EP0407275B1 - Method of making workpieces, with excellent mechanical properties, from non-treated steel - Google Patents
Method of making workpieces, with excellent mechanical properties, from non-treated steel Download PDFInfo
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- EP0407275B1 EP0407275B1 EP90401879A EP90401879A EP0407275B1 EP 0407275 B1 EP0407275 B1 EP 0407275B1 EP 90401879 A EP90401879 A EP 90401879A EP 90401879 A EP90401879 A EP 90401879A EP 0407275 B1 EP0407275 B1 EP 0407275B1
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- steel
- heating
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 17
- 239000010959 steel Substances 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 44
- 238000010438 heat treatment Methods 0.000 claims abstract description 27
- 238000005480 shot peening Methods 0.000 claims description 9
- 230000006698 induction Effects 0.000 claims description 6
- 238000010422 painting Methods 0.000 claims description 6
- 229910000639 Spring steel Inorganic materials 0.000 claims description 4
- 238000007493 shaping process Methods 0.000 claims 5
- 230000005764 inhibitory process Effects 0.000 claims 3
- 239000006223 plastic coating Substances 0.000 claims 3
- 229910001566 austenite Inorganic materials 0.000 claims 2
- 229910001563 bainite Inorganic materials 0.000 claims 2
- 238000010791 quenching Methods 0.000 abstract description 29
- 230000000171 quenching effect Effects 0.000 abstract description 27
- 230000009466 transformation Effects 0.000 abstract description 4
- 238000007669 thermal treatment Methods 0.000 abstract 1
- 238000009434 installation Methods 0.000 description 8
- 238000001816 cooling Methods 0.000 description 7
- 230000000903 blocking effect Effects 0.000 description 6
- 238000005496 tempering Methods 0.000 description 5
- 239000003517 fume Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005422 blasting Methods 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 238000005541 quenching (cooling) Methods 0.000 description 2
- 101100008047 Caenorhabditis elegans cut-3 gene Proteins 0.000 description 1
- 239000002519 antifouling agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 239000000109 continuous material Substances 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- -1 vapors Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
- C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
Definitions
- the present invention relates to a process for manufacturing elastic function parts with high mechanical characteristics from untreated spring steel, comprising a succession of heat treatment and forming operations.
- this known method still has a certain number of drawbacks.
- it involves two temperature rise operations (austenitization heating before quenching, tempering after quenching).
- tempering after quenching the fact that the parts undergo cold forming or at least preforming, before any heating, it is impossible to carry out this heating on continuous material, for example strip.
- the subject of the present invention is a method of manufacturing parts with an elastic function in treated spring steel making it possible to produce parts of equivalent quality or even better than that obtained by the usual methods at a lower cost.
- the austenitization heating can advantageously be carried out in a fluidized bed bath or by induction, on continuous products (strips, crowns) or on blanks or pieces. It is also possible, within the framework of the invention, to carry out a cold preforming, before heating of austenitization, to give the parts a shape different from their final shape, in which case the warm forming carried out after heating of austenitization and isothermal quenching is intended above all to give the parts a more precise geometry and higher mechanical characteristics (thermomechanical treatment with lukewarm such as blocking in the case of springs).
- the conventional method of hot forming before quenching requires heating of the parts as a whole at a temperature markedly above the transformation point to take account of the cooling that the parts undergo during the hot forming operation and during transfers.
- the quenching operation (which gives the steel a bainitic structure) immediately follows the austenitization heating operation, the heat losses are very low and the lower heating temperature, since it is only used for quenching.
- the untreated part of the metal plays a complementary role for quenching and the rest of the operations, by heat diffusion.
- the replacement of the two quenching and tempering operations of the usual processes with isothermal quenching allows other significant energy savings.
- the energy to bring the part to the tempering temperature is removed.
- the holding time at the isothermal quenching temperature represents less than half of the holding time at the tempering temperature according to the usual methods.
- Most of the energy induced during austenitization is returned to the fluidized quench bath isothermal, which allows this energy to be reused, for example for heating buildings.
- the parts with bainitic structure are at a temperature higher than the martensite point, that is to say at a temperature of the order of 280-350 ° C. depending on the steel grades, and the residual energy that they contain can be used as and when the following operations are carried out warm (forming, blocking, prestressing, shot blasting, protection).
- the process according to the invention thus makes it possible to recover the major part of the energy provided during austenitization.
- Warm forming gives parts better precision and increases the mechanical characteristics of the finished product, notably promoting the blocking of dislocations induced during forming, due in particular to the increase in mobility of carbon atoms linked to temperature. Rapid heating followed by isothermal quenching eliminates any risk of decarburization.
- the successive operations of the process according to the invention are carried out in a precise order making it possible to make the most of the energy stored in the material.
- the choice of temperature for each operation aims to optimize the beneficial effects, in particular on a metallurgical level for shot peening and pre-forming (or blocking), and on the electrochemical level for anti-corrosion protection.
- the method according to the invention does not require the formation of a so-called bonding layer generally obtained by chemical combination (phosphating) with the metal to be protected, the formation of this bonding layer resulting in a decrease in the surface mechanical characteristics of the parts.
- the method according to the invention reduces the number of operations, in particular temperature rise and the temperature maintenance times.
- the installations necessary for the implementation of the method are therefore of reduced dimensions.
- the investments and the surface area required for an installation using the method according to the invention are divided by a factor of approximately five.
- the process according to the invention makes it possible to considerably reduce the work in progress.
- the outstanding amount is only 40 springs for the process according to the invention, while it is 1,200 in the conventional process.
- a few minutes are sufficient to empty the installation of its parts for implementing the process according to the invention.
- the process according to the invention eliminates all harmful fumes and vapors and makes work much less arduous.
- the process according to the invention eliminates all the releases (fumes, vapors, detergents, etc.) from the usual hot forming and oil quenching process.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Heat Treatment Of Articles (AREA)
- Heat Treatment Of Steel (AREA)
- Chemical Treatment Of Metals (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
La présente invention se rapporte à un procédé de fabrication de pièces à fonction élastique à hautes caractéristiques mécaniques à partir d'acier à ressorts non traité, comprenant une succession d'opérations de traitement thermique et de formage.The present invention relates to a process for manufacturing elastic function parts with high mechanical characteristics from untreated spring steel, comprising a succession of heat treatment and forming operations.
Les procédés classiques de fabrication de pièces en acier traité à partir d'acier non traité en barres, en bandes ou en couronnes, par exemple de ressorts, de barres stabilisatrices, d'attaches élastiques de rails de chemin de fer, comprennent un grand nombre d'opérations.Conventional methods of manufacturing steel parts treated from untreated steel in bars, strips or rings, for example springs, stabilizer bars, elastic fasteners of railway rails, include a large number of operations.
A titre d'exemple, on va donner ci-après les différentes opérations successives d'un procédé classique de fabrication de ressorts :
- dévidage des couronnes, dressage, écroutage et rectification,
- chauffage d'austénitisation dans un four à atmosphère,
- formage à chaud,
- trempe à l'huile,
- revenu dans un four,
- refroidissement,
- blocage,
- refroidissement à la température ambiante,
- grenaillage de précontrainte,
- revenu après grenaillage,
- protection (peinture ou plastification),
- cuisson ou réticulation,
- refroidissement à la température ambiante,
- contrôle.
- unwinding of crowns, dressing, peeling and grinding,
- austenitization heating in an atmosphere furnace,
- hot forming,
- oil quenching,
- returned to an oven,
- cooling,
- blocking,
- cooling to room temperature,
- shot peening,
- income after shot blasting,
- protection (painting or plasticization),
- baking or crosslinking,
- cooling to room temperature,
- control.
Ce procédé classique comprend en particulier un grand nombre de phases de variation de température dont chacune implique des dépenses d'énergie considérables et des installations coûteuses. Le formage à chaud et la trempe à l'huile sont par ailleurs des opérations qui ont lieu dans des conditions de travail et de sécurité difficiles. Enfin la trempe à l'huile est une opération génératrice de pollution par le dégagement de fumées et de vapeurs nocives et par le lavage auxquels les pièces doivent être soumises à la suite de la trempe à l'huile.This conventional process comprises in particular a large number of temperature variation phases, each of which involves considerable energy expenditure and costly installations. Hot forming and oil quenching are also operations that take place under difficult working and safety conditions. Finally, oil quenching is an operation generating pollution by the release of harmful fumes and vapors and by the washing to which the parts must be subjected following oil quenching.
Le procédé suivant la demande de brevet français n° 2 391 789 remédie déjà partiellement aux inconvénients énumérés ci-dessus. Ce procédé destiné notamment à la fabrication d'attaches de rails comprend les étapes suivantes :
- formage ou préformage à froid des pièces,
- chauffage d'austénitisation des pièces, de préférence dans un bain à lit fluidisé ou par induction,
- trempe des pièces dans un bain à lit fluidisé,
- revenu des pièces de préférence dans un bain à lit fluidisé,
- grenaillage,
- éventuellement formage final à froid des pièces,
- protection.
- cold forming or preforming of parts,
- heating of austenitization of the parts, preferably in a fluidized bed bath or by induction,
- soaking the parts in a fluidized bed bath,
- tempering of the parts preferably in a fluidized bed bath,
- shot blasting,
- possibly final cold forming of the parts,
- protection.
Toutefois, ce procédé connu présente encore un certain nombre d'inconvénients. En particulier, il implique deux opérations de montée en température (chauffage d'austénitisation avant trempe, revenu après trempe). Par ailleurs, du fait que les pièces subissent un formage ou au moins un préformage à froid, avant tout chauffage, il est impossible d'effectuer ce chauffage sur du matériau continu, par exemple en bande.However, this known method still has a certain number of drawbacks. In particular, it involves two temperature rise operations (austenitization heating before quenching, tempering after quenching). Furthermore, the fact that the parts undergo cold forming or at least preforming, before any heating, it is impossible to carry out this heating on continuous material, for example strip.
La présente invention a pour objet un procédé de fabrication de pièces à fonction élastique en acier à ressorts traité permettant de réaliser à moindre coût des pièces de qualité équivalente voire supérieure à celle obtenue par les procédés usuels.The subject of the present invention is a method of manufacturing parts with an elastic function in treated spring steel making it possible to produce parts of equivalent quality or even better than that obtained by the usual methods at a lower cost.
Le procédé conforme à l'invention de fabrication de pièces à fonction élastique à partir d'acier à ressort non traité comprend dans l'ordre les opérations successives suivantes :
- austénitisation totale par chauffage de l'acier à une température supérieure au point de transformation (austénitisation) pendant un temps suffisant,
- trempe isotherme dans un bain à lit fluidisé, immédiatement à la suite du chauffage d'austénitisation, pour transformer la structure austénitique de l'acier en structure bainitique totale,
- formage mécanique des pièces sous leur forme définitive en utilisant l'énergie thermique résiduelle des pièces.
- total austenitization by heating the steel to a temperature above the transformation point (austenitization) for a sufficient time,
- isothermal quenching in a fluidized bed bath, immediately following the austenitization heating, to transform the austenitic structure of the steel into a total bainitic structure,
- mechanical forming of the parts in their final form using the residual thermal energy of the parts.
Contrairement à un préjugé selon lequel seul un formage après chauffage d'austénitisation et trempe martensitique permettait d'obtenir des pièces à hautes caractéristiques, il s'est avéré de façon surprenante que les pièces obtenues par formage à tiède après trempe isotherme (structure bainitique) présentaient des caractéristiques mécaniques et géométriques (notamment tenue en fatigue, corrosion sous tension, précision, tolérances plus étroites) nettement améliorées.Contrary to a prejudice according to which only a formation after austenitization heating and martensitic quenching made it possible to obtain parts with high characteristics, it turned out surprisingly that the parts obtained by lukewarm forming after isothermal quenching (bainitic structure) exhibited mechanical and geometric characteristics (notably fatigue resistance, corrosion under stress, precision, tighter tolerances) significantly improved.
Dans le cadre de l'invention, le chauffage d'austénitisation peut se faire avantageusement en bain à lit fluidisé ou par induction, sur des produits continus (bandes, couronnes) ou sur des flans ou des lopins. Il est également possible, dans le cadre de l'invention, de procéder à un préformage à froid, avant chauffage d'austénitisation, pour donner aux pièces une forme différente de leur forme définitive, auquel cas le formage à tiède effectué après chauffage d'austénitisation et trempe isotherme est destiné surtout à conférer aux pièces une géométrie plus précise et des caractéristiques mécaniques plus élevées (traitement thermomécanique à tiède tel que blocage dans le cas de ressorts).In the context of the invention, the austenitization heating can advantageously be carried out in a fluidized bed bath or by induction, on continuous products (strips, crowns) or on blanks or pieces. It is also possible, within the framework of the invention, to carry out a cold preforming, before heating of austenitization, to give the parts a shape different from their final shape, in which case the warm forming carried out after heating of austenitization and isothermal quenching is intended above all to give the parts a more precise geometry and higher mechanical characteristics (thermomechanical treatment with lukewarm such as blocking in the case of springs).
Enfin, à la suite du formage à tiède, il est possible de procéder, dans le cadre de l'invention, sans nouvelle montée en température des pièces, à un grenaillage de précontrainte à tiède et à une protection à tiède (peinture avec cuisson, plastification), en bénéficiant de la chaleur résiduelle des pièces.Finally, following lukewarm forming, it is possible, within the framework of the invention, without further temperature rise in the parts, to a shot peening with lukewarm lukewarm and to a lukewarm protection (painting with cooking, plasticization), taking advantage of the residual heat of the rooms.
Les nombreux avantages du procédé conforme à l'invention peuvent être classés comme suit :The numerous advantages of the process according to the invention can be classified as follows:
Le procédé classique de formage à chaud avant trempe nécessite un chauffage des pièces dans leur totalité à une température nettement supérieure au point de transformation pour tenir compte du refroidissement que les pièces subissent pendant l'opération de formage à chaud et pendant les transferts.The conventional method of hot forming before quenching requires heating of the parts as a whole at a temperature markedly above the transformation point to take account of the cooling that the parts undergo during the hot forming operation and during transfers.
Dans le procédé conforme à l'invention, du fait que l'opération de trempe (qui donne à l'acier une structure bainitique) fait immédiatement suite à l'opération de chauffe d'austénitisation, les pertes de chaleur sont très faibles et la température de chauffage plus basse, puisqu'elle sert uniquement à réaliser la trempe.In the process according to the invention, since the quenching operation (which gives the steel a bainitic structure) immediately follows the austenitization heating operation, the heat losses are very low and the lower heating temperature, since it is only used for quenching.
Suivant le procédé conforme à l'invention, il n'est d'ailleurs nécessaire que de chauffer, donc de traiter la partie travaillante du métal, ce qui constitue un gain supplémentaire d'énergie.According to the process according to the invention, it is moreover only necessary to heat, therefore to treat the working part of the metal, which constitutes an additional gain in energy.
Il est à noter que dans ce cas, la partie non traitée du métal joue un rôle complémentaire pour la trempe et la suite des opérations, par diffusion de chaleur.It should be noted that in this case, the untreated part of the metal plays a complementary role for quenching and the rest of the operations, by heat diffusion.
Le choix du chauffage par induction ou en lit fluidisé permet de réaliser les échanges thermiques dans des espaces réduits, ce qui diminue sensiblement les pertes de l'installation en fonctionnement et les temps de démarrage et d'arrêt de l'installation, donc les pertes qui en découlent. Le remplacement de la trempe à l'huile par une trempe en lit fluidisé supprime la nécessité d'aspirer des fumées d'huile et celles de laver et de sécher les pièces. En plus de l'énergie que consomment ces opérations, on économise suivant l'invention le complément de chauffage nécessaire pour compenser les pertes dues aux opérations de la trempe à l'huile et du lavage.The choice of heating by induction or in a fluidized bed makes it possible to carry out heat exchanges in reduced spaces, which significantly reduces the losses of the installation in operation and the start-up and shutdown times of the installation, therefore the losses who as a result. The replacement of oil quenching by fluidized bed quenching eliminates the need to suck oil fumes and those to wash and dry the parts. In addition to the energy consumed by these operations, according to the invention, the additional heating necessary to compensate for the losses due to the oil quenching and washing operations is saved.
Le remplacement des deux opérations de trempe et de revenu des procédés usuels par la trempe isotherme permet d'autres importantes économies d'énergie. Ainsi, l'énergie pour amener la pièce à la température de revenu est supprimée. Le temps de maintien à la température de trempe isotherme représente moins de la moitié du temps de maintien à la température de revenu suivant les procédés usuels. La plus grande partie de l'énergie induite lors de l'austénitisation est restitué dans le bain fluidisé de trempe isotherme, ce qui permet de réutiliser cette énergie par exemple pour le chauffage des bâtiments.The replacement of the two quenching and tempering operations of the usual processes with isothermal quenching allows other significant energy savings. Thus, the energy to bring the part to the tempering temperature is removed. The holding time at the isothermal quenching temperature represents less than half of the holding time at the tempering temperature according to the usual methods. Most of the energy induced during austenitization is returned to the fluidized quench bath isothermal, which allows this energy to be reused, for example for heating buildings.
Au sortir de la trempe isotherme, les pièces à structure bainitique sont à une températures supérieure au point de martensite, soit à une température de l'ordre de 280-350°C selon les nuances d'acier, et l'énergie résiduelle qu'elles contiennent peut être utilisée au fur et à mesure des opérations suivantes effectuées à tiède (formage, blocage, précontrainte, grenaillage, protection).At the end of the isothermal quenching, the parts with bainitic structure are at a temperature higher than the martensite point, that is to say at a temperature of the order of 280-350 ° C. depending on the steel grades, and the residual energy that they contain can be used as and when the following operations are carried out warm (forming, blocking, prestressing, shot blasting, protection).
Le procédé conforme à l'invention permet ainsi de récupérer la majeure partie de l'énergie apportée lors de l'austénitisation.The process according to the invention thus makes it possible to recover the major part of the energy provided during austenitization.
Le formage à tiède confère aux pièces une meilleure précision et augmente les caractéristiques mécaniques du produit fini en favorisant notablement le blocage des dislocations induites au cours du formage, en raison notamment de l'augmentation de la mobilité des atomes de carbone liée à la température. Le chauffage rapide suivi de la trempe isotherme supprime tout risque de décarburation.Warm forming gives parts better precision and increases the mechanical characteristics of the finished product, notably promoting the blocking of dislocations induced during forming, due in particular to the increase in mobility of carbon atoms linked to temperature. Rapid heating followed by isothermal quenching eliminates any risk of decarburization.
Les opérations successives du procédé conforme à l'invention sont effectuées dans un ordre précis permettant de bénéficier au maximum de l'énergie emmagasinée dans la matière. Le choix de la température pour chaque opération vise à optimiser les effets bénéfiques notamment sur un plan métallurgique pour le grenaillage de précontrainte et la préconformation (ou blocage), et sur le plan électrochimique pour la protection anticorrosion. En effet, contrairement aux procédés usuels, le procédé conforme à l'invention ne nécessite pas la formation d'une couche dite d'accrochage obtenue généralement par combinaison chimique (phosphatation) avec le métal à protéger, la formation de cette couche d'accrochage entraînant une diminution des caractéristiques mécaniques superficielles des pièces.The successive operations of the process according to the invention are carried out in a precise order making it possible to make the most of the energy stored in the material. The choice of temperature for each operation aims to optimize the beneficial effects, in particular on a metallurgical level for shot peening and pre-forming (or blocking), and on the electrochemical level for anti-corrosion protection. In fact, unlike the usual methods, the method according to the invention does not require the formation of a so-called bonding layer generally obtained by chemical combination (phosphating) with the metal to be protected, the formation of this bonding layer resulting in a decrease in the surface mechanical characteristics of the parts.
La suppression de l'opération de trempe à l'huile et son remplacement par une trempe en bain à lit fluidisé économisent la consommation de produits pétroliers comme l'huile de trempe et les produits et l'eau de lavage. Dans la mesure où le procédé conforme à l'invention procure des pièces de meilleure qualité, il permet de réduire la quantité de matière nécessaire à une même fonction. D'un autre côté, il est possible d'utiliser, suivant l'invention, des aciers moins alliés pour obtenir des pièces ayant des caractéristiques comparables.The elimination of the oil quenching operation and its replacement by quenching in a fluidized bed bath saves the consumption of petroleum products such as quench oil and washing products and water. Insofar as the process according to the invention provides better quality parts, it makes it possible to reduce the quantity of material necessary for the same function. On the other hand, it is possible, according to the invention, to use less alloyed steels in order to obtain parts having comparable characteristics.
La possibilité d'utiliser le métal brut de laminage et en couronnes entraîne une réduction importante des pertes de matière et du prix de la matière première.The possibility of using raw rolling and crown metal results in a significant reduction in material losses and the price of the raw material.
Le procédé conforme à l'invention réduit le nombre des opérations notamment de montée en température et les temps de maintien en température. Les installations nécessaires pour la mise en oeuvre du procédé sont donc de dimensions réduites.The method according to the invention reduces the number of operations, in particular temperature rise and the temperature maintenance times. The installations necessary for the implementation of the method are therefore of reduced dimensions.
A titre d'exemple, les investissements et la surface nécessaire pour une installation utilisant le procédé conforme à l'invention, compararativement à une installation classique pour produire des ressorts de suspension de véhicules automobiles, sont divisés par un facteur d'environ cinq.By way of example, the investments and the surface area required for an installation using the method according to the invention, compared with a conventional installation for producing suspension springs for motor vehicles, are divided by a factor of approximately five.
Le procédé conforme à l'invention permet de réduire considérablement les encours de fabrication. Ainsi, pour une production de 600 ressorts de suspension à l'heure, l'encours n'est que de 40 ressorts pour le procédé conforme à l'invention, alors qu'il est de 1200 dans le procédé classique. Quelques minutes suffisent pour vider de ses pièces l'installation pour la mise en oeuvre du procédé conforme à l'invention.The process according to the invention makes it possible to considerably reduce the work in progress. Thus, for a production of 600 suspension springs per hour, the outstanding amount is only 40 springs for the process according to the invention, while it is 1,200 in the conventional process. A few minutes are sufficient to empty the installation of its parts for implementing the process according to the invention.
Grâce à la suppression de la trempe à l'huile et grâce au formage à tiède, le procédé conforme à l'invention supprime toutes les fumées et vapeurs nocives et rend le travail beaucoup moins pénible.Thanks to the elimination of oil quenching and thanks to lukewarm forming, the process according to the invention eliminates all harmful fumes and vapors and makes work much less arduous.
La propreté des installations pour la mise en oeuvre du procédé conforme à l'invention et leurs dimensions réduites procurent une qualité d'ambiance de travail et une productivité de loin supérieures à celles du procédé classique.The cleanliness of the facilities for implementing the process according to the invention and their reduced dimensions provide a quality of working atmosphere and productivity far superior to those of the conventional process.
Le procédé conforme à l'invention supprime tous les rejets (fumées, vapeurs, produits de lavage, etc.) du procédé usuel de formage à chaud et de trempe à l'huile.The process according to the invention eliminates all the releases (fumes, vapors, detergents, etc.) from the usual hot forming and oil quenching process.
On va décrire ci-après la succession des opérations, avec indication des températures et des temps nécessaires, pour un procédé classique de fabrication de ressorts et, à titre de comparaison, un exemple du procédé conforme à l'invention pour la fabrication de ressorts de caractéristiques comparables destinés aux suspensions de véhicules automobiles.The sequence of operations will be described below, with indication of the temperatures and times required, for a conventional method of manufacturing springs and, by way of comparison, an example of the method according to the invention for the manufacture of springs of comparable characteristics intended for the suspension of motor vehicles.
Claims (10)
- Production method for work pieces having an elastic function, from non-treated spring steel, comprising the following steps in the stated order:- Heating up to a determined temperature and during a sufficient period of time for effecting austenitization in order to impart a total austenite structure to the steel;- isothermal hardening in a fluidized bed at a determined temperature and during a determined period of time, in order to completely transform the austenite structure of the steel into a total bainite structure; and- as soon as the total bainite structure is achieved, a mechanical shaping, in order to form the steel into the definitive shape of the work piece, utilizing the residual thermal energy of the work pieces.
- Method in accordance with claim 1, characterized in that it comprises, prior to heating for austenitization, a cold pre-shaping of the steel, in order to give a shape to the spring parts, which differs from the final shape.
- Method in accordance with claims 1 or 2, characterized in that the heating for austenitization is carried out in a fluidized bed.
- Method in accordance with claim 1 or 2, characterized in that the heating for austenitization is carried out by means of induction.
- Method in accordance with anyone of the above claims, characterized in that it comprises furthermore a prestress inhibition which is carried out following the mechanical shaping, utilizing the residual thermal energy of the work pieces.
- Method in accordance with anyone of the claims 1 through 4, characterized in that it comprises furthermore a process of prestress shot-peening carried out on the work pieces following the shaping process, utilizing the residual thermal energy of the work pieces.
- Method in accordance with claim 5, characterized in that it comprises furthermore a process of prestress shot-peening carried out on the work pieces following a prestress inhibition, utilizing the residual thermal energy of the work pieces.
- Method in accordance with anyone of the claims 1 through 4, characterized in that it comprises furthermore an operation (painting, plastic coating) for the protection of the work pieces, carried out following the shaping, utilizing the residual thermal energy of the work pieces.
- Method in accordance with claim 5, characterized in that it comprises furthermore an operation (painting, plastic coating) for the protection of the work pieces, carried out following the prestress inhibition, utilizing the residual thermal energy of the work pieces.
- Method in accordance with claim 6, characterized in that it comprises furthermore an operation (painting, plastic coating) for the protection of the work pieces, carried out following the prestress shot-peening, utilizing the residual thermal energy of the work pieces.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8909189 | 1989-07-07 | ||
| FR8909189A FR2649415B1 (en) | 1989-07-07 | 1989-07-07 | PROCESS FOR MANUFACTURING PARTS WITH HIGH MECHANICAL CHARACTERISTICS FROM UNTREATED STEEL |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0407275A1 EP0407275A1 (en) | 1991-01-09 |
| EP0407275B1 true EP0407275B1 (en) | 1994-12-14 |
Family
ID=9383594
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90401879A Expired - Lifetime EP0407275B1 (en) | 1989-07-07 | 1990-06-29 | Method of making workpieces, with excellent mechanical properties, from non-treated steel |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0407275B1 (en) |
| JP (1) | JPH0353018A (en) |
| AT (1) | ATE115638T1 (en) |
| CA (1) | CA2020595C (en) |
| DE (1) | DE69015028T2 (en) |
| ES (1) | ES2068354T3 (en) |
| FR (1) | FR2649415B1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0593225A (en) * | 1991-09-30 | 1993-04-16 | Nissan Motor Co Ltd | Cast iron gear manufacturing method |
| CA2804707C (en) * | 2010-06-24 | 2016-05-10 | Magna International Inc. | Tailored properties by post hot forming processing |
| DE102010027179B3 (en) * | 2010-07-14 | 2011-11-10 | Benteler Automobiltechnik Gmbh | Production of automotive components e.g. structural/body parts of a car, comprises heating metal part in fluidized bed and subjecting metal part to forming, hardening or aging process, and forming metal part in warm state |
| JP5662903B2 (en) | 2010-11-18 | 2015-02-04 | 株式会社神戸製鋼所 | High-strength steel sheet with excellent formability, warm working method, and warm-worked automotive parts |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3240634A (en) * | 1964-07-23 | 1966-03-15 | Lasalle Steel Co | Steels and improved method of manufacture |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1543101A (en) * | 1967-10-30 | 1968-10-18 | British Iron And Steel | Thermo-mechanical treatment of steel |
| US4088511A (en) * | 1976-07-29 | 1978-05-09 | Lasalle Steel Company | Steels combining toughness and machinability |
| FR2391789A1 (en) * | 1977-05-25 | 1978-12-22 | Renault | Cold forgings, esp. railway rail clips - made from coiled metal strip and locally heat treated in fluidised beds |
| FR2448573A1 (en) * | 1979-02-06 | 1980-09-05 | Physique Appliquee Ind | Continuous automatic heat treatment plant - using row of fluidised beds, esp. for isothermal treatment of steel in absence of air |
-
1989
- 1989-07-07 FR FR8909189A patent/FR2649415B1/en not_active Expired - Lifetime
-
1990
- 1990-06-29 DE DE69015028T patent/DE69015028T2/en not_active Expired - Fee Related
- 1990-06-29 ES ES90401879T patent/ES2068354T3/en not_active Expired - Lifetime
- 1990-06-29 AT AT90401879T patent/ATE115638T1/en not_active IP Right Cessation
- 1990-06-29 EP EP90401879A patent/EP0407275B1/en not_active Expired - Lifetime
- 1990-07-06 CA CA002020595A patent/CA2020595C/en not_active Expired - Lifetime
- 1990-07-06 JP JP2179421A patent/JPH0353018A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3240634A (en) * | 1964-07-23 | 1966-03-15 | Lasalle Steel Co | Steels and improved method of manufacture |
Also Published As
| Publication number | Publication date |
|---|---|
| ES2068354T3 (en) | 1995-04-16 |
| JPH0353018A (en) | 1991-03-07 |
| FR2649415A1 (en) | 1991-01-11 |
| ATE115638T1 (en) | 1994-12-15 |
| CA2020595C (en) | 2001-07-03 |
| DE69015028D1 (en) | 1995-01-26 |
| EP0407275A1 (en) | 1991-01-09 |
| CA2020595A1 (en) | 1991-01-08 |
| DE69015028T2 (en) | 1995-07-20 |
| FR2649415B1 (en) | 1991-10-31 |
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