JP2018051591A - Judging method and joining apparatus for judging replacement of ultrasonic welding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determination method for determining replacement of an ultrasonic bonding tool capable of efficiently using a tool required for ultrasonic welding for a longer life, and a bonding device for carrying out the determination method. According to the present invention, a threshold value is set in advance for a peeling force when peeling a horn 22 or an anvil 23 from a work after forming a joint portion in the work, and the horn and the anvil are brought into contact with the work for joining. A portion is formed, the peeling force when peeling the horn or anvil from the work is measured, and the measured peeling force is compared with the threshold value to determine the replacement of the horn or anvil. [Selection diagram] FIG. 7

Description

  The present invention relates to a determination method and a joining apparatus for determining replacement of an ultrasonic joining tool.

  The electrode tab derived from the unit cell constituting the secondary battery is joined to the current collector accommodated in the unit cell. The joints may be joined by ultrasonic joining, and the ultrasonic joining is generally performed using an ultrasonic joining tool such as a horn or anvil. The horn or anvil used for ultrasonic bonding needs to be replaced due to the wear of the portion to be welded or the adhesion of the workpiece to the tool over time.

  As a conventionally known method for determining the replacement of an ultrasonic welding tool, there is a technique for detecting a change over time of a step provided at a machining position of a tool for machining a workpiece as a wear amount (see Patent Document 1). ).

JP 2014-104493 A

  The present inventor examined the long-term use of the above-mentioned tool, and the case where the tool can be used even when the amount of wear of the step at the machining location has progressed considerably as in Patent Document 1. Found that there is.

  Accordingly, the present invention provides a determination method for determining replacement of an ultrasonic welding tool that can efficiently use a tool necessary for ultrasonic welding near the end of its life instead of the amount of wear of a step at a machining location, and the determination method. An object of the present invention is to provide a joining apparatus that performs the above.

  The present invention that achieves the above object is a case in which a joining location is formed on a material to be joined including a plurality of members using an ultrasonic joining tool, and ultrasonic joining is considered in consideration of repeated use of the ultrasonic joining tool. This is a determination method for determining tool replacement. In the above determination method, a threshold is set in advance for the peeling force when the ultrasonic bonding tool is peeled off from the material to be bonded after the formation of the bonding point, and the ultrasonic bonding tool is brought into contact with one material to be bonded to determine the bonding point. Form. And the peeling force at the time of peeling an ultrasonic joining tool from one to-be-joined material is measured, and replacement | exchange of an ultrasonic joining tool is determined by comparing a peeling force and a threshold value.

  The present invention that achieves the above object is a joining device having a joining portion, a measuring portion, and a control portion. A joining part forms a joining location in a to-be-joined material containing a plurality of members using an ultrasonic joining tool, and the above-mentioned ultrasonic joining tool is exchanged by repeated use of an ultrasonic joining tool. A measurement part measures the peeling force at the time of peeling off an ultrasonic joining tool from a to-be-joined material after formation of a joining location. A control part memorizes a threshold beforehand about the above-mentioned peeling force, and judges exchange of an ultrasonic joining tool by comparing the above-mentioned peeling force and the above-mentioned threshold.

  According to the determination method and the joining apparatus of the present invention, a tool necessary for ultrasonic welding can be used efficiently to near the end of its life.

It is a schematic perspective view which shows the joining apparatus which concerns on one Embodiment of this invention. It is a fragmentary sectional view which shows a joining apparatus and shows the internal structure of the site | part which generate | occur | produces an ultrasonic wave. It is a perspective view which shows the process front-end | tip part of the tool (horn) used for ultrasonic joining. It is a side view which shows the process front-end | tip part of the tool (horn) used for ultrasonic joining. It is a front view which shows the process front-end | tip part of the tool (horn) used for ultrasonic joining. It is typical sectional drawing of the secondary battery which is an example of the object which uses the joining method which concerns on one Embodiment of this invention. It is a flowchart shown about the determination method of the tool exchange which concerns on one Embodiment of this invention. It is a graph which shows about the relationship between time and a load at the time of peeling an anvil from a joining component, when joining components do not adhere to an anvil as one embodiment of the present invention. It is a graph which shows about time and the relationship at the time of peeling a horn from joining components, when joining components do not adhere to a horn as one Embodiment of this invention. It is a front view which shows the joining apparatus which concerns on the modification of this invention. It is a graph which shows the relationship between the time at the time of separating a workpiece | work and a tool, and a load, Comprising: When the approach and separation movement of a workpiece | work and a tool is performed through supply of a fluid, the tool considers the pressure fluctuation of the fluid to supply. It is a graph which shows the case where the data which determine replacement | exchange are corrected.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The sizes and ratios of the members in the drawings are exaggerated for convenience of explanation and may be different from the actual sizes and ratios.

(Application example of joining method according to this embodiment)
FIG. 6 is a typical cross-sectional view of a secondary battery that is one of objects to which ultrasonic bonding according to an embodiment of the present invention is applied. The secondary battery 200 will be briefly described. As shown in FIG. 6, a power generation element 260 in which a single battery 240 having a separator 230 interposed between a positive electrode 210 and a negative electrode 220 is stacked in an exterior body 250. Yes. The positive electrode 210 is configured by providing the positive electrode current collector 211 with the positive electrode active material layer 212, and the negative electrode 220 is configured by providing the negative electrode current collector 221 with the negative electrode active material layer 222. The secondary battery 200 shown in FIG. 6 is configured as a so-called stacked secondary battery.

  As shown in FIG. 6, the positive electrode current collector 211 is joined to the positive electrode tab 213 in the vicinity of the outer periphery of the outer package 250. The negative electrode current collector 221 is joined to the negative electrode tab 223 near the outer periphery of the outer package 250 in the same manner as the positive electrode. The ultrasonic bonding according to the present embodiment is used when the positive electrode tab 213 and the plurality of positive electrode current collectors 211 are bonded, and when the negative electrode tab 223 and the plurality of negative electrode current collectors 221 are bonded. The Hereinafter, the case where the electrode tab and the current collector are joined will be described without distinguishing between the positive electrode and the negative electrode.

(Joining equipment)
FIG. 1 is a perspective view showing a bonding apparatus according to an embodiment of the present invention, and FIG. 2 is a side view of FIG. The bonding apparatus 100 according to the present embodiment includes a transport unit 10, a bonding unit 20, a measurement unit 30, and a control unit 40 as outlined with reference to FIGS.

  The transport unit 10 includes a mounting table 11 and a motor 12. The mounting table 11 is a table on which a plurality of materials to be bonded (bonded members) serving as workpieces are mounted. In this embodiment, the installation surface is made of a flat metal. The mounting table 11 is configured such that the right end in FIG. 2 extends beyond the positions of a horn 22 and an anvil 23 described later. The mounting table 11 is configured to penetrate through an overhead portion of the anvil 23 (see the broken line in FIG. 1) so that the workpiece and the anvil 23 can come into contact with each other. However, the material and shape of the mounting table are not limited to the above as long as the workpiece does not move or slide unintentionally during joining and the workpiece can be contacted with the horn 22 and the anvil 23.

  The motor 12 is housed in the housing shown in FIG. 2, and the mounting table 11 on which the workpiece is placed is brought close to the anvil 23 that constitutes the joining portion 20, or the joined workpiece is separated from the anvil 23. Configured for. The mounting table 11 is moved in the vertical direction in FIG. 2 by the motor 12 in this embodiment, and approaches or separates from an anvil 23 that constitutes a joint 20 described later. The motor 12 is configured as a servo motor in this embodiment. However, the present invention is not limited to this as long as the mounting table 11 can be moved toward and away from the anvil 23.

  As shown in FIG. 2, the joint portion 20 includes a vibration generating portion 21, a horn 22, an anvil 23, a motor 24, and a spring 25. The vibration generating unit 21 includes an ultrasonic vibrator and a booster. The ultrasonic transducer is composed of a transducer or the like, and generates a vibration corresponding to the frequency of the ultrasonic wave by electric power supplied from the outside. The ultrasonic transducer has one end connected to a booster and the other end connected to a power cable or the like. The booster is made of metal and connected to the horn 22 and the ultrasonic transducer. The booster amplifies the vibration generated by the ultrasonic transducer.

  3 to 5 are a perspective view, a side view, and a front view showing a tip portion of a horn used for ultrasonic bonding. The horn 22 generates frictional heat by applying ultrasonic waves to the joining surface of the current collector or electrode tab constituting the workpiece and vibrating the horn 22. The horn 22 is configured to be moved toward and away from the workpiece in the vertical direction in FIG.

  As shown in FIGS. 3 to 5, the tip surface of the horn 22 is provided with an infinite number of substantially quadrangular pyramid or quadrangular pyramid protrusions 22 a. The tip of the protruding shape 22a comes into contact with the workpiece. The protruding shape 22a is also called knurling or knurling. The tip of the protrusion shape 22a is worn by repeated use, and the height from the apex to the base of the substantially quadrangular pyramid shown in FIG. 4 gradually decreases, which requires a tool change. The replacement of the horn 22 and / or the anvil 23 will be described later.

  The anvil 23 is a table on which the joining portion of the workpiece is placed when the workpiece is joined by the horn 22, receives ultrasonic vibration from the horn 22, and holds the workpiece together with the horn 22. Similar to the horn 22 shown in FIG. 3 to FIG. 5, the anvil 23 is provided with an infinite number of protrusions arranged at the joint location with the workpiece. The horn 22 and the anvil 23 correspond to the ultrasonic bonding tool in this embodiment.

  The motor 24 moves the vibration generating unit 21 and the horn 22 close to or away from the workpiece in the vertical direction in FIG. The spring 25 is configured to apply a reaction force against the pressing force by the motor 24 on the vibration generating unit 21, and thereby the position of the vibration generating unit 21 is maintained. The motor 24 and the spring 25 constitute a moving part of the vibration generating part 21.

  The measuring unit 30 collects information on the peeling force when the horn 22 or the anvil 23 is peeled from the workpiece by measurement. As shown in FIG. 2, the measurement unit 30 includes force sensors 31 and 32 and a position sensor 33. The force sensor 31 is installed in order to monitor a change in the applied pressure when the workpiece after joining is separated from the horn 22. The force sensor 31 may be, for example, a piezoelectric load cell, but is not limited thereto. The force sensor 32 monitors a change in the applied pressure necessary to move the mounting table 11 of the transport unit 10 when the workpiece after joining is separated from the anvil 23.

  The position sensor 33 measures the position of the vibration generating unit 21 that is displaced according to the operation of the motor 24. The position sensor 33 can be configured by, for example, a linear encoder, but is not limited thereto.

  The control unit 40 is configured by storing a CPU, a RAM, a ROM, and the like in a housing shown in FIGS. With these configurations, the control unit 40 uses the horn 22 and the anvil 23 to form a joint portion on the workpiece, and then instructs the horn 22 and the anvil 23 to be separated from the workpiece and separated. Moreover, the control part 40 memorize | stores the peeling force when the replacement | exchange of the horn 22 or the anvil 23 is needed as a threshold value, compares the measured value which the measurement part 30 memorize | stored, and a threshold value, and determines replacement | exchange of a tool. Then, a tool change is instructed as necessary. Details will be described later.

(Joining method)
Next, the joining method according to this embodiment will be described. FIG. 7 is a flowchart showing the bonding method according to this embodiment. In this embodiment, a case where a current collector and an electrode tab are joined in the secondary battery 200 shown in FIG. 6 will be described as an example. However, this is an example, and as long as two or more members are joined using ultrasonic waves, the joining method according to the present invention can be applied to joining workpieces other than the secondary battery.

  When the joining method according to the present embodiment is outlined with reference to FIG. 7, when the current collector and the electrode tab are joined and the anvil 23 or the horn 22 is peeled from the current collector or the electrode tab, the horn 22 or A threshold for determining replacement of the anvil 23 is set (ST1). Next, a current collector and an electrode tab as a workpiece are placed on the mounting table 11 (ST2). Next, a joint location is formed at a predetermined position between the current collector and the electrode tab (ST3).

  Next, the horn 22 or the anvil 23 is separated from the work (ST4). Then, the peeling force (peeling load) when the horn 22 and the anvil 23 are separated from the workpiece is measured by the force sensors 31 and 32 (ST5), and the measured peeling force is compared with the set threshold (ST6). When the peeling force exceeds the threshold value, a tool change is instructed (ST8). Details will be described below.

(About tool wear)
First, a threshold for determining tool replacement will be described. FIG. 8 is a graph showing the relationship between the load and the time when the anvil is peeled from the joined part when the joined part is attached to the anvil and not when the joined part is attached as an embodiment of the present invention. FIG. 9 is a graph showing the relationship between time and load when the horn is peeled off from the joined part when the joined part is attached to the horn and not when the joined part is attached as an embodiment of the present invention.

  The inventor has intensively studied the matter of using the tool for a longer period.

  When the anvil 23 and the horn 22 are relatively new, the anvil 23 and the horn 22 come into contact with the work so as to bite into the work, and form a joint portion on the work while being firmly fixed to the work during the ultrasonic vibration.

  On the other hand, when wear of the anvil 23 and the horn 22 progresses, a slip occurs between the anvil 23 and the horn 22 and the workpiece during the joining, and the joining may be performed in that state. In this case, an adhesion point (adhered point) can be formed between the anvil 23 or the horn 22 and the workpiece from the state where the slip has occurred.

  Depending on the adhesive force between the workpiece and the horn 22 or the anvil 23, when the horn 22 or the anvil 23 is peeled away from the workpiece and separated, the joint with the workpiece may be deformed to some extent from the state before joining. is there.

  In this way, if the shape of the workpiece is deformed before joining due to joining, there may be cases where the assembly with other parts is affected in the subsequent process, or work for returning the workpiece to the original shape may be required. . Such a situation needs to be prevented, and for this purpose, it is necessary to replace the tool in use at an appropriate timing.

  As shown in FIGS. 8 and 9, when the workpiece and the horn 22 or the anvil 23 are not attached (see the broken line b in FIGS. 8 and 9) (see the solid line a in FIGS. 8 and 9). ), The force for peeling off the horn 22 or the anvil 23 from the workpiece is partially increased. The present inventor has found that there is a case where the work can be performed without any problem without deformation of the work as described above even when the wear of the horn or the anvil progresses. As a tool change index, it is better to monitor the peel force (peeling force) when peeling the horn or anvil from the workpiece as described above, rather than the wear amount of the tool such as the horn or anvil. It was found that it can be judged more appropriately.

  In the joining method according to the present embodiment, the data shown in FIG. 8 and FIG. 9 is measured every time when the joining portion is formed on the workpiece using the horn 22 or the anvil 23, and the maximum value is taken as the measured value. Then, when the horn 22 or the anvil 23 is peeled off from the work, the time when the work is deformed is specified, and for example, the peeling force at the time immediately before that time is recorded in the control unit 40 as a threshold value.

  In other words, the peeling force immediately before the current collector or the electrode tab is deformed is stored in the control unit 40 as a threshold value. The threshold value may be a value obtained by multiplying the calculated or measured value by a safety factor, for example, 95% of the measured value, in order to prevent defective products from appearing. The load when the current collector and electrode tab, which are workpieces, are turned up is simulated to prevent the above situation from occurring when a mass production line is operated. Separately from the line, it is preliminarily measured and calculated in an experiment (ST1). Here, “preliminarily” in the above means that the threshold value has been set before the time point when the control unit 40 described later determines the replacement of the tool at the latest.

  Next, the work is set on the mounting table 11, the transport unit 10 is driven, and the work is moved toward the anvil 23 and brought into contact therewith. Next, the horn 22 is moved toward the workpiece by the motor 24 and brought into contact with the workpiece (ST2). Then, energy is supplied to the vibration generating unit 21 to generate ultrasonic vibration in the horn 22 to form a joint portion on the workpiece (ST3).

  Next, the motor 24 is driven, and the horn 22 is separated from the workpiece and separated (ST4). When the bonding force between the workpiece and the anvil or the workpiece and the horn is large at the time of bonding, the bonded portion may be deformed. In this embodiment, in order to prevent such a situation, the load at the time of peeling is measured by the force sensor 31 (ST5) and compared with the threshold value obtained above (ST6).

  If the peeling force is lower than the threshold value (ST6: YES), it is next determined whether all tools have been peeled from the workpiece (ST7). Since only the horn 22 is peeled at this time (ST7: NO), this time, the mounting table 11 is moved to peel the anvil 23 from the workpiece (ST4), and the peeling force is measured by the force sensor 32 (ST5). Compare with the threshold (ST6).

  When the peeling load is less than the threshold value (ST6: YES), all the tools are peeled from the workpiece at the present time (ST7: YES). In that case, the control unit 40 determines that the tool is not exchanged at this time, and returns to step ST2 to set a new workpiece (ST2), form a joint (ST3), peel the tool (ST4), and The peel force is measured (ST5).

  When the peeling force exceeds the threshold value (ST6: NO), the control unit 40 determines that the horn 22 or the anvil 23 has become unsuitable for joining over time, and instructs to replace it with a new tool (ST8). The tool change instruction is not particularly limited as long as the operator can recognize it, and examples thereof include a monitor (display), a lamp display, and a sound notification.

(Function and effect)
Next, the function and effect according to this embodiment will be described. In the present embodiment, the configuration is such that the presence or absence of tool change is determined by comparing the peeling force when the horn 22 and the anvil 23 are peeled off from the workpiece after joining the workpieces with a predetermined threshold value. As described in the prior art, the present inventors have discovered a case where ultrasonic bonding is possible even when wear of a horn, anvil, or the like has progressed considerably.

  Therefore, it is determined that the tool should be replaced by using the peeling force when the horn 22 or the anvil 23 is separated from the work instead of the wear amount of the horn 22 or the anvil 23 as in the above-described conventional technique. Can be used.

  Further, in step ST1 of the flowchart of FIG. 7, a threshold for determining tool replacement can be obtained in advance in a separate experiment instead of a production line such as mass production. Thereby, the tool can be replaced before a defective product is generated in a production line such as mass production.

  In addition, this invention is not limited only to embodiment mentioned above, A various change is possible in a claim. FIG. 10 is a front view showing a joining device according to a modification of the present invention. FIG. 11 is a graph showing the relationship between time and load when the workpiece and the tool are separated from each other. In the case where the workpiece and the tool are moved toward and away from each other through the supply of the fluid, the pressure fluctuation of the fluid to be supplied is taken into consideration. 6 is a graph obtained by correcting data for determining tool replacement. In FIG. 10, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

  In the above description, the embodiment in which the mounting table 11 and the horn 22 constituting the transport unit 10 are moved using the servo motor has been described. However, the present invention is not limited to this. In addition to the above, for example, instead of the servo motor, the mounting table 11 and the horn 22 may be moved using air cylinders 12a and 24a as shown in FIG. In this case, fluid is supplied from the air cylinders 12a and 24a, and the mounting table 11 and the horn 22 are moved.

  When the mounting table 11 and the horn 22 are moved using the air cylinders 12a and 24a, as shown in FIG. 11, the pressure of the fluid supplied from the air cylinder is likely to fluctuate. It may be reflected. If the tool is changed using the change in the pressure applied by using the air cylinder as it is, the accuracy of the determination may be affected.

  Therefore, when pressurization is performed using a configuration such as an air cylinder, the pressure of the air cylinder 12a is detected by the pressure sensor 35 and the pressure of the air cylinder 24a is detected by the pressure sensor 34 as shown in FIG. The applied pressure is measured using the force sensors 31 and 32 as in the above embodiment. Then, as shown by a broken line c in FIG. 11, the tool change is determined using a solid line e obtained by subtracting the pressure fluctuation of the two-dot chain line d indicating the pressure of the air cylinder from the change in the applied pressure before correction. As a result, it is possible to prevent the pressure fluctuation of the air cylinder from being included in the fluctuation of the applied pressure, and it is possible to more appropriately determine whether or not to change the tool.

  Moreover, although embodiment which determines the replacement | exchange of the tool of the horn 22 and the anvil 23 using the peeling force at the time of peeling a tool from a workpiece | work was demonstrated above, it is not limited to this. In addition to the above, it may be configured to determine the replacement of the tool of only one of the horn 22 and the anvil 23 using the peeling force.

  In the above description, it has been described that data when a workpiece is deformed in an experiment or the like is acquired, and a threshold value is set therefrom. In addition to the above, an approximate curve indicating a change in the peeling load may be obtained using data acquired every time the workpiece is deformed, and the tool replacement time may be predicted using the approximate curve.

  In the above description, the embodiment in which the bonding method according to this embodiment is applied to a stacked secondary battery has been described. However, the present invention is not limited to this. In addition to the above, the present invention may be applied to, for example, a wound secondary battery. In the above description, the embodiment in which the bonding method according to the present embodiment is applied to the bonding between the current collector and the electrode tab in the secondary battery has been described. However, the present invention is not limited to this. In addition to the above, the secondary battery can be used, for example, for joining an electrode tab derived from a plurality of single cells and a bus bar. Moreover, you may utilize when joining electrode foil and a tab in a capacitor | condenser other than a secondary battery.

10 Conveying section,
11 mounting table,
12, 24 motor,
12a, 24a Air cylinder,
100 joining device,
20 joints,
21 Vibration generator,
22 horn (ultrasonic bonding tool),
23 Anvil (ultrasonic welding tool),
25 Spring,
30 measuring section,
31, 32 force sensor,
33 position sensor,
34, 35 Pressure sensor,
40 Control unit.

Claims (4)

Determining whether to replace the ultrasonic bonding tool in consideration of repeated use of the ultrasonic bonding tool, in the case where a bonding portion is formed on a material to be bonded including a plurality of members using the ultrasonic bonding tool A method,
A threshold is set in advance for the peeling force when the ultrasonic bonding tool is peeled off from the material to be bonded after the formation of the bonded portion,
The ultrasonic bonding tool is brought into contact with the one material to be bonded to form the bonding portion,
Measure the peeling force when peeling the ultrasonic welding tool from the one material to be joined,
The determination method of determining replacement | exchange of the said ultrasonic joining tool by comparing the said peeling force and the said threshold value.   The said peeling force is correct | amended in consideration of the fluctuation | variation part of the supply pressure of the said fluid, when the position of the said ultrasonic welding tool and the said to-be-joined material is adjusted by supply of the pressure of the fluid. Judgment method.   The determination method according to claim 1, wherein the ultrasonic welding tool is at least one of a horn and an anvil. Forming a joining portion in a material to be joined including a plurality of members using an ultrasonic joining tool, and a joining portion in which the ultrasonic joining tool is replaced by repeated use of the ultrasonic joining tool;
A measurement unit for measuring a peeling force when the ultrasonic tool is peeled off from the material to be joined after the formation of the joining portion;
And a controller that stores in advance a threshold value for the peeling force and compares the peeling force with the threshold value to determine replacement of the ultrasonic welding tool.