GB2595677A - Technical ceramics casting apparatus and method - Google Patents

Abstract

A ceramic casting system comprises a ceramic casting mould 2. The mould has two or more cavities. Each of the cavities is in fluid connection with a separate slip feed 30. In use, the cavities are so sized and shaped as to produce at least to produce two or more different types of product. The system also has a plurality of mould cavity pressurisation systems, wherein a separate pressurisation system is in fluid connection with each cavity, thereby allowing in use for the pressure conditions of each of the cavities to be separately set and adjusted. The system further includes a controller for controlling the pressure conditions supplied to each cavity by the process supply station, such that in use, different types of product can be produced simultaneously during a ceramic casting session in each of the cavities.

Description

Technical ceramics casting Apparatus and Method This invention relates to technical ceramics casting apparatus and methods. In a first aspect, it is a mould or casting cell, particularly for use in ceramic or specifically technical ceramic casting, more particularly for use in pressure casting, and more particularly still for use in automated, high speed pressure casting and in particular is for use in the high speed automated pressure casting of ceramic hands for use on a rubber glove making production line. The second aspect is that it is a system incorporating the mould or a plurality of moulds, wherein the moulds are borne by casting machines for the production of ceramics with multiple pieces and wherein those pieces are cast under different conditions. The third aspect is that it is a method for operating the system and the mould. The fourth aspect is that it is a technical ceramic hand or other assembled ceramic product produced using the system or the method of the claims. The hand is preferably for use on a disposable glove making production line, being the object on which the gloves are formed.

Background and prior art

High pressure ceramic casting is well known and is documented in the Applicant's other patent specifications, such as GB2518856 and GB2510182. In these applications, a combination of variations of pressure in a mould, and variations as to the orientation of the mould, allow for the quick casting of items such as sanitaryware units.

More recent patent application GB2572766 displays various innovations in this foundational technology in the context of a production line, thereby making marked further rationalisations of the production of ceramic products.

Although the apparatus described in these applications is well suited to the casting of essentially homogeneously composed items, such as the aforementioned sanitaryware products where, for example, the walls of an item (for example, a kitchen sink) are of a substantially uniform depth, or the ceramic material in the cast is of a single mixture, it is not so well suited to items which might require a portion composed of a different mixture of materials or of a different depth, or ceramic products made from the assembly of different pieces. Although of course ceramic products of this multiple character can be hand-assembled, this is slow and lacks precision. Where an assembled product with parts of such heterogeneous characteristics is nonetheless a relatively low value or mass product item, or where its uniformity is important, the speed and consistency of a high-tech production line and pressure casting means is desired.

Whilst the applicant has built a large number of casting machines in the past for producing sanitaryware products which have multiple moulds all with the ability to run different casting parameters, there has never been a casting system wherein different parameters are run in the same mould at the same time.

There is a real and widely felt need in the industry for a system which provides a fast and quality-consistent means of producing a relatively complex product composed of different types of products.

The specific use case of the disposable glove industry provides a specific problem in the form of the short life span of the ceramic hands onto which the disposable gloves are formed. The ceramic hands in this context are mounted from the base and it is the base which tends to perish, leaving the ceramic hand useless, since with a cracked or otherwise broken base it is no longer possible to use it and it requires replacement.

It is to these problems, amongst others, that the application attempts to provide solutions.

Summary of the invention

In a first broad independent aspect, the invention comprises a ceramic casting system, the system comprising a ceramic casting mould, the mould comprising two or more cavities, wherein each of the cavities is in fluid connection with a separate slip feed, and wherein, in use, the cavities are so sized and shaped as to produce at least two or more different types of product a plurality of mould cavity pressurisation systems, wherein a separate pressurisation system is in fluid connection with each cavity, thereby allowing in use for the pressure conditions of each of the cavities to be separately set and adjusted, the system further comprising a controller for controlling the pressure conditions supplied to each cavity by the mould cavity pressurisation systems, such that in use, different types of product can be produced simultaneously during a ceramic casting session in each of the cavities.

Advantageously, the system so described allows for the simultaneous casting of different types of ceramic product in a single mould. The products may subsequently be combined in a compound product and are conveniently collocated for that purpose. The swift and accurate production and reproduction of compound products is therefore ensured.

Preferably, the controller controls one or more of the following parameters separately for each cavity in the ceramic casting mould: * the pressure in the cavity during the casting stage; * the duration of the casting stage; * the duration of the draining stage; * the pressure in the cavity during the consolidation stage; or * the duration of the consolidation stage.

Advantageously, the control system allows the further precision setting, monitoring and adjusting of casting parameters such that a casting session can yield both types of ceramic product simultaneously with further efficiency savings.

Preferably, the pressurisation systems are attached to the slip feeds and the internal pressure parameters of each cavity are controlled via the slip feeds.

Advantageously the provision of a slip feed of this nature provides a robust and unified means of controlling the pressure within a given mould, cavity or mould portion.

Preferably, the ceramic casting mould comprises a plurality of mould portions, the system further comprising movement means for moving the mould portions from a first, assembled position to a second, disassembled position and wherein in the latter position, the ceramic products may be demoulded and wherein the movement means comprises a casting machine, the casting machine comprising at least a first and a second opposed, mould portion bearing mount, to which each of the respective mould portions is mounted, such that each respective mould portion is opposed to the other respective portion, wherein each mount further comprises at least one passage running through it the casting machine further comprising at least one elongate beam running through a passage in each mount the casting machine further comprising means for moving a least one mount back and forth along each beam such that the mould can be opened and closed.

The provision of a casting machine advantageously allows for the undertaking of casting at a high pressure and with speed, efficiency and precision.

More preferably, the mounts each comprise a quadrilateral plate and wherein each plate has a plurality of passages including at least one at or adjacent each corner of the plate.

The quadrilateral plate with beams in each corner provides a particularly stable way of locating the mould portions in a fixed plane. The mould can be opened and closed with precision and with stability, which improves the quality of the product moulded therein.

Preferably, the second product cavity comprises a portion sized and shaped to hold a pre-cast first product.

Advantageously, the provision of the second portion allows for the introduction of the pre-cast first type of product into the second type of product.

Preferably, a first mould cavity is arranged to provide a solid cast and wherein a second mould cavity is arranged to provide a drain cast.

Advantageously, this mould cavity arrangement allows for the production of diverse ceramic types, which may thereby be combined.

In a second broad independent aspect, the invention comprises a method of ceramic casting, the method comprising the steps of using a mould, the mould comprising at least a first cavity and second cavity, the first cavity being so arranged as to produce a first product component and the second cavity being so arranged as to produce a second product component, a first casting is undertaken, wherein as a result of said first casting at least a first product component is produced, on completion of the first casting the first product component is demoulded, the first product component is removed from the first mould cavity and placed in the second mould cavity, a second casting is undertaken, wherein as a result of said second casting the first product component is incorporated into the second product component, forming an assembled product.

The method described provides a manner of casting heterogeneous ceramic product or ceramic product component types in a single mould. The method allows for the fast and efficient incorporation of one component type into another in order to produce a compound component. This method provides a means of the mass production of these compounds or assembled products, thereby allowing for the production of relatively low-cost products on a mass scale.

Preferably, the first and second cavity are so arranged that product components may be simultaneously cast in a first casting cavity subject to a first set of parameters including pressure parameters, and in a second casting cavity subject to a second set of parameters, including pressure parameters.

Advantageously the provision of separate casting cavities allows for the production of quite different products in the same mould.

Preferably, the parameters of the first and second cavities are manipulated such that each of the first and second product components are produced simultaneously and during a period of substantially identical duration.

Advantageously, finishing the casting of each product component of the same type allows for the efficient management of casting sessions, such that the number of products produced in a given time period is thereby increased.

Preferably, subsequent to the removal of the first product component from the from the first cavity and prior to the second cast, the first cavity is purged, such that it can be used to produce a further batch of the first product component during the second cast.

Preferably, after the second cast, the assembled product is removed from the mould, the second cavity is purged and the further batch of the first product component is placed in the purged second cavity, for incorporating into a further assembled product.

Advantageously, the undertaking of the method in the manner above allows for the maximisation of the yield of products in a given set of casting sessions.

In a third broad independent aspect, the invention comprises a ceramic hand produced using the method described above, wherein the first product component is a base for the hand and the second product component is the main body of the ceramic hand.

Preferably, the first product component is partially contained by the second product 25 component.

Preferably, the depth of the base is at least twice that of the walls of the hand.

The pressure cast hand produced in this process is different from that produced by traditional recasting using a plaster mould or via other pressure casting methods. The method employed by this process casts the hand onto the pre-cast base to eliminate the difficulties and problems associated with the normal process of bonding a base onto the bottom of a hand. The benefits include: * Elimination of differential shrinkage which causes cracking -the bases are cast in the same mould using the same slip at the same temperature as the hand. The bases are demoulded and immediately inserted into the hand mould cavity, ensuring that the hand and base have an identical moisture content and the same characteristics once the finished hand is demoulded.

* Alignment -the base insertion process is automatic with the final base position determined by the mould cavity ensuring perfect alignment.

* Split faults -prior art hand producing process requires the base to be cast separately from the hand and glued together at a later time. The joint between the hand and the base is an additional operation which causes further potential for losses.

Brief description of the figures

The invention will now be described in detail, but by way of example only, with reference to the figures, of which: Figure la is a first perspective view of a mould of the invention; Figure lb is a second perspective view of a mould of the invention; Figure lc is a first side elevational view of a mould of the invention; Figure ld is a second side elevational view of a mould of the invention; Figure 2a is a first perspective view of a casting machine of the invention; Figure 2b is a second perspective view of a casting machine of the invention; Figure 3 is a perspective view of a tool changing device of the invention; Figure 4a is a perspective view of a process supply station of the invention; Figure 4b is a first side elevational view of a process supply station of the invention; Figure 4c is a second side elevational view of a process supply station of the invention; Figure 5 is a perspective view of a casting machine during the base demoulding step of the invention; Figure 6 is a perspective view of a casting machine of the invention during the step wherein the bases are placed into empty hand cavities; Figure 7 is a perspective view of a casting machine of the invention wherein the machine has moved to the hand demoulding position; Figure 8 is a perspective view of a casting machine of the invention demoulding the assembled product, in this case a completed ceramic hand; Figure 9a is a cross-sectional side view of a ceramic hand of the invention; Figure 9b is a side view of a ceramic hand of the invention; and Figure 9c is a perspective view of a ceramic hand of the invention.

Detailed description of the preferred embodiments

Figures la -ld all show different views of a mould 2 of the invention. The mould 2 comprises a first piece 4 and a second piece 6. First piece 4 and second piece 6 form the mould 2 when coupled together. In other embodiments it is possible for the mould 2 to have a number of pieces greater that two, for example when the casting of more complex items is required. In use, first piece 4 and second piece 6 face one another, such that the cavity bearing face 8 of first piece 4 faces the cavity bearing face 10 of second piece 6. When the mould 2 is being used the first and second pieces 4, 6 of mould 2 are moved in a linear fashion -substantially along a single plane -towards and away from each other in order to open and close the said mould. Cavity bearing faces 8 and 10 of first and second pieces 4, 6 of the mould 2 comprise a plurality of shaped cavities 12. In the present example, the cavities comprise on the first piece 4 eight cavities 12 being four first hand portion cavities 14 and four hand base cavities 16. The second piece bears a further array of cavities 12, namely second hand portion cavities 18 and second base portion cavities 19, wherein the ceramic product comprising the base 20 can be fitted within the respective first and second ceramic hand portions 22, 24 from moving mould half and fixed mould halves respectively via a shelf 25 in the appropriate cavity, where it can rest prior to and during a subsequent casting session.

The mould 2 further comprises access points 28 feeding the various cavities 12 wherein the access points 28 are separate and allow for separate slip feeds 30 (not shown) to be placed in fluid connection with the said cavities 12. The mould 2 further comprises a plurality of connectors 32 (not shown) for connecting the mould 2 to a casting machine 34, said connectors being for example bolts.

At figures 2a and 2b the casting machine 34 is illustrated. Casting machine 34 comprises fixed plates 36 and 40 and moving plate 38, wherein plates 38 and 40 are arranged such that they face one another. The inward facing surfaces of the plates 38, 40 are connected via connectors 32 with the mould pieces 4, 6. The plates 38,40 are arranged such that the first plate 38 can be moved towards and away from the second plate 40.

This is done using hydraulic or pneumatic means preferably and more preferably than via the inflation of lay flat tubing (not shown) disposed between first plate 38 and back plate 36. In alternative embodiments both first and second plates 38,40 can be moved relative to one another but here the second plate 40 is static, thereby providing additional stability and accuracy during moulding and demoulding. In use, therefore, the first plate 38 may be moved towards the second plate 40 thereby bringing respective mould pieces together. During moulding and demoulding, the first plate 38 moves along beams 44. In this embodiment, there are four beams 44, one arranged adjacent or at each corner of the plates. The plate and beam arrangement provides the facility to open and close the mould 2 precisely and to apply the necessary force to enable pressurised liquid slurry to be contained within the mould 2 and its cavities 12 whilst all of the necessary service connections are provided through bulkhead fitting fitted in the fixed machine plate 40 where the slip feed hoses from the supply station SO connect.

The beam runs through apertures in both first and second plates 38, 40 as well as the back plate 36 thereby lending additional strength to the construction. Here the beams are circular cylindrical, but they may be substituted by other shapes, including rails. Alternative means of stabilising and collocating the plates relative to one another are anticipated and means other than hydraulic and pneumatic such as mechanical or electrical actuation and movement may be used in alternative embodiments. The fluid used in the hydraulic or pneumatic movement is supplied via a separate fluid pressurisation system, which in preferred embodiments is a centrally mounted and controlled hydraulic power pack or cylinder 46 For additional stability, the casting machine 34 is attached to ground engaging portion 48 and may be screwed or bolted into an appropriate flooring surface, which advantageously provides further stability in use.

The casting machine 34 is fluidly connected via slip feeds 30 from process supply station SO, which can be seen at figures 4a, b and c. Process supply station 50 feeds slip feeds 28. The process supply station 50 provides all of the services required to be able to cast two completely different types of product or product components in the same mould 2 at the same time on a casting machine 34. The slip exits from slip feed exits 28. The mould 2 has two separate slip feeds 28 each feeding specific cavities 12 within the mould and in this preferred embodiment, the a first slip feed supplies slip to the hand cavity or cavities and a second slip feed provides slip to the base cavity or cavities Each of the slip feeds 28 is connected to separate pressurisation systems 52 and 54 on the process supply station 50 enabling different casting processes to be run simultaneously. The process supply station SO is attached to a controller which may be a central electronic control system and it is on this system (not shown) that the controlling parameters are all set and monitored and this facilitates completely independent high pressure casting pressures and times in different parts of mould 2 as well as different draining time and consolidation pressures and times. This enables two very different products to be simultaneously cast in the same mould 2 with both casting cycles to be controlled to finish at the same time.

Other ceramic products or product components may be substituted in other embodiments of the invention. In this instance, the assembled product is a ceramic hand SS with a hand base 56 incorporated. In the example product the hands SS are 4.5mm thick hollow drain cast product and the bases 56 are a 10mm thick solid cast product, this being considered an optimum balance of robustness and economy of materials -although of course other combinations are possible for these or other products. The two types of product, being product components of an assembled product, require different casting parameters which are all controlled in the process supply station 50.

On setting up the first cycle on the casting machine 34 will run solid cast bases 56 only.

At the end of the cycle the mould 2 is open and the newly cast hand bases 56 are demoulded and placed into the bottom of the empty side of the hand mould cavity of fixed mould half 14. A second casting session is then undertaken wherein the hollow cast hand 55 is cast around the solid hand base thereby casting the hand base into the overall ceramic product comprising the base 20. The hollow cast hand produced in this way -with the solid cast base cast into it -is then automatically demoulded. Once the mould 2 has been demoulded it is washed and purged for the next casting cycle. The mould 2 is then closed and the casting process starts again. Demoulding of the components is undertaken by a demoulding tool 60 manipulated and controlled by a robotic arm (not shown). The robotic arm is connected to the demoulding tool 60 using the interface plate 58. The interface plate is attached -preferably permanently -to the end of the robotic arm and is used as an automatic tool changing device such that the robot can put the demoulding tool 60 down and pick up a different tool, or something else, if required. As part of the mould change process, the robot will put the demoulding tool 60 down and connect directly to the top of a mould half using the interface plate, pick the mould up and move it to the mould change station.

One example of a completed casting system 62 not shown might comprise four separate casting machines 34 with each having a mould 2 producing a plurality of separate pieces and each casting machine 34 having its own separate process supply station. The process supply station 50 provide the casting machines 34 with all the services required to cast pieces, i.e. air for demoulding, purging and consolidating, low pressure slip, high pressure slip and cleaning water. However, to run a system, only one casting machine 34 is required, along with a suitable robotic arm. In the present example, the four casting machines 34 are managed by a single control system (not shown) and are demoulded. Demoulding of the components is undertaken by a tool 58. which is manipulated and controlled by a robotic arm. All finished products are demoulded onto a single conveyer (not shown). Included within the system is a mould change station and a mould storage system which enables moulds to be semi-automatically loaded and unloaded into the casting machines 34. In the current example, the moulds 2 are suitable for casting four hand base portions and four hollow cast hands. The process supply station 50 connected to each casting machine 34 facilitates two completely different sets of casting parameters to be run simultaneously on the same mould 2.

When the mould 2 is opened after the casting process is complete hands are left in piece 4 and cast bases are left on piece 6.The robotic arm moves demoulding tool 60 into position via an interface plate, removes the bases from one mould half 6 and places them on the shelf 25 in the empty hand cavity 18. It then moves to the other mould half 4 and removes the completed ceramic product 20 -ready for placing on to a conveyor. Mould 2 then closes and the casting process starts again. On the first cast of any sequence the casting machine 34 casts bases only. On the final cast of any sequence the machine casts completed ceramic products comprising the base (in other words hands) only. All other casting cycles cast both hands and bases.

The apparatus and method described above are particularly useful in the production of ceramic products which are made of multiple parts. For example, this process has been found to be particularly appropriate for the production of ceramic hands for use in the subsequent production of rubber gloves.

At figure 9, a completed ceramic product (which in this case is a hand) 20 comprises a hollow body 55, moulded in the shape of a hand. Hollow body 55 has a base, which comprises an aperture (not shown), so sized and shaped to be cast around and therefore to receive a discoid cast base portion 56. The cast base portion 56 in the finished product is arranged such that the discoid base portion 56 is contained within the aperture in the base and is held in position during casting and there is thereby formed in their assemblage a base, or in preferred embodiments the walls of the hand might be 4mm thick and the base might be 10mm thick. The cast base portion 56 is a previously cast ceramic or clay part, positioned such that it will for the base of hollow body SS. The halves of the body SS are cast around the base 56 The product so produced is advantageously substantially more robust than conventional ceramic hands, which it is understood have a tendency to crack and break around the base when they are themselves utilised as glove moulds, for example for latex gloves and the like. This is achieved by first casting discoid portion and drain casting the body 55 of the hand 20 such that it contains the said portion. The pressure cast ceramic hand 20 produced in this process is different from that produced by traditionally casting using a plaster mould or by other pressure casting methods. The method employed by this process casts the hand on to the precast base which eliminates the difficulties and problems associated with the 'normal' process of bonding a base on to the bottom of the hand.

Claims (15)

1. CLAIMS1. A ceramic casting system, the system comprising; a ceramic casting mould, the mould comprising two or more cavities, wherein each of the cavities is in fluid connection with a separate slip feed, and wherein, in use, the cavities are so sized and shaped as to produce at least two or more different types of product; a plurality of mould cavity pressurisation systems, wherein a separate pressurisation system is in fluid connection with each cavity, thereby allowing in use for the pressure conditions of each of the cavities to be separately set and adjusted, the system further comprising a controller for controlling the pressure conditions supplied to each cavity by the mould cavity pressurisation systems, such that in use, different types of product can be produced simultaneously during a ceramic casting session in each of the cavities.
2. 2. A system according to claim 1, wherein the controller controls one or more of the following parameters separately for each cavity in the ceramic casting mould: the pressure in the cavity during the casting stage; the duration of the casting stage; the duration of the draining stage; the pressure in the cavity during the consolidation stage; or the duration of the consolidation stage.
3. 3. A system according to either claim 1 or claim 2, wherein the pressurisation systems are attached to the slip feeds and the internal pressure parameters of each cavity are controlled via the slip feeds.
4. 4. A system according to any of the preceding claims, wherein the ceramic casting mould comprises a plurality of mould portions, the system further comprising movement means for moving the mould portions from a first, assembled position to a second, disassembled position and wherein in the latter position, the ceramic products may be demoulded; 10 15 20 and wherein the movement means comprises a casting machine, the casting machine comprising at least a first and a second opposed, mould portion bearing mount, to which each of the respective mould portions is mounted, such that each respective mould portion is opposed to the other respective portion, wherein each mount further comprises at least one passage running through it; the casting machine further comprising at least one elongate beam running through a passage in each mount; the casting machine further comprising means for moving a least one mount back and forth along each beam such that the mould can be opened and closed.
5. S. A system according to claim 4, wherein the mounts each comprise a quadrilateral plate and wherein each plate has a plurality of passages including at least one at or adjacent each corner of the plate.
6. 6. A system according to any of the previous claims, wherein the second product cavity comprises a portion sized and shaped to hold a pre-cast first product. 20
7. 7. A system according to any of the previous claims, wherein a first mould cavity is arranged to provide a solid cast and wherein a second mould cavity is arranged to provide a drain cast.
8. 8. A method of ceramic casting, the method comprising the steps of: Using a mould, the mould comprising at least a first cavity and second cavity, the first cavity being so arranged as to produce a first product component and the second cavity being so arranged as to produce a second product component; a first casting is undertaken, wherein as a result of said first casting at least a first product component is produced, on completion of the first casting the first product component is demoulded, the first product component is removed from the first mould cavity and placed in the second mould cavity; a second casting is undertaken, wherein as a result of said second casting the first product component is incorporated into the second product component, forming an assembled product.
9. 9. A method according to claim 8, wherein the first and second cavity are so arranged that product components may be simultaneously cast in a first casting cavity subject to a first set of parameters including pressure parameters, and in a second casting cavity subject to a second set of parameters, including pressure parameters.
10. 10. A method according to claim 8 or 9, wherein the parameters of the first and second cavities are manipulated such that each of the first and second product components are produced simultaneously and during a period of substantially identical duration.
11. 11. A method of any of the previous claims, wherein subsequent to the removal of the first product component from the first cavity and prior to the second casting, the first cavity is purged, such that it can be used to produce a further batch of the first product component during the second casting.
12. 12. A method according to claim 11, wherein after the second casting, the assembled product is removed from the mould, the second cavity is purged and the further batch of the first product component is placed in the second cavity, for incorporating into a further assembled product.
13. 13. A ceramic hand produced using the method of any of claims 8-12, wherein the first product component is a base for the hand and the second product component is a main body of the ceramic hand.
14. 14. A ceramic hand according to claim 13, wherein the first product component is partially contained by the second product component.
15. 15. A ceramic hand according to claim 14, wherein the depth of the base is at least twice that of the walls of the hand.