Machine and method for producing monoaxial reinforcement steel bar mats, and monoaxial reinforcement bar mats

Abstract

The present invention relates to a machine and a method for producing monoaxial reinforcement bar mats, in particular for uses not involving predominantly static loading, as well as a corresponding reinforcement bar mat.

Description

[0001] Machine and method for the production of uniaxial reinforcing steel bar mats, as well as uniaxial reinforcing bar mats

[0002] The present invention relates to a machine and a method for manufacturing uniaxial reinforcing bar mats, in particular those for applications with non-predominantly static loads, and to a corresponding reinforcing bar mat.

[0003] In reinforced concrete construction, steel bodies or bars are used to improve the static properties of concrete components. These absorb tensile forces and thus supplement the compressive strength of the concrete, thereby increasing the load-bearing capacity of the reinforced concrete components. This is achieved by individually delivering steel bodies or bars made of reinforcing steel or round steel to the construction site and interlacing them by hand, by installing welded uniaxial or biaxial reinforcing meshes, or in segments of special shapes. Since uniaxial reinforcing meshes can only absorb tensile forces in one direction, their longitudinal direction, two uniaxial reinforcing meshes rotated 90° relative to each other are necessary per reinforced concrete component so that it can absorb tensile forces and bending moments in all directions.Cold- or hot-formed reinforcing steel bars are generally not twisted, have a nearly circular cross-section and an obliquely ribbed surface, and may also have longitudinal ribs. Reinforcing steel bars are often up to 12 m long and typically have diameters of up to 40 mm, allowing them to reach weights of several hundred kilograms.

[0004] Welded connections have long been known and proven for predominantly static loads. Welded uniaxial reinforcing steel mesh offers a particular advantage, as it can be installed very quickly on the construction site. Corresponding machines have also been known for some time, for example from EP 0 862 958 or PCT / DE2009 / 000298. The machine for producing uniaxial reinforcing steel mesh described in EP 0 862 958 features a lateral feed of reinforcing steel bars to a mesh former, whereby the pre-cut reinforcing bars are either taken from a holding magazine or the reinforcing steel bars yet to be cut are pulled from coils by a bar former designed as a straightening and cutting machine, straightened, and cut to length.The reinforcing steel bars fed into the mat forming machine are positioned transversely to the mat by a transverse positioner and welded to flexible steel support belts by an automated welding machine. The single-axis reinforcing steel bar mats have widths of up to 15 m and can contain reinforcing steel bars of varying diameters and lengths. The thin steel belts of a certain width are used to ensure the reinforcing steel bars are unrolled in a directionally stable manner. The width of the belt ensures good straight-line tracking, and the reinforcing steel bars lie precisely and stably in the previously calculated and planned position after unrolling.

[0005] However, welded steel reinforcing mesh is less suitable for reinforced concrete components and structures subjected to non-predominantly static loads, such as those found in civil engineering, structural engineering, and building construction. Examples of such reinforced concrete components include those of road and railway bridges exposed to alternating loads from traffic, offshore wind turbines subjected to wave action, and structures subjected to dynamic excitations from gusty winds or vortex shedding, such as towers, masts, or high-rise buildings. Finally, concrete components in industrial plants, such as crane runways, forklift platforms, or machine foundations, also fall under this category of structures not subjected to predominantly static loads. In all these components, material fatigue can occur due to continuous, highly cyclic loading with a high number of load cycles.This type of stress is a major cause of damage to the aforementioned components and structures.

[0006] Since the material fatigue behavior in welded joints is concentrated locally primarily on the weld seam - due to microstructure changes and strong notch effects, there is a significant reduction in the fatigue strength of the steel - such a welded joint is known in expert circles to be problematic.

[0007] For example, due to the notch effect of the weld, conventional welded reinforcing steel mats or round bars do not achieve the fatigue strength prescribed by Eurocode 2 for applications with non-predominantly static loading; their values ​​are significantly below the S-N curve for bars. Therefore, for components subjected to dynamic loading, individual bars have primarily been used, which had to be laboriously and time-consumingly connected by hand on-site using thin wires. This resulted in a correspondingly expensive production of a dynamically load-bearing surface due to the costly manual connection. If welded reinforcing steel mats were used instead, steel consumption increased significantly because a large amount of additional material was required.

[0008] From DE 10 2020 126 584 A1, a machine is known with a steel belt conveyor for conveying a plurality of parallel and spaced-apart steel support belts and a reinforcing bar conveyor, wherein the latter conveys individual reinforcing bars onto the multiple support belts by crossing them at intersection points, and wherein several connecting units are arranged acting at each intersection point, and wherein a connecting unit has a binding wire conveyor which conveys a binding wire through a rotary unit, wherein the rotary unit is movable relative to the steel support belt and the crossing reinforcing steel bar and is arranged on one side of the plane defined by both.Furthermore, a binding wire guide unit is provided, which is arranged on the opposite side of the plane and which discharges a binding wire fed into it by the binding wire conveying device in the opposite direction to the feed direction and holds it in a frictional fit. The rotating unit twists and cuts the two binding wire strands located on one side of the plane together. The rotating unit and the binding wire guide unit are brought together to form a wire loop connecting the steel support band and the reinforcing steel bar, such that the steel support band and the reinforcing steel bar are pressed against each other. Simple, non-high-grade steel bands without any material additions are used for the steel support bands. A uniaxial reinforcing steel bar mat produced in this way therefore has a multitude of wire loops around reinforcing steel bars and steel support bands.The number of wire loops per reinforcing bar corresponds to the number of support straps on which they are to be attached in a crossing fashion; thus, there are nx wire loops per n support straps of the mat, where x is a number between 0 and n-2.

[0009] Starting from this prior art, the present invention aims to provide a more versatile machine, a corresponding manufacturing process, and a corresponding mat. This objective is achieved by the features of the respective independent claims.

[0010] In contrast to the known machine described above, the machine of the invention has a joining unit with two subunits for different types of connections. One of these subunits is in a working position and the other in a waiting position, with both being able to be moved synchronously to the other position. A first subunit is formed by a combination of a binding wire feeder, a rotary unit, and a binding wire guide unit; the second subunit is designed as a welding unit. The synchronous movement of the subunits from one position to the other is achieved in particular by horizontal displacement, preferably by means of a carriage on which the two subunits are arranged. This makes the machine according to the invention particularly versatile; it can be used to produce reinforcing bar mats made of a wide variety of materials.

[0011] In another difference from the machine described above, the rotary unit of the first sub-unit is located on the support belt side of the plane spanned by the reinforcing bars and the support belts, and the binding wire guide unit is located on the reinforcing bar side, so that the cut and twisted binding wire ends are also located on the support belt side of the plane.

[0012] Furthermore, the present machine differs in that it processes a plastic support belt and can process reinforcing bars made of fiberglass, carbon fiber, plastics, galvanized steel, or stainless steel, in addition to those made of reinforcing steel and plastic-coated reinforcing steel. The resulting wide variety of reinforcing bar mats that can be produced with the machine is based on the type of connection between the support belt and the reinforcing bar, as well as on the material of the support belts.

[0013] It is surprising that such a plastic support strap is suitable for connecting numerous heavy reinforcing steel bars in a rollable, uniaxial reinforcing steel mesh weighing up to several tons, which was anything but expected given this material combination. In particular, it was not anticipated that a plastic strap – especially a PET strap – would possess the same or a similarly high degree of stiffness to ensure the straight running of the plastic strap when unrolling the finished uniaxial reinforcing steel mesh on the construction site and during production, as the steel straps used exclusively until now. If reinforcing bars made of the aforementioned non-metallic materials are used within the machine and for the reinforcing steel mesh according to the invention, the plastic support strap is undoubtedly also suitable. These, too, can be connected particularly securely and permanently with a plastic support strap.Due to their lower weight, the overall weight of the finished, single-axis reinforcing mesh to be transported is advantageously reduced even further, without negatively affecting its static properties.

[0014] Such a plastic support strap is significantly less expensive than the previously known steel strap. It is also lighter, thus reducing the mass of the reinforcing mesh that needs to be transported. It cannot rust, even if the concrete in which the single-axis mesh is embedded develops cracks and fissures during its service life, allowing moisture and oxygen to reach the reinforcement. It is therefore completely impervious to freeze-thaw cycles, such as those that occur particularly in bridge construction. This advantage is even more pronounced when using the aforementioned non-metallic materials for the reinforcing bars. In this case, the mesh is entirely resistant to such attacks.

[0015] Preferably, the plastic according to the invention is a PET material, in particular a recycled PET material. Despite the aforementioned stiffness, this material surprisingly also exhibits sufficient softness (flexibility) to ensure both the correct spacing of the reinforcing steel bars when unrolling the uniaxial reinforcing steel mesh on a construction site and the mesh's rollability during its manufacture. This latter property is essential for the machine in question.

[0016] In one embodiment of the invention, the plastic support strap is an embossed PET strap, in particular a strapping strap. As such, it exhibits high tensile strength, which, due to the larger dimensions of the plastic strap, is even higher than that of previously used steel support straps. It is available in long lengths on rolls and can thus be advantageously used on the machine and for the reinforcing bar mat according to the invention.

[0017] A major advantage of this material is that it can be easily punched and cut with less force, and also causes much less wear on the cutting edges of the tools than is the case with the steel support belts used exclusively until now.

[0018] A particularly advantageous feature is that the PET material can be joined together by friction welding, so that the machine according to the invention easily allows for a roll change during operation by connecting the end of an almost completely unwound roll of PET support tape to the beginning of a new PET support tape roll. In this embodiment of the invention, the PET is a homogeneous, non-fiber-reinforced PET and is correspondingly tough and ductile. The tensile strength is up to 18,000 N.

[0019] The dimensions of the plastic strip are, in particular, a width between 12 and 35 mm, especially between 19 and 32 mm, preferably between 25 and 32 mm. The thickness is between 0.5 mm and 1.5 mm, preferably between 0.7 and 1.2 mm.

[0020] In a further development of the invention, the web between two through-openings is designed to be wide enough that the plastic deforms plastically when connected to the reinforcing steel bar by means of a wire loop, thus pressing against the reinforcing steel bar and its ribs, and thereby largely assuming its outer contour. This advantageously increases the strength of the friction-fit connection to the reinforcing steel bar and thus leads to a stiffer connection, which also contributes to the surprising suitability of the plastic support strip for use in a uniaxial reinforcing steel bar mat. The reinforcing steel bar practically does not slip; at most, a slight twisting occurs between the plastic support strip and the reinforcing steel bar.

[0021] The inventive method for producing a uniaxial reinforcement mat from a plurality of mutually parallel and spaced-apart reinforcing bars, which are oriented orthogonally to and attached to a plurality of mutually parallel and spaced-apart plastic support strips, comprises the following steps: a) feeding in spaced-apart, parallel plastic support strips and creating through-holes in each plastic support strip, b) feeding in a reinforcing bar orthogonally to the longitudinal axes of the parallel plastic support strips to create a plurality of intersection points between each plastic support strip and the reinforcing bar, c) pressing the reinforcing bar onto the plastic support strip to hold it in a tight position.d) Feeding a binding wire around the plastic support strap and reinforcing bar in the area of ​​an intersection point, forming a double binding wire strand on the support strap side, e) cutting the binding wire to length and twisting the two binding wire strands together to form a twisted section.

[0022] In the design of the procedure, it is provided that after step e) a step f) of bending the twisted section into or in the direction of the plane defined by support straps and reinforcing bars takes place.

[0023] The procedure is designed so that steps a) and b) are carried out simultaneously and / or step c) extends over at least step d), preferably also over steps e) and f).

[0024] The reinforcing bar mat according to the invention comprises a plurality of plastic support straps and a plurality of reinforcing bars permanently connected to these straps by a plurality of wire loops. The reinforcing bars are made of materials such as reinforcing steel, plastic-coated reinforcing steel, glass fibers, carbon fibers, plastics, galvanized steel, or stainless steel. The invention is explained in more detail below with reference to the figures of an exemplary embodiment, where identical components are designated by the same reference numerals. The figures show...

[0025] Fig. 1: a schematic view of a wire loop,

[0026] Fig. 2: a schematic sectional view of an embodiment of the machine in a first state,

[0027] Fig. 3: a schematic sectional view of an embodiment of the machine in a second state and

[0028] Fig. 4: a connecting unit consisting of two subunits.

[0029] Fig. 1 shows a binding wire loop around a crossing point 5 made of plastic support tape 2 – here a PET tape – and a reinforcing bar 4 made of one of the aforementioned materials, in particular the non-weldable materials. Elongated holes 17, created in-situ by means of a punching or cutting tool, are visible in the plastic support tape 2, the closest distance between which is less than the diameter of the reinforcing bar 4. The two elongated holes 17 are here an embodiment of the inventive guide 14 for the binding wire 8 in the form of openings 15.The binding wire 8 is guided through the two elongated holes 17, and its two strands 11 are twisted together to form a twisted section 18 according to the inventive method. This twisted section 18 is bent, in particular approximately parallel to the plane formed by the plastic support strip 2 and the reinforcing bar 4, in order to prevent it from protruding from the concrete and also to avoid injury to the user. "Plane" here does not refer to a strictly mathematical two-dimensional plane, but rather to the three-dimensional plane formed by both, roughly like a flat plate. The width of the support strips 2 of a uniaxial reinforcing mat is selected such that it can be unrolled with reliable straight-line tracking, which is surprisingly also possible for the plastic strips according to the invention. The twisted section 18 is arranged on the support strip side.

[0030] The reinforcing bars 4 are selected from those with diameters between 6 mm and 40 mm, but can also have larger diameters. The spacing of the parallel reinforcing bars 4 of a uniaxial reinforcement mat is freely selectable according to the requirements of the respective application of the uniaxial reinforcement mat. This is achieved through computer-aided optimized planning with regard to length, position, spacing, diameter, material, etc. Reinforcing steel, carbon fiber, glass fiber, plastic, or galvanized steel, or the aforementioned materials, are suitable materials for the reinforcing bars. Preferably, a minimum distance is maintained between two adjacent reinforcing bars 4 to ensure slippage resistance.

[0031] The edge distance of the web remaining between the elongated holes 17 of the plastic support strip 2 is adapted to the diameter of the bar to be bound. In particular, it is smaller than or equal to the diameter of the bar. This ensures that the bond does not loosen even if the plastic support strip 2 bends or kinks, especially during winding in manufacturing. By adapting the edge distance, a secure bond is always achieved for any different diameter of the reinforcing bars 4. This also prevents the reinforcing bar 4 from twisting about its longitudinal axis. According to the invention, this distance is also wider than the bar diameter. This results in a kind of clamping action around the reinforcing bar 4, with positive effects on its positional stability while maintaining a secure bond.The advantages of a plastic strip with regard to deformation and adaptation to the surface structure of the reinforcing bars have already been mentioned above.

[0032] Fig. 2 shows an embodiment of the invention with the first subunit 16 of the connecting device in a first operating state. In this state, a reinforcing bar 4 has already been fed to a plurality of plastic support belts 2 and, if necessary, positioned in its axial direction relative to them. The support belt conveying device 1 and the reinforcing bar conveying device 3 are shown purely schematically; the intersection point 5 is located above the illustrated reinforcing bar 4, with the rounded binding wire guide unit 9 arranged below the intersection point 5 and partially encompassing the reinforcing bar 4. A binding wire conveying device (not shown) conveys the binding wire 8 through the rotary unit 10 towards the intersection point 5. The connecting unit 6 according to the invention consists of the components of the binding wire conveying device, the rotary unit 10, and the binding wire guide unit 9.In the operating state shown, the binding wire 8 has already been fed into the binding wire guide unit 9 by the rotary unit 10, which for this purpose has a u-shaped body against whose wall the binding wire 8 rests at least partially and is thus held in frictional contact.

[0033] In this embodiment, the plastic support belt 2 is guided by a schematically depicted punching unit 19, which introduces in-situ guides 14 in the form of elongated holes 17 into the plastic support belt 2.

[0034] The operating state shown is the one before the connection. To the

[0035] To create a wire loop, rotary unit 10 and binding wire guide unit 9 are moved towards each other and press reinforcing bar 4 and support strap 2 together.

[0036] Fig. 3 shows a second operating state of the first subunit 16 of the joining unit, in which the connection has already been made by creating a tight wire loop. For this purpose, the wire fed through the binding wire channel 20 of the rotating unit 10 was first cut to length, then the rotating unit 10 was lifted from the support belt 2 and rotated, so that the twisted section 18 with ends 11 was formed. The cutting to length is done on the machine side with a blade (not shown) that is located in front of the rotating unit 10 when viewed in the conveying direction of the binding wire 8. A resistance to pulling the wire out due to the shortening of the protruding wire length during twisting is provided by the frictional engagement described above. This makes the binding tight and secure. The rotation against the resistance to pulling the wire out allows the two strands of binding wire 11 to twist against each other, creating a twisted section 18.The twisting action eventually causes the cut end to slide out of the rotating unit 9. A bending unit 12 pushes the twisted section towards the support strap 2. After releasing the clamp, the rod is now free. During binding, the rod and the plastic support strap are additionally pressed together and thus held in a tight position.

[0037] Finally, the binding wire guide 9 also moves away, so that the intersection point is released, or rather all intersection points of this reinforcing bar 4 created simultaneously.

[0038] The machine creates the through-holes in situ as guides for reinforcing steel bars. These guides advantageously create a guided, position-invariant binding wire loop around the node, which cannot loosen even if the support strap bends or kinks, for example when the uniaxial reinforcement mat is rolled up or down.

[0039] A web width in the plastic support band, adapted to the rod diameter, prevents the rod from twisting. The web width can also be wider than the rod diameter. This results, as described, in a kind of gripping of the rod, with positive effects on positional stabilization and a secure bond.

[0040] Operating states with the second subunit 16 of the connection unit, namely the welding unit, are not shown. This is a known unit whose structure and function are familiar to those skilled in the art.

[0041] Finally, Fig. 4 schematically shows a detail of the connecting unit 6, consisting of two subunits 16. The carriage 22, on which the two subunits 16 are arranged, is visible. The welding unit 21 is shown on the left, and the second subunit 16, referred to as the binding unit, is shown on the right. The carriage 22 is controlled such that one subunit 16 is in an operating position at the intersection of the reinforcing bar and the support strap, while the other subunit 16 is in a waiting position. These positions are reversed by moving the carriage 22.

[0042] This allows the rest of the machine's structure to remain unchanged and unmodified, advantageously avoiding duplication of conveyor belts, rod supports, etc.

[0043] This invention offers a significant advantage in providing a versatile machine for the production of uniaxial reinforcing bar mats. Furthermore, it opens the door for those skilled in the art to unusual material combinations for the uniaxial reinforcing bar mats according to the invention. Due to the absence of welded connections, these mats can also be used in dynamically loaded concrete structures and offer at least significant weight advantages compared to known reinforcing bar mats.

[0044] REFERENCE SYMBOL LIST Belt conveyor system Belt Reinforcing bar conveyor system Reinforcing bar Crossing point Connecting unit Binding wire Binding wire guide unit Rotary unit Binding wire strand Bending unit Guide Opening Subunit Slotted hole Twisting section Punching unit Binding wire channel Welding unit Slide

Claims

PATENT CLAIMS 1. Machine for the production of single-axis reinforcing bar mats, comprising a conveyor belt device (1) for conveying a plurality of mutually parallel and spaced-apart conveyor belts (2) and a reinforcing bar conveying device (3), wherein the latter conveys individual reinforcing bars (4) crossing onto the multiple conveyor belts (2) by forming intersection points (5), wherein the machine generates in-situ guides (14) in the form of elongated holes (17) in the conveyor belt (2), further comprising several connecting units (6) arranged to act at each intersection point (5), wherein a connecting unit (6) has two subunits (16) for different types of connection, wherein a first subunit (16) is formed by a binding wire conveying device, a rotary unit (10) and a binding wire guide unit (9), wherein the binding wire conveying device feeds a binding wire (8) through the rotary unit (10),wherein the rotary unit (10) is movable relative to the plastic support belt (2) and the crossing reinforcing bar (4) and is arranged on one side of the plane defined by the longitudinal axes of the plastic support belt (2) and reinforcing bar (4), wherein the binding wire guide unit (9) is arranged on the opposite side of the plane and it has a binding wire conveying device into it, introduced binding wire (8) in reverse to infeed direction conveying and frictionally holding, wherein the rotary unit (10) twists and cuts to length the two binding wire strands (11) located on one side of the plane, and wherein it and the binding wire guide unit (9) are brought together in such a way as to form a wire loop connecting a plastic support band (2) and reinforcing bar (4) that the support band (2) and reinforcing bar (4) are pressed together, and wherein the second subunit (16) is formed by a welding unit (21).

2. Machine according to claim 1, characterized in that one subunit (16) is always in a working position and the other in a waiting position, wherein both can be moved synchronously into the other position, in particular by means of a horizontally displaceable slide on which the two subunits (16) are arranged.

3. Machine according to claim 1 or 2, characterized in that it has a friction welding device for joining two plastic support belts.

4. Uniaxial reinforcing bar mat comprising a plurality of reinforcing bars (4) and support straps (2), wherein reinforcing bars (4) and support straps (2) are connected to each other by means of wire loops, characterized in that at least one support strap (2) is a plastic support strap and the reinforcing bars (4) are selected made from fiberglass, carbon fiber, plastic, stainless steel, galvanized steel and reinforcing steel bars.

5. Uniaxial reinforcing bar mat according to claim 4, characterized in that the plastic support band (2) is made of PET, in particular of recycled PET, and preferably is an embossed PET band, in particular a strapping band.

6. Uniaxial reinforcing bar mat according to claim 4 or 5, characterized in that the PET is a homogeneous, non-fiber-reinforced PET.

7. Uniaxial reinforcing bar mat according to claim 4, 5 or 6, characterized in that the plastic support strips have a width between 12 and 35 mm, in particular between 19 and 32 mm, preferably between 25 and 32 mm and a thickness between 0.5 mm and 1.5 mm, preferably between 0.7 and 1.2 mm.

8. Method for producing a uniaxial reinforcement mat from a plurality of mutually parallel and spaced-apart reinforcing bars, which are oriented orthogonally to and attached to a plurality of mutually parallel and spaced-apart support strips, comprising the following steps: a) feeding in spaced-apart, parallel plastic support strips and creating openings in each plastic support strip, b) feeding in a reinforcing bar orthogonally to the longitudinal axes of the parallel plastic support strips to a) Creating multiple intersection points between the respective plastic support strip and the reinforcing bar, c) Pressing the reinforcing bar onto the plastic support strip to hold it in a tight position, d) Feeding a binding wire into the area of ​​a e) Crossing point around plastic support strap and reinforcing bar, forming a double binding wire strand on one side, e) Cutting the binding wire to length and twisting the two binding wire strands together to form a twist section.

9. Method according to claim 8, wherein after step e) a step f) of bending the twisted section in or in the direction of the plane defined by support straps and reinforcing bars is carried out.

10. Method according to claim 8 or 9, wherein steps a) and b) are performed simultaneously and / or step c) extends over at least step d), preferably also over steps e) and f).

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