JP2018122338A - Weld strength inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weld strength inspection method which can inspect the weld strength of a weld part by applying an inspection load thereto, and can properly inspect the weld part in which the weld strength is lowered due to the applied inspection load.SOLUTION: A weld strength inspection method for inspecting the weld strength of a weld part 27 in a creeping direction EH comprises: a load displacement amount measurement process S1 for fixing either of a first member 10 and a second member 23, pressing the other to the creeping direction EH, applying a preset inspection load Pc to the weld part 27, and measuring a load displacement amount ΔLa of the second member 23 with respect to the first member 10 which is generated in the creeping direction EH; and a residual displacement amount measurement process S3 for measuring a residual displacement amount ΔLb of the second member 23 with respect to the first member 10 in the creeping direction EH which remains even after the release of the inspection load Pc.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a weld strength inspection method for inspecting the weld strength of the welded portion of a structure in which the first joint surface of the first member and the second joint surface of the second member are joined via the welded portion. .

A structure having a welded portion in which two members are welded, for example, a battery module joined via a welded portion in a state where the terminal surface of the electrode terminal portion of the battery and the connecting surface of the conductive portion of the bus bar are opposed to each other is known. It has been. In manufacturing such a structure such as a battery module, it may be desired to inspect the weld strength of the welded portion of the two members. However, it is difficult to determine whether or not the necessary welding strength can be ensured without contacting the weld. For this reason, as a method for inspecting the welding strength, one of the two members (the first member and the second member) is fixed, the other is pressed, an inspection load is applied to the welded portion, It is conceivable to determine the welding strength of the welded portion based on the amount of displacement of the second member relative to one member.
In addition, patent document 1 is mentioned as a related prior art. Patent Document 1 discloses a technique for inspecting a welded portion where a wire and a terminal are welded in a state where both ends of the wire protrude beyond the terminal.

JP 2000-74787 A

  However, the welded portion may be damaged by the inspection load applied to the welded portion during the weld strength inspection, and the weld strength may be greatly reduced. Only by the above-described welding strength inspection method, it has been unavoidable that the welding strength greatly decreased due to the inspection load applied during such inspection.

  The present invention has been made in view of the current situation, and can inspect the welding strength of the welded portion between the first member and the second member by applying an inspection load to the welded portion, and an inspection applied during the inspection. It aims at providing the welding strength inspection method which can detect appropriately what the welding strength fell with the load.

  In one aspect of the present invention for solving the above-described problem, a first joint surface of a first member and a second joint surface facing the first joint surface of a second member are joined via a welded portion. A weld strength inspection method for inspecting a weld strength in a creeping direction along the first joint surface and the second joint surface of the welded portion of the structure, wherein either the first member or the second member One is fixed and the other is pressed in the creeping direction, a predetermined inspection load is applied to the welded portion, and a load displacement amount ΔLa of the second member relative to the first member generated in the creeping direction is measured. Weld strength inspection comprising: a load displacement amount measurement step; and a residual displacement amount measurement step of measuring a residual displacement amount ΔLb of the second member with respect to the first member in the creeping direction remaining after the inspection load is released. Is the method.

In the welding strength inspection method described above, an inspection load is applied to the welded portion between the first member and the second member, and the load displacement amount ΔLa of the second member relative to the first member is measured. Based on this, it can be determined whether or not the welded part has the required welding strength.
In addition, in this welding strength inspection method, the residual displacement amount ΔLb of the second member relative to the first member remaining even after the inspection load is released is measured. If the welded part is greatly damaged due to the inspection load applied to the welded part at the time of inspection and the welding strength is greatly reduced, the value of the residual displacement amount ΔLb becomes large. For this reason, it is possible to appropriately detect a case where the welding strength has been reduced by the inspection load applied at the time of inspection based on the magnitude of the residual displacement amount ΔLb.

It is a partial top view of the battery module which concerns on embodiment. It is an AA fragmentary sectional view in Drawing 1 of a battery module concerning an embodiment. It is a flowchart of the welding strength inspection method which concerns on embodiment. It is explanatory drawing which concerns on embodiment and shows a weld strength test | inspection. It is a graph which shows the relationship between inspection time T of welding strength inspection, load P, and displacement amount (DELTA) L according to embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 and FIG. 2 show a partial top view and a partial cross-sectional view of a battery module 1 that is a structure that is a target of a welding strength inspection in the present embodiment. In the cylindrical battery 10 of FIG. 2, illustration of an electrode body and the like housed in the battery is omitted, and only a cross section of the battery case 11 and the like is shown. 1 and 2, the horizontal direction CH of the battery module 1, the vertical direction in FIG. 1 is the vertical direction DH of the battery module 1, and the vertical direction in FIG. 2 is the height direction GH of the battery module 1. Will be described.

  The battery module 1 is an in-vehicle battery module mounted on a vehicle such as a hybrid car, a plug-in hybrid car, or an electric vehicle. The battery module 1 is formed by connecting a plurality of cylindrical batteries 10 in parallel. In addition to the cylindrical batteries 10, a positive electrode bus bar 20 that connects positive terminal portions (electrode terminal portions) 15 of the cylindrical batteries 10 to each other. , A negative electrode bus bar (not shown) for connecting negative electrode terminal portions (not shown) of the cylindrical battery 10, a battery holding member (not shown) for holding a plurality of cylindrical batteries 10, and the like.

  Each of the cylindrical batteries 10 is a cylindrical (columnar) and sealed lithium ion secondary battery (specifically, 18650 type lithium ion secondary battery). This cylindrical battery 10 includes an electrode body (not shown) in which a belt-like positive electrode plate and a belt-like negative electrode plate are overlapped with each other via a pair of belt-like separators inside a cylindrical battery case 11 and wound into a cylindrical shape. ) Together with a non-aqueous electrolyte (not shown). In each cylindrical battery 10, the positive electrode terminal portion 15 is above the height direction GH (upward in FIG. 2), and the negative electrode terminal portion (not shown) is below the height direction GH (FIG. 2). They are arranged in parallel with each other and at the same height.

  At one end (upward in FIG. 2) of the cylindrical battery 10 in the axial direction, a convex positive electrode terminal portion 15 that is electrically connected to the positive electrode plate of the electrode body is provided inside the battery. The positive electrode terminal portion 15 is fixed to the battery case 11 while being insulated from the battery case 11 via an annular insulating member 17. A terminal surface 15m of each positive electrode terminal portion 15 is in contact with a lower surface 23m of a bus bar conduction portion 23 of the positive electrode bus bar 20 described later, whereby the positive electrode terminal portions 15 are electrically connected to each other via the positive electrode bus bar 20. Yes.

  The positive electrode bus bar 20 is formed by press punching and bending a metal plate material, and a plate-like bus bar main body that covers each cylindrical battery 10 from the positive electrode terminal portion 15 side (above the height direction GH). 21. A plurality of through holes 21 h are formed in the bus bar main body 21. When the positive electrode bus bar 20 is viewed from above in the height direction GH (see FIG. 1), the positive electrode terminal portion 15 of each cylindrical battery 10 is exposed in each through hole 21h. In addition, in each through hole 21h, a bus bar conduction portion 23 and an arm portion 25 that are connected to the positive electrode terminal portion 15 are provided.

  Specifically, the arm portion 25 extends obliquely downward inward in the radial direction from the periphery of each through hole 21 h in the bus bar main body portion 21, and the bus bar conduction portion 23 is provided at the tip of the arm portion 25. . The bus bar conduction portion 23 has a rectangular shape in plan view, and has a center portion 23c protruding downward in the height direction GH. A lower surface 23 m of the central portion 23 c is joined to a terminal surface 15 m of the positive electrode terminal portion 15 of the cylindrical battery 10 via a welded portion 27. Specifically, a welded portion between the bus bar conductive portion 23 and the positive electrode terminal portion 15 (on the central portion of the contact portion between the lower surface 23 m of the central portion 23 c of the bus bar conductive portion 23 and the terminal surface 15 m of the positive electrode terminal portion 15 ( A weld nugget) 27 is formed.

  In this embodiment, the cylindrical battery 10 corresponds to the “first member” described above, and the terminal surface 15 m of the positive electrode terminal portion 15 of the cylindrical battery 10 corresponds to the “first bonding surface” described above. In addition, the bus bar conductive portion 23 of the positive bus bar 20 corresponds to the “second member” described above, and the lower surface 23 m of the bus bar conductive portion 23 corresponds to the “second joint surface” described above. In addition, the above-mentioned “creepage” in which the direction (including the horizontal direction CH and the vertical direction DH) EH perpendicular to the height direction GH is along the terminal surface (first bonding surface) 15 m and the bonding surface (second bonding surface) 23 m. Direction "(see FIG. 2).

  On the other hand, the bottom surface of the battery case 11 located at the other end in the axial direction of the cylindrical battery 10 (upward in FIG. 2) is a disc-shaped negative electrode terminal portion (not shown) that conducts with the negative electrode plate of the electrode body inside the battery. (Illustrated). Each negative electrode terminal portion is connected to a negative electrode bus bar (not shown), whereby the negative electrode terminal portions are electrically connected to each other via the negative electrode bus bar.

  Next, a welding strength inspection method for inspecting the welding strength in the creeping direction EH of each welded portion 27 in the battery module 1 will be described (see FIGS. 3 to 5). First, a welding strength inspection apparatus 100 for inspecting the welding strength will be described (see FIG. 4). The welding strength inspection apparatus 100 includes a fixing jig (not shown) that fixes the battery module 1 in a predetermined position, a load applying unit 110 that applies a load P (N) to the welded portion 27 in the creeping direction EH, and the load A load measuring unit 120 that measures the size of P and a displacement amount measuring unit 130 that measures a displacement amount ΔL (μm) in the creeping direction EH of the bus bar conducting portion 23 relative to the cylindrical battery 10 are provided.

Of these, the load applying means 110 abuts on the bus bar conducting portion 23 and presses the bus bar conducting portion 23 in the creeping direction EH (specifically, one side CH1 in the lateral direction CH), a servo motor, and the like. And a moving device 113 configured to be able to move the pressing member 111 in the creeping direction EH (specifically, the horizontal direction CH).
The load measuring means 120 is a plate-shaped load cell capable of detecting a load applied in the thickness direction in the present embodiment, and is disposed between the pressing member 111 of the load applying means 110 and the moving device 113. Thereby, when the pressing member 111 presses the bus bar conducting portion 23, the load P applied to the welded portion 27 can be measured.
Further, the displacement measuring means 130 has a laser displacement meter arranged so as to be able to measure the position in the creeping direction EH (lateral direction CH) of the pressing member 111 of the load applying means 110.

Next, a welding strength inspection method using the above-described welding strength inspection apparatus 100 will be described. First, the battery module 1 is placed on a fixing jig (not shown), and each cylindrical battery 10 constituting the battery module 1 is fixed to the fixing jig.
Then, in the load displacement amount measuring step S1, the bus bar conducting portion 23 is pressed in the creeping direction EH (one side CH1 in the lateral direction CH), and a predetermined inspection load Pc is applied to the welded portion 27 (Pc = 70N in this embodiment). Is applied, and the load displacement amount ΔLa (μm) of the bus bar conduction portion 23 with respect to the cylindrical battery 10 generated in the creeping direction EH (lateral direction CH) is measured.

Specifically, the pressing member 111 is moved in the creeping direction EH (one side CH1 in the lateral direction CH) by the moving device 113 of the load applying means 110, and the pressing member 111 is moved to the bus bar conduction portion 23 as shown in FIG. Make contact. In FIG. 5, the pressing member 111 contacts the bus bar conduction portion 23 at the inspection time T1 (T1 = 0.30 sec in this embodiment).
Further, the pressing member 111 is moved by the moving device 113 in the creeping direction EH (one side CH1 of the lateral direction CH) until the load P measured by the load measuring means 120 becomes the inspection load Pc. The conduction portion 23 is pressed in the creeping direction EH (one side CH1 in the lateral direction CH). As shown in FIG. 5, the load P measured by the load measuring means 120 gradually increases, and the load P reaches the inspection load Pc at the inspection time T2 (T2 = 0.35 sec in this embodiment). At this time, the inspection load Pc is applied to the welded portion 27 in the creeping direction EH (lateral direction CH).

  Thereafter, the state in which the inspection load Pc is applied to the welded portion 27 is maintained from the inspection time T2 to the inspection time T3 (T3 = 0.90 sec in the present embodiment). Then, by the displacement measuring means 130, the position L1 in the creeping direction EH (lateral direction CH) of the pressing member 111 at the inspection time T1, and the position L2 in the creeping direction EH (lateral direction CH) of the pressing member 111 at the inspection time T3. From this, the load displacement amount ΔLa = L1−L2 in the creeping direction EH of the bus bar conduction portion 23 with respect to the cylindrical battery 10 is obtained.

  Thereafter, in the load displacement amount determination step S2, it is determined whether or not the welded portion 27 has a required welding strength based on the magnitude of the load displacement amount ΔLa obtained in the load displacement amount measurement step S1. . Specifically, the obtained load displacement amount ΔLa is compared with a predetermined reference load displacement amount ΔLr. When the load displacement amount ΔLa is equal to or less than the reference load displacement amount ΔLr (ΔLa ≦ ΔLr), the welded portion 27 is It is determined that the necessary welding strength can be secured. FIG. 5 shows an example of a solid line (good) and a two-dot chain line (defect 2) among three examples in which the displacement ΔL is indicated by a solid line (good), a one-dot chain line (defect 1), and a two-dot chain line (defect 2). Then, since the load displacement amount ΔLa is equal to or less than the reference load displacement amount ΔLr, in these examples, it is determined that the welded portion 27 can secure the necessary welding strength.

  On the other hand, when the load displacement amount ΔLa is larger than the reference load displacement amount ΔLr (ΔLa> ΔLr), it is determined that the welding strength of the welded portion 27 is insufficient. Among the above three examples shown in FIG. 5, in the example of the alternate long and short dash line (defect 1), the load displacement amount ΔLa is larger than the reference load displacement amount ΔLr. Determined to be sufficient. In the example of the alternate long and short dash line (defect 1), the weld strength of the welded portion 27 was too low. Therefore, when the inspection load Pc was applied, the welded portion 27 was greatly plastically deformed beyond the elastic deformation range. For this reason, it is considered that the load displacement amount ΔLa has increased.

  Next, in the residual displacement measurement step S3, the pressing member 111 is moved to the opposite side of the creeping direction EH by the moving device 113 (the other side CH2 of the lateral direction CH) by the load measuring means 120. The load P applied to the welded portion 27 is gradually reduced until the load P to be measured becomes the load P = 0. In FIG. 5, the load P = 0 at the inspection time T4 (T4 = 1.00 sec in this embodiment). Then, a residual displacement amount ΔLb (μm) of the bus bar conducting portion 23 with respect to the cylindrical battery 10 in the creeping direction EH (lateral direction CH) remaining after the release of the load P (inspection load Pc) is measured. Specifically, the displacement measuring means 130 measures the position L3 in the creeping direction EH (lateral direction CH) of the pressing member 111 at the inspection time T4 when the load P = 0 applied to the welded portion 27, and this position L3. From the position L1 in the creeping direction EH (lateral direction CH) of the pressing member 111 at the above-described inspection time T1, the residual displacement amount ΔLb = L1-L3 in the creeping direction EH of the bus bar conducting portion 23 with respect to the cylindrical battery 10 is obtained. .

  Thereafter, in the residual displacement determination step S4, the welding strength of the welded portion 27 is not reduced by the inspection load Pc applied during the inspection based on the magnitude of the residual displacement ΔLb obtained in the residual displacement measurement step S3. Determine whether. Specifically, the obtained residual displacement amount ΔLb is compared with a predetermined reference residual displacement amount ΔLs, and when the residual displacement amount ΔLb is equal to or smaller than the reference residual displacement amount ΔLs (ΔLb ≦ ΔLs), the inspection load Pc It determines with the welding strength of the welding part 27 not falling by application.

  Of the above-described three examples shown in FIG. 5, in the solid line (good) example, the residual displacement amount ΔLb is equal to or less than the reference residual displacement amount ΔLs. It is determined that the welding strength has not decreased. In the example of the solid line (good), the weld strength of the welded portion 27 is sufficiently high, so that the inspection load Pc is applied mainly within the range of the elastic deformation of the welded portion 27. For this reason, after the inspection load Pc is released, the welded portion 27 has almost returned to its original shape due to elastic deformation, and it is considered that the residual displacement amount ΔLb has become smaller.

On the other hand, when the residual displacement amount ΔLb is larger than the reference residual displacement amount ΔLs (ΔLb> ΔLs), it is determined that the welding strength of the welded portion 27 is reduced.
Among the above-described three examples shown in FIG. 5, in the examples of the one-dot chain line (defect 1) and the two-dot chain line (defect 2), the residual displacement amount ΔLb is larger than the reference residual displacement amount ΔLs. It is determined that the welding strength of the welded portion 27 is reduced.
In the example of the alternate long and short dash line (defect 1), as described above, the weld strength of the welded portion 27 is too low, so that when the inspection load Pc is applied, the welded portion 27 is greatly plasticized beyond the elastic deformation range. Deformed. For this reason, it is considered that the residual displacement amount ΔLb after the inspection load Pc is released is also increased.

  Further, in the example of the two-dot chain line (defect 2), the weld strength of the welded portion 27 is larger than that in the example of the one-dot chain line (defect 1). However, the amount of plastic deformation was small. For this reason, as described above, the load displacement amount ΔLa is equal to or less than the reference load displacement amount ΔLr. However, since the plastic deformation occurred, the weld strength of the welded portion 27 was reduced by the inspection. In this example, since the residual displacement amount ΔLb caused by the plastic deformation is larger than the reference residual displacement amount ΔLs, it can be determined that the welding strength of the welded portion 27 has decreased due to the application of the inspection load Pc in the residual displacement amount determination step S4. .

  Next, in the undetermined weld portion determination step S5, among the plurality of weld portions 27 included in the battery module 1, the above-described load displacement amount measurement step S1, load displacement amount determination step S2, residual displacement amount measurement step S3, and residual It is determined whether there is an undetermined welded portion 27 that has not been subjected to the displacement amount determining step S4. Here, when YES, that is, when the undetermined welded portion 27 not subjected to the load displacement measuring step S1 to the residual displacement determining step S4 remains, the load is similarly applied to the welded portion 27 as well. A displacement amount measurement step S1 to a residual displacement amount determination step S4 are performed. On the other hand, NO, that is, when there is no undetermined welded portion 27 that has not been subjected to the load displacement measuring step S1 to the residual displacement determining step S4 (the load displacement measuring step S1 to the residual displacement for all the welded portions 27). When the quantity determination step S4 is completed), the process proceeds to a defective product removal step S6.

  Next, in the defective product removal step S6, for all the welded portions 27 included in the battery module 1, the battery that is determined to be good in the load displacement amount determination step S2 and that is also determined to be good in the residual displacement amount determination step S4. Only the module 1 is a good battery module 1 and the other battery modules 1 are removed as defective products.

As described above, in the welding strength inspection method, the inspection load Pc is applied to the welded portion 27 between the cylindrical battery 10 and the bus bar conductive portion 23, and the load displacement amount ΔLa of the bus bar conductive portion 23 with respect to the cylindrical battery 10 is set. Since the measurement is performed, it can be determined whether or not the welding portion 27 has a required welding strength based on the magnitude of the load displacement amount ΔLa.
In addition, in this welding strength inspection method, the residual displacement amount ΔLb of the bus bar conduction portion 23 with respect to the cylindrical battery 10 remaining after the inspection load Pc is released is measured. If the welded portion 27 is greatly damaged by the inspection load Pc applied to the welded portion 27 during the inspection and the welding strength is greatly reduced, the value of the residual displacement amount ΔLb increases. For this reason, it is possible to appropriately detect a case where the welding strength is reduced by the inspection load Pc applied at the time of inspection based on the magnitude of the residual displacement amount ΔLb.

In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the embodiment, the present invention is exemplified when the welding strength of the welded portion 27 between the positive terminal portion 15 of the cylindrical battery 10 and the bus bar conductive portion 23 of the positive bus bar 20 is inspected. Not limited to. The present invention can also be applied when inspecting the welding strength of the welded portion between the negative electrode terminal portion of the cylindrical battery 10 and the bus bar conduction portion of the negative electrode bus bar.

  In the embodiment, in the load displacement amount measurement step S1, the inspection load Pc is continuously applied to the welded portion 27 from the inspection time T2 to the inspection time T3. However, the present invention is not limited to this. For example, after the inspection load Pc is applied to the welded portion 27, the load P applied to the welded portion 27 may be reduced immediately without waiting for a predetermined time to elapse. Even when the load displacement amount ΔLa is measured in this way, it is possible to determine whether or not the welded portion 27 can ensure the required welding strength in the load displacement amount determination step S2. Furthermore, based on the residual displacement amount ΔLb obtained in the residual displacement amount measurement step S3, it can be determined in the residual displacement amount determination step S4 whether the weld strength of the welded portion 27 is reduced by the inspection load Pc.

1 Battery module (structure)
10 Cylindrical battery (first member)
15 Positive terminal (electrode terminal)
15m terminal surface (first joint surface)
20 Positive bus bar 21 Bus bar body 23 Bus bar conduction part (second member)
23m bottom surface (second joint surface)
27 Welded part 110 Load applying means 120 Load measuring means 130 Displacement measuring means EH Creeping direction P Load Pc Inspection load ΔL Displacement amount ΔLa Load displacement amount ΔLr Reference load displacement amount ΔLb Residual displacement amount ΔLs Reference residual displacement amount S1 Measurement of load displacement amount Step S2 Load displacement amount determination step S3 Residual displacement amount measurement step S4 Residual displacement amount determination step S5 Undetermined welded portion determination step S6 Defective product removal step

Claims (1)

Of the structure in which the first joint surface of the first member and the second joint surface facing the first joint surface of the second member are joined via the welded portion, the first joint surface of the welded portion. And a weld strength inspection method for inspecting the weld strength in the creeping direction along the second joint surface,
One of the first member and the second member is fixed, the other is pressed in the creeping direction, a predetermined inspection load is applied to the welded portion, and the first member generated in the creeping direction is applied. A load displacement amount measuring step for measuring the load displacement amount ΔLa of the second member;
A residual displacement measuring step for measuring a residual displacement amount ΔLb of the second member with respect to the first member in the creeping direction remaining even after the inspection load is released.

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