GB2339330A

GB2339330A - Manufacture of lead acid batteries

Info

Publication number: GB2339330A
Application number: GB9813186A
Authority: GB
Inventors: Joseph Cain
Original assignee: Chloride Industrial Batteries Ltd
Current assignee: Chloride Industrial Batteries Ltd
Priority date: 1998-06-19
Filing date: 1998-06-19
Publication date: 2000-01-19
Anticipated expiration: 2018-06-19
Also published as: GB9813186D0; GB2339330B; GB2339330A9

Description

2339330 MANUFACTURE OF LEAD ACID BATTERIES This invention relates to the

manufacture of lead acid batteries.

In a conventional known process, positive and negative rectangular battery plates are prepared and assembled together in alternate side-by- side arrangement, each plate being separated by one or more sheets of separator material. Each plate has a lug extending from a side thereof and adjacent a corner. The plates are arranged so that the lugs of the positive plates are in one row and the lugs of the negative plates are in another row. The stack of plates and separator sheets so assembled is then placed in a cell of a suitable box, usually made of plastics material. The stack is initially pushed only partially into the cell so that the lugs project from the box. Next the box with the lugs projecting upwards is inverted and placed above a mould assembly containing moulding cavities one for each connecting strap to be formed. The lugs now project downwards into the respective mould cavity. Terminals, as required, are placed in the appropriate mould cavities and molten lead is then poured in and allowed to solidify to form connecting straps, whereby the lugs are connected together as required. The stacks, now provided with connecting straps are pushed fully into the box, the battery turned upright, a lid is secured to the box and the required amount of acid injected. The battery is then charged.

Just before the stage of placing the lugs into the or each mould cavity, the lug at each end of a row of lugs forming part of negative plates is bent inwards towards the next lug in the row by the operator. The requirement for this usually occurs when the total number of negative plates in a stack is one more than the number of positive plates. This bending is to ensure that the end lug is completely surrounded by lead of the connecting strap, thereby ensuring good electrical contact between lug and strap, and does not contact the edge of the mould cavity, especially if it had previously been bent outwards accidentally. However, although the material of the lug (mainly lead) is very ductile, it can still "spring back" and interfere with the cavity edge. Alternately the lug may be bent too much, and damage may be caused to the plate adjacent the base of the lug through displacement of the active material of the plate. Further, the end of the 2 lug, if bent too much, may not enter the mould cavity sufficiently with the result that the lug does not project into the lead of the connecting strap by the required amount.

It is an object of the present invention to overcome or substantially reduce the effects of the above disadvantages.

In -accordance with a first aspect of the invention a method of manufacturing a lead acid battery comprises positioning a row of lugs of battery plates above a mould cavity, the lugs projecting generally downwardly, providing a ramp surface at an edge of the mould cavity, lowering the row of lugs into the cavity including simultaneously lowering a lug at one end of the row against the ramp surface to cause said lug at one end to bend a controlled amount towards the next adjacent lug in the row and thereby be in a predetermined position relative to said next adjacent lug, pouring molten lead into the mould cavity and around the lugs thereby covering a predetermined amount thereof, allowing the lead to solidify to form a connecting strap for the lugs and thereby hold the end lug in said predetermined position.

Subsequently the row of lugs with the connecting strap now attached is raised so that the connecting strap moves upwardly from the mould cavity and arranging that the ramp surface moves simultaneously to allow unimpeded movement of the strap.

Two ramp surfaces may be provided, each one positioned to cause the bending of lugs at opposite ends of a row of lugs of plates of the same polarity, and the two ramp surfaces may both move simultaneously with the raising of the row of lugs and the connecting strap so formed attached thereto to allow unimpeded movement of the strap.

In accordance with another aspect of the invention an apparatus for forming a connecting strap for a row of lugs of battery plates of the same polarity comprises a mould cavity, a ramp surface positioned at an edge of the mould cavity to be engaged by a generally-downwardly projecting lug at the end of the row whereby on movement of the row of lugs into the cavity the said lug at the end of the row is caused to be bent by engagement with the ramp surface a 3 controlled amount towards the next adjacent lug in the row and thereby be in a predetermined position relative to said next adjacent lug.

The ramp surface may be provided on a deflector and two deflectors each having a ramp surface may be provided adjacent a mould cavity, each ramp surface being capable of being engaged by one of two lugs, one at each end of the row of lugs.

Preferably the or each deflector is mounted, and preferably pivotally mounted, to be capable of moving into position at an edge of the mould cavity where it is engageable by the end lug of the row of lugs and to be capable of moving out of said position to allow unimpeded movement of a connecting strap connected to the row of lugs. Preferably the deflector is mounted whereby the movement of the deflector is simultaneous with the movement of the row of lugs out of the cavity.

The or each deflector may be mounted at an end of a member or an arm capable of rotating about a pivot mounted at the side of a mould assembly including the or each mould cavity.

Two embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:- Figure 1 shows a horizontal cross-sectional view of a battery box and some battery plates, the box and plates being inverted ready for lowering towards a mould assembly; Figure 2 shows a side view of part of a battery plate; Figure 3 shows a plan view of a mould assembly for casting seven connecting straps; Figure 4 shows a side view of the mould assembly shown in Figure 3; Figure 5 shows a cross-seGtion on line A-A of Figure 3 with the lugs of the plates connected by means of a connecting strap; Figure 6 shows a view similar to that in Figure 5 but with the plates, lugs and connecting strap being lifted from the mould assembly; 4 Figures 7-11 show a cross-sectional simplified diagrammatic view of the five stages of casting a connecting strap to the lugs of battery plates.

The apparatus of the first embodiment shown particularly in Figures 3-6 is used in the manufacture of a 12-volt battery as shown in Figures 1 and 2. This battery comprises a rectangular box 2 being divided into six cells A, B, C, D, E and F as shown, the box 2 and cell walls 3 being moulded from suitable plastics material, e g ABS. Each cell holds an assembly of six negative electrode plates 4 and five positive electrode plates 5 arranged alternately in a stack, each plate being separated from the next by sheets of separator material 6. Each plate 4 or 5 is generally rectangular and is provided wfth an upstanding lug 7 (see Figure 2). In each cell the lugs are arranged in rows depending on the polarity of the plate of which they form part and attached together by means of connecting straps 19. The apparatus of the present invention specifically relates to the forming of these connecting straps.

During manufacture the positive and negative plates and the separator sheets are assembled together in a stack and positioned in the cells of the battery box 2. The stack is not fully inserted in fts cell so the lugs and upper parts of the plates 4 and 5 are positioned proud of the box 2. The whole assembly is then inverted.

The box with the lugs extending downwardly is subsequently lowered towards the mould cavities 9 of the mould assembly shown in Figures 3 and 4 so that the connecting straps may be formed as required around the ends of the lugs.

As can be seen in Figure 1 the lugs in cell A for the positive plates are arranged in a row at the left-hand side of the cell in its inverted position. These lugs need to be connected together by a connecting strap and to the positive terminal 10 of the battery. The lugs of the negative plates at the right-hand side of the cell A need to be connected together and to the lugs of the positive plates located in the adjacent cell B. The lugs of the negative plates located in cell B need to be connected together and to the lugs of the positive plates located in cell C. The lugs of the negative plates located in cell C need to be connected together and to the lugs of the positive plates in cell D. The lugs of the negative plates in cell D need to be connected together and to the lugs of the positive plates in cell E. The lugs of the negative plates in cell E need to be connected together and to the lugs of the positive plates in cell F. The lugs of the negative plates in,cell F need to be connected together and to the negative battery terminal 30. The mould cavities of the mould assembly shown in Figure 3 which forms the connecting straps are arranged in accordance with these requirements.

Since there is one more negative plate than positive plates in a cell the outer plates, i e those closer to the cell wall, are always negative. Thus the lugs 7 of negative plates 4 are at the ends of a row and where these are to be located at the edge of a mould cavity 9 there is a need for them to be bent inwards. This bending is achieved by means of deflectors 11 each having a ramp surface 12 the base of which overlies the edge at the appropriate mould cavity. The deflectors 11 are each positioned at the ends of suitably cranked arms 13 (see Figures 3 and 4) mounted on pivots 14 at the sides of the mould assembly. Grub screws 17 are positioned in part of each arm extending down the sides of the mould assembly to allow adjustment. The arms are all arranged so that each deflector swings away from the respective mould cavity to allow the connecting straps formed on the lugs to be lifted clear.

The mould cavity 9B forming the connecting strap for connecting the lug 7 of the negative plates 5 in cell F to each other and to the negative terminal 30 has two deflectors 11, one at each side of the mould cavity. Each deflector is connected to a respective arm 13A or 13B. The arm numbered 13A is L-shaped in plan to avoid the mould cavity 9A for forming the connecting strap for connecting the lugs of the positive plates in cell A to each other and to the positive terminal 10. The arm 13A is also cranked (as seen in Figure 5) and mounted on a pivot 14A at the side of the mould assembly appearing at the top of Figure 3. The other arm numbered 13B is straight in plan, is cranked and mounted on a pivot 14B at the side of the mould assembly appearing at the foot 6 of Figure 3.

The mould cavity 9C for forming the connecting strap for connecting the lugs of the negative plates of cell A together and to the lugs of the positive plates of cell B, lies alongside a similarly shaped mould cavity 9D for forming the connecting strap for connecting the lugs of the negative plates of cell E together and to the lugs of the positive plates of cell F. Deflectors 11 are provided at both ends of the rows of lugs of the negative plates. As can be seen in Figures 3 and 4 the deflectors 11 for the lugs at the ends of the two rows nearer to the side of the mould assembly nearer to the top of Figure 3 are connected to members 15C and 16C respectively which are integrally formed as parts of a cranked arm 13C mounted on a pivot 14C at the side of the assembly nearer to the top of Figure 3. The deflectors 11 for the lugs at the other ends of the rows of negative plates are also connected to respective members 15D and 16D formed as part of cranked arm 13D mounted on a pivot 14D at the foot of the assembly as shown in Figure 3. This arrangement ensures that the arms and members avoid the remaining parts of the mould cavities and therefore there is no interference with the lugs of the positive plates and the associated connecting straps.

The arrangement of pivots 14E,14F, arms 13E,13F, members 15EJ 6EJ 5FJ 6F and deflectors 11 for the mould cavities 9E and 9F for forming connecting straps for connecting the lugs of the negative plates of cell B together and to the lugs of the positive plates of cell C and for forming connecting straps for connecting the lugs of the negative plates of cell D together and to the lugs of the positive plates of cell E is the same as that just described in relation to the mould cavities 9C and 9D. However, as can be seen in Figure 3 the mould cavities are arranged in a manner which is reverse to that of the mould cavities 9E and 9F.

As shown at the right-hand side of Figure 3 the mould assembly is provided with a long narrow mould cavity 9G for forming a connecting strap to connect the lugs of the negative plates of cell C together and to the lugs of the positive plates of cell D since all the lugs are arranged in a single row. Thus only one deflector 11 is required and provided, this being positioned near the upper 7 side of the mould cavity 9G as shown in Figure 3. This deflector is located at the end of a single cranked arm 13G mounted on a pivot 14G at the side of the mould assembly near the top of Figure 3.

During manufacture of a battery as shown in Figures I and 2 using the apparatus of the first embodiment the end lug 18 of the negative plates of cell C is bent towards the other lugs (see Figures 5 and 6) as the battery box containing the stacks of plates and separators in each cell is lowered towards the mould assembly. Simultaneously other lugs of negative plates at the ends of rows are bent. Each end lug is thus bent by a controlled amount. Molten lead is poured into the respective mould cavity to form a connecting strap and allowed to cool and solidify. The box and stacks of plates and separators is then lifted from the mould assembly and the deflectors, which overlie the sides of the moulds, rise as the arms on which the deflectors are located rotate about the respective pivots. The deflectors are thus moved clear of the moulded connecting straps 19 and then drop back into position ready for the manufacture of another battery.

The manufacture of the battery is completed by turning the box and stacks of plates and separators upright, pushing the stacks fully into the box, securing a lid to the box, adding acid and charging.

The apparatus of the second embodiment shown in Figures 7-11 is a simplified version of the apparatus of the first embodiment. This apparatus comprises a mould cavity 20 for forming a connecting strap for a single row of lugs 21 of negative plates and, at each side of the mould cavity, one of two pivotally mounted deflectors 22 each having a ramp surface 23, the base of which overlies the nearer edge of the mould cavity.

The five stages of forming the connecting strap and bending the end lugs in the row are shown in Figures 7-11 as follows.

Stage 1: as shown in Figure 7 the battery box containing a stack of plates and separators is inverted and positioned so that the lugs 21 of the negative plates are located above the mould cavity 20.

Stage 2: as shown in Figure 8 molten lead is poured into the mould cavity, the 8 box and stack is lowered, the lugs 24 at the ends of the row contacting the respective ramp surfaces 23 on the deflectors 22 and are thus bent inwards by a controlled amount.

Stage 3: as shown in Figure 9 the row of lugs is positioned in the mould cavity so that the extremities of the lugs are at a required distance below the level of the surface of the molten lead 25, the end lugs 24 having been bent inwards towards the remaining lugs in the row by contact with the ramp surfaces 23.

Stage 4: as shown in Figure 10, when the lead 25 has solidified the battery is lifted clear of the mould, the solidified lead of the connecting strap 28 now formed holding the end lugs in their bent condition. During this stage, the deflectors pivot until the base of each ramp surface 23 is clear of the edge of the connecting strap 28.

Stage 5: as shown in Figure 11 the deflectors drop back to their original positions (as shown in Figures 7, 8 and 9), the end lugs of the row now being permanently held in the required bent positions by the now solid connecting strap 28.

9

Claims

CLAIMS:

1. A method of manufacturing a lead acid battery comprising positioning a row of lugs of battery plates above a mould cavity, the lugs projecting generally downwardly, providing a ramp surface at an edge of the mould cavity, lowering the row of lugs into the cavity including simultaneously lowering a lug at one end of the row against the ramp surface to cause said lug at one end to bend a controlled amount towards the next adjacent lug in the row and thereby be in a predetermined position relative to said next adjacent lug, pouring molten lead into the mould cavity and around the lugs thereby covering a predetermined amount thereof, allowing the lead to solidify to form a connecting strap for the lugs and thereby hold the end lug in said predetermined position.

2. A method of manufacturing a lead acid battery according to claim I comprising raising the row of lugs with the connecting strap now attached so that the connecting strap moves upwardly from the mould cavity and arranging that the ramp surface moves simultaneously to allow unimpeded movement of the strap.

3. A method of manufacturing a lead acid battery according to claim 1 or 2 wherein two ramp surfaces are provided, each one positioned to cause the bending of the lugs at opposite ends of a row of lugs of plates of the same polarity, and the two ramp surfaces are both moved simultaneously with the raising of the row of lugs and the connecting straps so formed attached thereto to allow unimpeded movement of the strap.

4. Apparatus for forming a connecting strap for a row of lugs of battery plates of the same polarity comprising a mould cavity, a ramp surface positioned at an edge of the mould cavity to be engaged by a generally downwardly projecting lug at the end of the row whereby on movement of the lugs into the cavity said lug at the end of the row is caused to be bent by engagement with the ramp surface a controlled amount towards the next adjacent lug in the row and thereby be in a predetermined position relative to the next adjacent lug.

5. Apparatus for forming a connecting strap according to claim 4 wherein the ramp surface is provided on a deflector.

6. Apparatus for forming a connecting strap according to claim 5 comprising two deflectors each having a ramp surface provided adjacent a cavity, each ramp surface being capable of being engaged by one of two lugs, one at each end of the row of lugs.

7. Apparatus for forming a connecting strap according to claim 5 or claim 6 wherein the or each deflector is mounted to be capable of moving into position at an edge of the mould cavity where it is engageable by the end lug of the row of lugs and to be capable of moving out of said position to allow unimpeded movement of a connecting strap connected to the row of lugs.

8. Apparatus for forming a connecting strap according to claim 7 wherein the deflector is mounted whereby movement of the deflector is simultaneously with the movement of the row of lugs out of the cavity.

9. Apparatus according to claim 7 or claim 8 wherein the or each deflector is pivotally mounted.

10. A method of manufacturing a lead acid battery substantially as described herein with reference to Figures 1-6 of the accompanying drawings.

11. A method of manufacturing a lead acid battery substantially as described herein with reference to Figures 7-11 of the accompanying drawings.

12. Apparatus for forming a connecting strap for a row of lugs of battery plates of the same polarity substantially as described herein with reference to and as shown in Figures 1-6 of the accompanying drawings.

13. Apparatus for forming a connecting strap for a row of lugs of battery plates of the same polarity substantially as described herein with reference to and as shown on Figures 7-11 of the accompanying drawings.

BWTIML - 10871 I I Amendments to the claims have been filed as follows two deflectors each having a ramp surface provided adjacent a cavity, each ramp surface being capable of being engaged by one of two lugs, one at each end of the row of lugs.

14. A lead acid battery manufactured by a method according to any one of Claims 1-3, 10 and 11.

15. A lead acid battery manufactured using apparatus according to any one of Claims 4-9, 12 and 13.