US3600481A

US3600481A - Method for more rapidly producing aeroconcrete building elements

Info

Publication number: US3600481A
Application number: US873747A
Authority: US
Inventors: Walter Lanz
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-06-08
Filing date: 1969-11-26
Publication date: 1971-08-17
Anticipated expiration: 1988-08-17
Also published as: DE1683888A1; BE699492A; CH468876A; SE336548B; GB1173070A; AT263598B; NL6707875A

Abstract

A METHOD FOR CONTINUOUSLY PRODUCING BUILDING ELEMENTS OF AEROCONCRETE, WHEREIN COMPONENTS OF A MULTI-PART FORM INCLUDE BOTTOM PORTIONS WHICH ARE RECIRCULATED TO A FILLING STATION AFTER SETTING OF THE ELEMENTS BEING PRODUCED WHILE FRAMES AND INSERTS OF THE MULTI-PART FOAMS ARE RECIRCULATED AFTER STABILIZATION OF THE AEROCONCRETE WHICH HAS BEEN POURED, AND PRIOR TO THE USE ARE CLEANED AND GREASED. BY USING A MIXTURE OF ALUMINUM AND LIMESTONE POWDERS AS THE BLOWING AGENT AND BY PREHEATING THE COMCRETE MIXTURE TO ABOUT 20-35*C., THE AEROCONCRETE IS STABILIZED SUFFICIENTLY TO PERMIT REMOVAL OF THE DIE FRAMES WITHIN ABOUT 36 MINUTES AFTER POURING.

D R A W I N G

Description

W. LANZ Aug. 17, 1971 METHOD FOR MORE RAPIDLY PRODUCING ABROCONCRBTE BUILDING ELEMENTS 5 Sheets-Shoat 1 Original Filed May 29, 1967 m m w."

or m r Z E T INVENTOR wallrer Lanz wee, 2-.

Aug. 17, 1971 W L METHOD FOR MORE RAPIDLY PRODUCING AI'IHOCONURETE BUILDING ELEMENTS 3 Shoots-Shoot (5 Original Filed May 29, 1967 l 6 \NF ma 9 v mw J W V o b a kwzvm 35 LC... M rm 5 arlbu k F m 6/ u wa A; "I" l mm Cl INVENTOR WaHer Lanz United States Patent US. Cl. 26442 2 Claims ABSTRACT OF THE DISCLOSURE A method for continuously producing building elements of aeroconcrete, wherein components of a multi-part form include bottom portions which are recirculated to a filling station after setting of the elements being produced while frames and inserts of the multi-part forms are recirculated after stabilization of the aeroconcrete which has been poured, and prior to the use are cleaned and greased.

By using a mixture of aluminum and limestone powders as the blowing agent and by preheating the concrete mixture to about -35 (3., the aeroconcrete is stabilized sufiiciently to permit removal of the die frames within about 36 minutes after pouring.

This application is a continuation of Ser. No. 642,038, filed May 29, 1967 and now abandoned.

This invention relates to a method for mechanized production of building elements of aeroconcrete having hollow spaces, and a plant for carrying out this method.

It is known to produce building elements with high isolating values of aeroconcrete for construction of monolithic walls. In this case production is effected by means of relatively small dies with a decomposable die frame and core portions insertable into the die by hand. When producing several elements in one die several separating walls insertable into the die frame by hand and a core portion associated with each element insertable by hand are provided. This prior procedure is only suitable for producing relatively small quantities of elements, whereby the required working time is relatively high. With the prior method an aeroconcrete mixture was used requiring about two hours for completely expanding and stabilizing. Finally the cores were immediately removed from the mixture in the prior method after complete stabilisation, since later removal would be impossible without damaging the elements. However, the decomposable die frame was only decomposed and removed after complete setting of the elements and then the elements were lifted off the die bottom.

The described prior method and the device serving for carrying it out are badly suited for a mechanized production of elements and it is the aim of the present invention to provide the conditions for economic production of elements. A first solution resides in the idea that the most expensive and heaviest parts of the die, namely the die frame and the die insert should be recovered at a stage as early as possible of the production of the elements and should be made available for another casting operation. For this purpose, the method according to this invention is characterized by providing a number of dies, repeatedly assembling, filling and providing with core means and separating wall means individual dies in a filling station at one end of conveyor means, removing said core means, separating wall means and frame portion from said bottom portion simultaneously or within short time intervals at the other end of said conveyor means after a transfer time corresponding to the time required for stabilisation of the mixture, and reconveying said core means, separating wall means and frame portions through a cleaning plant and a greasing plant to the filling station, while the building elements remain on the said bottom portion until complete setting of the mixture, whereafter the bottom portions are returned to the filling station. Consequently, the die frame and the cores or a single die insert comprising cores respectively are recovered practically at the same time, this allowing not only reduction of the number of die frames but also simplifies the retransport of the die frames and core inserts from the dismantling station to the casting and filling station.

It is another object of this invention to increase the producing capacity of a plant of a determined size and with a determined number of dies and with good mechanical and isolating properties by substantially reducing the time interval from the casting to the dismantling operation, this being achieved in accordance with this invention by the use of a mixture comprising 32-39 weight percent cement, 39-32 weight percent sand, 25-30 weight percent water and at least .5 weight percent expanding agent, whereby the mixture has a temperature of 28-35 C. when poured into the die. The expanding agent specified in Swiss Patent No. 360,332 and consisting of 1-2 parts by volume of aluminum powder and 1-2 parts by volume of limestone powder may preferably be used. With such a mixture sufiicient stabilization within 30 to 40 minutes may be obtained, whereafter the cores and the die frame may be removed and returned. It is thus possible to obtain a. high productivity with a relatively small number of die frames and core inserts and with limited size of the plant but relatively high operating speed and short operating sequence respectively.

This invention also relates to a plant for carrying out the above method, this plant comprising a production line having conveyor means for simultaneously transporting a number of dies from a filling station to a dismantling station, a cutting device in said dismantling station for removal of portions of the stabilized mixture extending upwardly from the die, a running period of said conveyor means from said filling station to said dismantling station adapted to the time interval required for stabilization of the mixture, and by means in said filling station following each other in the running direction of the conveyor means for positioning of the bottom portion of the die, for putting the frame portion of the die onto said bottom portion, for stirring and pouring said mixture and for inserting said core means and separating wall means. The filling station comprises the necessary equipment for assembling and filling the dies. This plant, specifically adapted to the requirements of the production of aeroconcrete preferably has a first closed circulation for the die frames and die inserts which are retransported from the dismantling station through a cleaning station and a station for application of greasing mediums to the filling station, whereas in a second circulation the die bottoms with the dismantled elements are brought into a storing plant until the elements are completely set, and are retransported from this storing plant through a cleaning and greasing plant to the filling station. A substantial advantage of the method and plant according to the invention :resides in the fact that only the simplest, lightest and cheapest part of the die, namely the die bottom, is required until the elements have completely set.

The invention will be explained below in detail with reference to the accompanying drawing illustrating by way of example an embodiment of the plant according to the invention.

FIG. 1 is an elevation of the important part of the plant,

FIG. 2 is a top view of the part of the plant shown in FIG. 1,

FIG. 3 is a top View of a die,

FIG. 4 is an elevation of this die,

FIG. is a partial section of the die along line V-V in FIG. 3,

FIG. 6 is a partial section along line VIVI in FIG. 3, and

FIGS. 7-9 show details of a guiding device.

The plant illustrated in FIGS. 1 and 2 has a straight producing line along which casting dies or molds may be transported from a filling station to a dismantling station. The filling station of the production line has a fixed work table 1, along which the casting dies may be advanced stepwise from the right to the left by means of a hydraulic cylinder 2 indicated in FIG. 2. In a first place A, the die bottoms 3 schematically illustrated in FIGS. 1 and 2 as fiat sheets, are put onto the table 1. Individual die bottoms put on the table are then shifted to the left into position B by means of the advancing device 2, in which a die frame 5 is put onto the bottom from a return ramp 4 by means of a suitable hoist. In this way a die of parallelepipedic form open at the upper side is obtained into which a mixture may be poured. By the next stepwise advancing movement, the bottom 3, provided with a die frame 5 or the open die respectively, is shifted into a filling place C in which a mixture described in detail later on is poured from a mixer 6 into the open die. By the next advancing step, the filled die is brought into an operating position D in which a schematically indicated core insert 8 may be brought into the open die and into the mixture contained therein. The die provided with the die insert 8 moves from the table 1 onto the right-hand end of a conveyor line 9 during the next operating period. This conveyor line preferably consists of a suitable sliding Way along which the bottoms 3 of the dies may slide, and of a conveyor chain 10 having driving members, not shown, for driving one die each. The dies are continuously shifted without vibration to the left-hand end of the sliding way by the chain 10.

Water, sand and portland cement may be fed to the mixer 6 from three

containers

11, 12 and 13 through suitable dosing devices not shown, and through a common collecting funnel, while the expanding agent such as equal parts of aluminum and limestone powders, is directly fed to the mixer 6 from a small container 15.

At the outlet of the conveyor way 9, a table 16 extends transversely to the direction of this conveyor way. By means of a device similar to the device 2, the dies arriving from the conveyor way on the table 16 may be shifted along this table into positions E and F. By means of a bracket 17, a knife 18 in the form of a snowplow is supported above the table, the lower edge acting as a cutter being disposed at a distance above the table 16 corresponding to the height of the die, such that the die may be passed below the knife into position E practically without vertical clearance. Two stacking trucks 19 and 20 are disposed at the side of the table 16, which are coupled with each other and may be displaced on a track along the table 16. The stacking truck at the side of position F serves for taking up the die bottoms carrying elements, while the die bottoms with elements stacked above each other on the other stacking truck are simultaneously lifted out by means of a fork truck and may be transported into a warehouse, for example in which the elements are stored for setting.

Hoists

21 and 22 respectively, schematically illustrated in FIG. 1 only, are disposed above positions E and F, which serve for lifting the die insert and the die frame. respectively, from the die bottom and to life them onto the one of two conveyor bands 23 and 24 respectively. The upper sides of both conveyor bands first pass through a cleaning device 25 and into a device 26 for greasing the die frames and die inserts, respectively, with a suitable greasing agent. The cleaning device 25 may include nozzles for cleaning the frames and die inserts by means of vapour, compressed air, water, solvent agent or the like or a combination of several of these nozzles. The greasing device 26 includes a spraying device for spraying preferably a mixture of fat and oil of such a consistency that fine vaporization and spraying and forming of continuous well adhering layers is possible. From the greasing device 26, the die inserts and die frames slide over the slide ways not designated to the places from where they are transferred onto the die bottom and into the already filled die respectively in the filling station.

In FIGS. 3 to 6 the particular die is illustrated. It consists, as mentioned above, of the fiat die bottom 3, the die frame 5 and the die insert 8.

The die frame has the form of a rectangular frame of sheets 29 reinforced on the full circumference by U- profiles 30 welded to the sheets 29.

The die insert has a grid of separating

walls

31 and 32 respectively of steel sheets welded to each other and disposed at right angles. These separating

walls

31 and 32 form a honeycombed grid so that with the die insert 8 put into the frame 5 elongated chambers 33 of rectangular cross section are formed. Core portions made of welded sheets and centrally extending through four chambers 33 are connected to the transverse separating walls 31. As shown particularly in FIG. 6, the core portions substantially consist of a U-shaped bent metal-sheet canal 34 having two transversely extending cuttings 35 in each chamber 33. Each cutting 35 is closed by a V-shaped bent metal sheet 36 at its upper side and by means of metal sheets 37 at its faces, such metal sheets having a V-shaped cutting corresponding to the form of the metal sheet 36 at their upper end. The ends of the core portions are closed by means of end metal sheets 38. Finally, all core portions are closed at the upper side by means of a plane covering metal sheet 39.

As is seen from FIG. 6, the cores are somewhat wider at their upper side than at their lower side so that they may be lifted out of the mixture filling the chamber 33 relatively easily. Thus, a core extends in longitudinal direction through each chamber 33, hvaing an upper continuous horizontal prismatic portion of the sectional form seen in FIG. 6 and three vertical column-shaped portions separated from each other by the cuttings 35. These cores correspond to the hollow spaces of the finished elements or stones which thus have two solid lateral wall portions interconnected by two transverse ribs corresponding to the cuttings 35.

Rings 40 are provided at four crossings of separating

Walls

31 and 32 respectively, at which the die insert may be lifted.

Production of hollow elements or stones of aeroconcrete by means of the illustrated plant explained above is as follows:

As already mentioned, the die bottoms 3 returning from the store, cleaned and greased at their upper surface are put into the filling station in position A, they are provided with a die frame in position B and filled in position C to a predetermined height with the previously prepared mixture. The mixer 6 is dimensioned for preparing quantities suitable for filling one die, and the required quantities of water, sand, portland cement and expanding agent are admitted from suitable dosing devices and mixed immediately after release of the previously prepared mixture. The die is filled in a well known manner to such a height that at the end of its expansion the mixture slightly swells over the die so that in any case the die is completely filled and the excess material may be removed. When the die is still in position C, or immediately after its arrival in position D, the mixture is again intensively stirred and distributed in the die so that all portions of the mixture, particularly constituents of different weight of the sand are uniformly distributed in the die. The die insert 8 is then inserted whereafter the die arrives on the conveyor line 9.

During the continuous gradual displacement of the die along the sliding way 9, development of gas in the mixture begins, and the transfer time between the filling station and the dismantling station is so adjusted that upon arrival of each form in the dismantling station, that is on the table 16, the mixture has completely solidified and stabilized, but not yet set or hardened. Each die shifted from the line 9 onto the table 16 is pushed below the knife 18 into position E whereby mixture expanded above the chambers 33 is sheared off evenly. The covering sheets 39 promote clean cutting of the excess portions of the mixture in that the knife may slide on these sheets. In places where rings 40 are provided, the knife has openings through which the rings 40 may pass. When the so treated die arrives in position E of the dismantling station, the die insert 8 is first lifted out and is put onto the conveyor band 23. When the next die is shifted into position E, the die laying in this position is pushed on into position F in which the frame is now lifted and put onto the conveyor band 24. After lifting out of the frame the die bottom together with the dismantled elements is shifted into the stacking, truck 19 placed in front of position F. While the stacking truck 19 is filled, several die bottoms with dismantled elements are. simultaneously removed from the stacking truck 20 by means of a fork lift truck not illustrated and are placed into the store for setting. When the stacking truck 19 is filled, both stacking trucks are shifted upwardly in FIG. 2 so that the stacking truck 20 unloaded in the meantime arrives again in front of position F and is gradually filled While the die bottoms with the dismantled elements are removed from the stacking truck 19.

The die inserts and die frames are cleaned and greased in the manner indicated above during their retransfer over the conveyor bands 23 and 24 parallel to the producing line, and then return directly to the filling station where they may be used again. The elements which were produced in the manner explained above are left in storage for about 2 /2 days until the elements have completely set, whereafter the elements are shifted off and stacked or transported away, While the remaining die bottoms are cleaned and greased and returned to the filling station.

It is obvious that for a determined expenditure, that is for a determined size of the plant and for a determined number of available die frames and die inserts, the production capacity depends in the first line from the time interval from the filling operation to dismantling. This time may be reduced to about 36 minutes when a mixture is used comprising 32-39, preferably 37.5 weight percent portland cement, 3932, preferably 37.5 weight percent sand, 2530, preferably 28.5 weight percent water and at least .5 Weight percent expanding agent. Further care must be taken that during the casting operation, the mixture has a relatively high temperature of 20- C., this being achieved by placing the plant in a room heated to at least 20 C. and preheating the Water to 30- 32 C. The producing capacity is further determined by the sequence, that is, the time interval between each casting operation and dismantling operation respectively. Assuming that 20 dies are disposed between the filling station, and the dismantling station an interval of 1.8 minutes is required, that is, each casting operation must be completed within time intervals of 1.8 minutes. The duration of the operating sequence is limited by the fact that the die insert must be put into the mixture poured into the die before development of gas begins. With the mixture indicated above, gas development begins relatively soon and care must be taken that the die insert is inserted not later than 4 minutes after the end of the casting operation.

Careful greasing of the die portions in a suitable moment is of substantial importance for the whole producing operation. Greasing should be effected immediately before use of the die frames or die inserts, if possible, so that the greasing device 26 should be located as near to the filling station as possible.

Various parts of the plant and operations may differ from those disclosed above for the illustrated embodiment.

While it is assumed for this embodiment that the mixture is still distributed and stirred by hand in position C or immediately prior to insertion of the die insert in position D, another position may be added between positions C and D in a filling station of correspondingly increased length, in which the filled mixture may be stirred. In this case a mechanical stirring device, having by way of example a number of relatively small stirring propellers with vertical shafts or having a reciprocating stirring rake may be provided, which may be lowered into the die frame without, however, touching the bottom and damaging the layer of grease on the same.

It is not indispensable to lift out the die insert and the die frame in different places and in two separate operations, and it might under circumstances be an advantage to simultaneously lift out both parts with the same hoist and to put them onto the two conveyor bands 23 and 24. In order to avoid any relative transversal displacement of these die portions during removal thereof, means may be provided for rigid interconnection of both die portions for lifting them. If occasion arises, the hoist, for instance a vertically guided hydraulic press, may be provided with a coupling device allowing simultaneous rigid coupling with both die

portions

5 and 8 to be lifted, and to lift them in precise vertical direction. At the same time it may be necessary to hold the freely accessible portions of the mixture in the chambers 33 by means of a counter holder or a holding-down appliance adapted to be lowered onto the said freely accessible portions of the mixture but exerting practically no pressure onto such mixture portions, in order that no portions of the mixture may be pulled upwardly with the die frame or die insert. The holding-down appliance may be a part of the vertically guided lifting appliance mentioned above for simultaneously lifting the die frame and die insert.

As already mentioned, it is important that the die insert and die frame are lifted out from the unset and consequently easily deformable mixture exactly vertically without lateral displacement. As shown in FIGS. 7 to 9, outer orienting angles 50 are mounted on levers 51 swingable round a shaft 52 by means of a double-acting hydraulic cylinder 53. The levers 5 1 engage into and are axially guided in slit cuttings 54 of the table 16 in position F in all corners of the die bottom 3. When the orienting angles 50 are in their upper operative position shown in FIGS. 8 and 9, they tightly enclose the corners of the die bottom and thus exactly determine the position of this bottom. Guiding angles 55 mounted inside the orienting angles 50 in the upper part thereof, engage the corners of the reinforcements 30 of the die frame 5 and guide the same in vertical direction when it is lifted off the die bottom. The legs of

angles

50 and 55 extending in the swinging direction have their ends bent outwardly for properly engaging and orienting the die bottom and engaging the die frame when swung into operative position. As shown in FIGS. 7 and 8, the die bottoms have enlarged rim portions 56 butting against each other so that gaps are formed between adjacent die bottoms allowing entrance of the angles 50. The angles 50* and 55 may be swung outwardly into a substantially horizontal inoperative position below the table 16 for allowing shifting of another die from position E into position F and for shifting a die bottom with dismantled elements from position F into the stacking truck.

Since no displacement of the die frame on the die bottom must occur when applying the guide angles 55, care must either be taken that the die frames can only be placed onto the die bottoms in a predetermined relative position, or in position B of the filling station a corresponding orienting appliance should be provided in order that the die frames are always positioned on the die bottoms in precisely prescribed position.

For producing elements of various forms, it is only necessary to use die inserts of different type. The die frame and the die bottom may thus be used for all kinds of elements.

What I claim is:

1. A method for mechanized production of building elements of aeroconcrete having hollow spaces, which comprises the steps of:

feeding a succession of die bottom members along a given path,

placing die frames from a source thCI'COlf onto the successive bottom members at a first station along said path to provide die bottom frame assemblies presenting open topped die cavities,

introducing a mixture of concrete and an expanding agent, said mixture consisting essentially of 3239 weight percent cement, 39-32 weight percent sand, 25-30 weight percent water, and at least .5 weight percent expanding agent consisting essentially of 1-2 parts by volume of aluminum powder and 1-2 parts by volume of limestone powder with the mixture having a temperature of 20-35 C. when poured into the die cavities, and inserting core means and separating wall means, from a source thereof, into the die cavities at a first region along said path adjacent said first station within a time interval of not more than 4 minutes after pouring the mixture,

removing the core means, separating wall means, and

the die frames from successive assemblies at a second region along said path remote from said first region, recycling the removed die frames, core means and separating wall means from said region toward said first station and said first region for rapid reuse to form the respective sources for said die frames, core means and separating wall means while transporting the die bottom members with building elements thereon to a remote region for setting of the concrete forming the building elements, cleaning and greasing the die frames, core means and separating wall means during recycling thereof, maintaining the feed of the filled die assemblies such that the time interval between the introduction of the mixture at said first region and removal of the die frames, core means and separating means at said second region is about 36 minutes, removing the building elements from the die bottoms after the concrete is set, and recycling the die bottoms from said remote region to the inlet of said path for delayed reuse. 2. A method according to claim 1, characterized in that said expanding agent essentially consists of equal parts of aluminum powder and limestone powder.

References Cited UNITED STATES PATENTS 3,442,991 5/1969 Lanz 26442 FOREIGN PATENTS 360,332 3/1962 Switzerland 264-42 DONALD J. ARNOLD, Primary Examiner J. H. MILLER, Assistant Examiner US. Cl. X.R. 264-87