Non-remelting wire semi-finished product production from chip and / or powder material

Abstract

The invention relates to a method for producing wire semi-finished products by a non-remelting forming process of metallic secondary materials, such as chip and / or powder material.

Description

Summary The invention relates to a method for producing wire semi-finished products by means of a non-remelting forming process of metallic secondary materials, such as chip and / or powder material. Background and state of the art Classification and motivation Processes for converting secondary metallic materials, such as shavings and / or powder, into semi-finished wire products are of central importance to industry. Semi-finished wire products are primarily prefabricated wire products that are further processed in various industrial sectors, such as the automotive, electrical, and construction industries, for example, into cables or wire mesh, welds, and three-dimensional components of varying geometries. Secondary metallic materials are generated, for example, during machining in component manufacturing, in processing metallic materials such as milling or drilling, or when metallic components are shredded after production. These secondary materials then typically remain as scrap materials or waste products. Recycling secondary raw materials enables the energy-efficient return of metallic materials to a production cycle. This allows for the efficient use of valuable resources in the form of materials and energy when manufacturing semi-finished wire products from secondary metallic materials or scrap metal, reducing waste products and minimizing the environmental impact of using primary raw materials. In particular, this can lower production costs and energy consumption, and increase the sustainability of manufacturing. The described recycling of secondary and scrap materials, including titanium, copper, and nickel, is particularly relevant because these raw materials are on the EU list of critical and strategic raw materials. This list comprises essential raw materials for technologies that are important for Europe's green and digital ambitions, as well as for defense and space applications, and for which potential supply risks exist. Previous solutions and disadvantages According to the current state of technology, metallic secondary materials, for example in the form of chips, are usually processed using melt metallurgy and returned to the market, for example as wires, cast ingots, sheets, rods or in the form of other semi-finished products. Melting metallurgy refers to processes for the recovery and recycling of secondary metallic products, scrap metal, and / or metal shavings, which are melted down in a melting furnace. This processing method is widespread but has the significant disadvantage of high energy consumption. This is primarily due to the high melting temperatures required to melt the secondary metallic materials. Depending on the type of metal, these temperatures are typically above 1,000 °C. The secondary metallic materials used for processing are typically contaminated by various prior processes, and these impurities are usually removed during smelting metallurgical processing by adding additives or through existing physical separation processes. These processes include melting additives such as aluminum or calcium, which are used to remove gases like oxygen and hydrogen from the molten material. Other additives, such as lime, dolomite, or quartz, promote the formation of slag, which can absorb unwanted impurities from the molten scrap material. Many of these chemical reactions are endothermic, meaning that an external heat input is required to sustain the process. This results in an additional energy demand necessary to produce a usable product. Due to the high energy demands of metallurgical processing, this is predominantly carried out in non-EU countries, where energy and production costs are generally lower. The EU is therefore highly dependent on imports of these materials. For example, the EU's import dependency for titanium is currently 100%. It is estimated that a significant proportion of titanium comes from China. This underscores the urgent need to establish an internationally competitive circular economy for these materials within the EU as well. The increasing demand for metallic materials in key industries such as aerospace, automotive, and medical technology will further drive the need for efficient, sustainable, and safe processes. Object of the invention The object of the invention is therefore to provide a process by which metallic scrap materials are processed without remelting, in a resource- and energy-efficient manner, and further processed into semi-finished wire products. The process should be particularly suitable for processing metal chips, shavings, and / or powder material into wire and / or semi-finished wire products, achieving in particular a high bulk density of the scrap material and a high packing density of the wire. This problem is solved by a non-remelting forming process for the secondary or scrap metal. Using the present invention, metallic chips, which arise, for example, during the machining of components or as shredded components at the end of their product life cycle, can be further processed into semi-finished products such as wires. In particular, the produced wire semi-finished products are used in the application fields of joining welding or additive manufacturing using arc or laser cladding. Description of the invention The problem is solved by the features of the independent claim. Advantageous embodiments of the invention are described in the dependent claims. In a first aspect, the invention relates to a method for producing a wire semi-finished product by remelting-free processing of contaminated metallic chips, the method comprising the following steps: a) comminution and cleaning of the chips, thereby obtaining cleaned chips, b) filling a sheath with the cleaned chips, thereby obtaining a wire sheath with a chip filling characterized by a chip space number (CSN) and a bulk density, wherein the filled wire sheath has a diameter D1, c) increasing the bulk density by (I) applying external vibrations without diameter reduction, or (II) rotary swaging process-inherent vibrations with partial diameter reduction to a diameter D2, d) reducing the diameter D1 or D2 to a predetermined final diameter D3, wherein the bulk density of the chip filling is increased to a high packing density and the CSN is reduced.and wherein the diameter reduction is achieved by rotary swaging, wire drawing or by a combination of these forming processes. The process comprising steps a) - d) represents a remelting-free forming process for the production of contaminated metallic chips to manufacture a wire semi-finished product. In the process according to the invention, the need for a prior melt metallurgical preparation of the scrap material before the manufacturing process of the semi-finished product is eliminated. The process according to the invention enables the direct production of wire semi-finished products from metallic chips without melt metallurgical preparation. The wire semi-finished products preferably have a high packing density, a low chip space ratio (CSRR), a predetermined diameter D3, a predetermined wall thickness, and / or a continuous homogeneous surface. A packing density higher than 90% of the density of the respective material is preferred, more preferably higher than 95%, and most preferably 100% of the density of the respective material. The wall thickness of the produced wire semi-finished products is preferably in the range of 0.3 mm to 0.5 mm, more preferably in the range of 0.2 mm to 0.3 mm, and most preferably in the range of 0.1 mm to 0.2 mm. The mechanical and / or metallurgical properties of the wire semi-finished products produced by the process according to the invention meet the quality requirements placed on end products from conventional melt metallurgical processing processes. These quality requirements relate in particular to strength, hardness, ductility, corrosion resistance and / or heat treatment suitability, chemical composition, diameter, and diameter tolerance along the wire. The process reduces energy consumption compared to melt metallurgical processes and enables the direct recycling of metallic chips in line with a circular economy. The process according to the invention exhibits a 30%, preferably 50%, and most preferably 70% lower energy requirement compared to previous melt metallurgical processes. In particular, the manufactured wire semi-finished products and / or wires are surprisingly well suited and ideally suited for the application fields of joining welding and / or additive manufacturing. In welding and additive manufacturing, the wires are preferably remelted. Therefore, the final product has essentially the same quality as if it were manufactured with a conventional wire. In additive manufacturing, wires are melted and the molten material is applied layer by layer in specific areas. After solidification, this process creates a 3D component. In welding, a wire is melted and inserted into a joint. After the molten metal solidifies, a metallurgical bond is formed. In additive manufacturing and post-solidification welding, it is generally not apparent whether the wire used was produced by forming or melt metallurgy. Therefore, the chemical composition and diameter of the wire are of primary importance. Additionally, the strength and other properties of the products may be relevant for handling and storage. The chip and / or powder material used to manufacture the wire semi-finished product is usually contaminated by previous process and / or processing steps. In particular, contamination within the meaning of the invention means that undesirable foreign materials and / or substances are present in the chips, shavings, and / or powder material that can impair the quality, purity, and / or functionality of the material. The contaminated metallic shavings and / or powder material typically originates from a previous machining operation during the manufacture of components and / or from components that have been shredded using a metal shredder. The typically contaminated secondary material in the form of metallic chips is provided for further processing, starting with process step a). In particularly preferred embodiments, the chips are uncontaminated or substantially uncontaminated. In process step a), the metallic chips, especially coarse chips, are reduced in size. Various methods for reducing the size of chips are known in the prior art, such as shredding and chipping. Within the scope of the invention, the reduction of the chips serves in particular to convert them into a smaller initial form, which is advantageously suited to achieving the highest possible bulk density of the loose chip filling in the casing. In preferred embodiments, the chip capacity (SC) of the crushed chips is less than 2, particularly preferably less than 1.5. In particular, the chip capacity can be measured by weight measurement at a given volume (container volume). A non-limiting example for calculating chip density would be steel chips in a 1 m³ container weighing 2000 kg, where the actual density of the steel is 7850 kg / m³. In this case, the (ideal) material density is 7850 kg / m³, and the (disordered) chip density is 2000 kg / m³. This results in a chip density ratio (CR) of 7850 / 2000 = 3.925. Furthermore, process step a) includes cleaning the shredded chips. In preferred embodiments, cleaning methods are selected that are energy-efficient and / or do not damage the chips. Such methods are known to those skilled in the art. In further preferred embodiments, the metallic chips are fine chips, in particular voluminous three-dimensional fine chips. By comminution in process step a), preferably by shredding, two-dimensional fine chips with the lowest possible SRZ (separation factor) are obtained. The chips, which were crushed and cleaned in step a), are filled as loose material into or onto a casing in step b). The loose material in this step typically has a low bulk density. The bulk density depends in particular on the size and / or properties of the chips. In a preferred embodiment, the jacket is provided as a tube section, preferably having a closed bottom surface and an open top surface. The open top surface serves as an opening for filling the jacket with chips. The tube-shaped jacket has a diameter D1 and a wall thickness. In a further preferred embodiment, the chips from process step a) are distributed as loose bulk material onto an endless strip in process step b), and the endless strip is then folded. In this preferred embodiment, the outer layer is provided as an endless strip. In this embodiment, the folded endless strip has a diameter D1 and a wall thickness. Preferably, the endless strip is produced from fine chips by further processing, as described above. In particularly preferred embodiments, the endless strip or a sheet is provided as the primary material. The wire sheath with chip filling produced in process step b) represents an intermediate component characterized by the bulk density of the loose chip filling. This bulk density is transformed into a higher packing density by the subsequent process steps. In process step b), the chip filling has a chip space number (SRZ) which is preferably reduced by the further process steps. In preferred embodiments, particularly from the onset of plastic deformation, the SRZ (Single-Cut Density) can be understood as the inverse of the bulk density and the packing density of the chip filling. In preferred embodiments, the bulk density before plastic deformation is characterized by the SRZ and the orientation of the chips relative to each other. In some cases, a person skilled in the art understands the bulk density and the packing density of the chip filling as equivalent parameters, with the bulk density preferably describing a loose bulk and the packing density indicating the density of the compacted bulk. In step c), the bulk density of the filled casing is increased. An increased bulk density ensures, in particular, increased stability of the wire semi-finished product, an increase in load-bearing capacity, an improvement in thermal properties, and / or, most preferably, a high recycling rate. A recycling rate refers specifically to the proportion of waste products that are reused or recycled within a given period, compared to the total amount of waste products that are theoretically available for recycling. Thus, a high recycling rate indicates that a large portion of the waste is reused, which contributes to conserving resources and reducing environmental impact. Various chipless forming processes, particularly for rotationally symmetrical workpieces such as tubes and bars, are known in the art. In preferred processes, these methods also reduce the diameter of the workpieces. One such process is rotary swaging, in which the workpiece is kneaded by oscillating tools rotating parallel to it. The pressure exerted by the tools on the wire sheath reduces its diameter and simultaneously increases the packing density of the crushed chips within the wire sheath, thus reducing the scaling ratio (SRZ). In this process, the workpiece is preferably moved axially by means of roller drives. In the preferred embodiment (I), an external vibration is applied to the filled wire sheath in step c). This increases the bulk density while the diameter D1 remains unchanged. External vibrations can be generated by tools including vibrating plates, ultrasonic sonotrodes, unbalance vibrators, and pneumatic, hydraulic, and electric piston vibrators. In accordance with the invention, external vibrations are defined as targeted periodic movements applied to the wire sheath with the aim of increasing the bulk density. The application of external vibrations can increase the bulk density by causing the chips to settle into voids that formed during the pouring process. Furthermore, external vibrations advantageously lead to a conformal alignment of the chips. Particularly long or irregular chips can interlock more effectively through vibration, thereby filling the volume of the wire sheath more efficiently. The application of vibrations results in a denser packing of the material, a reduction in voids, and an increase in bulk density. In a further preferred embodiment (II) the bulk density is increased by rotary kneading, rotary kneading process-inherent vibrations and / or by a diameter reduction from D1 to D2. In a preferred embodiment, where the casing is provided as an endless strip in step b), the bulk density is increased by rotary swaging and vibrations inherent in the swaging process. In particular, the diameter D1 is reduced to diameter D2 in this embodiment. In this embodiment, various effects occur in parallel but are location-dependent. Specifically, the bulk density is first increased at a location behind a chip container or chip feeder but in front of the rotary swaging tool, as exemplified at locations B and especially C in Fig. 2, while maintaining a constant SRZ (seamless surface area). Simultaneously, the SRZ and the diameter are reduced at location D in Fig. 2, thereby increasing the packing density at location D. The preferred method (II) for increasing the bulk density is selected particularly, but not exclusively, when the loose chips in process step b) have been distributed on an endless belt which has then been folded. In this preferred embodiment, steps b) and c) partially coincide accordingly. In particular, the bulk density is advantageously increased by vibrations inherent in the rotary kneading process and / or external vibrations, without chips being lost during this process step. In process step d), the diameter D1 or D2 of the filled wire sheath from the previous step is reduced to a predetermined diameter D3. In particular, in process step d), the bulk density or packing density of the chip filling is further increased, and the SRZ (single-point reduction) is reduced. The diameter reduction is preferably achieved by rotary swaging, wire drawing, or a combination of both forming processes. The process of wire drawing is known from the prior art, in which a wire is guided through a conical opening of one or more drawing dies. The diameter of the wire is thereby gradually reduced to a predetermined value D3. Rotary swaging is a process in which a workpiece is machined in a rotating tool between two or more rollers. This deforms the material and uniformly reduces the workpiece's diameter while simultaneously increasing its length. In particular, rotary swaging inherently causes vibrations that propagate along the workpiece. The semi-finished wire products produced in process step d) are preferably wires with a predetermined end diameter D3. These wires are primarily used in the application areas of joining welding and / or additive manufacturing by arc and / or laser cladding. In a preferred embodiment of the invention, possibly contaminated metallic coarse shavings are used as the starting material in the process for producing a wire. According to the invention, "coarse chips" refers in particular to chips comprising the forms of ribbon chips (SRZ ≥ 90), flat helical chips (SRZ ≥ 50), long cylindrical helical chips (SRZ ≥ 50), helical chip pieces (SRZ ≥ 25), spiral chips (SRZ ≥ 8), spiral chip pieces (SRZ ≥ 8) and / or crumbly chips (SRZ ≥ 3) or combinations of the aforementioned chip types. The scope of application of the invention is advantageously extended by the fact that different chip shapes can be used as starting material for wire production. The proposed method is suitable for processing metallic chips with an initial low chip space count, such as those encountered in processes like precision turning, precision milling, or high-precision drilling. Furthermore, the method is also suitable for processing chips with a high chip space count, such as those produced in rough turning or applications with large depths of cut. In a preferred embodiment, the chips consist of metals and / or their alloys. In particularly preferred embodiments, the chips consist of metals selected from the group comprising Al, Ni and their alloys, particularly preferably Ti and Ti alloys, and most particularly preferably Cu and Cu alloys. In particularly preferred embodiments, impurities in the metallic chips, which originate as secondary products or scrap materials in a production process, can be coolant and / or lubricant adhering to the chips. In preferred embodiments, the chips are contaminated by oxidation processes and originate from machining processes of metallic tools and / or from the abrasion of the tools used in the production process. In further particularly preferred embodiments, the metallic chips are clean, species-rich chips. In particular, the chips are cleaned in process step a), and thus preferably a large proportion of the residues, and especially preferably almost all residues, are removed. Preferably, a large proportion of the coolant residues are removed from the chips, and most preferably, all coolant residues are removed from the chips. In a particularly preferred embodiment, the chips are free of or substantially free of contamination, so that the cleaning step in process a) can be omitted or carried out anyway. In particular, no change to the chips is to be expected as a result of this step. In a preferred embodiment, in step a), the metallic chips are crushed such that they have a low chip space number SRZ ≥ 2, preferably 2 ≥ SRZ ≥ 1.5, and particularly preferably SRZ ≈ 1. This results in a higher bulk density of the chips in process step b) than would be the case without crushing in step a). This allows for advantageous filling of the wire sheath with chips. The bulk density, preferably a high bulk density, is crucial for the quality and / or hardness of the produced wire half or wire. Since denser chips are more easily compacted into a homogeneous and stable wire, a high bulk density simplifies the subsequent rotary swaging and / or wire drawing processes. Smaller and more compact chips require less plastic deformation to bond into a wire. In a remelting-free process, no thermal energy is supplied during rotary swaging. Therefore, the chips must be mechanically deformable to achieve good compaction. A low chip space ratio promotes this property because the smaller chips can then be more easily formed into a dense, cohesive structure by the swaging movements. A high bulk density is advantageous from the perspective of the circular economy, process efficiency, and process control.The denser the initial wire, the simpler, more reproducible and / or more stable the respective forming process. In preferred embodiments, a lower chip space ratio (CSRR) reduces the volume that needs to be filled during the compaction process. This minimizes air inclusions and / or incomplete connections, contributing to improved wire quality. Furthermore, because the chips are already denser at a lower CSRR, less mechanical pressure is required to compact them into wire. This simplifies the rotary swaging process and can reduce energy consumption and / or wear on the machinery. In a preferred embodiment, a wire sheath in the form of a tube is provided in process step b). The tube is characterized by a closed bottom surface and an open top surface. The top surface serves as an opening for filling the tube with chips. In preferred embodiments, a vent hole is provided in each end face of the setup for rotary swaging. The length of the tube is preferably 80 mm to 200 mm, particularly preferably 100 mm to 150 mm, and most preferably 90 mm. The initial diameter D1 is determined by the relevant framework conditions of the application area of ​​the wire to be produced and / or by the material composition of the chips. A starting diameter D1 of approximately 2 mm is particularly advantageous when machining materials with a high degree of hardness, such as titanium or titanium alloys. In particular, reducing a diameter D1 from 2 mm to a typical final diameter D3 of 0.8 mm corresponds to a low degree of deformation. In the context of the invention, a "degree of deformation" describes the ratio of the cross-sectional area before and after the reduction of the wire sheath's diameter. Higher degrees of deformation result in higher deformation forces, which increases energy consumption and wear on the equipment, and may reduce the quality of the produced wire, for example, through cracking. A diameter D1 of approximately 100 mm is particularly preferred for machining wrought copper or bronze alloys, as these materials exhibit a higher degree of post-compaction. In the context of the invention, post-compaction refers to an improvement in material properties through increased density and / or homogeneity of the material. In the case of wrought copper or bronze alloys, reducing the diameter leads to work hardening of the material, which is particularly important for applications where the alloys are subjected to high mechanical stress. Furthermore, the material's porosity can be reduced through the densification effect. This can contribute to increased conductivity and, due to the denser structure, hinder the penetration of corrosive media, thus increasing the material's corrosion resistance. In another respect, the use of a wire sheath with a large diameter D1, on the order of 100 mm, is preferred for reasons of material requirements. The larger the diameter D1 of the wire sheath, the greater the ratio of recycled material in the form of shredded chips to the sheath. A large diameter D1 therefore allows for a maximum degree of recycled material use, thereby reducing the manufacturing costs of the wire to be produced. A larger diameter D1 simplifies the handling of wire production, especially filling the tube with chips. Furthermore, coarser chips can be used, and the likelihood of chips becoming jammed in the tube is reduced. In a particularly preferred embodiment of the invention, the wire sheath in process step b) is an endless strip, wherein this strip is formed into a funnel, this shape affecting only a portion of the endless strip. All process steps a) - d) proceed in parallel along the endless strip, depending on their position. In particular, the continuous belt is folded at one point or in one section, with this fold initially forming a U-shape and then continuing into a wire or tube. At another point between the flat continuous belt and the section already folded into a tube, the continuous belt is folded into a funnel. This funnel preferably serves for filling with chips. The funnel shape, in particular, simplifies the filling process. Subsequently, as already described, the bulk density is increased in a further step, for example, by vibration. In the further process, the belt is completely folded and the diameter is then reduced to the final diameter D3. In a preferred embodiment, the final diameter D3 of the wire to be produced is 1.6 mm, preferably 1.0 mm, particularly preferably 0.8 mm, and most preferably 1.2 mm. The predefined diameter D3 is set by rotary swaging, direct wire drawing, or a combination of both methods. The choice of diameter D3 can depend on the application of the wire to be produced. In a further aspect, it is preferred, in accordance with the invention, that the chips poured into the jacket have the highest possible bulk density. The bulk density depends on various factors, primarily the size, shape, and moisture content of the chips and / or the way in which the chips are poured into the jacket. In a particularly preferred embodiment of the invention, the reduction of the wire sheath diameter and the increase in bulk density occur simultaneously or substantially simultaneously during rotary swaging. Rotary swaging reduces the diameter to D3. In the same step, the vibrations occurring during the rotary swaging process act on the wire sheath in such a way that they contribute to an increase in bulk density. Advantageously, two separate process steps can thus be combined in the rotary swaging process. Combining these two steps advantageously reduces the production time of a wire. Furthermore, it reduces the need for different tools, since instead of one tool for increasing bulk density and one tool for reducing the diameter, only one tool is required to perform both steps. In further preferred embodiments, a sintering process can be used to homogenize the wire blank and / or to achieve solid welding of the chips. The sintering process comprises heating the material to a temperature below its melting point, whereby the powder particles bond together to form a solid structure. According to the invention, "semi-finished products" (rarely also "wire semi-finished products") are preferably metallic materials in wire form that have been formed into a specific shape and size by forming processes such as wire drawing or rotary swaging and / or have not yet undergone the final processing stage. These thus represent an intermediate stage in production or a pre-product. As a rule, wire semi-finished products are used for further processing in other manufacturing processes, for example in wire processing, cable manufacturing, or as raw material for specific applications such as welding or additive manufacturing. According to the invention, the "bulk density" preferably refers to the density, i.e., the mass per unit volume, of a loose mixture of a granular solid, preferably chips, and a continuous fluid, preferably air, which fills the voids between the particles or chips. Thus, in the present invention, the bulk density describes the ratio of the mass of a bulk material, or of the chip and / or powder material, to a given bulk volume. In particular, the bulk density of the chips in a wire sheath is specified. An increase in the bulk density, as in process step c), therefore leads to a reduction in the air-filled voids or to an increase in the chip and / or powder material per unit volume. An increase in bulk density can thus be achieved either by reducing the volume and / or by increasing the mass while maintaining a fixed volume.In particular, the bulk density results from the chip space ratio (CSRR) and the positioning of the chips relative to each other. Preferably, the bulk density can be increased by "shaking" or "vibrating" the material while maintaining the same CSRR, if the chips assume a more favorable position relative to each other. The "packing density," for example of chips in a tube or wire sheath, preferably describes the density achieved when the particles or chips are packed more densely. In some contexts, the terms bulk density and packing density are used interchangeably to describe the density of the chip material in a wire sheath and should be understood accordingly. The term "chip" or "chips" preferably refers to mechanically removed particles from, for example, a machined workpiece. In particular, metallic chips removed from metallic workpieces are relevant in the present invention. According to the invention, metallic chip and / or powder material can also be considered chips. The "chip volume ratio" (CRR) preferably indicates the ratio between the space required for a random quantity of chips and the volume of material removed. The CRR is primarily determined by the shape of the chips. Specifically, the space requirement can be understood as the chip volume. The smaller the CRR, the less space is needed for the chips, and the easier they are to handle and melt down in the steel mill. Thus, the CRR preferably indicates how much more transport volume a chip shape requires than the actual material volume of the chip. In particular, the CRR is a dimensionless quantity. The CRR of chips is typically dependent on previous manufacturing processes. Chips with a low chip volume ratio are generally the product of machining processes characterized by low material removal and very fine chips.In contrast, chips with a high chip space number typically arise in processes characterized by the removal of large quantities of material, e.g. the machining of large components. In the context of the invention, "remelting-free" means, in particular, that the chips are processed into a wire semi-finished product without having been previously treated by a melt metallurgical process. Avoiding the melting process customary in the prior art allows for significant energy and cost savings and reduces the overall costs of the processing. Arc cladding is primarily an additive manufacturing process in which a metallic filler material, usually in wire form, is melted by an electric arc and precisely applied to the surface of a component. The electric arc acts as the heat source. Laser cladding is primarily an additive manufacturing process in which a metallic filler material, usually in wire form, is melted by a laser and precisely applied to the surface of a component. The laser acts as the heat source. Examples of implementation The following examples are not intended to limit the scope of the invention, but rather represent exemplary, non-limiting embodiments of the invention. Fig. 1 shows two possible process routes for the remelting-free processing of chips into wire. Fig. 2 shows a section of an endless strip, with particular emphasis on the relevant areas where the individual process steps partially run in parallel. Figure 1 illustrates two possible process routes for the remelting-free processing of chips into wire. Process route 1 is a preferred embodiment of the invention, while process route 2 represents a prior art solution. In a preferred method according to the invention, the process steps i) - iii) and / or iv), and / or vii) and / or viii) are carried out. Step i) represents the initial state, in which the chips are provided as loose bulk material and a section of pipe. In (ii), the filled wire sheath with diameter D1 is provided, and the bulk density is increased by means of external vibrations. In (iii), rotary swaging is shown, which increases the packing density of the chips in the wire sheath and reduces the wall thickness. The next step (iv) is optional and represents a possible sintering process to achieve homogenization and / or local solid-state wear of the chips. For this purpose, a heating element and / or a continuous furnace is provided. The wire blank, i.e., the filled wire sheath, is further processed by rotary swaging, thereby further reducing the diameter, increasing the bulk density, and reducing the SRZ (solid surface area).To reduce the diameter D2 of the wire blank after process step iii) to the specified final diameter D3, either wire drawing (vii) and / or rotary swaging (viii) or a combination of both forming processes is applied. Wire drawing produces the cast billet, with an increased packing density compared to the original bulk density. Furthermore, wire drawing achieves the uniform roundness of the wire or the cast billet. Additionally or alternatively, rotary swaging in step (viii) increases the packing density and / or reduces the wall thickness. In conventional non-remelting forming processes for the production of wire or wire blanks from chips, a bed of metal chips is filled into an inner bushing in the first step (v). In the next step (vi), a direct bar pressing process is used. A compact block (chip-based billet) is produced by compaction and / or agglomeration. Similar to a preferred embodiment of the process according to the invention, as shown in process route 1, the wire blank from process step (vi) is optionally further processed by wire drawing (vii) and / or rotary swaging (viii). The disadvantages of the described prior art compared to the embodiments according to the invention relate essentially to a limited length of the wire (the necessary forming forces increase with the length of the wire due to friction on the cylindrical surface with the die), high wear of the dies in steps v) and / or vi), for example due to sharp-edged chips, as well as limited suitability and / or insufficient forming capacity for the subsequent rotary swaging (insufficient bonding of the chips to each other, the chip-based billet crumbles during rotary swaging) or wire drawing (chip-based billets can only withstand very low tensile stresses). Fig. 2 shows an endless belt and the various process steps, which in the process according to the invention take place partially in parallel at sections A, B, C, D, and E. Section A represents the endless belt without folding. The black triangle marks the chip container, specifically a section where the endless belt is filled with chips. Section B shows a section where the endless belt is partially folded, and section C shows a section where the endless belt is folded somewhat further. In the section between B and C, the chip filling has a low bulk density and a high chip capacity (CC). At point B, the hopper is filled primarily with chips. At section C, the bulk density is increased, while the CC remains constant, by a more favorable positioning of the chips relative to each other. This more favorable positioning results from the vibrations.In particular, the diameter is not yet defined at these points, as the endless strip has not yet been formed into a wire. Thus, up to and including step C, the endless strip is still a kind of funnel and not yet a wire. Especially in the areas between C and D, the bulk density increases due to the inherent vibrations of the rotary swaging process. Behind area C, the endless strip, folded into a wire and filled with chips, is shown. The bulk density is increased, the SRZ (solid surface area) remains unchanged, and the strip diameter is D1. At area D, the rotary swaging tool is shown, with the strip or wire visible within the black blocks (rotary swaging tool). The rotary swaging tool reduces the diameter of the wire and thereby inherently generates vibration. These vibrations propagate in both directions from area D, i.e., towards areas C and E. These vibrations further increase the bulk density.In this process, the SRZ (Strength of Residue) is lower due to plastic deformation at point D, and the bulk density / packing density of the wire has increased. The specified diameter D2 is reached at point D, and the manufactured wire with the intermediate diameter D2 is shown in area E. Furthermore, the packing density is increased by plastic deformation of the entire wire, and the SRZ is reduced by plastic deformation of the chips. The chips are essentially flattened and occupy a smaller external volume. Thus, in this specific embodiment, which is carried out using an endless belt, the various steps of the process are performed locally and in parallel. For further diameter reduction of the wire to the final diameter, another wire drawing process or another rotary swaging process is carried out at point F to further reduce the diameter to the desired value through further forming. Additionally, in Fig. 2, the letters a) - f) illustrate the shape or symbolic curvature of the endless strip during the manufacturing process into a wire. In particular, g) symbolically represents a finished circle. In a), the essentially flat endless strip is shown; in b), a partially folded endless strip; in c), a further folded endless strip; in d), a circular kneading tool is shown on the outside and a wire with a diameter on the inside; in e), the wire after forming; and in f), a further forming of the wire, especially for diameter reduction, is shown.

Claims

A method for producing a wire semi-finished product by remelting-free processing of contaminated metallic chips, characterized in that it comprises the following steps: a) comminution and cleaning of the chips, thereby obtaining cleaned chips; b) filling a sheath with the cleaned chips, thereby obtaining a wire sheath with a chip filling characterized by a chip space number (CSN), wherein the filled wire sheath has a diameter D1; c) increasing the bulk density of the chips in the wire sheath by (I) applying external vibrations without diameter reduction or (II) circular swaging process-inherent vibrations with diameter reduction to D2; d) reducing the diameter D1 or D2 to a predetermined final diameter D3, wherein the bulk density of the chip filling in process step c) is increased and the CSN is reduced.and wherein the diameter reduction is achieved by rotary swaging or wire drawing or by a combination of these forming processes. The method according to claim 1 is characterized in that the chips are selected from a group comprising strip chip (SRZ ≥ 90), tangled chip (SRZ ≥ 90), flat helical chip (SRZ ≥ 50), cylindrical helical chip (SRZ ≥ 50), helical chip pieces (SRZ ≥ 25), spiral chip (SRZ ≥ 8), spiral chip pieces (SRZ ≥ 8), and / or crumbly chip (SRZ ≥ 3) or combination of the aforementioned chip types. Method according to claim 1 or 2 characterized in that the contamination of the chips is preferably caused by lubricants, preferably cooling lubricants, or the chips are not contaminated. Method according to one of claims 1 to 3 characterized in that the metallic chips are preferably selected from a group comprising Al, Ni, Ti, Cu and their alloys. Method according to one of the preceding claims characterized in that the chips after comminution in process step a) have a chip space number SRZ ≥ 2, preferably SRZ ≥ 1.5 and particularly preferably SRZ ≈ 1. Method according to one of the preceding claims, characterized in that in method step b) a tube which is filled with chips is preferably provided. Method according to one of the preceding claims, characterized in that in process step b) the sheath is preferably an endless belt which is filled with chips as loose bulk material and is folded to form the wire sheath, particularly preferably to form a funnel-shaped wire sheath. Method according to one of the preceding claims, characterized in that the output diameter is preferably 2mm-100mm, for Ti materials particularly preferably 2mm, for Cu or bronze wrought alloys particularly preferably 100mm. Method according to one of the preceding claims, characterized in that the final diameter is preferably 1.6 mm, particularly preferably 1.0 mm, particularly preferably 0.8 mm and most preferably 1.2 mm. Method according to one of the preceding claims, characterized in that the process steps c) and d) are carried out together in one step, wherein the diameter reduction preferably includes a rotary kneading process which preferably triggers a vibration which leads to an increase in bulk density.

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