NL2009282C2

NL2009282C2 - Method, apparatus and arrangement for manufacturing reinforcement steel, and reinforcement steel manufactured therewith.

Info

Publication number: NL2009282C2
Application number: NL2009282A
Authority: NL
Inventors: Wilhelmus Josephus Beek
Original assignee: Znd Draad B V
Priority date: 2012-08-03
Filing date: 2012-08-03
Publication date: 2014-02-06
Also published as: EP2862645B1; EP2862645A1

Abstract

Method of manufacturing reinforcement steel for reinforcement of concrete structures, said reinforcement steel having an elongated shape of arbitrary length and cross-section, said method comprising the steps of: providing a steel base wire, rolling the steel base wire for modifying a cross-sectional dimension thereof and for creating a bonding profile on a surface of said wire. The method further comprises, prior to the step of rolling, the step of surface layer breaking for breaking of a surface layer and surface cleaning of said steel base wire for removing the surface layer from said steel base wire, and, subsequent to said step of rolling, applying a plurality of bending actions to the steel base wire for improving tensile properties thereof, such as to provide said reinforcement steel having a tensile strength to yield strength ratio R_m/R_e of at least 1,08, and having a percentage uniform elongation at maximum force A_gt of at least 5,0.

Description

Titel: Method, apparatus and arrangement for manufacturing reinforcement steel, and reinforcement steel manufactured therewith.

Field of the invention

The present invention is directed to a method of manufacturing reinforcement steel for reinforcement of concrete structures, said reinforcement steel having an elongated shape of arbitrary length and cross-5 section, said method comprising the steps of: providing a steel base wire; and rolling the steel base wire for modifying a cross-sectional dimension thereof, and for creating a bonding profile on a surface of said wire.

The invention is further directed to an apparatus for use in a method as described above, and to a manufacturing arrangement for 10 performing the method described. Moreover, the invention is directed at reinforcement steel manufactured using a method as described.

Background

Roughly since the second half of the twentieth century, concrete 15 has become the preferred choice of building material for building all kinds of structures. Its popularity is evidently based on the fact that it is conveniently mouldable in any preferred shape (enabling for example prefabrication) while at the same time it provides a very strong and durable building material.

20 An important factor in providing the strength and robustness of concrete is the use of embedded reinforcement steel inside the concrete. The reinforcement steel for example determines how well a concrete structure can withstand vibrations or shocks. To this end, the industry and governmental bodies have defined standards for the use of various kinds of 25 reinforcement steel for different purposes. For example, an office building in an arbitrary environment and subject to average weather and geologic 2 conditions (i.e. a low risk area) may safely be build using concrete with reinforcement steel having relatively relaxed properties with respect to it’s yield strength. On the other hand, a highway bridge to be built for spanning a ravine in an area where earthquakes are known to happen from time to 5 time, must be designed to withstand the most extreme conditions. Such a bridge may be built using concrete with reinforcement steel with excellent properties with respect to tensile strength and yield strength.

Since the production method of reinforcement steel plays an important role in determining the properties of the end product, until 10 recently, the European standards for reinforcement steel distinguished the reinforcement steel types based on their manner of manufacturing. As known to the skilled person, if reinforcement steel is manufactured and rolled at high temperatures in a blast-furnace, the properties with respect to the capacity to withstand vibrations and tensile forces improve. Therefore, 15 the former classification well distinguished the high-grade reinforcement steel types from the lower-grade types. However, this manner of standardizing also comes with disadvantages. For example, although one would expect that the furnace based production methods usually provide high-grade metals, the classification leaves room for errors - i.e. furnace 20 manufactured reinforcement steel being of accidental low-grade due to errors in the production process. Moreover, this standardisation only enabled the definition of two classes, being FeB500HKN (low grade) and FeB500HK/HWL (high grade) where the indications HKN, HK and HWL indicated the production process.

25 Since recently, the standardization has been adapted and is now only based on the properties of the end product. The existing European norms presently categorizes reinforcement steel types in three different ductility classes, being B500A, B500B and B500C, where the classes A and B more or less correspond to the earlier two classes and the additional class 30 B500C is a new class indicating very high grade reinforcement steel. Where 3 the number 500 in fact indicates the mandatory yield strength of the reinforcement steel (which must be 500 MPa or higher), the classes further define the property ranges in terms of two parameters: the tensile strength to yield strength ratio Rm/Re, and the percentage uniform elongation at 5 maximum force Agt. These latter two parameters are different for each of the classes B500A, B500B and B500C.

Existing methods for production of reinforcement steel are not really different from how it has been done for years; only the standardization has changed. This comes to no surprise, since the technical 10 reality has not changed either. It is still furnace based manufacturing methods that enable to provide reinforcement steel types that satisfy the requirements of high grade steel types in classes B500B and C. The cold methods performed at room temperatures on steel base wire give rise to micro fractures, making the steel more prone to metal fatigue. An example 15 of such a micro fracture can be seen in figure 6 (inside the white circle), which provides a photo taken with an scanning electron microscope of a micro fracture at the surface of a reinforcement steel wire. In this respect, it is to be noticed that the cold methods differ from the furnace based methods in that the rolling step for imprinting a profile on the wire is performed 20 outside a furnace. In the furnace based methods, the rolling step is performed inside a furnace and an axial stretching step is performed after leaving the furnace.

A disadvantage of the present manufacturing methods for making high grade reinforcement steel of class B500B, however, is that furnace 25 based processing steps leave a thin oxidation layer on the surface of the reinforcement steel. By performing the rolling process inside the furnace, causes the reinforcement steel to have an irregular cross-sectional shape. This is known to be problematic when the reinforcement steel is later processed after manufacturing (e.g. when being lashed or otherwise handled 30 by a client). On the other hand, the existing cold processes only yield low 4 grade reinforcement steel types, and cannot be applied for achieving the more stringent requirements in terms of material properties required for B500B type steel.

5 Summary of the invention

In view of the above, it is an object of the present invention to provide a method of manufacturing high grade reinforcement steel that may be performed at low temperatures, preferably room temperature. It is a further object of the invention to provide such a method enabling at least 10 the production of reinforcement steel satisfying the standard for B500B type steels.

The above mentioned objects of the invention are achieved in that there is provided a method of manufacturing reinforcement steel for reinforcement of concrete structures, said reinforcement steel having an 15 elongated shape of arbitrary length and cross-section, said method comprising the steps of: providing a steel base wire; and rolling the steel base wire for modifying a cross-sectional dimension thereof, and for creating a bonding profile on a surface of said wire; characterized in that, the method further comprises a step of applying a plurality of bending actions to the 20 steel base wire for improving tensile properties thereof, such as to provide said reinforcement steel having a tensile strength to yield strength ratio Rm/Re of at least 1,08, and having a percentage uniform elongation at maximum force Agt of at least 5,0.

The threshold properties for providing B500B type standardized 25 reinforcement steel is that the parameter tensile strength to yield strength ratio Rm/Re of the reinforcement steel is at least 1,08 as presently defined, and that the percentage of total or uniform elongation at a maximum force Agt is at least 5,0. For reinforcement steel on a roll the latter, the uniform elongation at a maximum force Agt, must even be 5,5. As will be appreciated 30 although these thresholds are not expected to be redefined in the future, 5 these thresholds are merely definitions following from agreement between industry and governmental bodies which maybe subject to change.

The inventive concept surprisingly has found a manner of fabricating high grade reinforcement steel satisfying the requirements for at 5 least class B500B, wherein the step of rolling of the reinforcement steel is be performed at low temperatures (i.e. outside (or after the steel base wire has left) the furnace). The inventive manner as described above is based on insight in the material processes taking place in a steel wire upon bending the wire. The inventors have recognised that after applying just a few 10 bending actions the properties of the metal wire in terms of the above mentioned parameters will in fact improve. This can surprisingly be applied successfully to such an extend that it becomes possible to create reinforcement steel falling within the class requirements for B500B. This process enables to improve the properties of steel base wire in such a 15 manner that a B500B class type reinforcement steel wire may be achieved using a cold process. Whereas existing methods for manufacturing these kinds of reinforcement steel rely on a hot rolling step inside a furnace, as will be appreciated, the inventive cold process provides an important technological advantage which allows the reinforcement steel to be produced 20 having a more accurately defined cross-sectional shape. Preferably, the bending actions are applied to the steel base wire after the step of rolling the steel base wire has been concluded.

The advantages of the method of the present invention are evident. This is due to the fact that heating of the wire in a furnace leaves a thin and 25 irregular layer of metal oxide on the surface of the steel wire. When rolling is performed inside the furnace, the oxidation surface layer will be present on the outer surface of the acquired shape provided by the rolling mill. This weak brittle surface layer easily comes of the surface of the wire in use, yielding a reinforcement steel wire with a slight irregular shape. By 30 performing the rolling step outside the furnace, the oxidation layer already 6 comes of upon cold handling of the steel base wire, and the shape is imprinted more accurately. The subsequent bending actions allow to achieve the material properties required for B500B type steel. A further advantage of the invention is that the process requires less steps and is overall more 5 easy to perform than a furnace based process.

Conventionally, the oxidation layer is at least partly removed at some point during the process by performing a surface layer breaking step, regardless of whether the process is a cold or warm production process. In accordance with the invention, a further improvement of the production 10 process has surprisingly be found. In accordance with a specific embodiment of the present invention, a further improvement of the method is achieved by performing an additional step of surface cleaning prior to the step of rolling, for removing a surface layer such as an oxidation layer from the steel base wire. This step of surface cleaning, although the specific type of 15 surface cleaning may be chosen freely by the skilled person, may comprise for example a step of brushing, polishing, spooling of the wire, a chemical treatment such as staining or a high pressure fluid jet for cleaning the wire. The conventional surface breaking step removes the major part of the oxidation layer, however, it will leave remnants of the oxide layer on the 20 surface of the steel base wire. Upon performing the cold rolling step, the rolling process pushes these small remnant parts of the oxidation layer into the steel underneath the surface, creating very small micro fractures, such as depicted in figure 6 (inside the white circle). These micro fractures have a negative effect on the strength of the reinforcement steel created.

25 The inventors have recognized that the properties with respect to metal fatigue of the reinforcement steel are greatly improved by complete removing the oxidation layer prior to rolling of the steel base wire, which may be achieved by performing an additional cleaning step in addition to the surface breaking step.

30 7

By removing the oxidation layer using an additional step of surface cleaning, the above mentioned effect is prevented from happening, yielding a stronger end product which is less prone to metal fatigue. As a result, the requirements of the high grade class B500B are more easily achieved using 5 a cold process in accordance with the present invention, including the additional surface cleaning step.

In accordance with a second aspect of the present invention, there is provided an apparatus for applying a plurality of bending actions to a steel base wire in a manufacturing method in accordance with the first 10 aspect, said apparatus comprising a plurality of consecutive roller wheels arranged in a single plane of rotation, wherein each roller wheel is rotatable by means of a shaft such as to be rotatable in the plane of rotation of the plurality of roller wheels, said roller wheels being placed such that in use for providing the bending action the steel base wire is moved across or with at 15 least a part of the circumference of each wheel.

In accordance with a third aspect of the invention there is provided a manufacturing arrangement, for the manufacturing of reinforcement steel using a method in accordance with the first aspect, said arrangement comprising: a lead-in unit for receiving a steel base wire; and a rolling 20 mill unit for a rolling the steel base wire for modifying a cross-sectional dimension thereof, and for creating a bonding profile on a surface of said wire; said arrangement characterized by further comprising an apparatus in accordance with the second aspect for applying a plurality of bending actions to the steel base wire for improving tensile properties thereof, such 25 as to provide said reinforcement steel having a tensile strength to yield strength ratio Rm/Re of at least 1,08, and having a percentage uniform elongation at maximum force Agt of at least 5,0.

The invention in accordance with the fourth aspect provides reinforcement steel manufactured using a manufacturing method as 30 described above.

8

Brief description of the drawings

The invention will further be elucidated by description of some specific embodiments thereof, making reference to the attached drawings, wherein: 5 Figure 1 schematically provides an overview of the method steps of the present invention;

Figure 2 schematically illustrates the steps of brushing and rolling of a steel base wire which may be used in accordance with the method of the present invention; 10 Figure 3 schematically illustrates an apparatus for applying bending actions in accordance with the present invention;

Figure 4 schematically illustrates how the rollers of the apparatus for applying and bending actions maybe adjusted relative to each other, in accordance with the present invention; 15 Figure 5 illustrates a manufacturing arrangement in accordance with the present invention;

Figure 6 provides a photo taken with an electron microscope of a micro fracture in the surface of a steel wire.

20 Detailed description

Figure 1 illustrates a method in accordance with the present invention.The method that starts in step 2 with the providing of a steel base wire e.g. to a production line in accordance with the present invention. The steel base wire itself is usually created using a furnace based process which 25 leaves, as an undesired side-effect, a thin irregular oxidation layer on the surface thereof. In step 3, the surface layer is broken, e.g. by twisting or vibrating the wire. In step 4, a further step of surface cleaning is performed in order to remove the oxidation layer from the surface of the steel base wire. Although the description below implements the step of surface 30 cleaning by a step of brushing of the steel base wire, the skilled person will 9 appreciate that many alternatives exist for performing a surface cleaning step, including but not limited to polishing, spooling, chemical cleaning e.g. by applying a stain or coating, or blowing using a high pressure fluid (such as air of water).

5 In step 6, a rolling action is performed on the steel base wire from a plurality of sides, for modifying the shape of the cross section or a dimension thereof (i.e. decreasing its diameter), and for imprinting a bonding profile on the surface of the wire. The bonding profile is important for providing a good bonding between the concrete and the reinforcement steel in use.

10 After the step of rolling of the steel base wire, the method in accordance with the present invention continues by a step 8 of applying a plurality of bending actions to the steel base wire for improving the tensile properties thereof. The bending actions are performed in the strain hardening regime of plastic deformation of the wire. As will be appreciated, 15 this process maybe controlled in a number of ways, e.g. by increasing the number of bending actions while decreasing the intensity of the bending actions. It has been found that applying a multiple of five bending actions provides good results with the method of the present invention. However, this should not be considered as a limitation to the invention and desired 20 results may be achieved upon applying a total of three, four, six, seven, eight, or any other number of bending actions.

After applying the bending actions in step 8, the method of the present invention continues by winding the reinforcement steel on a spindle in step 10, after which a manufacturing method is completed (12).

25 The steps 4 and 6 are schematically illustrated in figure 2. A steel base wire 15 moved in the direction of arrow 16 through a cleaning unit 17 and through a rolling mill unit 30. The surface cleaning unit 17 exists, in the present embodiment, of three steel brushes 18, 19 and 20. On the circumferential surfaces of the steel brushes 18, 19 and 20 a plurality of 30 brush hairs generally indicated by reference numeral 23 on brush 18 extend 10 radially there from. The brush hairs 23 strike upon rotation of the brushes 18, 19 and 20 in the direction indicated for example by arrows 25 and 26 on the surface of the steel base wire 15, removing the oxidation layer. Good results have been achieved by rotating the brushes 18, 19 and 20 in counter 5 direction to the direction of movement of the steel wire 15. This is indicated by the arrows 25 and 26. As will be appreciated, the brushes 18, 19, and 20 may also rotate in the other direction, and the number of brushes may differ from what is indicated in figure 2. In stead of or in addition to steel brushes, a plurality of polishing brushes may be applied.

10 In rolling mill unit 30 a plurality of rollers 33, 34 and 35 circumferentially apply a rolling action to the surface of the steel base wire 15. Each of the rollers 33,34 and 35 comprises a slightly rounded inward shape such as is indicated for roller 35 in the dashed circle 40 by reference numeral 42. In addition, the circumferential sides of each of the rollers 33, 15 34 and 35 is comprised of a plurality of surface structures 43 which create the desired bonding profile on the surface of the steel wire 15 by imprinting the pattern on the surface thereof. Arrows 37 and 38 indicate the direction of rotation of roller wheels 33 and 35. Roller wheel 34 rotates in a corresponding direction as roller wheels 33 and 35.

20 Figure 3 schematically illustrates an apparatus for applying a plurality of bending actions in accordance with the present invention. This apparatus maybe used for applying step 8 in the method illustrated schematically in figure 1. The apparatus consists of a frame 46 which is fixedly connected to the ground 48 such as to prevent moving thereof in use. 25 Extending from the base structure 46 an additional top structure 50 is present for supporting a second suspension unit 52 in an adjustable manner as will be explained below.

The bending actions itself are applied by a plurality of roller wheels 57, 58, 59, 60 and 61. The roller wheels are rotatable in a single plane of 30 rotation, and are alternately suspending from shafts at either a first or a 11 second height. The shafts extend transverse to the plane of rotation from a respective first or second suspension 53, 52. The roller wheels 57, 59, 60 and 61 are suspended from shafts from a first height. These shafts are in turn rotatably or operationally connected to a first suspension unit 53 attached to 5 the frame structure 46 of the apparatus 45. The roller wheels 58 and 60 are suspended from shafts that are in turn operatively connected to a second suspension unit 52 which is adjustably suspended from the top frame structure 50 of the apparatus 45. The adjustable suspension of the second suspension unit 52 is provided by a hydraulic cylinder 55 which allows for 10 adjusting the heights of roller wheels 58 and 60 above the level of roller wheels 57, 59 and 61 as will be explained below in connection with figure 4.

In order to apply the bending action, the sum of the radiuses of each two consecutive roller wheels 57-61 will be at least equal to or greater than the height of the shafts of wheels 58 and 60 above the level of the 15 shafts of wheels 57, 59 and 61. In terms of the wording used in connection with figure 4, the sum of the radiuses of two consecutive wheels (e.g. ri and ΐ2 in figure 4) is greater than or equal to the pitch distance di. In test performed by the inventors, working with five roller wheels, good results have been achieved using wheels having a diameter of 150 mm (i.e. r=75 20 mm), a height di ~ 50 mm and a pitch distance d2 = 150 mm. In addition, good results have been achieved with r = 125 mm, di ~ 50 mm, and d2 = 250 mm, and with r = 130 mm, di = 70 mm, and d2 = 250 mm. As will be appreciated, these are mere test results, and the invention can be applied across a much wider range of values for r, di and d2.

25 In general, it is important that a number of bending actions is applied, while the exact number of bending actions, and the intensity of each bending action (determined by r, di and d2) will differ dependent on the type of steel and should be determined experimentally (e.g. by trial and error). The invention is not to be interpreted as limited to a particular choice 30 of these parameters. To this end, it is also important to mention that the 12 above dimensions have been used for the embodiment as illustrated in figure 3. However, performing bending action may be performed in a different manner than as specifically illustrated in figure 3. The skilled person will appreciate that a wire may be moved across the outer 5 circumferences of a number of wheels having smaller dimensions, instead of the illustrated embodiment wherein the wire moves in between the consecutive wheels. Moreover, the bending actions may not even be performed all in a single plane of rotation.

In use, the steel base wire 15, after leaving the roller mill unit 30, 10 will be guided via pulleys 64 and 65 to the roller wheels 57, 58, 59, 60 and 61. Each roller wheel 57-61 will apply a single bending action to the steel base wire 15 as indicated in figure 3. After applying the bending actions the steel base wire 15 is guided via pulleys 66 and 67 to a spindle (not shown in figure 3).

15 Figure 4 schematically illustrates how the rollers wheels of the apparatus for applying the bending action 45 maybe adjusted in use. As schematically illustrated in figure 4, each of the rollers 57, 59 and 61 suspends from a corresponding shaft 77, 79 and 81, and the midpoints of the shafts 77, 79 and 81 are aligned on a notional first line 70. Roller wheels 58 20 and 60 are suspended from shafts 78 and 80 which are in turn aligned on notional second line 72. The height between the first line 70 and the second line 72, di, is adjustable by means of the second suspension unit 52 and the hydraulic cylinder 55. In addition, each of the shafts 77, 78, 79, 80 and 81 is respectively connected to the first or second suspension unit 53 or 52 in such 25 a manner that the position of the shaft along either the first line 70 or the second line 72 may be adjusted such as to adjust the distance d2 between each to consecutive rollers. Moreover, the suspension of each of the roller wheels 57-61 from the shafts 77-81 is such that the roller wheels 57-61 are connected in a releasable manner such as to allow replacement of the roller 30 wheels 57-61 by different roller wheels. This may be used for adapting the 13 diameter of the wheels. As will be appreciated the manner in which apparatus 45 allows for adjustment of the various dimensions of the roller wheels 57-61 and their suspension relative to each other, allows for accurate dimensioning of the bending actions applied by the apparatus during the 5 manufacturing method.

Figure 5 schematically illustrates a manufacturing arrangement in accordance with the present invention disclosing a first spindle 92 comprising a steel base wire which is fed to the arrangement at the input thereof, Prior to the surface cleaning step, surface layer breaking unit 93 10 twists or vibrates the wire such as to break and partly remove the brittle oxidation layer on the surface. Instead of vibrating or twisting, the steel base wire may already be moved across one or more roller wheels for breaking the surface layer. Unit 94 provides the additional surface cleaning by means of a step of brushing, e.g. as indicated in figure 2 schematically.

15 The rolling of the steel base wire is performed by a roller mill unit 96, after which the steel base wire is provided to the apparatus for applying the bending action schematically illustrated by 98. After leaving apparatus 98 the reinforcement steel wire is lead to the second spindle 100 after which the manufacturing method is completed.

20 Figure 6 illustrates a micro fracture at the surface of a steel wire.

The micro fracture can be clearly seen inside the wide dashed circle in the picture, and has been discussed herein above.

The present invention has been described in terms of some specific embodiments thereof. It will be appreciated that the embodiments shown in 25 the drawings and described here and above are intended for illustrative purposes only, and are not by any manner or means intended to be restrictive on the invention. The context of the invention discussed here is merely restricted by the scope of the appended claims.

Claims

A method of manufacturing reinforcing steel for reinforcing concrete structures, wherein the reinforcing steel has an elongated shape of any length and cross-section, the method comprising the steps of: 5. providing a steel base wire; and - rolling the steel base wire to modify a cross-sectional dimension thereof, and to produce an adhesion profile on a surface of the wire, the rolling being a cold rolling; 10. characterized in that prior to the rolling step, the method further comprises: a surface layer breaking step for breaking a surface layer, and surface cleaning of the steel base wire for removing the surface layer from the steels basic thread; and wherein, following the rolling step, the method further comprises a step of applying a plurality of bending movements to the steel base wire to improve the elongation properties thereof, to provide the reinforcing steel with a tensile strength up to 20 strain ratio Rn / Re of at least 1.08 and with a percentage of uniform elongation at maximum force Agt of at least 5.0.

2. Method for claim 1, wherein the bending movements are applied by moving the steel base wire along a plurality of successive rollers, wherein for each roll to provide the bending action the steel base wire is moved over or with at least a part of the circumference of the roll.

The method of claim 2, wherein each roll is rotatable in a plane of rotation of the plurality of rollers, wherein each roll is rotatable by means of an axis, and wherein from the plane of rotation of the rollers the shafts extend alternately transversely to the plane of rotation from 5 positions along respectively a first and a second line, the first and the second line being parallel to each other and to the plane of rotation, in which for every two consecutive rolls the sum of the radii of the rolls is greater than or equal to a distance between the first and the second line for imposing the bending action on the steel base wire when the wire moves over or with the circumference of the rollers.

A method according to any one of the preceding claims, wherein the step of imposing a plurality of bending actions comprises imposing at least three bending actions.

5. Method as claimed in any of the foregoing claims, wherein the additional step of surface cleaning comprises at least one step selected from a group comprising brushing, polishing, rinsing the steel base wire, a chemical treatment such as pickling, or a high-pressure spray for cleaning of the steel base wire.

A manufacturing device for manufacturing reinforcing steel 20 using a method according to any of claims 1 to 5, wherein the device comprises: an input unit for receiving a steel base wire; and a rolling unit for performing a cold rolling step for rolling the steel base wire for modifying a cross-sectional dimension thereof, and for producing an adhesion profile on the surface of the wire; the device characterized by further comprising, in use upstream of the rolling unit, a surface cleaning unit prior to the rolling unit for applying a surface cleaning step to the steel base wire prior to the rolling step, for removing a surface layer such as an oxidation layer of the steel base wire; and, in use downstream to the rolling unit, a bending unit for imposing a plurality of bending actions on the steel base wire to improve its elongation properties, to provide the reinforcing steel with a tensile strength to elongation ratio Rn / Re of at least 1 , 08 and with a percentage of even elongation at maximum force Agt of at least 5.0.

The manufacturing apparatus of claim 6, wherein the apparatus comprises a plurality of consecutive rollers located in a single rotation plane, wherein each roller is rotatable through less of an axis such that it is rotatable in the plane of rotation of the plurality of rollers, the rollers being such are placed that in use to provide the bending action 15 the steel base wire is moved over or with at least a portion of the circumference of each roll.

8. Manufacturing device as claimed in claim 6 or 7, wherein from the plane of rotation, the axes of the rollers alternately extend transversely to the plane of rotation from positions respectively along a first and a second line, the first and the second line being parallel to each other and to the plane of rotation, in which for every two consecutive rolls the sum of the radii of the rolls is greater than or equal to a distance between the first and the second line for imposing the bending actions on the steel base wire when moving it over or with the circumference of the roller.

The manufacturing apparatus of any one of claims 6-8, wherein the shafts extending from the first line are structurally connected by a first suspension unit, and wherein the shafts extending from the second line are structurally connected by a second suspension unit, wherein at least one of the first and second suspension units is adaptably connected to a structure of the device such that adjusting the distance between the first and the second line is released in use.

Manufacturing device according to any of claims 6-9, wherein one or more of the shafts is adaptably connected to the first and second suspension unit, for releasing adjustment of the position of the first and second shafts along the first or second line, respectively .

11. Manufacturing device according to any of claims 6-10, wherein the rollers are suspended from the shafts in a removable manner, for releasing replacement thereof, for adjusting a diameter of one or more rollers in use.

12. Manufacturing device as claimed in any of the claims 6-11, wherein a peripheral side of one or more of the rollers has an inwardly round shape.

13. Reinforcing steel produced using a manufacturing method according to any of claims 1-5, or manufactured using a manufacturing device according to any one of claims 6-12, wherein the reinforcing steel has a tensile strength up to yield strength Rn / Re of at least 1.08 and a percentage of uniform elongation at maximum force Agt of at least 5.0.