embodiments of the present application, optionally, referring further toFIG.15, in the second direction f, the first tooth51has a dimension less than that of the second tooth53; and in the first direction e, the first tooth51has a dimension equal to that of the second tooth53.

Taking the ultrasonic welding head100defined as a cuboid and the first tooth51and the second tooth53both defined as pyramids as an example, the top surface of the cuboid corresponds to the welding surface10. Optionally, in the width direction of the welding surface10, W3=1.5W1, where W3and W1are the dimensions of the bottom surfaces of the second tooth53and the first tooth51, respectively. In the length direction of the welding surface10, L1=L3, where L1and L3are the dimensions of the bottom surfaces of the second tooth53and the first tooth51, respectively.

In this way, the dimension of the second tooth53in the second direction f is greater than that of the first tooth51, making it easier to perform further machining on the second tooth53, so as to create a space-keeping structure on the second tooth53. The dimension of the second tooth53in the length direction is equal to that of the first tooth51, so that the space of the welding surface10is effectively utilized.

Referring further toFIGS.1and7, in a second aspect, the present application provides a welding device1000, comprising an ultrasonic welding head100in the foregoing embodiments. The ultrasonic welding head100may have a second welding tooth40defined as a sphere and a first welding tooth50defined as a pyramid, that is, the ultrasonic welding head100shown inFIG.9.

Referring further toFIGS.2to5, according to some embodiments of the present application, an ultrasonic welding head100is provided. The ultrasonic welding head100comprises a welding surface10, a side surface20and a connection surface30, and an avoidance space400is defined between the three surfaces, thereby reducing the contact area between the side surface20of the ultrasonic welding head100and a corner tab215and a cell-side tab213. A second welding tooth40is provided on the connection surface30, and the second welding tooth40may pre-press and shape the tabs210in advance before high-frequency vibration of the ultrasonic welding head100, so as to compress the corner tab215and the cell-side tab213in a fluffy state. A first welding tooth50is provided on the welding surface10, and the first welding tooth50is configured to directly participate in ultrasonic welding. The first welding tooth50comprises a first tooth51and a second tooth53, and the second tooth53is designed to have a space-keeping structure, so as to reduce the frictional forces from the first welding tooth50near the corner tab215and the cell-side tab213to the tabs210in this region. Through the aforementioned ultrasonic welding head100, the friction areas between the corner tab215and the cell-side tab213and the side surface20during welding can be greatly reduced. Moreover, when friction still occurs, the arrangement of the second welding tooth40and the second tooth53can reduce the friction areas between the corner tab215and the cell-side tab213and the ultrasonic welding head100, and reduce the magnitudes of the frictional forces between the corner tab215and the cell-side tab213and the ultrasonic welding head100, thereby alleviating the undesirable phenomena such as breakage or cracking of the corner tab215and the cell-side tab213due to friction during the ultrasonic welding, and improving the quality of the ultrasonic welding.

Finally, it should be noted that the above embodiments are merely used for illustrating rather than limiting the technical solutions of the present application. Although the present application has been illustrated in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features thereof may be equivalently substituted; and such modifications or substitutions do not make the essence of the corresponding technical solution depart from the scope of the technical solutions of the embodiments of the present application, and should fall within the scope of the claims and the description of the present application. In particular, the technical features mentioned in the embodiments can be combined in any manner, provided that there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein but includes all the technical solutions that fall within the scope of the claims.