JP2000221016A - Weld inspection method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the reliability of a battery by enabling nondestructive inspection without pulling a welded part. In a welding inspection apparatus (100) for inspecting a welding state between a positive electrode lead (22) and a sealing unit (26), a battery (1) is provided.
0, a holding mechanism 112 for holding the sealing unit 26 to which the positive electrode lead 22 is welded,
An inspection unit 114 that reads an image of the nugget 104 formed on the welded portion 102 by welding the positive electrode lead 22 and the sealing unit 26, and inspects the state of formation of the nugget 104 based on the read image; Sorting unit 1 that sorts out good or bad products based on the inspection results of
16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for superposing one principal surface of a first member to be welded and one principal surface of a second member to be welded,
The present invention relates to a welding inspection method when irradiating a laser beam toward the other main surface of the first member to be welded to weld the first and second members to be welded, and particularly to a battery having a bottomed cylindrical shape. The present invention relates to a welding inspection method for inspecting a welding state between a lead extending from a winding group and a sealing body in a battery configured by winding a winding group together with an electrolytic solution in a can.

[0002]

2. Description of the Related Art For example, a lithium battery comprises a winding group in which a positive electrode plate and a negative electrode plate provided with current collecting leads (a positive electrode lead and a negative electrode lead) are wound with a separator interposed therebetween. The battery is inserted into the battery can.

[0003] In the case of manufacturing the above-mentioned lithium battery, usually, a winding group in which a positive electrode plate and a negative electrode plate are wound through a separator is produced, and then this winding group is formed into a cylindrical battery can with a bottom. Is inserted into.

[0004] Next, an annular groove is formed near the opening of the battery can, and after the negative electrode lead is spot-welded to the inner bottom of the battery can, an electrolyte is injected. Further, a sealing plate is welded to the positive electrode lead, and various sealing components including a safety valve (PTC ring) are inserted into the battery can and subjected to sealing and caulking, thereby completing the above-described lithium battery.

[0005] When assembling a battery, it is necessary to weld the negative electrode lead and the battery can, and the positive electrode lead and the sealing body. Conventionally, welding strength has been checked by a destructive inspection by sampling as an off-line inspection and a 100% check by pulling on an on-line inspection. Since 100% inspection cannot be performed for offline inspection, online 100% inspection is attracting attention.

In the on-line inspection, the welded portion is pulled with a minimum necessary strength, and if it is broken, it is determined to be defective, and if it is not broken, it is determined to be good. Specifically, the displacement of the pulling head while the weld is being pulled is measured, and if the displacement is larger than a set value, it is determined to be defective.

[0007]

However, when performing a 100% inspection by pulling, even if the welding itself is good, internal short-circuiting due to deformation of the lead and the electrode plate due to pulling by strong force and deterioration of battery performance are caused. I am concerned.

The present invention has been made in view of such problems, and enables nondestructive inspection without pulling a welded portion, internal short circuit due to deformation of leads and electrode plates, and deterioration of battery performance. It is an object of the present invention to provide a welding inspection method that does not cause any welding.

[0009]

According to a welding inspection method of the present invention, one principal surface of a first member to be welded is overlapped with one principal surface of a second member to be welded, and the first member to be welded is overlapped. When irradiating the laser beam toward the other main surface of the member and welding the first and second members to be welded, an image of a nugget formed by the welding is read, and based on the read image, The method is characterized in that the state of formation of the nugget is inspected, and a non-defective or defective product is selected based on the inspection result.

As described above, the image of the nugget formed by welding is read, and the state of formation of the nugget is inspected based on the read image. Therefore, the inspection is performed non-destructively without pulling the welded portion. It does not cause internal short circuit or deterioration of battery performance due to deformation of leads and electrode plates. This leads to higher reliability of the battery.

Inspection of the state of formation of the nugget includes:
It may be inspected whether or not nuggets for a predetermined number of welding points have been formed. Further, it may be inspected whether or not a hole passing through the first welded member is formed in the nugget. These combinations may be used.

The presence or absence of the hole is determined by whether or not a flaw is formed on one main surface of the second member to be welded which is exposed from the hole as the hole is formed. Alternatively, the determination may be made based on whether or not the diameter of the nugget is equal to or larger than a predetermined diameter.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a welding inspection method according to the present invention will be described, for example, in a cylindrical secondary battery (hereinafter simply referred to as a battery) for inspecting a welding state between a lead extending from a winding group and a sealing body. An embodiment applied to the case (hereinafter simply referred to as a welding inspection method according to the embodiment) will be described with reference to FIGS.

Before describing the welding inspection method according to the present embodiment, first, a battery 10 to which the welding inspection method is applied is described.
1 and a method of manufacturing the battery 10 will be briefly described with reference to FIGS.

As shown in FIG. 1, the battery 10 includes a battery can 12 having a cylindrical shape with a bottom, and a winding group 14 sealed in the battery can 12 together with an electrolyte.

The winding group 14 is formed by winding a positive electrode plate 16 and a negative electrode plate 18 with a separator 20 interposed therebetween.
And a negative electrode lead 24 which is a metal lead is also provided at an end of the negative electrode plate 18.

The positive electrode lead 22 extends from the winding center side of the winding group 14 to the opening 12a side of the battery can 12, and
It is welded to the sealing unit 26. The sealing unit 26 includes various sealing components in a gasket 28, that is, a sealing plate 30 to be welded to the positive electrode lead 22, a breaker 32,
The TC ring 34 and the cap member 36 are integrally incorporated, and the sealing unit 26 is fixed to the end of the battery can 12 on the side of the opening 12a. At this time, the various sealing components are undercut, and maintain a laminated state.

The negative electrode lead 24 extends from the outer periphery of the winding group 14 to the inner bottom 12 b of the battery can 12, and
2b is spot-welded, for example.

An annular groove 38 is formed in the battery can 12 near the opening 12a. In the battery can 12, a lower insulating plate 40 and an upper insulating plate 42 are provided for the winding group 14.

Next, a method of manufacturing the battery 10 thus configured will be described with reference to FIG.

First, after a winding group 14 in which a positive electrode plate 16 and a negative electrode plate 18 are wound via a separator 20 is produced,
The negative electrode lead 24 of the negative electrode plate 18 is bent toward the center of the winding group 14 with the lower insulating plate 40 interposed therebetween (see (a) in FIG. 2).

The wound group 14 is inserted into the battery can 12, and an upper insulating plate 42 is disposed on the side of the opening 12a of the battery can 12 ((b), (c) in FIG. 2). reference).
At this time, the negative electrode lead 24 of the winding group 14 contacts the inner bottom portion 12b of the battery can 12, while the positive electrode lead 22 protrudes outward from the opening 12a of the battery can 12.

Next, the negative electrode lead 24 of the winding group 14 is spot-welded to the inner bottom 12b of the battery can 12,
After the annular groove 38 is formed in the vicinity of the opening 12a of the battery can 12, the electrolyte is injected into the battery can 12 through the electrolyte injection means 44 as shown in FIG. You. Further, as shown in FIG. 2E, the sealing unit 26 is welded to the positive electrode lead 22 of the winding group 14.

Here, as shown in FIG. 1, the sealing unit 26 has a gasket 28 in which a sealing plate 30, a breaker 32, a PTC ring 34, and a cap member 36, which are various sealing components, are laminated and integrally integrated. Have been.
Then, the positive electrode lead 22 is welded to the sealing plate 30 by, for example, laser welding.

The sealing unit constituting the sealing unit 26 includes at least a sealing plate 30 and a cap member 36 which are welded to the positive electrode lead 22, and includes a breaker 32 and a PTC ring 34, if necessary. Various sealing parts are incorporated.

After the positive electrode lead 22 is welded to the sealing unit 26, the positive electrode lead 22 is
The sealing unit 26 is disposed so as to be supported by an inner wall portion of the annular groove 38 of the battery can 12 ((f) in FIG. 2).
reference).

Next, the end of the battery can 12 on the side of the opening 12a is subjected to a sealing and caulking process, thereby producing a battery 10 as a product (see (g) and (h) in FIG. 2). .

The welding inspection method according to the present embodiment is performed using a welding inspection device 100 as shown in FIG.

Here, the quality of the welding condition is shown in FIGS.
This will be described with reference to FIG. 6B. First, FIGS. 5A and 5
As shown in B, when a normal nugget 104 is formed in the welded portion 102 by laser welding to the positive electrode lead 22 and the sealing unit 26, the positive electrode lead 22 and the sealing unit 26 are melted in the welded portion 102, and a good It becomes a welding state.

On the other hand, as shown in FIGS. 6A and 6B, when the center of the nugget 104 evaporates to form a hole 106 through the positive electrode lead 22 in the nugget 104,
A scratch 108 is formed on one principal surface of the sealing unit 26, and heat is not transmitted to the sealing unit 26, so that the diameter n of the nugget 104 is larger than the diameter do of the normal nugget 104.

The positive electrode lead 22 and the sealing unit 26
As a feature of laser welding, as long as a laser beam of a constant output is emitted from a laser oscillator used for laser welding, welding defects other than the formation of the hole 106 in the positive electrode lead 22 occur. I know from experience. In addition, emission of a laser beam having a constant output from the laser oscillator can be achieved by monitoring using an output monitor that performs feedback control of the laser oscillator.

As shown in FIG. 3, the welding inspection apparatus 100 according to the present embodiment includes a fixing mechanism 110 for fixing the battery 10 and a gripping mechanism 112 for gripping the sealing unit 26 to which the positive electrode lead 22 is welded. An inspection unit 114 that reads an image of the nugget 104 formed on the welded portion 102 by welding the positive electrode lead 22 and the sealing unit 26, and inspects the formation state of the nugget 104 based on the read image; And a selection unit 116 for selecting good or defective products based on the inspection result at 114.

The fixing mechanism 110 has a support arm 120 for supporting the battery 10 with its axis oriented in the vertical direction. The support arm 120 is horizontally and horizontally moved by a moving drive mechanism 122 controlled by a sorting unit 116. It is movable vertically. That is, the sorting unit 116 controls the movement driving mechanism 122 to transport the battery 10 determined as a non-defective product to a conveyor for transporting to the next process, and transports the battery 10 determined as a defective product to the collection box. The movement driving mechanism 122 is controlled as described above.

The gripping mechanism 112 includes a pair of holding members 130a and 130b for holding the sealing unit 26 in an upright state, and an air cylinder 132 for moving the holding members 130a and 130b in a direction away from a direction approaching each other. And A pair of holding members 130a and 1
30b, one holding member 130a has a shape following the upper shape of the sealing unit 26, and the other holding member 130b has a welding portion between the positive electrode lead 22 and the sealing unit 26, as shown in FIG. It has a notch 134 formed to correspond to 102.

The inspection unit 114 includes an imaging camera 140 that reads an image of the nugget 104 formed on the welded portion 102 by welding the positive electrode lead 22 and the sealing unit 26;
An illumination device 142 for illuminating the welding portion 102; a monitor 144 for displaying an image captured by the imaging camera 140; and image processing for processing the captured image to determine the quality of the battery in the inspection process. And an apparatus 146.

In the inspection of the welding state between the positive electrode lead 22 and the sealing unit 26, the imaging camera 14
At the same time, the image taken at 0 is displayed on the monitor 144, and at the same time, the formation state of the nugget 104 is automatically determined through the image processing device 146.

In particular, in the present embodiment, the imaging camera 14
The illumination device 142 is integrated with the illumination device 142. Specifically, the ring-shaped illumination device 1 surrounds the imaging camera 140.
42 is attached. Thereby, the illumination light L is incident on the welded portion 102 in an oblique direction.

When a normal nugget 104 is formed in the welded portion 102 by the above-described illumination, the nugget 10
Since the outline portion of the nugget 104 is reflected and the surface portion other than the outline of the nugget 104 is not reflected, the outline portion of the nugget 104 is clearly displayed on the screen of the monitor 144.

On the other hand, when the hole 106 is formed in the nugget 104, the outline of the nugget 104 and the flaw 108 formed on one main surface of the sealing unit 26 are both reflected,
Since the outline portion of the nugget 104 and the surface portion other than the scratches 108 are not reflected, the outline portion of the nugget 104 and the scratches 108 are clearly displayed on the screen of the monitor 144.

In order to clearly display the image of the outline of the nugget 104 and the image of the flaw 108 on the screen of the monitor 144, the incident angle θ of the illumination light L from the illumination device 142 to the welding portion 102 is set to 10 ° to 30 °. It is preferable to set to °. Of course, the imaging camera 1 is set so that the contour image of the nugget 104 is as large as possible on the screen.
Adjust the zoom of 40.

Here, the determination process in the image processing device 146 will be described with reference to the flowchart of FIG.
In step S <b> 1, image data relating to the nugget 104 is searched for among the image data captured by the image processing device 146.

Next, in step S2, the number of nuggets 104 is detected from the image data of the nuggets 104, and it is determined whether or not the nuggets 104 have been formed for a predetermined number of welding points. If the number of nuggets 104 is as specified, the process proceeds to the next step S3, and if the number is not enough, it is determined as a defective product.

In step S3, nugget 104
The diameter of the nugget 104 is calculated based on the image data. Then, in the next step S4, nugget 10
It is determined whether or not the diameter of No. 4 is within a specified range. If the diameter of the nugget 104 is within the specified range, the process proceeds to the next step S5, and if the diameter is not within the specified range, it is determined to be defective.

In step S5, nugget 104
It is determined whether or not the image data of the scratch 108 exists in the image data of. In order to detect the image data of the flaw 108, it is preferable that the image data taken into the image processing device 146 be binarized. Further, by binarizing the image data, the image data can be substantially compressed, and an increase in memory can be avoided.

In step S5, if there is no image data of the flaw 108, it is determined as a non-defective product, and if there is data of the flaw 108, it is determined as a defective product. Then, in the next step S6, the determination result in the image processing device 146 is output to the selection unit 116, and the determination processing in the image processing device 146 ends.

If the determination result from the image processing device 146 is a non-defective product, the sorting unit 116 controls the driving of the moving drive mechanism 122 to transport the battery 10 to a conveyor for transporting the battery 10 to the next step. If the determination result from 146 is a defective product determination, the drive of the movement drive mechanism 122 is controlled to transport the battery 10 to the collection box.

As described above, in the welding inspection method according to the present embodiment, the image of nugget 104 formed on welding portion 102 by welding is read, and the state of formation of nugget 104 is inspected based on the read image. As a result, it is possible to perform nondestructive inspection without pulling the welded portion 102, and there is no occurrence of internal short circuit or deterioration of battery performance due to deformation of the positive electrode lead 22, the positive electrode plate 16, and the like. This leads to higher reliability of the battery 10.

It should be noted that the welding inspection method according to the present invention is not limited to the above-described embodiment, but can adopt various configurations without departing from the gist of the present invention.

[0049]

As described above, according to the welding inspection method of the present invention, a non-destructive inspection can be performed without pulling a welded portion, and an internal short-circuit due to deformation of a lead or an electrode plate and a battery performance can be obtained. Does not cause deterioration of

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a battery to which a welding inspection method according to an embodiment is applied.

FIG. 2 is a process chart showing a method for manufacturing a battery.

FIG. 3 is a configuration diagram showing an example of a welding inspection device for realizing the welding inspection method according to the present embodiment.

FIG. 4 is a front view partially showing a state in which a sealing unit is held between a pair of holding members in a gripping mechanism.

FIG. 5A is a sectional view showing a state where a normal nugget is formed in a welded portion, and FIG. 5B is a front view thereof.

FIG. 6A is a cross-sectional view showing a state where a nugget having a hole in a weld is formed, and FIG. 6B is a front view thereof.

FIG. 7 is a flowchart illustrating a determination process in the image processing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Battery 16 ... Positive electrode plate 22 ... Positive electrode lead 26 ... Sealing unit 100 ... Welding inspection apparatus 102 ... Welding part 104 ... Nugget 106 ... Hole 108 ... Scratch 114 ... Inspection part 116 ... Sorting part 140 ... Shooting camera 142 ... Illumination device 144 … Monitor 146… Image processing device

Continued on the front page F-term (reference) 2F065 AA45 AA61 CC15 DD16 FF04 GG04 GG17 HH12 JJ03 JJ16 JJ26 LL06 QQ04 QQ24 SS02 SS13 TT03 4E068 AF02 BH01 CA17 CC02 DA09 5H011 AA09 AA12 CC06 DD13 EE04 AFF CC FB04 CB

Claims (5)

[Claims] 1. A main surface of a first member to be welded is overlapped with a main surface of a second member to be welded, and a laser beam is irradiated to another main surface of the first member to be welded. When the first and second members to be welded are welded, an image of the nugget formed by the welding is read, and a state of formation of the nugget is inspected based on the read image. A welding inspection method characterized by selecting good or defective products based on the inspection. 2. The welding inspection method according to claim 1, wherein the inspection of the formation state of the nuggets is performed by inspecting whether or not a predetermined number of nuggets are formed. Method. 3. The welding inspection method according to claim 1, wherein the inspection of the formation state of the nugget is performed to determine whether a hole that penetrates the first member to be welded is formed in the nugget. A welding inspection method characterized in that: 4. The welding inspection method according to claim 3, wherein the presence or absence of the hole is determined by the presence or absence of a flaw in one principal surface of the second welded member exposed from the hole as the hole is formed. A welding inspection method, characterized in that it is determined based on whether or not it is formed. 5. The welding inspection method according to claim 3, wherein the presence or absence of the hole is determined based on whether or not the diameter of the nugget is equal to or larger than a predetermined diameter.