EP0404674A1 - Process and device for improving the fatigue resistance of helicoidal springs under compression and springs obtained by this process - Google Patents

Process and device for improving the fatigue resistance of helicoidal springs under compression and springs obtained by this process Download PDF

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Publication number
EP0404674A1
EP0404674A1 EP90401744A EP90401744A EP0404674A1 EP 0404674 A1 EP0404674 A1 EP 0404674A1 EP 90401744 A EP90401744 A EP 90401744A EP 90401744 A EP90401744 A EP 90401744A EP 0404674 A1 EP0404674 A1 EP 0404674A1
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EP
European Patent Office
Prior art keywords
spring
shot
rotor
blasting
internal surfaces
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP90401744A
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German (de)
French (fr)
Inventor
Michel Duchemin
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Allevard Industries SA
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Allevard Industries SA
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Publication of EP0404674A1 publication Critical patent/EP0404674A1/en
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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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/10—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C3/00—Abrasive blasting machines or devices; Plants
    • B24C3/32—Abrasive blasting machines or devices; Plants designed for abrasive blasting of particular work, e.g. the internal surfaces of cylinder blocks

Definitions

  • the present invention relates to a method and a device for improving, by shot peening, the fatigue resistance of helical springs and more particularly of compression helical springs.
  • Shot blasting is a surface treatment process which involves projecting shot against the surface to be treated.
  • the fatigue resistance of metal parts can be improved by this process, provided that the shot is well rounded, that it is thrown at high speed and that the impacts fully cover the stressed surfaces of the part to be treated.
  • Each impact of shot on the surface of the part produces a deformation which generates internal compression tensions, which hardens the metal and which attenuates the possible small irregularities. All these effects contribute to increasing the resistance to the weariness of the part, provided that no portion of the stressed surface is forgotten.
  • the internal tensions which will subsequently compensate for the constraints of use can be increased if the part is shot blasted, under tension, in a stress state similar to that which it will support in service. The increase is all the more noticeable as the tension of the metal during shot peening is higher.
  • the maximum efficiency of a coil spring is obtained by making its entire surface work at maximum stresses.
  • the internal shot blasting tensions make it possible to increase the value of the admissible stresses in service and therefore the efficiency of the spring, but the orientation in all directions of the surface of the helical spring makes it difficult to carry out shot blasting.
  • the most commonly used method which consists in displacing the spring under a conical jet of shot projected at high speed by a turbine does not allow reach all surfaces and in particular the internal surfaces of the spring only if the turns are sufficiently spaced. If it is a helical compression spring that is to be shot blasted under high tension, the covering of the internal surfaces by the impacts of shot is not sufficient to bring about a significant improvement.
  • the internal surfaces of the spring can be defined as those which constitute the internal wall of the spring when the latter has contiguous turns.
  • a method of shot blasting generally used for cleaning consists in entraining the shot in a jet of compressed air. This method is sometimes also used to improve resistance to fatigue, by reducing the diameter of the jet outlet nozzle so that its speed is substantially the same as that obtained with shot blasted by a turbine.
  • the angle at the top of the cone formed by the shot of shot becomes very sharp and the impact surface covered by the shot very narrow. As a result, it takes a long time to blast a coil spring.
  • a part of the surfaces being reached only by a tangential jet is not subjected to sufficiently strong internal tensions and constitutes a zone of weakness likely to be the seat of a subsequent rupture.
  • Japanese patent published under number 56-107880 gives an example of the application of this method.
  • two nozzles one inside and the other outside the spring, are driven in an alternating translational movement parallel to the axis of the spring by projecting shot against the compressed spring and rotated simultaneously.
  • shot is always projected in the same direction, it follows that not all surfaces receive the same intensity of shot; some being reached that tangentially are therefore only subject to low internal tensions and will be therefore the seat of breaking points.
  • DE 3,711,826 describes a device for peening cylindrical parts on their internal wall by means of a direct shot projection member, said member being movable in translation and / or in rotation inside the piece but without changing tilt, relative to the axis of the spring.
  • the shot should hit the spring at all points perpendicular to its surface and therefore the turns should be very far apart, which would exclude shot blasting under tension from a compression spring.
  • the spring In order for the spring to acquire the maximum internal tension, it should be shot peened in the highest possible stress state, i.e. be compressed with contiguous turns, but then the contact surfaces between turns would not be blasted and would constitute zones of weakness likely to constitute a starting point of rupture.
  • the object of the present invention is to produce high performance helical compression springs capable of withstanding without damage high stress amplitudes leading the spring to a state of almost contiguous turns.
  • the external surfaces of the spring which are less stressed in service than the internal surfaces, do not need to be blasted as much.
  • the spring is compressed with contiguous or almost contiguous turns during the shot blasting but it is however necessary to leave enough passage for the shot between the turns of the spring.
  • the internal surfaces of the spring acquire better resistance to fatigue when they are blasted with contiguous turns.
  • a device for improving the fatigue resistance of a helical compression spring by shot blasting of the surfaces comprising a shot distributor and a movable shot projection member disposed coaxially inside said spring and means for compressing said spring, characterized in that said movable shot projection member comprises a cylindrical rotor whose l the axis is substantially vertical during shot blasting and which is provided on its side wall with peripheral fins adapted to project the shot from the distributor against the internal surfaces of the spring as a function of the speed of rotation
  • the rotor is at variable speed.
  • said peripheral fins are divided into two series, one of which extends parallel to the vertical axis of said rotor and the other extends obliquely with respect to said vertical axis.
  • the shot dispenser comprises a substantially horizontal upper plate mounted above the rotor and comprising, at its lower part, a housing adapted to receive in support contact the end upper spring and at least one shot distribution duct.
  • Another object of the invention is a method of improving the fatigue resistance of a helical compression spring comprising in particular the blasting of the internal surfaces of the spring, characterized in that the blasting is carried out by shot deviated to inside the spring and projected in different directions by a rotor.
  • the shot peening is carried out inside the spring, so that the internal surfaces of the spring are struck at least directly and perpendicularly by said shot.
  • said spring is maintained at least partially in the compressed state.
  • said spring is gradually compressed during shot-blasting until the state of almost contiguous turns.
  • said spring is kept compressed during shot peening in the form of almost contiguous turns.
  • Yet another object of the invention is a helical compression spring having improved fatigue resistance and obtained by the method of the invention.
  • the internal surfaces of the spring are advantageously blasted by jets of shot differently oriented so that all the points of these surfaces are struck at least once during shot blasting from an effective angle.
  • the device of the invention as shown in Figure 1 comprises a shot dispenser 2 and a movable member 3 of shot projection disposed inside the spring 1 coaxially with respect to said spring.
  • the device of the invention also includes means for compressing the spring 1 so as to gradually make its contiguous or almost contiguous turns during the peening.
  • the mobile shot projection member 3 comprises a cylindrical rotor 5 with variable speed.
  • the common axis of the rotor and the spring is substantially vertical during the blasting.
  • the rotor 5 is provided on its side wall included inside the spring 1, with two series of peripheral fins 6, 7, one of which 6 extends parallel to the axis vertical of said rotor 5 and the other 7 extends obliquely relative to said vertical axis. These fins 6, 7 are adapted to deflect and project the shot from the distributor 2 in all directions against the internal surfaces of the spring 1 as a function of the speed of rotation.
  • the shot dispenser 2 comprises a substantially horizontal upper plate 8 mounted above the rotor 5 and comprising at its lower part a housing 9 adapted to receive in contact with support the upper end of the spring 1 and at least one conduit 10 of shot distribution.
  • the conduit 10 as shown in Figure 1 is formed in the mass of the upper plate 8 in the form of a frustoconical recess whose side faces are inclined to allow a gradual flow by gravity of the shot.
  • the compression means of the spring 1 are constituted by the upper plate 8 actuated in the vertical direction by a set of hydraulic cylinders 11 and by a lower plate 12 supporting and wedging the lower end of the spring 1.
  • the rotor 5 is preferably moved at variable speed by a motor 13 mounted coaxially on the upper plate 8.
  • the helical compression spring 1 is therefore compressed either gradually or in a single phase between the two plates 8 and 12 before or during the peening operation by means of the hydraulic cylinders 11 and the positioning of the spring 1 between the plates 8 , 12 is done prior to the introduction of the rotor 5 coaxially at the center of the spring 1.
  • the blasting is carried out, according to the method of the invention, inside the spring in all the angular directions, so that the internal surfaces are struck at least directly and perpendicularly by said shot, that is to say along the normal to each of these surfaces.
  • This operation is carried out by first supplying the distributor 2 with shot and by putting the rotor 5 in rotation by means of the motor 13.
  • the shot flows by gravity inside the conduits 10, falls inside the spring 1 where it is struck and deflected by the peripheral fins 6, 7 of the moving rotor 5.
  • the subsequent kinetics of the shot depend on the speed of the rotor and the type of fin with which the impact takes place.
  • the shot blasting of the external surfaces of the spring 1 is carried out in a known manner and independently of the shot blasting of the internal surfaces described above.
  • the shot peening process according to the invention applies not only to cylindrical springs in round wire but also to all coiled springs and in particular to conical springs or springs with variable winding diameter, to springs with variable pitch, to springs in wire conical or of variable wire diameter, with square, rectangular or any section wire springs and produces springs with resistance to exceptional fatigue.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Springs (AREA)

Abstract

The invention relates to a device for improving the fatigue resistance of a helical compression spring (1) by the shot-blasting of the inner surfaces of said spring, comprising a shot distributor (2) and a moveable shot-projecting member (3) arranged coaxially within said spring and means for the compression of said spring, characterised in that said moveable shot-projecting member (3) comprises a cylindrical rotor (5), the axis of which is substantially vertical during the shot-blasting and which is equipped on its lateral wall with peripheral blades (6, 7) designed to project the shot coming from the distributor (2) against the inner surfaces of the spring as a function of the rotational speed. <IMAGE>

Description

La présente invention concerne un procédé et un dispositif pour améliorer, par grenaillage, la résistance à la fatigue des ressorts hélicoïdaux et plus particulièrement des ressorts hélicoïdaux de compression.The present invention relates to a method and a device for improving, by shot peening, the fatigue resistance of helical springs and more particularly of compression helical springs.

Le grenaillage est un procédé de traitement de surface qui consiste à projeter de la grenaille contre la surface à traiter. La résistance à la fatigue des pièces métalliques peut être améliorée par ce procédé, à condition que la grenaille soit bien arrondie, qu'elle soit projetée à grande vitesse et que les impacts couvrent entièrement les surfaces sollicitées de la pièce à traiter. Chaque impact de grenaille sur la surface de la pièce y produit une déformation qui engendre des tensions internes de compression, qui écrouit le métal et qui atténue les petites irrégularités éventuelles. Tous ces effets contribuent à augmenter la résistance à la fatique de la pièce, à condition qu'aucune portion de surface sollicitée ne soit oubliée.Shot blasting is a surface treatment process which involves projecting shot against the surface to be treated. The fatigue resistance of metal parts can be improved by this process, provided that the shot is well rounded, that it is thrown at high speed and that the impacts fully cover the stressed surfaces of the part to be treated. Each impact of shot on the surface of the part produces a deformation which generates internal compression tensions, which hardens the metal and which attenuates the possible small irregularities. All these effects contribute to increasing the resistance to the weariness of the part, provided that no portion of the stressed surface is forgotten.

Les tensions internes qui viendront, par la suite, compenser les contraintes d'utilisation, peuvent être augmentées si la pièce est grenaillée, sous tension, dans un état de contraintes analogue à celui qu'elle supportera en service. L'augmentation est d'autant plus sensible que la tension du métal pendant le grenaillage est plus forte.The internal tensions which will subsequently compensate for the constraints of use can be increased if the part is shot blasted, under tension, in a stress state similar to that which it will support in service. The increase is all the more noticeable as the tension of the metal during shot peening is higher.

L'efficacité maximum d'un ressort hélicoîdal est obtenue en faisant travailler toute sa surface aux contraintes maximales.The maximum efficiency of a coil spring is obtained by making its entire surface work at maximum stresses.

Les tensions internes de grenaillage permettent d'augmenter la valeur des contraintes admissibles en service et donc l'efficacité du ressort, mais l'orientation dans toutes les directions de la surface du ressort hélicoïdal rend difficile la mise en oeuvre du grenaillage. La méthode la plus couramment utilisée qui consiste à déplacer le ressort sous un jet conique de grenaille projetée à grande vitesse par une turbine ne permet d'atteindre toutes les surfaces et en particulier les surfaces internes du ressort que si les spires sont suffisamment espacées. S'il s'agit d'un ressort hélicoîdal de compression que l'on veut grenailler sous forte tension , le recouvrement des surfaces internes par les impacts de grenaille n'est pas suffisant pour y apporter une amélioration sensible.The internal shot blasting tensions make it possible to increase the value of the admissible stresses in service and therefore the efficiency of the spring, but the orientation in all directions of the surface of the helical spring makes it difficult to carry out shot blasting. The most commonly used method which consists in displacing the spring under a conical jet of shot projected at high speed by a turbine does not allow reach all surfaces and in particular the internal surfaces of the spring only if the turns are sufficiently spaced. If it is a helical compression spring that is to be shot blasted under high tension, the covering of the internal surfaces by the impacts of shot is not sufficient to bring about a significant improvement.

Les surfaces internes du ressort peuvent être définies comme étant celles qui constituent la paroi interne du ressort lorsque celui-ci est à spires jointives.The internal surfaces of the spring can be defined as those which constitute the internal wall of the spring when the latter has contiguous turns.

Les surfaces comprises entre les spires ne sont que peu soumises à des tensions internes puisqu'elles ne reçoivent que des impacts tangentiels de grenaille.The surfaces between the turns are only slightly subjected to internal tensions since they only receive tangential impacts from shot.

Une méthode de grenaillage utilisée généralement pour le nettoyage consiste à entraîner la grenaille dans un jet d'air comprimé. Cette méthode est parfois utilisée aussi pour améliorer la résistance à la fatigue, en diminuant le diamètre de l'ajutage de sortie du jet pour que sa vitesse soit sensiblement la même que celle obtenue avec de la grenaille projetée par une turbine. L'angle au sommet du cône formé par le jet de grenaille devient très aigu et la surface d'impact couverte par le jet très étroite. Par suite, il faut beaucoup de temps pour grenailler un ressort hélicoïdal. De plus, une partie des surfaces n'étant atteinte que par un jet tangentiel, n'est pas soumise à des tensions internes suffisamment fortes et constitue une zone de faiblesse susceptible d'être le siège d'une rupture ultérieure.A method of shot blasting generally used for cleaning consists in entraining the shot in a jet of compressed air. This method is sometimes also used to improve resistance to fatigue, by reducing the diameter of the jet outlet nozzle so that its speed is substantially the same as that obtained with shot blasted by a turbine. The angle at the top of the cone formed by the shot of shot becomes very sharp and the impact surface covered by the shot very narrow. As a result, it takes a long time to blast a coil spring. In addition, a part of the surfaces being reached only by a tangential jet, is not subjected to sufficiently strong internal tensions and constitutes a zone of weakness likely to be the seat of a subsequent rupture.

Le brevet japonais publié sous le numéro 56-107880 donne un exemple d'application de cette méthode. Pour gagner du temps deux buses, l'une à l'intérieur, l'autre à l'extérieur du ressort sont animées d'un mouvement de translation alternatif parallèlement à l'axe du ressort en projetant de la grenaille contre le ressort comprimé et animé simultanément d'un mouvement de rotation. La grenaille étant toujours projetée dans la même direction, il en résulte que toutes les surfaces ne reçoivent pas la même intensité de grenaillage ; certaines en étant atteintes que tangentiellement ne sont donc soumises qu'à de faibles tensions internes et seront donc le siège d'amorces de rupture.Japanese patent published under number 56-107880 gives an example of the application of this method. To save time, two nozzles, one inside and the other outside the spring, are driven in an alternating translational movement parallel to the axis of the spring by projecting shot against the compressed spring and rotated simultaneously. As the shot is always projected in the same direction, it follows that not all surfaces receive the same intensity of shot; some being reached that tangentially are therefore only subject to low internal tensions and will be therefore the seat of breaking points.

Le DE 3 711 826 décrit un dispositif de grenaillage de pièces cylindriques sur leur paroi interne au moyen d'un organe de projection directe de grenaille, ledit organe étant mobile en translation et/ou en rotation à l'intérieur de la pièce mais sans changer d'inclinaison, par rapport à l'axe du ressort.DE 3,711,826 describes a device for peening cylindrical parts on their internal wall by means of a direct shot projection member, said member being movable in translation and / or in rotation inside the piece but without changing tilt, relative to the axis of the spring.

Que la grenaille soit projetée par une turbine ou entraînée par un courant d'air comprimé, les tensions internes que l'on applique au ressort ne sont jamais uniformément réparties et font l'objet d'un compromis entre deux exigences contradictoires.Whether the shot is thrown by a turbine or driven by a stream of compressed air, the internal tensions that are applied to the spring are never uniformly distributed and are the subject of a compromise between two contradictory requirements.

Pour que le grenaillage soit efficace, il faudrait que la grenaille frappe en tous points le ressort perpendiculairement à sa surface et donc que les spires soient très écartées, ce qui excluerait le grenaillage sous tension d'un ressort de compression.For the shot blasting to be effective, the shot should hit the spring at all points perpendicular to its surface and therefore the turns should be very far apart, which would exclude shot blasting under tension from a compression spring.

Pour que le ressort acquiert le maximum de tensions internes, il devrait être grenaillé dans l'état de contrainte le plus élevé possible, c'est-à-dire être comprimé à spires jointives, mais alors les surfaces de contact entre spires ne seraient pas grenaillées et constitueraient des zones de faiblesse susceptibles de constituer une amorce de rupture.In order for the spring to acquire the maximum internal tension, it should be shot peened in the highest possible stress state, i.e. be compressed with contiguous turns, but then the contact surfaces between turns would not be blasted and would constitute zones of weakness likely to constitute a starting point of rupture.

La présente invention a pour but de réaliser des ressorts hélicoïdaux de compression à hautes performances capables de résister sans dommage à de fortes amplitudes de contraintes conduisant le ressort à un état de spires presque jointives.The object of the present invention is to produce high performance helical compression springs capable of withstanding without damage high stress amplitudes leading the spring to a state of almost contiguous turns.

Les surfaces externes du ressort, qui sont moins sollicitées en service que les surfaces internes, n'ont pas besoin d'être autant grenaillées. Le ressort est comprimé à spires jointives ou presque jointives pendant le grenaillage mais il est cependant nécessaire de laisser assez de passage à la grenaille entre les spires du ressort. En revanche, les surfaces internes du ressort acquièrent une meilleure résistance à la fatigue quand elles sont grenaillées à spires jointives.The external surfaces of the spring, which are less stressed in service than the internal surfaces, do not need to be blasted as much. The spring is compressed with contiguous or almost contiguous turns during the shot blasting but it is however necessary to leave enough passage for the shot between the turns of the spring. On the other hand, the internal surfaces of the spring acquire better resistance to fatigue when they are blasted with contiguous turns.

Ce but est atteint conformément à l'invention au moyen d'un dispositif pour améliorer la résistance à la fatigue d'un ressort hélicoïdal de compression par grenaillage des surfaces internes dudit ressort, comprenant un distributeur de grenaille et un organe mobile de projection de grenaille disposé coaxialement à l'intérieur dudit ressort et des moyens de compression dudit ressort, caractérisé en ce que ledit organe mobile de projection de grenaille comprend un rotor cylindrique dont l'axe est sensiblement vertical pendant le grenaillage et qui est pourvu sur sa paroi latérale d'ailettes périphériques adaptées pour projeter la grenaille provenant du distributeur contre les surfaces internes du ressort en fonction de la vitesse de rotationThis object is achieved in accordance with the invention by means of a device for improving the fatigue resistance of a helical compression spring by shot blasting of the surfaces. internal of said spring, comprising a shot distributor and a movable shot projection member disposed coaxially inside said spring and means for compressing said spring, characterized in that said movable shot projection member comprises a cylindrical rotor whose l the axis is substantially vertical during shot blasting and which is provided on its side wall with peripheral fins adapted to project the shot from the distributor against the internal surfaces of the spring as a function of the speed of rotation

Selon une caractéristique de l'invention, le rotor est à vitesse variable.According to a characteristic of the invention, the rotor is at variable speed.

Selon une autre caractéristique du procédé de l'invention, lesdites ailettes périphériques sont réparties en deux séries dont l'une s'étend parallèlement à l'axe vertical dudit rotor et l'autre s'étend obliquement par rapport audit axe vertical.According to another characteristic of the method of the invention, said peripheral fins are divided into two series, one of which extends parallel to the vertical axis of said rotor and the other extends obliquely with respect to said vertical axis.

Selon un autre aspect du dispositif de l'invention, le distributeur de grenaille comprend un plateau supérieur sensiblement horizontal monté au-dessus du rotor et comportant,au niveau de sa partie inférieure,un logement adapté pour recevoir en contact d'appui l'extrémité supérieure du ressort et au moins un conduit de distribution de grenaille.According to another aspect of the device of the invention, the shot dispenser comprises a substantially horizontal upper plate mounted above the rotor and comprising, at its lower part, a housing adapted to receive in support contact the end upper spring and at least one shot distribution duct.

Un autre objet de l'invention est un procédé d'amélioration de la résistance à la fatigue d'un ressort hélicoïdal de compression comprenant notamment le grenaillage des surfaces internes du ressort , caractérisé en ce que le grenaillage est réalisé par de la grenaille déviée à l'intérieur du ressort et projetée dans différentes directions par un rotor.Another object of the invention is a method of improving the fatigue resistance of a helical compression spring comprising in particular the blasting of the internal surfaces of the spring, characterized in that the blasting is carried out by shot deviated to inside the spring and projected in different directions by a rotor.

Selon une caractéristique du procédé de l'invention, le grenaillage est effectué à l'intérieur du ressort, de telle sorte que les surfaces internes du ressort soient percutées au moins directement et perpendiculairement par ladite grenaille.According to a characteristic of the process of the invention, the shot peening is carried out inside the spring, so that the internal surfaces of the spring are struck at least directly and perpendicularly by said shot.

Selon encore une autre caractéristique, ledit ressort est maintenu au moins partiellement à l'état comprimé.According to yet another characteristic, said spring is maintained at least partially in the compressed state.

Selon un autre aspect du procédé de l'invention, ledit ressort est comprimé progressivement pendant le grenaillage jusqu'à l'état de spires presque jointives.According to another aspect of the method of the invention, said spring is gradually compressed during shot-blasting until the state of almost contiguous turns.

Selon une variante du procédé, ledit ressort est maintenu comprimé pendant le grenaillage à l'état de spires presque jointives.According to a variant of the method, said spring is kept compressed during shot peening in the form of almost contiguous turns.

Encore un autre objet de l'invention est un ressort hélicoïdal de compression possédant une résistance à la fatigue améliorée et obtenu par le procédé de l'invention.Yet another object of the invention is a helical compression spring having improved fatigue resistance and obtained by the method of the invention.

Ainsi, selon la présente invention, les surfaces internes du ressort sont avantageusement grenaillées par des jets de grenaille différemment orientés de telle sorte que tous les points de ces surfaces sont au moins une fois durant le grenaillage percutés sous un angle efficace.Thus, according to the present invention, the internal surfaces of the spring are advantageously blasted by jets of shot differently oriented so that all the points of these surfaces are struck at least once during shot blasting from an effective angle.

Compte tenu de la compression progressive pendant le grenaillage, on obtient également un grenaillage efficace des faces en regard des spires au début de la compression par des jets pratiquement perpendiculaires à leurs surfaces.Given the progressive compression during shot peening, efficient shot peening of the opposite faces of the turns is also obtained at the start of compression by jets practically perpendicular to their surfaces.

La présente invention sera mieux comprise à la lecture de la description qui va suivre accompagnée du dessin annexé sur lequel :

  • La figure 1 représente une vue en coupe transversale du dispositif de l'invention.
The present invention will be better understood on reading the description which follows, accompanied by the appended drawing in which:
  • Figure 1 shows a cross-sectional view of the device of the invention.

Le dispositif de l'invention tel que représenté sur la figure 1 comprend un distributeur de grenaille 2 et un organe mobile 3 de projection de grenaille disposé à l'intérieur du ressort 1 de façon coaxiale par rapport audit ressort.The device of the invention as shown in Figure 1 comprises a shot dispenser 2 and a movable member 3 of shot projection disposed inside the spring 1 coaxially with respect to said spring.

Le dispositif de l'invention comprend également des moyens de compression du ressort 1 pour rendre progressivement pendant le grenaillage ses spires jointives ou presque jointives.The device of the invention also includes means for compressing the spring 1 so as to gradually make its contiguous or almost contiguous turns during the peening.

L'organe mobile de projection 3 de grenaille comprend un rotor cylindrique 5 à vitesse variable. De préférence, l'axe commun du rotor et du ressort est sensiblement vertical pendant le grenaillage. Le rotor 5 est pourvu sur sa paroi latérale comprise à l'intérieur du ressort 1, de deux séries d'ailettes périphériques 6, 7 dont l'une 6 s'étend parallèlement à l'axe vertical dudit rotor 5 et l'autre 7 s'étend obliquement par rapport audit axe vertical. Ces ailettes 6, 7, sont adaptées pour dévier et projeter la grenaille provenant du distributeur 2 dans toutes les directions contre les surfaces internes du ressort 1 en fonction de la vitesse de rotation.The mobile shot projection member 3 comprises a cylindrical rotor 5 with variable speed. Preferably, the common axis of the rotor and the spring is substantially vertical during the blasting. The rotor 5 is provided on its side wall included inside the spring 1, with two series of peripheral fins 6, 7, one of which 6 extends parallel to the axis vertical of said rotor 5 and the other 7 extends obliquely relative to said vertical axis. These fins 6, 7 are adapted to deflect and project the shot from the distributor 2 in all directions against the internal surfaces of the spring 1 as a function of the speed of rotation.

Le distributeur de grenaille 2 comprend un plateau supérieur 8 sensiblement horizontal monté au-dessus du rotor 5 et comportant au niveau de sa partie inférieure un logement 9 adapté pour recevoir en contact d'appui l'extrémité supérieure du ressort 1 et au moins un conduit 10 de distribution de grenaille.The shot dispenser 2 comprises a substantially horizontal upper plate 8 mounted above the rotor 5 and comprising at its lower part a housing 9 adapted to receive in contact with support the upper end of the spring 1 and at least one conduit 10 of shot distribution.

Le conduit 10 tel qu'il est représenté sur la figure 1, est réalisé dans la masse du plateau supérieur 8 sous la forme d'un évidement tronconique dont les faces latérales sont inclinées pour permettre un écoulement progressif par gravité de la grenaille.The conduit 10 as shown in Figure 1, is formed in the mass of the upper plate 8 in the form of a frustoconical recess whose side faces are inclined to allow a gradual flow by gravity of the shot.

Les moyens de compression du ressort 1 sont constitués par le plateau supérieur 8 actionné dans le sens vertical par un jeu de vérins hydrauliques 11 et par un plateau inférieur 12 supportant et calant l'extrémité inférieure du ressort 1.The compression means of the spring 1 are constituted by the upper plate 8 actuated in the vertical direction by a set of hydraulic cylinders 11 and by a lower plate 12 supporting and wedging the lower end of the spring 1.

Le rotor 5 est mû de préférence à vitesse variable par un moteur 13 monté coaxialement sur le plateau supérieur 8.The rotor 5 is preferably moved at variable speed by a motor 13 mounted coaxially on the upper plate 8.

Le ressort hélicoïdal de compression 1 est donc comprimé soit progressivement, soit en une seule phase entre les deux plateaux 8 et 12 avant ou pendant l'opération de grenaillage au moyen des vérins hydrauliques 11 et la mise en place du ressort 1 entre les plateaux 8, 12 se fait préalablement à l'introduction du rotor 5 de façon coaxiale au centre du ressort 1.The helical compression spring 1 is therefore compressed either gradually or in a single phase between the two plates 8 and 12 before or during the peening operation by means of the hydraulic cylinders 11 and the positioning of the spring 1 between the plates 8 , 12 is done prior to the introduction of the rotor 5 coaxially at the center of the spring 1.

Une fois que le ressort est amené à l'état partiellement comprimé, on effectue, selon le procédé de l'invention, le grenaillage à l'intérieur du ressort suivant toutes les directions angulaires, de telle sorte que les surfaces internes soient percutées au moins directement et perpendiculairement par ladite grenaille, c'est-à-dire suivant la normale à chacune de ces surfaces.Once the spring is brought to the partially compressed state, the blasting is carried out, according to the method of the invention, inside the spring in all the angular directions, so that the internal surfaces are struck at least directly and perpendicularly by said shot, that is to say along the normal to each of these surfaces.

Cette opération est réalisée en alimentant tout d'abord le distributeur 2 en grenaille et en mettant le rotor 5 en rotation au moyen du moteur 13.La grenaille s'écoule par gravité à l'intérieur des conduits 10, tombe à l'intérieur du ressort 1 où elle est frappée et déviée par les ailettes périphériques 6, 7 du rotor 5 en mouvement. La cinétique ultérieure de la grenaille dépend de la vitesse du rotor et du type d'ailette avec laquelle a lieu le choc.This operation is carried out by first supplying the distributor 2 with shot and by putting the rotor 5 in rotation by means of the motor 13. The shot flows by gravity inside the conduits 10, falls inside the spring 1 where it is struck and deflected by the peripheral fins 6, 7 of the moving rotor 5. The subsequent kinetics of the shot depend on the speed of the rotor and the type of fin with which the impact takes place.

Si la grenaille est frappée par une ailette 6 qui s'étend parallèlement à l'axe du rotor 5, sa trajectoire sera plutôt orientée dans une direction sensiblement horizontale.If the shot is struck by a fin 6 which extends parallel to the axis of the rotor 5, its trajectory will rather be oriented in a substantially horizontal direction.

Si la grenaille est frappée par la face supérieure d'une ailette 7, la trajectoire ultérieure de la grenaille après le choc sera orientée vers le haut.If the shot is struck by the upper face of a fin 7, the subsequent trajectory of the shot after the impact will be oriented upwards.

Au contraire, si la grenaille est frappée par la face inférieure d'une ailette 7, sa trajectoire sera orientée vers le bas.On the contrary, if the shot is struck by the underside of a fin 7, its trajectory will be oriented downwards.

Au fur et à mesure que le rotor 5 est accéléré, la proportion de grenaille frappée par les ailettes 6 augmente et on comprime alors de plus en plus le ressort 1 pour l'amener à l'état de spires presque jointives. Les surfaces internes des spires en regard du rotor 5 subissent à ce moment là un grenaillage intensif que l'on prolonge pendant une durée suffisante pour obtenir un effet sensible sur la résistance à la fatigue du ressort.As the rotor 5 is accelerated, the proportion of shot hit by the fins 6 increases and the spring 1 is then compressed more and more to bring it to the state of almost contiguous turns. The internal surfaces of the turns facing the rotor 5 are then subjected to intensive shot peening which is extended for a sufficient time to obtain a significant effect on the fatigue strength of the spring.

Ensuite on stoppe l'alimentation en grenaille, on arrête le moteur 13 et on libère le ressort 1 des moyens de compression par détente des vérins 11.Then the supply of shot is stopped, the motor 13 is stopped and the spring 1 is released from the compression means by expansion of the jacks 11.

Le grenaillage des surfaces extérieures du ressort 1 est effectué de manière connue et indépendamment du grenaillage des surfaces internes décrit ci-dessus.The shot blasting of the external surfaces of the spring 1 is carried out in a known manner and independently of the shot blasting of the internal surfaces described above.

Le procédé de grenaillage conforme à l'invention s'applique non seulement aux ressorts cylindriques en fil rond mais aussi à tous les ressorts enroulés et notamment aux ressorts coniques ou à diamètre d'enroulement variable, aux ressorts à pas variable, aux ressorts en fil conique ou à diamètre de fil variable, aux ressorts en fil carré, rectangulaire ou de section quelconque et produit des ressorts possèdant une résistance à la fatigue exceptionnelle.The shot peening process according to the invention applies not only to cylindrical springs in round wire but also to all coiled springs and in particular to conical springs or springs with variable winding diameter, to springs with variable pitch, to springs in wire conical or of variable wire diameter, with square, rectangular or any section wire springs and produces springs with resistance to exceptional fatigue.

Claims (10)

1. Dispositif pour améliorer la résistance à la fatigue d'un ressort hélicoïdal (1) de compression par grenaillage des surfaces internes dudit ressort, comprenant un distributeur de grenaille (2) et un organe mobile (3) de projection de grenaille disposé coaxialement à l'intérieur dudit ressort et des moyens de compression dudit ressort, caractérisé en ce que ledit organe mobile (3) de projection de grenaille comprend un rotor cylindrique (5) dont l'axe est sensiblement vertical pendant le grenaillage et qui est pourvu sur sa paroi latérale d'ailettes périphériques (6, 7) adaptées pour projeter la grenaille provenant du distributeur (2) contre les surfaces internes du ressort en fonction de la vitesse de rotation.1. Device for improving the fatigue resistance of a helical spring (1) for compression by shot blasting of the internal surfaces of said spring, comprising a shot distributor (2) and a movable shot projection member (3) arranged coaxially with the interior of said spring and means for compressing said spring, characterized in that said movable shot projection member (3) comprises a cylindrical rotor (5) whose axis is substantially vertical during shot blasting and which is provided on its side wall of peripheral fins (6, 7) adapted to project the shot from the distributor (2) against the internal surfaces of the spring as a function of the speed of rotation. 2. Dispositif selon la revendication 1, caractérisé en ce que ledit rotor est à vitesse variable.2. Device according to claim 1, characterized in that said rotor is at variable speed. 3. Dispositif selon les revendications 1 ou 2, caractérisé en ce que lesdites ailettes périphériques sont réparties en deux séries dont l'une (6) s'étend parallèlement à l'axe vertical dudit rotor et l'autre (7) s'étend obliquement par rapport audit axe vertical.3. Device according to claims 1 or 2, characterized in that said peripheral fins are distributed in two series, one of which (6) extends parallel to the vertical axis of said rotor and the other (7) extends obliquely to said vertical axis. 4. Dispositif selon l'une des revendications prédédentes, caractérisé en ce que ledit distributeur de grenaille comprend un plateau supérieur (8) sensiblement horizontal monté au-dessus du rotor (5) et comportant au niveau de sa partie inférieure un logement (9) adapté pour recevoir en contact d'appui l'extrémité supérieure du ressort et au moins un conduit (10) de distribution de grenaille.4. Device according to one of the preceding claims, characterized in that said shot distributor comprises an upper plate (8) substantially horizontal mounted above the rotor (5) and comprising at its lower part a housing (9) adapted to receive in contact contact with the upper end of the spring and at least one pipe (10) for distributing shot. 5. Dispositif selon l'une des revendications précédentes, caractérisé en ce que ledit rotor est mû par un moteur (13) monté coaxialement sur le plateau supérieur.5. Device according to one of the preceding claims, characterized in that said rotor is driven by a motor (13) mounted coaxially on the upper plate. 6. Procédé d'amélioration de la résistance à la fatigue d'un ressort hélicoïdal de compression comprenant notamment le grenaillage des surfaces internes du ressort caractérisé en ce que ledit grenaillage est réalisé par de la grenaille déviée et projetée à l'intérieur du ressort dans différentes directions par un rotor.6. A method of improving the fatigue strength of a helical compression spring comprising in particular the blasting of the internal surfaces of the spring characterized in that said blasting is carried out by deflected shot and projected inside the spring in different directions by a rotor. 7. Procédé selon la revendication 6, caractérisé en ce que le grenaillage est effectué à l'intérieur du ressort, de telle sorte que les surfaces internes du ressort soient percutées au moins directement et perpendiculairement par ladite grenaille.7. Method according to claim 6, characterized in that the blasting is carried out inside the spring, so that the internal surfaces of the spring are struck at least directly and perpendicularly by said shot. 8. Procédé selon la revendication 6 ou 7, caractérisé en ce que ledit ressort est comprimé progressivement pendant le grenaillage jusqu'à l'état de spires presque jointives.8. Method according to claim 6 or 7, characterized in that said spring is compressed progressively during shot peening to the state of almost contiguous turns. 9. Procédé selon la revendication 6 ou 7, caractérisé en ce que ledit ressort est maintenu comprimé pendant le grenaillage à l'état de spires presque jointives.9. Method according to claim 6 or 7, characterized in that said spring is kept compressed during shot peening in the form of almost contiguous turns. 10. Ressort hélicoïdal de compression possédant une résistance à la fatigue améliorée et obtenu par le procédé selon l'une des revendications 6 à 9.10. helical compression spring having improved fatigue resistance and obtained by the method according to one of claims 6 to 9.
EP90401744A 1989-06-20 1990-06-20 Process and device for improving the fatigue resistance of helicoidal springs under compression and springs obtained by this process Withdrawn EP0404674A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8908222 1989-06-20
FR8908222A FR2648380B1 (en) 1989-06-20 1989-06-20

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0672501A1 (en) * 1994-03-15 1995-09-20 Fried. Krupp AG Hoesch-Krupp Shot peening arrangement for helical compression springs
EP2644714A1 (en) * 2012-03-30 2013-10-02 Allevard Rejna Autosuspensions Controlled blocking apparatus of a spring and method thereof

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Publication number Priority date Publication date Assignee Title
US2249677A (en) * 1940-07-11 1941-07-15 Eaton Mfg Co Apparatus for treating coil springs
DE2616894A1 (en) * 1975-04-19 1976-10-28 Riichi Maeda CENTRIFUGAL SPIN DEVICE
JPS56107880A (en) * 1981-01-23 1981-08-27 High Frequency Heattreat Co Ltd Stress shot peening device for coil spring
JPS58192754A (en) * 1982-04-30 1983-11-10 Kato Hatsujo Kaisha Ltd Spring whose fatigue strength is processed to improve and its processing method
DE3711826A1 (en) * 1987-04-08 1988-10-27 Meuwsen & Brockhausen Method of repairing hydraulic cylinders
DE3800679A1 (en) * 1987-07-11 1989-01-19 Teves Gmbh Alfred Sealing ring for a piston-cylinder unit
JPS6471666A (en) * 1987-09-07 1989-03-16 Taiyo Chuki Kk Shot blast material shooting device

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Publication number Priority date Publication date Assignee Title
US2249677A (en) * 1940-07-11 1941-07-15 Eaton Mfg Co Apparatus for treating coil springs
DE2616894A1 (en) * 1975-04-19 1976-10-28 Riichi Maeda CENTRIFUGAL SPIN DEVICE
JPS56107880A (en) * 1981-01-23 1981-08-27 High Frequency Heattreat Co Ltd Stress shot peening device for coil spring
JPS58192754A (en) * 1982-04-30 1983-11-10 Kato Hatsujo Kaisha Ltd Spring whose fatigue strength is processed to improve and its processing method
DE3711826A1 (en) * 1987-04-08 1988-10-27 Meuwsen & Brockhausen Method of repairing hydraulic cylinders
DE3800679A1 (en) * 1987-07-11 1989-01-19 Teves Gmbh Alfred Sealing ring for a piston-cylinder unit
JPS6471666A (en) * 1987-09-07 1989-03-16 Taiyo Chuki Kk Shot blast material shooting device

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PATENT ABSTRACTS OF JAPAN vol. 13, no. 274 (M-841)(3622) 23 juin 1989, & JP-A-1 71666 (TAIYO CHUKI K.K.) 03 mars 1989, *
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PATENT ABSTRACTS OF JAPAN vol. 8, no. 35 (M-276)(1472) 15 février 1984, & JP-A-58 192754 (KATOU HATSUJIYOU K.K.) 10 novembre 1983, *
WIRE INDUSTRY. vol. 55, no. 654, juin 1988, OXTED GB Sommer: "Shot blast descaling and shot peening" *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0672501A1 (en) * 1994-03-15 1995-09-20 Fried. Krupp AG Hoesch-Krupp Shot peening arrangement for helical compression springs
EP2644714A1 (en) * 2012-03-30 2013-10-02 Allevard Rejna Autosuspensions Controlled blocking apparatus of a spring and method thereof

Also Published As

Publication number Publication date
FR2648380A1 (en) 1990-12-21
FR2648380B1 (en) 1994-10-07

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