JPH11162448A - Manufacturing method of lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To weld posts within adjacent cells in a through hole with no defects by forming the tip of a welding electrode in conical trapezoid of first and second two steps, using the bottom surface of the first conical trapezoid as the top surface of the second conical trapezoid, forming the bottom angle of the second conical trapezoid in the specified range, and limiting the relation between the tip diameter of the first conical trapezoid and the through hole diameter to the specified range. SOLUTION: An electrode 8 is brought into contact with a through hole 5 through a partition wall 4 by pushing a post, and has the tip of a first conical trapezoid 7 whose diameter D is smaller than the diameter D' of the through hole 5. The post of the electrode 8 is pushed in the through hole 5 by applying the constant pressure, and since the electrode 8 follows in the expansion 1 contraction caused by temperature change in welding or by melting/solidifying of the post, an inclined part 14 serving as a wedge is formed in the electrode 8. The bottom angle 8 of a second conical trapezoid is made 5-20 deg. to ensure the sufficient pressure contact force and forging pressure action between the post and the partition wall 4. By making the tip diameter D of the electrode 8 to be 60-80% of the diameter D' of the through hole 5, blowhole is prevented, and unstable contact between adjacent posts caused by deformation producing when the post is pushed in the through hole 5 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, several methods have been used for connection between cells of a lead storage battery. Typical examples are a partition over system and a partition penetrating system (through partition system). In the case of recent lead-acid batteries for automobiles, a through partition method (disclosed in Japanese Patent Publication No. 2-121257)
Adoption is dominant. In this through partition method, poles in adjacent cells are welded to each other through a partition wall through a partition wall. This has the advantage that, compared to the conventionally used over partition wall system, the conductor required for connection is shortened, the voltage characteristics are improved, and the amount of lead alloy used can be significantly reduced. .

FIG. 2 is a cross-sectional view of a welded portion after the through partition method is performed. The pole 2 is the ear 1 of a plurality of pole plates
Are integrated by welding. The pole 2 is welded in the through hole of the partition wall 4 between the adjacent cells 3. In this method, resistance welding is employed because the characteristics required for the welded portion are secured and the mass productivity is excellent. Hereinafter, in the present invention, the through-partition resistance welding is referred to as through welding.

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 partition wall 4. Next, an electrode 8 supported by the jaw 6 and having a projection (a projection 15 in FIG. 4) at the tip is circumscribed to the bipolar pole. Then, the bipolar pole 2 is pressurized by the electrode 8 and deformed into the through hole 5, and as shown in FIG.
The contact is made inside the through hole 5. Thereafter, a predetermined welding current is applied to the electrode 8 to perform resistance welding on the contact surface 9. Thereby, the welded portion in the state shown in FIG. 2 is obtained. Indentation 1 on which the tip shape of the electrode for penetration welding is transferred to the side surface of the welded part
1 is seen. Since a high pressing force is applied to the electrode 8 used for this penetration welding, a material having high hardness and hardly alloying with lead is selected. In addition, the pole 2
(Lead alloy) is soft, so that a large contact area can be easily obtained at the time of welding, and the contact resistance is small and it is difficult to generate heat. Therefore, it is necessary to use a material having a low thermal conductivity for the electrode 8 to prevent heat dissipation. Therefore, a copper alloy containing cobalt or beryllium is usually used for the penetration welding electrode 8. Although the shape of the electrode for penetration welding is various, in general, a flat shape, a spherical shape, a truncated cone shape, a point shape, and the like are used. Among them, the electrode 8 having the truncated conical projection 15 shown in FIG. 4 is most frequently used (Japanese Patent Publication No. 2-121257).

[0005]

However, when the above-described conventional through-welding electrode 8 is used, the pole 2 in the through-hole 5 is not used.
At the stage where they are brought into contact with each other, as shown in FIG.
2 results. If a welding current is applied to melt the pole 2 in this state, most of the air in the space 12 will be caught in the molten metal, and will remain as a defect called a blowhole after the end of energization. In general, the penetration welding is extremely short in welding time of about 0.1 s, and the pole column 2 which is an object to be welded is
Is welded in the through hole 5 of the partition wall 4 made of resin. As a result, rapid temperature rise (heat generation), melting and vaporization of the resin cannot be avoided, and “splashing” of the molten metal occurs.
Voids in the weld due to cracks are likely to occur. In other words, abnormally rapid heat generation brings the molten lead into a boiling state and ejects it from the nugget 10 to generate welding defects (voids in the welded portion). In the case of a through-hole having a conventional shape, the pole is forced into the through-hole, and depending on the variation in the thickness of the pole 2, the contact state between the poles inside the through-hole tends to become unstable. Therefore, it is difficult to control the contact area (contact resistance) between the poles during welding. Therefore, the contact resistance varies, causing abnormal heat generation and “scattering”.
5% when the lead alloy melted by welding solidifies
A degree of coagulation shrinkage occurs. Since the solidification proceeds from the outside of the fusion zone, a cavity defect (the void 13 shown in FIG. 2) corresponding to the contraction exists in the center. Such a defect is called “close”. Void 1 considering the mechanism of solidification
The shape of 3 is difficult to be spherical, and the space 1 is actually narrow.
In many cases, it occurs as 3 and its inner surface is not smooth, but rather has a three-dimensionally complicated shape. On the other hand, when the gap 13 is generated by “scattering”, the pressure of the boiling molten metal exceeds the pressure applied by the electrode 8 and the boiling molten metal jumps out. It has a wider space than “close”.

It goes without saying that the presence of the above-mentioned defects affects the function required for the welded portion depending on the size of the defects. However, the recent deterioration of the battery usage environment, especially for automotive lead batteries mounted on automobiles,
Due to the high temperature of the engine room, even defects that were previously thought to have no effect can not be ignored. The problem to be solved by the present invention is to suppress defects in a welded portion obtained by welding pole poles in adjacent cells via a partition wall in a through hole of the partition wall.

[0007]

According to the present invention, there is provided a method of manufacturing a lead-acid battery according to the present invention, in which poles 2 in cells 3 adjacent to each other via a partition 4 are welded through a through hole 5 in the partition 4. Is an integral shape in which the tip of the welding electrode 8 is formed by stacking two truncated cones, and the lower surface of the most advanced (first) truncated cone 7 is
And the bottom angle (θ) of the vertical section of the second truncated cone 7 ′ is 5 ° to 20 °,
The diameter (D) of the tip of the truncated cone 7 is the diameter of the through hole 5 (D ')
60 to 80%. The welding conditions for realizing the above-described method for manufacturing a lead storage battery of the present invention are somewhat affected by the mechanical and electrical characteristics of the welding machine to be used. It is possible. The general conditions include, for example, using a single-phase AC welding machine (air pressurization method), a welding current of 6 to 12 kA, a welding time of 0.08 to 0.1 seconds, and a pressing force of 650 on the pole. ~ 7
50 kg.

FIG. 1 shows an example of the shape of the electrode 8 according to the present invention. The electrode 8 has a tip diameter of the first truncated conical shape 7 smaller than the diameter (D ′) of the through-hole 5 because the poles 2 arranged via the partition walls 4 in the through-hole 5 are pushed into contact with each other. (D). Further, the first function of bringing the poles into contact with each other with a more stable pressing force than before so as to obtain a substantially constant pole pole contact state before the welding process, and the above-mentioned "shrinkage"
A second frusto-conical shape 7 ′ also has a portion (inclined portion 14) having a second function of crushing even if it occurs. The first function is that the electrode 8 forms the pole 2 through the through-hole 5.
The inclination portion 14 functions as a wedge when applying a constant pressing force to be pushed into the inside, which is realized by allowing the variation in the thickness of the pole 2 by the height of the second truncated cone 7 '. Therefore, a more stable contact state of the pole can be obtained before the welding process than before. The second function is realized by ensuring that the electrode 8 follows the temperature change during welding and the expansion and contraction caused by the melting and solidification of the pole 2 by the inclined portion 14 serving as a wedge. I do. That is, an action (forging action) of crushing a void (shrinkage) generated due to solidification of the molten portion (nugget) by the height of the second truncated cone 7 'can be realized.

The base angle (θ) of the vertical section of the second truncated cone is
If it is too large, it will be difficult to secure the pressure contact force between the pole 2 and the partition 4, and there is a possibility that a liquid junction of the electrolytic solution may occur between adjacent cells. On the other hand, if θ is too small, the movement of the electrode 8 is hindered, and a sufficient forging action cannot be obtained. Therefore, an appropriate angle is required. An appropriate angle is 5 ° to 20 ° based on experimental data described later. In penetration welding, the electrode 8
The relationship between the diameter (D) of the tip and the diameter (D ′) of the through hole 5 is also important. If D 'is extremely larger than D, welding will be performed at a locally large temperature rise, and the above-mentioned "scatter" will easily occur. Further, since the space 12 in FIG. 3B becomes large, there is a concern about occurrence of blow holes. On the other hand, if D ′ is extremely small to the extent that D becomes substantially the same as D, when the pole 2 is pushed into the through hole 5 by the tip of the electrode 8, The partition walls 4 may be excessively deformed by a large stress, and the contact state between the adjacent poles 2 may be unstable. Therefore, from the experimental data described later, it is preferable that D is 60 to 80% of D '.

As described above, when the welding electrode 8 having a shape optimized for each of the above-described factors is used, the bipolar pole 2 inside the through hole 5 at the time of penetration welding can be used in a conventional manner during pressurization before energization. The voids 12 are smaller than those in the case, which helps to suppress blow holes. In addition, the contact state (that is, contact resistance) between the pole columns 2 is stabilized, so that rapid melting of lead during welding is less likely to occur, which helps to prevent “scatter”. Furthermore, following the instantaneous expansion and contraction of the pole 2, it becomes possible to crush “retraction”.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The material of the welding electrode 8 according to the present invention is made of Cu-
2.0Co-1.5Be alloy (trade name Mallory 100)
And Diameter (D) of the tip surface of the first truncated cone 7 of the electrode 8
Is 16 mm, the height is 1.5 mm, and the second truncated cone 7 ′
Has a bottom angle (θ) of 15 °. The partition walls used were made of polypropylene (PP) and had a thickness of 1.
5 mm, the diameter of the through hole (D ') was 9.6 mm, and D /
D ′ × 100 = 60%. The pole 2 is manufactured by a known cast-on-strap (COS) method, and is made of Pb-1.65Sb-0.05As. The width and height of the pole are 20 mm and 25 mm, respectively, and the thickness is 4.5 mm. The pole 2 has age hardening properties,
Since 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 step was used. The welding device uses a single-phase alternating current welding machine (air pressurization method using an air cylinder). The maximum current of this welding machine is 20 kA, and the maximum pressure is 2 t. Welding current is 10 kA, welding time is 0.0
For 8 seconds (5 cycles), the pressure applied to the pole was set to 700 kg.

[0012] The present invention can solve the problem of the pole column material, thickness, and welding conditions other than those in the present example, as long as they are conditions generally employed in the manufacture of a lead storage battery.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The value of .theta.
The welding state was evaluated when the value of D / D ′ × 100 was set to 50 to 90% at 25 °. Welding state is "scattered""closed"
Judgment was made based on the state of generation of voids inside the nugget due to blowholes and welding strength, and the deformation of the partition walls and poles was visually observed and comprehensively evaluated. 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. This radiation transmission test means that when there is a defect in the welded part when strong radiation such as γ-rays is irradiated, the amount of transmission in that part increases, and only this part on the photosensitive film installed under the test piece This is a method in which the presence of a defect is discriminated by shading in color as the degree of exposure increases. Further, the welding strength was evaluated by a torque value (kg · cm) when one pole was fixed immediately after welding and the other pole was twisted by sliding along the partition wall 4. The required strength at this time is 65k
g / cm or more (Empirically, 60 kg · cm is a strength that does not cause any problem with respect to mechanical stress such as vibration applied to a vehicle-mounted battery. Was set as a reference). The number of samples (the number of welds) subjected to the evaluation was four per condition (that is, n = 4).

The results are shown in Tables 1 to 3. In the results of evaluating the voids determined to be defects inside the nugget, the mark ○ indicates no void, the mark Δ indicates the presence of voids within 0.5 mm in diameter, and the mark × indicates the presence of voids exceeding 0.5 mm in diameter. . Also,
The deformation due to the pressure was evaluated based on the deformation of the partition wall after welding. Originally, the partition wall is straight, but it is deformed to the left or right depending on the quality of the welding condition. Therefore, the deviation from the original position was used as an evaluation criterion. ○ is 1
Deformation within 1.0mm, △ mark exceeds 1.0mm and 1.5mm
And the crosses indicate deformations exceeding 1.5 mm. Experience has shown that this deformation amount has almost no problem if it is within 1.5 mm. As can be seen from Tables 1 to 3, when the electrode projection diameter is 50% and 90% of the diameter of the through hole, the welding strength is relatively small as compared with the others, and there is a tendency for defects to occur. When the angle θ is in the range of 5 ° or more and 20 ° or less, all the evaluation items such as the welding strength, the state of occurrence of defects, and the deformation of the partition wall were satisfied.
Therefore, the diameter of the electrode projection is 60 times the diameter of the through hole.
% To 80%, and the angle of inclination from the projection to the outer periphery of the electrode must be 5 ° to 20 °.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

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

[0019]

According to the present invention, it is possible to suppress a defect in a welded portion obtained by a step of pressing and welding an electrode column of an adjacent lead storage battery at a tip of an electrode through a through hole in a partition wall. Was completed.

[Brief description of the drawings]

FIG. 1 is a view showing an electrode for penetration welding and a partition according to the present invention.

FIG. 2 is a diagram showing a state after cell-to-cell connection by a partition penetration method.

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

FIG. 4 is a view showing a conventional electrode for penetration welding and a partition wall.

[Explanation of Codes] Ear 2. Pole 3 Cell 4. Partition wall 5. Through hole 6. Joe 7. First frustoconical shape 7 '. 7. second truncated cone Electrode 9. Contact surface 10. Nugget 11. Indentation 12. Space 13. Void 14. Incline 15. Protrusion

Claims (1)

[Claims] 1. A method for manufacturing a lead-acid battery in which poles in adjacent cells are welded through a partition wall through a partition wall, wherein the tip of a welding electrode has an integral shape in which two truncated cones are stacked, The lowermost (first) frustoconical lower surface is the same as the upper surface of the second frustoconical shape, and the bottom angle (θ) of the vertical section of the second frustoconical shape is 5 ° to 20 °
゜, the diameter (D) of the first frustoconical tip is the diameter of the through hole (D ′)
A method for producing a lead-acid battery, characterized in that the content is 60 to 80% of the above.