NO753516L - - Google Patents

Description

Procedure for filling plates

for electric batteries

The invention relates to the manufacture of electric battery plates, especially of the tubular type, and particularly relates to the filling of pipes with such plates.

Tubular sheets can have a variety of different types of tube material and tube shapes and can have tubes that are interconnected or formed as separate tubes that are separately arranged on the spines.

An example of such separately arranged tubes are woven fabric tubes with a thin, outer plastic sheath with through-holes with a diameter of 1 - 2 mm and a distance from each other of 1 - 2 mm. The plastic sheath is 0.1 - 0.2 mm thick.

The invention will be described in more detail with special reference to such pipe devices as, for example, where the pipes are made up of a simple pre-formed assembly as this facilitates the assembly of the pipes on the spines of the plate.

A common method in the manufacture of tubesheets involves impregnating fabric tubes with a resin to make them rigid, but still permeable, arranging the tubes on a series of lead alloy spines, one spine per tubes, and filling the space between the inside of the tubes and the spines with active material, e.g. lead oxide powder from a funnel, and shaking the assembly to compact the powder in the tube. This method presents considerable problems including loss of lead oxide powder, irregular filling weight and uneven filling, and the active material tends to become. too strongly compacted at the bottom of the pipes during filling which in use forms the top of the pipes.

In British patent document no. 947 '796, in order to reduce these problems, it is proposed to extrude a paste of active material containing a water-soluble thickener into the tubes under high pressure. This method, however, led to plates with unpredictable variable electrical properties. There was also a tendency for the paste to break down and lose its fluidity under pressure and also to dry out in the machinery if there were stoppages or delays in the production sequence.

In British Patent No. 1 386 056 it is proposed

to inject a measured volume, corresponding to the inner volume of the tube plate, of an acid accumulator into the tubes within a very short time, e.g. under 1.5 s. A certain amount of additional water is added to the paste. This is claimed to result in the formation of a suspension, but the mixture is in reality a thick paste which is not self-leveling. The pastes described contain 3 parts by weight of gray lead oxide, .1 part by weight of red lead oxide, 2.96 parts by weight of oxides per parts by weight of acid and water and 0.06 parts by weight of sulfuric acid with a specific gravity of 1.4 per weight part oxide, i.e. that 12.6% of the gray lead oxide was sulphated. In the patent it is described that the pastes have dynamic viscosities in the range of 3000 - 4000 centipoise. It is not indicated which method or which apparatus should be used for measuring the viscosity.

The inventor behind the present method has measured the viscosity of the paste described in the above-mentioned British Patent No. 1,386,056 with a viscometer with a rotating blade, as described below, using the measurement method described below.

This paste was found to have a torque (as defined herein) in the rotating blade viscometer of 10.7 kg-cm. The paste is not self-leveling, i.e. when a mass is placed as a lump on a flat surface, it will not get one. flat leveled surface within 24 hours even if small amounts of liquid are separated from the solid during this time.

This method has the disadvantage that it requires an exact dosage of the paste volume to be injected, and that the paste is so viscous that it must be forced into the pipes under high pressure.

This need to apply high pressure causes the paste to have a varied specific gravity along the length of the tubes, and the paste tends to be too strongly compacted at the inlet of the tubes as during use. forms the bottom of the tubes. Also, this method makes it difficult to get the paste to completely fill the tube, especially in a deep plate. This severely limits the plate size that can be filled. This introduces further problems when producing accumulators from the paste and when using the accumulators.

According to the invention, it has been shown that these problems, separately and collectively, can be reduced by using an active material with a very different composition, an apparatus and a method where a pourable liquid slurry with low viscosity is introduced into the pipes under the influence of .the weight or a low pressure, after which the paste reaches the tubes, has been filled, is preferably compacted by building up the back pressure.

By regulating the increase in back pressure, the degree of compaction can be varied as desired and uniform compaction achieved.

A slurry with a very low viscosity is introduced into the pipes under the influence of gravity or a very low pressure.

In the present method for filling sheathed plates, e.g. tube sheets, for electric batteries,

e.g. lead/acid accumulators, an active material is introduced into the porous sheath for a sheathed plate, e.g. the tubes, when the casing is mounted on the board's current-conducting element, e.g. the spines, and the procedure is characterized by the fact that the active material

le is introduced into the casing as an aqueous slurry with a torque (as defined herein) in a rotating blade viscometer of 0.082 0.83 kg-cm at 20°C.

A material is preferably chosen for the casing

which is able to filter out active material, while

allows liquid to pass, and the introduction of the slurry into the casing is continued until the casing is filled with active material

le, the introduction of the slurry into the casing is preferably carried out at a pressure of less than 1.05, preferably <0.35, kg/cm until the casing has been filled with material, after which the pressure is preferably increased to over 1.05 or 0.35 kg /cm 2, but not over

7.03 kg/cm 2 , and then cancels. The active material has a torque (as defined herein) in a rotating blade viscometer of 0.082 - 0.69 or 0.83 kg-cm, preferably 0.20 - 0.55 kg-cm, at 20°C.

For the sake of simplicity, the present method will be described essentially in connection with tube sheets.

The ratio between the slurry volume that is introduced into the pipes and the pipes' overall internal free volume in the plate is preferably not more than 3:1, e.g. under 2:1.

The pipes' internal free volume is the volume within the pipes' internal diameter that is not taken up by the current-conducting elements.

The aqueous slurry comprises a mixture of water

and particulate active material. The slurry may be unacidified or it may contain added acid in a sufficient amount to at least partially sulfate the oxide.

The weight ratio that should be used depends on the special active material used, the permeability of the pipes being filled and on whether the material contains an acid or not, and if the material contains an acid, the ratio between acid and active material, i.e. the degree of sulphation.

For the nonwoven fabric described below, it is preferred to use non-acidified slurries with a ratio of solids to liquids of 2.5:1 - 3.5:1, and for partially acidified slurries a ratio of solids to liquid of 1.7: 1 - 2.5:1, as the acid causes a strong increase in the viscosity of the slurry.

The slurry may contain common fillers and additives for the active material, such as hydrophobic or hydrophilic silicon dioxide, as long as the material still has a viscosity as defined above. According to a device is filled

o

the pipes essentially under the influence of the weight by pumping the material into the pipes under no back pressure, and the pumping' is continued and the back pressure is allowed to rise to a value just above 7.03 kg/cm 2. The pressure can thus be 0.35-3, 51, for example; 0.70 - 2.11, kg/cm 2 . The time that the pressure is allowed to increase is not

of decisive importance. Usually, the pressure is only allowed to increase to a set value, and when this has been reached, the pressure is released.

It was surprising and stood. in contrast to the more time-consuming proposals where the entire filling operation is carried out under high pressure. as. led to the formation of layers in the active material as the paste has a higher specific gravity near the inlet (which will form the bottom of the tubes during use), that with this arrangement the specific gravity of the active material can be increased evenly throughout the tube.

As mentioned above, the ratio between active material and liquid that should be used will depend on a number of variables including the type of material from which the pipes are made.

The need for the material to have a high permeability to water in order to obtain a good conductivity when used in accumulators must be adjusted in relation to the need for the material to hold the active material so that the filling can be carried out quickly and the active material is kept in place in the pipes for longer periods of time and exposed to shock and vibration. A suitable material is made from a non-woven sheet of polyester fibers with a thickness of 0.5 - 0.7 mm and a weight of 120 - 160 g/cm , with a nitrogen permeability (as defined below) of 8.0 l /cm per minute and a permeability to water (as defined below) of o 1.5 l/cm 2 per minute. This material is preferably not perforated, and its porosity is due to the natural openings between the fibers from which it is made.

It is more generally preferred to use a material with a nitrogen permeability of .0.5 - 12, e.g. 1 - 10, or preferably 3-9, l/cm per minute. The material should also have a water permeability of at least 0.01, e.g. 0.1 or 0.5 - 1.2 or 5, l/cm 2 per minute or more.

As indicated below, it is preferred to use a slurry in which the particles of the active material have an average size of 5 - 20 µm.

in

A material with particles with an average size of 1 - 30 or 50 - 100<y>m can, however, just as well be used.

As for the lead/acid tanks have essentially

all lead oxide particles a size below 100<y>m, e.g. less than 1% by weight of the particles have a diameter over 200 ym. Also, less than 1% by weight of the particles have a diameter of less than 0.001 µm. Typically has at least 50% by weight, e.g. 95% by weight of the particles, a diameter below 10 µm and 5% by weight of the particles with a diameter below 1 µm.

The oxygen can be made up of gray lead oxide or red lead oxide. or a mixture of gray lead oxide and red lead oxide, preferably of a mixture of gray lead oxide with an average particle size of 20 um and red lead oxide with an average particle size of 5 10 um. The ratio between gray lead oxide and red lead oxide can be 95:5 - 5:95, preferably 90:10 - 50:50, e.g.

33:67.

The pipes are preferably clamped at the top and. below

allowing liquids to escape from the entire area of the pipes.

It is advantageous that a certain amount of the slurry is continuously mixed during the filling and that a smaller proportional proportion of the supplied slurry is taken from this continuously mixed quantity that is filled into each tube plate.

The slurry is preferably supplied by means of pump which provides a uniform delivery and keeps the slurry<*>suspended, and in the spaces between the introduction into a tube plate the slurry is recycled from the pump's outlet to the pump's inlet, e.g. via a recirculation pipe that is connected to the pump's outlet, and a stirred storage tank from which a supply pipe runs to the pump's inlet.

According to a first embodiment of the present method, the slurry is introduced from a pump into a tube plate, and when this plate has been filled, the slurry is continuously recycled from the pump's outlet to the pump's inlet and then introduced into another tube plate.

The present invention can be practiced in several different ways, and one particular embodiment and certain modifications thereof will be described as an example with reference to the drawings, of which

fig. 1 is a schematic side view of an apparatus used for carrying out the present method,

fig. 2 is an enlarged schematic perspective sketch

of the one in fig. 1 shown filling box,

fig. 3 is a schematic diagram of a part of that in fig.

2 showed the lower clamp in the open position, where only part of the plate's tube is shown, fig. 4 is a horizontal cross-section taken along the line IV - IV in fig. 3, fig. 5 is a partial cross-section through part of the upper clamp in the open position, as shown in fig. 3, fig. 6 is a front elevation of the rotating blade viscometer used to measure the viscosity of the slurries used in the present process, fig. 7 is one. detailed front view of the blade assembly in the viscometer according to fig. 6, fig. 8 is a horizontal view of the container for use with the viscometer of FIG. 6 and for receiving the sample which must have its viscosity measured, and fig. 9 is a horizontal view prepared from an optical micrograph of the nonwoven fabric, NW, described below and used in the examples. The apparatus consists of a slurry tank 10 for storing the slurry to be filled in the plate pipes. The tank is provided at its bottom with a stirring arm 11 which is driven by means of a belt and drum device 12 which is affected by a motor 13 with variable speed. A vertical supply pipe 15 extends upwards from just above the stirring arm 11 to the inlet for a supply 16 which is also driven by means of a belt and drum device 17 which is affected by a motor 18 with variable speed. The outlet of the pump 16 is connected vertically downwards to a plate filling station 20 via a supply line 19. The supply line runs through a manometer 22, a two-way valve 23 and a fishtail manifold 24. The valve 23 can be adjusted so that the slurry will flow vertically downwards to the station 20 , or so that the slurry will flow to the tank 10 via a recirculation pipe 25 which extends downwards to just above the stirring arm 11. The pipes 15 and 26 preferably have the same cross-sectional area.

The amount of slurry added is preferably maintained

of approx. 150 kg, e.g. 100 - 200 kg, and the amount of slurry introduced into each tube plate, i.e. the separate filling weight,

is 400 - 1000 g. More generally, the weight ratio between the active material, e.g. 75 kg, in the continuously mixed slurry supply and the separate filling weight 1300:1 - 25:1, preferably 1000:1 - 200:1, and preferably 160:1 - 100:1..

The station 20 comprises a frame 29 which is rigidly fixed in relation to the manifold 24 and comprises top and bottom clamps 30 and 31.

The clamps 30 and 31 are provided with teeth and fit the outer surface profile of the bottom and top of the tube plate as the plate is inserted into the clamps with its open bottom facing the manifold 24. The manifold has an outlet nozzle assembly consisting of 6.35 mm' long copper supply pipes or other rigid supply pipes with an external diameter that corresponds to the inner diameter of the sheet metal pipes and which are arranged at a distance from each other along a straight line, the center of the supply pipes being located at the center of the sheet metal pipes.

The open ends of the plate pipes thus fit snugly over the supply pipes and are clamped to them by means of the upper clamp 30 which can be provided with a pliable gasket lining.

The lower clamp 31 holds the plate in place and presses the tubes against a thickened end section of the spine. The plate's surfaces are completely free.

The spines are made of a common lead alloy and have a common structure and are arranged on a top rail at centers that correspond to the centers of the tubes with which they are to be used. They are preferably provided with short axial fins which are used to center the spines in the tubes and to prevent the spines from being distorted during handling prior to filling.

The station 20 will now be described in more detail with reference to fig. 2-5.

As mentioned above, the station 20 comprises a frame 29 which is rigidly fixed in relation to the manifold 24. This frame consists of two parts 32 and 33 which are hinged to each other along the left edge, and it is the part 33 which is rigidly fixed to the manifold 24 The upper and lower clamps are both made up of two parts 30A and 30B and 31A and 31B. Sections 30A and 3IA are sub-. supported by the movable part 32 of the frame 29, and the parts 30B and 31B are supported by the stationary part 33 of the frame 29.

The stationary part 33 also supports upper and lower locking outriggers 36 and 37, which are arranged in such a way that they engage with the upper. and lower handles 38 and 39 on the movable frame part 32 and lock the filling station in the closed state.

The stationary part 33 of the frame 29 also carries a lower support rail 42 with an opening 43 through which the tab 44 of a plate 45 can pass and which facilitates the positioning of the plate in the filling station.

The upper and lower clamps 30 and 31 are provided with teeth adapted to the plate's outer jacket dimensions, and the two parts of each clamp define, when closed, a row of cylindrical holes 48 which are connected by slots 49 with the double thickness of the mantle's fabric 47 to prevent the mantle from being cut to pieces by the clamps.

The lower clamp 31 presses the mantle's fabric 47 against the wide shoulders 51 of the plate's spines 52 to ensure a tight seal (see fig. 3 and 4).

In fig. 5 shows the clamping device at the manifold 24. A manifold plate 54 has a row of supply pipes 55 which pass down through the manifold and which are provided with tapered ends 56 which are passed through openings in a rubber gasket 58. This is flexible and can be pressed together with the fingers to only approx. half of its thickness in • uncompressed state which is approx. 3.18 mm. In fig. 5 shows that the jacket 50 is passed over the ends 56 of the supply pipes. This arrangement is in reality such that the gasket 58 must be compressed with approx. 1.59 mm of the mantle 50 which is forced up into the gasket, in order for the plate's upper rail to be brought against the frame's lower rail 42 (this compression is not shown in the drawing). The clamp 30 presses the mantle's fabric 47 around the ends 56 of the supply pipes 55 to obtain a good upper seal.

The pump 16 provides uniform delivery and is of the well-known type, such as the pump sold under the trade name "MONOPUMP", which comprises a rotor in the form of a single starting coil spring fitted in a cylinder in the form of a double starting coil spring with twice the pitch of the rotor , and in which the rotor rotates around its own axis in one direction while its axis rotates around the axis of the cylinder in the opposite direction at the same speed, this type of pump provides a positive displacement with steady flow and

prevents liquids from separating from solids in the material.

According to another embodiment (not shown), the filling station is formed with a twin manifold which each. fed .' from the pump 16. The two-way valve 23 is replaced with a three-way valve, and each line from the valve 23 to a manifold contains a pressure sensitive valve 70.

This valve 70 is preferably a pressure reduction valve which can be set to any desired pressure, e.g. 1.05 kg/cm 2 , and when this pressure has been reached, the valve will maintain a pressure of 1.05 kg/cm 2 until it is regulated, e.g. manually.

The method then used is that a plate is introduced in

a manifold and that the valve 23 is changed from recirculation or from the other manifold. The plate will be filled e.g. during the 5

s, and the pressure will rise to 1.05 kg/cm 2 and be maintained for 5 s.

During this time, the operator will have removed the filled plate from the other manifold and inserted a new plate. He can then change the valve 23 for immediate recirculation or to immediately fill the new plate.

According to another embodiment, the pressure reduction valve 70 can be used to switch the pump supply to recirculation and to reduce the pressure against the plate immediately after that. pre-set pressures have been reached.

The filling process is carried out as follows:

The material is produced with the desired composition

in the tank 10 by means of the stirring arm 11. A pipe plate 50 is mounted, the fabric pipes 47 are brought into position on the metal spines 52, and the pipe plate is brought against the clamps 30B and 31B of the station 20 with its upper bottom ends pushed up against the gasket 58 and over the ends 56 of the manifold 24's supply pipe 55. The frame part 32 is then swung towards the part 33, and the clamps 30 and 31 are thereby closed, and the locking arms 36 and 37 are guided over the handles 38 and 39. The stirring arm 11 is kept in motion, and the valve 23, which is turned to the recirculation position, connects the pump 16 with the pipe 28, and the pump 16 is started. The recirculation is carried out until the flow has become even. The pressure indicator 22 indicates zero pressure while the recirculation is taking place.

The valve 23 is then changed to connect the pump 16 to the manifold 24. The slurry flows down into the station 20,

and the active material is filled into the tubes. The valve 23 is held in this position until the pipes have been filled with active material, and the pressure indicator will then show a relatively sudden increase in pressure. At this point, liquid will separate out as small droplets essentially simultaneously over the entire surface of the tube plate. As the pressure rises to the shut-off pressure, additional small amounts of liquid will separate from the plates.

The first amounts of liquid tend to be clear, while the later secreted amounts of liquid also tend to contain active material. When the pressure reaches the desired shut-off value, the valve 23 is changed for recycling the material to the tank 10 via the line 26.

Terminals 30 and 31 • . is then opened and the filled plate removed, and the plate is subjected to the further processing steps, such as insertion of one female rail, pickling, drying and electrolytic propagation.

The excess of slurry in the manifold 24 falls down

in the tank 10.

With continuous operation, the pressure increase shown by the indicator 22 can be used to regulate the filling cycle, e.g. to actuate the valve 23 and to open the clamps 30 and 31 to release them from the manifold 24 and to bring them into engagement with a new plate in a clamped position. ■ Limit switches can be used which will be affected by the new plate which engages with the manifold 24, to shift the valve 23 back to the filling position.

Examples

Examples will now be given of specific methods for plate production.

The plates were positive plates with 15 tubes each having a length of 34.8 cm. The tubes were made of non-woven polyethylene terephthalate fibres. These were produced as follows: A thin web (1.5 mm wide) of fibers with a through-stitch length of 11.4 cm was produced by carding, and a coat was made by laying approx. 10 webs on top of each other to produce a continuous web of non-woven cloth (also 1.5 m wide).

The fibers generally extend along the web which is pleated in a sik.-sak pattern as it is removed from a conveyor running in the same direction as the length of the web, and transferred onto a conveyor running at right angles to the length of the web. The fibers will thus lie essentially across the length of the fur, but due to the movement of the second conveyor, the fibers in the neighborhood will have an opposite slant with a small angle in relation to the transverse direction.

This material is then impregnated with 50% by weight of a polyacrylic binder. It has a thickness of 0.5 - 0.7 mm and weighs 120 - 160 g/cm<2>.

This material is then converted into a series of tubes by passing two layers of the material through a multi-stitch machine to attach the layers together along parallel lines (eg about 2 lines per 2.54 cm) to form pockets or tubes in the usual manner.

This material is then immersed in a phenolic resin and dried. The material takes up 30% of the phenolic resin, based on the dry weight of the unwoven material. After dividing into equal lengths, mandrels with a circular cross-section and a diameter of 7.29 mm are then inserted between the rows of stitches to form the pockets. The material has<1> an air permeability of 8.0 l/min per cm^ and a water permeability of 1.5 l/min per cm 2. Its structure is shown in fig. 9.

It appears from fig. 9 that this non-woven fabric consists of individual fibers which are arbitrarily interwoven into each other. The fibers have a diameter of approx. 25 ym or more, generally 20 - 50<y>m. The distance between the individual fibers is usually below 250 ym and most often below 100 ym, and due to its thickness of 0.5 - 0.7 mm, the material has a three-dimensional structure which enables an overlap between several individual fibers along any path from the surface to: surface of the plate.

Air permeability was measured as follows:

A sample with a diameter of 2.8 cm (an effective cross-sectional area of.6.16 cm 2) was clamped, and the time it took. for 50.1 dry nitrogen to flow through the sample at 20° C. at a pressure difference of 1.5 cm water column was noted.

The material is too permeable for mercury porosity measurement or measurement of air flow through an alcohol-saturated sample to be accurate.

The permeability of the same sample to water was investigated by measuring the time. it took a column of water with an initial height of 42 cm and a volume of 1 liter to flow through the sample under the influence of gravity.

The downstream end of the column below the sample was closed, the water was introduced above the sample, and the downstream end below the sample was then opened to the atmosphere. This material is designated as non-woven cloth N.W. in the table 1 below.

Another cloth was also used. It was a spun, woven cloth which in Table 1 below is denoted by SW and which has an air permeability of 6.0 l/cm per minute. It has 17 weft threads per cm and 22 warp threads per cm. The warp threads have

a diameter of approx. 250 ym and the weft threads a diameter of approx. 375 etc. An examination under a microscope suggests that the distances between neighboring warp threads and neighboring weft threads are at most 250 ym s 250 ym, but over these distances there are bridges of a very large number of loose fibers that extend from the threads.

The compositions used are indicated in the following tables IA and IB. \

The slurry was prepared from mixtures of gray lead oxide (average particle size 20<y>m) and red lead oxide (average particle size 5-10 ym) mixed in different weight ratios with tap water.

The solid particles in the slurry were such that under 1% by weight had a size over 200 µm and under 1% by weight a size under 0.001 um, with 95% by weight having a size under 50 um. These particle sizes were determined by sieving.

The tank 10 contained 150 kg of slurry, and the stirring arm II with a size of 76.2 x 3.8 cm was rotated at 30-70 revolutions per minute. minute (rpm) to keep the solids suspended. The pump 16 was operated at various capacities as indicated in Table IA. During the recirculation, the indicator showed 22. zero pressure. -Using the same rotation and pumping conditions, the valve 23 was changed to the 1.1 filling position, and the time when the indicator 22 showed zero pressure and the total time until the valve 23 was again changed back for recirculation, and it reached maximum pressure • was noted .. These are indicated in table IA. The internal volume of the tubes was 170 cm 3.

It is preferred to add acid to at least partially sulfate the oxide. lg oxyd requires 0.4 ml of sulfuric acid with a specific gravity of 1.4 to achieve this. The mixing of the slurry continues in the storage tank during the addition of acid, and once this has finished, the filling cycle can be continued. Some of the examples in tables IA and IB apply to partially acidified materials.

Example 12 was carried out using tubes with a total internal free volume of 105 cm 3 .

Footnotes to Tables IA and IB

1) Acid:solid ratio. It has been assumed that the entire amount of acid is absorbed by and reacts with the oxide excess at the stage it is first added and that the acid/oxide ratio thus holds

where more acid is constantly added, i.e. that a proportion of the acid is removed with each pasta sample that is removed.

2) Solid:liquid ratio.

A). These are calculated including the entire amount of acid that even

tuelt is added as a liquid.

B) The weight of the solids removed in the filtrate samples is

not included as the weight of these samples was relatively small and there was no way to easily determine the ratio between solids and liquids in the filtrates.' C) The conditions have been calculated without taking into account the quantities of liquid that are removed in the pastes in the tubes. These conditions are therefore

somewhat low in terms of the solids content in the slurries.

3) Ratio between gray oxide and red oxide. These have been assumed to remain constant unless an additional amount of

gray or red oxide is added.

4) Wet pasta in a plate. The weight x of the fabric tube, lead back-

the rows and a bottom rail were measured. The specified values apply to it. wet, filled plate after the introduction of a bottom rail minus x. 5) % excretion of the sample. This is the height A of the solids in the container divided by the height B of the liquids from the bottom of the container, expressed as a percentage, after the sample has been well shaken for 0.5 minutes and. has then been allowed to settle in a vertical position for 24 hours.

The container is a test tube with a round bottom and an internal diameter of 1.5 cm, and at least 9 cm of slurry is filled into the test tube.

6) 1/2 lifetime of the suspension. This is the time it takes for the solids level in the sample in the container described under 5)

to sink to halfway between B and A.

The examination is carried out by placing a rubber band with

a lower edge at the mid-level, i.e. (B + A)/2 cm, from the bottom of the test tube which is then shaken vigorously for at least 0.5 minute or until all solid has been displaced from the bottom of the test tube which is then straightened, and the time from this time to the time when light first becomes visible under the rubber band is measured. 7) Pump speed. This is simply a regulation. The volume of slurry pumped through the manifold was measured at various positions by collecting the slurry as it exited the manifold. Two measurements were performed for each pump setting. The volume of the slurry was measured.

A curve was then plotted for volume at pump settings 0, 20, 30 and 40 against time in seconds (using a stopwatch). An approximately straight line curve was obtained. 8) Time before starting pressure increase. This is the time that elapses between the opening of the inlet valve and the pressure gauge actually starting to move instead of just oscillating. 9) Theoretical volume pumped before starting pressure increase. This is the time indicated in column 8 of table IA multiplied by the volume indicated in column 7 of table IA and is purely theoretical.

10\ Layer formation. (Table 3) This is determined by pickling the plates in sulfuric acid with a specific gravity of 1.40 for 6 hours, followed by drying at 8 2° C for 12 hours.

The upper rail and the lower rail were then cut off from the plate and the remainder cut into four equal horizontal strips which were designated A, B, C and D, A being cut off at the lower rail of the plate. These were then weighed. The horizontal strips were then divided into four sections of 3 tubes each omitting every 4th tube and were designated 1-4, 1 being cut off at the handle side of the plate. The four sections, one from each of the horizontal strips, were then weighed, and the value given under 1 in table 3 is this value. The other vertical sections 2, 3 and 4 were weighed in the same way.

11) Pencil porosity. This is determined using it

well-known method referred to as mercury penetration porosity measurement and was carried out in connection with the same samples as indicated in table 3. Details regarding this method are given in British patent document hr. 1,331,257.

The values obtained by using the rotating blade viscometer for certain of the slurries used in the above examples are shown in table 2 below.

The viscometer used is shown in fig. 6, 7 and 8.

The apparatus consists of a frame 110 which carries an electric motor 111 which drives a stirring arm assembly 120 via a gearbox 112 and a torsion transducer 119. The speed in the gearbox 112 is monitored by a tachogenerator 113 which emits a signal to a digital voltmeter 113A. The voltage signal emitted from the torsion transducer is transmitted to a map printer 114. The printer has a variable map speed and a variable scale.

A sample container 130 is clamped onto an adjustable table 115 which can be raised and lowered on guide rails 116 by means of a pneumatic cylinder 117.. -

The sample container 130 has a removable lid 131 arranged over the stirring paddle assembly 120. The lid can be attached to the container by means of an external bayonet lock (not shown).

The paddle assembly 120 is removably attached to the output shaft 118 of the gearbox 112 and consists of a central rod 121 with a lower knob 122 which, when in use, fits into a hole 132 in the container 130 bottom. The rod 12.1 has a diameter D5 of 1.3 cm and carries 3 pairs of vanes 123, 124 and 125. The vanes 123 and 125 are located in the same plane and are arranged at right angles to the vanes 124. All vanes are vertical and thus parallel in relative to the rod's 121 axis. The buckets are carried on arms 126, 127 and/28. The distance D6 from the center of the arm 126 to the knob 122 is 6.5 cm, the distance D7 from the center of the arm 127 to the knob 122 is 3.9 cm, and the distance from the center of the arm 128 to the knob 122 is 1.6 cm. The width of each paddle D3 is 1.2 cm, and its height D2 is 1.2 cm and its thickness 0.1 cm. The distance

D4 from the inner edge of each vane to the surface of the rod 121 is 1.5 cm.

The distance Dl between the outer edges of the blades for each pair of blades is 6.8 cm.

The inner height of the container 130 is 8.2 cm/and its inner diameter is 8.8 cm. There are four internal screens 135 arranged at the ends of the diameters and at right angles to each other. The thickness D10 of each screen 135 is 0.30 cm, and they extend a distance D9 inwards of 0.5 cm. The separation Dll between the screens along a diameter is 7.65 cm. Each screen has a height1 that corresponds to the overall height of the container.

The container and screens are made of smooth stainless steel.

The device is used as follows:

The container is filled to a depth of 8.2 cm with the material to be examined, and raised and clamped to the drill 115, and the lid 131 is attached. The map printer 114 is started, and the motor 111 is then started up with the drive set for a low cutting speed of . e.g. C op. The torque during start-up and the torque during steady operation are detected by the torque transducer 119, and the motor and the printer are used for at least 2 minutes until a steady torque value is written down. This is the torque value for steady state. The torque value for steady state is noted, and if an initial peak was present, this ratio is also noted. The sample was then removed and shaken with the rest of the the material being measured and the container: refilled. The measurement is again repeated at a higher cutting speed of e.g. 18 p.m. The cycle is repeated for the number of cutting speeds that are desired.

The background torsion value, i.e. with the container 130 empty, was found to be 0.055 kg-cm for all the cutting speeds listed in Table 2. The same value was obtained when the container was filled with water.

The torsion value, as defined herein, obtained by an-

ts

rotation of the rotating blade viscometer is the value of the steady-state torsion of the sample measured in the manner described above with the machine described above at a cutting speed of 6 revolutions of the vanes per minute at an ambient temperature of 20° C, minus the background reading at 20° C.

Lamination results for the plates produced in Examples 3, 5, 8 and 12 are reproduced in Table 3 below.

Porosity results for the plates made in examples 3, 5 and 8 are reproduced in table 4 below.

Claims (19)

1. Procedure for filling sheathed plates for electric batteries, where a mixture for active material is introduced into the porous sheath for a sheathed plate when the sheath is mounted on the plate's current-conducting element, k a r a k characterized in that the mixture for the active material is introduced into the casing in the form of an aqueous slurry which has a torsion value measured by means of a viscometer with a rotating blade of 0.082 - 0.828 kg-cm at 20°C. 2. Method according to claim 1, characterized in that the aqueous slurry has a torsion value measured using a viscometer with a rotating blade of 0.082 - 0.552 kg-cm at 20°C. 3. Method according to claim 1 or 2, characterized in that the aqueous slurry is introduced into the casing at a pressure of less than 1.05 kg/cm until the casing has been filled with the mixture, after which the pressure is allowed to increase to over 1.05 kg/cm 2 , but not over 7.03 kg/cm 2 , after which the pressure is lifted . 4. Method according to claims 1-3, characterized in that the casing consists of a number of pipes arranged next to each other and with a current-conducting element arranged in each pipe. 5. Method according to claims 1-4, characterized in that the ratio between the slurry volume introduced into the pipes and the pipes' total internal free volume in the plate is at least 2:1. 6. Method according to claim 5, characterized in that the ratio is 3:1 - 15:1. 7. Method according to claims 1-6, characterized in that the material for the covering has a nitrogen permeability of 0.5 -. 20 l/cm <2> per minute. 8- Method according to claim 7, characterized in that the material for the covering has a capacity for nitrogen of 3 - 10.l/cm per minute. 9. Method according to claim 8, characterized in that a non-woven sheet of polyester fibers with a thickness of 0.5 - 0.7 mm is used as material for the wrapping, a weight of 120 - 160 g/cm and a nitrogen permeability of 8.0 l/cm2. 10. Method according to claim 9, characterized in that a slurry is used which has not been acidified and which has a weight ratio between solids and liquid of 2.5:1-3.5:1. 11. Method according to claims 1-10, character. characterized by the active material consisting of a lead/acid-active material which is at least partially sulphated before it is introduced into the plates' porous casing. 12. Method according to claims 1-11, characterized in that a partially sulfated slurry is used with a degree of sulfation of less than 10%, and that the slurry has a weight ratio between solids and liquids of 1.7:1 - 2.5:1. 13. Method according to claim 8, characterized in that a covering of a material is used which consists of a spun and woven cloth with 15 - 25 weft threads per cm and 15 - 25 warp threads per cm and a nitrogen permeability of 5 l/cm 2 per..minute. 14. Method according to claims 1-13, characterized in that an active material with an average particle size of 1 - 100 ym is used. 15. Method according to claim 14, characterized in that an active material with an average particle size of 5 - 20 ym is used. 16. Method according to claims 1-15, characterized in that the casing is clamped at the top and bottom while the slurry is introduced into the pipes, so that the liquids can escape from the entire area of the casing. 17. Method according to claims 1-16, characterized in that a supply of the slurry continuously blan des during the filling and that a smaller proportion of the slurry supply is introduced from this continuously mixed supply into each sheathed plate. 18. Method according to claim 17, characterized in that a continuously mixed slurry supply is used in which the weight ratio of the active material and the separate filling weight is 1300:1-25:1. 19. ' Method according to claims 1 - 18, characterized in that the slurry is delivered by means of a pump from a stirred supply of the slurry in a storage tank to a filling manifold for filling in a plate, using a pump which gives a uniform delivery and keeps the slurry suspended, while the slurry in the intervals between introduction into a shrouded plate via the filling manifold is recirculated from the pump's outlet via a recirculation pipe which is connected to the pump's outlet, to the storage tank and from there via a supply pipe to the pump's inlet.