Method for manufacturing flexible bus bar

Abstract

Provided is a method for manufacturing a flexible bus bar, the method making it possible to prevent displacement of laminated electroconductive material foils. A plurality of electroconductive material foils B1 are laminated. When the plurality of electroconductive material foils B1 are laminated, dowel caulking parts B2 are formed on the left-side-surface B1a side and the right-side-surface B1b side of the electroconductive material foils B1. Furthermore, the left-side-surface B1a side and the right-side-surface B1b side of the electroconductive material foil B1 on which the dowel caulking part B2 is formed are thermocompression-bonded. This makes it possible to prevent displacement of the laminated electroconductive material foils B1.

Description

Method for manufacturing flexible bus bar

[0001] The present invention relates to a method for manufacturing a flexible bus bar.

[0002] In general, it is known to use flexible bus bars for connecting members that can conduct electricity (for example, batteries mounted on electric vehicles, hybrid vehicles, and the like). As such a flexible bus bar, for example, one described in Patent Document 1 is known.

[0003] Japanese Unexamined Patent Application Publication No. 2008-41330

[0004] By the way, the flexible bus bar as described above is manufactured by processing a conductive material foil made of a thin plate-shaped flexible metal such as copper, then laminating the foils, and fixing required portions (for example, both side portions) thereof.

[0005] However, there has been a problem that misalignment may occur in the laminated conductive material foils when proceeding to the step of fixing the required portions (for example, both side portions).

[0006] In view of the above problem, an object of the present invention is to provide a method for manufacturing a flexible bus bar that can prevent misalignment of laminated conductive material foils.

[0007] The above object of the present invention is achieved by the following means. Note that reference numerals of the embodiments described later are given in parentheses, but the present invention is not limited thereto.

[0008] A method for manufacturing a flexible bus bar according to claim 1 includes a step (see FIG. 1(a)) of laminating a plurality of conductive materials (conductive material foils B1), and when laminating the plurality of conductive materials (conductive material foils B1), a step of performing dowel caulking on a part of the conductive materials (for example, the left side surface B1a side and the right side surface B1b side of the conductive material foil B1), or on sprues / runners (B6) provided on the conductive materials (conductive material foils B1) when laminating the plurality of conductive materials (conductive material foils B1) (see FIG. 1(b), FIG. 8(a)(c), and FIG. 9), and a step of thermocompression bonding the side portions of the plurality of conductive materials that have been subjected to the dowel caulking.

[0009] The method for manufacturing a flexible busbar according to claim 2 is characterized in that, in the method for manufacturing a flexible busbar according to claim 1, it further comprises the steps of: arranging a plurality of conductive materials (conductive material foil B1) that have been dowel-crimped in a predetermined box (2) (see Figure 4(c)); degassing the oxygen in the predetermined box (2) and filling it with an inert gas; and heat-pressing the sides of the plurality of conductive materials (conductive material foil B1) that have been dowel-crimped in an environment of the inert gas.

[0010] The method for manufacturing a flexible busbar according to claim 3 is characterized in that, in the method for manufacturing a flexible busbar according to claim 2, when arranging a plurality of conductive materials (conductive material foil B1) that have been dowel-crimped in a predetermined box (2), the plurality of conductive materials that have been dowel-crimped are held by being sandwiched between insulating materials (first insulating material 41, second insulating material 42), except for the sides of the plurality of conductive materials (conductive material foil B1) that have been dowel-crimped (left side B1a and right side B1b of the conductive material foil B1).

[0011] The method for manufacturing a flexible busbar according to claim 4 is characterized in that, in the method for manufacturing a flexible busbar according to claim 2 or 3, the sides (left side B1a and right side B1b of the conductive material foil B1) of the multiple conductive materials (conductive material foil B1) that have been dowel-crimped are heat-pressed together in an inert gas environment, a cooling period is provided, and then the multiple conductive materials (conductive material foil B1) that have been dowel-crimped are removed from the predetermined box (2).

[0012] The method for manufacturing a flexible busbar according to claim 5 is characterized in that, in the method for manufacturing a flexible busbar according to claim 2 or 3, when thermally bonding the sides (left side B1a and right side B1b of the conductive material foil B1) of a plurality of conductive materials (conductive material foil B1) that have been crimped together in an inert gas environment, the thermal bonding is performed by resistance heating, and in this case, the resistance heating is performed by passing a first current for a first period, and then the resistance heating is performed by passing a second current which is higher than the first current for a second period (see Figure 7).

[0013] Next, the effects of the present invention will be described with reference to the reference numerals in the drawings. Note that the reference numerals in parentheses are those of embodiments described later, but the present invention is not limited thereto.

[0014] According to the invention of claim 1, when laminating multiple conductive materials (conductive material foil B1), dowel crimping is performed on a part of the conductive material (for example, the left side B1a side and the right side B1b side of the conductive material foil B1), or on the spool / runner (B6) provided on the conductive material (conductive material foil B1) when laminating multiple conductive materials (conductive material foil B1). As a result, the positions of the multiple conductive material foils (B1) are fixed, so that when moving on to the process of fixing the necessary parts (the process of forming the left fixing part (B3) and the right fixing part (B4)), misalignment of the laminated conductive material foils (B1) can be prevented.

[0015] Therefore, according to the present invention, it is possible to prevent misalignment of the laminated conductive material foil (B1).

[0016] According to the invention of claim 2, oxygen is removed from a predetermined box (2) and filled with an inert gas, and the sides (left side B1a and right side B1b of the conductive material foil B1) of a plurality of conductive materials (conductive material foil B1) that have been crimped are heat-pressed together in an inert gas environment, so that oxidation does not occur as in the conventional method. As a result, the work of polishing the oxidized parts as in the conventional method is not required, and quality can be improved without increasing the number of work steps.

[0017] According to the invention of claim 3, by sandwiching and holding a plurality of conductive materials (conductive material foil B1) that have been crimped together with insulating materials (first insulating material 41, second insulating material 42), the risk of leakage current through the plurality of conductive materials (conductive material foil B1) that have been crimped together can be prevented, and the plurality of conductive materials (conductive material foil B1) that have been crimped together can be prevented from bending due to high-temperature heating.

[0018] According to the invention of claim 4, by providing a cooling period, it is possible to prevent the multiple conductive materials (conductive material foil B1) that have been riveted after heat compression from coming into contact with oxygen in the atmosphere and oxidizing.

[0019] According to the invention of claim 5, sparking can be reduced by performing resistance heating in multiple stages.

[0020] (a) is an explanatory diagram illustrating the state in which conductive material foils are laminated, (b) is a partially enlarged vertical cross-sectional view of the dowel crimping portion, and (c) is a perspective view showing the laminated conductive material foil with the dowel crimping portion formed. This is a perspective view of a manufacturing apparatus used in the manufacturing method of a flexible busbar according to the same embodiment. (a) is a perspective view of a mounting base placed inside the manufacturing apparatus according to the same embodiment, (b) is a perspective view showing the state in which the first holding base is attached and fixed to the upper surface of the mounting base shown in (a), and (c) is a perspective view showing the state in which the first insulating material is placed on the upper surface of the first holding base shown in (b). (a) is a perspective view showing the state in which the flexible busbar is placed on the upper surface of the first insulating material shown in Figure 3(c), (b) is a perspective view showing the state in which the second insulating material is placed on the upper surface of the flexible busbar shown in (a), and (c) is a perspective view showing the state in which the second holding base is placed on the upper surface of the second insulating material shown in (b) and attached and fixed to the first holding base. This is a side view of a flexible busbar. This is a photograph showing the oxidation of the surface of the flexible busbar in response to changes in oxygen concentration. This is a graph illustrating the two-stage resistance heating process. (a) is a perspective view showing a conductive material foil laminated with a dowel crimp section formed, (b) is a perspective view showing the state in (a) with the left and right bolt holes formed, and (c) is a perspective view showing an example of a conductive material foil laminated with a dowel crimp section formed on a non-fixed portion. This is a plan view showing an example of a conductive material foil laminated with a dowel crimp section formed on a spool / runner.

[0021] A method for manufacturing a flexible busbar according to one embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, when the directions of up, down, left, and right are indicated, they refer to the up, down, left, and right directions as viewed from the front as shown in the drawings.

[0022] <Outline of the manufacturing method for flexible busbars> The manufacturing method for flexible busbars according to this embodiment can prevent misalignment of the laminated conductive material foils. A detailed explanation follows below.

[0023] <Explanation of the manufacturing method of a flexible busbar> In manufacturing the flexible busbar B shown in Figure 5, first, as shown in Figure 1(a), a conductive material foil B1 made of a thin, flexible metal such as copper is cut into a predetermined shape (a straight shape in the illustration) and then laminated. At this time, dowel crimping is performed on the left side B1a and the right side B1b of the conductive material foil B1 shown in Figure 1(a). Specifically, as shown in Figure 1(b), crimping protrusions B1c are formed on the conductive material foil B1 by press molding. Then, as shown in Figure 1(b), by fitting these crimping protrusions B1c together, the multiple conductive material foils B1 are connected in the lamination direction. As a result, as shown in Figure 1(c), dowel crimping portions B2 are formed on the left side B1a and the right side B1b of the laminated conductive material foil B1. Note that dowel crimping itself is a conventionally known method.

[0024] Next, the conductive material foil B1, which has been laminated with the dowel crimp portion B2 formed, is fixed on the left side to form the left fixed portion B3, and fixed on the right side to form the right fixed portion B4, as shown in Figure 5. This is because these portions become fastening portions that connect electrically conductive members (for example, batteries installed in electric vehicles and hybrid cars). Therefore, the left fixed portion B3 and the right fixed portion B4 described above are formed. Accordingly, the manufacturing apparatus 1 shown in Figure 2 is used to form these left fixed portion B3 and right fixed portion B4.

[0025] <Description of Manufacturing Equipment> Next, we will explain manufacturing equipment 1 in detail.

[0026] As shown in Figure 2, the manufacturing apparatus 1 includes a box 2 that is rectangular in shape. In this embodiment, the box 2 is semi-transparent, allowing the inside to be seen from the outside.

[0027] Thus, as shown in Figure 2, such a box 2 has inlets 20 at the four corners of its top surface 2a. From these inlets 20, an inert gas (for example, nitrogen gas) can be injected into the box 2 from the direction of arrow Y1 shown in Figure 2.

[0028] On the other hand, as shown in Figure 2, an outlet 21 is provided in the center of the left side 2b of the box 2, slightly below the center. This outlet 21 is designed to discharge the air (including oxygen) filling the box 2 in the direction of arrow Y2 when an inert gas (for example, nitrogen gas) is injected into the box 2 from the direction of arrow Y1 shown in Figure 2. At this time, in order to measure the oxygen concentration inside the box 2 with an oxygen concentration meter (not shown), a connection port 22 for connecting an oxygen concentration meter (not shown) is provided in the center of the right side 2d of the bottom surface 2c of the box 2, as shown in Figure 2.

[0029] On the other hand, as shown in Figure 2, a roughly T-shaped first energizing section 23 is provided at the center of the left side 2b of the upper surface 2a of the box 2. As shown in Figure 2, the lower part 23a of this first energizing section 23 is located inside the box 2, and a first graphite electrode 23a1 made of non-metallic graphite material is attached to its lower surface.

[0030] Furthermore, as shown in Figure 2, a nearly T-shaped second energizing section 24 is provided at the center of the left side 2b of the lower surface 2c of the box 2, opposite the first energizing section 23. As shown in Figure 2, the upper part 24a of this second energizing section 24 is located inside the box 2, and a second graphite electrode 24a1 made of non-metallic graphite material is attached to its upper surface.

[0031] Incidentally, the first energizing part 23 and the second energizing part 24 described above are designed to move vertically up and down so that the first graphite electrode 23a1 and the second graphite electrode 24a1 can approach or contact each other, or move apart. This allows the first graphite electrode 23a1 and the second graphite electrode 24a1 to approach or contact each other, thereby sandwiching the left side B1a and the right side B1b of the laminated conductive material foil B1 with the dowel crimping part B2 shown in Figure 1(c). Thus, in this state, by applying a predetermined current and resistively heating using the first graphite electrode 23a1 and the second graphite electrode 24a1, the left fixing part B3 or the right fixing part B4 shown in Figure 5 can be formed. After the left fixing part B3 or the right fixing part B4 shown in Figure 5 is formed, the first graphite electrode 23a1 and the second graphite electrode 24a1 are moved apart.

[0032] On the other hand, when performing resistance heating as described above, it is necessary to support the conductive material foil B1 which is laminated with the dowel crimp portion B2 shown in Figure 1(c). Therefore, as shown in Figure 2, a mounting base 3 is provided between the connection port 22 and the second energizing portion 24 at the center of the right side 2d of the lower surface 2c of the box 2. As shown in Figure 3(a), this mounting base 3 consists of a horizontally elongated rectangular first mounting base 30 extending in the front-to-back direction and a rectangular second mounting base 31 which is attached and fixed to the upper surface 30a of the first mounting base 30 and is arranged in the left-to-right direction.

[0033] Thus, as shown in Figure 4(c), an alignment jig 4 is attached and fixed to the upper surface 31a of the second mounting base 31 (see Figure 3(a)) on the mounting base 3 configured in this way. This alignment jig 4 includes a horizontally elongated rectangular first holding base 40 that extends in the front-to-back direction as shown in Figure 3(b). This first holding base 40 is attached and fixed to the upper surface 31a of the second mounting base 31, as shown in Figure 3(b).

[0034] On the other hand, as shown in Figure 3(c), a rectangular first insulating material 41 is placed on the upper surface 40a of the first holding base 40 shown in Figure 3(b). Any insulating material can be used as the first insulating material 41, but it is preferable to use alumina, which can withstand high currents and high temperatures and has low heat absorption.

[0035] Thus, as shown in Figure 4(a), a conductive material foil B1, which has been laminated with a dowel crimp portion B2, is placed on the upper surface 41a (see Figure 3(c)) of the first insulating material 41. At this time, the conductive material foil B1, which has been laminated with a dowel crimp portion B2, is placed such that its left side B1a (the part where the left fixing portion B3 shown in Figure 5 is formed) and its right side B1b (the part where the right fixing portion B4 shown in Figure 5 is formed) protrude from the first insulating material 41, as shown in Figure 4(a).

[0036] Thus, as shown in Figure 4(b), a rectangular second insulating material 42 is placed on the upper surface of the conductive material foil B1, which is laminated with a dowel crimp portion B2 placed on the upper surface 41a (see Figure 4(a)) of the first insulating material 41. As a result, as shown in Figure 4(b), the conductive material foil B1, which is laminated with a dowel crimp portion B2, is sandwiched between the first insulating material 41 and the second insulating material 42. Any insulating material can be used as the second insulating material 42, but it is preferable to use alumina, which can withstand high current and high temperature and has low heat absorption.

[0037] Thus, as shown in Figure 4(c), a horizontally elongated rectangular second holding base 43, extending in the front-to-back direction, is placed on the upper surface 42a (see Figure 4(b)) of the second insulating material 42, which sandwiches the conductive material foil B1, with the dowel crimp portion B2 formed and laminated, between the first insulating material 41 and the second insulating material 42. This second holding base 43 is then attached and fixed to the first holding base 40, as shown in Figure 4(c). As a result, as shown in Figure 4(c), an alignment jig 4, which sandwiches the conductive material foil B1, with the dowel crimp portion B2 formed and laminated, is attached and fixed to the upper surface 31a of the second mounting base 31.

[0038] Thus, in this state, in this embodiment, the left side B1a of the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c) formed (the part where the left fixing portion B3 shown in Figure 5 is formed) is sandwiched between the first graphite electrode 23a1 and the second graphite electrode 24a1 shown in Figure 2. Then, when a predetermined current is passed through in this state, resistance heating occurs. That is, by passing a predetermined current, heat is generated in the first graphite electrode 23a1 and the second graphite electrode 24a1. This heat is transferred to the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c), and the left side B1a of the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c) is heat-pressed. As a result, the left fixing portion B3 shown in Figure 5 is formed.

[0039] Incidentally, the reason why the conductive material foil B1, which is laminated with a dowel crimp portion B2 formed between the first insulating material 41 and the second insulating material 42, is sandwiched between them is to perform resistance heating by passing a predetermined current through it. In other words, if it were not insulated, there would be a risk of current flowing through the first graphite electrode 23a1 and the second graphite electrode 24a1 leaking through the conductive material foil B1, which is laminated with a dowel crimp portion B2 formed between them. If leakage occurs, there is a risk of a major accident, such as sparks flying inside the manufacturing apparatus 1. For this reason, the conductive material foil B1, which is laminated with a dowel crimp portion B2 formed between the first insulating material 41 and the second insulating material 42, is sandwiched between them for insulation. Furthermore, since resistance heating is performed at high temperatures of 700°C to 900°C, if there is no support for the conductive material foil B1 with the dowel crimped portion B2 formed and laminated, this high temperature could cause the entire or a part of the conductive material foil B1 with the dowel crimped portion B2 to bend. For this reason, the conductive material foil B1 with the dowel crimped portion B2 formed and laminated is sandwiched between the first insulating material 41 and the second insulating material 42, which also serve as clamps.

[0040] Furthermore, in the present embodiment, the first graphite electrode 23a1 and the second graphite electrode 24a1 are used for the following reason. That is, copper is mainly used as the material of the laminated conductive material foil B1 on which the dowel caulking portion B2 is formed. Therefore, when a copper electrode is used, the melting point and resistance value of copper are substantially the same, and current simply flows therethrough. This results in no transformer effect, and optimal resistance heating cannot be achieved. For this reason, the first graphite electrode 23a1 and the second graphite electrode 24a1 are used so that the melting point and resistance value of copper are not substantially the same. Thereby, a part with a high resistance value is created, and optimal resistance heating can be performed.

[0041] The content described above is the description of the manufacturing apparatus 1.

[0042] <Description of Usage Example of Manufacturing Apparatus> Next, a usage example of the manufacturing apparatus 1 configured as described above will be described. Note that the procedure shown below is merely an example, and is not limited thereto.

[0043] First, as shown in FIG. 4(c), the alignment jig 4 holding the laminated conductive material foil B1 on which the dowel caulking portion B2 is formed is attached and fixed to the upper surface 31a of the second mounting table 31 (see FIG. 3(a)).

[0044] Next, an inert gas (for example, nitrogen gas) is injected into the box 2 from the injection port 20 shown in FIG. 2. Thereby, the atmosphere (containing oxygen) filling the inside of the box 2 is discharged from the discharge port 21 shown in FIG. 2. At this time, an unillustrated oxygen concentration meter connected to the connection port 22 is checked, and the inert gas (for example, nitrogen gas) is injected into the box 2 from the injection port 20 shown in FIG. 2 until the oxygen concentration inside the box 2 reaches an oxygen-free state. That is, the oxygen inside the box 2 is degassed.

[0045] Next, after creating an inert gas environment inside box 2, the left side B1a or right side B1b of the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c) is sandwiched between the first graphite electrode 23a1 and the second graphite electrode 24a1 shown in Figure 2. In this state, when a predetermined current is passed through, resistance heating occurs. That is, by passing a predetermined current, heat (for example, 700°C to 900°C) is generated in the first graphite electrode 23a1 and the second graphite electrode 24a1. This heat is transferred to the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c), causing the left side B1a or right side B1b of the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c) to be heat-pressed. As a result, the left fixing portion B3 or the right fixing portion B4 shown in Figure 5 is formed. Furthermore, after forming the left fixing portion B3 or the right fixing portion B4 shown in Figure 5, the first graphite electrode 23a1 and the second graphite electrode 24a1 will be separated.

[0046] Incidentally, since the inside of box 2 is oxygen-free, even if the left side B1a or right side B1b of the conductive material foil B1 with the dowel crimped portion B2 shown in Figure 4(c) is heat-pressed, it will not oxidize (turn black, etc.). In other words, when heat-pressing, the left side B1a or right side B1b of the conductive material foil B1 with the dowel crimped portion B2 shown in Figure 4(c) becomes hot, so simply heat-pressing it would cause oxidation (turn black, etc.). Therefore, if oxidation occurs, the oxidized part must be polished. However, this not only increases the number of work steps, but also causes damage to the conductive material foil B1 with the dowel crimped portion B2 formed during the polishing process, leading to variations in quality. Therefore, in this embodiment, the inside of box 2 is kept oxygen-free to prevent oxidation.

[0047] This point is clear when viewing the photograph shown in Figure 6. That is, the photograph shown in Figure 6 indicates that the oxygen concentration in the atmosphere approaches the oxygen concentration of the ambient air toward the right side of the drawing, and approaches an oxygen-free state toward the left side of the drawing. As shown in Figure 6, when the oxygen concentration is 1.5% to 2.0%, 4.5% to 5.0%, and 20.9%, the surface of the laminated conductive material foil B1 on which the dowel caulked portion B2 is formed is clearly discolored, and oxidation is observed. On the other hand, as shown in Figure 6, when the oxygen concentration is 0.4% to 0.5%, the oxidation observed at oxygen concentrations of 1.5% to 2.0%, 4.5% to 5.0%, and 20.9% is not observed, but slight oxidation is seen in the portion indicated by the dotted line on the surface of the laminated conductive material foil B1 on which the dowel caulked portion B2 is formed. However, as shown in Figure 6, under an oxygen-free condition, even the oxidation observed at an oxygen concentration of 0.4% to 0.5% is not observed.

[0048] Thus, from the above, if the inside of the box 2 is kept in an oxygen-free state, even if the left side surface B1a side or the right side surface B1b side of the laminated conductive material foil B1 on which the dowel caulked portion B2 shown in Figure 4(c) is formed is thermocompression bonded, oxidation (discoloration to black or the like) will not occur.

[0049] Therefore, by degassing oxygen and filling the space with an inert gas through the method described above, and performing thermocompression bonding on the left side surface B1a side or the right side surface B1b side of the laminated conductive material foil B1 on which the dowel caulked portion B2 shown in Figure 4(c) is formed in the inert gas environment, oxidation as seen in the conventional art will not occur. This eliminates the conventional work of polishing oxidized portions, so quality can be improved without increasing the number of work steps.

[0050] By the way, if, after heat-pressing the left side B1a or right side B1b of the laminated conductive material foil B1 with the dowel crimp portion B2 formed as shown in Figure 4(c) as described above, the laminated conductive material foil B1 with the dowel crimp portion B2 formed is immediately removed from the box 2, there is a risk that the laminated conductive material foil B1 with the dowel crimp portion B2 formed may oxidize. For this reason, it is preferable to allow a cooling period. That is, after heat-pressing the left side B1a or right side B1b of the laminated conductive material foil B1 with the dowel crimp portion B2 formed as shown in Figure 4(c), the laminated conductive material foil B1 with the dowel crimp portion B2 formed is still hot. Therefore, if the laminated conductive material foil B1 with the dowel crimp portion B2 formed is exposed to oxygen in the air by opening the box 2, there is a risk that the laminated conductive material foil B1 with the dowel crimp portion B2 formed may oxidize due to that oxygen. Therefore, after the left side B1a or right side B1b of the laminated conductive material foil B1 with the dowel crimp portion B2 shown in Figure 4(c) formed, it is preferable to provide a cooling period by injecting an inert gas (for example, nitrogen gas) into the box 2 from the injection port 20 shown in Figure 2 to cool it, or by leaving it for a certain period of time.

[0051] Thus, as described above, by using the manufacturing apparatus 1 shown in Figure 2, the left fixing portion B3 and the right fixing portion B4 shown in Figure 5 are formed, and the flexible busbar B shown in Figure 5 is manufactured as a result.

[0052] Therefore, according to the embodiment described above, when laminating multiple conductive material foils B1, dowel crimping is performed on the left side B1a and the right side B1b of the conductive material foil B1. As a result, the positions of the multiple conductive material foils B1 are fixed, so when moving on to the process of fixing the necessary parts (in this embodiment, the process of forming the left fixing part B3 and the right fixing part B4), it is possible to prevent the laminated conductive material foils B1 from shifting.

[0053] Therefore, according to this embodiment, it is possible to prevent misalignment of the laminated conductive material foil B1.

[0054] <Explanation of Variations> The shapes shown in this embodiment are merely examples, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. For example, the shape of the manufacturing apparatus 1 described in this embodiment is merely an example and can be changed to any shape.

[0055] Furthermore, although this embodiment shows an example of resistance heating by applying a predetermined current, heating may be performed in stages depending on the size and number of layers of the flexible busbar B. For example, heating can be performed in two stages. First, in the first stage, a low current of about 1.0 kA to 2.0 kA is applied to heat the busbar to a target temperature of about 200°C to 350°C. Next, in the second stage, a high current of about 2.5 kA to 7.0 kA is applied to heat the busbar to a target temperature of about 700°C to 900°C. This reduces the sparks that may occur during the bonding process. In other words, since the surface resistance of the flexible busbar B is highest before heating, it is thought that the resistance decreases as the heating temperature rises. Therefore, it is thought that sparks will occur if a high current is applied in the initial stage of heating when the resistance is highest. For this reason, a low current is applied in the initial stage of heating to reduce the resistance. Then, in the next stage, a high current is applied to heat the busbar to the final target temperature. This can be visualized as shown in the graph in Figure 7.

[0056] As shown in Figure 7, the first stage of heating is performed between time T1 and T2. The target temperature for the first stage is reached at time T2.

[0057] Next, as shown in Figure 7, the second stage of heating is performed between times T2 and T3. During this stage, the left side B1a or the right side B1b of the conductive material foil B1 shown in Figure 1(a) is heat-pressed. The target temperature for the second stage is reached at time T3.

[0058] Next, as shown in Figure 7, a cooling period is provided between times T3 and T4. Once the temperature falls below a certain level (for example, about 200°C), the conductive material foil B1 with the dowel crimped portion B2 formed and laminated is removed from the box 2 after time T4.

[0059] Therefore, to reduce the sparks that may occur during settling, heating may be performed in two stages as described above. While it is also conceivable to continuously apply a low current of approximately 1.0 kA to 2.0 kA to reduce sparks, this requires prolonged heating, and furthermore, there are limitations to the heating capacity, potentially preventing the final target temperature from being reached. Therefore, rather than continuously applying a low current of approximately 1.0 kA to 2.0 kA, it is preferable to heat in multiple stages as described above.

[0060] Furthermore, in this embodiment, an example is shown in which dowel crimping portions B2 are formed on the left side B1a and the right side B1b of the conductive material foil B1 shown in Figure 1(a). However, the embodiment is not limited to this, and can also be done as follows.

[0061] For example, as shown in Figure 8(a), a dowel crimping portion B2 may be formed in the central part of the left side B1a of the multiple laminated conductive material foils B1, and a dowel crimping portion B2 may be formed in the central part of the right side B1b.

[0062] Incidentally, as shown in Figure 8(b), when the left fixing portion B3 and the right fixing portion B4 are formed, the left fixing portion B3 and the right fixing portion B4 become fastening portions that connect electrically conductive members (for example, batteries installed in electric vehicles or hybrid cars). Therefore, as shown in Figure 8(b), a circular left bolt hole B3a is provided through the left fixing portion B3 in the vertical direction, and a circular right bolt hole B4a is provided through the right fixing portion B4 in the vertical direction. As a result, when the flexible bus bar B shown in Figure 8(b) is manufactured, the traces of the dowel crimp portion B2 are erased by the left bolt hole B3a and the right bolt hole B4a. Therefore, as shown in Figure 8(a), if the dowel crimp portion B2 is formed, the traces of it can be erased when the flexible bus bar B is manufactured.

[0063] On the other hand, as shown in Figure 8(c), a dowel crimping portion B2 may be formed in the non-fixed portion B5 formed between the left fixed portion B3 and the right fixed portion B4. In this way, displacement of the laminated conductive material foil B1 can be prevented. Furthermore, if distortion occurs in the non-fixed portion B5, the dowel crimping portion B2 can be used to adjust the distortion in the non-fixed portion B5.

[0064] On the other hand, when laminating multiple conductive material foils B1 using the T-shaped spool / runner B6 shown in Figure 9, a dowel crimping portion B2 may be formed on each of the multiple conductive material foils B1 with respect to the spool / runner B6. In this case, since the dowel crimping portion B2 is formed on the spool / runner B6, misalignment of the laminated conductive material foils B1 can be prevented. Note that the spool / runner B6 shown in Figure 9 will ultimately be cut, so when it becomes a flexible busbar B as shown in Figures 5 and 8(b), the traces of the dowel crimping portion B2 can be erased.

[0065] Furthermore, although a straight shape was used as an example for the flexible busbar B in this embodiment, it is not limited to this and can also be applied to complex shapes (non-straight shapes).

[0066] 1 Manufacturing equipment 2 Box 4 Alignment jig 41 First insulating material (insulating material) 42 Second insulating material (insulating material) B Flexible bus bar B1 Conductive material foil (conductive material) B1a Left side (of conductive material foil) B1b Right side (of conductive material foil) B2 Dowel crimping part B3 Left fixing part B4 Right fixing part B6 Spool / runner

Claims

1. A method for manufacturing a flexible busbar, comprising the steps of: laminating a plurality of conductive materials; performing dowel crimping on a part of the conductive materials or on a spool / runner provided on the conductive materials when laminating the plurality of conductive materials; and heat-pressing the sides of the plurality of conductive materials that have been crimped.

2. A method for manufacturing a flexible busbar according to claim 1, further comprising the steps of: arranging a plurality of conductive materials that have been crimped in a predetermined box; degassing the oxygen in the predetermined box and filling it with an inert gas; and heat-pressing the sides of the plurality of conductive materials that have been crimped in an inert gas environment.

3. The method for manufacturing a flexible busbar according to claim 2, wherein, when arranging the plurality of conductive materials that have been dowel-crimped in a predetermined box, the plurality of conductive materials that have been dowel-crimped are held by being sandwiched between insulating materials, except for the sides of the plurality of conductive materials that have been dowel-crimped.

4. A method for manufacturing a flexible busbar according to claim 2 or 3, comprising: heat-pressing the sides of the plurality of conductive materials that have been dowel-crimped in an inert gas environment, providing a cooling period, and then removing the plurality of conductive materials that have been dowel-crimped from the predetermined box.

5. A method for manufacturing a flexible busbar according to claim 2 or 3, wherein, in an environment of the inert gas, the sides of the plurality of conductive materials that have been crimped together are heat-compressed together by resistance heating, and in this case, the resistance heating is performed by passing a first current for a first period, and then the resistance heating is performed by passing a second current which is higher than the first current for a second period.

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