TECHNICAL FIELD

The present invention relates to a machine for producing spacers for concrete reinforcements and concrete structures, methods of manufacturing such spacers, and use thereof.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Reinforcements for flat structures in reinforced concrete usually consist of steel reinforcement mats. Often, one or more reinforcement mats are provided at the top and bottom of the flat structure, so that both tensile and pressure forces can be absorbed in an optimum manner.

During construction, the reinforcement mats are usually kept a desired distance apart by means of spacers. Various kinds of spacers are available.

Production of the spacers is carried out by means of a machine which is provided with separate wires and/or frame structures and completely automatically transforms these and welds them together to form a spacer.

During welding, wires may become stuck to parts of the machine, as a result of which manufacturing has to be stopped. This 'downtime' problem results in longer production times and costs for spacers.

In recent years, there is an increasing demand to produce ever lighter spacers in a shorter time. However, such a production method also increases the risk of the wires sticking, thus resulting in increased 'downtime'.

There is thus a need for new or adapted machines and new or adapted methods for manufacturing lighter spacers.

SUMMARY

The present invention relates to a machine for producing spacers for concrete reinforcements and concrete structures, methods of manufacturing such spacers, and use thereof.

In a first embodiment, the present invention relates to a machine for producing spacers for concrete reinforcements and/or concrete structures, the spacers comprising three parallel straight longitudinal wires which form the sides of a triangular prism, wherein each of the bottom longitudinal wires is connected to the top longitudinal wire by means of a frame structure, the machine furthermore comprising:

a. a welding installation for welding together the two frame structures to the top longitudinal wire and optionally welding together each of the frame structures to a bottom longitudinal wire, and;

b. a drive mechanism for transporting the spacers through the welding installation;

characterized in that the drive mechanism is positioned downstream of the welding installation.

In a particular embodiment, the machine according to the present invention comprises a second drive mechanism, characterized in that the second drive mechanism is positioned upstream of the welding installation.

In a particular embodiment of the machine according to the present invention, the drive mechanism comprises a system which clamps the wires during transportation, preferably a mechanical gripping system, such as a clamp.

In a particular embodiment of the machine according to the present invention, the welding installation comprises one or more sets of electrodes which weld the frame structures to the top longitudinal wire and optionally comprises one or more electrodes which weld each of the frame structures to a bottom longitudinal wire. In a particular embodiment of the machine according to the present invention, the first drive mechanism is mechanically coupled to the second drive mechanism, as a result of which the driving cycle of the drive mechanisms is synchronized, preferably by means of a mechanical connecting piece, such as a rod, bar, post and/or the like.

In a further embodiment of the machine, the first drive mechanism is electronically coupled to the second drive mechanism by means of an electronic connection which automatically synchronizes the driving cycle of the drive mechanisms.

In a particular embodiment of the machine according to the present invention, the welding installation comprises one or more rotating circular supports which mechanically support the top longitudinal wire during welding. Preferably, the rotating circular supports comprise a stand which is height-adjustable.

In a particular embodiment, the welding installation comprises a support which comprises a guide slat, wherein the guide slat comprises a contact line, the contact line being interrupted by a groove.

In a particular embodiment of the machine according to the present invention, the spacer has a wire diameter for the top longitudinal wire, the bottom longitudinal wires and the two frame structures of less than 5 mm, less than 3 mm and less than 3 mm, respectively.

In a second aspect, the invention relates to a method for manufacturing spacers for concrete reinforcements and/or concrete structures, comprising the following steps:

a. transporting spacers (three longitudinal wires and two frame structures) through a welding installation, and;

b. welding the top longitudinal wire to the two frame structures in the welding installation and optionally welding together each of the frame structures to a bottom longitudinal wire;

wherein step (a) is performed by a drive mechanism positioned downstream of the welding installation.

In a particular embodiment of the method according to the present invention, the method for step (a) comprises a second drive mechanism which is positioned upstream of the welding installation.

In a particular embodiment of the method according to the present invention, the method for step (a) comprises one or more drive mechanisms which clamp the spacers outside the welding installation and subsequently mechanically transport them to the position of the next welding point.

In a particular embodiment of the method according to the present invention, the method for step (a) comprises that the transport distance corresponds to the distance between the welding points or a multiple thereof. In a particular embodiment of the method according to the present invention, the method comprises that the top longitudinal wire is supported by one or more rotating circular supports during welding.

In a particular embodiment, the method comprises the following steps:

- supporting the top longitudinal wire with a support comprising a guide slat, wherein the guide slat comprises a contact line, the contact line being interrupted by a groove;

- the welding of at least one frame structure, preferably two frame structures, to the top longitudinal slat;

wherein the welding takes place where the groove is situated in the contact line of the bottom support block and the top support block.

In a particular embodiment of the method according to the present invention, the method comprises that the spacer has a wire diameter for the top longitudinal wire, the bottom longitudinal wires and the two frame structures of less than 5 mm, less than 3 mm and less than 3 mm, respectively.

In a third aspect, the present invention concerns the use of a machine according to the present invention for manufacturing spacers. DESCRIPTION OF THE FIGURES

FIGURE 1A is a diagrammatic view of a particular embodiment of the machine

(100) for producing spacers (400).

FIGURE 1 B is a diagrammatic view of a particular embodiment of the machine

(101 ) for producing spacers (400).

FIGURE 2 is a view of the welding installation according to a particular embodiment of the machine (101 ) for producing spacers (400).

Figure 3 shows a diagrammatic view of a guide slat according to the prior art (210).

Figure 4 shows a diagrammatic view of a guide slat according to an embodiment of the present invention (220). Figure 5 shows an end-side view of a girder whose top longitudinal wire (403) is supported by a guide slat (220) according to a particular embodiment of the present invention. DETAILED DESCRIPTION

As used below in this text, the singular forms "a", "an", "the" include both the singular and the plural, unless the context clearly indicates otherwise.

The terms "comprise", "comprises" as used below are synonymous with "including", "include" or "contain", "contains" and are inclusive or open and do not exclude additional unmentioned parts, elements or method steps. Where this description refers to a product or process which "comprises" specific features, parts or steps, this refers to the possibility that other features, parts or steps may also be present, but may also refer to embodiments which only contain the listed features, parts or steps.

The enumeration of numeric values by means of ranges of figures comprises all values and fractions in these ranges, as well as the cited end points.

The term "approximately" as used when referring to a measurable value, such as a parameter, an amount, a time period, and the like, is intended to include variations of +/- 10% or less, preferably +1-5% or less, more preferably +/-1 % or less, and still more preferably +/-0.1 % or less, of and from the specified value, in so far as the variations apply to the invention disclosed herein. It should be understood that the value to which the term "approximately" refers per se has also been disclosed. All references cited in this description are hereby deemed to be incorporated in their entirety by way of reference.

Unless defined otherwise, all terms disclosed in the invention, including technical and scientific terms, have the meaning which a person skilled in the art usually gives them. For further guidance, definitions are included to further explain terms which are used in the description of the invention.

As referred to herein, an object is "elongate" if the length of that object is longer than twice the width of that object; preferably the length is longer than three, four or five times the width of the object. As used herein, the term "perpendicular" may include a certain degree of deviation from an exactly perpendicular orientation. More particularly, a first wire is deemed to be positioned perpendicularly with respect to a face or second wire if the angle between the longitudinal axis of the first wire and the face, or the angle between the longitudinal axes of the first and second wire, is between 89° and 91 °; preferably between 89.5° and 90.5°; and most preferably is 90°.

The present invention relates to a machine for producing spacers for concrete reinforcements and concrete structures, methods for manufacturing such spacers, and use thereof. Producing the spacers is achieved by first providing the present machine with separate wires and/or frame structures which will form the skeleton structure of the spacers. More particularly, the machine is provided with at least three parallel longitudinal wires, including one top longitudinal wire and two bottom longitudinal wires, which form the sides of a triangular prism. In addition, at least two further frame structures are provided, either already in a desired pattern or in the form of straight longitudinal wires which are bent to form a desired pattern. During production, each of the bottom longitudinal wires is connected to the top longitudinal wire by means of a frame structure which is placed on the outside or inside of the formed triangular prism. The connection between the longitudinal wires and frame structures is achieved by means of a welding installation which uses electrodes. During welding, the top longitudinal wire and/or spacer may furthermore be supported by means of a support. After a connection has been achieved, the machine will transport the longitudinal wire and/or spacer through the welding installation in order to make a subsequent connection possible. This transport takes place by means of a drive mechanism which can push the wires further by means of a mechanical entrainment movement.

During welding, there is a risk that a longitudinal wire will stick to certain parts of the machine, such as an electrode or the support. When this happens with machines according to the prior art, the drive mechanism will push the longitudinal wire through the welding installation, resulting in the longitudinal wire and/or spacer being bent (double) and/or torn loose. When the longitudinal wire and/or spacer become bent, the machine has to be stopped and, in the best case, the bent part is straightened by pulling, so that production may be resumed; or, in the worst case, the entire longitudinal wires/frame structures and/or spacers will have to be removed from the machine and be passed through again. If the longitudinal wire and/or spacer is torn off, the torn part has to be removed, as a result of which manufacturing of the spacer will have to restart. In both cases, production has to be stopped (downtime), resulting in an increase in both production times and production costs of spacers.

The risk of sticking increases as the diameter of the wires decreases, the production speed increases, the current to the electrode is increased, and/or when using several electrodes. However, in recent years, there is an increasing demand for ever lighter spacers to be produced in a shorter period of time which significantly increases the risk of the wires sticking with existing embodiments. The present invention comprises a solution to reduce the risk of the longitudinal wire sticking to certain parts. Should a longitudinal wire nevertheless become stuck, then the invention provides a solution to avoid bending (double) of the sticking longitudinal wire and to facilitate its release, as a result of which the risk of the sticking longitudinal wire tearing off decreases and thus the downtime of the production is significantly reduced. In addition, the invention also provides a solution for adapting the present machine to the production of spacers with different dimensions and/or diameters of the longitudinal wires/frame structures. By providing a drive mechanism downstream of the welding installation in the present invention, the longitudinal wires and/or spacers are pulled through the welding installation.

As a result of the comprised solution, the invention provided constitutes an improvement in the present method of both the production costs and production speed of spacers. In addition, the use of the invention offers the possibility of producing lighter spacers with a lower diameter of wires, which is very difficult using the methods from the prior art.

In a first aspect, the present invention provides a machine for producing spacers for concrete reinforcements and/or concrete structures, the spacers comprising three parallel straight longitudinal wires which form the sides of a triangular prism, wherein each of the bottom longitudinal wires is connected to the top longitudinal wire by means of a frame structure, the machine furthermore comprising:

a. a welding installation for welding together the two frame structures to the top longitudinal wire and optionally welding together each of the frame structures to a bottom longitudinal wire, and;

b. a drive mechanism for transporting the spacers through the welding installation;

characterized in that the drive mechanism is positioned downstream of the welding installation.

As used herein, the term "machine" comprises all terms in which an apparatus is composed of a frame, a drive mechanism and all parts/systems which are required to produce the spacers described herein. The machine is capable of converting a form of energy into a mechanical form of movement. The machine comprises all systems which are required to supply and convert energy for the use of the present machine.

As used herein, the term "spacer" is in particular intended to mean a structure which serves to keep two or more parallel concrete reinforcements, for example reinforcement mats for a flat structure, a desired distance apart. The flat structure may be a horizontal structure, such as a floor, or a vertical structure, such as a wall. The spacers may, for example, be used for keeping reinforcement mats in prefabricated (prefab) hollow walls at a distance. Such walls typically comprise two prefab concrete shells, with each concrete shell comprising a reinforcement mat. These reinforcement mats are kept a distance apart by one or more spacers. In this case, a hollow wall is produced, into which concrete may be poured at the building site.

The spacer according to the present invention comprises three longitudinal wires, in particular two bottom longitudinal wires and one top longitudinal wire. The three longitudinal wires of the spacer each form a (longitudinal) end of a triangular prism. As used herein, the term "triangular prism" refers to a longitudinal polyhedron, in which the cross section perpendicular to the longitudinal axis forms a triangular geometry. In a particular embodiment, the longitudinal edges of said polyhedron run parallel to each other.

Each of the two bottom longitudinal wires is connected to the top longitudinal wire by means of two or more frame structures.

The frame structures ensure that the relative position of the longitudinal wires is fastened, so that that the spacer is able to resist stress from the outside, such as bending. With the spacer according to the present invention, each frame structures comprises a wire which is connected to the bottom longitudinal wire at N locations and to the top longitudinal wire at N-1 and/or N+1 locations, in which N is an integer greater than 1 . In particular, N equals 2, 3, 4, 5, 6, 7, 8 or more. Each frame structure comprises a curved or bent wire; as a result of which the entire frame structure comprises one or more curved sections.

In a particular embodiment, the frame structure has a zigzag shape, such as a sinusoid or saw-tooth pattern, in which the frame structure is alternately connected to a top and bottom longitudinal wire at each bending and/or curving action.

In a further embodiment, the frame structure has a U-shaped bend or a V-shaped curve, in which the top longitudinal wire is connected to the bent or curved section of the frame structure, and each of the bottom longitudinal wires is connected to one of the ends of the frame structure.

The longitudinal wires and frame structures are preferably made of steel. In certain embodiments, the wires are not smooth, but are, for example, provided with spiral- shaped ribs. As a result thereof, the surface area of the wires increases, resulting in an improved bond of the steel and the concrete. However, this is not compulsory, so that the wires may be smooth in certain embodiments.

The diameter of the longitudinal wires and frame structures is typically between 2.0 and 10.0 mm. In certain embodiments, the diameter of the longitudinal wires and frame structures is between 2.4 and 5.0 mm. In further embodiments of lighter spacers, the diameter of the longitudinal wires and frame structures is between 2.8 and 4.0 mm.

A reduction in the diameter of the longitudinal wires and frame structures could offer a significant advantage as a result of a limitation in production material, which could possibly reduce the production price of the spacers. An additional advantage of a reduction of the diameters is that this makes it possible to produce lighter spacers. As a result thereof, the weight per meter of a spacer will be reduced, thus creating the possibility of producing spacers having a greater maximum length. Both a reduction in weight and an increase in total length could lead to a reduction in the transportation and fitting costs of the spacers.

Preferably, the top longitudinal wire has a diameter which is greater than that of the bottom longitudinal wires and the frame structures. This could offer an advantage with regard to the stability of the supporting surface of the spacers. The bottom longitudinal wires preferably have an identical diameter which may be equal to or may differ from the diameter of the top longitudinal wire. However, it is not ruled out that, in certain embodiments, the bottom longitudinal wires have a different diameter or thickness.

The diameter of the frame structures may be identical to the diameter of the longitudinal wires, or may be different.

Usually, all the frame structures of the spacer have an identical diameter or thickness. However, it is not ruled out that, in certain embodiments, the frame structures have a different diameter or thickness.

As used herein, the term "welding installation" comprises all systems in which a thermal process leads to a fusion of the longitudinal wire/frame structure provided as a base for the skeleton structure of the spacers.

In a preferred embodiment, the welding installation comprises one or more electrodes which weld the frame structures to the top longitudinal wire and, optionally, one or more electrodes which weld each of the frame structures to a bottom longitudinal wire. In a particular embodiment, the welding installation comprises one or more electrodes which weld the frame structures to the top longitudinal wire and one or more electrodes which weld each of the frame structures to a bottom longitudinal wire.

As used herein, the system of a "drive mechanism" comprises all systems which effect transportation of the longitudinal wires/frame structures and/or spacer through the machine by means of a mechanical motion. As used herein, the terms drive mechanism and driving mechanism are synonymous. As used herein, the terms "upstream" and "downstream" refer to the direction of transport of the longitudinal wires/frame structures and/or spacer through the machine; with "upstream" referring to the direction and/or position opposite to the direction of transport, and "downstream" referring to the direction and/or position in the same direction as the direction of transport.

The drive mechanism transports the spacer further to the next welding point after each welding operation, in which case the distance of the transport corresponds to the distance between the desired welding points, or a multiple thereof.

In a further aspect, the invention comprises a drive mechanism consisting of an entrainment mechanism characterized in that the drive mechanism is positioned downstream of the welding installation.

As a result of a drive mechanism being positioned downstream of the welding installation, the spacer is pulled through the welding installation. This has the advantage that when a longitudinal wire/frame structure becomes stuck to an electrode and/or support during welding, it will not bend (double), but rather be pulled loose from the electrode and/or support. In contrast to the embodiments which are customary in the prior art, the risk of possible folds of the longitudinal wire is reduced significantly as a result thereof.

If the longitudinal wire/frame structure remains stuck to the electrode, it can be released more easily due to the lack of folds and without necessarily having to restart production. This has the significant advantage that the 'downtime' of the machine for the correction of the longitudinal wires and/or spacers can be limited, which per se already results in an increased production efficiency of the machine. In a further embodiment, the drive mechanism consists of two entrainment mechanisms, characterized in that the entrainment mechanisms positioned both upstream and downstream of the welding installation to transport the wires through the welding installation.

By using two drive mechanisms, the pressure, and thus also the force on the transportation of the wires is distributed over several attachment points. This has the advantage that when a longitudinal wire becomes stuck to the electrodes during welding, it can be pulled loose more easily due to the combination of several pressure points which in addition reduces the risk of possible tearing off of the wires.

In a specific embodiment, the transport of one or more drive mechanisms would be transferred to the longitudinal wire and/or spacer by means of one or more mechanical gripping systems, preferably using a clamp, an entrainment finger or a set of pressure-exerting wheels.

The use of a clamp has the advantage that the risk of losing grip is very small. The use of a strong clamp lowers the risk of a possible slipping on the surface of the spacer and/or longitudinal wire and the possibly incorrect conveying of the transport distance.

The machine according to the present invention as described herein provides a welding installation which comprises one or more electrodes, which weld the frame structures to the top longitudinal wire and, optionally, one or more electrodes which weld each of the frame structures to a bottom longitudinal wire.

As used herein, the term "electrode" as part of the welding installation comprises any structure which converts electrical energy into thermal energy with the function of welding a longitudinal wire to a frame structure, and/or vice versa, both provided as a basis for the skeleton structure of the spacers.

As used herein, the term "set of electrodes" refers to a group of separate electrodes whose welding function is connected to each other in one welding cycle.

In a specific embodiment, a set of electrodes comprises two or several electrodes which are positioned on either side of the top longitudinal wire for simultaneous double-sided welding of the top longitudinal wire to the frame structure.

In a further embodiment, a set of electrodes comprises at least four electrodes, of which two or several electrodes are positioned on either side of the top longitudinal wire, and two or several electrodes are positioned on either side of each of the bottom longitudinal wires; in addition, the bottom electrodes may weld each of the bottom longitudinal wires on both sides, or only on one side, but be supported in that case by one or more elements placed on the reverse of the bottom longitudinal wires in order to absorb the welding pressure. In a particular embodiment, the welding installation contains one set of electrodes, which is referred to as a single pass system.

In a particular embodiment, the welding installation contains two sets of electrodes, which is referred to as a double pass system.

In a particular embodiment, the welding installation contains several sets of electrodes, which is referred to as a multiple pass system.

The use of an electrode has the advantage that welding takes place in an energy- efficient and accurate manner. Here, the speed of welding depends on the intensity of the power supply to the electrode or the resistance between the electrodes and the welding time. If the production speed of the machine has to be increased, this can be achieved in a simple manner by increasing the power intensity or welding time to the electrode.

The use of several electrodes in series ensures that several points can be welded simultaneously. This makes it possible to increase the transport distance to a multiple of the distance between the welding points, in which the multiple depends on the number of electrodes in series. As a result thereof, the production speed of the machine can be increased significantly. The machine according to the present invention provides for the first drive mechanism to be coupled to the second drive mechanism, as a result of which the operation of the drive mechanisms is synchronized.

In a specific embodiment, the transportation performed by the first drive mechanism would be mechanically coupled to the transport performed by the second drive mechanism. Preferably, this coupling would be effected by means of a mechanical connecting piece, for example a rod.

This would have the advantage that the present invention is compatible with the mechanical parts of existing embodiments. In addition, it would prevent that the two drive mechanisms on the welding system have to be adjusted (electronically); instead it suffices to only adjust one of two drive mechanisms to the welding system and to subsequently adjust the second drive mechanism to the first drive mechanism. This would increase the compatibility of the invention with existing embodiments further, and thus lower the modification costs.

In a specific embodiment, the transportation performed by the first drive mechanism would be electronically coupled to the transportation performed by the second drive mechanism.

An electronic synchronization could possibly be even more accurate than a mechanical synchronization. An electronic system would also be able to deactivate both drive mechanisms more quickly if a welding problem (sticking) is detected.

The sticking could, for example, also be recorded electronically.

By using a synchronized system, it would also be possible to increase the accuracy of the transport distance and the speed of production further.

The machine according to the present invention and as described herein furthermore provides a welding installation which comprises one or more supports.

In some embodiments, these are rotating circular supports which mechanically support the top longitudinal wire during welding.

The use of a support has the advantage that the top longitudinal wire will deform to a lesser degree on account of thermal stress resulting from welding.

In a specific preferred embodiment, the top longitudinal wire is supported by one or more rotating circular supports.

The use of a rotating circular support has the advantage that, when a longitudinal wire becomes stuck to the support during welding, it is released more easily due to the rotating movement of the support.

In addition, the rotating movement also lowers the risk of the stuck wires tearing off when these are being transported forwards by the drive mechanism.

In a specific embodiment, the top longitudinal wire is supported during welding by several rotating circular supports which have been placed in series.

The use of several supports results in a greater extension of the supporting surface and consequently in a further reduction of the risk of the longitudinal wire deforming.

The machine according to the present invention furthermore provides that rotating circular supports comprise a stand which is height-adjustable. The possibility of adjusting the height makes the machine very flexible with regard to the choice in the dimensions and/or diameter of the spacer. After all, a different height of the top longitudinal wire requires a different height of the support. The correct height is necessary in order to ensure optimum support of the longitudinal wire during welding.

In a further embodiment, the machine as described herein comprises a folding mechanism which is capable of folding a straight longitudinal wire to form a frame structure with a desired pattern.

The advantage of a folding mechanism is that no separate supply of frame structures has to be provided. This would render an external machine for shaping the frame structures obsolete.

In a specific embodiment, the top longitudinal wire is supported during welding by several rotating circular supports placed in series.

The use of several supports results in a greater extension of the supporting surface and consequently in a further reduction of the risk of the longitudinal wire deforming.

In a particular embodiment, the machine as described herein provides that the spacer has a wire diameter for the top longitudinal wire, the bottom longitudinal wires and the two frame structures of less than 5 mm, less than 3 mm and less than 3 mm, respectively, and preferably 4 mm, 2.8 mm and 2.8 mm, respectively, and preferably even thinner.

In some embodiments, a support comprises a guide slat. The guide slat comprises a contact line. The contact line is interrupted by a groove. Due to this groove, the guide slat does not make contact with the top longitudinal wire at the spot where the top longitudinal wire is welded to the frame structures. Thus, welding of the top longitudinal wire and/or the frame structures to the guide slat is avoided.

In a further aspect, the invention comprises a method for manufacturing a spacer for concrete reinforcements and/or concrete structures, comprising the following steps: (a) transporting spacers (three longitudinal wires and two frame structures) through a welding installation with a drive mechanism positioned downstream of the welding installation, and;

(b) welding the top longitudinal wire to the two frame structures in the welding installation and optionally welding together each of the frame structures to a bottom longitudinal wire;

wherein step (a) is performed by a drive mechanism positioned downstream of the welding installation.

In a further embodiment, the invention comprises a method for manufacturing a spacer for concrete reinforcements and/or concrete structures comprising the following steps:

(a) transporting spacers (three longitudinal wires and two frame structures) through a welding installation with two drive mechanisms positioned both upstream and downstream of the welding installation, and

(b) welding the top longitudinal wire to the two frame structures in the welding installation.

In the method in which one or more drive mechanisms transfer the transport movement to the longitudinal wires and/or spacers, the transfer of the transport movement is effected by means of gripping systems. In a preferred method, a clamp grips the longitudinal wires and/or spacers and the longitudinal wires and/or spacers will be transported by means of an entrainment mechanism. If a driving mechanism is positioned downstream of the welding installation, this will be effected by means of a pulling movement; if a driving mechanism is positioned upstream of the welding installation, this will be effected by a pushing movement. The method by which the transport distance is determined depends on the number of electrodes in the welding installation which are placed in series. When using one set of electrodes, the transport distance will correspond to the distance between two welding points, when using several sets of electrodes, the transport distance will correspond to a multiple X of the distance between two welding points, wherein the multiple X depends on the number of electrodes in series; for example, when using two sets of electrodes, the multiple X will equal two and the transport distance will equal two times the distance between two welding points, etcetera.

Preferably, the method comprises the following step: supporting the top longitudinal wire during welding by means of a support. In some embodiments, a support comprises a guide slat which comprises grooves, as has been described elsewhere.

In a further aspect, the invention comprises a method for welding the spacers by means of a support. In some embodiments, the support is a rotating circular support which supports the top longitudinal wire during welding using the electrodes. In some embodiments, the support comprises a guide slat which comprises grooves, as has been described elsewhere.

In a further aspect, the invention comprises a method for adjusting the height of the supports on which the spacers are supported during welding.

In a further aspect, the invention comprises the use of a machine for manufacturing spacers for concrete reinforcements and concrete structures, comprising:

(a) a welding installation for welding together the two frame structures to the top longitudinal wire and optionally welding together each of the frame structures to a bottom longitudinal wire, and

(b) a drive mechanism for transporting the spacers through the welding installation,

characterized in that the drive mechanism is positioned downstream of the welding installation. EXAMPLES

Figure 1A is a diagrammatic view of a particular embodiment of the machine (100) for manufacturing spacers (400) while providing longitudinal wires (401 ) and frame structures (402). The machine (100) comprises a welding installation (200) which welds the products by means of one or more electrodes, while the longitudinal wire is optionally supported by one or more supports (202), and a drive mechanism (300) for transporting the spacers through the welding installation by means of a gripping mechanism (301 ) coupled to an entrainment mechanism (302), characterized in that the drive mechanism is positioned downstream of the welding installation.

Figure 1 B is a diagrammatic view of a particular embodiment of the machine (101 ) for manufacturing spacers (400) while providing longitudinal wires (401 ) and frame structures (402). The machine (100) comprises a welding installation (200), a drive mechanism (300) for transporting the spacers by means of a pulling movement, characterized in that the drive mechanism is positioned downstream of the welding installation, and a drive mechanism (500) for transporting the spacers by means of a pushing movement, characterized in that the drive mechanism is positioned upstream of the welding installation.

Figure 2 is an illustration of the welding installation according to a particular embodiment of the machine (101 ) for manufacturing spacers (400). Figure 2A (front view) and Figure 2B (side view) illustrate the welding installation (200) according to a particular embodiment of the machine for manufacturing spacers according to the present invention. In the welding installation (200), the longitudinal wires (401 ) are welded to the frame structures (402) by means of electrodes (201 ). In this case, the top longitudinal wire is supported by a rotating circular support (202).

By way of further example, we refer to figures 3 and 4. Figure 3 diagrammatically shows a guide slat according to the prior art (210). Figure 4 diagrammatically shows a guide slat according to an embodiment of the present invention (220). The guide slat (210) supports the top longitudinal wire when frame structures (402) are welded to the top longitudinal wire (401 ) during a welding operation, as described elsewhere.

In particular, a guide slat according to the prior art (210) comprises a contact line (214). The contact line (214) is uninterrupted. As a result of the uninterrupted contact line (214), the guide slat according to the prior art contacts the top longitudinal wire (401 ) along its entire length during a welding operation. This entails the risk of the girder being welded to the guide slat (210). This risk is prevented by means of a guide slat according to an embodiment of the present invention (220). In particular, a guide slat according to an embodiment of the present invention (220) comprises a contact line (224). The contact line (224) is interrupted. In particular, the contact line is interrupted by a groove (226). As a result of this groove (226), the guide slat (220) does not contact the top longitudinal wire (401 ) at the location where the top longitudinal wire (401 ) is being welded to the frame structures. In this way, the top longitudinal wire (401 ) and/or the frame structures are prevented from being welded to the guide slat (220).

By way of further example, we refer to figure 5. Figure 5 shows a head-end view of a girder whose top longitudinal wire (403) is supported by a guide slat (220) according to the present invention. The girder furthermore comprises bottom longitudinal wires (404) and frame structures (402).

In particular, the guide slat (220) comprises a bottom side (227) and a top side (228). Both the bottom side (227) and the top side (228) of the guide slat (220) comprise a groove (see figure 4). Thus, the guide slat (220) can be reversed when one side (the top side (227) or the bottom side (228)) is worn after multiple welding operations.