EP2942792A1 - Process for manufacturing a magnetic part of a differential relay comprising a surface treatment by shot-peening - Google Patents

Process for manufacturing a magnetic part of a differential relay comprising a surface treatment by shot-peening Download PDF

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Publication number
EP2942792A1
EP2942792A1 EP15163999.4A EP15163999A EP2942792A1 EP 2942792 A1 EP2942792 A1 EP 2942792A1 EP 15163999 A EP15163999 A EP 15163999A EP 2942792 A1 EP2942792 A1 EP 2942792A1
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EP
European Patent Office
Prior art keywords
magnetic
manufacturing
magnetic part
surface treatment
pallet
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EP15163999.4A
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German (de)
French (fr)
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EP2942792B1 (en
Inventor
Ghislain Saujot
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Aperam SA
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Aperam SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H83/00—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current
    • H01H83/14—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by imbalance of two or more currents or voltages, e.g. for differential protection
    • H01H83/144—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by imbalance of two or more currents or voltages, e.g. for differential protection with differential transformer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/081—Magnetic constructions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H51/00—Electromagnetic relays
    • H01H51/22—Polarised relays
    • H01H51/2236—Polarised relays comprising pivotable armature, pivoting at extremity or bending point of armature

Definitions

  • the present invention provides a method for manufacturing a magnetic part of a high sensitivity differential relay.
  • Such switches or circuit breakers are intended to ensure the safety of people by quickly cutting a main electrical circuit when a fault appears on this circuit.
  • the "self-current" type of differential circuit breakers consist of a fault current detector, a high sensitivity differential relay, and a mechanism for opening the main electrical circuit.
  • the differential relay comprises a magnetic circuit comprising two magnetic pieces, which are a movable pallet and a fixed armature.
  • the fault current detector When a fault appears on the main electrical circuit, the fault current detector is able to send an electrical signal to the differential relay. In response to this electrical signal, the differential relay opens by pivoting the pallet relative to the armature, which causes the opening mechanism of the main electrical circuit to be set in motion.
  • the magnetic parts of the differential relay consist of a soft magnetic alloy, characterized by high saturation induction, low coercive field, and relatively high electrical resistivity. Such characteristics ensure proper operation of the differential relay.
  • the magnetic parts of the magnet magnetic circuit of the iron-nickel type for example an alloy comprising, by weight, from 46% to 49% of nickel, especially %, the rest being iron and impurities resulting from the elaboration.
  • This alloy has the advantage of having a saturation induction Bs of 1.5 Tesla and a coercive field Hc of 4 A / m.
  • the magnetic parts thus manufactured are nevertheless likely to be subjected to humid atmospheric conditions, which entails a risk of corrosion between the iron and the nickel of the alloy forming oxides and hydroxides of iron leading either to inadvertent tripping of the differential relay, on the contrary to a bonding of the pallet on the frame.
  • the magnetic nickel-based alloys used have a low hardness (of the order of 120 HV) and a low wear resistance.
  • these nickel alloys are not stainless and their resistance to corrosion under the conditions of use of the relay is insufficient.
  • An object of the invention is to overcome these disadvantages and to provide a method for manufacturing magnetic parts of a differential relay having good wear resistance, and which is less costly to implement than the methods according to the invention. state of the art.
  • the subject of the invention is a process of the aforementioned type, said manufacturing method comprising a step of microbrilling surface treatment of at least a portion of a surface of said magnetic part, said surface treatment step by microbilling comprising a projection of microbeads under pressure on said surface portion.
  • the invention also relates to a magnetic part of a magnetic circuit of a high sensitivity differential relay, characterized in that it is obtained by a method of manufacturing a magnetic part according to the invention.
  • the invention also relates to a magnetic circuit of a high sensitivity differential relay, said magnetic circuit comprising two magnetic parts forming a frame and a pallet, characterized in that at least one of said magnetic pieces is a magnetic piece according to the invention. 'invention.
  • circuit breaker 1 interposed on a main electrical supply circuit of an electrical apparatus 2, for the detection of a leakage current in this main electrical circuit.
  • the circuit breaker 1 comprises a magnetic core 3, a differential relay with high sensitivity 5, and a mechanism 7 for opening the main electrical circuit.
  • the magnetic core 3 is able to detect a fault current on the main circuit.
  • the differential relay 5 comprises a magnetic circuit 9, a permanent magnet 11 and a return spring 13.
  • the magnetic circuit 9 comprises two magnetic relay parts, which are a movable vane 15 and a U-shaped fixed armature 17.
  • the frame 17 comprises a base 18, and first and second branches 19 and 20, the branches 19 and 20 being each terminated by a flat polar surface 19a, 20a.
  • the pallet 15 is mounted facing the polar surfaces 19a, 20a of the frame 17.
  • the pallet 15 comprises a substantially flat polar surface 15a, adapted to come into contact with the polar surfaces 19a and 20a of the frame 17.
  • the pallet 15 is pivotally mounted about an axis corresponding to an edge 21 of a first branch 19 of the armature 17, between a rest position, shown in FIG. figure 1 in which the pole surface 15a of the paddle 15 is in contact against the pole surfaces 19a, 20a of the frame 17, and a pivoted position, in which the paddle 15 has pivoted about the edge 21, is more in contact with the polar surface 20a of the second branch 20.
  • the pole surface 15a of the pallet 15 and the pole surfaces 19a and 20a of the frame 17 are contact areas intended to come into contact with one another.
  • the pallet 15 and the frame are made of a Fe-Ni alloy.
  • the Fe-Ni alloy is for example an alloy comprising, by weight, from 46% to 49% of nickel, the balance being iron and impurities resulting from the preparation. This is for example an alloy of Supra50® type.
  • the permanent magnet 11 is in the shape of a parallelepiped bar.
  • the permanent magnet 11 is placed between the branches 19 and 20 of the armature 17, one of the poles of the magnet 11 being attached to the base 18 of the armature 17, and the other pole being placed opposite of the pallet 15.
  • the permanent magnet 11 is able to exert a magnetic force on the pallet 15 to maintain it in the rest position.
  • the return spring 13 is adapted to exert a force on the pallet 15, antagonistic to the force exerted by the permanent magnet 11, to drive it to the rotated position.
  • a control coil 23 is wound on the second branch 20 of the armature 17.
  • the control coil 23 is supplied with electric current via the magnetic core 3.
  • the control coil 23 is able to generate an opposite magnetic flux. the flow of the permanent magnet 11 in the branch 20 when the control coil 13 is traversed by an excitation current.
  • the spring is calibrated so that a fault current greater than or equal to 30 mA causes a pivoting of the pallet 15 to its pivoted position.
  • the displacement of the pallet 15 from its rest position to the rotated position makes it possible to actuate the opening mechanism 7 of the main electric circuit, and thus to cut off the power supply to the apparatus 2.
  • the manufacture of the magnetic circuit 9 comprises the manufacture of the two magnetic parts of this circuit, that is to say the pallet 15 and the armature 17, and the assembly of these two parts to form the circuit.
  • the manufacture of each of the magnetic parts comprises the manufacture of a blank part.
  • Each blank is manufactured by cutting in a Fe-Ni alloy strip, followed by a shaping by folding, so as to give each piece the desired geometry, the cutting being followed by a high temperature heat treatment (greater than 1000 ° C) intended to give the band the desired mechanical and magnetic properties, in particular a very low coercive field, for example less than or equal to 15 A / m.
  • Such a coercive field makes it possible to obtain a high sensitivity of the relay, for example an electrical triggering power of less than 250 ⁇ VA and preferably of between 50 and 150 ⁇ VA.
  • the alloy strip is obtained from an ingot by hot rolling, followed by cold rolling.
  • each blank is then subjected to a microbead surface treatment step, during which microbeads are sprayed onto at least a portion of the surface of each blank.
  • the surface portion on which the microbeads are projected comprises at least the contact zones of this part, that is to say the areas of this part intended to come into contact with the other part.
  • the microbeads are projected on the sides of the magnetic parts comprising the contact areas of these parts, that is to say the areas of these parts intended to come into contact with each other.
  • the treatment by microbilling has the effect of performing a surface hardening penetrating a few hundredths of a millimeter, in particular from 0.03 mm to 0.05 mm, on the treated surface portion, and thus to increase the hardness of the piece on this surface portion.
  • the micro-shot treatment makes it possible to increase the Vickers hardness on the surface of the workpiece by more than 50 HV, the hardness passing for example from 120 HV to more than 170 HV.
  • a depth of at least a few hundredths of a millimeter, in particular of at least 0.03 mm, is sufficient to keep the possibility of carrying out, after the microbeading treatment, surfacing operations with a slight removal of material, while retaining on the surface of the workpiece an increased hardness of at least 170 HV.
  • a depth of at most a few hundredths of a millimeter, in particular of at most 0.05 mm makes it possible to ensure the conservation of the magnetic properties of the part.
  • each of the pieces is subjected to a finishing treatment intended to give the piece the appearance, roughness and flatness desired by the application.
  • obtaining a roughness Ra at least equal to 0.03 ⁇ m and less than 0.5 ⁇ m ensures a good quality of contact between the contact areas of the two parts.
  • the pallet 15 and the armature 17 thus manufactured are then assembled to form the magnetic circuit 9.
  • an intermediate finishing treatment step may be performed on the rough parts prior to the microbead treatment step.
  • microbead treatment step will now be described in more detail with reference to the figure 2 which schematically illustrates a device 50 for implementing this step.
  • the device 50 comprises an enclosure 52 comprising an opening 54 for the introduction of the rough parts, able to be sealed in order to seal the enclosure 52.
  • the device 50 also comprises means 56 for supporting rough magnetic parts, and means 58 for projecting a flow of microbeads conveyed in a fluid, on the parts held by the support means 56.
  • the means 58 for spraying microbeads comprise a nozzle 60 for projecting a flow of microbeads conveyed in a fluid, and means for supplying the nozzle 60 with a fluid under pressure conveying microbeads.
  • Microbeads are glass, ceramic or steel balls of micrometric size.
  • the microbeads have a diameter of between 20 ⁇ m and 200 ⁇ m.
  • the microbeads are microbeads of the SS19 type marketed by Rössler France. These microbeads are made of soda-lime glass of average diameter substantially equal to 40 ⁇ m.
  • the fluid in which the microbeads are conveyed is for example water or air.
  • the fluid used is water, in which the microbeads are mixed, the mixture comprising 25% by volume of microbeads.
  • the nozzle 60 comprises an opening 62 through which the pressurized fluid, mixed with the microbeads, is projected.
  • the shape and dimensions of the opening 62 are adjustable depending on the extent of the surface to be treated and the homogeneity of the desired projection.
  • the opening 62 is for example a circular opening, with a diameter of between 5 and 12 mm, in particular equal to 10 mm.
  • the pressure of the fluid mixed with the microbeads at the outlet of the nozzle 60 is for example between 1 and 5 bar.
  • the support means 56 are able to maintain a magnetic piece in a predetermined position in front of the opening 62 of the nozzle 60 during the projection of the microbeads on this piece.
  • the support means 56 are furthermore able to modify the position of the magnetic part with respect to the projection means 58, in particular the distance d between the part and the opening 62 and the orientation of the part with respect to the jet issuing from the opening 62, subsequently called angle of attack ⁇ .
  • the distance d is for example between 100 mm and 200 mm.
  • the angle of attack is for example equal to 90 °, that is to say that the jet from the nozzle has an angle of incidence on the part substantially equal to 90 °.
  • the angle of attack can also be chosen less than 90 °, for example equal to 75 °.
  • the support means 56 comprise, for example, a magnet capable of exerting a magnetic force on a magnetic piece to hold it in position, the magnet being able to be rotated with respect to the nozzle 60 in order to rotate the magnetic piece by compared to the nozzle 60.
  • the support means 56 thus make it possible to scan one or more parts by the jet coming from the nozzle 60.
  • Fe-Ni alloy strips comprising 48% of Ni have been manufactured, the balance being iron and impurities resulting from the preparation, from ingots, by hot rolling, followed by cold rolling.
  • Cutting pallets and reinforcements were then produced by cutting into these strips, followed by bending shaping, and a heat treatment to impart to the band the desired mechanical and magnetic properties.
  • a finishing intermediate treatment was then carried out on a first series of rough-edged reinforcements, followed by a micro-bead treatment using the device described with reference to FIG. figure 2 .
  • a finishing treatment was again applied to the reinforcement to obtain finished reinforcement.
  • a second batch of preformed frameworks was subjected to microbead treatment, without intermediate finishing treatment, by means of the device described with reference to FIG. figure 2 .
  • a finishing treatment was applied to the reinforcements to obtain finished reinforcement.
  • microbeaching treatments were carried out using microbeads of SS19 type described above, conveyed in water, the water-microbead mixture comprising 25% microbeads by volume.
  • the nozzle used is a nozzle having a circular opening 62 of diameter equal to 10 mm. Furthermore, the distance between the opening 62 of the nozzle 60 and the pallets and armatures was set at 150 mm.
  • the coefficient of roughness Ra of the reinforcements and pallets of each group was also measured.
  • the influence of the microbell treatment on the electrical properties of a magnetic circuit formed with the treated pallets and reinforcements has been determined.
  • the impedance of a magnetic circuit according to the state of the art, formed by assembling a pallet and a coated armature but not micro-blasted is typically between 1.10 ⁇ and 1.75 ⁇ .
  • magnetic circuits were formed from the vanes and armatures of each of the groups, and the impedance of the magnetic circuits thus formed, that is to say the resistance of these circuits to the passage of a magnetic flux, was measured. .
  • a force F was applied to the pallet 15 by means of a weight. This force is intended to simulate the force exerted by the permanent magnet 11 when the differential relay 5 is in operation.
  • a first coil 70 comprising N1 turns, was wound around one of the branches 19 of the frame 17, and a second coil 72, comprising N2 turns, was wound around the other branch 20 of the frame 17 .
  • the first coil 70 is connected to an alternating current generator 74, and the second coil is connected to a voltmeter 76.
  • An alternating current I was generated by the generator 74 in the first coil 70, the value of this current being controlled by means of an ammeter 78.
  • the voltage V across the second coil 74 has been measured.
  • the impedance Z was then determined as the ratio of the voltage V to the current I.
  • reinforcements of each of the groups of the first series were assembled on the one hand with non-coated and non-micro-blotted pallets, on the other hand with pallets coated with a chromed and non-microbelled coating, and finally with pallets obtained by the process according to the invention, therefore uncoated and microballed, of the corresponding group of the series of pallets.
  • Reinforcements were also assembled from each of the groups of the second series on the one hand with non-coated and non-micro-blotted pallets, on the other hand with pallets coated with a chromed and non-microbelled coating, and finally with pallets obtained by the process according to the invention, thus uncoated and microballed, of the corresponding group of the series of pallets.
  • the electrical impedance, denoted Z pal was then measured. prod, magnetic circuits formed by armatures of each of the groups and pallets uncoated and non-microballed, the electrical impedance, denoted Z pal Cr, magnetic circuits formed by armatures of each of the groups and pallets coated with chromium and non microballed, and electrical impedance, noted Z pal ⁇ bill, circuits magnets formed by frames of each group and pallets according to the invention of the corresponding group.
  • pallets of each of the groups of the series of pallets were assembled on the one hand with uncoated and non-microbelled reinforcement, on the other hand with reinforcement coated with a chromed and non-microbelled coating, and finally with reinforcements obtained by the process according to the invention, thus uncoated and microbeaded, of the corresponding group of the first series of reinforcements.
  • the electrical impedance, denoted Z arm was then measured. prod, magnetic circuits formed by vanes of each of the uncoated and non-microbelled groups and armatures, the electrical impedance, denoted Z arm Cr, magnetic circuits formed by vanes of each of the chromium-coated groups and armatures and non-microballed, and electrical impedance, denoted Z arm ⁇ bill, magnetic circuits formed by pallets of each of the groups and armatures according to the invention of the corresponding group of the first series of frames.
  • the electrical impedance Z arm ⁇ bill of a magnetic circuit formed by a pallet of a group and an armature according to the invention of the corresponding group of the first series of armatures is necessarily identical to the electrical impedance Z pal ⁇ bill of a magnetic circuit formed by an armature of the first series of this group and a pallet according to the invention of the corresponding group, as can be seen in Table 2.
  • Table 2 Impedance, Hardness and Roughness Measurements Series Group N ° Z pal. prod Z pal. dream Z pal.
  • the roughness coefficients of the pallets and reinforcements are also satisfactory, in particular greater than 0.03 ⁇ m.
  • the electrical impedances of magnetic circuits formed by a pallet and an armature manufactured according to the method according to the invention have a satisfactory electrical impedance of between 1.10 ⁇ and 1.75 ⁇ . These satisfactory values are also found for electrical circuits of which only one of the mechanical parts has been manufactured according to a method according to the invention.
  • step of microbrilling treatment makes it possible to increase the hardness of the surface of these magnetic parts without negatively impacting other properties, in particular the impedance of the magnetic circuit or the ability of these parts to undergo effective finishing treatment.
  • the contact surfaces of the magnetic parts according to the invention therefore have a very satisfactory wear resistance, and substantially greater than the wear resistance of the relays comprising metal coatings of known type.
  • only the pallet or only the armature can be manufactured according to a method according to the invention.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacture Of Motors, Generators (AREA)
  • Soft Magnetic Materials (AREA)

Abstract

Ce procédé de fabrication d'une pièce magnétique (15, 17) d'un relais différentiel (5) à haute sensibilité comprend une étape de traitement de surface par microbillage d'au moins une portion d'une surface de ladite pièce magnétique (15, 17). L'étape de traitement de surface par microbillage comporte une projection de microbilles sous pression sur ladite portion de surface.This method of manufacturing a magnetic part (15, 17) of a high sensitivity differential relay (5) comprises a step of microbrilling surface treatment of at least a portion of a surface of said magnetic part (15). , 17). The microbead surface treatment step comprises a projection of microbeads under pressure on said surface portion.

Description

La présente invention un procédé de fabrication d'une pièce magnétique d'un relais différentiel à haute sensibilité.The present invention provides a method for manufacturing a magnetic part of a high sensitivity differential relay.

Elle s'applique en particulier à la fabrication d'interrupteurs ou de disjoncteurs de protection différentielle.It applies in particular to the manufacture of switches or circuit breakers of differential protection.

De tels interrupteurs ou disjoncteurs différentiels sont destinés à assurer la sécurité des personnes en coupant rapidement un circuit électrique principal lorsqu'apparaît un défaut sur ce circuit. En particulier, les disjoncteurs différentiels du type dit « à propre courant » sont constitués d'un détecteur de courant de défaut, d'un relais différentiel à haute sensibilité, et d'un mécanisme d'ouverture du circuit électrique principal.Such switches or circuit breakers are intended to ensure the safety of people by quickly cutting a main electrical circuit when a fault appears on this circuit. In particular, the "self-current" type of differential circuit breakers consist of a fault current detector, a high sensitivity differential relay, and a mechanism for opening the main electrical circuit.

Le relais différentiel comprend un circuit magnétique comportant deux pièces magnétiques, qui sont une palette mobile et une armature fixe.The differential relay comprises a magnetic circuit comprising two magnetic pieces, which are a movable pallet and a fixed armature.

Lorsqu'un défaut apparait sur le circuit électrique principal, le détecteur de courant de défaut est propre à envoyer un signal électrique au relais différentiel. En réponse à ce signal électrique, le relais différentiel s'ouvre, par pivotement de la palette par rapport à l'armature, ce qui provoque la mise en mouvement du mécanisme d'ouverture du circuit électrique principal.When a fault appears on the main electrical circuit, the fault current detector is able to send an electrical signal to the differential relay. In response to this electrical signal, the differential relay opens by pivoting the pallet relative to the armature, which causes the opening mechanism of the main electrical circuit to be set in motion.

Les pièces magnétiques du relais différentiel sont constituées d'un alliage magnétique doux, caractérisé par une induction à saturation élevée, un champ coercitif faible et une résistivité électrique relativement élevée. De telles caractéristiques assurent un bon fonctionnement du relais différentiel.The magnetic parts of the differential relay consist of a soft magnetic alloy, characterized by high saturation induction, low coercive field, and relatively high electrical resistivity. Such characteristics ensure proper operation of the differential relay.

Afin de satisfaire aux conditions de caractéristiques magnétiques souhaitables, il est connu de fabriquer les pièces magnétiques du circuit magnétique en alliage magnétique du type fer-nickel, par exemple un alliage comprenant, en poids, de 46% à 49% de nickel, notamment 48%, le reste étant du fer et des impuretés résultant de l'élaboration. Cet alliage a l'avantage d'avoir une induction à saturation Bs de 1,5 Tesla et un champ coercitif Hc de 4 A/m.In order to satisfy the conditions of desirable magnetic characteristics, it is known to manufacture the magnetic parts of the magnet magnetic circuit of the iron-nickel type, for example an alloy comprising, by weight, from 46% to 49% of nickel, especially %, the rest being iron and impurities resulting from the elaboration. This alloy has the advantage of having a saturation induction Bs of 1.5 Tesla and a coercive field Hc of 4 A / m.

Les pièces magnétiques ainsi fabriquées sont néanmoins susceptibles d'être soumises à des conditions atmosphériques humides, ce qui entraîne un risque de corrosion entre le fer et le nickel de l'alliage formant des oxydes et des hydroxydes de fer conduisant soit à des déclenchements intempestifs du relais différentiel, soit au contraire à un collage de la palette sur l'armature.The magnetic parts thus manufactured are nevertheless likely to be subjected to humid atmospheric conditions, which entails a risk of corrosion between the iron and the nickel of the alloy forming oxides and hydroxides of iron leading either to inadvertent tripping of the differential relay, on the contrary to a bonding of the pallet on the frame.

En outre, les contacts successifs entre la palette et l'armature sont susceptibles de conduire à une usure locale et à une déformation de ces pièces, entraînant un mauvais fonctionnement du relais différentiel.In addition, successive contacts between the pallet and the armature are likely to lead to local wear and deformation of these parts, causing a malfunction of the differential relay.

Généralement, les alliages magnétiques à base de nickel utilisés ont une faible dureté (de l'ordre de 120 HV) et une faible résistance à l'usure. En outre, ces alliages de nickel ne sont pas inoxydables et leur tenue à la corrosion dans les conditions d'utilisation du relais est insuffisante.Generally, the magnetic nickel-based alloys used have a low hardness (of the order of 120 HV) and a low wear resistance. In addition, these nickel alloys are not stainless and their resistance to corrosion under the conditions of use of the relay is insufficient.

On a donc proposé d'améliorer la dureté et la résistance à l'usure des surfaces de contact des pièces magnétiques des relais en réalisant sur ces surfaces des revêtements métalliques qui accroissent également la résistance à la corrosion des surfaces de contact. Ces revêtements métalliques sont par exemple des dépôts d'or, de chrome ou de carbone diamant.It has therefore been proposed to improve the hardness and wear resistance of the contact surfaces of the magnetic parts of the relays by producing on these surfaces metal coatings which also increase the corrosion resistance of the contact surfaces. These metal coatings are for example deposits of gold, chromium or diamond carbon.

Néanmoins, cette technique est très coûteuse.Nevertheless, this technique is very expensive.

Il a par ailleurs été proposé de conditionner les relais différentiels dans des boitiers en plastique imperméables, propres à protéger de la corrosion le circuit magnétique. Cependant, cette technique ne permet pas de résoudre les problèmes liés à l'usure du circuit magnétique.It has also been proposed to condition the differential relays in waterproof plastic housings, able to protect the magnetic circuit from corrosion. However, this technique does not solve the problems related to the wear of the magnetic circuit.

Un but de l'invention est de remédier à ces inconvénients et de fournir un procédé de fabrication de pièces magnétiques d'un relais différentiel ayant une bonne résistance à l'usure, et qui soit moins coûteux à mettre en oeuvre que les procédés selon l'état de la technique.An object of the invention is to overcome these disadvantages and to provide a method for manufacturing magnetic parts of a differential relay having good wear resistance, and which is less costly to implement than the methods according to the invention. state of the art.

A cet effet, l'invention a pour objet un procédé du type précité, ledit procédé de fabrication comprenant une étape de traitement de surface par microbillage d'au moins une portion d'une surface de ladite pièce magnétique, ladite étape de traitement de surface par microbillage comportant une projection de microbilles sous pression sur ladite portion de surface.For this purpose, the subject of the invention is a process of the aforementioned type, said manufacturing method comprising a step of microbrilling surface treatment of at least a portion of a surface of said magnetic part, said surface treatment step by microbilling comprising a projection of microbeads under pressure on said surface portion.

Selon d'autres aspects de l'invention, le procédé de fabrication comprend l'une ou plusieurs des caractéristiques suivantes :

  • ladite pièce magnétique est une armature ou une palette d'un circuit magnétique ;
  • ladite pièce est en alliage Fe-Ni comprenant, en poids, de 46% à 49% de nickel, le reste étant du fer et des impuretés résultant de l'élaboration ;
  • lesdites microbilles sont des microbilles de verre, de céramique ou d'acier ;
  • lesdites microbilles sont projetées sur ladite portion de surface avec une pression comprise entre 1 et 5 bars ;
  • le procédé de fabrication comprend en outre une étape intermédiaire de surfaçage de ladite pièce magnétique, mise en oeuvre avant l'étape de traitement de surface par microbillage ;
  • le procédé de fabrication comprend en outre une étape finale de surfaçage de ladite pièce magnétique, mise en oeuvre après l'étape de traitement de surface par microbillage.
According to other aspects of the invention, the manufacturing method comprises one or more of the following features:
  • said magnetic piece is a frame or a paddle of a magnetic circuit;
  • said part is made of Fe-Ni alloy comprising, by weight, from 46% to 49% of nickel, the balance being iron and impurities resulting from the preparation;
  • said microbeads are microspheres of glass, ceramic or steel;
  • said microbeads are projected on said surface portion with a pressure of between 1 and 5 bar;
  • the manufacturing method further comprises an intermediate step of surfacing said magnetic part, implemented before the step of surface treatment by microbeading;
  • the manufacturing method further comprises a final step of surfacing said magnetic part, implemented after the surface microbeaching treatment step.

L'invention a également pour objet un procédé de fabrication d'un circuit magnétique d'un relais différentiel à haute sensibilité, ledit circuit magnétique comprenant deux pièces magnétiques formant une armature et une palette, ledit procédé comprenant :

  • la fabrication desdites pièces magnétiques, et
  • l'assemblage desdites pièces magnétiques pour former ledit circuit magnétique, dans lequel la fabrication d'au moins une desdites pièces magnétiques est mise en oeuvre par un procédé de fabrication d'une pièce magnétique selon l'invention.
The invention also relates to a method for manufacturing a magnetic circuit of a high sensitivity differential relay, said magnetic circuit comprising two magnetic parts forming a frame and a pallet, said method comprising:
  • the manufacture of said magnetic pieces, and
  • assembling said magnetic pieces to form said magnetic circuit, wherein the manufacture of at least one of said magnetic pieces is carried out by a method of manufacturing a magnetic piece according to the invention.

L'invention a également pour objet une pièce magnétique d'un circuit magnétique d'un relais différentiel à haute sensibilité, caractérisée en ce qu'elle est obtenue par un procédé de fabrication d'une pièce magnétique selon l'invention.The invention also relates to a magnetic part of a magnetic circuit of a high sensitivity differential relay, characterized in that it is obtained by a method of manufacturing a magnetic part according to the invention.

L'invention a également pour objet un circuit magnétique d'un relais différentiel à haute sensibilité, ledit circuit magnétique comprenant deux pièces magnétiques formant une armature et une palette, caractérisé en ce qu'au moins une desdites pièces magnétiques est une pièce magnétique selon l'invention.The invention also relates to a magnetic circuit of a high sensitivity differential relay, said magnetic circuit comprising two magnetic parts forming a frame and a pallet, characterized in that at least one of said magnetic pieces is a magnetic piece according to the invention. 'invention.

L'invention sera mieux comprise à la lecture de la description qui va suivre, donnée uniquement à titre d'exemple et faite en se référant aux figures annexées parmi lesquelles :

  • la figure 1 est une vue schématique d'un disjoncteur comportant un relais différentiel à haute sensibilité suivant l'invention,
  • la figure 2 est une vue schématique d'un dispositif pour la mise en oeuvre du procédé selon un mode de réalisation de l'invention,
  • la figure 3 est un schéma d'un montage électrique pour la détermination de l'impédance de circuits magnétiques selon l'invention.
The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended figures in which:
  • the figure 1 is a schematic view of a circuit breaker comprising a differential relay with high sensitivity according to the invention,
  • the figure 2 is a schematic view of a device for implementing the method according to one embodiment of the invention,
  • the figure 3 is a diagram of an electrical assembly for the determination of the impedance of magnetic circuits according to the invention.

On a illustré sur la figure 1 un disjoncteur 1 interposé sur un circuit électrique principal d'alimentation d'un appareil électrique 2, pour la détection d'un courant de fuite dans ce circuit électrique principal.We illustrated on the figure 1 a circuit breaker 1 interposed on a main electrical supply circuit of an electrical apparatus 2, for the detection of a leakage current in this main electrical circuit.

Le disjoncteur 1 comprend un tore magnétique 3, un relais différentiel à haute sensibilité 5, et un mécanisme 7 d'ouverture du circuit électrique principal.The circuit breaker 1 comprises a magnetic core 3, a differential relay with high sensitivity 5, and a mechanism 7 for opening the main electrical circuit.

Le tore magnétique 3 est propre à détecter un défaut de courant sur le circuit principal.The magnetic core 3 is able to detect a fault current on the main circuit.

Le relais différentiel 5 comprend un circuit magnétique 9, un aimant permanent 11 et un ressort de rappel 13.The differential relay 5 comprises a magnetic circuit 9, a permanent magnet 11 and a return spring 13.

Le circuit magnétique 9 comporte deux pièces magnétiques de relais, qui sont une palette mobile 15 et une armature fixe 17 en forme de U.The magnetic circuit 9 comprises two magnetic relay parts, which are a movable vane 15 and a U-shaped fixed armature 17.

L'armature 17 comprend une base 18, et une première et une deuxième branches 19 et 20, les branches 19 et 20 étant chacune terminée par une surface polaire plane 19a, 20a.The frame 17 comprises a base 18, and first and second branches 19 and 20, the branches 19 and 20 being each terminated by a flat polar surface 19a, 20a.

La palette 15 est montée en regard des surfaces polaires 19a, 20a de l'armature 17. La palette 15 comprend une surface polaire 15a sensiblement plane, propre à venir en contact avec les surfaces polaires 19a et 20a de l'armature 17.The pallet 15 is mounted facing the polar surfaces 19a, 20a of the frame 17. The pallet 15 comprises a substantially flat polar surface 15a, adapted to come into contact with the polar surfaces 19a and 20a of the frame 17.

La palette 15 est montée pivotante autour d'un axe correspondant à une arête 21 d'une première branche 19 de l'armature 17, entre une position de repos, représentée à la figure 1, dans laquelle la surface polaire 15a de la palette 15 est en contact contre les surfaces polaires 19a, 20a de l'armature 17, et une position pivotée, dans laquelle la palette 15, ayant pivoté autour de l'arête 21, n'est plus en contact avec la surface polaire 20a de la deuxième branche 20.The pallet 15 is pivotally mounted about an axis corresponding to an edge 21 of a first branch 19 of the armature 17, between a rest position, shown in FIG. figure 1 in which the pole surface 15a of the paddle 15 is in contact against the pole surfaces 19a, 20a of the frame 17, and a pivoted position, in which the paddle 15 has pivoted about the edge 21, is more in contact with the polar surface 20a of the second branch 20.

La surface polaire 15a de la palette 15 et les surfaces polaires 19a et 20a de l'armature 17 sont des zones de contact destinées à venir en contact les unes avec les autres.The pole surface 15a of the pallet 15 and the pole surfaces 19a and 20a of the frame 17 are contact areas intended to come into contact with one another.

La palette 15 et l'armature sont réalisées en un alliage Fe-Ni. L'alliage Fe-Ni est par exemple un alliage comprenant, en poids, de 46% à 49% de nickel, le reste étant du fer et des impuretés résultant de l'élaboration. Il s'agit par exemple d'un alliage de type Supra50®.The pallet 15 and the frame are made of a Fe-Ni alloy. The Fe-Ni alloy is for example an alloy comprising, by weight, from 46% to 49% of nickel, the balance being iron and impurities resulting from the preparation. This is for example an alloy of Supra50® type.

L'aimant permanent 11 est en forme de barreau parallélépipédique. L'aimant permanent 11 est placé entre les branches 19 et 20 de l'armature 17, l'un des pôles de l'aimant 11 étant accolé à la base 18 de l'armature 17, et l'autre pôle étant placé en regard de la palette 15.The permanent magnet 11 is in the shape of a parallelepiped bar. The permanent magnet 11 is placed between the branches 19 and 20 of the armature 17, one of the poles of the magnet 11 being attached to the base 18 of the armature 17, and the other pole being placed opposite of the pallet 15.

L'aimant permanent 11 est propre à exercer une force magnétique sur la palette 15 pour la maintenir en position de repos.The permanent magnet 11 is able to exert a magnetic force on the pallet 15 to maintain it in the rest position.

Par ailleurs, le ressort de rappel 13 est propre à exercer une force sur la palette 15, antagoniste à la force exercée par l'aimant permanent 11, pour l'entraîner vers la position pivotée.Furthermore, the return spring 13 is adapted to exert a force on the pallet 15, antagonistic to the force exerted by the permanent magnet 11, to drive it to the rotated position.

Une bobine 23 de commande est enroulée sur la deuxième branche 20 de l'armature 17. La bobine 23 de commande est alimentée en courant électrique par l'intermédiaire du tore magnétique 3. La bobine 23 de commande est propre à engendrer un flux magnétique opposé au flux de l'aimant permanent 11 dans la branche 20 lorsque la bobine 13 de commande est parcourue par un courant d'excitation.A control coil 23 is wound on the second branch 20 of the armature 17. The control coil 23 is supplied with electric current via the magnetic core 3. The control coil 23 is able to generate an opposite magnetic flux. the flow of the permanent magnet 11 in the branch 20 when the control coil 13 is traversed by an excitation current.

Lorsqu'un défaut de courant est détecté par le tore 3, un courant d'excitation est généré dans la bobine 23 de commande, ce qui génère un flux magnétique dans le circuit magnétique 9 opposé au flux de l'aimant permanent 11 et entraîne une réduction ou une annulation de la force de maintien exercée sur la palette 15. La force exercée par le ressort de rappel 13 surpasse la force de maintien exercée sur la palette 15, ce qui entraîne un pivotement de la palette 15 vers sa position pivotée.When a current fault is detected by the core 3, an excitation current is generated in the control coil 23, which generates a magnetic flux in the magnetic circuit 9 opposite to the flux of the permanent magnet 11 and causes a reducing or canceling the holding force exerted on the pallet 15. The force exerted by the return spring 13 surpasses the holding force exerted on the pallet 15, which causes a pivoting of the pallet 15 to its pivoted position.

A titre d'exemple, le ressort est taré pour qu'un courant de défaut supérieur ou égal à 30 mA entraîne un pivotement de la palette 15 vers sa position pivotée.For example, the spring is calibrated so that a fault current greater than or equal to 30 mA causes a pivoting of the pallet 15 to its pivoted position.

Le déplacement de la palette 15 de sa position de repos à la position pivotée permet d'actionner le mécanisme 7 d'ouverture du circuit électrique principal, et donc de couper l'alimentation électrique de l'appareil 2.The displacement of the pallet 15 from its rest position to the rotated position makes it possible to actuate the opening mechanism 7 of the main electric circuit, and thus to cut off the power supply to the apparatus 2.

La fabrication du circuit magnétique 9 comprend la fabrication des deux pièces magnétiques de ce circuit, c'est-à-dire la palette 15 et l'armature 17, et l'assemblage de ces deux pièces pour former le circuit.The manufacture of the magnetic circuit 9 comprises the manufacture of the two magnetic parts of this circuit, that is to say the pallet 15 and the armature 17, and the assembly of these two parts to form the circuit.

La fabrication de chacune des pièces magnétiques comprend la fabrication d'une pièce ébauchée.The manufacture of each of the magnetic parts comprises the manufacture of a blank part.

Chaque pièce ébauchée est fabriquée par découpe dans une bande en alliage Fe-Ni, suivie d'une mise en forme par pliage, de manière à donner à chacune des pièces la géométrie souhaitée, la découpe étant suivie d'un traitement thermique à haute température (supérieure à 1000°C) destiné à conférer à la bande les propriétés mécaniques et magnétiques souhaitées, en particulier un champ coercitif très faible, par exemple inférieur ou égal à 15 A/m.Each blank is manufactured by cutting in a Fe-Ni alloy strip, followed by a shaping by folding, so as to give each piece the desired geometry, the cutting being followed by a high temperature heat treatment (greater than 1000 ° C) intended to give the band the desired mechanical and magnetic properties, in particular a very low coercive field, for example less than or equal to 15 A / m.

Un tel champ coercitif permet d'obtenir une forte sensibilité du relais, par exemple une puissance électrique de déclenchement inférieure à 250µVA et de préférence comprise entre 50 et 150µVA.Such a coercive field makes it possible to obtain a high sensitivity of the relay, for example an electrical triggering power of less than 250μVA and preferably of between 50 and 150μVA.

De manière connue, la bande en alliage est obtenue à partir d'un lingot par laminage à chaud, suivi d'un laminage à froid.In known manner, the alloy strip is obtained from an ingot by hot rolling, followed by cold rolling.

Chaque pièce ébauchée est alors soumise à une étape de traitement de surface par microbillage, lors de laquelle des microbilles sont projetées sur au moins une portion de la surface de chaque pièce ébauchée. Pour chacune des pièces magnétiques, la portion de surface sur laquelle les microbilles sont projetées comprend au moins les zones de contact de cette pièce, c'est-à-dire les zones de cette pièce destinée à venir en contact avec l'autre pièce.Each blank is then subjected to a microbead surface treatment step, during which microbeads are sprayed onto at least a portion of the surface of each blank. For each of the magnetic parts, the surface portion on which the microbeads are projected comprises at least the contact zones of this part, that is to say the areas of this part intended to come into contact with the other part.

Selon un mode de réalisation, les microbilles sont projetées sur les côtés des pièces magnétiques comprenant les zones de contact de ces pièces, c'est-à-dire les zones de ces pièces destinées à venir en contact les unes avec les autres.According to one embodiment, the microbeads are projected on the sides of the magnetic parts comprising the contact areas of these parts, that is to say the areas of these parts intended to come into contact with each other.

Le traitement par microbillage a pour effet de réaliser un écrouissage superficiel pénétrant de quelques centièmes de millimètres, notamment de 0,03 mm à 0,05 mm, sur la portion de surface traitée, et ainsi d'augmenter la dureté de la pièce sur cette portion de surface. A titre d'exemple, le traitement par microbillage permet d'augmenter la dureté Vickers à la surface de la pièce de plus de 50 HV, la dureté passant par exemple de 120 HV à plus de 170 HV.The treatment by microbilling has the effect of performing a surface hardening penetrating a few hundredths of a millimeter, in particular from 0.03 mm to 0.05 mm, on the treated surface portion, and thus to increase the hardness of the piece on this surface portion. By way of example, the micro-shot treatment makes it possible to increase the Vickers hardness on the surface of the workpiece by more than 50 HV, the hardness passing for example from 120 HV to more than 170 HV.

Une profondeur d'au moins quelques centièmes de millimètres, notamment d'au moins 0,03 mm, est suffisante pour garder la possibilité de réaliser, postérieurement au traitement par microbillage, des opérations de surfaçage avec un léger enlèvement de matière, tout en conservant à la surface de la pièce une dureté augmentée, d'au moins 170 HV. Par ailleurs, une profondeur d'au plus quelques centièmes de millimètres, notamment d'au plus 0,05 mm, permet d'assurer la conservation des propriétés magnétiques de la pièce.A depth of at least a few hundredths of a millimeter, in particular of at least 0.03 mm, is sufficient to keep the possibility of carrying out, after the microbeading treatment, surfacing operations with a slight removal of material, while retaining on the surface of the workpiece an increased hardness of at least 170 HV. Moreover, a depth of at most a few hundredths of a millimeter, in particular of at most 0.05 mm, makes it possible to ensure the conservation of the magnetic properties of the part.

A l'issue du traitement par microbillage, chacune des pièces est soumise à un traitement de finition destiné à conférer à la pièce l'aspect, la rugosité et la planéité voulue par l'application.At the end of the micro-grinding treatment, each of the pieces is subjected to a finishing treatment intended to give the piece the appearance, roughness and flatness desired by the application.

En particulier, l'obtention d'une rugosité Ra au moins égale à 0,03 µm et inférieure à 0,5 µm permet d'assurer une bonne qualité de contact entre les zones de contact des deux pièces.In particular, obtaining a roughness Ra at least equal to 0.03 μm and less than 0.5 μm ensures a good quality of contact between the contact areas of the two parts.

La palette 15 et l'armature 17 ainsi fabriquées sont alors assemblées pour former le circuit magnétique 9.The pallet 15 and the armature 17 thus manufactured are then assembled to form the magnetic circuit 9.

En variante, une étape de traitement intermédiaire de finition peut être réalisée sur les pièces ébauchées, avant l'étape de traitement par microbillage.Alternatively, an intermediate finishing treatment step may be performed on the rough parts prior to the microbead treatment step.

L'étape de traitement par microbillage va maintenant être décrite plus en détails en référence à la figure 2, qui illustre schématiquement un dispositif 50 pour la mise en oeuvre de cette étape.The microbead treatment step will now be described in more detail with reference to the figure 2 which schematically illustrates a device 50 for implementing this step.

Le dispositif 50 comprend une enceinte 52 comprenant une ouverture 54 pour l'introduction des pièces ébauchées, propre à être scellée pour fermer de manière étanche l'enceinte 52.The device 50 comprises an enclosure 52 comprising an opening 54 for the introduction of the rough parts, able to be sealed in order to seal the enclosure 52.

Le dispositif 50 comprend par ailleurs des moyens 56 de support de pièces magnétiques ébauchées, et des moyens 58 de projection d'un flux de microbilles convoyées dans un fluide, sur les pièces maintenues par les moyens 56 de support.The device 50 also comprises means 56 for supporting rough magnetic parts, and means 58 for projecting a flow of microbeads conveyed in a fluid, on the parts held by the support means 56.

Les moyens 58 de projection de microbilles comprennent une buse 60 de projection d'un flux de microbilles convoyées dans un fluide, et des moyens d'alimentation de la buse 60 en un fluide sous pression convoyant des microbilles.The means 58 for spraying microbeads comprise a nozzle 60 for projecting a flow of microbeads conveyed in a fluid, and means for supplying the nozzle 60 with a fluid under pressure conveying microbeads.

Les microbilles sont des billes en verre, en céramique ou en acier, de taille micrométrique. Par exemple, les microbilles ont un diamètre compris entre 20 µm et 200 µm.Microbeads are glass, ceramic or steel balls of micrometric size. For example, the microbeads have a diameter of between 20 μm and 200 μm.

A titre d'exemple les microbilles sont des microbilles de type SS19 commercialisées par Rössler France. Ces microbilles sont en verre sodocalcique de diamètre moyen sensiblement égal à 40 µm.By way of example, the microbeads are microbeads of the SS19 type marketed by Rössler France. These microbeads are made of soda-lime glass of average diameter substantially equal to 40 μm.

Le fluide dans lequel sont convoyées les microbilles est par exemple de l'eau ou de l'air.The fluid in which the microbeads are conveyed is for example water or air.

Par exemple, le fluide utilisé est de l'eau, dans lequel sont mélangées les microbilles, le mélange comprenant 25% en volume de microbilles.For example, the fluid used is water, in which the microbeads are mixed, the mixture comprising 25% by volume of microbeads.

La buse 60 comprend une ouverture 62 par laquelle le fluide sous pression, mélangé aux microbilles, est projeté. La forme et les dimensions de l'ouverture 62 sont ajustables en fonction de l'étendue de la surface à traiter et de l'homogénéité de la projection recherchée. L'ouverture 62 est par exemple une ouverture circulaire, de diamètre compris entre 5 et 12 mm, notamment égale à 10 mm.The nozzle 60 comprises an opening 62 through which the pressurized fluid, mixed with the microbeads, is projected. The shape and dimensions of the opening 62 are adjustable depending on the extent of the surface to be treated and the homogeneity of the desired projection. The opening 62 is for example a circular opening, with a diameter of between 5 and 12 mm, in particular equal to 10 mm.

La pression du fluide mélangé aux microbilles à la sortie de la buse 60 est par exemple comprise entre 1 et 5 bars.The pressure of the fluid mixed with the microbeads at the outlet of the nozzle 60 is for example between 1 and 5 bar.

Les moyens 56 de support sont propres à maintenir une pièce magnétique dans une position prédéterminée en face de l'ouverture 62 de la buse 60 lors de la projection des microbilles sur cette pièce. Les moyens 56 de support sont par ailleurs propres à modifier la position de la pièce magnétique par rapport aux moyens 58 de projection, notamment la distance d entre la pièce et l'ouverture 62 et l'orientation de la pièce par rapport au jet issu de l'ouverture 62, appelé par la suite angle d'attaque α.The support means 56 are able to maintain a magnetic piece in a predetermined position in front of the opening 62 of the nozzle 60 during the projection of the microbeads on this piece. The support means 56 are furthermore able to modify the position of the magnetic part with respect to the projection means 58, in particular the distance d between the part and the opening 62 and the orientation of the part with respect to the jet issuing from the opening 62, subsequently called angle of attack α.

La distance d est par exemple comprise entre 100 mm et 200 mm.The distance d is for example between 100 mm and 200 mm.

L'angle d'attaque est par exemple égal à 90°, c'est-à-dire que le jet issu de la buse a un angle d'incidence sur la pièce sensiblement égal à 90°. L'angle d'attaque peut également être choisi inférieur à 90°, par exemple égal à 75°.The angle of attack is for example equal to 90 °, that is to say that the jet from the nozzle has an angle of incidence on the part substantially equal to 90 °. The angle of attack can also be chosen less than 90 °, for example equal to 75 °.

Le réglage de la distance d et de l'angle α permettent de contrôler l'écrouissage obtenu sur la pièce traitée.The adjustment of the distance d and the angle α make it possible to control the work hardening obtained on the treated part.

Les moyens 56 de support comprennent par exemple un aimant propre à exercer une force magnétique sur une pièce magnétique pour la maintenir en position, l'aimant étant propre à être entraîné en rotation par rapport à la buse 60 pour entraîner en rotation la pièce magnétique par rapport à la buse 60.The support means 56 comprise, for example, a magnet capable of exerting a magnetic force on a magnetic piece to hold it in position, the magnet being able to be rotated with respect to the nozzle 60 in order to rotate the magnetic piece by compared to the nozzle 60.

Les moyens 56 de support permettent ainsi de réaliser un balayage d'une ou plusieurs pièce(s) par le jet issu de la buse 60.The support means 56 thus make it possible to scan one or more parts by the jet coming from the nozzle 60.

A titre d'exemple, on a fabriqué des bandes en alliage Fe-Ni, comprenant 48% de Ni, le reste étant du fer et des impuretés résultant de l'élaboration, à partir de lingots, par laminage à chaud, suivi d'un laminage à froid.By way of example, Fe-Ni alloy strips comprising 48% of Ni have been manufactured, the balance being iron and impurities resulting from the preparation, from ingots, by hot rolling, followed by cold rolling.

On a ensuite fabriqué des palettes et des armatures ébauchées par découpe dans ces bandes, suivie d'une mise en forme par pliage, et d'un traitement thermique destiné à conférer à la bande les propriétés mécaniques et magnétiques souhaitées.Cutting pallets and reinforcements were then produced by cutting into these strips, followed by bending shaping, and a heat treatment to impart to the band the desired mechanical and magnetic properties.

On a alors effectué sur une première série d'armatures ébauchées un traitement intermédiaire de finition, suivi d'un traitement par microbillage au moyen du dispositif décrit en référence à la figure 2. A l'issue du traitement par microbillage, un traitement de finition a été à nouveau appliqué aux armatures pour obtenir des armatures finies.A finishing intermediate treatment was then carried out on a first series of rough-edged reinforcements, followed by a micro-bead treatment using the device described with reference to FIG. figure 2 . At the end of the microbead treatment, a finishing treatment was again applied to the reinforcement to obtain finished reinforcement.

On a par ailleurs effectué sur une deuxième série d'armatures ébauchées un traitement par microbillage, sans traitement de finition intermédiaire, au moyen du dispositif décrit en référence à la figure 2. A l'issue du traitement par microbillage, un traitement de finition a été appliqué aux armatures pour obtenir des armatures finies.In addition, a second batch of preformed frameworks was subjected to microbead treatment, without intermediate finishing treatment, by means of the device described with reference to FIG. figure 2 . At the end of the microbeach treatment, a finishing treatment was applied to the reinforcements to obtain finished reinforcement.

On a également effectué sur une série de palettes ébauchées un traitement par microbillage, sans traitement de finition intermédiaire, au moyen du dispositif décrit en référence à la figure 2. A l'issue du traitement par microbillage, un traitement de finition a été appliqué aux palettes pour obtenir des palettes finies.A microbrack treatment, without intermediate finishing treatment, was also performed on a series of roughing pallets by means of the device described with reference to FIG. figure 2 . After the microbead treatment, a finishing treatment was applied to the pallets to obtain finished pallets.

Tous ces traitements par microbillage ont été effectué au moyen de microbilles de type SS19 décrites ci-dessus, convoyées dans de l'eau, le mélange eau-microbilles comprenant 25% de microbilles en volume.All these microbeaching treatments were carried out using microbeads of SS19 type described above, conveyed in water, the water-microbead mixture comprising 25% microbeads by volume.

La buse utilisée est une buse ayant une ouverture 62 circulaire de diamètre égal à 10 mm. Par ailleurs, la distance entre l'ouverture 62 de la buse 60 et les palettes et armatures a été fixée à 150 mm.The nozzle used is a nozzle having a circular opening 62 of diameter equal to 10 mm. Furthermore, the distance between the opening 62 of the nozzle 60 and the pallets and armatures was set at 150 mm.

Chacune des séries d'armatures et de palettes a été divisé en neuf groupes, et chaque armature ou palette de chaque groupe a été traitée par microbillage suivant les paramètres d'angle d'attaque α, de pression P et de durée d'exposition T figurant dans le tableau 1 ci-dessous. Tableau 1 : paramètres de traitement de microbillage appliqué à chaque groupe Série Groupe N° α(°) P (bars) T (s) Première série d'armatures 1 90 1 7 2 90 1 14 3 90 1,5 7 4 90 1,5 14 5 90 2 7 6 90 2 14 7 75 2 7 8 90 2,5 7 9 90 2,5 14 Deuxième série d'armatures 1 90 1 7 2 90 1 14 3 90 1,5 7 4 90 1,5 14 5 90 2 7 6 90 2 14 7 75 2 7 8 90 2,5 7 9 90 2,5 14 Série de palettes 1 90 1 7 2 90 1 14 3 90 1,5 7 4 90 1,5 14 5 90 2 7 6 90 2 14 7 75 2 7 8 90 2,5 7 9 90 2,5 14 Each series of reinforcements and pallets was divided into nine groups, and each reinforcement or pallet of each group was treated by microbooting according to the parameters of angle of attack α, pressure P and exposure time T shown in Table 1 below. Table 1: Microbead treatment parameters applied to each group Series Group N ° α (°) P (bars) T (s) First series of frames 1 90 1 7 2 90 1 14 3 90 1.5 7 4 90 1.5 14 5 90 2 7 6 90 2 14 7 75 2 7 8 90 2.5 7 9 90 2.5 14 Second series of frames 1 90 1 7 2 90 1 14 3 90 1.5 7 4 90 1.5 14 5 90 2 7 6 90 2 14 7 75 2 7 8 90 2.5 7 9 90 2.5 14 Pallet series 1 90 1 7 2 90 1 14 3 90 1.5 7 4 90 1.5 14 5 90 2 7 6 90 2 14 7 75 2 7 8 90 2.5 7 9 90 2.5 14

On a ensuite mesuré l'influence du traitement par microbillage sur la dureté de la surface des palettes et armatures.The influence of microbell treatment on the hardness of the surface of the pallets and reinforcements was then measured.

Pour cela, on a mesuré la dureté Vickers HV 0,025 et HV 0,01 des palettes ou armatures de chacun des groupes.For this, the Vickers HV 0.025 and HV 0.01 hardness of the pallets or reinforcements of each of the groups were measured.

On a par ailleurs mesuré le coefficient de rugosité Ra des armatures et palettes de chacun de groupes.The coefficient of roughness Ra of the reinforcements and pallets of each group was also measured.

Les mesures obtenues, résultant au sein de chacun des groupes d'une moyenne des valeurs de rugosité, de tombée et de dureté Vickers mesurées sur cinq palettes ou armatures de ce groupe, sont reportées dans le tableau 2.The measurements obtained, resulting in each group of an average of the Vickers roughness, fall and hardness values measured on five pallets or frames of this group, are reported in Table 2.

Par ailleurs, on a déterminé l'influence du traitement par microbillage sur les propriétés électriques d'un circuit magnétique formée avec les palettes et armatures traitées. En particulier, l'impédance d'un circuit magnétique selon l'état de la technique, formé par assemblage d'une palette et d'une armature revêtue mais non microbillées, est typiquement comprise entre 1,10 Ω et 1,75 Ω. On a ainsi formé, à partir des palettes et armatures de chacun des groupes, des circuits magnétiques, et mesuré l'impédance des circuits magnétiques ainsi formés, c'est-à-dire la résistance de ces circuits au passage d'un flux magnétique.On the other hand, the influence of the microbell treatment on the electrical properties of a magnetic circuit formed with the treated pallets and reinforcements has been determined. In particular, the impedance of a magnetic circuit according to the state of the art, formed by assembling a pallet and a coated armature but not micro-blasted, is typically between 1.10 Ω and 1.75 Ω. Thus magnetic circuits were formed from the vanes and armatures of each of the groups, and the impedance of the magnetic circuits thus formed, that is to say the resistance of these circuits to the passage of a magnetic flux, was measured. .

La mesure d'impédance de chaque circuit a été effectuée selon le montage décrit en référence à la Figure 3.The impedance measurement of each circuit was carried out according to the arrangement described with reference to the Figure 3 .

Comme illustré sur la Figure 3, une force F a été appliquée sur la palette 15 au moyen d'un poids. Cette force est destiné à simuler la force exercée par l'aimant permanent 11 lorsque le relai différentiel 5 est en fonctionnement.As illustrated on the Figure 3 a force F was applied to the pallet 15 by means of a weight. This force is intended to simulate the force exerted by the permanent magnet 11 when the differential relay 5 is in operation.

Une première bobine 70, comprenant N1 spires, a été enroulée autour d'une des branches 19 de l'armature 17, et une deuxième bobine 72, comprenant N2 spires, a été enroulée autour de l'autre branche 20 de l'armature 17.A first coil 70, comprising N1 turns, was wound around one of the branches 19 of the frame 17, and a second coil 72, comprising N2 turns, was wound around the other branch 20 of the frame 17 .

La première bobine 70 est reliée à un générateur de courant alternatif 74, et la deuxième bobine est reliée à un voltmètre 76.The first coil 70 is connected to an alternating current generator 74, and the second coil is connected to a voltmeter 76.

Un courant alternatif I a été généré par le générateur 74 dans la première bobine 70, la valeur de ce courant étant contrôlée au moyen d'un ampèremètre 78.An alternating current I was generated by the generator 74 in the first coil 70, the value of this current being controlled by means of an ammeter 78.

La tension V aux bornes de la deuxième bobine 74 a été mesurée.The voltage V across the second coil 74 has been measured.

L'impédance Z a alors été déterminée comme le rapport de la tension V sur le courant I.The impedance Z was then determined as the ratio of the voltage V to the current I.

En particulier, on a assemblé des armatures de chacun des groupes de la première série d'une part avec des palettes non revêtues et non microbillées, d'autre part avec des palettes revêtues d'un revêtement chromé et non microbillées, et enfin avec des palettes obtenues par le procédé selon l'invention, donc non revêtues et microbillées, du groupe correspondant de la série de palettes.In particular, reinforcements of each of the groups of the first series were assembled on the one hand with non-coated and non-micro-blotted pallets, on the other hand with pallets coated with a chromed and non-microbelled coating, and finally with pallets obtained by the process according to the invention, therefore uncoated and microballed, of the corresponding group of the series of pallets.

On a par ailleurs assemblé des armatures de chacun des groupes de la deuxième série d'une part avec des palettes non revêtues et non microbillées, d'autre part avec des palettes revêtues d'un revêtement chromé et non microbillées, et enfin avec des palettes obtenues par le procédé selon l'invention, donc non revêtues et microbillées, du groupe correspondant de la série de palettes.Reinforcements were also assembled from each of the groups of the second series on the one hand with non-coated and non-micro-blotted pallets, on the other hand with pallets coated with a chromed and non-microbelled coating, and finally with pallets obtained by the process according to the invention, thus uncoated and microballed, of the corresponding group of the series of pallets.

On a ensuite mesuré l'impédance électrique, notée Z pal. prod, des circuits magnétiques formés par des armatures de chacun des groupes et des palettes non revêtues et non microbillées, l'impédance électrique, notée Z pal Cr, des circuits magnétiques formés par des armatures de chacun des groupes et des palettes revêtues de chrome et non microbillées, et l'impédance électrique, notée Z pal µbill, des circuits magnétiques formés par des armatures de chacun des groupes et des palettes selon l'invention du groupe correspondant.The electrical impedance, denoted Z pal, was then measured. prod, magnetic circuits formed by armatures of each of the groups and pallets uncoated and non-microballed, the electrical impedance, denoted Z pal Cr, magnetic circuits formed by armatures of each of the groups and pallets coated with chromium and non microballed, and electrical impedance, noted Z pal μbill, circuits magnets formed by frames of each group and pallets according to the invention of the corresponding group.

Les impédances mesurées sont reportées dans le tableau 2.The measured impedances are reported in Table 2.

De même, on a assemblé des palettes de chacun des groupes de la série de palettes d'une part avec des armatures non revêtues et non microbillées, d'autre part avec des armatures revêtues d'un revêtement chromé et non microbillées, et enfin avec des armatures obtenues par le procédé selon l'invention, donc non revêtues et microbillées, du groupe correspondant de la première série d'armatures.Likewise, pallets of each of the groups of the series of pallets were assembled on the one hand with uncoated and non-microbelled reinforcement, on the other hand with reinforcement coated with a chromed and non-microbelled coating, and finally with reinforcements obtained by the process according to the invention, thus uncoated and microbeaded, of the corresponding group of the first series of reinforcements.

On a ensuite mesuré l'impédance électrique, notée Z arm. prod, des circuits magnétiques formés par des palettes de chacun des groupes et des armatures non revêtues et non microbillées, l'impédance électrique, notée Z arm Cr, des circuits magnétiques formés par des palettes de chacun des groupes et des armatures revêtues de chrome et non microbillées, et l'impédance électrique, notée Z arm µbill, des circuits magnétiques formés par des palettes de chacun des groupes et des armatures selon l'invention du groupe correspondant de la première série d'armatures.The electrical impedance, denoted Z arm, was then measured. prod, magnetic circuits formed by vanes of each of the uncoated and non-microbelled groups and armatures, the electrical impedance, denoted Z arm Cr, magnetic circuits formed by vanes of each of the chromium-coated groups and armatures and non-microballed, and electrical impedance, denoted Z arm μbill, magnetic circuits formed by pallets of each of the groups and armatures according to the invention of the corresponding group of the first series of frames.

Les impédances mesurées, exprimées en ohms, sont reportées dans le tableau 2.The measured impedances, expressed in ohms, are reported in Table 2.

Il est à noter que l'impédance électrique Z arm µbill d'un circuit magnétique formé par une palette d'un groupe et une armature selon l'invention du groupe correspondant de la première série d'armatures est nécessairement identique à l'impédance électrique Z pal µbill d'un circuit magnétique formé par une armature de la première série de ce groupe et une palette selon l'invention du groupe correspondant, comme cela est visible dans le tableau 2. Tableau 2 : Mesures d'impédance, de dureté et de rugosité Série Groupe N° Z pal. prod Z pal. revê Z pal. µbill HV 0,025 HV 0,01 Ra (µm) Première série d'armatures 1 1,732 1,248 1,424 269 253 0,0764 2 1,614 1,252 1,458 289 290 0,0406 3 1,452 1,16 1,322 273 259 0,0358 4 1,6 1,202 1,378 276 298 0,0392 5 1,658 1,19 1,292 274 229 0,0388 6 1,476 1,174 1,294 297 317 0,0382 7 1,572 1,166 1,378 287 234 0,0384 8 1,484 1,174 1,36 275 275 0,052 9 1,454 1,246 1,32 275 251 0,0356 Deuxième série d'armatures 1 1,74 1,35 1,482 297 255 0,0372 2 1,644 1,284 1,32 305 285 0,0412 3 1,574 1,276 1,304 271 295 0,0366 4 1,62 1,246 1,372 294 276 0,041 5 1,532 1,242 1,414 257 287 0,0418 6 1,532 1,216 1,32 289 300 0,0394 7 1,542 1,282 1,382 281 255 0,0384 8 1,462 1,112 1,322 242 270 0,0384 9 1,458 1,07 1,226 312 311 0,0456 Série Groupe N° Z arm. prod Z arm. revê Z arm. µbill HV 0,025 HV 0,01 Ra (µm) Série de palettes 1 1,74 1,218 1,424 240 231 0,0678 2 1,498 1,232 1,458 215 213 0,066 3 1,274 1,016 1,322 246 238 0,0586 4 1,454 1,052 1,378 260 224 0,058 5 1,536 1,06 1,292 251 249 0,056 6 1,422 1,068 1,294 265 257 0,062 7 1,482 1,114 1,378 256 232 0,064 8 1,448 1,102 1,36 253 263 0,056 9 1,492 1,07 1,32 261 245 0,06 It should be noted that the electrical impedance Z arm μbill of a magnetic circuit formed by a pallet of a group and an armature according to the invention of the corresponding group of the first series of armatures is necessarily identical to the electrical impedance Z pal μbill of a magnetic circuit formed by an armature of the first series of this group and a pallet according to the invention of the corresponding group, as can be seen in Table 2. Table 2: Impedance, Hardness and Roughness Measurements Series Group N ° Z pal. prod Z pal. dream Z pal. μbill HV 0.025 HV 0.01 Ra (μm) First series of frames 1 1,732 1,248 1,424 269 253 0.0764 2 1,614 1,252 1,458 289 290 0.0406 3 1,452 1.16 1,322 273 259 0.0358 4 1.6 1,202 1,378 276 298 0.0392 5 1,658 1.19 1,292 274 229 0.0388 6 1,476 1,174 1,294 297 317 0.0382 7 1,572 1,166 1,378 287 234 0.0384 8 1,484 1,174 1.36 275 275 0,052 9 1,454 1,246 1.32 275 251 0.0356 Second series of frames 1 1.74 1.35 1,482 297 255 0.0372 2 1,644 1,284 1.32 305 285 0.0412 3 1,574 1,276 1,304 271 295 0.0366 4 1.62 1,246 1,372 294 276 0.041 5 1,532 1,242 1,414 257 287 .0418 6 1,532 1,216 1.32 289 300 0.0394 7 1,542 1,282 1,382 281 255 0.0384 8 1,462 1,112 1,322 242 270 0.0384 9 1,458 1.07 1,226 312 311 0.0456 Series Group N ° Z arm. prod Z arm. dream Z arm. μbill HV 0.025 HV 0.01 Ra (μm) Pallet series 1 1.74 1,218 1,424 240 231 0.0678 2 1,498 1,232 1,458 215 213 0.066 3 1,274 1,016 1,322 246 238 .0586 4 1,454 1,052 1,378 260 224 0.058 5 1,536 1.06 1,292 251 249 0,056 6 1,422 1,068 1,294 265 257 0.062 7 1,482 1,114 1,378 256 232 0.064 8 1,448 1,102 1.36 253 263 0,056 9 1,492 1.07 1.32 261 245 0.06

Les résultats reportés dans le tableau 2 montrent que le procédé de fabrication des palettes et armatures selon l'invention, en particulier l'étape de traitement par microbillage de ces palettes et armatures, permettent d'augmenter la dureté de la surface de ces pièces de manière très satisfaisante. En effet, que l'angle d'attaque soit égal à 90° ou 75°, et quelle que soit la pression du flux projeté à la sortie de la buse, entre 1 bar et 2,5 bar, les duretés Vickers HV 0,025 et HV 0,01 sont nettement supérieures à la dureté initiale des pièces (120 HV), et également nettement supérieures aux duretés généralement obtenues par des procédés de revêtement (170 HV).The results reported in Table 2 show that the method of manufacturing the pallets and reinforcements according to the invention, in particular the step of microbrilling treatment of these pallets and frames, makes it possible to increase the hardness of the surface of these pieces of very satisfactory way. Indeed, that the angle of attack is equal to 90 ° or 75 °, and whatever the pressure of the projected flow at the outlet of the nozzle, between 1 bar and 2.5 bar, Vickers hardness HV 0.025 and HV 0.01 are significantly higher than the initial hardness of the parts (120 HV), and also significantly higher than the hardnesses generally obtained by coating processes (170 HV).

En outre, les coefficients de rugosité des palettes et armatures sont également satisfaisants, notamment supérieurs à 0,03 µm. Ainsi, ces résultats montrent que l'écrouissage superficiel de la surface des pièces permet de réaliser une finition satisfaisante des pièces avec enlèvement de matière, tout en conservant en surface une dureté élevée.In addition, the roughness coefficients of the pallets and reinforcements are also satisfactory, in particular greater than 0.03 μm. Thus, these results show that the surface hardening of the surface of the parts makes it possible to finish satisfactory parts with removal of material, while maintaining high surface hardness.

On constate par ailleurs que les impédances électriques de circuits magnétiques formés d'une palette et d'une armature fabriquées selon le procédé selon l'invention ont une impédance électrique satisfaisante, comprise entre 1,10 Ω et 1,75 Ω. Ces valeurs satisfaisantes sont également constatées pour des circuits électriques dont une seule des pièces mécaniques a été fabriquée selon un procédé selon l'invention.Moreover, it can be seen that the electrical impedances of magnetic circuits formed by a pallet and an armature manufactured according to the method according to the invention have a satisfactory electrical impedance of between 1.10 Ω and 1.75 Ω. These satisfactory values are also found for electrical circuits of which only one of the mechanical parts has been manufactured according to a method according to the invention.

Ces résultats montrent ainsi que l'étape de traitement par microbillage permet d'augmenter la dureté de la surface de ces pièces magnétiques sans impacter négativement d'autres propriétés, notamment l'impédance du circuit magnétique ou l'aptitude de ces pièces à subir un traitement de finition efficace.These results thus show that the step of microbrilling treatment makes it possible to increase the hardness of the surface of these magnetic parts without negatively impacting other properties, in particular the impedance of the magnetic circuit or the ability of these parts to undergo effective finishing treatment.

Les surfaces de contact des pièces magnétiques suivant l'invention présentent en conséquence une résistance à l'usure très satisfaisante, et sensiblement supérieure à la résistance à l'usure des relais comportant des revêtements métalliques de type connu.The contact surfaces of the magnetic parts according to the invention therefore have a very satisfactory wear resistance, and substantially greater than the wear resistance of the relays comprising metal coatings of known type.

Il devra toutefois être compris que l'exemple de réalisation présenté ci-dessus n'est pas limitatif.It will however be understood that the embodiment shown above is not limiting.

Notamment, selon une variante, seule la palette ou seule l'armature peut être fabriquée selon un procédé conforme à l'invention.In particular, according to one variant, only the pallet or only the armature can be manufactured according to a method according to the invention.

Claims (12)

Procédé de fabrication d'une pièce magnétique (15, 17) d'un relais différentiel (5) à haute sensibilité, ledit procédé de fabrication comprenant une étape de traitement de surface par microbillage d'au moins une portion d'une surface de ladite pièce magnétique (15, 17), ladite étape de traitement de surface par microbillage comportant une projection de microbilles sous pression sur ladite portion de surface.A method of manufacturing a magnetic part (15, 17) of a high sensitivity differential relay (5), said manufacturing method comprising a step of microbrilling surface treatment of at least a portion of a surface of said magnetic piece (15, 17), said microbead surface treatment step comprising a projection of microbeads under pressure on said surface portion. Procédé de fabrication d'une pièce magnétique (15, 17) selon la revendication 1, dans lequel ladite pièce magnétique est une armature (17) ou une palette (15) d'un circuit magnétique (9).A method of manufacturing a magnetic part (15, 17) according to claim 1, wherein said magnetic part is a frame (17) or a pallet (15) of a magnetic circuit (9). Procédé de fabrication d'une pièce magnétique (15, 17) selon l'une quelconque des revendications 1 ou 2, dans lequel ladite pièce est en alliage Fe-Ni comprenant, en poids, de 46% à 49% de nickel, le reste étant du fer et des impuretés résultant de l'élaboration.A method of manufacturing a magnetic part (15, 17) according to any one of claims 1 or 2, wherein said part is made of Fe-Ni alloy comprising, by weight, 46% to 49% nickel, the rest being iron and impurities resulting from the elaboration. Procédé de fabrication d'une pièce magnétique (15, 17) selon l'une quelconque des revendications 1 à 3, dans lequel lesdites microbilles sont des microbilles de verre, de céramique ou d'acier.A method of manufacturing a magnetic part (15, 17) according to any one of claims 1 to 3, wherein said microbeads are microspheres of glass, ceramic or steel. Procédé de fabrication d'une pièce magnétique (15, 17) selon l'une quelconque des revendications 1 à 4, dans lequel lesdites microbilles sont projetées sur ladite portion de surface avec une pression comprise entre 1 et 5 bars.A method of manufacturing a magnetic part (15, 17) according to any one of claims 1 to 4, wherein said microbeads are projected on said surface portion with a pressure of between 1 and 5 bar. Procédé de fabrication d'une pièce magnétique (15, 17) selon l'une quelconque des revendications 1 à 5, comprenant en outre une étape intermédiaire de surfaçage de ladite pièce magnétique (15, 17), mise en oeuvre avant l'étape de traitement de surface par microbillage.A method of manufacturing a magnetic part (15, 17) according to any one of claims 1 to 5, further comprising an intermediate step of surfacing said magnetic part (15, 17), implemented before the step of surface treatment by microbeading. Procédé de fabrication d'une pièce magnétique (15, 17) selon l'une quelconque des revendications 1 à 6, comprenant en outre une étape finale de surfaçage de ladite pièce magnétique (15, 17), mise en oeuvre après l'étape de traitement de surface par microbillage.A method of manufacturing a magnetic part (15, 17) according to any one of claims 1 to 6, further comprising a final step of surfacing said magnetic part (15, 17), implemented after the step of surface treatment by microbeading. Procédé de fabrication selon l'une quelconque des revendications 1 à 7, caractérisé en ce qu'il comprend, avant ladite étape de traitement de surface, une étape de fabrication d'une pièce magnétique ébauchée, comprenant une phase de découpe d'une bande obtenue par un laminage à chaud suivi d'un laminage à froid, ladite étape de traitement de surface étant mise en oeuvre sur ladite pièce magnétique ébauchée.Manufacturing method according to any one of claims 1 to 7, characterized in that it comprises, before said surface treatment step, a step of manufacturing a rough magnetic part, comprising a cutting phase of a strip obtained by hot rolling followed by cold rolling, said surface treatment step being carried out on said rough magnetic part. Procédé selon la revendication 8, caractérisé en ce que ladite étape de fabrication de la pièce magnétique ébauchée comprend en outre, après la phase de découpe, une phase de mise en forme par pliage de la bande découpée.A method according to claim 8, characterized in that said step of manufacturing the roughed magnetic piece further comprises, after the cutting step, a phase of forming by folding the cut strip. Procédé de fabrication d'un circuit magnétique (9) d'un relais différentiel (5) à haute sensibilité, ledit circuit magnétique (9) comprenant deux pièces magnétiques (15, 17) formant une armature (17) et une palette (15), ledit procédé comprenant : - la fabrication desdites pièces magnétiques (15, 17), et - l'assemblage desdites pièces magnétiques (15, 17) pour former ledit circuit magnétique (9), dans lequel la fabrication d'au moins une desdites pièces magnétiques (15, 17) est mise en oeuvre par un procédé de fabrication selon l'une quelconque des revendications 1 à 9.A method of manufacturing a magnetic circuit (9) of a high sensitivity differential relay (5), said magnetic circuit (9) comprising two magnetic pieces (15, 17) forming a frame (17) and a pallet (15) , said method comprising: - manufacture of said magnetic parts (15, 17), and - assembling said magnetic pieces (15, 17) to form said magnetic circuit (9), wherein the manufacture of at least one of said magnetic pieces (15, 17) is carried out by a manufacturing method according to any one of claims 1 to 9. Pièce magnétique (15, 17) d'un circuit magnétique (9) d'un relais différentiel (5) à haute sensibilité, caractérisée en ce qu'elle est obtenue par un procédé de fabrication selon l'une quelconque des revendications 1 à 9.Magnetic part (15, 17) of a magnetic circuit (9) of a high-sensitivity differential relay (5), characterized in that it is obtained by a manufacturing method according to any one of Claims 1 to 9 . Circuit magnétique (9) d'un relais différentiel (5) à haute sensibilité, ledit circuit magnétique (9) comprenant deux pièces magnétiques (15, 17) formant une armature (17) et une palette (15), caractérisé en ce qu'au moins une desdites pièces magnétiques est une pièce magnétique selon la revendication 11.Magnetic circuit (9) of a high sensitivity differential relay (5), said magnetic circuit (9) comprising two magnetic parts (15, 17) forming a frame (17) and a pallet (15), characterized in that at least one of said magnetic pieces is a magnetic piece according to claim 11.
EP15163999.4A 2014-05-09 2015-04-17 Process for manufacturing a magnetic part of a differential relay comprising a surface treatment by shot-peening Active EP2942792B1 (en)

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EP0889488A1 (en) * 1997-07-04 1999-01-07 Imphy S.A. Soft magnetic alloy of the Fe-Ni-Cr-Ti type for magnetic circuit of a high sensitive relay
WO2012105913A1 (en) * 2011-02-04 2012-08-09 Eti Elektroelement D.D. Electromagnetic relay, in particular for interruption of an electric circuit in the cases of differential circuit, and a switch comprising such relay
US20130000797A1 (en) * 2011-07-01 2013-01-03 Vacuumschmelze Gmbh & Co. Kg Soft magnetic alloy and method for producing a soft magnetic alloy

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