GB2361893A

GB2361893A - Separating porous concrete bodies

Info

Publication number: GB2361893A
Application number: GB0108529A
Authority: GB
Inventors: Gunter Lutkenhorst
Original assignee: Dorstener Maschinenfabrik AG
Current assignee: Dorstener Maschinenfabrik AG
Priority date: 2000-04-20
Filing date: 2001-04-05
Publication date: 2001-11-07
Also published as: NL1017875C2; GB0108529D0; DE10019726C2; DE10019726A1

Abstract

Porous concrete bodies 2 are separated from a cake 1 along parting faces 3a,3b by the action of fluid pressure along such parting faces. The fluid may be air and may be pulsed. It is applied by means of a sealing shoe 6 placed against a slit at the edge of a parting face through which fluid is applied. Preferably two such shoes are located on opposite faces of the cake and they are vertically adjustable to register with a slit. A plurality of such shoes may be arranged vertically spaced to register with each parting face of the cake.

Description

2361893 "Producing porous concrete bodies" This invention relates to a

method of producing porous concrete bodies from a cake which is cut into cake pieces or into porous blocks along parting faces, and to apparatus 5 for carrying out this method.

A method of this type is described in German Patent Specification 196 54 139 Cl, for example. In this method, a starting material is generally cast into a casting mould and the cast starting material is pre-hardened to form a cake. Thereafter, the cake can be tipped by 90% for example, from its horizontal initial position on to a bottom narrow face. The cake is subsequently cut, and is generally cut along (vertical and horizontal) planes (parting faces) which are parallel to its outer faces to form cake pieces which are generally cuboidal. In order to harden a cake of this type, it is generally introduced into an autoclave in which hardening occurs under the action of steam pressure.

Crystal growth in the cut cake is promoted by this procedure or by the action of heat and steam in the autoclave. This is particularly disadvantageous in the region of the horizontal parting faces, because the individual (cuboidal) cake pieces tend to cake there due to their intrinsic weight. In any event, there is an ever-present problem in that after they have been treated in the autoclave the cake pieces tend to stick or cake together, particularly in the region of their horizontal parting layers or parting faces.

Therefore, it has already been proposed in the prior art that the hardened cake pieces (porous blocks or porous concrete blocks) are subsequently separated horizontally.

Separating devices which are specially designed for this purpose are usually required. These devices tear apart the cake pieces or porous blocks which have caked together, as it were, whereupon damage to the parting and external faces cannot be ruled out. The consequence of this is that the damaged cake pieces or porous blocks either have to be subsequently processed or constitute waste which cannot be reused. The present invention as a whole aims to provide a remedy here.

A basic object of the present invention is the provision of a method of, and apparatus for, producing porous concrete bodies from a cake which is cut into cake pieces or porous blocks along parting faces which makes it possible to achieve perfect separation of the porous blocks from each other.

According to a first aspect of the present invention, there is provided a method of producing porous concrete bodies from a cake which is cut into cake pieces along parting faces, characterised in that the cake pieces are separated from each other by the action of pressure on the parting faces by means of a fluid.

This fluid can be a gas, particularly air. Air is particularly suitable in this respect, firstly because disintegration phenomena of the individual porous blocks do not constitute a problem, and secondly because (compressed) air is available anyway to a sufficient extent during the manufacture of porous concrete bodies.

In principle, water or oil can also, of course, be employed if the consistency of the cake or of the porous concrete bodies to be produced permits this. In general, the pneumatic medium is fed to the parting faces via at least one sealing shoe which completely or partly covers at least one parting line of the parting slit or parting face on the outside of the cake with the formation of a seal. This sealing shoe is therefore placed on the corresponding parting line of the parting face to be separated, or on the parting slit, on the outside of the cake, and is subsequently acted upon by the fluid or pneumatic medium. In this manner, the fluid penetrates the parting face via the parting slit preferably over the entire length of the sealing shoe - as a parallel, slit-like flow of fluid.

The fluid therefore forms a wedge of medium, as it were, which raises the cake pieces disposed above the parting face by a minimal extent so that they are released in the region of the parting face from the cake pieces or porous blocks situated below them. This effect is increased further by supplying the bulk of the pneumatic medium in a pulsed manner. In this respect, pressure pulses with a duration of about 1 second have proved to be particularly advantageous, for example. The pressure of the pneumatic medium preferably falls within the range of a few bar, usually between 3 and 10 bar (0.3 to 1 MPa). This of course depends on the weight of the cake pieces which are to be raised (for a short time) above the parting face which is acted upon, and on the pressure drop and the size of the parting face.

The effect described above can advantageously be intensified even further if the parting face which is to be separated is acted upon by means of opposite flows of fluid. These flows of fluid can penetrate said parting face via opposite parting lines. This is generally effected by providing opposite sealing shoes which form a pair of sealing shoes. Provided that these two sealing shoes or this pair of sealing shoes are placed simultaneously on the cake at the separating line of the parting face to be separated and are acted upon synchronously by the pneumatic medium, the cake pieces to be separated are separated particularly thoroughly from each other.

As a result, the method described above first carries conviction due to its simple, cost- effective nature. This is because it expressly avoids the need for the cake pieces to be grasped and to be pulled apart by tearing them, as was considered to be unavoidable in the prior art. At the same time, any possibility of the clamped cake pieces breaking is also prevented. This is a risk which exists in particular for long, thin cuboidal cake pieces. Waste can consequently be minimised.

Furthermore, known separating apparatuses which are operated by the methods described in the prior art can be modified inexpensively and in a simple manner, to the form defined in claim 8, basically by replacing the grippers which were obligatory in the simplest case there by the sealing shoes which are used according to the invention.

Preferred features of the apparatus are defined in claims 8 - 14, which apparatus can be constructed extremely simply and inexpensively. This is because the high pressures or forces which were necessary hitherto for grasping and pulling apart the cut cake pieces or porous blocks no longer have to be provided. Instead, it is sufficient to place the sealing shoes on the outside of the cake so that they form a seal in the region of the respective parting lines or parting slits. This can be effected with the assistance of springs. Similarly, the pneumatic medium which is available anyway is suitable for placing the sealing shoes on the outside of the cake with the assistance of said pressure medium. In any event, particularly high contact pressure forces are no longer expressly necessary. The cost of the requisite mechanical devices can thereby be considerably reduced, particularly because costly hydraulic units, such as those which were 5 obligatory in the prior art, become superfluous.

The method according to the invention always makes it possible to effect a particularly simple and effective separation of the horizontal parting faces of the cake. The vertical parting faces can also, of course, be treated in this manner. However, this is generally not necessary, because in the region of the vertical parting faces the intrinsic weight of the cake pieces, which gives rise to the caking process which has to be overcome, plays no part. In other words, the problems described above generally cannot occur in the region of the vertical parting faces, so that the method described above is employed almost exclusively in the region of the horizontal parting faces.

Finally, it should be mentioned that the sealing shoes which are generally used are of extremely small construction, so that the thickness of an unavoidable bottom piece or of a bottom layer which has to be removed can be minimised (see DE 196 54 139 Cl). This means that, even taking this aspect into consideration, the amount of non-reusable waste is considerably reduced compared with that which occurs in previous procedures.

The invention is described in more detail below with reference to the drawings, which merely illustrate an example of an embodiment, and where:

Figure 1 is a perspective view of the porous concrete body in association with a separating apparatus according to the invention which has been reduced to its essential components; Figure 2 is a front view of the subject of Figure 1, with one area shown on an enlarged scale; Figure 3 is a view of the sealing shoe employed; and Figure 4 is a side view of the subject of Figure 3.

The Figures illustrate a separating apparatus which is suitable for producing porous concrete bodies. The porous concrete bodies are produced from a cake 1, which originates from a starting material which has been cast in a casting mould which is not illustrated. The cast starting material is pre- hardened to form the cake 1 concerned. Sand, lime, cement, anhydrite, aluminium powder and water are used as the constituents of the starting material, as is basically known. After pre-hardening, the cake 1 is in each case situated in a vertical position on its narrow face. So as to be able to produce porous concrete bodies following this stage, the cake has been cut along planes parallel to its external faces in order to produce cake pieces or porous blocks 2, and taking into account corresponding parting faces 3 between said cake pieces/porous blocks. Cutting is effected in a (wire-) cutting machine, which is likewise not illustrated.

After it has been cut, the cake 1 has been hardened in an autoclave by the action of steam and heat. The result of this hardening process is that the cake can be separated in the region of vertical parting faces 3a, although this does not apply to the horizontal parting faces 3b. In other words, the corresponding cake pieces 2 which are stacked one above another become caked to each other in the region of their horizontal parting faces 3b due to their intrinsic weight and due to the crystal growth which occurs in the autoclave. Accordingly, the cake pieces 2 in the embodiment exemplified have to be separated from each other in the region of their respective horizontal parting faces 3b.

For this purpose, the invention provides a holder 4 on a cross-beam 5 which carries two sealing shoes 6. These two sealing shoes 6 can be placed by means of the holder 4 on the outside of the cake on parting lines or parting slits 7 corresponding to the horizontal parting faces 3b. The holder 4 or the cross-beam 5 can also, of course, accommodate more than two sealing shoes 6.

In any event, the holder 4 is equipped with respective gripper arms 4a, 4b which can be placed individually or jointly on the respective parting slits or parting lines 7 of the respective parting faces 3b on the outside of the cake. This is effected by placement devices, which are not illustrated, but which swivel the respective gripper arms 4a, 4b about associated rotary bearings 8 in the manner which is merely indicated in Figure 2.

The sealing shoes 6 are constructed as is shown in detail in Figures 3 and 4. It can be seen from these Figures that the respective sealing shoe 6 comprises a baseplate 9 with a fluid connection 10 at the back. In addition, a seal support 11 is provided at the front or on the cake side, and consists of a rubber-like, flexible material which does not damage the outside of the cake. The seal support 11 surrounds a substantially rectangular or slit-shaped pressure space 12. Said pressure space 12 communicates via a central fluid pressure feed line 13 with the fluid connection 10, which in turn is acted upon by the fluid or by a pneumatic medium/air via a fluid supply device which is not illustrated.

The fluid supply device is capable of generating pressure pulses in the fluid or pneumatic medium or in the air which can have a duration of about 1 second. When the sealing shoes 6 are placed on the outside of the cake, these pressure pulses result in the fluid or air penetrating the associated parting face 3b via the parting lines or parting slits 7. This occurs with a parallel flow of fluid or air. This is because the pressure space 12 extends substantially collinearly, or at least parallel, to the respective parting lines 7 when the pressure shoes 6 are placed on the cake 1.

This can easily be put into effect by providing for the rectangular pressure space 12 of the sealing shoe 6 or of the pair of sealing shoes 6 to be aligned as a whole so that it is collinear or parallel to the associated parting line 7; this is achieved with the aid of the gripper arms 4a, 4b or with the aid of additional devices placed there. The fluid or pneumatic medium can thereby penetrate the parting face in the form of a slit or wedge of fluid via the respective parting line/parting slit 7. So that the fluid does not escape between the outside of the cake and the seal support 11 during this operation, the sealing shoe 6 covers the respective parting slit 7 of the parting face 3b on the outside of the cake forming a seal. Additional sealing measures can also be provided at this location, although they are not necessary. This is because the parting lines 7 in the region of the vertical parting faces 3a are generally closed anyway, by cake residues which become spread out during the cutting operation. These spreading losses first of all carry the penetrating fluid, but are then displaced outwards almost simultaneously.

In the embodiment exemplified, two opposite sealing shoes 6 are provided in each case so that the parting slits or parting lines 7 of the parting face 3b which is situated therebetween can be acted upon in opposite directions by the fluid or pneumatic medium. In the embodiment shown in Figure 2, the fluid therefore penetrates both sides of the respective parting face 3b (which is not cut vertically) in the shape of a wedge and ensures that the cake pieces (denoted by 2) which are disposed above said parting face 3b are raised for a short time at least and thus effect the desired separation.

The holder can then be moved vertically and/or upwards and downwards in relation to the cross-beam 5, in order to act upon the respective horizontally disposed parting faces 3b again and again. It is also possible, of course, for a plurality of sealing shoes 6 or pairs of sealing shoes 6 to be disposed parallel to each other, so that in the embodiment illustrated in Figure 2 the horizontally disposed parting faces 3b of the cake I are separated simultaneously from each other in one operation. It also falls within the scope of the invention for the pressure shoes 6 to be disposed on an annoured chain which is moved vertically and/or horizontally along the parting lines or parting faces 3a, 3b which are to be acted upon. In any event, following this the holder 4 moves longitudinally in relation to the cross- beam 5 to the next vertical stack of cake pieces, which are treated correspondingly. The invention also, of course, opens up the possibility of effecting separation into rows rather than into blocks.

8 -

Claims

1. A method of producing porous concrete bodies from a cake which is cut into cake pieces along parting faces, characterised in that the cake pieces are separated from 5 each other by the action of pressure on the parting faces by means of a fluid.

2. A method according to claim 1, characterised in that a gas, particularly air, is used as the fluid.

3. A method according to claims 1 or 2, characterised in that the fluid is fed to the parting faces via at least one sealing shoe which completely or partly covers at least one parting line or parting slit of the parting face on the outside of the cake, forming a seal.

4. A method according to any one of claims 1 to 3, characterised in that the fluid penetrates the parting face via the parting slit as a parallel, slit-like flow of fluid.

5. A method according to any one of claims 1 to 4, characterised in that the fluid is supplied in a pulsed manner.

6. A method according to any one of claims 1 to 5, characterised in that each parting face is acted upon by means of fluid flows which are opposite to each other and which enter the parting face via opposite parting slits.

7. A method of producing porous concrete bodies from a cake substantially as herein before described with reference to the accompanying drawing(s).

8. A separating apparatus for producing cake pieces from a cake which is cut along parting faces in the course of producing porous concrete bodies corresponding to the method according to any one of claims 1 to 6, having a holder for receiving at least one sealing shoe, wherein the sealing shoe is placed, by means of the holder, on a parting slit or on parting slits corresponding to the parting faces on the outside of the cake, and wherein a fluid enters the parting face from the sealing shoe via the parting slits in order -9to separate the cake pieces from each other.

9. A separating apparatus according to claim 8, characterised in that the holder is suspended from a cross-beam so that it is longitudinally adjustable and/or height5 adjustable.

10. A separating apparatus according to claims 8 or 9, characterised in that two opposite sealing shoes are provided in each case for simultaneously acting in opposite directions on a parting face.

11. A separating apparatus according to any one of claims 8 to 10, characterised in that the sealing shoes can jointly be placed, via gripper arms of the holder, on each separating slit of the parting face which is on the outside of the cake.

12. A separating apparatus according to any one of claims 8 to 11, characterised in that a plurality of pairs of sealing shoes is disposed in parallel and one above another, in order simultaneously to act upon all of the horizontal parting faces of the cake.

13. A separating apparatus according to any one of claims 8 to 12, characterised in that the sealing shoe comprises a baseplate with a pneumatic connection at the back and a seal support on the cake side or at the front.

14. A separating apparatus according to claim 13, characterised in that the seal support surrounds a substantially rectangular pressure space which preferably comprises a central fluid pressure feed line.

15. A separating device, substantially as herein before described with reference to the accompanying drawings(s).