DE2360574A1 - Continuous pasting of lead accumulator grid plates - using mixer-kneader-extruder to produce paste strip, for uniform prod - Google Patents

Abstract

In the continuous prodn. of the grid plates for Pb accumulators by mixing Pb oxide dust (Pb + PbO) to a paste successively with water and H2SO4, cooling and pressing into the grid spaces, the dust is ground before mixing to increase and equalise its surface activity and the paste is pressed through a die of a suitable size and shape in the form of a thin, wide, cohesive strip, whilst the grid is passed to or under this strip, which is pressed into the spaces. The paste pref. is extruded through a wide slit die and pressed into the grid spaces by rolling. The water used for mixing can also contain additives needed for negative grid plates, e.g. BaSO4, C black, lignin derivs. and/or storage stabilisers. The mixt. can be stabilised by adding high-mol. water-soluble polyethylene oxide, pref. in a amt. of 0.05-0.5%, before adding the water. Grinding and mixing are carried out in a 2-shaft mixer-kneader-extruder, with 2 adjacent worm shafts, turning in the same direction, in an 8-shaped twin-screw housing. This continuous pasting process gives good homogeneity and uniformity in wt. and dimensions, so that the plates have reproducible physical and chemical properties. The proces is simple and suitable for mass prodn. and the closed construction reduces the lead dust level in the factory.

Description

Hoppecke accumulator factory

Carl Zoellner & Son

5000 Cologne, Barbarossaplatz 2

Method and device for the production of Grid plates for lead accumulators

The invention relates to a method and a device for the continuous production of grid plates of lead batteries, in the case of the lead oxide dust, mixed one after the other with water and sulfuric acid in a mixer to form a paste is, is cooled and in a pasting process in the interstices the grid is pressed in '.

For the production of grid plates of lead batteries by applying a paste of active material, it is known to produce the pastes from a mixture of lead, lead oxide, water and sulfuric acid by stirring in a vessel. Disadvantageous is the discontinuous production and the associated differences between the individual batches regarding the physical and chemical properties of the pastes produced.

A method for producing grid plates for lead-acid batteries has already become known to remedy these disadvantages, in which the lead oxide mass required for pasting the grid is continuously produced (compare Canadian Patent No. 906 05I). For this purpose, two-shaft mixers are used, which have lead dust on the feed side at the same time Water is fed in, with mixing taking place by means of screw flights or paddles provided in the mixer. After a certain The sulfuric acid is then added to the mixing section

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and the paste mixed with sulfuric acid is cooled. Finally, there is a feed station for further paste additives intended. The disadvantage is that it is still necessary to look at conventional pasting machines, the twin-shaft mixer and the pastes produced in the mixer cannot be extruded in the form of a continuous ribbon.

Furthermore, it is previously known that the grid by means of a transport device to move vertically past the openings of mass containers, the mass with rotating vanes and / or in opposite directions corrugated rollers from both sides is pressed into the openings of the grid. This pasting process only succeeds from one side, the grids are no longer guided vertically past the paste opening of the mass container, but horizontally. The grids themselves then lie on the so-called pasting belt, an endless belt made of rubberized fabric.

In order to achieve the most uniform plate thickness possible, the pasted grids are made superfluous by means of a scraper Paste exempt. Both the one-sided pasting of grids and the two-sided pasting have deficiencies. The two-sided pasting process sets grid strengths with very tight tolerances ahead of them, as they can not be met in today's common falling casting, so that the pasting process a device must be connected upstream with the help of which the grids are brought to the same strengths.

The horizontal or band pasting process with one-sided loading the openings of the grid with paste leads to strong fluctuations in weight of the pressed paste volume as a result the uneven supply of the paste, the dependence on the changing static pressure in the paste storage container and the non-uniform function of the scraper. The latter point is strongly influenced by the correspondence and viscosity of the pastes to be processed, as a result of the batch production and the chemical Reactions from each other are very different.

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The invention has for its object to continuously grid plates to paste lead accumulators while avoiding the disadvantages of the prior art mentioned, in particular to a high degree of homogeneity, weight equality and dimensional equality and consequently the same physical and chemical properties of the individual grid plates are important to one another.

The object is achieved according to the invention in that the lead dust is subjected to a rubbing process to increase and equalize before mixing the surface activity of the lead oxide crystals is subjected, that the mixing is then carried out that the through the mixing produced paste by one of the shape and size of the To be produced grid plate adapted nozzle to produce a thin, wide, coherent paste band is pressed and that grids "are continuously guided onto the paste belt or under the paste belt, which is then pressed into the lattice spaces is introduced.

The paste is preferably extruded into the paste band. The pressor The extrusion process should be carried out through a slot die.

It is advantageous to roll the tape of paste into the spaces between the grids. The other substances required for negative grid plates such as barium sulfate, soot> lignin derivatives and / or storage protection substances can be added when the ground lead dust is mixed with water. The mixture can also be stabilized during mixing and before the pressing process by adding high molecular weight, water-soluble polyethylene dioxide. Here it is advisable to add $ 0.05-0.5 polyethylene oxide.

The device for carrying out the process for continuous Production of grid plates of lead batteries is characterized according to the invention by a twin-shaft mixing

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and kneading extruder, the two side by side, in the same direction rotating worm shaft! in an 8-shaped twin worm housing having, wherein the worm shafts are mounted and driven on one side and on the opposite of the drive Side an extruder device with a slot die and one behind the other in the direction of material flow a lead dust task, a water inlet, a cooling section and a sulfuric acid task are provided. By The mixing and kneading extruder enables the continuous production of a paste in the form of a continuous strip. The paste is produced by means of a continuous broadband extrusion process, which is adjusted to the desired paste consistency and viscosity is rubbed, mixed, cooled and kneaded.

It is expedient in the direction of flow behind the sulfuric acid addition arranged another cooling section. The cooling sections are housing parts of the mixing and kneading extruder, each from one Cooling jacket are surrounded, through which a coolant is sent.

An endless pasting belt can be arranged below the extruder, on which grids can be fed, which of the Paste tape to be covered. The upper run of the pasting belt is preferably passed through the gap between two rollers, which Press the paste tape into the spaces between the grids underneath.

In order to carry out the rubbing process, mixing process, To be able to carry out the kneading process and the extrusion process is proposed in an expedient embodiment of the invention, to provide the screw shafts one behind the other with grating screws, mixing screws, kneading screws and an extrusion head.

Further details, features and advantages of the invention emerge from the following description of the associated Drawing in which a device for the continuous production

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development of grid plates of lead batteries shown schematically is.

According to the drawing, the outlet end is a twin-shaft Mixing and kneading extruder 1 above the feed end of a pasting belt 2 arranged, whose endless belt j5 grid at 4 are fed. The upper run of the endless belt j5 is carried out through the gap between two pasting rollers 5 and 6 .

The twin-screw mixing and kneading extruder 1 can perform the process tasks of rubbing, mixing, kneading and extruding the continuous production of grid plates for lead-acid batteries. The mixing and kneading extruder is used for this purpose 1 mounted on one side and provided with a drive 7. The drive 7 acts via a reduction and splitting gear on two worm shafts arranged in a housing 8, which are not shown in detail. The two worm shafts are next to each other and rotate in the same direction. The inner shape of the housing 8 is 8-shaped in cross section, so that the Double screws of the screw shafts can be added without dead corners with play for the material transport. The product will consequently inevitably along the housing wall in an 8-shaped path in the direction of the discharge of the mixing and kneading extruder emotional.

The snails themselves are appropriate to the task to be performed Shaped differently over the length of the worm shafts in such a way that initially a friction process occurs over a certain movement path of the supplied material, then a mixing and kneading process and finally an extruding process are carried out will. This is illustrated in the drawing below the schematic representation of the system by means of a labeled line. The screw configuration as such is not shown in the drawing, since it is not the subject of the invention is. '

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The housing 8 of the mixing and kneading extruder 1 is provided with several entry openings or locks. First will be on the left end in the drawing of the mixing and kneading extruder lead dust, consisting of lead and lead oxide weighed over a Opening 9 made in the housing 8. At the beginning of the mixing section water and optionally polyethylene oxide, barium sulfate, carbon black and / or lignin are weighed out through a further opening 10 introduced into the housing 8. The adjoining housing section is surrounded by a cooling jacket 11 through which a coolant is performed for the purpose of cooling the material that is already pasty in the interior of the housing 8.

In the adjoining housing section there is another lock 12 for the weighed supply of sulfuric acid intended. Two more cooling jackets 1 ^, 14 allow controlled cooling of the grid plate paste inside the mixing and kneading extruder 1.

The extrusion area of the mixing and kneading extruder 1 is provided with a slot die 15 on the extrusion head, so that the paste is extruded from the housing 8 in the form of a continuous band.

According to the structure of the system, the single-sided twin-screw mixing and kneading extruder 1 is fed with the so-called lead dust, which has lead oxide contents between 65 and 75 % , via the feed and metering devices for the production of the paste suitable for pasting grid plates. Purely for the consistency of the paste to be produced, it has proven to be useful to rub the lead dust in the first phase to increase and equalize the surface activity of the lead oxide crystals. In terms of surface activity, the lead dust is not homogeneous in terms of its production and storage conditions, so that the surfaces can be

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switched rubbing process with appropriately designed screw geometries is formed in the mixing and kneading extruder 1 more energetic and the same.

The mechanical processing of plague bodies is changing not only the shape, but also almost all other properties such as free energy and chemical reactivity. With an appropriately designed screw geometry of two counter-rotating screws or one main screw and three or more planetary snails it is possible on the individual To act mechanoenergetically in such a way that lead dust particles that existing energy differences as a result of disturbances in the atomic structure are leveled out by taking up or releasing more differently mechanical energy contributions of the individual crystalline particles of the lead dust.

In the following step, water and, if necessary, polyethylene oxide are supplied to the rubbed dust via the opening 10, the For negative pastes, additional substances such as barium sulfate, carbon black, lignin derivatives and storage protection substances such as stearic acid have been added are.

The sulfuric acid is then added. The resulting heat of reaction must now be dissipated quickly so that the now possible chemical reactions, which e.g. lead to the formation of basic lead sulfates, proceed as slowly as possible. Of the The mentioned reactions are only aimed for after the pasting process in the plate. One then speaks of the maturation process of the plates.

The process steps outlined above make a highly tough one using the adjustable theological properties Paste consistency achieved that required the execution of an extrusion operation made possible under pressure. The paste behaves like a plastic, while that according to the usual mixing processes produced pastes release water under pressure and

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with are difficult or difficult to extrude. The on the described Art produced pastes still have a significant difference to the conventional ones. Their color is gray-white in contrast to gray-yellow. It can be seen from this that the lead sulfate formed is much more finely distributed and thus gives a color tone in the paste compared to conventional manufacturing methods.

The plasticity of the paste that can be achieved in the mixing and kneading extruder can be further stabilized by using high molecular weight, water-soluble polyethylene oxide in the order of magnitude, for example 0.05 to 0.5 %, with the formation of very stable hydrogen bonds to the mixed water.

In the last part of the mixing and kneading extruder 1, the screws of the screw shafts with the conveying part now press the pfestic Paste through the geometrically suitable slot die and thus create, for example, a 1.6 mm thick and 235 mm wide band. Double grids for starter batteries are now continuously opened under this belt by means of a transport device the endless belt 3 brought up lying. The double grilles will be covered by the extruded paste band and get into the gap between the rollers 5 and 6, where the material of the paste band is introduced under pressure into the interstices of the respective underlying grid.

It is also possible to extrude the paste tape twice with e.g. 1.6 χ 115 mm. This will be the connection points of the grids excluded from the paste to the double lattice.

Furthermore, as a modification, it is possible to continuously guide the grids onto the extruded paste band and into the paste band to be pressed in under pressure e.g. by the rollers 5, 6.

With the method of the invention, the continuous mixing provides a previously unattainable uniformity of the pastes

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achieved. The distribution of the solid and liquid components is more homogeneous than in previously known methods, in particular the homogeneous distribution of the sulfuric acid visible through the coloring by lead sulfate leads to a for the electrical Properties of the paste important homogeneous porosity.

In addition to the qualitative advantages, economic improvements are also achieved with the invention. In the procedural and Machine sequence: Mixing device, intermediate paste storage, Pastiermas chine, who combined in a single machine. The production of grid plates for vehicle propulsion in large numbers is after this Veifehren and with this device only possible. So far there has been a lack of suitable machines. The exposure of workplaces to lead dust is increased by the possible closed construction of the conveyor and mixing plants are significantly reduced.

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Claims (12)

Expectations ; Process for the continuous production of grid plates for lead batteries, with lead oxide dust in one Mixer one after the other with water and sulfuric acid to a paste is mixed, is cooled and in a pasting process is pressed into the gaps between the grids, characterized in that the lead dust is subjected to a rubbing process to increase it before mixing and equalization of the surface activity is subjected, that the mixing is then carried out, that the through The mixing of the paste produced through a nozzle adapted to the shape and size of the grid plate to be produced a thin, wide, coherent paste band is pressed and that continuous grid on cfes paste band or under the paste band, the material of which is finally introduced into the spaces between the grids by pressure will. 2. The method according to claim 1, characterized in that the paste is extruded into a paste tape. J. Expire according to claim 1 and 2, characterized in that the pressing or extrusion process through a slot die is made. 4. The method according to any one of claims 1 to 3, characterized in that that the paste band is introduced into the spaces between the grids by rolling. 5. The method according to any one of claims 1 to 4, characterized in that that when mixing the ground lead dust with water, if necessary, the necessary for negative grid plates other substances such as barium sulfate, soot, lignin derivatives and / or storage protection substances are added. - 11 509825/0408 6. The method according to any one of claims 1 to 5, characterized in that that before the addition of water to stabilize the mixture to be created, high molecular weight, water-soluble polyethylene oxide is added. 7. The method according to claim 6, characterized in that 0.05 to 0.5 % polyethylene oxide is added. 8. Device for carrying out the method according to one of claims 1 to 7, characterized by a twin-screw mixing and "kneading extruder (1), which has two adjacent, co-rotating tendon shafts in an 8-shaped twin screw housing, which are mounted and driven on one side An extrusion device with a slot die is provided on the side opposite the drive and a lead dust feed, a water inlet, a cooling section and a sulfuric acid feed are present in the direction of material flow. 9. Apparatus according to claim 8, characterized in that in the flow direction behind 'the sulfuric acid task is another Cooling section is arranged. 10. Apparatus according to claim 8 and 9, characterized in that the cooling sections are each surrounded by a cooling jacket housing parts. . . 11. Device according to one of claims 8 to 10, characterized in that that under the extruder a pasting belt is arranged, on which grids can be fed, and its upper run through the gap between two pasting rollers is led. 12. Device according to one of claims 8 to 11, characterized in that that the screw shafts one behind the other with friction screws, mixing screws, kneading screws and an extruder head are provided. 50 982 5/040 8 - 12 -