A method of forming a semi dry cast stone product

Abstract

A method of forming a semi dry cast stone product using a robotic system comprises using a manipulator (44) of the robotic system to move a compaction tool (42) between a first set of positions relative to a mould (16), wherein at each position of the first set of positions the compaction end (46) is extended so as to compact a portion of the semi dry stone mix is in the mould (16), and then retracted. The method further comprises adding additional semi dry stone mix into the mould (16) on top of the compacted portions. The method further comprises using a manipulator (44) to move a compaction tool (42) between a second set of positions relative to the mould (16), wherein at each position of the second set of positions the compaction end (46) is extended so as to compact a portion of the semi dry stone mix is in the mould (16), and then retracted.

Description

A METHOD OF FORMING A SEMI DRY CAST STONE PRODUCTBACKGROUND OF THE INVENTION

[0001] The present disclosure relates to the field of semi dry cast stone products, such as may be used in the construction industry. It relates particularly, but not exclusively, to a method of forming a semi dry cast stone product using a robot, a robotic semi dry cast stone moulding machine, a semi dry cast stone product, and a building.

[0002] Semi dry cast stone products are widely used in the construction industry. They see particular use in house building, largely for decorative rather than structural components. These products are moulded from semi dry stone mix - a mixture of sand, lime and cement, along with pigment and / or waterproofing additives as needed. In different technical fields such as wet cast stone and precast concrete, the mix is liquid or semi-liquid and can simply be poured into a mould and left to set. In some cases the mould may be vibrated during / after pouring so as to release air bubbles in the concrete before it sets, particularly in the case of “dry cast” or “low-slump” concrete which has a lower water content and thus has a thicker consistency during pouring. In the case of semi dry cast stone, however, the mix (which resembles damp sand in consistency, thus cannot effectively be poured and is largely unaffected by vibration) must be compacted into the mould to avoid the formation of voids which can affect structural integrity and / or surface finish.

[0003] Due to the need for proper compaction, the production process of semi dry cast stone products is not well suited to automation. It therefore remains a fully manual process, with skilled craftsmen producing pieces individually by hand.

[0004] To produce a semi dry cast stone product, a mould of the requisite size is produced, often being formed out of wooden boards clamped together to form a cavity. The cavity is often cuboidal in shape (for instance where the product is intended for use as a window lintel or the like), but in some cases the cavity may be curved (for instance where the product forms part of an ornamental or structural arch) or may have any other shape according to the intended use of the product.

[0005] Craftsmen then fill the cavity in the mould with semi dry stone mix and compact it to ensure that any voids are eliminated. They then trowel off any excess mix from the topof the mould, turn the mould out onto a support and disassemble the mould to leave the compacted semi dry stone mix on the support. They then clean up any surface defects which may have resulted from removal of the mould, before curing the compacted mix (e.g. in a steam chamber) to form the finished product.

[0006] Although production of semi dry cast stone products by hand allows very exacting quality standards to be met, the reliance on manual labour has several downsides. In particular, semi dry stone mix is heavy, as are the tools usually used to compact the mix in the mould, therefore repeated manual handling of the mix and the compacting tools therefore requires craftsmen to use a lot of strength. The act of compacting the mix also requires significant strength. These strength requirements not only require craftsmen to be heavily built in order to sustain the work for any length of time, but also mean that there is a risk of injury. These factors affect the numbers of people who are suited to, or willing to, perform this work. The industry therefore struggles to maintain an active workforce of sufficient size to achieve the required levels of throughput.

[0007] The manual nature of the work also makes it quite slow in comparison to other fields such as wet cast stone and precast concrete where automation can be used more effectively. Compounding this is the physically demanding nature of the work, which requires frequent breaks to be taken. The low speed of production of semi dry cast stone products negatively affects lead times and production costs.

[0008] The present invention seeks to mitigate one or more of the above-mentioned disadvantages. Alternatively or additionally, the present invention seeks to provide an improved or alternative method, machine, product, building, system, kit of parts, computer program or set of moulded structures.SUMMARY OF THE INVENTION

[0009] According to a first aspect of the present invention there is provided a method of forming a semi dry cast stone product using a robotic system to perform one or more actions on semi dry stone mix in a mould for forming the product. The robotic system comprises one or more compaction tools each having a compaction end which is extendable and retractable along a compaction direction (for example relative to a mounting portion of thecompaction tool). The robotic system comprises one or more manipulators, for example in the form of a multi -axis (e.g. at least 4-axis, preferably 5 -axis, and optionally 6-axis arm) robotic arm for moving said compaction tool(s) relative to a mould. The movement of the robotic arm may be controlled by multiple servo motors. Said one or more of the one or more compaction tools may be configured for being attached to (and removed from) a mounting portion of a manipulator. Additionally or alternatively, a manipulator may be configured to select the use of one tool from multiple tools available to it. It may be that in some embodiments said one or more compaction tools are each provided as a part of the manipulator, and not removed or disconnected during normal use.

[0010] The method comprises using a manipulator to move a compaction tool between a first set of positions relative to the mould, wherein at each position of the first set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted. The positions of the first set of positions may include multiple (two or more, optionally four or more and possibly at least six positions all spaced apart from each other when view from above - i.e. horizontally spaced apart).

[0011] The compaction tool end may be extended by the robotic system by firing it (for example using a pneumatic control system) along a linear path at speed at the mould, such that at the point of impact with the mix in the mould the tool is travelling at a speed of at least 1 ms'1, preferably at least 2ms'1.

[0012] The compaction end may move relative to other parts of the tool, such as the mounting portion.

[0013] The stroke length of the compaction end (the distance travelled from the retracted to the extended position of the compaction end) may be at least 100mm, for example in order to enable the compaction end to accelerate to the required speed at the point of impact.

[0014] At each position of the first set of positions the compaction end may be extended and then retracted multiple times before the tool is moved to the next position. The time taken between successive impacts of the compaction end with the mix while the manipulator holds the compaction tool at a single position of the first set of positions may be at least 100ms, possibly at least 300ms, and optionally at least 500ms. A certain amount of time is required to enable the compaction end to be retracted before being extended again. The successive impacts of the compaction end are preferably reasonably rapid toallow fast throughput - thus, the time between successive impacts of the compaction end may be less than 2 seconds, and is preferably about once a second or faster.

[0015] The compaction end may have a forward facing surface for impacting on the mix that has a surface area that may be at least 0.005m2but preferably less than 0.15m2. Compaction of the mix may be performed in multiple different stages. There may be a stage of bulk compaction, performed with a heavier compaction end with the path of travel of the compaction end being generally vertical. There may be multiple (for example at least two) stages of bulk compaction, a first stage performed that results in the mould being partially filled, and a later stage following a step of adding additional semi dry stone mix into the mould on top of the previously compacted mix. A manipulator (for example the same manipulator as used to move the compaction tool between the first set of positions) may then move a compaction tool (for example the same compaction tool) between a second set of positions relative to the mould, wherein at each position of the second set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted (for example in a similar manner to that performed when the compaction tool is moved between the first set of positions).

[0016] One of the stages of compaction of the mix may include corner compaction. A different compaction tool and / or compaction end may be used for corner compaction than is used for bulk compaction. The robotic system may be configured to perform corner compaction by firing a corner compaction end (for example using a pneumatic control system) along a linear path at speed at the mould, such that at the point of impact with the mix in the mould the tool is travelling at a speed of at least 1 ms'1, preferably at least 2ms' or at least 4ms'1, and possibly faster than a bulk compaction end of a bulk compaction tool. The corner compaction end may have a mass that is less than half the mass of the bulk compaction end. The corner compaction end may have a mass that is at least 0.1kg, preferably at least 0.25kg and possibly 0.4kg or more. The momentum of the corner compaction end at the point of impact may be at least Ikgms'1, possibly 5kgms or more. The stroke length of the corner compaction end may be similar to the bulk compaction end. It may be at least 100mm. Corner compaction may be performed by the manipulator moving the corner compaction tool to a position and angling it towards a corner of the mould (e.g. a bottom corner), then extending and then retracting the corner compaction endmultiple times before the manipulator moves to a different position. The path of travel of the corner compaction tool may be at an angle (e.g. of at least 10 degrees, preferably more than 20 degrees) to the vertical.

[0017] During the compaction of the mix in the mould by the mould may be supported by (and for example held in position by) a mould support, for example a table.

[0018] The method includes a step of removing the compacted semi dry stone mix from the mould and then curing it to form a solid product.

[0019] As mentioned above, the manipulator used in the method may comprise a multiaxis robot arm controlled by two or more servomotors. The method may include firing the compaction end of the compaction tool towards the mix in the mould in a way that shields the manipulator from the forces that would otherwise be sustained as a result of the rate of change of momentum of the compaction end during / after impact. For example the compaction end and the manipulator may be decoupled at the point of impact with the mix in the mould so as to reduce transmission of forces or shocks from the compaction end to the manipulator.

[0020] The compaction end may be fired pneumatically, for instance using a pneumatic cylinder, in which case the compaction end and the manipulator may be decoupled by venting pressurised air responsible for firing the compaction end (e.g. through a vent valve). As an alternative the compaction end may be fired electromechanically, for instance using a solenoid, in which case the compaction end and the manipulator may be decoupled by blocking electrical current responsible for firing the compaction end (for instance using a switch).

[0021] Reference herein to a compaction end being “fired” or “thrown” is intended to denote that the compaction action provided by the compaction end primarily utilises momentum, rather than the steady application of force. In other words, a compaction end which is “fired” or “thrown” functions as a hammer rather than a jack / press. Put another way, a “fired” or “thrown” compaction end provides an impact rather than a push.

[0022] Thus in an embodiment of the present invention there is provided a method of forming a semi dry cast stone product using a robotic system that acts on a mould containing semi dry stone mix, the robotic system comprising one or more compaction tools each having a compaction end and one or more multi-axis robot arms controlled bytwo or more servomotors for moving said compaction tool(s) relative to a mould, wherein the method comprises using the robot arm to move the compaction tool between a set of different positions relative to a mould, at each position firing a compaction end of the compaction tool towards the mix in the mould with the compaction end and the manipulator being decoupled at the point of impact with the mix so as to reduce transmission of forces or shocks from the compaction end to the manipulator.

[0023] For the avoidance of doubt, reference to the compaction end and the manipulator being decoupled at the point of impact refers to the fact that the compaction end and the manipulator are in a state of being decoupled when impact occurs. The act of decoupling may take place before or at the point of impact.

[0024] The compaction end may be extended by the robotic system by firing it (for example using a pneumatic control system) along a linear path at speed at the mould, such that at the point of impact with the mix in the mould the compaction end is travelling at a speed of at least 1 ms'1, preferably at least 2ms'1. The compaction end may have a mass of at least 1kg, preferably at least 2.5kg and possibly 4kg or more. The momentum of the compaction end at the point of impact may be at least 5kgms-1, possibly 1 Okgms'1or more. The stroke length of the compaction end (the distance travelled from the retracted to extended position) may be at least 100mm, for example in order to enable the tool to accelerate to the required speed at the point of impact. At each position of the first set of positions the compaction end may be extended and then retracted multiple times before being moved to the next position. The time taken between successive impacts of the tool with the mix while the manipulator holds the compaction tool at a single position of the first set of positions may be at least 100ms, possibly at least 300ms, and optionally at least 500ms. A certain amount of time is required to enable the tool to be retracted before being extended again. The successive impacts of the tool are preferably reasonably rapid to allow fast throughput - thus, the time between successive impacts of the tool may be less than 2 seconds, and is preferably about once a second or faster. The compaction end may have a forward facing surface for impacting on the mix that has a surface area that may be at least 0.005m2but preferably less than 0.15m2. It may be that no mix is added to the mould (or if any is added it is negligible - e.g. less than 5%, possibly less than 1% by weight of the mix already present in the mould) between successive impacts of the compaction end whenextended and retracted at one (preferably each) of the first set and / or second set of positions.

[0025] Compaction of the mix may be performed in multiple different stages. There may be a stage of bulk compaction, performed with a compaction tool with a heavier end, with the path of travel of the tool being generally vertical. There may be multiple (for example at least two) stages of bulk compaction, a first stage performed that results in the mould being partially filled with compacted mix, and a later stage following a step of adding additional semi dry stone mix into the mould on top of the previously compacted mix. A manipulator (for example the same manipulator as used to move the compaction tool between the first set of positions) may then move a compaction tool (for example the same compaction tool) between a second set of positions relative to the mould, wherein at each position of the second set of positions the compaction end of that compaction tool is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted (for example in a similar manner to that performed when the compaction tool is moved between the first set of positions).

[0026] It may be that no mix is added to the mould (or if any is added it is negligible - e.g. less than 5%, possibly less than 1% by weight of the mix already present in the mould) between the compaction tool moving between the first set of positions. It may be that no mix is added to the mould (or if any is added it is negligible - e.g. less than 5%, possibly less than 1% by weight of the mix already present in the mould) between the compaction tool moving between the second set of positions.

[0027] One of the stages of compaction of the mix may include corner compaction. A different compaction tool may be used for corner compaction than is used for bulk compaction. The robotic system may be configured to perform corner compaction by firing a corner compaction end of a corner compaction tool (for example using a pneumatic control system) along a linear path at speed at the mould, such that at the point of impact with the mix in the mould the corner compaction end is travelling at a speed of at least 1 ms-1, preferably at least 2ms- 1 or at least 4ms- 1, and possibly faster than a bulk compaction end of a bulk compaction tool. The corner compaction end may have a mass that is less than half the mass of the bulk compaction end. The corner compaction tool may have a mass that is at least 0.1kg, preferably at least 0.25kg and possibly 0.4kg or more. Themomentum of the corner compaction endat the point of impact may be at least lkgms-1, possibly 5kgms-l or more. The stroke length of the corner compaction end may be similar to the bulk compaction end. It may be at least 100mm. Corner compaction may be performed by the manipulator moving the corner compaction tool to a position and angling it towards a corner of the mould (e.g. a bottom corner), then extending and then retracting the corner compaction end multiple times before the manipulator moves the tool to a different position. The path of travel of the corner compaction end may be at an angle (e.g. of at least 10 degrees, preferably more than 20 degrees) to the vertical.

[0028] Thus in an embodiment of the present invention there is provided a method of forming a semi dry cast stone product using a robotic system that acts on a mould containing semi dry stone mix, the robotic system comprising two or more compaction tools each having a compaction end, and one or more manipulators for moving said compaction tool(s) relative to a mould, wherein the method comprises said one or more manipulators moving a first compaction tool between a set of different positions relative to a mould, and at each position effecting a compacting action on the mix in the mould by movement of the compaction end repeatedly towards and away from the mix in the mould in vertical direction, said one or more manipulators moving a second compaction tool end (which may be smaller and / or less massive than the first compaction tool end) between a set of different positions relative to a mould (after, before or overlapping in time with when the first compaction tool end is compacting the mix), and at each position effecting a compacting action on the mix in the mould by movement of the second compaction end repeatedly towards and away from the mix in the mould in a direction at an angle (e.g. a non-zero or non-negligible angle, for example of more than 10 degrees) to the vertical and directed into a corner or lower edge of the mould.

[0029] As mentioned above, a compaction end may be used to compact a portion of the semi dry stone mix in the mould, before additional semi dry stone mix is added into the mould, after which a compaction end (which may be the same or a different compaction end) is used to compact the newly added semi dry stone mix. Thus in an embodiment of the present invention there is provided a method of forming a semi dry cast stone product using a robotic system, the robotic system comprising: (a) one or more compaction tools each having a compaction end which is extendable and retractable along a compactiondirection relative to a mounting portion of the compaction tool; and (b) one or more manipulators, each being attachable to the mounting portion of one or more of the one or more compaction tools and configured to move said compaction tool(s) relative to a mould, the method comprising (i) providing a mould containing semi dry stone mix; (ii) using a manipulator to move a compaction tool between a first set of positions relative to the mould, wherein at each position of the first set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted; (iii) adding additional semi dry stone mix into the mould on top of the compacted portions; (iv) using a manipulator to move a compaction tool between a second set of positions relative to the mould, wherein at each position of the second set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted; and (v) removing the compacted semi dry stone mix from the mould and curing it to form a solid product.

[0030] The use of a robot for performing the method may provide numerous benefits such as improved precision of compaction (for instance what portions of semi dry stone mix are compacted, and how firmly they are compacted), improved speed of throughput, and / or reduced requirement for manual exertion.

[0031] The method deviates from conventional approaches to automating compaction or moulding processes, as found in remote technical fields, in ways which would not be obvious to the skilled person even if he were aware of such processes. In particular, the method requires compaction of some semi dry stone mix, before additional mix is added and further compaction takes place. The inventor of the present application has discovered that this can improve the compaction of the semi dry stone mix, providing a stronger and more aesthetically pleasing product. However, it runs counter to the thinking of conventional automation where one would seek to fill the mould with all the required mix and then perform all necessary compaction, in order to reduce process complexity and time spent moving between different operations.

[0032] The method also deviates from conventional approaches to automating compaction or moulding processes in that the compaction of the semi dry stone mix is performed with a compaction tool in different positions. The inventor of the present application has discovered that this approach can also improve the compaction of the mix and provide theassociated advantages in terms of strength and aesthetics. Again, however, it runs counter to conventional thinking in automation where a compaction tool, of complementary shape to the mould, would be used in a single position to compact the mix in all the areas of the mould at once. According to conventional thinking it might be thought that a hydraulic press for compacting the mix in the mould would be faster and allow better controlling of loads on the machine provided for performing compaction, for example.

[0033] The compacted semi dry stone mix may be removed from the mould and then cured. As an alternative, the compacted semi dry stone mix may be cured and then removed from the mould. As another alternative, the compacted semi dry stone mix may be removed from the mould in a partially cured state.

[0034] The compaction direction may be a substantially straight line. As an alternative, the compaction direction may be curved. For instance, the compaction end of a compaction tool may be a lever which pivots to extend and retract it, whereupon the compaction direction would be an arc.

[0035] The mould may be removed from the robotic system to add the additional semi dry stone mix, before being replaced in advance of the manipulator moving a compaction tool between the second set of positions. As an alternative the mould may remain in the robotic system while the additional semi dry stone mix is added.

[0036] The method may further comprise, before additional semi dry stone mix is added into the mould, using a manipulator to move a compaction tool between an additional set of positions relative to the mould, wherein at each position of the additional set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix is in the mould and then retracted.

[0037] This may improve the compaction of the semi dry stone mix which is compacted before the additional semi dry stone mix is added, which may lead to a stronger and / or more aesthetic product.

[0038] The method may further comprise, after movement of a compaction tool between the second set of positions, using a manipulator to move a compaction tool between a further set of positions relative to the mould, wherein at each position of the further set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix is in the mould and then retracted.

[0039] This may improve the compaction of the semi dry stone mix which is added part way through the compaction process, which may lead to a stronger and / or more aesthetic product.

[0040] The robotic system may have a single manipulator which performs all movement of the compaction tool(s) between said positions. As an alternative, the robotic system may have two or more manipulators each of which performs some of the movement of the compaction tool(s) between said positions. For example, one manipulator may move a compaction tool between the first set of positions and another manipulator may move a compaction tool between the second set of positions.

[0041] Where a compaction tool is moved between an additional set of positions and a compaction tool is moved between a further set of positions, a first manipulator may move a compaction tool between the first set of positions and move a compaction tool between the additional set of positions, and a second manipulator may move a compaction tool between the second set of positions and move a compaction tool between the further set of positions. As an alternative the robotic system may have four manipulators each of which moves a compaction tool between one set of positions.

[0042] Where the robotic system comprises more than one manipulator, the manipulators may be positioned adjacent to or opposite to one another.

[0043] The positions making up a set of positions are different from another. However, for the avoidance of doubt, one or more positions of a compaction tool may be common to two or more sets of positions. Indeed, in some cases two or more sets of positions (for instance all sets of positions) may be duplicate sets of the same positions.

[0044] Each set of positions may comprise at least two positions, at least three positions, at least four positions or at least five positions.

[0045] Within a particular set of positions, each position may differ from the other positions in terms of the location of said compaction tool and / or in terms of the angle of said compaction tool (i.e. the angle of the compaction direction thereof, and / or the angle of the compaction tool about the compaction direction).

[0046] Optionally, in each position of at least one of the sets of positions, the compaction end of said compaction tool is extended and then retracted more than once, for instance twice, three times or more.

[0047] At least one of the sets of positions may be a set of positions in which the compaction direction is positioned substantially vertically.

[0048] Vertical compaction may allow compaction to assist with the spreading out of a pile of semi dry stone mix within the mould, so as to provide a more even layer.

[0049] The mould may have one or more corners defined on a bottom side of the mould. There may be two or more corners. There may be three of more corners, for example, and optionally at least four corners.

[0050] Optionally, the mould has a bottom wall, and at least two walls extending upwardly from the bottom wall. There may be at least two opposing end walls. There may be at least two opposing side walls. Optionally, the mould defines a set of bottom edges, for example four bottom edges, each bottom edge being defined by the bottom wall and one of the side walls or end walls. The mould may define a set of four corners, each corner being defined by the bottom wall, one of the end walls and one of the side walls. It may be that at least one of the sets of positions is a set of positions in which extension of the compaction end moves the compaction end generally towards one or more of the bottom edges of the mould.

[0051] The bottom edges of the mould can be quite constricted, making these areas at relatively high risk of a void forming in the semi dry stone mix. With extension of the compaction end moving it generally towards one or more of the bottom edges, semi dry stone mix may be compacted into said bottom edge(s) of the mould more effectively so as to reduce the level of risk.

[0052] At least one of the sets of positions may be a set of positions in which extension of the compaction end moves the compaction end generally towards one or more of the corners of the mould.

[0053] The corners of the mould can also be quite constricted and vulnerable to void formation, often more so than the bottom edges. With extension of the compaction end moving it generally towards one or more of the corners, semi dry stone mix may be compacted into said corner(s) of the mould more effectively so as to reduce the level of risk.

[0054] For the avoidance of doubt, if a compaction end is moved generally towards a corner then it is necessarily being moved generally towards a bottom edge of the mould (and indeed towards two bottom edges of the mould at the same time).

[0055] The compaction tool which is moved between one of said sets of positions may be different to the compaction tool which is moved between another of said sets of positions.

[0056] This can allow the compaction tools used for different sets of positions to be tailored more towards the requirements of those positions. For example where one set of positions is a set of positions in which the compaction end is extended towards the corners of the mould, the compaction tool used in those positions may have a narrower compaction end so as to reach into the corners more effectively. Equally, where another set of positions is a set of positions in which the compaction end is extended straight downwards, the compaction tool used in those positions may have a compaction end which is wider so as to cover more area at once.

[0057] As an alternative, the same compaction tool may be moved between all said sets of positions.

[0058] The method may further comprise using the robotic system to place a reinforcing bar onto the compacted semi dry stone mix before adding the additional semi dry stone mix. The mould may be shaped to make a stone product with a maximum dimension (e.g. length) of between 250mm and 1500mm, for example between 400mm and 1200mm. It may be that the use of at least one reinforcing bar is beneficial when making products having a length of about 600mm.

[0059] The compacted semi dry stone mix is the semi dry stone mix that was compacted during movement of a compaction tool between the first set of positions, and / or compacted during movement of a compaction tool between the additional set of positions where this step is performed.

[0060] The inclusion of a reinforcing bar in the component may improve its strength, particularly under tension or under the tensile stresses associated with bending loads, in a manner akin to reinforced concrete.

[0061] The reinforcing bar may define a longitudinal axis, and the robotic system may reciprocally move the reinforcing bar along its longitudinal axis while pushing it into the compacted semi dry stone mix.

[0062] This may bed the reinforcing bar into the compacted semi dry stone mix, which may ensure that it is seated properly and does not move when the additional semi dry stonemix is added. This, in turn, can improve the strength of the product and / or improve the consistency of its behaviour under loads in different directions.

[0063] As an alternative, the reinforcing bar may be pressed down into the compacted semi dry stone mix without movement along its longitudinal axis, or may simply be placed or dropped on top of the compacted semi dry stone mix.

[0064] The method may further comprise using the robotic system to scrape excess semi dry stone mix from a top surface of the mould, for instance before the mould is removed from the robotic system.

[0065] This can give the top of the mould an even and unimpeded surface, allowing the mould to be turned out with lower risk of distortion of the compacted semi dry stone mix.

[0066] The robotic system may scrape the excess semi dry stone mix by running an edge of a compaction tool across the top surface using a manipulator.

[0067] This may reduce the number of different tools required by the robotic system, resulting in a lower overall cost and / or resulting in shorter production time due to reduced need for tool changeover.

[0068] The edge of the compaction tool may be an edge of the compaction end of the compaction tool.

[0069] The method may further comprise using the robotic system to run a rake member across the compacted semi dry stone mix before the additional semi dry stone mix is added.

[0070] Said compacted semi dry stone mix is the semi dry stone mix that was compacted during movement of a compaction tool between the first set of positions, and / or compacted during movement of a compaction tool between the additional set of positions where this step is performed.

[0071] The robotic system may use the manipulator to run the rake member across the compacted semi dry stone mix. As an alternative, the robotic system may have a rake tool which is presented to the mould whereupon an actuator of the rake tool may move the rake member across the compacted semi dry stone mix.

[0072] Raking the compacted semi dry stone mix may roughen its surface, thereby allowing better adhesion between the compacted semi dry stone mix and the additional semi dry stone mix added subsequently. This, in turn, can improve the strength and / or water resistance of the product.

[0073] The method may comprise compacting substantially all the semi dry stone mix in the mould. For instance during movement of a compaction tool between each set of positions, all of the semi dry stone mix in the mould at that time may be compacted.

[0074] The method may further comprise using the robotic system to slide a substantially flat surface across an exposed top surface of the compacted semi dry stone mix, with the substantially flat surface and exposed top surface being in substantially planar contact during said sliding, after all said compaction of portions of the semi dry stone mix.

[0075] This may improve the finish of the exposed top surface, giving that surface better aesthetics and / or water resistance in the finished product.

[0076] The robotic system may use the manipulator to run the substantially flat surface across the compacted semi dry stone mix. As an alternative, the robotic system may have a trowelling tool which is presented to the mould whereupon an actuator of the trowelling tool may move the substantially flat surface across the compacted semi dry stone mix.

[0077] The substantially flat surface may be a surface of a compaction tool, for instance a surface of the compaction end which is positioned to contact semi-dry stone mix during compaction.

[0078] The robotic system may be a single robot. As an alternative, the robotic system may comprise two or more robots (which may be in communication with one another or in communication with a common controller, or may be entirely independent of one another).

[0079] The mould containing semi dry stone mix may be accommodated by a mould carrier. The mould may be located in a set position relative to the mould carrier, which may for example be determined by one or more formations defined by structure of the mould carrier engaging with one or more parts of the mould. The method may include a step of using a conveyor to convey the mould carrier to a set position in a conveying direction, for example relative to a mould support, for example a table. The mould carrier and mould may be conveyed by the conveyor to where a manipulator is located. The method may include causing the mould carrier and mould to move relative to the table (e.g. by lowering the conveyor or raising the table) to bring a set of formations of the table (e.g. pins) into engagement with a set of corresponding formations of the mould carrier (e.g. holes), for example so that the mould carrier (and therefore the mould) are moved to and / or held in a particular position relative to a datum. There may be a step of clamping the mould againsta structure of the mould carrier that defines a datum edge and / or clamping the mould carrier against a structure that defines a datum edge, for example so as to restrict its / their movement in a direction transverse to the conveying direction. By such steps, it may be that the mould carrier and / or the mould are held in a fixed and preset position relative to a mould support (e.g. the table) and / or the manipulator. It may be that the weight of the mould carrier and mould are supported by the conveyor as it conveys the mould carrier to the table, and that the method includes lowering the conveyor, mould carrier and mould so as to transfer support of the weight of the mould carrier and mould from the conveyor to the mould support / table.

[0080] The robotic system may be controlled by a computer comprising a processor and memory. The computer may be arranged to control the movements of the one or more compaction tools according to a set of motions dictated by the shape and size of the mould. The method may include the computer selecting a particular set of motions, in preference to other sets of motions, in dependence upon an input to the computer that relates to the shape and / or size of the mould being used in the method. The method may include the computer selecting said particular set of motions based on information detected by the computer about the size and shape of the mould. The information may be detected by, for example, reading mould ID information provided on the mould (for instance in the form of a barcode or QR code read by an optical scanner connected to the computer, or in the form of an RFID chip read by an RFID reader connected to the computer). For instance, each mould may be provided with a sticker, insert or the like on which an ID barcode it is provided. The computer may then identify a mould using its ID barcode, infer from the ID barcode the dimensions of the mould (for instance using a lookup table), and then select a particular set of motions which will provide compaction of semi dry stone mix in the mould without leaving uncompacted areas of mix or allowing a compaction tool end to collide with a wall of the mould.

[0081] According to a second aspect of the present invention there is provided a robotic semi dry cast stone moulding machine comprising: a mould support configured to support a mould;one or more compaction tools each having a mounting portion, a compaction end and an actuator arranged to extend and retract the compaction end along a compaction direction relative to the mounting portion; a manipulator attachable to the mounting portions of each of the one or more compactions tool and configured to move said one or more compaction tools relative to the mould support; and a controller operably connectable to the manipulator and each of the one or more compaction tools so as to control the movement of the manipulator and the or each compaction tool, wherein the controller is configured to: control the manipulator to move a compaction tool between a first set of positions relative to the mould support, and to control the actuator of that compaction tool to extend and then retract the compaction end in each position of the first set of positions so as to compact a portion of semi dry stone mix in a mould supported by the mould support; pause until signalled that additional semi dry stone mix has been inserted into said mould supported by the mould support, on top of the compacted portions; and control the manipulator to move a compaction tool between a second set of positions relative to the mould support, and to control the actuator of that compaction tool to extend and then retract the compaction end in each position of the second set of positions so as to compact a portion of semi dry stone mix in a mould supported by the mould support.

[0082] Such a robotic machine may provide numerous benefits such as improved precision of compaction (for instance what portions of semi dry stone mix are compacted, and how firmly they are compacted), improved speed of throughput, and / or reduced requirement for manual exertion.

[0083] The robotic machine deviates from conventional approaches to automating compaction or moulding processes, as seen in remote technical fields, in ways which would not be obvious to the skilled person even if he were aware of them. In particular, the machine is configured to compact of some semi dry stone mix, pause for additional mix to be added, then perform further compaction. The inventor of the present application has discovered that this can improve the compaction of the semi dry stone mix, providing astronger and more aesthetically pleasing product. However, it runs counter to the thinking of conventional automation where one would seek to provide apparatus configured for the mould to be filled with all the required mix before all necessary compaction is performed, in order to reduce the complexity of use of the machine and the time spent with the robot switching between different operations.

[0084] The method also deviates from conventional approaches to automating compaction or moulding processes in that the machine is configured to compact the semi dry stone mix by moving a compaction tool between different positions. The inventor of the present application has discovered that this approach can also improve the compaction of the mix and provide the associated advantages in terms of strength and aesthetics. Again, however, it runs counter to conventional thinking in automation where a compaction tool, of complementary shape to the mould, would be provided to be used in a single position to compact the mix in all the areas of the mould at once.

[0085] The mould support may have one or more holding members to support the mould and prevent it from moving. As an alternative, the mould support may be a recess or a plain surface, for example.

[0086] The manipulator may be configured to move a compaction tool by translation in one dimension (for instance along a length direction), in two dimensions (for instance in a length direction and a width direction) or three dimensions.

[0087] Instead or as well, the manipulator may be configured to move a compaction tool by rotation about one axis (for instance a length axis of the mould support), two orthogonal axes (for instance a length axis and a width axis of the mould support), or three orthogonal axes (for instance a length axis, width axis and depth axis of the mould support).

[0088] A machine according to the second aspect of the invention may be for performing a method according to the first aspect of the invention.

[0089] The controller may be configured to control the manipulator to move a compaction tool between an additional second set of positions relative to the mould support, and to control the actuator of that compaction tool to extend and then retract the compaction end in each position of the additional set of positions, before said pausing.

[0090] The controller may be configured to control the manipulator to move a compaction tool between a further set of positions relative to the mould support, and to control theactuator of that compaction tool to extend and then retract the compaction end in each position of the further set of positions, after movement of a compaction tool between the second set of positions.

[0091] Optionally, the controller may be configured whereby in each position of at least one of the sets of positions, the compaction end of said compaction tool is extended and then retracted more than once, for instance twice, three times or more.

[0092] At least one of the sets of positions may be a set of positions in which the compaction direction is positioned substantially vertically.

[0093] Vertical compaction may allow compaction to assist with the spreading out of a pile of semi dry stone mix within the mould, so as to provide a more even layer.

[0094] Optionally: the mould support defines a length axis positioned to run between opposing end walls of said mould supported by the mould support; a width axis positioned to run between opposing side walls of said mould; and a depth axis; the depth axis is generally upright; the axes of the mould support are substantially perpendicular to one another; and at least one of the sets of positions is a set of positions in which the compaction direction has a component in the direction of the depth axis and a component in the direction of another axis of the mould.

[0095] Each of the axes of the mould support may be straight. As an alternative, the length axis and / or the width axis may be curved.

[0096] With the compaction direction so aligned, extension of the compaction end may move the compaction end generally towards one or more of the bottom edges of the mould. The bottom edges of the mould can be quite constricted, making these areas at relatively high risk of a void forming in the semi dry stone mix. With extension of the compaction end moving it generally towards one or more of the bottom edges, semi dry stone mix may be compacted into said bottom edge(s) of the mould more effectively so as to reduce the level of risk.

[0097] At least one of the sets of positions may be a set of positions in which the compaction direction has a component in the direction each of the axes of the mould.

[0098] With the compaction direction so aligned, extension of the compaction end may move the compaction end generally towards one or more of the corners of the mould. The corners of the mould can also be quite constricted and vulnerable to void formation, often more so than the bottom edges. With extension of the compaction end moving it generally towards one or more of the corners, semi dry stone mix may be compacted into said corner(s) of the mould more effectively so as to reduce the level of risk.

[0099] Optionally: the machine further comprises a gripper tool which is configured to grasp and release a reinforcing bar; the gripper tool is attachable to the manipulator and movable thereby; and the controller is operably connectable to the gripper tool to control the grasping and realising of the reinforcing bar.

[0100] The gripper tool may allow the robotic machine to place a reinforcing bar on top of the compacted semi dry stone mix before the additional semi dry stone mix is added. The inclusion of a reinforcing bar in the component may improve its strength, particularly under tension or under the tensile stresses associated with bending loads, in a manner akin to reinforced concrete.

[0101] The machine may further comprise a rake member configured to be raked across compacted semi dry stone mix.

[0102] Raking the compacted semi dry stone mix may roughen its surface, thereby allowing better adhesion between the compacted semi dry stone mix and the additional semi dry stone mix added subsequently. This, in turn, can improve the strength and / or water resistance of the product.

[0103] The machine may comprise more than one compaction tools. The mounting portions of the compaction tools may be interchangeably attachable to a common attachment point provided on the manipulator. This may allow the robotic machine to be advantageously compact. As an alternative, each compaction tool may be attached to a different point on the manipulator, in which case the manipulator may be configured to move all the compaction tools at once (but align different compaction tools with the mould support as needed). This may allow the machine to swap between different tools with advantageous speed.

[0104] The range of motion of the compaction end of at least one of the one or more compaction tools, relative to the mounting portion, may be more than 50mm, for instance more than 100mm or more than 150mm.

[0105] This may reduce the risk of the range of motion of the compaction end being insufficient to allow full compaction of semi dry stone mix in the mould.

[0106] The range of motion of the compaction end of at least one of the one or more compaction tools, relative to the mounting portion, may be less than 500mm, for instance less than 400mm, less than 300mm or less than 250mm.

[0107] This may reduce the risk of the compaction end being able to move too far, which may lead to it penetrating into the semi dry stone mix rather than compacting it.

[0108] The actuator of at least one of the one or more compaction tools may be arranged to extend the compaction end with a force of more than 200N, for instance more than 400N or more than 600N.

[0109] This may reduce the risk of the compaction tool extending with insufficient force to properly compact the semi dry stone mix.

[0110] The actuator of at least one of the one or more compaction tools may be arranged to extend the compaction end with a force of less than 3000N, for instance less than 2000N or less than 1000N.

[0111] This may reduce the risk of the compaction end extending with excessive force, which may lead to it penetrating into the semi dry stone mix rather than compacting it.

[0112] The compaction end of at least one of the one or more compaction tools may have a mass of at least 1kg, for instance at least 2.5kg or at least 4kg.

[0113] The compaction end of at least one of the one or more compaction tools, and any other components of said compaction tool which move together with the compaction end relative to the mounting portion, may have a total mass of more than 2kg, for instance more than 4kg or more than 6kg.

[0114] This may reduce the risk of the compaction tool having insufficient mass, and thus insufficient momentum, to provide a hammering action and properly compact the semi dry stone mix.

[0115] The momentum of the compaction end of at least one of the one or more compaction tools (potentially including any other components of said compaction tool which movetogether with the compaction end) at the point of impact of the compaction end may be at least 5kgms , for instance lOkgms'1or more.

[0116] The compaction end of at least one of the one or more compaction tools, and any other components of said compaction tool which move together with the compaction end relative to the mounting portion, may have a total mass of less than 80kg, for instance less than 40kg or less than 20kg.

[0117] This may reduce the risk of the compaction tool having excessive mass, which may make the machine less energy efficient and / or may lead to the compaction end penetrating into the semi dry stone mix rather than compacting it.

[0118] The controller may be configured to move one compaction tool between one of said sets of positions, and move a different compaction tool between another of said sets of positions.

[0119] The actuator of at least one of the one or more compaction tools may be a pneumatic cylinder.

[0120] The compaction end of at least one of the one or more compaction tools may have a convex surface positioned to contact semi dry stone mix being compacted by said compaction tool.

[0121] The compaction end of at least one of the one or more compaction tools may have a substantially planar surface positioned to contact semi dry stone mix being compacted by said compaction tool.

[0122] At least one of the one or more compaction tools may have one or more guide rods positioned to guide movement of the compaction end between the extended and retracted positions.

[0123] The one or more guide rods may move with the compaction end, or may form part of the compaction end. As an alternative, they may remain stationary and the compaction end of a component connected thereto may run along them during extension and retraction of the compaction end.

[0124] At least one of the one or more compaction tools may have a resilient buffer positioned to limit extension of the compaction end.

[0125] The manipulator may be a robotic arm.

[0126] The actuator of at least one of the one or more compaction tools may be arranged to extend the compaction end with a speed of the compaction end immediately before contact with the semi dry stone mix of more than 1ms , preferably more than 2ms4and optionally at least 3ms4. The actuator of at least one of the one or more compaction tools may be arranged to extend the compaction end with a speed of the compaction end immediately before contact with the semi dry stone mix such that the compaction end has a momentum of at least 5kgms4, preferably at least lOkgms4, and optionally at least 15kgms4.

[0127] The manipulator may comprise a multi-axis robot arm, for example an arm having at least four axes of control (and comprising at least three rotating joints). The motion of the arm may be effected by two or more servomotors, optionally at least four servomotors. It may be that each compaction tool is configured to fire the compaction end (for example a part of the tool) towards the mould, for example pneumatically with the use of a pneumatic system or electromagnetically (e.g. using a solenoid). This is preferably done in a way that protects the servomotors of the arm, at least in part, from the forces and / or shocks experienced by the compaction end when the tool impacts with the mix in the mould and / or rebounds therefrom.

[0128] The protection for the servomotors may be provided by a decoupling mechanism. For example, the tool, or part thereof, may be fired (e.g. thrown) at the mix with the use of pneumatic pressure provided by a pneumatic device such that when the tool impacts with the mix the pneumatic device is disengaged or otherwise isolated from any rapid change in pressure in the pneumatic system that might occur. For example, a vent valve in the pneumatic system may be opened at the relevant time to protect the servomotors from forces that would otherwise occur. As another example the tool, or part thereof, may be fired at the mix electromagnetically such that when the tool impacts with the mix electric current responsible for firing of the tool may be blocked by a switch or the like. Mechanical springs, air springs, and / or air damping may additionally, or alternatively, be provided to assist with protecting the servomotors from such forces.

[0129] The manipulator may be rated to handle loads of over 100kg, preferably over 150kg, and optionally over 200kg. The manipulator may be configured to have a reach of over Im, preferably over 2m, and optionally over 3m.

[0130] The present invention also provides a system for moulding semi dry cast stones including a moulding machine according to any aspect of the invention as described or claimed herein. Such a system may comprise multiple mould carriers, each mould carrier being configured to hold and support a mould in a set position relative to a datum. Such a system may comprise a conveyor for conveying the mould carriers to and from the manipulator.

[0131] Each mould carrier may comprise one of more formations (for example edges or stop or the like) for holding a mould in a fixed position relative to a datum. Each mould carrier may comprise one of more formations (for example pins, or holes, or the like) for engaging with corresponding formation formed on another part of the system (for example a conveyor, support or table of the like), so that the mould carrier holding a mould may be moved to a fixed position relative to a datum of the system.

[0132] The system may comprise a clamp for holding the mould carrier and / or mould in place in a fixed position relative to a datum ready for the manipulator to move the compaction tool between the first set of positions relative to the mould support.

[0133] The present invention also provides a kit of parts for use in such a system, the kit of parts comprising multiple such mould carriers and multiple such moulds.

[0134] The present invention also provides a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to function as the controller according to any aspect of the invention as described or claimed herein and / or the computer according to any aspect of the invention as described or claimed herein.

[0135] The present invention also provides multiple (e.g. 10 or more) identical moulded structures made using a method according to any aspect of the invention as described or claimed herein and / or or using the apparatus according to any aspect of the invention as described or claimed herein, the identical moulded structures being made using the same shape and size of mould. It has been observed in testing that the moulded products resulting from the use of the method and / or the machine according to the present invention are far more consistent in quality than those made using an entirely manual process. For example, multiple moulded structures may be manufactured over the course of several hours (e.g. 5 hours or more) with fewer products failing to meet quality control tests, as compared withmanually made products. This may be as a result of more consistent compaction in all regions of the mix in the mould. The variation in density throughout the product may be less than when compared with manually made products. This may be tested by taking a random sample of ten manually made products, and comparing them with a random sample of ten products made according the present invention, using the same set of moulds. It may be that the standard deviation of the mass of the manually made products is more than 1%, greater, for example 5% greater (possibly more than 10% greater), than the standard deviation of the mass of the products according to the present invention. Alternatively samples could be taken by dividing each product into eight pieces of approximately equal mass, and comparing the distribution of the densities of such pieces (comparing 80 pieces in total). It may be that the standard deviation of the density of the pieces taken from the manually made products is more than 1%, greater, for example 5% greater (possibly more than 10% greater), than the standard deviation of the density of the pieces taken from the products according to the present invention. There may be more hidden voids, as measured by number and / or volume, in manually made products, which create a larger variation in densities.

[0136] According to a third aspect of the present invention there is provided a semi dry cast stone product manufactured using a method according to the first aspect of the invention and / or using a machine according to the second aspect of the invention (and / or using any other aspect or embodiment of the invention).

[0137] According to a fourth aspect of the present invention there is provided a building comprising a semi dry cast stone product according to the third aspect of the invention.

[0138] The / a compaction tool described above may comprise a suspension mechanism configured to allow one part of the tool to be resiliently movable relative to another part of the tool. For instance, a part comprising the compaction end may be movable relative to a part configured for attachment to a manipulator such as a robotic arm. The suspension mechanism may be configured to constrain relative movement of said parts to movement in one direction, such as a generally vertical direction. The suspension mechanism may comprise one or more resilient members in the form of coil springs or elastomeric components, for example. The suspension mechanism may bias said parts to a limit of saidrelative movement, for instance a limit of downward movement of a part comprising the compaction end.

[0139] It is to be understood that reference herein to the weight or momentum of a compaction end may refer to the weight / momentum of just that compaction end, or the weight / momentum of that compaction end along with any other components of that compaction tool which move together with the compaction end.

[0140] The semi dry stone mix may comprise sand, lime, cement and water. Optionally it may also comprise a dye or pigment, and / or a waterproofing agent which limits the water permeability of the finished product. The semi dry stone mix may consist essentially of, or may consist of, those four, five or six ingredients. Accordingly, a semi dry cast stone product produced by such a mix would comprise (or consist essentially of or consist of) said ingredients but with reduced or zero water content.

[0141] The semi dry stone mix may have a water to cement ratio of less than 0.3, for instance less than 0.27, less than 0.25 or less than 0.23. In contrast, concrete (even dry cast concrete) has a water to cement ratio of more than 0.3 and typically around 0.4-0.6 or more. Nonetheless, in a semi dry stone mix water is still typically required for proper curing. Accordingly, the semi dry stone mix may have a water to cement ratio of at least 0.1, for instance at least 0.15, at least 0.18 or at least 0.2.

[0142] The water content of the semi dry stone mix may be less than 7% by mass, for instance less than 6%, less than 5.5% or less than 5%. Instead or as well, the water content of the semi dry stone mix may be at least 2% by weight, for instance at least 3%, at least 4% or at least 4.5%.

[0143] The semi dry stone mix may comprise at least 10% by weight of lime, for instance at least 15% or at least 20%. Instead or as well, the semi dry stone mix may comprise no more than 35% by weight of lime, for instance no more than 30% or no more than 25%. That percentage weight may be of the complete mix, or of the dry mix (i.e. of the mix excluding water).

[0144] The semi dry stone mix may comprise at least 10% by weight of cement, for instance at least 15% or at least 20%. Instead or as well, the semi dry stone mix may comprise no more than 35% by weight of cement, for instance no more than 30% or no more than 25%. That percentage weight may be of the complete mix, or of the dry mix.

[0145] The semi dry stone mix may comprise at least 40% by weight of sand, for instance at least 45% or at least 50%. Instead or as well, the semi dry stone mix may comprise no more than 70% by weight of sand, for instance no more than 65%, or no more than 60% or no more than 55%. That percentage weight may be of the complete mix, or of the dry mix.

[0146] The semi dry stone mix may comprise roughly equal proportions of lime and cement. For example, the semi dry stone mix may comprise lime, cement and sand at a ratio of around 2:2:5, or more particularly around 13: 13:33. Indeed, the semi dry stone mix may comprise lime, cement, sand and water at a ratio of around 2:2:5:0.4, more particularly around 13:13:33:2.7.

[0147] It will of course be appreciated that features described in relation to one aspect / embodiment of the present invention may be incorporated into other aspects / embodiments of the present invention.DESCRIPTION OF THE DRAWINGS

[0148] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:Figure 1 shows a perspective view of a robotic semi dry cast stone moulding machine according to an embodiment of the invention;Figure 2 shows a plan view of a mould support of the robot of Figure 1, supporting a mould;Figure 3 shows a front view of a compaction tool of the robot of Figure 1, with a compaction end thereof in a retracted position;Figure 4 shows a front view of the compaction tool of Figure 3, with the compaction end in an extended position;Figure 5 shows a perspective view of another compaction tool of the robot of Figure 1;Figure 6 shows a perspective view of another compaction tool of the robot of FigureFigure 7 shows a perspective view of a gripper tool of the robot of Figure 1, and a reinforcing bar;Figure 8 shows a flow chart of a method of forming a semi dry cast stone product;Figure 9 A shows a first set of positions of a compaction tool relative to a mould;Figure 9B shows an additional set of positions of a compaction tool relative to a mould;Figure 9C shows a second set of positions of a compaction tool relative to a mould;Figure 9D shows a further set of positions of a compaction tool relative to a mould;Figure 10 shows a plan view of an assembly line for making dry cast stone mouldings according to a further embodiment of the invention;Figure 11 shows a sectional view of a first tool head used by a robot of the assembly line of Figure 10;Figure 12 shows a sectional view of a second tool head used by a robot of the assembly line of Figure 10;Figure 13A shows a plan view of the first tool head of Figure 11;Figure 13B shows a cross-sectional side view of the first tool head of Figures 11 and 13 A;Figure 14A shows a sectional view (about a horizontal plane) of a platen and mould for use in the assembly line of Figure 10;Figure 14B shows is an enlarged part of Figure 11A showing more detail;Figures 15A and 15B show a view from above and a side view of a part of the assembly line of Figure 10 in a first configuration;Figures 16A and 16B show a view from above and a side view of a part of the assembly line of Figure 10 in a second configuration; andFigures 17A and 17B show a view from above and a side view of a part of the assembly line of Figure 10 in a third configuration.DETAILED DESCRIPTION

[0149] Figure 1 shows a robotic semi dry cast stone moulding machine 2, or a “robot” for short, according to an embodiment of the invention. The robot 2 is an example of a robotic system. The robot 2 has a mould support 4 which has a length axis 6, a width axis 8, and a depth axis 10. The three axes 6, 8, 10 are mutually perpendicular, with the depth axis 10 being positioned vertically. The mould support 4 has a first holding member 12 which extends parallel to the length axis 6 and provides a first datum edge, and a second holding member 14 which extends parallel to the width axis 8 and provides a second datum edge. The mould support 4 supports a mould 16, which is held against the holding members 12, 14 using a pair of clamps 18. Figure 2 shows the mould support 4 and mould 16 schematically in plan view. Figure 2 will now be referred to in combination with Figure 1.

[0150] The mould 16 is made up of five wooden boards 20, 22, 24, 26, 28 held together by clamps 30 (one of which is visible in Figure 1). Board 20 forms a bottom wall of the mould 16, boards 22 and 24 form two opposing end walls of the mould 16, and boards 26 and 28 form opposing side walls. A length axis 32 of the mould 16 extends parallel to (and in this case collinear with) the length axis 6 of the mould support 4, a width axis 34 of the mould 16 extends parallel to (and in this case collinear with) the width axis 8 of the mould support 4, and depth axis 36 of the mould 16 extends parallel to (and in this case collinear with) the depth axis 10 of the mould support 4.

[0151] The mould 16 has four bottom edges 38, each of which is defined by the bottom wall 20 and one of the end walls 22, 24 or side walls 26, 28. The mould 16 also has four corners 40, each of which is defined by the bottom wall 20, one of the end walls 22, 24 and one of the side walls 26, 28.

[0152] Returning to Figure 1, the robot 2 also has a compaction tool 42 and a manipulator 44 in the form of a robotic arm which terminates in an attachment point 45. The compaction tool 42 has a compaction end 46, and a mounting portion 48 in the form of a backing plate. The compaction end 46 is extendable and retractable relative to the mounting portion 48 along a compaction direction 50, which in this embodiment is a straight line. The manipulator is attachable to the mounting portion 48 of the compaction tool 42, and isconfigured to move the compaction tool 42 relative to the mould support 4 (and thus relative to the mould 16).

[0153] The machine 2 also has a controller 52, positioned atop the manipulator 44 in this case, which is connectable to the compaction tool 42 and the manipulator 44 so as to control their movement as described in more detail later.

[0154] The compaction tool 42 is shown more clearly in Figures 3 and 4. Figure 3 shows the compaction end 46 retracted along the compaction direction 50 to a retracted position, and Figure 4 shows the compaction end 46 extended along the compaction direction 50 to an extended position. Referring now to Figures 3 and 4 in combination with Figures 1 and 2, the compaction end 46 of the compaction tool 42 has a compaction head 54 with a planar bottom surface 56 positioned to contact semi-dry stone mix in the mould 16 to compact it, as discussed later.

[0155] The compaction end 46 also has a pair of guide rods 58 each of which is slidably received through a corresponding upper guide block 60. Positioned between the guide blocks 60 is a resilient buffer 64. Both guide rods 58 are also slidably received through a lower guide block 62. Both guide rods 58 terminate at an upper assembly 66 with a projection 68 that is received in a slot 70 in a lever 72 which is pivotably attached to the backing plate 48 by a pivot block 74.

[0156] The compaction tool 42 also has an actuator 76 in the form of a double acting pneumatic cylinder. The cylinder 76 is pivotably mounted at its lower end, and its piston shaft 78 is pivotably connected to the lever 72 at a position between the slot 70 and the pivot block 74.

[0157] To extend the compaction end 46 towards the position shown in Figure 4, the controller 52 signals the cylinder 76 to retract. The piston shaft 78 is thus pulled downwards (from the perspective of Figures 3 and 4), which pulls the lever 72 downwards in synchrony. The lever 72 pivots downwards about the pivot block 74, which moves the slot 70 downwards. The slot 70 pushes the projection 68 of the upper assembly 66 downwards as it rides along the slot. This pushes the upper assembly 66, and thus the whole compaction end 46 (i.e. the upper assembly 66, guide rods 58 and compaction head 54), downward along the compaction direction 50. When the compaction end 46 reaches the point ofmaximum extension, the upper assembly 66 contacts the buffer 64 which prevents it from travelling any further but softens the impact.

[0158] To retract the compaction end 46 towards the position shown in Figure 3, the controller 52 signals the cylinder 76 to extend. The piston shaft 78 is thus pushed upwards (from the perspective of Figures 3 and 4), which pushes the lever 72 upwards in synchrony. The lever 72 pivots upwards about the pivot block 74, which moves the slot 70 upwards. The slot 70 pulls the projection 68 of the upper assembly 66 upwards as it rides along the slot. This pulls the upper assembly 66, and thus the whole compaction end 46, upward along the compaction direction 50.

[0159] With the actuator 76 being attached to the lever 72 between the slot 70 and the pivot block, the lever 72 acts as a third class lever. The lever 72 magnifies the stroke length of the actuator 76 at the expense of the force produced thereby - the compaction end 46 moves further than the piston shaft 78 of the actuator 76, but under lower force. In the present case the compaction end 46 has a total stroke length (i.e. distance along the compaction direction 50 between its fully extended and fully retracted positions) of around 200mm, and is moved with a force of around 800N. This relatively large stroke length and relatively low force gives the compaction end 46 more of a hammering action than a crushing action. The compaction end 46 may therefore considered to be “fired” or “thrown”. To ensure that the compaction end 46 has sufficient momentum to provide that action, it has a relatively high mass. The compaction end 46 and the other components of the compaction tool 42 which move together with it (namely the lever 72 and piston shaft 78) have a total mass of around 10kg. The compaction end 46 is fired at a speed of around 5ms-l, giving the compaction end 46 (and said components) a momentum at point of impact of 50kgms-l.

[0160] Inside the actuator 76 is a decoupling mechanism in the form of a vent valve 79 which is connected to the controller 52. The controller 52 can selectively open the vent valve 79 so as to provide an outlet for pressurised air to escape the actuator 76. In the present embodiment the controller 52 is configured to open the vent valve 79 as the compaction end 46 impacts the semi dry stone mix. When the compaction end 46 impacts the semi dry stone mix the impact creates a shock which can propagate from the compaction tool 42 and into the manipulator 44. Instead or as well, the compaction end 46 may rebound from the semi dry stone mix, which again can create a shock which propagates from thecompaction tool 42 into the manipulator 44. Over time, such shocks can damage components such as servomotors within the manipulator, reducing its service life. By opening the vent valve 79 as the compaction end 46 strikes the semi dry stone mix, the controller 52 can to an extent mechanically decouple the compaction end 46 from the mounting portion 48 (and thus from the manipulator 44), reducing the extent to which shocks from the impact and / or rebounding of the compaction end 46 propagate to the manipulator. In other embodiments the controller 52 may be configured to open the vent valve 79 before the compaction end 46 contacts the semi dry stone mix (but after it has obtained enough speed), or as it contacts the mix.

[0161] The machine 2 of the present embodiment has two other compaction tools 42a, 42b which are not visible in Figure 1. The other compaction tools 42a, 42b are shown in Figures 5 and 6 respectively, which will now be referred to in combination with Figures 1 to 4.

[0162] The other compaction tools 42a, 42b have compaction heads 54a, 54b of different forms, but otherwise are substantially the same as the compaction tool 42 described above. Accordingly, only the compaction heads 54a, 54b will be described in detail.

[0163] In the case of the compaction tool 42a of Figure 5, the compaction head 42a (highlighted in white outline) is generally cylindrical rather than cuboidal, and its bottom surface 56a is convex rather than flat. In the case of the compaction tool 42b of Figure 5, the compaction head 42b is again cuboidal with a flat bottom surface 56b, but is wider than that of the compaction tool 42 of Figures 3 and 4. Accordingly, its bottom surface 56b has a larger area.

[0164] Their differing compaction heads 54a, 54b mean that the compaction ends 46a, 46b have different masses. More particularly, in the compaction tool 42a the compaction end 46a and the other components of the compaction tool 42a which move together with it have a total mass of around 7kg, and in the compaction tool 42b the compaction end 46b and the other components of the compaction tool 42b which move together with it have a total mass of around 14kg.

[0165] As well as the compaction tools 42, 42a, 42b, the robot 2 has a gripper tool. Figure 7 shows part the gripper tool 80, along with a ribbed steel reinforcing bar 82 and its longitudinal axis 84. In the present embodiment the gripper tool 80 has substantially the same structure as each of the compaction tools 42, 42a, 42b with the exception that thegripper tool has a support plate 86 with two pairs of jaws 88, in place of a compaction head. Referring now to Figure 7 in combination with Figures 1 to 6, the gripper tool 80 is configured to grasp and release the reinforcing bar 82 using the jaws 88. The gripper tool 80 is attachable to the manipulator 44 which can move the gripper tool 80 relative to the mould support 4, and is connectable to the controller 52. The controller can open the jaws 88 to receive the reinforcing bar 82, close the jaws 88 to grip the reinforcing bar 82, and open the jaws 88 to release the reinforcing bar 82. The gripper tool 80 also has a rake member 90 (highlighted in white) for raking across compacted semi dry cast stone mix as will be described in more detail later.

[0166] In the present embodiment, each of the tools 42, 42a, 42b, 80 are interchangeably attachable to the attachment point 45 of the manipulator 44 using their respective mounting portions 48. The manipulator 44 can “pick up” and “put down” each of the tools 42, 42a, 42b, 80 as needed, under instructions from the controller 52.

[0167] A method of forming a semi dry cast stone product using the robot 2 will now be described, with reference to Figures 8 and 9A-9D, in combination with Figures 1 to 7.

[0168] In a first step 102, the mould 16 is assembled, filled with a first quantity of semi dry stone mix, and placed onto the mould support 4 to be supported thereby. The mould 16 is clamped against the holding members 12, 14 as described above, to hold it in place.

[0169] In step 104, the controller 52 controls the manipulator 44 to pick up the compaction tool 42a of Figure 5 and move it to a first position A of a first set of positions relative to the mould 16, with its compaction end 46a in the retracted position shown in Figure 3.

[0170] In step 106, the controller 52 then moves the compaction tool 42a between the four positions A-D that make up the first set, as shown in Figure 9A. With the compaction tool 42a in each position, the controller 52 controls the actuator 76 to extend the compaction end 46a so as to compact the portion of the semi dry stone mix which is in the path of the convex bottom surface 56a, then retract it again. More particularly, in this case the compaction end 46a is extended and then retracted three times in each position A-D of the first set of positions, at a speed of around one impact per second.

[0171] In each of the first set of positions, the controller 52 instructs the manipulator 44 to position the compaction tool 52a such that extension of the compaction end 46a moves the compaction end toward one of the corners 40 of the mould. For example in position A thecompaction direction 50 has a component in the vertical direction (i.e. along the depth axis 10 of the mould support 4 and the depth axis 36 of the mould 16) into the page from the perspective of Figure 9, a component in the longitudinal direction (i.e. along the length axis 6 of the mould support 4 and the length axis 32 of the mould 16) upward from the perspective of Figure 9 A, and a component in the width direction (i.e. along the width axis 8 of the mould support 4 and the width axis 34 of the mould 16) to the left from the perspective of Figure 9A. The compaction end 46a thus extends generally towards two different bottom edges at the same time, in the general direction of the top left corner 40 of the mould 19 from the perspective of Figure 9A.

[0172] Similarly, in position B of the first set of positions the compaction direction 50 has a component in the vertical direction into the page from the perspective of Figure 9, a component in the longitudinal direction upward from the perspective of Figure 9A, and a component in the width direction to the right from the perspective of Figure 9A. The compaction end 46a thus extends in the general direction of the top right corner 40 of the mould 19 from the perspective of Figure 9A. Equally, in position C the compaction direction 50 has a component in the vertical direction into the page from the perspective of Figure 9, a component in the longitudinal direction downward from the perspective of Figure 9A, and a component in the width direction to the left from the perspective of Figure 9A. The compaction end 46a thus extends in the general direction of the bottom left corner 40 of the mould 19 from the perspective of Figure 9A.

[0173] After the semi dry stone mix has been compacted into each of the corners 40 of the mould 16 (which may be considered to be corner compaction using a corner compaction tool), in step 108 the controller 52 instructs the manipulator 44 to move compaction tool 42a away from the mould support 4 and put it down, then pick up compaction tool 42 and move it to a first position A of an additional set of positions relative to the mould 16, with its compaction end 46 in the retracted position.

[0174] In step 110, the controller 52 then moves the compaction tool 42 between the nine positions A-I that make up the additional set, as shown in Figure 9B. With the compaction tool 42 in each position, the controller 52 controls the actuator 76 to extend the compaction end 46 so as to compact the portion of the semi dry stone mix which is in the path of the planar bottom surface 56, then retract it again. Again, in this case the compaction end 46is extended and then retracted three times in each position A-I of the additional set of positions, at a rate of around once a second.

[0175] It is noteworthy that in positions A-C the compaction direction 50 is positioned so that it has a component in the depth direction and a component in the width direction (to the left from the perspective of Figure 9B). Thus, extension of the compaction end 46 moves it generally towards one of the bottom edges (the one to the left from the perspective of Figure 9B). Equally in positions G-I the compaction direction 50 is positioned so that it has a component in the depth direction and a component in the width direction (to the right from the perspective of Figure 9B). Thus, extension of the compaction end 46 moves it generally towards another of the bottom edges (the one to the right from the perspective of Figure 9B). In contrast, in positions D-F the compaction direction 50 is positioned parallel to the depth axes 10, 36). Thus, in these positions the compaction tool 42 compacts semi dry stone mix directly downwards towards the bottom wall 20.

[0176] While the additional set of positions has been described as containing each of positions A-I, this should not be construed as limiting. It may equally be considered that the additional set of positions comprises positions A-C and G-I (whereupon the additional set of positions would be considered to be a set of positions in which extension of the compaction end moves the compaction end generally towards one or more of the bottom edges of the mould). In this case, positions D-F may be considered to be an intermediate set of positions which the compaction tool 42 occupies while moving between the positions A-C, G-I of the additional set of positions.

[0177] After compaction of the semi dry stone mix using compaction tool 42a (which may be considered to constitute a first stage of bulk compaction using a first bulk compaction tool), in step 112 the controller instructs the manipulator 44 to move the compaction tool 42a away from the mould support 4 and put it down, and then pick up the gripper tool 80. The gripper tool 80 is moved to where a reinforcing bar 82 is stored, its jaws 88 are opened and placed over the reinforcing bar 82, then the jaws are closed again to grip the reinforcing bar 82. The arm 44 then moves the gripper tool 80, carrying the reinforcing bar 82, over to the mould 16. Under instruction of the controller 52 the arm 44 then rotates the gripper tool 80 to place the rake member 90 at the bottom of the tool 80, then moves the tool 80 so asto draw the rake member 90 across the top of the compacted semi dry stone mix in the mould. This has the effect of roughening the top surface.

[0178] Following raking of the compacted semi dry stone mix, in step 114 the arm 44 rotates the gripper tool 80 back to the position shown in Figure 7. The arm 44 then lowers the reinforcing bar 82 down onto the compacted (and raked) semi dry stone mix, while moving the reinforcing bar 82 reciprocally along its longitudinal axis 84. This beds the reinforcing bar 82 into the compacted semi dry stone mix, ensuring that it remains level. The jaws 88 then release the reinforcing bar 82, and the arm 44 withdraws the gripper tool 80 with the reinforcing bar 82 resting on (and to some extent in) the compacted semi dry stone mix.

[0179] The controller 52 then instructs the manipulator 44 to move the gripper tool 80 away from the mould support and put it down. Then, in step 116, the controller 52 initiates a pause. At this point, workers add additional semi dry stone mix into the mould 16, on top of the existing semi dry stone mix and the reinforcing bar. Once this has been completed, the workers press a button to signal to the controller 52 that the additional mix has been added.

[0180] After receiving the signal, in step 118 the controller 52 instructs the manipulator 44 to pick up the compaction tool 42b shown in Figure 6 and carry it to a first position A of a second set of positions, with its compaction end 46b in the retracted position.

[0181] In step 120, the controller 52 then moves the compaction tool 42b between the three positions A-C that make up the second set of positions, as shown in Figure 9C. With the compaction tool 42b in each position, the controller 52 controls the actuator 76 to extend the compaction end 46b so as to compact the portion of the semi dry stone mix which is in the path of the planar bottom surface 56b, then retract it again. Again, the compaction end 46b is extended and then retracted three times in each position A-C. In each of the second set of positions, the compaction tool 42 is positioned with the compaction direction 50 vertical (i.e. parallel to the depth axes 10, 36), as was the case with positions D-F of the additional set of positions. This stage may be considered to constitute a second stage of bulk compaction using a second bulk compaction tool.

[0182] Following this, in step 122 the manipulator 44 moves the same compaction tool 42b to a first position A of a further set of positions with its compaction end 46b in the retractedposition. In step 124, the controller 52 then moves the compaction tool 42b between the three four positions A-D that make up the further set of positions, as shown in Figure 9D. With the compaction tool 42b in each position, the controller 52 controls the actuator 76 to extend the compaction end 46b so as to compact the portion of the semi dry stone mix which is in the path of the planar bottom surface 56b, then retract it again. Again, the compaction end 46b is extended and then retracted three times in each position A-D. In each of the second set of positions, the compaction tool 42 is positioned with the compaction direction 50 vertical (i.e. parallel to the depth axes 10, 36), as was the case with positions D-F of the additional set of positions, and with the all the second set of positions. This may be considered to constitute another stage of bulk compaction using a bulk compaction tool.

[0183] It is noteworthy that in this final set of positions, the compaction tool 42b is oriented at 90 degrees to its orientation when in each of the other sets of positions. So oriented, the planar bottom surface 56b slightly overlaps the side walls 26, 28 of the mould 16. This can improve the fill of semi dry stone mix into the top part of the mould 16. After the compaction end 46b is retracted for the third time with the compaction tool 42b in the third position C of the further set of positions, compaction of the semi dry stone mix is complete.

[0184] In step 126, the controller 52 instructs the robotic arm 44 to angle the compaction tool 42 and run an edge of the compaction tool 42b (more particularly an edge of the planar bottom surface 56b) across the top surface of the mould 16. This scrapes off excess semi dry stone mix off the mould 16. Then, in step 128 the robotic arm 44 returns the compaction tool to the vertical (i.e. positions the compaction direction 50 vertically), then slides the planar bottom surface 56b across the exposed top surface of the compacted semi dry stone mix (and of the mould). The bottom surface 56b slides along the exposed top surface, in planar contact therewith, which improves the quality of finish of the exposed part of the compacted semi dry stone mix.

[0185] Following this, in step 130 workers remove the mould 16 containing the semi dry stone mix from the mould support, then turn it out onto a board. In conventional fashion they disassemble the mould 16, clean up any defects in the surface finish and take the moulded and compacted semi dry stone mix for curing to form the finished product.

[0186] Figures 10 to 17B show parts of an assembly line system 200 according to a further embodiment of the invention. As shown in Figure 10, the assembly line 200 includes a conveyor system 202 that carries a mould 16 held on a mould carrier 204 in the form of a platen via a number of cells (or stations) at which various actions are taken. The conveyor system 202 conveys the mould carrier 204 and mould 16 in a conveying direction which in this embodiment is substantially linear (from left to right from the perspective of Figure 10) At a first cell 210, moulds 16 are mounted on platens (one mould to a platen) and then filled with semi-dry mix up to level with the upper surface of the mould 16. The first cell 210 allows multiple moulds 16 to be filled in parallel. Once the mould 16 is filled with mix, it is moved onto the conveyer 202 which then transports it to a second cell 212, at which two robots 214, 216 perform a series of operations. Each robot 214, 216 has a 6-axis robotic arm with a reach of just over 3m and rated to handle loads up to 350kg. The first of the two robots 214 has a first tool assembly 218 mounted at the end of its arm.

[0187] In the present embodiment the conveyor system 200 (and indeed the assembly line system 220 as a whole) is a straight line. In other embodiments, however, a conveyor system and / or assembly line system may take any suitable shape. For example, in a modification of the above embodiment the conveyor system (and thus the assembly line system) may be generally L-shaped, C-shaped or U-shaped, or may resemble a closed loop. Such a shape may be formed from a set of straight sections of conveyor, positioned at an angle to one another. For example, a conveyor in the shape of a closed loop may be formed from straight sections of conveyor positioned at right angles to one another to form a generally rectangular shape. A conveyor taking a shape such as those mentioned above may allow the system to occupy a smaller footprint on a shop floor, and / or may tailor it more effectively to the shape of a space available in a shop floor (for instance a corner area thereof). Instead or as well, it may allow robots at different points along the conveyor system to be positioned closer together, which may for example allow a single safety cage to encircle both robots without being excessively large.

[0188] As shown in Figure 11, the first tool assembly 218 has a stomping head tool 220 and a raking tool 222. The stomping head tool 220 of the present embodiment is similar to the compaction tool 42 of the embodiment described above, having inter alia a compaction end 46 movable by a pneumatic cylinder 78 via a lever 72, buffer 64, upper guide blocks60 and a lower guide block 62. Indeed, the first tool assembly 218 may also be considered to be an example of a compaction tool. In view of the similarity between the stomping head tool 220 and the compaction tool 42, it will not be described in detail.

[0189] The raking tool 222 has a rake member 90 of generally the same structure and function as the rake member of the first embodiment, with the exception that it has two tines rather than four. The raking tool 222 also has a pair of guide rods 224 which extend from the rake member 90 through the lower guide block 62, one of which is attached to another actuator 226 in the form of a pneumatic cylinder. The rake member 90 of the raking tool 222 is extendable and retractable using the actuator 226. The ability to extend the rake member 90 can allow it to reach into relatively constricted spaces in moulds 16 more easily.

[0190] The second of the two robots 216 has a second tool assembly 230 mounted at the end of its arm. As shown in Figure 12, the second tool assembly 230 has a corner compaction tool 232 and a gripper tool 234 for gripping a reinforcing bar. The corner compaction tool 232 is similar to the compaction tool 42a of the first embodiment, with the only substantive difference being that the compaction end 46a is smaller (having only a single guide rod 58) and lighter (excluding the guide rod 58, the compaction end only has a mass of 0.5kg). The gripper tool 234 is similar to the gripper tool 80 of the first embodiment, but lacks the support plate 86 and rake member 90 of the gripper tool 80). For the avoidance of doubt, the second tool assembly 230 may also be considered to be an example of a compaction tool.

[0191] Whereas in the first embodiments the backing plate 48 of each compaction tool 42, 42a, 42b forms its mounting portion, in the first and second tool assemblies 218, 230 (and equally the compaction tools constituted thereby) the mounting portion 240 is more complex. As shown in Figures 13A and 13B, in this embodiment each mounting portion 240 has a backing plate 48 (which is of similar structure and function as those of the first embodiment) which is attached to an interface plate 242 of a base section 244 by a suspension mechanism 246. The suspension mechanism 246 comprises a runner 248 projecting from the backing plate 48 which is ridable along a rail 250 projecting from the interface plate 242, and a set of coil springs 252. The rail 250 and runner 248 co-operatively constrain the backing plate 48 so it can move in a single direction (vertical from the perspective of Figure 13B) relative to the base section 244. The coil springs 252 bias thebacking plate 48 (and thus the entire tool assembly) to the downward limit (from the perspective of Figure 13) of its travel relative to the base section 244, but allow it to be displaced upward (from the perspective of Figure 13) from this position.

[0192] The tool assemblies / compaction tools being resiliently movable, thanks to the suspension mechanisms 246 of their mounting portions 240, can avoid shocks generated during semi dry stone mix compaction from propagating into the arms of the robots 214, 216.

[0193] The robots 214, 216 of this embodiment do not have vision systems. Accordingly, it is important that a mould 16 in the second cell 212 is positioned correctly so that it matches the position in that the robots 214, 216 are programmed to expect it. Equally, during compaction / stomping of semi dry stone mix the mould 16, and thus the mould carrier 204, experiences significant downward force. It can beneficial to the longevity of the conveyor system 202 if these forces are not transferred into it. The provisions of the assembly line system 200 which ensure correct mould positioning and prevent stomping force transmittal to the conveyor system 202 will be described below.

[0194] As shown in Figures 14A and 14B, the mould carrier 204 has a flat plate 260 on which handles 262 for manual manipulation are provided. The mould carrier 204 also has a set of anchor points 264 chich collectively provide a pair of datum edges (one horizontal and one vertical from the perspective of Figure 14A) against which a mould 16 is positioned in abutment. This positions the mould 16 correctly on the mould carrier 204. One or more of the anchor points 264 has a location projection 266, which in this embodiment takes the form of a nut which is held in position on the associated anchor point 264 by a bolt 268. Each mould 16 has a corresponding location recess 270 positioned to receive each location projection 266 when the mould is in abutment with all the anchor points 264. Engagement between the location project! on(s) and location recess(es) helps to hold the mould 16 in position on the mould carrier 204 during movement by the conveyor system 202, reducing the risk of vibration or knocks moving the mould 16 relative to the mould carrier 204.

[0195] As shown in Figure 15A, the second cell 212 has a retractable stop surface 272 which forms a datum edge for the mould carrier 204 (and thus for the mould 16). When the mould carrier 204 and mould 16 are transported into the second cell 212 by the conveyor202, they are advanced along the conveying direction (upward from the perspective of Figure 15A and away from the page from the perspective of Figure 15B) until the mould carrier 204 abuts the stop surface 272. Abutment of the mould carrier 204 against the stop surface 272 ensures that the mould carrier 204 (and thus the mould 16) reaches the required position in the conveying direction.

[0196] The second cell 212 also has a table 274 on which is provided an array of formations in the form of upward-facing pins 276. The pins 276 are engageable with a complementary set of formations in the mould carrier 204, in this case an array of blind holes (not visible) on the underside of the mould carrier 204. The pins 276 and holes are each tapered from a wider base to a narrower end.

[0197] During transport of the mould carrier 204 by the conveyor 204, the mould carrier 204 can ride over the top of the table 274 on the conveyor 204. However, a section of the conveyor 202 can be selectively lowered so as to lower a mould carrier 204 and mould 16, placing them onto the table. This is shown in Figures 16A and 16B. During use of the assembly line system 200, the mould carrier 204 is placed onto the table once a mould carrier 204 with a mould 16 has entered the second cell 212 from the first cell 210 and abutted the stop surface 270. With the mould carrier 204 so positioned, its holes are aligned with the pins 276 of the table, therefore when the mould carrier 204 is lowered by the conveyor 202 the pins 276 are received in the holes. This prevents the mould carrier 204 from moving out of position on the surface of the table. Indeed, the tapered shape of the pins 276 and holes (not visible) can also provide a centring action in case of slight misalignment, with the centres of the holes being cammed into a collinear relationship with the corresponding pins 276 during insertion of the pins 276 into the holes.

[0198] The second cell 212 also has an extendable mould clamp 280. Once the mould carrier 204 is resting on the table, the mould clamp 280 is extended so as to clamp the mould 16 against one of the datum edges some of the anchor points 264 of the mould carrier 204 (the horizontal one from the perspective of Figure 14A). This avoids the potential for the mould 16 to be dislodged and become misaligned relative to the mould carrier 204, e.g. due to vibration or knocks from compaction (or ‘stomping’) of the semi dry stone mix.

[0199] Once the mould 16 is clamped in position in the second cell (in the manner as described above), the first robot 214 stomps (and thus compacts) the mix by firing thestomping head tool 220 pneumatically vertically downwards onto the mix in the mould multiple times at a series of set positions across the upper surface of the mix in the mould, in a similar fashion to compaction of semi dry stone mix as described above in relation to Figure 9B.

[0200] The second robot 216 then compacts the lower corners of the mix in the mould 16 by firing the compaction end 46 of the corner compaction tool 232 pneumatically multiple times at each corner in a direction that is angled towards the corner. The first robot 214 then rakes the upper surface of the mix with the raking tool 222 (with the rake member 90 having been extended by the actuator 226). Meanwhile the second robot 216 collects a reinforcing bar (“rebar”) from a store of such bars (rebar feeder system being shown in the Figures as the box containing the word BAR in Figure 10) with the use of the gripper tool 234, such that when the raking is competed the rebar is firmly placed in position on the top of the mix.

[0201] The mould 16 and platen 204 are then un-clamped by retracting the mould clamp 280, and lifted back up off the table 274 by raising the portion of the conveyor 202 which was previously lowered. The stop surface 272 is retracted to allow the mould carrier 204 to continue moving in the conveying direction, and the conveyor 202 moves the mould carrier to a third cell 282 at which mix is added to the mould - this time filling to above the upper surface of the mould. The raking performed at the second cell provides a key for the newly added mix to adhere to. The amount of mix added is such that once compacted the mould 16 will be completely filled with mix up to the upper surface of the mould, but not over-filled to any significant extent. Once the mould 16 is sufficiently over-filled with mix, it is moved back onto the conveyer 202 which then transports it to a fourth cell 284, at which there is located a third robot 286 with a 6-axis robotic arm equipped with a further stomping head tool which is similar to that shown in Figure 11 but with a larger compaction head. Once the mould 16 is in position, it is positioned, lowered and clamped in corresponding fashion to the second cell 212. The third robot 286 then stomps the mix by firing its stomping head tool (not visible) pneumatically vertically downwards onto the mix in the mould multiple times at a series of set positions across the upper surface of the mix in the mould again in a similar fashion to compaction of semi dry stone mix as describedabove in relation to Figure 9C, the point of impact being vertically higher, relative to the bottom of the mould, than when using the stomping head tool 220 of the first robot 214.

[0202] Once the mix in the mould 16 is suitably compacted, the third robot then smooths the top surface of the mix by moving a flat surface of the stomping head tool (not visible) in a circular motion across the upper surface. The platen 204 and mould 16 are then conveyed to a fifth cell 288 at which the platen 204 and mould 16 are moved off the conveyor 202. The mould 16 is then removed from the platen 204, and the platen 204 is returned for re-use on the assembly line 200. The compacted dry-mix is then removed from the mould 16, and cured. The mould 16 is then cleaned are returned for re-use in the assembly line process.

[0203] It is noteworthy that the assembly line system 200 is designed to work with moulds of different shapes and sizes. Each mould is provided with an ID sticker which includes a barcode denoting that specific mould, and each of the robots 214, 216, 286 is provided with an optical barcode scanner. Each robot 214, 216, 286 scans a mould’s barcode to identify it, then accesses a lookup table to select a set of movements (e.g. a set of tool positions) best suited to the size and shape of that mould. This can ensure that the compaction performed by each robot 214, 216, 286 is tailored to the size and shape of each mould 16, so that all the mix is compacted and there is minimal risk of a compaction end colliding with a wall of a mould 16.

[0204] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims

CLAIMS1. A method of forming a semi dry cast stone product using a robotic system, the robotic system comprising: one or more compaction tools each having a compaction end which is extendable and retractable along a compaction direction relative to a mounting portion of the compaction tool; and one or more manipulators, each being attachable to the mounting portion of one or more of the one or more compaction tools and configured to move said compaction tool(s) relative to a mould, the method comprising: providing a mould containing semi dry stone mix; using a manipulator to move a compaction tool between a first set of positions relative to the mould, wherein at each position of the first set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted; adding additional semi dry stone mix into the mould on top of the compacted portions; using a manipulator to move a compaction tool between a second set of positions relative to the mould, wherein at each position of the second set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix in the mould, and then retracted; and removing the compacted semi dry stone mix from the mould and curing it to form a solid product.

2. A method according to claim 1 further comprising, before additional semi dry stone mix is added into the mould, using a manipulator to move a compaction tool between an additional set of positions relative to the mould, wherein at each position of the additional set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix is in the mould and then retracted.

3. A method according to claim 1 or 2 further comprising, after movement of a compaction tool between the second set of positions, using a manipulator to move a compaction tool between a further set of positions relative to the mould, wherein at each position of the further set of positions the compaction end is extended so as to compact a portion of the semi dry stone mix is in the mould and then retracted.

4. A method according to any preceding claim wherein at least one of the sets of positions is a set of positions in which the compaction direction runs substantially vertically.

5. A method according to any preceding claim wherein: the mould has a bottom wall, two opposing end walls and two opposing side walls; the mould defines a set of four bottom edges, each bottom edge being defined by the bottom wall and one of the side walls or end walls; the mould defines a set of four corners, each corner being defined by the bottom wall, one of the end walls and one of the side walls; and at least one of the sets of positions is a set of positions in which extension of the compaction end moves the compaction end generally towards one or more of the bottom edges of the mould.

6. A method according to claim 5 wherein at least one of the sets of positions is a set of positions in which extension of the compaction end moves the compaction end generally towards one or more of the corners of the mould.

7. A method according to any preceding claim further comprising using the robotic system to place a reinforcing bar onto the compacted semi dry stone mix before adding the additional semi dry stone mix, and wherein the reinforcing bar defines a longitudinal axis, and the robotic system reciprocally moves the reinforcing bar along its longitudinal axis while pushing it into the compacted semi dry stone mix.

8. A method according to any preceding claim further comprising using the robotic system to scrape excess semi dry stone mix from a top surface of the mould, optionally by running an edge of a compaction tool across the top surface using a manipulator.

9. A method according to any preceding claim further comprising using the robotic system to run a rake member across the compacted semi dry stone mix before the additional semi dry stone mix is added.

10. A method according to any preceding claim further comprising using the robotic system to slide a substantially flat surface across an exposed top surface of the compacted semi dry stone mix, with the substantially flat surface and exposed top surface being in substantially planar contact during said sliding, after all said compaction of portions of the semi dry stone mix has been completed.

11. A method according to any preceding claim wherein the mould containing semi dry stone mix is accommodated by a mould carrier in a set position relative to the mould carrier, the method includes a step of using a conveyor to convey the mould carrier to a set position in a conveying direction relative to a table at which a manipulator for moving the compaction tool is located, the method includes a step of causing the mould carrier and mould to move relative to the table to bring a set of formations of the table into engagement with a set of corresponding formations of the mould carrier, the method includes a step of clamping the mould carrier against a datum edge so as to restrict its movement in a direction transverse to the conveying direction, the mould carrier, and therefore the mould, thus being held in a fixed and preset position relative to the table and therefore also the manipulator at the table.

12. A method according to claim 11 , wherein the weight of the mould carrier and mould are supported by the conveyor as it conveys the mould carrier to the table,the step of causing the mould carrier and mould to move relative to the table is effected by lowering the conveyor, mould carrier and mould so as to transfer support of the weight of the mould carrier and mould from the conveyor to the table.

13. A method according to any preceding claim wherein the robotic system is controlled by a computer comprising a processor and memory, wherein the computer is arranged to control the movements of the one or more compaction tools according to a set of motions dictated by the shape and size of the mould, and wherein the method includes the computer selecting a particular set of motions, in preference to other sets of motions, in dependence upon an input to the computer that relates to the shape and / or size of the mould being used in the method.

14. A robotic semi dry cast stone moulding machine comprising: a mould support configured to support a mould; one or more compaction tools each having a mounting portion, a compaction end and an actuator arranged to extend and retract the compaction end along a compaction direction relative to the mounting portion; a manipulator attachable to the mounting portions of each of the one or more compactions tool and configured to move said one or more compaction tools relative to the mould support; and a controller operably connectable to the manipulator and each of the one or more compaction tools so as to control the movement of the manipulator and the or each compaction tool, wherein the controller is configured to: control the manipulator to move a compaction tool between a first set of positions relative to the mould support, and to control the actuator of that compaction tool to extend and then retract the compaction end in each position of the first set of positions so as to compact a portion of semi dry stone mix in a mould supported by the mould support; pause until signalled that additional semi dry stone mix has been inserted into said mould supported by the mould support, on top of the compacted portions; andcontrol the manipulator to move a compaction tool between a second set of positions relative to the mould support, and to control the actuator of that compaction tool to extend and then retract the compaction end in each position of the second set of positions so as to compact a portion of semi dry stone mix in a mould supported by the mould support.

15. A machine according to claim 14 wherein the machine is for performing a method according to any one of claims 1 to 13.

16. A machine according to claim 14 or 15 wherein: the mould support defines a length axis positioned to run between opposing end walls of said mould supported by the mould support; a width axis positioned to run between opposing side walls of said mould; and a depth axis; the depth axis is generally upright; the axes of the mould support are substantially perpendicular to one another; and at least one of the sets of positions is a set of positions in which the compaction direction has a component in the direction of the depth axis and a component in the direction of another axis of the mould.

17. A machine according to claim 16 wherein at least one of the sets of positions is a set of positions in which the compaction direction has a component in the direction of each of the axes of the mould.

18. A machine according to any one of claims 14 to 17 wherein: the machine further comprises a gripper tool which is configured to grasp and release a reinforcing bar; the gripper tool is attachable to the manipulator and movable thereby; and the controller is operably connectable to the gripper tool to control the grasping and realising of the reinforcing bar.

19. A machine according to any one of claims 14 to 18 further comprising a rake member configured to be raked across compacted semi dry stone mix.

20. A machine according to any one of claims 14 to 19 wherein the range of motion of the compaction end of at least one of the one or more compaction tools, relative to the mounting portion, is more than 50mm and is less than 500mm.

21. A machine according to any one of claims 14 to 20 wherein the actuator of at least one of the one or more compaction tools is arranged to extend the compaction end with a speed of the compaction end immediately before contact with the semi dry stone mix of more than 2ms'1and with a momentum of at least lOkgms'1.

22. A machine according to any one of claims 15 to 21 wherein the manipulator comprises a multi-axis robot arm controlled by two or more servomotors, and each of the one or more compaction tools is configured to fire the compaction tool towards the mould, in use, so that at the point of impact with the mix in the mould the servomotors are, at least in part, protected by decoupling of the compaction end and the manipulator.

23. A system for moulding semi dry cast stones including a moulding machine according to any one of claims 15 to 22 wherein the system comprises multiple mould carriers, each mould carrier being configured to hold and support a mould in a set position relative to a datum, and a conveyor for conveying the mould carriers to and from the manipulator.

24. A kit of parts for use in the system according to claim 23 wherein the kit of parts comprises multiple mould carriers and multiple moulds.

25. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to function as the controller of any of claims 14 to 22 and / or the computer of claim 13.

26. Ten or more identical moulded structures made using a method according to any of claims 1 to 13 or using the machine according to any of claims 14 to 22, using the same shape and size of mould.

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