GB2543532A

GB2543532A - Portable casting apparatus

Info

Publication number: GB2543532A
Application number: GB1518595.2A
Authority: GB
Inventors: Moore Christopher
Original assignee: Pcl Ceram Ltd
Current assignee: Pcl Ceram Ltd
Priority date: 2015-10-20
Filing date: 2015-10-20
Publication date: 2017-04-26
Also published as: GB201518595D0; WO2017068323A1

Abstract

A portable casting apparatus comprising a base 102 and rear column 104, in which a frame 140 comprising an upper and lower flange portion are mounted via an interconnecting web 116, which allows rotation on a horizontal axis. A jacking means 150 clamps workpiece 200 between the flanges. Preferably, the web is mounted to the midpoint of the frame allowing manual rotation without interference from the base. Preferably, the jacking means, comprising ratchet jack 154 with pressure gauge 160, is between two C-shaped plates 142 that form the frame and the upper flange comprises resilient pad 148. Preferably, rotation is indexed. Preferably, the jack free end corresponds in cross-section to a recess in the workpiece. Preferably, a control panel 120 supplies pressurised air at two different pressures using hoses. Preferably, the work piece comprises slip cup and mould of identical annular cross-section with air inlets and connected by gasket.

Description

Portable Casting Apparatus

Field of the Invention

The present invention is a portable pressure casting apparatus. More specifically, the present invention relates to an essentially portable casting apparatus in which a mould is provided and to which a quantity of a fluent slurry or slip, consisting predominantly of a clay, chalk or other ceramic material, is introduced and subsequently dried, pressurized, and/or sintered to create a hollow (or sometimes solid) body of desired shape. Equally, this portable pressure casting apparatus can be used in resin moulding and other cases where the separation of mixtures is desirable, as can be the case with the manufacture of metal polishing elements, filtration equipment and sewage. More specifically, the present invention ideally provides a casting apparatus which is adapted for testing the various parameters of the casting process, the materials used therein, and the resulting items cast thereby. In this regard, the volume of the mould may be quite small, for example of the order of 10-3 m3, although this volumetric size is provided purely as an aid to understanding of the present invention and should not be regarded as a limitation thereof. Yet further specifically, the present invention relates to small-scale laboratory casting apparatus which may be either free-standing on, or fixedly mounted to, a laboratory bench or table top.

Background to the Invention

The ceramic casting industry is very well established, and there exist various different casting techniques which in turn create usually solid ceramic products with different physical characteristics. Of particular relevance to the present application is the slipcasting process whereby a slurry or slip of liquid clay is poured into a plaster mould. The water in the slip is drawn or forced out (e.g. under gravity, under a vacuum or by some physically, hydraulically or pneumatically applied pressure) leaving an inside layer of solid clay. Once the solid layer is thick enough, the excess slip can be removed from the mould if desired. During or after moisture extraction, the solid layer starts to dry, and once dried to a sufficient degree, the cast item can be removed from the mould, usually by separating the two separable parts of which moulds are most commonly constituted.

Although pressure casting is widely practised, and there are in existence various types of dedicated pressure casting apparatus (see for example Applicant's prior published patent applications WO2015/049486 and WO2014/118499, incorporated herein by reference), there exists little by way of dedicated test or experimental casting apparatus, whether for slipcasting or other forms of casting.

One form of experimental apparatus currently available for testing slurries and slip materials, as well as suspensions, is known as the Baroid Filter Press, shown in Figures 1A and 1B hereof. As will be seen from these figures, the apparatus indicated generally at 2 is essentially free-standing and of generally simple welded construction wherein a pair of feet 4 are welded to a frame 6 consisting of a pair of upright members 6A, 6B between which are further welded a top bar, a centre bar 10 and a crossbar 22, said centre bar serving as a support for a slip cup 12, the component parts of which are shown in exploded arrangement in Figure 1B. Said slip cup 12 is seated substantially centrally on said centre bar 10 such that a threaded screw which passes through a correspondingly threaded aperture in top bar 8 is brought to bear against the upper surface of a top cap 30 of said slip cup by manual clockwise rotation thereof achieved by means of a “T" shaped handle 14 affixed to the end of said threaded screw remote from the free end thereof. By such means are the various components of the slip cup clamped securely together. In addition, said slip cup top cap 30 is provided with a fluid inlet 32 through which pressurised air or other fluid can be introduced by means of a suitable air hose 16 to exert a downward surface pressure on the contents of the slip cup. It can be seen from the Figures that slip cup 12 includes a base cap 34 which is provided with an opening (not shown) substantially centrally to which a filtrate tube 36 is secured, by means of which the fluid component of the slip can escape from the slip cup and drop into a graduated cylinder 18 thus enabling a determination of at least a moisture extraction rate for the slip currently under test within the slip cup. Graduated cylinder 18 is affixed at its base to a horizontal support plate 24 which is in turn connected by means of a thumb screw 24 to a threaded support rod 20 screwingly fixed within cross bar 22.

From Figure 1B, it can be seen that the slip cup 12 comprises the top and base caps 32, 34 respectively, and between these are provided rubber gaskets 38, a slip cell 40, a filter 42 (of paper or other semi-permeable material), and a perforated screen 44.

Although this apparatus is relatively robust and adapted for test purposes in that it is free-standing and is of a size suitable for mounting or positioning on a lab bench or table, the design of the apparatus is inflexible - that is, it is a completely rigid construction adapted solely for determining the vertical, gravity assisted moisture extraction rate from slip under some predefined fluid pressure, and there is no means whereby the slip cup can move within the apparatus once secured therein and a test is taking place. Furthermore, it is to be noted that while the filter press described includes a slip cup, there is no means whatsoever whereby the apparatus can receive a mould of desired shape and within which test items can be cast under pressure. A first object of the invention is therefore to overcome this disadvantage and provide a more flexible casting testing rig. It is a further object of the invention to provide casting test apparatus which can be used to create small sample cast items for testing, and which incorporates the types of control systems and physical features more commonly found in commercially casting available casting apparatus adapted for industrial production.

It is a further object of the invention to provide a casting rig which accepts a mould of desired shape and within which items can be cast and subsequently released therefrom for inspection and testing.

Summary of the Invention

According to the present invention there is provided portable casting apparatus comprising a base and a column towards the rear thereof and extending upwardly therefrom, said apparatus further comprising a frame comprising at least upper and lower flange portions which together define an opening, and an interconnecting web portion disposed behind the opening and by means of which said upper and lower flange portions are connected, said interconnecting web portion of said frame being mounted to said column so that a clearance exists between said base and said frame lower flange portion, characterised in that jacking means are mounted to one of said frame upper and lower flange portions such that the direction of travel of a ram of said jacking means is directly towards the opposing flange portion so that, in use, a workpiece may be clampingly retained within said frame between a free end of said ram and the opposing frame flange portion, and further characterised in that the mounting between said interconnecting web portion and said column permits relative rotation therebetween to allow the entire frame to be rotated while a workpiece is clampingly retained therein.

Most preferably, the interconnecting web portion of the frame is mounted to the column of the apparatus in the region of the mid-point of the former such that the frame can be rotated completely without the base interfering with the upper or lower flange portions of the frame as the case may be.

Most preferably, the jacking means is mounted in the lower flange portion of the frame, and the upper flange portion thereof is provided with a resilient pad, for example of rubber or other compressible material, and against which one end of the workpiece reacts when clampingly retained within the frame by means of the clamping force applied to the alternate end of the workpiece by the ram of said jacking means.

Most preferably, the jacking means is a manual jack, preferably lever-driven and incorporating a ratchet mechanism, and further preferably connected to a pressure measurement gauge affixed to one side of the lower flange portion of the frame.

Most preferably the mount permitting the rotation of the frame relative to the column of the apparatus frictionally resists such rotation to an extent which is capable of being overcome by human force.

Most preferably said mount is indexable such that the frame may be locked in one or more rotated positions relative to the column to which it is mounted thereby.

Most preferably, the workpiece is provided with a recess, most preferably of a shape and size which corresponds to the shape and size of the free end of the ram of the jacking means which can thus be received in said recess and which thus, at least to some extent, prevents the workpiece from laterally moving within the frame. Most preferably, the cross-sectional shape of the free and of the ram and the recess are non-circular, in which case the cooperation between said ram free end and said recess effectively also prevents the workpiece from rotating relative to the ram.

Most preferably the lower flange portion of the frame provides one or more seating surfaces on one or both sides of the jacking means which freely support said workpiece in upright condition above said jacking means in anticipation of a ram thereof being upwardly jacked into the recess in the base of said workpiece.

Most preferably the frame is essentially C-shaped.

Yet further preferably, the frame comprises two spaced-apart C-shaped plates secured to one another by means of one or more cross-members. Most preferably, the jacking means is mounted between adjacent lower flange portions of respective C-shaped plates, which further preferably are provided with flattened planar edges to provide support for a workpiece with a flat planar base.

Most preferably, the apparatus comprises a control panel by means of which the supply of pressurised air is initiated, adjusted and terminated. Most preferably, the control panel includes at least two outputs to which air hoses may be attached, and through which pressurised air may be supplied at different pressures. In a particularly preferred embodiment, the control panel may include two or more separate inputs directly connected to the said two or more separate outputs. Alternately, the control panel may require, or be provided with only a single input to which a single source of pressurised air is delivered, said control panel including therein air supply bifurcation means connected to said single input, said two separate outputs being directly connected within said control panel to each of the bifurcations of said air supply bifurcation means.

Preferably the workpiece consists essentially of two separable hollow parts each having a closed end, the external surface of which forms the base of that part, and an open end, one being a slip cup and the other being a mould.

Most preferably the mould is porous or semi-porous, and includes a shaped cavity - the porosity of the mould allows the mould to act as the separation mechanism (as opposed to the prior art method which requires filtration of some kind). This also allows the casting of items within the apparatus to be a much truer representation of industrial casting processes.

Most preferably, the slip cup and the mould are of essentially identical cross-sectional shape and size, and have a wall thickness which is at least similar if not identical such that when their open ends are brought into mating contact to form the workpiece, a cavity is defined therein having substantially smooth walls, particularly around the interface of slip cup and mould open ends. In the alternative, a two- or multi- part mould comprising parts of different shape and/or size and/or wall thickness, bridged by one or more adaptor plates or adaptor pieces, such that the non-identical mould portions can be joined to form a single mould. The mould portions may further exhibit different level of porousness.

Preferably, said slip cup and mould open ends are essentially annular in cross-section, and further preferably, at least one of the slip cup and mould open ends is provided with a O-ring gasket or seal which stands proud of the otherwise planar annularly shaped open end.

In a particularly preferred embodiment, an annular channel corresponding in shape, but being one of: - Shallower than the extent to which the O-ring seal stands proud of the annular surface in which it is seated, - Narrower than said O-ring seal is provided in annular surface of the open end of the other of the two parts of the workpiece such that together, said O-ring and said annular channel provide the means by which one part is correctly and precisely brought into contact with the other, and in a manner which provides positive feedback to an operator that the two parts are in correct registration with one another.

Most preferably, one or both of the separable parts of the workpiece are provided with at least one air inlet to which air hoses can be connected to deliver pressurized air from the air outlets of the control panel to the interior of the said parts. Most preferably, the air inlet provided on the mould is provided at a position along its length remote from its open end such that pressurised air delivered therethough acts to free one or more exterior surfaces of an item having been cast within said mould from the corresponding one or more interior walls thereof and thus said cast item can be released from the mould, most preferably after having been separated from the slip cup after the completion of a casting operation performed while both parts are clampingly held together within the frame.

In certain specialised forms of casting, the air could be replaced with other fluids - for example nitrogen or a nitrox mixture, water or an alcohol suspension in the cases of some ceramic slurries.

It will be appreciated from the above that the casting test apparatus and the workpiece operate substantially in concert, and in one aspect at least, the invention should be considered as extending to a combination of both a casting test apparatus as previously described, and a workpiece also as described. Furthermore, it will also be appreciated that while the invention preferably includes a workpiece consisting of two separable parts, one being a slip cup and the other being a mould, it is equally possible that the workpiece may be of essentially unitary construction having an internal cavity to which fluid, whether liquid slip or slurry material, or pressurized air, may be delivered through one or more ports provided in and through either the side or end walls of said workpiece.

Further independent aspects of the invention should be considered to be the apparatus as described herein with reference to the accompanying drawings, and the method of casting also as hereinafter described.

The invention provides advantage in that the apparatus simple to operate and yet potentially solves one of the great challenges in the ceramics industry, and indeed any casting industry, that being the understanding of how clay slip will perform in pressure casting and the measured optimisation of that performance. The apparatus described also allows technicians to replicate both solid and hollow casting processes in a precisely repeatable manner using a variety of mould shapes in the laboratory - this is key to the quantitative analysis of slip performance. The apparatus is not only simple, but it is a compact portable unit.

Other advantages, attributes and aspects of the present invention will become apparent from the following specific description wherein:

Brief Description of the Drawings

Figures 1A, 1B show respectively a perspective view of a Prior Art Baroid filter press, and an exploded perspective view of the various components which constitute the slip cup used therein,

Figures 2, 3 respectively show schematic perspective views of a portable casting apparatus according to the invention in which the frame is shown in upright and rotated positions,

Figure 4 shows an exploded perspective view of the workpiece consisting of a clip cup and mould, and

Figures 5, 6, 7 shows respectively a side elevation, a front elevation, and a plan view of the apparatus according to the invention.

Detailed Description

Referring to Figure 2, there is shown a portable casting test apparatus indicated generally at 100 and having a base 102 constituted by a pair of horizontal spars 104 to which threaded adjustable feet, two of which are referenced at 106, are received in appropriate threaded apertures in the said spars and thus connected thereto. A removable tray 108 having edge flanges 110 is placed between said spars and which provide support for the edge flanges 110 of said tray. Towards the rear of said base 102, a horizontal cross-member 112 is provided which structurally, e.g. by being welded thereto, connects spars 104 together, and in the region of a mid-point of said crossmember, a columnar strut 114 is welded thereto and extends generally vertically upwardly therefrom towards a free end thereof, which in this embodiment includes, is in the form of, or has welded thereto a mounting plate 114A. Atop said mounting plate is bolted a swivel anchor indicated generally at 116 and including corresponding mounting plat 116A which is bolted or otherwise connected to mounting plate 114A.

To the right side of the base 102 is provided a control panel indicated generally at 120 secured to an extended portion of cross-member 112 and which provides two sets of identical controls 122A, 124A, 122B, 124B which respectively allow an operator to: gradually increase or decrease the supply of a pressurised fluid, most commonly air (122A, 124A), and - Open or close valve means (124A, 124B) within the control panel so that the pressure of fluid within different parts of the apparatus can be effectively maintained or released (as will be hereinafter described).

Control panel 120 also includes two gauges 126A, 126B which allow an operator to quantitatively gauge the current fluid pressure at a particular time.

Although not shown in the Figure, control panel is connected to at least one if not two sources of a pressurised fluid, and provides two outlets to which pressure hoses are ideally connected to allow the pressurised fluid to be delivered to the parts of the apparatus where it is required.

Apparatus 100 further includes a frame indicated generally at 140 capable of rotating relative to the apparatus base 102 and columnar strut 114 thereof by means of swivel anchor 116, which may take any appropriate form. For example, frame 140 may have a spigot welded or bolted to its rear at approximately the vertical mid-point thereof, and said spigot may be rotatably received and retained in a corresponding journal cylinder secured to said mounting plate 116A. Of course, such components may be secured in reverse, that is to say the journal may be provided on the frame, and the spigot may be provided on the mounting plate 116A, but regardless of how the connection between the columnar strut 114 and the frame 140 is achieved, in accordance with the invention the connection must permit the rotation of one relative to the other. Those skilled in the art will appreciate that a wide variety of different types of connection may be possible, and all are considered within the ambit hereof.

As can be appreciated from the Figure, frame 140 in this embodiment is constructed from a pair of generally identical but spaced apart C-shaped steel or aluminium plates 142 of a thickness of the order of 2-6mm and between which are welded or otherwise connected one or more brace components 144,146 which maintain the plates 142 in spaced relationship and also strengthen and rigidify the frame structure generally. Plates 142 include upper flange regions 142A and lower flange regions 142B which together generally define an opening in the frame and which, in use, receives a workpiece (as hereinafter described). To upper flange regions 142A is mounted a resilient rubber compression pad of desired thickness so that the effective height of the frame opening is set at a desired level, i.e. the separation distance between flange portions is capable of being adjusted depending on the height of the workpiece which is to be received therebetween. Pad 148 may of course be made up of multiple separate pads of differing thicknesses in the form of a sandwich if more precise adjustment of the frame opening height is required.

In the lower reaches of the frame 140, between lower flange portions 142B, is securely mounted a simple ratchet jack 150 having a lever connector 152 into which a simple bar or lever (shown in dotted outline extending away from connector 152) may be inserted. Repeated back and forth, up and down motions of such a lever, as indicated generally at 154 cause a ram, again shown only in dotted outline at 158, to travel vertically upwardly in the frame through the jack so that the upper free end of said ram moves into the frame opening and applies a compressive force to whatever workpiece might at the time be disposed between the upper and lower flange portions 142A, 142B. A pressure gauge 160 is in directly fluidly communicates with said jack and provides an immediate indication to an operator of the pressure or compressive force currently being applied thereby. Alternatives to a ratchet jack, such as clamping means, height adjustable screw means and types of ratchet other than the simple ratchet jack specified all fall within the ambit of the invention.

In Figure 2, there is also shown a slip cup 200 in situ within the frame 140 and supported by the upper flat edges of the lower flange portions 142B of plates 142. Although slip cup 200, and the more general workpiece of which it forms part are described in more detail below and with specific reference to Figure 4, it can be seen here that slip cup 200 is provided with a fluid inlet 210 to which an air hose 212 is be attached; although the alternate end of said air hose is shown in the Figure as being stray and unconnected, in use this free end will be connected to one of the outlets of the control panel 120 so pressurised fluid can be supplied directly to the hollow interior of the slip cup 200, as further described hereinafter.

Referring now to Figure 3, apparatus 100 is shown with frame 140 in partially rotated condition, ‘fully rotated' here being considered to be a rotation of the frame through 180° from the position shown in Figure 2, ie. inverted or upside down as compared to that position. Although Figure 3 still shows apparatus 100 without a workpiece in place between the upper and lower flange portions 142A, 142B of plates 142, ram 158, again shown in the figure in dotted outline is shown extending through ratchet jack 150 with an upper free end 158A thereof disposed some way between said upper and lower flange portions 142A, 142B. Those skilled the art will immediately understand that, in use, a workpiece will be clampingly retained by, and compressed between said ram free end 158A and the pad 148, and that the clamping of a workpiece will most ideally be performed while the frame is in the upright condition shown in Figure 2 and in which an operator can most easily operate the jack lever and so ratchet the ram increasingly upwardly to so clamp the workpiece. Once clamped with a desired pressure or compressive force, thereafter the operator can invert the frame manually and simply, and without hindering or obstructing access to the various controls of the control panel 120.

Referring now to Figure 4, there is shown the various components which make up a workpiece indicated generally at 190 and suitable, in assembled form, for use in the apparatus. Most commonly the workpiece 190 consists of two separable hollowed out parts, a first of which is a slip cup 200 and the second of which is a mould 250. Slip cup 200 has an essentially cylindrical body 202 in which a cylindrical cavity 204 is provided into which a slip, slurry or other liquid suspension can be poured, ideally when the slip cup alone is situated in the apparatus as shown in Figure 2. Slip cup 200 is additionally provided with an air inlet 206 in the upper reaches thereof and to which may be connected an air hose (not shown), and by means of which pressurised air or other fluid may be delivered to the cavity 204. In the base of slip cup 200 is provided a recess 208 ideally corresponding in cross-sectional shape to that of the ram free end 158A which can, when the free end 158A of the ram 158 stands proud of the upper flat edges of the lower flange portions 142B of plates 142 by only a small amount (e.g. by an amount equal to the depth of the recess 208), server to correctly locate said slip cup on said lower flange portions and within the apparatus. Said recess 208 also serves, once the workpiece is completed by superposing the mould 250 on of the slip cup and the ram 158 is jacked up so that the workpiece is clamped to some degree between the upper and lower flange portions 142A, 142B of the frame 140, to prevent the slip cup, and thus the workpiece as a whole, from bursting open should the compressive force applied to the workpiece by the ram not be exactly co-axial with the central longitudinal axis thereof. Accordingly, recess 208 performs a very important function in the context of the invention.

As mentioned above with regard to Figure 2, slip cup 200 also includes a fluid inlet 210 by means of which a pressurised fluid, typically air, can be delivered to the interior cavity 204- it is by such means, in combination with the control panel and the various controls thereon, that pressure casting process (as further described below) can be relatively precisely controlled and adjusted. Although air inlet 210 is shown feeding a single interior channel 214 within solid body 202 of slip cup 200, it is possible that multiple air inlets may be provided, and that the single air inlet 210 (or multiple such inlets) might deliver pressurised fluid to the cavity interior through multiple channels provided within said body. However, for simplicity and practicality, most commonly only a single inlet 210 is necessary.

Slip cup 200 is additionally provided with an annular groove or channel 216 in its uppermost annular free end to receive an O-ring gasket or seal 218, which is preferably compressible and resilient (e.g. of rubber), in such a manner than that when in place within said groove 216, there is at least some portion of said seal 218 which stands proud of the surface of the annular free end of said clip cup. By this arrangement, when mould 250 is disposed on top of the annular free end of said slip cup, there is at least some resistance to the sliding relative lateral movement between mould and slip cup before being clamped within the apparatus, which might occur for example if one or other part of the workpiece is accidentally nudged or knocked. Also, of course, after the workpiece is clamped within the apparatus, it is this O-ring gasket which effectively hermetically seals the workpiece interior cavity thus creating a suitable environment for pressurised casting to occur.

Turning now to mould 250, the body 253 of which is again generally cylindrical, a fluid inlet 252 is again provided which, through a channel 254, communicates with an interior mould cavity 256, which in this is instance is shown as conical, but of course may be any desired or required shape, depending on the tests which are to be performed. In use, this inlet 252 will be connected to the second fluid outlet of control panel 120 so that a separately controllable supply of pressurised fluid can be applied to the mould cavity, and most preferably to the exterior surface of an test item (not shown) already having been cast within said mould cavity. Mould 250 will ideally be identical in diameter to the slip cup 200 so that when placed thereon, the two together will form a perfectly cylindrical workpiece. Ideally, and the mouth of the mould cavity 256 will be of an identical diameter to that of the cavity 204 so that the annular free ends of each of slip cup and mould are identical, and the interface therebetween will be most robust when under compression. In the alternative, asymmetrical and multi-part moulds may be utilised. A further alternative might see a single slip pot serving multiple moulds in a single operation of the apparatus 100.

Figures 5, 6 and 7 hereof merely provide different views of the apparatus of Figures 2 and 3. Reference numerals used in Figures 2 and 3 are repeated in Figures 5, 6, and 7 as appropriate and identify respective parts of the apparatus already described above.

As regards the utilisation of the apparatus 100 in a test casting procedure, referring again to Figures 2 and 4, empty slip cup 200 is firstly placed in the apparatus above the jack 150 on upper flat edges of the lower flange portions 142B as shown in Figure 2. A preferably measured quantity slurry or slip material is poured into the slip cup so as to fill it either completely or to a desired level, depending on both the parameters of the test casting procedure to be conducted and/or the size of the cavity 256 within mould 250. Thereafter, mould 250 is placed over and on top of clip cup so that respecting upper and lower annular faces of those components are above one another, the mould being held in place on the slip cup initially by its own weight, which in turn slightly compresses the O-ring gasket 218 disposed in the annular groove 216 of said slip cup. These two parts together are considered to constitute the assembled workpiece.

Correct location of the workpiece within the apparatus is most preferably achieved by jacking the ram 158 upwardly so that it stands proud of the flat edges of the lower flange portions 142B of plates 142 by an amount less than or equal to the depth of the recess 208 provided in the base of said slip cup so that the ram is received therein and the slip cup is thus prevented from moving around laterally on said flange lower portion flat edges. Thereafter, the ram is further jacked upwardly within the apparatus by manual operation of jack 150 so that the workpiece is compressed between the upper and lower flange portions 142A, 142B of the frame 140, or more precisely is compressed into the pad 148 by the upwardly moving free end 158A of the ram. The gauge 160 provides an indication of the instant compression force or pressure applied to the workpiece, and an ideal pressure is of the order of 2 bar.

Once clamped within the apparatus at the desired pressure, the frame 140, and thus the workpiece within it, are manually rotated through 180° so that the workpiece is completely inverted, and the liquid slip formerly occupying the slip cup falls under gravity into the mould cavity and settles therein. Naturally, a most preferred arrangement is that the mould cavity 256 is volumetrically larger than the slip cup cavity 204 so that the slip is entirely emptied into the mould once in inverted condition, and the slip cup cavity 204 is empty. At this stage, one set (122,124) of controls of the control panel 120 is actuated to deliver a supply of pressurised air to the empty slip cup cavity through inlet 210. Thus commences the pressure casting process. In the case of casting ceramic sanitary ware, a fluid pressure of between 3-12 bar is created inside the slip cup and mould cavities 204, 256 above the liquid slip material now occupying the mould. Most preferably, an initial air pressure of 4bar is maintained for a short period of time, e.g. 1-2 minutes, and thereafter the air pressure is increased to 10bar for the remaining period of the pressure casting process, typically for a further 2-5 minutes. Pressure levels and periods will differ, dependent on use cases. This completes the pressure casting process, after which the air supply to the slip cup inlet 210 is closed off, and/or disconnected. The operator then re-inverts the frame and the workpiece within it so that any remaining liquid slip material inside the cavity falls under gravity back into the slip cup, and after releasing the ratchet, ideally gradually, at that time holding the ram in its workpiece-compressing position, the workpiece is no longer compressed and clamped within the apparatus, so the mould can be easily lifted from the workpiece with the item cast inside the cavity thereof still retained therein by virtue the adhesion of the still moist cast solid to the mould cavity wall(s). In order that the cast item can be uniformly and simply released from inside the mould, a source of pressurised air is delivered from the control panel of the apparatus through inlet 252 to the mould cavity 256, and the flow of air between the cavity wall and the cast item adjacent thereto causes the two to separate, and the cast item can then simply drop under gravity from the cavity. Thereafter, the cast item can be inspected, and if necessary cut in half or otherwise testing for both performance of the casting process, and for specific physical characteristics of the cast item itself.

Henceforth, the apparatus of the invention provides a facility for producing drain cast (hollow cast) pieces in a laboratory setting using relatively compact and simple equipment. This in turn allows for assessments to be made of smaller sample sizes (cast pieces) of Theologically challenging suspensions. By comparison factory scale apparatus would require complex pumping and pipework to fill and drain slip (suspensions) to and from moulds to allow for the production of hollow cast pieces. Also, the apparatus described includes various gauges so that major casting process parameters can be easily controlled and adjusted. A yet further advantage is that varying mould sizes can be accommodated in the apparatus by virtue of either the simplicity with which pad 148 can be changed or adjusted in thickness by adding further thinner pads to a required thickness. The mechanical clamping provided by the ram (in certain embodiments, this may be hydraulic) allows high clamping pressure to be easily and quickly applied (circa 10 tonnes of force) thus allowing for casting pressures of up to potentially 40bar.

In summary therefore, a portable casting apparatus is described comprising a base and a column towards the rear thereof and extending upwardly therefrom, said apparatus further comprising a frame comprising at least upper and lower flange portions which together define an opening, and an interconnecting web portion disposed behind the opening and by means of which said upper and lower flange portions are connected. The interconnecting web portion of the frame is pivotally mounted to the column of the base of the apparatus, ideally at the mid-point, so that a clearance exists between said base and said frame lower flange portions when the frame is in a first position, and also between the base and the upper flange portions when the frame is rotated through 180°. The apparatus additionally includes jacking means that are mounted to one of said frame upper and lower flange portions such that the direction of travel of a ram of said jacking means is directly towards the opposing flange portion of the frame so that, in use, a workpiece may be both clampingly retained within said frame between a free end of said ram and the opposing frame flange portion, and rotated as a result of the rotation of the frame within which it is clamped. In a most preferred embodiment, the workpiece comprises two separable generally cylindrical parts, one being a slip cup into which a slurry, slip or other castable liquid suspension may be poured, and the other being a mould including a mould cavity into which that castable liquid may fall from the slip cup when the workpiece is in assembled condition and clampingly retained within the frame of the apparatus as it is rotated from a first position in which the mould is disposed above the slip cup to a second position in which the mould is disposed beneath the slip cup.

Claims

1. A portable casting apparatus comprising a base and a column towards the rear thereof and extending upwardly therefrom, said apparatus further comprising a frame comprising at least upper and lower flange portions which together define an opening, and an interconnecting web portion disposed behind the opening and by means of which said upper and lower flange portions are connected, said interconnecting web portion of said frame being mounted to said column so that a clearance exists between said base and said frame lower flange portion, characterised in that jacking means are mounted to one of said frame upper and lower flange portions such that the direction of travel of a ram of said jacking means is directly towards the opposing flange portion so that, in use, a workpiece may be clampingly retained within said frame between a free end of said ram and the opposing frame flange portion, and further characterised in that the mounting between said interconnecting web portion and said column permits relative rotation therebetween to allow the entire frame to be rotated while a workpiece is clampingly retained therein.

2. Apparatus according to claim 1 wherein the interconnecting web portion of the frame is mounted to the column of the apparatus in the region of the mid-point of said web portion such that the frame can be rotated completely without the base interfering with the upper or lower flange portions of the frame, as the case may be.

3. Apparatus according to any preceding claim wherein the jacking means is mounted in the lower flange portion of the frame, and the upper flange portion thereof is provided with a resilient pad and against which one end of the workpiece reacts when clampingly retained within the frame by means of the clamping force applied to the alternate end of the workpiece by the ram of said jacking means.

4. Apparatus according to any preceding claim wherein the jacking means is a manually operated ratchet jack

5. Apparatus according to any preceding claim wherein the jacking means is fluidly connected to a pressure measurement gauge affixed to the frame which indicates the instant clamping pressure being applied by said jacking means.

6. Apparatus according to any preceding claim wherein the mount permitting the rotation of the frame relative to the column of the apparatus frictionally resists such rotation to an extent which is capable of being overcome by human force.

7. Apparatus according to any preceding claim wherein the mount permitting the rotation of the frame relative to the column of the apparatus is one of: indexed, and indexable.

8. Apparatus according to any preceding claim wherein the workpiece is provided with a recess a base thereof and which is of a shape and size which corresponds to the shape and size of the free end of the ram of the jacking means which, in used, is received in said recess.

9. Apparatus according to claim 8 wherein the cross-sectional shape of the free and of the ram and the recess are non-circular.

10. Apparatus according to any preceding claim wherein the lower flange portion of the frame provides one or more seating surfaces on one or both sides of the jacking means which freely support said workpiece in upright condition above said jacking means.

11. Apparatus according to any preceding claim wherein the frame is C-shaped.

12. Apparatus according to claim 11 wherein the frame comprises two spaced-apart C-shaped plates secured to one another by means of one or more cross-members.

13. Apparatus according to claim 12 wherein the jacking means is mounted between adjacent lower flange portions of respective C-shaped plates.

14. Apparatus according to any preceding claim wherein the apparatus comprises a control panel by means of which the supply of pressurised air is initiated, adjusted and terminated.

15. Apparatus according to claim 14 wherein the control panel includes at least two outputs to which air hoses may be attached, and through which pressurised air may be supplied at different pressures.

16. Apparatus according to any preceding claim wherein the workpiece comprises two separable hollow parts each having a closed end, the external surface of which forms the base of that part, and an open end, one being a slip cup and the other being a mould.

17. Apparatus according to claim 16 wherein the slip cup and the mould are of identical cross-sectional shape and size, and have a wall thickness at their open ends which is also identical.

18. Apparatus according to either claim 16 or 17 wherein said slip cup and mould open ends are essentially annular in cross-section.

19. Apparatus according to claim 18 wherein at least one of the slip cup and mould open ends is provided with an annular channel in which is disposed an O-ring gasket and which, when in place, stands proud of the otherwise planar annular surface of the open end of that part.

20. Apparatus according to claim 16 or any claim dependent thereon wherein one or both of the separable parts of the workpiece are provided with one or more air inlets.