RU2772767C1 - Method for manufacturing raw wire from a first metal strip and at least one other metal strip by shaping in rolls - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to a method for manufacturing raw wire (7) from a first metal strip (2) and at least one other metal strip (4) by shaping in rolls. The first (2) and at least one other metal strips (4) are made of different metals, preferably of different metals with different yield strength. By shaping in rolls with multiple rolling mill stands (G1, G2), a shell is formed in several passes from the first metal strip (2), completely covering at least one other metal strip (4) along the periphery in the final form. In the first group (G1) of rolling mill stands, first only the first metal strip (2) is imparted a rough shape in several passes. The first (2) and at least one other metal strip (4) are then jointly moulded into the final shape in the second group (G2) of rolling mill stands.

EFFECT: elongation of one of the metal strips relative to the other is prevented.

17 cl, 4 dwg

Description

The invention relates to a method for producing a raw wire from a first metal strip and at least one other metal strip by roll profiling, wherein, by profiling in rolls with several rolling stands, a sheath is formed from the first metal strip in several passes, which in the final form surrounds on the periphery at least one other metal strip, preferably completely covers.

Preferably, it is provided that the first and at least one other metal strip are made of different metals. Also, preferably, different metals are understood to mean metals which differ in their yield strength. Preferably, the yield strengths of different metals differ by a factor of at least 2, more preferably by a factor of at least 3, even more preferably by a factor of at least 4.

Preferably, such a raw wire is for use as a welding wire or a thermal spray wire. Preferably, the metal strips are unwound from the coil. Raw wire is made by profiling in rolls from strips. Roll forming is also called roll forming. In this case, the metal strips are passed between the profiling rollers, due to which the profiling of the metal strips takes place. Metal strips with different yield strength according to the invention are fed into the roller molding process separately. The metal strip used as a sheath is wider than at least one other metal strip and before forming at least one other strip, preferably with a lower, as a rule, yield strength, it is preformed separately, in in particular, approximately, give the finished shape. According to the invention, the produced raw wire can be brought to the final size, for example, by forging, rolling, drawing with reduction and/or drawing.

As a strip with a higher yield strength, a nickel strip can be used, as a strip with a lower yield strength, preferably an aluminum strip. Preferably, in this case, a pure grade with a reduced carbon content is selected for the nickel strip, which provides a NiAl compound during recrystallization annealing. NiAl-sputtering wire is used, for example, for applying high-temperature-resistant coatings, including Bond Coat (intermediate (connecting) layer) in the manufacture of turbine blades.

By slowing down the feeding of a strip with a lower yield strength into the roll forming process, this strip is prevented from elongating relative to the other and thus from the risk of being pushed out of the resulting wire and wrinkling in it. The preferential use of coiled materials allows the production of wire with greater usable length. This prevents strips with a lower yield strength from being extruded from the raw wire during sizing and subsequent forming. In order to enable stronger deformations of the material with a lower yield strength, by, in particular, limiting the width of this strip, free space is provided to be filled by the transverse flow.

BACKGROUND OF THE INVENTION

Roll profiling is a simple method for bending a single metal strip. If several metal strips are to be processed at once, the prior art uses clad metal strips which behave to a large extent like a single strip.

Significant problems arise when jointly unbonded laminated metal strips are to be profiled, in particular when these metal strips have different widths. The essence of the problem lies in the difference in the yield strength of different metals, due to which the jointly processed unbonded metal strips move relative to each other, in particular, they elongate differently.

The yield strength is understood as a characteristic of a material that reflects the amount of stress up to which the material does not exhibit long-term plastic deformation during uniaxial momentless tension, that is, up to the yield strength after the load is removed, the material elastically returns to its original shape, and when the yield strength is exceeded, it remains in a deformed state, therefore, in a tensile test - elongated.

The elongation problem still has no solution. It is even more difficult, by means of roll profiling, to obtain from metal strips a continuous wire-like cross-section in which the outer sheath consists solely of one of the elements to be joined.

US Pat. No. 3,940,964 describes the use of a clad strip of equal width layers for the manufacture of a rod-like body. From this starting material it is impossible to produce a continuous profile and, at the same time, a wire coated on all sides with a sheath. However, the technical solution of this document is not explicitly aimed at this.

In addition, US 2010/0047416 A1 describes the production of a composite wire from two layered strips, whereby in the resulting final form one metal strip forms a sheath that completely encloses the other metal strip. In this document, it is proposed to apply an aluminum strip to a wider nickel strip, both strips together first to give an approximately U-shape, and then the protruding in the width direction (perpendicular to the longitudinal direction) part of the nickel strip to be wrapped around the ends of the aluminum strip and rounded off. Thereafter, the raw wire thus obtained is further drawn to obtain a wire with a smaller cross section.

The method described in US 2010/0047416 A1 has the following disadvantages:

1. Quantitative ratio of aluminum and nickel

According to US 2010/0047416 A1, [0014], nickel and aluminum parts should be distributed in cross section, approximately uniformly and occupy the same volume. However, aluminum and nickel must be present in the cross section in the ratio required for the alloying that occurs during thermal spraying/welding/melting.

The standard for NiAl alloy is Ni 80 wt.% / Al 20 wt.% This weight ratio is converted to the surface dimensions of the strip. However, this is not described in this publication.

2. Different elongation of different metals processed together due to different yield strength

a. Strip introduction

US 2010/0047416 A1 proposes to form aluminum and nickel together from the start, either as a layered ([0015] and [0016]) or clad ([0022]) material. However, the metals have different strengths: UNS N02200 standard grade soft annealed nickel is about 100 MPa, while ENAW 1050 soft annealed aluminum is about 20 MPa.

True, when profiling in rolls, first of all, the cross section is definitely deformed; however, in order for the strip to be fed steadily, a minimum transverse pressure in the thickness direction must be exerted on the metal strip. The required roll pressure depends on the material: sufficient pressure to feed nickel steadily, for softer aluminium, already leads to a reduction in thickness. In roll forming, the energy required to shape the material is transferred from the work rolls through the work tool (rollers) in the form of pressure on the metal strip. This means that the pressure between the upper and lower working tool and the metal strip must be so great that the material of the metal strip is drawn out in the working tool and can be deformed to the specified parameters above its yield strength.

If two or more layered metal strips with different yield strengths are to be molded, then the strain energy applied can be as high as the material strength of the metal strip with the lowest yield strength allows.

In the transition zone between the still possible pressure of the working tool on the softer material and the simultaneous achievement of the pressure necessary to deform the harder material, the thickness of the softer material decreases, in front of the working tool it continuously lengthens or shrinks.

However, if a softer material could transfer the no longer required strain energy to a harder material, its thickness would be greatly reduced and it would disappear, the friction between the working tool and the metal strip would disappear, and the processing would become impossible. The working tool (rollers) would slip in a "standing" engagement.

The decrease in thickness is manifested during the rolling of the metal strip rather than as a change in width, the displaced material is the cause of the change in the length of the metal strip. A change in the length of laminated metals with different strengths simultaneously processed leads to extrusion of a softer metal strip or to the formation of folds (doubling) in a softer strip. The formation of wrinkles makes the intended forming in the subsequent rolling stand impossible. Both of these phenomena interfere with the observance of the required quantitative ratio, since as a result of the redistribution of material in the cross section, it inevitably changes.

To prevent the consequences of different length changes, the aluminum strip at the entrance to the profiling mill can be slowed down or fed with tensile stress. However, the reverse pulling action is only possible at the entrance to the first rolling stand. Although duplication in the first rolling stand is thus eliminated, different length changes cannot be compensated for in subsequent steps. Therefore, there is a risk that the resulting different length changes of the two strips during profiling in the rolls will lead to an overlap of the softer material. Both the differential change in length and the overlap cause a change in the ratio of aluminum and nickel in the cross section; wire with an unpredictably changing material ratio is unsuitable for the intended purpose.

However, the solution to the problem of preventing the elongation difference between nickel and aluminum is not, as suggested in [0016] and FIG. 4, bend the protruding sides of the nickel strip onto the aluminum strip and fix it in this way. When the aluminum strip is pre-clamped during the profiling process, the differential length change of the nickel and aluminum results in a tensile stress that can be so great that the aluminum strip first cracks and eventually breaks. When assessing the risk, it should be taken into account that in the manufacture of raw wire, about 20 technological deformation positions are required.

b. raw wire

For a given pressure exerted on the complex of two metal strips, which exceeds the yield strength of the softer metal, the softer and harder metal are deformed differently. A deformation difference is not prevented due to the fact that a closed raw wire is produced. According to US 2010/0047616 A1, [0015], two metals to be processed must be layered on top of each other. When metals are layered prior to co-working, the length available for work is limited. Experiments on the manufacture of a raw wire 6 m long showed that the aluminum insert extends from the end of the wire by 7.5-11.5 cm. Therefore, the ratio of Ni and Al in the raw wire changes significantly and unpredictably.

In contrast to that described in US 2010/0047616 A1, [0018], aluminum not only fills voids, on the contrary, it primarily elongates in the machining direction.

3. The thickness of the raw material and the need for intermediate annealing

a. Raw wire dimensions according to US 2010/0047616 A1

The diameter of the raw wire produced by the profiled wire was 6.35 to 7.63 mm (US 2010/0047616 A1 [0017]). Its cross section was not continuous (see Fig. 5 in US 2010/0047616 A1), forging, rolling or drawing was required to reduce the diameter to 2.381-3.175 mm and thereby densify the material (US 2010/0047616 A1 [0018 ]). However, a diameter reduction of about 50% already leads to a surface reduction of more than 80%.

Initial diameter End Diameter Surface reduction mm mm % 7.62 3.18 82.58 6.35 2.38 85.50

With this decrease in diameter, the wire becomes stiffer. With a reduction of more than 80%, the possibility of changing the shape of the combined wire is exhausted. Such a combined wire is so rigid that, at least in conventional devices, due to insufficient flexibility, it cannot be fed through the cable package of the welding machine.

Even if the method according to US 2010/0047616 A1 were to produce a thermal spray wire consisting of nickel and aluminum strips - which is not the case - it could not be inserted into the sprayer.

When compacted and drawn to final size, the raw wire becomes stiffer. To make it suitable, that is, soft, annealing is required. However, US 2010/0047616 A1 does not provide for annealing for good reasons:

The recrystallization temperature of nickel (from 690°C to 720°C) exceeds the melting point of aluminum (650°C). As soon as the molten aluminum comes into contact with the nickel, an exothermic reaction begins, which leads to such heating of the composition that the nickel also melts. Thus, the composite wire according to US 2010/0047616 A1 is not susceptible to softening firing.

b. Raw wire of thinner thickness

According to the research of the author, the cross section of the raw wire should be only 20% larger than the size of the compacted and solid wire obtained after sizing and size reduction. The large reduction percentage shown in US 2010/0047616 A1 [0017] and [0018] is not required if thinner starting strips are used, preferably to avoid recrystallization annealing.

The horizontal cross section shown in Fig. 1 of document US 2010/0047616 A1 of the wire consists of 10 layers of approximately the same thickness, arranged in a folded-symmetric manner: 6 of Ni and 4 of Al.

If we assume that all layers have the same thickness, then the thickness of the source material:

Final size for thermal spraying Cross section reduction Raw wire size Layer thickness Decrease Diameter Surface Required Diameter Surface Thickness mm mm² % mm mm² mm % 1.6 2.01 twenty 2.0 3.14 0.2 56.25 2.38 4.448 twenty 2.975 6.95 0.2975 56.25 3.2 8.04 twenty 4.0 12.57 0.4 56.34 6.4 32.17 twenty 8.0 50.27 0.8 56.60

However, the use of thinner metal strips does not solve the problem:

The metal strips must not be too thin: a certain minimum thickness of the metal strip is required for stable feeding of the strips into the rolling stand. The minimum thickness depends on the material and is about 0.2 mm for steel, and more for softer materials. The layered metal strips are introduced into the process not at their joint thickness, but individually, since the layered strips behave like the individual strips that make up the stack of layers. The fact is that a set of layers behaves like separate strips, as long as the strips can move relative to each other.

The use of a thinner strip, however, is not only technically problematic, but also uneconomical, since the thin initial strip must first be rolled and then, with a longer length, profiled. The thinning of the composite wire, which consists of thicker metal strips, by rolling or drawing, is much cheaper in comparison; such operations are already required for compaction.

Thus, by profiling in rolls, a wire with a diameter of 1.6 mm cannot be produced. Large diameter wire can be made by roll forming, approximately 56% thickness reduction (compression) however makes it too stiff to be fed through the cable bundle in the preferred application. It should be taken into account that when the protruding parts of the nickel strip are bent, ribs appear inside the wire, due to which the combined wire bends much worse than a solid wire of the same thickness.

4. Because aluminum is present in the nickel-hooked strip, the center of the wire is not exclusively nickel.

According to US 2010/0047616 A1, FIG. 1, the portions of the nickel strip protruding in the width direction are folded onto the inserted aluminum strip and clamped tightly. Due to the pre-clamping, before the sheath is completed, the aluminum strip experiences shear stress and may break. Therefore, the composition in the cross section changes.

5. Presented in US 2010/0047616 A1, FIG. 1, the cross section cannot be obtained by roll profiling as described

In FIG. 5 of US 2010/0047616 A1 shows an already closed profile which cannot be converted into the profile shown in FIG. 1, since the profile rolls during subsequent deformation can only act from the outside. In order to make the cross section shown in Fig. 1, it is necessary, based on Fig. 5, additionally bend the outer edges of the nickel strip by 90° into the already closed profile. This cannot be achieved by profiling in windrows. On the contrary, under pressure from the outside, the outer edges of the nickel strip pierce the aluminum layer and cut off the aluminum.

The raw wire profile produced by roll profiling according to FIG. 1 cannot be obtained from FIG. 4, since the outer strip cannot be deformed by 90°, let alone by 180° as required: there is no support from the inside for such a deformation.

Therefore, the problem posed cannot be solved by the method described in US 2010/0047616 A1; however, the basic idea of making raw wire from strips is an attempt improved by the present invention.

Formulation of the problem

If strips whose width is many times their thickness, in particular at least 5 times, more preferably 10 times their thickness, are deformed by perpendicular pressure, this deformation results almost exclusively in a change in length and not in a change in width. In order to make a wire of a particular composition from two or more metal strips, in particular strips with different yield strength, it is necessary to prevent the metal strip having a lower yield strength from being relatively more elongated.

Thus, one of the objectives of the invention is to reduce the elongation of one of the metal strips relative to the other, preferably to prevent it. It is also preferable to provide a method for manufacturing a raw wire, which makes it possible to obtain a raw wire, the central part of which, at least predominantly, is formed from a material that also forms the shell of the raw wire.

In addition, in one of the preferred applications, the thermal spray wire made from nickel and aluminum strips should preferably also meet the following requirements:

- Metals should not be present in powder form, but in the form of bands.

For the manufacture of NiAl wires for thermal spraying, nickel sheaths are often filled with aluminum powder. Because the surface of the powder is larger than the surface of the strip, more oxide is deposited with the powder than with the strip. Therefore, the use of powder is unprofitable.

In addition, aluminum powder is pyrophoric if its particle size is less than 500 microns.

The powder has another disadvantage, which is its fluidity, which makes it difficult to control the exact composition of the cross section formed by the shell and the powder filling it.

- The stripes should not be present in the form of an alloy, but in the form of alloying components.

An alloy of 80 wt.% nickel and 20 wt.% aluminum melts already at 1362°C. The melting point of nickel is 1455°C. At first glance, it seems advantageous to use the alloy as a thermal spray wire. In particular, the advantage of spraying with a combination wire is that the exothermic reaction of Al with Ni occurs only during melting directly during thermal spraying. At the same time, an increase in temperature ensures good adhesion of the sprayed coating to the substrate. Preliminary preparation of the substrate to improve adhesion under certain conditions can be omitted.

- The difference in strength between nickel and aluminum during wire production must not cause a difference in length and thus a change in the ratio of the components.

- The composition should preferably be amenable to recrystallization annealing.

The wire should preferably be dimensionally stable, i.e. it should not be so soft as to wrinkle when fed. On the other hand, it should also not be so rigid that it interferes with the feed. Therefore, it is preferable to be able to adjust the stiffness of the composite wire during deformation and annealing. During annealing, no exothermic reaction should take place.

- Cross-sectional structure of nickel and aluminum layers.

Significant surface roughness, such as aluminum due to the presence of an oxide layer, causes too rapid wear of the cable package. Therefore, the outer layer of the composite wire should preferably consist of nickel. The center of the wire should also be made of nickel to prevent premature clamping of the aluminum strip.

- The cross section of the profile should preferably be completely filled.

In this preferred embodiment, no hollow space should be left, as when heated, the air will oxidize the joined metals.

Terms

The term "raw wire" means a composite wire formed from at least two metal strips, produced by roll forming.

The term "nickel" in the preferred interpretation means a grade of nickel with a purity of at least 99.6 wt.% and a maximum carbon content of 0.02 wt.%

The term "aluminum" should also include aluminum alloys, in particular with additions of rare earth elements, providing thermal protection.

By W-profile is meant the shape of the cross-section of the metal strip, perpendicular to the direction of length, resembling the letter W. In particular, it is formed, in a top view, by bending, in particular, convex deformation, of the metal strip between two arms of the metal strip rising laterally.

DESCRIPTION OF THE INVENTION

According to the invention, the problem is solved by the fact that in the above-described manufacturing method in the first group of rolling stands, in several passes, first only the first metal strip is given a rough shape, after which, on the second group of rolling stands, the first and at least one more metal strip co-molded into the final shape.

The invention proceeds from the fact that the shaping of at least two metal strips, and therefore the first and at least one more metal strip, is carried out in a plurality of passes, which are carried out by means of a plurality of rolling stands, in particular one rolling cages for passage.

The total number of all rolling stands involved in the deformation according to the invention according to the invention is divided into two groups. The first group is intended for deformation of only one first metal strip, which subsequently forms the shell of the raw wire, the second group of rolling stands is intended for the joint deformation of all metal strips that form the raw wire. Between the first and second groups, at least one other metal strip is added to the first metal strip. Technologically, at least one other metal strip can be fed from the coil/unwinder over the first group of rolling stands without processing, then directed downwards and, together with the first metal strip, fed to the second group of rolling stands. The decoiler for the other metal strip can also be mounted above the first set of rolling stands so that the other metal strip can be fed directly into the first stand of the second set of rolling stands. In both cases, this strip can be properly fed through the S-stand.

Due to the separation, it becomes possible on the first group of rolling stands to exert such pressure only on the first metal strip, which, if applied to at least one other metal strip, would lead to an elongation of this at least one other metal strip relative to the first one. By partially separating the forming steps, such an elongation is prevented, which is found in particular when metal strips with different tensile strengths are joined in the raw wire.

Partial separation of the deformation process into separate deformation of the first metal strip and subsequent joint deformation is also beneficial when the metals have the same or close yield strength, since even at the same or close yield strength, the strips processed together move relative to each other. In addition, the shell profile is easier to form separately.

The difference in strip elongation occurs when strips of different strengths are processed together. Differences in the elongation of different metal strips, e.g. nickel and aluminum due to different strengths of the materials according to the invention, can be avoided due to the fact that the joint processing is delayed, preferably only carried out in the second half of the processing steps, in particular in all rolling passes. cages of the second group. To this end, at least one other metal strip, in particular an aluminum strip, in contrast to the solution according to US 2010/0047616 A1, is placed on the first metal strip, in particular the nickel strip, not immediately in the first pass, but only through several passes, in particular through as many passes as possible, the first metal strip, preferably a nickel strip, already having a rough cross-sectional shape, preferably a trough-shaped one, is laid. Thus, preferably, the strong first metal strip is first deformed separately from the second metal strip.

The fact that metals with a lower yield strength at the same pressure deform more strongly than metals with a higher yield strength, or already deform at a lower pressure, is due to physical reasons and cannot be ruled out during joint processing. Therefore, the invention provides for the separation of the stages of processing of different materials of metal strips.

Before the different materials are processed together, the metal strip forming the sheath, in particular the stronger metal strip, preferably the nickel metal strip according to the invention, is deformed separately, namely by means of a first set of rolling stands.

In a preferred embodiment, the invention provides that by means of rolling stands of the first group, designed to give the first metal strip a rough shape, the first metal strip, when viewed in a cross section perpendicular to the direction of the length of the metal strip, is given a trough-like shape, in particular with side walls and the bottom connecting them. At the same time, the trough-shaped form is observed in the cross section perpendicular to the direction of the length of the metal strip. The trough shape can also essentially be represented, in particular, as a modified U-shape.

Then, in this embodiment of the invention, it is provided that at least one other metal strip is inserted inside the trough-shaped mold, ensuring contact with the bottom of the trough-shaped mold, after which the first and at least one other metal strip are jointly formed using the second group rolling stands, squeezing each other.

In this case, clamping can be carried out, for example, so that the introduced at least one other metal strip is pressed against the bottom of the trough shape by means of at least one roller of the corresponding rolling stand. Clamping can also be carried out, in particular subsequently, by means that at least one other metal strip is clamped and held by the first metal strip.

The trough shape is an open draft shape of the later closed raw wire sheath, so it is clear that in such an embodiment the sheath formation is already largely completed before at least one other metal strip is fed into the deformation process.

In this case, the invention preferably provides that the trough-shaped shape is obtained by deforming, preferably, at first a flat first metal strip by bending two opposite (in the direction of the width of the metal strip) strip edges of the first metal strip by 180 degrees, each, onto the surface of the metal strip, in in particular, by flanging. In this case, the edges, in fact, turn out to be bent on themselves. Preferably, there is no gap/void between the folded and self-contacting edge regions. In this case, the bent edges are preferably twice as thick as the original thickness of the metal strip.

Further, the creation of a trough shape is carried out by forming two raised arms by bending the opposite (in the width direction) side regions of the first metal strip, in particular, by 90 degrees plus/minus 15 degrees, each, relative to the original plane of the metal strip, while two shoulders form the side outer walls are trough-shaped, and the area connecting the shoulders forms the bottom of the trough-shaped.

These two deformation steps may be performed in any order, however, it is preferred that the "fold-back-on-itself" is performed first.

The width of the two-sided flanging of the edges by 180° on themselves already determines the further required volume of the core of the raw wire formed from the sheath material.

Subsequent raising of the strip edges up to the raised side arms, in particular preferably by another 90°, forms, in a cross section perpendicular to the length direction, said trough-shaped shape into which the second metal strip can be placed. In particular, given the subsequent formation of the trough-shaped walls/shoulders, it already approximately corresponds to the final geometry of the raw wire.

Before the trough-shaped arms are folded inwards, a second metal strip, preferably an aluminum strip, is inserted into the trough-shaped, more preferably W-shaped, first metal strip.

With regard to the embodiment of the invention shown in the figures, as shown in FIG. 1, at least one other metal strip, preferably an aluminum strip, is connected to the already trough-shaped first metal strip, preferably a profiled nickel strip, only at the working station 11. Since the first metal strip, in particular the nickel profile, is substantially narrower rolled and preferably already W-shaped, the laying of the strip does not require much force to be applied to at least one other metal strip/aluminum strip, which would therefore thin out and elongate disproportionately.

Technically, the later feeding of at least one other/second metal strip, in particular an aluminum strip, is carried out by placing the running end of the aluminum strip above the profiling mill (see FIG. 1). This strip coming from the uncoiler is introduced into the profiling process preferably in an S-shaped path above the rolls from above. This unwinder can also be installed before the unwinder from which the first metal strip, in particular the nickel strip, is fed.

The invention can also provide for limiting the roll pressure required to feed the strip when introducing at least one other/second metal strip, preferably an aluminum strip.

Measures may be provided to prevent the deflection of at least one other/second metal strip, in particular the aluminum strip transversely to the strip movement.

For this purpose, the invention can provide for the centering of at least one other, in particular the second metal/aluminum strip, when it is fed into the trough-shaped mold by means of a work roll located above it, while at least one other metal strip is introduced, essentially only laterally, i.e. centered on the first metal strip/nickel strip only with such pressure that does not cause elongation of at least one other metal strip.

However, the first metal/nickel strip can be given a convex shape if the first metal strip has a preferred W-shape, described later, but not required.

In this way, the elongation of at least one other metal strip, in particular the aluminum strip during its feeding and centering, is completely eliminated.

The strips are characterized by a high ratio of width to thickness. If pressure is applied to the strips, a perpendicular force causes elongation. The width changes only slightly. If two strips with different yield strengths are processed together, the softer strip will elongate more than the stiffer strip. Because of this, in contrast to FIG. 4 of US 2010/0047616 A1, the invention provides that at least one other metal strip, preferably an aluminum strip, is clamped only after the first metal strip has been shaped, in particular, therefore, not beforehand at the beginning of the profiling process; this prevents otherwise too high forces in the length direction, which could cause shearing of at least one other metal strip, preferably a softer aluminum strip.

In order to achieve the desired final shape, the invention provides that a first metal strip, preferably a nickel strip, is pressed against a second metal strip, preferably an aluminum strip. To this end, the shoulders of the trough-shaped form formed from the first metal strip are folded inwards and then the outer regions of at least one other metal strip are brought into contact with the edges bent towards themselves. At least one other metal strip, in particular an aluminum strip, is clamped by the folded edges of a first metal strip, in particular a nickel strip, and is thus fixed in a centered orientation. Preferably, it can also be ensured by the invention that, when clamping, the first metal strip also takes over the feeding of at least one other, in particular the second metal strip, and the pressure exerted by the work roll at least only substantially or at least least predominantly affects the first metal strip.

Thanks to the invention, extrusion of the material of at least one other metal strip, preferably an aluminum strip, from the raw wire can be prevented.

The techniques described so far aimed at avoiding disproportionate elongation of at least one other metal strip, in particular an aluminum strip compared to a first metal strip, in particular a nickel strip, are no longer effective when a closed wire profile is obtained, in in particular when, for the purpose of preferably subsequent sizing of the raw wire, the raw wire produced according to the invention is subjected to the same pressure on all sides. At a certain predetermined pressure acting on the resulting complex, which exceeds the yield strength of the softer metal, the metals of both bands, in particular, Ni and Al, are deformed differently. The difference in deformation at the available strip sizes appears almost exclusively as a different elongation. Such a difference in elongation cannot be ruled out due to the fact that the raw wire already has a closed profile. Despite the clamping of at least one other metal strip, in particular the aluminum strip, by the first metal strip, when the combined wire is deformed, it is pressed out of the end of the wire. In the case of aluminum and nickel, in bars with a length of approximately 6 m, the softer aluminum protrudes from the end of the wire by 7.5-11.5 cm when the combined wire is deformed.

The invention may provide for the formation at the bottom of the trough-shaped form of a projecting convexity directed into its inner space, in particular, to create a trough-shaped W-shaped form. At least one other metal strip, which is centered in contact with the bottom of the trough shape, can be bent over the bulge in this embodiment. Thus, the centering of at least one other metal strip in the trough shape of the first metal strip is guaranteed.

Giving such a convex shape to both strips, in particular the nickel and aluminum strips, at first glance seems controversial, since in order to obtain a wire cross-section, the combined strip must be concave. Therefore, in US 2010/0047616 A1, the profile is naturally made concave (see [0016] and FIG. 3).

The W-shape is preferably obtained by temporarily convexly deforming/convexing the bottom of the trough-shaped sheathed metal strip in the area between the side arms.

The use of the W-shape for the production of raw wire seems to be unfortunate, primarily for two reasons:

To create the W-shape, at least two rolling stands are additionally required, in particular crimping stands. The cost of additional stands and working tools increases the cost of the profiling process.

Due to the variable bending, the cold hardening of the metal strip is enhanced. Therefore, the potential for joint shape change is exhausted earlier and, under certain circumstances, preliminary or even additional annealing is required.

For the manufacture of a composite wire, the creation of a W-shape by means of the necessary shear forces is essentially optional; on the basis of the reasons given above, this could be waived. In principle, the combined wire can also be produced with a flat bottom, trough-shaped form of a metal strip forming a sheath.

Creating a W-shape when making a combination wire is preferred, but not required. Also preferred is the convex shape of the second metal strip, in particular the aluminum strip above the convex first metal strip (forming the shell). To do this, the second metal strip can be laid on a W-shaped bulge in the trough-shaped first metal strip, and the sides of the second metal strip are pressed down, as a result of which the second strip also acquires a convex shape. The convex shape is preferably created by means of a roll acting from above, see FIG. 3, passage 11. Not only does this lead to the centering of the second metal strip, in particular the aluminum strip, it also prevents lateral displacement of the strip in the subsequent stages of deformation. Since only small bending forces are required, a relatively large elongation of at least one other/second metal strip, in particular an aluminum strip, is avoided.

In principle, the methods according to the invention can also be carried out without W-shaped deformation.

The invention preferably provides that the trough-shaped arms of the first metal strip are folded inwards onto the surface of at least one other metal strip, in particular at least one other metal strip in its lateral regions is in contact with the folded edges of the first metal strip and squeezed by them.

After that, in order to create an at least essentially closed shell, it is provided that in several passes the outer surfaces of the trough-shaped arms are brought into contact with each other, in particular by bending relative to the interior of the trough-shaped / wrapping around the bottom of the trough-shaped form and clamped between it and the shoulders trough-shaped, at least one other metal strip.

In a particularly preferred embodiment, the invention provides for the prevention of displacement/extrusion of the material of the second metal strip, in particular the aluminum strip, by a further advantageous improvement, preferably without changing the cross-sectional composition. The raw wire thus produced can be particularly preferably used in the critical application of thermal spraying or welding.

To this end, the invention may provide that the metal strips are each unwound from a coil, and the raw wire is wound into a coil. When using the material in coils, a large usable length can be obtained. Particularly advantageous when processing material from coil to coil is that the displacement of the material in the longitudinal direction is excluded.

In the description of the starting material in patent application US 2010/0047616 A1, [0015], it is indicated that a core material should be used, and the materials to be joined should not be wound from the coil: “flat strips ..., both of the same length, bring together with obtaining a laminate.

According to a preferred improvement, the invention provides for the prevention of material displacement of at least one other, in particular the second metal strip, in particular the aluminum strip as a whole, by limiting the longitudinal movement of this material. Instead of short lengths of the strip according to the invention, at least in relation to at least one other metal strip, preferably both metal strips, coils of the material to be processed to obtain raw wire are used, therefore, the frictional resistance of at least one other of the metal strip, in particular the aluminum strip on the layers of the first metal strip, in particular the nickel layers in the subsequent wire, is so large that the material of at least one other metal strip cannot elongate more than the material of the first metal strip.

Therefore, it is advisable to produce a combined wire not in the form of rods, but in the form of coils, preferably from two coils of the original strips or the corresponding number of coils of all the original strips to obtain a coil of manufactured raw wire. In this case, the invention can also provide that the metal strips of coils used one after the other are connected, in particular welded, whereby a continuous, endless production of raw wire is possible.

The invention can also provide that the width of at least one other metal strip is chosen so that between the outer edges of at least one other metal strip and the lower end of the trough-shaped arm, a free space closed/closing by the material flow is formed. In this way, according to the invention, a known void/free space is provided, allowing material to flow into it.

If the profile in cross section is strongly deformed, while the longitudinal movement of the material of at least one other metal strip is limited, it still stretches more than the material of the first metal strip. Therefore, in a preferred development, the invention provides that the material of at least one other/second metal strip must be provided with a free space into which, despite being clamped, it can expand perpendicular to the direction of operations or the longitudinal direction. Perpendicular and preferably horizontal expansion is not critical as it does not change the ratio of materials in the cross section.

In US 2010/0047616 A1, [0018], it is stated that existing voids are filled due to the flow of aluminum. However, in order for cross-flow to be possible at all, the invention preferably provides for the creation of voids or free space. The creation of voids at first seems doubtful, since in subsequent stages of processing they need to be filled again.

However, according to the invention, voids have been found to be useful in allowing material to flow perpendicular to the direction of operations. In this way, by means of a controlled tolerable cross flow, it can be possible to transfer the expansion of the material of at least one other metal strip from a longitudinal flow into a transverse flow, whereby profile breakage is preferably prevented.

Preferably, a free space is provided, the total surface of which in the annealed wire is between 5% and 20%, preferably between 9% and 14% of the cross section of at least one other, in particular the second metal strip.

For example, for Ni/Al, other combinations of a lower limit calculated from the surface of Ni and Al and the surface of the annealed wire and an upper limit determined by measurements are also possible.

To provide voids, the width of at least one other metal strip is chosen so that it does not reach the corners/lower ends of the arms of the first metal strip bent inward, i.e., does not completely fill the profile. In addition, the folding of the edges of the first metal strip onto itself causes the doubling of the metal layer of the first metal strip thus created to act as a retainer that provides free space for the metal of the second metal strip, in particular the space in the upper part of the thickness of the first metal strip. .

The metal of at least one other/second metal strip can now expand despite being clamped by the first metal strip, since the elongation is blocked. Due to this, the cross section is completely filled. By allowing the expansion of the second metal strip, the free space in the cross section is preferably completely filled.

Thanks to the invention, despite the difference in the yield strength of two different metal strips, the ratio of the metals in the cross section does not change.

The invention may provide for the creation of an intermetallic connection between the metal strips during annealing.

Intermetallic bonding, as a rule, is observed during annealing of clad strips. During the first recrystallization annealing in the combined wire, due to the absence of a metal connection of the layers, a layer of mixed crystals is not formed. And during the second recrystallization annealing, despite the contraction and compaction of the complex during stretching, no metal compound is formed. In particular, this can be explained by the low annealing temperature of about 400°C and the short holding time of about 1 hour. At a higher temperature and longer holding time in the second anneal, an intermetallic phase of two metals can form, for example, an intermetallic phase of about 4 μm thick of nickel and aluminum, which dissolves the layers at the interface when the alloy is formed. In this case, the layers "stick together". This makes it even more difficult to extrude the metal of the at least one other/second metal strip during subsequent processing. True, the formation of a layer of mixed crystals may be undesirable. The user can decide, based on the range of annealing modes, whether a layer of mixed crystals will appear, or whether its formation should be excluded.

The invention can also provide that a material with a higher yield strength is packed into a material with a lower yield strength, so that the latter forms a sheath.

In the foregoing description, it has preferably been assumed that the lower yield strength material does not form the sheath, but the interior of the composite wire. The reverse case, in which a material with a higher yield strength is enclosed in a material with a lower yield strength, is non-critical, since then the so-called sandwich effect occurs. As a result, a hard material embedded in a soft material can be rolled with less energy, and without intermediate annealing, can be more thinned by rolling than a core material of the same thickness. Thus, the method according to the invention can also be carried out with this configuration of materials.

In a preferred embodiment, the invention provides for the complete filling of the cross section of the produced raw wire.

The strips can be made into a tubular rather than wire cross-section. However, in US 201010047616 A1, FIG. 1 shows a completely filled cross section, although such a cross section, as shown above, cannot be produced by roll forming. In order to completely fill the cross section, the invention provides for bending the edges of the strip of a wider material, which acts as a sheath, by 180 ° C, therefore, bending over themselves so that, at the end of profiling, a thickening is formed in the center of the wire, preferably, if possible, a rounded thickening of the material that forms the shell. The size of the overlap is variable; along the length of the 180° flange, the subsequent volume of the core of the sheath material, in particular nickel, can be finely adjusted.

On this basis, the invention also provides that the strips used for the connection have different widths.

Forming a wire cross-section to meet the requirements of the preferred thermal spray application

It is expedient that both the center and the sheath of the combined wire consist of nickel:

When the nickel strip is first deformed separately and not together with the aluminum strip, after the strips have been converted to wire, the common center is filled with sheath material.

To prevent the hard alumina from damaging the cable package, it is advisable that the sheath also consists of nickel rather than aluminium.

The possibility of changing the shape of the combined wire is exhausted after approximately 80% reduction in the surface. This for a slightly oval raw wire 14 mm wide and 13 mm high corresponds to a reduction in cross section of 57.5%.

If the roll-formed and then densified and drawn wire in an improved embodiment of the invention is to be made even thinner, intermediate annealing is preferably provided.

But in the preferred described embodiment of the use of nickel and aluminum as a strip material, the recrystallization temperature of standard quality nickel exceeds the melting point of aluminum. Therefore, the complex cannot be annealed. To be able to anneal the nickel-aluminum complex, it is necessary either to alloy aluminum with other elements that increase the melting point of aluminum. This is, for example, silicon. Such alloying is technically possible, however, the resulting wire is no longer suitable for the intended application due to the added alloying elements. Alternatively, the recrystallization temperature of the nickel used must be lowered so that it is preferably well below the melting point of aluminium.

This condition is only met in the case of pure nickel with a purity of at least 99.6% and a maximum C content of 0.02 wt.% Pure nickel with even higher purity (>=99.8%) recrystallizes, in depending on the previous deformation, already at 300°C - 350°C. When using pure nickel with a purity of at least 99.6%, recrystallization annealing of the composite wire is also possible according to the invention.

In the raw wire obtained by rounding the first metal strip, a groove can remain (see Fig. 4), in particular, at the foot of the original trough-shaped shoulders. During further processing, the oil used during drawing can penetrate into the groove and coke during annealing. This would undesirably change the composition of the composite wire.

Therefore, the invention provides for sealing such a groove by welding.

Therefore, experimental welding was carried out, the purpose of which was to close the walls of the groove. The groove welding was carried out using a fiber laser with an energy release in the core of 1000 W, an energy release in the ring of 2000 W, a focus position of 7.0 mm, and a feed rate of 2.0 m/min. The weld seam withstood the subsequent deformation of the raw wire.

The invention can also provide for the reduction of the groove by deformation aimed at reducing the cross section.

If the wire is subjected to deformation without welding the groove, when the diameter is reduced from 13/14 mm to 10 mm, the groove is extended so that it is no longer visible to the naked eye. Therefore, brewing the groove can be abandoned. Welding can be advantageous in long term storage at ambient temperature and high humidity where moisture must be prevented from entering the composite wire.

In a preferred embodiment, the invention may provide for the conversion of the ratio of atomic weights of the metals present required for the raw wire into the relative area of the metals in the cross section of the raw wire and then joining the metal strips according to the obtained relative area by the method according to the invention. For example, the preferred use of Ni/Al is described in more detail below.

The standard for thermal spraying is a composition of 80 wt.% Ni and 20 wt.% Al. The invention preferably provides for the conversion of this weight ratio into the surface area of the strips to be joined.

The following formula gives the volume fraction. Since the volume distribution along the length is constant, this ratio of volume fractions is also suitable for calculating the surface. In this case, the following is true:

Formula:

G1 =% mass fraction of component 1

G2 = % mass fraction of component 2

R1=density of component 1

R2=density of component 2

V1 = % vol. component 1

V1=G1*R2/(G1*R2+G2*R1)

Data:

Material Density Mass fraction atomic fraction g/ ^cm3 wt% % at. Aluminum 2.7 twenty 35.2260 Nickel 8.91 80 4.7740

Calculation:

VAL=20*8.91/(20*8.91+80*2.7) = 0.4521

Al=45.21%

Ni=54.79%

Such a ratio of surfaces can be obtained by a variety of combinations of width and thickness.

Calculation of stripe size based on relative area

Based on the given diameter of the raw wire and the ratio of surfaces described above, the thickness of the strips can be calculated:

Given:

DVDraht=12.72 [mm] finished raw wire diameter

pAl=2.70 [g/cm³] aluminum density

pNi=8.91 [g/cm³] nickel density

AAl% = 45.21 [%] relative area of aluminum in the combined wire

ANi% = 54.79 [%] area ratio of nickel in composite wire

sAL=2.40 [mm] aluminum strip thickness (optional)

sNI=1.20 [mm] nickel strip thickness (optional)

Need to find:

bAl = [mm]

bNi = [mm]

Calculation:

AVDraht = (DVDraht)²*π/4

= 12²*π/4

= 127.08 [mm²]

bAl=AVDraht*AAl%/100/sAl

= 127.08*45.21/100/2.40

= 23.94 [mm]

= 24.00 [mm] selectable

bNi=AVDraht*ANi%/100/sNi

= 127.08*54.79/100/1.20

= 58.02 [mm]

= 58.00 [mm] optional

Scope of the invention

Although in a preferred application the invention has been described in detail with reference to the manufacture of NiAl wire, since in this case the problem of manufacture is particularly difficult, the invention is not limited to this combination of metals. It is also not limited to having a softer material inside and a harder material forming the shell and core. The location can also be reversed. It is decisive that the sheath material be deformed as much as possible in order to obtain a blank according to the invention before the introduction of a second or, in the known case, another metal strip into the roll profiling process. Since only the amount of pressure required for centering with horizontal rolls is exerted on the metal strip introduced later, not only one metal strip, but also more can be placed in the first metal strip having a trough-shaped form, in particular even strips with different yield strengths.

It is preferable to use the invention, in particular

- when some alloys cannot or are difficult to be prepared pyrometallurgically, for example, because the alloy components tend to delaminate. Then the introduction of certain alloy components is limited;

- when the alloy is difficult to machine, for example, because it becomes brittle or quickly hardens, and therefore intermediate annealing is often required. In comparison, processing alloy components as a laminate can be much easier.

In these cases, the alloy can be made by diffusion heat treatment to a size close to the final size. Diffusion can also be used to create gradients.

Other combinations of metals can be processed according to the process principles described, for example:

- austenitic-ferritic and so-called duplex steels

Austenitic-ferritic steels (eg material no. 1.4462) have a two-phase structure. An austenitic-ferritic structure in which both constituent parts of the structure are present in approximately equal proportions is also called duplex steel (eg materials nos. 1.4362, 1.4460, 1.4501). They combine the high strength of ferritic chromium steel with the corrosion resistance of austenitic CrNi steel. It is more difficult to produce grades in which structural elements are not present in equal proportions, in particular, those containing <25 wt.% ferrite and <25 wt.% austenite. A hot-rolled billet with an austenitic-ferritic structure of this composition is prone to cracking at the corners. Cracks also start from notches on the surface.

The yield strength of ferritic steel is generally greater than that of austenitic steel. The wire can be made both with an austenitic sheath and a ferritic core, and with a sheath of ferritic steel and an austenitic steel core.

The combination wire can be made in the form of a welding wire.

- FeCrAI alloys

The aluminum content in pyrometallurgical alloys is limited to at most 5-5.6%, since alloys with a high aluminum content are more difficult to process, the higher their aluminum content. Using the new method, wires with a high aluminum content, for example 9%, can also be produced. This is advantageous, since by increasing the aluminum-rich phase, the service life of the layers obtained by welding increases. If the composite wire is made from stainless steel and aluminum strips, ferritic stainless steel grades such as UNS S43000, UNS S43400 and UNS S44600 can be used as the steel, preferably with a limited sulfur content. A particular advantage of the method with the introduction of alloying elements by means of individual strips is that the difficult-to-work FeCrAl alloy is formed only after the end of the production process during diffusion annealing, or even only when used as a welding wire.

- FeNiCrAl and FeNiAl, e.g. Cr26 Ni14 Al10 rest. Fe or, for example, Ni30 Al16 rest. Fe

These material combinations are used for coating boilers in coal-fired power plants.

- The wires produced according to the invention can be used not only as welding wire or wire for thermal spraying, such as flame spraying, high-speed flame spraying, electric arc coating and laser welding, but also for processing molten metal by introducing a wire. The wire can also be used to smelt difficult-to-manufacture alloys such as nickel aluminides using the Oak Ridge National Laboratory's Exo-Melt (exothermic melting) raw materials arrangement. The manufacture of the alloy in this method is carried out by reaction synthesis. The combined NiAl wire is especially conveniently produced by melting a cast body.

Brief description of the figures

In FIG. 1 shows the device for the production of raw wire profiling mill.

From the coil 1, the first metal strip 2, which then forms the shell, is fed into the first group G1 of rolling stands, where only this first metal strip 2 is deformed, giving it a draft form, in particular, a trough-shaped form. From coil 3, the second metal strip 4 is led past the first group G1, in this case above it, and by means of an S-shaped stand 5 is introduced into the production line. By means of the second group G2 of the rolling stands, the two metal strips 2 and 4 are then deformed together to obtain the final shape according to the invention.

In this embodiment, an optional group G3 of additional work stations is also shown, in which the manufactured raw wire 7 is calibrated and/or straightened, for example.

At the end of the technological trajectory, the manufactured raw wire 7 is wound into a coil 6.

The order of the deformation stages is shown in Fig. 2.

In the first pass 1, i.e. the passage through the first rolling stand, the first metal strip 2 is centered. doubles.

In the passages 8-10, by raising the edge regions, the strips form trough-shaped side arms 2b. In the embodiment shown, it is also envisaged that the bottom 2c is provided inside the trough shape with a protruding bulge 2d directed upwards, whereby a W-shape is formed.

Starting from the passage 11, the second metal strip 4 is introduced into the technological path, centered and bent over the bulge 2d.

In the passages 12-14, the trough-shaped arms 2b are folded inward of the trough-shaped form and onto the side regions of the second metal strip 4, thereby clamping it to the first metal strip.

In the passages 15-21, the trough-shaped arms 2b are pressed against each other by their former outer sides 2e relative to the former trough-shaped in the passages 8-10 and, thereby, round off the compressed complex of two metal strips, while the bulge 2d is deformed in the opposite direction, up to the passage 21, when the outer sides come into contact with each other to form the finished raw wire 7 according to the invention.

The enlarged view of the shape achieved in the passages 16 and 18 also shows the free space 2f closed by the flow of material between the edges of the second metal strip 4 and the formerly lower regions of the trough-shaped arms 2b.

In FIG. 3 shows the roller sections used for profiling. In FIG. 4 shows a metallographic cross-sectional section of a combined wire with a diameter of 1.6 mm.

An exemplary embodiment of the invention

The fabrication of NiAl wire from strips, in contrast to pyrometallurgical fabrication of the alloy, has the advantage that the exothermic effect of aluminum melting promotes better adhesion of the sprayed alloy. Compared to using aluminum in powder form, the advantage is that less oxide is added.

- Quality of materials

A nickel strip with a purity of 99.98% by weight and a C content of 0.002% by weight was used. The grade EN AW 1050A was used as the aluminum strip.

- Band sizes

Many size options are possible; it must be taken into account that a change in thickness also leads to a change in width. Based on a fixed width of 58 mm or 24 mm of the original Ni- and Al-strips determined in this example by unwinding, and a given Al/Ni surface ratio of 45.21%/54.79% for the preferred application as a thermal spray wire , the thickness of the nickel strip is 1.2 mm, the thickness of the aluminum strip is 2.40 mm.

Trial:

Metal Width Thickness Surface mm mm abs. in mm ² in % Ni 58.0 1.2 69.6 54.72 Al 24.0 2.4 57.6 45.28 100.00

- Roll profiling

In the manufacture of raw wire by the method of roller molding at separate stages of profiling, in order to exclude disproportionate elongation of the metal with a lower yield strength, the following was done. See the individual steps in FIG. 2:

pass Actions 2-7 Determining the manufacture of a predetermined volume of the core of the later obtained composite wire before co-processing the two materials by roll forming. To do this, on these passes, the edges of the strip are folded back on themselves by 180 degrees and, thus, the thickness is doubled. First, the nickel strip is profiled separately, as close as possible to the given geometry. 8-12 Pretty much the finalization of the geometry of the stiffer material (RH Ni) before the introduction of the softer material (RH Al) in order to maintain this geometry and prevent elongation in the profiling direction. On passes 8-10, the shoulders are raised and thus a trough shape is obtained, in this case with a W-shaped bulge. Starting from passage 11, the aluminum strip is bent around the convex nickel strip with less pressure. To do this, use a temporary W-shape. 13 and 14 Immediate clamping of softer material after centered insertion by overlaying the folded edges of a strip of harder material. Without directly applying pressure to the softer material, this rolling prevents unwanted elongation. 13-16 Formation of a closed connection to create a guide surface between workpieces/materials. Filling lateral voids by blocking longitudinal forces and assisting transverse forces. The deformation of the convexity into a concave strip, starting from the passage 15, is carried out using side rollers. In the cross section, only the holding force is applied. 16-21 Raising the sides of the combined wire, mainly by means of side rollers (see SRS 17-18 in Fig. 3), thereby minimizing the pressure acting on the inner soft strip. Prevention of longitudinal forces, so that there is no elongation of the soft strip. By roll profiling and sizing, raw wire is produced with a diameter of 14 mm in width and 13 mm in height. The cross section is not yet completely filled. After calibration and reduction of the diameter to 12 mm, the compaction is complete.

According to these predetermined parameters, the calculation of the cross section of the rolls using the software "Copra RF2015 (Service Release 3)" was confirmed by data from M Sheet Metal Solutions, GmbH, Am Marschallfeld 17, D-83626 Oberlaindern/Valley. Profiling was carried out using Dreistern P120 with 21 technological positions.

At the exit of the profiling trajectory, the annealed wire as a finished product was wound into coils.

First, when profiling, due to the insufficient stability of the stands used, a combined wire was obtained with a slightly oval outer diameter of 14 mm wide and 13 mm high. By using more stable stands or by an additional calibration pass, the profile can be completely rounded and the diameter reduced.

By verification measurements of the thickness of the nickel strip, it was found that when profiling in rolls, the thickness of the now profiled nickel strip does not decrease; rather there is a slight thickening.

In order to reduce the raw wire to standard thermal spray dimensions, additional passes are required with a raw wire diameter of 13/14 mm. Raw wire can be thinned in additional passes of roll forming, rolling, drawing, drawing and forging.

- Additional profiling in the rolls to reduce the cross section

Since no intermediate annealing is possible after the production of the raw wire, a further reduction in the cross section can be carried out by inline profiling. Then additional, not shown in FIG. 1 and 2 technological positions. On the other hand, a separate process step, as described below, is then not needed.

- Rolling and winding by drawing operation

The ovality of the raw wire is an advantage when the cross section has to be reduced by rolling. Rolling stands are formed from alternately horizontally and vertically installed rolling stands, providing alternate rolling of oval or round cross-section. By rolling the ovals, pressing out is prevented.

A raw wire with a diameter of 13/14 mm produced according to the invention was first reduced to 10 mm using a 6-stand W10-3 rolling mill. After the rolling stands, a Herborn Einzelziehblock EG IV was installed, with which the wire was thinned to 8 mm and simultaneously wound into a coil.

When the diameter is reduced by forging, already at a deformation (without intermediate annealing) of 70% (relative to the surface), microcracks appear on the inner side of the outer shell.

- Recrystallization annealing

Although the materials used become harder when profiling in rolls, however, not so much that the possibility of changing the shape is completely exhausted. Recrystallization annealing of the raw wire immediately after roll profiling is thus not required. On the contrary, as described above in paragraphs. 4 and 5, after profiling, the blank wire is further thinned to only 8 mm. A coil of wire with a diameter of 8 mm removed from Herborn is subjected to recrystallization annealing at 450°C for 1 hour in a protective atmosphere (argon with 10% hydrogen).

Recrystallization annealing does not lead to welding of the layers. On the one hand, this does not start the formation of mixed crystals, on the other hand, the layers do not connect due to the formation of mixed crystals. However, during further processing, the previously encountered problem of different elongation of the materials being joined can be largely ignored, since the frictional resistance in the wire, relative to the cross section, is greater, the thinner and longer the wire.

- Drawing and final annealing

After annealing, the wire size should be reduced to the standard for thermal spraying, 3.2 or 1.6 mm.

Drawing experiments have shown that at a deformation of >85% of the cross section relative to the surface, the limit of the possibility of changing the shape of nickel and aluminum is exceeded. First, cracks appear on the inside of the nickel shell. When the limit of the possibility of changing the shape of the combined wire is exceeded, the edges of the nickel strip, which were previously folded in half, are first torn off; they rupture before the shell. With further deformation, the aluminum layer of the combined wire is torn. It can be installed on wire bends. When the nickel wall and the aluminum insert break, the composition of the cross section changes in an uncontrolled way.

In a drawing bench consisting of 8 technological positions, a wire with a diameter of 8 mm was thinned to 3.53 mm by 18.5% reduction per pass.

The total deformation was 80.5%. With a diameter of 3.53 mm, the wire was annealed at 450° for 1 hour.

And during the second annealing with such parameters, the intermetallic phase is not formed. If the formation of an intermetallic phase is required, the annealing temperature of 450° C. must be maintained for at least 3 hours.

The final dimensions of 3.2 and 1.6 mm were obtained in one or five trips:

After one pass, due to a slight deformation, the wire is relatively soft and is well suited for feeding into a cable bundle.

The total deformation when the diameter is reduced to 1.6 mm (see Fig. 4) is 79.5%. Although this wire is rigid, due to its small diameter it can be fed into a cable package.

Claims (22)

1. Method for manufacturing raw wire (7) from the first metal strip (2) and at least one other metal strip (4) by roll profiling, wherein the first (2) and at least one other metal strip (4) are made from different metals with different yield strengths, while by profiling in rolls with several rolling stands (G1, G2) in several passes from the first metal strip (2) a shell is formed, which in the final form completely encircles at least one other metal strip (4), characterized in that in the first group (G1) of rolling stands, in several passes, first only the first metal strip (2) is roughed, after which, in the second group (G2) of rolling stands, the first (2) and at least another other metal strip (4) is jointly formed into the final shape, while using the rolling stands of the first group (G1), designed to give the first metal strip (2) h the first metal strip (2), when viewed in a cross section perpendicular to the direction of the length of the metal strip (2), is given a trough-like shape, then at least one other metal strip (4) is inserted inside the trough-shaped form, ensuring contact with the bottom of the trough-shaped form , after which the first (2) and at least one other metal strip (4) are jointly deformed by means of the second group (G2) of rolling stands by compression with each other. 2. The method according to claim 1, characterized in that the trough-shaped form is formed with side arms (2b) and a bottom (2c) connecting them. 3. The method according to claim 2, characterized in that the trough shape is obtained by deformation of the first metal strip (2), which includes the following stages, in which: a. bending both opposite edges (2a) of the strip of the first metal strip (2) by 180 degrees each onto the surface of the metal strip (2), in particular by flanging the edges (2a) of the strip, b. two raised arms (2b) are formed by bending the opposite side regions of the first metal strip (2), in particular by 90 degrees plus/minus 15 degrees each, relative to the original plane of the metal strip, while the two arms (2b) form trough-shaped side outer walls , and the region connecting the shoulders forms a bottom (2c) of a trough-like shape. 4. The method according to claim 3, characterized in that on the bottom (2c) of the trough shape a bulge (2d) directed into its interior space is formed, preferably a convex bulge (2d), in particular to create a trough-shaped W-shape. 5. Method according to one of claims 2 to 4, characterized in that at least one other metal strip (4) is brought into contact with the trough-shaped bottom (2c) centered in the trough-shaped form. 6. Method according to claim 4 or 5, characterized in that at least one other metal strip (4) is bent over a convex bulge (2d). 7. A method according to one of claims 2 to 6, characterized in that the trough-shaped arms (2b) formed from the first metal strip (2) are folded inwards onto the surface of at least one other metal strip (4), in particular along at least one other metal strip (4) in its lateral areas is clamped by the bent edges (2a) of the strip of the first metal strip (2). 8. Method according to any one of claims 2 to 7, characterized in that in several passes the outer surfaces (2e) of the arms (2b) of the trough shape are brought into contact with each other, in particular by arching relative to the interior of the trough shape or bending around the bottom trough-shaped (2c) and sandwiched between it and the shoulders (2b) trough-shaped at least one other metal strip (4). 9. Method according to one of claims 1 to 8, characterized in that each metal strip (2, 4) is unwound from the coil (1, 3), and the raw wire (7) is wound into the coil (6). 10. Method according to one of claims 1 to 9, characterized in that the first metal strip (2) is formed from a metal with a higher yield strength than that of the metal of at least one other metal strip (4). 11. The method according to one of claims 2 to 10, characterized in that the width of at least one other metal strip (4) is chosen so that between the outer edges of the strip of at least one other metal strip (4) and the lower end of the shoulder ( 2b) in a trough-shaped form, a free space (2f) that can be closed/closed by the flow of material is formed. 12. Method according to one of claims 1 to 11, characterized in that the raw wire (7), in particular after sizing and/or diameter reduction, is subjected to recrystallization annealing. 13. A method according to one of claims 1 to 12, characterized in that pure nickel with a purity of Ni ≥ 99.6 wt.% and a carbon content is selected as a metal with a high yield strength, in particular for the first metal strip (2). ≤ 0.02 wt.%, as a metal with a lower yield strength, in particular for the only other metal strip (4) selected aluminum or aluminum alloy. 14. Method according to one of claims 1 to 12, characterized in that one of the following material combinations is selected for the first and at least one other metal strip (2, 4): a. austenitic and ferritic stainless steel, or b. ferritic stainless steel and aluminum or aluminum alloy, or With. iron, steel or ferritic stainless steels and nickel and aluminum for the production of FeNiCrAl and FeNiAl combined wire. 15. A method according to one of claims 1 to 14, characterized in that the resulting raw wire (7) is subjected to a reduction in diameter for use as a welding wire or thermal spray wire for coating, in particular temperature-resistant, preferably by flame spraying, high-speed flame spraying, electric arc coating and laser cladding. 16. The method according to one of claims 1 to 15, characterized in that the resulting raw wire (7) is intended for processing molten metal by introducing a wire. 17. The method according to one of claims 1 to 16, characterized in that the resulting raw wire (7) is intended for the smelting of alloys, in particular nickel aluminides.

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