Method and apparatus for making pre-cages for reinforcement

Abstract

The method for making pre-cages intended for forming cages for reinforcing building structures comprises the steps of individually arranging a plurality of stirrups (2) with a closed or open profile on suitably spaced parallel planes. At least one thin longitudinal auxiliary wire (3) is associated with the outside of said stirrups (2) at a corner of the same stirrups (2). Said at least one longitudinal auxiliary wire (3) is bonded to said stirrups (2) by welding.

Description

[0001] Description

[0002] METHOD AND APPARATUS FOR MAKING PRE-CAGES FOR REINFORCEMENT Technical field

[0003]

[0001] The present invention relates to a method and apparatus for making pre-cages intended for forming cages for reinforcing building structures.

[0004] Prior art

[0005]

[0002] The use of metal cages for reinforcing reinforced concrete pillars and beams is currently well known in the construction industry. These metal cages usually consist of longitudinal bars connected by appropriately spaced transverse stirrups. The stirrups generally define a closed path, for example in the shape of a quadrilateral, with the ends folded and overlapped to form closing hooks. The longitudinal bars are inserted inside the profile defined by the stirrups, for example at the corners of this profile.

[0006]

[0003] The traditional method for making these metal cages involves manually attaching the stirrups, suitably spaced, to the longitudinal bars. However, this solution requires a lot of time and therefore high labor costs. To overcome these drawbacks, the use of semiautomatic machines has been proposed, which simplify the formation of reinforcement cages by passing through an intermediate stage consisting of the formation of a pre-cage; however, these introduce a new problem consisting of protecting the final product from corrosion.

[0007]

[0004] More recently, in order to automate the formation of cages for reinforcing building structures, it has been proposed to first make pre-cages that make it easier to finish the reinforcement cages later. These pre-cages are essentially formed by a truss consisting of a plurality of closed or open profile stirrups arranged on parallel planes at appropriate distances, connected by at least one pair of disposable auxiliary wires, not provided by the designers; the auxiliary wires are usually welded step-by-step to the outside of the stirrups. Since the auxiliary wires are external, it is possible to easily insert the stirrups between them, progressively forming the aforementioned truss. This results in an intermediate or pre-cage structure in which the stirrups are fixed to each other in the perfect position required.

[0008]

[0005] To form the reinforcement cages, the appropriate longitudinal bars are then bonded to the lattice, for example inserted inside the stirrups and joined to at least part of them, in the positions specified in the design. Thanks to the fact that the pre-cage is sufficiently stable in itself, in particular for the transport and handling of the corresponding finished cage, it is not necessary for the longitudinal bars and longitudinal bars to be fixed at all intersections with the stirrups to obtain a stable structure, but it is sufficient to make a very small number of bindings, sufficient to hold the bars in position.

[0009]

[0006] It should be noted that the pre-cage itself, being welded, is capable of providing sufficient stability to the entire structure.

[0010]

[0007] Patent document EP 0 667 195 B1 in the name of the same applicant describes a method and apparatus for making pre-cages for forming cages for reinforcing building structures.

[0011]

[0008] Patent document IT UD990206 A1 describes a different method for manufacturing precages of the type mentioned above.

[0012]

[0009] It has been observed that at the aforementioned auxiliary wires, the distance between the wires themselves and the surface of the casting is less than the distance of the stirrup, thus reducing the so-called concrete cover. Between one stirrup and another, the disposable auxiliary wires can be suitably shaped with loops to fit more closely to the external surface of the casting; however, at the stirrup, the disposable auxiliary wires, even if partially flattened by welding, always reduce the amount of concrete cover. This results in less protection against corrosion of the steel forming the reinforcement. At these points, protected by a reduced concrete cover compared to the stirrups, real openings to corrosion can form, which then reaches the rest of the reinforcement, reducing the overall durability of the entire structure.

[0013] Disclosure

[0014]

[0010] The task of the present invention is to solve the aforementioned problems by devising a method and a semi-automatic apparatus that allow for the optimal production of pre-cages intended for the formation of cages for the reinforcement of building structures.

[0015]

[0011] Within the scope of this task, a further purpose of the present invention is to provide a method and apparatus for the production of pre-cages equipped with disposable auxiliary wires arranged in areas where their presence does not adversely affect the concrete cover.

[0016]

[0012] Another purpose of the present invention is to provide a method and apparatus for producing pre-cages equipped with disposable auxiliary wires that do not adversely affect corrosion resistance.

[0017]

[0013] Another purpose of the present invention is to provide an apparatus for manufacturing pre-cages for reinforcement with a simple construction and functional design, which is safe and reliable in use and relatively inexpensive.

[0018]

[0014] The above objectives are achieved, according to the present invention, by the method for manufacturing pre-cages intended for forming cages for reinforcing building structures according to claim 1 .

[0019]

[0015] The method for making pre-cages for forming cages for reinforcing building structures comprises the steps of: a. placing a first stirrup of a plurality of closed or open profile stirrups on a joining plane; b. externally joining to said first stirrup arranged on said joining plane one or more thin longitudinal auxiliary wires at a corner position of the same stirrup; c. securing said one or more longitudinal auxiliary wires to said first stirrup, preferably by welding; d. advancing step-by-step said one or more longitudinal auxiliary wires integral with said first stirrup already joined; e. repeating the previous cycle, from point a. to point d., inserting in ordered sequence a subsequent stirrup until obtaining a pre-cage having all the stirrups of said plurality of stirrups spaced exactly with the same steps provided for the cage to be produced.

[0020]

[0016] In the context of the present invention, "thin" auxiliary wires are wires having a crosssection smaller than the cross-section of the metal elements with which the stirrups are made.

[0021]

[0017] The pre-cage intended for forming cages for reinforcing building structures, according to the present invention, comprises a plurality of closed or open profile stirrups arranged on parallel planes at appropriate distances from each other; one or more thin longitudinal auxiliary wires fixed externally to said stirrups at least at one corner position of the stirrups themselves.

[0022]

[0018] Preferably, said longitudinal auxiliary wires are three or four in number.

[0023]

[0019] According to one embodiment of the invention, all the longitudinal auxiliary wires are fixed externally to said stirrups, respectively at a corner position of the same stirrups.

[0024]

[0020] Advantageously, said longitudinal auxiliary wires arranged at a corner position of the stirrups engage at least the sides of the cage intended to be arranged at the surface of the building structure facing outwards, i.e., more exposed to atmospheric agents that can most attack and degrade the structure over the years.

[0025]

[0021] Preferably, the method in question involves joining said one or more longitudinal auxiliary wires externally to said stirrups at the blind spot defined externally to the stirrups themselves, understood as the difference between the actual and ideal dimensions, so as to create a space in which to house each auxiliary wire without eroding the thickness of the concrete cover measured on the ideal dimensions.

[0026]

[0022] Advantageously, at least one of said longitudinal auxiliary wires is arranged at the overlap of the metal elements with which said stirrups are made.

[0027]

[0023] This overlap of the metal elements with which the stirrups are made often occurs at the closing hook of the stirrups themselves or, in complex stirrups, also in other sections. In this way, the overlapping metal elements are welded by the said auxiliary wire and the stirrup thus becomes a closed profile with greater rigidity.

[0028]

[0024] Advantageously, said one or more longitudinal auxiliary wires may have a loop at the areas of coupling with said areas of the stirrups. In this way, the section of said auxiliary wires between one stirrup and another remains more internal to the concrete product.

[0025] Preferably, said loop has a trapezoidal or curved shape. In this way, the loop is configured to accommodate a plurality of metal elements with which the stirrups are made, in particular a pair of rods placed side by side or one above the other.

[0029]

[0026] The present invention also relates to an apparatus for making pre-cages intended for forming cages for reinforcing building structures, as described above.

[0030]

[0027] The apparatus for making pre-cages intended for forming cages for reinforcing building structures comprises joining means for joining one or more thin, disposable longitudinal auxiliary wires, externally to said stirrups, said joining means being suitable for welding said external auxiliary wires at a corner of the stirrups themselves.

[0031]

[0028] Advantageously, said joining means comprise one or more welding heads that can be adjusted to be substantially orthogonal to the curvature of said stirrup at the point of contact with the auxiliary wire to be welded externally.

[0032]

[0029] In particular, said welding heads are orientable on the plane of the stirrup.

[0033]

[0030] Preferably, said welding heads are adjustable along orthogonal axes on the plane of the stirrup.

[0034]

[0031] Preferably, said orthogonal axes are horizontal and vertical, respectively, if the plane of the stirrup is vertical.

[0035]

[0032] Preferably, said welding heads are orientable by rotating substantially around the axis of a relative auxiliary wire.

[0036]

[0033] Advantageously, said welding heads are configured to rotate substantially about the axis of a respective auxiliary wire.

[0037]

[0034] It should be noted that the aforementioned methods of rotation of the welding heads refer to two different embodiments of the apparatus in question.

[0038]

[0035] In one case, rotation takes place substantially around the auxiliary wire, causing the welding heads to move relative to circular sector-shaped slots, all having a common center in the auxiliary wire. However, this solution requires the welding heads to be lifted by means of special lifting devices in order to orient them, due to the considerable weight of the welding heads themselves, which also carry the relative piston and transformer.

[0039]

[0036] In the other, more advantageous case, the welding head is physically hinged at the axis of the auxiliary wire by means of a perforated fulcrum, for example a sleeve, which allows rotation, allowing the wire to pass freely through the hole. This greatly reduces the effort required to orient the welding head, which can also be automated by means of a simple actuator member.

[0040]

[0037] Preferably, the apparatus comprises a frame defining a work surface extending longitudinally on which the pre-cage is formed in front of a fixed head, bearing said means for joining the auxiliary wires externally to said stirrups, and a mobile drawing head mounted so as to slide on said work surface and configured to pull the same auxiliary wires that draw the already joined stirrups step-by-step.

[0041]

[0038] It should be noted that, alternatively, the auxiliary wires could be pushed, by means known per se.

[0042] Brief description of the drawings

[0043]

[0039] The details of the invention will be more evident from the detailed description of a preferred embodiment of the pre-cage intended for forming cages for reinforcing building structures, according to the method also covered by the invention, illustrated by way of example in the accompanying drawings, in which:

[0044] Figures 1 and 1a show a perspective view and a front view of the pre-cage in question, respectively;

[0045] Figures 2, 2a; 3, 3a; 4, 4a; 5, 5a and 6, 6a show, respectively, a perspective view and a front view of different embodiments of the pre-cage in question; figure 7 shows a front view of a corner area of a stirrup of the pre-cage in question coupled with a relative disposable auxiliary wire, according to the actual dimensional proportions;

[0046] Figure 8 shows an enlarged detail of a portion of a longitudinal auxiliary wire in the area where the loop is formed, at an overlap of the stirrup;

[0047] Figure 9 shows a similar enlarged detail of a portion of a longitudinal auxiliary wire deformed during the welding step at a differently shaped loop;

[0048] Figure 10 shows a perspective view of an apparatus for making pre-cages intended for forming cages for reinforcing building structures;

[0049] Figure 11 shows a corresponding side view;

[0050] Figures 12 and 13 show, in a front view, different configurations of use of one or more welding heads in the welding step of respective longitudinal auxiliary wires to the stirrups of the pre-cage.

[0051] Description of embodiments of the invention

[0052]

[0040] With particular reference to these figures, 1 indicates a pre-cage intended for forming cages for reinforcing building structures, such as beams or load-bearing pillars. The precage 1 comprises a plurality of stirrups 2 with a closed or open profile, arranged on parallel planes at appropriate distances; the stirrups 2 are connected to each other by one or more longitudinal auxiliary wires 3, preferably of thin thickness.

[0053]

[0041] In the context of the present invention, "thin" auxiliary wires are wires having a crosssection smaller than the cross-section of the metal elements constituting the stirrups. The maximum dimensions that the auxiliary wires of the cage can assume are specified in more detail below.

[0054]

[0042] Preferably, there should be three or four longitudinal auxiliary wires 3.

[0043] The stirrups 2, technically defined as "transverse reinforcement" in the specific field of use, are made in a known manner from elongated metal elements, such as profiles and steel rods for reinforced concrete, hereinafter also referred to as rods for simplicity.

[0055]

[0044] According to one aspect of the present invention, the pre-cage in question provides that at least one of said one or more longitudinal auxiliary wires 3 is fixed externally to said stirrups 2 at a corner position of the stirrups 2 themselves.

[0056]

[0045] More specifically, said one or more longitudinal auxiliary wires 3 are inserted and fixed by means of special welding members, at the blind spot defined externally to the stirrup 2, understood as the difference between the actual and ideal dimensions, which creates a space in which to house the auxiliary wire 3 without eroding the thickness of the concrete cover measured on the ideal dimensions (see Figure 7, where 3a indicates the maximum dimension that the auxiliary wire 3 can assume within the aforementioned blind spot).

[0057]

[0046] According to another aspect of the invention, said one or more longitudinal auxiliary wires 3 may have a loop 30 at the areas of coupling with said stirrups 2. In this way, the section of the auxiliary wires 3 between one stirrup and another remains more internal to the concrete product.

[0058]

[0047] Preferably, the loop 30 has a trapezoidal or curved shape so that it can accommodate more than one of the metal elements with which said stirrups are made, in particular a pair of rods placed side by side or superimposed, (see Figure 8).

[0059]

[0048] This is advantageous because the loop can then accommodate more than one rod of the stirrup, as is the case, for example, at overlaps or closing hooks. It should be noted that the loop 30 thus formed is able to avoid the risk of the auxiliary wire deforming under the pressure exerted by the welding members 4 during welding, as happens with a triangular loop (see Figure 9).

[0060]

[0049] Preferably, one of the auxiliary wires 3 is positioned at the overlap of the two ends of the stirrup 2, joining them and effectively transforming the stirrup into a closed ring.

[0061]

[0050] In Figure 10, 10 indicates the apparatus for making pre-cages 1 intended for forming cages for reinforcing building structures.

[0062]

[0051] The apparatus 10 comprises a frame 11 defining a work surface 12 extending longitudinally in front of a fixed head 13. A mobile drawing head 14 is mounted on the work surface 12 so as to slide along a longitudinal opening 15 dividing the work surface 12.

[0063]

[0052] As specified below, the stirrups 2 are fed one at a time manually by an operator on the joining plane. The mobile drawing head 14 sets the pre-cage in formation in motion, preferably by pulling the auxiliary wires 3 which drag the already joined stirrups 2 step-by- step. In this way, the stirrups 2 lie on parallel planes suitably spaced apart.

[0064]

[0053] Alternatively, it is possible to provide for the auxiliary wires to be set in motion by pushing means using known means.

[0065]

[0054] The apparatus also comprises means for joining one or more longitudinal auxiliary wires 3 externally to the stirrups 2, at least one of which is at a corner position of the stirrups 2 themselves. The joining means comprise one or more welding heads 16, associated with the fixed head 13 of the apparatus and configured to weld respective longitudinal auxiliary wires 3 externally to the stirrups 2 of the pre-cage.

[0066]

[0055] As mentioned, according to the present invention, the auxiliary wires 3 are welded at a corner position on the outside of the stirrups 2. To this end, the welding heads 16 are preferably adjustable so as to be positioned substantially perpendicular to the curvature of the stirrup 2 at the point of contact with the auxiliary wire 3. In particular, the welding heads 16 can be oriented on the vertical plane of the stirrup 2 and adjusted in orthogonal directions, in particular horizontally and vertically.

[0067]

[0056] The method for making pre-cages intended for forming cages for reinforcing building structures, using the apparatus described, is easily understood from the following description.

[0068]

[0057] First, one or more thin longitudinal auxiliary wires 3 are placed in an external position to the stirrups 2, at least one and preferably all of them at a corner of the stirrups 2 themselves. Inside the auxiliary wires 3, the operator inserts a stirrup 2 against the references that identify the joining plane, which is substantially orthogonal to the axis of the auxiliary wires 3. The auxiliary wires 3 are then welded to the stirrup 2. The mobile drawing head 14 then pulls the auxiliary wires 3 step-by-step, which in this way also advance the stirrup 2 joined to them. The insertion cycle of the individual stirrups 2 is repeated until the pre-cage intended for the formation of a corresponding cage for the reinforcement of building structures is completed.

[0069]

[0058] Advantageously, the operating steps described above are controlled by a control unit 5 associated with the apparatus.

[0070]

[0059] The method and apparatus of the present invention achieve the purpose of optimally producing pre-cages for forming cages for reinforcing building structures.

[0071]

[0060] In particular, the pre-cage produced by the method in question does not reduce the concrete cover in any way, even at the auxiliary wires, and is therefore able to guarantee maximum protection and durability of the product.

[0072]

[0061] This is achieved thanks to the inventive idea of associating one or more auxiliary wires externally to the stirrups, arranged on parallel vertical planes, at respective corner positions of the stirrups themselves.

[0073]

[0062] The positioning of the auxiliary wires substantially at the corners of the stirrups is particularly advantageous because the stirrups do not have sharp corners, but rather rounded corners because the metal rod can only be bent during the bending step. Therefore, between the corner curve of the stirrups and the theoretical sharp edge, a sort of blind spot is created, i.e., a surplus of concrete cover where, due to its size, an auxiliary wire placed outside the stirrup can be easily accommodated without reducing the thickness of the concrete cover in any way. Furthermore, an auxiliary wire placed outside the stirrup, in the aforementioned corner position, acts as reinforcement for the edge, which is usually damaged by impact because it is the most exposed part and subject to impact and, on the contrary, is normally without any form of reinforcement.

[0074]

[0063] It is also particularly advantageous that one of the auxiliary wires is positioned at the overlap of the sides of the closing hook (see figures 1 to 6). In this way, the two flaps are both welded by the auxiliary wire and the stirrup thus becomes a closed profile, which is advantageously much more rigid. This ensures that the reinforcement assumes the correct geometry defined in the approved structural design.

[0075]

[0064] Furthermore, in order to avoid the so-called "hinge effect," good construction practices suggest that the closing hooks be arranged alternately so that as few as possible are arranged on the same side, which is certainly feasible with the apparatus and method of the present invention.

[0076]

[0065] According to another aspect of the present invention, the longitudinal auxiliary wires of the pre-cage may have a loop at the areas of coupling with the stirrups, in particular having a trapezoidal or curved shape.

[0077]

[0066] In the practical implementation of the invention, the materials used, as well as the shape and dimensions, may be any as required.

[0078]

[0067] Where the technical features mentioned in each claim are followed by reference signs, such reference signs have been included solely for the purpose of increasing the understanding of the claims and consequently they have no limiting effect on the scope of each element identified by way of example by such reference signs.

Claims

Claims1. A method for making pre-cages intended for forming cages for reinforcing building structures, comprising the steps of: a. placing a first stirrup (2) of a plurality of closed or open profile stirrups on a joining plane; b. joining externally to said first stirrup (2) arranged on said joining plane one or more longitudinal auxiliary wires (3) of thin thickness, so as to have a cross section smaller than the cross section of the stirrup itself (2), at least one auxiliary wire (3) being fixed at a corner position of the stirrup itself (2); c. connecting said one or more longitudinal auxiliary wires (3) to said first stirrup (2), preferably by welding; d. advancing step-by-step said one or more longitudinal auxiliary wires (3) integral with said first stirrup (2) already joined; e. repeating the previous cycle, from step a. to step d., inserting in ordered sequence a subsequent stirrup (2) until obtaining a pre-cage (1) having all the stirrups (2) of said plurality of stirrups (2) spaced exactly with the same steps provided for the cage to be produced.

2. The method of claim 1 , wherein a loop (30) is formed along said one or more longitudinal auxiliary wires (3) at the coupling zones with said stirrups (2), said loop (30) being configured to accommodate at least one metal element of the stirrup (2).

3. The method of claim 2, wherein said loop (30) has a trapezoidal or curved shape configured to accommodate a pair of metal elements of the stirrup (2) placed side by side or superimposed.

4. The method of claim 1 or 2, wherein at least one of said one or more longitudinal auxiliary wires (3) is welded at the closing hook of the two ends placed side by side or superimposed of the stirrup (2) so as to create a closed stirrup.

5. The method of claim 3 and 4, wherein the loop (30) is made trapezoidal in shape at the overlapping areas of a plurality of elements of the stirrup (2), in particular forming the closing hook of the stirrup (2).

6. The method of claim 1 or 2, wherein the one or more longitudinal auxiliary wires (3) are joined to the stirrup (2) respectively at the blind spot defined externally to the stirrup itself (2), understood as the difference between the actual and ideal dimensions, so as to create a space in which to house the auxiliary wire (3) without eroding the thickness of the concrete cover measured on the ideal dimension.

7. An apparatus for making pre-cages intended for forming cages for reinforcing building structures, of the type comprising a plurality of stirrups (2) with a closed or open profilearranged on parallel planes suitably spaced apart and mutually constrained by one or more longitudinal auxiliary wires (3), said one or more longitudinal auxiliary wires (3) being thin, so as to have a cross-section smaller than the cross-section of the same stirrup (2), the apparatus comprising means (16) for joining said one or more longitudinal auxiliary wires (3) externally to said stirrups (2), at least one said auxiliary wire (3) being fixed at a corner position of said stirrups (2).

8. The apparatus of claim 7, wherein said joining means comprise one or more welding heads (16) which can be oriented so as to be substantially orthogonal to the curvature of said stirrup (2) at the point of contact with the auxiliary wire (3) to be welded.

9. The apparatus of claim 8, wherein said one or more welding heads (16) of the joining means are orientable to be arranged in a position substantially orthogonal to the curvature of the stirrup (2) at the point of contact with the auxiliary wire (3) to be welded.

10. The apparatus of claim 9, wherein said welding heads (16) are orientable in the vertical plane of the stirrup (2).

11. The apparatus of claim 9 or 10, wherein said welding heads (16) can be oriented being rotatable substantially about the axis of a relative auxiliary wire (3).

12. The apparatus of claim 9, wherein said welding heads (16) are adjustable in the vertical plane of the stirrup (2) in orthogonal directions.

13. The apparatus of claim 12, wherein said orthogonal directions of adjusting the welding heads (16) are horizontal and vertical, respectively.

14. The apparatus of any one of claims 8 to 13, wherein it comprises a frame (11 ) defining a work surface (12) extending longitudinally in front of a fixed head (13), bearing said means (16) for joining the auxiliary wires (3) externally to said stirrups (2), to support the forming pre-cage.

15. The apparatus of claim 14, wherein it comprises a movable drawing head (14) mounted so as to slide on said work surface (12) and configured to pull the same disposable auxiliary wires (3) which draw step-by-step the stirrups (2) already joined.

16. A pre-cage for forming cages for reinforcing building structures, comprising a plurality of stirrups (2) with a closed or open profile arranged on parallel planes suitably spaced apart; characterized in that it comprises one or more longitudinal auxiliary wires (3) of thin thickness, so as to have a cross section smaller than the cross section of the same stirrup (2), at least one of which is fixed externally to said stirrups (2) at a corner position of the same stirrups (2).

17. The pre-cage of claim 16, wherein said one or more longitudinal auxiliary wires (3) have a loop (30) at the areas of coupling with said stirrups (2).

18. The pre-cage of claim 16 or 17, wherein at least one of said one or more longitudinal auxiliary wires (3) is welded at the closing hook of the two overlapping ends of the stirrup (2) so as to create a closed stirrup.

19. The pre-cage of any one of claims 16 to 18, wherein said longitudinal auxiliary wires (3) are all welded substantially at the blind spot defined externally by the stirrup (2), understood as the difference between the actual and ideal dimensions, so as to create a space in which to house the auxiliary wire (3) without eroding the thickness of the concrete cover measured on the ideal dimension.

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