A MOULD
The present invention relates to moulds.
It is known that flat or single curved or compound curved panels can be manufactured by a number of methods including: (a) thermoforming which is the process of deforming an organic sheet material which is rendered plastic or malleable, generally with heat, onto a rigid mould employing vacuum or pressure. On cooling the sheet retains the geometry of the mould; and (b) casting which is the process of introducing organic or inorganic materials into an open or closed (cavity) mould. The material being of a viscosity low enough to be a pourable. Upon curing (by chemical reaction, thermal reduction or other solidifying process or hardening) the cast retains the geometry of the mould.
The existing process of manufacturing thermoformed parts or cast parts requires that a mould (tool, pattern or equipment) is fabricated to conform to the positive or negative geometry of the desired finished part. These moulds may be fabricated from sheet materials such as laminated wood. The resulting moulds are generally rigid and dedicated to reproducing the geometry upon which they are built. It should be readily recognised that the existing technology requires that each new geometry (shape or form) will cause a new mould to be fabricated. Moulds are expensive and any large scale composition of a multiplicity of geometries will be both expensive to fabricate and time consuming.
It is known that thermoformings or castings of the type described may be employed on architectural and civil engineering structures to provide decorative or weather proofing surfaces (also known as cladding, facades or weather shields). The applications include swimming pools, fountains, skate board and bike arena, shelters, sun shelters, roof lights, etc.
The present invention provides a mould comprising: a plurality of pad members forming a pad member array; and at least one actuator for moving said pad members which are rotatable about orthogonal axes perpendicular to the direction of movement such that together the pad members form an overall desired negative shape of a surface of an article to be moulded.
The present invention further provides a mould apparatus comprising: a plurality of pad members forming a pad member array, each pad member being rotatably mounted on the end of a pin; and at least one actuator detachably connectable to said pins for translating the pins along the respective axis of the pin such that a shape of a mould surface is defined.
The advantages of the present invention is that the same mould may be used in the fabrication of members with different shapes.
The present invention will be described by way of example only with reference to the following drawings in which:
Figure 1 shows a casting embodiment of the present invention for casting slabs with a rectangular cross-section;
Figure 2 illustrates, in cross-section, a mould of the present invention used for producing a slab with major surfaces having a convex shape;
Figures 3 and 4 illustrate two examples of shaped slabs being manufactured with one convex major surface and one concave major surface; Figure 5 illustrates an actuator, pad and moulding surface of the present invention;
Figure 6 illustrates in plane the pad of Figure 5;
Figures 7 and 8 illustrate the arrangement of Figures 5 and 6 in use;
Figure 9 illustrates a pad array;
Figure 10 illustrates different three-dimensional configurations of pads; Figure 1 1 shows in cross-section a separable mould assembly (B) and ram assembly (A);
Figure 12 shows in step 1 a pair of ram assemblies configuring a pair of mould assemblies and moving to configure a second pair of mould assemblies in step 2;
Figure 13 shows in step 1 a pair of partial ram assemblies indexing down a pair of mould assemblies before moving to configure a second pair of mould assemblies in step 2;
Figure 14 shows in step 1 a pair of partial ram assemblies indexing down and across a pair of mould assemblies before moving to configure a second pair of mould assemblies in step 2;
Figure 15 shows in step 1 a pair of ram assemblies configuring a pair of mould assemblies. Step 2 shows the ram assembly disconnected from the mould assembly and the introduction of a casting material C introduced into the cavity tool. Step 3 shows the finished casting;
Figure 16 shows a ram assembly progressing along a line of moulds and stopping at each mould to set the shape of the mould before moving onto the next mould in line; Figure 17 shows how a single ram assembly can set both sides of a cavity mould using a rotating (and optionally translatable) pad table; and
Figure 18 shows schematically how a pad is rotatably mounted at the end of a pin.
This invention proposes a machine which enables the manufacture of single curved and compound curved panels by providing an open mould or a cavity mould of variable geometry.
The present invention relates to thermoformings or castings of the type described and may be employed on architectural (cladding) and civil engineering structures to provide decorative or weather proofing surfaces (also known as cladding, facades or
weather shields). The applications include swimming pools, fountains, skateboard and bike arena, shelters, sun shelters, roof lights, etc. Tools for other manufacturing tooling may be thermoformed (e.g. to make a cast for concrete). Glass may be formed by heating it in a kiln and letting it slump over a mould of the invention or over a mould made using a mould of the invention.
A machine with a variable geometry mould surface suitable for the manufacture of single curved and compound curved parts is proposed. It is proposed that the machine has two embodiments albeit employing the same engineering and software principals (i) for thermoformed parts and (ii) for cast parts. The mould is capable of being used to mould articles with overall different shapes and not just minor different surface patterns.
The machines of both embodiments preferably comprise five parts. 1. A mould surface 10. For thermoformed parts only one mould surface is envisaged though more could be used. For cast parts two mould surfaces and a side wall
Insert 20 is envisaged but other arrangements are possible. 2. Pads 30.
3. at least one, preferably a plurality of rams or actuators 40.
4. A Machine Housing.
5. Machine Operating Software. The Operating Method
The mould surface 10 of the machine is supported by an array of pads 30 each of which is attached to a ram 40. The mould surface 10, comprising an elastic membrane, is deformed by the variable extension of the rams 40 of the array such that the pads 30 form a continuous or discontinuous pixilated surface in accordance with the geometry required and controlled either manually or by the Machine Operating Software. Once the required geometry of the pads 30 has been achieved, the set-up phase, the rams 40 are locked to provide a rigid structure under the mould surface 10 for the duration of the manufacturing cycle. In the case of thermoformed (or vacuum formed) parts the machine is configured with one mould surface to form an open mould or pattern and one pad and ram array. Single open moulds may be used for casting or spraying organic (for example a polymer resin) or inorganic compounds (for example a cementateous preparation, for example concrete, glass reinforced concrete/cement, organic fibre reinforced concrete/cement or metal fibre reinforced concrete/cement) or any combination thereof.
A single open mould which has had an organic or inorganic material sprayed onto the surface may be subsequently closed to form a cavity mould by the application of a second mould prior to a second material being injected or poured into the cavity thus created. This provides for a bi-material casting.
A single open mould which has had an organic or inorganic material sprayed onto the surface may be subsequently closed by the application of a second mould which is
configured to press the exposed surface of the sprayed material, of the first mould. This action may be used to equalise irregularities in the exposed sprayed surface or impart a smooth finish or impart a textured surface finish or other three-dimensional surface feature/graphic while the material remains plastic. In the case of casting the machine is configured with two mould surfaces, at least one of which is malleable and has associated pads and actuators in an array. Preferably there are two malleable mould surfaces and two pad and ram arrays. The thermoforming and casting materials and handling conditions are identical to those of the existing manufacturing methods using existing moulds. After each geometry has been thermoformed or cast the mould surface may be unlocked and reconfigured to create a new geometry without any part of the machine being discarded.
In the casting embodiment the distance between the two mould surfaces may be constant resulting in a casting of uniform thickness (Figs. 3 and 4) or the distance between the mould surfaces may be irregular (Fig. 2) resulting in a casting of variable thickness. The mould surfaces do not need to conform to the same shape. Only one of the surfaces needs to be malleable, the other surfaces(s) can be comprised of stiff members (e.g. an existing structure). The mould cavity or press then being defined between a malleable mould and the stiff members. The distance between the two mould surfaces is preferably in the range 0.1mm to 25m, more preferably lmm to 10m. The combined ram and mould assembly may be orientated at any angle e.g. so that the mould surface is verticle or horizontal or somewhere in between.
The Mould Surface
The A surface of the surface mould 10 forms the surface from which the thermoformings or castings take their form. The B surface of the surface mould is in contact with the pads 30.
It is preferred that the surface mould is uniformly elastic in the x, y and z axis. It may also desirable that the surface mould is not uniformly elastic in the x, y and z axis.
The mould surface may be of, but not exclusively, a continuous organic polymer sheet, a composition of woven organic polymer strips, a woven fabric of organic polymer, a composite of sheet and woven fabric, an organic elastic fabric with an elastic organic coating, a composition of woven metal strips or wires, or any combination of the same.
The surface mould may have a smooth surface finish or a textured surface finish which may be representative of, for example, wood grain, riven stone, leather or an abstract pattern, graphic or texture. The qualities of surface finish may be imparted to the face side of a thermoforming and one side or both sides of a casting.
The surface mould may be covered by a secondary layer or film which has surface finish imparting qualities. This secondary layer may be discarded on completion of each
production cycle.
Referring now to Figure 5, in the casting embodiment the A surface of the surface mould may be subjected to positive atmospheric pressure, once the cavity is closed, during the set-up phase to ensure that the B surface engages with the pads. The B surface of the surface mould may alternatively be subject to vacuum to achieve the same result. It may be desirable to use both methods simultaneously. When engaged the vacuum facility on the pads, suction pads, may be employed to hold the pads firmly against the B surface of the surface mould. This scheme is particularly useful for when convex internal shapes are required (i.e. when actuator rams 40 are pulling at the material of the mould surface). The mould surface may be used as an offset printing blanket. While at rest, i.e. in a flat configuration, the mould surface, now a mould blanket may have ink applied to it, for example by hand brushing, screen printing, spraying or stencilling etc. The mould is then configured by the ram (as described elsewhere) and the inked surface is brought into contact with the surface of a receiving material which may have the negative geometry of the mould. By this method surfaces of variable geometry may be printed.
The Pads
The pad 30 array may comprise any number of individual pads. The pads may be of any size and shape. All the pads in an array may not be uniform in size. The number and size of the pads is related to the overall size of the desired thermoforming or cast part and the degree of surface smoothness required. It will be appreciated that a large number of small pads will more easily approximate a continuous curved geometry than a small number of large pads. However, the faceting resulting from the latter may for a given application be nevertheless, desirable. The pads may be of any two dimensional geometry, for example, a square, a triangle, a polygon, a hexagon, a pentagram or a disk. Shapes which tesselate are preferred. The pads may be an open ring (outline) of any of the previous geometric forms. The pads may also be three dimensional in form, for example, a hemisphere or part thereof, a cone, a conical prism, a domed triangle, a domed cone etc. as shown in Figure 10. The pads may be of a rigid or a flexible material.
The pads may have openings (perforations) through the face side to accommodate pressurised air or vacuum to be directed to the B surface of the mould surface as described above. Pressurised air may be used to facilitate ejection of the thermoforming or cast from the machine while vacuum may be used to engage (bond, adhere) the pad with the mould surface.
The pads may rotate in two axes about the end of the rams. The purpose of this rotation is to allow the pad to conform to the angle of curvature of the surface mould corresponding to the location of that individual pad.
The individual pads are connected to the end of each corresponding ram by means of an articulated mechanical or electro/mechanical connection 70 which may, for example, take the form of a ball and socket joint, a hinge, a flexible shaft or rod, a spring or a flexible sub-structure of the pad design.
The Rams
The individual pads are each fixed to a ram. The function of the ram is to enable the pad to be extended to a given position along the axis of the ram in accordance with the desired geometry. The ram or actuator may be, for example, a manually or electro/mechanically rotated screw thread, a electro/hydraulic piston, an electrical or magnetic actuator, a linear electro/mechanical step motor or a combination of the above.
It is preferred that in the electro/mechanical or electro/hydraulic embodiment the rams of the machine are controlled by Machine Operating Software.
It is desirable that the rams are capable of being locked in the desired geometric configuration for a period consistent with the cycle time of the part manufacture or any other time as required. It is desirable that the locked mode is un-effected by system, power or computer failure.
The Machine Housing The Machine Housing contains all the working parts, the pads, the rams and all the associated electro/mechanical parts of the machine. In one embodiment of the invention the five sides of the Machine Housing with one surface mould forming the sixth side constitutes an airtight container. This arrangement may be used for Thermoforming. A vacuum or partial vacuum may be put on the Machine Housing drawing the surface mould firmly onto the pads. This arrangement is also useful in preventing foreign bodies, dirt and dust etc from entering the working parts of the machine. In another embodiment of the invention the air tight seal is located at the ram shaft between the ram chambers and the pads. This provides the machine with foreign body, dirt and dust protection while giving the rams a greater degree of extension. In the case of thermoforming, one machine housing is required and replaces a conventional (existing technology) mould in a thermoforming machine.
In the case of casting, two machine housings are required and replace a conventional (existing technology) cavity mould.
The Machine Operating Software
Large scale architectural or civil engineering compositions of a multiplicity of surface geometries are generally created in a computer aided design (CAD) digital environment employing existing (branded) 3D surface modelling software packages.
Manufacture of the geometry may take two steps. Step 1, existing software may break down the desired surface geometry into components or sub-units or parts of manufacturable size. Step 2, existing software may take each individual part and produce shop drawings to facilitate the fabrication of the desired mould from which the part would be thermoformed or cast.
The software of the invention would take the three dimensional data produced at Stage 1 and convert it directly into digital instruction to configure the rams of the invention into the desired geometry.
The machine described may also be characterised as being in two parts, a ram assembly (a) and a mould assembly (b) illustrated in Figure 11. The ram assembly (a) comprises a structural frame 170 to which the rams are attached, with associated indexing devices, actuators, and control equipment. The function of the ram is to configure the mould assembly. The ram assembly is independent of the mould assembly.
The mould assembly (b) comprises a structural frame 70 to which Pins 60 are attached to pads 30 described above but not illustrated in Figure 11, lock-off devices 65 which lock the pins in place relative to the frame when the rams are disconnected and the mould surface 10, an elastic membrane as described above. The pins 60 of the mould assembly align with the corresponding actuators 40 of the ram assembly. The function of the mould assembly is to retain the configuration created by the actuators for the duration of the manufacturing process, or longer if desired.
The mould assembly including the pad array, mould surface, associated lock-offs, pneumatic and air supply and control equipment, may be independent from the ram assembly. This embodiment suggests that (a) and (b) may be brought together in such a way that the respective rams and the pins, of the mould assembly, align and are temporarily connected. The rams of (a) configure the pins of (b) upon which the pins are locked off and the assemblies disconnect from each other. The lock-off devices are similar to hydraulic breaks of lorries which lock off where there is no hydraulic power and open up under hydraulic power i.e. they are biased towards the locked off position and must be actuated to allow the rams to move the pins. This enables a single ram assembly (a) to configure an unlimited number of mould assemblies (b) and optimises the use of the relatively expensive ram assembly.
The ram assembly may have the same number of actuators as the mould assembly has pins. It is also possible that the ram assembly may have one actuator or a single row or part of a row of actuators or multiple rows of actuators. In this case the actuators configure a single pin or row of pins respectively, in sequence. This reduces the number of expensive rams required.
In the embodiment of a pair of mould assemblies (to form cavity moulds or presses) there may be a pair of ram assemblies configuring their respective mould assemblies
synchronously.
The pad array may be a single row of pads of any number or a multiple row of pads of any number. For example, the assembly may comprise 10 pairs of ram and pad assembly laid out in a line eg. ::::::::
A corresponding set may be placed in a mirrored arrangement, creating a configurable vice.
This arrangement has the advantage that one or two expensive ram(s) assembly can service more than one mould. This is especially useful bearing in mind that a moulding or casting may take several hours to cure which would otherwise result in an unacceptable downtime of the expensive ram array.
Figure 12 shows ram assemblies (a) moving independently from one set of mould assemblies to a second set of mould assemblies. Figure 16 shows the same except that only one mould is present to form an open mould. Figure 13 shows the ram assembly (a) as independent of the mould assembly (b) and only aligning with a proportion of the row of pins of the mould assembly at any one time. The ram assembly indexes down (or up) the mould assembly, eventually covering all the pins, d is an example of the direction of the indexing of the ram assembly across the pins of the mould assembly. The indexing directions may also be left to right, right to left, bottom to top, top to bottom or diagonal or random.
Figure 14 is the same as Figure 13 except the ram assembly is smaller than the mould pin assembly and requires indexing across the mould assembly as well as up as down.
Figure 15 shows material c being cast once the ram assembly has formed two mould assemblies and has been moved away.
The Mould/Ram Connection.
The mould assembly may be connected to the ram assembly as required to enable the ram assembly to configure the pad & mould assembly to the required geometry. The connection 80 between the shafts of the mould assembly and the ram assembly may be a mechanical or electromechanical or a magnetic connection or another type of connection such that the connection is sufficient to transmit the force of the ram assembly to the mould assembly in both directions along the axis of the ram to complete the configuration procedure without premature detachment, but may be detached when required.
Configuring the mould assemblies
In a production/manufacturing environment it may be desirable for the ram
assembly to remain in one place while the moulds are brought in alignment with it, or visa versa.
In one case the moulds may form a chain. There may be 'stations' through which the chain passes in order to perform the separate functions required of the thermo forming, spraying, printing or casting processes. At one of the stations the ram and the mould assemblies connect, configure and disconnect.
In another case the moulds are mounted in pairs on a turn-table. The turn-table may rotate in a fixed position or rotate and move linearly, for example along a track. In either case the turn-table rotates to bring each mould assembly in alignment with the ram upon which the ram and the mould connect, configure and disconnect. This requires only one ram assay and is illustrated in Figure 17.
The mould assembly may, after being configured by the ram in a vertical orientation, be rotated into a horizontal orientation, or visa versa. In the separate mould/ram assembly embodiment, either the moulds may be moved to the ram assembly or assemblies or the ram assembly or assemblies may be moved to the moulds or a combination of both. The moulds may be moved after being adjusted by the rams either before or after being filled.
The actuators 40 may act directly on the pads 30 in the separate mould/ram array embodiment and the lock off means may act between adjacent pads to hold the mould surface in the desired shape.
As the skilled person would understand from the foregoing the above described mould could also work in the absence of the surface mould 10 such that it is the surface of each of the pads of the array of pads 30 which face away from the actuator 40 which form together the mould surface against which the article is moulded. Particularly in thermoforming applications, the presence of gaps between the individual pads is not a problem as the item which is being thermoformed maintains enough stiffness during the forming process to hold it together and prevent it from flowing through the gaps between the pads.
In casting applications it may be necessary to provide some kind of webbing between pads or to use a film which covers the pads which may or may not be reusable and which may or may not be part of the mould. In this way the outer surface of the pads define the mould surface. The fact that the pads are hinged at the end of the pins as described above means that the pads will move to a orientation at the end of their respective pins so that each individual pad takes of a mean position in the mould surface such that the mould surface which is defined by the plurality of pads is smooth. The relative rotation of the pads to the pins takes place either under the weight of the mould material and/or the under pressure which is applied to the area of the other side of the pads to the material being formed.
Figure 18 shows schematically how a pad is rotatably mounted at the end of a pin. The hinge is preferably designed such that the point around which the pad can pivot is on the outer surface of the pad i.e. on the surface of the pad which defines part of the mould surface. Thus, the pad can rotate about two orthogonal axes which are perpendicular to the axis of the pin to which the pad is attached. In this way the position of the centre point of the surface of the pad forming the mould surface can be determined by the position of the pin regardless of the degree of rotation of the pad because the distance x between the bottom of the pin and the centre point of the surface of the pad forming the mould surface is constant as is illustrated in Figure 18. This applies to all embodiments. In one embodiment the pins have a screw thread formed on their outside and they pass through nuts which are attached to or are part of the frame 70. Adjustment of the position of the pads is simply done by rotating the pins until the pad is in the desired position. In this embodiment it may not be necessary to use a lock off device 65 because the friction between the screw thread on the pin and the nut is enough to ensure that there is no movement of the pin 60 relative to the frame 70 during the moulding process.
In the embodiment in which the mould surface 10 is not present and the pads form the mould surface all of the above described methods and arrangements are possible including the situation where the mould is comprised of pads and pins and a frame and the actuator array is releasably attachable to the mould in order to set the position of the pins. The feature of the pads having the ability to suck the mould surface 10 towards them can be maintained in the embodiment without the mould surface 10 and this is particularly advantageous if a film as described above for sealing the gaps between the pads is employed.