CERAMIC SANITARY ARTICLE AND METHOD FOR PRODUCING SAME

Abstract

A method for producing a ceramic sanitary article, more particularly a washbasin or washstand, wherein a mold is used to produce, from a ceramic composition, a green body, which is subsequently fired in a firing to form a fired body, where the fired body after the firing is subjected to material-removing working on one or more visible faces until it has a desired dimension, after which the worked body is glazed at least on the worked visible face or faces and is fired a further time in order to fire the glaze.

Claims

1. A method for producing a ceramic sanitary article, more particularly a washbasin or washstand, wherein a mold is used to produce, from a ceramic composition, a green body, which is subsequently fired in a firing to form a fired body, wherein the fired body after the firing is subjected to material-removing working on one or more visible faces until it has a desired dimension, after which the worked body is glazed at least on the worked visible face or faces and is fired a further time in order to fire the glaze.

2. The method according to claim 1, wherein the firing temperature in the second firing is lower than the firing temperature in the first firing.

3. The method according to claim 2, wherein the firing temperature in the second firing is lower by 10-100 C., more particularly by 15-60 C., preferably by 20-40 C.

4. The method according to claim 1, wherein the firing temperature in the first firing is 1200-1300 C., more particularly 1240-1290 C.

5. The method according to claim 1, wherein a holding time during the second firing is shorter than a holding time during the first firing.

6. The method according to claim 5, wherein the holding time in the second firing is shorter by 90-110 min, more particularly by 100 min.

7. The method according to claim 1, wherein the holding time in the first firing is 240-360 min, more particularly 250-350 min.

8. The method according to claim 1, wherein the material-removing working takes place by milling or grinding.

9. The method according to claim 1, wherein the material-removing working takes place in such a way that edges on the sanitary article after the second firing have a radius 2 mm, more particularly 1 mm.

10. The method according to claim 1, wherein before the first firing, at least locally, a glaze is applied to the body and is fired in the first firing.

11. The method according to claim 10, wherein the glaze is also applied to the one or more visible faces intended for subsequent working, where it is removed in the course of the working, and the visible face(s) are subsequently reglazed.

12. A ceramic sanitary article produced by the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0021] In the drawing:

[0022] FIG. 1 shows a schematic representation to illustrate the method of the invention,

[0023] FIG. 2 shows a partial view of a sanitary article of the invention after the first firing and after implementation of the mechanical working, and

[0024] FIG. 3 shows a sectional view through the sanitary article of the invention from FIG. 2, in the edge region.

DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 1 shows the process of the method of the invention, in the form of a flow diagram.

[0026] First of all in step a), a castable ceramic composition 1 is prepared, which thensee step b)is introduced into a plaster or pressure casting mold 2, where it remains for a certain time to form a green ceramic body which, after removal from the mold 2, is dried for a defined first time t.sub.1 at a defined temperature T.sub.1, so thatsee step c)a dried green body 3 is formed, here by way of example in the form of a washstand or washbasin 4.

[0027] At this point, there are two variant methods, represented using the arrows I and II. According to variant I, the green body 3 can be covered with a glaze composition 5, using a suitable spraying facility 6 in order to apply the glaze composition 5 to one or more of the visible faces 8 of the green body 3. This is shown in step d). Following application of this glaze, the glaze-coated green body 3see step e)is introduced into a firing oven 9 in order for it and the spray-applied glaze composition 5 to be fired.

[0028] According to variant II, after the drying of the green body 3, for the formation of a fired body 7, the merely dried but not glaze-coated is introduced directly into the firing oven 9 in step c), meaning that in this case the unglazed green body 3 is fired in step e).

[0029] The green body 3, whether unglazed or (partly) glazed, is fired in the firing oven 9 for a predetermined time t.sub.2 at a predetermined firing temperature T.sub.2, with the time t.sub.2, the so-called holding time, being between 240-360 min, more particularly between 250-350 min. The firing temperature during this first firing is between 1200-1300 C., more particularly between 1240-1290 C.

[0030] Following implementation of the firing operation, the fired body 7 is withdrawn from the firing oven 9 and cooled, this being shown in step f). After the firing, the body 7 has altered dimensions in comparison to the merely dried green body according to step c), owing to shrinkage and deformation events concluded in the course of the firing. After the first firing, by way of example, the body 7 has a length x.sub.1, a width y.sub.1, and a height z.sub.1. Here, as described, the visible faces 8 may be either unglazed or glazed, depending on whether variant I or II has been implemented.

[0031] In the next step, g), the fired body 7 is subjected to material-removing working by means of a tool 10, preferably a miller 11, which can be moved in space via a multi-axis robot, more particularly a 5-axis robot, in the region of one or more or all visible sides 8, which are therefore viewable by the user in the installed position; this working takes place until the body has a predetermined target dimension in the respective desired direction. After this material-removing working, by way of example, the body 7 has a length x.sub.2, a width y.sub.2, and a height z.sub.2, the surfaces here being assumed to have been worked in each dimension. In other words, x.sub.2<x.sub.1, y.sub.2<y.sub.1, and z.sub.2<z.sub.1. It is, however, not necessary for each dimension to be worked; instead, it is also possible for only some of the dimensions to be worked, according to the direction in which a high-precision dimensional integrity is desired. Through the working of the visible faces 8, in the course of which, if a glaze has already been applied, this glaze as well has been removed at least on parts of the visible faces 8, where, indeed, the material working takes place, therefore the fired body 7 is worked in such a way that it has the desired final target dimensions.

[0032] In the next step, h), the worked body 7, optionally again, is glazed on either all the visible faces 8 or, if an initial glaze has already taken place, on the visible faces 8 worked in step g), this glazing meaning that a glaze composition 5 is (re-)applied by spraying using a spraying tool 6. The body 7 glaze-coated accordingly is then introduced again into the or a firing oven 9 (step i)), where it is fired a second time. This is done at a firing temperature T.sub.3 which is somewhat lower than the firing temperature T.sub.2 during the first firing. The firing temperature T.sub.3 ought to be lower by around 10-100, more particularly by 15-60 C., and preferably by 20-40.

[0033] The holding time ta as well, being the duration for which the second firing takes place, is shorter than the holding time t.sub.2 in the first firing. The holding time t.sub.3 ought to be shorter by 90-110 min, more particularly by around 100 min, than the holding time t.sub.2.

[0034] The reduction in the firing temperature T.sub.3 is of advantage insofar as it results in definitive avoidance of the slightest shrinkage events and hence deformation events during this second firingthese events, as described, are already concluded within the first firing. The reduced firing temperature in the second firing avoids even only minimal alterations in the target dimensions x.sub.2, y.sub.2, and z.sub.2 produced by mechanical working, apart from the minimal increase as a result of the glaze layer, which is very thin and usually less than 1 mm thick. The reduced holding time is set because the only task in this second firing is to fire the thin glaze layer, which is rapidly accomplished.

[0035] Following implementation of the second firing, the ceramic sanitary article 12, which is then fully fired and glazed, is withdrawn from the firing oven 9, as shown in step j). Since no further deformations have occurred during the second firing, this article continues to have the target dimensions x.sub.2, y.sub.2, and z.sub.2 produced by the mechanical working in step g), with these dimensions having not undergone significant changeonly through the applied glaze layer, which, as described, has a thickness of less than 1 mm. This means that the completed sanitary article 12 has exactly the desired target dimensions and, accordingly, does not suffer from tolerance, and can be manufactured reproducibly with exactly these dimensions, hence any desired number of sanitary articles 12 can be produced with the same target dimensions.

[0036] FIG. 2 shows a partial view of the body 7, already fired once, after implementation of the material-removing working according to step g). It may be assumed that the visible faces 8 which converge in the region of the left-hand front edge 13 have been worked. It may further be assumed that the edge 13 and, respectively, the adjacent, right-hand and left-hand visible faces 8 are at an angle of 90 to one another; in this regard, see also the sectional view according to FIG. 3. As shown in FIG. 2, the glaze composition 5 is applied via the spraying facility 6 to the milled visible faces 8, and then fired in the second firing (step i)).

[0037] FIG. 3 shows a sectional view through the fully fired ceramic sanitary article 12. Shown again is the still sharp edge 13 at the convergence of the two visible faces 8, which still approach one another exactly at the angle =90. Additionally shown is the fired glaze layer 14, which is extremely thin and has a thickness of typically less than 1 mm, but which is shown here somewhat thicker for reasons of illustration. In any case, only a minimum radius 15 of the glaze layer 14 is formed at the edge 13, meaning that at this edge of the fired sanitary article 12, a curvature with a minimum radius is obtained, this curvature being ultimately dependent in its radius only on the layer thickness of the glaze coating 14. By virtue of the mechanical working of the bordering visible faces 8, the formation of the edge or the edge radius is no longer material-dependent, since with existing customary production methods, in order to avoid cracking, the only edges it has been possible to form are not sharp edges but rather edges with a radius of several millimeters.

[0038] Such an edge may be provided at any desired position on the sanitary articlefor example, at the convergence of two side faces, or in the region of a top-face recess for accommodating one or more fittings or a soap tray, etc.anywhere, that is, where two (planar) faces approaching at an angle converge with one another. In addition to very small radii and/or sharp edges, it is of course possible, with the appropriate milling tool or profile miller, to also generate curvatures with larger radii, in the centimeter range, for example, which then undergo only insubstantial enlargement with the glaze.

[0039] As well as the production of a sanitary article having extremely high dimensional integrity in a desired spatial direction, therefore, the method of the invention also enables, furthermore, the formation of any desired edges or convergences with a varying radius; in other words, it is possible to form high-precision curvatures by corresponding mechanical working of the face convergences, and also to form edges with a smaller radius, down to edges with a minimum radius of 1 mm or less.

[0040] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.