These seven tricks can effectively solve the common defects in mold processing

Time:2020/7/13 11:04:51

　　 2. The mold processing uses the cooling lubricant reasonably, plays the three major roles of cooling, washing and lubrication, keeps the cooling lubrication clean, so as to control the grinding heat within the allowable range to prevent the workpiece from thermal deformation. Improve the cooling conditions during grinding, such as the use of oil-immersed grinding wheels or internal cooling grinding wheels. Introduce the cutting fluid into the center of the grinding wheel, the cutting fluid can directly enter the grinding area, and play an effective cooling role to prevent burns on the surface of the workpiece.
　　 3. The quenching stress after heat treatment is reduced to the minimum, because the quenching stress and the meshed carbon structure are under the action of the grinding force, and the phase change of the structure is very easy to crack the workpiece. For precision molds, in order to eliminate the residual stress of grinding, low temperature aging treatment should be carried out after grinding to improve toughness.
　　 4. To eliminate grinding stress, the mold can also be immersed in a salt bath at 260~315°C for 1.5min, and then cooled in 30°C oil, so that the hardness can be reduced by 1HRC and the residual stress can be reduced by 40%~65%.
　　 5. For precision grinding of precision molds with dimensional tolerance within 0.01mm, attention should be paid to the influence of ambient temperature, and constant temperature grinding is required. It can be seen from the calculation that when a 300mm long steel part has a temperature difference of 3℃, the material has a change of about 10.8μm, (10.8=1.2×3×3, the amount of deformation per 100mm is 1.2μm/℃), and each finishing process needs to be fully considered The influence of this factor.
　　 6. Adopt electrolytic grinding process to improve mold manufacturing precision and surface quality. During electrolytic grinding, the grinding wheel scrapes off the oxide film: instead of grinding the metal, the grinding force is small and the grinding heat is also small, and there will be no grinding burrs, cracks, burns and other phenomena. The general surface roughness can be better than Ra0 .16μm; In addition, the wear of the grinding wheel is small, such as grinding cemented carbide, the wear amount of the silicon carbide grinding wheel is about 400% to 600% of the weight of the cemented carbide. When using electrolytic grinding, the wear of the grinding wheel The amount is only 50% to 100% of the amount of carbide removal.
　　 7. Choose the amount of grinding reasonably, and use the fine grinding method with even smaller radial feed or even fine grinding. If the radial feed rate and the grinding wheel speed are appropriately reduced, the axial feed rate is increased, so that the contact area between the grinding wheel and the workpiece is reduced, and the heat dissipation conditions are improved, thereby effectively controlling the increase in the surface temperature.