Stress-peening - OSK Kiefer GmbH
Transcrição
Stress-peening - OSK Kiefer GmbH
Stress-peening Verfestigungsstrahlen Stress-peening O K S O K O S K unter Vorspannung Yield point of material Materialfließgrenze Yield Yield point point of of material material Compressive stress Druckspannung Compressive Compressive stress stress 0 0 0 Tensile stress Zugspannung Tensile Tensile stress stress stress by applied bending load = Vorspannung = by applied bending load = stress stress by stress appliedafter bending load resultant shot peening in induzierter the stressed condition = Resultierende aus Vorspannung und = resultant peening in durch Verfestigungsstrahlen = Druckeigenspannung resultant stress stress after after shot shot peening in the the stressed stressed condition condition = resultant stress after stress-peening in the relieved condition = resultant the = Eigenspannung resultant stress stress after after stress-peening in the relieved relieved condition condition nach stress-peening Entlastung der in Vorspannung Shot peening induces compressive residual stress in a surface layer. The distributiUnabhängig vom Spannungszustand eines Bauteiles stellt sich nach VerShot peening compressive residual stress in The distributiShot peening induces compressive residual stress in a a surface surface layer. The dem distribution and level ofinduces this residual compressive stress depends only onlayer. the material, depth festigungsstrahlen eine Druckeigenspannung in Abhängigkeit von Werkstoff on level residual stress depends on and level of of this residual compressive compressive stress layer. depends only only on on the the material, material, depth depth andand intensity of this the plastically deformed surface und Plastifizierung ein. and intensity of the plastically deformed surface layer. and intensity of the plastically deformed surface or layer. Already existing stress, produced by machining external load, has no influence on Werden Bauteilestress, betriebsund konstruktionsbedingt nur schwellend, d. influence h. nur in eiAlready produced by load, on Already existing stress, produced by machining machining or or external external load, has has no no influence on this fact.existing ner Richtung auf Zug beansprucht (z. B. Kipphebel, Federn, Zuganker, Dehnschrauthis fact. this fact.peening can be applied if parts are only loaded in one direction. Stress ben), diese Vorspannung die Bauteile Stress peening can be if are loaded in direction. Stresskönnen peening canunter be applied applied if parts partsgestrahlt are only onlywerden. loadedDabei in one onewerden direction. in geeigneten Vorrichtungen mit Betriebsspannungen elastisch bis ca. 50 % der Fließgrenzspannung belastet und adie Zugspannungsseite in diesem Zustand VerIn the stress peening process, In the stress peening process, a festigungsgestrahlt. In the stress peening process, a part is shot peened in a externalpart is shot peened in a externalpart is shotorpeened in acondition externally loaded stressed Nach der Strahlbehandlung werden die ly loaded or stressed condition ly loaded or stressed condition by using a fixture or weight toentlassiBauteile von der Vorspannung by using a or to by using the a fixture fixture or weight weighttensile to sisimulate operating tet. Dabeithe addieren sich die tensile Druckvormulate operating mulate the operating tensile stress. spannungen aus dem Verfestigungsstress. stress. After shotmit peening the parts will be strahlen den Umkehrspannungen After shot the be After shotofpeening peening the parts parts will be relieved the applied load, will which aus der elastischen Vorspannung und relieved of the applied load, which relieved ofanthe applied load, which produces even higher compresführen zu extrem hohen Druckeigenproduces an even compresproduces an stress even higher higher compressive residual upzur to the yield spannungen bis hin Fließbzw. sive residual stress up to the yield sive residual stress up to the yield stress of the material. Streckgrenze. Die Betriebsfestigkeit stress of material. stress of the thestrength material.and endurance The fatigue dieser Bauteile reagiert entsprechend. The fatigue strength and The fatigue strength and endurance endurance limit are modified accordingly. limit are modified accordingly. limit are modified accordingly. Rocker arm in a Ventilkipphebel einer arm a Rocker arm in inin a fixture toggle Rocker lever prestress Kniehebelvorspannvorrichtung toggle toggle lever lever prestress prestress fixture fixture 62 63 63 Stress-peening O SOKS KStress-peening LeafLeaf spring, spring, decarburized decarburized [ % Rm [% ] Rm ] + 40 + 40 0 0 - 20 - 20 - 40 - 40 - 60 - 60 - 80 - 80 Residual stress Residual stress + 20 + 20 [%] [%] 240 240 220 220 200 200 180 180 160 160 140 140 120 120 100 100 Bending stress Bending stress 0 80 10 0 0.1 0.1 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.6 0.6[mm] [mm] Distance Distance from from surface surface 80 4 104 105 105 106 106 107 107 108 108 Cycles Cycles = not shot = notpeened shot peened = shot=peened shot peened (normal) (normal) = stress-peened = stress-peened ( externally ( externally loadedloaded with about with about 50% of50% Rmof ) Rm ) 64 64 63