EP2323823B1

EP2323823B1 - Automated manufacturing of large scale shell structures in setting materials

Info

Publication number: EP2323823B1
Application number: EP09806897.6A
Authority: EP
Inventors: Jan Capjon
Original assignee: Hogskolen i Vestfold
Current assignee: Hogskolen i Vestfold
Priority date: 2008-08-13
Filing date: 2009-08-12
Publication date: 2013-09-25
Anticipated expiration: 2029-08-12
Also published as: EP2323823A4; PL2323823T3; DK2323823T3; EP2323823A1; WO2010019051A1

Description

The invention relates to structure manufacturing of shell structures in setting materials. In particular, the invention relates to construction of self-bearing shell-structures of such materials, such as concrete.
Manufacturing of self-bearing concrete structures by means of covering forms with a tempering concrete is known. For instance, patent application US 2005/0097830 describes such a method, in which the inside of an inflatable form is covered with concrete. In this way a dome-shaped building can be produced.
International patent application publication WO2005070657 , being the base of the preamble of claim 1, describes a system for automated construction with robotic systems. In this solution a setting material is extruded onto a previous layer of material, wherein a material nozzle is suspended from a gantry.
An example of a related form principle is described in EP 0233502 . Here, concrete is also internally applied onto an inflatable membrane form to produce a shell building, such as a dome.
In the prior art, the application of concrete onto such forms is performed manually. The concrete is either sprayed onto the form surface with a hand-held application device, or it can be sprayed or extruded onto the form with equipment, such as arranged on a concrete lorry. In the latter case, the application of concrete is mechanically performed, by controlling the equipment with handles and switches etc. Either way, the final quality of the self-bearing structure is directly depending on the experience and skills of the operator.
When using an inflatable form as in the above-mentioned publications, one must ensure that the periphery of the inflatable form is properly oriented. To remedy this, patent publication US 5918438 proposes a foundation method to keep the form periphery to the ground.
According to the present invention, there is provided a system for computer-controlled construction of large-scale self-bearing shell structures in a setting material having dimensions larger than 1 meter, preferably larger than 10 meters. The system comprises

a self-contained unit comprising
a material supply system, comprising
a material tank and a material pump and furthermore
a material dispensing nozzle and a manipulation arm onto which said nozzle is arranged, wherein said supply system is adapted to feed the setting material to the nozzle;
a plurality of computer-controlled actuators controlling said manipulation arm and dispensing of material; and
a traverse crane carrying said unit;
wherein said unit is adapted to be computer controlled according to a CAM-pattern (computer aided manufacturing) stored in a computer-readable storage medium;
wherein said nozzle is movable in a substantially arbitrary path within a predetermined operation section, and is adapted to dispense material in substantially any arbitrary direction, by means of said dispensing nozzle (22) and manipulation arm.

the unit, the supply system, the dispensing nozzle, and the manipulation arm, are suspended from the traverse crane and the tank is suspended from the traverse crane or adapted to move with the bogie of the same.

With such a system, one can produce shell structures, preferably in concrete, with a significantly more accurate thickness and quality than with the methods of the prior art. This is due to the computer-controlled nature of the method, eliminating randomness in the application process. Making the method computer controlled results in a full control of how much concrete that has been applied, where it has been applied and at what time (which is important with regard to the hardening period). This will further result in that one does not have to apply more concrete than necessary "just to be sure", and that no areas of the shell structure has been provided with too little concrete.
When constructing building structures, as the domes known from prior art, these advantages are indeed important. However, when constructing more sophisticated shell structures, the importance of these features increases. For instance, if the method according to the first aspect of the invention is used to manufacture floating structures such as sea farm or boat hulls, the above-mentioned features are important to ensure the structure's floating characteristics. The thickness of the hull is of course very important, as is the material or weight distribution of the hull, which must be controlled. The method according the first aspect of the invention ensures that the final product corresponds with the intended one. Corresponding advantages exist when constructing products such as tanks for liquids or chemicals.
Furthermore, by elevating the tank or mixer (hereinafter referred to as "tank") up to the level of the traverse crane, another advantage is achieved in that the pressure material in the nozzle is higher than it would be if the tank was arranged on the floor. Or, alternatively, one may use a smaller pump in order to provide the desired pressure in the nozzle.
Another advantage is that one save valuable floor space.
Preferably, the system comprises at least one sensor for measuring the distance and/or angularity to the form surface, wherein misalignment between said measurement and expected values according to a 3D CAD-model can be adjusted for on the basis of said measurement.
The structures can be made of one or a plurality of material layers. The form can be dismantled already after a first layer of material or concrete has been tempered. Thus, the same form can be used for the start-up of construction of a further structure while the original one still is in production.
According to the invention, with the system, one can apply material or concrete according to a CAM-pattern (computer aided manufacturing) stored in a computer-readable storage medium. Thus, one can easily design and adjust structure thickness with a computer interface according to needs without having to perform adjustments to the hardware such as the form or robotic unit. This gives process flexibility.
By arranging the system with a traverse crane it can advantageously be employed in a production hall, such as a shipyard. Such an arrangement will result in a large working area of the system and it can for instance be used for the parallel production of shell structures, even different structures. An arrangement of the system as a self-contained construction could also allow many other applications than crane suspension.
In an especially preferred use of the system according to the invention, air, e.g. in the form of polystyrene spheres, and preferably fibre reinforcements, can be intermixed in the concrete. This process step can be performed to avoid preassembled reinforcements and to reduce specific weight.
In another preferred embodiment, the distance between the nozzle and the surface onto which concrete is to be applied is measured by means of at least one sensor, wherein said measurement is used to adjust for misalignment between measured distance and a theoretical distance of a CAD model. Thus, any misalignment between the calculated application pattern according to the computer (which controls the motors) and the actual position of the form surface can be adjusted.
Preferably, the system can be used in connection with controlling software adapted to minimize time of production of a predetermined structure, as it keeps record of material thickness and tempering time of various material-coated layer areas.
In this description is also described a flange form for moulding of a flange along the periphery of an inflatable form of the type that is adapted to be coated with a tempering construction material for self-bearing shell construction. The flange form comprises

a first band arranged in a substantially upright position along the periphery of an inflatable form, in a position where a part of said form extends radially outward of said first band;
a flange band attached to said periphery of the inflatable form;
a plurality of orientation devices comprising supporting means to support the first band and the flange band in a substantially upright position;
a facing wall element supported in an upright position and making an outer mould wall, wherein the facing wall element and said flange band define a mould between them.

Preferably, the flange band is provided with protrusions extending into the flange, the protrusions being adapted to absorb vertical forces between the flange band and the flange and to be releasable from the flange after deflation of the inflatable form.
In one preferred embodiment, a six axes production robot can be created through adding to it a four axes specialised robotic unit with a base assembly rotating around a vertical and a horizontal axis, a stiff up and down movement and a forming head rotating around a horizontal axis. Preferably, all movements are driven through actuators, preferably electric gear motors or drives with motor controls that detect number of revolutions and supply data to a central computer - including similar control devices for the crane drives. The unit is suspended in the traverse crane (which has two axes movements less the vertical hoist).
A concrete with appropriate pumping, adhesion, hardening, and strength properties is preferably supplied from a tank and pump unit under pressure through a flexible and adjustable hose and is sprayed or extruded through a nozzle fastened to the forming head.
The concrete is preferably applied layer-wise onto a form. Such forms can be made from conventional form materials, like for instance flat or singly curved plates, or from glass reinforced unsaturated polyester (GUP) for double curvature geometry - and with negative configuration (like for plastic boats with high quality external surfaces) or positive configuration (like for tanks with high quality internal surfaces). But in order to obtain a more efficient, flexible and cheap overall process than conventional forms can support, the present invention suggests a preferable integration of an inflatable membrane form in the process. Forms can be of double curvature (like in EP 0233502 ) or of single (sausage-like) curvature or combinations. If the concrete is applied externally instead of internally, the form can in principle be deflated, demounted and reused for a new production run when the concrete is hardened - instead of being left as an external shell.
A lift-off-the-floor problem complicates an internal inflatable form application in an effective process. Inflatable form structures are readily made from plastic sheets that are welded together in single or double curvatures of multiple possibilities. For instance part-sphere-shaped forms, such as a hemisphere, are preferably made from one (floor) sheet and many semi elastic sheets welded into a double curvature dome form - with a welded main flange along the circumference. When such a structure is inflated, the welded flange will undesirably lift from the floor because of material elasticity. Sausage-like structures will have the same problem. Circumference bolting or weighting of the flange to the floor are undesirable solutions in effective production scenarios because of need for floor holes or heavy weights.
A solution to the lift-off-the-floor problem is based on prefabrication of a necessary product flange and the employment of this product flange to weigh down the form when inflated without need for floor bolts. However, according to this aspect of the present invention, the flange form is designed to be removable and flexibly adaptable to a membrane form that can be removed after concrete tempering. A flange form is suggested, which is accurately adaptable to realistic flange geometries and which fastens the foil form to the flange in a way that allows the flange to weight the membrane form, but still is easily detachable after deflation. The flange form comprises flexible bands and adjustable connection hoops. This will be further explained later.
Application of concrete to physical forms can advantageously involve a process where form surfaces can be used to control 3D CAD model trajectories. One or more sensors attached to the application device can measure the distance to the surface, through which data the computer can control distance and angularity to a tangent plane at the point of concrete application, regardless of small system deformations. Laser, infrared or ultrasound sensors can be used. Thus, the distance to the form surface to be sprayed and the angle of incidence can be fully controlled according to various variable parameters, such as concrete properties. It should be noted that the invention is not restricted to spraying the concrete. It could also be extruded or otherwise applied onto the form through a nozzle.
A more detailed explanation of the advantageous features according to the present invention is given below with an example of embodiment. Here, a system and constructive elements according to the embodiment of the present invention is outlined with reference to the drawings, in which

FIG. 1: depicts a cross section of a production hall with a traverse crane that is supplied with a specialised robotic unit of four axes in partly extended position vertically.
FIG. 2: shows a tilted position of the specialised unit, in this assembly supplied with a tank unit running on separate wheels.
FIG. 3: shows an enlarged side view of the production assembly of FIG. 1, where the extension device is stiffly fastened to the crane's bogie by means of its hook and with a concrete supply system integrated.
FIG. 4: shows a front view of the assembly in FIG. 3.
FIG. 5: shows an enlarged section view of a form system for prefabrication of product flanges for weighting and orienting forms made from inflatable membranes.
FIG. 6: shows a further enlarged section view of one side of the FIG. 5 section.
FIG. 7: shows a section view corresponding to the upper part of FIG. 2, illustrating an alternative manner to arrange the robotic unit and the concrete tank.

In the figures, reference number 1 depicts a standard traverse crane (a two beam version is drawn) where a bogie 2 is running on wheels 3 (Figs. 3, 4), driven by a geared electric motor 4 (Fig. 3) on a horizontal track 5. In the length dimension of the hall the traverse is driven by synchronised geared electric motors 6 with drive wheels 7.
Onto the bogie 2 is fastened a specialised robotic unit consisting of several parts. In FIG. 7, the robotic unit is suspended on the same beams as the traverse crane, with means for releasably attachment to the traverser carriage. Referring to Figs. 3 and 4, e.g. four tubes, 10, 11, 12 and 13 are telescoping within each other. The three tubes 11, 12 and 13 are run up and down by geared electric motors 15, 16 and 17. On the lower end of tube 13 is connected a robot forming head 18, which is rotated around a horizontal axis by a gear motor 20 and holds an application device 21 with a nozzle 22 and distance sensor(s) 23. The specialised robotic unit is in FIGs 1, 3, 4 connected to a concrete tank 25 onto which a horizontal turning unit 26, driven by a gear motor 27 and rotating round a vertical axis is fastened. Onto the unit 26 brackets 28 are fastened, which connect the largest tube 10 to axle 29. The movement of 10 (and connected tubes) around the axle 29 is driven by a gear motor 30 and a chain or gear 31. In FIG. 2 a concrete tank and pump unit 32 is detachably connected to the bogie 2 and is running on the traverse on separate wheels 33. In FIG. 7, the robotic unit is directly connected to a concrete tank, and it can be parked at the end of the beams by detaching it from the boggie. The traverse crane can be used as a crane as such.
Preferably, all parts of the specialised unit are moving in high tolerance bearings according to standard robot specifications. All electric gear motors (4, 6, 15, 16, 17, 27, 30) are advantageously equipped with revolution counters that register number of revolutions forwards and backwards and are connected to a central computer and power supply 34 controlling the robot sequences.
At need for shorter telescopic arm, e.g. the tube 13 with motor 17 can be removed, and the forming head assembly 18, 20, 21, 23 can be connected to the tube 12.
Onto this specialised robotic unit can be fastened a concrete supply system which comprises a tank 25 with a pump 35 that can feed concrete from the tank 25 to a spring loaded storing drum 36. The drum 36 coils in and out a hose 37 that supplies concrete to the nozzle 22, where it is sprayed or extruded under pressure. The pump 35 is supplied with a valve and tube system that can allow pumping in upside-down position as well. The said valve and tube system is adapted in such a way that when the robotic unit is suspended, for instance as shown in Figs. 3 and 4, the pump 35 will be fed with concrete in the lower part of the tank 25, in the position of the pump 35. However, when the unit is arranged for instance on a trolley, it is preferably turned upside down. The pump 35 will then be fed through the tube 38, ensuring that the pump 35 is fed even if the tank 25 is almost to empty.
Referring again to Figs. 3 and 4; if the specialised robotic unit is connected to a crane, it can be connected by means of the crane's hook 40, which lifts it up by a flexible lifting hoop 41 onto four orientation peaks 42 at the lower end of brackets 43 connected to the bogie 2. If the unit is not in use, it can be parked in special brackets 45, for instance at the end of the hall, as drawn stippled and retracted (46) in FIG. 1.
In a 'filling or cleaning position' in the hall, the bogie with connected tank 25 (or 32 in FIG. 2) can be placed directly underneath a filling point, where concrete is pumped into the tank from a mixing station. Then the device with full tank is driven to an action point, empties its content by spraying, as described, and returns to filling position to repeat the sequence. Devices for cleaning can also be placed at such a location.
In addition to overall process rationality, an advantage with the computer controlled application of the concrete, as provided with the present invention, is that one will obtain control of the thickness of the applied layer. If the layer is applied manually, as is known from the prior art, the layer will be applied with non-uniform thickness. Yet another advantage of the computer controlled application is that the computer keeps record of when the layer was applied. The computer will thus know how long the layer has hardened. According to concrete characteristics, the computer will then be able to optimize the time for when it can apply an additional layer on top of the previous. For instance, it can commence with a new layer while a distant area of the previous layer is still tempering.
The concrete can for instance be specialised concrete composites, with or without armature or fillers. Forms or moulds are necessary as bases for creating desired product geometries - as (internal or external) support structures onto which concrete is sprayed or extruded. The concrete is applied onto the form and hardens on form surfaces. Resulting products can be loosened from the forms when hardened - or membranes can be left in external configurations.
In FIG. 1, 57 depicts a negative form for a boat (high quality external surface), 58 depicts a positive mould for e.g. a tank (high quality inside and rough outside), and 59 depicts a form for a flat product, e.g. for prefabrication of building elements.
The form 60 illustrates a form technology which is focused in this application as integral part of a rational overall process: an inflatable form made from plastic membranes, basically as welded sphere sections or cylinder sections or combinations - with welded flanges at maximum circumference. The drawn membrane form is intended to be removed inwards after external spray-moulding of walls. Fig. 5 shows a cross section of the described flange form solution for form 60. One hoop consists of two orientation devices 61, one connecting tube 62 and two adjustment screws 63. Such hoops are preferably placed at approximately equal intervals along the welded flange of a deflated foil form. Two thin bands 65 and 66 are entered from rolled-up spools vertically into the jaws 67 of the orientation devices 61 - thereby making a form for moulding a product flange 68. The bands 65, 66 can e.g. be made from thin hardened stainless steel and will in vertical position have good strength sideways, particularly when slightly curved corresponding to the inflated rounded form.
The product flange form is to be placed on top of the inner edge along a flange of an (at first) deflated membrane form - and the plastic flange should be tilted upward. The up-tilted flange is drawn in FIGs 5 and 6, where 70 is the upper foil and 71 is the lower foil of a welded part-sphere-shaped plastic form 60. 73 is a plastic flange band (e.g. extruded) which is welded to 70 and 71 at its base 74. On one side are placed pointed barbs 75 that point inwards after up-tilting of the flange band 73 and 'parking' it into jaw 67. When tilted upwards in this position all around the plastic form 60 periphery and adjusted to its length, the flange form is ready for moulding of the product flange 68. This flange will be needed as rim of the final product - and can be roughly dimensioned for strength and weighting purposes - e.g. with armature sticking up for anchoring of the wall. After flange 68 hardening, the hoops (61, 62, 63) can be removed and the arrangement is ready for spray-moulding of walls by the robot assembly. When the plastic form is inflated with an air pump, the upper foil 70 will press against the inner band wall of the flange form and thereby secure the vertical connection between the barbs 75 and the material of the product flange 68. The product flange will weigh down the plastic form when inflated as intended - and can be supplied with additional weights at need. The form is easily disassembled inwards when the plastic form 60 is deflated and the barbs 75 are retracted from their dents in the flange 68.

Claims

System for computer-controlled construction of large-scale self-bearing shell structures in a setting material having dimensions larger than 1 meter, preferably larger than 10 meters, wherein the system comprises
- a self-contained unit comprising
- a material supply system comprising

- a material tank (25) and a material pump (35); and furthermore

- a material dispensing nozzle (22) and a manipulation arm (10, 11, 12, 13) onto which said nozzle (22) is arranged, wherein said supply system (25, 35) is adapted to feed the setting material to the nozzle (22);

- a plurality of computer-controlled actuators (15, 16, 17, 26, 30, 35) controlling said manipulation arm (10, 11, 12, 13) and dispensing of material; and

- a traverse crane (1) carrying said unit;

- wherein said unit is adapted to be computer controlled according to a CAM-pattern (computer aided manufacturing) stored in a computer-readable storage medium;

- wherein said nozzle (22) is movable in a substantially arbitrary path within a predetermined operation section, and is adapted to dispense material in substantially any arbitrary direction, by means of said dispensing nozzle (22) and manipulation arm (10, 11, 12, 13);
characterized in that
- the unit, the supply system (25, 35), the dispensing nozzle (22), and the manipulation arm (10 ,11, 12, 13), are suspended from the traverse crane (1) and the tank (25) is suspended from the traverse crane (1) or adapted to move with a bogie (2) of the same.
System according to claim 1, characterized in that it comprises at least one sensor (23) for measuring the distance and/or angularity to a form surface, wherein misalignment between said measurement and expected values according to a 3D CAD-model is adapted to be adjusted for on the basis of said measurement.