DE2319176C - Method and device for producing ceramic bodies - Google Patents

Description

is bent at the top, i.e. opposite to the bend, which would result without pre-tensioning during drying, and then the strand of mass is straightened will.

Drying the body takes place. In practice this can Bias z. B. can be generated in that the ceramic After exiting the mouthpiece, the strand of mass is bent upwards in the longitudinal direction, that is, opposite to the bend that would result during drying without pre-tensioning, and then the strand of mass is straightened.

The invention also has an apparatus for performing the method described in various ways Embodiments to the subject. In one embodiment, the mouthpiece is around one Angle arranged inclined to the press head, and there is one between a belt table and the mouthpiece Curved roller conveyor arranged. By then straightening the strand on the Belt table becomes a strand in the lower zone Compression and tensile prestressing in the upper zone, which causes the undesired downward bending counteract when drying. The amount of preload can be adjusted by varying the angle of inclination of the mouthpiece and by varying the curvature of the strand on the roller conveyor can be changed accordingly, so that besides downwardly curved or straight ceramic bodies also upwardly curved ceramic bodies are produced can be. The angle of inclination or the necessary strand curvature required for the greatest possible dimensional stability can easily be determined by a few production searches.

The advantages of the process according to the invention lie in the fact that the shape retention sta ^r k can be improved greatly from ceramic bodies with minimal cost. Thus, with the method 5, ceramic plates with dimensions of about 220 × 380 mm can be produced without any particular difficulty, the longitudinal and transverse bending of which is less than 0.5 mm.

The ones necessary for the application of the procedure

• Devices can also be used in almost all cases can be retrofitted to the existing machines or mouthpieces without difficulty.

In the drawing, exemplary embodiments of the device according to the invention are shown.

> 5 F i g. 1 shows a side view of a device for Carrying out the method according to the invention in one embodiment. A mouthpiece 9 is around one Angle 10 inclined attached to a press head 11. A ceramic strand 12 runs on a curve designed roller conveyor 13 to a belt table 14, on which by straightening the strand in a lower zone 15 of the same a compressive prestress and in an upper zone 16 of the same a tensile prestress is produced.

F i g. 2 again shows in a side view a modified embodiment of a device for Implementation of the method according to the invention. In this embodiment, the roller conveyor 13 is omitted Embodiment according to FIG. 1. The strand 12 arrives

rather, immediately after exiting the mouthpiece 9 on a belt table 14. This is the Strand 12 was given a slight kink 17.

1 sheet of drawings

Claims (5)

Patent claims: 1. A method for producing extruded ceramic body, which is preferably a flat Have contact side on the drying support, with little bending deformation during drying, characterized in that the mass strand one of the bending deformations at the mouthpiece outlet and / or after leaving the mouthpiece during drying, counteracting bias is applied before the drying of the body takes place. 2. The method according to claim 1, characterized in that the mass strand one of the bending deformation atipi drying is given opposite deformation and then the mass strand is straightened. 3. Device for performing the method according to claim 1 or 2, characterized in that shrinks, the already solidified upper side cannot be compressed more so that the underside is excessively shortened. The consequence of this is that the Ceramic body bends downwards at the edges when it dries out and arches up in the middle. This deformation is particularly strong in the case of flatter, plate-like bodies, since here the slowly drying one Bottom is relatively large. With more cubic bodies, the deformation is slight. Mix in one Moldings occur, as often both material softening and uneven firing shrinkage provide the prerequisites for this. In order to ensure the best possible dimensional stability, two or more bodies of the desired shape with predetermined breaking points combined to form a more cubic body and pressed in one piece in the strand and after . that the mouthpiece (9) inclined at an angle (10) to dry or burn in the individual desired to the press head (11) is arranged and that between ^{20 Kor} P ^{he zerIeT} '^ ^Mo ^ ^chs ' *? ^te symmetry of the composite ¹ ^ ^v ' ⁶ .... mixed cross-section favors the shape retention a belt table (14) and the mouthpiece (9) a curved roller conveyor (13) is arranged is. 4. Device for performing the method according to claim 1 or 2, characterized in that that a belt table (14) is arranged immediately following the inclined mouthpiece (9). The invention relates to a method for The ability to dry and burn in addition. This method is z. B. applied in manufacturing of split tiles, in which intermediate webs are separated out as waste, or of brick shells for lintels. The disadvantages of this method are that of dividing the assembled body another operation is required and that many cross-sections are not available for assembly suitable for larger cross-sections. Further methods of improving the dimensional stability during manufacture consist in the support surfaces of the blank on the frame approximately linear or punctiform or during the G
Manufacture of extruded ceramic bodies that change the drying process so that the flow around them preferably a flat contact side on the dry surface with little bending deformation during drying. Known methods of this type are the re-pressing of dried, extruded moldings on punch presses or the so-called dry pressing with reduced moisture content on extrusion. In both processes, the cause of the lack of dimensional stability, namely the shrinkage of the ceramic Drying out of the blank underside is improved. What all processes have in common is the still inadequate shape retention and the sometimes extremely high effort required to improve them. How significant the difficulties are to ensure good dimensional stability in the manufacture of ceramic bodies is clear from DIN 456, "Roof tiles", according to which z. B. the winged blanks during drying, thereby partly lack of beaver tails (size 155x375mm), that the material moisture during pressing is 6 mm and the wingedness of hollow sockets is kept very low. The thickest dry (size 235 χ 400 mm) may even be 12 mm,
shrinkage of around 6 to 10% is namely at high levels of »consulting room for ceramic - glass - enamel«, Mixing water content available, which is usually p. 252 to 254, from 20.5. 1957 and pp. 280 to 283, from 5.6. 1957, it is known to drop the strand before it influence from the mouthpiece. Such measures only allow to eliminate the errors, which arise during the pressing itself, and thus to obtain a symmetrically running strand. The invention is based on the object of maintaining the shape, in particular winginess, longitudinal bending and Transverse bending of extruded ceramic bodies without great manufacturing effort to improve significantly that the drying is between 15 to 25%. If the mixing water content is lower, the shrinkage is often only a fraction of it. The disadvantages of the re-pressing process are in particular the additionally necessary pressing process on punch presses, the disadvantages of dry pressing are the high power consumption and machine wear and the still poor shape retention.
In the usual process, the pressed, plastic blank is placed on frames, frames, conveyor belts, Rolls or the like, placed on which it is compensated for errors caused by the dryer,
rci is brought. According to the invention, this object is achieved by the fact that the surface = lower surface of the blank is not as good as that the mass strand at the mouthpiece outlet and / or can flow around as the other surfaces, especially after leaving the mouthpiece one of the bending verfordie surface, the top of the dries Pre-tensioning, which counteracts the drying process, begins to dwindle and becomes leather-hard, 65 before the body is dried. In practice, while the still plastic underside is this preload can e.g. B. is thereby astonished and shortened. If in the further course it is shown that the ceramic mass strand after the drying process then also the underside after the exit from the mouthpiece in the longitudinal direction