DE2052462A1 - Process for the production of copper-clad aluminum wires - Google Patents

Description

Cable and metalwork Gutehoffnungshutte Aktiengeiollachaft

1 Io9o * .ü. Io. 197ο

Process for the production of copper- clad aluminum wires

The present invention is concerned with a method for the production of wires from an aluminum cele and a coat in the shape of a around the aluminum core copper country shaped and welded to form a roll. Such copper-clad aluminum wires have something special Advantage that they are relatively small specific weight and economic efficiency of aluminum with the good electrical properties of copper associate.

According to a known method (DOS 1 $ o "f Io7) an aluminum strand emerging from a press is used as the aluminum core, which is enclosed by a longitudinally running, tubularly bent copper rim. This copper band is welded at its edges and then welded to the aluminum core to the respective wire diameter In order to prevent the formation of oxide layers on the priced aluminum strand, the aluminum core emerges from the press and the subsequent wrapping with the longitudinal copper tape takes place in a protective gas atmosphere copper-clad aluminum wires, which are characterized by a flawless, mechanically strong connection between the copper jacket and the aluminum core.

209818/0467

The present invention is for continuous manufacturing of wires made of an aluminum core and a Sheath in the form of a tube shaped around the aluminum core and welded copper tape a different way. According to the invention, the soul-forming, e.g. aluminum strand produced by casting, eating or the like surface treated under protective gas and then also under protective gas with a longitudinal inlet ends, bent tubular and wrapped in copper tape; then it is made from the aluminum core and the copper jacket formed strand in cross section preferably by at least 5 ° #> based on the initial cross-section, reduced and then the reduced strand one a diffusion layer of a few ^ m on the interface between the copper tape and the aluminum strand generating heat treatment at temperatures above 300 C, preferably between 4oo and 5 ^ * 8 C *

The diffusion layer produced in this way causes an intimate Connection between the copper and the aluminum, so there is a continuous copper-clad Aluminum wire can be made of any size can be further processed. The diffusion layer thickness, which are a few A * m, preferably between 1 and 2o / ** m can, is essentially dependent on the reduction in cross-section, the temperature used in ddr heat treatment and the duration of the temperature treatment. For a rational production this means that for the production of the intermetallic compound between the copper and the aluminum these three sizes «within certain limits, are arbitrarily adjustable, depending on the desired diffusion layer thickness according to the requirements to achieve. As soon as the welding of the

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Copper tape with the aluminum strand by diffusion has occurred, the strand produced in this way Reduce further without causing peeling or tearing the copper layer comes. Improve all further reductions liability. To what extent such a manufactured DrahV ^ u annealed again at a later point in time or is tightened, ultimately depends essentially on which properties of a copper plated according to the invention Aluminum wire are required.

The thickness of the diffusion layer between the copper tape and the aluminum strand has a decisive influence on the quality of the wire If a small diffusion layer thickness is achieved, the two metals will not be sufficiently welded together. If, however, the diffusion layer is too thick, then the result is a brittle copper-aluminum compoundi which breaks when the wires are bent, so that the copper separates from the aluminum.

υ h ac of the invention is carried out, therefore, the .larmbehandluiig of preferably at least 5o> o in the reduced cross-section strand at temperatures above 3 ° ° C, preferably between 5 and 4oo ^ 8 C. The Gluhung h can in the form of a Glühuiig: e RBEI by indirect heating, such as conduction, radiation, convection or the like. Take place. However, it is also possible for the glow to be carried out by direct heating, for example by means of electrical current.

The annealing takes place from aluminum strand and copper tape produced strand in the run, it is advantageous to have an annealing temperature of at least 500 ° C

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20b2462

choose an annealing time of a few seconds in order to achieve the desired diffusion layer thickness. Conversely, it is advantageous, if the annealing takes place while the strand is stationary, that the annealing temperature is 400 ° C. for an annealing period of a few minutes
Hours is, it is essential that depending on the
desired wire properties the three factors cross-section reduction, temperature during heat treatment
and the duration of the temperature treatment can be optimized · For example, with slight reductions in the cjuer cut but an increase in temperature, diffusion can be achieved
if the applied temperature is only applied for a short time. However, it is always the case for the sheathing of the aluminum strand under protective gas
It is essential that there is no gap between the aluminum core and the copper jacket, into which atmospheric oxygen is present

In the"

penetrate and thus an oxidation of the oxide-free itself Surface can cause.

In carrying out the invention, the surface treatment of the strand produced, for example by casting, pressing in any other way, will be carried out mechanically under protective gas. Here can
it is often expedient to remove the strand of fat residues ^. and other surface contamination through suitable
Solvents such as perchlorethylene or the like. To be cleaned before the actual surface treatment. To the
Surface treatment itself can be done by the aluminum strand
for example milled oddr peeled to the
to remove oxide layers on the strand. However, it is also possible to remove the oxide layer from the surface of the strand by means of a burst device.

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A brush device of this type expediently consists of at least one circumferential concentric to the strand rotating thirst, with the brush or brushes at Around ^ run around one strand in addition around its own axis rotate. Furthermore it kaiin to be beneficial to to prevent mutual interference i.e. contamination during surface treatment, the To arrange brushes offset in the axial direction.

Regardless of the type of oxide removal, it is essential that this surface treatment of the aluminum tranges are carried out under protective gas to prevent that further new oxide layers are formed after the treatment. A continuous removal of the oxide layer It has also proven to be advantageous to achieve through the mechanical surface treatment proved new aluminum strand before surface treatment Prepare in motion, for example by using suitable guide or Directional elements is pulled through.

Used for the aluminum strand, especially pure aluminum used because of the high conductivity, then it can be used for the surface treatment of the strand Sometimes it can be advantageous to use the aluminum strand for a short time to subcool on its surface in order to prevent smearing, for example when milling or scraping. It is also possible, however, for the aluminum strand that has been produced, for example, by casting, pressing or the like Alloys with increased machinability, e.g. lead-containing or iron-containing aluminum alloys use.

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In addition to the cleanliness of the aluminum, cleanliness is decisive for the bond between the materials used of the copper tape used. For this reason it has In a continuation of the invention, it has been found to be particularly expedient, namely the copper tape effecting the sheathing surface-treat preferably under protective gas. That is expediently done in such a way that the surface of the tape facing the strand is e.g. Brushing is roughened.

In order to prevent the band from swerving to the opposite side when brushing the copper band, the the side of the belt facing away from the brushes by being in a protective gas atmosphere Unu counter-pressure generating supports, for example in the form of rollers or the like., held in position.

Furthermore, it can often. It may be advantageous to pull the strand down further after the heat treatment and the resulting diffusion layer in order to create a increased adhesion between your aluminum tr a ng and the Achieve copper tape.

The method according to the invention can be further improved if, at the beginning of the sheathing of the aluminum, it is reduced to a certain distance in relation to its cross-section, for example in accordance with the desired dimensions of the cross-section preference. On ^ e example, a pull-down, ie a cross-sectional sr Eduk tion of the sheathed strand from the start, possible without it dull for tearing off the copper cladding ko now L.

* the beginning

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To produce a perfect weld seam on the Edges of the copper tape formed into the tube, it has also proven to be useful that the incoming, surface-treated aluminum strand before closing the casing on the bottom of the tubular bent Copper tape is pressed. This ensures that the pipe passes through the weld seam without hindrance the underlying aluminum strand can be closed can.

Furthermore, it can often be advantageous to pull it down gradually the one from the aluminum core and your copper tape existing strand alternating with a heat treatment for soft annealing or in the heated state of the Make aluminum strand. This makes the Significantly improve the quality of the wire to be produced.

The invention is based on that shown in FIGS Explained in more detail from the management example. the Figures 1 and 2 relate to manufacturing facilities, while in FIG. 3 a diagram shows the dependence of the diffusion layer thickness on the glow time.

As can be seen from FIG. 1, the arrangement for carrying out the method according to the invention consists of the storage container 1 for the aluminum strand produced by casting, pressing or the like, an adjoining brush device 3 with the brushes k and 5, as well as Exier shielding gas cover 7 * encompassing this burst device and reaching as far as the welding device 6

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Instead of the brushing device, a suitable milling, scraping or peeling device can of course also be used. The strip run-off for the copper strip 9 is denoted by 8, which is first stored in the strip storage device Io by means of the rollers 11 and 1ώ and then fed to the strip liner Ij. The band storage device also serves primarily to connect the copper bands used to one another, for example with the aid of a transverse welding device, so that a continuous sheathing of the aluminum strand is ensured. The belt cleaning device 13 with the belt dryer lk is followed by the belt brushing device 15 for the copper strip 9. Hinge side. This is followed by the molding table 18, along which the brushed copper strip is brought into the tubular shape by means of a molding device 19 'which is known per se, for example consisting of pairs of rollers arranged one behind the other. A reducing device, for example a drawing ring or one or more reducing rollers, is designated by 2o, which is referred to immediately in front of the take-off device 21, which in the illustrated embodiment is a disk, but can also be a caterpillar take-off or a collet take-off advantageous hereits reduced copper-aluminum strand ^ J ₁ as shown in cross section in Figure la.

The manufacture of a copper-clad aluminum wire according to the invention goes, for example, so that from the storage container 1 an aluminum strand e.g. a diameter of about 9 mm continuously, if necessary after prior straightening, the brushing device 3 is fed,

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which is under protective gas. The burst device 3 consists of the two revolving brushes arranged concentrically to the strand, which advantageously rotate around their own axis when revolving around the strand, while the aluminum strand 2 is withdrawn from the storage container 1 and the surface treatment by the brushing device J to remove the oxide layer the serving for the sheathing, for example 0.3 "in the thick copper tape y, runs off the tape drain 8 and is first fed to a storage device Io, from which it then runs into a per se known tape cleaning system 1 '} , where esp of grease and other contaminants The belt dryer 14, designed as a suction roller, for example, serves to dry off the last liquid residue , weu ^ a tape prepared in this way on its surface roughened and then formed under protective gas along the forming table 18 in a manner known per se by means of the schematically indicated forming device 19 around the aluminum strand ü to form a tube of 10 mm diameter and then welded to its strip edges by means of the welding device 6. rJoch during the withdrawal, the jacket formed from the copper hand 9 is then pulled down onto the aluminum strand ü by means of the reducing device üo, for example a drawing ring or one or more suitable pairs of rollers, or the strand formed from the aluminum core and the copper jacket is reduced in cross-section so that After the two metals have cooled down, a firm fit of the jacket on the core is guaranteed. The composite strand produced in this way is then wound onto the winding drum üz.

Io

209818/0467

Io

Deviating from the exemplary embodiment according to FIG. 1, the figure shows an arrangement by means of which the coated aluminum strand 2, ie the connecting strand 23 , is pulled down to the required end transverse dimension and subjected to one or more varra treatment stages to achieve the desired diffusion layer thickness . For this purpose, a reduction device 25, which is arranged in the direction of the arrow behind the outlet 2k for the composite strand, is used, which can consist of one or more pulling rings, pulling rollers or other pulling elements known per se. The annealing device 26 serves for the soft annealing of the strand with a reduced cross-section; the strand can be heated indirectly or directly. Indirect heating should be understood to mean heating via conduction, radiation or convection by different thermal carriers, such as baths, gases, etc., while direct heating by an electrical current, be it via the ohmic resistance or inductively.

The heat treatment for the purpose of deep annealing can be followed by further reduction stages, for example in the form of the schematically illustrated drawing devices 27 »28 and U9, depending on the desired wire end dimensions, which, like the reducing device 25, ^{consist of} drawing rings, reducing rollers with and without drive and known guide and pulling elements can exist. If, for example, the cross-section of the composite strand 23 is reduced by 58 to 7 o? Ί, based on the initial cross-section, as a result of the drawing steps connected one behind the other, then the wire reduced so far is subjected to a heat treatment for the purpose of achieving a diffusion layer at the interface between

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Subjected to aluminum strut and copper tape. Can do this the strand running out of the reduction stage 29 to the On reel js drum or reel wound and in one brought to the appropriate temperature in a suitable oven will. But it is also possible and often particularly advantageous to heat treatment for the purpose of diffusion in the Make pass in such a way that the from the reducer 29 outgoing strand of one in front of the take-up drum 3 ° arranged, indicated by dashed lines in the drawing annealing device 3I is supplied. The warming Diffusion annealing can also be done directly or indirectly, i.e. via the electrical Electricity or suitable baths erfojgpn. The indirect one The strand that has already been pulled down can be heated, for example, by circulating or in a salt bath direct heating by resistance heating by means of electrical power.

In the above reduction ratio of 5 l> is 7 ° 70, a diffusion layer thickness is, for example, from 6 to 8 m m at doo C after 63 minutes, at kf> o C after Io minutes if an indirect heating is selected in Umwnlzofen. If the copper-coated aluminum strand is annealed in a salt bath, where the heat transfer is much better, then a diffusion layer thickness of 6 to 8 4 * m results at a temperature of 5 ° C. after about 2.7 minutes. If the temperature is increased to around 55o ° C, the result is a diffusion layer thickness of 6 to 8 AsLin with direct heating via the Widex level of the material after 12 seconds. As a result, diffusion is basically also possible at higher temperatures, that is to say in the area of the melt flow, if the exposure time is kept extremely short.

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The influence of the ^ uerschnittsreuuktion to the required diffusion layer shows the 3 · I * ¹ de ^«1 local diagram is the dependence of the diffusion layer thickness ^ vm of the annealing time (minutes) of two kupferuiumantelter aluminum strands shown having different dear friend yuerschnittsreduktion. With the same temperature conditions, namely annealing in a salt bath of 500 C, there is reduction in the event of an external temperature. of about? o / i, based on the starting transverse slice, a layer thickness of 6 µm after about 2.7 minutes, while with your less strongly deformed composite strand the same diffusion layer thickness only reaches after 5 minutes, ie approximately twice as much ., earth. The extent to which a desired diffusion layer thickness of, for example, 6 to 8 .mu.m is achieved by greater cross-section reduction and shorter annealing time or by longer annealing time with a small degree of reduction, depends essentially on the means available for carrying out the method according to the invention.

Notwithstanding ülirungsbcispiel from that shown in the Figure 2 embodiment it can also often be advantageous, by first supplying the soft glow ck from the drain running kupferumniantelten Aluiuiuiumdrähte an annealing apparatus and the reduction of vfuerschnittes including performs "Also, the stepwise reduction can in each case in alternating with a heat treatment for soft annealing ii. Likewise, as can be seen from FIG. 3, it can often be advantageous to first reduce the cross-section, for example alternating with a deep annealing, then to connect the diffusion annealing, etvia while passing through the gluing device jl,

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and the strand treated in this way only afterwards by means of the Reducers ^ 7 to ^ 9 on the final Pull down the wire or strand diameter.

The method according to the invention for the continuous production of wires from an aluminum core and a copper jacket assumes that at the beginning of the Manufacturing first a copper pipe is welded in that the surface-treated aluminum strand 2 introduced will. The copper pipe is thereby on the HluminiunibLrang pulled down, whereby it is advantageous already in the first reduction stage copper pipe and oxide-free Aluminum strand together to reduce the cross-section. Here, however, it is gozoified that at the moment in your aluminum trang iu the reducing device, For example, the target ring or a correspondingly arranged pair of rollers, comes in, the forces to heat the composite strand become very high.

However, since there is no aluminum strand c between the trigger, for example the trigger disk ~ 1 and the reducing device, at the start of production, the relatively thin-walled copper tube must resent the entire tensile force. As a result, the copper pipe tears off. Although the degree of reduction of the compound ti-ans is decreasing, the tensile forces on the copper pipe alone can be absorbed, but the possible wjuer cut educUons are not sufficient to produce the desired intermetallic connection between the aluminum strand and the copper strip. In addition to this, the invention of aluminum will be explained in more detail . by means of suitable rollers, pulling rods or stones in the diameter to a certain one

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Length, e.g. to a machine or drum length. sharpened, i.e. brought to the diameter that it gets with the desired total reductant bn. The so prepared The strand is then in the tube shape or. Welding equipment turig retracted, so that the reduced copper pipe just sits well on the aluminum frame. the Extraction device then detects copper roll and aluminum Lrang together, so that the copper pipe tore off when traversing the following, not sharpened length, is avoided by the reducing device with certainty.

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Claims (1)

Cable and * metal works Gutehoff iiungshut te Ak txenge! Shank ή $ 1 Io 9o 22.lo.iy7o Claims jl. jVci'f uliren for the continuous division of diets made of eiiior Aluiaini uiuseele and a copper uinliül lung, the with the aluminum core, which has an oxide-free surface is metallically connected, characterized in that that that which forms the soul e.g. by casting, pressing or the like. produced aluminum strand surface-treated under protective gas and then also under gas with a longitudinally curved, l-oiirfiirmig Ivuu f he band is wrapped that the one from the aluminum core and the strand formed by the copper jacket in cross section, preferably by at least 5θ / · »based on the output cross-med reduced and then the reduced strand of a diffusion layer of a few / «in, on the Interface between the copper strip and the aluminum strip generating heat treatment at temperatures above 3 °° C, preferably between 100 and 5 ^ 8 ° C will. 2. The method according to claim 1, dadac h characterized, duu the Dxffusioiischichtdicke 1 to ^ .o αλ \\\ at viuerschnitIsrcdulvtionen between 6o ',' i and lo ^y , O and temperatures around 5oo C betx'äge. 3. Verfalu'en according to claim 1, characterized in that daii the surface treatment of the aluminum strand underneath Sclutzgas takes place mechanically. 209818/0467 k. Method according to claim 3, characterized in that the aluminum strand is milled or peeled. 5 · The method according to claim 3 »characterized in that the aluminum strand is brushed. 6. The method according to claim 1, characterized in that the aluminum strand before the surface treatment in the
Pass is directed. 7 · Verfa ^ a-s according to claim 1, characterized in that the enveloping copper tape is preferably surface treated under protective gas. 8. Veffahren according to claim 7 ι kei which the wrapping tape is surface treated, characterized in that the diadem strand facing surface of the federal government, for example
is roughened by brushing. 9. The method according to claim 8, characterized in that the suite of the belt facing away from the brushes by means of counter pressure, preferably in a protective gas atmosphere generating supports is held in position. 10. The method according to claim 1, characterized in that the heat treatment with indirect heating, such as conduction, Radiation, convection ocjbr the like. Takes place. 11. The method according to claim 1, characterized in that the heat treatment is carried out by direct heating by means of an electric current. Ιέ. Method according to claim 1, characterized in that a further reduction of the strand takes place following the heat treatment. 209818/0467 13 · Method according to claim 1 or one of the following, in which the hot treatment of the strand takes place in a continuous flow, characterized in that the heat treatment temperature, i.e. the annealing temperature, at least duration of a few seconds. i.e. the annealing temperature, at least 5oo C for an annealing l4. The method according to claim 1 or one of the following, at which the heat treatment, i.e. the annealing of the strand, in Stand takes place, characterized in that the annealing temperature is at least 4oo C with an annealing time of a few Minutes to hours. 15 · The method according to claim 1, characterized in that the Gradual pulling down of the aluminum core and copper band existing strand alternating with a heat treatment for soft annealing or in the heated state of the Composite strand takes place. l6. Method according to claim l, or one of the following, characterized in that for the surface treatment of the e.g. duxh casting, pressing or similarly manufactured strand briefly on his before mechanical processing Surface is supercooled. 17. The method according to claim 1, characterized in that for the e.g. by casting, pressing or deigl. manufactured Strand aluminum alloys with increased machinability, e.g. lead or iron containing aluminum alloys used will. l8. Method according to claim 1, or one of the following, characterized characterized in that the surface-treated Aluminum strands before sheathing in one preferably Introduced under protective gas storage and fed from this under protective gas to the strip forming device. 209818/0467 Jr 19 · Method according to claim 1 or one of the following, daduidi characterized that at the start of production of the aluminum strand to a predetermined length before sheathing in its cross-section, e.g. to the dimensions of the total reduction. 20. The method according to claim 1 or one of the following ', characterized characterized in that the incoming aluminum strand before closing the tube-shaped bent copper tape is pressed onto the bottom of the envelope. 21. Apparatus for performing the method according to claim or one of the following, characterized by a series connection a device for the surface treatment of the aluminum strand, one or more of the strip forming tube forming devices or welding devices and subsequent wire reducing and annealing device ^ if necessary in alternating order. 2έ. Device according to claim 21, characterized in that between the device for surface treatment and the tube forming device, a strand storage device under protective gas is arranged * 23 · Device according to claim 21 with a brushing device for the aluminum strands, characterized in that the Büretvorrichtungh from at least one concentric to the Strand is made of revolving rotating brush. 24. Apparatus according to claim 23, characterized in that the brush or brushes also rotate around their own axis as they revolve around the strand. 25 * Device according to claim 24, with several rotating Brushes, characterized in that the brushes in the axial direction are arranged offset. öt it / cue7 IS Blank page