JP5105788B2 - Micro spot resistance welding apparatus and welding method thereof - Google Patents

Description

  The present invention relates to a micro spot resistance welding apparatus and a welding method thereof, and more particularly to a multi-point micro spot resistance welding apparatus suitable for welding in a battery pack manufacturing process and a welding method thereof.

  In the process of manufacturing a battery pack by adding a protection circuit board or PTC (Positive Temperature Coefficient) element to a unit cell such as a lithium ion battery, a conductive tab that connects between the unit cell, the terminal of the protection circuit board, and the external terminal For connection or connection between two conductive tabs, microspot resistance welding such as 2, 3, 4, 6, etc. is used per connection.

  In the case of two-point welding, there is a welding method called series welding in which bipolar electrodes are arranged on one side of a welding member and two-point resistance welding is simultaneously performed. FIG. 5 shows the welding apparatus (conventional example 1). FIG. 5A is a schematic diagram showing the whole welding apparatus, in which 501 is a welding power source, 502 is a pressurizing mechanism of a welded portion, 51 is a positive electrode, and 52 is a negative electrode. FIG. 5B is an enlarged view of the portion B of FIG. 5A when welding, 53 is an auxiliary electrode, 54 is a first welding material, and 55 is a second welding material. With such a welding apparatus, two points of resistance welding are simultaneously performed.

  The example of patent document 1 based on the same technique makes it possible to simultaneously join two welding locations of a material to be welded to a substantially uniform welding strength in a short energization time in series welding.

  As another method, there is a welding method called direct welding in which two electrodes facing each other are used to sequentially weld a plurality of welding points one by one. FIG. 6 shows the welding apparatus (conventional example 2). FIG. 6A is a schematic diagram showing the entire welding apparatus, in which 601 is a welding power source, 602 is a pressurizing mechanism of a welded portion, 61 is a positive electrode, 62 is a negative electrode, and 64 is a first weld. Material 65 is the second welding material. Moreover, FIG.6 (b) is an enlarged view at the time of welding of the C section of Fig.6 (a). Welding is performed point by point with such a welding apparatus.

Japanese Patent Laid-Open No. 10-85947

  In order to perform multi-point resistance welding by the method of Conventional Example 2, the process of movement, pressurization, and welding current energization is required for each welding point, and it is difficult to shorten the time of all welding processes. In addition, in series welding in which two points are welded simultaneously in one process of Conventional Example 1, reactive current is likely to be generated, and the contact is poor due to dirt, surface roughness, flatness, etc. of the surfaces of the members to be joined. In particular, there are cases where a lot of reactive current flows, and there are problems such as variations in welding strength, inability to weld, and disconnection of the welded portion.

  This will be described in detail with reference to FIG. The current that passes through the boundary surface between the first welding material 54 and the second welding material 55 and effectively contributes to heat generation at the welding point includes (1) the first welding material 54 → the second welding material 55 → the first welding material. There is a required current 56a that passes in the order of 54, and (2) a required current 56b that passes in the order of the first welding material 54 → the second welding material 55 → the auxiliary electrode 53 → the second welding material 55 → the first welding material 54. . On the other hand, there is a reactive current 57 that passes only through the first welding material 54 and does not contribute to welding. This current is reduced by the provision of the auxiliary electrode 53, but it is easily affected by dirt, surface roughness, flatness, etc. on the surfaces of the members to be joined, which causes variations in welding strength.

  In the above situation, an object of the present invention is to provide a multi-point micro spot resistance welding apparatus and a welding method thereof that can reduce variation in welding strength and can shorten the time required for the welding process.

  In order to solve the above-described problems, the micro spot resistance welding apparatus of the present invention is a multi-point micro spot resistance welding apparatus that performs spot welding at two or more minimum locations, and is (1) arranged on the same plane. Two or more same-polarity upper electrodes, (2) one common lower electrode, and (3) a pressurizing mechanism that pressurizes a welding member between the upper electrode and the lower electrode, 4) a pressure detection mechanism for detecting that the pressurization has reached a predetermined value; (5) a trigger signal generator for generating a trigger signal based on an output of the pressure detection mechanism; and (6) a trigger signal. In response, a power supply unit is provided for flowing a welding current at the predetermined time interval in order between each of the upper electrodes and the lower electrode.

  In addition, the power source unit includes individual power sources provided for each of the upper electrodes. Each of the individual power sources receives the trigger signal and then receives a welding current after a delay time different from the others. It is recommended to start energization.

  The micro spot resistance welding method of the present invention is a multi-point micro spot resistance welding method in which spot welding is performed on N (N is a natural number of 2 or more) minimum locations, and (1) arranged on the same plane. A step of pressurizing a welding member between the N upper electrodes having the same polarity and one lower electrode, and (2) a pressure sensor detecting that the pressure of the pressurization has reached a predetermined value. Then, using a trigger signal generator and a resistance welding power source, a step of flowing a welding current at a predetermined time interval between each of the first to Nth upper electrodes and the lower electrode.

  According to the present invention, two points can be welded almost simultaneously in one process as in series welding, and stable welding strength similar to direct welding can be obtained in one welding process. That is, variation in welding strength can be reduced, and the time required for the welding process can be shortened.

  FIG. 1 is a schematic diagram showing a microspot resistance welding apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing a state of energization at the time of first welding of the A part (welding head). FIG. 3 is an enlarged view showing a state of energization during the second welding of the A part.

  The micro spot resistance welding apparatus of the present embodiment includes (1) two first welding power sources 101 and 102 for generating and generating welding energy, and (2) pressurizing a material to be welded, A pressure mechanism 103 having the same structure as the series welding pressure mechanism for generating a trigger by pressure, and (3) a lower electrode 13 made mainly of copper.

  The first and second welding power sources 101 and 102 are power sources capable of controlling the pulse width. The + terminals of the two welding power sources are connected to respective terminals having the same structure as the series welding pressure mechanism. That is, the + terminal of the first welding power source 101 is connected to the first upper electrode 11, and the + terminal of the second welding power source 102 is connected to the second upper electrode 12. Further, the negative terminals of the first and second welding power sources 101 and 102 are both connected to the common lower electrode 13 installed under the pressurizing mechanism, and current is supplied to the first and second welding materials 14 and 15. Is connected to flow.

  The TRG terminal (trigger terminal) of the pressurizing mechanism unit 103 including the trigger signal generator is connected to the first and second welding power sources 101 and 102 and outputs a trigger for starting welding to the welding power source. It is assumed that the second welding power source 102 sets a delay time of about 10 ms (milliseconds) from the time when the welding trigger is generated with respect to the first welding power source 101.

  When welding the first welding material 14 and the second welding material 15 between the pressurizing mechanism 103 and the lower electrode 13, the entire pressurizing mechanism 103 is lowered by an external trigger or a foot pedal. The first upper electrode 11 and the second upper electrode 12 come into contact with the first welding material 14 and are further pressurized. When the applied pressure increases and reaches the set pressure set by the pressurizing mechanism, it is detected by the pressurizing detection mechanism, and the pressurizing mechanism section 103 generates a trigger signal for welding by a built-in trigger signal generator. The first welding power source 101 that has received the trigger signal causes a welding current to flow through the first upper electrode 11 of the positive terminal, and the current flows from the first upper electrode 11 of the positive electrode to the lower electrode 13 of the negative electrode as shown in FIG. As a result, a first nugget 16 is generated between the first welding material 14 and the second welding material 15.

  FIG. 4 is a timing chart showing current pulses of two welding power sources in the present embodiment. As shown in FIG. 4, it is assumed that the current pulse width of the first welding power source is about several ms, and that there is a sufficient margin for the delay time of the second welding power source. By doing so, the current flow is stabilized. Next, in a time delayed by about 10 ms from the time of the trigger, the second welding power source sends a welding current to the + terminal and welds from the positive second upper electrode 12 to the negative lower electrode 13 as shown in FIG. A current (necessary current 31) flows. As a result, a second nugget 17 is generated between the first welding material 14 and the second welding material 15. However, since the first nugget 16 is also generated, the reactive current 32 is generated, but the amount thereof is small, and the current value of the second welding power source 102 is set larger than the current value of the first welding power source 101. Problem can be avoided.

  In the timing chart shown in FIG. 4, upon receiving one trigger signal, the welding power source 1 immediately generates a current pulse (welding process 1), and the welding power source 2 has a delay time of about 10 ms after receiving the trigger signal. However, instead of providing a separate welding power source for each upper electrode, a single welding power source is used, and a plurality of trigger signals corresponding to a plurality of trigger signals are generated. A current pulse may be generated.

  As another configuration, a trigger signal generator is also incorporated in the first welding power source 101, and the trigger signal generated by the pressurizing mechanism 103 is output only to the first welding power source 101. In addition to generating a current pulse, a built-in trigger signal generator generates a new trigger signal after a predetermined delay time, and outputs this to the second welding power source 102, which receives it. It is also possible to immediately generate a welding current pulse.

  Although the present embodiment relates to two-point welding, welding of three or more points can be easily inferred from the description of the present embodiment. That is, after the pressurization process is completed, it is preferable that a welding current is sequentially flowed between each of the upper electrode and the lower electrode in response to a trigger signal at predetermined time intervals so that the welding currents do not overlap each other.

  As described above, according to the micro spot resistance welding and the welding method of the present invention, two or more points can be welded simultaneously in one process, and the reactive current does not flow in the first welding process. Stable welding strength can be obtained, and the conventional direct welding requires as many welding steps as the number of welding points, but it can be seen that welding can be performed in a shorter time than that.

  As an embodiment of the present invention, an example in which two conductive tabs are connected by welding will be described. The micro spot resistance welding apparatus used in this example is the same as that of FIG. 1 described in the embodiment of the present invention, and its welding head is as shown in FIG. The outline is the same as that shown in FIG. 4, and is an example in which two points are resistance-welded almost simultaneously.

  The welding object is two conductive tabs, which are made of nickel having a width of 3 mm and a thickness of 0.1 mm.

  Referring to FIG. 2, the diameters of first upper electrode 11 and second upper electrode 12 are φ1.0 mm, and the center-to-center distance is 1.4 mm. Further, although alumina-dispersed copper is used for the common lower electrode 13, chromium copper or the like may be used.

  Referring to FIG. 1 regarding the power source unit, the first welding power source 101 is an inverter power source and receives a trigger signal from the pressurizing mechanism unit 103 and immediately generates a welding current pulse. The second welding power source 102 is also an inverter power source, and is set to generate a welding current pulse after a delay time of 10 ms after receiving the trigger signal from the pressurizing mechanism unit 103. At this time, the voltage of the welding current pulse was 2.0 V, the current was 1.8 to 2.1 kA, and the pulse width was about 2.5 ms.

  The two nugget diameters obtained under these welding conditions were about φ1.3 mm, and the center-to-center distance was 1.4 mm. Also, good welding strength was obtained when the voltage of the welding current pulse was 1.5 V to 2.5 V and the current was in the range of 1.3 kA to 2.5 kA.

  Further, the time required for the entire welding process by positioning, pressurization, and energization of the welding current is 8 seconds, which can be greatly shortened from 14 seconds in the case of welding one point at a time.

  In the above examples, welding between nickel was described, but welding between tin-plated irons or between tin-plated iron and nickel was also successfully performed.

The schematic diagram which shows the micro spot resistance welding apparatus in one embodiment of this invention. The enlarged view which shows the mode of the electricity supply at the time of the 1st welding of the A section of FIG. The enlarged view which shows the mode of the electricity supply at the time of the 2nd welding of the A section of FIG. The timing chart which shows the current pulse of the two welding power supplies in one embodiment of this invention. The welding apparatus of the prior art example 1 is shown, Fig.5 (a) is a schematic diagram which shows the whole welding apparatus, FIG.5 (b) is an enlarged view at the time of the welding of the B section of Fig.5 (a). The welding apparatus of the prior art example 2 is shown, Fig.6 (a) is a schematic diagram which shows the whole welding apparatus, FIG.6 (b) is an enlarged view at the time of the welding of the C section of Fig.6 (a).

Explanation of symbols

11 First upper electrode 12 Second upper electrode 13 Lower electrodes 14, 54, 64 First welding material 15, 55, 65 Second welding material 16 First nugget 17 Second nugget 31, 56a, 56b Required current 32, 57 Invalid Current 51, 61 Positive welding electrode 52, 62 Negative welding electrode 101 First welding power source 102 Second welding power source 103 Pressurization mechanism section 501, 601 Welding power source 502, 602 Pressurization mechanism

Claims (2)

A multi-point micro spot resistance welding apparatus that performs spot welding on two or more minimum points,
Two or more same-polar upper electrodes disposed on the same plane;
One common lower electrode having a polarity different from that of the upper electrode facing the upper electrode across a welding member ;
A pressure mechanism for performing interposed therebetween pressure the welding member between said upper and lower electrodes,
A pressure detection mechanism for detecting that the pressurization has reached a predetermined value;
A trigger signal generator that generates a trigger signal based on the output of the pressure detection mechanism;
In response to the trigger signal, between each lower electrode of the upper electrode, and a power supply unit for supplying a welding current at a predetermined time interval in order,
The power supply unit comprises individual power supplies provided one for each of the upper electrodes,
Each of the individual power supplies receives energization of its own welding current after receiving the trigger signal, after a delay time different from the others, and in a state where no welding current is energized elsewhere. Micro spot resistance welding equipment. A multi-point micro spot resistance welding method for spot welding to N (N is a natural number of 2 or more) minimum points,
And an upper electrode of the N same polarity arranged on the same plane, pressurized across the welding member between the upper electrode and the polarity different one lower electrode facing the upper electrode across the welding member Pressing, and
After detecting that the pressure of this pressurization has reached a predetermined value with the pressure detection mechanism,
Using a trigger signal generator and a power supply, and passing a welding current at a predetermined time interval between each of the first to Nth upper electrodes and the lower electrode,
The power supply unit is composed of individual power supplies provided for each of the N upper electrodes.
In the step of flowing the welding current, each of the individual power supplies receives the trigger signal from the trigger signal generator, and then sequentially does not pass the welding current after a delay time different from the others. A microspot resistance welding method characterized by starting energization of a self-welding current in a state.

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