EP0481902A1 - Process for improving the pliability of hardened copper tubes by dynamic thermal treatment - Google Patents

Process for improving the pliability of hardened copper tubes by dynamic thermal treatment Download PDF

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Publication number
EP0481902A1
EP0481902A1 EP91420365A EP91420365A EP0481902A1 EP 0481902 A1 EP0481902 A1 EP 0481902A1 EP 91420365 A EP91420365 A EP 91420365A EP 91420365 A EP91420365 A EP 91420365A EP 0481902 A1 EP0481902 A1 EP 0481902A1
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Prior art keywords
tubes
hard
copper
temperature
tube
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German (de)
French (fr)
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EP0481902B1 (en
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Abbas Bohran Tavakoli
Patrick Boisgontier
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Trefimetaux SAS
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Trefimetaux SAS
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

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  • the invention relates to a method for improving the workability of drawn, hard copper tubes.
  • Hard copper tubes are mainly used in sanitary installations. Their rate of use of pressurized sanitary water inside homes today reaches 90%.
  • the expression "hard copper tubes” includes copper tubes or copper alloys capable of being used inter alia in sanitary installations. The implementation of these tubes requires bending operations which are carried out either on site with manual benders, or in the workshop with automatic benders with pneumatic or hydraulic control.
  • Straight copper tubes are most often produced from a large diameter tubular blank obtained by hot spinning, followed successively by cold rolling and drawing to final dimensions without intermediate annealing.
  • the finished hard tubes have a very low residual ductility and consequently the bending operation risks generating cracks, incipient fractures and even breakages.
  • These curves each have an inflection point of abscissa T Rm and T A% respectively, these inflection points also being very close to the point of intersection of the two curves, of abscissa T i .
  • All copper alloys exhibit characteristic softening curves, generally shifted towards high temperatures. This difference is, all other things being equal, essentially due to the presence of the elements of addition.
  • the first object of the invention is a method for increasing the elongation (A%) of the hard copper tubes to a sufficient level so that the defects resulting from the bending of hard copper tubes according to the prior art do not appear. , and that, while respecting the current standards or in preparation on hard copper tubes.
  • Another object of the invention is a reliable and economical manufacturing process for bendable hard copper tubes without the appearance of defects and giving reproducible results whatever the manufacturing methods of the hard copper tubes used.
  • the method for improving the workability of hard copper or copper alloy tubes comprises a heat treatment of said hard tubes and is characterized in that the hard tubes are continuously scrolled through a heating device allowing bring the tube to a treatment temperature between T Rm -50 ° C and T Rm -100 ° C for a time between 0.1 and 10 seconds, T Rm being the temperature (° C) at which the curve d softening of said copper or copper alloy, which gives the tensile strength Rm as a function of temperature, has an inflection point (this temperature is called half-softening temperature).
  • the heating device is an induction furnace having sufficient power to allow the scrolling of tubes at a speed between 30 and 250 m / min.
  • the geometry of the inductor choose the power and the frequency to carry out the invention.
  • the treatment temperature is between 380 and 415 ° C.
  • the Applicant has observed that it is advantageous to control the atmosphere inside and outside the hard tubes during the short period of time when they are brought to high temperature.
  • the external gas atmosphere of the hard tubes during heating consists of a gas neutral while that inside the hard tubes contains oxygen.
  • the gaseous atmosphere inside the hard tubes can be air or a mixture of air and oxygen in all proportions, which can optionally be circulated. It is thus possible on the one hand to greatly reduce the content of lubricant residues and on the other hand to form a thin layer of Cu2O on the inner surface of the tube, all of which improve corrosion resistance.
  • Figure 2 gives the diagram of the installation. It includes a supply of straight copper tube (9), straight with means (7) to ensure a regular advancement of the tube and at a predetermined speed, the passage of the tube in an induction heating device comprising the induction furnace (1 ) and the generator (6), the passage through a cooling device (2) allowing the temperature of the tube to drop rapidly (quenching).
  • the tube was made to circulate in an enclosure (3) provided with a circulation of nitrogen.
  • the installation may include, as shown diagrammatically in FIG. 2, a hardness control device (5) which continuously measures, during travel, the hardness of the treated tube.
  • a hardness control device (5) which continuously measures, during travel, the hardness of the treated tube.
  • it is advantageous to control the residence time and / or the treatment temperature to the hardness measured continuously for example using a device (10) controlling the installation automatically according to predetermined set values and according to parameter values such as hardness (shown diagrammatically by sensor 5) or temperature (sensor not shown in the figure), which further contributes to improving reliability and the reproducibility of the process.
  • the installation may include a device (8) for cutting hard, straight tubes of predetermined constant length.
  • the properties of the hard tubes treated according to the invention were measured: Bending tests were also carried out on the two crowns before and after the treatment of the invention with a hydraulic and automatic bender making it possible to make hangers of radius (with neutral fiber) of 52.5 mm, 49 mm (standard value ), 42 mm, 35 mm and 28 mm. These radii correspond respectively to the bending ratios (bending radius / tube diameter) 3.75, 3.5, 3.0, 2.5 and 2.0.
  • FIG. 1 is a diagram representing the qualitative development of the breaking load Rm (y-axis on the left) as a function of the temperature T (softening curve of the alloy), and the qualitative development of the elongation at break A% (y-axis on the right) as a function of temperature.
  • FIG. 3 is a diagram which translates the results of workability, with on the ordinate the percentage of bending tests recognized as good and on the abscissa the ratio "bending radius / diameter of the tube". The smaller this ratio, the more severe the bending.
  • Curve A corresponds to the tubes before the treatment according to the invention.
  • Curve B corresponds to the tubes obtained according to the invention, with a treatment at 400 ° C.
  • Curve C corresponds to the tubes having undergone a treatment at 300 ° C. (outside the field defined by the invention).

Abstract

Process for improving the bendability of hard copper or copper alloy tubes comprising a heat treatment of the said hard tubes, characterised in that hard tubes are passed continuously through a heating device allowing the tube to be heated to a processing temperature of between TRm-50 DEG C and TRm-100 DEG C for a period of between 0.1 and 10 seconds, TRm being the temperature ( DEG C) at which the softening curve of the said copper or copper alloy, which gives the breaking load Rm as a function of temperature, exhibits an inflexion point. <IMAGE>

Description

DOMAINE DE L'INVENTIONFIELD OF THE INVENTION

L'invention concerne un procédé destiné à améliorer la cintrabilité de tubes de cuivre étirés, à l'état dur.The invention relates to a method for improving the workability of drawn, hard copper tubes.

RAPPEL DE L'ART ANTERIEURRECALL OF THE PRIOR ART

Les tubes de cuivre à l'état dur sont utilisés essentiellement dans les installations sanitaires. Leur taux d'utilisation en eau sanitaire sous pression à l'intérieur des habitations atteint aujourd'hui 90%.
Dans la présente demande l'expression "tubes de cuivre durs" comprend les tubes de cuivre ou alliages de cuivres susceptibles d'être utilisés entre autres dans les installations sanitaires.
La mise en oeuvre de ces tubes nécessite des opérations de cintrage qui s'effectuent soit sur chantier avec des cintreuses manuelles, soit en atelier avec des cintreuses automatiques à commande pneumatique ou hydraulique.Hard copper tubes are mainly used in sanitary installations. Their rate of use of pressurized sanitary water inside homes today reaches 90%.
In the present application, the expression "hard copper tubes" includes copper tubes or copper alloys capable of being used inter alia in sanitary installations.
The implementation of these tubes requires bending operations which are carried out either on site with manual benders, or in the workshop with automatic benders with pneumatic or hydraulic control.

Les tubes de cuivres droits sont fabriqués le plus souvent à partir d'une ébauche tubulaire de gros diamètre obtenue par filage à chaud, suivi successivement par un laminage à froid et étirage jusqu'aux dimensions finales sans recuits intermédiaires.
De ce fait, les tubes finis durs présentent une ductilité résiduelle très faible et par conséquent l'opération de cintrage risque de générer des criques, des amorces de rupture et même des casses.Straight copper tubes are most often produced from a large diameter tubular blank obtained by hot spinning, followed successively by cold rolling and drawing to final dimensions without intermediate annealing.
As a result, the finished hard tubes have a very low residual ductility and consequently the bending operation risks generating cracks, incipient fractures and even breakages.

Par ailleurs, l'emploi de tubes à l'état recuit est exclu en raison de leur ductilité excessive qui conduit à des déformations inesthétiques dans le cas d'installations où les tubes sont apparents.Furthermore, the use of tubes in the annealed state is excluded because of their excessive ductility which leads to unsightly deformations in the case of installations where the tubes are visible.

Les tubes de cuivre utilisés dans les installations sanitaires sont généralement des tubes durs en cuivre désoxydés au phosphore tels que le Cub₂ (Cu-DLP) et le Cub₁ (Cu-DHP), dont les valeurs moyennes des caractéristiques mécaniques sont les suivantes:

  • * charge à la rupture (Rm) = 450 MPa
  • * limite élastique (R0,2) = 430 MPa
  • * allongement à la rupture sur une base de 50 mm (A50mm%) = 5 %
The copper tubes used in sanitary installations are generally hard copper tubes deoxidized with phosphorus such as Cub₂ (Cu-DLP) and Cub₁ (Cu-DHP), the average values of the mechanical characteristics of which are as follows:
  • * breaking load (Rm) = 450 MPa
  • * elastic limit (R 0.2 ) = 430 MPa
  • * elongation at break on a base of 50 mm (A 50mm %) = 5%

Par ailleurs, il existe des normes pour les tubes durs de cuivre :

  • selon la norme AFNOR (NF A51-120), les tubes durs (état H14) doivent avoir les propriétés suivantes :
    • * Rm ≧ 310 MPa
    • * A% ≧ 5%
  • selon le projet de norme européenne (EN 133/22), les tubes durs doivent avoir les propriétés suivantes :
    • * Rm ≧ 290 MPa
    • * A% ≧ 3%
    • * HV₅ ≧ 100 (dureté)
In addition, there are standards for hard copper tubes:
  • according to AFNOR standard (NF A51-120), hard tubes (state H14) must have the following properties:
    • * Rm ≧ 310 MPa
    • * A% ≧ 5%
  • according to the draft European standard (EN 133/22), hard tubes must have the following properties:
    • * Rm ≧ 290 MPa
    • * A% ≧ 3%
    • * HV₅ ≧ 100 (hardness)

Il est connu qu'une augmentation de l'allongement traduit une amélioration de la ductilité qui favorise la cintrabilité des tubes en général.
On connait aussi les effets des traitements thermiques sur les propriétés mécaniques telles que la charge à la rupture (Rm) et l'allongement (A%), typiquement représentés par le graphique de la figure 1 qui montre l'évolution de la charge à la rupture (Rm) et de l'allongement (A%) en fonction de la température (T), T étant en abscisse et Rm,A% en ordonnée.It is known that an increase in elongation translates into an improvement in ductility which favors the cointrability of tubes in general.
We also know the effects of heat treatments on mechanical properties such as the load at break (Rm) and elongation (A%), typically represented by the graph in Figure 1 which shows the evolution of the load at rupture (Rm) and elongation (A%) as a function of temperature (T), T being on the abscissa and Rm, A% on the ordinate.

La courbe Rm = f(T) (appelé aussi dans la suite de la description "courbe d'adoucissement") tout comme la courbe A% = F(T) a une forme en "S" (voir figure 1). Ces courbes ont chacune un point d'inflexion d'abcisse TRm et TA% respectivement, ces points d'inflexion étant également très voisins du point d'intersection des deux courbes, d'abscisse Ti.
Tous les alliages de cuivre présentent des courbes d'adoucissement caractéristiques, généralement décalées vers les hautes températures. Ce décalage est, toutes choses égales par ailleurs, essentiellement dû à la présence des éléments d'addition.The curve Rm = f (T) (also called in the following description "softening curve") just like the curve A% = F (T) has an "S" shape (see FIG. 1). These curves each have an inflection point of abscissa T Rm and T A% respectively, these inflection points also being very close to the point of intersection of the two curves, of abscissa T i .
All copper alloys exhibit characteristic softening curves, generally shifted towards high temperatures. This difference is, all other things being equal, essentially due to the presence of the elements of addition.

D'une manière générale, ce type de graphique montre que la charge à la rupture et l'allongement varient inversement l'un de l'autre et qu'il existe en fait 3 domaines de températures :

  • domaine noté "A" : Rm élevé et A% faible (métal écroui)
  • domaine noté "T" : domaine transitoire à forte instabilité
  • domaine noté "B" : Rm faible et A% élevé (métal recristallisé)
In general, this type of graph shows that the breaking load and the elongation vary inversely from each other and that there are in fact 3 temperature ranges:
  • domain marked "A": high Rm and A% low (work hardened metal)
  • domain noted "T": transient domain with high instability
  • domain noted "B": Low rm and A% high (recrystallized metal)

Pour l'homme du métier, un traitement thermique de tubes de cuivre durs visant à améliorer la ductilité tout en conservant l'état dur serait à proscrire dans les zones T et B. En effet, dans la zone T, les transitions sont d'une part trop brutales (dRm/dT et dA%/dT trop élevés) et donc difficilement maîtrisables industriellement, et ne permettent pas d'avoir simultanément Rm et A% elevés. Quant à la zone B, elle est exclue puisqu'elle correspond au domaine d'obtention de tubes recuits ayant une charge à la rupture "faible" et un allongement "élevé". Les traitements connus à ce jour effectués dans la zone A ont conduit à certains résultats. Ainsi, la demande française N° 83 09942 au nom de la demanderesse décrit un procédé d'amélioration de la cintrabilité de tubes de cuivre durs à l'aide d'un traitement thermique statique de recuit partiel intéressant uniquement la zone corticale du tube, effectué entre 150 et 350°C et pendant une durée comprise entre 5 minutes et 24 heures. Les résultats obtenus après traitement dans un four à air chaud étaient les suivants :

  • * Rm = entre 390 et 420 MPa
  • * A% = entre 4 et 6%
Ces résultats conduisaient à une amélioration significative de la cintrabilité, mais, outre que ce procédé n'était qu'une solution partielle au problème de la cintrabilité puisque ce procédé réduisait le nombre de défauts apparus lors du cintrage mais sans les éliminer totalement, ce procédé avait aussi le défaut d'être relativement long et coûteux, d'être, à l'usage, peu reproductible, et en particulier d'être très sensible au procédé d'obtention des ébauches tubulaires de départ, ce qui a conduit à limiter fortement voire à abandonner son application industrielle.For those skilled in the art, heat treatment of hard copper tubes aimed at improving ductility while retaining the hard state would be to be avoided in zones T and B. Indeed, in zone T, the transitions are of a part too brutal (dRm / dT and dA% / dT too high) and therefore difficult to control industrially, and do not allow to have simultaneously Rm and A% high. As for zone B, it is excluded since it corresponds to the field of obtaining annealed tubes having a "low" breaking load and a "high" elongation. The treatments known to date carried out in zone A have led to certain results. Thus, French application N ° 83,09942 in the name of the applicant describes a process for improving the cintrability of copper tubes hard using a static partial annealing heat treatment involving only the cortical region of the tube, performed between 150 and 350 ° C and for a period of between 5 minutes and 24 hours. The results obtained after treatment in a hot air oven were as follows:
  • * Rm = between 390 and 420 MPa
  • * A% = between 4 and 6%
These results led to a significant improvement in bendability, but, besides that this method was only a partial solution to the problem of bendability since this method reduced the number of defects appeared during bending but without eliminating them completely, this method also had the defect of being relatively long and costly, of being, in use, not very reproducible, and in particular of being very sensitive to the process for obtaining the starting tubular blanks, which led to greatly limiting even to abandon its industrial application.

OBJET DE L'INVENTIONOBJECT OF THE INVENTION

L'invention a pour premier objet un procédé permettant d'augmenter l'allongement (A%) des tubes de cuivre durs à un niveau suffisant pour que n'apparaîssent pas les défauts résultant du cintrage de tubes de cuivre durs selon l'art antérieur, et cela, tout en respectant les normes actuelles ou en préparation sur les tubes de cuivre durs.The first object of the invention is a method for increasing the elongation (A%) of the hard copper tubes to a sufficient level so that the defects resulting from the bending of hard copper tubes according to the prior art do not appear. , and that, while respecting the current standards or in preparation on hard copper tubes.

Un autre objet de l'invention est un procédé de fabrication fiable et économique de tubes de cuivre durs cintrables sans apparition de défauts et donnant des résultats reproductibles quels que soient les procédés de fabrication des tubes de cuivre durs utilisés.Another object of the invention is a reliable and economical manufacturing process for bendable hard copper tubes without the appearance of defects and giving reproducible results whatever the manufacturing methods of the hard copper tubes used.

DESCRIPTION DE L'INVENTIONDESCRIPTION OF THE INVENTION

Selon l'invention, le procédé d'amélioration de la cintrabilité de tubes de cuivre ou alliage de cuivre durs comprend un traitement thermique desdits tubes durs et est caractérisé en ce qu'on fait défiler en continu des tubes durs dans un dispositif de chauffage permettant de porter le tube à une température de traitement comprise entre TRm-50°C et TRm-100°C pendant une durée comprise entre 0,1 et 10 secondes, TRm étant la température (°C) à laquelle la courbe d'adoucissement dudit cuivre ou alliage de cuivre, qui donne la charge à la rupture Rm en fonction de la température, présente un point d'inflexion (cette température est appelée température de demi-adoucissement).According to the invention, the method for improving the workability of hard copper or copper alloy tubes comprises a heat treatment of said hard tubes and is characterized in that the hard tubes are continuously scrolled through a heating device allowing bring the tube to a treatment temperature between T Rm -50 ° C and T Rm -100 ° C for a time between 0.1 and 10 seconds, T Rm being the temperature (° C) at which the curve d softening of said copper or copper alloy, which gives the tensile strength Rm as a function of temperature, has an inflection point (this temperature is called half-softening temperature).

Selon une modalité préférée de l'invention le dispositif de chauffage est un four à induction ayant une puissance suffisante pour permettre le défilement de tubes à une vitesse comprise entre 30 et 250 m/min. L'homme du métier peut adapter la géométrie de l'inducteur, choisir la puissance et la fréquence pour réaliser l'invention.According to a preferred embodiment of the invention, the heating device is an induction furnace having sufficient power to allow the scrolling of tubes at a speed between 30 and 250 m / min. Those skilled in the art can adapt the geometry of the inductor, choose the power and the frequency to carry out the invention.

Dans le cas de tubes de cuivre durs en cuivre désoxydé au phosphore Cub₁ ou Cub₂, la température TRm correspondant au point d'inflexion de la courbe d'adoucissement Rm = f(T) est voisine de 470°C (pour un chauffage dynamique par induction), de sorte que la température du traitement selon l'invention est comprise dans ce cas entre 370 et 420°C.
De préférence, la température de traitement est comprise entre 380 et 415°C.In the case of hard copper tubes made of deoxidized copper with phosphorus Cub₁ or Cub₂, the temperature T Rm corresponding to the inflection point of the softening curve Rm = f (T) is close to 470 ° C (for dynamic heating by induction), so that the temperature of the treatment according to the invention is in this case between 370 and 420 ° C.
Preferably, the treatment temperature is between 380 and 415 ° C.

La demanderesse a observé qu'il était avantageux de contrôler l'atmosphère à l'intérieur et à l'extérieur des tubes durs pendant le court laps de temps où ils sont portés à haute température.
Ainsi, de préférence, l'atmosphère gazeuse extérieure des tubes durs pendant le chauffage est constituée d'un gaz neutre alors que celle de l'intérieur des tubes durs contient de l'oxygène. Ainsi, l'atmosphère gazeuse à l'intérieur des tubes durs peut être de l'air ou un mélange d'air et d'oxygéne en toutes proportions, que l'on peut éventuellement faire circuler.
Il est ainsi possible d'une part de diminuer fortement la teneur en résidus de lubrifiant et d'autre part de former une couche mince de Cu₂O sur la surface intérieure du tube, toutes choses qui améliorent la résistance à la corrosion.The Applicant has observed that it is advantageous to control the atmosphere inside and outside the hard tubes during the short period of time when they are brought to high temperature.
Thus, preferably, the external gas atmosphere of the hard tubes during heating consists of a gas neutral while that inside the hard tubes contains oxygen. Thus, the gaseous atmosphere inside the hard tubes can be air or a mixture of air and oxygen in all proportions, which can optionally be circulated.
It is thus possible on the one hand to greatly reduce the content of lubricant residues and on the other hand to form a thin layer of Cu₂O on the inner surface of the tube, all of which improve corrosion resistance.

L'exemple suivant illustre l'invention sans la limiter :The following example illustrates the invention without limiting it:

On a travaillé avec deux couronnes de tubes durs en Cub1. Ces couronnes, désignées par C1 et C2 sont constituées d'environ 1200 m de tubes durs, de 14 mm de diamètre extérieur et de 0,94 mm d'épaisseur. Leur poids est de 400 Kg.We worked with two crowns of hard tubes in Cub1. These rings, designated by C1 and C2, consist of approximately 1,200 m of hard tubes, 14 mm in outside diameter and 0.94 mm thick. Their weight is 400 Kg.

Propriétés mesurées sur ces couronnes :

Figure imgb0001
Dans ce tableau, les valeurs de la charge à la rupture, l'allongement et le carbone résiduel sont données avec un intervalle de confiance à 95%.Properties measured on these crowns:
Figure imgb0001
 In this table, the values of the breaking load, the elongation and the residual carbon are given with a 95% confidence interval.

On a traité les deux couronnes suivant le procédé de l'invention en faisant passer les tubes durs droits dans un four à induction avec les paramètres opératoires suivants :

  • atmosphère à l'intérieur des tubes : air
  • atmosphère à l'extérieur des tubes : azote
  • température visée de traitement : 400°C
  • durée du traitement : 0,8 s
The two crowns were treated according to the process of the invention by passing the straight hard tubes through an induction furnace with the following operating parameters:
  • atmosphere inside the tubes: air
  • atmosphere outside the tubes: nitrogen
  • target treatment temperature: 400 ° C
  • duration of treatment: 0.8 s

La figure 2 donne le schéma de l'installation. Elle comporte une alimentation en tube de cuivre (9) dur, droit avec des moyens (7) pour assurer un avancement régulier du tube et à vitesse prédéterminée, le passage du tube dans un dispositif de chauffage par induction comprenant le four à induction (1) et le générateur (6), le passage dans un dispositif de refroidissement (2) permettant de faire chuter rapidement la température du tube (trempe).
Afin de contrôler l'atmosphère extérieure du tube pendant le traitement thermique, on a fait circuler le tube dans une enceinte (3) munie d'une circulation d'azote.Figure 2 gives the diagram of the installation. It includes a supply of straight copper tube (9), straight with means (7) to ensure a regular advancement of the tube and at a predetermined speed, the passage of the tube in an induction heating device comprising the induction furnace (1 ) and the generator (6), the passage through a cooling device (2) allowing the temperature of the tube to drop rapidly (quenching).
In order to control the outside atmosphere of the tube during the heat treatment, the tube was made to circulate in an enclosure (3) provided with a circulation of nitrogen.

L'installation peut comporter, comme représenté schématiquement sur la figure 2, un dispositif de contrôle de la dureté (5) qui mesure en continu, au défilé, la dureté du tube traité. Comme la dureté varie sensiblement comme la charge à la rupture, il est avantageux d'asservir le temps de séjour et/ou la température de traitement à la dureté mesurée en continu par exemple à l'aide d'un dispositif (10) pilotant l'installation de manière automatique en fonction de valeurs de consigne prédéterminées et en fonction des valeurs des paramètres tels que la dureté (schématisé par le capteur 5) ou la température (capteur non représenté sur la figure), ce qui contribue encore à améliorer la fiabilité et la reproductibilité du procédé.The installation may include, as shown diagrammatically in FIG. 2, a hardness control device (5) which continuously measures, during travel, the hardness of the treated tube. As the hardness varies substantially like the breaking load, it is advantageous to control the residence time and / or the treatment temperature to the hardness measured continuously, for example using a device (10) controlling the installation automatically according to predetermined set values and according to parameter values such as hardness (shown diagrammatically by sensor 5) or temperature (sensor not shown in the figure), which further contributes to improving reliability and the reproducibility of the process.

L'installation peut comporter un dispositif (8) de débitage de tubes durs, droits, de longueur constante prédéterminée.The installation may include a device (8) for cutting hard, straight tubes of predetermined constant length.

On a mesuré les propriétés des tubes durs traités selon l'invention :

Figure imgb0002
On a aussi réalisé des tests de cintrage sur les deux couronnes avant et après le traitement de l'invention avec une cintreuse hydraulique et automatique permettant de faire des cintres de rayon (à la fibre neutre) de 52,5mm, 49 mm (valeur normalisée), 42 mm, 35 mm et 28 mm. Ces rayons correspondent respectivement aux rapports de cintrage (rayon de cintrage/diamètre du tube) 3,75, 3,5, 3,0, 2,5 et 2,0.The properties of the hard tubes treated according to the invention were measured:
Figure imgb0002
 Bending tests were also carried out on the two crowns before and after the treatment of the invention with a hydraulic and automatic bender making it possible to make hangers of radius (with neutral fiber) of 52.5 mm, 49 mm (standard value ), 42 mm, 35 mm and 28 mm. These radii correspond respectively to the bending ratios (bending radius / tube diameter) 3.75, 3.5, 3.0, 2.5 and 2.0.

Le diagramme de la figure 3 résume les résultats : en abscisse est porté le rapport de cintrage (= rayon de cintrage/diamètre du tube) qui varie inversement à la sévérité de cintrage, et en ordonnée est porté le pourcentage de cintrages "bons", c'est à dire ne présentant pas de défaut visible.
Chaque point du diagramme correspond à 300 essais de cintrage.
Le diagramme comporte 3 courbes :

  • la courbe A correspond au tube non traité
  • la courbe B correspond au tube traité selon l'exemple à 400°C.
  • la courbe C résulte d'un essai réalisé à partir des mêmes tubes durs de départ, avec le dispositif de l'invention mais à 300°C, c'est à dire à une température plus basse et en dehors du domaine prévu par l'invention.
The diagram in FIG. 3 summarizes the results: the bending ratio is plotted on the abscissa (= bending radius / tube diameter) which varies inversely with the bending severity, and the percentage of "good" bends is plotted on the ordinate, that is to say having no visible defect.
Each point in the diagram corresponds to 300 bending tests.
The diagram has 3 curves:
  • curve A corresponds to the untreated tube
  • curve B corresponds to the tube treated according to the example at 400 ° C.
  • curve C results from a test carried out using the same hard starting tubes, with the device of the invention but at 300 ° C., that is to say at a lower temperature and outside the range provided by invention.

Ces résultats illustrent tout l'intérêt de l'invention et montrent le progrès considérable que l'invention a permis de réaliser en ce qui concerne la cintrabilité de tubes de cuivre ou alliage de cuivre à l'état dur. Ce progrès est obtenu à l'aide d'un procédé continu, économique, de bonne fiabilité et reproductibilité des résultats, et peu sensible à la manière dont les tubes ont été élaborés, la composition de l'alliage mise à part, qui a, comme cela a déjà été mentionné, une incidence sur la courbe d'adoucissement de l'alliage et donc sur la valeur de TRm.These results illustrate all the advantage of the invention and show the considerable progress which the invention has made possible with regard to the curability of copper tubes or copper alloy in the hard state. This progress is obtained using a continuous, economical process, with good reliability and reproducibility of the results, and little sensitive to the way in which the tubes were produced, the composition apart from the alloy, which has, as already mentioned, an effect on the softening curve of the alloy and therefore on the value of T Rm .

Typiquement, l'invention permet d'obtenir de tubes de cuivre ou alliage de cuivre à l'état dur présentant simultanément :

  • une charge à la rupture élevée supérieure à 360 MPa
  • un allongement élevé, supérieur à 8% entraînant un comportement excellent à la cintrabilité
  • une tenue à la corrosion améliorée d'une part par réduction de la teneur en carbone et d'autre part par formation d'une couche de Cu₂O sur la surface intérieure du tube.
De tels tubes de cuivre à l'état dur, aux performances nettement supérieures aux normes en vigueur, présente le plus grand intérêt à la fois d'un point de vue économique et pour l'utilisateur qui doit mettre en forme les tubes par cintrage.Typically, the invention makes it possible to obtain copper or copper alloy tubes in the hard state simultaneously having:
  • a high breaking load greater than 360 MPa
  • a high elongation, greater than 8%, resulting in excellent behavior at workability
  • improved corrosion resistance on the one hand by reducing the carbon content and on the other hand by forming a layer of Cu₂O on the inner surface of the tube.
Such copper tubes in the hard state, with performances clearly superior to the standards in force, present the greatest interest both from an economic point of view and for the user who has to shape the tubes by bending.

DESCRIPTION DES FIGURESDESCRIPTION OF THE FIGURES

La figure 1 est un diagramme représentant l'évolution qualitative de la charge à la rupture Rm (axe des ordonnées à gauche) en fonction de la température T (courbe d'adoucissement de l'alliage), et l'évolution qualitative de l'allongement à la rupture A% (axe des ordonnées à droite) en fonction de la température.FIG. 1 is a diagram representing the qualitative development of the breaking load Rm (y-axis on the left) as a function of the temperature T (softening curve of the alloy), and the qualitative development of the elongation at break A% (y-axis on the right) as a function of temperature.

La figure 2 schématise une installation pour mettre en oeuvre l'invention qui comporte :

  • des moyens (7) pour assurer le déplacement du tube à vitesse constante contrôlée par le dispositif de commande (10).
  • un dispositif de chauffage par induction comportant un four à induction (1) muni d'une enceinte (3) dans laquelle passe le tube (9) et dans laquelle circule un gaz neutre (4), et d'un générateur (6) rélié au dispositif de commande (10),
  • un dispositif de refroidissement (2) permettant une trempe rapide du tube,
  • un appareil de mesure de la dureté (5) en continu, relié au dispositif de commande (10).
A noter que ne figurent pas sur ce schéma, pour ne pas l'alourdir, les capteurs de température et le dispositif permettant d'introduire ou de faire circuler une atmosphère oxydante à l'intérieur du tube.FIG. 2 diagrams an installation for implementing the invention which comprises:
  • means (7) for moving the tube at a constant speed controlled by the control device (10).
  • an induction heating device comprising an induction furnace (1) provided with an enclosure (3) in which the tube (9) passes and in which a neutral gas circulates (4), and of a generator (6) connected to the control device (10),
  • a cooling device (2) allowing rapid quenching of the tube,
  • a hardness measuring device (5) continuously, connected to the control device (10).
Note that the temperature sensors and the device making it possible to introduce or circulate an oxidizing atmosphere inside the tube do not appear on this diagram, so as not to make it heavier.

La figure 3 est un diagramme qui traduit les résultats de cintrabilité, avec en ordonnée le pourcentage d'essais de cintrage reconnus bons et en abscisse le rapport "rayon de cintrage / diamètre du tube". Plus ce rapport est petit, plus le cintrage est sévère.
La courbe A correspond aux tubes avant le traitement selon l'invention.
La courbe B correspond aux tubes obtenus selon l'invention, avec un traitement à 400°C.
La courbe C correspond aux tubes ayant subi un traitement à 300°C (hors du domaine défini par l'invention).FIG. 3 is a diagram which translates the results of workability, with on the ordinate the percentage of bending tests recognized as good and on the abscissa the ratio "bending radius / diameter of the tube". The smaller this ratio, the more severe the bending.
Curve A corresponds to the tubes before the treatment according to the invention.
Curve B corresponds to the tubes obtained according to the invention, with a treatment at 400 ° C.
Curve C corresponds to the tubes having undergone a treatment at 300 ° C. (outside the field defined by the invention).

Claims (9)

1 - Procédé d'amélioration de la cintrabilité de tubes de cuivre ou alliage de cuivre durs comprenant un traitement thermique desdits tubes durs caractérisé en ce qu'on fait défiler en continu des tubes durs dans un dispositif de chauffage permettant de porter le tube à une température de traitement comprise entre TRm-50°C et TRm-100°C pendant une durée comprise entre 0,1 et 10 secondes, TRm étant la température (°C) à laquelle la courbe d'adoucissement dudit cuivre ou alliage de cuivre, qui donne la charge à la rupture Rm en fonction de la température, présente un point d'inflexion. 1 - Process for improving the workability of hard copper or copper alloy tubes comprising a heat treatment of said hard tubes, characterized in that the hard tubes are continuously scrolled through a heating device making it possible to bring the tube to a treatment temperature between T Rm -50 ° C and T Rm -100 ° C for a period of between 0.1 and 10 seconds, T Rm being the temperature (° C) at which the softening curve of said copper or alloy of copper, which gives the tensile strength Rm as a function of temperature, has an inflection point. 2 - Procédé selon la revendication 1 dans lequel ledit dispositif est un four à induction ayant une puissance suffisante pour permettre le défilement de tubes à une vitesse comprise entre 30 et 250 m/min. 2 - The method of claim 1 wherein said device is an induction furnace having sufficient power to allow the scrolling of tubes at a speed between 30 and 250 m / min. 3 - Procédé selon une quelconque des revendications 1 et 2 dans lequel ledit tube de cuivre dur est en cuivre désoxydé au phosphore Cub₁ ou Cub₂ et chauffé à une température de traitement comprise entre 370 et 420°C. 3 - A method according to any one of claims 1 and 2 wherein said hard copper tube is deoxidized copper phosphor Cub₁ or Cub₂ and heated to a treatment temperature between 370 and 420 ° C. 4- Procédé selon la revendication 3 dans lequel la température de traitement est de préférence comprise entre 380 et 415°C. 4- The method of claim 3 wherein the treatment temperature is preferably between 380 and 415 ° C. 5 - Procédé selon une quelconque des revendications 1 à 4 dans lequel l'atmosphère extérieure des tubes durs pendant le chauffage est constituée d'un gaz neutre alors que celle de l'intérieur des tubes durs contient de l'oxygène. 5 - Method according to any one of claims 1 to 4 wherein the outer atmosphere of the hard tubes during heating consists of a neutral gas while that of the interior of the hard tubes contains oxygen. 6 - Procédé selon la revendication 5 dans lequel l'atmosphère à l'intérieur des tubes durs contient de l'air ou un mélange d'air et d'oxygène en toutes proportions. 6 - Process according to claim 5 wherein the atmosphere inside the hard tubes contains air or a mixture of air and oxygen in all proportions. 7 - Tubes durs en cuivre ou alliage de cuivre obtenus selon le procédé de l'une quelconque des revendications 1 à 6 qui présentent des propriétés améliorées en cintrabilité . 7 - Hard copper or copper alloy tubes obtained according to the method of any one of claims 1 to 6 which have improved properties in cintrability. 8 - Tubes selon la revendication 7 présentant une charge à la rupture Rm supérieure à 360 MPa et un allongement A% supérieur à 8%. 8 - Tubes according to claim 7 having a breaking load Rm greater than 360 MPa and an elongation A% greater than 8%. 9 - Tubes selon une quelconque des revendications 5 ou 6 dont la surface intérieure est recouverte d'une couche mince de Cu₂O qui présentent des propriétés améliorées en cintrabilité et en résistance à la corrosion. 9 - Tubes according to any one of claims 5 or 6, the inner surface is covered with a thin layer of Cu₂O which have improved properties in workability and resistance to corrosion.
EP91420365A 1990-10-18 1991-10-16 Process for improving the pliability of hardened copper tubes by dynamic thermal treatment Expired - Lifetime EP0481902B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9013484A FR2668170B1 (en) 1990-10-18 1990-10-18 PROCESS FOR IMPROVING THE CINTRABILITY OF HARD COPPER TUBES BY DYNAMIC HEAT TREATMENT.
FR9013484 1990-10-18

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EP0481902A1 true EP0481902A1 (en) 1992-04-22
EP0481902B1 EP0481902B1 (en) 1995-11-29

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DE (1) DE69114991T2 (en)
ES (1) ES2079618T3 (en)
FR (1) FR2668170B1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4334536A1 (en) * 1993-10-09 1995-04-13 Kabelmetal Ag Process for the production of seamless drawn semi-hard / hard installation pipes

Citations (5)

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Publication number Priority date Publication date Assignee Title
GB1138485A (en) * 1965-10-20 1969-01-01 Phelps Dodge Copper Prod Process for production of tubes
US3965027A (en) * 1974-03-11 1976-06-22 Calgon Corporation Scale inhibition and corrosion inhibition
BE841148A (en) * 1976-04-26 1976-08-16 METHOD OF MANUFACTURING COPPER OR COPPER ALLOY TUBE ROLLS
FR2490116A1 (en) * 1980-09-12 1982-03-19 Gp Konstruk Prodn. of brass pipes - by cold working a tubular blank and then annealing in a protective atmos.
EP0213771A2 (en) * 1985-08-02 1987-03-11 Westinghouse Electric Corporation Improvements in or relating to annealing metal tubing

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Publication number Priority date Publication date Assignee Title
US3956027A (en) * 1975-04-09 1976-05-11 Olin Corporation Processing copper base alloys
FR2547317B3 (en) * 1983-06-09 1986-02-28 Trefimetaux PROCESS FOR IMPROVING THE CINTRABILITY OF A NUT OF COPPER TUBE, BY PARTIAL ANNEALING
JPH0674494B2 (en) * 1985-04-04 1994-09-21 株式会社神戸製鋼所 Manufacturing method of tempered copper pipe

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1138485A (en) * 1965-10-20 1969-01-01 Phelps Dodge Copper Prod Process for production of tubes
US3965027A (en) * 1974-03-11 1976-06-22 Calgon Corporation Scale inhibition and corrosion inhibition
BE841148A (en) * 1976-04-26 1976-08-16 METHOD OF MANUFACTURING COPPER OR COPPER ALLOY TUBE ROLLS
FR2490116A1 (en) * 1980-09-12 1982-03-19 Gp Konstruk Prodn. of brass pipes - by cold working a tubular blank and then annealing in a protective atmos.
EP0213771A2 (en) * 1985-08-02 1987-03-11 Westinghouse Electric Corporation Improvements in or relating to annealing metal tubing

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
AMERICAN SOCIETY FOR METALS 'METALS HANDBOOK EDITION 9 VOL 2' 1979 , ASM , METALS PARK, OHIO, US "HEAT TREATING OF COPPER AND COPPER ALLOYS" *
PATENT ABSTRACTS OF JAPAN vol. 11, no. 75 (C-408)(2522) 6 Mars 1987 & JP-A-61 231 146 ( KOBE STEEL LTD ) 15 Octobre 1986 *

Also Published As

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ES2079618T3 (en) 1996-01-16
DE69114991D1 (en) 1996-01-11
DE69114991T2 (en) 1996-04-18
FR2668170B1 (en) 1992-12-11
FR2668170A1 (en) 1992-04-24
EP0481902B1 (en) 1995-11-29

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