JP2016175095A - Ultrasonic welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic welding method capable of suppressing the occurrence of disconnection and rupture of metal plates or suppressing the occurrence to the minimum level when performing ultrasonic welding of at least two laminated metal plates, and increasing a yield of ultrasonic welding.SOLUTION: At the time of executing a welding step, metal plates 3A-3C are bent to the side where a collector lead metal plate 1 is located so that a gap is not formed between the metal plates 3A-3C in the vicinity of a temporary weld zone 5 of a connection lead 3 and a welded zone 1A of the collector lead metal plate 1 sandwiched between a horn 7A and an anvil 7B. In a case where the gap cannot be formed between the metal plates 3A-3C, even if the portions of the metal plates 3A-3C which are not temporarily welded are located in the spot sandwiched between the horn 7A and the anvil 7B, the overlapped metal plates 3A-3C are brought into close contact with each other, and thereby junction with excellent actual welding which causes no disconnection and rupture can be obtained.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic welding method for welding a plurality of laminated metal plates, and more particularly to a superconductor suitable for welding metal lead plates when assembling power storage devices such as lithium ion capacitors and lithium ion batteries. The present invention relates to a sonic welding method.

  An electricity storage device such as a bottomed cylindrical lithium ion capacitor or a lithium ion battery is configured by accommodating a wound electrode plate group together with an electrolyte in a bottomed cylindrical container. The wound electrode plate group includes a positive electrode plate, a separator, and a negative electrode plate. The positive electrode plate and the negative electrode plate are respectively connected to the positive electrode terminal and the negative electrode provided at both ends of the electricity storage device through the positive electrode current collector and the negative electrode current collector. Connected to the terminal, charging / discharging to / from the outside is performed through the both terminals. When assembling such an electricity storage device, in order to electrically connect the current collector and the lid, the free ends of the two metal lead plates extending from each other are welded to each other, and then the electrolytic solution is put into the container. Then, a step of attaching a lid to be one terminal to the container by caulking is performed.

  Before the lid is attached to the container, in order to electrically connect the current collector and the lid, the free ends of the two metal lead plates extending from each other are welded. Since a large current flows through the lead plate, it is necessary to minimize the resistance. For this purpose, it is preferable to make the distance of current flow between the joints as short as possible and to make the cross-sectional area of the path as large as possible. In order to realize this requirement, one of the lead plates is a laminated plate in which at least two metal plates are laminated, and the other one lead plate made of metal plates is superposed and ultrasonic welding is put into practical use. Has been. Since ultrasonic welding is solid phase welding, it has the characteristics that there is little adverse effect on the metal structure due to the generation of heat and the bonding strength is also high.

  However, according to ultrasonic welding, as the number of metal plates to be stacked increases and the thickness increases, the metal plate is easily broken or broken only by the main welding, which deteriorates the yield of the electricity storage device. Prior to the main welding, the laminated plate may be temporarily welded under relatively weak ultrasonic welding conditions in order to prevent the occurrence of misalignment between the laminated metal plates and increase the accuracy of ultrasonic welding. Has been done. Japanese Patent Laying-Open No. 2010-153074 discloses a connection method having a temporary welding process in which ultrasonic welding is performed with ultrasonic vibration energy smaller than the ultrasonic vibration energy in the welding process before the welding process (Patent Document 1). ).

  However, even temporary welding has not led to a significant reduction in breakage and breakage of the laminated metal plates. In Japanese Patent Laid-Open No. 4-221413, sufficient bonding strength can be obtained by applying ultrasonic vibration once depending on the conditions, rather than applying ultrasonic vibration in two steps, temporary welding and main welding. It has been reported (Patent Document 2, [0026]).

JP 2010-153074 A JP-A-4-221413

  In ultrasonic welding of two or more laminated metal plates including a temporary welding step and a subsequent main welding step, disconnection or breakage of the metal plate in the main welding is temporarily welded in the vicinity of the part to be main welded. It was found that it occurred in the part that was not.

  An object of the present invention is to suppress or minimize the occurrence of disconnection or breakage of a metal plate when ultrasonically welding at least two laminated metal plates, thereby increasing the yield of ultrasonic welding. An object of the present invention is to provide an ultrasonic welding method that can be used.

  As a result of intensive studies, the inventors have found that when there is a gap between the position where the temporary welding is performed and the position where the main welding is performed, the portion where the temporary welding is not performed or the temporary welding is insufficient, It was found that the metal plate was disconnected or broken by the main welding. In further research, disconnections and fractures of metal plates are not preliminarily welded or insufficient, resulting in gaps between overlapping metal plates. It has been found that the ultrasonic vibrations of the above cause large vibrations of a plurality of metal plates. In the vicinity of the ultrasonic welding tool, if a gap is formed between the metal plates of the part that is not temporarily welded, the energy that should be spent on welding between the metal plates is temporarily welded due to the vibration of the ultrasonic welding tool. It is presumed that the metal plate is broken or broken as a result of causing a large metal plate to vibrate and generating a shearing stress on the vibrating metal plate.

  In the present invention, in order to join a part of one metal plate and a part of a laminated plate composed of at least two metal plates laminated with a thickness equal to or less than the thickness of the metal plate 1, The present invention is directed to an ultrasonic welding method in which the temporary welding step and the main welding step are performed. In the following description, in order to facilitate understanding, the symbols used in the embodiments are listed. In the present invention, in the temporary welding step, two or more metal plates are partially welded to each other by temporary welding to form the temporary welded portion 5. In the main welding step, the temporary welded portion and the welded portion 1A are paired with a pair of ultrasonic welding tools in a state where the temporarily welded portions of two or more metal plates that have been temporarily welded are stacked on the welded portion of one metal plate. By sandwiching and ultrasonically vibrating at least one of the pair of ultrasonic welding tools, the temporary welded portion and the welded portion are joined. In the present invention, two or more metals are provided in the vicinity of the pair of ultrasonic welding tools in a state where the temporary welding portion 5 and the welded portion 1A are sandwiched between the pair of ultrasonic welding tools when the main welding step is performed. Two or more metal plates 3 are bent to the side where one metal plate is positioned so that a gap cannot be formed between the plates 3. In this way, by bending two or more metal plates 3 to the side where one metal plate is located, a gap cannot be formed between the two or more metal plates 3. In this case, even if the part that is not temporarily welded due to inaccurate positioning of the parts in the temporary welding step is located outside the ultrasonic welding tool, the part of the metal plate that is not temporarily welded Since there is no gap that causes the metal plate to vibrate greatly, the superimposed metal plates closely contact each other to minimize or prevent vibration of the metal plate, and as a result, disconnection or breakage is less likely to occur. Good bonding can be obtained.

  The two or more metal plates may be further temporarily welded at the end portion away from the temporarily welded portion, thereby making it difficult to form a gap between the metal plates.

  Further, two or more metal plates may be bent in the vicinity of the temporary welded portion before being sandwiched by the pair of ultrasonic welding tools together with the welded portion, or after being sandwiched. Bending may be performed in the vicinity of the temporary weld 1A.

  Furthermore, the present invention specifically relates to a part of a current collecting lead metal plate made of one metal plate extending from a current collecting plate of a battery or a storage cell such as a capacitor, and the thickness of the current collecting lead metal plate or less. It can be applied to an ultrasonic welding method in which the other end of a connection lead composed of at least two metal plates laminated with a thickness of 1 mm and having one end welded to a lid is joined by ultrasonic welding. Even in this case, the present invention provides a temporary welding step in which two or more metal plates are partially welded to each other by temporary welding to form a temporary welded portion 5, and a temporary welded portion of two or more temporarily welded metal plates. In a state where the welded portion of one metal plate is overlapped, the temporary welded portion and the welded portion are sandwiched between a pair of ultrasonic welding tools, and at least one of the pair of ultrasonic welding tools is ultrasonically vibrated, A main welding step for joining the temporary welded portion and the welded portion is performed. In the present invention, the temporary welding portion and the welded portion are sandwiched between a pair of ultrasonic welding tools at the time of performing the main welding step, and between two or more metal plates in the vicinity of the pair of ultrasonic welding tools. The ultrasonic welding method is configured such that two or more metal plates are bent toward the side where one metal plate is positioned so that a gap cannot be formed. In this way, if two or more metal plates 3 are bent to the side where one metal plate is located so that no gap can be formed between the two or more metal plates, positioning in the temporary welding step is accurate. Even if a portion that has not been temporarily welded due to a cause such as not being generated on two or more metal plates 3, each metal plate is excellent in that the overlapping metal plates are in close contact with each other and disconnection or breakage does not occur. Bonding can be obtained.

It is an enlarged front view which shows the mode of the main welding step which welds a current collection lead metal plate and a connection lead in one embodiment of the ultrasonic welding method which concerns on this invention. FIG. 2 is a half sectional view showing a state where a current collecting lead metal plate and a connection lead in the embodiment of FIG. 1 are welded. FIG. 3 is a half sectional view showing the entire lithium ion capacitor in the state of FIG. 2.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In the illustrated embodiment, the present invention is applied to the assembly of a cylindrical lithium ion capacitor which is a kind of power storage device or power storage cell.

  FIG. 1 is an enlarged front view showing a state of a main welding step of welding a current collecting lead metal plate and a connection lead in one embodiment of the ultrasonic welding method according to the present invention. FIG. 2 is a half sectional view showing the vicinity of the positive electrode of the capacitor 4 shown in FIG. 3 in an enlarged manner. FIG. 3 schematically shows a half of a cylindrical lithium ion capacitor 4 (hereinafter abbreviated as “capacitor 4”) assembled by applying the embodiment of the ultrasonic welding method of the present invention. FIG.

  In each figure, the capacitor 4 has an outer shape formed of a steel-bottomed cylindrical container body 8 plated with nickel and a lid 9 that closes the upper surface opening of the container body 8 (before closing). ing. The container body 8 and the lid 9 are electrically insulated from each other, and the container body 8 constitutes a negative electrode terminal and the lid 9 constitutes a positive electrode terminal.

  An electrode plate group unit comprising a combination of the positive electrode current collector plate 2, the negative electrode current collector plate 10 and the wound electrode plate group 11 is accommodated in the container body 8. The wound electrode plate group 11 is configured by winding a belt-like positive electrode plate and a negative electrode plate through a separator on a hollow cylindrical PPS (polyphenylene sulfide) shaft core (both are not shown). Although illustration is omitted, the welded portion of the positive electrode plate in the wound electrode plate group 11 is electrically connected to the positive electrode current collector plate 2 by welding. The same applies to the relationship between the negative electrode plate and the negative electrode current collector plate 10.

  The positive electrode current collector plate 2 is electrically insulated from the container body 8 by an insulating ring 12, while the negative electrode current collector plate 10 is directly welded to the container body 8. The lid 9 is finally attached to the upper surface opening of the container main body 8 by caulking after achieving electrical insulation with the container main body 8 via the insulating member 13. In each figure, the caulking process is not performed.

  Before the lid 9 is attached to the container body 8, the positive electrode current collector plate 2 and the lid 9 are electrically connected through the current collector lead metal plate 1 and the connection lead 3. The positive electrode current collector plate 2 and the current collector lead metal plate 1 are integrally formed. Specifically, the current collecting lead metal plate 1 is formed by cutting and raising a part of the positive electrode current collecting plate 2. One end of the current collector lead metal plate 1 is connected to the positive electrode current collector plate 2, and the other end is ultrasonically welded to the other end of the connection lead 3. One end of the connection lead 3 is welded to the back surface of the lid 9, and the other end is ultrasonically welded to the other end of the current collector lead metal plate 1. The ultrasonic welding of the other ends of the current collecting lead metal plate 1 and the connection lead 3 is performed by the method of the embodiment of the present invention. Hereinafter, embodiments will be described in detail.

  From the surface of the positive electrode current collector plate 2 facing the lid 9, the current collector lead metal plate 1 made of a single metal plate extends upward in the drawing so as to extend from the upper surface opening of the container body 8. . As described above, the current collector lead metal plate 1 is formed integrally with the positive electrode current collector plate 2 and both are made of aluminum.

  The connection lead 3 is a laminated plate in which three metal plates 3A to 3C are laminated. The connection lead 3 is welded to the back surface 9A of the lid 9 at one end (terminal portion 6), extends so as to form a gradually widening gap with the back surface 9A of the lid 9, and then separates from the back surface 9A. Bent in the direction. The connection lead 3 is temporarily welded to each other in a state where the three metal plates 3A to 3C are laminated at the end portion 6 before being welded to the back surface of the lid 9 at one end. In the process of assembling the lid 9, welding of one end of the connection lead 3 to the back surface 9 </ b> A of the lid 9 is completed.

  The connection lead 3 is formed by laminating metal plates 3 </ b> A to 3 </ b> C made of aluminum with a thickness equal to or less than that of the current collecting lead metal plate 1. The connection lead 3 is composed of the three thin metal plates 3A to 3C because the current flowing through the connection lead 3 is shared by the respective metal plates 3A to 3C, thereby suppressing the heat generation of the connection lead 3. Because.

  In the present embodiment, the thickness of each of the metal plates 3A to 3C is preferably 0.1 to 0.3 mm. The thickness of the current collecting lead metal plate 1 is preferably 0.4 mm or more, and is a thickness required according to the capacity of the lithium ion capacitor. The number of metal plates constituting the connection lead 3 is not limited as long as it is two or more.

  Next, the ultrasonic welding method of the present embodiment including the temporary welding step and the main welding step will be described with reference to FIG.

  In the temporary welding step, the three metal plates 3A to 3C are partially welded to each other by temporary welding to form the temporary welded portion 5. The temporary welding method is ultrasonic welding in the present embodiment. In the temporary welding, three metal plates 3A to 3C are sandwiched between a pair of ultrasonic welding tools (horn and anvil) of an ultrasonic welding apparatus, and one jig (horn) is ultrasonically vibrated to form three metal plates. Weld the plates simultaneously.

  In the present embodiment, the three metal plates 3A to 3C are temporarily welded not only to the temporary welded portion 5 near one end but also the end portion 6 near the other end. The end portion 6 is formed by temporary welding at the same time as the temporary welding portion 5, but is not limited thereto.

  The welding conditions such as the vibration period of temporary welding are appropriately adjusted according to the type of ultrasonic welding apparatus, the thickness and material of the metal plate, and the vibration period is about 20 kHz and the output is 700 W, for example.

  Before the application of ultrasonic vibration is started in the main welding step, the bending lead step is applied to the connection lead 3 in which the temporary welding portion 5 and the end portion 6 near the both ends are temporarily welded. Before and after the step, a connection step to the lid 9 is performed in which the end portion 6 is connected to the back surface of the lid 9.

  In the present embodiment, the connection step is executed first. The end portion 6 of the connection lead 3 is placed at a predetermined position on the back surface of the lid 9 and welded by spot welding. Thereby, the lid 9 and the connection lead 3 are electrically connected.

  Next, the operator holds the lid 9 to which the connection lead 3 is welded by hand or grasps it with a grasping device (not shown), and the electrode plate group unit is inserted to collect the current collecting lead from the positive electrode plate 2. The lid 9 is moved to the vicinity of the upper opening of the container body 8 of the capacitor 4 assembled to the state where the metal plate 1 extends upward. Further, the position of the lid 9 is finely adjusted so that the temporarily welded portion 5 of the connection lead 3 overlaps the welded portion 1A near one end of the current collecting lead metal plate 1. In this state, the horn 7A and the anvil 7B of the ultrasonic welding apparatus are moved, the horn 7A and the anvil 7B are brought close to each other, and the horn 7A is in contact with the connection lead 3 as shown in FIG. The anvil 7B is in contact with the plate 1 and is sandwiched between the horn 7A and the anvil 7B.

  The connection lead 3 is sandwiched between the horn 7A and the anvil 7B, and is bent in the vicinity of 90 degrees to the side where the current collecting lead metal plate 1 is located. The bending angle is preferably 30 ° or more in consideration of interference with the horn 7A. In this state, since the metal plate 3C located outside the bent portion is displaced in the longitudinal direction, the metal plate 3B is pushed toward the center of the bend, and the metal plate 3A located inside the bent portion is compressed in the longitudinal direction. Therefore, the metal plate 3B is pushed toward the outside of the bend. Accordingly, the three metal plates 3A to 3C are in close contact with each other so that no gap can be formed between them. In this way, by preventing a gap from being formed between the metal plates 3A to 3C, the stacked metal plates 3A to 3C are brought into close contact with each other, thereby minimizing or preventing misalignment. As a result, in the main welding of the connection lead 3 and the current collecting lead metal plate 1, it is possible to realize good bonding without disconnecting or breaking the metal plates 3 </ b> A to 3 </ b> C.

  That is, as in the present embodiment, the term “bending” in this specification is not limited to irreversible processing such as by using a die and a punch, and the current collecting lead metal plate 1 by an ultrasonic welding tool. It is only necessary to bend so that a gap cannot be formed between the metal plates 3A to 3C by the time when preparation for starting the main welding is completed with the connection lead 3 interposed therebetween.

  Next, when the horn 7A of the ultrasonic welding apparatus is activated and a main welding step of applying ultrasonic vibration to the connection lead 3 is performed, the temporary welding portion 5 of the connection lead 3 and the current collecting lead metal plate 1 The welded part 1A is welded and joined. At this time, the occurrence of disconnection or breakage is minimized or prevented as described above.

  The vibration period in the main welding is, for example, about 20 kHz, the output is about 1000 to 3000 W, and the ratio of the output of the temporary welding and the main welding is generally in the range of 1: 1.2 to 1: 4.0. If it is this range, the resistance of a temporary welding part can be lowered | hung before a main welding, and also it does not affect a bending process.

  When the main welding step is completed, the electrolytic solution is injected, and then the lid 9 is attached to the container body 8 by caulking, so that the physical configuration of the capacitor 1 is almost completed.

  In the above embodiment, the present invention is applied to the manufacture of a lithium ion capacitor, but the present invention can of course be applied to other uses.

  According to the present invention, two or more metal plates 3 are bent toward the side where one metal plate 1 is located, so that no gap can be formed between the two or more metal plates 3, and the wire breaks or breaks. Therefore, it is possible to realize a good bonding with less occurrence of the phenomenon, and in particular, it is possible to improve the yield of a lithium ion capacitor, a lithium ion secondary battery, or the like.

1 Current collecting lead metal plate (1 metal plate)
1A Welded part 2 Positive current collector 3 Connection lead (laminated plate)
3A-3C Metal plate 4 Capacitor 5 Temporary welding part 6 Terminal part 7A Horn (ultrasonic welding tool)
7B Anvil (Ultrasonic Welding Tool)
8 Container 9 Lid 10 Negative Current Collector 11 Winding Electrode Group 12 Insulating Ring 13 Insulating Member

Claims (5)

Ultrasonic welding method for joining by ultrasonic welding a part of one metal plate and a part of a laminated plate composed of at least two metal plates laminated with a thickness equal to or less than the thickness of the metal plate Because
A temporary welding step in which the two or more metal plates are partially welded to each other by temporary welding to form a temporary welded portion;
The temporary welded part and the welded part are sandwiched between a pair of ultrasonic welding tools in a state where the temporary welded part of the two or more metal plates temporarily welded are overlapped with the welded part of the single metal plate. And performing a main welding step for joining the temporary welded portion and the welded portion by ultrasonically vibrating at least one of the pair of ultrasonic welding tools,
The two or more metals in the vicinity of the pair of ultrasonic welding tools in a state where the temporary welding portion and the welded portion are sandwiched between the pair of ultrasonic welding tools at the time of performing the main welding step. The ultrasonic welding method, wherein the two or more metal plates are bent toward a side where the one metal plate is positioned so that a gap cannot be formed between the plates.   The ultrasonic welding method according to claim 1, wherein the two or more metal plates are further temporarily welded at a terminal portion separated from the temporary welding portion.   3. The two or more metal plates are bent in the vicinity of the temporary welded portion before being sandwiched by the pair of ultrasonic welding tools together with the welded portion. Ultrasonic welding method.   The two or more metal plates are bent in the vicinity of the temporary welded portion after being sandwiched by the pair of ultrasonic welding tools together with the welded portion. Ultrasonic welding method. A part of a current collecting lead metal plate made of one metal plate extending from a current collecting plate of a storage cell, and at least two or more metal plates laminated with a thickness less than the thickness of the current collecting lead metal plate An ultrasonic welding method for joining the other end of the connection lead having one end welded to the lid by ultrasonic welding,
A temporary welding step in which the two or more metal plates are partially welded to each other by temporary welding to form a temporary welded portion;
The temporary welded part and the welded part are sandwiched between a pair of ultrasonic welding tools in a state where the temporary welded part of the two or more metal plates temporarily welded are overlapped with the welded part of the single metal plate. And performing a main welding step for joining the temporary welded portion and the welded portion by ultrasonically vibrating at least one of the pair of ultrasonic welding tools,
The two or more metals in the vicinity of the pair of ultrasonic welding tools in a state where the temporary welding portion and the welded portion are sandwiched between the pair of ultrasonic welding tools at the time of performing the main welding step. The ultrasonic welding method, wherein the two or more metal plates are bent toward a side where the one metal plate is positioned so that a gap cannot be formed between the plates.

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