EP0161374B1 - Plant and method for making building panels of plaster - Google Patents

Abstract

The plaster panel casting plant according to the invention contains a mould casting machine in which a large number of vertical hollow moulds (23), open at the top, are arranged adjacently in the manner of a package. The elements limiting each hollow mould (23), specifically lateral mould rails (104, 105), rear and front separating plates (101, 102) and the lower stamp (112) forming the demoulding device, are compressed under high pressure (100 tons per 100 x 50 cm) when the plaster paste is poured into the mould and can move a few tenths of a millimetre apart for the purposes of easier demoulding. A novel gripping device (200) for sensitive plaster panels is also disclosed, in which the stack (202) of panels is gripped, not laterally, but from front and rear at the broad sides of the panels.

Description

The present invention relates to a system for producing molded building boards from plaster, in particular ceiling building boards.

The production of wall building boards from plaster is known. Such panels are used to create partitions in buildings of all types and occasionally also to clad existing walls. Gypsum boards have many advantageous properties so that they can be used in a variety of ways. Gypsum boards for walls are usually made with a length of 667 mm (= 2/3 m) and a width of 500 mm (= 1/2 m) and with modular thicknesses of 60, 70, 80 and 100 mm.

Mold casting systems have been developed for efficient production. They usually consist of the storage containers for fired gypsum and any additives such as reinforcing materials, setting accelerators or retarders etc. Then there is a metering and mixing device for producing a pourable aqueous gypsum slurry, which is then transferred to the actual casting machine, where a large number of plates in a molding box are cast vertically at the same time, for example 36 pieces. After reaching the setting strength, which allows molding and transport, the gypsum boards are simultaneously ejected from the molding box upwards by hydraulic means, gripped by a gripping device, placed on trolleys and dried in a long chamber oven for up to 72 hours.

In addition to the wall panels mentioned, there is an ever increasing need for ceiling panels, which, as the name suggests, are used for fastening to ceilings in buildings. They perform ornamental, sound and heat insulating functions in particular and are used as ceiling cladding or ventilation ceilings. Their dimensions in terms of length and width are usually 600 x 600 mm or 1000 x 500 mm, and they are requested and supplied with thicknesses of 15, 25, 30 and 40 mm.

It has so far not been possible to use the systems used for the production of wall building boards also for the production of ceiling building boards, because the small thickness of the ceiling boards makes it impossible for the hardened boards to be ejected from the molding box in that the boards break. Also, the gripping of the plates by the known and introduced gripping devices which engage on the narrow sides of the plates leads to the destruction of the plate due to the small plate thickness.

The ceiling panels are still manufactured in semi-continuous processes with the help of disassemblable individual molds. So you can arrange several stations on a horizontal turntable with a diameter of approx. 5-6 m. At the first station, the horizontal mold box, which is open at the top, is closed, the mold is sprayed with a separating oil and then filled with gypsum paste. The free surface of the form is smoothed out with a ruler. Then you place spacer rails and a cover plate, which represents the bottom of another, previously closed form. This is fed with gypsum paste as described above. Then continue until a stack of generally 8 or 10 horizontally superimposed shapes has been created.

Then the disc rotates an angle that corresponds to the position of the next molding box. The gypsum slurry hardens in the first molding box, while the second molding box is pretreated and set up as described.

The disc is rotated again by the same angle and the hardened plates - the hardening time is approximately 8 minutes - are shaped. This is only possible by opening the molding box on the four narrow sides, whereupon the plates are removed from top to bottom one after the other and placed by hand on the trolley, which, after being fully loaded, goes into the drying oven.

The production described is very labor intensive; 3 men can generally make no more than 75 plates per hour.

Plants and methods for producing molded building boards from plaster are known from LU-A-37.726 and DE-A-2.551.476.

The object of the invention is to provide a system which, in analogy to the production of the wall building boards, permits rational, improved and accelerated production, in particular of the thinner gypsum ceiling building boards, and in which a board breakage which also occurs with the previous, gentle and slow method of working, is reduced to a maximum.

The object is achieved by the system according to the invention; in a plant for the production of molded building boards from gypsum by casting a gypsum slurry, with a molding machine in which a plurality of hollow molds which extend vertically form a mold box in parallel in a package-like arrangement in which the hollow molds are formed by delimiting elements Devices that compress the molding box horizontally so that it absorbs the pressure of the building boards that expand as they solidify and relieve the pressure after the building boards have solidified, the invention is to be seen in the fact that the devices for compressing the molding box are single-acting, on both sides of the molding box attached, on the one hand on cover plates of the molding box and on the other hand acting on the delimiting elements penetrating hydraulic hollow piston cylinders, the horizontal displaceability of the delimiting elements by adjusting the stroke of the pressure piston in the hydraulic pressure cylinder to 0.1 to 0.25 mm per hollow mold or building board is limited.

Another object of the invention is a ver drive to the production of flat plasterboard, in which you pour an aqueous gypsum slurry into a mold box with a number of package-like hollow molds, let it solidify in it and simultaneously mold the solidified plates from bottom to top as a package, and in which you mold the mold box before pouring the Gypsum paste presses horizontally and releases the pressure after the gypsum has solidified and before the slabs have been molded, which means that the delimiting elements can easily be separated from each other and the molding is made easier, characterized in that the pressure on the mold box is at least 75-80 kPa per hollow mold multiplied by the number of shapes.

The invention is based on the fact that it has been found that when a high pressure is applied to the plasterboard mold, it is possible to prevent the known slight expansion of the material of a plasterboard when the gypsum slurry hardens, and that when the pressure is released after hardening, there is so much play between The plate and the parts of the mold are made so that all plates produced can be easily pushed out of the mold box with a multiple stamp as with the wall plate machine. It was also found that the plates produced according to the invention have improved surface quality and density values. In addition, the most important advantages are a production which is multiplied compared to the previous technology and a decrease in the reject rate towards zero; this is partly due to a new type of gripping device, which is also still to be described.

The molding box, which is still to be described in detail, basically consists of a plurality of delimiting elements arranged side by side. These are not firmly connected, e.g. screwed or welded, but can vary horizontally per plate by small values, e.g. 0.1 to 0.25 mm depending on the panel thickness, move against each other. This length, which is referred to in the following description as the mold gap, is preferably limited so that the risk of gypsum abrasion settling in the gap formed is excluded. It is, of course, advisable to clean the mold box from time to time in order to remove any residues between the molds in the mold gap.

The individual delimiting elements of the hollow molds which form the molding box are preferably held by horizontal tie rods which, with play, connect all delimiting elements with the exception of the lower elements forming the push-out stamp. The limiting elements are then pressed together by exerting pressure on one side or on both sides of the two outer covers of the molding box, in particular by hydraulic means. When the pressure is released after the gypsum slurry of the plates has hardened, the mold gap can then form, a suitable choice or setting of the hydraulic pressure medium ensuring that the hydraulic pressure medium is limited. Then all the plates can be ejected equally well, since the mold gap is not limited individually for each hollow mold, but globally as the sum of all hollow molds in the box, and each plate can "choose" the necessary relief. It is worth remembering disc brakes in automobiles in which the brake pressure relief leads to the brake pads only being retracted by a fraction of a millimeter and the brake disc is nevertheless completely released.

The pressure that must be exerted laterally on the molding box during the hardening of the slabs in order to achieve the success of the invention is determined by the expansion force of the hardening gypsum paste. For example, it corresponds to a force of 981 kN (100 t) for a molding box for the simultaneous production of 25 plates with the dimensions 500 x 1000 x 25 mm, generated by 8 hydraulic cylinders with a hydraulic feed pressure of 400 bar (40 MPa). With this information, the person skilled in the art is able to calculate the forces required for a different number of plates and / or different plate dimensions; if necessary, some simple attempts would have to be made.

An exemplary embodiment of the system according to the invention and the implementation of the method according to the invention will now be explained in more detail by way of example with reference to the following description, which is supplemented by the attached drawing. All features with the exception of those which are expressly designated as not belonging to the invention are important and can form the subject of patent claims.

• Fig. 1 eine Seitenansicht einer Ausführungsform der Anlage,
• Fig. 2 eine Vorderansicht der Anlage nach Fig. 1,
• Fig. 3 eine Seitenansicht der Formmaschine nach Fig 1,
• Fig. 4 eine Vorderansicht der Formmaschine nach Fig. 1, und
• Fig. 5 eine Seitenansicht einer Greifvorrichtung gemäss Erfindung.

In the drawing:

• 1 is a side view of an embodiment of the system,
• 2 is a front view of the system of FIG. 1,
• 3 shows a side view of the molding machine according to FIG. 1,
• Fig. 4 is a front view of the molding machine according to Fig. 1, and
• Fig. 5 is a side view of a gripping device according to the invention.

In the drawing, the same reference numbers mean the same or equivalent elements.

The plate production system according to the invention shown (see Fig. 1 and Fig. 2) consists of the actual molding machine 1 and a number of additional devices, namely the storage containers for gypsum and aggregates such as e.g. Glass fibers, which serve as reinforcing material, the conveying devices, the metering and mixing devices, etc.

The plaster silo 2 is set up to the side of the molding machine 1, from which a pipe conveyor 4 leads to the measuring and metering container 3. This is to be understood with a weighing device 5, which is connected to the weigh feeder 6. This scale is programmable.

The dosing container 4 is arranged above the mixing trough 7 and can be emptied into it. The trough 7 is provided with the agitator 9 and can be tilted about the axis 8 with the aid of the hydraulic drive 10 so that its contents are emptied into the hopper 11 of the molding machine.

The water required to produce the gypsum slurry passes through the pipeline 12 via an annular piston counter 13, which is connected to a control program which is located in the control box 14, and via the controllable metering valve 15 into the trough 7.

In Fig. 1, the gripping and transport device 200 is shown in broken lines as 200A in the position in which it grips the finished plasterboard and as 200B when lowering the plate share 202 onto a transport pallet 201. The device 200 will be described later.

3 and 4, the side and front view of the molding machine according to FIGS. 1 and 2 is drawn out, parts being shown in section.

The machine consists of the molding box 20, which is arranged above the ejection device 21. In the example selected, the molding box 20 contains 25 mold cavities 23 which are delimited on both sides by molding rails 104, 105 and on the underside by ejection stamps 112. The shaped rails 104, 105 and the punch 112 are provided with a profile which corresponds to the crest and the groove of the plate to be produced; these profiles can be seen in particular in FIG. 4.

The front and rear hollow mold are each closed by a strong cover plate 101. The individual hollow molds 23 are also separated from one another by partitions 102, which are flush with the side rails 104, 105.

Four strong steel tie rods 106 are drawn in with slight play through holes in the shaped rails 104, 105 and the partition walls 102. Single-acting hydraulic hollow piston cylinders 134 are pushed onto the ends of the tie rods 106 projecting beyond the molding box and secured with pairs of locknuts 107. The outer bell of the cylinders 134 is supported against the cover plates 101 and the inner piston against the lock nuts 107. These are set in such a way that the required and maximum permissible play is guaranteed. If each hydraulic drive 134 delivers a force of 25 t (approx. 245 kN), the molding box is pressed together with a total force of approx. 980 kN. With an area of 100 x 50 cm, this corresponds to a pressure of 980 kN / 0.5m ² = 1960 kPa, and experience has shown that this pressure is sufficient to achieve an expansion pressure of the plaster of about 75-80 kPa per cavity mold.

The hydraulic connections are not shown. 2, only the hydraulic pump arrangement 115 can be seen.

The hollow molds are open at the top. After filling with gypsum paste, they are covered by grids 114, which are provided on their underside with the corresponding counter profile of the narrow side of the board. So that the grids and the plate edges are not damaged when the mold is relieved of pressure and the plates are ejected, a contact switch 135 is provided which interacts with an actuating pawl 117. Only when the grids 114 are hooked into the pawls 117 and the switch 135 is closed can the pressure relief of the mold and the ejection of the plates be activated.

The whole molding box is suspended between two horizontal beams 116 and is held by them; these beams are fastened to the bottom of a pit via pillars 127 (FIG. 1). The pillars 127 also serve to guide the yoke 132 of the plate ejection device 21.

The stamps 112 are connected to this yoke 132 via the flat stamp crossbars 110. If the yoke 132 is moved upwards, which is done hydraulically, the gypsum boards formed are ejected upwards out of the hollow molds 23. The yoke 132 is raised and lowered by the hydraulic cylinders 122 (see FIG. 2).

Otherwise, all actuation, measurement and control circuits are housed in the control cabinet 14; Facilities are also installed there that allow and effect a fully automatically programmed production process.

5 shows an embodiment of the gripping and transport device 200 according to the invention.

The relatively thick panels produced in machines for the production of wall panels can be handled with grippers which act on the narrow sides of the panels. With relatively thin ceiling panels, this is no longer possible without damaging or breaking the panel.

A new type of gripping and transport device has now been developed, which is tailored to the handling of the thin plates. It consists (Fig. 5) of a horizontally hanging on crane hook 203 beam 204 with side jaws 205, in which end gripper plates 206 are articulated via a lever mechanism that can pivot the end gripper plates 206 with the help of hydraulic drives 207 inwards or outwards. Intermediate plates 208 are also freely suspended on the beam 204. The cable winch for lifting and lowering the crane hooks 203 is designated with 209.

The whole system works as follows, whereby the workflow to be described can also proceed automatically.

The required amount of water is metered into the mixing and casting trough 7 and the reinforcing materials - about 1 kg of glass staple fibers - are introduced. Then the tube conveyor 4 is put into operation, which conveys gypsum from the gypsum silo 2 into the dosing container 3 via the weighing and dosing device 5. When the set amount of gypsum has been supplied, the automatic scale 6 switches off the conveyor, and the measured gypsum is transferred into the trough 7 after the agitator 9 has been started.

If the gypsum paste in the trough 7 is homogeneous, it is pivoted about the axis 8, and the slurry runs through the funnel 11 into the hollow molds 23 of the previously pressurized and compressed molding box 20, which was sprayed with separating oil. After filling, the molding box is covered with the grates 114 which are pressed into the surface of the gypsum paste.

After approx. 8-10 minutes the gypsum has hardened and the still wet, dimensionally stable but sensitive gypsum boards can be removed. The pressure is released from the hydraulic cylinders 134, and the guide rails and partitions of the molding box now give in to the pressure of the compressed plasterboard and move away from each other by a few tenths of a millimeter; the resulting mold gaps add up so that the outer partitions of the mold box can move by 1-2 mm. The piston travel of the cylinders 134 is limited to this value, which results after a few attempts.

For molding, the motors 122 (FIG. 2) are put into operation and lift the yoke 132. The cross members 110 push all the punches 112 in the associated hollow mold upwards, and the plate series generated accordingly rises upwards out of the molding box. It should be added that the releasing of the pressure from the cylinders 134 and the lifting of the yoke 132 can only be started when the grids 114 have been removed from the molding box and hung on the pawls 117.

In the meantime, the gripping device 200 (FIG. 5) has been suitably lowered, approximately as indicated by the broken line in FIG. 1. Depending on their upward movement, the individual plasterboards of the plate pack 202 slide between adjacent intermediate plates 208 of the gripping device. When the punches 112 finally arrive at the molding box, the hydraulic cylinders 207 of the device 200 are supplied with pressure medium, and as a result of the lever movements already described, which immediately result from FIG. 5, a large-area, gentle clamping of all the plates 202 is not achieved on their sensitive narrow sides , but on the top and bottom sides.

The gripping device is moved until the stack is placed in the transport and drying car 201 (which can also be a pallet, see FIG. 1). The carriage 201 arrives in the drying oven not belonging to the invention, which is also not shown. The manufacturing cycle now begins anew with the lowering of the punches 112 to the lower edge of the molding box, with the preparation and compression of the molding box and the application of the gypsum paste as soon as the gripping and transport device 200 has left the molding area.

The system according to the invention, which now delivers about 180 ceiling tiles per hour with 25 hollow molds with a solidification time of the gypsum of 8 minutes, only needs 1 operator, while according to the prior art 6 men are required to produce 120-150 sheets and still do heavy physical work.

In the above description, the invention for the production of ceiling tiles made of plaster has been described and explained. In principle, it can also be used to manufacture wall panels, although less pronounced advantages occur. So the necessary forming force for wall panels is currently approx. 200 t, which can then be reduced to 5-10 t, with corresponding structural and operational savings. This advantage is then offset by the somewhat higher outlay of an element-movable molding box with press cylinders, but overall the advantages predominate, which also include the better plate quality.

Claims (3)

1. An installation for making building panels of plaster by pouring a plaster mixture in a moulding machine having a set of hollow moulds arranged vertically and parallel side-by-side to form by juxtaposition a moulding box in which the hollows moulds are constituted of limitation parts; with devices (107, 134) horizontally pressing the moulding box (20) in order to take up the pression developed by the panels of plaster expanding during hardening and relieving it after hardening of the panels of plaster, characterized in that the moulding box (20) compression devices (107, 134) consist in simple hydraulic hollow pistons (134) acting on both sides of the moulding box, on the one hand on the external panel (101) and on the other hand on traction rods (106) passing through the limitation parts (101, 102, 104, 105), the horizontal displacement of which is limited to 0,1 to 0,25 mm per hollow mould, per building panel respectively, by adjusting the hub of the piston in the hydraulic pressure cylinder (134).

2. The installation according to claim 1, characterized by grates (114) adapted to close the upper part of the moulding box, and by a safety device (117, 135) preventing the pression onto the moulding box (20) from being relieved and the finished plaster plates from being ejected as long as the grates are not remoted out of the moulding box (20).

3. A method for making building flat panels of plaster, in which one pours a mixture of plaster and water into a moulding box comprising a set of hollow moulds placed side-by-side, one let it harden and one ejects at once all the hardened panels from bottom to top; and in which an horizontal pression is applied onto the moulding box before pouring the plaster mixture, this pression is relieved after the plaster is hardened and before the panels are ejected, to allow the limitation parts to slightly move the ones from the others to facilitate the ejection, characterized in that the pression onto the moulding box is at least 75-80 kPa per hollow mould multiplied by the number of moulds.

Images