DE102010032066A1 - Method for manufacturing cathodic protected pipe profile utilized during construction of e.g. cooling agent pipeline, involves extruding press block, and forming pipe profile from press block using extruding method - Google Patents

Abstract

The method involves extruding a press block (1) with an electrochemical ignoble outer sheath (1.1) and an electrochemical noble inner core (1.2), where the press block is molded in a hollow cylindrical manner. A pipe profile is formed from the press block using an extruding method. The press block is co-extruded from aluminum alloy, and the co-extruded press block is punched perpendicular to a cross sectional surface. A hydrostatic strand-press process is implemented in the pipe profile in a direct or indirect manner at press temperature below 600 degree Celsius.

Description

The invention relates to a method for producing a cathodically protected pipe profile.

When using coated aluminum materials, such as. B. piping in corrosion contaminated installation locations, despite the passivation of the aluminum material material erosive attacks on the component surface act, which continues until the perforation of the aluminum material.

From the EP 1 433 544 B1 For example, a method of plating a metal strip to make a multi-walled tube is known. In this method, a steel sheet is immersed in a first electroplating bath and then in a second electroplating bath, and the steel sheet in the first bath is plated on both sides with a thin metal layer and plated in the second bath with copper on one side only Steel plate is subsequently immersed in a third galvanic bath, wherein the electrode of the first and second bath has a reverse polarity, whereby metal is removed, leaving only on one side a plated layer. To produce the multi-walled tube, the metal strip is rolled, wherein the rolling comprises at least two complete revolutions and thus the tube is formed, wherein the inside of the tube has the plated layer. Subsequently, the tube is heated to solder the surface of the inside and the outside which are in contact with each other. The soldering is done by directly soldering the plated side on the steel.

The invention has for its object to provide a comparison with the prior art improved method for producing a cathodically protected pipe profile.

The object is achieved by the features specified in claim 1. Advantageous developments of the invention are the subject of the dependent claims.

In a method for producing a cathodically protected tube profile, according to the invention, a pressing block is coextruded with an electrochemically non-noble outer sheath and an electrochemically noble inner core, and then the tube profile is formed from the pressing block in an extrusion process.

Due to the fact that the tube profile is produced from a coextruded press block in an extrusion process, the tube profile in a particularly advantageous manner has no cathodically unprotected longitudinal seam. By producing the press block as further processed semifinished product by means of coextrusion, a cost savings compared to the known from the prior art method for producing a tubular profile can be achieved.

The tube profile produced by means of the method according to the invention can be used in profit-making manner, for example in vehicle construction as air conditioning line, coolant line and transmission oil line.

A passivation of the pipe profile can be omitted, since the various alloys of the layers of the pipe profile of the cathodic protection is ensured. For this purpose, a core of the pressing block of an electrochemically noble metal alloy and the shell of the pressing block are formed from an electrochemically less noble metal alloy. Thus, it is possible to use the tube profile produced by the method in corrosion-contaminated installation locations, in particular in vehicle construction. The core is protected against corrosion, since the outer shell serves as a sacrificial anode.

Embodiments of the invention are explained in more detail below with reference to drawings.

Showing:

1 1 is a schematic sectional view of a coextruded press block for producing a pipe profile according to the invention;

2 schematically a device for a hydrostatic extrusion process, and

3 schematically a perspective view of a pipe profile produced according to the invention.

Corresponding parts are provided in all figures with the same reference numerals.

In the 1 is a cross section of a coextruded press block 1 for the production according to the invention of a cathodically protected pipe profile 2 which is in 3 shown is shown.

The pressing block 1 is hollow cylindrical and has two layers, with an outer layer as a shell 1.1 and an inner layer as a core 1.2 be designated.

The aim of the invention is a cathodically protected tube profile 2 which is preferably formed of aluminum alloys, and can be used without additional passivation in corrosion loaded installation locations.

The core 1.2 is formed from a first aluminum alloy in which aluminum is mixed with copper. The case 1.1 is formed of a second aluminum alloy, which has a lower copper content than the first aluminum alloy. This is the core 1.2 electrochemically nobler than the envelope 1.1 ,

The pressing block 1 is made in a coextrusion process in which the aluminum alloys are heated and pressed through a profile die to form the second aluminum alloy of the shell 1.1 not with the first aluminum alloy of the core 1.2 mixed and thus the pressing block 1 is formed as a semi-finished product. The resulting pressing block 1 is cylindrical and is then provided with a centric hole.

The cathodic protection of the pressing block 1 results from the use of the electrochemically nobler first and the electrochemically less noble second aluminum alloy.

By cathodic protection is meant corrosion protection, this type of cathodic protection being also referred to as active cathodic corrosion protection. The shell consisting of the less noble second aluminum alloy 1.1 acts on the manufactured pipe profile 2 as a so-called sacrificial or protective anode, to which the corrosion attacks, whereby a persistence of the core formed by the nobler first aluminum alloy 1.2 is largely ensured.

Because of the pressing block 1 formed by coextrusion, have the pressing block 1 as well as the tube profile produced therefrom 2 not over a longitudinal seam. Ie. the electrochemically less noble shell 1.1 is formed as a sacrificial anode over its entire surface on the outer peripheral surface, which avoids that the nobler core 1.2 corroded prematurely. A longitudinal seam, for example, as a result of a welding process, however, means a non-continuous, ie not full-surface, training of the shell 1.1 , whereby the shell 1.1 as a sacrificial anode is not formed over the entire surface and thus no full-surface corrosion protection of the core 1.2 consists.

To the cathodically protected pressing block 1 to the pipe profile 2 to process, this is, as usual with hollow profiles, pre-perforated. For this purpose, in the pressing block a perpendicular to the cross-sectional area extending pre-perforation 1.3 brought in.

As an alternative to the use of various aluminum alloys, other metallic materials, ie alloys for the production of as a pipe profile 2 trained hollow profiles are used. The preparation of the coextruded cathodically protected compression block 1 is therefore not limited to the use of aluminum alloys.

The pre-punched cathodically protected pressing block 1 is in a further process step of a device 3 fed to carry out an extrusion process, as in 2 is shown. Preferably, hydrostatic extrusion is used here, but in the same way every other suitably suitable extrusion process can be used, in particular direct or indirect extrusion.

The device 3 includes a picker 3.1 , a press stamp 3.2 , a die 3.3 , Lubricant 3.4 , a hydrostatic medium 3.5 For example, water or oil, seals 3.6 , a mandrel not shown in detail and the pressing block 1 from the tube profile 2 is formed.

In the hydrostatic extrusion process, the pressing block 1 in the picker 3.1 from the hydrostatic medium 3.5 surround. A pick-up room is opposite the punch 3.2 and opposite the die 3.3 by means of seals 3.6 sealed, so that when advancing the press ram 3.2 the hydrostatic medium 3.5 is compressed to a pressing pressure, without the press ram 3.2 the pressing block 1 touched. Even when pressing itself touches the punch 3.2 the pressing block 1 Not.

The speed with which the pressing block 1 when pressing towards the die 3.3 moved, does not match the speed of the ram 3.2 but is proportional to the displaced hydrostatic medium volume. The pressing block 1 is through the die 3.3 pressed over the mandrel, not shown, so that the tube profile 2 is formed.

For the production of the pipe profile 2 As an alternative to the hydrostatic extrusion process and the extrusion process without hydrostatic medium 3.5 be performed. This is the pre-punched block 1 also pressed by a die over a mandrel, wherein a pressing temperature of the preheated press block 1 depending on the alloys used between room temperature and a maximum of 600 ° Celsius.

The ratio of the radii of core 1.2 and sheath 1.1 depends on the alloys used and the geometric and / or process-technical conditions of the respective extrusion device.

In 3 this is from the coextruded cathodically protected compression block 1 shaped tube profile 2 shown in a perspective view, wherein the outer wall of the tubular profile 2 from the shell 1.1 of the pressing block 1 and the inner wall of the pipe profile 2 from the core 1.2 were formed.

A manufactured by the process according to the invention tube profile 2 can be installed particularly preferred in corrosion loaded installation locations, since by the cathodic protection a function of the pipe profile 2 comparatively long-term.

Particularly suitable pipe profiles produced in this way are 2 for use in vehicle construction, for example as an air conditioning line, coolant line and transmission oil line.

LIST OF REFERENCE NUMBERS

1

press block

1.1

shell

1.2

core

1.3

preliminary hole

2

tube profile

3

contraption

3.1

pickup

3.2

press die

3.3

die

3.4

lubricant

3.5

Hydrostatic medium

3.6

poetry

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1433544 B1 [0003]

Claims (6)

Process for producing a cathodically protected pipe profile ( 2 ), characterized in that a pressing block ( 1 ) with an electrochemically non-noble outer shell ( 1.1 ) and an electrochemically noble inner core ( 1.2 ) is coextruded and then from the compression block ( 1 ) the pipe profile ( 2 ) is formed in an extrusion process. Method according to claim 1, characterized in that the pressing block ( 1 ) is coextruded from at least two aluminum alloys. Method according to claim 1 or 2, characterized in that the coextruded pressing block ( 1 ) is first perforated perpendicular to the cross-sectional area. Method according to one of the preceding claims, characterized in that the extrusion process is carried out at a pressing temperature below 600 ° Celsius. Method according to one of the preceding claims, characterized in that the tube profile ( 2 ) is formed in a hydrostatic extrusion process. Method according to one of claims 1 to 4, characterized in that the tube profile ( 2 ) is formed in a direct or indirect extrusion process.

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