JP2000351078A - Welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of burrs by forming a hole of a specified diameter in advance at a location to be welded of a metal plate held by two metal plates, and pouring a molten metal generated during the spot welding in the hole. SOLUTION: At least three metal plates overlap and are spot welded. A copper alloy movable plate connection part 33, a connection part of a bimetal plate having a hole 45 therein, and a copper alloy second external connection terminal 50 overlap. Electrodes 71, 72 of a spot welding machine are located on the control line of the hole 45. The connection part 33 and the second external connection terminal 50 are pressed by the electrodes 71, 72. A metal stock of a welded part is melted through the heat generation of the welding current flowing between the electrodes 71, 72. The molten metal flows into the hole 45 and is entrapped, and prevented from leaking outward to form burrs 80. A projecting part 33a located in the hole 45 is formed on the connection part 33, the connection part 33 is brought close to the second external connection terminal 50 by the height of the projecting part 33a to preferably reduce the electric resistance between the two.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method applied when three or more superposed metal plates are spot-welded to each other.

[0002]

2. Description of the Related Art A thermal protector of the type in which a contact is opened by utilizing a reversing operation of a bimetal plate is widely used as a protection means for a secondary battery pack built in a portable computer, for example. During the manufacturing process of this type of thermal protector, a welding process is performed in which an end of a bimetal plate and two metal plates made of a copper alloy or the like overlapped with the end sandwiched therebetween by spot welding. It is included.

[0003]

In the above welding process, the molten metal generated between the metal plates due to welding leaks outward through gaps between the metal plates and adheres as so-called burrs. Become. Burrs generated by the above welding,
It becomes an obstacle when inserting the assembled mechanism of the thermal protector into the case. Therefore, conventionally, a step of manually cutting off the burrs is provided as a step subsequent to the welding step, but this is a factor that reduces productivity. In addition, the occurrence of burrs makes it difficult to automate the process of inserting the assembled thermal protector into the case.

[0004] In view of such a situation, an object of the present invention is to provide:
An object of the present invention is to prevent molten metal from leaking during spot welding, in other words, to prevent the occurrence of burrs due to the molten metal leaking.

[0005]

The welding method according to the first invention is applied to spot welding three or more superposed metal plates to each other, and is sandwiched between two metal plates located outside. A hole having a predetermined diameter is previously formed in a portion to be welded of the metal plate thus formed, and molten metal generated during the spot welding is caused to flow into the hole. The welding method according to a second invention is the welding method according to the first invention, wherein the superposed metal plates are
It is characterized by a bimetal plate and two copper alloy plates sandwiching the bimetal plate.

[0006]

FIG. 1 is a longitudinal sectional view of a thermal protector to which a welding method according to the present invention is applied. FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG.
It is an arrow view. As shown in FIG. 1, this thermal protector has a movable plate 30, a bimetal plate 40, and a second external connection terminal 50 sequentially disposed on a support member 20 fixed to a fixed plate 10, and these are electrically insulated. It is configured to be housed in a case 60 made of a conductive resin.

The fixed plate 10 is made of a conductive material such as a copper alloy, and has a fixed contact 11 formed at a front end and a first external connection terminal 12 formed at a rear end. The support member 20 is made of an electrically insulating resin material, and has a convex portion 21 at a front end portion and a support portion 22 at a rear end portion.

The movable plate 30 is made of a material having conductivity and elasticity. As shown in FIG. 4, a movable portion 31, a support portion 32 extending from a rear end of the movable portion 31, and a support portion 32 are provided.
And a connecting portion 33 protruding from the rear end. The movable portion 31 is provided with a movable contact 36 at a distal end portion, forms an escape hole 37 at a position located closer to the support portion 32 than the movable contact 36, and furthermore, forms a support hole 3 at a central portion of the support portion 32.
8 are formed.

[0009] As shown in FIG.
It comprises a reversing operation part 41, a support part 42 extending from the rear end of the reversal operation part 41, and a connecting part 43 protruding from the rear end of the support part 42. This bimetal plate 40
Engagement projection 3 having a distal end formed at the distal end of movable plate 30
9, the support portion 42 and the connection portion 43 are superimposed on the support portion 32 and the connection portion 33 of the movable plate 30, respectively. Note that a support hole 44 corresponding to the support hole 38 of the movable plate 30 is formed in the center of the support portion 42.

The second external connection terminal 50 is formed by bending the end portion of a strip-shaped press plate into a substantially U-shaped cross section, and the lower surface of the end portion is in contact with the upper surface of the support portion 42 of the bimetal plate 40. It is arranged in a manner. Note that a support hole 51 is formed at the bent front end of the terminal 50.

As shown in FIG. 1, the movable plate 30, the bimetal plate 40 and the external connection terminal 50 have their support holes 38, 44 and 51 fitted in the support portions 22 of the support member 20, respectively. . Since the top of the support portion 22 is fitted to the large-diameter portion of the support hole 51 by heat deformation, the movable plate 30, the bimetal plate 40, and the external connection terminal 50
The support 22 is fixedly supported.

In this state, the movable contact 36 is pressed against the fixed contact 11 by the elasticity of the movable plate 30, and the projection 21 of the fixed plate 10 is located in the escape hole 37 of the movable plate 30. Then, as shown in FIG. 6 and FIG. 7 which is an enlarged cross-sectional view taken along the line CC, the connecting portion 43 of the bimetal plate 40 is superimposed on the connecting portion 33 of the movable plate 30, and the second portion is provided on the connecting portion 43. The non-bent portions of the external connection terminals 50 are overlapped.

The connecting portion 3 in the above-mentioned superposed state
3, 43 and the non-bent portion of the terminal 50 are spot-welded to each other. However, according to the welding method according to the present invention, prior to the spot welding, the connection portion 43 of the bimetal plate 40 has a predetermined diameter. Is formed (see FIG. 5). In this example, the diameter of the hole 45 is set to 0.5 mm.

At the time of spot welding, as shown in FIG. 7, the electrode 7 of the spot welding machine is placed on the center line of the hole 45.
The outer surfaces of the connection portion 33 and the non-bent portion of the terminal 50 are pressed by the electrodes 71 and 72. The point P in FIG. 6 is the center point of the pressure of the electrode 71. When the electrodes 71 and 72 are pressurized, these electrodes 7
The metal material of the welded portion is melted by the heat generated by the welding current flowing between the portions 1 and 72, and the molten metal flows into the hole 45 provided in the connection portion 43 and is confined.

If the hole 45 does not exist, there is no escape for the molten metal, and as shown by the chain line in FIG. The portion 43 and the second external connection terminal 50 are pushed out to the side of the portion to be welded through the joint. The extruded molten metal is fixed as burrs 80 around the bimetal plate 40.

The movable plate 30 and the second external connection terminals 50 are usually formed of a copper alloy. That is, for example, the movable plate 30 is formed of brass, and the second external connection terminal 50 is formed of beryllium copper. On the other hand, the bimetal plate 40 is formed of a material made of iron.

Therefore, the bimetal plate 40 is
And the second external connection terminal 50 has a higher electric resistance than that of the second external connection terminal 50.
The zero connection 43 melts the most.

As described above, according to the welding method according to the present invention, the hole 45 provided in the connection portion 43 of the bimetal plate 40 is provided.
Since the molten metal flows into the metal, there is no possibility that the molten metal leaks outward to form burrs. Therefore, the step of removing the burr is not required, and the productivity is improved. In addition, the mechanical part of the assembled thermal protector is connected to the case 6.
This facilitates the automation of the step of inserting into zero.

As shown in FIG. 6, the connecting portion 33 of the movable plate 30 has a projection 33a located in the hole 45.
Is formed. The convex portion 33a serves to make the connecting portion 33 and the second external connection terminal 50 closer to each other by the height thereof, and to further reduce the electric resistance between them.

Here, the operation of the thermal protector will be described. For example, when the thermal protector is incorporated in a battery pack of a portable computer (not shown), a load current of a secondary battery built in the battery pack flows between the terminals 12 and 50 via the movable plate 30. When the load current becomes abnormally large due to a load short circuit or the like, the movable plate 30 generates heat due to its internal resistance.
As a result, the temperature of the bimetal plate 40 increases.

When the temperature of the bimetal plate 40 reaches a predetermined reversal temperature, the reversing operation portion 41 of the bimetal plate 40 instantaneously reverses and deforms into a concave shape. The tip of the plate 40 rises. As a result, the distal end of the movable plate 30 is
The movable contact 36 is lifted through the fixed contact 1
1 so that the abnormal load current flowing between the terminals 12 and 50 is stopped. The first terminal 1
The rear ends of the second and second terminals 50 project outside the case 60. The inside of the opening of the case 60 from which the terminals 12 and 50 protrude is sealed with a resin 90.

The application of the welding method according to the present invention is not limited to the components of the thermal protector. In other words, the present invention is effective for any application in which three or more superposed metal plates need to be spot-welded to each other. When the number of the superposed metal plates is four or more, a hole corresponding to the hole 45 is formed in advance in a portion to be welded of the metal plate except for two metal plates located outside.

[0023]

According to the present invention, when three or more superposed metal plates are spot-welded to each other, a portion to be welded of the metal plate sandwiched between the two metal plates located outside is previously formed. A hole having a predetermined diameter is formed so that molten metal generated during the spot welding flows into the hole. Therefore, since the molten metal is confined in the hole, it is possible to prevent the molten metal from leaking outward to form burrs. If the welding method of the present invention is applied to, for example, the assembly of the thermal protector, the step of removing burrs is not required, and productivity is improved, and furthermore, the assembled mechanism of the thermal protector is inserted into the case. This makes it easier to automate the process. Further, when the burr is generated, an excessive current flows through the electrode of the spot welding machine. According to the present invention, since the excessive current does not occur, the electrode is prevented from being damaged. Therefore, the durability of the electrode is improved, and the maintenance thereof can be facilitated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a thermal protector to which a welding method according to the present invention is applied.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a view taken in the direction of arrow B in FIG. 1;

FIG. 4 is a plan view of a movable plate.

FIG. 5 is a plan view of a bimetal plate.

FIG. 6 is a perspective view showing a welded portion of the thermal protector.

FIG. 7 is a sectional view taken along line CC of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixed plate 11 Fixed contact 12 1st external connection terminal 20 Support member 21 Convex part 22 Prop part 30 Movable plate 33 Connection part 36 Contact 40 Bimetal plate 43 Connection part 45 hole 50 Second external connection terminal 60 Case 71, 72 Electrode 80 burr

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 2/34 H01M 2/34 A // B23K 103: 12 103: 18 F term (Reference) 4E001 AA03 CB02 CB05 CC04 DA01 DF09 4E065 EA04 5H022 AA19 BB16 CC09 KK01

Claims (2)

[Claims] The present invention is applied to spot welding of three or more superposed metal plates to each other, and a hole having a predetermined diameter is formed in a portion to be welded of a metal plate sandwiched between two metal plates located outside. Wherein the molten metal generated during the spot welding is caused to flow into the hole. 2. The welding method according to claim 1, wherein the superposed metal plates are a bimetal plate and two copper alloy plates sandwiching the bimetal plate.