Welding method for preventing foil from cracking

Abstract

The invention belongs to the technical field of foil welding, and discloses a welding method for preventing foil cracking, which comprises the following steps: S1, stacking an A layer of foil on a lower mold; s2, a first upper welding head adopts ultrasonic welding to pre-weld the A-layer foil into the whole foil with first welding energy, and a first welding printing area is formed during welding of the first upper welding head; and S3, the first upper welding head is replaced with a second upper welding head, the second upper welding head conducts final welding on the whole foil with second welding energy through ultrasonic welding in the first welding printing area, and the first welding energy is smaller than the second welding energy. The method comprises the following steps: firstly, welding and fixing the foils into a foil whole by using relatively small first welding energy; and then the whole foil is subjected to final welding reinforcement with large second welding energy, so that the difference of load and friction behaviors of the contact surfaces of the foils can be reduced, the consistency of welding quality is ensured, and cracking of the surfaces of the foils can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of foil welding, and in particular to a welding method for preventing foil from cracking. Background Art

[0002] In the prior art, ultrasonic welding of foil is usually performed directly using a convex tooth welding head. The copper and aluminum foils with the required number of welding layers are placed on the lower welding head. The materials near the contact surface are affected by high temperature softening and acoustic softening, and plastic deformation occurs under the action of external loads, thereby forming a mechanical fit.

[0003] When the above method is used to weld foils, since the ultrasonic energy gradually decays from the outer layer to the inner layer, when the number of foils to be welded is too large, in order to ensure a higher welding quality and make the foil in the middle part better connected, high-energy welding is required. However, due to the small thickness of a single-layer foil, cracks often occur on the surface of the welded foil. Summary of the invention

[0004] The object of the present invention is to provide a welding method for preventing foil from cracking, which can maintain welding quality while avoiding cracking on the foil surface.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A welding method for preventing foil from cracking comprises the following steps:

[0007] S1, stacking the A layer of foil on the lower mold;

[0008] S2, the first upper welding head uses ultrasonic welding with a first welding energy to pre-weld the foil material of layer A into a whole foil material, and the first upper welding head forms a first weld mark area during welding;

[0009] S3. Replace the first upper welding head with a second upper welding head. The second upper welding head uses ultrasonic welding in the first welding print area to perform final welding on the entire foil material with a second welding energy. The first welding energy is less than the second welding energy.

[0010] In some embodiments, the following step is further included between S2 and S3: detecting whether the foil material of layer A is welded into the foil material as a whole, if so, executing S3; if not, returning to S2.

[0011] In some embodiments, detecting whether a plurality of foils are welded into a foil as a whole comprises the following steps:

[0012] The foil is lifted up as a whole at a point on the uppermost layer or the lowermost layer of the foil to observe whether there is a gap between the foils.

[0013] In some embodiments, detecting whether a plurality of the foils are welded into the foil as a whole further comprises the following steps:

[0014] The foil is divided into a first part and a second part from top to bottom, wherein the first part is a B layer and the second part is an AB layer. The first part and the second part are pulled with a tensile force M to observe whether the first part and the second part are separated; the B is taken as 10%×A; 20%×A; 30%×A; 40%×A; 50%×A; 60%×A; 70%×A; 80%×A; 90%×A in sequence.

[0015] In some embodiments, M is 10N.

[0016] In some embodiments, the second upper welding head forms a second weld print area when welding, and the second weld print area is located within the first weld print area.

[0017] In some embodiments, a size of the first upper welding head is greater than a size of the second upper welding head.

[0018] In some embodiments, the first upper welding head forms a first welding depth when welding, and the second upper welding head forms a second welding depth when welding, and the depth of the first welding depth is less than the depth of the second welding depth.

[0019] In some embodiments, the tooth density of the first upper welding head is greater than the tooth density of the second upper welding head.

[0020] In some embodiments, the first welding energy=first welding time×first welding power; the second welding energy=second welding time×second welding power.

[0021] Beneficial effects of the present invention:

[0022] First, the foil is welded and fixed into a whole foil with a smaller first welding energy; then the whole foil is finally welded and reinforced with a larger second welding energy. Ultrasonic welding is used in both steps, which can reduce the differences in load and friction behavior of the contact surfaces of each foil, thereby ensuring the consistency of welding quality and avoiding cracking of the foil surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the welding method for preventing foil from cracking of the present invention;

[0024] Figure 2 is a schematic diagram of a first weld print area formed by a first upper welding head in the present invention;

[0025] Figure 3 It is a schematic diagram of the second weld mark area formed by the second upper welding head in the present invention.

[0026] In the figure:

[0027] 1. The first weld print area; 2. The second weld print area. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0029] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" 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 an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0031] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0032] like Figures 1 to 3 As shown, the present invention provides a welding method for preventing foil from cracking, the method comprising the following steps:

[0033] S1. Stacking the A-layer foil material on the lower mold. It can be understood that the lower mold can be a welding head or a bottom felt;

[0034] S2, the first upper welding head uses ultrasonic welding with a first welding energy to pre-weld the A layer of foil into a whole foil, and the first upper welding head forms a first weld mark area 1 during welding;

[0035] S3, replacing the first upper welding head with a second upper welding head, the second upper welding head uses ultrasonic welding in the first welding print area 1 to perform final welding on the entire foil with a second welding energy, and the first welding energy is less than the second welding energy.

[0036] In the above manner, the foil is first welded and fixed into an integral foil with a smaller first welding energy; then the integral foil is finally welded and reinforced with a larger second welding energy, and ultrasonic welding is used in both steps, thereby reducing the differences in load and friction behavior of contact surfaces of various foils, thereby ensuring the consistency of welding quality, and thus avoiding cracking on the foil surface; at the same time, ultrasonic welding is used twice, so that no gaps are formed inside the foil, which can further enhance the conductivity.

[0037] It should be noted that, in S1, the A layer is at least 60 layers, and the thickness of each foil layer is 4 μm-20 μm. The whole foil refers to the at least 60 layers of foil being connected into a whole.

[0038] In some embodiments, a detection step is also included between S2 and S3, that is, detecting whether the foil is welded into a whole foil. If the A-layer foil is formed into a whole foil, S3 is continued; if the A-layer foil is not formed into a whole foil, S2 is returned to weld again with the first upper welding head. Thus, the above detection step can avoid cracking of the foil surface due to the failure to form a whole foil.

[0039] In some embodiments, the step of detecting whether the foils are welded into a whole foil includes lifting the foil as a whole, specifically: lifting the foil as a whole at a point on the topmost or bottommost foil to observe whether there are gaps between the foils.

[0040] Furthermore, the detection of whether the A-layer foil is welded into a foil as a whole also includes the following steps: the foil as a whole is divided into a first part and a second part from top to bottom, wherein the first part is the B layer and the second part is the AB layer, and the first part and the second part are pulled by a tensile machine with a tensile force value of M to observe whether the first part and the second part are separated; wherein B is 10%×A; 20%×A; 30%×A; 40%×A; 50%×A; 60%×A; 70%×A; 80%×A; 90%×A in sequence. Thus, it is possible to detect whether the foils at different positions are welded into a foil as a whole through different layers. Specifically, M is 10N.

[0041] In some embodiments, in order to avoid the risk of foil breakage, the second upper welding head forms a second weld mark area 2 during welding, and the second weld mark area 2 is located in the first weld mark area 1 to ensure balanced force transmission. Further, in order to achieve the above method, in the current embodiment, the size of the first upper welding head is larger than that of the second upper welding head.

[0042] In some embodiments, a first weld depth is formed when the first upper welding head is welding, and a second weld depth is formed when the second upper welding head is welding; it should be noted that the first weld depth refers to the pressing depth when the first upper welding head is pressed on the foil, and similarly, the second weld depth refers to the pressing depth when the second upper welding head is pressed on the entire foil; in the current embodiment, the depth of the first weld depth is less than the depth of the second weld depth. The depth when the first upper welding head is welding is smaller, which can reduce the risk of foil breakage, while the depth of the second weld depth is larger, which can make the connection between the foils after the final welding more stable, that is, the degree of fit is higher, thereby improving the welding quality.

[0043] Exemplarily, the first upper welding head adopts a flat tooth welding head, and the second upper welding head adopts a convex tooth welding head. Compared with the flat tooth welding head, the convex tooth welding head can form a deeper weld depth under the same conditions; the flat tooth head and the convex tooth welding head are existing technologies, and their structures are not described in detail.

[0044] In some embodiments, the tooth density of the first upper welding head is greater than that of the second upper welding head. On the basis that the first weld print area 1 is larger, the first upper welding head with a larger tooth density has better consistency in load conditions and friction behaviors between layers of foil during welding.

[0045] It should also be explained here that the first welding energy = first welding time × first welding power; the second welding energy = second welding time × second welding power. Since there is no need for deep welding in S2, it is only necessary to ensure the preliminary connection of the foils; in S3, stable welding is required, and the second welding depth is made greater to ensure the stability of welding, avoid separation between the foils during later use, and reduce the risk of use; it is necessary to ensure that the first welding energy is less than the second welding energy, and the first welding time, the first welding power, the second welding time and the second welding power can be combined in various ways. The specific values ​​of each parameter need to be adjusted according to the number and thickness of the welded foils, and are not specifically limited.

[0046] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A welding method for preventing foil from cracking, characterized in that: The steps include: S1, stacking the A layer of foil on the lower mold; S2, the first upper welding head uses ultrasonic welding with a first welding energy to pre-weld the foil material of layer A into a whole foil material, and the first upper welding head forms a first weld mark area (1) during welding; S3, replacing the first upper welding head with a second upper welding head, wherein the second upper welding head uses ultrasonic welding in the first welding print area (1) to perform final welding on the entire foil material with a second welding energy, wherein the first welding energy is less than the second welding energy.

2. The welding method for preventing foil cracking according to claim 1, characterized in that: The following step is also included between S2 and S3: detecting whether the foil material of layer A is welded into the foil material as a whole, if so, executing S3; if not, returning to S2.

3. The welding method for preventing foil cracking according to claim 2, characterized in that: Detecting whether a plurality of foils are welded into a foil as a whole comprises the following steps: The foil is lifted up as a whole at a point on the uppermost layer or the lowermost layer of the foil to observe whether there is a gap between the foils.

4. The welding method for preventing foil cracking according to claim 3, characterized in that: Detecting whether a plurality of the foils are welded into the foil as a whole also includes the following steps: The foil is divided into a first part and a second part from top to bottom, wherein the first part is a B layer and the second part is an AB layer. The first part and the second part are pulled with a force of M to observe whether the first part and the second part are separated; B is taken as 10%×A; 20％×A； 30％×A； 40％×A； 50％×A； 60％×A； 70%×A; 80%×A; 90％×A。 5. The welding method for preventing foil cracking according to claim 4, characterized in that: The M is 10N.

6. The welding method for preventing foil cracking according to claim 1, characterized in that: The second upper welding head forms a second weld print area (2) when welding, and the second weld print area (2) is located within the first weld print area (1).

7. The welding method for preventing foil cracking according to claim 6, characterized in that: The size of the first upper welding head is greater than that of the second upper welding head.

8. The welding method for preventing foil cracking according to claim 1, characterized in that: The first upper welding head forms a first welding depth when welding, and the second upper welding head forms a second welding depth when welding, and the depth of the first welding depth is less than the depth of the second welding depth.

9. The welding method for preventing foil cracking according to claim 6, characterized in that: The tooth density of the first upper welding head is greater than the tooth density of the second upper welding head.

10. The welding method for preventing foil cracking according to claim 6, characterized in that: The first welding energy=first welding time×first welding power; the second welding energy=second welding time×second welding power.

Images