DE102007034096A1 - Extrusion process for copper-surface wire involves protecting hot wire from contact with acid in air by means of protective gas - Google Patents

Abstract

The extrusion process involves the extrusion of copper from a casting billet (1) pushed by a punch (3) at a temperature of over 500[deg] C through one or more apertures of a die (4) of an extrusion press (2) and its subsequent cooling. The hot wire (5) issuing from the die is protected against contact with acid in the air by means of protective gas, and also in the cooling zone by a set-temperature water bath through which it is drawn at temperatures above 60[deg] C.

Description

The invention relates to a process for the production of wires having a "bright metallic" surface made of copper or of a copper alloy, for example, the copper alloys suitable for this purpose are in the standard DIN EN 1044 standardized. In addition to copper as alloying additives, they contain cadmium, zinc, silicon, tin, manganese, nickel, silver, phosphorus and other non-ferrous metals. From these alloys usually wires are made with diameters of 1 to 5 mm.

Methods and apparatus for making wires and rods of copper or copper alloys are disclosed, for example, in German Offenlegungsschriften DE 39 29 287 A1 and DE 196 02 054 A1 as well as in the US Patents US 2,290,684 and US 2,795,520 described. Starting point for the production of the wires are usually cylindrical ingots, which are heated to 550 to 600 ° C and extruded with an extruder to one or more wires. The resulting raw wires must usually be brought by further drawing or rolling processes to the desired final diameter.

copper or copper alloys form a dark at high temperatures Oxide skin of Cu (II) oxide at the surface and tend at large changes in shape during the drawing or rolling processes for embrittlement. Without further precautions To avoid these problems must be removed from the extruder emerging raw wires to remove the oxide skin in dilute Pickled sulfuric acid and then with water be rinsed. The embrittlement by subsequent Drawing processes can be reversed by annealing become. The cited patent documents avoid the formation of the Oxide skin by spraying the extruded from the extruder hot wires with cold water from suitable Spray nozzles to "metallic bare" wires to obtain.

It has been shown that spraying with cold Water partially to spotty surfaces of the wires leads. In addition, the wires thus produced are brittle and can not without previous annealing be processed in subsequent drawing processes.

task It is therefore the object of the present invention to provide a process for the preparation of metallic bare wires indicate which starting from a Gußblock metal Lisch bare wires supplies. Under "metallic blank" is used in the context of this invention understood that on the surface of the wires no black Cu (II) oxide is found, but only the inevitable red Cu (I) oxide.

These Task is solved by the specified in the main claim Method. Preferred embodiments of the method are given in the subclaims.

The inventive method is based on the Prior art known extrusion process. Copper or Copper alloy in the form of a cast bolt in a Extruder inserted and at a temperature above 500 ° C. through a die with at least one die opening pressed and then cooled in a cooling zone.

According to the invention the hot wire (s) emerging from the die in a stretching zone directly following the die with a protective gas largely protected against contact with atmospheric oxygen. Is the stretch zone of the environment through a suitable housing separated, so it is sufficient, the housing with the To fill inert gas and any gas losses of time to balance time. When the stretch zone is open, it must be from Inert gas is continuously flooded to prevent the oxidation of the to prevent hot wires. Suitable as protective gases Argon or nitrogen, preferably nitrogen is used.

In The stretching zone is the temperature of the wire immediately behind the Exit the die still so high that the wire has a plastic nature and with relatively little Force can be pulled in length. in this connection the cross-sectional dimensions of the wire are calculated from the Cross-sectional dimensions of the die opening to a desired cross-section reduced. This process is subject to a manufacturing tolerance, which are minimized by controlling the force acting on the wire can. Another function of the stretching zone is the separation of the hot Die from the subsequent cooling zone.

After leaving the stretching zone, the wires in the cooling zone in a tempered water bath at temperatures above 60, preferably above 80 ° C to below 100 ° C are cooled. For this purpose, the wires are preferably pulled through the water bath within 1 to 10 seconds. It is advantageous if the water bath is constantly swirled to prevent gas bubbles from forming on the hot wire surfaces. This can be done, for example, by the wires be flowed across the extrusion direction with hot water.

The Pulling speed for the wires behind the Stretching zone is preferably between 0.5 and 1.5, in particular between 0.7 and 1.0 m / s.

The inventive method provides wires with a "metallic shiny" surface, like they for further processing in downstream drawing processes is required.

To further explain the invention, the single figure is used. It shows the basic structure for carrying out the method. Reference number ( 1 ) denotes the cast bolt made of copper or a copper alloy. He is in the extruder ( 2 ) and is maintained at a temperature of, for example, 600 ° C by external heating, not shown here. With the stamp ( 3 ), the cast bolt is passed through an opening in a die ( 4 ) pressed. The extruded raw wire is denoted by reference numeral ( 5 ) designated. To the die ( 4 ) connects the stretching zone (I), in which the wire is only moderately cooled. To avoid oxidation of the wire, the stretching zone is filled or flooded, for example, with a protective gas. In the subsequent cooling zone (II), the still hot wire is cooled to a temperature below 100 ° C by passing through a tempered water bath ( 6 ), which is maintained at a temperature of at least 60 ° C. The water bath is shown in plan view of the water surface. The opposite sides of the raw wire ( 5 ) directed arrows represent a flow of the wire with water from a plurality of nozzles, which are arranged along the wire in a water bath. The necessary water is circulated. For this purpose, there is an outlet at the bottom of the water bath, through which a pump sucks water and feeds back to the water bath via the Anströmdüsen. The transverse flow of the wires prevents gas bubbles from settling on the wire surfaces and to a stained surface (their.

• • Schutz des frisch extrudierten Drahtes in der Reckzone vor Oxidation durch Befüllen oder Durchfluten der Reckzone mit einem Schutzgas,
• • Abkühlen des Rohdrahtes in einem auf wenigstens 60°C temperierten Wasserbad und
• • Verwirbeln des Wasserbades, um das Anhaften von Gasbläschen an der Drahtoberfläche zu verhindern

ihren zu Drähten mit metallisch blanker Oberfläche, die noch ein ausreichendes Formänderungsvermögen für nachfolgende Ziehprozesse aufweisen. Wesentlich hierbei ist, daß das Wasserbad auf etwa 60 bis 95°C temperiert wird. Temperaturen des Wasserba des unter 60°C führen zu einer Versprödung des Drahtes, die beim nachfolgenden Fertigziehen häufigen Drahtbruch zur Folge hat.The measures described

• Protection of the freshly extruded wire in the stretching zone from oxidation by filling or passing through the stretching zone with an inert gas,
• • Cooling of the raw wire in a tempered to at least 60 ° C water bath and
• • Swirling the water bath to prevent the adhesion of gas bubbles to the wire surface

their wires with metallic bare surface, which still have a sufficient deformability for subsequent drawing processes. It is essential here that the water bath is heated to about 60 to 95 ° C. Temperatures of the Wasserba of less than 60 ° C lead to embrittlement of the wire, which in the subsequent finishing has frequent wire breakage.

The proposed method is particularly suitable for combination with other procedural measures with the aim in one continuous operation of a cast block a ready-made wire produce with a metallically smooth surface.

In the test series described below, raw wires made of the copper alloy Ag40Cu30Zn28Sn2 (designation after DIN EN 1044 : AG 105) with a smooth metallic surface. These raw wires were then finished to a wire diameter of 1.5 mm.

One 10 kg cast bolt from said copper alloy was in an extruder through a die with two round die openings of 2.9 mm diameter each to two parallel wires extruded. In the stretch zone, the wire diameters were made by applying a controlled tensile force reduced to a nominal dimension of 1.7 mm. The stretching zone was preceded by nitrogen flow Protected against atmospheric oxygen. The stretching zone ended directly into a tempered water bath. To swirl the water the bathroom was equipped with a cross-flow device. The speed of the wires passing through the water bath was 1 m / s.

Several cast bolts were extruded with the described apparatus at different temperatures of the water bath. The extruded bare-surface wires were then drawn down to 1.5 mm diameter in a 1.7 mm drawing apparatus and their drawing behavior was qualitatively evaluated. The results are shown in the following table. Table: Drawing behavior of the extruded wires as a function of the temperature of the water bath Experiment No. 1 Experiment No. 2 Trial No. 3 Experiment No. 4 Wassertmperatur 20 ° C 40 ° C 60 ° C 80 ° C drawing behavior Wire is brittle. Frequent wire breaks while pulling Occasional wire breaks while pulling Wire can be pulled without breaks Well

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3929287 A1 [0002]
• - DE 19602054 A1 [0002]
• - US 2290684 [0002]
• US 2795520 [0002]

Cited non-patent literature

• - DIN EN 1044 [0001]
• - DIN EN 1044 [0016]

Claims (5)

A process for extruding wires of copper or a copper alloy with a bare metal surface, wherein copper or copper alloy in the form of a cast bolt and extruded at a temperature above 500 ° C by means of an extruder through a die with at least one die opening to one or more wires and are cooled in a cooling zone, characterized in that the or emerging from the die hot wires in a directly adjacent to the die stretching zone with a protective gas largely protected from contact with atmospheric oxygen and then in the cooling zone by a tempered water at temperatures above 60 ° C are drawn. Method according to claim 1, characterized in that that the wires go through in 1 to 10 seconds the water bath is drawn and cooled. Method according to claim 2, characterized in that that the water bath to avoid gas bubbles on the Wire surface is constantly swirling. Method according to claim 3, characterized that the formation of gas bubbles on the wire surface is prevented by passing along the wires a cross-flow is produced. Method according to claim 1, characterized in that that the speed of the wires behind the stretching zone between 0.5 and 1.5 m / s.