Worm is an important Portion of device Resource rotating pieces. Worm spiral area and worm equipment tooth floor slip fairly when Functioning, and that is easy to don. For that reason, the worm will usually carburizing quenching treatment to get greater hardness to forestall worm spiral area put on. Worm pieces require higher precision, Therefore the processing technology is intricate and long. When there is any trouble through processing, it can trigger large loss. A kind of worm sections inside our enterprise appeared grinding cracks during grinding, leading to elements scrapped, critically influencing the generation agenda.
1. Worm material and major approach flow
The worm material is 20CrMnTiH and the warmth treatment method needs carburizing and quenching that has a depth of 1.one-one.5mm along with a surface hardness of 58HRC immediately after quenching.
Blanking→Forging→Normalizing→Tough machining→Worry reduce→Great machining→carburizing→Carbon get rid of around the thread→Quenching→Tough grinding→Examination→Growing older→Wonderful grinding
Warmth treatment method approach: Forging normalizing→ Carburizing →Quenching →Minimal temperature tempering →Straightening→Tension aid→Very low temperature getting older.
Following carburizing and quenching, the carburized depth layer is one.32mm along with the surface hardness is fifty nine to 60HRC.
2. Crack phenomenon description
Immediately after rough grinding, the crack seems within the tooth floor with the worm. The cracks are really fantastic, linear and shallow in depth. The shape in the cracks is often referred to as "hairline". The cracks are not parallel and scattering lines.
3. Examination of grinding cracks
It is clearly various from widespread quenching cracks. The quenching cracks are thick and deep, and the volume of cracks is smaller. It only happens about the grinding floor, as well as selection is big, the depth is shallow, even so the depth is essentially precisely the same. The lighter ones are stripe cracks perpendicular to or approximately perpendicular to your grinding route. The worm tooth surface is often a spiral surface area.
Inside the grinding strategy of warmth-addressed components, the instantaneous higher temperature within the grinding zone can reach four hundred-1500 ℃ as the grinding wheel is blunt, the grinding depth is simply too deep plus the cooling is insufficient. Consequently, the grinding melt away arise, resulting in the variations of area microstructure, microhardness, residual anxiety and mechanical Qualities on the components.
The formation of cracks is linked to the hardness in the workpiece. Although the workpiece with hardness under 55HRC could be burned, the event of grinding cracks is scarce. The workpiece with hardness previously mentioned 60HRC will tremendously improve the potential for crack. The measured hardness of the element is fifty nine ~ 60HRC, which considerably boosts the tendency of grinding cracks. Over the just one hand, when grinding conditions are incorrect or grinding is not really normal, grinding floor will firstly form a read more powerful burn up Heart, causing uneven thermal anxiety. In alternate superior temperature and quick cooling, the strain price step by step amplified. Once the strain exceeds the fabric toughness Restrict, the grinded area will produce cracks. However, the retained austenite in the area carburized and quenched structure will be reworked into new martensite with the affect of intensive grinding heat as well as the cooling of coolant for the duration of grinding, that will cause the local quantity growth within the surface area of your element, growing the tensile worry about the floor in the component and bring on tension focus. Constant grinding will effortlessly speed up the grinding crack era.