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 2 comprises using a manipulator 44 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, and then retracted. The method further comprises adding additional semi dry stone mix into the mould on top of the compacted portions. The method further comprises using the 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 is in the mould, and then retracted. A machine for performing the method is also disclosed. The machine comprises at least one compaction tool and a controller 52 operably connectable to the manipulator to control the movement of the manipulator and the or each compaction tool.

Description

BACKGROUND 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. 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 the case of semi dry cast stone, however, the mix (which resembles damp sand in consistency) 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 side is produced, often being formed out of wooden boards clamped together to form a cavity. The cavity is often cuboidal m 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 top of 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 or building. 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, 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.

[0010] 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.

[0011] 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 inventors of the present application have 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.

[0012] 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 inventors of the present application have 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 used in a single position to compact the mix in all the areas of the mould at once.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Where the robotic system comprises more than one manipulator, the manipulators may be positioned adjacent to or opposite to one another.

[0023] 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.

[0024] Each set of positions may comprise at least two positions, at least three positions, at least four positions or at least five positions.

[0025] 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).

[0026] 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.

[0027] At least one of the sets of positions may be a set of positions in which the compaction direction is positioned substantially vertically.

[0028] 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.

[0029] Optionally: 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.

[0030] 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.

[0031] 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.

[0032] The comers 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.

[0033] 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).

[0034] 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.

[0035] 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.

[0036] As an alternative, the same compaction tool may be moved between all said sets of positions.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 stone mix 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] The edge of the compaction tool may be an edge of the compaction end of the compaction tool.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] This may improve the finish of the exposed top surface, giving that surface better aesthetics and / or water resistance in the finished product.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] 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.

[0059] 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.

[0060] 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 inventors of the present application have 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 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.

[0061] 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 inventors of the present application have 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.

[0062] 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.

[0063] 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.

[0064] 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).

[0065] A machine according to the second aspect of the invention may be for performing a method according to the second aspect of the invention.

[0066] 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.

[0067] 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 the actuator 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.

[0068] 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.

[0069] At least one of the sets of positions may be a set of positions in which the compaction direction is positioned substantially vertically.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] The machine may further comprise a rake member configured to be raked across compacted semi dry stone mix.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] This may reduce the risk of the compaction tool extending with insufficient force to properly compact the semi dry stone mix.

[0087] 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 lOOON.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] The actuator of at least one of the one or more compaction tools may be a pneumatic cylinder.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] At least one of the one or more compaction tools may have a resilient buffer positioned to limit extension of the compaction end.

[0100] The manipulator may be a robotic arm.

[0101] 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.

[0102] 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.

[0103] It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. DESCRIPTION OF THE DRAWINGS

[0104] 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 Figure 1; Figure 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 9A 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; and Figure 9D shows a further set of positions of a compaction tool relative to a mould. DETAILED DESCRIPTION

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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 is configured to move the compaction tool 42 relative to the mould support 4 (and thus relative to the mould 16).

[0109] 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. [OHO] 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.

[0111] 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.

[0112] 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.

[0113] 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 of maximum extension, the upper assembly 66 contacts the buffer 64 which prevents it from travelling any further but softens the impact.

[0114] 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. [0H5] 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. 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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 the gripper 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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 comers 40 of the mould. For example in position A the compaction 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 9A, 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, m the general direction of the top left corner 40 of the mould 19 from the perspective of Figure 9A.

[0127] 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 9 A, 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.

[0128] After the semi dry stone mix has been compacted into each of the corners 40 of the mould 16, 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.

[0129] 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 46 is extended and then retracted three times in each position A-I of the additional set of positions.

[0130] 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.

[0131] 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.

[0132] After compaction of the semi dry stone mix using compaction tool 42a, 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 as to 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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 retracted position. 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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

1. 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; andone 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; andremoving 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 anadditional 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; andat 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 wherein the compaction tool which is moved between one of said sets of positions is different to the compaction tool which is moved between another of said sets of positions.

8. 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.

9. A method according to claim 8 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.

10. 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.

11. A method according to claim 8 wherein the robotic system scrapes the excess semi dry stone mix by running an edge of a compaction tool across the top surface using a manipulator.

12. 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.

13. 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.

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; anda 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; andat 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 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; andthe 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 100mm.

21. A machine according to any one of claims 14 to 20 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 less than 300mm.

22. A machine according to any one of claims 14 to 21 wherein the actuator of at least one of the one or more compaction tools is arranged to extend the compaction end with a force of more than 400N.

23. A machine according to any one of claims 14 to 22 wherein the actuator of at least one of the one or more compaction tools is arranged to extend the compaction end with a force of less than 2000N.

24. A machine according to any one of claims 14 to 23 wherein the compaction end of at least one of the one or more compaction tools, and any other components of saidcompaction tool which move together with the compaction end relative to the mounting portion, have a total mass of more than 4kg.

25. A machine according to any one of claims 14 to 24 wherein 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, have a total mass of less than 40kg.

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