DE102022100633A1 - Method of glazing a ceramic article - Google Patents

Abstract

The invention relates to a method for glazing a ceramic article, in particular hollowware (1) with a perforated base edge (2). The invention also relates to a device (4) for carrying out the method. In order to enable ceramic articles, in particular hollowware with perforated base edges, to be glazed with little effort and high quality, a method with the following steps is proposed:- Glazing a first Part (5) of the ceramic article (1) with a first glaze (6) by means of flood glazing, - subsequent cleaning of the ceramic article (1) by removing the superfluous parts of the applied first glaze (6) in such a way that a defined boundary line (19) of the first glaze (6) is formed, and- subsequent glazing of a second part (27) of the ceramic article (1) with a second glaze (24) by means of dip glazing, wherein during the dip glazing the second glaze (24) extends up to the boundary line (19 ) of the first glaze (6) is applied.

Description

The invention relates to a method for glazing a ceramic article, in particular hollowware with a perforated base edge. In addition, the invention relates to a device for carrying out the method.

Ceramic articles can have a mouth rim and a foot rim, especially when it comes to hollow goods. These foot edges can be designed as perforated foot edges. The openings in the edge of the foot are also referred to as water grooves, and a foot interrupted by such water grooves is also referred to as a wash foot. Examples of ceramic articles that may have feet with water grooves are cups, mugs, and other ceramic drinking vessels.

The glazing of articles with washing feet on the inside and outside has so far been carried out predominantly using the technique of spray glazing or spray glazing, as this is a comparatively simple and reliable technique, especially against the background that for the immersion of the article in the glaze at Using the alternative immersion glazing technique always requires holding the article by the base edge and an additional, subsequent glazing step for glazing the base edge, which can lead to quality problems due to the often different glazing results.

Spray or spray glazing routinely wastes a large amount of glaze because it is not applied to the article. The overspray has to be collected and recycled at great expense.

One object of the present invention is to enable ceramic articles, in particular hollowware with perforated base edges, to be glazed with little effort and of particularly high quality.

This object is achieved by a method according to claim 1 or by a device according to claim 10. Advantageous embodiments of the invention are specified in the dependent claims. The advantages and configurations explained below in connection with the method also apply analogously to the device according to the invention and vice versa.

The method according to the invention for the preferably fully automated glazing of a ceramic article, in particular a hollowware with a perforated foot edge, has the following steps: glazing of a first part of the ceramic article with a first glaze by means of flow glazing, subsequent cleaning of the ceramic article by removing the superfluous parts of the applied first glaze such that a defined boundary line of the first glaze is formed, and then glazing a second part of the ceramic article with a second glaze by means of dip glazing, during which dip glazing the second glaze is applied exactly up to the boundary line of the first glaze. In this way, after the glazing is complete, the boundary line of the flow glazing forms the dividing line of the two glazes.

With the method according to the invention for glazing ceramic articles with perforated feet, the use of spray glazing can be dispensed with. Instead, the techniques of flow and dip glazing can be used. The process is therefore not only simpler, but also more cost-effective. The disadvantages of spray and spray glazing, in particular the problem of overspray, are avoided. At the same time, a very high glazing quality is achieved. In particular, a very precise dividing line and a particularly smooth transition between the glazes can be formed.

According to one embodiment of the invention, the second part of the ceramic article is a part of the article which is not provided with the first glaze. In other words, the second part of the ceramic article is a different part than the first part of the ceramic article, i. H. the second part can be completely different from the first part.

According to one embodiment of the invention, the second part of the ceramic article, or a portion of this second part, is a part of the article which (since it has already been cleaned) is no longer provided with the first glaze. In other words, the glazed parts or parts to be glazed of the ceramic article can also overlap, i. H. the second part or a portion of the second part of the ceramic article may be the first part or a portion of the first part of the ceramic article or vice versa.

According to one embodiment of the invention, the second part of the ceramic article, apart from the first part of the article, is the entire remaining part of the article, so that together with the first part the entire ceramic article is glazed. Alternatively, the first part and second part may together form only part of the ceramic article, with the remainder of the article not formed by the first or second part having been or will be glazed in the same or a different manner, or not is glazed.

According to one embodiment of the invention, the first part of the ceramic article is at least an inside of a hollow article and the second part is at least a part of an outside of this hollow article. According to one embodiment of the invention, the first part of the ceramic article is glazed with a first glaze and the second part of the ceramic article is glazed with a second glaze different from the first glaze. According to one embodiment of the invention, the second glaze has a different color than the first glaze. In this way, the invention can also be used to apply a two- or multi-color glaze, as is often desired for hollowware.

According to one embodiment of the invention, the ceramic article is cleaned in such a way that the boundary line is formed in the region of the mouth rim of the ceramic article. This meets the desire to glaze the inside with one color and the outside with the other color in two-tone glazes, so that the color dividing line between the inside and outside of the article resulting from the dip glazing is in the area of the mouth rim.

According to one embodiment of the invention, the ceramic article is held during flow glazing by a first article holder operating according to a first functional principle and during immersion glazing by a second article holder preferably operating according to a second functional principle different from the first holding principle. In this way, optimized holding methods can be used for the respective process step. This is particularly advantageous when the article is hollow goods with a perforated foot edge, since an article holder can then be used whose holding principle is adapted to a perforated foot edge.

According to one embodiment of the invention, the ceramic article is held by the first article holder during cleaning. In this way, a transfer device between the surge station and the cleaning station can be dispensed with.

According to one embodiment of the invention, the ceramic article is immersed during immersion glazing in a glaze basin arranged in a storage basin, the second glaze being transported from the storage basin into the glaze basin and flowing out of the glaze basin over the edge thereof back into the storage basin. This creates a very smooth glaze mirror into which the ceramic item is immersed.

It is common practice for the glaze to be constantly in circulation in the dipping tank, otherwise the glaze will sediment. According to one embodiment of the invention, this method is deviated from and the transport of the second glaze from the storage basin to the glaze basin is interrupted from time to time. Such an interruption advantageously takes place during the immersion of the ceramic article in the glaze basin or in a defined temporal connection with this immersion. In this way, a particularly calmed glaze is created with a very smooth glaze surface, which is unusual for dipping glazes, since so far dipping glazing has not been done with calmed glazes, but instead the glaze has always been turned over. Sedimentation does not take place despite the interruption in the transport of the glaze, since the interruption only lasts for a short period of time.

According to one embodiment of the invention, before the ceramic article is dipped into the glaze basin, preferably immediately before dipping, a blowing device is used to generate an air stream guided over the glaze surface. This air flow is preferably in the form of a blast of air and is directed in such a way that it flows directly over the glaze mirror. It is used to remove any foam from the glaze surface, the so-called haze, before the article is immersed in the glaze. Removing this veil prevents it from accumulating on the article, which would lead to undesirable glaze defects on the article after firing.

With the invention, it is possible to mechanically and automatically provide ceramic articles, in particular hollowware, such as mugs or cups, with different glazes, especially differently colored glazes, on the inside and outside. It is not only possible with the invention that these ceramic articles can have perforated foot edges. Particularly precise boundary lines of the glazes or particularly precise dividing lines between the glazes can also be implemented. If different colored glazes are used, an extraordinarily sharp color separation can be achieved with the method according to the invention. At the same time, a very even transition of the glazes can be created in the area of the dividing line, which is particularly advantageous for cups. If the dividing line between the two glazes is in the area of the mouth rim of the cup, as is usually desired, a particularly smooth mouth rim can be achieved with the method according to the invention. This is therefore from of particular importance because irregularities on the surface of the rim of the cup can be perceived particularly well by the very sensitive lips.

The method according to the invention is particularly suitable for the fully automated glazing of ceramic articles. However, the method according to the invention is also suitable for the semi-automated glazing of ceramic articles, in which the individual steps of the actual glazing process or the feeding or removal of the ceramic articles to the glazing machine are carried out by hand.

The device according to the invention, also referred to here as a glazing machine, comprises at least one device for flow glazing of ceramic articles, at least one device for subsequent cleaning of the ceramic articles and at least one device for subsequent immersion glazing of the ceramic articles, the said devices for carrying out the corresponding process steps of the inventive Process are formed. The glazing machine may further comprise devices for feeding and discharging the ceramic articles (feeding devices, discharging devices) and/or devices for transferring the ceramic articles from one station of the glazing machine to another station of the glazing machine (transfer devices).

• 1 eine schematische Darstellung des Innenglasierens des keramischen Artikels,
• 2 eine schematische Darstellung des Schwammens des keramischen Artikels,
• 3 eine schematische Darstellung des Außenglasierens des keramischen Artikels,
• 4 eine schematische Darstellung des unglasierten keramischen Artikels,
• 5 eine schematische Darstellung des schwallglasierten keramischen Artikels,
• 6 eine schematische Darstellung des gereinigten keramischen Artikels,
• 7 eine schematische Darstellung des tauchglasierten keramischen Artikels.

An embodiment of the invention is explained in more detail below with reference to the drawings. Here show:

• 1 a schematic representation of the interior glazing of the ceramic article,
• 2 a schematic representation of the sponging of the ceramic article,
• 3 a schematic representation of the external glazing of the ceramic article,
• 4 a schematic representation of the unglazed ceramic article,
• 5 a schematic representation of the flow-glazed ceramic article,
• 6 a schematic representation of the cleaned ceramic article,
• 7 a schematic representation of the dip-glazed ceramic article.

None of the figures show the invention to scale, but only schematically and only with its essential components. The same reference symbols correspond to elements with the same or comparable function.

The ceramic article to be glazed is a hollow product 1, namely a cup. The foot edge 2 of the hollowware 1 is perforated and has a water groove 3 ( 4 ) . The glazing of the hollowware 1 is fully automated using a glazing machine 4.

After the hollow goods 1 have been fed to the glazing machine 4 by means of a suitable feed device (not shown), for example a feed device for clocked feed, a first part 5 of the hollow goods 1 is first glazed with a first glaze 6 in a first color by means of flow glazing. A device 7 designed as part of the glazing machine 4 for flow glazing serves for this purpose. The first part 5 of the hollow goods 1 is essentially the inside 8 of the hollow goods 1 ( 5 ). The first glaze 6 is therefore the inner glaze.

For gushing, the hollow goods 1 are grasped at their foot edge 2 by a first article holder 9 and are moved with their mouth edge 11 oriented downwards towards a gush nozzle 12 of the gush glazing device 7, from which the first glaze 6 exits in the manner of a fountain ( 1 ) . The first article holder 9 is a vacuum suction cup arranged on a support arm 13 of the glazing machine 4 . The first article holder 9 acts on the foot edge 2 of the hollow article 1 and sucks it in with negative pressure. In this way, the hollow goods 1 are held at the foot edge 2 . The hollow goods 1 can then be moved into the desired position above the surge nozzle 12 and back by rotating (see double arrow 14) and/or linearly moving (see double arrow 15) the support arm 13. The first article holder 9 is designed to hold a perforated foot rim 2 . As an alternative to a vacuum suction cup, another suitable article holder can also be attached to the support arm 13 .

In addition, during flow glazing, the mouth edge 11 and a section 16 of the outside 17 of the hollow goods 1 are provided with the first glaze 6 by immersing the mouth edge 11 of the hollow goods 1 in a glaze container 18, with which the first glaze exiting the flow nozzle 12 6 is caught.

The hollowware 1 is immersed into the glaze container 18 at least to such an extent that it is ensured that the mouth rim 11 is completely provided with the first glaze 6 on the inside and outside ( 5 ).

If the pump (not shown) used for the flow glazing is operated in a non-pulsating mode, so that a smooth Emergence of glaze 6 from the surge nozzle 12 occurs, a very regular glaze thickness can be achieved.

Following the application of this flood glaze, the hollowware 1 is cleaned by removing the superfluous parts of the applied first glaze 6 in such a way that a defined, sharp boundary line 19 of the first glaze 6 is formed ( 6 ). A device 21 designed as part of the glazing machine 4 for cleaning ( 2 ).

The cleaning takes place, for example, by sponges on the edge of the mouth 11 . The surface of the hollow goods 1 is cleaned by the hollow goods 1 being moved against a rotating cleaning sponge 22 of the cleaning device 21 . A dry or a wet sponge 22 can be used for this. If the cleaning device 21 is arranged adjacent to the flood glazing device 7, the hollow goods 1 can be pressed against the cleaning sponge 22 with the aid of the same article holder 9 immediately after the flood glazing. A transfer device between these two stations is then not required. Alternatively, the sponge 22 can be moved against the hollow goods 1.

However, the superfluous glaze 6 can also be removed in other ways. For example, the glaze 6 can be scraped off with a cleaning knife from a correspondingly equipped alternative cleaning device (not shown).

A sharp boundary line 19 of the first glaze 6 is achieved by this cleaning ( 6 ). The cleaning process can be adjusted so that this boundary line 19 runs exactly where on the hollow goods 1 where it is desired. In other words, the position of the boundary line 19 is freely adjustable. The arrangement of the cleaning knife and the position and shape of the cleaning sponge 22 can be adjusted accordingly. In the example described here, the boundary line 19 runs directly in the area of the mouth edge 11 of the hollow article 1.

After cleaning, the inner side 8 of the hollow ware 1 and the mouth rim 11 are completely provided with the first glaze 6 up to the sharp boundary line 19, while the outer side 17 of the hollow ware 1 is unglazed up to this boundary line 19 ( 6 ). On the one hand, this prevents the inner glaze 6 located on the outside 17 of the hollow ware 1 in the area of the mouth edge 11 after the flow glazing from mixing with the outer glaze 24 when the hollow ware 1 is immersed in the outer glaze bath 23 . On the other hand, the wiping defines a particularly sharp boundary line 19, as is required so that after glazing the outside 17 of the hollowware 1 with the second glaze 24, there is a precise parting line 25 between the glazes 6, 24, as described below.

After the inner glaze 6 has been cleaned from the flood glazing, the hollowware 1 is either transferred directly to a device 26 for immersion glazing with the aid of a transfer device (not shown) or the hollowware 1 is stored or subjected to a further intermediate step, e.g. B. a drying step. Also, the hollowware 1 does not have to be cleaned immediately after flood glazing. The glaze 6 can also be removed after a waiting period. The hollow goods 1 can therefore also be temporarily stored and/or transported after the flow glazing, for example.

After the cleaning step, a second part 27 of the hollowware 1 is glazed with a second glaze 24 in a second color that differs from the first color by means of immersion glazing. A device 26 designed as part of the glazing machine 4 for immersion glazing serves for this purpose. This second part 27 of the hollow goods 1 is essentially the outside 17 of the hollow goods 1. The second glaze 24 is therefore the outer glaze. A section 28 of this second part 17 of the hollowware 1 is a part of the section 16 of the first part 5 of the hollowware 1 that is no longer provided with the first glaze 6 because it has already been cleaned, namely that part on the outside 17 of the hollowware 1, which was provided with the first glaze 6 during flow glazing during immersion in the glaze container 18 ( 6 ). The remaining part of the second part 27 of the hollowware 1 was unglazed until then.

For dip glazing the outside 17 of the hollow article 1, including the base of the cup, the hollow article 1 is held by a suitable second article holder 29. This article holder 29 is designed in such a way that it acts exclusively on the inside 8 of the hollow article 1 . For example, a stamp (not shown) that is inserted in a sealing manner into the hollow goods 1 and that fixes the hollow goods 1 to the article holder 29 with the formation of a negative pressure is suitable for this purpose. Alternatively, the inside 8 of the hollow goods 1 can also be held with a vacuum-free gripper (not shown).

The second article holder 29 is also attached to a support arm 31, which can move the hollow goods 1 into the desired dipping position and back by rotating and/or linear displacement. For high-precision positioning of the hollow goods 1 in the dipping tank cken 23 are used to drive the support arm 31, preferably servomotors 32.

The hollowware 1 held in this way on its inner side 8 is immersed into the outer glaze bath 23 with its base edge 2 oriented downward for the purpose of immersion glazing and covered with the outer glaze 24 . The second glaze 24 is applied exactly up to the boundary line 19 of the first glaze 6, so that after the end of the immersion glazing, the boundary line 19 of the flood glazing forms the dividing line 25 of the two glazes 6, 24. In other words, the two glazes 6, 24 each end at the dividing line 25, without the glazes 6, 24 overlapping or leaving a defect. A very precise transition between the glazes 6, 24 is thus achieved.

The dip tank 23, into which the hollowware 1 is immersed during the dip glazing, is designed as an inner tank which is arranged in an outer storage tank 33, the second glaze 24 being pumped from the storage tank 33 into the dip tank 23 from below and out of the dip tank 23 over the edge 34 flows back into the reservoir 33 on all sides.

The pumping of the second glaze 24 into the dipping basin 23 is interrupted immediately before each immersion of a hollow product 1 for the duration of the dipping process, so that the second glaze 24 is not circulated during the dipping glazing and the glaze 24 also no longer overflows into the storage basin 33 . Immediately before the hollowware 1 is immersed, there is an overfull immersion basin 23 in which, due to the surface tension, the second glaze 24 forms a glaze mound (not shown) that protrudes beyond the basin edge 34 and has a very flat surface, which serves as a glaze mirror 35. The pump for pumping the outer glaze 24 is in 3 For reasons of simplification, they are not shown, nor are the transport lines for the inner glaze 6 in 1 .

Immediately before the hollowware 1 is dipped into this glaze mirror 35, an air nozzle 36 attached to the dipping basin 23 generates an air stream that flows over the glaze mirror 35 and blows the silicate foam (not shown) away from the glaze surface.

After applying the dipping glaze, the hollowware 1 is completely glazed. The hollow goods 1 are then dried and can be transferred to a suitable discharge device (not shown) with the aid of a transfer device (not shown), by means of which the hollow goods 1 are guided away from the glazing machine 4 .

All of the features presented in the description, the following claims and the drawings can be essential to the invention both individually and in any combination with one another.

Each of these features or combinations of features can form the basis of an independent invention, the right to which is expressly reserved.

When specifying a combination of features that defines an invention, individual features from the description of an exemplary embodiment do not necessarily have to be combined with one or more or all other features specified in the description of this exemplary embodiment; in this regard, each sub-combination of features of one or more exemplary embodiments is also expressly disclosed.

In addition, physical features of the device can be reworded as method features and method features can be reworded and used as physical features of the device. Features reformulated in this way are automatically disclosed as well.

Reference List

1

ceramic article, hollow ware, cup

2

foot edge

3

water groove

4

glazing machine

5

first part of hollowware

6

first glaze, inner glaze

7

Equipment for flood glazing

8th

inside of the hollowware

9

first article holder, vacuum suction

10

(free)

11

edge of mouth

12

surge nozzle

13

Beam

14

linear travel direction

15

direction of rotation

16

outside section

17

outside of the hollowware

18

glaze container

19

boundary line

20

(free)

21

facility for cleaning

22

cleaning sponge

23

Plunge pool, outdoor glaze bath

24

second glaze, outer glaze

25

parting line

26

Device for immersion glazing

27

second part of hollowware

28

Part cleaned from the first glaze

29

second article holder

30

(free)

31

Beam

32

servo motor

33

reservoir

34

plunge pool edge

35

glaze mirror

36

air nozzle

Claims (8)

Process for the preferably fully automated glazing of a ceramic article, in particular hollowware (1) with a perforated foot edge (2), with the steps - Glazing a first part (5) of the ceramic article (1) with a first glaze (6) by means of flow glazing, - subsequently cleaning the ceramic article (1) by removing the superfluous parts of the applied first glaze (6) in such a way that a defined boundary line (19) of the first glaze (6) arises, and - subsequently glazing a second part (27) of the ceramic article (1) with a second glaze (24) by means of immersion glazing, during which immersion glazing the second glaze (24) is applied up to the boundary line (19) of the first glaze (6). . procedure after claim 1 , wherein the first part (5) of the ceramic article (1) is at least an inside (8) of a hollow article (1) and the second part (27) is at least part of an outside (17) of this hollow article (1 ) acts. procedure after claim 1 or 2 , wherein the first glaze (6) has a different color than the second glaze (24). Procedure according to one of Claims 1 until 3 , wherein the cleaning of the ceramic article (1) takes place in such a way that the boundary line (19) is formed in the area of the mouth rim (11) of the ceramic article (1). Procedure according to one of Claims 1 until 4 , wherein the ceramic article (1) is immersed during immersion glazing in an immersion basin (23) which is arranged in a storage basin (33), the second glaze (24) being transported from the storage basin (33) into the immersion basin (23). is and flows from the dip tank (23) over the edge (34) back into the storage tank (33). procedure after claim 5 , wherein the transport of the second glaze (24) from the storage tank (33) into the dip tank (23) is interrupted from time to time. procedure after claim 5 or 6 , wherein before the ceramic article (1) is immersed in the immersion basin (23) with the aid of a blowing device (36) an air flow guided over the glaze mirror (35) is generated. Device (4), characterized in that it is used to carry out the method according to one of Claims 1 until 7 is trained.

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