EP0362055A1 - Method and installation for manufacturing smooth steel wire with a small cross section - Google Patents

Abstract

The installation comprises a single tank at the entrance for containing a lubricant, an assembly of wire-drawing roller blocks, each comprising two pairs of rollers (1, 2; 3, 4) arranged in the vicinity of one another along planes perpendicular to one another which contain the wire and which are respectively parallel to first and second predetermined reference directions (V, H), in order to produce, during successive cold-rolling passes, progressive cross- sectional reductions, a calibrating roller block located downstream of the wire-drawing roller blocks and comprising two pairs of rollers arranged in the vicinity of one another along planes perpendicular to one another which contain the wire and are respectively parallel to the said first and second reference directions (V, H), in order to carry out a very small additional pass effecting only a reduction of the diameter of the wire at most equal to approximately one tenth of a millimetre, a first series (160) of an odd number of straightening rollers (161-165) arranged in staggered formation in a first plane parallel to the said first reference plane (V), and a second series (170) of the same odd number of straightening rollers (171-175) arranged in staggered formation in a second plane parallel to the said second reference plane (H). The invention is used particularly for making smooth steel wires for welded concrete-reinforcing grids. <IMAGE>

Description

The subject of the present invention is a method and an installation for manufacturing smooth steel wire of small section having a diameter of between approximately 3 and 4.5 mm from steel wire rod having a diameter of between approximately 5 and 6 , 5 mm, by cold deformation by successive passes for the production of concrete reinforcement or welded mesh.

Smooth steel wire for the manufacture of concrete reinforcement or welded mesh must have a certain number of specific characteristics which are linked either to the need to carry out assemblies by electric welding in the case of welded mesh, or more generally for end use in reinforced concrete. Thus, the surface condition of the smooth wires produced is important in view of the subsequent operations carried out on these wires, but the mechanical characteristics of the steel wires at the end of their manufacture are essential in order to guarantee users conditions of use which respect various safety standards and rules.

It is known that the transformation of a steel wire by wire drawing with appreciable reduction of the section is measured by a rate of work hardening and that the rate of work hardening has an inverse influence on the yield strength and elongation at break , the elastic limit increasing with the rate of work hardening while the elongation at break decreases with the rate of work hardening. In order to reduce the mass of the reinforcements used, it is desirable to be able to increase the rate of work hardening. This trend, however, comes up against limits due to the need to guarantee a sufficient elongation at break as well as an elongation under maximum load also sufficiently significant, this last criterion making it possible to guarantee plastic deformation of the steel without degradation of its properties. mechanical. This last characteristic depends very much on the way in which the smooth wire was made from the wire rod.

Multipass wire drawing machines of various types are already known in the conventional way which make it possible to produce smooth metallic wires of small diameter, for example of the order of 3 to 4.5 mm, from wire rod of larger cross section obtained by rolling to hot. These drawing machines include several die-capstan assembly allowing successive passes to arrive at the desired work hardening rate.

However, the significant work hardening obtained by cold drawing and the very nature of the drawing process lead to several major drawbacks.

The brittleness of the wire produced by cold drawing is great, the wire undergoes a loss of elongation, in particular at the level of plastic deformation, and it is not possible to control the residual stresses within the highly cold worked steel. nor by guaranteeing a reliability of the diameter of the wire produced. The drawing lubricant, such as soap powder, applied to each pass forms on the surface of the wire a harmful layer for the subsequent operations, in particular welding, which are carried out on the wire. The energy consumption of wire drawing machines is always high. The dies wear out quickly, causing production stoppages. Finally, wire breaks during drawing due to the brittleness of the metal and the significant tensile force in the dies are relatively frequent.

In the case of the production of welded mesh, a descaling operation is generally generally carried out before drawing and after a drawing operation after drawing, which are intended to facilitate welding. These descaling and straightening operations are carried out on machines independent of the wire drawing machines and associated with the welding installations. The straightening operation makes it possible to better prepare the wire before the welding operation but does not reduce the brittleness of the wire and cannot remedy the various drawbacks mentioned above.

The present invention aims to remedy the various aforementioned drawbacks and to improve both the quality of the wire produced by increasing the elongation characteristics of the wire, productivity by limiting production stoppages and profitability by reducing manufacturing costs.

The object of the invention is also to allow an improvement in the quality of the product and an increase in productivity by reusing part of the existing wire drawing installations which can be easily adapted to constitute machines in accordance with the present invention at a reduced cost, which limits investments.

• a) introduire le fil machine sélectionné dans un réservoir unique contenant un produit du type savon pour lubrifier le fil,
• b) introduire en continu le fil lubrifié dans des blocs successifs de tréfilage à galets assurant chacun un laminage à froid par déformations orthogonales dans des plans perpendiculaires à l'aide de deux paires de galets disposées au voisinage l'une de l'autre selon des plans perpendiculaires entre eux contenant le fil et respectivement parallèles à des première et seconde directions de référence prédéterminées afin de réaliser au cours de passes successives des réductions progressives de section avec des taux d'écrouissage déterminés dégressifs compris entre environ 28 et 15%,
• c) introduire en continu le fil laminé à froid issu de la dernière passe dans un bloc de calibrage à galets comprenant deux paires de galets disposées au voisinage l'une de l'autre selon des plans perpendiculaires entre eux contenant le fil et respectivement parallèles auxdites première et seconde directions de référence pour réaliser une très faible passe supplémentaire n'apportant qu'une réduction de diamètre du fil au plus égale à environ un dixième de millimètre, et
• d) redresser en continu le fil laminé à froid et calibré par passage du fil entre des première et seconde séries d'un nombre impair de galets de redressage disposés en quinconce dans des plans perpendiculaires entre eux contenant le fil et respectivement parallèles auxdites première et seconde directions de référence, les galets de redressage presentant un diamètre inférieur à celui des galets de laminage ou de calibrage.

These aims are achieved by a method of manufacturing smooth steel wire of small cross section representing a diameter of between approximately 3 and 4.5 mm from steel wire rod having a diameter of between approximately 5 and 6.5 mm. , characterized in that it comprises the following stages:

• a) introduce the selected wire rod into a single tank containing a soap-type product to lubricate the wire,
• b) continuously introducing the lubricated wire into successive blocks of roller drawing each ensuring cold rolling by orthogonal deformations in perpendicular planes using two pairs of rollers arranged in the vicinity of one another according to mutually perpendicular planes containing the wire and respectively parallel to first and second predetermined reference directions in order to achieve, during successive passes, progressive reductions in section with determined decreasing work hardening rates of between approximately 28 and 15%,
• c) continuously introducing the cold rolled wire from the last pass into a roller calibration block comprising two pairs of rollers arranged in the vicinity of one another along planes perpendicular to each other containing the wire and respectively parallel to said first and second reference directions to achieve a very low pass additional bringing only a reduction in wire diameter at most equal to about one tenth of a millimeter, and
• d) continuously straightening the cold-rolled and calibrated wire by passing the wire between first and second series of an odd number of straightening rollers staggered in planes perpendicular to each other containing the wire and respectively parallel to said first and second reference directions, the straightening rollers having a diameter smaller than that of the rolling or calibrating rollers.

Such a process, which combines the known cold rolling and straightening processes, makes these two rolling and straightening operations compatible with each other, and thus makes it possible to better control these stresses within the metal which has kept the orthogonal orientations in memory. deformation. The qualities of the product obtained are thus greatly improved. In addition, all the drawbacks specific to the drawing process are themselves eliminated.

Another subject of the invention is an installation for manufacturing smooth steel wire of small section, in particular for concrete reinforcement or welded mesh from wire rod by cold deformation in successive passes, characterized in that it includes a single inlet reservoir to contain a soap powder lubricant, a set of roller drawing blocks each comprising two pairs of rollers arranged in the vicinity of one another in perpendicular planes containing the wire and respectively parallel to first and second predetermined reference directions in order to achieve, during successive passes by cold rolling, progressive reductions in section with determined decreasing work hardening rates of between approximately 28% and 15%, a calibration block with rollers arranged downstream of the roller drawing blocks and comprising two pairs of rollers arranged in the vicinity one of e the other along planes perpendicular to each other containing the wire and respectively parallel to said first and second reference directions to achieve a very small additional pass providing only a reduction in wire diameter at most equal to about one tenth of a millimeter, a first series of an odd number of straightening rollers arranged in staggered rows in a first plane parallel to said first reference direction and a second series of the same odd number of straightening rollers staggered in a second plane parallel to said second reference direction.

Each roller drawing block comprises a first pair of rollers located in a plane parallel to said first reference direction and comprising grooves of oval cross section, and a second pair of rollers located immediately downstream of the first pair of rollers in a plane parallel to said second reference direction and comprising grooves of circular section.

According to a particular aspect of the present invention, which makes it possible to limit the investments necessary for the implementation of the method according to the invention, the installation comprises a frame of wire drawing bench, traction capstans, speed control jacks and deflection pulleys of a wire drawing bench of the direct passage type without sliding and without torsion usually arranged between wire drawing blocks made up of a soap powder reserve and a die and the roller rolling blocks are arranged at the location of the conventional drawing blocks on the frame of the drawing bench.

• - la figure 1 est une vue schématique de dessus d'une installation de fabrication de fil d'acier lisse selon la présente invention,
• - la figure 2 est une vue schématique en perspective montrant la combinaison d'une opération de laminage à froid à quatre galets et d'une opération de redressage selon deux plans orthogonaux sur une même chaîne en continu, conformément à l'invention,
• - les figures 3 et 4 sont des sections agrandies montrant la forme des gorges des galets des première et deuxième paires de galets d'un bloc de laminage tel que celui représenté sur la figure 2,
• - la figure 5 est une vue en perspective d'une partie de l'installation de fabrication de fil lisse selon l'invention montrant des éléments communs avec un banc de tréfilage, et
• - la figure 6 est une vue schématique en élévation d'un bloc de laminage d'une installation de fabrication de fil lisse selon l'invention.

Other characteristics and advantages of the invention will become apparent from the following description of a particular embodiment of the invention, with reference to the appended drawings, in which:

• FIG. 1 is a schematic top view of an installation for manufacturing smooth steel wire according to the present invention,
• - Figure 2 is a schematic perspective view showing the combination of a cold rolling operation with four rollers and a straightening operation in two planes orthogonal on the same continuous chain, in accordance with the invention,
• FIGS. 3 and 4 are enlarged sections showing the shape of the grooves of the rollers of the first and second pairs of rollers of a rolling block such as that shown in FIG. 2,
• FIG. 5 is a perspective view of part of the installation for manufacturing smooth wire according to the invention showing elements common to a wire drawing bench, and
• - Figure 6 is a schematic elevational view of a rolling block of a smooth wire manufacturing installation according to the invention.

FIG. 1 schematically shows a top view of the assembly of an installation according to the invention making it possible to continuously manufacture in a simple manner with high productivity a smooth wire of small section and having good mechanical characteristics, from 'A wire rod obtained by hot rolling such as a wire of diameter equal for example to 5.50 or 6.50 mm. The wire produced can have a diameter for example of 3 mm, 3.50 mm, 4 mm or 4.50 mm.

The wire rod is made of carbon steel such as hot rolled electrical steel.

The installation 100 of FIG. 1, part of which is shown in perspective in FIG. 5, can present the general configuration of a traditional multi-pass wire drawing bench with a succession of stations arranged in series and treating the wire continuously to reduce its section on each pass. For example, Figure 1 shows an installation 100 with four passes, but a different number of passes, for example between three and six is quite possible.

Preferably, as shown in FIGS. 1 and 5, the installation comprises at each work station, on a frame 180, a traction capstan 111, 112, 113, 114, a speed control jack 121, 122, 123 , 124 and a return pulley 132, 133, 134, 135 so as to define a machine for direct passage of the wire without slipping or twisting thereof unlike the case of wire drawing machines of the accumulation type.

The installation according to the invention may thus include a certain number of elements common to known wire drawing machines, such as the frame 180, the traction capstans 111 to 114, the jacks 121 to 124, the deflection pulleys 131 to 135 as well as the drive elements (electric motors, reducers) or cooling of the capstans 111 to 114.

Unlike conventional drawing machines which have reservoirs of lubricant known as soap boxes at each station, the machine of FIG. 1 only has a single reservoir 140 of lubricant of the soap powder type placed at the entrance to the installation 100 and which is sufficient for all the cold deformation operations then carried out continuously in several passes within the installation 100. Furthermore, the installation 100 does not have any die unlike conventional drawing machines.

According to the invention, at each pass, a block 101, 102, 103, 104 of roller drawing, which in fact ensures a cold rolling operation, acts on the wire of progressively reduced section, identified by the successive references 10a, 11, 12, 13, to further reduce its section even more. After the last pass in the roller block 104, the wire 14 is introduced into a roller calibration block 105 whose structure may be similar to that of the rolling blocks 101 to 104, but which achieves only a very weak pass . The wire 15 calibrated in the block 105 is then subjected to a straightening or relaxation operation in a first straightening block 160, then the wire 16 straightened in the block 160 is subjected to a second straightening operation in a second straightening block 170 to provide a smooth wire 17 of small section ready for use to form a concrete reinforcement or used for the production of welded mesh.

An essential characteristic of the present invention resides in the manner in which all the cold deformations of the steel wire are carried out within the installation 100 to guarantee the production of a smooth steel wire with improved and controlled characteristics.

As already indicated above, in conventional wire drawing installations, the use of dies does not make it possible to control the residual stresses in the work hardened metal. In addition, the straightening operations are carried out completely independently of the drawing, which does not ensure an optimized release of stresses. In the case of using known techniques of cold rolling by passing the wire between two rollers arranged at 180 ° from one another or between three rollers arranged at 120 ° from one another, it does not Nor is it envisaged to control the final deformations of the steel, which does not make it possible to obtain smooth wires of improved quality.

According to the invention, within the installation 100, a cold deformation of the starting machine wire is carried out which combines a cold rolling process and a straightening process by making them compatible with one another with a view to improving the metallurgical plan of the final product manufactured continuously while improving productivity.

During successive passes, the lubricated wire 10a passes through the blocks 101 to 104 of roller drawing which each provide cold rolling by orthogonal deformations in perpendicular planes using two pairs of rollers 1, 2, 3, 4 (FIG. 2) arranged in the vicinity of one another along planes perpendicular to each other containing the wire and respectively parallel to first and second predetermined reference directions which can be for example a vertical direction V and a horizontal direction H .

The calibration block 105 itself comprises two pairs of rollers comparable to the rollers 1, 2, 3, 4 of the blocks 101 to 104 and arranged in the same way in two orthogonal planes parallel to the directions V and H.

The first straightening block 160 comprises a first series of an odd number, for example 5, 7 or 9, of straightening rollers 161 to 165 having a diameter smaller than that of the rolling or sizing rollers 1, 2, 3, 4 and staggered in a plane containing the wire 15 and parallel to the predetermined vertical direction V.

The second straightening block 170 comprises a second series of the same odd number, for example 5, 7 or 9, of straightening rollers 171 to 175 having the same diameter as that of the straightening rollers 161 to 165 and staggered in a plane containing the wire 16 and perpendicular to the plane of the rollers 161 to 165, thus being parallel to the predetermined horizontal direction H.

Insofar as the steel wire itself does not undergo any twist, either between the different rolling passes, or between the last rolling pass in the roller drawing block 104 and the calibration block 105, or between the calibration block 105 and the two series 160, 170 of straightening rollers, it is guaranteed that all of the cold deformations operated continuously on the installation 100 are carried out in well-defined orthogonal directions and the straightening of the wire can -Even be operated in optimized conditions due to the conservation in memory of the direction of deformation of the metal and the action of the straightening rollers in a manner compatible with the orthogonal deformation of the hardened steel.

As shown in Figures 3 and 4, it is advantageous that the rollers 1, 2 of the first pair of rollers 1, 2 placed vertically and acting first on the wire within a bl ° C of cold rolling 101, 102, 103 or 104, have grooves 81, 82 of oval cross section with a larger groove dimension in the direction parallel to the axis of the rollers 1, 2. On the contrary, the rollers 3, 4 of the second pair of rollers placed horizontally and acting immediately downstream of the first pair of rollers, for example at a distance of the order of a few centimeters, have grooves 83, 84 of circular section. The rollers of the calibration block 105 can have the same configuration as the rollers 1 to 4 of the cold rolling blocks 101 to 104. However, it is also possible, for the operation of calibration, to use four rollers with circular grooves, insofar as the calibration block 105 essentially aims to guarantee the reliability of the final diameter as well as the metric mass and achieves only a very small pass of the order of a tenth of millimeter.

In the rolling blocks 101 to 104, the hardening rates used are a function of the diameters of input and output wire and aim to maintain an identical metal flow rate on each pass. In principle, the blocks 101 to 104 carry out progressive successive reductions in section with successive passes with determined decreasing work hardening rates of between approximately 28 and 15%.

FIG. 6 shows an exemplary embodiment of a rolling block with two pairs of rollers 1, 2, 3, 4, such as block 101, but all the blocks 101 to 105 may have structures similar to that of the first block 101 shown in Figure 1. Clevis 201, 202 supporting the axes 221, 222 of the rollers 1, 2 of the first pair of rollers placed vertically are mounted around axes 211, 212 on a support frame 91 fixed on the base 90 of the block 101 intended to be mounted on the frame 180. Adjusting screws 231, 232 allow the position of the yokes 201, 202 to be slightly modified by rotation about the axes 211, 212 in order to adjust the spacing between the rollers 1, 2.

Similarly, two yokes 203, 204 for supporting the axes 223, 224 of the rollers 3, 4 of the second pair of rollers placed horizontally are mounted around axes 213, 214 on a second support frame 92 fixed on the base 90 or the first frame 91. Adjustment screws 233, 234 make it possible to adjust the spacing between the rollers 3, 4 by rotation of the yokes 203, 204 around the axes 213, 214.

The references 251, 252, 253, 254 designate the cooling water supply and return conduits towards the screeds 201 to 204 for supporting the rollers 1 to 4. The circulation of water through the screeds supporting the rollers and the axes of these rollers makes it possible to efficiently dissipate the heat created during the rolling of the wire 10a which after passage between the grooves 81, 82 of the rollers 1, 2 then the grooves 83, 84 of the rollers 3, 4 has undergone hardening and orthogonal deformations well oriented and leaves with a reduced section (section of wire 11).

In order to show the impact of the implementation of the combination of rolling and straightening carried out in accordance with the invention, with pairs of rolling rollers arranged in two perpendicular planes and series of straightening rollers arranged in the planes perpendicular to each other corresponding to the planes of the rolling rollers, the table below gives series of elongation measurements under maximum load (Agt) expressed in percent recorded during three comparative tests carried out a) during a conventional drawing operation, b) during a conventional rolling operation, and c) during combined rolling and straightening operations carried out according to the invention.

It can be seen that the average value of the Agt for measurements carried out during the test relating to the present invention (2.76%) is much higher than the average values corresponding to the tests relating to conventional wire drawing operations (1, 06%) and rolling (1.96%).

Claims (11)

1. A method of manufacturing smooth steel wire of small section representing a diameter of between approximately 3 and 4.5 mm from steel wire rod having a diameter of between approximately 5 and 6.5 mm, characterized in that '' it includes the following stages: a) introducing the selected wire rod into a single reservoir (140) containing a product of the soap type for lubricating the wire (10a), b) continuously introducing the lubricated wire (10) into successive blocks (101 to 104) of roller drawing each ensuring a cold rolling by orthogonal deformations in perpendicular planes using two pairs of rollers (1,2 ; 3,4) arranged in the vicinity of one another along planes perpendicular to each other containing the wire and respectively parallel to first and second directions of reference (V, H) predetermined in order to achieve during successive passes of the progressive reductions in section with degressive determined work-hardening rates of between around 28 and 15%, c) continuously introducing the cold rolled wire (14) from the last pass into a roller calibration block (105) comprising two pairs of rollers arranged in the vicinity of one another in perpendicular planes containing them the wire and respectively parallel to said first and second reference directions (V, H), to achieve a very small additional pass providing only a reduction in diameter of the wire at most equal to about one tenth of a millimeter, and d) continuously straightening the cold-rolled and calibrated wire (15) by passing the wire between first and second series (160, 170) of an odd number of straightening rollers (161, 165; 171, 175) arranged in staggered in planes perpendicular to each other containing the wire and respectively parallel to said first and second reference directions (V, H), the straightening rollers (161-165, 171-175) having a diameter smaller than that of the rolling rollers or calibration (1,2,3,4). 2. Method according to claim 1, characterized in that during the successive stages of cold rolling by orthogonal deformations the wire whose section is to be reduced is introduced between a first pair of rollers (1,2) located in a plane parallel to said first reference direction (V) and comprising grooves (81, 82) with oval cross-section, then between a second pair of rollers (3,4) situated in a plane parallel to said second reference direction (H) and comprising grooves with circular section (83, 84). 3. Method according to claim 1 or claim 2, characterized in that the number of passes during the successive cold rolling steps is between three and six. 4. Installation for manufacturing smooth steel wire of small section, in particular for concrete reinforcements or welded mesh from wire rod by cold deformation in successive passes,
characterized in that it comprises a single reservoir (140) at the inlet for containing a soap powder-based lubricant, a set of roller drawing blocks (101 to 104) each comprising two pairs of rollers (1,2; 3,4) arranged in the vicinity of one another according to perpendicular planes between them containing the wire and respectively parallel to first and second predetermined reference directions (V, H) to achieve during successive passes by cold rolling progressive reductions in section with degressive determined work hardening rates of between approximately 28% and 15%, a grading block with rollers (105) arranged downstream of the drawing blocks with rollers (101 to 104) and comprising two pairs of rollers arranged in the vicinity of one another along planes perpendicular to each other containing the wire and respectively parallel to said first and second reference directions (V, H) to achieve a tr ès weak additional pass bringing only a reduction in diameter of the wire at most equal to about a tenth of a millimeter, a first series (160) of an odd number of straightening rollers (161-165) arranged in staggered rows in a foreground parallel to said first reference plane (V) and a second series (170) of the same odd number of straightening rollers (171-175) staggered in a second plane parallel to said second reference plane (H). 5. Installation according to claim 4, characterized in that each bl ° C of roller drawing (101 to 104) comprises a first pair of rollers (1,2) located in a plane parallel to said first reference direction and comprising grooves (81, 82) of oval cross section, and a second pair of rollers (3, 4) located immediately downstream of the first pair of rollers (1, 2) in a plane parallel to said second reference direction (H) and comprising circular section grooves (83, 84). 6. Installation according to claim 4 or claim 5, characterized in that the first and second reference directions (V, H) are respectively a vertical direction and a horizontal direction. 7. Installation according to any one of claims 4 to 6, characterized in that it comprises between three and six blocks of wire drawing with rollers (101 -104) 8. Installation according to any one of claims 4 to 7, characterized in that the first and second series of straightening rollers (160, 170) each comprise 5, 7 or 9 straightening rollers. 9. Installation according to any one of claims 4 to 8, characterized in that each block of roller drawing (101 to 104) comprises means (231 to 234) for adjusting the relative position of the rollers (1, 2 , 3, 4) of each pair of rollers. 10. Installation according to any one of claims 4 to 9 characterized in that each block of roller drawing (101 to 104) comprises a circuit (251 to 254) of cooling water of the first and second pairs of rollers (1 , 2, 3, 4). 11. Installation according to any one of claims 4 to 10, characterized in that it comprises a frame (180) of wire drawing bench, traction capstans (111 to 114), puppets speed control (121 to 124) and deflection pulleys (131 to 135) of a drawing bed of the direct passage type without sliding and without twisting usually arranged between drawing blocks made up of a reserve of powder soap and a die and in that the roller rolling blocks (101 to 104) are arranged at the location of the conventional wire drawing blocks on the frame (180) of wire drawing bench.

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