JP6007783B2 - Welding method and welding apparatus - Google Patents

Description

  The present invention relates to a welding method and a welding apparatus for resistance welding an electrode of a power storage device and a conductive member that transmits and receives electricity between the electrode.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. In this type of secondary battery, a negative electrode with a negative electrode active material applied to a metal foil and a positive electrode with a positive electrode active material applied to a metal foil are insulated by a separator, and these are laminated into a layered electrode assembly. The electrode assembly is accommodated in the case together with the electrolyte. Each electrode constituting the electrode assembly is electrically connected to positive and negative electrode terminals exposed to the outside of the case via a conductive member that exchanges electricity with the electrode. And joining of each electrode and an electrically-conductive member is performed by resistance welding using a resistance welding machine as disclosed by patent document 1, for example.

International Publication WO2010 / 110316

  Resistance welding is a system in which a pair of positive and negative welding electrodes are brought into contact with a joining object, the welding electrode and the joining object are energized, and the joining object is melted and welded by resistance heat generated by the energization. By the way, the welding electrode used in resistance welding generates heat when energized at the time of welding and is accompanied by a rise in temperature. For this reason, a crack may occur in the welding electrode due to a thermal shock accompanying a temperature change, and the welding electrode in which the crack has occurred needs to be replaced. Therefore, frequent replacement of the welding electrode is a factor that decreases the manufacturing efficiency of the power storage device.

  This invention was made paying attention to the problem which exists in such a prior art, The objective is to provide the welding method and welding apparatus which suppress generation | occurrence | production of the crack of the electrode for welding. is there.

A welding method for solving the above-described problem is a welding method for resistance-welding an electrode of a power storage device and a conductive member that transmits and receives electricity between the electrode of the power storage device, and is wound around a welding electrode the heating means heats the welding electrode, the heated welding electrodes is brought into contact with the electrodes of the conductive member and the electrical storage device, the welding electrode, by supplying current to the electrodes of the conductive member and the electrical storage device resistance Weld. According to this, the temperature change of the welding electrode at the time of resistance welding can be reduced by heating the welding electrode. Therefore, it is possible to suppress the occurrence of cracks in the welding electrode due to thermal shock.
A welding method that solves the above-described problem is a welding method that resistance-welds an electrode of a power storage device and a conductive member that transfers electricity between the electrode of the power storage device, and heats the welding electrode by a heating unit. The heated welding electrode is brought into contact with the conductive member and the electrode of the power storage device, and the welding electrode, the conductive member and the electrode of the power storage device are energized and subjected to resistance welding, and then heated by the heating means. In a continued state, energization of the welding electrode, the conductive member, and the electrode of the power storage device is stopped. According to this, the temperature change of the welding electrode at the time of resistance welding can be reduced by heating the welding electrode. Therefore, it is possible to suppress the occurrence of cracks in the welding electrode due to thermal shock.

  In the welding method, the resistance welding is preferably performed in a state where the welding electrode is kept warm. According to this, since the welding electrode is kept warm, a rapid temperature change of the welding electrode due to repeated resistance welding can be suppressed. Therefore, it is possible to suppress the occurrence of cracks in the welding electrode due to thermal shock.

  In the welding method, the welding electrode is preferably kept at a temperature equal to or lower than a melting temperature of the electrode of the power storage device. According to this, even when the welding electrode is brought into contact with the electrode of the power storage device, it is possible to prevent the electrode of the power storage device from being melted by the heat of the welding electrode. Therefore, a good weld can be obtained.

A welding apparatus that solves the above problem is a welding apparatus that resistance welds an electrode of a power storage device and a conductive member that transmits and receives electricity between the electrode of the power storage device, the electrode of the power storage device, and the a welding electrode for energizing the conductive member, a moving mechanism for contacting the welding electrode electrode of the electric storage device, and the conductive member, and a heating means for heating the welding electrode, said heating means , Wound around the welding electrode . According to this, the heating means for heating the welding electrode is provided, and the temperature of the welding electrode during resistance welding can be reduced by heating the welding electrode by the heating means. Therefore, it is possible to suppress the occurrence of cracks in the welding electrode due to thermal shock.

  The welding apparatus preferably includes voltage applying means for applying a voltage to the welding electrode and energy applying means for applying heating energy to the heating means. According to this, it is possible to individually perform control for energizing the welding electrode, the conductive member, and the electrode of the power storage device, and control for heating the welding electrode by the heating means. Therefore, control can be simplified.

A welding apparatus that solves the above problem is a welding apparatus that resistance welds an electrode of a power storage device and a conductive member that transmits and receives electricity between the electrode of the power storage device, the electrode of the power storage device, and the A welding electrode for energizing the conductive member, a moving mechanism for bringing the welding electrode into contact with the electrode of the power storage device and the conductive member, a heating means for heating the welding electrode, and heating means for heating the heating means. Energy applying means for applying energy, and voltage applying means for applying a voltage to the welding electrode, wherein the energy applying means applies heating energy to the heating means prior to voltage application by the voltage applying means. The voltage application means is the welding electrode when the energy application means is in a state where energy for heating is applied to the heating means. It is to start and stop the application of voltage. According to this, the heating means for heating the welding electrode is provided, and the temperature of the welding electrode during resistance welding can be reduced by heating the welding electrode by the heating means. Therefore, it is possible to suppress the occurrence of cracks in the welding electrode due to thermal shock. In addition, control for energizing the welding electrode, the conductive member, and the electrode of the power storage device and control for heating the welding electrode by the heating means can be performed separately. Therefore, control can be simplified.
In the welding apparatus, it is preferable that the energy applying unit applies electric energy to the heating unit. According to this, since the welding electrode is heated by converting electric energy into heat, the configuration of the heating means can be simplified.

  In the welding apparatus, it is preferable that the heating means is wound around the welding electrode. According to this, the heat of a heating means can be directly given to the welding electrode, and the welding electrode can be heated satisfactorily.

  According to the present invention, the occurrence of cracks in the welding electrode can be suppressed.

The partially broken perspective view of a secondary battery. The disassembled perspective view which shows the component of an electrode assembly. The schematic diagram which shows a welding apparatus. The schematic diagram which shows the state which is welding the electrode and the electrically-conductive member.

Hereinafter, an embodiment embodying a welding apparatus and a welding method will be described with reference to FIGS.
As shown in FIG. 1, a secondary battery 10 as a power storage device includes a case body 11a and a rectangular box-shaped case 11 formed of a lid 11b covering an opening of the case body 11a. A liquid (not shown) is contained. A positive electrode terminal 13 and a negative electrode terminal 14 are electrically connected to the electrode assembly 12. The positive terminal 13 and the negative terminal 14 are exposed outside the case 11 from the lid 11b.

  As shown in FIG. 2, the electrode assembly 12 includes a positive electrode 15 as an electrode of the power storage device, a negative electrode 16 as an electrode of the power storage device, and a separator 17 that insulates the positive electrode 15 and the negative electrode 16. Have. The electrode assembly 12 has a stacked structure in which a plurality of positive electrodes 15 and a plurality of negative electrodes 16 are alternately stacked, and a separator 17 is interposed between the positive electrodes 15 and the negative electrodes 16.

  The positive electrode 15 has a rectangular sheet shape, and has a positive electrode active material layer 19 containing a positive electrode active material on both surfaces of a positive electrode metal foil (an aluminum foil in the embodiment) 18. A positive electrode current collecting tab 20 made of a positive electrode metal foil 18 is provided on one side of the positive electrode 15. The negative electrode 16 has a rectangular sheet shape, and has a negative electrode active material layer 22 containing a negative electrode active material on both surfaces of a negative electrode metal foil (copper foil in the embodiment) 21. Further, a negative electrode current collecting tab 23 made of the negative electrode metal foil 21 is provided on one side of the negative electrode 16.

  The positive electrode current collecting tab 20 of each positive electrode terminal 13 and each positive electrode 15 is electrically connected to a positive electrode conductive member (in the embodiment, an aluminum plate) 24 that exchanges electricity with each positive electrode 15. The negative electrode current collecting tab 23 of each of the negative electrode terminal 14 and each negative electrode 16 is electrically connected to a negative electrode conductive member (a copper plate in the embodiment) 25 that exchanges electricity with each negative electrode 16. Resistance welding is used for joining the positive electrode current collecting tab 20 and the positive electrode conductive member 24 and joining the negative electrode current collecting tab 23 and the negative electrode conductive member 25. Resistance welding is, for example, a method in which an object to be joined such as the positive electrode current collecting tab 20 and the positive electrode conductive member 24 is sandwiched between a pair of positive and negative welding electrodes and welded. In addition, the code | symbol "26" of FIG. 1 is the welding part formed by resistance welding.

  As shown in FIG. 3, a welding apparatus that performs resistance welding includes rod-shaped welding electrodes 30 and 31. The welding electrodes 30 and 31 are made of a metal material having good electrical conductivity such as copper or tungsten. In this embodiment, a heating wire (for example, a nichrome wire or an iron chrome wire) 32 is wound around the peripheral surfaces of the welding electrodes 30 and 31 as heating means. The heating wire 32 is covered with an insulating material (for example, ceramic or glass). Thereby, the heating wire 32 will be in the state insulated with each electrode 30 and 31 for welding.

  The welding apparatus includes an energization portion 33 of each welding electrode 30, 31 and an energization portion 34 of a heating wire 32 wound around each welding electrode 30, 31. In this embodiment, the energizing portion 33 serves as a voltage applying means for applying a voltage to the welding electrodes 30 and 31. Further, in this embodiment, the energization unit 34 serves as an energy applying unit that applies electric energy as heating energy by applying a voltage to the heating wire 32. Further, the welding apparatus has a moving mechanism 35 that moves the welding electrode 30 toward and away from the welding electrode 31. By the moving mechanism 35, the welding electrode 30 is moved so as to contact the object to be joined at the time of welding and is moved away from the object to be joined after welding.

  Hereinafter, the operation of the welding apparatus will be described together with a method for welding the positive electrode current collecting tab 20 and the positive electrode conductive member 24. The welding of the negative electrode current collecting tab 23 and the negative electrode conductive member 25 is the same method as the welding of the positive electrode current collecting tab 20 and the positive electrode conductive member 24 described below.

  The energization part 34 of the welding apparatus applies a voltage to the heating wires 32 of the welding electrodes 30 and 31 when a preheating start signal based on an external operation by an operator or the like is input. Thereby, each welding electrode 30 and 31 is heated by heat_generation | fever of the heating wire 32, and is kept at predetermined temperature. In this embodiment, each welding electrode 30 and 31 is maintained at a temperature not lower than the ambient temperature and not higher than the melting temperature of the objects to be joined. When the objects to be joined are the positive electrode current collector tab 20 and the positive electrode conductive member 24, the welding electrodes 30 and 31 are kept at a temperature equal to or lower than the melting temperature of the positive electrode current collector tab 20 and the positive electrode conductive member 24.

  At the time of welding, an object to be joined is disposed between the welding electrodes 30 and 31 in a separated state. Then, the welding electrode 30 is brought into contact with the object to be joined by the moving mechanism 35. At the time of welding, the current-carrying unit 33 that has input a welding start signal based on an external operation by an operator or the like applies a voltage, whereby the positive electrode current collector that is the object to be joined is brought into contact with each welding electrode 30, 31 and the object to be joined. The tab 20 and the positive electrode conductive member 24 are energized. By this energization, the objects to be joined are heated by resistance heat and melted, and are joined by receiving a pressing force from the welding apparatus.

  After the end of welding, the energization unit 33 stops applying the voltage to the welding electrodes 30 and 31. On the other hand, the energization unit 34 continues to apply a voltage to the heating wire 32 to keep the welding electrodes 30 and 31 warm. Thereby, the electrodes 30 and 31 for welding are maintained in a state where the temperature change is small during welding and during non-welding. When resistance welding is repeated, resistance welding is performed in a state where the welding electrodes 30 and 31 are kept warm.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The welding electrodes 30 and 31 generate heat when energized at the time of welding and increase in temperature, but the temperature changes drastically such that the temperature decreases when welding is completed. For this reason, the temperature change of the electrodes 30 and 31 for welding at the time of welding and the time of non-welding can be made small by heating the electrodes 30 and 31 for welding. Therefore, it is possible to suppress the occurrence of cracks in the welding electrodes 30 and 31 due to thermal shock.

  (2) Thereby, in the production of the secondary battery 10, the replacement frequency of the welding electrodes 30 and 31 due to the occurrence of cracks can be suppressed, and the reduction in the production efficiency of the secondary battery 10 can be suppressed.

  (3) Since welding is performed in a state where the welding electrodes 30 and 31 are kept warm, rapid temperature changes of the welding electrodes 30 and 31 due to repeated resistance welding can be suppressed. Therefore, even when resistance welding is repeatedly performed, it is possible to suppress the occurrence of cracks in the welding electrodes 30 and 31 due to thermal shock.

  (4) Since the electrodes 30 and 31 for welding are kept below the melting temperature of the cathode current collecting tab 20 or the like that is the object to be joined, even when the electrodes 30 and 31 for welding are brought into contact with the object to be joined, It can suppress that a joining target object melts with the heat of electrodes 30 and 31 for welding. Therefore, a good welded portion 26 can be obtained.

(5) Since the welding electrodes 30 and 31 are heated by applying a voltage to the heating wire 32, the configuration for heating can be simplified.
(6) Since the heating wire 32 is wound around the peripheral surfaces of the welding electrodes 30, 31, the heat of the heating wire 32 can be directly applied to the welding electrodes 30, 31. 31 can be heated satisfactorily.

  (7) When the welding electrodes 30 and 31 and the object to be joined are energized, the energization unit 33 applies a voltage, and when the welding electrodes 30 and 31 are heated, the energization unit 34 applies a voltage. For this reason, control at the time of energization and heating can be performed separately, and control can be simplified.

In addition, you may change the said embodiment as follows.
In place of the peripheral surface of the heating wire 32, the peripheral surfaces of the welding electrodes 30, 31 may be covered with an insulating material. Moreover, you may coat | cover both the surrounding surface of each welding electrode 30 and 31 and the surrounding surface of the heating wire 32 with an insulating material.

  O Each welding electrode 30 and 31 may be heated by arranging a heat source such as a heater around each welding electrode 30 and 31. In this case, a heating wire 32 may be wound around each of the welding electrodes 30 and 31, or may be heated only by a heat source such as a heater.

  O You may change the energy provided in order to generate heat to heating means, such as the heating wire 32 and a heater. For example, heat may be generated using energy such as gas combustion energy or sunlight.

  The heating means such as the heating wire 32 and the heater may be arranged so as to heat the entire welding electrodes 30, 31, or heat is applied to local parts such as the tips of the welding electrodes 30, 31, May be communicated throughout.

The control content such as the timing at which the energization units 33 and 34 apply voltage may be changed. In short, it is only necessary that the welding electrodes 30 and 31 are heated during welding.
The voltage application by the energization unit 34 may be uniquely performed when the main power supply of the welding apparatus is turned on.

During heating, heating of the welding electrodes 30 and 31 by the heating means (the heating wire 32 in the embodiment) may be continued or may be interrupted.
The secondary battery 10 is not limited to a lithium ion secondary battery, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge. Further, a capacitor may be used as the power storage device.

(Circle) the secondary battery 10 of embodiment may be mounted in a motor vehicle as a vehicle power supply device, and may be mounted in an industrial vehicle. Further, the present invention may be applied to a stationary power storage device.
The welding apparatus and the welding method of the embodiment are not limited to the laminated secondary battery 10, and the electrode and the conductive material are wound in a wound secondary battery in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers. You may apply when joining a member.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 15 ... Positive electrode, 16 ... Negative electrode, 20 ... Positive electrode current collection tab, 23 ... Negative electrode current collection tab, 24 ... Positive electrode conductive member, 25 ... Negative electrode conductive member, 30, 31 ... Electrode for welding, 32 ... heating wire, 33, 34 ... energization part, 35 ... moving mechanism.

Claims (8)

An electrode of a power storage device;
It is a welding method for resistance welding a conductive member that exchanges electricity with the electrode of the power storage device,
The heating means is wound to the welding electrode by heating the welding electrode, the heated welding electrodes is brought into contact with the electrodes of the conductive member and the electrical storage device, the welding electrode, the conductive member and said energy storage A welding method in which resistance welding is performed by energizing the electrodes of the apparatus.   An electrode of a power storage device;
  It is a welding method for resistance welding a conductive member that exchanges electricity with the electrode of the power storage device,
  The welding electrode is heated by a heating means, the heated welding electrode is brought into contact with the conductive member and the electrode of the power storage device, and the welding electrode, the conductive member and the electrode of the power storage device are energized and resistance welding is performed. A welding method for stopping energization to the welding electrode, the conductive member, and the electrode of the power storage device in a state in which heating by the heating means is continued. The welding method according to claim 1, wherein the resistance welding is performed in a state where the welding electrode is kept warm. The welding method according to claim 3 , wherein the welding electrode is kept at a temperature equal to or lower than a melting temperature of the electrode of the power storage device. An electrode of a power storage device;
A welding device for resistance welding a conductive member that exchanges electricity with an electrode of the power storage device;
An electrode for the power storage device, and a welding electrode for energizing the conductive member;
A moving mechanism for bringing the welding electrode into contact with the electrode of the power storage device and the conductive member;
Heating means for heating the welding electrode ,
The heating means is a welding apparatus wound around the welding electrode . Voltage applying means for applying a voltage to the welding electrode;
The welding apparatus according to claim 5 , further comprising: an energy applying unit that applies heating energy to the heating unit.   An electrode of a power storage device;
  A welding device for resistance welding a conductive member that exchanges electricity with an electrode of the power storage device;
  An electrode for the power storage device, and a welding electrode for energizing the conductive member;
  A moving mechanism for bringing the welding electrode into contact with the electrode of the power storage device and the conductive member;
  Heating means for heating the welding electrode;
  Energy applying means for applying heating energy to the heating means;
  Voltage application means for applying a voltage to the welding electrode,
  The energy application means is for applying energy for heating to the heating means prior to application of voltage by the voltage application means,
  The voltage application means is a welding apparatus for starting and stopping application of a voltage to the welding electrode when the energy application means is in a state where energy for heating is applied to the heating means. The welding apparatus according to claim 6 or 7 , wherein the energy applying unit applies electric energy to the heating unit.