EP0962267A2 - Method of fabrication of composite metallic tubes, composite tube and its use - Google Patents

Abstract

A metal strip with a coating of noble metal on at least one side is displaced in a drawing unit (1) with a stationary mandrel (4) in such a way that the coated strip side is formed into the inner surface of a resulting tubular element (12). The latter is inserted into an outer pipe (20), and the resulting assembly is drawn to produce a compound pipe (22) with required final dimensions. An Independent claim is also included for a compound pipe formed by the method which has an inner coating of noble metal. Such a pipe is applied to transmit by reflection, at least a part the radiation falling onto its inner surface.

Description

The invention relates to a method for producing a composite pipe made of metal, the one having a tubular insert encased by an outer seamless tube, insert and outer tube telescopically inserted and then pressed together radially by pulling be, as well as a method for producing a composite pipe made of metal, which by Pulling is compressed radially; the invention further relates to those produced by the processes Composite pipes and the use of such composite pipes.

EP 0 445 904 A2 describes a method for producing a thick-walled metal High-pressure pipe is known, in which two different cross-sectional dimensions Front tubes telescoped and then radially compressed by cold drawing become; the forming is preferably carried out by drawing with an internal tool, in which the wall thickness reduction, in particular of the inner tube, has a high proportion on the respective total deformation, with the pre-tubes in the work-hardened state can be pushed into one another with little play and the double-wall pipe thus produced initially heat treated and then cold drawn at least once; after this The final cold draft is followed by a final heat treatment, the one after the first heat treatment of the double wall pipe produced following the first cold drawing as a pulling with an internal tool is carried out. The production of such a composite pipe proves to be problematic especially in the miniature range, with the inside diameter being, for example 2.5 mm and the outer diameter should be 4 mm; in particular it turns out as problematic to provide the inner tube with an additional coating, for example can perform a function for guiding radiation by means of reflection, as it does is known for example from DE 36 05 737 A1. In practice, for example, this would be too a relatively expensive subsequent galvanization of the inner surface of the Composite pipe run.

From DE-PS 597 120 a device for producing tubes from sheet metal strips is known, in which the sheet is drawn through a die through a cylindrical mandrel; the The die is designed such that the sheet - starting from its longitudinal center line - progressively is bent to the diameter of the mandrel.

Furthermore, DE 36 30 625 C2 describes a method for producing an interior with a Zinc-coated pipe known for use in the refrigeration and automotive industries, in which a sheet metal strip is galvanized on one side and then to a slotted tube internal zinc layer is deformed; then this slotted tube is used of direct current or low frequency current between a welding roller and a rotating one If the welding zone is sufficiently flushed, the welding electrode is sealed with inert gas.

The object of the invention is to produce composite pipes with a small diameter of for example, 2 to 10 mm and a length of 0.5 to 6 m; additionally should the tubes have a reflective inner surface, for example for guiding the radiation of infrared radiation by reflecting part of the radiation can; In addition, a composite pipe with increased stability and seamlessly closed Outer jacket can be specified.

in einem zweiten Schritt wird der als rohrförmige Einlage geformte Rohling mit Beschichtung aus Edelmetall in das äußere Rohr eingeschoben;

weiterhin werden in einem dritten Schritt die ineinander geschobenen Rohre zusammen mit jeweils einem Ende in den Ziehschlitten eingespannt und mittels Ziehmatrize mit feststehendem Innendorn gemeinsam auf Endmaß gezogen, wobei durch radiales Zusammenpressen das äußere Rohr und die rohrartige Einlage über Preß-Sitz miteinander verbunden werden.

The object is achieved for a first method in that, in a first step, a metal strip which has a coating of noble metal on at least one strip side is guided in the pulling device with a fixed inner mandrel in such a way that the coated strip side is the inner surface of the surface to be created forms a tubular insert, the metal strip being clamped at one end in a pulling slide which is movable relative to the pulling device and bent by moving the pulling slit to the tubular insert, the width of the strip corresponding at least approximately to the central circumference of the tubular insert;

in a second step , the blank shaped as a tubular insert with a coating of precious metal is inserted into the outer tube;

Furthermore, in a third step, the tubes that are pushed into each other are clamped together with one end in each case in the drawing slide and are pulled together to the final dimension by means of a drawing die with a fixed internal mandrel, the outer tube and the tubular insert being connected to one another by a press fit by means of radial compression.

The particularly simple and inexpensive manufacturing process has proven to be particularly advantageous, at the same time a high stability of the composite pipe is achieved.

In a preferred embodiment of the method, the tubular insert becomes the first step formed into an insert tube so that its tubular jacket is almost closed Has a gap along the longitudinal axis of the pipe; here it proves to be advantageous that due to the almost closed gap practically no loss of attenuation in the transmission of Radiation occurs by means of reflection on the coating of the inside of the pipe, if used intended for temperature measurement according to DE 36 05 737 is.

In the first step, a metal strip with a thickness in the range of 0.1 to 0.8 mm and one Width in the range of 6 to 30 mm bent into an insert tube, the second step being the tubular insert with a length in the range of 0.5 m to 6 m into the already as blank prefabricated, seamless outer tube is inserted; the inside diameter of the outside The pipe is slightly larger than the outside diameter of the pipe to be inserted Insert tube.

This is a relatively simple handling, which is advantageous can also be automated by simple professional measures.

A metal strip is used in the process, which has a coating on at least one side of the strip made of precious metal - preferably gold - with the band in the pulling device is carried out that the coated hinge side the later inner surface of the to be created forms tubular insert.

It proves to be particularly advantageous that an already prefabricated one with a precious metal / gold coating provided metal band can be used, which without later additional galvanic processes are already required for optimal reflection properties Surface. A relatively economical consumption of Achieve precious metal in the coating process. The coating can be done by electroplating, Roll cladding or sputtering - preferably on one side - can be applied.

In an advantageous embodiment of the third method step, the diameter is both the tubular insert and the outer jacket tube by 5 to 50 percent - preferably by 10 to 30 percent - reduced; due to the radial pressure, an optimal Achieve the surface of the precious metal or gold coating of the insert tube.

This enables the composite pipe to be optimally stable with an optimum optical quality advantageously combine.

The task is for a second method of manufacturing a composite pipe from metal, which is radially compressed by pulling, solved in that a metal band with at least a strip side coated with precious metal in a drawing die of a drawing device inserted with a fixed internal mandrel, with one end in one opposite the drawing device movable slide and clamped by moving the slide to one Compound pipe is bent with an almost closed longitudinal gap, the width of the band corresponds at least approximately to the average circumference of the tubular insert and the metal strip is guided in the pulling device so that the coated side of the strip is the inner surface of the composite pipe to be created. In the second method, too Coating of the metal strip is applied by electroplating, roll cladding or sputtering become.

In a preferred embodiment of the second method, a metal strip with a thickness is used in the range of 0.1 to 0.8 mm and a width in the range of 6 to 30 mm to the composite pipe bent; the composite pipe is preferably drawn up to a length of 6 m.

The second method proves to be advantageous in terms of good surface quality Inside of the pipe and on the cost-effective production of the composite pipe.

The task is for a composite pipe consisting of an insert tube and an outer, seamless Jacket tube which by a drawing process according to the first method (according to claims 1 to 5) are radially compressed into a single composite tube, solved by the fact that the insert tube has an almost closed gap running along the tube axis.

In an advantageous embodiment of the composite pipe, the inside diameter is in the range from 1.5 to 9 mm and its outer diameter in the range from 2 to 10 mm; the inner Coating with precious metal or gold has a thickness of at least 0.1 µm, whereby the optical quality of the reflective coating by the one carried out in the third step Drawing process with radial pressure can be improved considerably. As a material for the tubular Inlay (insert tube) are non-ferrous metals (brass or copper), precious metal or Stainless steel proved to be particularly suitable; as a material for the outer, seamless tube Non-ferrous metals (copper or brass) or stainless steel are particularly suitable are relatively inexpensive materials.

The embodiment of a composite pipe manufactured according to claims 6 to 9 is proportional inexpensive to manufacture; it is in particular for guiding radiation by means of reflection suitable on the inner surface of the composite pipe.

The task becomes with regard to the use of the composite pipe for the transmission of radiation along the tube axis by reflection of at least part of the radiation on the inner Surface of the composite pipe released; in a preferred use the composite pipe used for the transfer of heat radiation for temperature measurement as it is known from DE 36 05 737 A1.

A major advantage of the coating containing precious metal on the inside of the composite pipe can be seen in the constant, temperature-independent reflection property.

Figur 1a zeigt ausschnittsweise im Längsschnitt einen Teil einer Ziehvorrichtung, der ein Metallband als Vormaterial zur Bildung einer rohrförmigen Einlage bzw. eines Verbundrohres zugeführt wird;

Figur 1b zeigt einen Querschnitt durch die rohrförmige Einlage bzw. das Verbundrohr gemäß Schnittebene AA (nach Figur 1a), wobei die Innenseite mit einer Beschichtung versehen ist;

Figur 1c zeigt eine rohrförmige Einlage im Querschnitt entlang der Schnittebene AA, wobei diese jedoch keine innere Beschichtung aufweist;

Figur 2a zeigt eine der Figur 1a entsprechende Ziehvorrichtung zur Bildung eines Verbundrohres aus der rohrförmigen Einlage und einem aufgeschobenen äußeren nahtlosen Mantelrohr;

Figur 2b zeigt einen vergrößerten Querschnitt durch das Verbundrohr entlang der Schnittebene AA (nach Figur 2a);

Figur 2c zeigt die im Prinzip bekannte Strahlungsführung mittels eines mit innerer Reflexionsschicht versehenen Verbundrohres, wobei die Strahlungsführung bereits in der DE 36 05 737 A1 beschrieben ist.

The subject matter of the invention is explained in more detail below with reference to FIGS. 1a, 1b, 1c and 2a, 2b and 2c.

FIG. 1a shows a detail in longitudinal section of a part of a drawing device, to which a metal strip is fed as a starting material for the formation of a tubular insert or a composite pipe;

FIG. 1b shows a cross section through the tubular insert or the composite pipe according to section plane AA (according to FIG. 1a), the inside being provided with a coating;

Figure 1c shows a tubular insert in cross section along the section plane AA, but this has no inner coating;

FIG. 2a shows a drawing device corresponding to FIG. 1a for forming a composite tube from the tubular insert and an outer seamless jacket tube pushed on;

Figure 2b shows an enlarged cross section through the composite pipe along the section plane AA (according to Figure 2a);

FIG. 2 c shows the radiation guidance known in principle by means of a composite tube provided with an inner reflection layer, the radiation guidance already being described in DE 36 05 737 A1.

According to FIG. 1a, the pulling device 1 partially shown has one along the pulling axis 3 arranged mandrel 4, which by means of mandrel rod 5 and mandrel holder 6 in the drawing device 1 is positioned stationary; In the inlet area of the metal strip 2 there is a strip guide 11 provided, in the direction of movement of the metal strip indicated by arrow 16 2 is followed by the conically shaped inlet area 7 of the drawing die 8, by means of the die holder 9, 10 is positioned stationary on the pulling device 1; with the help of mandrel 4 and that surrounds it at a distance (distance is matched to the thickness of the metal strip) Pulling die 8, the metal strip 2 is bent into a tube or tubular insert 12. The part of the preliminary material that has already been designed as a tubular insert is on its front end 13 clamped in the collet 14 of a slide 15. The direction of transport the driven by means not shown drive (chain drive, hydraulic drive) Drawing carriage 15 extends along the drawing axis 3. Metal strip 2 is located as a solid or coated primary material in one for a variety of drawing processes sufficient quantity on a supply spool 17, of which it is produced in batches (corresponding to the tube length) is handled. By pulling in the direction of arrow 18, the slide is 15 advanced so far that there is a length range between the drawing slide 15 and the die 8 from approx. 0.5 m to 6 m for the blank of the insert tube or the tubular insert 12 results. Figure 1a is for the sake of a better overview in a compressed along the longitudinal axis Form shown, so that this figure is by no means to be regarded as to scale; the after Existing tubular insert 12 or insert tube 12 leaving the die 8 is in cross section shown along the section plane AA in Figure 1b, this figure on a tubular Insert 12 is directed with applied surface coating 19; the almost closed Longitudinal gap is designated by number 21; is preferred as a surface coating Gold provided, for example, for optimal reflection of the tubular inlay or to allow radiation penetrating into the later composite pipe, provided the composite pipe is used for pyrometric temperature measurement.

The embodiment according to FIG. 1b is also suitable as a composite pipe without an additional outer pipe Casing, the manufacture of which is described in claims 7 to 9; such an arrangement is particularly suitable for pyrometric temperature measurement.

However, it is also possible to dispense with the surface coating of the strip material, as can be seen from FIG. 1c; Such an uncoated insert tube can be used as a raw material composite pipe to be created with closed outer jacket for the transmission of a Medium, for example gas or used as a channel for a cooling medium; as beneficial is the use of a material that is resistant to the respective medium to watch.

FIG. 2a again shows drawing device 1 with drawing mandrel 4, mandrel bar 5 and mandrel holder 6, drawing mandrel 4 from a die 8 in die holder 9 at a distance (distance is on the Wall thicknesses or final dimensions of the composite pipe to be created) is. The raw material is now inserted into an outer seamless jacket tube 20 Insert tube 12 is provided, both tubes with their front ends in the collet 14 of the slide 15 are clamped. By moving the slide 15 along the Drawing axis 3 in the direction of the arrow 18, both tubes in the radial direction to the drawing axis 3 seen compressed so that a composite tube 22 the area of the die 8 in Arrow direction 18 leaves; when pressed together in the radial direction on the mandrel 4 the surface coating 19 strongly smoothed that an optimally reflective interior Surface is reached. The surface coating is according to FIG. 2b with reference number 19 featured.

Figure 2c shows a longitudinal section of the finished composite pipe; according to Figure 2c occurs direct Radiation 25 along the tube axis 23, which passes through the composite tube 22 without reflection; Scattered radiation 26 (as described, for example, on the basis of DE 36 05 737 A1 on the other hand, occurs outside the tube axis 23 and is repeated several times on the surface coating 19 reflected within the tube and occurs at the tube end 24 in a not shown here Detector device; A pyrometer, for example, can be used as the detector device suitable for non-contact temperature measurement.

Claims (19)

A method for producing a composite pipe made of metal, which has a tubular insert encased by an outer, seamless tube, the insert and the outer tube being telescopically inserted and then radially compressed by pulling, characterized in that in a first step a metal strip , which has a coating of precious metal on at least one strip side, is guided in the pulling device with a fixed inner mandrel in such a way that the coated strip side forms the inner surface of the tubular insert to be produced, the metal strip being clamped at one end in a pulling slide movable relative to the pulling device and is bent by moving the drawing slide to the tubular insert, the width of the band at least approximately corresponding to the central circumference of the tubular insert, that in a second step , the blank shaped as a tubular insert is inserted into the outer tube and that in a third step the nested tubes are clamped together with one end in each case in the drawing slide and are pulled together to the final dimension using a drawing die with a fixed internal mandrel, the outer tube and tubular insert being connected to one another by a press fit by radial compression. A method according to claim 1, characterized in that in the first step the tubular Insert is formed as an insert tube, the tube jacket of which is almost closed Gap along the longitudinal axis of the tube. A method according to claim 1 or 2, characterized in that in the first step Metal tape with a thickness in the range of 0.1 to 0.8 mm and a width in the range is bent from 6 to 30 mm to form an insert tube. Method according to one of claims 1 to 3, characterized in that in the second Step the tubular insert with a length in the range of 0.5 m to 6 m into the outer Tube is inserted. Method according to one of claims 1 to 4, characterized in that in the third Step the diameter of both the tubular insert and the jacket tube by 5 can be reduced by up to 50%. Process for producing a composite pipe made of metal, which is radially compressed by drawing is characterized in that a metal band with a precious metal coated strip side in a drawing die of a pulling device with a fixed Inserted inner mandrel, with one end in a movable relative to the drawing device Pulling sled clamped and by moving the pulling sled to one Compound tube is bent with an almost closed longitudinal gap, the width of the Band corresponds at least approximately to the average circumference of the tubular insert and the metal strip is guided in the pulling device so that the coated Hinge side forms the inner surface of the composite pipe to be created. A method according to claim 6, characterized in that a metal strip with a thickness in the range of 0.1 to 0.8 mm and a width in the range of 6 to 30 mm to that Composite pipe is bent. A method according to claim 6 or 7, characterized in that the composite pipe with a length of up to 6 m. Method according to one of claims 1 to 8, characterized in that the drawing process or the pulling operations take place at room temperature. Composite pipe manufactured according to one of claims 1 to 9, characterized in that provide the inner surface of the composite pipe with a coating of precious metal is. Composite pipe according to claim 10, characterized in that the coating of the composite pipe is made of gold. Composite pipe according to claim 10 or 11, characterized in that the coating has a thickness in the range of at least 0.1 µm. Composite pipe manufactured according to one of claims 1 to 5, characterized in that the insert tube has an almost closed gap running along the tube axis having. Composite pipe according to claim 13, characterized in that its inner diameter in Range of 1.5 to 9 mm and its outer diameter in the range of 2 to 10 mm lies. Composite pipe according to claim 13 or 14, characterized in that as a material for the tubular insert of non-ferrous metal, in particular brass or copper, precious metal or Stainless steel is used. Composite pipe according to one of claims 13 to 15, characterized in that as Material for the outer tube stainless steel or non-ferrous metal, especially copper or brass, is used. Composite pipe manufactured according to one of claims 6 to 9, characterized in that its inner diameter in the range of 1.5 to 9 mm and its outer diameter in Range is 2 to 10 mm. Use of a composite pipe according to one of claims 10 to 17 for transmission radiation along the tube axis by reflecting at least a portion of the radiation on the inner surface of the composite pipe. Use of a composite pipe according to claim 18 for the transmission of infrared radiation for temperature measurement.

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