GB2109297A - Producing ceramic parts - Google Patents

Abstract

Apparatus for producing parts of porcelain articles, in particular reliefs for jasper porcelain, is described in which porcelain pieces are cut from a pugged roll of porcelain (2) by a cutter (4) and are then individually transported by a thin film (8) in between film (8) and film (10) and are positioned above an engraved matrix (16) in which the required relief pattern has been engraved in negative. A die (20) presses the porcelain piece down so that it fills out all the pattern components in the matrix. At the same time, any surplus porcelain is cut off between the die (20) and the edge around the matrix engraving without damaging the films (8, 10). The stamped relief adheres to the upper film (10) and is then transported from the upper film (10) via a conveyor belt (25) for further processing while the surplus waste porcelain is transported by the film (8) to a further conveyor belt (24). <IMAGE>

Description

SPECIFICATION Procedure and device for producing ceramic parts The present invention consists of a mechanical procedure for producing ceramic parts, in particular reliefs which are then applied to the basic articles when manufacturing jasper porcelain. A device, in which the reliefs are moulded, has been invented for carrying out this procedure.

Jasper ware or jasper porcelain is the name given to porcelain consisting of a basic porcelain article to which reliefs, made of a porcelain with a colour different to that of the basic article, are applied and fired to the basic article which they decorate. The production of jasper porcelain has traditions going back to antique times but the technique was mainly developed during the 1860s and 1870s by an English porcelain company which developed the technique to a level of industrial production of high artistic class. Vases, for example, were made of porcelain body which was coloured all the way through with rich pastel colours and provided with relief figurines of bright white porcelain. The reverse procedure, i.e.

with a white basic porcelain and reliefs made of through-coloured body, has also been used.

The reliefs, which were about a centimetre wide for tableware and up to a decimetre for ornamental goods, have been produced manually upto now either by casting or by impact moulding. The body, from which the reliefs have been made, has been produced in a conventional manner. In the case of coloured reliefs, the base porcelain body, has, however, been compensated for the change in shrinkage between body and relief which occurs during the drying and firing of the goods and which is caused by the colouring agent. Conversely, in the case of white/uncoloured reliefs, the porcelain body used for the relief is adjusted for the change in shrinkage between body and relief in the coloured base goods.The porcelain body used for the relief has a plastic consistency and a moisture content in the 20-30% range and has generally been extruded by means of a vacuum mill through a template to form a string of the required dimensions. Bats of a thickness selected to suit the depth of the relief which is to be produced are then cut from the string thus obtained.

These bats are placed one at a time on an electrically heated plate fastened to a frame to the rear of which a lever is attached by means of a hinge.

On the underside of the lever, in a position at a distance from the hinge corresponding to the position of the plate, is located a matrix which is a negative of the relief to be produced. The matrix is also heated electrically (to approximately 1300C) so as to evaporate the water from the body and contribute to ensuring that the relief blank is released from the matrix after the moulding. The end of the lever is designed as a handle and a considerable proportion of the weight of the lever is located in the section around the handle to ensure that the stroke, which is described below, provides satisfactorily stamped reliefs.

The relief is struck by moving the lever downwards with considerable force so that the matrix strikes the bat which is pressed against the plate and, as a result of the counter pressure from the plate, is pressed fully into all parts of the matrix pattern. The relief thus moulded usually accompanies the matrix upwards and is removed from the matrix by hand. This operation is followed by a time-consuming cleaning of the relief from surplus body. If the outline of the relief is irregular, the cleaning operation can be an extremely tedious job.

When the cleaning has been concluded, the reliefs can be applied directly to the base articles by means of slip, a ceramic binder with organic ingredients which evaporate when the article is fired. Alternatively, the reliefs can be stored on ceramic plates wrapped in dampened textile cloths. Depending on their size and shape, the finished reliefs can be stored in a moist cabinet from a few days to several weeks before they are applied to the moulded or cast porcelain article which is to be decorated.

A disadvantage involved in the manual production procedure used so far is that some of the blanks are damaged during the cleaning operation and cannot be used. Furthermore, the mode of production is in itself time-consuming and if the casting is carried out by relatively unskilled workers, it can result in incompletely filled pattern components in the relief blanks. At the same time, the proportion of unsaleable goods for relief blanks produced by means of the current technique is so large that it constitutes a considerable economic burden in the production.

The purpose of the present invention is to apply a mechanical method for producing the type of relief blanks described above. The device produced for applying this mechanical method has been designed so that the disadvantages which are inherent in the manual production procedure are avoided.

The distinguishing characteristics of the invented procedure are presented in the following patent claims.

The procedure is such that the body which has been prepared for producing the relief blanks in the form of strings is inserted in a magazine, preferably arranged vertically, in one end of a device provided for implementing the procedure. A knife, which is suitably operated by pneumatic means and which is located in the lower part of the magazine, cuts off the body string into blanks of a suitable thickness. These are then transported between two thin films which run horizontally and which consist, for example, of polyethylene adhesive film with a thickness of 0.008-0.020 mm, to a matrix in which the required relief has been engraved in the form of a negative.

When engraving the matrix, the engraving has, of course, been carried out in such a way that the shrinkage in the porcelain body due to drying and firing is compensated.

When a blank has been halted by means of a photocell, micro-switch or any other means, above the matrix a die, preferably pneumatically controlled, is lowered and presses out the body into all the pattern components of the matrix. In the final phase of the stamping operation, the surplus body is cut off along the edges of the relief blank without the films breaking. When the die has returned to its home position, the films are put into motion and the relief blank is removed from the matrix. Its smooth reverse side is fastened to the upper film as a result of adhesion forces while the surplus body cut off from the blank remains on the lower film. When the films continue their path through the machine, each of them passes over a sharp deflecting edge.The surplus body is freed from the film at this edge and falls down onto a conveyor which transports it to a collection vessel for recycling. At the same time as the upper film is pulled across its deflecting edge, the relief blank is released from the film and falls down onto another conveyor which runs at a short distance below the deflecting edge. The blank falls with its patterned surface against the conveyor and when the belt turns at the end of the conveyor, the blank accompanies the belt for a short distance around the end roll before falling and ending with its right side up on a reception plate. An impulse is generated from there to halt the machine and the machine does not begin its next cycle until the relief blank has been removed from the reception plate to be applied manually to a porcelain article.It should be noted that in each cycle the films step forward oniy a distance such that the relief blanks remain suspended in the upper film at intervals of a few centimetres. This means that when the machine is running continuously, a small buffer of stamped blanks is suspended from the upper film.

The films are supplied to the stamping tool in the form of continuous sheets from an upper and lower supply roll. The film sheets are pulled across guide rolls and across the abovementioned deflection edges through the machine by a couple of motordriven rolls. The motors for these rolls run intermittently on receipt of a pulse from a sensor, for example a photocell, which sense when a relief blank has been removed from the reception plate. A device invented for implementing this procedure has been given the distinguishing characteristics which are presented in the following patent claims. A selected design form of this device will be described in further detail with references to the appended drawings, wherein: Figure 1 presents a side elevation of the device, and Figure 2 presents a part section through the device in accordance with the indication II - II in Figure 1.

A machine for stamping relief blanks for jasper porcelain consists of a tubular magazine (1), preferably arranged vertically, for pugged rolls of porcelain body (2) prepared in a pug mill. At the lower opening (3) in the magazine, a cutting device provided with an edge or a string, and called the knife (4) hereinafter, is arranged. This cuts off the pugged rolls (2) in bats of a selectable thickness through the reciprocating movement of a piston cylinder (5), which is hydraulicaily or pneumatically driven across the opening (3). If a bat which has been cut off should not be released from the knife (4) due to its sticky consistency, it is picked off by an ejector rod (6) which consists of the piston rod in another hydraulic or pneumatic cylinder (7).

The bat which has been cut off falls down on a lower film sheet (8) which is transported through the machine from a lower supply roll (9). The lower film sheet (8) functions as a conveyor belt and transports the bat in under the upper film sheet (10) which is supplied to the machine from an upper supply roll (11). Since the two film sheets (8 and 10) are pulled together at the end of the machine by a drive roll (12) with a press roll (13) driven by the output shaft from a gear mechanism (14) for a motor (15), they receive the same speed.

When a bat has been moved by the lower film sheet (8) into position above an engraved matrix (16), a photocell (17) generates a pulse to a control unit (18) which stops the motor (15). A die (21) applied to the piston rod (20) of a piston cylinder (19) then moves down towards the matrix (16). The upper film sheet (10) will lie between the contact surface of the die (21) and the bat when the die completes its stroke. As a result of this stroke, the bat is pressed against the lower film sheet (8) which is deformed as a result of the flexibility of the sheet until the bat has filled all the pattern components engraved in the matrix (16).The die (21) reaches its lowest position with a certain force at a negligible distance above the matrix (16) This not only makes the relief blank formed from the bat body compact but also causes the surplus porcelain body, which has run over the edge of the engraved matrix, to be sheared off against the sharp edges of the engraving. The motor (15) is then restarted to pull the next blank across the matrix (16). As a result of adhesive forces, the stamped relief remains suspended by its smooth upward facing side from the upper film sheet (10) while the surplus body, which has been cut off, remains on the lower film sheet (8).

When relief has been stamped, the film sheets are stepped forward and each of them passes over a separate deflecting edge (22 and 23). These deflecting edges have an angle which is less than 90". As a result, even if the body is stuck to the film, it is released from the film when the film passes over the deflecting edge. The surplus body is thus released from the lower film (8) when the lower film passes over its deflecting edge (22) and falls down onto a conveyor belt (24) which transports the surplus body to a collection vessel (not illustrated). The upper film (10) passes over an upper deflecting edge (23) under which a second conveyor belt (25) runs. One relief at a time is thus released and falls with its pattern side downwards onto the conveyor belt (25). The conveyor belt (25) transports the relief towards the front of the machine. At the end of the conveyor belt (25) the relief accompanies the conveyor belt part of the way around the end roll (26) of the conveyor belt before falling down with its pattern side upwards onto a reception plate (27). A second photocell (28) records the presence of the relief on the reception plate (27) and generates a pulse to the control unit (18) to stop the machine until the relief has been removed, whereupon a new cycle is started.

The two film sheets can either be discarded after use or, if the films are sufficiently thick, can be rewound and used again. If so, the films should, however, probably be displaced so that the stamping is not carried out at exactly the same spot as during the preceding units. Another possiblity is to switch the upper and lower films before the second run.

This procedure is also suitable and the machine can also be used for producing other porcelain components which are to be applied to a basic article, for example ears or handles.

Claims (12)

1. A procedure for producing reliefs for decorating jasper porcelain, characterised by the fact that bats consisting of porcelain body between two films are placed in position above a matrix where a die presses out the bats into the engraved pattern in matrix, and by the fact that the surplus body is cut free between the die and the edge of the matrix without cutting off the films.

2. A procedure in accordance with Claim 1, characterised by the fact that adapted pieces (bats) of plastic porcelain body are supplied between the films from a magazine provided with a shearing device.

3. A procedure in accordance with Claim 1, characterised by the fact that the films consist of polyethylene film.

4. A procedure in accordance with Claim 3, characterised by the fact that the film has a thickness of 0.008-0.020 mm, preferably 0.010-0.015 mm.

5. A procedure in accordance with Claim 1, characterised by the fact that the films are of aluminium.

6. A procedure in accordance with Claim 1, characterised by the fact that the stamped relief and the surplus porcelain body each accompanies a separate film as a result of adhesion in such a way that they are transported away from the matrix and come free from the films when the films are pulled across deflecting edges and are transported by means of conveyor belts, the relief being transported to a worker for manual application to a porcelain article and the surplus body being transported to a waste vessel.

7. A device for producing reliefs for jasper porcelain and similar components, characterised by the fact that it incorporates means for transporting two film sheets through the device between which blanks are transported across a matrix in which a die presses out one bat at a time to form a relief, whereupon the film sheets are pulled forward, with the relief suspended from the upper film sheet and the cut-off surplus body lying on the lower film sheet, and are transported away from the matrix.

8. A device according to Claim 7, characterised by the fact that it is provided with a magazine for pugged rolls of porcelain body, from which blanks are supplied to the lower film sheet by means of a shearing device.

9. A device in accordance with Claim 7, characterised by the fact that the film sheets are, after the relief has been stamped, each pulled over a separate deflecting edge under which respective conveyor belts pass, one for the surplus body and one for the reliefs, the latter conveyor belt carrying the reliefs to a reception plate.

10. An arrangement in accordance with Claim 8, characterised by the fact that its operation is controlled by a control unit on receipt of pulses from a first photocell at the matrix and a second photocell at the reception plate respectively.

11. A procedure as claimed in Claim 1 and substantially as described and with reference to the drawings.

12. A device for producing ceramic parts by the procedure claimed in Claim 1 and substantially as described and with reference to the drawings.