Worm is a significant piece of machine apparatus turning parts. Worm bending surface and worm gear tooth surface slip for the most part when working, which is easy to wear.Thusly, the worm will typically carburizing extinguishing treatment to get higher hardness to forestall worm winding surface wear. Worm parts require high accuracy, so the handling innovation is perplexing and long. Assuming that there is any issue during handling, it will cause enormous misfortune. A kind of worm parts in our association appeared to be smashing breaks during pounding, achieving parts dismissed, really affecting the creation plan.
Worm material and fundamental cycle stream
The worm material is 20CrMnTiH and the hotness treatment requires carburizing and quenching with a significance of 1.1-1.5mm and a surface hardness of 58HRC ensuing to stifling.
Blanking→Forging→Normalizing→Rough machining→Stress relieve→Fine machining→carburizing→Carbon eliminate on the thread→Quenching→Rough grinding→Test→Aging→Fine crushing
Heat treatment process: Forging normalizing→ Carburizing →Quenching →Low temperature treating →Straightening→Stress relief→Low temperature maturing.
In the wake of carburizing and extinguishing, the carburized profundity layer is 1.32mm and the surface hardness is 59 to 60HRC.
Break peculiarity portrayal
Later harsh crushing, the break shows up on the tooth surface of the worm. The breaks are exceptionally fine, direct and shallow inside and out. The condition of the breaks is by and large called "hairline". The breaks are not equivalent and dispersing lines.
Examination of crushing breaks
It is clearly not the same as normal extinguishing breaks. The extinguishing breaks are thick and profound, and the quantity of breaks is little. It just happens on the crushing surface, and the number is huge, the profundity is shallow, yet the profundity is essentially something very similar. The lighter ones are stripe breaks opposite to or almost opposite to the crushing heading. The worm tooth surface is a bending surface.
In the devastating arrangement of hotness treated parts, the fast high temperature in the devastating zone can reach 400-1500 ℃ considering the way that the devastating wheel isgruff, the crushing profundity is too profound and the cooling is inadequate. Subsequently, the crushing consume happen, bringing about the progressions of surface microstructure, microhardness, remaining pressure and mechanical properties of the parts.
The development of breaks is identified with the hardness of the workpiece. Albeit the workpiece with hardness under 55HRC might be singed, the event of crushing breaks is uncommon. The workpiece with hardness above 60HRC will enormously expand the chance of break. The deliberate hardness of the part is 59 ~ 60HRC, which significantly builds the inclination of crushing breaks. From one perspective, when crushing conditions are inappropriate or crushing isn't standard, crushing surface will initially shape a solid consume focus, bringing about lopsided warm pressure. In substitute high temperature and quick cooling, the pressure esteem step by step expanded. At the point when the pressure surpasses the material strength limit, the crushed surface will create breaks. Then again, the held austenite in the surface carburized and extinguished construction will be changed into new martensite by the impact of exceptional crushing hotness and the cooling of coolant during crushing, which will cause the neighborhood volume extension on the outer layer of the part, expanding the pliable weight on the outer layer of the part and lead to pressure fixation. Predictable smashing will conveniently accelerate the devastating break age.
From the above investigation, we realize that the underlying driver of crushing breaks lies in the presence of stress. To forestall this peculiarity, it is important to lessen and take out different weights on the outer layer of parts.
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