Process for the production of wall bricks based on sand-lime and apparatus for manufacturing crude bricks

The invention relates to a method for producing Kalksilikatsteinen according to the preamble of claim 1 and an apparatus for producing stone blanks, in particular for the production of wall blocks on Kalksilikatbasis, according to the preamble of claim 13.

Kalksilikatsteine ​​compacted structure as bricks are usually produced by heating a raw mixture of quartz sand, lime and water, wherein the lime is optionally removed with the water mixed with the 'quartz sand, is prepared, the raw mix an almost dry, almost dusty or slightly has earth-moist consistency and using high pressures of the order of about 15 N / mm² must be compressed in a compression device to stone blanks. This compression is physical bonding forces sufficient due to the high pressure to obtain a blank strength that is enough to settle the blank removed from the mold without damage and can be transported to an autoclave, in which there is a steam curing result. The Dampfhär_tung leads to the formation of chemical bonding forces due to the formation of Calciumsilicathydratbrücken that give the stone the final strength. The use of such high pressures for the production of blanks but both constitutionally as-well with respect to the manufactured stone itself disadvantageous because a high body density is generated associated with low thermal capacity due to the high compression pressure. In addition, the high body density does not allow large stone formats because of excessive workload of Bricklayer walls.

To reduce the body density and thus increase the thermal insulation properties, according to DE-B 2526258 of the usual raw mix for Calcium silicate cement in an amount of at least 1 wt .-% and an addition of foam or Porenbildnem is added and then at substantially lower compaction pressures as 15 N / mm² worked. The cement additive partially replaces the need to achieve a sufficient strength blank physical bonding forces by chemical, as you can strength-forming reactions of the cement prior to forming the tile blank into gear. With less pressure, the body density can significantly decrease, and it becomes possible to use lightweight aggregates that improve the thermal insulation properties further effectively, and the stones are in this process with a hole pattern with a high proportion of holes of a variety of by webs separated prepared holes that are beneficial affect the thermal insulation properties and also significantly reduce the total weight of the stone. However, the thickness of the webs can not be reduced to the desired optimization, as at the desired se small web thickness at the webs_'Forming the blank would not formed properly. In addition, the process control is difficult when an intermediate storage of the crude mixture is required until the occurrence of the strength-forming reactions of the cement. In addition, the processing of the raw mixture is in itself problematic when a process procedure with interim storage is chosen, in particular in disorders of the downstream plant components.

From GB-A 1438062 a method for producing a porous lightweight building material based on a Kalkbindemittels and silicaceous material is known. The binder here consists of unslaked lime, preferably having a high reactivity and purity, an aqueous dispersion of hydrated lime and optionally cement. For the formation of pore lightweight aggregate, foam and in particular Al powders are used. To produce the raw mixture initially be water, then milk of lime and subsequently, the solid materials in a mixing vessel. By using preheated water and the extinguishing heat the lime results in an increased temperature. After pouring the raw mix into molds latter are brought into a room with an elevated temperature. After an initial stiffening is achieved in about 1.5 to 3 hours, the block is removed from the mold, cut into desired sizes and then autoklavgehärtet. Thus, there are relatively long mold residence times, which make the one hand a single stone production uneconomical, but then through the block preparation in relation to the relatively long mold life to sedimentation. Apart from the blocks to sever, and it always results in waste in the area of ​​the top of the block. The cement is used only to achieve adequate final strength.

Further, a method for producing lightweight foam concrete body is known from DE-B 2,617,153, which comprises mixing a rapidly-setting hydraulic cement composition in the form of a fine dry powder with a foaming agent and a containing aqueous foamed liquid Abbindehemmittel. The mixture is then placed in a mold where they abbindet and the desired initial strength is achieved in about 10 to 30 min. The setting takes place at 20 to 40 ° C, since at higher temperatures the initial strength would deteriorate. Optionally, a Autoklavhärtung be made. The fact that the aerated concrete body examined primarily consist of cement, they are expensive to manufacture, also the mold residence times are relatively long.

Moreover, a method for the production of hollow blocks is known from DE-A-2325 165 is known, which consist of lightweight concrete, said mandrels are introduced into a column filled with the raw mixture form. Otherwise, this method corresponds to the conventional production of concrete blocks.

Object of the present invention is to provide a method and an apparatus of the aforementioned type, which allow a simpler process management and besides achieving optimum thermal insulation properties of Kalksilikatsteine ​​the manufacture of Kalksilikatsteinen with particularly low cullet and Steinrohdichte and optionally with an optimum hole pattern.

Method, this object is solved according to claim. 1

The crude mixture used in this case has a pourable consistency, ie that it is essentially self-leveling (without natural angle of repose while pouring) and no measurable slump (> K3 according to DIN 1045). The crude mixture in this case has practically only those cavities which are formed by the added foam. Without the added foam considered, the voids between the individual particles of the raw mix are virtually completely filled with water so that applying pressure as in the conventional sand-lime brick manufacture when forming the tile blanks would not lead to -this increase of physical bonding forces and to a handleable preform. The pourable consistency allows an easy and simple dosing and filling the mold with the required amount of raw mix by pouring o. Dg)., Wherein the crude mixture substantially fills the mold without difficulty.

It also allows these pourable consistency, further reduce the webs between the holes in the stone in its width, so that the number of holes and the total proportion of holes can be enlarged with optimum hole pattern for insulation without mechanical problems with regard to the formation of holes or arise concerning blank strength.

Furthermore, the method is suitable to produce solid bricks with low density and hole and solid bricks with integrated thermal insulation, wherein, among the latter, the filling of a substantially across the width or length of the stone extending hole with a thermally insulating material such as a polystyrene block of is inserted into this hole, of course.

The sufficient for demoulding and subsequent transport strength to get the tile blanks by the establishment, in molding heat treatment, which not only leads to short cycle times in the production of blanks and perforated bricks forming of webs having the desired thin wall and yet with the required strength in blank enables, but in the first pressure in an economically acceptable processing of a crude mixture with a pourable consistency or substantially atmospheric pressure, and in particular without the need for intermediate storage of the raw mix prior to molding permits. The residence time in the mold and thus the cycle time is reduced with increase in the soaking temperature for the raw mixture and / or the proportion of cement. As a result of virtually atmospheric pressure producing the blanks, the addition of foam to raw mix is ​​particularly effective because the foam pores are practically not crushed in the blank production and thus contribute substantially fully to lower the body density of the stone and thus to increase the thermal insulation properties. It is also surprising that the predetermined through the foam pores remain in the stone, although the foam only has a low stability per se in the intended soaking temperatures for the raw mix in the form, if it ever is still present at the temperatures used.

This process has nothing to do with the per se known production of aerated concrete, in which the pores are produced by evolution of gas in a crude mixture which is already in a form, wherein the gas concrete 2 h and more remains in the mold. By taking place only in the form of gas, there is a not exactly determinable expansion, requiring then cutting the aerated concrete blocks in the desired size, which may have to even be ground. In the production of aerated concrete molding is connected to the binding process, and it can be personalized with fine grading curve, which must have a very small particle size, using only sand. By contrast, in the present process, the dimensional accuracy of the stones produced is ensured by the design, which is independent of the occurring chemical reactions (which, incidentally, is substantially different from those that occur in the production of aerated concrete), so that no post-processing is required and moreover, sands can be used with coarse fractions or other silicate-containing materials.

A significant advantage over the previously known production of calcium silicate blocks results from the fact that even slaked lime can be used as a starting material instead of quicklime. This may take the form of lime sludge, lime hydrate or the like happen:.. This causes the temperature issues that may otherwise occur through occurs when deleting the lime heat wesent Lich reduced. Moreover, the addition of water can make easier because die.Feuchte is in the sand determined with reasonable accuracy, contrast not just slaked lime due to the existing crystal water, which is also measured in the determination of water content. In conventional sand-lime brick production is the use of hydrated lime as hydrated lime o. Like. The other hand because of the normally present and usually also fluctuating water content of the sand is not possible, as this raw mix would be fed so much moisture that no blanks mehrausformbarwären.

Instead of the silica sand normally used, other silicate-containing materials may be used, such as pumice, clay or fly ash o. Like., Which can replace the quartz sand completely or partly and possibly also contribute to a reduction in weight of the finished stone.

As cement, for example, a Portland cement are used in combination with a correspondingly adjusted Erhärtungszeitbeginn with a certain amount of curing accelerator and optionally retarders, but also, for example, a quick-setting cement. When setting accelerator for example alkaline such as sodium hydroxide, carbonate, silicate, chloride such as aluminum and calcium chloride and water-soluble aluminates and silicates and sulfates as a retarder and sugar derivatives come into consideration.

The raw mixture can lightweight aggregates in the form of articles of cork, wood flour, polystyrene beads o. The like. Are added. Also known condenser can be used to liquefy the raw mix in addition to itself.

The crude mixture can be both volumetric and gravimetric dosed into the molds, although the former is preferred because then arise quickly and in simple stones with substantially constant weight. Possible variations in the density of the crude mixture can be reduced and the volumetric metered quantity weighed and corresponding to the measured value obtained in this way, the density of the crude mixture is adjusted for the following batch. This is achieved by appropriate dimensioning of water and amount of foam in the raw mix.

For forming the holes forms can be used, which have correspondingly shaped mandrels, however, it is preferable to form the holes by mandrels are inserted into the partially filled mold, in particular from above through the cover plate of the mold, whereby the mold then filled with the raw mix becomes. In a fully enclosed form and a slight overfilling for the intended Steinvolu-. mens is thereby simultaneously ensured the sharp edges of the formed blank, while the pourable consistency of the raw mix enables the upgrade of this between the mandrels and thus the formation of holes in only very low mechanical stress of einzufahrenden mandrels. The holes are preferably formed as blind holes.

The heating is carried out during a period of 10 to 60 sec by heating by means of a high-frequency field and causes a hardening of the cement (but not practically the calcium hydroxide by forming Calciumsilicathydratbrücken) to such an extent that the erförderliche blank strength greater than 0.1 N / mm² during this period, despite the pourable consistency of the raw mix is ​​achieved, resulting in a leather-hard surface of the tile blank without a liquid to impoverished surface area, so that no Abbrösein takes place. The achieved in this way, cycle times are industrially acceptable and avoiding a complex and problematic with respect to the timing of the method of intermediate storage.

The foam is either added as such or the crude mixture formed in this before filling in the form by the addition of a foaming agent, but the former is preferred. Schaumrohdichten of about 50 to 100 g / I, especially from about 70 to 80 g / I are preferred. Instead of air, the foam can also C0₂ be filled, thereby overfilling the mold and subsequent crushing of the extra dose foam. and / or the disintegration of the foam under the action of heat C0₂ is free, which leads to additional strength-forming reactions such as the air mortars. By adjusting the amount of foam and, optionally, of the other components of the crude mixture, it is preferably adjusted so that a body density of the stone <1600 kg / m³ for a perforated brick, with Scherbenrohdichten below 1200 kg / m³ readily be achieved, and <900 kg / m³ results for a solid brick.

Since foams are often sensitive to temperature, it is expedient to keep the temperature of the crude mixture to the filling in the form is so low that the stability of the foam is virtually unaffected by temperature. When using slaked lime this is not a problem because it is the raw mixture has a temperature, which is composed of the temperatures of the raw materials which are subject only to seasonal variations substantially. However, when the extinguishing heat of quick lime, which is used as a starting material is added, optionally a cooling approximately by appropriate heat radiation o. the like. undertake. So synthetic foams have practically only below 30 ° C, a sufficient stability, while protein foams also exhibit sufficient stability even above 30 ° C to 40 ° C and optionally. Depending on the used foam and the temperature of the materials used and the installation used can therefore maintain the temperature of the mixture of silicate-containing material, lime and water, and thus the addition of cement, accelerators and retarders, and foam constant or according to the initial temperature of the mixture of siliceous material, lime and water the amount of foam and / or the amount of retarder and / or accelerator for the cement dosage.

Here, the cement must be adjusted so as regards of starting from strength-forming reactions by appropriate addition of accelerators and retarders, depending on the temperature of the raw mixture that these reactions are triggered only by the action of heat in the form. For this purpose, it may also be necessary to remove coming from the deletion of lime heat accordingly. It is therefore appropriate that foam type and quantity and a retarder admitting controlled according to the temperature of the mixture of silicate-containing material, lime and water.

In order to facilitate the demoulding of the stone blank and to avoid caking, it is preferable to wet out the mold and the mandrels before filling of the crude mixture with a known release agent. This can be done by spraying or dipping, it being expedient for the latter to use an excited by ultrasonic separation bath, thereby removing remnants of the raw mix from the mold and the mandrels.

The above object-is. device achieved according to claim. 13

The soaking of the crude mixture by means of an electric field is suitable for both full and for perforated bricks and can be supported by heating the mold itself. For heating the raw mix in the mold by means of a high-frequency field frequencies> 600 kHz usable> 5 5 kV voltages, frequencies can be used up to 30 MHz.

The filling means can be a means for pouring the raw mix into the mold, because the raw mixture has pourable consistency. You can simultaneously serve for dosing the raw mix.

In the apparatus, in particular, the mandrels are positioned in the desired dimensions in the intended hole pattern and retractable as a whole in a filled with raw mix form, and specifically preferably from above, and in particular only up to a certain distance above the bottom of the mold for the formation of blind holes. In this case, the shape having a for closing thereof can be brought into the closed position the cover plate which has corresponding openings for insertion of the mandrels and is optionally arranged lowerable on a holder for the mandrels with these to a predetermined height.

However, the device may also have a highly mobile ground at a fixed cover plate during molding, optionally arranged mandrels firmly on the ground and are highly mobile with this. The floor may also consist of a circulating endless conveyor belt, for example a steel strip, consisting, the intermittently drivable, for example, according to the cycle time.

The cross section of the mandrels is preferably tapered at least in the area of ​​the free end thereof towards this end, for example, in cross-section conical and / or rounded o. Like., To facilitate removal from the mold. Also, each mandrel can have at its free end a ventilation opening, in order to prevent a vacuum from forming in this area when removing the spines from the shaped stone blank, since this could lead to a collapse of the webs.

The mandrels are preferably heated with an electric heater (heating elements), wherein the heating intensity along the length of the mandrels, continuously or in sections, is different (eg. As in three stages), so that in the axial direction of the mandrels, a temperature gradient among adaptation to when retracting the mandrels in the charged raw mixture is forming heat demand of the raw mixture is formed with the aim of a uniform as possible heating of the blank material. Since the heat requirement due to the heated example by means of contact heating walls of the mold seen over the cross-section of the tile blank is also not uniform is the heating intensity distributed over the base surface disposed mandrels of different sizes to be interpreted in order on the one hand in each case by a mandrel mass to be heated and on the other hand, the heat supply other components, such as the form, to be considered.

The bottom plate is designed approximately as a pallet or a conveyor belt o. The like., Optionally pre-heated, for example inductive, or by infrared irradiation.

When using a release agent bath for the mandrels, the mutual distance between which is arranged at the same level substantially the form and the bath may be equal to the mutual distance between a filling device for the shape and arranged at a punching mandrels, so that the on a common movable carrier is moved with the mold disposed below the band of the mandrels punching means moves the mold for filling device.

The cover plate is first held during removal in their position until the side walls of the mold and the mandrels are at least partially lifted from the stone blank to allow in this way an easy unmolding.

When used as a bottom plate of the form a conveyor belt, it is possible to demold the block blanks already, if they have not yet reached the desired for gripping and stacking blank strength, after which it. By means of the conveyor belt by an after-heater, for example, , Managed a heating tunnel or an infrared heating, where there is a further hardening to the desired blank strength for gripping and stacking as a result of there acting heat. This is possible because the tile blanks at the end of the conveyor belt have to be handled, because they are taken there to be transported to a autoclave in stacked form.

The invention is illustrated below with reference to the embodiments illustrated in the figures.<ul><li>FIG. 1 illustrates schematically the sequence of the process according to two embodiments.</li><li>Fig. 2 illustrates schematically the timing of the production of a stone blank by molding and heating.</li><li>Fig. Shows in detail, the forming of holes in the stone blank.</li><li>Fig. 4 shows an embodiment of a Dekkelplatte for a mold for producing a stone blank.</li><li>Fig. 5 shows an arrangement of spikes for molding a certain hole pattern in a Steirrohling.</li><li>Fig. 6 shows partly in section and partially end view of an embodiment of an apparatus for manufacturing a tile blank.</li><li>Fig. Shows a partial plan view according to the line VII-VII of Fig. 6.</li><li>Fig. 8 shows a side view of the apparatus of Fig. 6.</li><li>Fig. 9 shows a filling device for the apparatus of Fig. 6 in an end view.</li><li>Fig. Figure 10 shows the filling unit of Fig. 9 from the side.</li><li>Fig. 11 shows a further embodiment of an apparatus for producing stone blanks in schematic form.</li><li>Fig. Figure 12 shows a metering device for the apparatus of Fig. 11.</li></ul>

According to the first in Fig. 1 shown embodiment of the process of a silo 1 'which contains quartz sand, and a silo 1 ", contains the milled, calcined fine lime, these two materials fed to a pre-mixer 2, the same water is added q.s. is. the mixture is allowed in a reactor 2 'react during a sufficiently long period to remove the lime. the mixture of slaked lime and sand is fed to a mixer 3, is introduced into the further water to a sufficiently fluid consistency of to achieve final raw mix. This is also the temperature of the deletion may still relatively warm mixture of slaked lime and sand (seasonal) z. B. to a temperature of about 20 ° C reduced fluctuating values. in addition, a foam generating device 4 about a is foam gun, provided controlled by the generated foam via a control member 5 is also added to the mixer. 3 Cement from a reservoir 6 on the one hand directly supplied to the mixer 3 and the other hand placed in a secondary mixer 7, the further from a container 8 'a hardening accelerator and from a container 8 "Erhärtungsverzögerer is supplied. This proportion of cement together with accelerators and retarders are in the in addition to mixer 7 for better subsequent mixing in the mixer 3 is first premixed. The addition of accelerators and retarders via control members 9 'and 9 ". The mixture produced in the secondary mixer 7 is then fed via a control member 9 to the mixer third The control of the control devices 9, 9 'and 9 "is carried out according to the temperature T which has the reaching into the mixer 3 mixture to adjust the formulation of cement accelerators and retarders to the respective conditions. For example, after a mixing time of 1 min passes the final raw mix from the mixer 3 in an apparatus 10 for producing the tile blanks by molding and heating. this can be done metering volumetrically, after which the weight of the volumetrically determined amount determined on the raw mixture and for controlling the water and foam amount for the following batch via the regulator 5 and 5 'are used to produce a crude mixture as constant as possible density. After removal from the mold the block blanks ground stacked on hardening cars and transported to an autoclave 11, where they are subjected to steam curing, and leave the autoclave as finished Kalksilikatsteine.

When slaked lime is used instead of quicklime, it is fed directly from the silo 1 "the mixer 3 as well as the sand, as shown in phantom in FIG. 1.

In FIG. 2, the hole forming a tile blank is shown in the flow. First, a heated mold is 20, filled by a filling 21 with raw mix a certain amount of measured votumetrisch; Picture a. Thereafter, the mold 20 is placed under downward movable, arranged in the desired hole pattern and attached to a supporting plate 22 spikes 23, the free ends of the mandrels 23 are located approximately at the level of the recesses in a cover plate 24 for mold 20, image b. Thereafter, the mandrels 23 are first moved down to the top panel 24, to the cover plate 24 has reached the intended end position corresponding to the height of the manufactured stone, after which the mandrels 23 further down into it down through the openings in the cover plate 24 in the mold 20 until it shortly decide on the bottom plate 25 of the mold 20, image c. The mold 20 is now closed and the caused by the mandrels 23 displacement of the crude mixture, the entire mold 20 filled with the formation of sharp edges on the blank. In this retracted condition of the mandrels 23 in the closed mold 20, a heating of the located in the mold 20 crude mixture during for example 0.5 to 1 min, for example, about 80 ° G, whereby the temperatures of the individual pins 23 and the walls of the mold 20 in such a way are controlled so that a uniform temperature distribution over the blank, which rises slowly to the final temperature during the initial period of the clock shows. This heating results in an inactivation of the retarder and an activation of the accelerator for the cement, whereby a setting of the cement, however, no substantial reaction of the calcium hydroxide takes place, so that the molded blank after molding has sufficient strength to withstand subsequent handling , The blank 26 is preferably removed from the mold that first the side walls a piece or eliminated, if resuming, image d, after which the mandrels 23 of the mold 20 are removed simultaneously with or after the sidewalls and then the cover plate 24, image e. The blank 26, image f is then removed from the base plate 25 and, for example, stored on a conveyor to an autoclave, image g. Thereafter, the side walls of the mold 20 are brought back into position on the bottom plate 25, picture h, then (as well as the spines 23) treated with a release agent to become about sprayed, image i, and the sequence begins again.

Obviously can be in this type of molding the shape or a series of successive forms on a cyclically rotating belt or immovable, with about the forms in position can be brought filling devices and thorns or order with respect to the filling means and the pins reciprocally. The total time required for one cycle is just above the residence time of the blank in the form of 20th

Fig. 3 shows in detail partial retraction of the mandrel 23, the first (formed tapered) with its free end portion 23 'is approximately at the level of the cover plate 24. First, the cover plate 24 with the mandrels 23 downward process until it reaches the intended height of the stone, on their downward movement is stopped while the free end 23 'tapered mandrels 23 moved further into the mold 20 until it is just above the bottom plate 25 are thereof. Due to the conical shape of the mandrel 23 and the lower end portion 23 'with a larger taper both the retraction and removal from the mold is facilitated.

The cover plate 24 is shown in Figure 4 for a specific hole pattern and has a number of more or less long running parallel by narrow webs separate openings 27 into corresponding pins 23, which are (still axially conical) formed corresponding plate-shaped, retractable are closed and when retracted the openings 27th The shape of the cover plate 24 corresponds to the view of the tops of the thus formed blanks 26th

In Fig. 5 an arrangement of spikes 23 is shown in perspective, as that shown for another hole pattern in Fig. 4 are fixed to a supporting plate 22. The conicity of the pins 23 and the end portions 23 'in this case is not shown for reasons of simplification.

The embodiment 6 shown in Figs. 8 to an apparatus for producing stone blanks has a base frame 30 which is supported via rubber buffer 31 on the substrate 32nd On the base frame 30 a in the embodiment shown horizontally along by means of a piston-cylinder unit 33 guides 34 reciprocating slide 35 arranged, on the one hand, the bottom plate 20'trägt 25 of the mold 20 and the other part a the side walls of the mold 20 forming mold box , The flask 20 'is in this case fixed to a frame 36, which is in turn to vertical columns 37, which are arranged adjacent to the sides of the carriage 35 to the guides 34, out and up by means of piston-cylinder units 38 move up and down.

From the base frame 30 also extend vertically upward two columns 39, on which a crosshead 40 down by means of a corresponding drive and is guided downward move. At the cross head 40, the supporting plate 22 with the spikes 23 (which are indicated in Fig. 6 only as dashes) attached. The mandrels 23 can by means of the crosshead 4 .- {} between the positions shown in FIG. 3 above, and be moved into the mold 20.

The cover plate 24 for the mold 20, which is represented by solid lines used in Fig. 6 in its lower position in the molding box 20 'is fixed to two rods 41, which on to a further cross-head 42 which is arranged above the yoke 40 and also the columns 39 is guided are fixed. there is a support 43, from which two piston-cylinder units 44 extend downward to the crosshead 42, so this set up and can be moved up to the tops of the columns. 39 The cross head 40 is connected to the crosshead 42 via a piston-cylinder unit 45 so that 44 the crosshead 40 with the mandrels 23 and the cover plate 24 together can be moved initially by operating the piston-cylinder units downstream, wherein the cover plate 24 at the end of the movement has reached its end position, , after which the piston-cylinder unit 45 is actuated to retract the mandrels 23 in the mold 20th Corresponding stops for the movement of crossheads 40 and 42 may be provided.

Figure 8 also illustrates the displacement of the carriage 35, which is initially in the filling (the filling is here but omitted for clarity), then moved to the molding and heating position and from there transported the finished blank 26 into the removal position ,

The heating means such as heating cartridges for the mandrels 23 and contact heating of the mold 20 are not shown here as well as a device for wetting the mold 20 and the mandrels 23 with a release agent.

Fig. And 10 show the omitted in Figs. 8 to the filling station with a filling device 50th

In this embodiment, the filling device 50 essentially comprises a cup-shaped container 51 which can be filled from a (not shown) mixer with crude mixture 52nd While the dosage of the raw mix volumetrically into the container 51, the container 51 with the associated parts, which are suspended on ropes 51a, weighed, whereby a Zugkraftmeßdose 51 b, the corresponding measurement signal provides so that via a control circuit, the addition of water and / or foam for raw mix to obtain a practically constant density can be controlled.

Above the container 51 a guided on two guide rods 53 piston 54 is arranged, which can be retracted from the top into the Behätter 51st The container 51 is closed at its underside by means of a slide 55 which can be opened for emptying of the container 51 into the mold box 20 ', while the piston 54 retracted to the full emptying and thus to clean the container 51 during or after the emptying procedure in this is. Instead of the slide 55 and a one or two-piece flap could be used.

The container 51 is arranged in the frame 56 in a frame 56 between a filling station for the container 51 (not shown) through one volumetrically operating metering device which is connected to the (not shown) mixer, and a filling station for the mold 20 via has guides 57 in which the container 51 with wheels 58 supported, verfahrbär by a (not shown) drive, while the punch 54 in the filling of the form 20 stationary suspended in the frame 56 and up through a piston-cylinder unit 59 and traversed ,

The molding of the tile blank in the mold 20 takes place substantially without pressure, because of the tolerance of the stone blank limiting cover plate 24 in this case inevitably exerted, low strength, which also serves for the formation of sharp edges of the stone blank, only leads to a practically negligible pressure even at a suitably be made overfilling the mold to a corresponding crushing of foam pores does not somehow considerable densification of the tile blank the result, as is the present invention also desired.

It is at this point noted that after heating, surprisingly does not come during the extension of the mandrels 23 from the blank 26 to a collapse of the lands due to the formation of a leather-hard surface, although it is in the shaped of the mandrels 23 holes these blind holes, so that no air can enter from the opposite side of these holes, and one would expect that the footbridges of the blank occur by vacuum forming or at least could be considerably damaged. Surprisingly, the pore structure of the raw mix in the blank is maintained, although the foam is destroyed by the heating.

The mandrels 23 can partially (z. B. in three steps) or continuously along its length and each other differently heatable be designed to achieve not only a very uniform heating of the present in the form of 20 raw mix 52, but ultimately or stones initially. to obtain blanks with the greatest possible homogeneity, which, moreover, by a regulation or control of the heating of the mandrels 23 and the mold 20 for the purpose of heating the raw mix 52 towards a uniform heating of the mold 20 and the mandrels 23 and thus a generally uneven heating the raw mix 52 energy is still saving. For this reason, the mandrels 23 are preferably generally not heated with the same intensity, but further out in the region of the molding box 20 'lying mandrels 23 may be used to achieve uniform heating of the raw mix 52 with other, usually heated lower intensity than further inside mandrels 23rd

Fig. Figure 11 shows a volumetrically operating metering device 60 which is positioned below the mixer 3, which is provided with a stirrer 3 'and a funnel-shaped outlet. The metering device 60 is composed of two semi-cylindrical parts 61, 62, said part 62 - are arranged coaxially with the part 61 - in relation to the fixed part 61 is rotatable about an axis and slides along with its outer surface to the inner surface of the part 61st The part 61 has an inlet opening 63 in the region of the funnel-shaped outlet of the mixer 3 and an emptying opening 64 which is directed obliquely downwards. The part 62 has an outwardly open chamber 65 in which a suction piston 66 is disposed movably by means of a piston-cylinder unit 67th To fill the chamber 65 the opening of which is aligned with the inlet opening 63 of the part 61 while the Saugkol ben 66 is in its extended state, in which its outer surface with the outer surface of the part 62 is aligned. Thereafter, the suction piston 66 is moved by a certain distance inwardly, which is determined by an encoder 68th In this way, the crude mixture is volumetrically sized sucked into the chamber 65th Displaced air can adjacent through air outlet openings 69 emerge to the inner chamber end. The encoder 68 is used to adjust the volume according to the manufactured stone size.

The part 62 is then rotated with a filled chamber 65 opposite the part 61 (in Fig. 11 in a counterclockwise direction) until the opening of the chamber 65 with the discharge opening 64 of the part 61 is aligned. The piston 66 is again extended and thus the chamber 65 emptied. Thereafter, the part 62 is rotated back to re-fill the chamber 65 with the edge 64 'of the discharge opening 64 serves as a scraper edge for residues of the crude mixture. The turning of the part 62 relative to the part 61 can be made by means of a swing cylinder. Optionally, the part 62 can weigh them filled chamber 65 and the measured value thus obtained will be used to adjust the density of the crude mixture.

If multiple forms 20 are available, many chambers are accordingly 65 provided with pistons 66 and openings 63, 64th

In Fig. 12, a further embodiment of an apparatus for producing stone blanks is shown schematically, which comprises a conveyor belt 80 in the form of a steel band which is guided around two deflection rollers 81, of which at least one is driven. The upper run of the conveyor belt 80 can (not shown) running to support a steel plate. The flask 20 'is initially below the dosing device 60, which is connected to the mixer third The filled with the desired amount of crude mixture flask 20 'is then moved into the forming station where the mandrels 23 and 24 DeckelpJatte about in the manner described above for forming the blank into the mold box 20' are retracted.

In addition to the above-described indirect heating of the raw mix in the mold 20 or no indirect heating the raw mix is ​​heated through a high frequency field, wherein the conveyor belt 80 and the lid plate 24 serve as capacitor plates.

The flask 20 'is connected to a carriage 82, through which the molding box 20' back and forth between the filling and the forming station and is reciprocally movable, for what purpose on the carriage 82, a piston-cylinder unit engages 83rd

When the molded blank 26 has reached a sufficient strength, the molding box 20 'relative to the carriage 82 is (made for example by means of a piston-cylinder unit and vertical rods, not shown) is raised, after which the mandrels 23 and the lid plate 24 are removed. The unmolded in this way blank. 26 is further transported by the conveyor belt 80 in order to be taken over by a stacking device 84 which is equipped for example with grippers 85 at the end of the conveyor belt 80th

Conveniently, the conveyor belt of the filling station are sprayed about by means of a nozzle 86 with a release agent. An appropriate spray 87 is provided for the flask 20 '. Instead, however, may be immersed so that adhering residues of the crude mixture are removed there and the molding box 20 'and the pins 23 in a preferably energized with ultrasonic release dip.

At the discharge end of the conveyor belt 80, a cleaning device 88 for this purpose in the form of a stripping roller, a scraper o. The like. Be provided.

The operation of the apparatus shown in F i g. 12 is particularly suited to the heating process to shorten to achieve the desired stability of the blank 26 such that it is already removed from the mold when it has such a strength that, although he readily by means of transportable transport belt 80, however, is not yet gripped by the stacking means 84th as their strengths not yet sufficient. The further consolidation of the blank 26 to the required blank strength is then made by reheating about by passage of the blanks transporting 26 conveyor belt 80 under an after-heater 88 with z. B. infrared radiators or through a heating tunnel o. The like.

The method and apparatus of the invention allow the production of bricks with virtually ideal properties on extremely fast and therefore economical manner, namely bricks, which have excellent thermal properties due to their low density and their perforation and beyond relatively even with larger dimensions easily and are easy to handle, so that can achieve a corresponding increase in output volume.

As already explained, the soaking of the raw mix is ​​carried out in the mold 20 with a high frequency field and, if necessary, additionally by means of contact heat (the latter on the mold 20 and the mandrels 23). In the first case, the bottom plate 25 and the lid plate 24 of the mold 20 may be used as capacitor plates, or the high-frequency field is formed with alternating polarity between the mandrels 23 and two outer walls of the mold 20 to which the high-frequency voltage is applied.

The production of bricks according to the invention will be described below with reference to Step Example len. According to these examples are 10-DF-stones, that is, having the dimensions 148 mm x 300 mm (base) x 238 mm (height) made that have a hole proportion of approximately 41%. The individual components are provided in this case weighed and the foam dosage set by code of foaming a foam gun. The dry components are added to a mixer, and after its start, the metering of water begins. After 35 seconds mixing time, foam is added. After the foaming time of 8 sec and a further post-mixing in of the foam is carried out for 25 sec. After the total mixing time of 60 sec, the dosage of the raw mix is ​​carried out in a form that is as well as the associated mandrels heated. After about 70 seconds standing time in the mold is removed from the mold and transports the blank to an autoclave where it is subjected in a known manner to steam curing.

example 1

Prepare a crude mixture of the following components ago:<ul><li>10 kg quartz sand, washed natural sand with a grain size between 0 and 4 mm, average particle size 0.6 to 1 mm,</li><li>5 kg of quartz powder; Particle size &lt;0.16 mm,</li><li>2.2 kg of water,</li><li>1.5 kg hydrated lime to DIN 1060,</li><li>2.5 kg cement, quick-setting cement Heidelberg (Heidelberger Portland Zementwerke AG, Cap, Federal Republic of Germany),</li><li>600 g foam (sulfated fatty alcohol, Chemical Fabrik Grunau GmbH, lllertissen, Federal Republic of Germany) in accordance with a foam duration of 8.5 sec and a Schaumrohdichte of about 80 kg / m3.</li></ul>

The resulting crude mixture has a temperature of 15 ° C and is poured into a mold whose box a temperature of 75 ° C and their spines have a temperature above 76 ° C and below 82 ° C. Prior to the forming mold, and mandrels are treated with a release agent. After a standing time of 80 sec is removed from the mold. The congestion degree of the shape is 12%.

The crude mixture has a bulk density of 1150 kg / m³, The blank a body density 1285 kg / m³ and a blank strength greater than 0.12 N / mm² and the finished stone a body density 1155 kg / m³, An overall density of 685 kg / m³ and a strength of more than 2.5 N / mm²,

example 2

Prepare a crude mixture of the following components ago:<ul><li>10 kg of sand, as in Example 1,</li><li>5 kg boiler slag, broken into a grain size of 0 to 4 mm,</li><li>2.3 kg of water,</li><li>1.5 kg of hydrated lime,</li><li>2.25 kg cement as Example 1,</li><li>500 g of foam, such first</li></ul>

The resulting crude mixture has a temperature of 20 ° C and is poured into a mold whose box a temperature of 78 ° C and their spines have a temperature above 77 ° C and below 83 ° C. After a standing time of 70 sec is removed from the mold. The congestion degree of the shape is 15%.

The raw mix has a bulk density of 1250 kg / m³, The blank a body density of 1375 kg / m³ and a blank strength greater than 0.12 N / mm² and the finished stone shards a density of 1240 kg / m³, An overall density of 735 kg / m³ and a strength of 5 N / m_m. 2

example 3

Prepare a crude mixture of the following components ago:<ul><li>12 kg of sand, as in Example 1,</li><li>3 kg fly ash with a grain size of 0 to 4 mm,</li><li>2.8 kg of water,</li><li>1.5 kg of hydrated lime,</li><li>2.25 kg cement as Example 1,</li><li>420 g of foam, such first</li></ul>

The resulting crude mixture has a temperature of 20 ° C and is filled into a mold that is heated as in Example 2. FIG. After a standing time of 60 sec is demolded. The congestion degree is 7%.

The crude mixture has a bulk density of 1490 kg / m³, The blank a body density 1595 kg / m³ and a blank strength greater than 0.12 N / mm² and the finished stone shards a density 1435 kg / m³, An overall density of 855 kg / m³ and a strength of 5 N / mm²,