In order to improve the performance of the Crate Mould, many manufacturers will properly process the crate mould, but in many cases, the processing of the crate mould will also reflect the processing defects, resulting in the performance of the crates. How to build creat mould processing defects? The following seven measures can be used to construct crates mould processing defects.
1. Reasonable selection and dressing of the grinding wheel. In the grinding process, it is necessary to pay attention to dressing the grinding wheel in time to keep the grinding wheel sharp. When the grinding wheel is passivated, it will slide and squeeze on the surface of the workpiece, causing the surface of the workpiece to burn and the strength is reduced. Choose a grinding wheel with coarse grain size and low hardness, which can reduce the heat of cutting by self-excitation.
2. For precision grinding of precision moulds with a dimensional tolerance of 0.01 mm or less, pay attention to the influence of ambient temperature and require constant temperature grinding.
3. Reasonable use of cooling lubricants, play the three major functions of cooling, washing and lubrication, keep the cooling and lubrication clean, and thus control the grinding heat within the allowable range to prevent thermal deformation of the workpiece. Improve the cooling conditions during grinding, such as the use of oil-impregnated grinding wheels or internal cooling wheels. The cutting fluid is introduced into the centre of the grinding wheel, and the cutting fluid can directly enter the grinding zone to exert an effective cooling effect to prevent the surface of the workpiece from being burned.
4. Eliminate the grinding stress. The mould can also be immersed in a 260-315 ° C salt bath for 1.5 min, and then cooled in 30 ° C oil, so that the hardness can be reduced by 1 HRC, and the residual stress is reduced by 40% to 65%.
5. Using electrolytic grinding to improve mould manufacturing accuracy and surface quality. In electrolytic grinding, the grinding wheel scrapes off the oxide film: instead of grinding the metal, the grinding force is small, the grinding heat is small, and no grinding burrs, cracks, burns, etc. occur.
6. Reasonable choice of grinding amount, a fine grinding method with small radial feed rate and even fine grinding. If the radial feed amount and the grinding wheel speed are appropriately reduced, the axial feed amount is increased, the contact area between the grinding wheel and the workpiece is reduced, and the heat dissipation condition is improved, thereby effectively controlling the surface temperature increase.
7. The quenching stress after heat treatment is reduced to a minimum because the quenching stress and the reticulated carbonized structure under the action of the grinding force, the phase change of the structure is very easy to cause cracks in the workpiece. For high-precision moulds, in order to eliminate the residual stress of grinding, low-temperature ageing treatment should be performed after grinding to improve the toughness.
