DE102007034097A1 - Method for extrusion of wires via matrix openings to control cross section measurement of formed wire - Google Patents

Abstract

The method for extrusion of wires takes place through pressing in one or more matrix openings and, thereafter, cooled off in a cooling zone. There is a bar zone arranged between the matrix and the cooling zone in which the cross section measurement of the still hot wire opposite the cross section of the matrix openings is prevented to a solitary cross section. The cross section measurement of the wire from the solitary cross section is minimised through the regulated pulling force on the wire.

Description

The The invention relates to a method for extruding wires made of copper or a copper alloy.

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.

With the described extrusion process can be wires or produce bars with different cross-sectional shapes. Round or square cross sections are preferred. The extruded wires are usually through one or more cold drawing brought to finished size. For each drawing operation, in the case of alloys, only cold forming is used possible with a degree of deformation between 25 and 30%. The degree of deformation depends on the alloy chosen. With pure copper is also a higher degree of deformation reachable. The degree of deformation is defined as the ratio the change in cross section relative to the initial cross section.

Conventionally extruded wires have, according to experience, a fluctuation range of their cross-sectional dimensions of ± 5%. For copper alloys after DIN EN 1044 However, the required limit dimensions for wires are ± 3%. In order to comply with the limiting dimensions, a so-called calibration train is first made prior to the finishing in order to reduce the tolerance of the cross-sectional dimensions. In this case, wire sections with a larger cross section are deformed more strongly than thinner wire sections. This leads to different elongation at break, tensile strength and hardness along the wires. In general, hardness and tensile strength increase with increasing degree of deformation, while the elongation at break decreases. Therefore, before the finishing, the wires must be annealed in order to eliminate the work hardening during forming by annealing above the recrystallization temperature.

The Quality of extrusion thus has a decisive influence the subsequent operations. It is therefore the task of present inventions, a method for extruding wires of copper or of a copper alloy with a reduced Tolerance of the cross-sectional dimensions. By the increased Uniformity of the cross-sectional dimensions can any further steps are omitted, such as calibration trains and intermediate anneals.

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

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

According to the invention between die and cooling zone arranged a stretching zone. In the stretching zone, the temperature of the wire is 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 with a manufacturing tolerance of about ± 5% afflicted. It has been shown that by Controlling the tensile force acting on the wire, the tolerance of the cross-sectional dimensions can be reduced to a tolerance of less than ± 3%.

at Round wires, it has proven useful when the diameter the die opening by a factor of 1.4 to 2, preferably by a factor of 1.5 to 1.8, greater than that desired wire diameter after leaving the stretching zone. A larger die diameter reduces the Requirements for the pressing pressure of the extruder.

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 tensile force for the stretching process can be introduced through a arranged behind the cooling zone stretching drive in the wire. To control the tensile force of the actual cross-section is measured at a point after the exit of the wire from the extruder and before the stretch drive and compared with the desired cross-section. The actual cross section forms the controlled variable whose deviation from the nominal cross section is determined in a controller and used to determine the necessary change in the tractive force of the stretching drive. Preferably, the actual cross section of the wire is ver behind the cooling zone measure up. Both mechanical and optical measuring instruments can be used for the measurements.

The Length of stretch zone between die and cooling zone may be between 30 and 500 mm long, preferably it has a length from 50 to 300 mm. Because the freshly extruded wire is still in this zone is very hot, it is advisable to reduce the oxidation on the wire surface by filling or flooding the stretch zone with a To prevent protective gas. Suitable shielding gases are argon or nitrogen, Nitrogen is preferably used.

Of the Wire can be sprayed in the cooling zone by spraying Water or cooled by a water bath, preferably a water bath is used.

With The method can be wires with different Cross-sectional shapes are produced, wires are preferred generated with a round cross-section. In addition, it is possible the template with several, preferably two, die openings to provide and in this way several wires in parallel to extrude each other. The regulation of the cross-sectional dimensions then becomes independent for each individual wire performed.

The Method is suitable in principle for all extrusion methods, where an endless profile with reduced tolerances of the cross-sectional dimensions should be generated. However, the method is preferred for the production of wires made of copper or copper alloys used. The copper alloys can be added to copper alloying additions from silver, cadmium, zinc, silicon, tin, manganese, nickel or phosphorus or combinations of these additives. Other non-ferrous metals are possible as alloying additives.

Especially the method is suitable for integration into a production line, in the case of a metallic bare wire starting from a cast bolt continuously is produced to the finished wire. In this case, the affects reduced tolerance for the cross-sectional dimensions advantageous to the subsequent process steps. So often enough single further drawing step to the raw wire to finished with to tighten further narrowed tolerances.

in the The following is the invention with reference to the examples and figures closer explained. Show it:

1 : Basic structure for carrying out the method

2 : Measuring log for the diameters of two wires drawn in parallel without regulation of the stretching drive

3 : Measuring log for the diameters of two wires drawn in parallel with regulation of the stretching drive

1 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 can be 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. This can be done by a spray of water or a water bath. Behind the cooling zone (II) is a measuring system ( 6 ) for determining the cross-sectional dimensions of the wire. For example, optical measuring systems are suitable. The measuring signal is in the controller ( 7 ) is compared with the value for the desired cross section and from the resulting control deviation a manipulated variable to the drive motor of the stretch drive ( 8th ). If the measured cross section is greater than the nominal cross section, the tensile force of the stretching drive is increased, resulting in a longitudinal expansion with a corresponding reduction of the cross section. Conversely, if the measured cross section is smaller than the desired cross section, the tensile force of the stretch drive is reduced. With this control, the tolerance of the cross-sectional dimensions of the extruded wire can be reduced from ± 5% to less than ± 3%.

The matrix preferably contains ( 4 ) two extrusion openings so that two wires can be pulled in parallel.

The Diameter of the wires or rods are preferred between 1 and 5 mm. Larger diameters are however also possible.

In the following comparative example and example, raw wires made of the copper alloy Ag40Cu30Zn28Sn2 (designation after DIN EN 1044 : AG 105) extruded. These raw wires were then finished to a wire diameter of 1.5 mm.

Comparative example

A 40 kg casting bolt made of said copper alloy was in an extruder through a die with two round die openings of 2.9 mm in diameter extruded into two parallel wires. In the stretching zone, the wire diameters were reduced to a nominal dimension of 1.8 mm by applying a constant tensile force. The speed of the extruded wires behind the stretch zone was 1 m / s.

2 shows the recorded with an optical measuring system diameter values over a wire length of 880 m. In 2 the upper tolerance limit (TDC) is marked with 1.9 mm and the lower tolerance limit (TDC) with 1.7 mm. These values correspond to a thickness tolerance of about ± 5%.

The Nominal dimension of the wire diameter was in this extrusion test set to 1.8 mm, even with larger fluctuations the wire diameter still enough shape change for calibration train and finish to a diameter of 1.5 mm to have available.

With the calibration train, the wires were to a diameter pulled by 1.7 mm. Because of the large diameter fluctuations The extruded wires were corresponding by the Kalibrierzug Variations in hardness, tensile strength and elongation at break inserted into the wires. By intermediate annealing above the recrystallization temperature these became different mechanical properties balanced before the wires were finished to a diameter of 1.5 mm.

example

The comparative example was repeated with a second cast bolt. In contrast to the comparative example, the tensile force has now been regulated. The nominal diameter of the wires was 1.7 mm. The measurement results for the diameters of the two wires shows 3 over a length of 980 m. In 3 again upper and lower tolerance limits are indicated. The upper tolerance limit was 1.75 mm and the lower tolerance was 1.65 mm, corresponding to a diameter tolerance of ± 3%.

The reduced with the method according to the invention Diameter tolerance of the raw wire allowed it, the mean diameter of the raw wire from 1.8 to 1.7 mm lower without loss of sufficient Change in shape during the final drawing on one Diameter of 1.5 mm. Calibration train and intermediate annealing as in the comparative example were not necessary here.

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 [0004]
• - DIN EN 1044 [0024]

Claims (11)

A process for extruding wires of copper or of a copper alloy, wherein copper or copper alloy in the form of a cast pin and pressed at a temperature above 500 ° C by means of an extruder through a die with one or more die openings and then cooled in a cooling zone, characterized in that between the die and cooling zone, a stretching zone is arranged, in which the cross-sectional dimensions of the still hot wires relative to the cross sections of the die openings are reduced to a desired cross-section, wherein the resulting deviations of the cross-sectional dimensions of the wires from the desired cross-section by applying regulated tensile forces are minimized to the wires. Method according to claim 1, characterized in that that for regulating the tensile forces the actual cross sections the wires behind the cooling zone determined and with be compared to the desired cross-section. Method according to claim 2, characterized in that that the length of the stretch zone between die and Cooling zone is 30 to 500 mm. Method according to claim 3, characterized that the stretching zone filled with a protective gas or is flooded to oxidation of the hot wires to prevent. Method according to claim 4, characterized in that that the speed of the wires behind the Stretching zone between 0.5 and 1.5 m / s. Method according to claim 5, characterized in that that the wires in the cooling zone through Sprinkle with water or cooled by a water bath become. Method according to Claim 6, characterized that the tensile forces in the wires through behind the cooling zone arranged stretching drives are introduced. Method according to claim 1, characterized in that that the cross sections of the wires are round. Method according to claim 8, characterized in that that the diameter of the die openings to the Factor 1.4 to 2 are larger than the desired ones Wire diameter after leaving the stretching zone. Method according to claim 9, characterized a die with one or two die openings is used. Method according to claim 1, characterized in that that the copper alloy next to copper alloying additives selected from the group consisting of silver, cadmium, Zinc, silicon, tin, manganese, nickel, phosphorus and combinations of which contains.