JPH1031995A - Lead-through battery penetration welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a penetrative welding method to generate inter-cell connection of a lead-acid battery, with which it is possible to eliminate defects in the welds of the battery and provide an excellent anti-corrosiveness and mechanical strength. SOLUTION: The bulkhead cross-section of a through hole internal wall which is initially in the condition near the right angle is made V-shape. Concretely, a penetrative welding is performed using a battery jar to meet the relations that the angle θ formed by the through hole internal wall 14 to the external wall 15 of bulkhead is under 90 deg. and that the ratio P=θ/θ' is 0.75<=P<=1.00, refer to the illustration beside, where θ' is the inclining angle of the projecting part of an electrode for welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting cells of a lead battery.

[0002]

2. Description of the Related Art Conventionally, several methods have been used for connection between cells of a lead battery. In the case of a recent lead-acid battery for automobiles, for example, Japanese Patent Publication No. 2-121257 discloses the method. In most cases, the partition wall penetration method (through partition method) is used. This through-partition method connects the electrode groups in adjacent cells so as to penetrate the partition wall between the cells. Compared with the conventional partition-over method, the conductor required for connection is shorter. Therefore, the voltage characteristics are improved, and the amount of the lead alloy used can be significantly reduced.

FIG. 2 is a sectional view of a welded portion by the partition wall penetration method. The poles 2 previously welded to the ears 1 of a plurality of electrode plates constituting the electrode plate group are welded so as to penetrate the partition walls 4 between the cells 3. In this welding, resistance welding is used because it secures the characteristics required for the welded portion and is excellent in mass productivity. Hereinafter, in the present application, the resistance welding method of the partition wall penetration method will be referred to as a penetration welding method.

FIG. 3 shows the process of penetration welding. First, as shown in FIG.
The poles 2 are arranged on both sides of the partition wall 4 so as to sandwich the circular through-hole 5 provided in the above, and the electrodes 8 supported by the jaws 6 and having the projections 7 are circumscribed to the pole poles. Then, the bipolar pole 2 is pressed by the electrode 8 and deformed into the through-hole 5, and is brought into contact inside the through-hole 5 as shown in FIG. Thereafter, a predetermined welding current is applied to the electrode 8 to perform resistance welding. Thereby, the welded portion in the state shown in FIG. 2 is obtained. Prior to this penetration welding, when a through hole is opened in a partition wall, the most common method is a method of simply punching out using a circular male mold and a female mold having a predetermined diameter. The cross section is as shown in FIG. That is, the through hole has a columnar shape, and the angle between the inner wall surface 14 of the through hole and the outer wall surface 15 of the partition wall is almost a right angle.

[0005]

However, in the case where the above-mentioned conventional partition wall having a through hole is subjected to through welding, when the pole is brought into contact with the inside of the through hole, as shown in FIG.
As shown in (b), a space 12 is created. In this state, if a welding current is applied to melt the poles, most of the air in the space 12 is caught in the molten metal and remains as a defect called a blowhole after the end of energization. In addition, the penetration welding has an extremely short welding time of about 0.1 second, and has a peculiarity of welding a pole to be welded through a through hole, so that a defect due to “scattering” easily occurs. The “scatter” is a defect that is generated by ejecting a lead alloy which has a boiling state due to abnormally rapid heat generation from a nugget, and is greatly influenced by a contact area (contact resistance) of the bipolar poles. In the case of a through-hole having a conventional shape, the pole is forced into the through-hole, and the contact state between the poles inside the through-hole is likely to be unstable. Therefore, the contact resistance varies, causing abnormal heat generation and “scattering” easily occurring. In order to reduce the space 12 shown in FIG. 3 (b), a method of reducing the thickness of the partition wall 4 may be considered. However, the partition wall 4 is easily deformed by heat generated at the time of welding, which hinders a sealing operation in a later process. . Therefore, since it is necessary to maintain a certain level of strength, it is difficult to reduce the thickness of the partition walls. On the other hand, if the thickness is increased, "scatter" is likely to occur as described above. Therefore, the thickness of the partition walls 12 has a subtle problem, and is one of the factors that cause defects.

Needless to say, the degree of influence of the existence of such a defect differs depending on the size of the defect. However, in recent years, the use environment of the battery has deteriorated. However, even defects that have been considered to have no effect conventionally cannot be ignored.

[0007]

In order to solve the above-mentioned problems, the present invention changes the shape of the cross-section of the partition wall of the inner wall of the through hole from a nearly right angle to a V-shape. In particular,
As shown in FIG. 1, the inner wall surface 14 of the through hole and the outer wall surface 1 of the partition wall
5 is 90 ° or less, and the ratio P between the angle θ and the inclination angle θ ′ of the projection of the welding electrode is 0.75 ≦ P
≤ 1.00.

FIG. 5 shows a state immediately before the application of a welding current at the time of penetration welding using a battery case having a through hole according to the present invention.

In the above method, when a through-hole having a V-shaped cross section is used, the bipolar pole inside the through-hole at the time of through-welding has a smaller gap 12 than the conventional one when pressurized before energization, Helps control blowholes. Also, the contact state between the poles (that is, contact resistance) is stabilized,
Rapid melting of lead hardly occurs during welding,
Helps prevent "scatter".

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the cross section of the inner wall portion of the through hole of the partition is V-shaped, and the ratio of the inclination angle (.theta. ') Of this cross section to the inclination angle (.theta.) Of the electrode projection portion is P = .theta. / Θ 'is 0.7
The lead-acid battery is subjected to penetration welding in a range of 5 to 1.00.

By doing so, the occurrence of blow holes is suppressed, the contact between the poles is stabilized, the rapid melting of lead during welding is less likely to occur, and defects due to "scatter" are suppressed. .

[0012]

An embodiment of the present invention will be described.

The battery case having the through-hole of the present invention was formed by injection, and a V-shaped through-hole was formed at the same time. The material at this time was polypropylene (PP), the thickness of the partition wall was 1.5 mm, and the diameter of the through hole was 9.5 mm.
And The poles tested were manufactured by the cast-on-strap (COS) method, and the material was Pb-1.65.
Sb-0.05 As. The width and height of the pole are 20 mm and 25 mm, respectively, and the thickness is 4.5 mm. In addition, since the pole has age hardening property and the hardness changes with the passage of time, in order to minimize the variation in the welding result, the welding at the time when 3 minutes have passed after the COS was used.

Three types of electrodes A, B, and C are used for welding, and each of them is constituted by a core portion made of a Cu-Be alloy and a pad portion made of an oil-containing acetal resin. The A electrode has an outer diameter of 16 mm, a core diameter of 12 mm, and a frustoconical projection with a tip diameter of 2 mm, a base diameter of 9.2 mm, and a height of 2 mm at the center on the side facing the pole. It was manufactured so that the inclination angle of the projection was 30 °.
The B electrode has an outer diameter of 16 mm like the A electrode and a core diameter of 1
The diameter of the protruding tip of the truncated cone is 6 mm, that of the base is 10 mm, and the height is 2 mm. In this case, the inclination angle of the projection is set to 45 °. The outer diameter of the C electrode is 16 mm, the diameter of the core is 12 mm, the diameter of the tip of the truncated cone is 6 mm, and that of the base is 8.4 m.
m, the height is 2 mm, and the inclination angle of the projection is set to 60 °. Each electrode is a ring having a pad thickness of 4 mm, and is used integrally with the core. Both electrodes are attached to a jaw (electrode holder) so that the position of the center of the truncated conical projection coincides with that of the through hole.

The welding machine used in the experiment was of a single-phase AC type, and the maximum welding current was 20 kA. The electrodes are pressurized by an air pressurization method using an air cylinder, and the maximum pressing force is 2t.

The welding results were evaluated by the state of voids in the nugget due to "scatter" and the welding strength. The state of generation of the voids was examined by a radiation transmission test using γ-ray irradiation from a direction perpendicular to the partition walls. The welding strength was evaluated by a torque value (kg · cm) when one pole was fixed after welding and the other pole was twisted by sliding along the partition wall. The required strength at this time was 70 kg · cm or more. The number of samples (the number of welds) subjected to the evaluation was four per condition (that is, n = 4).

Since the ratio P between the angles θ and θ ′ greatly affects the welding result, an experiment was conducted by changing the ratio P between the angles θ and θ ′ shown in FIG. The relationship between blowholes and the state of occurrence of cracks was examined. The welding conditions in this case were as follows: energizing current, energizing time (frequency is controlled because an AC power supply is used), and applied pressure are 9.5 kA and 4 cycles (0.08 sec. Because the power supply is 50 Hz). ) And 700 kg. Table 1 shows the results. As a result of evaluating the gap determined to be a blow hole inside the nugget, there is no gap,
The mark indicates the presence of a small gap, and the cross indicates the presence of a large gap. In addition, in the results of the evaluation of the deformation of the partition wall, a circle indicates deformation within 1 mm, a triangle indicates deformation within 1.5 mm, and
The mark indicates a deformation of 1.5 mm or more. As the through-hole inclination angle θ becomes sharper, the welding strength increases and the electrode A
40 ° to 30 ° in the case of, 50 ° to 45 ° in the case of the electrode B,
In the case of the electrode C, it reaches a maximum at 80 ° and then decreases. In addition, a similar tendency is exhibited for the occurrence of blowholes. In the deformation of the partition wall, as described above, the through-hole inclination angle θ becomes sharp (the partition wall thickness of the welded portion becomes thin).
Then, the deformation becomes large. Therefore, considering the overall evaluation, it is necessary to select a condition in a range where the ratio P between the through-hole inclination angle θ and the projection inclination angle θ ′ of the welding electrode is within a range of 0.75 ≦ P ≦ 1.00.

[0018]

[Table 1]

From the above, it has been found that the present invention improves the quality of the through-welded portion of the lead-acid battery.

[0020]

As described above, since the through-hole of the battery case for a lead-acid battery according to the present invention has a V-shaped cross section, the blow-holes existing inside the welding are different from the case where the conventional through-hole is used. The number of occurrences of cracks and cracks is suppressed, the quality of the welded part is significantly increased, and the reliability of the lead storage battery is improved.
Excellent in terms of industrial value.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a through hole according to the present invention.

FIG. 2 is a diagram showing an inter-cell connection method using a partition penetration method.

FIG. 3 is a view showing a process of penetration welding by a conventional method.

FIG. 4 is a view showing a cross section of a through hole conventionally used.

FIG. 5 is a view showing a process of penetration welding according to the present invention.

[Explanation of symbols]

1 is an ear, 2 is a pole, 3 is a cell, 4 is a partition, 5 is a through hole,
6 is a jaw, 7 is an electrode projection, 8 is an electrode, 9 is a contact surface of the pole, 10 is a nugget, 11 is an indentation, 12 is a space, 13 is a void, 14 is an inner wall surface of a through hole, and 15 is an outer wall surface of a partition wall.

Claims (1)

[Claims] 1. A cross section of an inner wall portion of a through-hole when a positive electrode and a negative electrode column of an adjacent electrode plate group are opposed to each other through a through-hole of a partition wall and pressurized with electrodes from both sides and resistance-welded by energization. V
And a ratio P = θ / θ ′ between the inclination angle (θ ′) of the cross section and the inclination angle (θ) of the electrode projection portion is 0.75 or more and 1.00.
A penetration welding method for a lead-acid battery, wherein the method is in the following range.