EP1431015A1 - Process for making reinforced concrete beams and installation for the execution of this process - Google Patents

Abstract

The method of fabrication of cast concrete beams (1) involves preparing prefabricated assemblies (5) including armature cages (2) which are positioned with respect to each other to suit the functions of each beam to be made. The pre assembled cages are positioned in the moulds and the concrete poured in. After drying the beams are demoulded and passed to store. Claims include an installation for moulding beams using the method.

Description

The present invention relates to a method for manufacturing concrete beams obtained by molding in a molding bench. The invention also relates to a installation implementing this process and comprising at least one zone of molding provided with a molding bench.

Concrete beams, generally used in building and civil engineering, are usually reinforced concrete beams, in this case the concrete is reinforced by metal reinforcements, or prestressed concrete beams, in this case, the concrete is, in addition, under stress by prestressing cables stretched during the phase molding then slackened after hardening of the concrete.

Conventionally, the molds used for the manufacture of this type of beams extend over a great length, for example from 60 to 120 meters, and are cut each in a number T of longitudinal sections, by means of dividers or formwork combs, for the manufacture of a number T of beams forming a together. These molds are brought together in a molding bench, which has a number M of molds parallel to each other, which may have different sections. So, each molding bench allows the simultaneous production of an M number sets of beams, which may have different lengths and sections. So far, each mold is prepared individually and manually by a or several operators who install the reinforcement cages and the spacers or formwork combs at locations defined according to the length of the reinforced concrete beams to be manufactured, as described for example in publication EP-A-0 606 794. For prestressed concrete beams, they add cables of prestress which extend over the entire length of the molds and which are pulled by a tensioning device, as described for example in publication WO-A-97/18070.

To carry out these preparatory operations, the operators work bent over molds, which is a very uncomfortable position, causing fatigue premature and musculoskeletal disorders. This work is therefore very long and tedious. In addition, it monopolizes the molding bench for long periods, these downtimes being variable depending on the complexity of the beams to manufacture. When installing the prestressing cables in the molds, these cables not under tension are in contact with the demoulding oil present in the bottom and on the walls of the molds, which can be detrimental for technical performance of finished products. The installation of reinforcement cages and formwork dividers being manual, the precision of their positioning is relative and not reproducible.

During the production of prestressed concrete beams, after pouring and hardening concrete, the prestressing cables are released and then cut inside the mussels, either with a blowtorch or with a circular saw, with all the risks and difficulties this represents: difficult access, deterioration of the mold walls, heavy soiling, danger to the operator, etc. The finished beams are then unmolded one by one which, added to the previous tasks, immobilizes the bench molding over a very long period of time. The current manufacturing process does not allow not to consider optimal management of the production tool, nor better working conditions for operators.

The present invention aims to overcome these drawbacks by proposing a new semi-automated or automated manufacturing process, which eliminates tasks tedious related to the handling of heavy elements and difficult work positions, guarantees precise fabrication of the frames, offset outside the molding bench preparation operations before molding and treatment after molding and this reduces the downtime of the molding bench, allows great production flexibility and optimizes the overall performance of the installation manufacturing.

a) on prépare, en dehors dudit banc de moulage, au moins un ensemble d'éléments pré-assemblés comprenant au moins les cages d'armature entrant dans la fabrication de ladite poutre, ces éléments étant positionnés l'un par rapport à l'autre à des emplacements prédéterminés en fonction de la poutre à fabriquer,

b) on prélève cet ensemble d'éléments pré-assemblés d'un seul tenant à l'aide de moyens de préhension pour le déposer à l'intérieur dudit moule,

c) on coule le béton dans ledit moule,

d) après durcissement du béton, on démoule ladite poutre fabriquée d'un seul tenant à l'aide desdits moyens de préhension, puis

e) on l'évacue vers une aire de stockage.

To this end, the invention relates to a manufacturing process of the kind indicated in the preamble, in which the molding bench comprises at least one mold arranged to allow the manufacture of at least one beam, characterized in that it comprises at least the following steps, at least one of which is carried out semi-automatically or automatically:

a) at least one set of pre-assembled elements is prepared, apart from said molding bench, comprising at least the reinforcing cages used in the manufacture of said beam, these elements being positioned one relative to the other at predetermined locations depending on the beam to be manufactured,

b) this set of pre-assembled elements is taken in one piece using gripping means to deposit it inside said mold,

c) the concrete is poured into said mold,

d) after the concrete has hardened, said beam, which is manufactured in one piece, is removed from the mold using said gripping means, then

e) it is evacuated to a storage area.

For this purpose, the invention also relates to a manufacturing installation of the kind indicated in the preamble, characterized in that it comprises at least one zone of preparation arranged outside said molding zone in which are prepared pre-assembled elements comprising at least the reinforcement cages entering the manufacture of said beams, these elements being positioned relative to the others at predetermined locations depending on each beam to be manufactured, said pre-assembled elements constituting at least one assembly intended to be taken in one piece by gripping means to be placed in the bench molding before pouring concrete.

• les figures 1A et 1B représentent en perspective, respectivement, un exemple de poutre réalisée par le procédé et l'installation selon l'invention et un exemple de cage d'armature entrant dans la fabrication de cette poutre,
• la figure 2 représente une installation selon l'invention en vue de dessus,
• la figure 3 représente l'installation de la figure 2 en coupe transversale,
• la figure 4 représente la zone de préparation des cages d'armature en vue de côté,
• la figure 5 représente les moyens de préhension des cages d'armature en vue longitudinale, et
• les figures 6A à 6C représentent les dispositifs de traction des câbles de précontrainte respectivement en vues partielles de côté en position de repos et en position de travail et en vue de face.

The present invention and its advantages will appear better in the following description of an embodiment, given by way of nonlimiting example, with reference to the appended drawings, in which:

• FIGS. 1A and 1B show in perspective, respectively, an example of a beam produced by the method and the installation according to the invention and an example of a reinforcement cage used in the manufacture of this beam,
• FIG. 2 represents an installation according to the invention in top view,
• FIG. 3 represents the installation of FIG. 2 in cross section,
• FIG. 4 represents the area for preparing the reinforcement cages in side view,
• FIG. 5 represents the means for gripping the reinforcement cages in longitudinal view, and
• FIGS. 6A to 6C show the traction devices of the prestressing cables respectively in partial side views in the rest position and in the working position and in front view.

With reference to the figures, the installation 10 according to the invention makes it possible to manufacture reinforced concrete or prestressed concrete beams, of sections and lengths different. In the first case, the beams are reinforced by reinforcements metallic only, whereas in the second case, these beams are additionally placed under stress by metallic prestressing cables. Figure 1A illustrates a example of a prestressed concrete beam 1, reinforced by reinforcement cages 2 and stressing by prestressing cables 3. The beam 1 as illustrated has a substantially rectangular section, given by way of example not restrictive, this section can be square, frustoconical, T-shaped or any other section suitable for molding.

This installation 10 makes it possible to implement a new manufacturing process in which the beams 1 are manufactured by molding in a molding bench 40 comprising several molds 41 and the length of which makes it possible to manufacture in each mold 41 several beams 1, hereinafter called a set of beams 1.

• on prépare, pour chaque moule 41 et en dehors dudit banc de moulage 40, un ensemble d'éléments pré-assemblés 5 comprenant notamment des cages d'armature 2 (cf. fig. 1B), des câbles de précontrainte 3, des intercalaires de coffrage 4 et des pièces d'ancrage 6 (cf. fig. 5 et 6), ces éléments 2, 3, 4, 6 étant positionnés les uns par rapport aux autres à des emplacements prédéterminés en fonction dudit ensemble de poutres 1 à fabriquer,
• on prélève ledit ensemble d'éléments pré-assemblés 5 d'un seul tenant par des moyens de préhension 31 pour le déposer à l'intérieur dudit moule 41,
• on répète cette opération autant de fois qu'il y a de moules 41 à garnir,
• on met sous contrainte les câbles de précontrainte 3,
• on coule le béton dans les moules 41,
• après durcissement du béton, on démoule les ensembles de poutres 1 fabriqués l'un après l'autre d'un seul tenant par lesdits moyens de préhension 31,
• puis, pour chaque ensemble de poutres 1, on sectionne les câbles de précontrainte 3 entre deux intercalaires de coffrage 4 consécutifs pour séparer les poutres 1 les unes des autres avant de les évacuer vers une aire de stockage.

This new process is described for the production of prestressed concrete beams 1, but of course extends to the manufacture of reinforced concrete beams. It is characterized by the fact that:

• for each mold 41 and outside said molding bench 40, a set of pre-assembled elements 5 is prepared, comprising in particular reinforcement cages 2 (cf. FIG. 1B), prestressing cables 3, spacers of formwork 4 and anchoring parts 6 (cf. fig. 5 and 6), these elements 2, 3, 4, 6 being positioned relative to each other at predetermined locations as a function of said set of beams 1 to be manufactured,
• said set of pre-assembled elements 5 is removed in one piece by gripping means 31 to deposit it inside said mold 41,
• this operation is repeated as many times as there are molds 41 to be filled,
• the prestressing cables 3 are put under stress,
• the concrete is poured into the molds 41,
• after the concrete has hardened, the sets of beams 1 are produced one after the other in one piece by said gripping means 31,
• then, for each set of beams 1, the prestressing cables 3 are sectioned between two consecutive formwork spacers 4 to separate the beams 1 from each other before evacuating them to a storage area.

For the manufacture of reinforced concrete beams, the prestressing cables are omitted and, consequently, the operation of stressing these cables before molding then cutting these cables after demolding.

To implement this method, the installation 10 includes several work areas and in particular a preparation area A of sets of pre-assembled elements 5, a molding zone B of the beams 1, an evacuation zone C of the beams 1 manufactured (see fig. 2 and 3). This installation 10, and more particularly the area of preparation A, is automated and controlled by one or more machines receiving computer data from a design office relating to the different beams 1 to make (length, section, number and location of reinforcement cages 2, number of prestressing cables 3, location of formwork spacers 4 and anchors 6, etc.).

The molding area B comprises a molding bench 40 of reduced length by compared to conventional molding benches, for example from 30 to 70 meters instead of 100 to 150 meters. This molding bench 40 comprises several parallel molds 41, of different sections, mounted on 40 'foundations (see fig. 2 and 3). This arrangement particular gives this molding bench 40 great flexibility in management of production to simultaneously realize beams 1 of sections and lengths different. Of course, the number of molds 41 can be different, as can their section and their length. These molds 41 can also be adjustable in width and / or depth by means of movable walls.

The preparation zone A makes it possible to prepare, outside the molding bench 40, in parallel to it and at breast height, sets of pre-assembled elements 5 extending over the entire length of this molding bench 40. Each set of pre-assembled elements 5 corresponds to one of the molds 41 and includes a arrangement of reinforcement cages 2, formwork spacers 4, anchoring parts 6 and prestressing cables 3 determined according to the beams 1 to be manufactured.

This preparation zone A includes, in the example shown, a frames 20 which is a standard machine for automatically manufacturing frames 2a used in the composition of the reinforcement cages 2. These frames 2a are made by bending a metal wire, for example in the shape of a rectangle. This frame machine 20 is fed by a reel 21 carrying four bobbins 22 of wire metal with different diameters, for example 6, 8, 10 and 12 mm. By type of beams 1 to be manufactured, the frame machine 20 will automatically use one or the other diameter of metal wire to make frames 2a of dimensions and different strengths depending on the beams 1 to be manufactured.

The preparation zone A comprises another reel 23 carrying three reels 24 of metallic wire of the same diameter, for example 5 mm. These three sons constitute mounting frames 2b used in the composition of the frame cages 2. They are unwound simultaneously and positioned parallel, for example, in a triangle to be welded, by a welding machine 25, on three sides of the frames 2a of the same reinforcement cage 2. A conveyor belt 26 disposed between the frame machine 20 and the reel 23 allows the frames 2a to be brought to an operator who grasps the frames 2a one after the other and presents them next to the welding machine 25 (see fig. 4). The intervals between the parallel frames 2a of the same reinforcement cage 2 are indeed understood defined for each beam 1 to be manufactured. If the beams 1 to be manufactured have a length less than or equal to 8 meters, for example, we will make a cage of reinforcement 2 per beam 1. If their length is greater than 8 meters, we will realize two, or even three, reinforcement cages 2 per beam 1.

When a reinforcement cage 2 is completed, it is transferred to a mat. preparation 28 by a supply chain 27 (cf. fig. 4). This preparation mat 28 extends parallel over the entire length of the molding bench 40 and receives the cages of reinforcement 2 aligned one behind the other, as they are finished, and in the exact order of their intended position in the mold 41 corresponding. During this operation, the formwork spacers 4 and the anchor pieces 6 (cf. fig. 6) are interposed between the reinforcement cages 2, their handling being for example carried out by a lifting beam (not shown) placed at the start of the preparation mat 28. Next, prestressing cables 3 are threaded through reinforcement cages 2, formwork spacers 4 and parts anchor 6 over the entire length of the preparation mat 28. The installation of these prestressing cables 3 can be carried out either manually or semi-automatically, either automatically using a specific machine which does not not the object of the present invention. We obtain, after the installation of these cables prestress 3, a set of pre-assembled elements 5 corresponding to a mold 41 determined. The formwork spacers 4 make it possible to delimit the beams 1 between them in the same mold 41 and for example consist of a perforated metal plate whose number of holes corresponds to the number of cables prestressing 3. The anchors 6 are used both for transport of said assembly 5, between the preparation A and molding B zones, and for the attachment of the prestressing cables 3 to the traction devices 50, 51 provided on the molding bench 40. They are for example made of metal combs.

The arrangement of this preparation area A is designed to allow the operator to work in good ergonomic conditions, the conveyor belts 26 and preparation 28 being located at breast height, and to avoid any handling, the advancement of the reinforcement cages 2 being controlled manually by button push, without physical effort.

The set of pre-assembled elements 5 is then routed into the mold 41 adequate, in a single operation, by specific gripping means 31 attached to the anchoring pieces 6. These gripping means 31 are suspended from a spreader 30, the latter being movable in translation along the three axes X, Y, Z on a traveling crane (see fig. 3 and 5). These gripping means 31 are arranged to lift in one piece each set of pre-assembled elements 5 in it applying tension to tension the prestressing cables 3, avoid buckling and facilitate its positioning in the mold 41 as well as the introduction of said cables prestress 3 in the traction devices 50, 51 described below. The bridge rolling spans the preparation A and molding B zones to allow gripping means 31 to pass easily from one to the other zone A, B and C.

During this transfer operation, a new set of pre-assembled elements 5 can be prepared in preparation area A to garnish another mold 41.

When the molding bench 40 is ready, that is to say that the mold (s) 41 are furnished with sets of pre-assembled elements 5, the prestressing cables 3 are laid in tension by traction devices, commonly called headers 50, 51, arranged at the ends of the molds 41 in suitable pits 42 provided in the foundations 40 '(cf. fig. 6A-6C). For each mold 41, at least two are provided headers 50, 51: a fixed head 50 and a head 51 movable in rotation around a pivot 52 secured to the foundations 40 'between a rest position (cf. FIG. 6A) in which it exerts no traction on the prestressing cables 3 and a working position (see fig. 6B) in which it exerts traction on these cables prestress 3 in the direction of their length. Depending on the width of the molds 41, one can provide headers 50, 51 of different width and power. Rooms anchor 6 of the sets of pre-assembled elements 5 provided at the ends making it possible to block the prestressing cables 3 in the headers 50, 51. These headers 50, 51 are designed to allow automatic threading of the cables prestress 3 by vertical movement from top to bottom and unthreading by a reverse movement. They are formed of parallel, vertical, 53 strips separated by intervals 54 allowing the introduction of a prestressing cable 3 by interval 54 (cf. fig. 6C). This new design saves time very important and an automation of the threading. In comparison, in the headers conventional, prestressing cables are threaded manually and individually in through holes. When the prestressing cables 3 are placed in the two headers 50, 51, the mobile headers 51 are set in motion each by a jack 55 of force, articulated at its two ends between a pivot 56 secured to the foundations 40 ′ and a pivot 57 secured to the header 51. A removable stop 58 allows limit the stroke of the movable head 51, this stop 58 being actuated by another actuator 59. The movable headers 51 allow partial tension of the prestressing cables 3, for example from 30 to 50% of the total tension. Setting final tension is carried out unitarily on each prestressing cable 3 at for example by means of a single-wire cylinder.

When all these preparatory operations are completed, the concrete is poured into the molds 41. After hardening of the concrete, the movable headers 51 return to their rest position to release the tension on the prestressing cables 3 and the demoulding of beams 1 can begin. Each mold 41 is demolded into a single operation by the gripping means 31 of the lifter 30 which raises by alone holding all the beams 1 and depositing it on means of transport 60 provided in evacuation zone C. For this purpose, handling hooks (not shown) are provided in the upper part of the beams 1 for hanging the means gripping 31 of said lifter 30.

The means of transport consist, in the example shown, of a carriage evacuation 60 of the same length as the molding bench 40 and placed in parallel, between this molding bench 40 and the preparation mat 28 (cf. fig. 2 and 3). This cart discharge 60 is movable longitudinally for example on rails 61. It moves in front of a cutting station 62, where the prestressing cables 3 are cut between the successive beams 1, to separate the beams 1 from one another by same together. The cutting station 62 may include a torch, a saw circular, a chainsaw or any other suitable means. According to their length, beams 1 can be routed transversely to a post evacuation 63 or longitudinally towards the outside of the building for example, where the beams 1 are stored on a storage area (not shown), either in bundles on pallet, or individually depending on their length.

It is clear from this description that the manufacturing process according to the invention and the installation implementing this process make it possible to improve considerably at the same time the working conditions of the operators, the productivity of the production tool and the quality of the beams 1 manufactured. Indeed, all tasks painful inherent in traditional manufacturing are eliminated. The cables of prestress 3 being housed inside the reinforcement cages 2 and pretended during their placement in the molds 41 does not risk coming into contact with the oil mold release covering the bottom and the walls of the molds 41. The manufacture of reinforcement cages 2 being offset outside the molds 41 and assisted by computer ensures very good accuracy. Lack of intervention at risk such that cutting the prestressing cables 3 in the molds 41 makes it possible to preserve them and avoid soiling. Finally, the use of molds 41 being perfectly optimized since all the preparation and processing of the finished products is carried out outside the molding bench 40, this is only occupied during the pouring of the concrete and its hardening. It is therefore possible to perform a maximum number of rotations and make profitable the financial investment of the installation optimally. Another benefit also lies in the flexibility of production thanks to the reduced length of the molding bench 40 and the variety of molds 41 possible. This installation 10 can therefore respond quickly to market demand even for very small series, both for prestressed concrete beams and for reinforced concrete beams.

The present invention is not limited to the embodiment described but extends to any modification and variant obvious to a person skilled in the art while remaining within the scope of protection defined in the appended claims.

Claims (18)

Method for manufacturing concrete beams (1) obtained by molding in a molding bench (40) comprising at least one mold (41) arranged to allow the manufacture of at least one beam (1), characterized in that it includes at least the following steps, at least one of which is carried out semi-automatically or automatically: a) at least one set of pre-assembled elements (5) comprising at least reinforcement cages (2) used in the manufacture of said beam (1) is prepared, apart from said molding bench (40), these elements (2, 3) being positioned relative to each other at predetermined locations depending on the beam (1) to be manufactured, b) this set of pre-assembled elements (5) is removed in one piece using gripping means (31) and it is deposited inside said mold (41) c) the concrete is poured into said mold (41), d) after the concrete has hardened, said beam (1) is unmolded in one piece using the gripping means (31), then e) it is evacuated to a storage area. Method according to claim 1, in which the molding bench (40) comprises several molds (41), each mold (41) being arranged to allow the manufacture of a set of beams (1), characterized in that , in the 'preparation step (a) and outside said molding bench (40), several sets of pre-assembled elements (5) are successively prepared by supplementing them with formwork spacers (4) to separate the beams (1) between them from the same set, each set of pre-assembled elements is taken in one piece using the gripping means (31) to deposit it inside each mold (41). Method according to claim 2, characterized in that it is arranged to allow the manufacture of beams (1) of different sections and lengths, the molds (41) of said molding bench (40) having different sections and the spacers of formwork (4) of each set of pre-assembled elements (5) being arranged at different intervals. Method according to claim 2, characterized in that , in the preparation step (a) and outside said molding bench (40), said sets of pre-assembled elements (5) are completed by prestressing cables ( 3) which is passed inside the reinforcement cages (2) and the formwork spacers (4). Method according to claim 2, characterized in that , in the preparation step (a) and outside said molding bench (40), said assemblies of prefabricated elements (5) are completed by anchoring pieces (6 ) arranged at least at the ends and arranged to allow the displacement of these assemblies under tension by said gripping means (31) and the automatic threading of the prestressing cables (3) in traction devices (50, 51) of the bench molding (40). Method according to claim 1, characterized in that , in the preparation step (a) and outside said molding bench (40), said reinforcing cages (2) are produced at least semi-automatically. Method according to claim 2, characterized in that , after the concrete has hardened, each set of manufactured beams (1) is unmolded in one piece, then it is deposited in a discharge zone outside said molding bench (40 ). Method according to claims 4 and 7, characterized in that , in the evacuation zone, the prestressing cables (3) are cut between two consecutive formwork spacers (4) to separate the beams (1) from the same assembly before evacuating them to a storage area. Installation (10) for manufacturing concrete beams (1) comprising at least one molding zone (B) provided with a molding bench (40), characterized in that it comprises at least one preparation zone (A ) disposed outside said molding zone (B) in which pre-assembled elements are prepared (5) comprising at least reinforcement cages (2) used in the manufacture of said beams (1), said elements being positioned with relative to each other at predetermined locations as a function of each beam (1) to be manufactured, said pre-assembled elements (5) constituting at least one assembly intended to be removed in one piece by gripping means (31) to be deposited in said molding bench (40) before pouring the concrete. Installation (10) according to claim 9, characterized in that said preparation zone (A) comprises at least one frame machine (20) arranged to automatically produce frames (2a) from metal wires and at least one reel ( 23) of metal wires and a welding station (25) arranged to assemble said frames (2a) to each other by mounting frames (2b) so as to form said frame cages (2). Installation (10) according to claim 9, in which the molding bench (40) comprises several molds (41) and has a length suitable for producing a set of beams (1) in each mold (41), characterized in that said preparation area (A) comprises at least one preparation mat (28) arranged to receive sets of pre-assembled elements (5) comprising at least several reinforcing cages (2) and formwork spacers (4) positioned one relative to the other at predetermined locations according to each set of beams (1) to be produced in each mold (41). Installation (10) according to claim 11, characterized in that said zone of molding (B) comprises traction devices (50, 51) provided at the ends said molds (41) and arranged for tensioning prestressing cables (3) provided in said sets of pre-assembled elements (5). Installation (10) according to claim 12, characterized in that the traction devices (50, 51) comprise for each mold (41) at least one fixed trimmer (50) and at least one trimmer (51) movable in rotation around 'a pivot (52) fixed, these headers (50, 51) being constituted by strips (53) vertical, parallel and separated by intervals (54) to receive said prestressing cables (3). Installation (10) according to claim 9, characterized in that it comprises a evacuation zone (C) of the beams (1) manufactured, this evacuation zone (C) being disposed outside said molding zone (B) and comprising at least means of transport (60) of said beams (1) to at least one storage area. Installation (10) according to claims 11 and 14, characterized in that said gripping means (31) are arranged to, before pouring concrete, take in one piece each set of pre-assembled elements (5) of said preparation zone (A) and place it in one of the molds (41) of said molding zone (B) and, after pouring and hardening of the concrete, unmold in one piece each set of beams (1) manufactured and deposit it on said means of transport (60) of said evacuation zone (C). Installation (10) according to claims 12 and 15, characterized in that said gripping means (31) are arranged to apply tension to said sets of pre-assembled elements (5) when they move from the preparation area ( A) to the molding area (B) for tensioning the prestressing cables (3). Installation (10) according to claims 12 and 15, characterized in that said discharge zone (C) comprises at least one cutting station (62) arranged to cut said prestressing cables (3) between the formwork spacers (4 ) to separate the beams (1) from the same assembly before their storage. Installation (10) according to claim 10, characterized in that it comprises at least one automaton arranged to control at least the frame machine (20) in an automated manner according to computer data relating to the beams (1) to be produced.

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