Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
  • H01B1/026—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper

Definitions

• the invention relates to a catenary wire of a high-speed electrical railway line with a tensile strength (R m ) of the wire of at least 550 MPa and an electrical conductivity ( ⁇ ) of at least 65%, based on that of annealed pure copper according to the International Annealed Copper Standard (IACS) .
• the invention further relates to a method for producing such an overhead contact wire.
• Such an overhead contact wire and a corresponding manufacturing method are described in ER 0 569 036 A.
• the contact wire material is therefore subject to the highest demands with regard to its mechanical tensile strength R m with high electrical conductivity ⁇ at the same time.
• a CuAg alloy with an Ag content of 0.1% by weight Ag content is used for the contact wire of the Re250 control overhead line from Deutsche Bahn AG with a grooved profile and 120 mm2 diameter.
• This alloy has a tensile strength R m of about 350 MPa (N / mm2) with a conductivity ⁇ of about 95%, based on that of annealed pure Cu according to IACS (International Annealed Copper Standard).
• the contact wire is designed for regular operation at speeds of up to 250 km / h. Taking into account an unavoidable wear, it is prestressed at 125 MPa, ie with about 36% of its tensile strength ⁇ or a safety margin against breakage of about 2.8 (cf.
• a contact wire pretension of up to 200 MPa is required to design the overhead contact line for regular operation at high speeds of over 300 km / h. Based on the aforementioned safety margin, this requires a contact wire alloy with a minimum tensile strength ⁇ of approximately 550 MPa. The tensile strength is determined by tensile tests according to DIN 50145/46 (cf. the book “Materials in Electrical Engineering” by H. Fischer, 3rd edition, G. Hanser Verlag Kunststoff Vienna, 1987, pages 113 to 121).
• Such a high minimum tensile strength can be achieved, for example, with Cu alloys to be taken from the EP-A mentioned.
• one of these alloys consists of the components Cr (0.1 to 1%), Zr (0.01 to 0.3%), Mg (0.001 to 0.05%), O (maximum 10 ppm) and Cu (balance) together including unavoidable impurities.
• the selected composition of the alloy means that a casting strand obtained from the melted components must be cooled very quickly after hot rolling to an initial wire, either by immersing it in a water or oil bath, or after a slower air cooling, then an additional heat treatment (solution annealing) with rapid cooling must be subjected.
• the preform obtained in this way is then subjected to a number of cold deformations which are interrupted by precipitation annealing. Because of the generally necessary rapid cooling of the preliminary product from the solution temperature (860-1000 ° C.), the known method is relatively complex and therefore not very suitable for commercial wire production.
• the object of the present invention is to provide a catenary wire made of a material which, on the one hand, meets the minimum requirements mentioned with regard to the mechanical tensile strength R m and the electrical conductivity ⁇ and, on the other hand, enables the wire to be produced in a simplified manner compared to the known methods.
• the catenary wire consists of an at least 5-component, hardenable Cu a Cr b Zr c Mg d X e alloy, where X is an element from the group of the elements Al, P, S, Fe, Ni , Zn, Ag, Cd, In, Sn, Sb and Bi and should apply to the components (each in percent by weight): 0.2 ⁇ b ⁇ 0.8, 0.02 ⁇ c ⁇ 0.4, 0.01 ⁇ d ⁇ 0.2, 0.01 ⁇ e ⁇ 0.4, With a + b + c + d + e ⁇ 100 including unavoidable pollution elements.
• the invention is based on the knowledge that, with the choice of the Mg component in combination with the stated proportions of the other components, a special treatment of the wire precursor in the form of rapid cooling from the melting or solution temperature can advantageously be dispensed with .
• a melted from the alloy according to the invention then normal in the usual way, for example from 1200 ° C. to room temperature in 5 to 10 minutes, cooled and optionally still, for example, pre-deformed starting product or wire preliminary product by hot rolling only needs to be cold-formed and stored in order to obtain a wire with the desired properties.
• the materials to be selected for the X component (5th component) advantageously increase the yield strength of the Cu alloy and improve the formability of the wire intermediate. These properties are particularly important if only one single cold forming is to be provided in the manufacture of the wire.
• the wire according to the invention has a Si-free Cu alloy.
• an Si component By avoiding an Si component, an undesirable reduction in the electrical conductivity ⁇ can be ruled out (cf. e.g. the book “Materials in Electrical Engineering", page 172).
• the manufacturing method according to the invention is characterized in that first a wire intermediate is created, the Cu alloy is melted and then cooled comparatively more slowly compared to rapid cooling, then the wire intermediate is converted into an intermediate wire by means of at least one cold deformation, then the intermediate wire is subjected to at least one aging heat treatment and, if necessary, the steps of cold working and / or the aging treatment are repeated at least once more, the final shape of the wire being produced with the last cold working.
• the intermediate wire product can be produced directly from the melt of the Cu alloy. However, it is also possible to convert an initial product formed from the slowly solidified melt into the intermediate wire product by means of at least one preliminary deformation.
• the melt should have a comparatively lower cooling rate, in particular at a maximum of 20 ° C./s in the important temperature range from the melting temperature to around 700 ° C. , are cooled. Below 700 ° C the cooling rate can be significantly lower, for example 5 ° C / s. Such cooling rates can be achieved without great effort, so that the method according to the invention is advantageously easy to carry out.
• the aging heat treatment is carried out in a manner known per se at an elevated temperature and over such a period of time that the precipitates required for hardening the material form on the dislocation structures produced by the cold deformation.
• the material from the individual components is first melted, preferably in a protective gas atmosphere, such as under Ar.
• the oxygen content in the melt should namely be as low as possible and preferably below 100 ppm.
• the melting point of Cu (1084 ° C.), in particular to at least 1200 ° C., must be used for heating. If necessary, even higher temperatures are possible. This is why induction melting is advantageous intended.
• the melt is then cooled at a cooling rate or rate (in ° C / min) which, in the temperature range important for the formation of the precipitation-hardened material, between the melting temperature and about 700 ° C is clearly below the cooling rates characteristic of rapid cooling of at least is about 100 ° C / s.
• Cooling rates of at most 20 ° C./s in the temperature range mentioned are particularly suitable. Such cooling rates can be achieved, for example, by simply pouring them into a water-cooled mold under air or in a protective gas atmosphere. Quenching in a water or oil bath can therefore advantageously be dispensed with.
• the direct pouring of the melt into a pre-wire with a diameter of 20 to 30 mm, for example, by pulling off the melt through a water-cooled, horizontally stored mold is particularly suitable here.
• the melt mass which may be cast into blocks or bars, can then be remelted in order to create a wire preliminary product which is more suitable with regard to the wire shape.
• the cooled melt mass can be processed into a wire intermediate as a pre-wire by hot rolling. Hot rolling can also directly follow the melting of the Cu alloy in a continuous step, a so-called casting roll. Remelting of the cooled melt mass to form an ingot is also possible, which is processed, for example by extrusion, to form a pre-wire. Pin-like bodies can also be worked out from a corresponding ingot, which are then deformed, for example by round hammers, to form a pre-wire.
• the pre-wire cross-section should be set so that a cross-section reduction of 50 to 99%, preferably 60 to 95%, takes place in the subsequent at least one cold deformation in order to obtain the desired final cross-section of the overhead wire.
• the wire pre-product (or the pre-wire) is then subjected to a first cold forming.
• a first cold forming Such cold working can e.g. by pressing or rolling or hammering, in particular by pulling.
• the degree of deformation is generally between 20 and 80%, preferably between 40 and 70%.
• three drawing steps with a cross-sectional reduction of 38% to 34% (1st step) or from 34% to 30% (2nd step) or from 26% to 24% (3rd step) are selected.
• dislocation structures are produced in the wire intermediate product to be obtained in a known manner, which are prerequisites for sufficient hardening of the material.
• the first cold-forming step is then followed by a first aging heat treatment of the wire intermediate, which is advantageously carried out at a temperature between 350 ° C. and 600 ° C., preferably between 450 ° C. and 500 ° C.
• a first aging heat treatment of the wire intermediate is advantageously carried out at a temperature between 350 ° C. and 600 ° C., preferably between 450 ° C. and 500 ° C.
• the duration of this heat treatment is generally between 10 minutes and 10 hours. Considerable heating up and cooling down times have to be considered for large batches.
• each cold deformation in particular the last cold deformation, can be composed of several cold deformation steps.
• An at least 5-component Cu alloy of the composition Cu a Cr b Zr c Mg d X e is provided for the catenary wire to be produced in this way.
• This proportion ⁇ of impurity elements is generally less than 100 ppm per impurity element.
• the following table shows the tensile strength R m , the microhardness HV, the conductivity ⁇ and the elongation at break ⁇ B for some wires made of Cu alloys according to the invention in comparison to the known CuAg0.1 alloy for different processing states.
• the microhardness HV50 was determined on cross sections perpendicular to the longitudinal direction of the wire.
• the electrical conductivity ⁇ was measured with 0.2 to 1 A alternating current in lock-in technology at 370 Hz using a four-point method.
• the conductivity values determined apply to a temperature of 20 ° C.
• the specified properties are the same for corresponding catenary wires.
• the 5-component alloy according to the invention is of course only a base alloy for a catenary wire for high-speed electrical railways, to which at least one further element may optionally be added in a relatively small proportion of less than 0.1% by weight.
• additional elements are selected in particular from the elements provided for the X component.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Conductive Materials (AREA)
• Contacts (AREA)
• Manufacturing Of Electric Cables (AREA)
• Electric Cable Installation (AREA)
• Organic Insulating Materials (AREA)
• Manufacture Of Switches (AREA)

Applications Claiming Priority (4)

Publications (3)

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Cited By (6)

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• 1995
  • 1995-08-21 DE DE19530673A patent/DE19530673A1/de not_active Withdrawn
  • 1995-08-23 AT AT95113311T patent/ATE172814T1/de not_active IP Right Cessation
  • 1995-08-23 EP EP95113311A patent/EP0702375B1/fr not_active Revoked
  • 1995-08-23 ES ES95113311T patent/ES2123883T3/es not_active Expired - Lifetime
  • 1995-08-23 DE DE59504054T patent/DE59504054D1/de not_active Revoked

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